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1

Excitation energy after a smooth quench in a Luttinger liquid  

SciTech Connect

Low-energy physics of quasi-one-dimensional ultracold atomic gases is often described by a gapless Luttinger liquid (LL). It is nowadays routine to manipulate these systems by changing their parameters in time but, no matter how slow the manipulation is, it must excite a gapless system. We study a smooth change of parameters of the LL (a smooth ''quench'') with a variable quench time and find that the excitation energy decays with an inverse power of the quench time. This universal exponent is -2 at zero temperature and -1 for slow enough quenches at finite temperature. The smooth quench does not excite beyond the range of validity of the low-energy LL description.

Dziarmaga, Jacek; Tylutki, Marek [Institute of Physics and Center for Complex Systems Research, Jagiellonian University, Reymonta 4, PL-30-059 Krakow (Poland)

2011-12-01

2

Luttinger Model and Luttinger Liquids  

NASA Astrophysics Data System (ADS)

The Luttinger model owes its solvability to a number of peculiar features, like its linear relativistic dispersion relation, which are absent in more realistic fermionic systems. Nevertheless according to the Luttinger liquid conjecture a number of relations between exponents and other physical quantities, which are valid in the Luttinger model, are believed to be true in a wide class of systems, including tight binding or jellium one-dimensional fermionic systems. Recently a rigorous proof of several Luttinger liquid relations in nonsolvable models has been achieved; it is based on exact Renormalization Group methods coming from Constructive Quantum Field Theory and its main steps will be reviewed below.

Mastropietro, Vieri

2014-10-01

3

Ballistic thermoelectric transport in a Luttinger liquid.  

PubMed

The Seebeck and Peltier coefficients of a homogeneous Luttinger liquid are calculated in the ballistic regime. Nonlinearity of the electron spectrum is taken into account. It is shown that, in the framework of the defined approximations, the thermoelectric power of a Luttinger liquid is equal to zero, in agreement with the exponentially small thermopower of a one-dimensional degenerate Fermi gas. The Peltier coefficient is controlled by a nonequilibrium state of the system. It is finite and renormalized by the interaction in the case of a convective flow of a Luttinger liquid. The zero modes of bosonic excitations and the dispersion-induced contribution to the electric current operator are taken into account in calculations. PMID:21393787

Ivanov, Y V

2010-06-23

4

Detection of entanglement by helical Luttinger liquids  

NASA Astrophysics Data System (ADS)

A Cooper-pair or electron-hole splitter is a device capable of spatially separating entangled fermionic quasiparticles into mesoscopic solid-state systems such as quantum dots or quantum wires. We theoretically study such a splitter based on a pair of helical Luttinger liquids, which arise naturally at the edges of a quantum spin Hall insulator. Equipping each helical liquid with a beam splitter, current-current cross correlations can be used to construct a Bell inequality whose violation would indicate nonlocal orbital entanglement of the injected electrons and/or holes. Due to the Luttinger-liquid correlations, however, the entanglement is suppressed depending on ambient temperature and voltage bias.

Sato, Koji; Tserkovnyak, Yaroslav

2014-07-01

5

Compressible Strips, Chiral Luttinger Liquids, and All That Jazz  

NASA Astrophysics Data System (ADS)

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.

MacDonald, A. H.

1996-03-01

6

Luttinger liquid theory as a model of the gigahertz electrical properties of carbon nanotubes  

Microsoft Academic Search

Presents a technique to directly excite Luttinger liquid collective modes in carbon nanotubes at gigahertz frequencies. By modeling the nanotube as a nano-transmission line with distributed kinetic and magnetic inductance as well as distributed quantum and electrostatic capacitance, we calculate the complex frequency-dependent impedance for a variety of measurement geometries. Exciting voltage waves on the nano-transmission line is equivalent to

P. J. Burke

2002-01-01

7

a Luttinger Liquid Core Inside HELIUM-4 Filled Nanopores  

NASA Astrophysics Data System (ADS)

As helium-4 is cooled below 2.17 K it undergoes a phase transition to a fundamentally quantum mechanical state of matter known as a superfluid which supports flow without viscosity. This type of dissipationless transport can be observed by forcing helium to travel through a narrow constriction that the normal liquid could not penetrate. Recent experiments have highlighted the feasibility of fabricating smooth pores with nanometer radii, that approach the truly one-dimensional limit where it is believed that a system of bosons (like helium-4) may have startlingly different behavior than in three dimensions. The one-dimensional system is predicted to have a linear hydrodynamic description known as Luttinger liquid (LL) theory, where no type of long range order can be sustained. In the limit where the pore radius is small, LL theory would predict that helium inside the channel behaves as a sort of quasi-supersolid with all correlations decaying as power-law functions of distance at zero temperature. We have performed large scale quantum Monte Carlo simulations of helium-4 inside nanopores of varying radii at low temperature with realistic helium.helium and helium-pore interactions. The results indicate that helium inside the nanopore forms concentric cylindrical shells surrounding a core that can be described via LL theory and provides insights into the exciting possibility of the experimental detection of this intriguing low-dimensional state of matter.

Del Maestro, Adrian

2014-10-01

8

Luttinger Liquid in Non-equilibrium Steady State  

E-print Network

We propose and investigate an exactly solvable model of non-equilibrium Luttinger liquid on a star graph, modeling a multi-terminal quantum wire junction. The boundary condition at the junction is fixed by an orthogonal matrix S, which describes the splitting of the electric current among the leads. The system is driven away from equilibrium by connecting the leads to heat baths at different temperatures and chemical potentials. The associated non-equilibrium steady state depends on S and is explicitly constructed. In this context we develop a non-equilibrium bosonization procedure and compute some basic correlation functions. Luttinger liquids with general anyon statistics are considered. The relative momentum distribution away from equilibrium turns out to be the convolution of equilibrium anyon distributions at different temperatures. Both the charge and heat transport are studied. The exact current-current correlation function is derived and the zero-frequency noise power is determined.

Mihail Mintchev; Paul Sorba

2012-10-19

9

Attractive Tomonaga-Luttinger Liquid in a Quantum Spin Ladder  

NASA Astrophysics Data System (ADS)

We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1?T1/2K-1, which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1Luttinger liquid.

Jeong, M.; Mayaffre, H.; Berthier, C.; Schmidiger, D.; Zheludev, A.; Horvati?, M.

2013-09-01

10

Spontaneously magnetized Tomonaga-Luttinger liquid in frustrated quantum antiferromagnets  

NASA Astrophysics Data System (ADS)

We develop a theory of spontaneously magnetized Tomonaga-Luttinger (TLL) liquid in geometrically frustrated quasi-one-dimensional quantum magnets by taking an S =1/2 ferrimagnet on a union-jack lattice as an example. We show that a strong frustration leads to a spontaneous magnetization because of the ferrimagnetic nature of lattice. Due to the ferrimagnetic order, the local magnetization has an incommensurate oscillation with the position. We show that the spontaneously magnetized TLL is smoothly connected to the existence of a Nambu-Goldstone boson in the canted ferrimagnetic phase of a two-dimensional frustrated antiferromagnet.

Furuya, Shunsuke C.; Giamarchi, Thierry

2014-05-01

11

Quantum Hall Edge Physics and its One-Dimensional Luttinger Liquid Description  

NASA Astrophysics Data System (ADS)

We describe the relationship between quantum Hall edge states and the one-dimensional Luttinger liquid model. The Luttinger liquid model originated from studies of one-dimensional Fermi systems, however, it results that many ideas inspired by such a model can find applications to phenomena occurring even in higher dimensions. Quantum Hall systems which essentially are correlated two-dimensional electronic systems in a strong perpendicular magnetic field have an edge. It turns out that the quantum Hall edge states can be described by a one-dimensional Luttinger model. In this work, we give a general background of the quantum Hall and Luttinger liquid physics and then point out the relationship between the quantum Hall edge states and its one-dimensional Luttinger liquid representation. Such a description is very useful given that the Luttinger liquid model has the property that it can be bosonized and solved. The fact that we can introduce a simpler model of noninteracting bosons, even if the quantum Hall edge states of electrons are interacting, allows one to calculate exactly various quantities of interest. One such quantity is the correlation function which, in the asymptotic limit, is predicted to have a power law form. The Luttinger liquid model also suggests that such a power law exponent should have a universal value. A large number of experiments have found the quantum Hall edge states to show behavior consistent with a Luttinger liquid description. However, while a power law dependence of the correlation function has been observed, the experimental values of the exponent appear not to be universal. This discrepancy might be due to various correlation effects between electrons that sometimes are not easy to incorporate within a standard Luttinger liquid model.

Ciftja, Orion

2014-10-01

12

Rectification in Y-junctions of Luttinger liquid wires  

NASA Astrophysics Data System (ADS)

We investigate rectification of a low-frequency ac bias in Y-junctions of one-channel Luttinger liquid wires with repulsive electron interaction. Rectification emerges due to three scatterers in the wires. We find that it is possible to achieve a higher rectification current in a Y-junction than in a single wire with an asymmetric scatterer at the same interaction strength and voltage bias. The rectification effect is the strongest in the absence of the time-reversal symmetry. In that case, the maximal rectification current can be comparable with the total current ˜e^2V/h even for low voltages, weak scatterers and modest interaction strength. In a certain range of low voltages, the rectification current can grow as the voltage decreases. This leads to a bump in the I-V curve.[4pt] [1] Chenjie Wang and D. E. Feldman, Phys. Rev. B 83, 045302 (2011).

Wang, Chenjie; Feldman, D. E.

2012-02-01

13

Anomalous chiral Luttinger liquid behavior of diluted fractionally charged quasiparticles  

NASA Astrophysics Data System (ADS)

Fractionally charged quasiparticles in edge states, are expected to condense to a chiral Luttinger liquid (CLL). We studied their condensation by measuring the conductance and shot noise due to an artificial backscatterer embedded in their path. At sufficiently low-temperatures backscattering events were found to be strongly correlated, producing a highly nonlinear current-voltage characteristic and a nonclassical shot noise—both are expected in a CLL. When, however, the impinging beam of quasiparticles was made dilute, either artificially via an additional weak backscatterer or by increasing the temperature, the resultant outgoing noise was classical, indicating the scattering of independent quasiparticles. Here, we study in some detail this surprising crossover from correlated particle behavior to an independent behavior, as a function of beam dilution and temperature.

Chung, Y. C.; Heiblum, M.; Oreg, Y.; Umansky, V.; Mahalu, D.

2003-05-01

14

Pumping current of a Luttinger liquid with finite length  

E-print Network

We study transport properties in a Tomonaga-Luttinger liquid in the presence of two time-dependent point like weak impurities, taking into account finite-length effects. By employing analytical methods and performing a perturbation theory, we compute the backscattering pumping current (I_bs) in different regimes which can be established in relation to the oscillatory frequency of the impurities and to the frequency related to the length and the renormalized velocity (by the electron-electron interactions) of the charge density modes. We investigate the role played by the spatial position of the impurity potentials. We also show how the previous infinite length results for I_bs are modified by the finite size of the system.

Sebastián Franchino Viñas; Pablo Pisani; Mariano Salvay

2012-03-16

15

Luttinger Liquid, Singular Interaction and Quantum Criticality in Cuprate Materials  

NASA Astrophysics Data System (ADS)

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.

di Castro, C.; Caprara, S.

2014-10-01

16

Emergent ``super-solitons'' following an interaction strength quantum quench across a Luttinger liquid-Mott insulating phase boundary  

NASA Astrophysics Data System (ADS)

Rapid progress in cold atom experiments has motivated the study of non-equilibrium many-body dynamics following a sudden deformation of the system Hamiltonian (a ``quantum quench''). Here, we consider the dynamics of localized excitations produced via a quench across a quantum phase boundary separating critical Luttinger liquid and gapped Mott insulating states. Our initial liquid ground state is labeled by a Luttinger interaction parameter K, and subject to a density-inhomogeneity forming external potential. For the Mott insulator, we employ the quantum Sine Gordon model at the Luther-Emery (LE) point. We find that over a wide range of initial K values, the quench induces the production of relativistic, non-dispersive traveling density waves, which we dub ``super-solitons.'' The super-solitons are generated from generic antecedent localized density lumps, and appear to be a robust feature of the post-quench dynamics. An isolated exception occurs for the case of K = KLE; here, the density dynamics are generically dispersive, and depend sensitively upon the shape of the initial inhomogeneity. We show that the super-solitons do not interact, and we demonstrate that an inhomogeneous Luttinger parameter K can be used to produce super-solitons with different characteristics in the same system.

Foster, Matthew; Yuzbashyan, Emil

2010-03-01

17

Luttinger-Liquid Behavior in Weakly Disordered Quantum Wires E. Levy,1,* A. Tsukernik,2  

E-print Network

Luttinger-Liquid Behavior in Weakly Disordered Quantum Wires E. Levy,1,* A. Tsukernik,2 M-liquid model, in the limit of weakly disordered wires. We show that, for the relatively low level of disorderAs. However, samples with a higher level of disorder show conductance with stronger temperature dependence

Palevski, Alexander

18

Scaling of temporal correlations in an attractive Tomonaga-Luttinger spin liquid  

NASA Astrophysics Data System (ADS)

We report temperature-dependent neutron scattering measurements of the local dynamic structure factor in the quantum spin ladder (C7H10N) 2CuBr4 in a magnetic field H =9 T, in its gapless quantum-critical phase. We show that the measured quantity has a scaling form consistent with expectations for a Tomonaga-Luttinger liquid with attraction. The measured Luttinger parameter K ?1.25 and scaling function are in excellent agreement with density matrix renormalization group numerical calculations for the underlying spin Hamiltonian.

Povarov, K. Yu.; Schmidiger, D.; Reynolds, N.; Bewley, R.; Zheludev, A.

2015-01-01

19

Real Space Imaging of One-Dimensional Standing Waves: Direct Evidence for a Luttinger Liquid  

E-print Network

Real Space Imaging of One-Dimensional Standing Waves: Direct Evidence for a Luttinger Liquid, Nagoya 464-8602, Japan (Received 28 January 2004; published 14 October 2004) Electronic standing waves tunneling spectroscopy. The observed two standing waves caused by separate spin and charge bosonic

Eggert, Sebastian

20

Crossover from Fermi liquid to multichannel Luttinger liquid in high-mobility quantum wires.  

PubMed

We investigate the electrical conductance of long, high-mobility quantum wires formed by the split-gate technique, which allows for adjustment of the wire width and the number of one-dimensional electron subbands, n. In wires with 3liquid to a multichannel Luttinger liquid. PMID:20366730

Bell, M; Sergeev, A; Bird, J P; Mitin, V; Verevkin, A

2010-01-29

21

Luttinger liquid behavior in the alternating spin-chain system copper nitrate  

NASA Astrophysics Data System (ADS)

We determine the phase diagram of copper nitrate Cu(NO3) 2.2.5 D2O in the context of quantum phase transitions and novel states of matter. We establish this compound as an ideal candidate to study quasi-1D Luttinger liquids, 3D Bose-Einstein-Condensation of triplons, and the crossover between 1D and 3D physics. Magnetocaloric effect, magnetization, and neutron scattering data provide clear evidence for transitions into a Luttinger liquid regime and a 3D long-range ordered phase as a function of field and temperature. Theoretical simulations of this model material allow us to fully establish the phase diagram and to discuss it in the context of dimerized spin systems.

Willenberg, B.; Ryll, H.; Kiefer, K.; Tennant, D. A.; Groitl, F.; Rolfs, K.; Manuel, P.; Khalyavin, D.; Rule, K. C.; Wolter, A. U. B.; Süllow, S.

2015-02-01

22

Universality of One-Dimensional Fermi Systems, II. The Luttinger Liquid Structure  

NASA Astrophysics Data System (ADS)

We complete the proof started in Benfatto et al. (2014) of the universal Luttinger liquid relations for a general model of spinning fermions on a lattice, by making use of the Ward identities due to asymptotically emerging symmetries. This is done by introducing an effective model verifying extra symmetries and by relating its critical exponents to those of the fermion lattice gas by suitable fine tuning of the parameters.

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

2014-08-01

23

Universal transport signatures of Majorana fermions in superconductor-Luttinger liquid junctions  

NASA Astrophysics Data System (ADS)

One of the most promising proposals for engineering topological superconductivity and Majorana fermions employs a spin-orbit coupled nanowire subjected to a magnetic field and proximate to an s-wave superconductor. When only part of the wire's length contacts to the superconductor, the remaining conducting portion serves as a natural lead that can be used to probe these Majorana modes via tunneling. The enhanced role of interactions in one dimension dictates that this configuration should be viewed as a superconductor-Luttinger liquid junction. We investigate such junctions between both helical and spinful Luttinger liquids, and topological as well as nontopological superconductors. We determine the phase diagram for each case and show that universal low-energy transport in these systems is governed by fixed points describing either perfect normal reflection or perfect Andreev reflection. In addition to capturing (in some instances) the familiar Majorana-mediated “zero-bias anomaly” in a new framework, we show that interactions yield dramatic consequences in certain regimes. Indeed, we establish that strong repulsion removes this conductance anomaly altogether while strong attraction produces dynamically generated effective Majorana modes even in a junction with a trivial superconductor. Interactions further lead to striking signatures in the local density of states and the line shape of the conductance peak at finite voltage, and also are essential for establishing smoking-gun transport signatures of Majorana fermions in spinful Luttinger liquid junctions.

Fidkowski, Lukasz; Alicea, Jason; Lindner, Netanel H.; Lutchyn, Roman M.; Fisher, Matthew P. A.

2012-06-01

24

Quantum impurity in a Tomonaga-Luttinger liquid: Continuous-time quantum Monte Carlo approach  

NASA Astrophysics Data System (ADS)

We develop a continuous-time quantum Monte Carlo (CTQMC) method for quantum impurities coupled to interacting quantum wires described by a Tomonaga-Luttinger liquid. The method is negative-sign free for any values of the Tomonaga-Luttinger parameter, which is rigorously proved, and, thus, efficient low-temperature calculations are possible. Duality between electrons and bosons in one-dimensional systems allows us to construct a simple formula for the CTQMC algorithm in these systems. We show that the CTQMC for Tomonaga-Luttinger liquids can be implemented with only minor modifications of previous CTQMC codes developed for impurities coupled to noninteracting fermions. We apply this method to the Kane-Fisher model of a potential scatterer in a spin-less quantum wire and to a single spin coupled with the edge state of a two-dimensional topological insulator assuming an anisotropic XXZ coupling. Various dynamical response functions such as the electron Green's function and spin-spin correlation functions are calculated numerically and their scaling properties are discussed.

Hattori, K.; Rosch, A.

2014-09-01

25

Particle-Hole Symmetric Luttinger Liquids in a Quantum Hall Circuit  

NASA Astrophysics Data System (ADS)

We report current transmission data through a split-gate constriction fabricated onto a two-dimensional electron system in the integer quantum Hall (QH) regime. Split-gate biasing drives interedge backscattering and is shown to lead to suppressed or enhanced transmission, in marked contrast to the expected linear Fermi-liquid behavior. This evolution is described in terms of particle-hole symmetry and allows us to conclude that an unexpected class of gate-controlled particle-hole-symmetric chiral Luttinger liquids (CLLs) can exist at the edges of our QH circuit. These results highlight the role of particle-hole symmetry on the properties of CLL edge states.

Roddaro, Stefano; Pellegrini, Vittorio; Beltram, Fabio; Pfeiffer, Loren N.; West, Ken W.

2005-10-01

26

Tomonaga Luttinger liquid feature in sodium-doped quasi-one-dimensional trans-polyacetylene chain  

NASA Astrophysics Data System (ADS)

We employ density functional theoretical calculation to establish Tomonaga-Luttinger liquid (TLL) behavior of sodium-doped quasi-one-dimensional trans-polyacetylene chain. A study of density of states near the Fermi energy demonstrates power-law dependence at doping concentrations 8.3%, 10.0% and 12.5%. The existence of power-law behavior in density of states is the signature of TLL behavior. Related power-law scaling factors are calculated from the slopes of logarithmic density of states versus logarithmic energy relative to Fermi energy plot. Asymptotic variation of density-density correlation function also confirms the appearance of TLL.

Sen, Sabyasachi; Chakrabarti, Swapan

2008-06-01

27

Junctions of spin-incoherent Luttinger liquids with ferromagnets and superconductors  

NASA Astrophysics Data System (ADS)

We discuss the properties of a strongly interacting spin-charge separated one-dimensional system coupled to ferromagnets and/or superconductors. Our results are valid for arbitrary temperatures with respect to the spin energy, but require that temperature be small compared to the charge energy. We focus mainly on the spin-incoherent regime where temperature is large compared to the spin energy, but small compared to the charge energy. In the case of a ferromagnet we study spin pumping and the renormalized dynamics of a precessing magnetic order parameter. We find that the interaction-dependent temperature dependence of the spin pumping can be qualitatively different in the spin-incoherent regime from the Luttinger liquid regime, allowing an identification of the former. Likewise, the temperature dependence of the renormalized magnetization dynamics can be used to identify spin-incoherent physics. For the case of a spin-incoherent Luttinger liquid coupled to two superconductors, we compute the ac and dc Josephson currents for a wire geometry in the limit of tunnel coupled superconductors. Both the ac and dc responses contain “smoking gun” signatures that can be used to identify spin-incoherent behavior. Experimental requirements for the observation of these effects are laid out.

Tilahun, Dagim; Fiete, Gregory A.

2009-03-01

28

arXiv:cond-mat/0703101v2[cond-mat.str-el]3Jun2007 The Luttinger liquid kink  

E-print Network

arXiv:cond-mat/0703101v2[cond-mat.str-el]3Jun2007 The Luttinger liquid kink Trinanjan Datta,1 E. W: October 6, 2007) Spin-charge separation in the one dimensional electron gas should give rise to two peaks resolution can suppress the spin peak. Nevertheless, a telltale kink in the dispersion remains

Hu, Jiangping

29

Particle-hole symmetric Luttinger liquids in a quantum Hall circuit.  

PubMed

We report current transmission data through a split-gate constriction fabricated onto a two-dimensional electron system in the integer quantum Hall (QH) regime. Split-gate biasing drives interedge backscattering and is shown to lead to suppressed or enhanced transmission, in marked contrast to the expected linear Fermi-liquid behavior. This evolution is described in terms of particle-hole symmetry and allows us to conclude that an unexpected class of gate-controlled particle-hole-symmetric chiral Luttinger liquids (CLLs) can exist at the edges of our QH circuit. These results highlight the role of particle-hole symmetry on the properties of CLL edge states. PMID:16241751

Roddaro, Stefano; Pellegrini, Vittorio; Beltram, Fabio; Pfeiffer, Loren N; West, Ken W

2005-10-01

30

Quantum impurity in a Luttinger liquid: Universal conductance with entanglement renormalization  

NASA Astrophysics Data System (ADS)

We study numerically the universal conductance of Luttinger-liquid wire with a single impurity via the multiscale entanglement renormalization ansatz (MERA). The scale-invariant MERA provides an efficient way to extract scaling operators and scaling dimensions for both the bulk and the boundary conformal field theories. By utilizing the key relationship between the conductance tensor and ground-state correlation function, the universal conductance can be evaluated within the framework of the boundary MERA. We construct the boundary MERA to compute the correlation functions and scaling dimensions for the Kane-Fisher fixed points by modeling the single impurity as a junction (weak link) of two interacting wires. We show that the universal behavior of the junction can be easily identified within the MERA and argue that the boundary MERA framework has tremendous potential to classify the fixed points in general multiwire junctions.

Lo, Ya-Lin; Hsieh, Yun-Da; Hou, Chang-Yu; Chen, Pochung; Kao, Ying-Jer

2014-12-01

31

Particle-hole symmetry and Luttinger liquids in a quantum Hall circuit  

NASA Astrophysics Data System (ADS)

I shall present recent experimental results on edge-state transport through quantum point contacts in the quantum Hall (QH) regime. Finite-bias backscattering measurements between edge channels at filling factor ?=1 will be presented at different temperatures. Transport through the constriction displays a non-linear Luttinger-like behavior even in the integer QH regime in contrast with the linear tunneling predicted for integer edge states [1,2]. Both zero-bias enhancement and suppression of the inter-edge tunneling will be shown in a controllable way as a function of gate bias [2,3,4]. The observed evolution is connected to the local charge depletion in the constriction region and offers new insight into the link between QH charge-conjugation and Luttinger liquid description of edge channels [2]. I shall discuss the relevance of these experimental results in the context of the dynamics of the highly-correlated edge channels in the fractional QH regime [5]. Finally I shall demonstrate how charge-conjugation can be exploited in the design of new QH circuits where the transport properties of the hole component of a partially filled Landau level can be directly addressed. [1] X.-G. Wen, Phys. Rev. Lett. 62, 2206 (1990); P. Fendley et al. Phys. Rev. Lett. 74, 3005 (1995). [2] S. Roddaro, V. Pellegrini, F. Beltram, L. N. Pfeiffer, K. W. West, Phys. Rev. Lett. 95, 156804 (2005). [3] S. Roddaro, V. Pellegrini, F. Beltram, G. Biasiol, L. Sorba., Phys. Rev. Lett. 93, 046801 (2004). [4] S. Roddaro, V. Pellegrini, F. Beltram, G. Biasiol, L. Sorba, R. Raimondi, G. Vignale, Phys. Rev. Lett. 90, 046805 (2003). [5] A. M. Chang, Rev. Mod. Phys. 75, 1449 (2003).

Roddaro, Stefano

2006-03-01

32

Tomonaga-Luttinger liquid related superconductivity in end-bonded carbon nanotubes  

NASA Astrophysics Data System (ADS)

Is it possible to find superconductivity in one-dimensional (1D) systems? It is well known that 1D systems have some obstructions that prevent emergence of superconductivity, e.g. Tomonaga-Luttinger liquid (TLL), spin fluctuation, van-Hove singularity, Peierls transition, and charge-density waves. Carbon nanotube (CN) is a good candidate to investigate this possibility. Although a variety of intriguing quantum phenomena has been reported in CNs, only two groups reported intrinsic superconductivity without reproducibility by other researchers. As well, the transition temperature (Tc) was as low as 0.2K in suspended ropes of SWNTs. Although Tc of 15K was found in thin SWNTs, it was identified only from the Meissner effect. No correlation with 1D phenomena, in particular with TLL arising from 1D electron-electron interaction, was also clarified. Here, we report superconductivity with the onset Tc as high as 12K and T=7.8K, at which resistance drops to zero ohm, for the highest case in end-bonded CNs, which were packed into nanopores of alumina templates. The transition temperatures were approximately 25-times and 40-times larger than those in a past report, respectively. We find that end-bonding the CNs by an electrode is the crucial factor for realizing superconductivity that overcomes TLL.

Haruyama, Junji; Chiashi, Shohei; Sugai, Toshiki

2005-03-01

33

Universal duality in a Luttinger liquid coupled to a generic environment  

NASA Astrophysics Data System (ADS)

We study a Luttinger liquid (LL) coupled to a generic environment consisting of bosonic modes with arbitrary density-density and current-current interactions. The LL can be either in the conducting phase and perturbed by a weak scatterer or in the insulating phase and perturbed by a weak link. The environment modes can also be scattered by the imperfection in the system with arbitrary transmission and reflection amplitudes. We present a general method of calculating correlation functions under the presence of the environment and prove the duality of exponents describing the scaling of the weak scatterer and of the weak link. This duality holds true for a broad class of models and is sensitive to neither interaction nor environmental modes details, thus it shows up as the universal property. It ensures that the environment cannot generate new stable fixed points of the renormalization group flow. Thus, the LL always flows toward either conducting or insulating phase. Phases are separated by a sharp boundary which is shifted by the influence of the environment. Our results are relevant, for example, for low-energy transport in (i) an interacting quantum wire or a carbon nanotube where the electrons are coupled to the acoustic phonons scattered by the lattice defect; (ii) a mixture of interacting fermionic and bosonic cold atoms where the bosonic modes are scattered due to an abrupt local change of the interaction; (iii) mesoscopic electric circuits.

Yurkevich, Igor V.; Yevtushenko, Oleg M.

2014-09-01

34

Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model  

E-print Network

We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge $c=1$, where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix-renormalization-group methods, we demonstrate that the CLL phase, first predicted in [Phys. Rev. Lett. 111, 165302 (2013)], is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge $c=3/2$. The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly-dressed Rydberg atoms confined to optical lattices. Using quantum Monte-Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses.

M. Dalmonte; W. Lechner; Zi Cai; M. Mattioli; A. M. Läuchli; G. Pupillo

2015-02-02

35

Universal Tomonaga-Luttinger liquid phases in one-dimensional strongly attractive SU(N) fermionic cold atoms  

SciTech Connect

A simple set of algebraic equations is derived for the exact low-temperature thermodynamics of one-dimensional multicomponent strongly attractive fermionic atoms with enlarged SU(N) spin symmetry and Zeeman splitting. Universal multicomponent Tomonaga-Luttinger liquid (TLL) phases are thus determined. For linear Zeeman splitting, the physics of the gapless phase at low temperatures belongs to the universality class of a two-component asymmetric TLL corresponding to spin-neutral N-atom composites and spin-(N-1)/2 single atoms. The equation of state which we obtained provides a precise description of multicomponent composite fermions and opens up the study of quantum criticality in one-dimensional systems of N-component Fermi gases with population imbalance.

Guan, X. W.; Lee, J.-Y. [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Batchelor, M. T. [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Mathematical Sciences Institute, Australian National University, Canberra ACT 0200 (Australia); Yin, X.-G.; Chen Shu [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2010-08-15

36

Elementary Excitations in Quantum Liquids.  

ERIC Educational Resources Information Center

Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)

Pines, David

1981-01-01

37

Enhanced NMR Relaxation of Tomonaga-Luttinger Liquids and the Magnitude of the Carbon Hyperfine Coupling in Single-Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recent transport measurements [Churchill et al. Nature Phys.NPAHAX1745-2473 5, 321 (2009)10.1038/nphys1247] found a surprisingly large, 2-3 orders of magnitude larger than usual C13 hyperfine coupling (HFC) in C13 enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17 004 (2010)EULEEJ0295-507510.1209/0295-5075/90/17004]. Though we find that 1/T1 is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters.

Kiss, A.; Pályi, A.; Ihara, Y.; Wzietek, P.; Simon, P.; Alloul, H.; Zólyomi, V.; Koltai, J.; Kürti, J.; Dóra, B.; Simon, F.

2011-10-01

38

Enhanced NMR relaxation of Tomonaga-Luttinger liquids and the magnitude of the carbon hyperfine coupling in single-wall carbon nanotubes.  

PubMed

Recent transport measurements [Churchill et al. Nature Phys. 5, 321 (2009)] found a surprisingly large, 2-3 orders of magnitude larger than usual (13)C hyperfine coupling (HFC) in (13)C enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17,004 (2010)]. Though we find that 1/T(1) is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters. PMID:22107670

Kiss, A; Pályi, A; Ihara, Y; Wzietek, P; Simon, P; Alloul, H; Zólyomi, V; Koltai, J; Kürti, J; Dóra, B; Simon, F

2011-10-28

39

Cross-dimensional phase transition from an array of 1D Luttinger liquids to a 3D Bose-Einstein condensate  

E-print Network

We study the thermodynamic properties of a 2D array of coupled one-dimensional Bose gases. The system is realized with ultracold bosonic atoms loaded in the potential tubes of a two-dimensional optical lattice. For negligible coupling strength, each tube is an independent weakly interacting 1D Bose gas featuring Tomonaga Luttinger liquid behavior. By decreasing the lattice depth, we increase the coupling strength between the 1D gases and allow for the phase transition into a 3D condensate. We extract the phase diagram for such a system and compare our results with theoretical predictions. Due to the high effective mass across the periodic potential and the increased 1D interaction strength, the phase transition is shifted to large positive values of the chemical potential. Our results are prototypical to a variety of low-dimensional systems, where the coupling between the subsystems is realized in a higher spatial dimension such as coupled spin chains in magnetic insulators.

Andreas Vogler; Ralf Labouvie; Giovanni Barontini; Sebastian Eggert; Vera Guarrera; Herwig Ott

2014-10-07

40

Photothermal excitation of microcantilevers in liquids  

NASA Astrophysics Data System (ADS)

We report the selective excitation of the flexural modes of microcantilevers in aqueous solutions, by applying the photothermal excitation technique. The experiments show that a particular vibration mode can be efficiently excited by focusing the intensity-modulated laser beam on regions of high curvature of the vibration shape. In addition, the resulting resonant peaks in liquid appear distorted by an amplitude component that decreases with the frequency. This distortion produces a shift of the resonance to lower frequencies. A theoretical model based on the transformation of optical energy into mechanical energy via an intermediate thermal stage is proposed to interpret the experimental results. The theory shows that the driven oscillation of the cantilever depends on the curvature of the eigenmode at the excitation position and the heating induced by the excitation laser, which decreases with the frequency. The results reported here set the basis for efficient excitation of high vibration modes in liquids and for optimized design of optically driven microresonators.

Ramos, D.; Tamayo, J.; Mertens, J.; Calleja, M.

2006-06-01

41

Equilibration of a one-dimensional quantum liquid  

SciTech Connect

We review some of the recent results on equilibration of one-dimensional quantum liquids. The low-energy properties of these systems are described by the Luttinger liquid theory, in which the excitations are bosonic quasiparticles. At low temperatures, the relaxation of the gas of excitations toward full equilibrium is exponentially slow. In electronic Luttinger liquids, these relaxation processes involve backscattering of electrons and give rise to interesting corrections to the transport properties of one-dimensional conductors. We focus on the phenomenological theory of the equilibration of a quantum liquid and obtain an expression for the relaxation rate in terms of the excitation spectrum.

Matveev, K. A., E-mail: matveev@anl.gov [Argonne National Laboratory Argonne, Materials Science Division (United States)

2013-09-15

42

Luttinger surgery and Kodaira dimension  

E-print Network

In this note we show that the Lagrangian Luttinger surgery preserves the symplectic Kodaira dimension. Some constraints on Lagrangian tori in symplectic four manifolds with non-positive Kodaira dimension are also derived.

Ho, Chung-I

2011-01-01

43

Elementary excitations of liquid 4 He in aerogel  

E-print Network

Elementary excitations of liquid 4 He in aerogel O. Plantevin and B. Fa°k Commissariat a` l-roton excitations of liquid 4 He immersed in aerogel of 95% porosity have been measured using inelastic neutron.25 K. Aerogel grown with deuterated materials not exposed to air was used and measure- ments in bulk

Glyde, Henry R.

44

Tomonaga–Luttinger physics in electronic quantum circuits  

PubMed Central

In one-dimensional conductors, interactions result in correlated electronic systems. At low energy, a hallmark signature of the so-called Tomonaga–Luttinger liquids is the universal conductance curve predicted in presence of an impurity. A seemingly different topic is the quantum laws of electricity, when distinct quantum conductors are assembled in a circuit. In particular, the conductances are suppressed at low energy, a phenomenon called dynamical Coulomb blockade. Here we investigate the conductance of mesoscopic circuits constituted by a short single-channel quantum conductor in series with a resistance, and demonstrate a proposed link to Tomonaga–Luttinger physics. We reformulate and establish experimentally a recently derived phenomenological expression for the conductance using a wide range of circuits, including carbon nanotube data obtained elsewhere. By confronting both conductance data and phenomenological expression with the universal Tomonaga–Luttinger conductance curve, we demonstrate experimentally the predicted mapping between dynamical Coulomb blockade and the transport across a Tomonaga–Luttinger liquid with an impurity. PMID:23653214

Jezouin, S.; Albert, M.; Parmentier, F. D.; Anthore, A.; Gennser, U.; Cavanna, A.; Safi, I.; Pierre, F.

2013-01-01

45

Violent liquid sloshing in vertically excited cylindrical containers  

NASA Astrophysics Data System (ADS)

The frequency characteristics of gas-liquid surface sloshing induced by the vertical vibration of cylindrical containers containing liquid were experimentally investigated using a vibration-testing system with an electrodynamic shaker. The results show that the resonance frequency of the liquid-container vibration system depends on the excitation acceleration, and that the acceleration distribution of the container wall was not axisymmetrical at higher excitation accelerations. Significant changes in liquid pressure, container wall acceleration, and amplitude of surface oscillation were noted following the formation of a bubble cluster.

Hashimoto, Hiroyuki; Sudo, Seiichi

1988-04-01

46

Molecular dynamics of liquid benzene via femtosecond pulses laser excitation  

E-print Network

1749 Molecular dynamics of liquid benzene via femtosecond pulses laser excitation J. Etchepare, G moléculaires. Abstract. 2014 We analyse the complex response of liquid benzene to the applied 45 fs FHWM new results obtained by the transient grating temporal behaviour analysis of benzene, a molecule

Paris-Sud XI, Université de

47

Ionization and Excitation in Non-Polar Organic Liquids.  

ERIC Educational Resources Information Center

Reviews recent advances in radiation chemistry concerning the effect of high-energy radiation on organic liquids. Discusses the general nature of excited and ionized states, pathways for decay, the effect of environmental perturbation, the behavior of an electron in a nonpolar liquid, and comparison of photochemical and radiation chemical effects.…

Lipsky, Sanford

1981-01-01

48

Effective interactions and elementary excitations in quantum liquids  

SciTech Connect

The effective interactions which provide a wavevector and frequency dependent restoring force for collective modes in quantum liquids are derived for the helium liquids by means of physical arguments and sum rule and continuity considerations. A simple model is used to take into account mode-mode coupling between collective and multiparticle excitations, and the results for the zero-temperature liquid /sup 4/He phonon-maxon-roton spectrum are shown to compare favorably with experiment and with microscopic calculation. The role played by spin-dependent backflow in liquid /sup 3/He is analyzed, and a physical interpretation of its variation with density and spin-polarization is presented. A progress report is given on recent work on effective interactions and elementary excitations in nuclear matter, with particular attention to features encountered in the latter system which have no counterparts in the helium liquids.

Pines, D.

1986-01-01

49

A quantum liquid with deconfined fractional excitations in three dimensions  

NASA Astrophysics Data System (ADS)

Excitations which carry ``fractional'' quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However the existence of fractional excitations in three dimensions remains highly controversial. Here we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model --- the quantum dimer model on a diamond lattice [1]. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1) dimensional quantum electrodynamics [2,3]. [4pt] [1] O. Sikora et al. arXiv:0901.1057v3 --- to appear in Phys. Rev. Lett. [0pt] [2] R. Moessner and S.L. Sondhi, Phys. Rev. B 68, 184512 (2003).[0pt] [3] D.L. Bergman et al. Phys. Rev. B 73, 134402 (2006).

