WorldWideScience

Sample records for dense molecular fluids

  1. Simulations of vibrational relaxation in dense molecular fluids

    International Nuclear Information System (INIS)

    Holian, B.L.

    1985-07-01

    In the understanding of high-temperatre and -pressure chemistry in explosives, first step is the study of the transfer of energy from translational degrees of freedom into internal vibrations of the molecules. We present new methods using nonequilibrium molecular dynamics (NEMD) for measuring vibrational relaxation in a diatomic fluid, where we expect a classical treatment of many-body collisions to be relevant because of the high densities (2 to 3 times compressed compared to the normal fluid) and high temperatures (2000 to 4000 K) involved behind detonation waves. NEMD techniques are discussed, including their limitations, and qualitative results presented

  2. Dense fluid self-diffusion coefficient calculations using perturbation theory and molecular dynamics

    Directory of Open Access Journals (Sweden)

    COELHO L. A. F.

    1999-01-01

    Full Text Available A procedure to correlate self-diffusion coefficients in dense fluids by using the perturbation theory (WCA coupled with the smooth-hard-sphere theory is presented and tested against molecular simulations and experimental data. This simple algebraic expression correlates well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. We have also performed canonical ensemble molecular dynamics simulations by using the Hoover-Nosé thermostat and the mean-square displacement formula to compute self-diffusion coefficients for the reference WCA intermolecular potential. The good agreement obtained from both methods, when compared with experimental data, suggests that the smooth-effective-sphere theory is a useful procedure to correlate diffusivity of pure substances.

  3. Collective dynamics in dense fluid mixtures

    International Nuclear Information System (INIS)

    Sinha, S.

    1992-01-01

    This thesis deals with the short wavelength collective dynamics of dense binary fluid mixtures. The analysis shows that at the level of linearized generalized hydrodynamics, the longitudinal modes of the system separates essentially into two parts - one involves the coupling of partial density fluctuations of the two species and the other involves coupling of longitudinal momentum and temperature fluctuations. The authors have shown that the coupling of longitudinal momentum and temperature fluctuations leads to an adequate description of sound propagation in such systems. In particular, they show that structural disorder controls the trapping of sound waves in dense mixtures. The coupling of the partial density fluctuations of the two species leads to a simple description of the partial dynamic structure factors. The results are in agreement with the molecular dynamics simulations of soft sphere mixtures. The partial density fluctuations are the slowest decaying fluctuations on molecular length scales and it turns out that nonlinear coupling of these slow modes leads to important corrections to the long time behavior of the time correlation functions determining the shear viscosity in dense mixtures

  4. Predicting diffusivities in dense fluid mixtures

    Directory of Open Access Journals (Sweden)

    C. DARIVA

    1999-09-01

    Full Text Available In this work the Enskog solution of the Boltzmann equation, as corrected by Speedy, together with the Weeks-Chandler-Andersen (WCA perturbation theory of liquids is employed in correlating and predicting self-diffusivities of dense fluids. Afterwards this theory is used to estimate mutual diffusion coefficients of solutes at infinite dilution in sub and supercritical solvents. We have also investigated the behavior of Fick diffusion coefficients in the proximity of a binary vapor-liquid critical point since this subject is of great interest for extraction purposes. The approach presented here, which makes use of a density and temperature dependent hard-sphere diameter, is shown to be excellent for predicting diffusivities in dense pure fluids and fluid mixtures. The calculations involved highly nonideal mixtures as well as systems with high molecular asymmetry. The predicted diffusivities are in good agreement with the experimental data for the pure and binary systems. The methodology proposed here makes only use of pure component information and density of mixtures. The simple algebraic relations are proposed without any binary adjustable parameters and can be readily used for estimating diffusivities in multicomponent mixtures.

  5. Determination of the friction coefficient via the force autocorrelation function. A molecular dynamics investigation for a dense Lennard-Jones fluid

    International Nuclear Information System (INIS)

    Vogelsang, R.; Hoheisel, C.

    1987-01-01

    For a large region of dense fluid states of a Lennard-Jones system, they have calculated the friction coefficient by the force autocorrelation function of a Brownian-type particle by molecular dynamics (MD). The time integral over the force autocorrelation function showed an interesting behavior and the expected plateau value when the mass of the Brownian particle was chosen to be about a factor of 100 larger than the mass of the fluid particle. Sufficient agreement was found for the friction coefficient calculated by this way and that obtained by calculations of the self-diffusion coefficient using the common relation between these coefficients. Furthermore, a modified friction coefficient was determined by integration of the force autocorrelation function up to the first maximum. This coefficient can successfully be used to derive a reasonable soft part of the friction coefficient necessary for the Rice-Allnatt approximation for the shear velocity and simple liquids

  6. Screening in dense ionic fluids

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1991-01-01

    There has been great progress in recent years in determining and understanding the structure of molten salts. I focus on molten alkali halides and discuss two main points concerning their liquid structure and its relationship with static electrical response in these dense ionic conductors. These are (i) the nature of screening and the related definitions and properties of the screening length and of the dielectric function, and (ii) developments in integral equations techniques for the evaluation of molten salt structure and static screening from given pair potentials. (author). 26 refs, 3 figs, 2 tabs

  7. Chaotic dynamics in dense fluids

    International Nuclear Information System (INIS)

    Posch, H.A.; Hoover, W.G.

    1987-09-01

    We present calculations of the full spectra of Lyapunov exponents for 8- and 32-particle systems with periodic boundary conditions and interacting with the repulsive part of a Lennard-Jones potential both in equilibrium and nonequilibrium steady states. Lyapunov characteristic exponents λ/sub n/ describe the mean exponential rates of divergence and convergence of neighbouring trajectories in phase-space. They are useful in characterizing the stochastic properties of a dynamical system. A new algorithm for their calculation is presented which incorporates ideas from control theory and constraint nonequilibrium molecular dynamics. 4 refs., 1 fig

  8. Packing frustration in dense confined fluids.

    Science.gov (United States)

    Nygård, Kim; Sarman, Sten; Kjellander, Roland

    2014-09-07

    Packing frustration for confined fluids, i.e., the incompatibility between the preferred packing of the fluid particles and the packing constraints imposed by the confining surfaces, is studied for a dense hard-sphere fluid confined between planar hard surfaces at short separations. The detailed mechanism for the frustration is investigated via an analysis of the anisotropic pair distributions of the confined fluid, as obtained from integral equation theory for inhomogeneous fluids at pair correlation level within the anisotropic Percus-Yevick approximation. By examining the mean forces that arise from interparticle collisions around the periphery of each particle in the slit, we calculate the principal components of the mean force for the density profile--each component being the sum of collisional forces on a particle's hemisphere facing either surface. The variations of these components with the slit width give rise to rather intricate changes in the layer structure between the surfaces, but, as shown in this paper, the basis of these variations can be easily understood qualitatively and often also semi-quantitatively. It is found that the ordering of the fluid is in essence governed locally by the packing constraints at each single solid-fluid interface. A simple superposition of forces due to the presence of each surface gives surprisingly good estimates of the density profiles, but there remain nontrivial confinement effects that cannot be explained by superposition, most notably the magnitude of the excess adsorption of particles in the slit relative to bulk.

  9. Common intersection points in dense fluids via equations of state

    International Nuclear Information System (INIS)

    Parsafar, G. A.; Noorian, R.

    2001-01-01

    Some new of state which are derived for dense fluids in recent years, namely the linear isotherm regularity, the dense system equation of state, Ihm-Song-Mason equation of state, and a newly derived semi-empirical equation of state have used to investigate the common intersection point of isobaric expansivity (α p ) in dense fluids. We have shown that the accuracy of these equations of state in predicting such a common intersection point is reduced from the new semi-imperial equation of state, dense system equation of state, linear isotherm regularity, to Ihm-Song-Mason equation of state. respectively. Form physical point of view, the van der Waals equation of state is used to investigate such an intersection point. It is shown that the van der Waals repulsion forces and temperature dependency of the effective molecular diameter are important for existence of this common point. Finally, we have shown that the common intersection points of the isotherms of thermal pressure coefficient, the isotherms of heat capacity at constant volume, and the iso chores of internal pressure for a fluid are related to each other. Also, the common intersection points of the reduced bulk modulus and 1/(Tα p ) for isotherms of a fluid both appear at the same density

  10. Molecular dynamics for dense matter

    International Nuclear Information System (INIS)

    Maruyama, Toshiki; Chiba, Satoshi; Watanabe, Gentaro

    2012-01-01

    We review a molecular dynamics method for nucleon many-body systems called quantum molecular dynamics (QMD), and our studies using this method. These studies address the structure and the dynamics of nuclear matter relevant to neutron star crusts, supernova cores, and heavy-ion collisions. A key advantage of QMD is that we can study dynamical processes of nucleon many-body systems without any assumptions about the nuclear structure. First, we focus on the inhomogeneous structures of low-density nuclear matter consisting not only of spherical nuclei but also of nuclear “pasta”, i.e., rod-like and slab-like nuclei. We show that pasta phases can appear in the ground and equilibrium states of nuclear matter without assuming nuclear shape. Next, we show our simulation of compression of nuclear matter which corresponds to the collapsing stage of supernovae. With the increase in density, a crystalline solid of spherical nuclei changes to a triangular lattice of rods by connecting neighboring nuclei. Finally, we discuss fragment formation in expanding nuclear matter. Our results suggest that a generally accepted scenario based on the liquid–gas phase transition is not plausible at lower temperatures. (author)

  11. Molecular dynamics for dense matter

    Science.gov (United States)

    Maruyama, Toshiki; Watanabe, Gentaro; Chiba, Satoshi

    2012-08-01

    We review a molecular dynamics method for nucleon many-body systems called quantum molecular dynamics (QMD), and our studies using this method. These studies address the structure and the dynamics of nuclear matter relevant to neutron star crusts, supernova cores, and heavy-ion collisions. A key advantage of QMD is that we can study dynamical processes of nucleon many-body systems without any assumptions about the nuclear structure. First, we focus on the inhomogeneous structures of low-density nuclear matter consisting not only of spherical nuclei but also of nuclear "pasta", i.e., rod-like and slab-like nuclei. We show that pasta phases can appear in the ground and equilibrium states of nuclear matter without assuming nuclear shape. Next, we show our simulation of compression of nuclear matter which corresponds to the collapsing stage of supernovae. With the increase in density, a crystalline solid of spherical nuclei changes to a triangular lattice of rods by connecting neighboring nuclei. Finally, we discuss fragment formation in expanding nuclear matter. Our results suggest that a generally accepted scenario based on the liquid-gas phase transition is not plausible at lower temperatures.

  12. PHOTOCHEMICAL HEATING OF DENSE MOLECULAR GAS

    Energy Technology Data Exchange (ETDEWEB)

    Glassgold, A. E. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Najita, J. R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-09-10

    Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct process, heating is also produced by the subsequent chemical reactions initiated by these products. Some of this chemical heating comes from the kinetic energy of the reaction products and the rest from collisional de-excitation of the product atoms and molecules. In considering dense gas dominated by molecular hydrogen, we find that the chemical heating is sometimes as large, if not much larger than, the direct heating. In very dense gas, the total photochemical heating approaches 10 eV per photodissociation (or photoionization), competitive with other ways of heating molecular gas.

  13. Quasi-molecular processes in dense plasmas

    International Nuclear Information System (INIS)

    Younger, S.M.

    1991-01-01

    Quasi-molecular phenomena occur in dense plasmas when the interatomic spacing is comparable to the characteristic wavelength of the electrons. If the electronic states are bound, covalent orbitals arise with different excitation energies, radiative rates, and collisional rates than for isolated ions. For continuum electrons, charge localization near transient clusters of nuclei can influence many scattering and transport processes. We identify several novel consequences of quasi-molecular phenomena in plasmas and give a possible explanation of high energy features associated with helium-like emissions lines observed in recent inertial fusion experiments. 7 refs

  14. Neutron Brillouin scattering in dense fluids

    Energy Technology Data Exchange (ETDEWEB)

    Verkerk, P [Technische Univ. Delft (Netherlands); FINGO Collaboration

    1997-04-01

    Thermal neutron scattering is a typical microscopic probe for investigating dynamics and structure in condensed matter. In contrast, light (Brillouin) scattering with its three orders of magnitude larger wavelength is a typical macroscopic probe. In a series of experiments using the improved small-angle facility of IN5 a significant step forward is made towards reducing the gap between the two. For the first time the transition from the conventional single line in the neutron spectrum scattered by a fluid to the Rayleigh-Brillouin triplet known from light-scattering experiments is clearly and unambiguously observed in the raw neutron data without applying any corrections. Results of these experiments are presented. (author).

  15. Orbital free molecular dynamics; Approche sans orbitale des plasmas denses

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, F

    2007-08-15

    The microscopic properties of hot and dense plasmas stay a field essentially studied thanks to classical theories like the One Component Plasma, models which rely on free parameters, particularly ionization. In order to investigate these systems, we have used, in this PhD work, a semi-classical model, without free parameters, that is based on coupling consistently classical molecular dynamics for the nuclei and orbital free density functional theory for the electrons. The electronic fluid is represented by a free energy entirely determined by the local density. This approximation was validated by a comparison with an ab initio technique, quantum molecular dynamics. This one is identical to the previous except for the description of the free energy that depends on a quantum-independent-particle model. Orbital free molecular dynamics was then used to compute equation of state of boron and iron plasmas in the hot and dense regime. Furthermore, comparisons with classical theories were performed on structural and dynamical properties. Finally, equation of state and transport coefficients mixing laws were studied by direct simulation of a plasma composed of deuterium and copper. (author)

  16. Well-posed two-temperature constitutive equations for stable dense fluid shock waves using molecular dynamics and generalizations of Navier-Stokes-Fourier continuum mechanics.

    Science.gov (United States)

    Hoover, Wm G; Hoover, Carol G

    2010-04-01

    Guided by molecular dynamics simulations, we generalize the Navier-Stokes-Fourier constitutive equations and the continuum motion equations to include both transverse and longitudinal temperatures. To do so we partition the contributions of the heat transfer, the work done, and the heat flux vector between the longitudinal and transverse temperatures. With shockwave boundary conditions time-dependent solutions of these equations converge to give stationary shockwave profiles. The profiles include anisotropic temperature and can be fitted to molecular dynamics results, demonstrating the utility and simplicity of a two-temperature description of far-from-equilibrium states.

  17. Dynamic conductivity and partial ionization in dense fluid hydrogen

    Science.gov (United States)

    Zaghoo, Mohamed

    2018-04-01

    A theoretical description for optical conduction experiments in dense fluid hydrogen is presented. Different quantum statistical approaches are used to describe the mechanism of electronic transport in hydrogen's high-temperature dense phase. We show that at the onset of the metallic transition, optical conduction could be described by a strong rise in atomic polarizability, due to increased ionization, whereas in the highly degenerate limit, the Ziman weak scattering model better accounts for the observed saturation of reflectance. The inclusion of effects of partial ionization in the highly degenerate region provides great agreement with experimental results. Hydrogen's fluid metallic state is revealed to be a partially ionized free-electron plasma. Our results provide some of the first theoretical transport models that are experimentally benchmarked, as well as an important guide for future studies.

  18. Transport coefficients of dense fluids composed of globular molecules. Equilibrium molecular dynamics investigations using more-center Lennard-Jones potentials

    Science.gov (United States)

    Hoheisel, C.

    1988-09-01

    Equilibrium molecular dynamics calculations with constraints have been performed for model liquids SF6 and CF4. The computations were carried out with four- and six-center Lennard-Jones potentials and up to 2×105 integration steps. Shear, bulk viscosity and the thermal conductivity have been calculated with use of Green-Kubo relations in the formulation of ``molecule variables.'' Various thermodynamic states were investigated. For SF6, a detailed comparison with experimental data was possible. For CF4, the MD results could only be compared with experiment for one liquid state. For the latter liquid, a complementary comparison was performed using MD results obtained with a one-center Lennard-Jones potential. A limited test of the particle number dependence of the results is presented. Partial and total correlations functions are shown and discussed with respect to findings obtained for the one-center Lennard-Jones liquid.

  19. DENSE MOLECULAR CORES BEING EXTERNALLY HEATED

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwanjeong; Lee, Chang Won; Kim, Mi-Ryang [Radio Astronomy division, Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon, 34055 (Korea, Republic of); Gopinathan, Maheswar [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263129 (India); Jeong, Woong-Seob, E-mail: archer81@kasi.re.kr [Department of Astronomy and Space Science, University of Science and Technology, 217 Gajungro, Yuseong-gu, Daejeon, 34113 (Korea, Republic of)

    2016-06-20

    We present results of our study of eight dense cores, previously classified as starless, using infrared (3–160 μ m) imaging observations with the AKARI telescope and molecular line (HCN and N{sub 2}H{sup +}) mapping observations with the KVN telescope. Combining our results with the archival IR to millimeter continuum data, we examined the starless nature of these eight cores. Two of the eight cores are found to harbor faint protostars having luminosities of ∼0.3–4.4 L {sub ⊙}. The other six cores are found to remain starless and probably are in a dynamically transitional state. The temperature maps produced using multi-wavelength images show an enhancement of about 3–6 K toward the outer boundary of these cores, suggesting that they are most likely being heated externally by nearby stars and/or interstellar radiation fields. Large virial parameters and an overdominance of red asymmetric line profiles over the cores may indicate that the cores are set into either an expansion or an oscillatory motion, probably due to the external heating. Most of the starless cores show a coreshine effect due to the scattering of light by the micron-sized dust grains. This may imply that the age of the cores is of the order of ∼10{sup 5} years, which is consistent with the timescale required for the cores to evolve into an oscillatory stage due to external perturbation. Our observational results support the idea that the external feedback from nearby stars and/or interstellar radiation fields may play an important role in the dynamical evolution of the cores.