Shannon, Nic; Sikora, Olga; Pollmann, Frank; Penc, Karlo; Fulde, Peter

2010-03-01

50

Excitations in liquid ^4He in Geltech silica  

NASA Astrophysics Data System (ADS)

We have measured the elementary excitations of liquid ^4He confined in Geltech silica for temperatures between 35 mK and 2.5 K using inelastic neutron scattering techniques. Geltech is a 40-50% porous media having 25 Ådiameter pores with at most few percent of the volume made up of larger pores of diameter less than 70 ÅWe observe well defined phonon-roton (p-r) excitations at all wave vectors Q investigated (0.4<= Q <= 2.1 ÅAlso observed are 2D layer modes propagating in the liquid layers adjacent to the media walls. These 2D modes are identified as layer modes by measuring the dynamical structure factor of liquid ^4He as a function of filling of the Geltech. At full filling the energies and lifetimes of the 3D p-r modes are the same as those in superfluid ^4He within the current precision. Most interestingly, we observe a well defined p-r excitation above the superfluid-normal transition Tc =0.725 K as determined in a torsional oscillator measurement(S. Miyamoto and Y. Takano, Czech. J. Phys. 46), 137 (1996). Observation of a well defined maxon-roton above Tc in Geltech suggests, as in the case of Vycor(H. R. Glyde, O. Plantevin, B. Fåk, G. Coddens, P. S. Danielson, and H. Schober, Phys. Rev. Lett. 84), 2646 (2000), that there can be localized Bose-Einstein condensation in porous media with phase coherence on short-length scales above the macroscopic superfluid transition temperature.

Plantevin, O.; Schober, H.; Glyde, Henry; Mulders, N.; Bjorn, Fak; Bossy, J.; Albergamo, F.

2002-03-01

51

Dissociative ionization of liquid water induced by vibrational overtone excitation  

SciTech Connect

Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

Natzle, W.C.

1983-03-01

52

COVER IMAGE The TomonagaLuttinger liquid  

E-print Network

. D. Fuchs, G. Burkard, P. V. Klimov and D. D. Awschalom 794 Unconditional room-temperature quantum conductors at low temperature. Yet, experimental evidence that it is valid is sketchy. Scanning tunnelling ON THE COVER Complex oxides Superconductivity and magnetism coexist Letters p762, 767; News & Views p749

Loss, Daniel

53

Nonequilibrium dynamics of coupled Luttinger liquids  

NASA Astrophysics Data System (ADS)

In this work we consider the dynamics of two tunnel-coupled chains after a quench in the tunneling strength is performed and the two systems are allowed to evolve independently. We describe the form of the initial state, comparing with previous results concerning the dynamics after the splitting of a one-dimensional gas of bosons into two phase-coherent systems. We compute different correlation functions, among which are those that are relevant for interference measurements, and discuss the emergence of effective temperatures also in connection with previous works.

Foini, L.; Giamarchi, T.

2015-02-01

54

3He impurity excitation spectrum in liquid 4He  

NASA Astrophysics Data System (ADS)

We microscopically evaluate the excitation spectrum of the 3He impurity in liquid 4He at T=0 and compare it with the experimental curve at equilibrium density. The adopted correlated basis perturbative scheme includes up to two independent phonons, intermediate correlated states, and the correlation operator is built up with two- and three-body correlation functions. The experimental spectrum is well described by the theory along all the available momentum range. A marked deviation from the simple Landau-Pomeranchuck quadratic behavior is found and the momentum-dependent effective mass of the impurity increases by ~50% at q~1.7 Å-1 with respect to its q=0 value. No signature of rotonlike structures is found.

Fabrocini, A.; Polls, A.

1998-09-01

55

Acoustic excitation of liquid fuel droplets and coaxial jets  

NASA Astrophysics Data System (ADS)

This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase of the acoustic field generated within the chamber on the dark core length and the inner jet spreading angles is presented and the stability of coaxial flows in the current flow regime is discussed with respect to evidence for convective and absolute jet instabilities under different operating conditions.

Rodriguez, Juan Ignacio

56

Polarized neutron scattering investigation of excitations at low momentum transfer in liquid Ga: The mystery continues  

E-print Network

Polarized neutron scattering investigation of excitations at low momentum transfer in liquid Ga: Liquid metals; Scattering; Excitations; Sum-rule violation New polarized neutron scattering experiments in the literature. Our polarized neutron scattering experiments show that this increased cross-section cannot

Montfrooij, Wouter

57

Phonon-Roton Excitations in Liquid 4 He at Negative Pressures  

E-print Network

Phonon-Roton Excitations in Liquid 4 He at Negative Pressures Francesco Albergamo,1 Jacques Bossy,2 scattering measurements of the phonon-roton excitations of superfluid 4 He held at negative pressures from zero to ÿ5 bar. The liquid was stretched to negative pressures by immersing it in the porous medium MCM

Glyde, Henry R.

58

Advanced nanoparticle generation and excitation by lasers in liquids.  

PubMed

Today, nanoparticles are widely implemented as functional elements onto surfaces, into volumes and as nano-hybrids, resulting for example in bioactive composites and biomolecule conjugates. However, only limited varieties of materials compatible for integration into advanced functional materials are available: nanoparticles synthesized using conventional gas phase processes are often agglomerated into micro powders that are hard to re-disperse into functional matrices. Chemical synthesis methods often lead to impurities of the nanoparticle colloids caused by additives and precursor reaction products. In the last decade, laser ablation and nanoparticle generation in liquids has proven to be a unique and efficient technique to generate, excite, fragment, and conjugate a large variety of nanostructures in a scalable and clean manner. This editorial briefly highlights selected recent advancements and critical aspects in the field of pulsed laser-based nanoparticle generation and manipulation, including exemplary strategies to harvest the unique properties of the laser-generated nanomaterials in the field of biomedicine and catalysis. The presented critical aspects address future assignments such as size control and scale-up. PMID:23138867

Barcikowski, Stephan; Compagnini, Giuseppe

2013-03-01

59

Instability of interfaces of gas bubbles in liquids under acoustic excitation with dual frequency.  

PubMed

Instability of interfaces of gas bubbles in liquids under acoustic excitation with dual frequency is theoretically investigated. The critical bubble radii dividing stable and unstable regions of bubbles under dual-frequency acoustic excitation are strongly affected by the amplitudes of dual-frequency acoustic excitation rather than the frequencies of dual-frequency excitation. The limitation of the proposed model is also discussed with demonstrating examples. PMID:25164271

Zhang, Yuning; Du, Xiaoze; Xian, Haizhen; Wu, Yulin

2015-03-01

60

Slosh wave excitation due to cryogenic liquid reorientation in space-based propulsion system  

NASA Technical Reports Server (NTRS)

The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquistion or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. In this study slosh wave excitation induced by the resettling flow field activated by 1.0 Hz medium frequency impulsive reverse gravity acceleration during the course of liquid fluid reorientation with the initiation of geyser for liquid filled levels of 30, 50, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed.

Hung, R. J.; Shyu, K. L.; Lee, C. C.

1991-01-01

61

Excitation spectra and spin gap of the half-filled Holstein-Hubbard model  

NASA Astrophysics Data System (ADS)

Single- and two-particle excitation spectra of the one-dimensional, half-filled Holstein-Hubbard model are calculated using the continuous-time quantum Monte Carlo method. In the metallic phase, the results are consistent with a Luther-Emery liquid that has gapped spin and single-particle excitations but a gapless charge mode. However, given the initially exponential dependence of the spin gap on the backscattering matrix element, the numerical excitation spectra appear gapless in the weak-coupling regime, and therefore resemble those of a Luttinger liquid. The Mott phase has the expected charge gap and gapless spin excitations. The Peierls state shows a charge, spin, and single-particle gap, a soft phonon mode, backfolded shadow bands, and soliton excitations. Arguments and numerical evidence for the existence of a nonzero spin gap throughout the metallic phase are provided in terms of equal-time spin and charge correlation functions.

Hohenadler, Martin; Assaad, Fakher F.

2013-02-01

62

Liquid hydrogen slosh waves excited by constant reverse gravity acceleration of geyser initiation  

NASA Technical Reports Server (NTRS)

The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank before main engine restart poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. In this study slosh wave excitation induced by the resettling flowfield during the course of liquid reorientation with the initiation of geyser for liquid-filled levels of 30, 50, 65, 70, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations will affect the fluid stress distribution exerted on the container wall and shift the fluid mass distribution inside the container, which imposes the time-dependent variations in the moment of inertia of the container. This information is important for the spacecraft control during the course of liquid reorientation.

Hung, R. J.; Shyu, K. L.; Lee, C. C.

1992-01-01

63

Electromechanical response to white noise excitation in a ferroelectric liquid crystal  

E-print Network

783 Electromechanical response to white noise excitation in a ferroelectric liquid crystal G. Por possible to use white noise excitation as an input signal. By measuring the time response of the system to the white noise, one can estimate the transfer function (by using for example Fast Fourier Transformation

Boyer, Edmond

64

Parametrically excited sectorial oscillation of liquid drops floating in ultrasound.  

PubMed

We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters. PMID:20481825

Shen, C L; Xie, W J; Wei, B

2010-04-01

65

Excited level anisotropy produced by ion-solid and ion-liquid surface interactions  

E-print Network

model still does not exist which can predict the preferred populations in each sublevel of the excited atom after the foil excitation. In this experiment, the measurement of the anisotropic excitation of boron ion levels by solids and a liquid..., the Joule heating melts the solid gallium into liquid gallium 0 The melting temperature is 29 78 C Before the polarization of light from tHe boron ion beam was measured, a thermocouple was used to cal- ibrate the temperature as a function of heating...

Lee, Chin Shuang

1977-01-01

66

On the Kohn-Luttinger conundrum  

SciTech Connect

Kohn and Luttinger [Phys. Rev. 118, 41 (1960)] showed that the conventional finite-temperature extension of the second-order many-body perturbation theory had the incorrect zero-temperature limit in metals and, on this basis, argued that the theory was incorrect. We show that this inconsistency arises from the noninclusion of the temperature effect in the energies of the zeroth-order eigenstates of the perturbation theory, which causes not only the Kohn-Luttinger conundrum but also another inconsistency with the zero-temperature many-body perturbation theory, namely, the different rates of divergence of the correlation energy in a homogeneous electron gas (HEG). We propose a renormalized many-body perturbation theory derivable from the finite-temperature extension of the normal-ordered second quantization applied to the denominators of the energy expression, which involves the energies of the zeroth-order states, as well as to the numerators. The renormalized theory is shown to have the correct zero-temperature limit and the same rate of divergence in a HEG as the zero-temperature counterpart, and is, therefore, the correct finite-temperature many-body perturbation theory.

Hirata, So [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); He Xiao [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)

2013-05-28

67

Field-dependent molecular ionization and excitation energies: Implications for electrically insulating liquids  

NASA Astrophysics Data System (ADS)

The molecular ionization potential has a relatively strong electric-field dependence as compared to the excitation energies which has implications for electrical insulation since the excited states work as an energy sink emitting light in the UV/VIS region. At some threshold field, all the excited states of the molecule have vanished and the molecule is a two-state system with the ground state and the ionized state, which has been hypothesized as a possible origin of different streamer propagation modes. Constrained density-functional theory is used to calculate the field-dependent ionization potential of different types of molecules relevant for electrically insulating liquids. The low singlet-singlet excitation energies of each molecule have also been calculated using time-dependent density functional theory. It is shown that low-energy singlet-singlet excitation of the type n ? ?* (lone pair to unoccupied ?* orbital) has the ability to survive at higher fields. This type of excitation can for example be found in esters, diketones and many color dyes. For alkanes (as for example n-tridecane and cyclohexane) on the other hand, all the excited states, in particular the ? ? ?* excitations vanish in electric fields higher than 10 MV/cm. Further implications for the design of electrically insulating dielectric liquids based on the molecular ionization potential and excitation energies are discussed.

Davari, N.; Åstrand, P.-O.; Unge, M.; Lundgaard, L. E.; Linhjell, D.

2014-03-01

68

Fractionalized excitations in the spin-liquid state of a kagome-lattice antiferromagnet.  

PubMed

The experimental realization of quantum spin liquids is a long-sought goal in physics, as they represent new states of matter. Quantum spin liquids cannot be described by the broken symmetries associated with conventional ground states. In fact, the interacting magnetic moments in these systems do not order, but are highly entangled with one another over long ranges. Spin liquids have a prominent role in theories describing high-transition-temperature superconductors, and the topological properties of these states may have applications in quantum information. A key feature of spin liquids is that they support exotic spin excitations carrying fractional quantum numbers. However, detailed measurements of these 'fractionalized excitations' have been lacking. Here we report neutron scattering measurements on single-crystal samples of the spin-1/2 kagome-lattice antiferromagnet ZnCu(3)(OD)(6)Cl(2) (also called herbertsmithite), which provide striking evidence for this characteristic feature of spin liquids. At low temperatures, we find that the spin excitations form a continuum, in contrast to the conventional spin waves expected in ordered antiferromagnets. The observation of such a continuum is noteworthy because, so far, this signature of fractional spin excitations has been observed only in one-dimensional systems. The results also serve as a hallmark of the quantum spin-liquid state in herbertsmithite. PMID:23257883

Han, Tian-Heng; Helton, Joel S; Chu, Shaoyan; Nocera, Daniel G; Rodriguez-Rivera, Jose A; Broholm, Collin; Lee, Young S

2012-12-20

69

Effective interactions, elementary excitations, and transport in the helium liquids  

SciTech Connect

Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid /sup 4/He and /sup 3/He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of /sup 4/He and /sup 3/He-/sup 4/He mixtures, the phonon-maxon spectrum of normal and spin-polarized /sup 3/He, and the transport properties of superfluid /sup 4/He and of normal and spin-polarized /sup 3/He.

Pines, D.

1986-01-01

70

Luttinger Model in Dimensions d > 1  

NASA Astrophysics Data System (ADS)

In the present work the Luttinger model is formally extended to d > 1 dimensions. For purposes of comparison with the original model only short-range forces linking the fermions have been considered (as in the Hubbard model). The Fermi sea is decomposed into sectors labeled by wave-vectors q, each containing a set of orthogonal, independent normal modes. Operators that create or destroy normal modes within any given sector are shown to commute with those originating in other sectors. Because the Hamiltonian within each sector is a quadratic form in these normal modes it can be diagonalized in a multitude of ways. One convenient method consists of mapping it onto a model first introduced elsewhere in this volume, the d = 1 expanded Luttinger model. It too can be diagonalized, albeit not so trivially as the original, but by constructing and then diagonalizing a boson string. A product of eigenstates -- one from each sector -- is used to construct an exact eigenstate of the full many-body problem if the algebra connecting all the normal modes is Abelian. However, some form of non-Abelian algebra governs the normal modes in the presence of any sort of long-range order (LRO), whether ferromagnetic, antiferromagnetic or superconducting. (Note that the Mermin-Wagner theorem does preclude spontaneous LRO in dimensions d ? 2). Although it is also important to understand the nature of dynamical exchange corrections to arbitrary-range interactions -- including the physically important Coulomb interaction -- a detailed derivation, together with such other conundrum as the calculation of one-fermion distribution functions from "first principles," all are topics relegated to future publications.

Mattis, Daniel C.

2014-10-01

71

Pressure dependence of elementary excitations in normal liquid helium-3  

Microsoft Academic Search

The neutron scattering function for liquid 3He at 120 mK and pressures of 9, 0.5, 1, and 2 MPa has been determined for wave vectors in the range 3 nm-1

R. Scherm; K. Guckelsberger; B. Fak; K. Sköld; A. J. Dianoux; H. Godfrin; W. G. Stirling

1987-01-01

72

Neutron scattering study of elementary excitations in liquid helium-3  

Microsoft Academic Search

The neutron inelastic scattering function of liquid helium-3 at 0.015 K has been measured for wave vectors in the range 0.8 A⁻¹< or =q< or =2.2 A⁻¹. For q<1.4 A⁻¹, the scattering function contains two peaks. The peak at lower energy is due to spin-fluctuation scattering in the particle-hole region while the peak at higher energy is identified to be

K. Skold; C. A. Pelizzari; R. Kleb; G. E. Ostrowski

1976-01-01

73

FRONTIERS ARTICLE Dynamics of excited state electron transfer at a liquid interface  

E-print Network

importance in electrochemical exper- iments is that both liquids must contain supporting electrolytes [20 and tech- nological importance [1­7]. The physical and chemical characteris- tics of excited state electron to be important in advancing our understanding of electron transfer pro- cesses [1,18,19]. With the development

Turro, Nicholas J.

74

Excitations from a chiral magnetized state of a frustrated quantum spin liquid  

SciTech Connect

We study excitations in weakly interacting pairs of quantum spin ladders coupled through geometrically frustrated bonds. The ground state is a disordered spin liquid, at high fields replaced by an ordered chiral helimagnetic phase. The spectra observed by high-field inelastic neutron scattering experiments on the prototype compound Sul Cu2Cl4 are qualitatively different from those in the previously studied frustration-free spin liquids. Beyond the critical field Hc = 3.7 T, the soft mode that drives the quantum phase transition spawns two separate excitations: a gapless Goldstone mode and a massive magnon. Additional massive quasiparticles are clearly visible below Hc, but are destroyed in the ordered phase. In their place one observes a sharply bound excitation continuum.

Garlea, Vasile O [ORNL; Zheludev, Andrey I [ORNL; Tsvelik, A. [Brookhaven National Laboratory (BNL); Regnault, L.-P. [CEA, Grenoble, France; Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Kiefer, K. [Hahn-Meitner Institut, Berlin, Germany; Roessli, Bertrand [Swiss Spallation Neutron Source SINQ

2009-01-01

75

Excitations from a Chiral Magnetized State of a Frustrated Quantum Spin Liquid  

SciTech Connect

We study excitations in weakly interacting pairs of quantum spin ladders coupled through geometrically frustrated bonds. The ground state is a disordered spin liquid that at high fields is replaced by an ordered chiral helimagnetic phase. The spectra observed by high-field inelastic neutron scattering experiments on the prototype compound Sul-Cu{sub 2}Cl{sub 4} are qualitatively different from those in the previously studied frustration-free spin liquids. Beyond the critical field H{sub c} = 3.7 T, the soft mode that drives the quantum phase transition spawns two separate excitations: a gapless Goldstone mode and a massive magnon. Additional massive quasiparticles are clearly visible below H{sub c}, but are destroyed in the ordered phase. In their place one observes a sharply bound excitation continuum.

Zheludev, A.; Tsvelik, A.; Garlea, V.O.; Regnault, L.-P.; Habicht, K.; Kiefer, K.; Roessli, B.

2009-12-15

76

Excitations in a thin liquid {sup 4}He film from inelastic neutron scattering  

SciTech Connect

We perform a thorough analysis of the experimental dynamic structure function measured by inelastic neutron scattering for a low-temperature ({ital T}=0.65 K) four-layer liquid {sup 4}He film. The results are interpreted in light of recent theoretical calculations of the (nonvortex) excitations in thin liquid Bose films. The experimental system consists of four outer liquid layers, adsorbed to two solid inner {sup 4}He layers, which are themselves adsorbed to a graphite substrate. Relatively intense surface (ripplon) and bulklike modes are observed. The analysis of the experimental data gives strong evidence for still other modes and supports the long-standing theoretical predictions of layerlike modes (layer phonons) associated with excitations propagating primarily within the liquid layers comprising the film. The results of the analysis are consistent with the occurrence of level crossings between modes, and the existence of a layer modes for which the theory predicts will propagate in the vicinity of the solid-liquid interface. The theory and experiment agree on the detailed nature of the ripplon; its dispersion at low momenta, its fall off in intensity at intermediate momenta, and the level crossings at high momentum. Similar to experiment, the theory yields an intense mode in the maxon-roton region which is intrepreted as the formation of the bulklike excitation. {copyright} {ital 1996 The American Physical Society.}

Clements, B.E. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); [Institute Laue Langevin, 38042 Grenoble Cedex (France); Godfrin, H. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, Boite Postale 166X, 38042 Grenoble (France)] [Centre de Recherches sur les Tres Basses Temperatures, CNRS, Boite Postale 166X, 38042 Grenoble (France); Krotscheck, E. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A 4040 Linz (Austria); Lauter, H.J. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); Leiderer, P. [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany)] [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany); Passiouk, V. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

77

Enhanced efficiency in the excitation of higher modes for atomic force microscopy and mechanical sensors operated in liquids  

NASA Astrophysics Data System (ADS)

Recent developments in dynamic Atomic Force Microscopy where several eigenmodes are simultaneously excited in liquid media are proving to be an excellent tool in biological studies. Despite its relevance, the search for a reliable, efficient, and strong cantilever excitation method is still in progress. Herein, we present a theoretical modeling and experimental results of different actuation methods compatible with the operation of Atomic Force Microscopy in liquid environments: ideal acoustic, homogeneously distributed force, distributed applied torque (MAC Mode™), photothermal and magnetostrictive excitation. From the analysis of the results, it can be concluded that magnetostriction is the strongest and most efficient technique for higher eigenmode excitation when using soft cantilevers in liquid media.

Penedo, M.; Raman, A.; Hormeño, S.; Fernández-Martínez, I.; Luna, M.; Briones, F.

2014-10-01

78

Enhanced efficiency in the excitation of higher modes for atomic force microscopy and mechanical sensors operated in liquids  

SciTech Connect

Recent developments in dynamic Atomic Force Microscopy where several eigenmodes are simultaneously excited in liquid media are proving to be an excellent tool in biological studies. Despite its relevance, the search for a reliable, efficient, and strong cantilever excitation method is still in progress. Herein, we present a theoretical modeling and experimental results of different actuation methods compatible with the operation of Atomic Force Microscopy in liquid environments: ideal acoustic, homogeneously distributed force, distributed applied torque (MAC Mode™), photothermal and magnetostrictive excitation. From the analysis of the results, it can be concluded that magnetostriction is the strongest and most efficient technique for higher eigenmode excitation when using soft cantilevers in liquid media.

Penedo, M., E-mail: mapenedo@imm.cnm.csic.es; Hormeño, S.; Fernández-Martínez, I.; Luna, M.; Briones, F. [IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, E-28760 Tres Cantos, Madrid (Spain); Raman, A. [Birck Nanotechnology Center and School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47904 (United States)

2014-10-27

79

Slosh wave excitation of cryogenic liquid helium in gravity Probe-B rotating dewar  

NASA Technical Reports Server (NTRS)

The dynamical behavior of fluids, in particular the effect of surface tension on partially-filled rotating fluids (cryogenic liquid helium and helium vapor) in a full scale Gravity Probe-B Spacecraft propellant dewar tank imposed by various frequencies of gravity jitters have been investigated. Fluid stress distribution, caused by the excitation of slosh waves and their associated large amplitude disturbances on the liquid-vapor interface, exerted on the outer and inner walls of rotating dewar container also have been investigated. Results show that fluid stress distribution exerted on the outer and inner walls of rotating dewar are closely related to the characteristics of slosh waves excited on the liquid-vapor interface in the rotating dewar tank.

Hung, R. J.; Lee, C. C.; Leslie, F. W.

1991-01-01

80

Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation  

E-print Network

radicals absorb at that wavelength. Hydro- gen atoms and hydronium ions do not absorb light at either wavelength. In addition to the measurements for pure water, we ob- serve the transient change in absorption for a 2M solution of perchloric acid, where... waters preferentially decay through an alternate mechanism #1;e.g., the quantum yield of dissociation in crystalline ice is less than unity#2;, then the branching among channels depends on the extent of hydro- gen bonding in the liquid. Temperature...

Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Bradforth, Stephen E.

2007-04-25

81

Slosh wave and geyser excitations due to liquid hydrogen shut-off during draining in microgravity  

NASA Technical Reports Server (NTRS)

The dynamical behavior of liquid hydrogen shut-off during draining, and shut-off at the moment of the incipience of a suction dip have been investigated. It shows that a large amplitude surge is observed for liquid in the container at the moment of liquid hydrogen shut-off in reduced gravity. It also shows that slosh waves accompanied by a strong geyser are developed for surge-related flow fields induced by liquid hydrogen shut-off at the incipience of a suction dip. In the slosh wave excitation, both a lower gravity environment and higher flow rate before the shut-off of liquid draining are resonsible for the initiation of greater amplitude slosh waves. Slosh wave excitation, due to shut-off during liquid hydrogen draining, shift the fluid mass distribution in the container which imposes time-dependent variation in the spacecraft moment of inertia. This provides important information necessary for on-orbit guidance and attitude control of spacecraft.

Hung, R. J.; Shyu, K. L.

1995-01-01

82

Liquid draining shut-off induced geyser and slosh wave excitation at suction dip during draining in microgravity  

NASA Technical Reports Server (NTRS)

The dynamical behavior of vapor ingestion, liquid residual at the incipience of suction dip, liquid hydrogen shut-off at the incipience of suction dip, and slosh wave excitation under normal and various reduced gravity environments and different flow rates of liquid during draining have been investigated. It shows that the liquid residual at the incipience of suction dip increases as the values of gravity environment decrease from normal gravity to lower reduced gravity, and also that the liquid residual increases as the flow rates of liquid increase during the courses of liquid hydrogen draining. It also shows that slosh waves accompanied by strong geyser are developed for surge-related flowfields at the moment of liquid hydrogen shut-off. Slosh wave excitation, during the liquid hydrogen shut-off, shift the fluid mass distribution in the container which imposes time-dependent variation in spacecraft moment of inertia.

Hung, R. J.; Shyu, K. L.

1992-01-01

83

Coherent control of the molecular dynamics in a liquid by femtosecond four-pulse excitation  

NASA Astrophysics Data System (ADS)

The laser non-resonant excitation based on the (2? × ?2) sequence of the two pairs of the pump pulses with orthogonal linear polarizations is proposed and theoretically considered for the control of the vibrational responses without or with the low amplitude of the rotational responses in a liquid. As an example, we model the optical molecular responses resulting in the optical Kerr effect transients in ortho-dichlorobenzene. Theoretical analysis shows the high efficiency of the (2? × ?2) excitation scenarios for the various manipulations of the molecular responses.

Nikiforov, V. G.; Lobkov, V. S.; Samartsev, V. V.; Saiko, A. P.

2015-01-01

84

Studies Of The Solid-Liquid Interface Via Laser Excited Surface Plasmon Spectroscopy  

NASA Astrophysics Data System (ADS)

The chemistry of the solid-liquid interface is of intense practical and theoretical interest, since a vast majority of heterogeneous reaction, adsorption, and epitaxy processes occur there. It is also among the most difficult of systems to study. One must have a probe which is extraordinarily sensitive, in order to observe the first few atomic layers, and very selective, in order to separate the effects of the surface associated species from those of the solvent or neat liquid in close proximity. To fulfill these requirements and to retain the advantages of optical spectroscopic techniques requires that the electric fields employed for excitation of interfacial molecules be spatially localized. When the solid component of the interface is one of the non-lossy metals, the above constraints can be satisfied by exciting a surface plasma resonance of a thin metallic film. Both theoretical and experimental work has shown that enhancement of Raman signals at Ag-liquid interfaces can be as high as 4 x 104. In addition the excitation of surface plasma resonances at metallic interfaces in the Kretschmann configuration has been shown to be extremely sensitive to adsorption of components from the ambient.4-7 In general the position of the plasmon resonance along the wavevector axis shifts and broadens upon adsorption or overcoating. Thus the exci-tation of surface plasma resonances at metal-liquid interfaces offers the possibility of simultaneously studying both adsorption-desorption kinetics, via observation of the reflectivity, and interfacial geometries, via enhanced signal vibrational spectroscopy of the adsorbates themselves.

Bohn, P. W.

1986-06-01

85

Liquid laser cavities and waveguides. III. Radiation coupling-out and fluorescence under uniform excitation. 'Evapolators'  

SciTech Connect

An investigation was made of laser radiation coupling-out from totally reflecting closed liquid cavities by local frustration of total internal reflection with the aid of internal water spheres and external contact with a substrate or a prism. A rotating drop of ethanol containing rhodamine B in an envelope of liquid C{sub 8}F{sub 18} generated laser radiation with a divergence of several angular degrees and an efficiency up to 5% relative to the excitation energy. A transparent drop of ethanol with rhodamine B, suspended in air, and subjected to uniform pumping was used to determine the depth of the zone in which lasing took place in a liquid cavity. An increase in the integral (during the pump time) fluorescence energy from a selected internal part of this drop, which did not participate in lasing, on increase in the excitation flux was in agreement with the expectations and it began to fall at high pump intensities. Characteristics of oscillations in immiscible liquids which evaporated in an evaporator - oscillator ('evapolator') were discussed. (control of laser radiation parameters)

Belonogov, A Yu; Startsev, Aleksandr V; Stoilov, Yurii Yu; Sung-Joo, Cho [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1998-07-31

86

Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source: Assessment of plasma characteristics  

NASA Astrophysics Data System (ADS)

The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as a secondary excitation source with a parametric evaluation regarding carrier gas flow rate, applied current, and electrode distance. With this parametric evaluation, plasma optical emission was monitored in order to obtain a fundamental understanding with regards to rotational temperature (Trot), excitation temperature (Texc), electron number density (ne), and plasma robustness. Incentive for these studies is not only for a greater overall fundamental knowledge of the APGD, but also in instrumenting a secondary excitation/ionization source following laser ablation (LA). Rotational temperatures were determined through experimentally fitting of the N2 and OH molecular emission bands while atomic excitation temperatures were calculated using a Boltzmann distribution of He and Mg atomic lines. The rotational and excitation temperatures were determined to be ~ 1000 K and ~ 2700 K respectively. Electron number density was calculated to be on the order of ~ 3 × 1015 cm- 3 utilizing Stark broadening effects of the H? line of the Balmer series and a He I transition. In addition, those diagnostics were performed introducing magnesium (by solution feed and laser ablation) into the plasma in order to determine any perturbation under heavy matrix sampling. The so-called plasma robustness factor, derived by monitoring Mg II/Mg I emission ratios, is also employed as a reflection of potential perturbations in microplasma energetics across the various operation conditions and sample loadings. While truly a miniaturized source (< 1 mm3 volume), the LS-APGD is shown to be quite robust with plasma characteristics and temperatures being unaffected upon introduction of metal species, whether by liquid or laser ablation sample introduction.

Manard, Benjamin T.; Gonzalez, Jhanis J.; Sarkar, Arnab; Dong, Meirong; Chirinos, Jose; Mao, Xianglei; Russo, Richard E.; Marcus, R. Kenneth

87

Evidence of delayed light emission of tetraphenyl-butadiene excited by liquid-argon scintillation light  

NASA Astrophysics Data System (ADS)

Tetraphenyl-butadiene is the wavelength shifter most widely used in combination with liquid argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. Tetraphenyl-butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100% for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV. This work shows that tetraphenyl-butadiene, when excited by 127 nm photons, re-emits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarifying the anomalies in liquid-argon scintillation light reported in the literature since the 1970s, namely, the inconsistency in the measured values of the long decay time constant and the appearance of an intermediate component. Similar effects should be also expected when the TPB is used in combination with helium and neon, which emit scintillation photons with wavelengths shorter than 127 nm.

Segreto, E.

2015-03-01

88

Evidence of delayed light emission of TetraPhenyl Butadiene excited by liquid Argon scintillation light  

E-print Network

TetraPhenyl Butadiene is the wavelength shifter most widely used in combination with liquid Argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. TetraPhenyl Butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100% for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV. This work shows that TetraPhenyl Butadiene, when excited by 127 nm photons, reemits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarify the anomalies of liquid Argon scintillation light reported in literature since seventies, namely the inconsistency in the measured values of the long decay time constant and the appearence of an intermediate component.

Ettore Segreto

2014-11-17

89

Fractional shot noise in partially gapped Tomonaga-Luttinger liquids  

NASA Astrophysics Data System (ADS)

We depict a family of one-dimensional systems where one can create and detect fractional charges. These charges are produced via interacting one-dimensional conductors connected to noninteracting leads. At certain electron densities, some distinct modes develop an energy gap due to electron-electron interactions. This gap allows for tunneling events inside the conductor, which generate electric current noise. The resulting fractional noise's Fano factor depends only on the identification of the gapped mode, and is insensitive to additional interactions in the conductor. These effects can be realized in either quantum wires or edges of quantum Hall systems.

Cornfeld, Eyal; Neder, Izhar; Sela, Eran

2015-03-01

90

Ultrafast spectroscopy of electron transfer dynamics in liquids; excitation transfer studies of phase transitions  

NASA Astrophysics Data System (ADS)

The transfer of an electron from a donor to an acceptor is the fundamental step in a wide range of chemical and biological processes. As a result, electron-transfer reactions have been the focus of numerous theoretical and experimental efforts aimed at understanding the kinetics and mechanism of the transfer event. Liquid solvents are an important medium for electron-transfer processes. The influences of the distance dependence, diffusion, the radial distribution function, and the hydrodynamic effect have been incorporated into the theory of electron transfer in solution, as well as into the theory of electron transfer between donors and acceptors in the head group regions of micelles. The development of new laser system with a pulse duration of tens of femtoseconds, with tunable wavelength allowed us to study these processes on a considerably shorter time scale than previous studies. This allowed us to observe not only the diffusion controlled but also the kinetics of electron transfer for donor/acceptor pairs that are in close proximity. In one set of experiments we have studied the kinetics of electron transfer in electron accepting molecule (rhodamine 3B) dissolved in electron donating solvent (N,N-dimethylaniline). The data for the forward electron transfer and geminate recombination are approximated by the statistical theory of the electron transfer. Optical anisotropy observed in the experiment demonstrates the orientation dependence of the electron transfer rate. In further experiments we investigated the electron transfer in non-hydrogen bonding liquids of increasing viscosity. The effective value of the donor/acceptor electronic coupling was found to decrease with viscosity. Electron transfer experiments were also carried out on the surface of micelles. The systems studied are the hole donor octadecyl-rhodamine B (ODRB) and the hole acceptor N,N-dimethyl-aniline (DMA) in micelles made of dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB). It was found that the effective coupling is reduced compared to donor/acceptor pairs dissolved in simple liquids. In the 2nd half of thesis we have addressed the question of the dynamics of phase transitions. We have demonstrated the ability to use the fluorescent excitation-transfer technique to study the demixing of liquids specifically, kinetics of demixing water and 2,6-dimethylpyridine. These two liquids possess a low critical temperature point, which allowed us to use a temperature jump from a laser pulse to initiate the process of phase separation. It was found that Coumarin480 laser dye and HPTS (8-Hydroxypyrene-1,3,6-trisulfonic acid) fluorescent dye have significantly different solubilities in the components of the mixture. These dyes undergo excitation transfer from Coumarin480 to HPTS in the uniform state, but not in the phase-separated state. A system with a temperature jump pump and an excitation transfer probe measured the time scale of the initial step of the phase separation.

Goun, Alexei A.

91

High efficiency laser photothermal excitation of microcantilever vibrations in air and liquids  

NASA Astrophysics Data System (ADS)

Photothermal excitation is a promising means of actuating microscale structures. It is gaining increased interest for its capability to excite atomic force microscopy (AFM) microcantilevers with wide frequency bandwidth in liquid environments yielding clean resonance peaks without spurious resonances. These capabilities are particularly relevant for high speed and high resolution, quantitative AFM. However, photothermal efficiency is low, which means a large amount of laser power is required for a given mechanical response. The high laser power may cause local heating effects, or spill over the cantilever and damage sensitive samples. In this work, it is shown that by simply changing from a probe with a rectangular cross-section to one with a trapezoidal cross-section, the photothermal efficiency of an uncoated silicon cantilever can be increased by more than a order of magnitude, and the efficiency of a coated cantilever can be increased by a factor of 2. This effect is demonstrated experimentally and explained theoretically using thermomechanical analysis. Results are shown for both air and water, and for normal bending and torsional oscillations.

Kiracofe, Daniel; Kobayashi, Kei; Labuda, Aleksander; Raman, Arvind; Yamada, Hirofumi

2011-01-01

92

High efficiency laser photothermal excitation of microcantilever vibrations in air and liquids.  

PubMed

Photothermal excitation is a promising means of actuating microscale structures. It is gaining increased interest for its capability to excite atomic force microscopy (AFM) microcantilevers with wide frequency bandwidth in liquid environments yielding clean resonance peaks without spurious resonances. These capabilities are particularly relevant for high speed and high resolution, quantitative AFM. However, photothermal efficiency is low, which means a large amount of laser power is required for a given mechanical response. The high laser power may cause local heating effects, or spill over the cantilever and damage sensitive samples. In this work, it is shown that by simply changing from a probe with a rectangular cross-section to one with a trapezoidal cross-section, the photothermal efficiency of an uncoated silicon cantilever can be increased by more than a order of magnitude, and the efficiency of a coated cantilever can be increased by a factor of 2. This effect is demonstrated experimentally and explained theoretically using thermomechanical analysis. Results are shown for both air and water, and for normal bending and torsional oscillations. PMID:21280832

Kiracofe, Daniel; Kobayashi, Kei; Labuda, Aleksander; Raman, Arvind; Yamada, Hirofumi

2011-01-01

93

Soil-structure interaction effects for laterally excited liquid-tank system  

SciTech Connect

Following a brief review of the mechanical model for liquid-storage tanks which permits consideration of the effects of tank and ground flexibility, and lateral and rocking base excitations, the effects of both kinematic and inertia interaction effects on the response of the tank-liquid system are examined and elucidated. The free-field motion is defined by a power spectral density function and an incoherence function, which characterizes the spatial variability of the ground motion due to the vertically incident incoherence waves. The quantities examined are the ensemble means of the peak values of the response. The results are compared with those obtained for no soil-structure interaction and for kinematic interaction to elucidate the nature and relative importance of the two interactions. Only the impulsive actions are examined, the convective actions are for all practical purposes unaffected by both kinematic and inertia interactions. It is shown that the major reduction of the response is attributed to inertia interaction. 20 refs.

Tang, Yu (Argonne National Lab., IL (United States)); Veletsos, A.S. (Rice Univ., Houston, TX (United States). Dept. of Civil Engineering)

1992-01-01

94

Soil-structure interaction effects for laterally excited liquid-tank system  

SciTech Connect

Following a brief review of the mechanical model for liquid-storage tanks which permits consideration of the effects of tank and ground flexibility, and lateral and rocking base excitations, the effects of both kinematic and inertia interaction effects on the response of the tank-liquid system are examined and elucidated. The free-field motion is defined by a power spectral density function and an incoherence function, which characterizes the spatial variability of the ground motion due to the vertically incident incoherence waves. The quantities examined are the ensemble means of the peak values of the response. The results are compared with those obtained for no soil-structure interaction and for kinematic interaction to elucidate the nature and relative importance of the two interactions. Only the impulsive actions are examined, the convective actions are for all practical purposes unaffected by both kinematic and inertia interactions. It is shown that the major reduction of the response is attributed to inertia interaction. 20 refs.

Tang, Yu [Argonne National Lab., IL (United States); Veletsos, A.S. [Rice Univ., Houston, TX (United States). Dept. of Civil Engineering

1992-05-01

95

Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian  

SciTech Connect

We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378 (2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the 'Zitterbewegung' of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.

Jiang, Z.F.; /Beijing, Inst. Phys.; Li, R.D.; /Peking U.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.; Liu1, W.M.; /Beijing, Inst. Phys.

2010-02-15

96

Cross sections, stopping powers, and energy loss rates for rotational and phonon excitation processes in liquid water by electron impact  

NASA Astrophysics Data System (ADS)

We calculated cross sections, stopping powers, and energy loss rates for rotational and phonon-mode excitations caused by the impact of an electron in an energy region from 0.1 meV to 100 eV injected into liquid water. The spatial distribution of the decelerated electron depends on these cross sections. We performed calculations assuming an optical approximation with the dielectric functions that are experimentally reported in the literature. We observed that the cross sections lie below 1×10-16 cm2 over the considered energy region. The values for rotational excitation processes in the liquid phase are less by three orders of magnitude than those in the gas phase because of the screening effect of neighboring water molecules on the interaction between the incident electron and water molecules. These results suggest that the cross sections in the liquid phase are significantly different from those in the gas phase. The values for phonon-mode excitations in the liquid phase are close to those reported for amorphous ice. Furthermore, we observed that the stopping power shows a maximum around 200 meV, and the energy loss rates, which are derived from the stopping power, depend significantly on the electron energy, particularly below 1 eV. The values obtained here will allow us to precisely estimate the decelerating process of an electron in liquid water to predict radiation effects such as chemical processes in water radiolysis or biomolecular damage induction strongly involved in low energy electron processes.

Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Watanabe, Ritsuko

2015-03-01

97

Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid  

E-print Network

Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become progressively more correlated. This results in the decoupling of exchange and persistence times, reflecting a violation of the Stokes-Einstein relation.

Daun Jeong; M. Y. Choi; Hyung. J. Kim; YounJoon Jung

2010-02-03

98

Liquid sloshing in partly-filled laterally-excited circular tanks equipped with baffles  

NASA Astrophysics Data System (ADS)

Linear potential theory in conjunction with the conformal mapping technique are employed to develop rigorous mathematical models for two-dimensional transient sloshing in non-deformable baffled horizontal circular cylindrical vessels, filled with inviscid incompressible fluids to arbitrary depths, and subjected to arbitrary time-dependent lateral accelerations. Three common baffle configurations are considered, namely, a pair of free surface-touching horizontal side baffles, and a central surface-piercing or bottom-mounted vertical baffle of arbitrary extension. The first few normalized antisymmetric/symmetric sloshing frequencies of the partially-filled tanks are tabulated for selected baffle extension and fill depth ratios. Also, the effects of liquid fill depth or baffle length parameter on the impulsive, total and modal convective mass ratios are examined. A ramp-step function is used to replicate the lateral acceleration excitation encountered in an idealized turning maneuver. Durbin's numerical Laplace transform inversion scheme was applied to solve the resulting truncated linear sets of ordinary differential equations in the time-domain. The effects of excitation input time, fill level, and baffle configuration/extension on the force and moment amplification factors are illustrated through appropriate design charts. Furthermore, the transient hydrodynamic responses to a real seismic event are calculated and the effectiveness of baffle configuration/length on suppression of the induced destabilizing lateral forces are examined. Limiting cases are considered and rigorous verifications are made by comparison with the available data as well as with the numerical simulations performed by using a commercial CFD software package.

Hasheminejad, Seyyed M.; Mohammadi, M. M.; Jarrahi, Miad

2014-01-01

99

Fermi liquid theory for high temperature superconductors  

SciTech Connect

In this article the Fermi liquid theory of metals is discussed starting from Luttinger's theorem. The content of Luttinger's Theorem and its implications for microscopic theories of high temperature superconductors are discussed. A simple quasi-2d Fermi liquid theory is introduced and some of its properties are calculated. It is argued that a number of experiments on YBa/sub 2/Cu/sub 3/O/sub 6+x/, x > 0.5, strongly suggest the existence of a Fermi surface and thereby a Fermi liquid normal state. 25 refs., 1 fig.

Bedell, K.S.

1988-01-01

100

Evidence of scattering of bulk elementary excitations in isotopically pure liquid helium-II at low temperatures  

NASA Astrophysics Data System (ADS)

This short report is concerned with experimental investigations of bulk elementary excitations (BEEs) in the isotopically pure liquid helium-II at low temperatures below 100 mK. The evidence of BEEs? scattering is introduced in this work. Two identical Au-heaters were used to generate BEEs. The first pulsed heater generates BEE beams to record them. The second heater serves to generate BEE beams in order to scatter the first beams, operating delay time between pulses of the heaters. Experimental signals were recorded by several bolometers situated both above and below the liquid surface: scattered BEEs are travelling in the liquid from the pulsed heater to the bolometer; scattered BEEs, reaching the liquid surface, evaporate 4He-atoms detected by two bolometers positioned in a vacuum; scattered signals are reflected from the liquid surface back to the liquid and are detected by the other bolometer situated in the liquid. It is manifested that the experimental results showed a dramatic decrease in peaks of recorded signals. Also, signal losses for different heater powers were calculated.

Zakharenko, A. A.

2010-07-01

101

Enhancement CH-SRS of benzene mixing with toluene in liquid-core optical fiber at a low excitation power  

Microsoft Academic Search

Stimulated Raman scattering (SRS) of benzene mixing with toluene is studied in liquid-core optical fiber (LCOF) at a low excitation power 3mJ\\/pulse. We obtained the intensive SRS of CH stretching vibration at 3060cm?1 [CH-SRS]. Neat benzene or toluene does not show the CH-SRS line under the same experimental condition. The CH-SRS threshold at 3060cm?1 for the binary solution was 2.5mJ\\/pulse.

Wenhui Fang; Chenglin Sun; Guannan Qu; Yunfeng Ding; Anyang Cao; Wei Song; Zuowei Li; Zhanlong Li; Zhiwei Men

102

High-frequency damping of collective excitations in fermion systems. II. Damping of zero sound in normal liquid 3He  

Microsoft Academic Search

The polarization potential approach of Aldrich and Pines to treat the elementary excitations in liquid 3He is here extended by an explicit many-body calculation of the two-particle-hole pair contribution to the imaginary part of the proper polarizability, as outlined in paper I and using a physically reasonable ansatz. The result is then used to calculate the line shape of the

A. Holas; K. S. Singwi

1989-01-01

103

Magnetic field spectral crossings of Luttinger holes in quantum wells  

NASA Astrophysics Data System (ADS)

We develop an analytic approach to two-dimensional (2D) holes in a magnetic field that allows us to gain insight into physics of measuring the parameters of holes, such as cyclotron resonance, Shubnikov-de Haas effect and spin resonance. We derive hole energies, cyclotron masses, and the g factors in the semiclassical regime analytically, as well as analyze numerical results outside the semiclassical range of parameters, qualitatively explaining the experimentally observed magnetic field dependence of the cyclotron mass. In the semiclassical regime with large Landau level indices, and for size quantization energy much bigger than the cyclotron energy, the cyclotron mass coincides with the in-plane effective mass, calculated in the absence of a magnetic field. The hole g factor in a magnetic field perpendicular to the 2D plane is defined not only by the constant of direct coupling of the angular momentum of the holes to the magnetic field, but also by the Luttinger constants defining the effective masses of holes. We find that the g factor for quasi-2D holes with heavy mass in the [001] growth direction in GaAs quantum well is g =4.05 in the semiclasssical regime. Outside the semiclassical range of parameters, holes behave as a species completely different from electrons. Spectra for size- and magnetic-field-quantized holes are nonequidistant, not fanlike, and exhibit multiple crossings, including crossing in the ground level. We calculate the effect of Dresselhaus terms, which transform some of the crossings into anticrossings, and the effects of the anisotropy of the Luttinger Hamiltonian on the 2D hole spectra. Dresselhaus terms of different symmetries are taken into account, and a regularization procedure is developed for the kz3 Dresselhaus terms. Control of the nonequidistant levels and crossing structure by the magnetic field can be used to control the Landau level mixing in hole systems, and thereby control hole-hole interactions in the magnetic field.

Simion, G. E.; Lyanda-Geller, Y. B.

2014-11-01

104

Comparison of photothermal and piezoacoustic excitation methods for frequency and phase modulation atomic force microscopy in liquid environments  

NASA Astrophysics Data System (ADS)

In attempting to perform frequency modulation atomic force microscopy (FM-AFM) in liquids, a non-flat phase transfer function in the self-excitation system prevents proper tracking of the cantilever natural frequency. This results in frequency-and-phase modulation atomic force microscopy (FPM-AFM) which lies in between phase modulation atomic force microscopy (PM-AFM) and FM-AFM. We derive the theory necessary to recover the conservative force and damping in such a situation, where standard FM-AFM theory no longer applies. Although our recovery procedure applies to all cantilever excitation methods in principle, its practical implementation may be difficult, or even impossible, if the cantilever is driven piezoacoustically. Specifically, we contrast the piezoacoustic excitation method to the photothermal method in the context of force spectroscopy of hydration structures at the mica-water interface. The results clearly demonstrate that photothermal excitation is superior to piezoacoustic excitation, as it allows for accurate quantitative interpretation of the acquired data.

Labuda, A.; Kobayashi, K.; Kiracofe, D.; Suzuki, K.; Grütter, P. H.; Yamada, H.

2011-06-01

105

Interfacial solvation and excited state photophysical properties of 7-aminocoumarins at silica/liquid interfaces  

NASA Astrophysics Data System (ADS)

The properties of solutes adsorbed at interfaces can be very different compared to bulk solution limits. This thesis examines how polar, hydrophilic silica surfaces and different solvents systematically change a solute's equilibrium and dynamic solvation environment at solid/liquid interfaces. The primary tools used in these studies are steady state fluorescence spectroscopy and time correlated single photon counting (TCSPC) --a fluorescence method capable resolving fluorescence emission on the picosecond timescale. To sample adsorbed solutes, TCSPC experiments were carried out in total internal reflection (TIR) geometry. These studies used total of six different 7-aminocoumarin dyes to isolate the effects of molecular and electronic structure on solute photophysical behavior. Fluorescence lifetimes measured in the TIR geometry are compared to the lifetimes of coumarins in bulk solution using different solvents to infer interfacial polarity and excited state solute conformation and dynamics. Steady state emission experiments measuring the behavior of the coumarins adsorbed at silica surfaces from bulk methanol solutions show that all coumarins had a similar affinity DeltaG ads ˜ - 25-30 kJ/mole. Despite these similar adsorption energetics solute structure had a very pronounced effect on the tendency of solutes to aggregate and form multilayers. Our finding suggests that hydrogen bonding donating properties of the silica surface plays a dominant role in determining the interfacial behavior of these solutes. The silica surface also had pronounced effects on the time dependent emission of some solutes. In particular, the strong hydrogen bond donating properties of the silica surface inhibit formation of a planar, charge transfer state through hydrogen bond donation to the solute's amine group. A consequence of this interaction is that the time dependent emission from solutes adsorbed at the surface appears to be more similar to emission from solutes in nonpolar solvation environments. To test the role of solvent identity on the photophysical properties of adsorbed solutes, additional experiments were carried out with a nonpolar solvent (decane), a moderately polar solvent (n-decanol) and a polar aprotic solvent (acetonitrile). The results from these studies demonstrated that interfacial solvation depends sensitively on a balance of competing forces including those between the solute and substrate, the solute and solvent and the surface and adjacent solvent.

Roy, Debjani

106

Excitations are localized and relaxation is hierarchical in glass-forming liquids  

E-print Network

For several atomistic models of glass formers, at conditions below their glassy dynamics onset temperatures, ${T_\\mathrm{o}}$, we use importance sampling of trajectory space to study the structure, statistics and dynamics of excitations responsible for structural relaxation. Excitations are detected in terms of persistent particle displacements of length $a$. At supercooled conditions, for $a$ of the order of or smaller than a particle diameter, we find that excitations are associated with correlated particle motions that are sparse and localized, occupying a volume with an average radius that is temperature independent and no larger than a few particle diameters. We show that the statistics and dynamics of these excitations are facilitated and hierarchical. Excitation energy scales grow logarithmically with $a$. Excitations at one point in space facilitate the birth and death of excitations at neighboring locations, and space-time excitation structures are microcosms of heterogeneous dynamics at larger scales. This nature of dynamics becomes increasingly dominant as temperature $T$ is lowered. We show that slowing of dynamics upon decreasing temperature below $T_\\mathrm{o}$ is the result of a decreasing concentration of excitations and concomitant growing hierarchical length scales, and further that the structural relaxation time $\\tau$ follows the parabolic law, $\\log(\\tau / \\tau_\\mathrm{o}) = J^2(1/T - 1/T_\\mathrm{o})^2$, for $T

Aaron S. Keys; Lester O. Hedges; Juan P. Garrahan; Sharon C. Glotzer; David Chandler

2014-05-07

107

Cryogenic exciter  

DOEpatents

The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

2012-03-13

108

YIELDS OF IONS AND EXCITED STATES IN NONPOLAR LIQUIDS EXPOSED TO X-RAYS OF 1 TO 30 KEV ENERGY  

SciTech Connect

When x-rays from a synchrotron source are absorbed in a liquid, the x-ray energy (E{sub x}) is converted by the photoelectric effect into the kinetic energy of the electrons released. For hydrocarbons, absorption by the K-electrons of carbon dominates. Thus the energy of the photoelectron (E{sub pe}) is E{sub x}-E{sub b}, where E{sub b} is the K-shell binding energy of carbon. Additional electrons with energy equal to E{sub b} is released in the Auger process that fills the hole in the K-shell. These energetic electrons will produce many ionizations, excitations and products. The consequences of the high density of ionizations and excitations along the track of the photoelectron and special effects near the K-edge are examined here.

HOLROYD,R.A.

1999-08-18

109

Role of structural relaxations and vibrational excitations in the high-frequency dynamics of liquids and glasses.  

PubMed

We present theoretical investigation on the high-frequency collective dynamics in liquids and glasses at microscopic length scales and in the terahertz frequency region based on the mode-coupling theory for ideal liquid-glass transition. We focus on recently investigated issues from inelastic-x-ray-scattering and computer-simulation studies for dynamic structure factors and longitudinal and transversal current spectra: the anomalous dispersion of the high-frequency sound velocity and the nature of the low-frequency excitation called the boson peak. It will be discussed how the sound mode interferes with other low-lying modes present in the system. Thereby, we provide a systematic explanation of the anomalous sound-velocity dispersion in systems--ranging from high temperature liquid down to deep inside the glass state--in terms of the contributions from the structural-relaxation processes and from vibrational excitations called the anomalous-oscillation peak (AOP). A possibility of observing negative dispersion--the decrease of the sound velocity upon increase of the wave number--is argued when the sound-velocity dispersion is dominated by the contribution from the vibrational dynamics. We also show that the low-frequency excitation, observable in both of the glass-state longitudinal and transversal current spectra at the same resonance frequency, is the manifestation of the AOP. As a consequence of the presence of the AOP in the transversal current spectra, it is predicted that the transversal sound velocity also exhibits the anomalous dispersion. These results of the theory are demonstrated for a model of the Lennard-Jones system. PMID:17025616

Chong, Song-Ho

2006-09-01

110

Effects of long-wavelength fluorescence excitation in liquid solutions of N-pyrrolobenzonitrile  

NASA Astrophysics Data System (ADS)

The absorption, dual fluorescence, and fluorescence excitation spectra of N-pyrrolobenzonitrile (P5C) in a set of solvents with different polarities are studied upon irradiation of solutions by light with different photon energies. The dual fluorescence from the locally excited Frank-Condon and charge-transfer states are recorded in all cases. The change in the excitation photon energy does not affect the fluorescence band positions, but noticeably changes the intensity ratio between the bands in favor of the long-wavelength band belonging to the charge-transfer state. The effects observed are explained using the data of quantum-mechanical calculations, which demonstrate that the solutions of these systems can very likely contain rotational isomers with different pyrrole orientations with respect to the benzene ring. In the excited state, these isomers have different charge-transfer reaction rates, which leads to different intensity ratios of the recorded fluorescence bands.

Tomin, V. I.; Hubisz, K.

2011-05-01

111

Luttinger-field approach to thermoelectric transport in nanoscale conductors  

NASA Astrophysics Data System (ADS)

Thermoelectric transport in nanoscale conductors is analyzed in terms of the response of the system to a thermomechanical field, first introduced by Luttinger, which couples to the electronic energy density. While in this approach, the temperature remains spatially uniform, we show that a spatially varying thermomechanical field effectively simulates a temperature gradient across the system and allows us to calculate the electric and thermal currents that flow due to the thermomechanical field. In particular, we show that in the long-time limit, the currents thus calculated reduce to those that one obtains from the Landauer-Büttiker formula, suitably generalized to allow for different temperatures in the reservoirs, if the thermomechanical field is applied to prepare the system, and subsequently turned off at t =0. Alternatively, we can drive the system out of equilibrium by switching the thermomechanical field after the initial preparation. We compare these two scenarios, employing a model noninteracting Hamiltonian, in the linear regime, in which they coincide, and in the nonlinear regime, in which they show marked differences. We also show how an operationally defined local effective temperature can be computed within this formalism.

Eich, F. G.; Principi, A.; Di Ventra, M.; Vignale, G.

2014-09-01

112

Energy spectrum of one-particle excitations in liquid dielectrics under high pressures and temperatures  

Microsoft Academic Search

The effect of pressure on the conductivity of molecular liquids (hydrogen, oxygen, and nitrogen) and alkali metals (cesium and rubidium) in the region of the experimentally observed dielectric-metal transition is investigated. It is shown that capture of free electrons by atoms or molecules (resulting in the formation of negative ions) is advantageous from the point of view of energy in

A. G. Khrapak; V. E. Fortov

2008-01-01

113

Energy spectrum of one-particle excitations in liquid dielectrics under high pressures and temperatures  

Microsoft Academic Search

The effect of pressure on the conductivity of molecular liquids (hydrogen, oxygen, and nitrogen) and alkali metals (cesium\\u000a and rubidium) in the region of the experimentally observed dielectric-metal transition is investigated. It is shown that capture\\u000a of free electrons by atoms or molecules (resulting in the formation of negative ions) is advantageous from the point of view\\u000a of energy in

A. G. Khrapak; V. E. Fortov

2008-01-01

114

Bose Einstein condensation: Its role in the excitations of liquid helium and in trapped Bose gases  

Microsoft Academic Search

The role of Bose-Einstein condensation (BEC) in determining the properties of Bose systems at ultracold temperatures is investigated. First, we present a model of the dynamic structure factor S(Q,o) of liquid 4He as observed in inelastic neutron scattering measurements beyond the roton (Q ≳ 2.0 A-1). We separate the dynamic susceptibility into chi = chiS + chi'R. chi S involves

Asaad R. Sakhel

2004-01-01

115

The {alpha}-particle excited scintillation response of the liquid phase epitaxy grown LuAG:Ce thin films  

SciTech Connect

Liquid phase epitaxy grown Lu{sub 3}Al{sub 5}O{sub 12}:Ce (LuAG:Ce) 20 {mu}m thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time (0.5-10 {mu}s). {sup 241}Am ({alpha} particles) was used for excitation. At the 0.5 {mu}s shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of Pb{sup 2+} contamination in the films (from the flux) and antisite Lu{sub Al} defect in bulk material is discussed.

Prusa, P.; Cechak, T.; Mares, J. A.; Nikl, M.; Beitlerova, A.; Solovieva, N.; Zorenko, Yu. V.; Gorbenko, V. I.; Tous, J.; Blazek, K. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 11519 Prague (Czech Republic); Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Laboratory of Optoelectronic Materials, Ivan Franko National University of Lviv, 107 Gen. Tarnavskyj Str., 79017 Lviv (Ukraine); Crytur Ltd., Palackeho 175, 51101 Turnov (Czech Republic)

2008-01-28

116

Effect of an external field on a modification of Luttinger's many-fermion model  

SciTech Connect

A modification is given of Luttinger's one-dimensional model of interacting fermions to incorporate both Fermi surfaces using one physical type of particle. The system is solved in the presence of an arbitrary external field, with linear response and pair correlation functions readily computed. These constitute and explicit realization of a relation associated with the random phase approximation.

Orfanopoulos, B.A.; Percus, J.K.

1987-02-01

117

Spiral and target patterns in bivalve nacre manifest a natural excitable medium from layer growth of a biological liquid crystal  

PubMed Central

Nacre is an exquisitely structured biocomposite of the calcium carbonate mineral aragonite with small amounts of proteins and the polysaccharide chitin. For many years, it has been the subject of research, not just because of its beauty, but also to discover how nature can produce such a superior product with excellent mechanical properties from such relatively weak raw materials. Four decades ago, Wada [Wada K (1966) Spiral growth of nacre. Nature 211:1427] proposed that the spiral patterns in nacre could be explained by using the theory Frank [Frank F (1949) The influence of dislocations on crystal growth. Discuss Faraday Soc 5:48–54] had put forward of the growth of crystals by means of screw dislocations. Frank's mechanism of crystal growth has been amply confirmed by experimental observations of screw dislocations in crystals, but it is a growth mechanism for a single crystal, with growth fronts of molecules. However, the growth fronts composed of many tablets of crystalline aragonite visible in micrographs of nacre are not a molecular-scale but a mesoscale phenomenon, so it has not been evident how the Frank mechanism might be of relevance. Here, we demonstrate that nacre growth is organized around a liquid-crystal core of chitin crystallites, a skeleton that the other components of nacre subsequently flesh out in a process of hierarchical self-assembly. We establish that spiral and target patterns can arise in a liquid crystal formed layer by layer through the Burton–Cabrera–Frank [Burton W, Cabrera N, Frank F (1951) The growth of crystals and the equilibrium structure of their surfaces. Philos Trans R Soc London Ser A 243:299–358] dynamics, and furthermore that this layer growth mechanism is an instance of an important class of physical systems termed excitable media. Artificial liquid crystals grown in this way may have many technological applications. PMID:19528636

Cartwright, Julyan H. E.; Checa, Antonio G.; Escribano, Bruno; Sainz-Díaz, C. Ignacio

2009-01-01

118

Boson localization and excitations of liquid {sup 4}He confined in gelsil  

SciTech Connect

We present neutron scattering measurements of the phonon-roton (P-R) modes of liquid {sup 4}He at saturated vapor pressure confined in 44 A mean pore diameter gelsil in the wave vector range 0.4{<=}Q{<=}2.15 A{sup -1}. Layer modes, modes which propagate in the liquid layers adjacent to the porous media walls, were also observed at wave vectors in the roton region (Q{approx_equal}1.95 A{sup -1}) but not at Q < or approx. 1.7 A{sup -1}. The first goal is to document the filling dependence of the dynamic response and of the P-R mode energies and widths more systematically than has been done in the past. As the gelsil is filled with {sup 4}He, the P-R and layer modes are first observed at a fractional filling of f=76% at low temperature (T=0.4 K). At fillings f=76%, the P-R mode energies lie below the bulk superfluid {sup 4}He values in the wave vector range 0.4{<=}Q{<=}1.7 A{sup -1}, especially at Q{approx_equal}1.1 A{sup -1}, as observed in helium films. As filling is increased, the intensity in the P-R mode increases markedly and the P-R mode energies move toward bulk superfluid values taking bulk values at full filling. The second goal is to determine the temperature dependence of the intensity in the P-R modes in a media in which the superfluid-normal transition temperature T{sub c}=1.92 K is independently known and lies well below the bulk liquid value T{sub {lambda}}=2.17 K. As temperature is increased, the intensity in the P-R and layer modes decreases. However, a well-defined P-R mode is observed at temperatures up to T{approx_equal}2.15 K, above T{sub c}=1.92 K. Since well-defined modes exist because there is Bose-Einstein condensation (BEC), this suggests that there is BEC above T{sub c}, probably localized. Localized BEC appears to exist up to T{approx_equal}T{sub {lambda}}.

Albergamo, Francesco [European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble Cedex (France); Bossy, Jacques [Centre de Recherche sur les Tres Basses Temperatures, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Pearce, Jonathan V. [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States); Schober, Helmut [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Glyde, Henry R. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States)

2007-08-01

119

Neutron-scattering investigation of the excitation spectrum of liquid helium  

SciTech Connect

The results of the investigation of the temperature evolution of the scattering law S(Q, {omega}) of superfluid helium measured in the wave-vector range 0.3 < Q < 0.8 A{sup -1} and helium temperatures from 1.0 to 2.2 K are reported. The investigations have been performed on the high-flux reactor at the Institut Laue-Langevin (France) with the IN6 neutron inelastic-scattering spectrometer. The deviation of the experimental scattering law of liquid helium from the damping harmonic oscillator model, which was previously observed independently in the experiments with the IN6 spectrometer and with the DIN-2PI spectrometer (at the IBR-2 reactor, Dubna, Russia) and were more recently called extrapeak, has been corroborated. The temperature dependence of the extrapeak parameters has been determined. This dependence makes it possible to propose hypotheses on the nature of the extrapeak.

Kalinin, I. V. [Institute of Physics and Power Engineering (Russian Federation)], E-mail: kaliv@ippe.ru; Lauter, H. [Institut Laue-Langevin (France); Puchkov, A. V. [Institute of Physics and Power Engineering (Russian Federation)

2007-07-15

120

Microscopic calculations of the excitation spectrum of one 3He impurity in liquid 4He  

NASA Astrophysics Data System (ADS)

We calculate the chemical potential ?0 and the effective mass m*/m3 of one 3He impurity in liquid 4He. First a variational wave function including two- and three-particle dynamical correlations is adopted. Triplet correlations bring the computed values of ?0 very close to the experimental results. The variational estimate of m*/m3 includes also backflow correlations between the 3He atom and the particles in the medium. Different approximations for the three-particle distribution function give almost the same values for m*/m3. The variational approach underestimates m*/m3 by ~10% at all of the considered densities. Correlated-basis perturbation theory is then used to improve the wave function to include backflow around the particles of the medium. The perturbative series built up with one-phonon states only is summed up to infinite order and gives results very close to the variational ones. All the perturbative diagrams with two independent phonons have then been summed to compute m*/m3. Their contribution depends to some extent on the form used for the three-particle distribution function. When the scaling approximation is adopted, a reasonable agreement with the experimental results is achieved.

Fabrocini, A.; Fantoni, S.; Rosati, S.; Polls, A.

1986-05-01

121

Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon  

SciTech Connect

A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin's resonant energy transfer hopping mechanism.

Peterson, E.S.

1992-08-01

122

Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon  

SciTech Connect

A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin`s resonant energy transfer hopping mechanism.

Peterson, E.S.

1992-08-01

123

Quantum oscillations in the Luttinger model with quadratic band touching: Applications to pyrochlore iridates  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments on Pr2Ir2O7 , we provide a theory of quantum oscillations in the Luttinger model with quadratic band touching, modeled for the spin-orbit-coupled conduction electrons in pyrochlore iridates. The magneto- and Hall resistivities are computed for electron- and hole-doped systems, and the corresponding Shubnikov-de Haas (SdH) signals are investigated. The SdH signals are characterized by aperiodic behaviors that originate from the unconventional Landau level structures of the Luttinger model near the neutrality point, such as inter-Landau-level crossing, nonuniform Landau level spacings, and nonparabolic dispersions along the applied magnetic-field direction. The aperiodic SdH signals observed in the paramagnetic state of Pr2Ir2O7 are shown to be consistent with such behaviors, justifying the use of the Luttinger model and the quadratic band touching spectrum as excellent starting points for physics of pyrochlore iridates. The implications of these results are discussed in light of recent theoretical and experimental developments in these systems.

Rhim, Jun-Won; Kim, Yong Baek

2015-03-01

124

{open_quote}{open_quote}Fermi liquid{close_quote}{close_quote} shell model approach to composite fermion excitation spectra in fractional quantum Hall states  

Microsoft Academic Search

Numerical results for the energy spectra of {ital N} electrons on a spherical surface are used as input data to determine the quasiparticle energies and the pairwise {open_quote}{open_quote}Fermi liquid{close_quote}{close_quote} interactions of composite fermion (CF) excitations in fractional quantum Hall systems. The quasiparticle energies and their interactions are then used to determine the energy spectra, {ital E} vs total angular momentum

P. Sitko; S. N. Yi; K. S. Yi; J. J. Quinn

1996-01-01

125

Critical spectral statistics as the Luttinger liquid of energy levels at a finite temperature  

Microsoft Academic Search

We review the recent results on the energy level statistics in disordered conductors near the Anderson localization transition and other critical systems with multifractal eigenstates. We focus on the critical random matrix ensemble (CRMT) suggested by Mirlin and Fyodorov as a possible generic description of the critical parametric spectral statistics (CPSS). We show that in the region of large energy

V. E. Kravtsov

1999-01-01

126

Transport properties of a two-lead Luttinger-liquid junction out of equilibrium: Fermionic representation  

NASA Astrophysics Data System (ADS)

The electrical current through an arbitrary junction connecting quantum wires of spinless interacting fermions is calculated in fermionic representation. The wires are adiabatically attached to two reservoirs at chemical potentials differing by the applied voltage bias. The relevant scale-dependent contributions in perturbation theory in the interaction up to infinite order are evaluated and summed up. The result allows one to construct renormalization group equations for the conductance as a function of voltage (or temperature, wire length). There are two fixed points at which the conductance follows a power law in terms of a scaling variable ? , which equals the bias voltage V , if V is the largest energy scale compared to temperature T and inverse wire length L-1, and interpolates between these quantities in the crossover regimes.

Aristov, D. N.; Wölfle, P.

2014-12-01

127

John Bardeen and the Theory of Superconductivity: A Late Revision of a Homework Assignment for J. M. Luttinger  

Microsoft Academic Search

This account of the history of the Bardeen–Cooper–Schrieffer theory of superconductivity has its roots in an assignment that Quin Luttinger designed for me in 1963 when I was his graduate student. It improves on my student work by tracing the story from historical source materials as well as published papers, thus reflecting the contingencies and human elements that shape all

Lillian Hoddeson

2001-01-01

128

Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation.  

PubMed

Time-resolved photoelectron spectroscopy is performed on thymine and thymidine in aqueous solution to study the excited-state relaxation dynamics of these molecules. We find two contributions with sub-ps lifetimes in line with recent excited-state QM/MM molecular dynamics simulations (J. Chem. Phys. 2013, 139, 214304). The temporal evolution of ionization energies for the excited ??* state along the QM/MM molecular dynamics trajectories were calculated and are compatible with experimental results, where the two contributions correspond to the relaxation paths in the ??* state involving different conical intersections with the ground state. Theoretical calculations also show that ionization from the n?* state is possible at the given photon energies, but we have not found any experimental indication for signal from the n?* state. In contrast to currently accepted relaxation mechanisms, we suggest that the n?* state is not involved in the relaxation process of thymine in aqueous solution. PMID:25671554

Buchner, Franziska; Nakayama, Akira; Yamazaki, Shohei; Ritze, Hans-Hermann; Lübcke, Andrea

2015-03-01

129

Universal topological data for gapped quantum liquids in three dimensions and fusion algebra for non-Abelian string excitations  

NASA Astrophysics Data System (ADS)

Recently we conjectured that a certain set of universal topological quantities characterize topological order in any dimension. Those quantities can be extracted from the universal overlap of the ground-state wave functions. For systems with gapped boundaries, these quantities are representations of the mapping class group MCG (M ) of the space manifold M on which the systems live. We will here consider simple examples in three dimensions and give physical interpretation of these quantities, related to the fusion algebra and statistics of particles and string excitations. In particular, we will consider dimensional reduction from 3+1D to 2+1D, and show how the induced 2+1D topological data contain information on the fusion and the braiding of non-Abelian string excitations in 3D. These universal quantities generalize the well-known modular S and T matrices to any dimension.

Moradi, Heidar; Wen, Xiao-Gang

2015-02-01

130

Tritium effluent control project progress report, July--September 1975. [Tritiated liquid waste decontamination by molecular excitation, electrolysis of high-level tritiated water, and catalytic exchange detritiation studies  

Microsoft Academic Search

In the Tritiated Liquid Waste Decontamination (Molecular Excitation) program, it was found that a 1\\/4'' Nd:YAG amplifier and a Faraday rotator isolator must be added to the oscillator to obtain the required power for the laser excitation experiments. The isotopic selectivity of the two-photon dissociation process was examined in more detail. The selectivity or ratio of HTO to HO molecules

C. J. Kershner; J. C. Bixel

1976-01-01

131

Ultraviolet excitation of remote phosphor with symmetrical illumination used in dual-sided liquid-crystal display.  

PubMed

The UV-excited flat lighting (UFL) technique differs from conventional fluorescent lamp or LED illumination. It involves using a remote phosphor film to convert the wavelength of UV light to visible light, achieving high brightness and planar and uniform illumination. In particular, UFL can accomplish compact size, low power consumption, and symmetrical dual-sided illumination. Additionally, UFL utilizes a thermal radiation mechanism to release the large amount of heat that is generated upon illumination without thermal accumulation. These characteristics of the UFL technique can motivate a wide range of lighting applications in thin-film transistor LCD backlighting or general lighting. PMID:20680053

Huang, Hsin-Tao; Tsai, Chuang-Chuang; Huang, Yi-Pai

2010-08-01

132

Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV  

E-print Network

Transient absorption measurements monitor the geminate recombination kinetics of solvated electrons following two-photonionization of liquid water at several excitation energies in the range from 8.3to12.4eV. Modeling the kinetics of the electron...

Elles, Christopher G.; Jailaubekov, Askat E.; Crowell, Robert A.; Bradforth, Stephen E.

2006-07-28

133

Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air.  

PubMed

In this study, a bipolar nanosecond pulse with 20ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency. PMID:24845733

Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

2014-10-15

134

Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air  

NASA Astrophysics Data System (ADS)

In this study, a bipolar nanosecond pulse with 20 ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390 K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency.

Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

2014-10-01

135

VOLUME 79, NUMBER 25 P H Y S I C A L R E V I E W L E T T E R S 22 DECEMBER 1997 Coulomb Interactions and Mesoscopic Effects in Carbon Nanotubes  

E-print Network

renormalized Luttinger liquid. At high temperatures, we find anomalous temperature dependences-Tc superconductors, and inclusions in composites for body armor. One of the most exciting prospects from the point temperatures, an isolated armchair nanotube should behave as a Luttinger liquid, with an anomalous power

Kane, Charles

136

Corrections to the Kohn-Luttinger wave function for donors in silicon  

NASA Astrophysics Data System (ADS)

Corrections to the Kohn-Luttinger ground state wave function from subsidiary minima are calculated using first order perturbation theory and a variational approach. The very precise Fermi contact constants ahpf(Rnmm) of the Hale-Mieher data determine a set of linear equations based on donor-dependent ratios such as ??d(333&barbelow;)?/??d(115)?=Kd=[ahpf(333&barbelow;)/ahpf(115)]1/2 . The minima considered [ L1(cb1) , ?2'(cb4) , ?(cb5) , ?W(cb2) , ?2'(cb5) , and XU(cb2) ] are each characterized by an A(k-kj) , a phase eikj?r and envelope functions F?j (?=x,y,z) . The ?d employed contains four terms not included in the comprehensive Ivey-Mieher (IM) calculation with pseudopotential Bloch functions for eight bands. Two terms arise from the crucial tetrahedral potential Ut?xyzf(r) ignored in most earlier work. The admixture coefficients are varied subject to the three constraint equations to minimize the mean-squared deviations of the calculated and experimental ahpf(nnm) of the 11 odd sites identified by IM. The results are not only vastly improved (compared to IM) for site (111) but also reverse the IM assignments for (331) and (551). Some of the inverted donor anomalies are explained. The average root-mean-squared deviation ?rmsd? for the 11 sites is better than the IM results for these odd sites. The results suggest that additional changes in the zeroth order ?KL may be required to improve the overall agreement. The uniaxial stress parameters id and 2f/a(0) are also reconsidered with some of the new corrections and compared with experimental values.

Castner, T. G., Jr.

2008-05-01

137

Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source for laser ablation-generated aerosols: parametric dependence and robustness to particle loading.  

PubMed

Liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma is being developed as a secondary vaporization-excitation source for the optical emission analysis of laser ablation (LA)-generated particle populations. The practicalities of this coupling are evaluated by determining the influence of source parameters on the emission response and the plasma's robustness upon LA introduction of easily ionized elements (EIEs). The influence of discharge current (45-70 mA), LA carrier gas flow rate (0.1-0.8 L min(-1)), and electrode separation distance (0.5-3.5 mm) was studied by measuring Cu emission lines after ablation of a brass sample. Best emission responses were observed for high-discharge currents, low He carrier gas flow rates, and relatively small (<1.5 mm) electrode gaps. Plasma robustness and spectroscopic matrix effects were studied by monitoring Mg(II) : Mg(I) intensity ratios and N2-derived plasma rotational temperatures after the ablation of Sr- and Ca-containing pellets. Plasma robustness investigations showed that the plasma is not appreciably affected by the particle loadings, with the microplasma being slightly more ionizing in the case of Ca introduction. In neither case did the concentration of the concomitant element change the robustness values, implying a high level of robustness. Introduction of the LA particles results in slight increases in the rotational temperatures (?10% relative), with Ca-containing particles having a greater effect than Sr-containing particles. The observed variation of 9% in the plasma rotational temperature is in the same order of magnitude as the short-term reproducibility determined by the proposed LA-LS-APGD system. The determined rotational temperatures ranged from 1047 to 1212 K upon introducing various amounts of Ca and Sr. The relative immunity to LA particle-induced matrix effects is attributed to the relatively long residence times and high power densities (>10 W mm(-3)) of the LS-APGD microplasma. PMID:25506884

Manard, Benjamin T; Konegger-Kappel, Stefanie; Gonzalez, Jhanis J; Chirinos, Jose; Dong, Meirong; Mao, Xianglei; Marcus, R Kenneth; Russo, Richard E

2015-01-01

138

Towards an easy-to-use tuberculosis diagnosis through exhaled breath analysis: a liquid fluorimeter with an excitation at 265 nm  

NASA Astrophysics Data System (ADS)

The struggle against tuberculosis is one of the World Health Organization priorities. Identifying in a short time, patients with active tuberculosis, would bring a tremendous improvement to the current situation. Recovering from this infectious and deadly disease (2 million of death per year) is possible with a correct diagnosis to give an appropriate treatment. Unfortunately, most common tuberculosis diagnoses have few drawbacks: - skin tests: not reliable at 100% and need an incubation of 2 days before the diagnosis, - blood tests: costly and sophisticated technology, - chest X-ray: the first step before the sputum tests used for a bacterial culture with a final diagnosis given within 2 weeks. A tuberculosis test based on exhaled breath analysis is a prospective and noninvasive solution, cheap and easy to use and to transport. This test lies on a fluoregenic detection of niacin, a well-known mycobacterium tuberculosis specific metabolite. In this paper, it is assumed that the selected probe is specific to niacin and that exhaled breath does not contain any interfering species. To address this problem, a fluorimeter is developed with a cheap and cooled CCD (? 2k$) as a sensor, to easily determine the suitable "fluorescent zone". In comparing aqueous solutions with and without niacin, 250 pM of niacin have been detected. With a commercial fluorimeter (Fluorolog from Horiba), only 200 nM of niacin are detected. The present detection remains 10 times above the estimated targeted value for a tuberculosis test. The excitation source is a LED, which typically emits 20 °W at 265 nm through an optical fiber. The emission signal is detected around 545 nm. A typical light exposure lasts 700 seconds. Analysis of biomarkers with a liquid fluorimeter is generic and promising as health diagnosis.