  20. Theory of the shock process in dense fluids

    International Nuclear Information System (INIS)

    Wallace, D.C.

    1991-01-01

    A shock is assumed to be a steady plane wave, and irreversible thermodynamics is assumed valid. The fluid is characterized by heat conduction and by viscous or viscoelastic response, according to the strain rate. It is shown that setting the viscosity zero produces a solution which constitutes a lower bound through the shock process for the shear stress, and upper bounds for the temperature, entropy, pressure, and heat current. It is shown that there exists an upper bound to the dynamic stresses which can be achieved during shock compression, that this bound corresponds to a purely elastic response of the fluid, and that solution for the shock process along this bound constitutes lower bounds for the temperature and entropy. It is shown that a continuous steady shock is possible only if the heat current is positive and the temperature is an increasing function of compression almost everywhere. In his theory of shocks in gases, Rayleigh showed that there is a maximum shock strength for which a continuous steady solution can exist with heat conduction but without viscosity. Two more limits are shown to exist for dense fluids, based on the fluid response in the leading edge of the shock: for shocks at the overdriven threshold and above, no solution is possible without heat transport; for shocks near the viscous fluid limit and above, viscous fluid theory is not valid, and the fluid response in the leading edge of the shock is approximately that of a nonplastic solid. The viscous fluid limit is estimated to be 13 kbar for water and 690 kbar for mercury

  1. Bonding and structure in dense multi-component molecular mixtures.

    Science.gov (United States)

    Meyer, Edmund R; Ticknor, Christopher; Bethkenhagen, Mandy; Hamel, Sebastien; Redmer, Ronald; Kress, Joel D; Collins, Lee A

    2015-10-28

    We have performed finite-temperature density functional theory molecular dynamics simulations on dense methane, ammonia, and water mixtures (CH4:NH3:H2O) for various compositions and temperatures (2000 K ≤ T ≤ 10,000 K) that span a set of possible conditions in the interiors of ice-giant exoplanets. The equation-of-state, pair distribution functions, and bond autocorrelation functions (BACF) were used to probe the structure and dynamics of these complex fluids. In particular, an improvement to the choice of the cutoff in the BACF was developed that allowed analysis refinements for density and temperature effects. We note the relative changes in the nature of these systems engendered by variations in the concentration ratios. A basic tenet emerges from all these comparisons that varying the relative amounts of the three heavy components (C,N,O) can effect considerable changes in the nature of the fluid and may in turn have ramifications for the structure and composition of various planetary layers.

  2. Molecular thermodynamics of nonideal fluids

    CERN Document Server

    Lee, Lloyd L

    2013-01-01

    Molecular Thermodynamics of Nonideal Fluids serves as an introductory presentation for engineers to the concepts and principles behind and the advances in molecular thermodynamics of nonideal fluids. The book covers related topics such as the laws of thermodynamics; entropy; its ensembles; the different properties of the ideal gas; and the structure of liquids. Also covered in the book are topics such as integral equation theories; theories for polar fluids; solution thermodynamics; and molecular dynamics. The text is recommended for engineers who would like to be familiarized with the concept

  3. High frequency flow-structural interaction in dense subsonic fluids

    Science.gov (United States)

    Liu, Baw-Lin; Ofarrell, J. M.

    1995-01-01

    Prediction of the detailed dynamic behavior in rocket propellant feed systems and engines and other such high-energy fluid systems requires precise analysis to assure structural performance. Designs sometimes require placement of bluff bodies in a flow passage. Additionally, there are flexibilities in ducts, liners, and piping systems. A design handbook and interactive data base have been developed for assessing flow/structural interactions to be used as a tool in design and development, to evaluate applicable geometries before problems develop, or to eliminate or minimize problems with existing hardware. This is a compilation of analytical/empirical data and techniques to evaluate detailed dynamic characteristics of both the fluid and structures. These techniques have direct applicability to rocket engine internal flow passages, hot gas drive systems, and vehicle propellant feed systems. Organization of the handbook is by basic geometries for estimating Strouhal numbers, added mass effects, mode shapes for various end constraints, critical onset flow conditions, and possible structural response amplitudes. Emphasis is on dense fluids and high structural loading potential for fatigue at low subsonic flow speeds where high-frequency excitations are possible. Avoidance and corrective measure illustrations are presented together with analytical curve fits for predictions compiled from a comprehensive data base.

  4. A kinetic theory description of the viscosity of dense fluids consisting of chain molecules.

    Science.gov (United States)

    de Wijn, Astrid S; Vesovic, Velisa; Jackson, George; Trusler, J P Martin

    2008-05-28

    An expression for the viscosity of a dense fluid is presented that includes the effect of molecular shape. The molecules of the fluid are approximated by chains of equal-sized, tangentially jointed, rigid spheres. It is assumed that the collision dynamics in such a fluid can be approximated by instantaneous collisions between two rigid spheres belonging to different chains. The approach is thus analogous to that of Enskog for a fluid consisting of rigid spheres. The description is developed in terms of two molecular parameters, the diameter sigma of the spherical segment and the chain length (number of segments) m. It is demonstrated that an analysis of viscosity data of a particular pure fluid alone cannot be used to obtain independently effective values of both sigma and m. Nevertheless, the chain lengths of n-alkanes are determined by assuming that the diameter of each rigid sphere making up the chain can be represented by the diameter of a methane molecule. The effective chain lengths of n-alkanes are found to increase linearly with the number C of carbon atoms present. The dependence can be approximated by a simple relationship m=1+(C-1)3. The same relationship was reported within the context of a statistical associating fluid theory equation of state treatment of the fluid, indicating that both the equilibrium thermodynamic properties and viscosity yield the same value for the chain lengths of n-alkanes.

  5. Color molecular dynamics for dense matter

    International Nuclear Information System (INIS)

    Maruyama, Toshiki; Hatsuda, Tetsuo

    2000-01-01

    We propose a microscopic approach for quark many-body system based on molecular dynamics. Using color confinement and one-gluon exchange potentials together with meson exchange potentials between quarks, we construct nucleons and nuclear/quark matter. Dynamical transition between confinement and deconfinement phases are studied at high baryon density with this molecular dynamics simulation. (author)

  6. Modeling of dilute and dense dispersed fluid-particle flow

    Energy Technology Data Exchange (ETDEWEB)

    Laux, Harald

    1998-08-01

    A general two-fluid model is derived and applied in CFD computations to various test cases of important industrial multiphase flows. It is general in the sense of its applicability to dilute and dense dispersed fluid-particle flows. The model is limited to isothermal flow without mass transfer and only one particle phase is described. The instantaneous fluid phase equations, including the phase interaction terms, are derived from a volume averaging technique, and the instantaneous particle phase equations are derived from the kinetic theory of granular material. Whereas the averaging procedure, the treatment of the interaction terms, and the kinetic theory approach have been reported in literature prior to this work the combination of the approaches is new. The resulting equations are derived without ambiguity in the interpretation of the particle phase pressure (equation-of-state of particle phase). The basic modeling for the particle phase is improved in two steps. Because in the basic modeling only stresses due to kinetic and collisional interactions are included, a simple model for an effective viscosity is developed in order to allow also frictional stresses within the particle phase. Moreover, turbulent stresses and turbulent dispersion of particles play often an important role for the transport processes. Therefore in a second step, a two-equation turbulence model for both fluid and particle phase turbulence is derived by applying the phasic average to the instantaneous equations. The resulting k-{epsilon}-k{sup d}-{epsilon}{sup d} model is new. Mathematical closure is attempted such that the resulting set of equations is valid for both dilute arid dense flows. During the development of the closure relations a clear distinction is made between granular or ''viscous'' microscale fluctuations and turbulent macro scale fluctuations (true particle turbulence) within the particle phase. The set of governing equations is discretized by using a

  7. Modeling of dilute and dense dispersed fluid-particle flow

    Energy Technology Data Exchange (ETDEWEB)

    Laux, Harald

    1998-08-01

    A general two-fluid model is derived and applied in CFD computations to various test cases of important industrial multiphase flows. It is general in the sense of its applicability to dilute and dense dispersed fluid-particle flows. The model is limited to isothermal flow without mass transfer and only one particle phase is described. The instantaneous fluid phase equations, including the phase interaction terms, are derived from a volume averaging technique, and the instantaneous particle phase equations are derived from the kinetic theory of granular material. Whereas the averaging procedure, the treatment of the interaction terms, and the kinetic theory approach have been reported in literature prior to this work the combination of the approaches is new. The resulting equations are derived without ambiguity in the interpretation of the particle phase pressure (equation-of-state of particle phase). The basic modeling for the particle phase is improved in two steps. Because in the basic modeling only stresses due to kinetic and collisional interactions are included, a simple model for an effective viscosity is developed in order to allow also frictional stresses within the particle phase. Moreover, turbulent stresses and turbulent dispersion of particles play often an important role for the transport processes. Therefore in a second step, a two-equation turbulence model for both fluid and particle phase turbulence is derived by applying the phasic average to the instantaneous equations. The resulting k-{epsilon}-k{sup d}-{epsilon}{sup d} model is new. Mathematical closure is attempted such that the resulting set of equations is valid for both dilute arid dense flows. During the development of the closure relations a clear distinction is made between granular or ''viscous'' microscale fluctuations and turbulent macro scale fluctuations (true particle turbulence) within the particle phase. The set of governing equations is discretized by using a finite volume method

  8. Carbon chemistry in dense molecular clouds: Theory and observational constraints

    International Nuclear Information System (INIS)

    Blake, G.A.

    1990-01-01

    For the most part, gas phase models of the chemistry of dense molecular clouds predict the abundances of simple species rather well. However, for larger molecules and even for small systems rich in carbon these models often fail spectacularly. Researchers present a brief review of the basic assumptions and results of large scale modeling of the carbon chemistry in dense molecular clouds. Particular attention is to the influence of the gas phase C/O ratio in molecular clouds, and the likely role grains play in maintaining this ratio as clouds evolve from initially diffuse objects to denser cores with associated stellar and planetary formation. Recent spectral line surveys at centimeter and millimeter wavelengths along with selected observations in the submillimeter have now produced an accurate inventory of the gas phase carbon budget in several different types of molecular clouds, though gaps in our knowledge clearly remain. The constraints these observations place on theoretical models of interstellar chemistry can be used to gain insights into why the models fail, and show also which neglected processes must be included in more complete analyses. Looking toward the future, larger molecules are especially difficult to study both experimentally and theoretically in such dense, cold regions, and some new methods are therefore outlined which may ultimately push the detectability of small carbon chains and rings to much heavier species

  9. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    or an estimate there-of is known. Estimated flow fields in weather satellite imagery might also be used on an operational basis as inputs to short-term weather prediction. In this article we describe a method for the estimation of dense flow fields. Local measurements of motion are obtained by analysis...

  10. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    1998-01-01

    or an estimate there-of is known. Estimated flow fields in weather satellite imagery might also be used on an operational basis as inputs to short-term weather prediction. In this article we describe a method for the estimation of dense flow fields. Local measurements of motion are obtained by analysis...

  11. The role of triplet correlation function in dense fluids

    International Nuclear Information System (INIS)

    Rashid, R.I.M.A.

    1993-09-01

    In the theory of dense liquids, one usually introduces various correlation functions for describing properties of such systems. It has proved impossible to solve these correlation functions exactly and as such one often resorts to some meaningful approximations for their solutions. It is well known that unless proper precautions are taken, the approximate solutions will violate some useful sum rules and thermodynamic consistency conditions. Here the general rules for generating thermodynamically consistent approximate correlation functions are discussed. The role of triplet correlation is elucidated further by calculating a residual correction to the vacancy formation energy via three-particle correlation in rare gas solids. (author). 16 refs, 4 figs, 1 tab

  12. Quantum molecular dynamics simulations of thermophysical properties of fluid ethane

    OpenAIRE

    Zhang, Yujuan; Wang, Cong; Zheng, Fawei; Zhang, Ping

    2012-01-01

    We have performed first-principles molecular-dynamics simulations based on density-functional theory to study the thermophysical properties of ethane under extreme conditions. We present new results for the equation of state of fluid ethane in the warm dense region. The optical conductivity is calculated via the Kubo-Greenwood formula from which the dc conductivity and optical reflectivity are derived. The close correlation between the nonmetal-metal transition of ethane and its decomposition...

  13. Bulk viscosity of molecular fluids

    Science.gov (United States)

    Jaeger, Frederike; Matar, Omar K.; Müller, Erich A.

    2018-05-01

    The bulk viscosity of molecular models of gases and liquids is determined by molecular simulations as a combination of a dilute gas contribution, arising due to the relaxation of internal degrees of freedom, and a configurational contribution, due to the presence of intermolecular interactions. The dilute gas contribution is evaluated using experimental data for the relaxation times of vibrational and rotational degrees of freedom. The configurational part is calculated using Green-Kubo relations for the fluctuations of the pressure tensor obtained from equilibrium microcanonical molecular dynamics simulations. As a benchmark, the Lennard-Jones fluid is studied. Both atomistic and coarse-grained force fields for water, CO2, and n-decane are considered and tested for their accuracy, and where possible, compared to experimental data. The dilute gas contribution to the bulk viscosity is seen to be significant only in the cases when intramolecular relaxation times are in the μs range, and for low vibrational wave numbers (<1000 cm-1); This explains the abnormally high values of bulk viscosity reported for CO2. In all other cases studied, the dilute gas contribution is negligible and the configurational contribution dominates the overall behavior. In particular, the configurational term is responsible for the enhancement of the bulk viscosity near the critical point.

  14. Test of a new heat-flow equation for dense-fluid shock waves.

    Science.gov (United States)

    Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon

    2010-09-21

    Using a recently proposed equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, we model shockwave propagation in the dense Lennard-Jones fluid. Disequilibrium among the three components of temperature, namely, the difference between the kinetic temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, gives rise to a new transport (equilibration) mechanism not seen in usual one-dimensional heat-flow situations. The modification of the heat-flow equation was tested earlier for the case of strong shock waves in the ideal gas, which had been studied in the past and compared to Navier-Stokes-Fourier solutions. Now, the Lennard-Jones fluid, whose equation of state and transport properties have been determined from independent calculations, allows us to study the case where potential, as well as kinetic contributions are important. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations under strong shock wave conditions, compared to Navier-Stokes.

  15. Structural relaxation in dense hard-sphere fluids

    International Nuclear Information System (INIS)

    Ladd, A.J.C.; Edward Alley, W.; Alder, B.J.

    1987-01-01

    The long-time decay of the shear-stress autocorrelation function is shown to be quantitatively related to the decay of correlations between the orientation of ''bonds'' connecting colliding pairs of particles. Within computational uncertainties, we find that orientational correlations in high-density fluids decay as a ''stretched'' exponential in time, with an exponent that is independent of density. However, at low densities the decay is exponential. In two-dimensional systems the decay is exponential, even at high density

  16. ON THE FORMATION OF GLYCOLALDEHYDE IN DENSE MOLECULAR CORES

    Energy Technology Data Exchange (ETDEWEB)

    Woods, Paul M.; Kelly, George; Viti, Serena [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Slater, Ben; Brown, Wendy A.; Puletti, Fabrizio; Burke, Daren J.; Raza, Zamaan, E-mail: paul.woods@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2012-05-01

    Glycolaldehyde is a simple monosaccharide sugar linked to prebiotic chemistry. Recently, it was detected in a molecular core in the star-forming region G31.41+0.31 at a reasonably high abundance. We investigate the formation of glycolaldehyde at 10 K to determine whether it can form efficiently under typical dense core conditions. Using an astrochemical model, we test five different reaction mechanisms that have been proposed in the astrophysical literature, finding that a gas-phase formation route is unlikely. Of the grain-surface formation routes, only two are efficient enough at very low temperatures to produce sufficient glycolaldehyde to match the observational estimates, with the mechanism culminating in CH{sub 3}OH + HCO being favored. However, when we consider the feasibility of these mechanisms from a reaction chemistry perspective, the second grain-surface route looks more promising, H{sub 3}CO + HCO.

  17. ON THE FORMATION OF GLYCOLALDEHYDE IN DENSE MOLECULAR CORES

    International Nuclear Information System (INIS)

    Woods, Paul M.; Kelly, George; Viti, Serena; Slater, Ben; Brown, Wendy A.; Puletti, Fabrizio; Burke, Daren J.; Raza, Zamaan

    2012-01-01

    Glycolaldehyde is a simple monosaccharide sugar linked to prebiotic chemistry. Recently, it was detected in a molecular core in the star-forming region G31.41+0.31 at a reasonably high abundance. We investigate the formation of glycolaldehyde at 10 K to determine whether it can form efficiently under typical dense core conditions. Using an astrochemical model, we test five different reaction mechanisms that have been proposed in the astrophysical literature, finding that a gas-phase formation route is unlikely. Of the grain-surface formation routes, only two are efficient enough at very low temperatures to produce sufficient glycolaldehyde to match the observational estimates, with the mechanism culminating in CH 3 OH + HCO being favored. However, when we consider the feasibility of these mechanisms from a reaction chemistry perspective, the second grain-surface route looks more promising, H 3 CO + HCO.