Hue, J.; Dupoy, M.; Vignoud, S.; Ricaud, J. L.; Tran-Thi, T.; Karpe, S.; Novelli-Rousseau, A.; Mallard, F.

2013-03-01

139

Non-Fermi-liquid behavior in the fluctuating gap model: From the pole to a zero of the Green's function  

SciTech Connect

We analyze the non-Fermi-liquid (NFL) behavior of the fluctuating gap model (FGM) of pseudogap behavior in both one and two dimensions. A detailed discussion of quasiparticle renormalization (Z-factor) is given, demonstrating a kind of marginal Fermi-liquid or Luttinger-liquid behavior and topological stability of the bare Fermi surface (the Luttinger theorem). In the two-dimensional case, we discuss the effective picture of the Fermi surface destruction both in the hot spot model of dielectric (AFM, CDW) pseudogap fluctuations and for the qualitatively different case of superconducting d-wave fluctuations, reflecting the NFL spectral density behavior and similar to that observed in ARPES experiments on copper oxides.

Kuchinskii, E. Z.; Sadovskii, M. V. [Russian Academy of Sciences, Institute for Electrophysics (Russian Federation)], E-mail: sadovski@iep.uran.ru

2006-09-15

140

Identifying a bath-induced bose liquid in interacting spin-boson models.  

PubMed

We study the ground state phase diagram of a one-dimensional hard-core bosonic model with nearest-neighbor interactions (XXZ model) where every site is coupled Ohmically to an independent but identical reservoir, hereby generalizing spin-boson models to interacting spin-boson systems. We show that a bath-induced Bose liquid phase can occur in the ground state phase diagram away from half filling. This phase is compressible, gapless, and conducting but not superfluid. At half filling, only a Luttinger liquid and a charge density wave are found. The phase transition between them is of Kosterlitz-Thouless type where the Luttinger parameter takes a nonuniversal value. The applied quantum Monte Carlo method can be used for all open bosonic and unfrustrated spin systems, regardless of their dimension, filling factor, and spectrum of the dissipation as long as the quantum system couples to the bath via the density operators. PMID:25615290

Cai, Zi; Schollwöck, Ulrich; Pollet, Lode

2014-12-31

141

Identifying a Bath-Induced Bose Liquid in Interacting Spin-Boson Models  

NASA Astrophysics Data System (ADS)

We study the ground state phase diagram of a one-dimensional hard-core bosonic model with nearest-neighbor interactions (X X Z model) where every site is coupled Ohmically to an independent but identical reservoir, hereby generalizing spin-boson models to interacting spin-boson systems. We show that a bath-induced Bose liquid phase can occur in the ground state phase diagram away from half filling. This phase is compressible, gapless, and conducting but not superfluid. At half filling, only a Luttinger liquid and a charge density wave are found. The phase transition between them is of Kosterlitz-Thouless type where the Luttinger parameter takes a nonuniversal value. The applied quantum Monte Carlo method can be used for all open bosonic and unfrustrated spin systems, regardless of their dimension, filling factor, and spectrum of the dissipation as long as the quantum system couples to the bath via the density operators.

Cai, Zi; Schollwöck, Ulrich; Pollet, Lode

2014-12-01

142

The Kohn-Luttinger mechanism and phase diagram of the superconducting state in the Shubin-Vonsovsky model  

SciTech Connect

Using the Shubin-Vonsovsky model in the weak-coupling regime W > U > V (W is the bandwidth, U is the Hubbard onsite repulsion, and V is the Coulomb interaction at neighboring sites) based on the Kohn-Luttinger mechanism, we determined the regions of the existence of the superconducting phases with the d{sub xy}, p, s, and d{sub x{sup 2}-y{sup 2}} symmetry types of the order parameter. It is shown that the effective interaction in the Cooper channel considerably depends not only on single-site but also on intersite Coulomb correlations. This is demonstrated by the example of the qualitative change and complication of the phase diagram of the superconducting state. The superconducting (SC) phase induction mechanism is determined taking into account polarization contributions in the second-order perturbation theory in the Coulomb interaction. The results obtained for the angular dependence of the superconducting gap in different channels are compared with angule-resolved photoemission spectroscopy (ARPES) results. The influence of long-range hops in the phase diagram and critical superconducting transition temperature in different channels is analyzed. The conditions for the appearance of the Kohn-Luttinger superconductivity with the d{sub x{sup 2}-y{sup 2}} symmetry and high critical temperatures T{sub c} {approx} 100 K near the half-filling are determined.

Kagan, M. Yu., E-mail: kagan@kapitza.ras.ru [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation); Val'kov, V. V.; Mitskan, V. A.; Korovuskin, M. M. [Russian Academy of Sciences, Kirenskii Physics Institute, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Kirenskii Physics Institute, Siberian Branch (Russian Federation)

2013-10-15

143

Ferromagnetic spin-orbital liquid of dipolar fermions in zigzag lattices  

NASA Astrophysics Data System (ADS)

Two-component dipolar fermions in zigzag optical lattices allow for the engineering of spin-orbital models. We show that dipolar lattice fermions permit the exploration of a regime typically unavailable in solid-state compounds that is characterized by a spin-liquid phase with a finite magnetization and spontaneously broken SU(2) symmetry. This peculiar spin liquid may be understood as the Luttinger liquid of composite particles consisting of bound states of spin waves and orbital domain walls moving in an unsaturated ferromagnetic background. In addition, we show that the system exhibits a boundary phase transitions involving nonlocal entanglement of edge spins.

Sun, G.; Kolezhuk, A. K.; Santos, L.; Vekua, T.

2014-04-01

144

Luttinger liquid in a finite one-dimensional wire with box-like boundary conditions Fabrizio Anfuso1,2  

E-print Network

- teresting effects in such one-dimensional many-body systems and systematically change the shape visualization of the effect of interactions on the wave function and the energy quantization. In particular of an electron wave function. For the noninteracting case, this is given by a standing wave at the Fermi wave

Eggert, Sebastian

145

Luttinger liquid in a finite onedimensional wire with boxlike boundary conditions Fabrizio Anfuso 1,2 and Sebastian Eggert 1  

E-print Network

­ teresting effects in such one­dimensional many­body systems and systematically change the shape visualization of the effect of interactions on the wave function and the energy quantization. In particular as the square of an electron wave function. For the noninteracting case, this is given by a standing wave

Eggert, Sebastian

146

Persistence of bending and torsional modes in piezoelectric-excited millimeter-sized cantilever (PEMC) sensors in viscous liquids - 1 to 103 cP  

NASA Astrophysics Data System (ADS)

Cantilever sensors consisting of only a piezoelectric layer express both bending and torsional modes near ˜25 kHz that persist with reasonable Q-values (˜15) in liquids of high viscosity (>100 cP). Responses of both bending and torsional modes in liquids (1-1019 cP) were measured simultaneously. The bending mode response was more sensitive to mass-change effects than the torsional mode, and the response in liquids <70 cP matched theoretical values within 0.9%. At 1019 cP the bending mode response was within 10.4% of theory. The bending and torsional modes in PEMC can potentially be used simultaneously for bio-chemical sensing in very viscous samples.

Johnson, Blake N.; Mutharasan, Raj

2011-03-01

147

Transmitting Electromagnetic Energy into Liquids  

NASA Technical Reports Server (NTRS)

Rough liquid surface enhances coupling. Agitating surface of liquid nitrogen bath with periodic or aperiodic excitation enhances electromagnetic coupling between microwave horn and blackbody temperature standard immersed in liquid. Useful in interfaces between electromagnetic radiation and liquids. Biomedical, radar, and meteorological applications.

Johnston, E. J.

1984-01-01

148

P cell excitability AP excitability  

E-print Network

AP (mV) P (mV) DP(15) (ipsi) DP(15) (contra) ba d P cell excitability Vm I (nA) AP excitability Vm) Measurement of input resistance of P and cell 212 and the amplitude of the P-to-cell 212 synaptic potential. We hyperpolarized cell 212 to prevent it from generating action potentials during P cell stimulations

Gaudry, Quentin

149

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

150

Magnetostrictive resonance excitation  

DOEpatents

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

1992-01-01

151

Ionization and excitation cross sections for the interaction of HZE particles in liquid water and application to Monte Carlo simulation of radiation tracks  

NASA Astrophysics Data System (ADS)

Relativistic heavy ions of high charge (Z) and energy (E) (HZE) in galactic cosmic rays (GCR) are important contributors to space radiation risk because they cannot be shielded completely and their relative biological effectiveness is very high. To understand these risks, Monte Carlo track structure simulations by radiation transport codes are widely used in radiation biology to provide information on energy deposition and production of radiolytic species that damage cellular structures. In this paper, we show that relativistic corrections can be applied to existing semi-empirical cross section models for the ionization and excitation of water molecules by ions to extend the validity of their energy range up to ~104 MeV amu-1. Similarly, an effective charge value correction is applied for Z>2 ions. Simulations of HZE tracks have been performed by a new C++ Monte Carlo transport code, named RITRACKS, that uses these cross sections to calculate the stopping power, radial dose, XY-plane projections of track segments and radial distributions of primary radiolytic species (H•, •OH, H2, H2O2 and e-aq) at ~10-12 s. These new data will be useful to understand results from experiments performed at ion accelerators by discriminating the role of the so-called core and penumbra of the tracks.

Plante, Ianik; Cucinotta, Francis A.

2008-12-01

152

White-Light-Exciting, Layer-by-Layer-Assembled ZnCdHgSe Quantum Dots/Polymerized Ionic Liquid Hybrid Film for Highly Sensitive Photoelectrochemical Immunosensing of Neuron Specific Enolase.  

PubMed

ZnCdHgSe quantum dots (QDs) functionalized with N-acetyl-l-cysteine were synthesized and characterized. Through layer-by-layer assembling, the ZnCdHgSe QDs was integrated with a polymerized 1-decyl-3-[3-pyrrole-1-yl-propyl]imidazolium tetrafluoroborate (PDPIT) ionic liquid film modified indium tin oxide (ITO) electrode to fabricated a photoelectrochemical interface for the immobilization of rabbit antihuman neuron specific enolase (anti-NSE). After being treated with glutaraldehyde vapor and bovine serum albumin successively, an anti-NSE/ZnCdHgSe QDs/PDPIT/ITO sensing platform was established. Simplely using a white-light LED as an excitation source, the immunoassay of neuron specific enolase (NSE) was achieved through monitoring the photocurrent variation. The polymerized ionic liquid film was demonstrated to be an important element to enhance the photocurrent response of ZnCdHgSe QDs. The anti-NSE/ZnCdHgSe QDs/PDPIT/ITO based immunosensor presents excellent performances in neuron specific enolase determination. The photocurrent variation before and after being interacted with NSE exhibits a good linear relationship with the logarithm of its concentration (log cNSE) in the range from 1.0 pg mL(-1) to 100 ng mL(-1). The limit of detection of this immunosensor is able to reach 0.2 pg mL(-1) (S/N = 3). The determination of NSE in clinical human sera was also demonstrated using anti-NSE/ZnCdHgSe QDs/PDPIT/ITO electrode. The results were found comparable with those obtained by using enzyme-linked immunosorbent assay method. PMID:25790014

Yu, Xiangyang; Wang, Yanying; Chen, Xuemin; Wu, Kangbing; Chen, Danchao; Ma, Ming; Huang, Zhenjia; Wu, Wangze; Li, Chunya

2015-04-21

153

Excited Delirium  

PubMed Central

Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

2011-01-01

154

Rashba coupling and magnetic order in correlated helical liquids  

NASA Astrophysics Data System (ADS)

We study strongly correlated helical liquids with and without Rashba coupling using quantum Monte Carlo simulations of the Kane-Mele model with a Hubbard interaction at the edge. Independent of the Rashba coupling, we find that interactions enhance spin correlations and suppress the spectral weight at the Fermi level. For sufficiently strong interactions, a gap can be observed in the single-particle spectral function. However, based on a finite-size scaling analysis and theoretical arguments, we argue that this gap is closed by order parameter fluctuations in the Luttinger liquid phase even at zero temperature, and filled in by thermally induced kinks in the order parameter in the Mott phase at finite temperatures. While the bosonization suggests an umklapp-driven Mott transition only in the presence of Rashba coupling and hence a significant impact of the latter, our numerical results are almost unaffected by Rashba coupling even at low temperatures.

Hohenadler, Martin; Assaad, Fakher F.

2014-12-01

155

Universal nature of collective plasmonic excitations in finite 1-D carbon-based nanostructures  

E-print Network

Tomonaga-Luttinger (T-L) theory predicts collective plasmon resonances in 1-D nanostructure conductors of finite length, that vary roughly in inverse proportion to the length of the structure. Yet, such resonances have not been clearly identified in experiments so far. Here we provide evidence of the T-L plasmon resonances using first-principle computational real-time spectroscopy studies of representative finite 1-D carbon-based nanostructures ranging from atom and benzene-like chain structures to short carbon nanotubes. Our all-electron Time-Dependent Density-Functional Theory (TDDFT) real-time simulation framework is capable to accurately capture the relevant nanoscopic effects including correct frequencies for known optical transitions, and various collective plasmon excitations. The presence of 1-D T-L plasmons is universally predicted by the various numerical experiments, which also demonstrate a phenomenon of resonance splitting. Extending these simulations to longer structures will allow the accurate ...

Polizzi, Eric

2015-01-01

156

Deconfined fractionally charged excitation in any dimensions  

SciTech Connect

An exact incompressible quantum liquid is constructed at the filling factor 1/m{sup 2} in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m{sup 2}, the excitation has fractional charge e/m{sup 2}, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/m{sup n}. -- Highlights: ? We demonstrate that the fractionally-charged excitations can in principle exist in any dimensions. ? We compute the fractional charge of the excitations (e{sup ?}=e/m{sup D}). ? We demonstrate that the fractionally-charged excitation is in a deconfined phase.

Chern, Chyh-Hong, E-mail: chchern@ntu.edu.tw; Huang, Po-Hao; Lee, Hong-Hsi

2013-05-15

157

Shock wave excited liquid micro-jets  

Microsoft Academic Search

The meniscus of the gas-water interface in a thin hydrophilic capillary of 1mm and less has some similarities to a ``shaped charge'' used to penetrated armored vehicles. In this presentation we show high-speed recordings of the interface dynamics after the reflection from a shock wave: the interface flattens and shapes into a microscopic needle-like jet, which accelerates to velocities of

Claus-Dieter Ohl; Daan Martens; Aaldert Zijlstra; Michel Versluis; Detlef Lohse; Nico de Jong

2006-01-01

158

Shock wave excited liquid micro-jets  

NASA Astrophysics Data System (ADS)

The meniscus of the gas-water interface in a thin hydrophilic capillary of 1mm and less has some similarities to a ``shaped charge'' used to penetrated armored vehicles. In this presentation we show high-speed recordings of the interface dynamics after the reflection from a shock wave: the interface flattens and shapes into a microscopic needle-like jet, which accelerates to velocities of 100m/s and more. Further the dependencies of the pressure amplitude, capillary diameter, and interface curvature on the jet velocity are presented.

Ohl, Claus-Dieter; Martens, Daan; Zijlstra, Aaldert; Versluis, Michel; Lohse, Detlef; de Jong, Nico

2006-11-01

159

Liquid-Liquid Extraction Processes  

E-print Network

Liquid-liquid extraction is the separation of one or more components of a liquid solution by contact with a second immiscible liquid called the solvent. If the components in the original liquid solution distribute themselves differently between...

Fair, J. R.; Humphrey, J. L.

1983-01-01

160

Sidechain liquid crystal polymers  

Microsoft Academic Search

Research has continued in the field sidechain liquid crystal polymers over recent years, but it is becoming clearer that this research is being directed away from the traditional technology areas of electro-optic devices and researchers are developing new and exciting applications for this novel state of matter.

Keith M Blackwood; Ian C Sage

1998-01-01

161

An anisotropic stratified structure for surface plasmon excitation  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) is widely applied for bio/ chemical sensing. The main problem for all sensors is accuracy and sensitivity enhancement. For SPR sensors the accuracy depends on the characteristics of the plasmon resonance. In this work, we study SPR excitation assisted by liquid crystal layer. We consider Kretshmann configuration where a liquid crystal is sandwiched between a prism and glass plate, while the gold layer is evaporated over the glass plate. We show that the Bragg reflection of cholesteric liquid crystals modifies the plasmon resonance in a way increasing the accuracy of its location. Also, features of plasmon resonance excitation are studied for chiral liquid crystals.

Zhelyazkova, K.; Petrov, M.; Katranchev, B.; Dyankov, G.

2015-01-01

162

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

PubMed

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 ?(xy)?M0.51. PMID:24289698

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

2013-11-15

163

Bound excited states in 27F  

NASA Astrophysics Data System (ADS)

The 1H(27F, 25,26,27F) reactions have been studied at 40 MeV /nucleon average energy using a liquid hydrogen target. For 25F, 26F and 27F nuclei, we have observed two ?-ray peaks each originating from the decay of two bound excited states. This is the first sign of the existence of bound excited states in 26,27F. The presence of a single bound excited state in 27F is a clear indication of a substantial change in the structure of the fluorine isotopes approaching the neutron dripline. The proposed second excited states in 25,26,27F nuclei have no counterparts in either the psd or the sdpf shell model calculations suggesting the appearance of nuclear structure effects lying out of these model spaces.

Elekes, Z.; Dombrádi, Zs.; Saito, A.; Aoi, N.; Baba, H.; Demichi, K.; Fülöp, Zs.; Gibelin, J.; Gomi, T.; Hasegawa, H.; Imai, N.; Ishihara, M.; Iwasaki, H.; Kanno, S.; Kawai, S.; Kishida, T.; Kubo, T.; Kurita, K.; Matsuyama, Y.; Michimasa, S.; Minemura, T.; Motobayashi, T.; Notani, M.; Ohnishi, T.; Ong, H. J.; Ota, S.; Ozawa, A.; Sakai, H. K.; Sakurai, H.; Shimoura, S.; Takeshita, E.; Takeuchi, S.; Tamaki, M.; Togano, Y.; Yamada, K.; Yanagisawa, Y.; Yoneda, K.

2004-10-01

164

Bound excited states in 27F  

NASA Astrophysics Data System (ADS)

The 1H(27F,25,26,27F) reactions have been studied at 40 MeV/nucleon average energy using a liquid hydrogen target. For 25F, 26F and 27F nuclei, we have observed two ?-ray peaks each originating from the decay of two bound excited states. This is the first sign of the existence of bound excited states in 26,27F. The presence of a single bound excited state in 27F is a clear indication of a substantial change in the structure of the fluorine isotopes approaching the neutron dripline. The proposed second excited states in 25,26,27F nuclei have no counterparts in either the psd or the sdpf shell model calculations suggesting the appearance of nucler structure effects lying out of these model spaces.

Elekes, Z.; Dombrádi, Zs.; Saito, A.; Aoi, N.; Baba, H.; Demichi, K.; Fülöp, Zs.; Gibelin, J.; Gomi, T.; Hasegawa, H.; Imai, N.; Ishihara, M.; Iwasaki, H.; Kanno, S.; Kawai, S.; Kishida, T.; Kubo, T.; Kurita, K.; Matsuyama, Y.; Michimasa, S.; Minemura, T.; Motobayashi, T.; Notani, M.; Ohnishi, T. K.; Ong, H. J.; Ota, S.; Ozawa, A.; Sakai, H. K.; Sakurai, H.; Shimoura, S.; Takeshita, E.; Takeuchi, S.; Tamaki, M.; Togano, Y.; Yamada, K.; Yanagisawa, Y.; Yoneda, K.

2006-03-01

165

Resonating-Valence-Bond Liquid in Low Dimensions  

NASA Astrophysics Data System (ADS)

The Hubbard model in D dimensions, with the on-site repulsion U and the transfer integral between nearest neighbors - t/sqrt{D} , is studied on the basis of the Kondo-lattice theory. If U/|t| ? 1, |n ? 1| ? |t|/(DU), where n is the number of electrons per unit cell, and D is so small that |J|/D ? kBTc, where J = ?4t2/U and Tc is 0 K for D = 1 and is the highest critical temperature among possible ones for D ? 2, a low-T phase where Tc < T ? |J|/(kBD) is a frustrated electron liquid. Since the liquid is stabilized by the Kondo effect in conjunction with the resonating-valence-bond (RVB) mechanism, it is simply the RVB electron liquid; in one dimension, it is also the Tomonaga–Luttinger liquid. The Kondo energy of the RVB liquid is kBTK = O(|J|/D); its effective Fermi energy is O(kBTK). A midband appears on the chemical potential between the upper and lower Hubbard bands; the Hubbard gap is a pseudogap. As regards the density of states per unit cell of the midband, its bandwidth is O(kBTK) or O(|J|/D), its peak height is O(1/U), and its spectral weight is O[t2/(DU2)]. Since the midband almost disappears in the Heisenberg limit, the RVB electron liquid in the Heisenberg limit is simply the RVB spin liquid. The RVB electron and spin liquids adiabatically continue to each other. Since local moments form in a high-T phase where T ? TK, the high-T phase is simply the Mott insulator.

Ohkawa, Fusayoshi J.

2014-12-01

166

Liquid Nitrogen Ice Cream (1st Grade) Lesson Plan  

E-print Network

Liquid Nitrogen Ice Cream (1st Grade) Lesson Plan Science Standards Addressed (From the Colorado substance. Materials: 5 or more Liters of liquid nitrogen (gloves, goggles, and lab coat recommended. Introduce kids to liquid nitrogen. Explain that it is a liquid and is very cold (kids will be excited

167

Continuously excited laser  

Microsoft Academic Search

There is disclosed continuously-excited lasers of the COâ mixing, and supersonic CO, types. There is specifically disclosed a method, and a laser apparatus, for producing a repetitively pulsed output, in which a stream of excited gas, of the type having a relatively long excitation life, is produced, stored and subsequently transferred, in the form of pulses, to a power extraction

R. C. McLeary; P. J. Beckwith

1984-01-01

168

Excitations of superfluid 4 He in porous media: Aerogel and Vycor  

E-print Network

Excitations of superfluid 4 He in porous media: Aerogel and Vycor O. Plantevin and B. Fa structure factor S(Q, ) and the elementary excitations of liquid 4 He immersed in aerogel and Vycor. In both and superfluid density, S(T), of liquid 4 He in aerogel and Vycor have been made over the past 30 years.1

Glyde, Henry R.

169

A Novel Liquid-Liquid Transition in Undercooled Ti-Zr-Ni Liquids  

NASA Technical Reports Server (NTRS)

If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, T(sub l), finally 'freezing' into a glass below a characteristic temperature called the glass transition temperature, T(sub g). In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of H2O and Si. Such phase transitions have been predicted in some stable liquids, ie. above T(sub l) at atmospheric pressure, for SiO2 and BeF2, but these have not been verified experimentally. They have been observed in liquids of P, Si and C, but only under high pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity metallic liquid that is driven by an approach to a constant entropy configuration state and correlated with a growing icosahedral order in the liquid. A maximum in the specific heat at constant pressure, similar to what is normally observed near T(sub g), is reported for undercooled liquids of quasicrystal-forming Ti-Zr-Ni alloys. A two-state excitation model that includes cooperativity by incorporating a temperature-dependent excitation energy, fits the specific heat data well, signaling a phase transition. An inflection in the liquid density with decreasing temperature instead of a discontinuity indicates that this is not a typical first order phase transition; it could be a weakly first order or higher order transition. While showing many similarities to a glass transition, this liquid-liquid phase transition occurs in a mobile liquid, making it novel.

Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Bradshaw, R. C.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.

2004-01-01

170

Conductivity of a generic helical liquid  

NASA Astrophysics Data System (ADS)

A quantum spin Hall insulator is a two-dimensional state of matter consisting of an insulating bulk and one-dimensional helical edge states. While these edge states are topologically protected against elastic backscattering in the presence of disorder, interaction-induced inelastic terms may yield a finite conductivity. By using a kinetic equation approach, we find the backscattering rate ?-1 and the semiclassical conductivity in the regimes of high (? ??-1) and low (? ??-1) frequency. By comparing the two limits, we find that the parametric dependence of conductivity is described by the Drude formula for the case of a disordered edge. On the other hand, in the clean case where the resistance originates from umklapp interactions, the conductivity takes a non-Drude form with a parametric suppression of scattering in the dc limit as compared to the ac case. This behavior is due to the peculiarity of umklapp scattering processes involving necessarily the state at the "Dirac point." In order to take into account Luttinger liquid effects, we complement the kinetic equation analysis by treating interactions exactly in bosonization and calculating conductivity using the Kubo formula. In this way, we obtain the frequency and temperature dependence of conductivity over a wide range of parameters. We find the temperature and frequency dependence of the transport scattering time in a disordered system as ? ˜[max(?,T)]-2K-2, for K >2/3 and ? ˜[max(?,T)]-8K+2 for K <2/3.

Kainaris, Nikolaos; Gornyi, Igor V.; Carr, Sam T.; Mirlin, Alexander D.

2014-08-01

171

A one-dimensional liquid of fermions with tunable spin  

NASA Astrophysics Data System (ADS)

Correlations in systems with spin degree of freedom are at the heart of fundamental phenomena, ranging from magnetism to superconductivity. The effects of correlations depend strongly on dimensionality, a striking example being one-dimensional (1D) electronic systems, extensively studied theoretically over the past fifty years. However, the experimental investigation of the role of spin multiplicity in 1D fermions--and especially for more than two spin components--is still lacking. Here we report on the realization of 1D, strongly correlated liquids of ultracold fermions interacting repulsively within SU(N) symmetry, with a tunable number N of spin components. We observe that static and dynamic properties of the system deviate from those of ideal fermions and, for N > 2, from those of a spin-1/2 Luttinger liquid. In the large-N limit, the system exhibits properties of a bosonic spinless liquid. Our results provide a testing ground for many-body theories and may lead to the observation of fundamental 1D effects.

Pagano, Guido; Mancini, Marco; Cappellini, Giacomo; Lombardi, Pietro; Schäfer, Florian; Hu, Hui; Liu, Xia-Ji; Catani, Jacopo; Sias, Carlo; Inguscio, Massimo; Fallani, Leonardo

2014-03-01

172

Spin liquids : mean field and beyond  

E-print Network

Spin liquids are fluid-like ground states of spin systems, where spins do not order at zero temperature. These states have long-range entanglement and concomitant exotic properties, such as fractionalized excitations and ...

Serbyn, Maksym

2014-01-01

173

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

174

Roles of viscosity, polarity, and hydrogen-bonding ability of a pyrrolidinium ionic liquid and its binary mixtures in the photophysics and rotational dynamics of the potent excited-state intramolecular proton-transfer probe 2,2'-bipyridine-3,3'-diol.  

PubMed

The room-temperature ionic liquid [C3mpyr][Tf2N] and its binary mixtures with methanol and acetonitrile provide microenvironments of varying viscosity, polarity, and hydrogen-bonding ability. The present work highlights their effects on the photophysics and rotational dynamics of a potent excited-state intramolecular double-proton-transfer (ESIDPT) probe, 2,2'-bipyridine-3,3'-diol [BP(OH)2]. The rotational diffusion of the proton-transferred diketo (DK) tautomer in [C3mpyr][Tf2N] ionic liquid was analyzed for the first time from the experimentally obtained temperature-dependent fluorescence anisotropy data using Stokes-Einstein-Debye (SED) hydrodynamic theory and Gierer-Wirtz quasihydrodynamic theory (GW-QHT). It was found that the rotation of the DK tautomer in neat ionic liquid is governed solely by the viscosity of the medium, as the experimentally observed boundary-condition parameter, Cobs, was very close to the GW boundary-condition parameter (CGW). On the basis of photophysical studies of BP(OH)2 in IL-cosolvent binary mixtures, we suggest that methanol molecules form hydrogen bonds with the cationic counterpart of the DK tautomers, as evidenced by the greater extent of the decrease in the fluorescence lifetime of BP(OH)2 upon addition of methanol compared to acetonitrile. It is also possible for the methanol molecules to form hydrogen bonds with the constituents of the RTIL, which is supported by the lesser extent of the decrease in the viscosity of the medium upon addition of methanol, leading to a less effective decrease in the rotational relaxation time compared to that observed upon acetonitrile addition. PMID:23668553

Mandal, Sarthak; Ghosh, Surajit; Banerjee, Chiranjib; Kuchlyan, Jagannath; Sarkar, Nilmoni

2013-06-01

175

Librational echo: Subpicosecond intermolecular interactions in liquid  

SciTech Connect

The ultrafast optical Kerr effect observed in liquids upon two-pulse laser excitation is studied theoretically. It is shown that a Raman echo on librational frequencies (librational echo) can be excited in liquid. The librational echo has the following features: its shape and amplitude strongly depend on the local inhomogeneity of a medium and the form of local potentials; and the echo signal can be separated into the contributions of the phase and irreversible relaxation of coherent molecular librations. These properties of the librational echo can be used for studying the specific features of the local structure of liquids by the method of selective subpicosecond spectroscopy of molecular librations. (nonlinear optical phenomena)

Nikiforov, V G [E.K.Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences, Kazan (Russian Federation)

2008-02-28

176

Raman Spectra of Compounds in the Gaseous and Liquid States  

Microsoft Academic Search

An apparatus for exciting the Raman spectra of gases and liquids at temperatures up to 300°C is described. For phosphorus trichloride, methyl chloride, methyl bromide, methyl alcohol, methylene chloride, methylene bromide, chloroform, and carbon tetrachloride, the Raman spectra of the gas and the liquid at the same temperature have been photographed in juxtaposition with a liquid-prism spectrograph of speed f:

J. Rud Nielsen; Newton E. Ward

1942-01-01

177

Medium-frequency impulsive-thrust-excited slosh waves during propellant reorientation with a geyser  

NASA Technical Reports Server (NTRS)

Slosh wave excitation induced by a resettling flowfield activated by 1.0-Hz impulsive thrust during the course of liquid reorientation with the initiation of geyser for liquid-fill levels of 30, 50, 65, 70, and 80 percent has been studied. Characteristics of slosh waves of various frequencies excited by the resettling flowfield are discussed. Slosh wave excitations shift the fluid mass distribution in the container which imposes time-dependent variations in spacecraft moment of inertia. This information is important for spacecraft control during the course of liquid reorientation.

Hung, R. J.; Shyu, K. L.; Lee, C. C.

1992-01-01

178

A Liquid-Liquid Transition in an Undercooled Ti-Zr-Ni Liquid  

NASA Technical Reports Server (NTRS)

If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, TI, finally freezing into a glass below a characteristic temperature called the glass transition temperature, T,. In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of HzO and Si4. Such phase transitions have been predicted in some stable liquids, i.e. above TI at atmospheric pressure, for Si02 and BeF;, but these have not been verified experimentally. They have been observed in liquids of P7, Sis and C9, but only under high pressure. All of these transitions are driven by an anomalous density change, i.e. change in local structure, with temperature or pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity liquid that is not driven by an anomalous density change, but by an approach to a constant configuration state. A maximum in the specific heat at constant pressure, similar to what is normally observed near T,, is reported here for undercooled low viscosity liquids of quasicrystal- forming Ti-Zr-Ni alloys. that includes cooperativity, by incorporating a temperature dependent excitation energy fits the data well, signaling a phase transition.

Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.

2003-01-01

179

Excitation Methods for Bridge Structures  

SciTech Connect

This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

1999-02-08

180

Exciting flavored bound states  

NASA Astrophysics Data System (ADS)

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

2014-10-01

181

Exciting flavored bound states  

E-print Network

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited $D_{(s)}$ mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

E. Rojas; B. El-Bennich; J. P. B. C. de Melo

2014-10-23

182

Local structural excitations in model glasses  

NASA Astrophysics Data System (ADS)

Structural excitations of model Lennard-Jones glass systems are investigated using the activation-relaxation technique (ARTn), which explores the potential energy landscape around a local minimum energy configuration by converging to a nearby saddle-point configuration. Performing ARTn results in a distribution of barrier energies that is single-peaked for well-relaxed samples. The present work characterizes such atomic-scale excitations in terms of their local structure and environment. It is found that, at zero applied stress, many of the identified events consist of chainlike excitations that can either be extended or ringlike in their geometry. The location and barrier energy of these saddle-point structures are found to correlate with the type of atom involved, and with spatial regions that have low Kelvin eigenshear moduli and are close to the excess free volume within the configuration. Such correlations are, however, weak and more generally the identified local structural excitations are seen to exist throughout the model glass sample. The work concludes with a discussion within the framework of ? and ? relaxation processes that are known to occur in the undercooled liquid regime.

Swayamjyoti, S.; Löffler, J. F.; Derlet, P. M.

2014-06-01

183

Physics of liquid jets  

NASA Astrophysics Data System (ADS)

Jets, i.e. collimated streams of matter, occur from the microscale up to the large-scale structure of the universe. Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids. Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology. Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup. In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology. They also arise from the last but one topology change of liquid masses bursting into sprays. Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium. The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects.

Eggers, Jens; Villermaux, Emmanuel

2008-03-01

184

Coalescence of Liquid Drops  

NASA Technical Reports Server (NTRS)

When two liquid drops come into contact, a neck forms between them and grows rapidly. We are interested in the very early stage of the coalescence process, which can be characterized by the time dependence of the radius of the neck. The functional dependence of the size of the neck on time depends on the properties of the liquid. Experimentally, we are investigating a liquid in Stokes flow regime where the viscosity provides the principal retarding force to the surface tension. Recently, it has been predicted that the neck radius should change as t ln|t| in this regime. Theoretically, we have studied the situation when the velocity at each point on the surface is proportional to the local curvature and directed normal to the surface. This is the case that should be applicable to superfluid helium at low temperature when the mean free path of the thermal excitations are comparable to the size of liquid drops. For this system, the radius of the neck is found to be proportional to t(sup 1/3). We are able to find a simple expression for the shape of the interface in the vicinity of the neck.

Yao, Wei-Jun

2003-01-01

185

Positron excitation of neon  

NASA Technical Reports Server (NTRS)

The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

1990-01-01

186

Excitations of Superfluid He4 in aerogel and Vycor  

NASA Astrophysics Data System (ADS)

We report precision neutron scattering measurements of the dynamic structure factor, S(Q,?), and the elementary excitations of liquid ^4He immersed in Vycor(H.R. Glyde, O. Plantevin, B. Fåk , G. Coddens, P.S. Danielson and H. Schober, Phys. Rev. Lett.), 84, 2646 (2000). and aerogel(B. Fåk, O. Plantevin, H. R. Glyde and N. Mulders, Phys. Rev. Lett.), 85, 388 (2000).. Liquid ^4He in both porous media supports two-dimensional (2D) layermodes at wavevectors in the roton region. Measurements as a function of filling of aerogel show that the 2D modes propagate in the liquid layers adjacent to the media walls. The layer modes have a roton-like energy dispersion relation with energies that are consistent with specific heat and superfluid density measurements at low temperature in Vycor. The liquid ^4He also supports 3D phonon-roton (p-r) excitations in both media that have energies and lifetimes at temperatures 0.5 <= T <= 2.3K which are the same as in bulk liquid ^4He within current precision (5 ? eV). In Vycor, we observe a well defined p-r excitation at low temperatures above Tc in the normal phase which suggests that there is a localized condensate (phase coherence on short length scales) above Tc in Vycor.

Plantevin, Olivier; Fak, Bjorn; Glyde, Henry; Mulders, Norbert

2001-03-01

187

Excitation of atmospheric pressure uniform dielectric barrier discharge using repetitive unipolar nanosecond-pulse generator  

Microsoft Academic Search

Dielectric barrier discharge (DBD) excitation by unipolar high voltage pulses is a promising approach for producing non-thermal plasma at atmospheric pressure. In this study, a magnetic compression solid-state pulsed power generator was used to produce repetitive nanosecond pulses for the excitation. The DBD is created using two liquid electrodes. The electrical characteristics of the discharge voltage and current are illustrated

Tao Shao; Yang Yu; Cheng Zhang; Dongdong Zhang; Zheng Niu; Jue Wang; Ping Yan; Yuanxiang Zhou

2010-01-01

188

High resolution resonant photoluminescence excitation of CdSe/ZnS nanocrystals at low temperatures  

E-print Network

1 High resolution resonant photoluminescence excitation of CdSe/ZnS nanocrystals at low resolution resonant photoluminescence excitation of CdSe/ZnS nanocrystals. The method takes advantage of the long photoluminescence decay times (~ 1 µs) observed in this system at liquid helium temperatures

Paris-Sud XI, Université de

189

Charge separation in liquids  

NASA Astrophysics Data System (ADS)

The common theory of reversible charge transfer (RCT) at low donor system excitation power in liquids is examined. The space averaging procedures describing the kinetics of RCT in the liquid space are discussed. The reaction space is presented as a totality of independent subgroups with one excited donor and some group of acceptors effectively interacting only with the donor in the given “subgroup”. We have shown that the theory [3-5] gives questionable results for cation state probability for the usual parameters of this problem. If the acceptor concentration or the charge transfer rate constants are low, then the cation state probability behaves the same in the two theories [3-5] and [7, 8]. The correct account of the donor’s ground state change and charge back transfer in the RCT theory gives the new, not contradictory results, different from the behavior of the results in references [3-5], but near to results of [7, 8]. The molecules motion accelerates the ionization of donors and neutralization of ions. The influence of the motion of neutral and ionized molecules on charge transfer kinetics is different. The Coulomb interaction of ions is taken into account; the effect depends on the space averaging method used. The new approximation in this article in comparison with references [3-6,9] consists in the space averaging procedure of the donor cation state probability, which takes into account the donor’s ground state.

Mikhelashvili, M. S.; Agam, O.

2004-10-01

190

Market Liquidity and Funding Liquidity  

Microsoft Academic Search

We provide a model that links an asset's market liquidity (i.e., the ease with which it is traded) and traders' funding liquidity (i.e., the ease with which they can obtain funding). Traders provide market liquidity, and their ability to do so depends on their availability of funding. Conversely, traders' funding, i.e., their capital and margin requirements, depends on the assets'

Markus K. Brunnermeier; Lasse Heje Pedersen

2009-01-01

191

Mystery Liquids  

NSDL National Science Digital Library

In this math lesson, learners analyze the density of liquids in order to explore linear functions. Learners gather mass and volume data for two mystery liquids, oil and water, and then use the data to explore linear functions. Learners discuss the physical meaning of the slopes and y-intercepts of the various lines they create from scatterplots.

PBS

2012-01-01

192

Liquid pearls  

E-print Network

This fluid dynamics video reports how to form liquid core capsules having a thin hydrogel elastic membrane named liquid pearls. These fish-egg like structures are initially made of a millimetric liquid drop, aqueous or not, coated with an aqueous liquid film containing sodium alginate that gels once the double drop enters a calcium chloride bath. The creation of such pearls with micrometer thick membrane requires to suppress mixing until gelling takes place. Here, we show that superimposing a two dimensional surfactant precipitation at the interface confers a transient rigidity that can damp the shear induced instability at impact. Based on this, pearls containing almost any type of liquids can be created. The video focuses on the dynamics of the entry of the compound drop into the gelling bath.

Bremond, Nicolas; Bibette, Jérôme

2010-01-01

193

Liquid metal thermoacoustic engine  

SciTech Connect

We are studying a liquid metal thermoacoustic engine both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts. A sound wave is usually thought of as consisting of pressure oscillations, but always attendant to the pressure oscillation are temperature oscillations. The combination produces a rich variety of ''thermoacoustic'' effects. These effects are usually so small that they are never noticed in everyday life; nevertheless under the right circumstances they can be harnessed to produce powerful heat engines, heat pumps, and refrigerators. In our liquid metal thermoacoustic engine, heat flow from a high temperature source to a low temperature sink generates a high-amplitude standing acoustic wave in liquid sodium. This acoustic power is converted to electric power by a simple magnetohydrodynamic effect at the acoustic oscillation frequency. We have developed a detailed thermoacoustic theory applicable to this engine, and find that a reasonably designed liquid sodium engine operating between 700/sup 0/C and 100/sup 0/C should generate about 60 W/cm/sup 2/ of acoustic power at about 1/3 of Carnot's efficiency. Construction of a 3000 W-thermal laboratory model engine has just been completed, and we have exciting preliminary experimental results as of the time of preparation of this manuscript showing, basically, that the engine works. We have also designed and built a 1 kHz liquid sodium magnetohydrodynamic generator and have extensive measurements on it. It is now very well characterized both experimentally and theoretically. The first generator of its kind, it already converts acoustic power to electric power with 40% efficiency. 16 refs., 5 figs.

Swift, G.W.; Migliori, A.; Wheatley, J.C.

1986-01-01

194

Algebraic spin liquid in an exactly solvable spin model  

SciTech Connect

We have proposed an exactly solvable quantum spin-3/2 model on a square lattice. Its ground state is a quantum spin liquid with a half integer spin per unit cell. The fermionic excitations are gapless with a linear dispersion, while the topological 'vison' excitations are gapped. Moreover, the massless Dirac fermions are stable. Thus, this model is, to the best of our knowledge, the first exactly solvable model of half-integer spins whose ground state is an 'algebraic spin liquid.'

Yao, Hong; Zhang, Shou-Cheng; Kivelson, Steven A.; /Stanford U., Phys. Dept.

2010-03-25

195

Caged spin-orbit excited I*,,2 P1/2... I*,,2  

E-print Network

1997 Two-photon excitation of I2 in room temperature liquid solutions and in cryogenic rare gas.8 s, in Ar, Kr, and Xe. In room temperature liquids, emission from both geminate and nongeminate pairs a rather useful tool for time resolved studies of molecular iodine. The approach was first implemented

Apkarian, V. Ara

196

Apparatus for photon excited catalysis  

NASA Technical Reports Server (NTRS)

An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

Saffren, M. M. (inventor)

1977-01-01

197

Harmonically excited orbital variations  

SciTech Connect

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

Morgan, T.

1985-08-06

198

Aperture excited dielectric antennas  

NASA Technical Reports Server (NTRS)

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

1974-01-01

199

Double Excitations of Helium  

NASA Astrophysics Data System (ADS)

The double excitations of helium offer an ideal case for investigating electron dynamics in a three-body system. Our study of the He ^1P^o double excitations comprises measurements of the partial photoionization cross sections ?n (He^+) and the partial photoelectron angular distribution parameters ?n for the series N(K,T)^Ai up to the N=5 threshold. The experiment was performed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 × 10^12 photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K=N-2 are clearly delineated in both ?n and ?_n. The ?n show all minor series with N=K-4 very clearly, in contrast to measurements of the total absorption cross section, as well as very weak members with A=-1. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N=5 and N=6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He^+(n), whereas the peak-to-valley variation in the ?n within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the ?n and ?n of the photoelectron satellites are virtually identical provided the final ionic state He^+(n), n >= 2, is reached via an excited series N with ?=1, or ?=2, where ?=N-n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (N-K), A, and T. We tentatively propose an extension of these systematics for higher series N >= 5, although further theoretical work toward understanding these features of the doubly excited states will be needed. The experiment was performed in close collaboration with C.D. Caldwell, M.O. Krause, S.P. Frigo, and S.B. Whitfield. Valuable theoretical contributions were made by J.-Z. Tang and I. Shimamura. Part of the work appeared in Phys. Rev. Lett. 75, 1479 (1995). This work is supported by the National Science Foundation under grants PHY-9207634 and PHY-9507573.

Menzel, Alexander

1996-05-01

200

Composite fermion excitations in fractional quantum Hall systems  

SciTech Connect

In two dimensional systems in a strong magnetic field, electrons can be transformed into composite Fermions (CF) by attaching to each a fictitious flux tube (carrying flux {Phi}) and fictitious charge q, where the product q{sup {Phi}} is a multiple of 2 {Pi}. In the mean field approximation, this transformation converts a fractionally filled electron Landau level into an integrally filled CF Landau level. This integrally filled CF Landau level corresponds to the ground state of a Laughlin incompressible fluid. Excited states are described by the n{sub QE} and n{sub QH}, the numbers of quasielectron and quasihole CF excitations. For N electrons on the surface of a sphere the energy and angular momentum of a quasihole (or quasielectron) are {var_epsilon}{sub QH} and l{sub QH}=1/2(N+n{sub QH}-n{sub QE}-1) (or {var_epsilon}{sub QE} and l{sub QE}=l{sub QH}+1). The lowest energy sector of the energy spectrum contains the minimum number of CF excitations consistent with the value of N and the degeneracy of the lowest Landau level, 2S+1. The first excited sector contains one additional QE-QH pair. The total angular momentum L is obtained by adding the angular momenta of QE excitations and QH excitations treated as distinguished sets of Fermions. In the absence of CF interactions, all states containing n{sub QE} quasielectrons and n{sub QH} quasiholes are degenerate. The interaction between CF excitations partially removes this degeneracy. The interactions between CF excitations can be determined by comparing exact numerical results for N electrons with the CF picture. This amounts to constructing a Fermi liquid theory of CF excitations, and should allow the study of low lying excitations of systems with much larger values of N than can be treated numerically.

Quinn, J.J. [Univ. of Tennessee, Knoxville, TN (United States)

1995-04-01

201

Seasonal excitation of polar motion  

NASA Astrophysics Data System (ADS)

We estimate geophysical excitations (?1 and ?2) of polar motion using multiple sources of data, including recent atmospheric, oceanic, and hydrological models, satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE), and compare geophysical excitations with observed polar motion excitations from space geodetic techniques. At seasonal time scales, both model-estimated excitations from the geophysical fluids envelope (i.e., atmosphere, ocean, and hydrosphere) and GRACE-observed excitations agree remarkably well with polar motion observations in the ?2 component, and in the ?1 component, model estimates and observed geodetic excitations show significant discrepancies. However, mass excitations estimated from GRACE show significantly better agreement with observed excitations than those from models, especially in ?1, due to better quantification of terrestrial water storage and oceanic mass changes using GRACE data. Furthermore, GRACE satellite gravity measurements offer a unique means for quantifying contributions from cryospheric angular momentum (CAM) change, a component mostly neglected in previous studies due to the lack of adequate observations or reliable ice sheets models. Based on GRACE estimates, CAM excitations appear a minor, but not negligible contributor to seasonal excitations of polar motion. The significantly better agreement in ?2 (than that in ?1) between observations and model excitations is related to the higher sensitivity of ?2 excitations to atmospheric pressure and terrestrial water changes over the Eurasia and North American continents, because of the special relationship between the ?S21 spherical harmonic coefficient (proportional to ?2) mass model and the locations of the two continents.

Chen, J. L.; Wilson, C. R.; Zhou, Y. H.

2012-12-01

202

Get excited: reappraising pre-performance anxiety as excitement.  

PubMed

Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. PMID:24364682

Brooks, Alison Wood

2014-06-01

203

Dynamic behavior of liquid free surface in a cylindrical container subject to vertical vibration  

NASA Astrophysics Data System (ADS)

This paper reports a series of experimental studies on the dynamic behavior of the gas-liquid interface. These studies are concerned with the liquid sloshing phenomena induced by vertical vibration of a cylindrical container containing a liquid. The disappearance of the harmonic surface wave motion, the formation of 1/2-subharmonic motion, the mechanism of the surface disintegration and the behavior of spray-excited low frequency waves are investigated. The effect of the liquid height in the container on the surface disintegration was a decrease in the threshold excitation amplitude for the disintegration with an increase in liquid height. Spray-excited low frequency waves were observed over a wide range of excitation frequencies. It was also found that a violet surface agitation might occur due to a bubble cluster formed by the air injection, although the excitation acceleration was relatively low.

Hashimoto, H.; Sudo, S.

1984-05-01

204

Exploring Liquids  

NSDL National Science Digital Library

Young learners investigate and observe the properties of three liquids -- water, vegetable oil, and corn syrup. They use their senses to collect data and ask and answer questions. This lesson for young learners introduces the scientific process.

Sharon Janulaw

2010-01-01

205

Line liquids  

Microsoft Academic Search

We review the long wavelength description of three-dimensional liquids of entangled lines with an average orientation along the z-axis. Originally developed for polymer nematics, a closely related approach is applicable to the vortex liquid state of high temperature superconductors, and to ferro- and electrorheological fluids. The theory predicts unusual behavior of the three-dimensional structure function near the origin of reciprocal

David R. Nelson

1991-01-01

206

Ionic Liquids  

Microsoft Academic Search

Ionic liquids are receiving an upsurge of interest as green solvents; primarily as replacements for conventional media in\\u000a chemical processes. This review presents an overview of the chemistry that has been developed utilising ionic liquids as either\\u000a catalyst and\\/or solvent, with particular emphasis on processes that have been taken beyond the pre-competetive laboratory\\u000a stage and represent clean industrial technology with

J. D. Holbrey; K. R. Seddon

1999-01-01

207

Excited States and Photons  

NSDL National Science Digital Library

Investigate how atoms can be excited to give off radiation (photons) with models of electron energy diagrams. Explore the effects of energy levels in atoms through interactive computer models. Learn about the different electron orbitals of an atom, and explore three-dimensional models of the atoms. Learn about photons and why they are emitted, and gain an understanding of the link between energy levels and photons as you discover how an atom?s electron configuration affects which wavelengths of light it will admit or absorb.

The Concord Consortium

2011-12-13

208

Dipole Excitation of Dipositronium  

E-print Network

The energy interval between the ground and the P-wave excited states of the recently discovered positronium molecule Ps_2 is evaluated, including the relativistic and the leading logarithmic radiative corrections, E_P-E_S = 0.181 586 7(8) a.u. The P-state, decaying usually via annihilation, is found to decay into the ground state by an electric dipole transition 19 percent of the time. Anticipated observation of this transition will provide insight into this exotic system.

Mariusz Puchalski; Andrzej Czarnecki

2008-09-30

209

Collective excitations in soft-sphere fluids.  

PubMed

Despite that the thermodynamic distinction between a liquid and the corresponding gas ceases to exist at the critical point, it has been recently shown that reminiscence of gaslike and liquidlike behavior can be identified in the supercritical fluid region, encoded in the behavior of hypersonic waves dispersion. By using a combination of molecular dynamics simulations and calculations within the approach of generalized collective modes, we provide an accurate determination of the dispersion of longitudinal and transverse collective excitations in soft-sphere fluids. Specifically, we address the decreasing rigidity upon density reduction along an isothermal line, showing that the positive sound dispersion, an excess of sound velocity over the hydrodynamic limit typical for dense liquids, displays a nonmonotonic density dependence strictly correlated to that of thermal diffusivity and kinematic viscosity. This allows rationalizing recent observation parting the supercritical state based on the Widom line, i.e., the extension of the coexistence line. Remarkably, we show here that the extremals of transport properties such as thermal diffusivity and kinematic viscosity provide a robust definition for the boundary between liquidlike and gaslike regions, even in those systems without a liquid-gas binodal line. Finally, we discuss these findings in comparison with recent results for Lennard-Jones model fluid and with the notion of the "rigid-nonrigid" fluid separation lines. PMID:25375488

Bryk, Taras; Gorelli, Federico; Ruocco, Giancarlo; Santoro, Mario; Scopigno, Tullio

2014-10-01

210

Multiphonon excitations in boson quantum films  

SciTech Connect

Dynamical excitations in thin liquid films of {sup 4}He adsorbed to a substrate are investigated by using a microscopic theory of excitations that includes multiple-phonon scattering. We study the dispersion relation, excitation mechanisms, transition densities, and particle currents as a function of surface coverage. A primary new result is that we have included three-phonon scattering processes in the calculation of the dynamic structure function and the one-body current densities. With the exception that our ground state is determined by our variational theory, rather than taken from experiment, our work on the dynamic structure function is the generalization of that of Jackson [Phys. Rev. A {bold 4}, 2386 (1971)] to inhomogeneous systems (films). Using sum rules for the dynamic structure function as a guide, we suggest a simple scaling argument for improving the agreement between our dynamic structure function and the experimental one. The addition of three-phonon contributions bring about the following changes. First, the energy of most modes is lowered by a non-negligible amount for finite momentum excitations. Second, the film{close_quote}s surface mode is the exception; it is only slightly affected. Third, for monolayer films there is large scattering at high energies at intermediate values of momenta. This scattering can be traced back to an anomalously large contribution to the two-particle density of states. Fourth, all modes with energy above a critical energy decay, and the associated peaks of the dynamic structure function are broadened. Fifth, the maxonlike character is enhanced in the bulklike modes. {copyright} {ital 1996 The American Physical Society.}

Clements, B.E. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Krotscheck, E. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria)] [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

211

New developments in catalysis using ionic liquids  

Microsoft Academic Search

Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents for catalysis. Being composed entirely of ions, they possess negligible vapour pressures, and the wide range of possible cations and anions means that other solvent properties may be easily controlled. There is currently great interest in the use of these materials as solvents for

Charles M. Gordon

2001-01-01

212

Liquid Crystals  

NASA Technical Reports Server (NTRS)

Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

1990-01-01

213

Liquid marbles.  

PubMed

The transport of a small amount of liquid on a solid is not a simple process, owing to the nature of the contact between the two phases. Setting a liquid droplet in motion requires non-negligible forces (because the contact-angle hysteresis generates a force opposing the motion), and often results in the deposition of liquid behind the drop. Different methods of levitation-electrostatic, electromagnetic, acoustic, or even simpler aerodynamic techniques-have been proposed to avoid this wetting problem, but all have proved to be rather cumbersome. Here we propose a simple alternative, which consists of encapsulating an aqueous liquid droplet with a hydrophobic powder. The resulting 'liquid marbles' are found to behave like a soft solid, and show dramatically reduced adhesion to a solid surface. As a result, motion can be generated using gravitational, electrical and magnetic fields. Moreover, because the viscous friction associated with motion is very small, we can achieve quick displacements of the droplets without any leaks. All of these features are of potential benefit in microfluidic applications, and also permit the study of a drop in a non-wetting situation-an issue of renewed interest following the recent achievement of super-hydrophobic substrates. PMID:11418851

Aussillous, P; Quéré, D

2001-06-21

214

Fission and Nuclear Liquid-Gas Phase Transition  

E-print Network

The temperature dependence of the liquid-drop fission barrier is considered, the critical temperature for the liquid-gas phase transition in nuclear matter being a parameter. Experimental and calculated data on the fission probability are compared for highly excited $^{188}$Os. The calculations have been made in the framework of the statistical model. It is concluded that the critical temperature for the nuclear liquid--gas phase transition is higher than 16 MeV.

E. A. Cherepanov; V. A. Karnaukhov

2007-03-30

215

Axonal excitability revisited.  

PubMed

The original papers of Hodgkin and Huxley (J. Physiol. 116 (1952a) 449, J. Physiol. 116 (1952b) 473, J. Physiol. 116 (1952c) 497, J. Physiol. 117 (1952d) 500) have provided a benchmark in our understanding of cellular excitability. Not surprisingly, their model of the membrane action potential (AP) requires revisions even for the squid giant axon, the preparation for which it was originally formulated. The mechanisms they proposed for the voltage-gated potassium and sodium ion currents, IK, and INa, respectively, have been superceded by more recent formulations that more accurately describe voltage-clamp measurements of these components. Moreover, the current-voltage relation for IK has a non-linear dependence upon driving force that is well described by the Goldman-Hodgkin-Katz (GHK) relation, rather than the linear dependence on driving force found by Hodgkin and Huxley. Furthermore, accumulation of potassium ions in the extracellular space adjacent to the axolemma appears to be significant even during a single AP. This paper describes the influence of these various modifications in their model on the mathematically reconstructed AP. The GHK and K+ accumulation results alter the shape of the AP, whereas the modifications in IK and INa gating have surprisingly little effect. Perhaps the most significant change in their model concerns the amplitude of INa, which they appear to have overestimated by a factor of two. This modification together with the GHK and the K+ accumulation results largely remove the discrepancies between membrane excitability of the squid giant axon and the Hodgkin and Huxley (J. Physiol. 117 (1952d) 500) model previously described (Clay, J. Neurophysiol. 80 (1998) 903). PMID:15561301

Clay, John R

2005-05-01

216

Multiphoton excitation of fluorescent probes.  

PubMed

This introduction reviews the multiphoton excitation cross sections of extrinsic and intrinsic fluorophores, genetically engineered probes, and nanoparticles. We will review the known two-photon excitation cross sections of biological indicators and will discuss several related issues such as how to theoretically estimate and experimentally gauge the two-photon cross section of an indicator. We provide practical guides for experimentally estimating the excitation cross section. PMID:25734074

Xu, Chris; Zipfel, Warren R

2015-01-01

217

Dipolar Solvation Dynamics in Room Temperature Ionic Liquids: An Effective Medium Calculation Using Dielectric Relaxation Data  

E-print Network

Dipolar Solvation Dynamics in Room Temperature Ionic Liquids: An Effective Medium Calculation Using to a laser-excited probe molecule in an ionic liquid is approximated by that in an effective dipolar medium, no probe dependence has been found for the average solvation times in these ionic liquids. In addition

Biswas, Ranjit

218

Optically excited states in positronium  

NASA Technical Reports Server (NTRS)

Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

1990-01-01

219

Plasmon excitation by slow ions  

NASA Astrophysics Data System (ADS)

We present a theoretical approach to the problem of subthreshold plasmon excitation in proton-aluminum collisions. Based both on recent experimental results by Ritzau [Phys. Rev. B 59, 15506 (1999)] and on previous calculations by two of the authors, we solve the master equations and obtain the probability of both plasmon excitation and nearly free electron excitation due to plasmon decay as functions of the projectile initial velocity. The mechanism considered for subthreshold plasmon excitation involves an intermediary fast electron as suggested by Ritzau

Bocan, G. A.; Arista, N. R.; Miraglia, J. E.

2007-01-01

220

The excited state model and an elementary act of softening of glassy solids  

SciTech Connect

A new elementary act of the glass-liquid transition is proposed, and the softening criterion is calculated for different classes of glassy systems. The transition of an amorphous substance from a glassy solid state to a liquid state is explained by defreezing of the process of excitation of the kinetic unit responsible for viscous flow when the average energy of thermal lattice vibrations becomes equal to or higher than the work of the ultimate elastic deformation of the interatomic bond, which corresponds to the maximum of the quasi-elastic force. The excitation of the kinetic unit is considered to mean its critical displacement from the equilibrium position, which corresponds to the maximum of the attractive force between particles. The kinetic unit (an atom or a group of atoms) capable of being displaced over a critical distance is referred to as an excited atom, and the approach under consideration is termed the excited state model. The nature of excited atoms in silicate glasses and amorphous polymers is discussed. The nature of fluctuation holes in liquids and glasses is considered in the excited state model. The known Frenkel exponential formula for the hole concentration acquires the meaning of the probability of excitation of the kinetic unit responsible for viscous flow. The elementary act of softening of glasses can serve as a molecular mechanism of their plastic deformation.

Sanditov, D. S. [Buryat State University, Siberian Branch, Russian Academy of Sciences (Russian Federation)], E-mail: sanditov@bsu.ru

2009-01-15

221

Liquid Ammonia  

Microsoft Academic Search

This is a review of the use of liquid ammonia as a solvent for chemical processes. Among the subjects covered are the physical properties of the solvent that defines it as “water like.” The physical and chemical processes associated with the formation of solutions and the properties of those solutions are also convered. Included is a discussion of metal?ammonia solutions,

J. J. Lagowski

2007-01-01

222

Layered Liquids  

NSDL National Science Digital Library

This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba

John Eichinger

2009-05-30

223

Liquid ventilation  

PubMed Central

Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

Sarkar, Suman; Paswan, Anil; Prakas, S.

2014-01-01

224

Helium at elevated pressures: Quantum liquid with non-static shear rigidity  

NASA Astrophysics Data System (ADS)

The properties of liquid helium have always been a fascinating subject to scientists. The phonon theory of liquids, taking into account liquid non-static shear rigidity, is employed here for studying internal energy and heat capacity of compressed liquid 4He. We demonstrate the good agreement of calculated and experimental heat capacity of liquid helium at elevated pressures and supercritical temperatures. Unexpectedly, helium remains a quantum liquid at elevated pressures for a wide range of temperature supporting both longitudinal and transverse-like phonon excitations. We have found that in the very wide pressure range of 5 MPa-500 MPa, liquid helium near melting temperature is both solid-like and quantum.

Bolmatov, D.; Brazhkin, V. V.; Trachenko, K.

2013-03-01

225

The Excitable Membrane  

PubMed Central

The model of the excitable membrane assumes common channels for Na+ and K+; the two ion species interact within the pores through their electrostatic forces. The electric field varies across the membrane and with time, as a result of ionic redistribution. Ionic flow is primarily controlled by energy barriers at the two interfaces and by Ca++ adsorption at the external interface. When the membrane is polarized, the high electric field at the external interface acting on the membrane fixed charge keeps the effective channel diameter small, so that only dihydrated ions can cross the interface. The higher energy required to partially dehydrate Na+ accounts for its lower permeability when polarized. Depolarized, the channel entrance can expand, permitting quadrihydrated ions to pass; the large initial Na+ flow is the result of the large concentration ratio across the interface. The effect at the internal interface is symmetric; Na+ crosses with greater difficulty when the membrane is depolarized. Na+ inactivation occurs when the ion distribution within the membrane has assumed its new steady-state value. Calculations based on parameters consistent with physicochemical data agree generally with a wide range of experiments. The model does not obey the two fundamental Hodgkin-Huxley (HH) postulates (independence principle, ion flow proportional to thermodynamic potential). In several instances the model predicts experimental results which are not predicted by the HH equations. ImagesFIGURE 12 PMID:4655662

Offner, Franklin F.

1972-01-01

226

Excited waves in shear layers  

NASA Technical Reports Server (NTRS)

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

Bechert, D. W.

1982-01-01

227

On the thermalization of a Luttinger liquid after a sequence of sudden interaction quenches This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

field of optimal control theory [18­20]: what is the steady-state dependence on the initial state quenches. The critical exponent governing the decay of the steady-state propagator is expressed a steady state or, if it does, the steady state is not the ground state of the quenched Hamiltonian

Stefanucci, Gianluca

228

Vibrational excitation induces double reaction.  

PubMed

Electron-induced reaction at metal surfaces is currently the subject of extensive study. Here, we broaden the range of experimentation to a comparison of vibrational excitation with electronic excitation, for reaction of the same molecule at the same clean metal surface. In a previous study of electron-induced reaction by scanning tunneling microscopy (STM), we examined the dynamics of the concurrent breaking of the two C-I bonds of ortho-diiodobenzene physisorbed on Cu(110). The energy of the incident electron was near the electronic excitation threshold of E0=1.0 eV required to induce this single-electron process. STM has been employed in the present work to study the reaction dynamics at the substantially lower incident electron energies of 0.3 eV, well below the electronic excitation threshold. The observed increase in reaction rate with current was found to be fourth-order, indicative of multistep reagent vibrational excitation, in contrast to the first-order rate dependence found earlier for electronic excitation. The change in mode of excitation was accompanied by altered reaction dynamics, evidenced by a different pattern of binding of the chemisorbed products to the copper surface. We have modeled these altered reaction dynamics by exciting normal modes of vibration that distort the C-I bonds of the physisorbed reagent. Using the same ab initio ground potential-energy surface as in the prior work on electronic excitation, but with only vibrational excitation of the physisorbed reagent in the asymmetric stretch mode of C-I bonds, we obtained the observed alteration in reaction dynamics. PMID:25489788

Huang, Kai; Leung, Lydie; Lim, Tingbin; Ning, Zhanyu; Polanyi, John C

2014-12-23

229

Kinetics of fast reactions of excited species. Final report  

SciTech Connect

This report contains brief summaries of findings in the following areas: gamma radiation induced decomposition of chloroform; proton transfer and ion neutralization reactions in gaseous hydrocarbons; kinetics of thremal D-atom reactions with CH/sub 4/ C/sub 2/H/sub 6/; the gamma radiation induced decomposition of liquid n-pentane; pulse radiolysis of rare gases and liquid n-pentane and n-pentane-O/sub 2/ solutions; rate constants and activation energies for second order decay of pentyl and peroxypentyl radicals; pulse radiolysis fo aromatic solutes in halogenated solvents; the gamma radiation induced decomposition of nitromethane; the radiolysis of heavy water vapor; pulse radiolysis of solvated electrons in binary liquid solutions; collisional quenching of rare gas excimers by small foreign molecules; kinetics and mechanism for decay of Paschen-1s argon atoms; detection and monitoring of excited atoms in pulse irradiated rare gases.

Firestone, R.F.

1986-09-01

230

Liquid electrode  

DOEpatents

A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

Ekechukwu, Amy A. (Augusta, GA)

1994-01-01

231

Wire deconstructionism of two-dimensional topological phases  

NASA Astrophysics Data System (ADS)

A scheme is proposed to construct integer and fractional topological quantum states of fermions in two spatial dimensions. We devise models for such states by coupling wires of nonchiral Luttinger liquids of electrons that are arranged in a periodic array. Which interwire couplings are allowed is dictated by symmetry and the compatibility criterion that they can simultaneously acquire a finite expectation value, opening a spectral gap between the ground state(s) and all excited states in the bulk. First, with these criteria at hand, we reproduce the tenfold classification table of integer topological insulators, where their stability against interactions becomes immediately transparent in the Luttinger liquid description. Second, we construct an example of a strongly interacting fermionic topological phase of matter with short-range entanglement that lies outside of the tenfold classification. Third, we expand the table to long-range entangled topological phases with intrinsic topological order and fractional excitations.

Neupert, Titus; Chamon, Claudio; Mudry, Christopher; Thomale, Ronny

2014-11-01

232

Radioactivity Induced by Nuclear Excitation I. Excitation by Neutrons  

Microsoft Academic Search

It is shown that the 4.1-hr. period of indium can be produced by nuclear excitation of indium and is to be attributed to an excited metastable state, In115,* of the stable In115. This result is obtained by studying the radioactivity produced in indium by neutrons of different energy distributions and by studying the chain reactions produced in cadmium by fast

M. Goldhaber; R. D. Hill; Leo Szilard

1939-01-01

233

Uniform excitations in magnetic nanoparticles.  

PubMed

We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T(3/2) law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

234

Uniform excitations in magnetic nanoparticles  

PubMed Central

Summary We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T 3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

235

Coulomb excitation of 107In  

NASA Astrophysics Data System (ADS)

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two ? rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2- states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code gosia2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Heyde, K.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2013-01-01

236

Effects of dark atom excitations  

E-print Network

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Jean-René Cudell; Maxim Yu. Khlopov; Quentin Wallemacq

2014-11-06

237

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering  

SciTech Connect

The spectra of collective excitations of liquid and glassy tellurium have been studied by means of inelastic neutron scattering. Here we report on the dynamics of liquid Te as measured at two different temperatures, just above melting (T{sub m}=723 K) and at {approx}1000 K as well as the glass that is studied at room temperature. Estimates for the velocity of propagating excitations for both temperatures have been obtained from the experimental data, and a contrasting behavior is found with respect to anomalies shown by the adiabatic sound velocity measured by ultrasound methods. The origin of such differences is finally discussed.

Ruiz-Martin, M. D.; Jimenez-Ruiz, M. [Institut Laue Langevin, 6 Rue Jules Horowitz, BP. 156, F-38042 Grenoble Cedex 9 (France); Bermejo, F. J. [C.S.I.C., Department of Electricity and Electronics, UPV/EHU, Box 644, 4880 Bilbao (Spain); Fernandez-Perea, R. [Instituto de Estructura de la Materia, Consejo Superior de Investigacioens Cientifcas, Serrano 123, E-28006 Madrid (Spain)

2006-03-01

238

News CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events  

NASA Astrophysics Data System (ADS)

CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events

2010-09-01

239

Liquid jet waveguide for Raman spectroscopy  

NASA Astrophysics Data System (ADS)

An optofluidic jet waveguide for Raman spectroscopy is reported. In this device a micro-channel is used to produce a high speed liquid stream acting at the same time, as the solution to analyse and as an optical waveguide. The liquid waveguide, exploiting total internal reflection, is able to effectively collect the Raman signal produced by the chemical compound under analysis opportunely excited by means of a laser source. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the Raman signal towards the detection system. The waveguiding nature of a liquid jet enables high Raman signal collection and the device configuration allows strong reduction of the background as no confining walls are used to contain the solution to analyse. The performances of the system have been successfully tested on isopropyl alcohol in water solutions showing a detection limit for this chemical compound of 0.8+/-0.1%.

Persichetti, Gianluca; Testa, Genni; Bernini, Romeo

2014-03-01

240

Industrial applications of photonuclear resonance excitation  

E-print Network

Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

Chichester, David Lee, 1971-

2000-01-01

241

Exciting Students About Science & Engineering ...  

E-print Network

applications include nanomachines, bioimplants, smart materials, fuel cells, genetic engineering and spaceExciting Students About Science & Engineering ... ASM MATERIALS CAMP® 2013 MATERIALS IN TODAY'S WORLD Materials science and engineering is a study of the relationship between the structure

Evans, Paul G.

242

Liquid electrode  

DOEpatents

A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

Ekechukwu, A.A.

1994-07-05

243

Liquid Rainbow  

NSDL National Science Digital Library

In this density activity, students determine the relative densities of five liquids and layer them atop one another in a straw. Directions for conducting the activity are included in addition to lists of the science process skills, complex reasoning strategies, and National Science Education Standards that relate to it. A brief explanation of the activity's science content and an assessment idea are also provided. This activity is part of a set called Whelmers that were designed to inspire students to think about science concepts.

Mid-continent Research for Education and Learning (McREL)

2004-01-01

244

Laser-induced nuclear excitation  

SciTech Connect

An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 10{sup 3} Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

Zon, B. A., E-mail: zon@niif.vsu.ru; Kornev, A. S., E-mail: a-kornev@yandex.r [Voronezh State University (Russian Federation)

2010-05-15

245

Ultralow detection limits for an organic dye determined by fluorescence spectroscopy with laser diode excitation  

SciTech Connect

Fluorescence of IR-140, a laser dye in methanol solution, is excited by a semiconductor laser diode. Analytical figures of merit are compared for three different instrumental configurations, with the dye measured in a cuvette, a liquid jet, and a compact instrument. The best limit of detection, 46,000 molecules, was achieved with a liquid jet. Linear dynamic range was 6 orders of magnitude. The laser diode operates in the near-infrared region, resulting in low background fluorescence.

Johnson, P.A.; Barber, T.E.; Smith, B.W.; Winefordner, J.D. (Univ. of Florida, Gainesville (USA))

1989-04-15

246

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

247

Electron-excited molecule interactions  

SciTech Connect

In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

248

Laser-induced separation of hydrogen isotopes in the liquid phase  

DOEpatents

Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

Freund, Samuel M. (Los Alamos, NM); Maier, II, William B. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM)

1980-01-01

249

Renormalization group analysis of thermal transport in the disordered Fermi liquid  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

250

High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host  

DOEpatents

A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

Comaskey, Brian J. (Walnut Creek, CA); Ault, Earl R. (Livermore, CA); Kuklo, Thomas C. (Oakdale, CA)

2005-07-05

251

Ionic liquids as electrolytes  

Microsoft Academic Search

Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their

Maciej Gali?ski; Andrzej Lewandowski; Izabela St?pniak

2006-01-01

252

Rocking response of tanks containing two liquids  

SciTech Connect

A study on the dynamic response of upright circular cylindrical liquid-storage tanks containing two different liquids under a rocking base motion with an arbitrary temporal variation is presented. Only rigid tanks were studied. The response quantities examined include the hydrodynamic pressure, sloshing wave height and the associated frequencies, base shear and moments. Each of these response quantities is expressed as the sum of the so-called impulsive component and convective component. Unlike the case of tanks containing one liquid, in which the response is controlled by one parameter, height-to-radius ratio, the response of tanks containing two different liquids are controlled by three parameters: height-to-radius ratio, and mass density ratio and height ratio of the two liquids. The interrelationship of the responses of the tank-liquid system to rocking and lateral base excitations is established by examining numerical results extensively. The study shows that some of the response quantities for tank-liquid system under a rocking base motion can be determined from the available data for the response of an identical tank under a horizontal base motion. Base rocking motion can occur in a ground-supported tank or in an elevated tank under earthquake motions.

Tang, Y. [Argonne National Lab., IL (United States). Reactor Engineering Div.

1995-01-01

253

Liquid sloshing in a tilted cylindrical tank.  

NASA Technical Reports Server (NTRS)

Two distinct fundamental modes are shown to exist for liquid sloshing in a tilted cylindrical tank. The 'long' mode is excited by tank motions parallel to the long axis of the elliptical free surface, the 'short' mode by tank motions perpendicular to it. Experiments show that the natural frequencies of both modes decrease as the tilt increases, and the slosh damping decreases markedly with increased tilt for the long mode.

Dodge, F. T.; Garza, L. R.

1972-01-01

254

The syndrome of excited delirium.  

PubMed

The excited delirium syndrome (EDS) is a life-threatening condition caused by a variety of factors including drug intoxication and psychiatric illness. Fatal instances of excited delirium frequently come to the attention of the medical examiner/coroner due to the circumstances and potential causes. Excited delirium may include paranoid, aggressive, and incoherent behavior which may lead to an encounter with law enforcement. In some instances, the person may die while in the presence of law enforcement. This circumstance further broadens the potential causes of death particularly as EDS has no pathognomonic autopsy finding. Although the syndrome of excited delirium is sufficient to explain death, other intervening causes need to be considered. These include chest or neck compression during restraint, blunt trauma, and underlying natural disease. Since chest/neck compression, natural disease (e.g., atherosclerosis), blunt trauma, and excited delirium are not mutually exclusive, all may be present in one death. The forensic pathologist's role is to determine what caused and/or contributed to the death. When attempting to determine the proximate cause of death in instances with multiple potential causes, determining the mechanism of death often is useful. As not all causes of death have pathologically-demonstrable mechanisms of death, examination of the circumstances of the death often are diagnostically important. The main goal of the autopsy of deaths suspected to be due to EDS is to identify (or exclude) intervening diseases or injuries sufficient to explain the death in the context of the investigated circumstances. PMID:24526411

Gill, James R

2014-06-01

255

Liquid-liquid-solid transition in viscoelastic liquids  

PubMed Central

Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528

Zubelewicz, Aleksander

2013-01-01

256

Liquid-liquid-solid transition in viscoelastic liquids.  

PubMed

Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528

Zubelewicz, Aleksander

2013-01-01

257

Liquid foams of graphene  

E-print Network

Liquid foams are dispersions of bubbles in a liquid. Bubbles are stabilized by foaming agents that position at the interface between the gas and the liquid. Most foaming agents, such as the commonly used sodium dodecylsulfate, ...

Alcazar Jorba, Daniel

2012-01-01

258

Lacerations - liquid bandage  

MedlinePLUS

Skin adhesives; Tissue adhesive ... the cut is minor, a liquid bandage (liquid adhesive) can be used on the cut to close ... bandage is quick and painless to apply. Skin adhesives, or liquid bandages, seal the cut closed after ...

259

What Is A Liquid?  

NSDL National Science Digital Library

The representation is an animation of the molecular motion of liquid and gaseous bromine. The motion of the atoms of liquid argon and the molecular motion of liquid water are shown as well. Descriptive information accompanies the animation.

260

Radiation from Excited Vortex in the Abelian  

Microsoft Academic Search

Excitation of a vortex in the Abelian Higgs model is investigated with the help of a polynomial approximation. The excitation can be regarded as a longitudinal component of the vector field trapped by the vortex. The energy and profile of the excitation are found. Back-reaction of the excitation on the vortex is calculated in the smalllimit. It turns out that

Higgs Model; H. Arodz; L. Hadas

261

Solids Liquids and Gases  

NSDL National Science Digital Library

Compare and contrast the three states of matter: solids, liquids and gases. First you will begin by looking at characteristics of each solids, liquids and gasesGases, Liquids and Solids Facts. Then you will look at examples of each stateSolids, Liquids and Gases Video. Demonstrate an understanding of solids, liquids and gases by playing interactive gameSolids, Liquids and Gases Game. Graphic Organizer is here to be filled out as you learn during this lesson. Use the red ...

Ms. Salter

2009-10-22

262

Transport currents in Bose quantum liquids  

SciTech Connect

Until now, most of what has been said about excitations in quantum liquids has concerned the dynamic structure function, which is observable by means of neutron scattering. The dynamic structure function can be calculated using standard linear response theory. However, at this level one needs only transition densities <0{rho}n> or transition currents <0jn>, which are oscillatory in time and hence do not describe mass transport. In this work we go a step further and study transport currents in excited states, , which requires the calculation of to second order. For that purpose, we take a well-tested microscopic theory of inhomogeneous quantum liquids and extend it to find the currents formed when helium atoms scatter off a helium slab or when excitations evaporate atoms (a setup experimented by A. F. G. Wyatt's group in Exeter). Current conservation was already a major theoretical problem encountered by R. Feynman and led him to introduce backflow corrections. We show that perfect current conservation is expected only for exact solutions of the time-dependent many-body Schroedinger equation. This is the first extensive theoretical study of transport phenomena in a quantum liquid based on an accurate microscopic theory.