  18. DENSE CLUMPS AND CANDIDATES FOR MOLECULAR OUTFLOWS IN W40

    Energy Technology Data Exchange (ETDEWEB)

    Shimoikura, Tomomi; Dobashi, Kazuhito [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Nakamura, Fumitaka; Hara, Chihomi; Kawabe, Ryohei [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tanaka, Tomohiro [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Shimajiri, Yoshito [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Sugitani, Kouji, E-mail: ikura@u-gakugei.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan)

    2015-06-20

    We report the results of the {sup 12}CO (J = 3−2) and HCO{sup +} (J = 4−3) observations of the W40 H ii region with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope (HPBW ≃ 22″) to search for molecular outflows and dense clumps. We found that the velocity field in the region is highly complex, consisting of at least four distinct velocity components at V{sub LSR} ≃ 3, 5, 7, and 10 km s{sup −1}. The ∼7 km s{sup −1} component represents the systemic velocity of cold gas surrounding the entire region, and causes heavy absorption in the {sup 12}CO spectra over the velocity range 6 ≲ V{sub LSR} ≲ 9 km s{sup −1}. The ∼5 and ∼10 km s{sup −1} components exhibit high {sup 12}CO temperature (≳40 K) and are found mostly around the H ii region, suggesting that these components are likely to be tracing dense gas interacting with the expanding shell around the H ii region. Based on the {sup 12}CO data, we identified 13 regions of high velocity gas, which we interpret as candidate outflow lobes. Using the HCO{sup +} data, we also identified six clumps and estimated their physical parameters. On the basis of the ASTE data and near-infrared images from 2MASS, we present an updated three-dimensional model of this region. In order to investigate molecular outflows in W40, the SiO (J = 1−0, v = 0) emission line and some other emission lines at 40 GHz were also observed with the 45 m telescope at the Nobeyama Radio Observatory, but they were not detected at the present sensitivity.

  19. Molecular mechanics and structure of the fluid-solid interface in simple fluids

    Science.gov (United States)

    Wang, Gerald J.; Hadjiconstantinou, Nicolas G.

    2017-09-01

    Near a fluid-solid interface, the fluid spatial density profile is highly nonuniform at the molecular scale. This nonuniformity can have profound effects on the dynamical behavior of the fluid and has been shown to play an especially important role when modeling a wide variety of nanoscale heat and momentum transfer phenomena. We use molecular-mechanics arguments and molecular-dynamics (MD) simulations to develop a better understanding of the structure of the first fluid layer directly adjacent to the solid in the layering regime, as delineated by a nondimensional number that compares the effects of wall-fluid interaction to thermal energy. Using asymptotic analysis of the Nernst-Planck equation, we show that features of the fluid density profile close to the wall, such as the areal density of the first layer ΣFL (defined as the number of atoms in this layer per unit of fluid-solid interfacial area), can be expressed as polynomial functions of the fluid average density ρave. This is found to be in agreement with MD simulations, which also show that the width of the first layer hFL is a linear function of the average density and only a weak function of the temperature T . These results can be combined to show that, for system average densities corresponding to a dense fluid (ρave≥0.7 ), the ratio C ≡ΣFLρavehFL, representing a density enhancement with respect to the bulk fluid, depends only weakly on temperature and is essentially independent of density. Further MD simulations suggest that the above results, nominally valid for large systems (solid in contact with semi-infinite fluid), also describe fluid-solid interfaces under considerable nanoconfinement, provided ρave is appropriately defined.

  20. The CO Transition from Diffuse Molecular Gas to Dense Clouds

    Science.gov (United States)

    Rice, Johnathan S.; Federman, Steven

    2017-06-01

    The atomic to molecular transitions occurring in diffuse interstellar gas surrounding molecular clouds are affected by the local physical conditions (density and temperature) and the radiation field penetrating the material. Our optical observations of CH, CH^{+}, and CN absorption from McDonald Observatory and the European Southern Observatory are useful tracers of this gas and provide the velocity structure needed for analyzing lower resolution ultraviolet observations of CO and H_{2} absorption from Far Ultraviolet Spectroscopic Explorer. We explore the changing environment between diffuse and dense gas by using the column densities and excitation temperatures from CO and H_{2} to determine the gas density. The resulting gas densities from this method are compared to densities inferred from other methods such as C_{2} and CN chemistry. The densities allow us to interpret the trends from the combined set of tracers. Groupings of sight lines, such as those toward h and χ Persei or Chameleon provide a chance for further characterization of the environment. The Chameleon region in particular helps illuminate CO-dark gas, which is not associated with emission from H I at 21 cm or from CO at 2.6 mm. Expanding this analysis to include emission data from the GOT C+ survey allows the further characterization of neutral diffuse gas, including CO-dark gas.

  1. Quantum molecular dynamics simulations of thermophysical properties of fluid ethane.

    Science.gov (United States)

    Zhang, Yujuan; Wang, Cong; Zheng, Fawei; Zhang, Ping

    2012-12-01

    We have performed first-principles molecular-dynamics simulations based on density-functional theory to study the thermophysical properties of ethane under extreme conditions. We present results for the equation of state of fluid ethane in the warm dense region. The optical conductivity is calculated via the Kubo-Greenwood formula from which the dc conductivity and optical reflectivity are derived. The close correlation between the nonmetal-metal transition of ethane and its decomposition, that ethane dissociates significantly into molecular and/or atomic hydrogen and some long alkane chains, has been systematically studied by analyzing the optical conductivity spectra, pair correlation functions, electronic density of states, and charge density distribution of fluid ethane.

  2. Three-particle equilibrium correlations in dense hard-sphere fluids

    NARCIS (Netherlands)

    Haffmans, A.F.E.M.; Schepper, I.M. de; Michels, J.P.J.; Beijeren, H. van

    1988-01-01

    We performed molecular-dynamics simulation experiments for a hard-sphere fluid at four high densities and determined the spatial Fourier transform of the three-particle equilibrium correlation function with two of the three particles at contact.

  3. The influence of molecular complexity on expanding flows of ideal and dense gases

    NARCIS (Netherlands)

    Harinck, J.; Guardone, A.; Colonna, P.

    2009-01-01

    This paper presents an investigation about the effect of the complexity of a fluid molecule on the fluid dynamic quantities sound speed, velocity, and Mach number in isentropic expansions. Ideal-gas and dense-gas expansions are analyzed, using the polytropic ideal gas and Van der Waals thermodynamic

  4. The fluid dynamics of a basaltic magma chamber replenished by influx of hot, dense ultrabasic magma

    Science.gov (United States)

    Huppert, Herbert E.; Sparks, R. Stephen J.

    1981-09-01

    This paper describes a fluid dynamical investigation of the influx of hot, dense ultrabasic magma into a reservoir containing lighter, fractionated basaltic magma. This situation is compared with that which develops when hot salty water is introduced under cold fresh water. Theoretical and empirical models for salt/water systems are adapted to develop a model for magmatic systems. A feature of the model is that the ultrabasic melt does not immediately mix with the basalt, but spreads out over the floor of the chamber, forming an independent layer. A non-turbulent interface forms between this layer and the overlying magma layer across which heat and mass are transferred by the process of molecular diffusion. Both layers convect vigorously as heat is transferred to the upper layer at a rate which greatly exceeds the heat lost to the surrounding country rock. The convection continues until the two layers have almost the same temperature. The compositions of the layers remain distinct due to the low diffusivity of mass compared to heat. The temperatures of the layers as functions of time and their cooling rate depend on their viscosities, their thermal properties, the density difference between the layers and their thicknesses. For a layer of ultrabasic melt (18% MgO) a few tens of metres thick at the base of a basaltic (10% MgO) magma chamber a few kilometres thick, the temperature of the layers will become nearly identical over a period of between a few months and a few years. During this time the turbulent convective velocities in the ultrabasic layer are far larger than the settling velocity of olivines which crystallise within the layer during cooling. Olivines only settle after the two layers have nearly reached thermal equilibrium. At this stage residual basaltic melt segregates as the olivines sediment in the lower layer. Depending on its density, the released basalt can either mix convectively with the overlying basalt layer, or can continue as a separate

  5. Equilibrium properties of dense hydrogen isotope gases based on the theory of simple fluids.

    Science.gov (United States)

    Kowalczyk, Piotr; MacElroy, J M D

    2006-08-03

    We present a new method for the prediction of the equilibrium properties of dense gases containing hydrogen isotopes. The proposed approach combines the Feynman-Hibbs effective potential method and a deconvolution scheme introduced by Weeks et al. The resulting equations of state and the chemical potentials as functions of pressure for each of the hydrogen isotope gases depend on a single set of Lennard-Jones parameters. In addition to its simplicity, the proposed method with optimized Lennard-Jones potential parameters accurately describes the equilibrium properties of hydrogen isotope fluids in the regime of moderate temperatures and pressures. The present approach should find applications in the nonlocal density functional theory of inhomogeneous quantum fluids and should also be of particular relevance to hydrogen (clean energy) storage and to the separation of quantum isotopes by novel nanomaterials.

  6. Sensitivity analysis of Immersed Boundary Method simulations of fluid flow in dense polydisperse random grain packings

    Directory of Open Access Journals (Sweden)

    Knight Chris

    2017-01-01

    Full Text Available Polydisperse granular materials are ubiquitous in nature and industry. Despite this, knowledge of the momentum coupling between the fluid and solid phases in dense saturated grain packings comes almost exclusively from empirical correlations [2–4, 8] with monosized media. The Immersed Boundary Method (IBM is a Computational Fluid Dynamics (CFD modelling technique capable of resolving pore scale fluid flow and fluid-particle interaction forces in polydisperse media at the grain scale. Validation of the IBM in the low Reynolds number, high concentration limit was performed by comparing simulations of flow through ordered arrays of spheres with the boundary integral results of Zick and Homsy [10]. Random grain packings were studied with linearly graded particle size distributions with a range of coefficient of uniformity values (Cu = 1.01, 1.50, and 2.00 at a range of concentrations (ϕ ∈ [0.396; 0.681] in order to investigate the influence of polydispersity on drag and permeability. The sensitivity of the IBM results to the choice of radius retraction parameter [1] was investigated and a comparison was made between the predicted forces and the widely used Ergun correlation [3].

  7. Subtle Monte Carlo Updates in Dense Molecular Systems

    DEFF Research Database (Denmark)

    Bottaro, Sandro; Boomsma, Wouter; Johansson, Kristoffer E.

    2012-01-01

    Although Markov chain Monte Carlo (MC) simulation is a potentially powerful approach for exploring conformational space, it has been unable to compete with molecular dynamics (MD) in the analysis of high density structural states, such as the native state of globular proteins. Here, we introduce...... as correlations in a multivariate Gaussian distribution. We demonstrate that our method reproduces structural variation in proteins with greater efficiency than current state-of-the-art Monte Carlo methods and has real-time simulation performance on par with molecular dynamics simulations. The presented results...... suggest our method as a valuable tool in the study of molecules in atomic detail, offering a potential alternative to molecular dynamics for probing long time-scale conformational transitions....

  8. Optimized theory for simple and molecular fluids.

    Science.gov (United States)

    Marucho, M; Montgomery Pettitt, B

    2007-03-28

    An optimized closure approximation for both simple and molecular fluids is presented. A smooth interpolation between Perkus-Yevick and hypernetted chain closures is optimized by minimizing the free energy self-consistently with respect to the interpolation parameter(s). The molecular version is derived from a refinement of the method for simple fluids. In doing so, a method is proposed which appropriately couples an optimized closure with the variant of the diagrammatically proper integral equation recently introduced by this laboratory [K. M. Dyer et al., J. Chem. Phys. 123, 204512 (2005)]. The simplicity of the expressions involved in this proposed theory has allowed the authors to obtain an analytic expression for the approximate excess chemical potential. This is shown to be an efficient tool to estimate, from first principles, the numerical value of the interpolation parameters defining the aforementioned closure. As a preliminary test, representative models for simple fluids and homonuclear diatomic Lennard-Jones fluids were analyzed, obtaining site-site correlation functions in excellent agreement with simulation data.

  9. MALT90 Kinematic Distances to Dense Molecular Clumps

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, J. Scott [Physics Department, Boston University, 590 Commonwealth Avenue, Boston, MA 02215 (United States); Jackson, James M.; Sanhueza, Patricio; Stephens, Ian W. [Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States); Rathborne, J. M. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia); Foster, J. B. [Department of Astronomy, Yale University, P.O. Box 28101, New Haven, CT 06520-8101 (United States); Contreras, Y. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Longmore, S. N., E-mail: scott@bu.edu [Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)

    2017-10-01

    Using molecular-line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have estimated kinematic distances to 1905 molecular clumps identified in the ATLASGAL 870 μ m continuum survey over the longitude range 295° <  l  < 350°. The clump velocities were determined using a flux-weighted average of the velocities obtained from Gaussian fits to the HCO{sup +}, HNC, and N{sub 2}H{sup +} (1–0) transitions. The near/far kinematic distance ambiguity was addressed by searching for the presence or absence of absorption or self-absorption features in 21 cm atomic hydrogen spectra from the Southern Galactic Plane Survey. Our algorithm provides an estimation of the reliability of the ambiguity resolution. The Galactic distribution of the clumps indicates positions where the clumps are bunched together, and these locations probably trace the locations of spiral arms. Several clumps fall at the predicted location of the far side of the Scutum–Centaurus arm. Moreover, a number of clumps with positive radial velocities are unambiguously located on the far side of the Milky Way at galactocentric radii beyond the solar circle. The measurement of these kinematic distances, in combination with continuum or molecular-line data, now enables the determination of fundamental parameters such as mass, size, and luminosity for each clump.

  10. Transport of excess electrons in dense dielectric fluids. Phenomenological interpretation and application to a one-dimensional argon fluid

    International Nuclear Information System (INIS)

    Leycuras, A.; Larour, J.

    1978-01-01

    The main results about the drift velocities of excess electrons in dense argon are summarized. The weaknesses of the available theories are mainly due to poor information concerning the electron-atom potential during an atom-atom collision. The drift velocities, as a function of the applied electric field present the following features at high fields: the drift velocity reaches a limit that is at most one order of magnitude larger than the sound velocity at the same density. These remarks and the attractive nature of the electron-atom potential suggest a transport model, the collisional transfer model analog to the one applied to the determination of the sound velocity. Drift velocities obtained with this model applied to a one-dimensional molecular dynamics simulation are presented [fr

  11. Influence of galactic arm scale dynamics on the molecular composition of the cold and dense ISM. I. Observed abundance gradients in dense clouds

    Science.gov (United States)

    Ruaud, M.; Wakelam, V.; Gratier, P.; Bonnell, I. A.

    2018-04-01

    Aim. We study the effect of large scale dynamics on the molecular composition of the dense interstellar medium during the transition between diffuse to dense clouds. Methods: We followed the formation of dense clouds (on sub-parsec scales) through the dynamics of the interstellar medium at galactic scales. We used results from smoothed particle hydrodynamics (SPH) simulations from which we extracted physical parameters that are used as inputs for our full gas-grain chemical model. In these simulations, the evolution of the interstellar matter is followed for 50 Myr. The warm low-density interstellar medium gas flows into spiral arms where orbit crowding produces the shock formation of dense clouds, which are held together temporarily by the external pressure. Results: We show that depending on the physical history of each SPH particle, the molecular composition of the modeled dense clouds presents a high dispersion in the computed abundances even if the local physical properties are similar. We find that carbon chains are the most affected species and show that these differences are directly connected to differences in (1) the electronic fraction, (2) the C/O ratio, and (3) the local physical conditions. We argue that differences in the dynamical evolution of the gas that formed dense clouds could account for the molecular diversity observed between and within these clouds. Conclusions: This study shows the importance of past physical conditions in establishing the chemical composition of the dense medium.

  12. Carbon molecular sieve dense film membranes derived from Matrimid® for ethylene/ethane separation

    KAUST Repository

    Rungta, Meha; Xu, Liren; Koros, William J.

    2012-01-01

    Development of dense film carbon molecular sieve (CMS) membranes for ethylene/ethane (C 2H 4/C 2H 6) separation is reported. A commercial polyimide, Matrimid®, was pyrolyzed under vacuum and inert argon atmosphere, and the resultant CMS films were

  13. The electronic and optical properties of warm dense nitrous oxide using quantum molecular dynamics simulations

    International Nuclear Information System (INIS)

    Zhang Yujuan; Wang Cong; Zhang Ping

    2012-01-01

    First-principles molecular-dynamics simulations based on density-functional theory have been used to study the electronic and optical properties of fluid nitrous oxide under extreme conditions. Systematic descriptions of pair-correlation function, atomic structure, and the charge density distribution are used to investigate the dissociation of fluid nitrous oxide. The electrical and optical properties are derived from the Kubo-Greenwood formula. It is found that the nonmetal-metal transition for fluid nitrous oxide can be directly associated to the dissociation and has significant influence on the optical properties of the fluid.

  14. Dense gas and star formation in individual Giant Molecular Clouds in M31

    Science.gov (United States)

    Viaene, S.; Forbrich, J.; Fritz, J.

    2018-04-01

    Studies both of entire galaxies and of local Galactic star formation indicate a dependency of a molecular cloud's star formation rate (SFR) on its dense gas mass. In external galaxies, such measurements are derived from HCN(1-0) observations, usually encompassing many Giant Molecular Clouds (GMCs) at once. The Andromeda galaxy (M31) is a unique laboratory to study the relation of the SFR and HCN emission down to GMC scales at solar-like metallicities. In this work, we correlate our composite SFR determinations with archival HCN, HCO+, and CO observations, resulting in a sample of nine reasonably representative GMCs. We find that, at the scale of individual clouds, it is important to take into account both obscured and unobscured star formation to determine the SFR. When correlated against the dense-gas mass from HCN, we find that the SFR is low, in spite of these refinements. We nevertheless retrieve an SFR-dense-gas mass correlation, confirming that these SFR tracers are still meaningful on GMC scales. The correlation improves markedly when we consider the HCN/CO ratio instead of HCN by itself. This nominally indicates a dependency of the SFR on the dense-gas fraction, in contradiction to local studies. However, we hypothesize that this partly reflects the limited dynamic range in dense-gas mass, and partly that the ratio of single-pointing HCN and CO measurements may be less prone to systematics like sidelobes. In this case, the HCN/CO ratio would importantly be a better empirical measure of the dense-gas content itself.