Apaja, V.; Krotscheck, E.; Rimnac, A. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A 4040 Linz (Austria); Zillich, R. E. [Fraunhofer ITWM, D-67663 Kaiserslautern (Germany)

2006-09-07

263

Excitation optimization for damage detection  

SciTech Connect

A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD

2009-01-01

264

Effects of dark atom excitations  

NASA Astrophysics Data System (ADS)

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles O--, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Cudell, Jean-Rene; Khlopov, Maxim Yu.; Wallemacq, Quentin

2014-11-01

265

Band Excitation in Scanning Probe Microscopy: Sines of Change  

SciTech Connect

In three decades since Scanning Probe Microscopy (SPM) methods have entered scientific arena, they have become one of the main tool of nanoscale science and technology by offering the capability for imaging topography, magnetic, electrical, and mechanical properties on the nanometer scale. The vast majority of force-based SPM techniques to date are based on single-frequency sinusoidal excitation and detection. Here, we illustrate the intrinsic limitations of single-frequency detection that stem from the fundamental physics of dynamic systems. Consequently, many aspects of nanoscale materials functionality including quantitative mechanical, magnetic, and electrical measurements, probing dissipative interactions, to name a few remain unexplored. Band excitation is illustrated as a universal alternative to traditional single-frequency techniques that allows quantitative and reliable studies of dissipative and conservative phenomena, and can be universally applied to all ambient and liquid SPM methods.

Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

2011-01-01

266

Production of O2,,1 ... in flowing plasmas using spiker-sustainer excitation  

E-print Network

to I2 and I. Plasma production of O2 1 in electrical COILs eCOILs eliminates liquid phase generatorsCOIL has focused on ef- ficiently generating O2 1 by engineering the operating E/N electric fieldProduction of O2,,1 ... in flowing plasmas using spiker-sustainer excitation Natalia Y. Babaevaa

Kushner, Mark

267

Faraday Discuss., 1997, 108, 115130 Excited state dynamics in clusters of oxygen  

E-print Network

Faraday Discuss., 1997, 108, 115�130 Excited state dynamics in clusters of oxygen Runjun Li, Karl A clusters of oxygen. Oxygen clusters and liquid oxygen have a com- plicated chemistry due to numerous low) dynamics of small anionic clusters of oxygen. We Ðnd that the dynamics of the neutral DPD pathway

Continetti, Robert E.

268

LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM  

E-print Network

LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM AND AT LIQUID NITROGEN decay of chloro- phyll (Chl) a in the green alga Chlorella pyrenoidosa, the red alga Porphyridium cruentum, and the blue-green alga Anacystis nidulans was measured by the phase- shift method under

Govindjee

269

Ferroelectric liquid crystal waveguide modulators  

NASA Astrophysics Data System (ADS)

Liquid crystals (LCs) possess effective electro-optic coefficients orders of magnitude larger than other materials used in integrated optics such as lithium niobate or poled polymers. In addition, the relatively simple fabrication of huge arrays of LC-based devices has made them the technology of choice in the flat panel display market. When nematic LC displays were introduced in the 1970's, researchers investigated waveguiding in these material, but found they scattered light too strongly to be of practical use. In 1980, the surface stabilized ferroelectric liquid crystal (FLC) display element was introduced, which used the smectic C liquid crystalline state. The smectic state has a higher degree of ordering than the nematic state, and therefore exhibits far less scattering loss. However, in stark contrast to the large volume of nematic waveguiding research performed following the introduction of the nematic based displays, there have been relatively few studies of FLC waveguides. This research described an FLC cladded waveguide as well as an FLC film waveguide. The performance of these two structures was calculated, and it was shown that the switching effect of the FLC film waveguide is greater but more sensitive to FLC defects. Several different modulator configurations are described and their performance is modeled theoretically. These configurations include Mach-Zehnder and directional couplers, a cut-off modulator, a deflection modulator, and a prism/total internal reflection modulator. Coupling light into a liquid crystal waveguide is complicated by the thick substrates and covers required to mechanically support the liquid film. Techniques for coupling light into the waveguide are described including techniques that directly excite the mode in the waveguide, and indirect techniques that first excite a mode in an intermediary waveguide (such as a polymer waveguide or an optical fiber), then transfer power to the FLC film. An experimental FLC waveguide modulator was designed and built. It was found that these devices require virtually defect-free uniform alignments because defects in the FLC cause significant scattering. Finally, the surface mode which propagates at the interface including an anisotropic material (like FLCs) was investigated and possible implications to FLC waveguides was discussed.

Walker, David Brian

270

Method for separating isotopes in the liquid phase at cryogenic temperature  

Microsoft Academic Search

Isotopes are separated from an isotopically mixed molecular dopant dissolved in a cryogenic liquid. The solution is exposed to infrared laser light in order to selectively vibrationally excite a particular molecular species which contains the isotope or isotopes that are to be separated. The excited species then is reacted or dissociated to form recoverable reaction products rich in the isotope

S. R. Brueck; R. M. Osgood

1980-01-01

271

Superheating water by CW excitation of gold nanodots.  

PubMed

A temperature-dependent photoluminescent thin film of Al(0.94)Ga(0.06)N doped with Er(3+) is used to measure the temperature of lithographically prepared gold nanodots. The gold nanodots and thin film are excited simultaneously with a continuous wave (CW) Nd:YAG 532 nm laser. The gold nanodot is submersed under water, and the dot is subsequently heated. The water immediately surrounding the nanodot is superheated beyond the boiling point up to the spinodal decomposition temperature at 594 ± 17 K. The spinodal decomposition has been confirmed with the observation of critical opalescence. We characterize the laser scattering that occurs in unison with spinodal decomposition due to an increased coherence length associated with the liquid-liquid transition. PMID:22313363

Carlson, Michael T; Green, Andrew J; Richardson, Hugh H

2012-03-14

272

The suppression of exciting thoughts  

Microsoft Academic Search

We examined how the suppression of an exciting thought influences sympathetic arousal as indexed by skin conductance level (SCL). Subjects were asked to think aloud as they followed instructions to think about or not to think about various topics. Experiment l showed that trying not to think about sex, like thinking about sex, elevates SCL in comparison to thinking about

Daniel M. Wegner; Joann W. Shortt; Anne W. Blake; Michelle S. Page

1990-01-01

273

Perceptual Load Alters Visual Excitability  

ERIC Educational Resources Information Center

Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load…

Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

2011-01-01

274

Communicating the Excitement of Science  

ScienceCinema

In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

Michael Turner

2010-01-08

275

Multi-photon excitation microscopy  

Microsoft Academic Search

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase

Alberto Diaspro; Paolo Bianchini; Giuseppe Vicidomini; Mario Faretta; Paola Ramoino; Cesare Usai

2006-01-01

276

Excitation of slosh waves associated with low frequency impulsive reverse gravity acceleration of geyser initiation  

NASA Technical Reports Server (NTRS)

The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank prior to main engine restart poses a microgravity fluid behavior problem. The purpose of the present study is to investigate the stability of the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. In this study slosh wave excitation induced by the resettling flow field activated by 0.1 Hz low frequency, impulsive reverse gravity acceleration, during reorientation with the initiation of geyser for liquid fill levels of 30, 50, 65, 70 and 80 percent, have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitation shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for the spacecraft control during the course of liquid reorientation.

Hung, R. J.; Shyu, K. L.

1992-01-01

277

Minimizing liquid contaminants in natural gas liquids  

SciTech Connect

In processing natural gas liquids, significant contamination occurs with liquid dispersions and emulsions. Natural gas liquids (NGL) and liquid petroleum gas (LPG) streams are treated with caustic to remove residual organic sulfur compounds such as mercaptans and with amines to remove hydrogen sulfide. In both cases a liquid/liquid contactor is used. Significant amounts of the caustic or amine can be carried over into the product stream in process units that are running at rates above design capacity, are treating high sulfur feed stocks, or have other operational problems. The carried over liquid results in off-spec products, excessive loses of caustic or amine, and can cause operating problems in downstream processes. In addition, water is a significant contaminant which can cause LPG and natural gasoline to be off-specification. This paper discusses a new technique for separating very stable liquid dispersions of caustic, amine, or water from natural gas liquids using liquid/liquid cartridge coalescers constructed with specially formulated polymer and fluoropolymer medium with enhanced surface properties. In addition, factors influencing the coalescer mechanism will be discussed including interfacial tension, concentration of surface active compounds, steric repulsion, and electrostatic charge affects. Results from field tests, operating data from commercial installations, and economic benefits will also be presented.

Brown, R.L. [Pall Industrial Process Filtration, East Hills, NY (United States); Wines, T.H. [Pall Scientific and Laboratory Services, Port Washington, NY (United States); Williamson, K.M. [Pall Process Equipment Development, Cortland, NY (United States)

1996-12-31

278

Spin-exchange dynamical structure factor of the S=1/2 Heisenberg chain.  

PubMed

We determine the spin-exchange dynamical structure factor of the Heisenberg spin chain, as is measured by indirect resonant inelastic x-ray scattering (RIXS). We find that two-spin RIXS excitations nearly entirely fractionalize into two-spinon states. These share the same continuum lower bound as single-spin neutron scattering excitations, even if the relevant final states belong to orthogonal symmetry sectors. The RIXS spectral weight is mainly carried by higher-energy excitations, and is beyond the reach of the low-energy effective theories of Luttinger liquid type. PMID:21568610

Klauser, Antoine; Mossel, Jorn; Caux, Jean-Sébastien; van den Brink, Jeroen

2011-04-15

279

Look-alike Liquids  

NSDL National Science Digital Library

Learners add drops of four liquids (water, alcohol, salt water, and detergent solution) to different surfaces and observe the liquids' behavior. Learners will see that liquids have characteristic properties which can be used for identification. In the related activity, " Developing Tests to Distinguish Between Similar-Looking Liquids" (see related resources), learners identify an unknown based on these properties.

James H. Kessler

2007-01-01

280

Liquid/liquid Extraction 62 LIQUID/LIQUID SEPARATION: EXTRACTION OF ACIDS OR BASES FROM NEUTRAL  

E-print Network

Liquid/liquid Extraction 62 LIQUID/LIQUID SEPARATION: EXTRACTION OF ACIDS OR BASES FROM NEUTRAL layer. 2. A neutral/carboxylic acid mixture is shaken with ether and NaOH/water. (Part 1) · The neutral. Isolating a neutral carboxylic acid from the NaOH/water layer: · Acidify/Neutralize HCl is added to acidify

Jasperse, Craig P.

281

Traveling Through Different Liquids  

NSDL National Science Digital Library

Learners observe and record what happens when they manipulate bottles containing a liquid (water or corn syrup) and one or more objects (screw, nail, paper clip). They should observe differences in how quickly the objects fall in the different liquids. This lesson builds on what learners have studied in previous lessons, Exploring Liquids and Exploring How Liquids Behave.

Sharon Janulaw

2010-01-01

282

Ionic Liquids Database- (ILThermo)  

National Institute of Standards and Technology Data Gateway

SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

283

Dye-Induced Enhancement of Optical Nonlinearity in Liquids and Liquid Crystals  

SciTech Connect

Optical nonlinearity of liquid crystals (LC) in the isotropic phase can be enhanced by 1 order of magnitude by dissolving 0.1{percent} of anthraquinone dye in the LC. The enhancement decreases by {approximately}30{percent} when the LC transforms into the nematic phase. The same guest-host effect also exists in non-LC liquids. It can be explained by a model based on the change of guest-host interaction induced by optical excitations of the dye. {copyright} {ital 1996} {ital The American Physical Society}

Muenster, R.; Jarasch, M.; Zhuang, X.; Shen, Y. [Department of Physics, University of California, Berkeley, California 94720-7300 (United States)] [Department of Physics, University of California, Berkeley, California 94720-7300 (United States)

1997-01-01

284

Liquid crystal polyester thermosets  

SciTech Connect

The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

Benicewicz, B.C.; Hoyt, A.E.

1990-12-31

285

Liquid crystal polyester thermosets  

SciTech Connect

The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

Benicewicz, B.C.; Hoyt, A.E.

1990-01-01

286

Proceedings of the 200,l Particle AcceleratorConference,Chicago THERMOELASTIC RESPONSE OF SUDDENLY HEATED LIQUID  

E-print Network

Source, muon collider targets, etc. Sudden energy deposition causes shock and rarefaction waves HEATED LIQUID TARGETS IN HIGH-POWER COLLIDERS A. Hassanein, I. Konkashbaev,and J. Norem Argonne National this paper. 1 INTRODUCTION Sudden deposition of beam energy in a liquid metal target causes excitation

Harilal, S. S.

287

THERMOELASTIC RESPONSE OF SUDDENLY HEATED LIQUID TARGETS IN HIGH-POWER COLLIDERS  

E-print Network

. Sudden energy deposition causes shock and rarefaction waves of magnitude ± P that corresponds deposition of beam energy in a liquid metal target causes excitation of cylindrical sound waves with pressureTHERMOELASTIC RESPONSE OF SUDDENLY HEATED LIQUID TARGETS IN HIGH-POWER COLLIDERS A. Hassanein, I

Harilal, S. S.

288

Backreaction of excitations on a vortex  

E-print Network

Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found in the cases of plane wave and wave packet type excitations. We find that the excited vortex radiates vector field and that the Higgs field has a very broad oscillating component.

Henryk Arodz; Leszek Hadasz

1996-07-15

289

Backreaction of excitations on a vortex  

E-print Network

Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found in the cases of plane wave and wave packet type excitations. We find that the excited vortex radiates vector field and that the Higgs field has a very broad oscillating component.

Arodz, H; Arodz, Henryk; Hadasz, Leszek

1997-01-01

290

Atom-Molecule Coherence in a One-Dimensional System  

NASA Astrophysics Data System (ADS)

We study a model of one-dimensional fermionic atoms with a narrow Feshbach resonance that allows them to bind in pairs to form bosonic molecules. We show that at low energy, a coherence develops between the molecule and fermion Luttinger liquids. At the same time, a gap opens in the spin excitation spectrum. The coherence implies that the order parameters for the molecular Bose-Einstein condensation and the atomic BCS pairing become identical. Moreover, both bosonic and fermionic charge density wave correlations decay exponentially, in contrast with a usual Luttinger liquid. We exhibit a Luther-Emery point where the systems can be described in terms of noninteracting pseudofermions. At this point we discuss the threshold behavior of density-density response functions.

Citro, R.; Orignac, E.

2005-09-01

291

Exploring How Liquids Behave  

NSDL National Science Digital Library

Learners apply their knowledge from a previous study to identify different liquids--water, corn syrup, and vegetable oil. They also investigate combinations of liquids, two at a time, to see how they interact. This is meant as a follow-up lesson to the related activity, Exploring Liquids. As an extension, learners can continue their study of these liquids in the lesson, Traveling Through Different Liquids.

2012-06-26

292

Two regimes of the parametrically self-exciting ultrasonic standing waves.  

PubMed

This paper discusses a nonlinear multi-wave mechanism for the parametrically self-exciting standing waves in a plane-parallel liquid layer driven at one end of the layer. The dependence of this process on the number of parametrically self-exciting waves and the frequency detuning between the frequency "f" of the pump wave and the nearest natural frequency are analyzed. It is found that two regimes with different thresholds are possible. One of them is characterized by self-exciting subharmonic frequencies close to f/2 and the second has a much lower threshold and the presence of a self-exciting subharmonic at a frequency near to the smallest natural frequency. Three dimensionless parameters determining each regime are introduced. PMID:21682375

Goldberg, Zinoviy; Goldberg, Iliya; Goldberg, Alexander

2011-06-01

293

Self assembled liquid crystal polymers on photo-irradiated alignment surfaces for tailoring response properties of liquid crystal molecules.  

PubMed

A liquid crystal polymer (LCP) self-assembled on a photoirradiated substrate can modify the viscoelastic response of liquid crystal medium on the substrate. Sum-frequency vibrational spectroscopy shows that the phenyl groups of LCP are oriented epitaxially with layer thickness and an in-plane alignment order much higher than that at the photoirradiated surface can be yielded. The liquid crystal molecules confined between the LCP-coated substrates reveals a stronger correlation among the thermally excited fluctuation modes. Our finding can be used to tailor the boundary forces on alignment substrates and to optimize the device performance. PMID:21902209

Huang, Jung Y; Li, Liu S

2011-10-20

294

Liquid-liquid phase transition in water  

NASA Astrophysics Data System (ADS)

Water shows anomalies different from most of other materials. Different sceniaros have been proposed to explain water anomalies, among which the liquid-liquid phase transition (LLPT) is the most discussed one. It attributes water anomalies to the existence of a hypothesized liquid-liquid critical point (LLCP) buried deep in the supercooled region. We briefly review the recent experimental and theoretical progresses on the study of the LLPT in water. These studies include the discussion on the existence of the first order LLPT in supercooled water and the detection of liquid-liquid critical point. Simulational results of different water models for LLPT and the experimental evidence in confined water are also discussed.

Sun, ZhaoRu; Sun, Gang; Chen, YiXuan; Xu, LiMei

2014-05-01

295

Autoresonant excitation of dark solitons  

NASA Astrophysics Data System (ADS)

Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested.

Borich, M. A.; Shagalov, A. G.; Friedland, L.

2015-01-01

296

Autoresonant excitation of dark solitons.  

PubMed

Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

Borich, M A; Shagalov, A G; Friedland, L

2015-01-01

297

Tachyonic thermal excitations and causality  

E-print Network

We consider an ideal Fermi gas of tachyonic thermal excitations as a continuous medium and establish when it satisfies the causality condition. At high temperature the sound speed is always subluminal $c_stachyon matter below the critical temperature $T_ctachyon mass $m$. The pressure $P$ and energy density $E$ cannot be arbitrary small, but $P$ can exceed $E$, and $P=2.36E$ when $T\\rightarrow T_c$.

Ernst Trojan; George V. Vlasov

2011-10-08

298

Launch Excitement with Water Rockets  

NSDL National Science Digital Library

Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable launchers and rockets for experiments while learning fundamental principles of physics.

John Penick

2007-10-01

299

Multiparticle excitations in 194Pb  

Microsoft Academic Search

High-spin states of 194Pb have been populated by the reaction 184W(16O,6n) at 113 MeV beam energy and studied using the EUROGAM-1 array. The level scheme has been extended up to spin of 33? and excitation energy of 11.1 MeV. The high-spin part of the level scheme is dominated by bands of dipole transitions. New dipole bands have been observed and the configurations

M. Kaci; M.-G. Porquet; I. Deloncle; M. Aiche; F. Azaiez; G. Bastin; C. W. Beausang; C. Bourgeois; R. M. Clark; R. Duffait; J. Duprat; B. J. P. Gall; F. Hannachi; K. Hauschild; M. J. Joyce; A. Korichi; Y. Le Coz; M. Meyer; E. S. Paul; N. Perrin; N. Poffé; N. Redon; C. Schück; H. Sergolle; J. F. Sharpey-Schafer; J. Simpson; A. G. Smith; R. Wadsworth

2002-01-01

300

Polarization Raman Spectral Microscopy of Polymer Fibers Formed in Ferroelectric Liquid Crystal  

Microsoft Academic Search

This letter focuses on Raman spectral microscopy of polymer fiber networks, which are formed by the photopolymerization of liquid crystalline acrylate monomers in low-molecular-weight ferroelectric liquid crystal, using polarized infrared light to excite the polymer molecules. It was found that the tolane side-chain molecules of the polymer are significantly orientated with the liquid crystal alignment along the rubbing direction of

Hideo Fujikake; Takeshi Murashige; Hiroto Sato; Masahiro Kawakita; Hiroshi Kikuchi

2003-01-01

301

Electronic excitations in Guanine quadruplexes.  

PubMed

Guanine rich DNA strands, such as those encountered at the extremities of human chromosomes, have the ability to form four-stranded structures (G-quadruplexes) whose building blocks are guanine tetrads. G-quadruplex structures are intensively studied in respect of their biological role, as targets for anticancer therapy and, more recently, of their potential applications in the field of molecular electronics. Here we focus on their electronic excited states which are compared to those of non-interacting mono-nucleotides and those of single and double stranded structures. Particular emphasis is given to excited state relaxation processes studied by time-resolved fluorescence spectroscopy from femtosecond to nanosecond time scales. They include ultrafast energy transfer and trapping of ??* excitations by charge transfer states. The effect of various structural parameters, such as the nature of the metal cations located in the central cavity of G-quadruplexes, the number of tetrads or the conformation of the constitutive single strands, are examined. PMID:24563011

Changenet-Barret, Pascale; Hua, Ying; Markovitsi, Dimitra

2015-01-01

302

Measurement of excited states in 40Si and evidence for weakening of the N=28 shell gap  

E-print Network

Excited states in 40Si have been established by detecting gamma-rays coincident with inelastic scattering and nucleon removal reactions on a liquid hydrogen target. The low excitation energy, 986(5) keV, of the 2+[1] state provides evidence of a weakening in the N=28 shell closure in a neutron-rich nucleus devoid of deformation-driving proton collectivity.

C. M. Campbell; N. Aoi; D. Bazin; M. D. Bowen; B. A. Brown; J. M. Cook; D. -C. Dinca; A. Gade; T. Glasmacher; M. Horoi; S. Kanno; T. Motobayashi; W. F. Mueller; H. Sakurai; K. Starosta; H. Suzuki; S. Takeuchi; J. R. Terry; K. Yoneda; H. Zwahlen

2006-08-15

303

On Diversity of Configurations Generated by Excitable Cellular Automata with Dynamical Excitation Intervals  

NASA Astrophysics Data System (ADS)

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Adamatzky, Andrew

2012-11-01

304

Stable Manifolds as Thresholds for Multipulse Excitability  

E-print Network

(p) · · saddle case t· PA/BK/HO - Stable manifolds and excitability ­ p. #12;Excitable Systems and Homoclinic Bifurcations ·p Ws loc(p) Wu(p) · · saddle-focus (Shilnikov) case t· PA/BK/HO - Stable manifolds Communications 215 (2003) 367-379.] PA/BK/HO - Stable manifolds and excitability ­ p. #12;Excitable Systems

Doedel, Eusebius

305

Backreaction of excitations on a vortex  

Microsoft Academic Search

Excitations of a vortex are usually considered in a linear approximation neglect- ing their backreaction on the vortex. In the present paper we investigate backre- action of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in

Henryk Arodz; Leszek Hadas

306

Back reaction of excitations on a vortex  

Microsoft Academic Search

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we

Henryk Arodz; Leszek Hadasz

1997-01-01

307

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2014 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2014-10-01

308

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2013 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2013-10-01

309

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2012 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2012-10-01

310

Semiconductor nanorod liquid crystals  

SciTech Connect

Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

2002-01-28

311

Gravity jitter induced slosh waves in liquid propellant and disturbances of fluid stresses on spacecraft  

NASA Technical Reports Server (NTRS)

The paper investigates the dynamical behavior of fluids, in particular the effect of surface tension on partially filled rotating fluids (cryogenic liquid helium and helium vapor) in a full-scale Gravity Probe-B spacecraft propellant dewar tank imposed by various frequencies of gravity jitters. Fluid stress distribution caused by the excitation of slosh waves and their associated large amplitude disturbances on the liquid-vapor interface and exerted on the outer and inner walls of a rotating dewar container are also examined. It is shown that fluid stress distributions near the outer and inner walls of the rotating dewar are closely related to the characteristics of slosh waves excited in the liquid-vapor interface in the rotating dewar tank. This can be of utility in managing spacecraft dynamic control leading to control of spacecraft imbalance caused by the uneven fluid stress distribution due to slosh wave excitations at the interface between liquid and vapor propellants.

Hung, R. J.; Lee, C. C.; Leslie, F. W.

1992-01-01

312

Charge transfer reactions in nematic liquid crystals  

SciTech Connect

Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.

Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.; [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry

1998-07-01

313

Peculiarities of collisional excitation transfer with excited screened energy levels of atoms  

SciTech Connect

We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

Gerasimov, V. A. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Gerasimov, V. V. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Department of Physics, Tomsk State University, Tomsk, 634050 (Russian Federation); Pavlinskiy, A. V. [Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation)

2007-09-15

314

Theoretical studies of electronically excited states  

SciTech Connect

Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

Besley, Nicholas A. [School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

2014-10-06

315

Benzotriazol Type Liquid Crystals  

Microsoft Academic Search

A new series of liquid crystals (LCs), benzotriazol ype which have high absorptivities to ultraviolet (UV) light within the wavelength range from 290 to 350 nm were synthesized. Their syntheses and liquid crystalline properties are reported in this paper.

Yinfa Yan; Lijuan Hu

1995-01-01

316

Turbulent swirling jets with excitation  

NASA Technical Reports Server (NTRS)

An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.

Taghavi, Rahmat; Farokhi, Saeed

1988-01-01

317

Multipulse excitability in injected lasers  

NASA Astrophysics Data System (ADS)

We show that a single-mode semiconductor laser subject to optical injection, and described by rate equations, can produce excitable multipulses, where the laser emits a certain number of pulses after being triggered from its steady state by a single perturbation. This phenomenon occurs in experimentally accessible regions in parameter space that are bounded by curves of n-homoclinic bifurcations, connecting a saddle to itself only at the n-th return to a neighborhood of the saddle. These regions are organised in what we call 'homoclinic teeth' that grow in size and shape with the linewidth enhancement factor.

Krauskopf, Bernd; Wieczorek, Sebastian; Lenstra, Daan

2003-07-01

318

Electron impact excitation of methane  

NASA Technical Reports Server (NTRS)

A crossed molecular beam-electron beam apparatus was employed to examine the excitation cross-sections of CH4. Attention was given to 20, 30, and 200 eV impact energies at angles from 8-130 deg. Spectra were obtained in the elastic and inelastic realms as well as in the ionization continuum in the 12.99-15.0 eV energy-loss range. Differential cross-sections were also determined. The results are useful for modeling the behavior of CH4 in planetary atmospheres.

Vuskovic, L.; Trajmar, S.

1983-01-01

319

Longitudinal and transverse modes of slosh wave excitation in rotating dewar associated with gravity jitters  

NASA Technical Reports Server (NTRS)

Characteristics of slosh waves based on the dynamical behavior of oscillations at the liquid-vapor interface have been investigated. Twelve case studies of slosh wave excitation due to various frequencies of gravity jitters under different rotating speeds of the propellant tank and different levels of background gravity environment have been simulated. The study shows that slosh waves excited inside the spacecraft propellant tank are characterized by the lowest frequency of the waves initiated, frequencies of the gravity jitters imposed on the propellant system, the levels of background gravity environment, and dewar rotating speeds. Conditions for suppression and amplification of the slosh waves are discussed.

Hung, R. J.; Lee, C. C.; Leslie, F. W.

1991-01-01

320

Excitation and Detection of Surface Waves on Normal and Superfluid 3He  

NASA Astrophysics Data System (ADS)

We describe the measurement principles to excite and detect surface waves on liquid helium at very low temperatures. We excited the waves mechanically by rocking the whole cryostat with frequencies of few hertz. The waves were detected capacitively with an interdigital capacitor on a vertical wall of the cuboid experimental volume. In superfluid 3He at around 0.2 mK at least eleven surface resonances were observed below 11 Hz whereas in normal fluid only a few resonances were observable above 50 mK.

Manninen, M. S.; Kaikkonen, J.-P.; Peri, V.; Rysti, J.; Todoshchenko, I.; Tuoriniemi, J.

2014-04-01

321

Semiconductor Nanorod Liquid Crystals  

Microsoft Academic Search

Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for

Liang-Shi Li; Joost Walda; Liberato Manna; A. Paul Alivisatos

2002-01-01

322

Volatile liquid storage system  

Microsoft Academic Search

This patent describes a method of collecting and abating emission from a volatile liquid in an above ground storage tank. It comprises the liquid storage tank having a bottom, a vertical cylindrical circular wall having a lower edge portion joined to the bottom, and an external fixed roof, the tank having an internal floating roof floating on a volatile liquid

R. J. Laverman; P. J. Winters; J. K. Rinehart

1992-01-01

323

Renewable liquid reflection grating  

DOEpatents

A renewable liquid reflection grating. Electrodes are operatively connected to a conducting liquid in an arrangement that produces a reflection grating and driven by a current with a resonance frequency. In another embodiment, the electrodes create the grating by a resonant electrostatic force acting on a dielectric liquid.

Ryutov, Dmitri D.; Toor, Arthur

2003-10-07

324

User Guide: Liquids NMR  

E-print Network

User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C Software Pub. No. 01-999161-00, Rev. B0801 #12;User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C Software Pub. No. 01-999161-00, Rev. B0801 #12;User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C

Zhou, Pei

325

Got Thickened Liquids?  

Microsoft Academic Search

The utilization of new technology combined with an old process in need of updating led to the production of acceptable, affordable, safe and consistent thickened liquids. Due to the limited variety and high cost of pre-packaged thickened liquids. Nutrition and Food Service continued to individually mix thickened liquids by hand. This resulted in variable viscosity and unacceptable products. These inconsistencies

C. Adams; A. M. Barrett; B. Burgess; J. Daniel; M. Elghayesh

1998-01-01

326

PREFACE: 6th Liquid Matter Conference  

NASA Astrophysics Data System (ADS)

This special issue of Journal of Physics: Condensed Matter contains the Proceedings of the 6th Liquid Matter Conference held in Utrecht, The Netherlands, 2-6 July 2005. The three-yearly Liquid Matter Conference is organized by the Liquids Section of the Condensed Matter Division of the European Physical Society. This series of meetings began in Lyon in 1990. The most recent meeting was held in 2003 in Konstanz. The aim of the Liquid Matter Conferences is to bring together scientists working on the liquid state of matter. This rapidly growing field includes the physics, chemistry, biology and chemical engineering of liquid matter as well as various applied research areas. In fact, the Utrecht meeting had, for the first time, a special session devoted to Fundamental Challenges in Applied Liquid Physics and Microfluidics. The Utrecht meeting had 760 registered participants from four continents. An important event at this meeting was the award of the First Liquid Matter Prize of the European Physical Society to Professor Jean-Pierre Hansen FRS, of Cambridge University. In addition to a plenary speech by the recipient of the Liquid Matter Prize, the scientific programme consisted of 10 plenary lectures, 117 symposia talks, 25 of which were keynote lectures and some 650 poster contributions. The meeting also hosted a one-day symposium of the Division of Liquids and Interfaces of the Chemical Sciences division of NWO. This special issue of Journal of Physics: Condensed Matter contains 61 of the oral communications. Liquid state physics is at the interface of many fields of research. As a consequence, many of the attendants come from adjacent fields and find in the Liquid Matter Conference a forum to meet experts from other areas of research. This aspect of the Liquid Matter Conference makes it an exciting meeting as it not only offers the participants an up-to-date picture of the status of research into the liquid state of matter, but it also allows them to establish new (and often unexpected) trans-disciplinary contacts for joint scientific endeavours. This applies in particular to the area of soft condensed matter such as colloidal suspensions, polymeric systems and biological materials. The conference was held at the Uithof, the campus of the University of Utrecht. The organizers gratefully acknowledge the generosity of the University and City of Utrecht, which enabled us to stage both the scientific part of the conference and several festive and cultural events in some of the most attractive venues of the Netherlands. We were also delighted by the substantial contributions offered by the sponsors of the 6th Liquid Matter Conference. With this support it became possible to support a large number of scientists who would otherwise not have been able to attend. Finally, we owe a great debt of gratitude to the secretarial staff of the conference and the many students, postdocs and other colleagues who helped tirelessly (and very efficiently) to make the conference run smoothly. The Board of the Liquids Section of the European Physical Society decided that the 7th Liquid Matter Conference will be held in Lund (Sweden). The tentative dates are Friday 27 June 2008 to Tuesday 1 July 2008.

Dijkstra, Marjolein; van Roij, René; Vroege, Gert Jan; Lekkerkerker, Henk; Frenkel, Daan

2005-11-01

327

Separating carbon dioxide and ethane by liquid-liquid extraction  

Microsoft Academic Search

A mixture of carbon dioxide and ethane derived from a prior separation stage or recovery process is separated by liquid-liquid extraction. One of the liquids is a liquid azeotrope of carbon dioxide and ethane. The extraction liquid is a liquid hydrocarbon with more carbon atoms than ethane, that is, a hydrocarbon having at least 3 carbon atoms. In the extraction

Styring; R. E. Jr

1982-01-01

328

Dynamics of Excited Granular Systems  

NASA Astrophysics Data System (ADS)

Getting a hydrodynamic sort of behavior for excited granular systems is a delicate matter. In the case of ordinary (conservative) fluid systems the hydrodynamic limit is the limit of small Knudsen number. For granular systems such limit may lead to inconsistencies unless carefully performed. We present quite general gas-dynamic equations---derived from kinetic theory---which correctly describe highly excited granular systems. The theory describes a system of hard spheres (disks really) with normal restitution coefficient r and it requires no constitutive equations (dynamic equations take their place) [R. Ramirez, D. Risso, R. Soto, and P. Cordero, Phys. Rev. E 62, 2521 (2000); D. Risso, P. Cordero, Phys. Rev. E. 65 021304 (2002)]. Well known analytic results such as the presence of a fourth cumulant in the velocity distribution function are reproduced exactly. The formalism also predicts Bénard's type of convection triggerd by the granular temperature gradient that is dynamically created because of the inelastic nature of the collisons [R. Ramirez, D. Risso, and P. Cordero, Phys. Rev. Letters 85 1230 (2000); X. He, B. Meerson and G. Doolen, Phys. Rev. E 65 030301 (2002)]. A quasi-homogenoeus solution is also described in detail.

Cordero, Patricio; Risso, Dino

2002-08-01

329

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii ! If ) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If ) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga...

Diriken, J; Balabanski, D; Blasi, N; Blazhev, A; Bree, N; Cederkäll, J; Cocolios, T E; Davinson, T; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V N; Fraille, L M; Franchoo, S; Georgiev, G; Gladnishki, K; Huyse, M; Ivanov, O V; Ivanov, V S; Iwanicki, V; Jolie, J; Konstantinopoulos, T; Kröll, Th; Krücken, R; Köster, U; Lagoyannis, A; Bianco, G Lo; Maierbeck, P; March, B A; Napiarkowski, P; Patronis, N; Pauwels, D; Reiter, P; Seliverstov, M; Sletten, G; Van de Walle, J; Van Duppen, P; Voulot, D; Walters, W B; Warr, N; Wenander, F; Wrzosek, K

2010-01-01

330

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkäll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekström; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Kröll; R. Krücken; U. Köster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

2010-11-25

331

Dual excitation multiphase electrostatic drive  

SciTech Connect

A novel electrostatic drive technology named Dual Excitation Multiphase Electrostatic Drive (DEMED) was presented. A basic DEMED consisted of two plastic films in which 3-phase parallel electrodes were embedded and was driven by a 3-phase ac excitation to the electrodes. Static characteristics of DEMED were calculated and tested and the results agreed very well. Three prototype motors of DEMED were fabricated using commercially available technique. The first prototype consisted of a single slider and stator and generated a linear motion with a slider`s motion range of about 5mm. It weighed 7g and generated a power of 1.6W and a thrust force of 4.4N. The second prototype consisted of 50 layer stack of linear motors, summing their outputs. It weighed 3.6kg and generated a propulsive force of 310N being powered with boosted commercial 3-phase electricity. The third prototype consisted of a rotor and a stator in which electrodes were arranged radially and generated rotational motion. The maximum power of 36mW was generated by the prototype weighing only 260mg for its rotor and stator. From the results of the numerical calculation, a practical design methodology for the motor was determined. An optimal design for a motor employing currently available material and fabrication techniques is provided as an example. Analyses predict that force generation over the interfacial area between the slider and stator of this motor would be 3,900N/m{sup 2}.

Niino, Toshiki [Inst. of Physical and Chemical Research, Wako, Saitama (Japan); Higuchi, Toshiro [Univ. of Tokyo (Japan); [Kanagawa Academy of Science and Technology, Kawasaki, Kanagawa (Japan); Egawa, Saku [Hitachi Ltd., Tsuchiura, Ibaraki (Japan). Mechanical Engineering Research Lab.

1995-12-31

332

Propagation of a liquid-liquid explosion  

SciTech Connect

Direct contact between two liquids, one cold and the other hot, may be precluded by the presence of a vapor film. Bridging of this film by one or both fluids results in rapid local boiling, which may initiate a propagating liquid-liquid explosion. A mechanism is discussed for the propagation that involves implosion of the film, rapid mixing of the fluids, heat exchange to warm the cold fluid above the temperature for spontaneous nucleation, and the explosive generation of vapor, which in turn continues to sustain the film implosion. Plausibility for the model is demonstrated by means of numerical studies by high-speed computer.

Harlow, F.H.; Ruppel, H.M.

1981-08-01

333

Gapless Spin-Liquid Phase in an Extended Spin 1/2 Triangular Heisenberg Model  

NASA Astrophysics Data System (ADS)

We numerically study the Heisenberg models on triangular lattices by extending it from the simplest equilateral lattice with only the nearest-neighbor exchange interaction. We show that, by including an additional weak next-nearest-neighbor interaction, a quantum spin-liquid phase is stabilized against the antiferromagnetic order. The spin gap (triplet excitation gap) and spin correlation at long distances decay algebraically with increasing system size at the critical point between the antiferromagnetic phase and the spin-liquid phase. This algebraic behavior continues in the spin-liquid phase as well, indicating the presence of an unconventional critical (algebraic spin-liquid) phase characterized by the dynamical and anomalous critical exponents z + ? ˜ 1. Unusually small triplet and singlet excitation energies found in extended points of the Brillouin zone impose constraints on this algebraic spin liquid.

Kaneko, Ryui; Morita, Satoshi; Imada, Masatoshi

2014-09-01

334

Radiation monitor for liquids  

DOEpatents

A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans.

Koster, James E. (Los Alamos, NM); Bolton, Richard D. (Los Alamos, NM)

1999-01-01

335

Radiation monitor for liquids  

DOEpatents

A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

Koster, J.E.; Bolton, R.D.

1999-03-02

336

Liquid/Gas Vortex Separator  

NASA Technical Reports Server (NTRS)

Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.

Morris, B. G.

1986-01-01

337

Liquid Wall Chambers  

SciTech Connect

The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

Meier, W R

2011-02-24

338

Duality of liquids  

PubMed Central

Liquids flow, and in this sense are close to gases. At the same time, interactions in liquids are strong as in solids. The combination of these two properties is believed to be the ultimate obstacle to constructing a general theory of liquids. Here, we adopt a new approach: instead of focusing on the problem of strong interactions, we zero in on the relative contributions of vibrational and diffusional motion. We show that liquid energy and specific heat are given, to a very good approximation, by their vibrational contributions as in solids over almost entire range of relaxation time in which liquids exist as such, and demonstrate that this result is consistent with liquid entropy exceeding solid entropy. Our analysis therefore reveals an interesting duality of liquids not hitherto known: they are close to solids from the thermodynamic perspective and to flowing gases. We discuss several implications of this result. PMID:23851971

Trachenko, K.; Brazhkin, V. V.

2013-01-01

339

Liquid cooled exhaust flange  

SciTech Connect

This patent describes a liquid-cooled exhaust flange for mating a liquid-jacketed exhaust conduit system to a conventional internal combustion engine turbo charger discharge port. It comprises: a generally cylindrical elongated exhaust conduit member adapted to mate in sandwiched relationship between the turbo charger housing and the liquid-jacketed exhaust conduit system; a cooling liquid-jacket housing internally and concentrically connected to the exhaust conduit member adapted to mate in fluidly communicating relationship with a flow of cooling liquid within the liquid-jacketed exhaust conduit system; the liquid-jacket housing covering a substantial portion of the external surface area of the exhaust conduit member so as to reduce the temperature of the external surface of the exhaust flange.