  15. Dense molecular clumps associated with the Large Magellanic Cloud supergiant shells LMC 4 and LMC 5

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Kosuke; Mizuno, Norikazu [Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Minamidani, Tetsuhiro [Nobeyama Radio Observatory, 462-2 Nobeyama Minamimaki-mura, Minamisaku-gun, Nagano 384-1305 (Japan); Onishi, Toshikazu; Muraoka, Kazuyuki [Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, Osaka 599-8531 (Japan); Kawamura, Akiko; Muller, Erik; Tatematsu, Ken' ichi; Hasegawa, Tetsuo; Miura, Rie E.; Ezawa, Hajime [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Dawson, Joanne [Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Tosaki, Tomoka [Joetsu University of Education, Yamayashiki-machi, Joetsu, Niigata 943-8512 (Japan); Sakai, Takeshi [Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Tsukagoshi, Takashi [College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512 (Japan); Tanaka, Kunihiko [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522 (Japan); Fukui, Yasuo, E-mail: kosuke.fujii@nao.ac.jp [Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

    2014-12-01

    We investigate the effects of supergiant shells (SGSs) and their interaction on dense molecular clumps by observing the Large Magellanic Cloud (LMC) star-forming regions N48 and N49, which are located between two SGSs, LMC 4 and LMC 5. {sup 12}CO (J = 3-2, 1-0) and {sup 13}CO(J = 1-0) observations with the ASTE and Mopra telescopes have been carried out toward these regions. A clumpy distribution of dense molecular clumps is revealed with 7 pc spatial resolution. Large velocity gradient analysis shows that the molecular hydrogen densities (n(H{sub 2})) of the clumps are distributed from low to high density (10{sup 3}-10{sup 5} cm{sup –3}) and their kinetic temperatures (T {sub kin}) are typically high (greater than 50 K). These clumps seem to be in the early stages of star formation, as also indicated from the distribution of Hα, young stellar object candidates, and IR emission. We found that the N48 region is located in the high column density H I envelope at the interface of the two SGSs and the star formation is relatively evolved, whereas the N49 region is associated with LMC 5 alone and the star formation is quiet. The clumps in the N48 region typically show high n(H{sub 2}) and T {sub kin}, which are as dense and warm as the clumps in LMC massive cluster-forming areas (30 Dor, N159). These results suggest that the large-scale structure of the SGSs, especially the interaction of two SGSs, works efficiently on the formation of dense molecular clumps and stars.

  16. On axial temperature gradients due to large pressure drops in dense fluid chromatography.

    Science.gov (United States)

    Colgate, Sam O; Berger, Terry A

    2015-03-13

    fluid in the column, contributing either to warming or cooling depending on local density and temperature. The molecular basis for this variation is described. Sample calculations of dissipation and temperature profiles of several model fluids including carbon dioxide-methanol mixtures are presented, based on the NIST REFPROP program including select equations of state and property calculation software. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Direct coupling of a dense (supercritical) gas chromatograph to a mass spectrometer using a supersonic molecular beam interface

    International Nuclear Information System (INIS)

    Randall, L.G.; Wahrhaftig, A.L.

    1981-01-01

    A detecting mass spectrometer has been successfully coupled to a dense gas (supercritical fluid) chromatograph to produce an instrument (DGC/MS) that may be an alternative to high performance liquid chromatograph/mass spectrometer instruments (HPLC/MS) and gas chromatograph/mass spectrometer instruments (GC/MS) for analysis of involatile and/or thermally labile compounds. The mobile phase in DGC is a gas held at temperatures above the critical temperature and at pressures sufficient to obtain nearly liquid-like densities. DGC combines advantages of GC and HPLC: rapid separations, moderate operating temperatures, and analysis of involatile compounds. An advantage unique to DGC is the solvent power dependence upon pressure. While several groups have studied DGC, its development has been limited by the lack of a sensitive and selective detector. Hence, work has been directed towards the design and construction of a DGC/MS resulting in a trial instrument capable of chromatographic pressures of at least 300 atm and temperatures from 10 0 to 60 0 C. The DGC/MS coupling has been accomplished by the use of a supersonic molecular beam interface. This application of molecular beam formation appears to be unique in its requirements of a large pressure ratio (approx.10 8 ), low flow rates, and low final pressures. The authors outline characteristics of supersonic jets and molecular beams pertinent to the design of such an instrument. The interface which uses pumping speeds of 2400 and 1200 l/s in the beam forming chambers is described in detail, while the other components: the detecting mass spectrometer, the dense gas supply, and the DGC: are briefly described. Preliminary work with this instrument has established the feasibility of DGC/MS as an analytical technique and further development is recommended

  18. An influence of low-stability region on dense gas phenomena and their peculiarities in the ORC fluids

    Directory of Open Access Journals (Sweden)

    Matuszewska Dominika

    2014-01-01

    Full Text Available An existence of low stability region in the dense vapours and its influence on some peculiarities in behaviour of selected dry and isentropic ORC fluids is discussed. The retrograde phenomena in the flow of BZT fluids [1.] can be simply related to the mechanical and thermodynamic stability parameters. These new refrigerant and their properties have been analysed based on the software tools REFPROP v.9.1 [2.]. Test examples have confirmed an importance of low thermodynamic stability area in the vicinity of saturation boundary line and neighbourhood of critical point of the fluid. The analytical results have been obtained for selected pure fluids applicable in the ORC and heat pump technology such C4H10, C6H5CH3, C12H26, R123, R134a, R227ea, R245fa, low GWP hydrofluoroolefins (R1234xxXand a group of linear and cyclic siloxanes.

  19. A glimpse of fluid turbulence from the molecular scale

    KAUST Repository

    Komatsu, Teruhisa S.

    2014-08-01

    Large-scale molecular dynamics (MD) simulations of freely decaying turbulence in three-dimensional space are reported. Fluid components are defined from the microscopic states by eliminating thermal components from the coarse-grained fields. The energy spectrum of the fluid components is observed to scale reasonably well according to Kolmogorov scaling determined from the energy dissipation rate and the viscosity of the fluid, even though the Kolmogorov length is of the order of the molecular scale. © 2014 The Authors.

  20. Toward Measuring Galactic Dense Molecular Gas Properties and 3D Distribution with Hi-GAL

    Science.gov (United States)

    Zetterlund, Erika; Glenn, Jason; Maloney, Phil

    2016-01-01

    The Herschel Space Observatory's submillimeter dust continuum survey Hi-GAL provides a powerful new dataset for characterizing the structure of the dense interstellar medium of the Milky Way. Hi-GAL observed a 2° wide strip covering the entire 360° of the Galactic plane in broad bands centered at 70, 160, 250, 350, and 500 μm, with angular resolution ranging from 10 to 40 arcseconds. We are adapting a molecular cloud clump-finding algorithm and a distance probability density function distance-determination method developed for the Bolocam Galactic Plane Survey (BGPS) to the Hi-GAL data. Using these methods we expect to generate a database of 105 cloud clumps, derive distance information for roughly half the clumps, and derive precise distances for approximately 20% of them. With five-color photometry and distances, we will measure the cloud clump properties, such as luminosities, physical sizes, and masses, and construct a three-dimensional map of the Milky Way's dense molecular gas distribution.The cloud clump properties and the dense gas distribution will provide critical ground truths for comparison to theoretical models of molecular cloud structure formation and galaxy evolution models that seek to emulate spiral galaxies. For example, such models cannot resolve star formation and use prescriptive recipes, such as converting a fixed fraction of interstellar gas to stars at a specified interstellar medium density threshold. The models should be compared to observed dense molecular gas properties and galactic distributions.As a pilot survey to refine the clump-finding and distance measurement algorithms developed for BGPS, we have identified molecular cloud clumps in six 2° × 2° patches of the Galactic plane, including one in the inner Galaxy along the line of sight through the Molecular Ring and the termination of the Galactic bar and one toward the outer Galaxy. Distances have been derived for the inner Galaxy clumps and compared to Bolocam Galactic Plane

  1. Dense Molecular Gas Around Protostars and in Galactic Nuclei European Workshop on Astronomical Molecules 2004

    CERN Document Server

    Baan, W A; Langevelde, H J

    2004-01-01

    The phenomena observed in young stellar objects (YSO), circumstellar regions and extra-galactic nuclei show some similarity in their morphology, dynamical and physical processes, though they may differ in scale and energy. The European Workshop on Astronomical Molecules 2004 gave astronomers a unique opportunity to discuss the links among the observational results and to generate common interpretations of the phenomena in stars and galaxies, using the available diagnostic tools such as masers and dense molecular gas. Their theoretical understanding involves physics, numerical simulations and chemistry. Including a dozen introductory reviews, topics of papers in this book also cover: maser and dense gas diagnostics and related phenomena, evolution of circumstellar regions around protostars, evolution of circumnuclear regions of active galaxies, diagnostics of the circumnuclear gas in stars and galactic nuclei. This book summarizes our present knowledge in these topics, highlights major problems to be addressed...

  2. Diffusion constant in hot and dense hadronic matter. A hadro-molecular-dynamic calculation

    International Nuclear Information System (INIS)

    Sasaki, N.; Miyamura, O.; Muroya, S.; Nonaka, C.

    2002-01-01

    We evaluate baryon/charge diffusion constant of dense and hot hadronic matter based on the molecular dynamical method by using a hadronic collision generator which describes nuclear collisions at energies 10 1-2 GeV/A and satisfies detailed balance at low temperatures (T ≤ 200 MeV). For the hot and dense hadronic matter of the temperature range, T = 100 - 200 MeV and baryon number density, n B =0.16 fm -3 - 0.32 fm -3 , charge diffusion constant D gradually increases from 0.5 fmc to 2 fmc with temperature and is almost independent of baryon number density. Based on the obtained diffusion constant we make simple discussions on the diffusion of charge fluctuation in ultrarelativistic nuclear collisions. (author)

  3. Equation of state and transport properties of warm dense helium via quantum molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhi-Guo [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Cheng, Yan [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, Qi-Feng, E-mail: chenqf01@gmail.com, E-mail: xrchen@scu.edu.cn [National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China); Chen, Xiang-Rong, E-mail: chenqf01@gmail.com, E-mail: xrchen@scu.edu.cn [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2016-05-15

    The equation of state, self-diffusion, and viscosity coefficients of helium have been investigated by quantum molecular dynamics (QMD) simulations in the warm dense matter regime. Our simulations are validated through the comparison with the reliable experimental data. The calculated principal and reshock Hugoniots of liquid helium are in good agreement with the gas-gun data. On this basis, we revisit the issue for helium, i.e., the possibility of the instabilities predicted by chemical models at around 2000 GPa and 10 g/cm{sup 3} along the pressure isotherms of 6309, 15 849, and 31 623 K. Our calculations show no indications of instability in this pressure-temperature region, which reconfirm the predictions of previous QMD simulations. The self-diffusion and viscosity coefficients of warm dense helium have been systematically investigated by the QMD simulations. We carefully test the finite-size effects and convergences of statistics, and obtain numerically converged self-diffusion and viscosity coefficients by using the Kubo-Green formulas. The present results have been used to evaluate the existing one component plasma models. Finally, the validation of the Stokes-Einstein relationship for helium in the warm dense regime is discussed.

  4. Testing the universality of the star-formation efficiency in dense molecular gas

    Science.gov (United States)

    Shimajiri, Y.; André, Ph.; Braine, J.; Könyves, V.; Schneider, N.; Bontemps, S.; Ladjelate, B.; Roy, A.; Gao, Y.; Chen, H.

    2017-08-01

    Context. Recent studies with, for example, Spitzer and Herschel have suggested that star formation in dense molecular gas may be governed by essentially the same "law" in Galactic clouds and external galaxies. This conclusion remains controversial, however, in large part because different tracers have been used to probe the mass of dense molecular gas in Galactic and extragalactic studies. Aims: We aimed to calibrate the HCN and HCO+ lines commonly used as dense gas tracers in extragalactic studies and to test the possible universality of the star-formation efficiency in dense gas (≳104 cm-3), SFEdense. Methods: We conducted wide-field mapping of the Aquila, Ophiuchus, and Orion B clouds at 0.04 pc resolution in the J = 1 - 0 transition of HCN, HCO+, and their isotopomers. For each cloud, we derived a reference estimate of the dense gas mass MHerschelAV > 8, as well as the strength of the local far-ultraviolet (FUV) radiation field, using Herschel Gould Belt survey data products, and estimated the star-formation rate from direct counting of the number of Spitzer young stellar objects. Results: The H13CO+(1-0) and H13CN(1-0) lines were observed to be good tracers of the dense star-forming filaments detected with Herschel. Comparing the luminosities LHCN and LHCO+ measured in the HCN and HCO+ lines with the reference masses MHerschelAV > 8, the empirical conversion factors αHerschel - HCN (=MHerschelAV > 8/LHCN) and αHerschel - HCO+ (=MHerschelAV > 8/LHCO+) were found to be significantly anti-correlated with the local FUV strength. In agreement with a recent independent study of Orion B by Pety et al., the HCN and HCO+ lines were found to trace gas down to AV ≳ 2. As a result, published extragalactic HCN studies must be tracing all of the moderate density gas down to nH2 ≲ 103 cm-3. Estimating the contribution of this moderate density gas from the typical column density probability distribution functions in nearby clouds, we obtained the following G0

  5. The Effect of an Inert Solid Reservoir on Molecular Abundances in Dense Interstellar Clouds

    Directory of Open Access Journals (Sweden)

    Kalvāns Juris

    2012-12-01

    Full Text Available The question, what is the role of freeze-out of chemical species in determining the molecular abundances in the interstellar gas is a matter of debate. We investigate a theoretical case of a dense interstellar molecular cloud core by time-dependent modeling of chemical kinetics, where grain surface reactions deliberately are not included. That means, the gas-phase and solid-phase abundances are influenced only by gas reactions, accretion on grains and desorption. We compare the results to a reference model where no accretion occurs, and only gas-phase reactions are included. We can trace that the purely physical processes of molecule accretion and desorption have major chemical consequences on the gas-phase chemistry. The main effect of introduction of the gas-grain interaction is long-term molecule abundance changes that come nowhere near an equilibrium during the typical lifetime of a prestellar core.

  6. The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120–5453

    Energy Technology Data Exchange (ETDEWEB)

    Privon, G. C.; Treister, E. [Instituto de Astrofśica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Aalto, S.; Falstad, N.; Muller, S.; Costagliola, F. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 94 Onsala (Sweden); González-Alfonso, E. [Universidad de Alcalá, Departamento de Física y Matemáticas, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Sliwa, K. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Armus, L. [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA, 91125 (United States); Evans, A. S. [Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States); Garcia-Burillo, S. [Observatorio de Madrid, OAN-IGN, Alfonso XII, 3, E-28014-Madrid (Spain); Izumi, T. [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Sakamoto, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, 10617, Taipei, Taiwan (China); Werf, P. van der [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Chu, J. K. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2017-02-01

    We present new Atacama Large Millimeter/submillimeter Array Band 7 (∼340 GHz) observations of the dense gas tracers HCN, HCO{sup +}, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120–5453. We find centrally enhanced HCN (4–3) emission, relative to HCO{sup +} (4–3), but do not find evidence for radiative pumping of HCN. Considering the size of the starburst (0.5 kpc) and the estimated supernovae rate of ∼1.2 yr{sup −1}, the high HCN/HCO{sup +} ratio can be explained by an enhanced HCN abundance as a result of mechanical heating by the supernovae, though the active galactic nucleus and winds may also contribute additional mechanical heating. The starburst size implies a high Σ{sub IR} of 4.7 × 10{sup 12} L {sub ⊙} kpc{sup −2}, slightly below predictions of radiation-pressure limited starbursts. The HCN line profile has low-level wings, which we tentatively interpret as evidence for outflowing dense molecular gas. However, the dense molecular outflow seen in the HCN line wings is unlikely to escape the Galaxy and is destined to return to the nucleus and fuel future star formation. We also present modeling of Herschel observations of the H{sub 2}O lines and find a nuclear dust temperature of ∼40 K. IRAS 13120–5453 has a lower dust temperature and Σ{sub IR} than is inferred for the systems termed “compact obscured nuclei (CONs)” (such as Arp 220 and Mrk 231). If IRAS 13120–5453 has undergone a CON phase, we are likely witnessing it at a time when the feedback has already inflated the nuclear ISM and diluted star formation in the starburst/active galactic nucleus core.

  7. Penetration of Cosmic Rays into Dense Molecular Clouds: Role of Diffuse Envelopes

    Science.gov (United States)

    Ivlev, A. V.; Dogiel, V. A.; Chernyshov, D. O.; Caselli, P.; Ko, C.-M.; Cheng, K. S.

    2018-03-01

    A flux of cosmic rays (CRs) propagating through a diffuse ionized gas can excite MHD waves, thus generating magnetic disturbances. We propose a generic model of CR penetration into molecular clouds through their diffuse envelopes, and identify the leading physical processes controlling their transport on the way from a highly ionized interstellar medium to the dense interior of the cloud. The model allows us to describe a transition between a free streaming of CRs and their diffusive propagation, determined by the scattering on the self-generated disturbances. A self-consistent set of equations, governing the diffusive transport regime in an envelope and the MHD turbulence generated by the modulated CR flux, is characterized by two dimensionless numbers. We demonstrate a remarkable mutual complementarity of different mechanisms leading to the onset of the diffusive regime, which results in a universal energy spectrum of the modulated CRs. In conclusion, we briefly discuss implications of our results for several fundamental astrophysical problems, such as the spatial distribution of CRs in the Galaxy as well as the ionization, heating, and chemistry in dense molecular clouds. This paper is dedicated to the memory of Prof. Vadim Tsytovich.

  8. Further studies of the role of dense molecular clouds around outflow sources

    International Nuclear Information System (INIS)

    Verdes-Montenegro, L.; Torrelles, J.M.; Rodriguez, L.F.; Anglada, G.; Lopez, R.

    1989-01-01

    The (J,K) = (1,1) and (2,2) ammonia inversion transitions toward six regions with active star formation and evidence of gas outflows have been observed. Ammonia emission has been detected and mapped in five of these regions: AFGL 5142, AFGL 5157, AFGL 6366S, HHL 73, and S140N. NH3 (2,2) emission was detected toward the peak of the NH3 (1,1) core of AFGL 5157 and S140N. A rotational temperature of T(R) (2,2;1,1) = about 16 K was estimated for the two regions. Two new H2O masers of intense emission, S(nu) greater or equal 40 Jy, were detected toward the ammonia cores of AFGL 5142 and AFGL 5157. It is clear that the dense NH3 gas is closely associated with the star formation activities, since the ammonia cores in all peak close to the centers of activity. In particular, the AFGL 5157 ammonia condensation coincides with the geometrical center of a bipolar molecular outflow, suggesting that the exciting source is embedded in the ammonia core. In contrast, the molecular outflow in the AFGL 6366S region is located at the southeast edge of the NH3 condensation, suggesting that the exciting source is outside the ammonia core and that the morphology of the outflow may be influenced by the interaction with the dense ambient gas. 52 refs

  9. A glimpse of fluid turbulence from the molecular scale

    KAUST Repository

    Komatsu, Teruhisa S.; Matsumoto, Shigenori; Shimada, Takashi; Ito, Nobuyasu

    2014-01-01

    . The energy spectrum of the fluid components is observed to scale reasonably well according to Kolmogorov scaling determined from the energy dissipation rate and the viscosity of the fluid, even though the Kolmogorov length is of the order of the molecular

  10. Computational fluid dynamics for dense gas-solid fluidized beds: a multi-scale modeling strategy

    NARCIS (Netherlands)

    Hoef, van der M.A.; Sint Annaland, van M.; Kuipers, J.A.M.

    2005-01-01

    Dense gas-particle flows are encountered in a variety of industrially important processes for large scale production of fuels, fertilizers and base chemicals. The scale-up of these processes is often problematic and is related to the intrinsic complexities of these flows which are unfortunately not

  11. Computational fluid dynamics for dense gas-solid fluidized beds: a multi-scale modeling strategy

    NARCIS (Netherlands)

    van der Hoef, Martin Anton; van Sint Annaland, M.; Kuipers, J.A.M.

    2004-01-01

    Dense gas–particle flows are encountered in a variety of industrially important processes for large scale production of fuels, fertilizers and base chemicals. The scale-up of these processes is often problematic, which can be related to the intrinsic complexities of these flows which are

  12. Rainbow particle imaging velocimetry for dense 3D fluid velocity imaging

    KAUST Repository

    Xiong, Jinhui

    2017-07-21

    Despite significant recent progress, dense, time-resolved imaging of complex, non-stationary 3D flow velocities remains an elusive goal. In this work we tackle this problem by extending an established 2D method, Particle Imaging Velocimetry, to three dimensions by encoding depth into color. The encoding is achieved by illuminating the flow volume with a continuum of light planes (a

  13. Validation of a two-fluid model used for the simulation of dense fluidized beds; Validation d`un modele a deux fluides applique a la simulation des lits fluidises denses

    Energy Technology Data Exchange (ETDEWEB)

    Boelle, A.

    1997-02-17

    A two-fluid model applied to the simulation of gas-solid dense fluidized beds is validated on micro scale and on macro scale. Phase coupling is carried out in the momentum and energy transport equation of both phases. The modeling is built on the kinetic theory of granular media in which the gas action has been taken into account in order to get correct expressions of transport coefficients. A description of hydrodynamic interactions between particles in high Stokes number flow is also incorporated in the model. The micro scale validation uses Lagrangian numerical simulations viewed as numerical experiments. The first validation case refers to a gas particle simple shear flow. It allows to validate the competition between two dissipation mechanisms: drag and particle collisions. The second validation case is concerted with sedimenting particles in high Stokes number flow. It allows to validate our approach of hydrodynamic interactions. This last case had led us to develop an original Lagrangian simulation with a two-way coupling between the fluid and the particles. The macro scale validation uses the results of Eulerian simulations of dense fluidized bed. Bed height, particles circulation and spontaneous created bubbles characteristics are studied and compared to experimental measurement, both looking at physical and numerical parameters. (author) 159 refs.

  14. Quantum molecular dynamics of warm dense iron and a five-phase equation of state

    Science.gov (United States)

    Sjostrom, Travis; Crockett, Scott

    2018-05-01

    Through quantum molecular dynamics (QMD), utilizing both Kohn-Sham (orbital-based) and orbital-free density functional theory, we calculate the equation of state of warm dense iron in the density range 7 -30 g/cm 3 and temperatures from 1 to 100 eV. A critical examination of the iron pseudopotential is made, from which we find a significant improvement at high pressure to the previous QMD calculations of Wang et al. [Phys. Rev. E 89, 023101 (2014), 10.1103/PhysRevE.89.023101]. Our results also significantly extend the ranges of density and temperature that were attempted in that prior work. We calculate the shock Hugoniot and find very good agreement with experimental results to pressures over 20 TPa. These results are then incorporated with previous studies to generate a five-phase equation of state for iron.

  15. On the nature of intramolecular vibrational energy transfer in dense molecular environments

    Energy Technology Data Exchange (ETDEWEB)

    Benten, Rebekka S. von [Institut fuer Physikalische Chemie der Universitaet Goettingen, Tammannstrasse 6, D-37077 Goettingen (Germany); Abel, Bernd, E-mail: Bernd.Abel@uni-lepzig.de [Wilhelm-Ostwald-Institut fuer Physikalische und Theoretische Chemie, Universitaet Leipzig, Linne-Strasse 2, D-04103 Leipzig (Germany)

    2010-12-09

    Graphical abstract: Mechanisms of IVR in multi-tiers of intramolecular energy levels in different molecular environments are investigated. - Abstract: Transient femtosecond-IR-pump-UV-absorption probe-spectroscopy has been employed to shed light on the nature of intramolecular vibrational energy transfer (IVR) in dense molecular environments ranging from the diluted gas phase to the liquid. A general feature in our experiments and those of others is that IVR proceeds via multiple timescales if overtones or combination vibrations of high frequency modes are excited. It has been found that collisions enhance IVR if its (slower) timescales can compete with collisions. This enhancement is, however, much more weaker and rather inefficient as opposed to the effect of collisions on intermolecular energy transfer which is well known. In a series of experiments we found that IVR depends not significantly on the average energy transferred in a collision but rather on the number of collisions. The collisions are much less efficient in affecting IVR than VET. We conclude that collision induced broadening of vibrational energy levels reduces the energy gaps and enhances existing couplings between tiers. The present results are an important step forward to rationalize and understand apparently different and not consistent results from different groups on different molecular systems between gas and liquid phases.

  16. MOLECULAR DESIGN OF COLLOIDS IN SUPERCRITICAL FLUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Keith P. Johnston

    2009-04-06

    The environmentally benign, non-toxic, non-flammable fluids water and carbon dioxide (CO2) are the two most abundant and inexpensive solvents on earth. Emulsions of these fluids are of interest in many industrial processes, as well as CO2 sequestration and enhanced oil recovery. Until recently, formation of these emulsions required stabilization with fluorinated surfactants, which are expensive and often not environmentally friendly. In this work we overcame this severe limitation by developing a fundamental understanding of the properties of surfactants the CO2-water interface and using this knowledge to design and characterize emulsions stabilized with either hydrocarbon-based surfactants or nanoparticle stabilizers. We also discovered a new concept of electrostatic stabilization for CO2-based emulsions and colloids. Finally, we were able to translate our earlier work on the synthesis of silicon and germanium nanocrystals and nanowires from high temperatures and pressures to lower temperatures and ambient pressure to make the chemistry much more accessible.

  17. Adsorption of fluids on solid surfaces: A route toward very dense layers

    Energy Technology Data Exchange (ETDEWEB)

    Sartarelli, S.A. [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento, San Miguel (Argentina); Szybisz, L., E-mail: szybisz@tandar.cnea.gov.ar [Laboratorio TANDAR, Departamento de Fisica, Comision Nacional de Energia Atomica, RA-1429 Buenos Aires (Argentina); Departamento de Fiica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, RA-1033 Buenos Aires (Argentina)

    2012-08-15

    Adsorption of Xe on single planar walls is investigated in the frame of a density functional theory. The strength of the adsorbate-substrate attraction is changed by considering surfaces of Cs, Na, Li, and Mg. The behavior is analyzed by varying the temperature T (between the triple point T{sub t} and the critical T{sub c}) and the coverage {Gamma}{sub Script-Small-L }. The obtained adsorption isotherms exhibit a variety of wetting situations. Density profiles are reported. It is shown that for strongly attractive surfaces the adsorbed liquid becomes very dense reaching densities characteristic of solids.

  18. Measurements of Grain Motion in a Dense, Three-Dimensional Granular Fluid

    Science.gov (United States)

    Yang, Xiaoyu; Huan, Chao; Candela, D.; Mair, R. W.; Walsworth, R. L.

    2002-03-01

    We have used NMR to measure the short-time, three-dimensional displacement of grains in a system of mustard seeds vibrated vertically at 15g. The measurements are in the ballistic regime, giving direct access to the granular temperature profile. The data are compared to a recent hydrodynamic theory developed for high density granular flows. We find that the hydrodynamic theory works well for the dense, lower portion of the sample but breaks down near the free surface, where the mean free path becomes long.

  19. Measurement bias of fluid velocity in molecular simulations

    International Nuclear Information System (INIS)

    Tysanner, Martin W.; Garcia, Alejandro L.

    2004-01-01

    In molecular simulations of fluid flow, the measurement of mean fluid velocity is considered to be a straightforward computation, yet there is some ambiguity in its definition. We show that in systems far from equilibrium, such as those with large temperature or velocity gradients, two commonly used definitions give slightly different results. Specifically, a bias can arise when computing the mean fluid velocity by measuring the mean particle velocity in a cell and averaging this mean over samples. We show that this bias comes from the correlation of momentum and density fluctuations in non-equilibrium fluids, obtain an analytical expression for predicting it, and discuss what system characteristics (e.g., number of particles per cell, temperature gradients) reduce or magnify the error. The bias has a physical origin so although we demonstrate it by direct simulation Monte Carlo (DSMC) computations, the same effect will be observed with other particle-based simulation methods, such as molecular dynamics and lattice gases

  20. Physical Properties of Low-Molecular Weight Polydimethylsiloxane Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Christine Cardinal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Graham, Alan [Univ. of Colorado, Denver, CO (United States); Nemer, Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Phinney, Leslie M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Garcia, Robert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stirrup, Emily Kate [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    Physical property measurements including viscosity, density, thermal conductivity, and heat capacity of low-molecular weight polydimethylsiloxane (PDMS) fluids were measured over a wide temperature range (-50°C to 150°C when possible). Properties of blends of 1 cSt and 20 cSt PDMS fluids were also investigated. Uncertainties in the measurements are cited. These measurements will provide greater fidelity predictions of environmental sensing device behavior in hot and cold environments.

  1. KINETIC TEMPERATURES OF THE DENSE GAS CLUMPS IN THE ORION KL MOLECULAR CORE

    International Nuclear Information System (INIS)

    Wang, K.-S.; Kuan, Y.-J.; Liu, S.-Y.; Charnley, Steven B.

    2010-01-01

    High angular-resolution images of the J = 18 K -17 K emission of CH 3 CN in the Orion KL molecular core were observed with the Submillimeter Array (SMA). Our high-resolution observations clearly reveal that CH 3 CN emission originates mainly from the Orion Hot Core and the Compact Ridge, both within ∼15'' of the warm and dense part of Orion KL. The clumpy nature of the molecular gas in Orion KL can also be readily seen from our high-resolution SMA images. In addition, a semi-open cavity-like kinematic structure is evident at the location between the Hot Core and the Compact Ridge. We performed excitation analysis with the 'population diagram' method toward the Hot Core, IRc7, and the northern part of the Compact Ridge. Our results disclose a non-uniform temperature structure on small scales in Orion KL, with a range of temperatures from 190-620 K in the Hot Core. Near the Compact Ridge, the temperatures are found to be 170-280 K. Comparable CH 3 CN fractional abundances of 10 -8 to 10 -7 are found around both in the Hot Core and the Compact Ridge. Such high abundances require that a hot gas phase chemistry, probably involving ammonia released from grain mantles, plays an important role in forming these CH 3 CN molecules.

  2. A comparison between integral equation theory and molecular dynamics simulations of dense, flexible polymer liquids

    International Nuclear Information System (INIS)

    Curro, J.G.; Schweizer, K.S.; Grest, G.S.; Kremer, K.; Corporate Research Science Laboratory, Exxon Research and Engineering Company, Annandale, New Jersey 08801; Institut fur Festkorperforschung der Kernforschungsanlage Julich, D-5170 Julich, Federal Republic of Germany)

    1989-01-01

    Recently we (J.G.C. and K.S.S.) formulated a tractable ''reference interaction site model'' (RISM) integral equation theory of flexible polymer liquids. The purpose of this paper is to compare the results of the theory with recent molecular dynamics simulations (G.S.G. and K.K.) on dense chain liquids of degree of polymerization N=50 and 200. Specific comparisons were made between theory and simulation for the intramolecular structure factor ω(k) and the intermolecular radial distribution function g(r) in the liquid. In particular it was possible to independently test the assumptions inherent in the RISM theory and the additional ideality approximation that was made in the initial application of the theory. This comparison was accomplished by calculating the intermolecular g(r) using the simulated intramolecular structure factor, as well as, ω(k) derived from a freely jointed chain model.The RISM theory results, using the simulated ω(k), were found to be in excellent agreement, over all length scales, with the g(r) from molecular dynamics simulations. The theoretical predictions using the ''ideal'' intramolecular structure factor tended to underestimate g(r) near contact, indicating local intramolecular expansion of the chains. This local expansion can be incorporated into the theory self consistently by including the effects of the ''medium induced'' potential on the intramolecular structure

  3. Rainbow Particle Imaging Velocimetry for Dense 3D Fluid Velocity Imaging

    KAUST Repository

    Xiong, Jinhui

    2017-04-11

    Despite significant recent progress, dense, time-resolved imaging of complex, non-stationary 3D flow velocities remains an elusive goal. In this work we tackle this problem by extending an established 2D method, Particle Imaging Velocimetry, to three dimensions by encoding depth into color. The encoding is achieved by illuminating the flow volume with a continuum of light planes (a “rainbow”), such that each depth corresponds to a specific wavelength of light. A diffractive component in the camera optics ensures that all planes are in focus simultaneously. For reconstruction, we derive an image formation model for recovering stationary 3D particle positions. 3D velocity estimation is achieved with a variant of 3D optical flow that accounts for both physical constraints as well as the rainbow image formation model. We evaluate our method with both simulations and an experimental prototype setup.

  4. A Two-Phase Solid/Fluid Model for Dense Granular Flows Including Dilatancy Effects

    Science.gov (United States)

    Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Narbona-Reina, Gladys

    2015-04-01

    We propose a thin layer depth-averaged two-phase model to describe solid-fluid mixtures such as debris flows. It describes the velocity of the two phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure, that itself modifies the friction within the granular phase (Iverson et al., 2010). The model is derived from a 3D two-phase model proposed by Jackson (2000) based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work (Bouchut et al., 2014). In particular, Pitman and Le replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's equations. We close the mixture equations by a weak compressibility relation involving a critical density, or equivalently a critical pressure. Moreover, we relax one boundary condition, making it possible for the fluid to escape the granular media when compression of the granular mass occurs. Furthermore, we introduce second order terms in the equations making it possible to describe the evolution of the pore fluid pressure in response to the compression/dilatation of the granular mass without prescribing an extra ad-hoc equation for the pore pressure. We prove that the energy balance associated with this Jackson closure is dissipative, as well as its thin layer associated model. We present several numerical tests for the 1D case that are compared to the

  5. Analytic solution of integral equations for molecular fluids

    International Nuclear Information System (INIS)

    Cummings, P.T.

    1984-01-01

    We review some recent progress in the analytic solution of integral equations for molecular fluids. The site-site Ornstein-Zernike (SSOZ) equation with approximate closures appropriate to homonuclear diatomic fluids both with and without attractive dispersion-like interactions has recently been solved in closed form analytically. In this paper, the close relationship between the SSOZ equation for homonuclear dumbells and the usual Ornstein-Zernike (OZ) equation for atomic fluids is carefully elucidated. This relationship is a key motivation for the analytic solutions of the SSOZ equation that have been obtained to date. (author)

  6. DENSE GAS IN MOLECULAR CORES ASSOCIATED WITH PLANCK GALACTIC COLD CLUMPS

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Jinghua; Li, Jin Zeng; Liu, Hong-Li [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Wu, Yuefang; Chen, Ping; Hu, Runjie [Department of Astronomy, Peking University, 100871 Beijing (China); Liu, Tie [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Zhang, Tianwei [Peking University Health Science Center, Xueyuan Road 38th, Haidian District, Beijing 100191 (China); Meng, Fanyi [Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 (Germany); Wang, Ke, E-mail: ywu@pku.edu.cn [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)

    2016-03-20

    We present the first survey of dense gas toward Planck Galactic Cold Clumps (PGCCs). Observations in the J = 1–0 transitions of HCO{sup +} and HCN toward 621 molecular cores associated with PGCCs were performed using the Purple Mountain Observatory’s 13.7 m telescope. Among them, 250 sources were detected, including 230 cores detected in HCO{sup +} and 158 in HCN. Spectra of the J = 1–0 transitions from {sup 12}CO, {sup 13}CO, and C{sup 18}O at the centers of the 250 cores were extracted from previous mapping observations to construct a multi-line data set. The significantly low detection rate of asymmetric double-peaked profiles, together with the good consistency among central velocities of CO, HCO{sup +}, and HCN spectra, suggests that the CO-selected Planck cores are more quiescent than classical star-forming regions. The small difference between line widths of C{sup 18}O and HCN indicates that the inner regions of CO-selected Planck cores are no more turbulent than the exterior. The velocity-integrated intensities and abundances of HCO{sup +} are positively correlated with those of HCN, suggesting that these two species are well coupled and chemically connected. The detected abundances of both HCO{sup +} and HCN are significantly lower than values in other low- to high-mass star-forming regions. The low abundances may be due to beam dilution. On the basis of an inspection of the parameters given in the PGCC catalog, we suggest that there may be about 1000 PGCC objects that have a sufficient reservoir of dense gas to form stars.

  7. Magnetic diffusion and ionization fractions in dense molecular clouds: The role of charged grains

    International Nuclear Information System (INIS)

    Elmegreen, B.G.

    1979-01-01

    The ionization fraction is determined for dense molecular clouds by considering charge exchange, dissociative recombination, radiative recombination, and collisions between grains and charged species. The inclusion of grains tends to lower the ionization fraction for a given cosmic-ray ionization rate zeta and metal depletion delta. The observed values of the ionization fractions in dense cloud cores (i.e., -8 ) are obtained for reasonable values of zeta=10 -17 s -1 and delta=0.1.For temperatures less than 30 K, each grain alternates in charge between -e and 0. The resulting motion of the grains in a self-graviting cloud that contains a magnetic field will be periodic; their response to electromagnetic forces will depend on their instantaneous charge. This complex motion is calculated in order to determine the average viscous force between the grains and the neutral molecules in the cloud. The grain-neutral viscous force combines with the ion-neutral viscous force to regulate the motion of the neutral molecules relative to the magnetic field. The resultant The result neutral drift leads to a diffusion of the magnetic field out of the cloud. The time scale for this diffusion is calculated. Grain-related viscous forces dominate ion-related forces for ionization fractions less than 5 x 10 -8 . The magnetic diffusion time in a self-gravitating cloud that is supported by an internal magnetic field is shown to be at least 10 times larger thanthe free-fall time even when the ionization fraction is much less than 10 -8

  8. Seeing the Forest Through the Trees: The Distribution and Properties of Dense Molecular Gas in the Milky Way Galaxy

    Science.gov (United States)

    Ellsworth-Bowers, Timothy P.

    The Milky Way Galaxy serves as a vast laboratory for studying the dynamics and evolution of the dense interstellar medium and the processes of and surrounding massive star formation. From our vantage point within the Galactic plane, however, it has been extremely difficult to construct a coherent picture of Galactic structure; we cannot see the forest for the trees. The principal difficulties in studying the structure of the Galactic disk have been obscuration by the ubiquitous dust and molecular gas and confusion between objects along a line of sight. Recent technological advances have led to large-scale blind surveys of the Galactic plane at (sub-)millimeter wavelengths, where Galactic dust is generally optically thin, and have opened a new avenue for studying the forest. The Bolocam Galactic Plane Survey (BGPS) observed over 190 deg 2 of the Galactic plane in dust continuum emission near lambda = 1.1 mm, producing a catalog of over 8,000 dense molecular cloud structures across a wide swath of the Galactic disk. Deriving the spatial distribution and physical properties of these objects requires knowledge of distance, a component lacking in the data themselves. This thesis presents a generalized Bayesian probabilistic distance estimation method for dense molecular cloud structures, and demonstrates it with the BGPS data set. Distance probability density functions (DPDFs) are computed from kinematic distance likelihoods (which may be double- peaked for objects in the inner Galaxy) and an expandable suite of prior information to produce a comprehensive tally of our knowledge (and ignorance) of the distances to dense molecular cloud structures. As part of the DPDF formalism, this thesis derives several prior DPDFs for resolving the kinematic distance ambiguity in the inner Galaxy. From the collection of posterior DPDFs, a set of objects with well-constrained distance estimates is produced for deriving Galactic structure and the physical properties of dense molecular

  9. Statistical properties of the dense hydrogen plasma: An ab initio molecular dynamics investigation

    International Nuclear Information System (INIS)

    Kohanoff, J.; Hansen, J.P.

    1995-12-01

    The hydrogen plasma is studied in the very high density (atomic and metallic) regime by extensive ab initio Molecular Dynamics simulations. Protons are treated classically, and electrons in the Born-Oppenheimer framework, within the local density approximation (LDA). Densities and temperatures studied fall within the strong coupling regime of the protons. We address the question of the validity of linear screening, and we find it to yield a reasonably good description up to r s approx. 0.5, but already too crude for r s = 1 (with r s = (3/4πρ) 1/3 the ion sphere radius). Finite-size and Brillouin zone sampling effects in metallic systems are studied and shown to be very delicate also in the fluid (liquid metal) phase. We analyse the low-temperature phase diagram and the melting transition. A remarkably fast decrease of the melting temperature with decreasing density is found, up to a point when it becomes comparable to the Fermi temperature of the protons. The possible vicinity of a triple point bcc-hcp(fcc)- liquid is discussed in the region of r s approx. 1.1 and T approx. 100 - 200K. The fluid phase is studied in detail for several temperatures. Proton-electron correlations show a weak temperature dependence, and proton-proton correlations exhibit a well-defined first coordination shell, thus characterizing fluid H in this regime as an atomic liquid. Diffusion coefficients are compared to the values for the one-component plasma. Vibrational densities of states (VDOS) show a plasmon renormalization due to electron screening, and the presence of a plasmon-coupled single-particle mode up to very high temperatures. Collective modes are studied through dynamical structure factors. In close relationship with the VDOS, the simulations reveal the remarkable persistent of a weakly damped high-frequency ion acoustic mode, even under conditions of strong electron screening. The possibility of using this observation as a diagnostic for the plasma phase transition to the

  10. Molecular Dynamics Simulation of Binary Fluid in a Nanochannel

    International Nuclear Information System (INIS)

    Mullick, Shanta; Ahluwalia, P. K.; Pathania, Y.

    2011-01-01

    This paper presents the results from a molecular dynamics simulation of binary fluid (mixture of argon and krypton) in the nanochannel flow. The computational software LAMMPS is used for carrying out the molecular dynamics simulations. Binary fluids of argon and krypton with varying concentration of atom species were taken for two densities 0.65 and 0.45. The fluid flow takes place between two parallel plates and is bounded by horizontal walls in one direction and periodic boundary conditions are imposed in the other two directions. To drive the flow, a constant force is applied in one direction. Each fluid atom interacts with other fluid atoms and wall atoms through Week-Chandler-Anderson (WCA) potential. The velocity profile has been looked at for three nanochannel widths i.e for 12σ, 14σ and 16σ and also for the different concentration of two species. The velocity profile of the binary fluid predicted by the simulations agrees with the quadratic shape of the analytical solution of a Poiseuille flow in continuum theory.

  11. Quantum molecular dynamics simulations of warm dense lithium hydride: Examination of mixing rules

    International Nuclear Information System (INIS)

    Horner, D. A.; Kress, J. D.; Collins, L. A.

    2008-01-01

    We have performed a systematic study of lithium hydride (LiH) in a density range from half to twice solid for temperatures from 0.5 to 3.0 eV using quantum molecular dynamics (QMD) methods and have tested density and pressure mixing rules for obtaining equations of state and optical properties such as frequency-dependent absorption coefficients and Rosseland mean opacities. The QMD simulations for the full LiH fluid served as a benchmark against which to assess the rules. In general, the mixing rule based on the pressure matching produces superior equations of state and mean opacities for the mixture except at the very lowest temperatures and densities. However, the frequency-dependent absorption coefficients displayed considerable differences in some frequency ranges except at the highest temperatures and densities

  12. Molecular Line Studies of Ballistic Stellar Interlopers Burrowing through Dense Interstellar Clouds

    Science.gov (United States)

    Rosen, Anna; Sahai, R.; Claussen, M.; Morris, M.

    2010-01-01

    When an intermediate-mass star speeds through a dense interstellar cloud at a high velocity, it can produce a cometary or bow shock structure due to the cloud being impacted by the intense stellar wind. This class of objects, recently discovered in an HST imaging survey, has been dubbed "ballistic stellar interlopers" (Sahai et al. 2009). Using the ARO's 12m and SMT 10m millimeter-wave dishes, we have obtained molecular line emission data towards 10 stellar interloper sources, in order to identify and characterize the dense clouds with which the interlopers are interacting. We have made small "on-the-fly" maps in the 12CO (J=2-1) and 13CO (J=2-1) lines for each cloud, and obtained spectra of high-density tracers such as N2H+ (J=3-2), HCO+ (J=3-2), CN(N=2-1), and SO(J=5-4), which probe a range of physical conditions in the interstellar clouds being impacted by the interlopers. The data have been reduced and analyzed, and preliminary estimates of the cloud temperatures (9-22 K) and 13CO optical depths (0.18-0.37) have been made. The maps, which show the emission as a function of radial velocity and spatial offset from the location of the interlopers, have helped us distinguish between the clouds interacting with the interlopers, and those which are unrelated but happen to lie along the line of sight. These data will now enable us to carry out high-resolution mm-wave interferometric observations of the interlopers in the future. This research was performed at JPL under the Minority Education Initiatives program. RS and MM were funded by a Long Term Space Astrophysics award from NASA for this work. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Special thanks goes to John Bieging and Bill Peters of the Arizona Radio Observatory.

  13. Observation of visible emission from the molecular helium ion in the afterglow of a dense helium Z-pinch plasma

    International Nuclear Information System (INIS)

    Tucker, J.E.; Brake, M.L.; Gilgenbach, R.M.

    1986-01-01

    The authors present the results of axial and radial time resolved visible emission spectroscopy from the afterglow of a dense helium Z-pinch. These results show that the visible emissions in the pinch afterglow are dominated by line emissions from molecular helium and He II. Axial spectroscopy measurements show the occurrence of several absorption bands which cannot be identified as molecular or atomic helium nor impurities from the discharge chamber materials. The authors believe that these absorption bands are attributable to the molecular helium ion which is present in the discharge. The molecular ion has been observed by others in low pressure and temperature helium discharges directly by means of mass spectrometry and indirectly by the presence of helium atoms in the 2/sup 3/S state, (the He 2/sup 3/S state is believed to result from molecular helium ion recombination). However, the molecular helium ion has not previously been observed spectroscopically

  14. Large Area, High Resolution N2H+ studies of dense gas in the Perseus and Serpens Molecular Clouds

    Science.gov (United States)

    Storm, Shaye; Mundy, Lee

    2014-07-01

    Star formation in molecular clouds occurs over a wide range of spatial scales and physical densities. Understanding the origin of dense cores thus requires linking the structure and kinematics of gas and dust from cloud to core scales. The CARMA Large Area Star Formation Survey (CLASSy) is a CARMA Key Project that spectrally imaged five diverse regions of the Perseus and Serpens Molecular Clouds in N2H+ (J=1-0), totaling over 800 square arcminutes. The observations have 7’’ angular resolution (~0.01 pc spatial resolution) to probe dense gas down to core scales, and use combined interferometric and single-dish data to fully recover line emission up to parsec scales. CLASSy observations are complete, and this talk will focus on three science results. First, the dense gas in regions with existing star formation has complex hierarchical structure. We present a non-binary dendrogram analysis for all regions and show that dense gas hierarchy correlates with star formation activity. Second, well-resolved velocity information for each dendrogram-identified structure allows a new way of looking at linewidth-size relations in clouds. Specifically, we find that non-thermal line-of-sight velocity dispersion varies weakly with structure size, while rms variation in the centroid velocity increases strongly with structure size. We argue that the typical line-of-sight depth of a cloud can be estimated from these relations, and that our regions have depths that are several times less than their extent on the plane of the sky. This finding is consistent with numerical simulations of molecular cloud turbulence that show that high-density sheets are a generic result. Third, N2H+ is a good tracer of cold, dense gas in filaments; we resolve multiple beams across many filaments, some of which are narrower than 0.1 pc. The centroid velocity fields of several filaments show gradients perpendicular to their major axis, which is a common feature in filaments formed from numerical

  15. Carbon molecular sieve dense film membranes derived from Matrimid® for ethylene/ethane separation

    KAUST Repository

    Rungta, Meha

    2012-04-01

    Development of dense film carbon molecular sieve (CMS) membranes for ethylene/ethane (C 2H 4/C 2H 6) separation is reported. A commercial polyimide, Matrimid®, was pyrolyzed under vacuum and inert argon atmosphere, and the resultant CMS films were characterized using pure C 2H 4 and C 2H 6 permeation at 35 °C, 50 psia feed pressure. The effects on C 2H 4/C 2H 6 separation caused by different final vacuum pyrolysis temperatures from 500 to 800 °C are reported. For all pyrolysis temperatures separation surpassed the estimated \\'upper bound\\' solution processable polymer line for C 2H 4 permeability vs. C 2H 4/C 2H 6 selectivity. C 2H 4 permeability decreased and selectivity increased with increasing pyrolysis temperature until 650-675 °C where an optimum combination of C 2H 4 permeability ∼14-15 Barrer with C 2H 4/C 2H 6 selectivity ∼12 was observed. A modified heating rate protocol for 675 °C showed further increase in permeability with no selectivity loss. CMS films produced from argon pyrolysis showed results comparable to vacuum pyrolysis. Further, mixed gas (63.2 mol% C 2H 4 + 36.8 mol% C 2H 6) permeation showed a slightly lower C 2H 4 permeability with C 2H 4/C 2H 6 selectivity increase rather than a decrease that is often seen with polymers. The high selectivity of these membranes was shown to arise from a high \\'entropic selection\\' indicating that the \\'slimmer\\' ethylene molecule has significant advantage over ethane in passing through the rigid \\'slit-shaped\\' CMS pore structure. © 2011 Elsevier Ltd. All rights reserved.

  16. Insulator-metal transition of fluid molecular hydrogen

    International Nuclear Information System (INIS)

    Ross, M.

    1996-01-01

    Dynamically compressed fluid hydrogen shows evidence for metallization at the relatively low pressure of 140 GPa (1.4 Mbar) while experiments on solid hydrogen made in a diamond-anvil cell have failed to detect any evidence for gap closure up to a pressure of 230 GPa (2.3 Mbar). Two possible mechanisms for metal- liclike resistivity are put forward. The first is that as a consequence of the large thermal disorder in the fluid (kT∼0.2 endash 0.3 eV) short-range molecular interactions lead to band tailing that extends the band edge into the gap, resulting in closure at a lower pressure than in the solid. The second mechanism argues that molecular dissociation creates H atoms that behave similar to n-type donors in a heavily doped semiconductor and undergo a nonmetal-metal Mott-type transition. copyright 1996 The American Physical Society

  17. Dense Molecular Gas and H2O Maser Emission in Galaxies F ...

    Indian Academy of Sciences (India)

    2School of Physics and Telecommunication Engineering, South China Normal University,. Guangzhou 510006, China. ∗ e-mail: jszhang@gzhu.edu.cn. Abstract. Extragalactic H2O masers have been found in dense gas cir- cumstance in off-nuclear star formation regions or within parsecs of. Active Galactic Nuclei (AGNs).

  18. Equation of state of dense plasmas: Orbital-free molecular dynamics as the limit of quantum molecular dynamics for high-Z elements

    Energy Technology Data Exchange (ETDEWEB)

    Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M. [CEA, DAM, DIF, 91297 Arpajon (France)

    2014-10-15

    The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.

  19. Diamonds in dense molecular clouds - A challenge to the standard interstellar medium paradigm

    Science.gov (United States)

    Allamandola, L. J.; Sandford, S. A.; Tielens, A. G. G. M.; Herbst, T. M.

    1993-01-01

    Observations of a newly discovered infrared C-H stretching band indicate that interstellar diamond-like material appears to be characteristic of dense clouds. In sharp contrast, the spectral signature of dust in the diffuse interstellar medium is dominated by -CH2- and -CH3 groups. This dichotomy in the aliphatic organic component between the dense and diffuse media challenges standard assumptions about the processes occurring in, and interactions between, these two media. The ubiquity of this interstellar diamond-like material rules out models for meteoritic diamond formation in unusual circumstellar environments and implies that the formation of the diamond-like material is associated with common interstellar processes or stellar types.

  20. Pressure Enhancement in Confined Fluids: Effect of Molecular Shape and Fluid-Wall Interactions.

    Science.gov (United States)

    Srivastava, Deepti; Santiso, Erik E; Gubbins, Keith E

    2017-10-24

    Recently, several experimental and simulation studies have found that phenomena that normally occur at extremely high pressures in a bulk phase can occur in nanophases confined within porous materials at much lower bulk phase pressures, thus providing an alternative route to study high-pressure phenomena. In this work, we examine the effect on the tangential pressure of varying the molecular shape, strength of the fluid-wall interactions, and pore width, for carbon slit-shaped pores. We find that, for multisite molecules, the presence of additional rotational degrees of freedom leads to unique changes in the shape of the tangential pressure profile, especially in larger pores. We show that, due to the direct relationship between the molecular density and the fluid-wall interactions, the latter have a large impact on the pressure tensor. The molecular shape and pore size have a notable impact on the layering of molecules in the pore, greatly influencing both the shape and scale of the tangential pressure profile.

  1. Application of the RISM theory to Lennard-Jones interaction site molecular fluids

    International Nuclear Information System (INIS)

    Johnson, E.; Hazoume, R.P.