Woods, W.E.

1990-04-24

340

The Liquid Crystal Institute  

NSDL National Science Digital Library

The homepage of the Liquid Crystal Institute (LCI) presents gorgeous color images produced from liquid crystal, research overviews, technology invention abstracts, news and conference links, and more. LCI is part of a consortium, selected by the National Science Foundation, based at the Center for Advanced Liquid Crystalline Optical Materials (ALCOM) at Kent State University. The consortium includes Kent State University, Case Western Reserve University, and the University of Akron. ALCOM focuses on interdisciplinary research and development of liquid crystal optoelectronic materials, technology, and consumer products. A few of the liquid crystal studies featured here are fine structure and oily streak defects, magneto-optic response, text display applications, and organic synthesis. One of LCI's projects, the Polymers and Liquid Crystals Textbook, was featured in the December 13, 1996 Scout Report for Science & Engineering The LCI Website is not especially well-organized, but it contains lots of information about liquid crystal technology.

341

Inelastic XInelastic X--ray Scattering byray Scattering by Electronic ExcitationsElectronic ExcitationsElectronic ExcitationsElectronic Excitations  

E-print Network

and Selected Results El t S ifi A li ti (XRS/XES/FPY XAS)Element-Specific Applications (XRS/XES/FPY-XAS) XRS at the K-edge of TM: NiO, Sr2CuO3, La2CuO4/La2NiO4 ... Possible Further Developments and Outlook Possible: High pressure phases of H2O, liquid & solid He, SiO2, Ba8Si46 ... XES/XAS: P/T-induced charge

Ohta, Shigemi

342

Anyonic liquids in nearly saturated spin chains.  

PubMed

Most Heisenberg-like spin chains flow to a universal free-fermion fixed point near the magnetic-field induced saturation point. Here, we show that an exotic fixed point, characterized by two species of low-energy excitations with mutual anyonic statistics, may also emerge in such spin chains if the dispersion relation has two minima. By using bosonization, two-magnon exact calculations, and numerical density-matrix-renormalization-group calculations, we demonstrate the existence of this anyonic-liquid fixed point in an xxz spin chain with up to second-neighbor interactions. We also identify a range of microscopic parameters, which support this phase. PMID:25615377

Rahmani, Armin; Feiguin, Adrian E; Batista, Cristian D

2014-12-31

343

Anyonic Liquids in Nearly Saturated Spin Chains  

NASA Astrophysics Data System (ADS)

Most Heisenberg-like spin chains flow to a universal free-fermion fixed point near the magnetic-field induced saturation point. Here, we show that an exotic fixed point, characterized by two species of low-energy excitations with mutual anyonic statistics, may also emerge in such spin chains if the dispersion relation has two minima. By using bosonization, two-magnon exact calculations, and numerical density-matrix-renormalization-group calculations, we demonstrate the existence of this anyonic-liquid fixed point in an xxz spin chain with up to second-neighbor interactions. We also identify a range of microscopic parameters, which support this phase.

Rahmani, Armin; Feiguin, Adrian E.; Batista, Cristian D.

2014-12-01

344

Heat transfer in gas-liquid and liquid-liquid two phase plug flow systems  

Microsoft Academic Search

Liquid-gas and liquid-liquid two phase flows are examined. It has been recently documented that gas-liquid segmented flows offer a thermal enhancement advantage over single phase flows, since the plug flow (Taylor flow) regime produces internal circulations which enhance radial transport. Additional strategies in liquid-gas and liquid-liquid cooling are being pursued with liquid cooled heat sinks. Proper heat transfer and pressure

N. Janes; Y. S. Muzychka; B. Guy; E. J. Walsh; P. Walsh

2010-01-01

345

Intensification of Liquid-Liquid Contacting Processes  

E-print Network

different energy sources and were investigated in this dissertation. They include electrostatic liquid spraying based on electric field and a two-disc spinning disc reactor based on high gravity field. Interfacial turbulence plays an important role...

Qiu, Zheyan

2010-09-01

346

Magnetorotational Instability in Liquid Metal Couette Flow  

E-print Network

Despite the importance of the magnetorotational instability (MRI) as a fundamental mechanism for angular momentum transport in magnetized accretion disks, it has yet to be demonstrated in the laboratory. A liquid sodium alpha-omega dynamo experiment at the New Mexico Institute of Mining and Technology provides an ideal environment to study the MRI in a rotating metal annulus (Couette flow). A local stability analysis is performed as a function of shear, magnetic field strength, magnetic Reynolds number, and turbulent Prandtl number. The later takes into account the minimum turbulence induced by the formation of an Ekman layer against the rigidly rotating end walls of a cylindrical vessel. Stability conditions are presented and unstable conditions for the sodium experiment are compared with another proposed MRI experiment with liquid gallium. Due to the relatively large magnetic Reynolds number achievable in the sodium experiment, it should be possible to observe the excitation of the MRI for a wide range of w...

Noguchi, K; Colgate, S A; Nordhaus, J; Beckley, H F

2002-01-01

347

Back reaction of excitations on a vortex  

SciTech Connect

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component. {copyright} {ital 1997} {ital The American Physical Society}

Arodz, H.; Hadasz, L. [Jagellonian University, Institute of Physics, Reymonta 4, 30-059 Cracow (Poland)] [Jagellonian University, Institute of Physics, Reymonta 4, 30-059 Cracow (Poland)

1997-01-01

348

Back reaction of excitations on a vortex  

NASA Astrophysics Data System (ADS)

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component.

Arod?, Henryk; Hadasz, Leszek

1997-01-01

349

Chemical dynamics of vibrationally excited molecules: Controlling reactions in gases and on surfaces  

PubMed Central

Experimental studies of the chemical reaction dynamics of vibrationally excited molecules reveal the ability of different vibrations to control the course of a reaction. This Perspective describes those studies for the prototypical reaction of vibrationally excited methane and its isotopologues in gases and on surfaces and looks to the prospects of similar studies in liquids. The influences of vibrational excitation on the CH bond cleavage in a single collision reaction with Cl and in dissociative adsorption on a Ni surface bear some striking similarities. Both reactions are bond-selective processes in which the initial preparation of a molecular eigenstate containing a large component of CH stretching results in preferential cleavage of that bond. It is possible to cleave either the CH bond or CD bond in the reaction of Cl with CH3D, CH2D2, or CHD3 and, similarly, to use initial excitation of the CH stretch to promote dissociation of CHD3 to CD3 and H on a Ni surface. Different vibrational modes, such as the symmetric and antisymmetric stretches in CH3D or CH4, lead to very different reactivities, and molecules with the symmetric stretching vibration excited can be as much as 10 times more reactive than ones with the antisymmetric stretch excited. The origin of this behavior lies in the change in the vibrational motion induced by the interaction with the atomic reaction partner or the surface. PMID:18765816

Crim, F. Fleming

2008-01-01

350

Comparison of two-photon imaging depths with 775 nm excitation and 1300 nm excitation  

NASA Astrophysics Data System (ADS)

We quantitatively compared the maximal two-photon fluorescence microscopy imaging depth achieved with 775 nm excitation to that achieved with 1300 nm excitation through ex-vivo TPM of blood vessels in the mouse brain. We achieved high contrast imaging of labeled blood vessels at approximately twice the depth at 1300 nm excitation as at 775 nm excitation. We also measured the two-photon excitation cross-sections of several commercially available fluorophores at 1220-1320 nm. We found that some of these fluorophores reveal comparable if not better cross-section values than those of the widely used dyes excited by shorter wavelength light.

Kobat, Demirhan; Wong, Angela; Schaffer, Chris B.; Xu, Chris

2009-02-01

351

High Frequency Electromechanical Imaging of Ferroelectrics in a Liquid Environment  

SciTech Connect

The coupling between electrical and mechanical phenomena is a ubiquitous feature of many information and energy storage materials and devices. In addition to involvement in performance and degradation mechanisms, electromechanical effects underpin a broad spectrum of nanoscale imaging and spectroscopies including piezoresponse force and electrochemical strain microscopies. Traditionally, these studies are conducted under ambient conditions. However, applications related to imaging energy storage and electrophysiological phenomena require operation in a liquid phase and therefore the development of electromechanical probing techniques suitable to liquid environments. Due to the relative high conductivity of most liquids and liquid decomposition at low voltages, the transfer of characterization techniques from ambient to liquid is not straightforward. Here we present a detailed study of ferroelectric domain imaging and manipulation in thin film BiFeO{sub 3} using piezoresponse force microscopy in liquid environments as model systems for electromechanical phenomena in general. We explore the use of contact resonance enhancement and the application of multifrequency excitation and detection principles to overcome the experimental problems introduced by a liquid environment. Understanding electromechanical sample characterization in liquid is a key aspect not only for ferroelectric oxides but also for biological and electrochemical sample systems.

Jesse, Stephen [ORNL; Chu, Ying-Hao [National Chiao Tung University, Hsinchu, Taiwan; Kalinin, Sergei V [ORNL

2012-01-01

352

Liquid Crystal Materials and Liquid Crystal Displays  

Microsoft Academic Search

Since the early 1970s, three major prerequisites have brought the success of the liquid crystal display (LCD) technology to its key role of today. Namely, the discovery of electro-optical field-effects on which the displays are based, the successful search for liquid crystals (LCs) with material properties that meet the complex requirements of electro-optical effects and render the effects applicable in

Martin Schadt

1997-01-01

353

Critical Phenomena in Liquid-Liquid Mixtures  

NASA Astrophysics Data System (ADS)

Critical phenomena provide intriguing and essential insight into many issues in condensed matter physics because of the many length scales involved. Large density or concentration fluctuations near a system's critical point effectively mask the identity of the system and produce universal phenomena that have been well studied in simple liquid-vapor and liquid-liquid systems. Such systems have provided useful model systems to test theoretical predictions which can then be extended to more complicated systems. Along various thermodynamic paths, several quantities exhibit a simple power-law dependence close to the critical point. The critical exponents describing these relationships are universal and should depend only on a universality class determined by the order-parameter and spatial dimensionality of the system. Liquid gas, binary fluid mixtures, uniaxial ferromagnetism, polymer-solvent, and protein solutions all belong to the same (Ising model) universality class. The diversity of critical systems that can be described by universal relations indicates that experimental measurements on one system should yield the same information as on another. Our experimental investigations have tested existing theory and also extended universal behavior into new areas. By measuring the coexistence curve, heat capacity, thermal expansion and static light scattering (turbidity) in various liquid-liquid and polymer-solvent systems, we have determined critical exponents and amplitudes that have sometimes confirmed and other times challenged current theory. Recent experiments investigating the heat capacity and light scattering in a liquid-liquid mixture very close to the critical point will be discussed. This research is currently supported by The Petroleum Research Fund and by NASA grant NAG8-1433 with some student support from NSF-DMR 9619406.

Jacobs, D. T.

2000-04-01

354

Supersymmetric approach to excited states.  

PubMed

We present here a supersymmetric (SUSY) approach for determining excitation energies within the context of a quantum Monte Carlo scheme. By using the fact that SUSY quantum mechanics gives rises to a series of isospectral Hamiltonians, we show that Monte Carlo ground-state calculations in the SUSY partners can be used to reconstruct accurately both the spectrum and states of an arbitrary Schrodinger equation. Since the ground state of each partner potential is nodeless, we avoid any "node" problem typically associated with the Monte Carlo technique. Although we provide an example of using this approach to determine the tunneling states in a double-well potential, the method is applicable to any 1D potential problem. We conclude by discussing the extension to higher dimensions. PMID:19919079

Bittner, Eric R; Maddox, Jeremy B; Kouri, Donald J

2009-12-31

355

Excited baryons in lattice QCD  

NASA Astrophysics Data System (ADS)

We present the first results for the masses of positive and negative parity excited baryons calculated in lattice QCD using an O(a2)-improved gluon action and a fat-link irrelevant clover (FLIC) fermion action in which only the irrelevant operators are constructed with APE-smeared links. The results are in agreement with earlier calculations of N* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner. A correlation matrix analysis reveals two low-lying JP=1/2- states with a small mass splitting. The study of different ? interpolating fields suggests a similar splitting between the lowest two ?1/2- octet states. However, the empirical mass suppression of the ?*(1405) is not evident in these quenched QCD simulations, suggesting a potentially important role for the meson cloud of the ?*(1405) and/or a need for more exotic interpolating fields.

Melnitchouk, W.; Bilson-Thompson, S.; Bonnet, F. D.; Hedditch, J. N.; Lee, F. X.; Leinweber, D. B.; Williams, A. G.; Zanotti, J. M.; Zhang, J. B.

2003-06-01

356

Coulomb excitation of 107Sn  

NASA Astrophysics Data System (ADS)

The radioactive isotope 107Sn was studied using Coulomb excitation at the REX-ISOLDE facility at CERN. This is the lightest odd-Sn nucleus examined using this technique. The reduced transition probability of the lowest-lying 3/2+ state was measured and is compared to shell-model predictions based on several sets of single-neutron energies relative to 100Sn . Similar to the transition probabilities for the 2+ states in the neutron-deficient even-even Sn nuclei, the measured value is underestimated by shell-model calculations. Part of the strength may be recovered by considering the ordering of the d_{5/2} and g_{7/2} single-neutron states.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2012-07-01

357

Excited Baryons in Holographic QCD  

SciTech Connect

The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

2011-11-08

358

Effect of baffle on the asymmetric gravity jitter excited slosh waves in microgravity  

NASA Technical Reports Server (NTRS)

The paper investigates the dynamical behavior of fluids affected by asymmetric gravity jitter oscillations, in particular, the effect of surface tension on partially filled rotating fluids in a full-scale Gravity Probe-B Spacecraft dewar tank, with and without the installation of the baffle-board, imposed by time-dependent directions of background gravity. The time-sequence evolution of the 3D behavior of the liquid-vapor interface oscillations resulting in the excitation of large amplitude slosh waves exerted by gravity jitter disturbances are examined. It is shown that the damping effect provided by baffle reduces the amplitude of slosh wave excitation and lowers the degree of asymmetry in the liquid-vapor distribution.

Hung, R. J.; Lee, C. C.; Leslie, F. W.

1993-01-01

359

Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC  

E-print Network

Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC: markst@nd.edu #12;Abstract Characterization of liquid-liquid equilibrium (LLE) in system containing ionic; Ionic liquids; Octanol-water partition coefficients; Excess Gibbs energy models; Electrolyte models #12

Stadtherr, Mark A.

360

Vibrationally Excited C4H  

NASA Astrophysics Data System (ADS)

Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C4H were observed in the millimeter band between 69 and 364 GHz in a low pressure glow discharge, and two of these were observed in a supersonic molecular beam between 19 and 38 GHz. All have rotational constants within 0.4% of the {{X}2}{{{? }}+} ground vibrational state of C4H and were assigned to new bending vibrational levels, two each with 2{? } and 2{\\Pi } vibrational symmetry. The new levels are tentatively assigned to the 1{{? }6} and 1{{? }5} bending vibrational modes (both with 2{\\Pi } symmetry), and the 1{{? }6}+1{{? }7} and 1{{? }5}+1{{? }6} combination levels (2{? } symmetry) on the basis of the derived spectroscopic constants, relative intensities in our discharge source, and published laser spectroscopic and quantum calculations. Prior spectroscopic constants in the 1{{? }7} and 2{{? }7} levels were refined. Also presented are interferometric maps of the ground state and the 1{{? }7} level obtained with the Submillimeter Array (SMA) near 257 GHz which show that C4H is present near the central star in IRC+10216. We found no evidence with the SMA for the new vibrationally excited levels of C4H at a peak flux density averaged over a 3\\prime\\prime synthesized beam of ?slant 0.15 Jy/beam in the 294-296 and 304-306 GHz range, but it is anticipated that rotational lines in the new levels might be observed in IRC+10216 when ALMA attains its full design capability.

Cooksy, Andrew L.; Gottlieb, C. A.; Killian, T. C.; Thaddeus, P.; Patel, Nimesh A.; Young, Ken H.; McCarthy, M. C.

2015-02-01

361

Collisional energy transfer from excited nitrogen dioxide  

NASA Astrophysics Data System (ADS)

The radiative lifetimes of gaseous nitrogen dioxide excited by pulsed, tunable dye laser radiation are determined for excitation wavelengths ranging from 400 to 750 nm. When the data are expressed in the form of zero-pressure radiative rate constants (k(sub 0)/s exp -1), they fit a linear equation with respect to excitation energy. This fit predicts a radiative lifetime of 64 microseconds for 400 nm excitation and 102 microseconds at 750 nm. The effects of pressure, observation delay time, and wavelength range of the fluorescence detection apparatus are determined for both radiative lifetime and quenching constant. Dispersed fluorescence spectra from excited nitrogen dioxide are analyzed into three-parameter functions that approximate the corresponding excited state population distributions. Energy transfer from nitrogen dioxide excited at 532 nm and colliding with thirteen buffer gases is studied by this population deconvolution method. The energy removal rate constants increase in the order Ne, Ar, Kr, Xe, He, CO, N2, O2, NO, NO2, CO2, SF6, SO2. The energy transfer rate constant is strongly correlated with the number of degrees of freedom of the buffer molecule and with low vibrational frequencies of the buffer molecule. Population deconvolution from excited nitrogen dioxide fluorescence spectra is again employed to find energy removal rate constants for the NO2*-NO2 collisions, excited by dye laser at 475.34, 435.04, and 400.00 nm. The energy transfer rate constant increases with decreasing excitation wavelength. The energy removal rate constant between 400 and 532 nm excitation increases as the (3.6 +/- 0.4) power of the excitation photon energy.

Patten, K. O.

1991-05-01

362

Photobleaching in Two-Photon Excitation Microscopy  

Microsoft Academic Search

The intensity-squared dependence of two-photon excitation in laser scanning microscopy restricts excitation to the focal plane and leads to decreased photobleaching in thick samples. However, the high photon flux used in these experiments can potentially lead to higher-order photon interactions within the focal volume. The excitation power dependence of the fluorescence intensity and the photobleaching rate of thin fluorescence samples

George H. Patterson; David W. Piston

2000-01-01

363

Gluonic excitations in the hadronic spectrum  

NASA Astrophysics Data System (ADS)

I describe progress made by the Hadron Spectrum Collaboration in understanding the role that excitations of the gluonic field play in determining the spectrum of hadrons. This is achieved through calculations of the hadron spectrum using lattice QCD techniques. Clear signals for the lightest set of hybrid mesons and baryons are presented, and a proposal that they correspond to the same chromomagnetic excitation is made. The prospects for studying the decay properties of excited hadrons are briefly discussed.

Dudek, Jozef

2014-06-01

364

Excitable Optical Waves in Semiconductor Microcavities  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally and theoretically the existence of excitable optical waves in semiconductor microcavities. Although similar to those observed in biological and chemical systems, these excitable optical waves are self-confined. This is due to a new dynamical scenario, where a stationary Turing pattern controls the propagation of waves in an excitable medium, thus bringing together the two paradigms of dynamical behavior (waves and patterns) in active media.

Marino, Francesco; Balle, Salvador

2005-03-01

365

Design evaluation: S-band exciters  

NASA Technical Reports Server (NTRS)

A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

1974-01-01

366

Quasiparticle excitations in superdeformed [sup 192]Hg  

SciTech Connect

For the first time, two excited superdeformed (SD) bands have been observed in the double closed shell superdeformed nucleus [sup 192]Hg. One of the SD bands exhibits a pronounced peak in the dynamic moment of inertia which is interpreted as a crossing between two excited SD configurations involving the [ital N]=7 intruder and the [512]5/2 orbitals. This is only the second occurrence of such a crossing in a SD nucleus around [ital A]=190. The second excited SD band has near identical transition energies to an excited SD band in [sup 191]Hg.

Fallon, P. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Lauritsen, T.; Ahmad, I.; Carpenter, M.P. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Cederwall, B.; Clark, R.M. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Crowell, B. (Argonne National Labortory, Argonne, Illinois 60439 (United States)); Deleplanque, M.A.; Diamond, R.M. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Gall, B.; Hannachi, F. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, IN2P-CNRS bat 104-108, F-91405 Orsay Cedex (France)); Henry, R.G.; Janssens, R.V.F.; Khoo, T.L. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Korichi, A. (Institut de Physique Nucleaire, IN2P3-CNRS bat 104, F-91406 Orsay Cedex (France)); Lee, I.Y.; Macchiavelli, A.O. (Nuclear Science Division, Lawrence

1995-04-01

367

Break-up dynamics of fluctuating liquid threads Julien Petit, David Rivire, Hamid Kellay, and Jean-Pierre Delville  

E-print Network

1 Break-up dynamics of fluctuating liquid threads Julien Petit, David Rivière, Hamid Kellay;2 Abstract: The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from to the thermally excited interfacial fluctuations, as for nano-jet break-up or the fragmentation of thermally

Paris-Sud XI, Université de

368

Optical study of long-lived size quantized vibrational excitations in porous aluminum oxide  

Microsoft Academic Search

The dynamics of terahertz phonons generated by laser pumping at liquid helium temperatures in monolithic transparent highly porous samples of γ-AlâOâ synthesized by the sol-gel technique is studied from the selectively excited, phonon-induced anti-Stokes luminescence (the ²E-⁴Aâ line) of impurity Cr{sup 3+} ions. The spectrum of generated phonons exhibits, in addition to the long-lived (tenths of milliseconds) thermalized Planck`s distribution,

A. A. Kaplyanskii; S. P. Feofilov; R. I. Zakharchenya

1995-01-01

369

Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge  

Microsoft Academic Search

The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115–200 nm.\\u000a The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed\\u000a molecule band around the Xe I resonance line at ? = 147 nm and the mixed molecule

B. Krylov; G. Gerasimov; A. Morozov; A. Arnesen; R. Hallin; F. Heijkenskjold

2000-01-01

370

Mechanical models for tanks containing two liquids  

SciTech Connect

The well-known Housner`s mechanical model for laterally excited rigid tanks that contain one liquid is generalized to permit consideration of tanks that contain two liquids under the horizontal and rocking base motions. Two mechanical models are developed herein; one is for rigid tanks and the other for flexible tanks. The model for rigid tanks has a rigidly attached mass and infinite number of elastically supported masses. The rigid attached mass which possesses a mass moment of inertia represents the impulsive component, whereas the elastically supported masses which do not possess mass moment of inertia represent the convective component of the response. These masses and their heights are chosen such that, under the same base motions, the base shear and base moments of the model match those of the original liquid-tank system. The spring stiffness constants for the elastically supported masses in the model are determined from the sloshing frequencies of the liquid-tank system. The model for flexible tanks, however, only represents the impulsive action of the hydrodynamic response. It has an elastically supported mass that does not possess mass moment of inertia and a member that has no mass but possesses a mass moment of inertia. This latter model is proposed for the study of the effect of the soil-structure interaction.

Tang, Y.

1994-06-01

371

Local energy landscape in a simple liquid  

NASA Astrophysics Data System (ADS)

It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure that defies precise definition. The potential energy landscape (PEL) approach is a very insightful way to conceptualize the structure-property relationship in liquids and glasses, particularly the effect of temperature and history. However, because of the highly multidimensional nature of the PEL it is hard to determine, or even visualize, the actual details of the energy landscape. In this article we introduce a modified concept of the local energy landscape (LEL), which is limited in phase space, and demonstrate its usefulness using molecular dynamics simulation on a simple liquid at high temperatures. The local energy landscape is given as a function of the local coordination number, the number of the nearest-neighbor atoms. The excitation in the LEL corresponds to the so-called ?-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.

Iwashita, T.; Egami, T.

2014-11-01

372

Local Energy Landscape in a Simple Liquid  

E-print Network

It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure which defies precise definition. The potential energy landscape (PEL) approach is a very insightful way to conceptualize the structure-property relationship in liquids and glasses, particularly on the effect of temperature and history. However, because of the highly multi-dimensional nature of the PEL it is hard to determine, or even visualize, the actual details of the energy landscape. In this article we introduce a modified concept of the local energy landscape (LEL) which is limited in phase space, and demonstrate its usefulness using molecular dynamics simulation on a simple liquid at high temperatures. The local energy landscape is given as a function of the local coordination number, the number of the nearest neighbor atoms. The excitations in the LEL corresponds to the so-called beta-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.

Takuya Iwashita; Takeshi Egami

2014-10-31

373

Local energy landscape in a simple liquid.  

PubMed

It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure that defies precise definition. The potential energy landscape (PEL) approach is a very insightful way to conceptualize the structure-property relationship in liquids and glasses, particularly the effect of temperature and history. However, because of the highly multidimensional nature of the PEL it is hard to determine, or even visualize, the actual details of the energy landscape. In this article we introduce a modified concept of the local energy landscape (LEL), which is limited in phase space, and demonstrate its usefulness using molecular dynamics simulation on a simple liquid at high temperatures. The local energy landscape is given as a function of the local coordination number, the number of the nearest-neighbor atoms. The excitation in the LEL corresponds to the so-called ?-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses. PMID:25493796

Iwashita, T; Egami, T

2014-11-01

374

Ultrasonic, Non-Invasive Classification/Discrimination of Liquid Explosives (LEs) and Threat Liquids from Non-Threat Liquids in Sealed Containers  

SciTech Connect

Government agencies and homeland security organizations are searching for more effective approaches for dealing with the increasing demand for inspections involving potential threat liquids and hazardous chemicals, including liquid explosives (LEs). The quantity and variability of hand-held and cargo-sized containers being shipped worldwide drives the need for rapid and effective ways for conducting non-intrusive inspections of liquid-filled containers of a diverse range of types, shapes and sizes. Such inspections need to quickly classify/discriminate between liquids within containers and also ascertain the presence of unexpected objects within a container. The science base, methodology and prototype device for classification/discrimination between classes of liquids has been developed. The Pacific Northwest National Laboratory (PNNL) has developed a methodology and prototype device for classification/discrimination of a wide variety of liquids (including threat liquids and their precursors), providing noninvasive liquid classification/discrimination capabilities using a nondestructive ultrasonic measurement approach for inspecting sealed containers. The Container Screening Device (CSD) employs frequency-modulated (FM) chirp excitation and pulse-compression signal processing techniques to measure ultrasonic velocity and a relative attenuation value for liquids within a container, and is capable of determining other acoustic properties from through-transmission, contact measurements over a wide frequency range. Recent algorithm developments are beginning to address the issues of container wall variations and thickness. A description of the basic science, measurement approach and sources of variability in the measurement will be presented and laboratory measurements acquired from a suite of commercial products and precursor liquids used in the manufacturing of Homemade Explosives (HMEs) will be given.

Diaz, Aaron A.; Cinson, Anthony D.; Tucker, Brian J.; Samuel, Todd J.; Morales, Romarie

2009-07-20

375

Monogroove liquid heat exchanger  

NASA Technical Reports Server (NTRS)

A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).

Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)

1990-01-01

376

Liquid level detector  

DOEpatents

A liquid level detector for conductive liquids for vertical installation in a tank, the detector having a probe positioned within a sheath and insulated therefrom by a seal so that the tip of the probe extends proximate to but not below the lower end of the sheath, the lower end terminating in a rim that is provided with notches, said lower end being tapered, the taper and notches preventing debris collection and bubble formation, said lower end when contacting liquid as it rises will form an airtight cavity defined by the liquid, the interior sheath wall, and the seal, the compression of air in the cavity preventing liquid from further entry into the sheath and contact with the seal. As a result, the liquid cannot deposit a film to form an electrical bridge across the seal.

Tshishiku, Eugene M. (Augusta, GA)

2011-08-09

377

Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container  

NASA Astrophysics Data System (ADS)

This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

2008-02-01

378

Liquid sheet radiator apparatus  

NASA Technical Reports Server (NTRS)

An external flow, liquid sheet radiator apparatus adapted for space applications has as its radiating surface a thin stable liquid sheet formed by fluid flow through a very narrow slit affixed to the sheet generator. As a result of surface tension forces, the sheet has a triangular shape and is collected into a simply designed collector positioned at the apex of the triangle. The specific power for the liquid sheet is virtually the same as the droplet sheet specific power.

Chubb, Donald L. (inventor)

1990-01-01

379

Icosahedral order in liquids  

SciTech Connect

The possibility of icosahedral order in liquids and its role in glass transition is discussed in a broad context of statistical mechanics of liquid. It is pointed out that the structures of glasses and liquids are described both in terms of the topology of atomic bond networks as well as the local distortion of the atomic bonds. While topology plays a dominant role in covalent glasses, local distortion is likely to be more important for metallic glasses.

Egami, Takeshi [ORNL

2007-01-01

380

Theoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers  

E-print Network

Theoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers James J. Feng Department and rheology of low-molecular-weight liquid crystals (LCs) and liquid crystalline polymers (LCPs). The latter­solid duality gives rise to much of the ``anomalous'' behavior of liquid crystal- line materials. When

Feng, James J.

381

Fast Laser Excitation and Ultrahigh Strain-Rate Deformation  

SciTech Connect

Phase evolution induced by single or repeated excitation with energetic femtosecond laser pulses is examined. Of primary interest is the solidification behavior of pure metals at deep undercoolings and self-organization in simple eutectic alloys. Time resolved measurements using third harmonic generation (THG) of light and ultrafast electron diffraction (UED) are employed to elucidate several issues related to fast laser excitation, including heat transport by ballistic and diffusional electrons through multilayer films, the dependence of crystallization velocities on materials properties, mechanisms controlling the transport of heat away from the crystal-liquid interface, and the possibility for quenching pure metals, such as Cu, Ni, and Fe, into the amorphous state. Special samples designed to maximize the quenching speed are developed. The properties of such pure metallic glasses, such as glass and crystallization temperatures, will be measured, if such samples are successfully produced. The measurements are complemented by molecular dynamics computer simulations of the solidification process. The second interest of this research is mesoscopic, self-organization of materials under repeated laser melting, with diffusional relaxation between pulses. We select binary alloys that are immiscible in the solid state but miscible in the liquid state, such as Ag-Cu. Femtosecond laser irradiation is employed to induce melting and to vary the melting time over a wide range, from a few ps to hundreds of ps. This enables us to perform critical experimental tests of key theoretical predictions self-organization in alloys under external forcing, in particular the existence of a threshold value of the forced mixing length for patterning to take place.

Robert Averback

2007-06-03

382

Electron excitation energy transfer from highly excited Cs atoms forming high Rydberg state atoms and molecules  

Microsoft Academic Search

The reactions of excited Cs atoms with various gases have been studied in a quadrupole mass spectrometer ion source. The excited atoms are formed in a thermionic converter (TIC) plasma and are sampled into the ion source as a molecular beam. Direct field ionization of the excited states from the plasma at field strengths up to 600 V\\/cm in the

Joergen Lundin; Leif Holmlid

1991-01-01

383

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media  

E-print Network

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media Statics#25; (#(~r) + !t)) #12; #12; #12; #12; #26;!+1 ; (2) where #26;(~r) and #(~r) are the polar coordinates the same kind of meander #12; NL3451 Vortex dynamics in excitable media 2 (a) (b) (c) (d) Figure 1. Typical

Biktashev, Vadim N.

384

Ultrasonic liquid level detector  

DOEpatents

An ultrasonic liquid level detector for use within a shielded container, the detector being tubular in shape with a chamber at its lower end into which liquid from in the container may enter and exit, the chamber having an ultrasonic transmitter and receiver in its top wall and a reflector plate or target as its bottom wall whereby when liquid fills the chamber a complete medium is then present through which an ultrasonic wave may be transmitted and reflected from the target thus signaling that the liquid is at chamber level.

Kotz, Dennis M. (North Augusta, SC); Hinz, William R. (Augusta, GA)

2010-09-28

385

Elasticity of liquid marbles.  

PubMed

Liquid marbles are liquid droplets covered densely with small particles. They exhibit hydrophobic properties even on hydrophilic surfaces and this behaviour is closely related to the Cassie wetting state and the phenomenon of superhydrophobicity. Typical liquid marbles are of millimetre size but their properties are analogous to smaller capsules and droplets of Pickering emulsions. We study water marbles covered with an uneven multilayer of polyethylene particles. Their elastic properties were assessed under quasi-static conditions. The liquid marbles are highly elastic and can sustain a reversible deformation of up to 30%. The spring constant is of the same order of magnitude as that for bare water droplets. Therefore the elasticity of the liquid marble is provided mainly by the liquid menisci between the particles. Upon further compression, the spring constant increases up to the point of breakage. This increase may be due to capillary attraction acting across the emerging cracks in the particle coating. The stress-strain curve for liquid marbles is similar to that obtained with liquid-filled microcapsules. A mechanical scaling description proposed for capsules is qualitatively applicable for liquid marbles. The exact mechanical role of the multilayer particle network remains elusive. PMID:25698501

Asare-Asher, Samuel; Connor, Jason N; Sedev, Rossen

2015-07-01

386

Liquid Crystal Optofluidics  

SciTech Connect

By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.

Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

2012-10-11

387

Liquid Metal Transformers  

E-print Network

The room temperature liquid metal is quickly emerging as an important functional material in a variety of areas like chip cooling, 3D printing or printed electronics etc. With diverse capabilities in electrical, thermal and flowing behaviors, such fluid owns many intriguing properties that had never been anticipated before. Here, we show a group of unconventional phenomena occurring on the liquid metal objects. Through applying electrical field on the liquid metals immersed in water, a series of complex transformation behaviors such as self-assembling of a sheet of liquid metal film into a single sphere, quick mergences of separate metal droplets, controlled self-rotation and planar locomotion of liquid metal objects can be realized. Meanwhile, it was also found that two accompanying water vortexes were induced and reliably swirled near the rotating liquid metal sphere. Further, effects of the shape, size, voltage, orientation and geometries of the electrodes to control the liquid metal transformers were clarified. Such events are hard to achieve otherwise on rigid metal or conventional liquid spheres. This finding has both fundamental and practical significances which suggest a generalized way of making smart soft machine, collecting discrete metal fluids, as well as flexibly manipulating liquid metal objects including accompanying devices.

Lei Sheng; Jie Zhang; Jing Liu

2014-01-30

388

Ultrasonic level sensors for liquids under high pressure  

NASA Astrophysics Data System (ADS)

An ultrasonic level sensor of novel design continuously measures the level of a liquid subjected to a high pressure (up to about 40 MPa), as is sometimes required for the effective transfer of the liquid. The sensor operates as a composite resonator fabricated from a standard high-pressure plug. A flat-bottom hole is machined into the plug along its center line. An ultrasonic transducer is bonded rigidly to the interior surface of the bottom wall, while the exterior surface is in contact with the liquid. Although the bottom wall is designed to satisfy the pressure code, it is still sufficiently thin to permit ready excitation of the axisymmetric plate modes of vibration. The liquid level is measured by a conventional pulse-echo technique. A prototype sensor was tested successfully in a 2300-l water vessel at pressures up to about 37 MPa. A spectral analysis of the transmitted pulse reveals that the flexural, extensional, thickness-shear, and radial plate modes are excited into vibration, but none of these appears to be significantly affected by the pressurization of the liquid.

Zuckerwar, A. J.; Mazel, D. S.; Hodges, D. Y.

1986-09-01

389

Ultrasonic level sensors for liquids under high pressure  

NASA Technical Reports Server (NTRS)

An ultrasonic level sensor of novel design continuously measures the level of a liquid subjected to a high pressure (up to about 40 MPa), as is sometimes required for the effective transfer of the liquid. The sensor operates as a composite resonator fabricated from a standard high-pressure plug. A flat-bottom hole is machined into the plug along its center line. An ultrasonic transducer is bonded rigidly to the interior surface of the bottom wall, while the exterior surface is in contact with the liquid. Although the bottom wall is designed to satisfy the pressure code, it is still sufficiently thin to permit ready excitation of the axisymmetric plate modes of vibration. The liquid level is measured by a conventional pulse-echo technique. A prototype sensor was tested successfully in a 2300-l water vessel at pressures up to about 37 MPa. A spectral analysis of the transmitted pulse reveals that the flexural, extensional, thickness-shear, and radial plate modes are excited into vibration, but none of these appears to be significantly affected by the pressurization of the liquid.

Zuckerwar, A. J.; Mazel, D. S.; Hodges, D. Y.

1986-01-01

390

Excited State Processes in Photosynthesis Molecules  

Microsoft Academic Search

A study of electronic processes in the chlorophyll and carothenoid molecules of the photo-reaction center II is presented with the focus on the electronic excitations and charge transfer in the photosynthetic process. Several novel ideas are mentioned especially concerning the electron replenishment and nuclear vibrational excitations. The study is build mainly on numerical quantum calculations of electronic structures of molecules

Henrik Bohr; Per Greisen; Barry Malic

2008-01-01

391

Excited State Processes in Photosynthesis Molecules  

Microsoft Academic Search

A study of electronic processes in the chlorophyll and carothenoid molecules of the photoreaction center II is presented with the focus on the electronic excitations and charge transfer in the photosynthetic process. Several novel ideas are mentioned especially concerning the electron replenishment and nuclear vibrational excitations. The study is build mainly on numerical quantum calculations of electronic structures of molecules

Henrik Bohr; Per Greisen; Barry Malic

2009-01-01

392

Are axoplasmic microtubules necessary for membrane excitation?  

Microsoft Academic Search

Summary The excitability of the squid giant axon was studied as a function of transmembrane hydrostatic pressure differences, the latter being altered by the technique of intracellular perfusion. When a KF solution was used as the internal medium, a pressure difference of about 15 cm water had very little effect on either the membrane potential or excitability. However, within a

Susumu Terakawa; Takashi Nakayama

1985-01-01

393

Surface and bulk excitations in condensed matter  

Microsoft Academic Search

In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept

Ritchie

1988-01-01

394

Excitation energy migration dynamics in upconversion nanomaterials.  

PubMed

Recent efforts and progress in unraveling the fundamental mechanism of excitation energy migration dynamics in upconversion nanomaterials are covered in this review, including short- and long-term interactions and other interactions in homogeneous and heterogeneous nanostructures. Comprehension of the role of spatial confinement in excitation energy migration processes is updated. Problems and challenges are also addressed. PMID:25223635

Tu, Langping; Liu, Xiaomin; Wu, Fei; Zhang, Hong

2015-03-10

395

Study of excited nucleons and their structure  

SciTech Connect

Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.

Burkert, Volker D. [JLAB, Newport News, VA (United States)

2014-01-01

396

What Gets a Cell Excited? Kinky Curves  

ERIC Educational Resources Information Center

Hodgkin and Huxley's (5) revealing the origins of cellular excitability is one of the great triumphs of physiology. In an extraordinarily deft series of papers, they were able to measure the essential electrical characteristics of neurons and synthesize them into a quantitative model that accounts for the excitability of neurons and other…

Kay, Alan R.