    1979-01-01

    It seems that reference interaction site model (RISM) theory atom--atom distribution functions have been obtained directly from the RISM equations only for fused hard sphere molecular fluids. RISM distribution functions for Lennard-Jones interaction site fluids are presented. Results presented suggest that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids

  2. Molecularly Imprinted Polymers for 5-Fluorouracil Release in Biological Fluids

    Directory of Open Access Journals (Sweden)

    Franco Alhaique

    2007-04-01

    Full Text Available The aim of this work was to investigate the possibility of employing Molecularly Imprinted Polymers (MIPs as a controlled release device for 5-fluorouracil (5-FU in biological fluids, especially gastrointestinal ones, compared to Non Imprinted Polymers (NIPs. MIPs were synthesized using methacrylic acid (MAA as functional monomer and ethylene glycol dimethacrylate (EGDMA as crosslinking agent. The capacity of the polymer to recognize and to bind the template selectively in both organic and aqueous media was evaluated. An in vitro release study was performed both in gastrointestinal and in plasma simulating fluids. The imprinted polymers bound much more 5-Fu than the corresponding non-imprinted ones and showed a controlled/sustained drug release, with MIPs release rate being indeed much more sustained than that obtained from NIPs. These polymers represent a potential valid system for drug delivery and this study indicates that the selective binding characteristic of molecularly imprinted polymers is promising for the preparation of novel controlled release drug dosage form.

  3. Molecular characterization of thymidine kinase mutants of human cells induced by densely ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, A; Little, J B

    1989-04-01

    In order to characterize the nature of mutants induced by densely ionizing radiations at an autosomal locus, the authors have isolated a series of 99 thymidine kinase (tk) mutants of human TK6 lymphoblastoid cells iraadiated with either fast neutrons or accelerated argon ions. Individual muant clones were examined for alterations in their restriction fragment pattern after hybridization with a human cDNA probe for tk. A restriction fragment length polymorphism (RFLP) allowed identification of the active tk allele. Among the neutron-induced mutants, 34/52 exhibited loss of the previously active allele while 6/52 exhibited intragenic rearrangements. Among the argon-induced mutants 27/46 exhibited allele loses and 10/46 showed rearrangements within the tk locus. The remaining mutants had restriction patterns indistinguishable from the TK6 parent. Each of the mutant clones was further examined for structural alterations within the c-erbAl locus which has been localized to chromosome 17q11-q22, at some unknown distance from the human tk locus at chromosome 17q21-q22. A substantial proportion (54%) of tk mutants induced by densely ionizing radiation showed loss of the c-erb locus on the homologous chromosome, suggesting that the mutations involve large-scale genetic changes. (author). 51 refs.; 2 figs.; 6 tabs.

  4. MOLECULAR SIMULATION OF PHASE EQUILIBRIA FOR COMPLEX FLUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Athanassios Z. Panagiotopoulos

    2009-09-09

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  5. Molecular Simulation Of Phase Equilibria For Complex Fluids

    International Nuclear Information System (INIS)

    Panagiotopoulos, Athanassios Z.

    2009-01-01

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  6. Effect of Porous Media and Fluid Properties on Dense Non-Aqueous Phase Liquid Migration and Dilution Mass Flux

    National Research Council Canada - National Science Library

    Totten, Christian T

    2005-01-01

    .... Media grain size and NAPL wettability were varied for relative comparisons. Fluid properties including density differential and interfacial tension between NAPL and water were varied for relative comparisons...

  7. Computational and Experimental Investigations of the Molecular Scale Structure and Dynamics of Gologically Important Fluids and Mineral-Fluid Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, Geoffrey [Alfred Univ., NY (United States)

    2017-04-05

    United States Department of Energy grant DE-FG02-10ER16128, “Computational and Spectroscopic Investigations of the Molecular Scale Structure and Dynamics of Geologically Important Fluids and Mineral-Fluid Interfaces” (Geoffrey M. Bowers, P.I.) focused on developing a molecular-scale understanding of processes that occur in fluids and at solid-fluid interfaces using the combination of spectroscopic, microscopic, and diffraction studies with molecular dynamics computer modeling. The work is intimately tied to the twin proposal at Michigan State University (DOE DE-FG02-08ER15929; same title: R. James Kirkpatrick, P.I. and A. Ozgur Yazaydin, co-P.I.).

  8. TWO MASS DISTRIBUTIONS IN THE L 1641 MOLECULAR CLOUDS: THE HERSCHEL CONNECTION OF DENSE CORES AND FILAMENTS IN ORION A

    International Nuclear Information System (INIS)

    Polychroni, D.; Schisano, E.; Elia, D.; Molinari, S.; Turrini, D.; Rygl, K. L. J.; Benedettini, M.; Busquet, G.; Di Giorgio, A. M.; Pestalozzi, M.; Pezzuto, S.; Roy, A.; André, Ph.; Hennemann, M.; Hill, T.; Könyves, V.; Martin, P.; Di Francesco, J.; Arzoumanian, D.; Bontemps, S.

    2013-01-01

    We present Herschel survey maps of the L 1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of the dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there, is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 M ☉ and drives the shape of the core mass function (CMF) at higher masses, which we fit with a power law of the form dN/dlogM∝M –1.4±0.4 . The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 M ☉ and leads to a flattening of the CMF at masses lower than ∼4 M ☉ . We postulate that this difference between the mass distributions is due to the higher proportion of gas that is available in the filaments, rather than in the diffuse cloud

  9. TWO MASS DISTRIBUTIONS IN THE L 1641 MOLECULAR CLOUDS: THE HERSCHEL CONNECTION OF DENSE CORES AND FILAMENTS IN ORION A

    Energy Technology Data Exchange (ETDEWEB)

    Polychroni, D. [Department of Astrophysics, University of Athens, Astronomy and Mechanics, Faculty of Physics, Panepistimiopolis, 15784 Zografos, Athens (Greece); Schisano, E.; Elia, D.; Molinari, S.; Turrini, D.; Rygl, K. L. J.; Benedettini, M.; Busquet, G.; Di Giorgio, A. M.; Pestalozzi, M.; Pezzuto, S. [Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Roy, A.; André, Ph.; Hennemann, M.; Hill, T.; Könyves, V. [Laboratoire AIM, CEA/IRFU CNRS/INSU Université Paris Diderot, Paris-Saclay, F-91191 Gif-sur-Yvette (France); Martin, P. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Di Francesco, J. [National Research Council Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Arzoumanian, D. [IAS, CNRS (UMR 8617), Université Paris-Sud, Bâtiment 121, F-91400 Orsay (France); Bontemps, S., E-mail: dpolychroni@phys.uoa.gr [Université de Bordeaux, Laboratoire d' Astrophysique de Bordeaux, CNRS/INSU, UMR 5804, BP 89, F-33271, Floirac Cedex (France); and others

    2013-11-10

    We present Herschel survey maps of the L 1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of the dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there, is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 M {sub ☉} and drives the shape of the core mass function (CMF) at higher masses, which we fit with a power law of the form dN/dlogM∝M {sup –1.4±0.4}. The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 M {sub ☉} and leads to a flattening of the CMF at masses lower than ∼4 M {sub ☉}. We postulate that this difference between the mass distributions is due to the higher proportion of gas that is available in the filaments, rather than in the diffuse cloud.

  10. Directly calculated electrical conductivity of hot dense hydrogen from molecular dynamics simulation beyond Kubo-Greenwood formula

    Science.gov (United States)

    Ma, Qian; Kang, Dongdong; Zhao, Zengxiu; Dai, Jiayu

    2018-01-01

    Electrical conductivity of hot dense hydrogen is directly calculated by molecular dynamics simulation with a reduced electron force field method, in which the electrons are represented as Gaussian wave packets with fixed sizes. Here, the temperature is higher than electron Fermi temperature ( T > 300 eV , ρ = 40 g / cc ). The present method can avoid the Coulomb catastrophe and give the limit of electrical conductivity based on the Coulomb interaction. We investigate the effect of ion-electron coupled movements, which is lost in the static method such as density functional theory based Kubo-Greenwood framework. It is found that the ionic dynamics, which contributes to the dynamical electrical microfield and electron-ion collisions, will reduce the conductivity significantly compared with the fixed ion configuration calculations.

  11. Molecular Entropy, Thermal Efficiency, and Designing of Working Fluids for Organic Rankine Cycles

    Science.gov (United States)

    Wang, Jingtao; Zhang, Jin; Chen, Zhiyou

    2012-06-01

    A shortage of fossil energy sources boosts the utilization of renewable energy. Among numerous novel techniques, recovering energy from low-grade heat sources through power generation via organic Rankine cycles (ORCs) is one of the focuses. Properties of working fluids are crucial for the ORC's performance. Many studies have been done to select proper working fluids or to design new working fluids. However, no researcher has systematically investigated the relationship between molecular structures and thermal efficiencies of various working fluids for an ideal ORC. This paper has investigated the interrelations of molecular structures, molecular entropies, and thermal efficiencies of various working fluids for an ideal ORC. By calculating thermal efficiencies and molecular entropies, we find that the molecular entropy is the most appropriate thermophysical property of a working fluid to determine how much energy can be converted into work and how much cannot in a system. Generally speaking, working fluids with low entropies will generally have high thermal efficiency for an ideal ORC. Based on this understanding, the direct interrelations of molecular structures and entropies provide an explicit interrelation between molecular structures and thermal efficiencies, and thus provide an insightful direction for molecular design of novel working fluids for ORCs.

  12. Vertical pneumatic conveying in dilute and dense-phase flows: experimental study of the influence of particle density and diameter on fluid dynamic behavior

    Directory of Open Access Journals (Sweden)

    Narimatsu C.P.

    2001-01-01

    Full Text Available In this work, the effects of particle size and density on the fluid dynamic behavior of vertical gas-solid transport of Group D particles in a 53.4 mm diameter transport tube were studied. For the conditions tested, the experimental curves of pressure gradient versus air velocity presented a minimum pressure gradient point, which is associated with a change in the flow regime from dense to dilute phase. The increases in particle size from 1.00 to 3.68 mm and in density from 935 to 2500 kg/m³ caused an increase in pressure gradient for the dense-phase transport region, but were not relevant in dilute transport. The transition velocity between dense and dilute flow (Umin also increased with increasing particle density and diameter. An empirical equation was fitted for predicting transition air velocity for the transport of glass spheres. Additional experiments, covering a wider range of conditions and particles properties, are still needed to allow the fitting of a generalized equation for prediction of Umin.

  13. Humidity-insensitive water evaporation from molecular complex fluids.

    Science.gov (United States)

    Salmon, Jean-Baptiste; Doumenc, Frédéric; Guerrier, Béatrice

    2017-09-01

    We investigated theoretically water evaporation from concentrated supramolecular mixtures, such as solutions of polymers or amphiphilic molecules, using numerical resolutions of a one-dimensional model based on mass transport equations. Solvent evaporation leads to the formation of a concentrated solute layer at the drying interface, which slows down evaporation in a long-time-scale regime. In this regime, often referred to as the falling rate period, evaporation is dominated by diffusive mass transport within the solution, as already known. However, we demonstrate that, in this regime, the rate of evaporation does not also depend on the ambient humidity for many molecular complex fluids. Using analytical solutions in some limiting cases, we first demonstrate that a sharp decrease of the water chemical activity at high solute concentration leads to evaporation rates which depend weakly on the humidity, as the solute concentration at the drying interface slightly depends on the humidity. However, we also show that a strong decrease of the mutual diffusion coefficient of the solution enhances considerably this effect, leading to nearly independent evaporation rates over a wide range of humidity. The decrease of the mutual diffusion coefficient indeed induces strong concentration gradients at the drying interface, which shield the concentration profiles from humidity variations, except in a very thin region close to the drying interface.

  14. Supercritical fluid molecular spray film deposition and powder formation

    Science.gov (United States)

    Smith, Richard D.

    1986-01-01

    Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. Upon expansion and supersonic interaction with background gases in the low pressure region, any clusters of solvent are broken up and the solvent is vaporized and pumped away. Solute concentration in the solution is varied primarily by varying solution pressure to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solvent clustering and solute nucleation are controlled by manipulating the rate of expansion of the solution and the pressure of the lower pressure region. Solution and low pressure region temperatures are also controlled.

  15. Supercritical fluid molecular spray thin films and fine powders

    Science.gov (United States)

    Smith, Richard D.

    1988-01-01

    Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. The solvent is vaporized and pumped away. Solution pressure is varied to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solution temperature is varied in relation to formation of a two-phase system during expansion to control porosity of the film or powder. A wide variety of film textures and powder shapes are produced of both organic and inorganic compounds. Films are produced with regular textural feature dimensions of 1.0-2.0 .mu.m down to a range of 0.01 to 0.1 .mu.m. Powders are formed in very narrow size distributions, with average sizes in the range of 0.02 to 5 .mu.m.

  16. Shear viscosity for dense plasmas by equilibrium molecular dynamics in asymmetric Yukawa ionic mixtures

    Science.gov (United States)

    Haxhimali, Tomorr; Rudd, Robert E.; Cabot, William H.; Graziani, Frank R.

    2015-11-01

    We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 1025 ions/cc. The motion of 30 000-120 000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We systematically study different mixtures through a series of simulations with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. In the more strongly coupled plasmas, the kinetic theory does not agree well with the MD results. We develop a simple model that interpolates between classical kinetic theories at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated, ranging from moderately weakly coupled to moderately strongly coupled asymmetric plasma mixtures.

  17. Study of shear viscosity for dense plasmas by equilibrium molecular dynamics in asymmetric Yukawa ionic mixtures

    Science.gov (United States)

    Haxhimali, Tomorr; Rudd, Robert; Cabot, William; Graziani, Frank

    2015-11-01

    We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and Inertial Confinement Fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 1025 ions/cc. The motion of 30000-120000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We study different mixtures with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. We introduce a model that interpolates between a screened-plasma kinetic theory at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated. This work was performed under the auspices of the US Dept. of Energy by Lawrence Livermore National Security, LLC under Contract DE-AC52-07NA27344.

  18. Ice Chemistry in Interstellar Dense Molecular Clouds, Protostellar Disks, and Comets

    Science.gov (United States)

    Sandford, Scott A.

    2015-01-01

    Despite the low temperatures (T less than 20K), low pressures, and low molecular densities found in much of the cosmos, considerable chemistry is expected to occur in many astronomical environments. Much of this chemistry happens in icy grain mantles on dust grains and is driven by ionizing radiation. This ionizing radiation breaks chemical bonds of molecules in the ices and creates a host of ions and radicals that can react at the ambient temperature or when the parent ice is subsequently warmed. Experiments that similar these conditions have demonstrated a rich chemistry associated with these environments that leads to a wide variety of organic products. Many of these products are of considerable interest to astrobiology. For example, the irradiation of simple ices has been shown to abiotically produce amino acids, nucleobases, quinones, and amphiphiles, all compounds that play key roles in modern biochemistry. This suggests extraterrestrial chemistry could have played a role in the origin of life on Earth and, by extension, do so on planets in other stellar systems.

  19. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... performed using a 5wt% Pd on activated carbon in custom-designed high pressure autoclaves at 323K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental...

  20. THE BLAST SURVEY OF THE VELA MOLECULAR CLOUD: PHYSICAL PROPERTIES OF THE DENSE CORES IN VELA-D

    International Nuclear Information System (INIS)

    Olmi, Luca; Angles-Alcazar, Daniel; Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Bock, James J.; Chapin, Edward L.; Halpern, Mark; Marsden, Gaelen; De Luca, Massimo; Devlin, Mark J.; Dicker, Simon; Klein, Jeff; Elia, Davide; Fazio, Giovanni G.; Marengo, Massimo; Giannini, Teresa; Lorenzetti, Dario; Gundersen, Joshua O.; Hughes, David H.

    2009-01-01

    The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out a 250, 350, and 500 μm survey of the galactic plane encompassing the Vela Molecular Ridge, with the primary goal of identifying the coldest dense cores possibly associated with the earliest stages of star formation. Here, we present the results from observations of the Vela-D region, covering about 4 deg 2 , in which we find 141 BLAST cores. We exploit existing data taken with the Spitzer MIPS, IRAC, and SEST-SIMBA instruments to constrain their (single-temperature) spectral energy distributions, assuming a dust emissivity index β = 2.0. This combination of data allows us to determine the temperature, luminosity, and mass of each BLAST core, and also enables us to separate starless from protostellar sources. We also analyze the effects that the uncertainties on the derived physical parameters of the individual sources have on the overall physical properties of starless and protostellar cores, and we find that there appear to be a smooth transition from the pre- to the protostellar phase. In particular, for protostellar cores we find a correlation between the MIPS24 flux, associated with the central protostar, and the temperature of the dust envelope. We also find that the core mass function of the Vela-D cores has a slope consistent with other similar (sub)millimeter surveys.

  1. Multi-charge-state molecular dynamics and self-diffusion coefficient in the warm dense matter regime

    Science.gov (United States)

    Fu, Yongsheng; Hou, Yong; Kang, Dongdong; Gao, Cheng; Jin, Fengtao; Yuan, Jianmin

    2018-01-01

    We present a multi-ion molecular dynamics (MIMD) simulation and apply it to calculating the self-diffusion coefficients of ions with different charge-states in the warm dense matter (WDM) regime. First, the method is used for the self-consistent calculation of electron structures of different charge-state ions in the ion sphere, with the ion-sphere radii being determined by the plasma density and the ion charges. The ionic fraction is then obtained by solving the Saha equation, taking account of interactions among different charge-state ions in the system, and ion-ion pair potentials are computed using the modified Gordon-Kim method in the framework of temperature-dependent density functional theory on the basis of the electron structures. Finally, MIMD is used to calculate ionic self-diffusion coefficients from the velocity correlation function according to the Green-Kubo relation. A comparison with the results of the average-atom model shows that different statistical processes will influence the ionic diffusion coefficient in the WDM regime.

  2. Extended application of Kohn-Sham first-principles molecular dynamics method with plane wave approximation at high energy—From cold materials to hot dense plasmas

    International Nuclear Information System (INIS)

    Zhang, Shen; Kang, Wei; Wang, Hongwei; Zhang, Ping; He, X. T.

    2016-01-01

    An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.

  3. Extended application of Kohn-Sham first-principles molecular dynamics method with plane wave approximation at high energy—From cold materials to hot dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shen; Kang, Wei, E-mail: weikang@pku.edu.cn [Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China); Wang, Hongwei [College of Engineering, Peking University, Beijing 100871 (China); Zhang, Ping, E-mail: zhang-ping@iapcm.ac.cn [Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871 (China); LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); He, X. T., E-mail: xthe@iapcm.ac.cn [Center for Applied Physics and Technology, HEDPS, and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2016-04-15

    An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.

  4. Molecular dynamics studies of fluid/oil interfaces for improved oil recovery processes.

    Science.gov (United States)

    de Lara, Lucas S; Michelon, Mateus F; Miranda, Caetano R

    2012-12-20

    In our paper, we study the interface wettability, diffusivity, and molecular orientation between crude oil and different fluids for applications in improved oil recovery (IOR) processes through atomistic molecular dynamics (MD). The salt concentration, temperature, and pressure effects on the physical chemistry properties of different interfaces between IOR agents [brine (H(2)O + % NaCl), CO(2), N(2), and CH(4)] and crude oil have been determined. From the interfacial density profiles, an accumulation of aromatic molecules near the interface has been observed. In the case of brine interfaced with crude oil, our calculations indicate an increase in the interfacial tension with increasing pressure and salt concentration, which favors oil displacement. On the other hand, with the other fluids studied (CO(2), N(2), and CH(4)), the interfacial tension decreases with increasing pressure and temperature. With interfacial tension reduction, an increase in fluid diffusivity in the oil phase is observed. We also studied the molecular orientation properties of the hydrocarbon and fluids molecules in the interface region. We perceived that the molecular orientation could be affected by changes in the interfacial tension and diffusivity of the molecules in the interface region with the increased pressure and temperature: pressure (increasing) → interfacial tension (decreasing) → diffusion (increasing) → molecular ordering. From a molecular point of view, the combination of low interfacial tension and high diffusion of molecules in the oil phase gives the CO(2) molecules unique properties as an IOR fluid compared with other fluids studied here.

  5. Diffusion of Supercritical Fluids through Single-Layer Nanoporous Solids: Theory and Molecular Simulations.

    Science.gov (United States)

    Oulebsir, Fouad; Vermorel, Romain; Galliero, Guillaume

    2018-01-16

    With the advent of graphene material, membranes based on single-layer nanoporous solids appear as promising devices for fluid separation, be it liquid or gaseous mixtures. The design of such architectured porous materials would greatly benefit from accurate models that can predict their transport and separation properties. More specifically, there is no universal understanding of how parameters such as temperature, fluid loading conditions, or the ratio of the pore size to the fluid molecular diameter influence the permeation process. In this study, we address the problem of pure supercritical fluids diffusing through simplified models of single-layer porous materials. Basically, we investigate a toy model that consists of a single-layer lattice of Lennard-Jones interaction sites with a slit gap of controllable width. We performed extensive equilibrium and biased molecular dynamics simulations to document the physical mechanisms involved at the molecular scale. We propose a general constitutive equation for the diffusional transport coefficient derived from classical statistical mechanics and kinetic theory, which can be further simplified in the ideal gas limit. This transport coefficient relates the molecular flux to the fluid density jump across the single-layer membrane. It is found to be proportional to the accessible surface porosity of the single-layer porous solid and to a thermodynamic factor accounting for the inhomogeneity of the fluid close to the pore entrance. Both quantities directly depend on the potential of mean force that results from molecular interactions between solid and fluid atoms. Comparisons with the simulations data show that the kinetic model captures how narrowing the pore size below the fluid molecular diameter lowers dramatically the value of the transport coefficient. Furthermore, we demonstrate that our general constitutive equation allows for a consistent interpretation of the intricate effects of temperature and fluid loading

  6. Molecular and phenotypic adaptation in social insect reproductive fluids

    DEFF Research Database (Denmark)

    Liberti, Joanito

    of sperm competition. The seminal fluid of ants and bees with multiply mated queens are known to have evolved proteins that are able to kill the sperm of rival males, but the identity of the proteins involved has remained poorly understood. I sequenced the seminal fluid proteomes of four fungus-growing ant...... species that span the evolutionary transition from single to multiple queen-mating in the fungus-growing ant phylogeny. I then reconstructed the evolutionary histories of these proteins and identified a number of their functions related to energy production, control of oxidative stress, and proteolysis...

  7. Molecular analysis of pancreatic cyst fluid changes clinical management.

    Science.gov (United States)

    Arner, David M; Corning, Brooke E; Ahmed, Ali M; Ho, Henry C; Weinbaum, Bradley J; Siddiqui, Uzma; Aslanian, Harry; Adams, Reid B; Bauer, Todd W; Wang, Andrew Y; Shami, Vanessa M; Sauer, Bryan G

    2018-01-01

    DNA molecular analysis has been suggested as a tool to evaluate pancreatic cysts. This study assesses whether the addition of DNA molecular analysis alters clinical management. This is a retrospective review of 46 consecutive patients who underwent EUS-FNA of pancreatic cysts with DNA molecular analysis at two major academic institutions. Cases were presented to two pancreaticobiliary surgeons first without and then with DNA molecular analysis data. The primary outcome was the frequency with which clinical management was altered with the addition of DNA molecular analysis. Forty-six patients with a mean age of 62.0 (±13.4) years and mean cyst size of 3.2 (±2.3) cm were included in the study. Cyst carcinoembryonic antigen (CEA) was available in 30 patients and ranged from 0.4 to 15,927 ng/mL. DNA molecular analysis was described as benign in 23 (50%), statistically indolent in 13 (28%), statistically higher risk in 9 (20%), and indeterminate in 1 (2%). Surgeon #1 changed the management in 13/46 cases (28%) and surgeon #2 changed the management in 12/46 cases (26%) with the addition of DNA molecular analysis. When organized by CEA concentration, those with an intermediate CEA (45-800 ng/mL) or without a CEA concentration had a management changed more frequently (40%) compared to all others (P molecular analysis alters the clinical management of pancreatic cystic lesions most often when CEA levels are intermediate (45-800 ng/mL) or when no CEA concentration is available. Use of DNA molecular analysis can be considered in this cohort. Further study of molecular markers in pancreatic cystic lesions is recommended.

  8. Spinodal decomposition in multicomponent fluid mixtures: A molecular dynamics study

    DEFF Research Database (Denmark)

    Laradji, Mohamed; Mouritsen, Ole G.; Toxvaerd, Søren

    1996-01-01

    parameter, leading to large growth-exponent values, the dynamics in multicomponent fluids (p = 3, 4) is found to follow a t(1/3) growth law, where t is time, which we relate to a long-wavelength evaporation-condensation process. These findings, which are proposed to be consequences of the compact domain...

  9. Dense ionic fluids confined in planar capacitors: in- and out-of-plane structure from classical density functional theory

    International Nuclear Information System (INIS)

    Härtel, Andreas; Samin, Sela; Van Roij, René

    2016-01-01

    The ongoing scientific interest in the properties and structure of electric double layers (EDLs) stems from their pivotal role in (super)capacitive energy storage, energy harvesting, and water treatment technologies. Classical density functional theory (DFT) is a promising framework for the study of the in- and out-of-plane structural properties of double layers. Supported by molecular dynamics simulations, we demonstrate the adequate performance of DFT for analyzing charge layering in the EDL perpendicular to the electrodes. We discuss charge storage and capacitance of the EDL and the impact of screening due to dielectric solvents. We further calculate, for the first time, the in-plane structure of the EDL within the framework of DFT. While our out-of-plane results already hint at structural in-plane transitions inside the EDL, which have been observed recently in simulations and experiments, our DFT approach performs poorly in predicting in-plane structure in comparison to simulations. However, our findings isolate fundamental issues in the theoretical description of the EDL within the primitive model and point towards limitations in the performance of DFT in describing the out-of-plane structure of the EDL at high concentrations and potentials. (paper)

  10. Sensitivity analysis of molecular design problem for the development of novel working fluids for power cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    . Multi-criteria database search and Computer Aided Molecular Design (CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance [1]. The problem formulation for the development of novel working fluids...... a certain working fluid property parameter on the performance of the power cycle, i.e. the net power output, can facilitate the identification key properties for working fluids. In that sense a sensitivity analysis of the different parameters is suggested in this work as a systematic method to efficiently...... technology to convert such waste heat sources into usable energy. So far the low-temperature heat is not utilized efficiently for electricity generation. To optimize the heat transfer process and the power generation, the influence of the working fluid, the cycle designs and the operating conditions is vital...

  11. Generalized extended Navier-Stokes theory: correlations in molecular fluids with intrinsic angular momentum.

    Science.gov (United States)

    Hansen, J S; Daivis, Peter J; Dyre, Jeppe C; Todd, B D; Bruus, Henrik

    2013-01-21

    The extended Navier-Stokes theory accounts for the coupling between the translational and rotational molecular degrees of freedom. In this paper, we generalize this theory to non-zero frequencies and wavevectors, which enables a new study of spatio-temporal correlation phenomena present in molecular fluids. To discuss these phenomena in detail, molecular dynamics simulations of molecular chlorine are performed for three different state points. In general, the theory captures the behavior for small wavevector and frequencies as expected. For example, in the hydrodynamic regime and for molecular fluids with small moment of inertia like chlorine, the theory predicts that the longitudinal and transverse intrinsic angular velocity correlation functions are almost identical, which is also seen in the molecular dynamics simulations. However, the theory fails at large wavevector and frequencies. To account for the correlations at these scales, we derive a phenomenological expression for the frequency dependent rotational viscosity and wavevector and frequency dependent longitudinal spin viscosity. From this we observe a significant coupling enhancement between the molecular angular velocity and translational velocity for large frequencies in the gas phase; this is not observed for the supercritical fluid and liquid state points.

  12. The density functional theory and the charged fluid molecular dynamics

    International Nuclear Information System (INIS)

    Hansen, J.P.; Zerah, G.

    1993-01-01

    Car and Parrinello had the idea of combining the density functional theory (Hohenberg, Kohn and Sham) to the 'molecular dynamics' numerical modelling method, in order to simulate metallic or co-valent solids and liquids from the first principles. The objective of this paper is to present a simplified version of this method ab initio, applicable to classical and quantal charged systems. The method is illustrated with recent results on charged colloidal suspensions and highly correlated electron-proton plasmas. 1 fig., 21 refs

  13. High-Resolution Imaging of Dense Gas Structure and Kinematics in Nearby Molecular Clouds with the CARMA Large Area Star Formation Survey

    Science.gov (United States)

    Storm, Shaye

    This thesis utilizes new observations of dense gas in molecular clouds to develop an empirical framework for how clouds form structures which evolve into young cores and stars. Previous observations show the general turbulent and hierarchical nature of clouds. However, current understanding of the star formation pathway is limited by existing data that do not combine angular resolution needed to resolve individual cores with area coverage required to capture entire star-forming regions and with tracers that can resolve gas motions. The original contributions of this thesis to astrophysical research are the creation and analysis of the largest-area high-angular-resolution maps of dense gas in molecular clouds to-date, and the development of a non-binary dendrogram algorithm to quantify the hierarchical nature and three-dimensional morphology of cloud structure. I first describe the CARMA Large Area Star Formation Survey, which provides spectrally imaged N2H+, HCO+, and HCN (J = 1→0) emission across diverse regions of the Perseus and Serpens Molecular Clouds. I then present a detailed analysis of the Barnard 1 and L1451 regions in Perseus. A non-binary dendrogram analysis of Barnard 1 N2H emission and all L1451 emission shows that the most hierarchically complex gas corresponds with sub-regions actively forming young stars. I estimate the typical depth of molecular emission in each region using the spatial and kinematic properties of dendrogram-identified structures. Barnard 1 appears to be a sheet-like region at the largest scales with filamentary substructure, while the L1451 region is composed of more spatially distinct ellipsoidal structures. I then do a uniform comparison of the hierarchical structure and young stellar content of all five regions. The more evolved regions with the most young stellar objects (YSOs) and strongest emission have formed the most hierarchical levels. However, all regions show similar mean branching properties at each level

  14. Obstructive renal injury: from fluid mechanics to molecular cell biology.

    Science.gov (United States)

    Ucero, Alvaro C; Gonçalves, Sara; Benito-Martin, Alberto; Santamaría, Beatriz; Ramos, Adrian M; Berzal, Sergio; Ruiz-Ortega, Marta; Egido, Jesus; Ortiz, Alberto

    2010-04-22

    Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making.

  15. Molecular simulation studies on thermophysical properties with application to working fluids

    CERN Document Server

    Raabe, Gabriele

    2017-01-01

    This book discusses the fundamentals of molecular simulation, starting with the basics of statistical mechanics and providing introductions to Monte Carlo and molecular dynamics simulation techniques. It also offers an overview of force-field models for molecular simulations and their parameterization, with a discussion of specific aspects. The book then summarizes the available know-how for analyzing molecular simulation outputs to derive information on thermophysical and structural properties. Both the force-field modeling and the analysis of simulation outputs are illustrated by various examples. Simulation studies on recently introduced HFO compounds as working fluids for different technical applications demonstrate the value of molecular simulations in providing predictions for poorly understood compounds and gaining a molecular-level understanding of their properties. This book will prove a valuable resource to researchers and students alike.

  16. Fluctuating hydrodynamics for multiscale modeling and simulation: energy and heat transfer in molecular fluids.

    Science.gov (United States)

    Shang, Barry Z; Voulgarakis, Nikolaos K; Chu, Jhih-Wei

    2012-07-28

    This work illustrates that fluctuating hydrodynamics (FHD) simulations can be used to capture the thermodynamic and hydrodynamic responses of molecular fluids at the nanoscale, including those associated with energy and heat transfer. Using all-atom molecular dynamics (MD) trajectories as the reference data, the atomistic coordinates of each snapshot are mapped onto mass, momentum, and energy density fields on Eulerian grids to generate a corresponding field trajectory. The molecular length-scale associated with finite molecule size is explicitly imposed during this coarse-graining by requiring that the variances of density fields scale inversely with the grid volume. From the fluctuations of field variables, the response functions and transport coefficients encoded in the all-atom MD trajectory are computed. By using the extracted fluid properties in FHD simulations, we show that the fluctuations and relaxation of hydrodynamic fields quantitatively match with those observed in the reference all-atom MD trajectory, hence establishing compatibility between the atomistic and field representations. We also show that inclusion of energy transfer in the FHD equations can more accurately capture the thermodynamic and hydrodynamic responses of molecular fluids. The results indicate that the proposed MD-to-FHD mapping with explicit consideration of finite molecule size provides a robust framework for coarse-graining the solution phase of complex molecular systems.

  17. THE BOLOCAM GALACTIC PLANE SURVEY. XII. DISTANCE CATALOG EXPANSION USING KINEMATIC ISOLATION OF DENSE MOLECULAR CLOUD STRUCTURES WITH {sup 13}CO(1-0)

    Energy Technology Data Exchange (ETDEWEB)

    Ellsworth-Bowers, Timothy P.; Glenn, Jason [CASA, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Rosolowsky, Erik [Department of Physics, 4-183 CCIS, University of Alberta, Edmonton, AB T6G 2E1 (Canada); Ginsburg, Adam [European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München (Germany); Evans II, Neal J. [Department of Astronomy, University of Texas, 2515 Speedway, Stop C1400, Austin, TX 78712 (United States); Battersby, Cara [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Shirley, Yancy L.; Svoboda, Brian, E-mail: timothy.ellsworthbowers@colorado.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2015-01-20

    We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO{sup +}(3-2), NH{sub 3}(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) {sup 13}CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region of the GRS {sup 13}CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of {sup 13}CO matched to the BGPS source. For objects with a HCO{sup +}(3-2) velocity, ≈95% of the new {sup 13}CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties ≲ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.

  18. The description of dense hydrogen with Wave Packet Molecular Dynamics (WPMD) simulations; Die Beschreibung von dichtem Wasserstoff mit der Methode der Wellenpaket-Molekulardynamik (WPMD)

    Energy Technology Data Exchange (ETDEWEB)

    Jakob, B.

    2006-10-10

    In this work the wave packet molecular dynamics (WPMD) is presented and applied to dense hydrogen. In the WPMD method the electrons are described by a slater determinant of periodic Gaussian wave packets. Each single particle wave function can parametrised through 8 coordinates which can be interpreted as the position and momentum, the width and its conjugate momentum. The equation of motion for these coordinates can be derived from a time depended variational principle. Properties of the equilibrium can be ascertained by a Monte Carlo simulation. With the now completely implemented antisymmetrisation the simulation yields a fundamental different behavior for dense hydrogen compare to earlier simplified models. The results show a phase transition to metallic hydrogen with a higher density than in the molecular phase. This behavior has e.g. a large implication to the physics of giant planets. This work describes the used model and explains in particular the calculation of the energy and forces. The periodicity of the wave function leads to a description in the Fourier space. The antisymmetrisation is done by Matrix operations. Moreover the numerical implementation is described in detail to allow the further development of the code. The results provided in this work show the equation of state in the temperature range 300K - 50000K an density 10{sup 23}-10{sup 24} cm{sup -3}, according a pressure 1 GPa-1000 GPa. In a phase diagram the phase transition to metallic hydrogen can be red off. The electrical conductivity of both phases is destined. (orig.)

  19. ALMA 0.1–0.2 arcsec resolution imaging of the NGC 1068 Nucleus: compact dense molecular gas emission at the putative AGN location

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2016-05-01

    We present the results of our ALMA Cycle 2 high angular resolution (0.″1–0.″2) observations of the nuclear