2014-01-01

397

Multi-photon excitation microscopy.  

PubMed

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

398

Multi-photon excitation microscopy  

PubMed Central

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

399

Zero-order suppression for two-photon holographic excitation.  

PubMed

Wavefront shaping with liquid-crystal spatial light modulators (LC-SLMs) is frequently hindered by a remaining fraction of undiffracted light, the so-called "zero-order." This contribution is all the more detrimental in configurations for which the LC-SLM is Fourier conjugated to a sample by a lens, because in these cases this undiffracted light produces a diffraction-limited spot at the image focal plane. In this Letter we propose to minimize two-photon (2P) excitation of the sample, resulting from this unmodulated light, by introducing optical aberrations to the excitation beam. Aberrations are subsequently compensated by the LC-SLM, but only for the modulated part of the beam, and not for the zero-order component. In order to experimentally demonstrate the method, we use astigmatism as the optical aberration, by simply adding one or two cylindrical lenses in the optical path of the beam. A 10? decrease in zero-order-induced 2P fluorescence intensity is demonstrated. Combining this approach with temporal focusing is shown to decrease zero-order fluorescence by a factor of 4·10?. PMID:25361128

Hernandez, Oscar; Guillon, Marc; Papagiakoumou, Eirini; Emiliani, Valentina

2014-10-15

400

Gluonic Excitations and Experimental Hall-D at Jefferson Lab  

E-print Network

A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple $q\\bar{q}$ pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

Justin R. Stevens

2014-07-08

401

Gluonic Excitations and Experimental Hall-D at Jefferson Lab  

SciTech Connect

A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple qq^- pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

Stevens, Justin [MIT

2014-07-01

402

Scalability of mass transfer in liquid-liquid flow  

E-print Network

We address liquid–liquid mass transfer between immiscible liquids using the system 1-butanol and water, with succinic acid as the mass transfer component. Using this system we evaluate the influence of two-phase flow ...

Woitalka, A.

403

Chiral separation by enantioselective liquid-liquid extraction.  

PubMed

The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants. PMID:21107491

Schuur, Boelo; Verkuijl, Bastiaan J V; Minnaard, Adriaan J; de Vries, Johannes G; Heeres, Hero J; Feringa, Ben L

2011-01-01

404

Method for beam steering compensation in an ultra-high power liquid laser  

DOEpatents

Thermally induced distortion of the optical wavefront caused by heating of the laser media by waste heat from the excitation process and absorption of laser radiation creates optical phase errors. A system generates an error signal derived from the optical phase errors. The error signal is fed back to the power supplies driving semiconductor diodes that excite the lasing liquid thereby introducing an electrically controllable wedge into the optical cavity to correct the optical phase errors.

Ault, Earl R. (Livermore, CA)

2002-01-01

405

Non-Fermi liquids and the Wiedemann-Franz law  

NASA Astrophysics Data System (ADS)

A general discussion of the ratio of thermal and electrical conductivities in non-Fermi liquid metals is given. In metals with sharp Drude peaks, the relevant physics is correctly organized around the slow relaxation of almost-conserved momenta. While in Fermi liquids both currents and momenta relax slowly, due to the weakness of interactions among low-energy excitations, in strongly interacting non-Fermi liquids typically only momenta relax slowly. It follows that the conductivities of such non-Fermi liquids are obtained within a fundamentally different kinematics to Fermi liquids. Among these strongly interacting non-Fermi liquids we distinguish cases with only one almost-conserved momentum, which we term quasi-hydrodynamic metals, and with many patchwise almost-conserved momenta. For all these cases, we obtain universal expressions for the ratio of conductivities that violate the Wiedemann-Franz law. We further discuss the case in which long-lived “cold” quasiparticles, in general with unconventional scattering rates, coexist with strongly interacting hot spots, lines, or bands. For these cases, we characterize circumstances under which non-Fermi liquid transport, in particular a linear in temperature resistivity, is and is not compatible with the Wiedemann-Franz law. We suggest the likely outcome of future transport experiments on CeCoIn5, YbRh2Si2, and Sr3Ru2O7 at their critical magnetic fields.

Mahajan, Raghu; Barkeshli, Maissam; Hartnoll, Sean A.

2013-09-01

406

Laser multiphoton ionization of aromatic molecules in nonpolar liquids  

NASA Astrophysics Data System (ADS)

The laser multiphoton ionization (MPI) of fluoranthene in tetramethylsilane (TMS) and of azulene in n-tridecane, n-pentane, 2,2,4,4-tetramethylpentane, TMS and tetramethyltin is reported. Three distinct types of MPI mechanisms have been identified: two-photon ionization, stepwise three-photon ionization and mixed two- and three-photon ionization. The stepwise three-photon process consists of two-photon excitation, relaxation to a lower lying excited state with a lifetime comparable to the laser pulse duration (for azulene this state is the S 2 while for fluoranthene both the S 1 and S 2 states) and subsequent ionization with the absorption of a third photon. The ionization threshold of azulene in each liquid has been determined and found to vary linearly with the V0 of the liquid.

Faidas, H.; Christophorou, L. G.

407

Time-resolved laser-excited Shpol'skii spectrometry with a fiber-optic probe and ICCD camera  

SciTech Connect

Improved methodology for chemical analysis via laser-excited Shpol'skii spectrometry is reported. The complications of traditional methodology for measurements at liquid nitrogen temperature are avoided by freezing the distal end of a bifurcated fiber-optic probe directly into the sample matrix. Emission wavelength-time matrices were rapidly collected by automatically incrementing the gate delay of an intensified charge-coupled device (ICCD) camera relative to the laser excitation pulse. The excitation source is a compact frequency-doubled tunable dye laser whose bandwidth (<0.03 nm) is well matched for Shpol'skii spectroscopy. Data reproducibility for quantitative analysis purposes and analytical figures of merit are demonstrated for several polycyclic aromatic hydrocarbons at 77 K. Although not attempted in this study, time-resolved excitation-emission matrices could easily be collected with this instrumental system. (c) 2000 Society for Applied Spectroscopy.

Bystol, Adam J. [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States)] [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States); Campiglia, Andres D. [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States)] [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States); Gillispie, Gregory D. [Dakota Technologies, Inc., 2201A 12th St. N., Fargo, North Dakota 58102-1803 (United States)] [Dakota Technologies, Inc., 2201A 12th St. N., Fargo, North Dakota 58102-1803 (United States)

2000-06-01

408

Guidance Document Cryogenic Liquids  

E-print Network

have boiling points below -73°C (-100°F). The most common cryogenic liquids currently on campus conditions of temperature and pressure. But all have two very important properties in common. First, the liquids and their vapors are extremely cold. The risk of destructive freezing of tissues is always present

409

Advanced proteomic liquid chromatography  

SciTech Connect

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-10-26

410

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

2011-11-01

411

Precision liquid level sensor  

DOEpatents

A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

Field, Michael E. (Albuquerque, NM); Sullivan, William H. (Albuquerque, NM)

1985-01-01

412

Precision liquid level sensor  

DOEpatents

A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.

Field, M.E.; Sullivan, W.H.

1985-01-29

413

Natural-gas liquids  

Microsoft Academic Search

Casinghead gasoline or natural gasoline, now more suitably known as natural-gas liquids (NGL), was a nuisance when first found, but was developed into a major and profitable commodity. This part of the petroleum industry began at about the turn of the century, and more than 60 yr later the petroleum industry recovers approx. one million bbl of natural-gas liquids a

W. B. Blackstock; G. W. McCullough; R. C. McCutchan

1968-01-01

414

Ionic liquids in catalysis  

Microsoft Academic Search

The current state of the art of the application of ionic liquids in catalysis is reviewed. The review selects examples of the different ways in which ionic liquids have been applied in catalysis, i.e. as the catalyst itself, as a co-catalyst or catalyst activator, as the source of a new ligand for a catalytic metal centre, or just as the

Tom Welton

2004-01-01

415

Liquid heat capacity lasers  

DOEpatents

The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

Comaskey, Brian J. (Walnut Creek, CA); Scheibner, Karl F. (Tracy, CA); Ault, Earl R. (Livermore, CA)

2007-05-01

416

LIGHT NONAQUEOUS PHASE LIQUIDS  

EPA Science Inventory

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

417

Perfluorocarbon liquids in ophthalmology  

Microsoft Academic Search

Perfluorocarbon liquids have been used to facilitate surgery in a wide variety of conditions, including proliferative vitreoretinopathy, giant retinal tears, drainge of suprachoroidal hemorrhages, diabetic traction, retinal detachments with a rhegmatogenous component, dislocated crystalline or intraocular lenses, and retinal detachment associated with choroidal coloboma. The clarity of perfluorocarbon liquids, with a refractive index close to that of water, allows the

Steven G. Kramer; David Hwang; Gholam A. Peyman; Joel A. Schulman; Brian Sullivan

1995-01-01

418

INEEL Liquid Effluent Inventory  

SciTech Connect

The INEEL contractors and their associated facilities are required to identify all liquid effluent discharges that may impact the environment at the INEEL. This liquid effluent information is then placed in the Liquid Effluent Inventory (LEI) database, which is maintained by the INEEL prime contractor. The purpose of the LEI is to identify and maintain a current listing of all liquid effluent discharge points and to identify which discharges are subject to federal, state, or local permitting or reporting requirements and DOE order requirements. Initial characterization, which represents most of the INEEL liquid effluents, has been performed, and additional characterization may be required in the future to meet regulations. LEI information is made available to persons responsible for or concerned with INEEL compliance with liquid effluent permitting or reporting requirements, such as the National Pollutant Discharge Elimination System, Wastewater Land Application, Storm Water Pollution Prevention, Spill Prevention Control and Countermeasures, and Industrial Wastewater Pretreatment. The State of Idaho Environmental Oversight and Monitoring Program also needs the information for tracking liquid effluent discharges at the INEEL. The information provides a baseline from which future liquid discharges can be identified, characterized, and regulated, if appropriate. The review covered new and removed buildings/structures, buildings/structures which most likely had new, relocated, or removed LEI discharge points, and at least 10% of the remaining discharge points.

Major, C.A.

1997-06-01

419

Liquid Crystal Thermometers  

NSDL National Science Digital Library

In this activity, learners explore liquid crystal thermometers to observe how heat flows by conduction, convection, radiation, and evaporation. This resource includes five mini-explorations in which learners use basic materials and observe color changes on a liquid crystal thermometer card.

Paul Doherty

1999-01-01

420

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

2008-09-09

421

Liquidity in global markets  

Microsoft Academic Search

The latest episode of turbulence has been marked by an extended period of illiquidity in a large number of markets –ranging from traditionally highly liquid interbank money markets to the less-liquid structured credit markets. The event began with what was widely perceived as a credit deterioration in the US subprime mortgage market. However, this quickly raised uncertainty about the valuation

J. Caruana; L. Kodres

2008-01-01

422

Liquid-liquid phase transition in a two-dimensional system with anomalous liquid properties.  

PubMed

The phase diagram of the two-dimensional particles interacting through a smooth version of Stell-Hemmer interaction was studied using Monte Carlo computer simulations. By evaluating the pressure-volume isotherms, we observed liquid-liquid, liquid-gas phase transitions and three stable crystal phases. The model shows the liquid-liquid critical point in stable liquid phase and is confirmed by observing properties of other thermodynamic functions such as heat capacity and isothermal compressibility, for example. The liquid-gas and the liquid-liquid critical points were estimated within the thermodynamic limit. PMID:24483440

Urbic, Tomaz

2013-12-01

423

Liquid-liquid phase transition in a two-dimensional system with anomalous liquid properties  

NASA Astrophysics Data System (ADS)

The phase diagram of the two-dimensional particles interacting through a smooth version of Stell-Hemmer interaction was studied using Monte Carlo computer simulations. By evaluating the pressure-volume isotherms, we observed liquid-liquid, liquid-gas phase transitions and three stable crystal phases. The model shows the liquid-liquid critical point in stable liquid phase and is confirmed by observing properties of other thermodynamic functions such as heat capacity and isothermal compressibility, for example. The liquid-gas and the liquid-liquid critical points were estimated within the thermodynamic limit.

Urbic, Tomaz

2013-12-01

424

Thermal excitations of warped membranes  

NASA Astrophysics Data System (ADS)

We explore thermal fluctuations of thin planar membranes with a frozen spatially varying background metric and a shear modulus. We focus on a special class of D-dimensional "warped membranes" embedded in a d-dimensional space with d ?D+1 and a preferred height profile characterized by quenched random Gaussian variables {h?(q)}, ? =D+1,...,d, in Fourier space with zero mean and a power-law variance h?(q1)h?(q2)¯˜?? ,??q1,-q2q1-dh. The case D =2, d =3, with dh=4 could be realized by flash-polymerizing lyotropic smectic liquid crystals. For D 4-?f(F) (dh<4-?f(F)), where ?f(F) is the scaling exponent for tethered surfaces with a flat background metric, and the scaling exponents are related through ?u+?f=dh-D (?u+2?f=4-D).

Košmrlj, Andrej; Nelson, David R.

2014-02-01

425

The Excitation of Sodium by Ionized Mercury Vapor  

Microsoft Academic Search

Excitation of sodium by excited and by ionized mercury vapor.-The excitation of the sodium spectrum by ionized mercury distilling from an arc was studied in a tube in which conditions were under control. An auxiliary electrode in the stream of mercury vapor was used to increase the number of excited atoms at the point of observation until the excitation due

Harold W. Webb; S. C. Wang

1929-01-01

426

Collision Frequency of Molecules Excited by Monochromatic Light  

Microsoft Academic Search

The variation in intensity of the exciting line across the absorption line in fluorescence spectra excited by monochromatic light is shown to result in a non-Maxwellian velocity distribution of the excited molecules. Expressions for the collision frequency and velocity distribution of the excited molecules are derived, assuming that the fluorescence exciting line is Gaussian and that the absorption line is

Ralph H. Kummler; M. McCarty Jr.

1965-01-01

427

Liquid metal enabled pump  

PubMed Central

Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O’Mullane, Anthony P.; Abbott, Derek; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2014-01-01

428

Mixing liquids in microseconds  

NASA Astrophysics Data System (ADS)

An instrument is described in which two solutions can be homogeneously mixed within several microseconds. The liquids flow separately through two coaxial capillaries with conical tips and then simultaneously around a sphere (50-100 ? in diameter) which has been positioned close to the end of the outer tip. The liquids flow with velocities of ˜100 m/s through the small passages (˜5 ? wide) separating the sphere and the wall of the outer capillary and mix in the turbulent liquid flow behind the sphere. The mixed liquids are then ejected as a narrow liquid jet for observation. Design characteristics and construction techniques are presented along with a discussion of the properties of the turbulent flow field and estimates of the expected practically realizable mixing times. The experimentally determined speed of mixing indicates that we have nearly achieved the proposed lower limits of the mixing time.

Regenfuss, Peter; Clegg, Robert M.; Fulwyler, Mack. J.; Barrantes, Francisco J.; Jovin, Thomas M.

1985-02-01

429

Liquid metal enabled pump.  

PubMed

Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O'Mullane, Anthony P; Abbott, Derek; Mitchell, Arnan; Kalantar-Zadeh, Kourosh

2014-03-01

430

Polymers and Liquid Crystals  

NSDL National Science Digital Library

This newly enhanced site is the result of a cooperative effort between the Department of Physics and the Department of Macromolecular Science and Engineering at Case Western Reserve University in conjunction with the Center for Advanced Liquid Crystalline Optical Materials (ALCOM) at Kent State University. The project aims to demonstrate the potential of the hypertext multimedia medium for instructional use, and is still under development (occasionally users will come across an "under construction" notice). Topics covered include polymers, liquid crystals, polymer liquid crystals, polymer dispersed liquid crystals, polymer stabilized cholesterics, and liquid crystal displays. The previous version, which debuted in January 1996, has been enhanced with more video and audio, frames, and a glossary. Throughout the text, users are invited to enter the Virtual Laboratory, in which browser applets allow control of experiments demonstrating the principles under discussion. A CD-ROM version of the textbook is planned.

431

Linear magnetohydrodynamic Taylor-Couette instability for liquid sodium  

Microsoft Academic Search

The linear stability of MHD Taylor-Couette flow of infinite vertical extension is considered for liquid sodium with its small magnetic Prandtl number Pm of order 10-5. The calculations are performed for a container with Rout=2Rin, with an axial uniform magnetic field and with boundary conditions for both vacuum and perfect conductions. For resting outer cylinder subcritical excitation in comparison to

Günther Rüdiger; Manfred Schultz; Dima Shalybkov

2003-01-01

432

Resonance enhanced Raman scatter in liquid benzene at vapor-phase absorption peaks.  

PubMed

The resonance enhanced Raman spectra in the 1B2u mode of the forbidden benzene electronic transition band, ~230-270 nm, has been investigated. Resonance enhanced Raman scattering in both liquid benzene and liquid toluene exhibit the greatest enhancement when the wavelength of excitation is tuned to the vapor-phase absorption peaks; even though the sample volume is in a liquid state. Raman signals for the symmetric breathing mode of the carbon ring are found to be resonantly enhanced by several orders of magnitude (>500X) with deep UV excitation compared to non-resonant visible excitation. Since the benzene absorbs near this resonant wavelength, its effect on the sampled volume cannot be neglected in determining the resonance gain, as we discuss in detail. Large resonant gains correspond with excitation at the 247, 253, and 259 nm absorption peaks in the benzene vapor spectrum. The narrow region of resonance gain is investigated in detail around the absorption peak located at 259 nm using 0.25 nm steps in the excitation wavelength. We observe the resonance gain tracking the vapor phase absorption peaks and valleys within this narrow range. Results are interpreted in terms of the coherence forced by the use of a forbidden transition for resonance excitation. PMID:24216839

Willitsford, Adam; Chadwick, C Todd; Hallen, Hans; Kurtz, Stewart; Philbrick, C Russell

2013-11-01

433

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ˜ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for ? -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( ? L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ? value for 21Na is 137±9 e^2fm^4, while the resulting B( ? L) ? values for 20Na are 55±6 e^2fm^4 for the 3+ rightarrow 2+ , 35.7±5.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.154±0.030 ?_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( ? L) values for the proton dripline nucleus 20Na .-1

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-12-01

434

Renewable liquid reflecting zone plate  

DOEpatents

A renewable liquid reflecting zone plate. Electrodes are operatively connected to a dielectric liquid in a circular or other arrangement to produce a reflecting zone plate. A system for renewing the liquid uses a penetrable substrate.

Toor, Arthur; Ryutov, Dmitri D.

2003-12-09

435

Solid-Liquid Interfacial Premelting  

E-print Network

We report the observation of a premelting transition at chemically sharp solid-liquid interfaces using molecular-dynamics simulations. The transition is observed in the solid-Al—liquid-Pb system and involves the formation of a liquid interfacial...

Yang, Yang; Asta, Mark; Laird, Brian Bostian

2013-02-28

436

Landau-Placzek ratio for heat density dynamics and its application to heat capacity of liquids.  

PubMed

Exact relation for contributions to heat capacity of liquids is obtained from hydrodynamic theory. It is shown from analysis of the long-wavelength limit of heat density autocorrelation functions that the heat capacity of simple liquids is represented as a sum of two contributions due to "phonon-like" collective excitations and heat relaxation. The ratio of both contributions being the analogy of Landau-Placzek ratio for heat processes depends on the specific heats ratio. The theory of heat density autocorrelation functions in liquids is verified by computer simulations. Molecular dynamics simulations for six liquids having the ratio of specific heats ? in the range 1.1-2.3, were used for evaluation of the heat density autocorrelation functions and predicted Landau-Placzek ratio for heat processes. The dependence of contributions from collective excitations and heat relaxation process to specific heat on ? is shown to be in excellent agreement with the theory. PMID:23343280

Bryk, Taras; Ruocco, Giancarlo; Scopigno, Tullio

2013-01-21

437

Stability of Liquid Rivulets on Liquid Substrate  

NASA Astrophysics Data System (ADS)

The human tear-film lipid layer is a thin (100nm) oily film on water. Such films are unstable and dewet into lenses surrounded by a monolayer (Harkins, 1941). Dewetting has four stages: initial rupture, hole growth, hole coalescence, and retraction into lenses. The human lipid layer is shown to behave similarly. Brochard-Wyart has addressed the first two stages (1993); here we focus on the third. As adjacent holes grow into each other, the oil between them takes the shape of a long, thin rivulet with a lens cross-section. Eventually this rivulet undergoes an instability and the holes coalesce. We perform a linear stability analysis on a thin symmetric lens rivulet on a horizontal liquid substrate at low Bond number (Davis, 1980; Schiaffino, 1997), accounting for the first time for the liquid-substrate hydrodynamics. Analytical expressions are derived for the wavelength and breakup times associated with the maximum growth rate of the instability for multiple substrate flow conditions. We show that for negligible thin-film forces, a liquid rivulet on an immiscible liquid substrate is unstable at a critical wavelength disturbance. The instability growth rate varies by orders of magnitude depending on the lens contact angle.

Cerretani, Colin; Takatori, Sho; Radke, Clayton

2011-11-01

438

Application of Ionic Liquids in Liquid Chromatography  

Microsoft Academic Search

Interest in ionic liquids (ILs) for their potential application in analytical chemistry continues to grow. Their usefulness can be due to favourable physicochemical properties, like the lack of vapour pressure, good thermal and chemical stability as well as very good dissolution properties regarding both organic and inorganic compounds. A specific feature of ILs is that these compounds provide strong proton

Micha? Piotr Marsza??; Roman Kaliszan

2007-01-01

439

Localized and propagating excitations in gapped phases of spin systems with bond disorder  

NASA Astrophysics Data System (ADS)

Using the conventional T-matrix approach, we discuss gapped phases in one-, two-, and three-dimensional (3D) spin systems (both with and without a long-range magnetic order) with bond disorder and with weakly interacting bosonic elementary excitations. This work is motivated by recent experimental and theoretical activity in spin-liquid-like systems with disorder and in the disordered interacting boson problem. In particular, we apply our theory to both paramagnetic low-field and fully polarized high-field phases in dimerized spin-1/2 systems and in integer-spin magnets with large single-ion easy-plane anisotropy D with disorder in exchange coupling constants (and/or D). The elementary excitation spectrum and the density of states are calculated in the first order in defects concentration c ?1. In 2D and 3D systems, the scattering on defects leads to a finite damping of all propagating excitations in the band except for states lying near its edges. We demonstrate that the analytical approach is inapplicable for states near the band edges and our numerical calculations reveal their localized nature. We find that the damping of propagating excitations can be much more pronounced in considered systems than in magnetically ordered gapless magnets with impurities. In 1D systems, the disorder leads to localization of all states in the band, while those lying far from the band edges (short-wavelength excitations) can look like conventional wave packets.

Utesov, O. I.; Sizanov, A. V.; Syromyatnikov, A. V.

2014-10-01

440

Quantum criticality in two dimensions and marginal Fermi liquid  

NASA Astrophysics Data System (ADS)

Kinetic properties of a two-dimensional model of fermions interacting with antiferromagnetic spin excitations near the quantum critical point are considered. The temperature or doping are assumed to be sufficiently high, such that the pseudogap does not appear. In contrast to standard spin-fermion models, it is assumed that there are intrinsic inhomogeneities in the system suppressing space correlations of the antiferromagnetic excitations. It is argued that the inhomogeneities in the spin excitations in the "strange metal" phase can be a consequence of the existence of "? -shifted" domain walls in the doped antiferromagnetic phase. Averaging over the inhomogeneities and calculating physical quantities such as resistivity and some others one can explain unusual properties of cuprates unified under the name "marginal Fermi liquid." The dependence of the slope of the linear temperature dependence of the resistivity on doping is compared with experimental data.

Efetov, K. B.

2015-01-01

441

Relativistic dynamical spin excitations of magnetic adatoms  

NASA Astrophysics Data System (ADS)

We present a first-principles theory of dynamical spin excitations in the presence of spin-orbit coupling. The broken global spin rotational invariance leads to a new sum rule. We explore the competition between the magnetic anisotropy energy and the external magnetic field, as well as the role of electron-hole excitations, through calculations for 3 d -metal adatoms on the Cu(111) surface. The spin excitation resonance energy and lifetime display nontrivial behavior, establishing the strong impact of relativistic effects. We legitimate the use of the Landau-Lifshitz-Gilbert equation down to the atomic limit, but with parameters that differ from a stationary theory.

dos Santos Dias, M.; Schweflinghaus, B.; Blügel, S.; Lounis, S.

2015-02-01

442

Spin excitations in di-nuclear systems  

SciTech Connect

The spin excitations of products from two-body reactions have two sources: transfer of orbital motion into intrinsic spins via tangential friction and thermal excitations of di-nuclear spin modes. The relative importance of these two mechanisms is discussed for deep inelastic scattering, quasi-fission and spontaneous fission processes. The results of simple model calculations are compared to measured {gamma}-multiplicities in {sup 238}U induced quasi-fission reactions and it is concluded that the spin-excitation are only partially equilibrated during the interaction. 11 refs., 5 figs.

Back, B.B.

1990-01-01

443

Pulse Vector-Excitation Speech Encoder  

NASA Technical Reports Server (NTRS)

Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.

Davidson, Grant; Gersho, Allen

1989-01-01

444

Surface and bulk excitations in condensed matter  

SciTech Connect

In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept of elementary excitations in solids, pioneered by Bohm and Pines almost 4 decades ago, has proved to be extremely useful in understanding the properties of systems of many particles, especially in respect to the response to the action of external probes. 32 refs., 12 figs.

Ritchie, R.H.

1988-01-01

445

First Evidence of Double Spin Isospin Excitation  

NASA Astrophysics Data System (ADS)

To study double spin-isospin responses in view of the ??0? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher ?L excitations.

Takahisa, Keiji

2007-06-01

446

First Evidence of Double Spin Isospin Excitation  

SciTech Connect

To study double spin-isospin responses in view of the {beta}{beta}0{nu} decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher {delta}L excitations.

Takahisa, Keiji [Research Center for Nuclear Physics, Osaka University, Mihogaoka 10-1, Ibaraki, Osaka, 567-0047 (Japan)

2007-06-13

447

Helicon wave excitation with helical antennas  

NASA Astrophysics Data System (ADS)

Components of the wave magnetic field in a helicon discharge have been measured with a single-turn, coaxial magnetic probe. Left- and right-handed helical antennas, as well as plane-polarized antennas, were used; and the results were compared with the field patterns computed for a nonuniform plasma. The results show that the right-hand circularly polarized mode is preferentially excited with all antennas, even those designed to excite the left-hand mode. For right-hand excitation, the radial amplitude profiles are in excellent agreement with computations.

Light, Max; Chen, Francis F.

1995-04-01

448

Electron-impact excitation of holmium atoms  

SciTech Connect

The electron-impact excitation of holmium atoms was studied by the method of extended crossing beams. The cross sections and the optical excitation functions were obtained for odd levels of Ho I, including the 22014 cm{sup -1} laser level. Over 99% of the atoms were shown to reside in the ground level prior to collisions with electrons. Also measured were the excitation cross sections for six even levels, which presumably participate in the formation of inversion population in a gas-discharge holmium vapour laser. (laser applications and other topics in quantum electronics)

Smirnov, Yu M [Moscow Power Engineering Institute, Moscow (Russian Federation)

2000-06-30

449

Resonant excitation of plasma wakefield  

NASA Astrophysics Data System (ADS)

Particle accelerators are the main tool for discovering new elementary particles. Plasma based accelerator (PWFA) has been proven a very attractive new acceleration technique due to the large acceleration gradient it has reached (>50GV/m), which is two to three orders higher than the conventional radio frequency accelerators. PWFA is essentially an energy transformer transferring the energy from the drive bunches to witness bunches. For a future more compact and more affordable linear electron/positron collider, such an accelerator will require drive bunches with small longitudinal size (on the order of 100 um) and multi-kilojules of energy to access the new physics at the energy frontier. However, present relativistic electron bunch drivers carry less than 100Joules, thereby limiting the energy gain by the accelerated bunch to less than 100Joules. Proton bunches produced at CERN have been proven as potential drivers for PWFA due to the many tens of kilojules energy they carry (1e11 particles, 3.5-7TeV per particle). However, the CERN proton bunches are too long (approximately 12cm) to drive the wakefield efficiently. It has been proposed that a long particle bunch (protons, electrons, positrons, ... ) traveling in dense plasmas is subject to self-modulation instability (SMI), which transversely modulates a long bunch into multiple short bunches (on the scale of plasma wavelength) and therefore results in high acceleration amplitudes through resonant excitation. In this thesis, we demonstrate the first experimental evidence for the seeding of SMI with an electron bunch. We also use numerical simulations to study the SMI development with a higher-charge electron bunch and propose a possible experiment to demonstrate the transverse modulation directly in experiments. Moreover, we investigate with simulations the effect of transverse plasma radius on the SMI development, which is an important factor to consider when designing plasmas for future SMI and SMI-based experiments. Besides efficient drivers such as high-energy proton bunches, the PWFA also requires high transformer ratio (an indication of energy transfer efficiency) so that the witness bunch can gain energy efficiently from the drive bunch. In this thesis, we explore the possibility of reaching high transformer ratio in the weakly nonlinear PWFA regime so that the witness bunch particles can gain many times the energy of the drive bunch particles in a single acceleration stage.

Fang, Yun

450

Vacuum ultraviolet light production by nuclear irradiation of liquid and gaseous xenon  

NASA Technical Reports Server (NTRS)

Recent Los Alamos investigations suggest that a liquefied noble element may be the long-sought medium for a nuclear-excited laser or flashlamp. Research is needed to confirm this finding and to provide a basis for design and application studies. Quantitative and qualitative information are needed on the nature and behavior of the excited species, the effects of impurities and additives in the liquid phase under nuclear excitation, and the existence and magnitudes of nonlinear effects. Questions that need to be addressed and the most appropriate types of facilities for this task are identified.

Baldwin, G. C.

1981-01-01

451

Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination  

PubMed Central

Summary 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials. PMID:21915207

Breen, Jessica R; Yufit, Dmitrii S; Howard, Judith A K; Fray, Jonathan; Patel, Bhairavi

2011-01-01

452

Nanowire liquid pumps.  

PubMed

The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ?10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability. PMID:23542904

Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X; Li, Ju

2013-04-01

453

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

Larson, L.L.

1984-09-17

454

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

Larson, Loren L. (Idaho Falls, ID)

1987-01-01

455

A theoretical study of the excited states of Ag3  

NASA Technical Reports Server (NTRS)

Calculations of the excited states of the Ag3 molecule are reported. The excitation energies, geometries, derived harmonic frequencies, and transition moments are given and discussed. The results of other calculations of the excited states are reviewed and assessed.

Walch, Stephen P.

1987-01-01

456

Liquid metal drop ejection  

NASA Technical Reports Server (NTRS)

The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

Khuri-Yakub, B. T.

1993-01-01

457

Students Excited by Stellar Discovery  

NASA Astrophysics Data System (ADS)

In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

2011-02-01

458

Acoustics of Excited Jets: A Historical Perspective  

NASA Technical Reports Server (NTRS)

The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

Brown, Cliffard A.

2005-01-01

459

The DSS-14 C-band exciter  

NASA Technical Reports Server (NTRS)

The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

Rowan, D. R.

1989-01-01

460

Magnetic Excitation for Spin Vibration Testing  

NASA Technical Reports Server (NTRS)

The Dynamic Spin Rig Laboratory (DSRL) at the NASA Lewis Research Center is a facility used for vibration testing of structures under spinning conditions. The current actuators used for excitation are electromagnetic shakers which are configured to apply torque to the rig's vertical rotor. The rotor is supported radially and axially by conventional bearings. Current operation is limited in rotational speed, excitation capability, and test duration. In an effort to enhance its capabilities, the rig has been initially equipped with a radial magnetic bearing which provides complementary excitation and shaft support. The new magnetic feature has been used in actual blade vibration tests and its performance has been favorable. Due to the success of this initial modification further enhancements are planned which include making the system fully magnetically supported. This paper reports on this comprehensive effort to upgrade the DSRL with an emphasis on the new magnetic excitation capability.

Johnson, Dexter; Mehmed, Oral; Brown, Gerald V.

1997-01-01

461

Detecting cracked rotors using auxiliary harmonic excitation  

NASA Astrophysics Data System (ADS)

Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts.

Sawicki, Jerzy T.; Friswell, Michael I.; Kulesza, Zbigniew; Wroblewski, Adam; Lekki, John D.

2011-03-01

462

Stimulated excitation electron microscopy and spectroscopy.  

PubMed

Recent advances in instrumentation for electron optics and spectroscopy have prompted exploration of ultra-low excitations such as phonons, bond vibrations and Johnson noise. These can be excited not just with fast electrons but also thermally or by other external sources of radiation. The near-field theory of electron energy loss and gain provides a convenient platform for analysing these processes. Possibilities for selected phonon mapping and imaging are discussed. Effects should certainly be observable in atomic resolution structure imaging but diffraction contrast imaging could perhaps be more informative. Additional exciting prospects to be explored include the transition from phonon excitation to single atom recoil and the boosting of energy loss and gain signals with tuned laser illumination. PMID:25312246

Howie, A

2015-04-01

463

On Oscillators in Phyllosilicate Excitable Automata  

NASA Astrophysics Data System (ADS)

Phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate excitable automaton is a regular network of finite state machines, which mimics structure of a silicate sheet. A node of the silicate sheet is an automaton, which takes resting, excited and refractory states, and updates its state in discrete time depending on a sum of excited states of its three (silicon automata) or six (oxygen automata) closest neighbors. Oscillator is a localized compact configuration of nonquiescent states which undergoes finite growth and modification but returns to its original state in a finite number of steps. We show that phyllosilicate excitable automata exhibit waves and oscillating localizations (oscillators) dynamics. Basic types of oscillators are classified and characterized.

Adamatzky, Andrew

2013-06-01

464

Excitation with Effective Subcycle Laser Pulses  

NASA Astrophysics Data System (ADS)

We have used laser pulses with a temporally shaped polarization to demonstrate the multiphoton excitation of the xenon 5g state within a subcycle of a laser pulse. Our polarization gated laser pulses are composed of circularly polarized sections at the leading and trailing edges of the pulse and of an experimentally defined linearly polarized central part. Only the linear part (the gate) of the pulse can excite neutral xenon in the 5g state. The transition cannot be driven with circularly polarized light because the number of photons needed would cause a violation of selection rules for the change of the magnetic quantum number. We show that the linearly polarized central part can be reduced to a subcycle pulse. This allows us to study excitation with an effective pulse as short as 2.3 fs at 800 nm. Electron imaging spectroscopy has been used to visualize the presence of excited states as a function of the pulse duration of the gate.

Marceau, C.; Gingras, G.; Witzel, B.

2013-11-01

465

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3...may be used for excitation of an emergency generator unless it is provided with a permanent...

2011-10-01

466

Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy  

SciTech Connect

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

2010-05-01

467

Circular dielectric liquid iris.  

PubMed

We demonstrate a liquid iris diaphragm using dielectric force, enabling its aperture to vary from 4 mm at the resting state to 1.5 mm at 160 V(rms). The liquid iris is a packaged optical component comprised of transparent oil, opaque ink, and a set of driving electrodes on a glass substrate. The iris aperture shrinks with the dielectric force, which is exerted on the interface between the two nonconductive liquids. The transmittance was measured to exceed 85% with no antireflection coatings over the spectrum of visible light. The maximum electric power consumed is measured to be 5.7 mW. PMID:20634871

Tsai, C Gary; Yeh, J Andrew

2010-07-15

468

Liquid metal electric pump  

DOEpatents

An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

1992-01-14

469

Exploring Materials: Liquid Crystals  

NSDL National Science Digital Library

In this activity, learners discover that the way a material behaves on the macroscale is affected by its structure on the nanoscale. Learners investigate the properties of a heat sensitive liquid crystal and make their own liquid crystal sensor to take home. This is a fun and engaging activity, especially since liquid crystals are used in many consumer products, including cell phone displays, laptop computer screens, strip thermometers, and even "mood" rings! SAFETY: learners must be supervised when doing this activity. They must wear safety glasses to protect their eyes. Before doing this activity, read through the Material Safety Data Sheets.

Nanoscale Informal Science Education Network

2010-01-01

470

Liquid-level detector  

DOEpatents

Aliquid level sensor is described which has a pair of upright conductors spaced by an insulator defining a first high resistance path between the conductors. An electrically conductive path is interposed between the upright conductors at a discrete location at which liquid level is to be measured. It includes a liquid accessible gap of a dimension such that the electrical resistance across the conductor when the gap is filled with the liquid is detectably less than when the gap is emptied. The conductor might also be physically altered by temperature changes to serve also as an indicator of elevated temperature.

Not Available

1981-01-29

471

Electrically Deformable Liquid Marbles  

E-print Network

Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. The semi-quantitative theory describing deformation of liquid marbles in a uniform electric field is presented. The scaling law relating the radius of the contact area of the marble to the applied electric field shows a satisfactory agreement with the experimental data.

Edward Bormashenko; Roman Pogreb; Tamir Stein; Gene Whyman; Marcelo Schiffer; Doron Aurbach

2011-02-17

472

Comparison of vapor formation of water at the solid/water interface to colloidal solutions using optically excited gold nanostructures.  

PubMed

The phase transformation properties of liquid water to vapor is characterized by optical excitation of the lithographically fabricated single gold nanowrenches and contrasted to the phase transformation properties of gold nanoparticles located and optically excited in a bulk solution system [two and three dimensions]. The 532 nm continuous wave excitation of a single gold nanowrench results in superheating of the water to the spinodal decomposition temperature of 580 ± 20 K with bubble formation below the spinodal decomposition temperature being a rare event. Between the spinodal decomposition temperature and the boiling point liquid water is trapped into a metastable state because a barrier to vapor nucleation exists that must be overcome before the thermodynamically stable state is realized. The phase transformation for an optically heated single gold nanowrench is different from the phase transformation of optically excited colloidal gold nanoparticles solution where collective heating effects dominates and leads to the boiling of the solution exactly at the boiling point. In the solution case, the optically excited ensemble of nanoparticles collectively raises the ambient temperature of water to the boiling point where liquid is converted into vapor. The striking difference in the boiling properties of the single gold nanowrench and the nanoparticle solution system can be explained in terms of the vapor-nucleation mechanism, the volume of the overheated liquid, and the collective heating effect. The interpretation of the observed regimes of heating and vaporization is consistent with our theoretical modeling. In particular, we explain with our theory why the boiling with the collective heating in a solution requires 3 orders of magnitude less intensity compared to the case of optically driven single nanowrench. PMID:24476426

Baral, Susil; Green, Andrew J; Livshits, Maksim Y; Govorov, Alexander O; Richardson, Hugh H

2014-02-25

473

Self excitation of iron core homopolar generators  

Microsoft Academic Search

In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at the University of Texas. In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A

D. E. Perkins; K. E. Nalty; W. A. Walls

1986-01-01

474

Fast pulsed excitation wiggler or undulator  

DOEpatents

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron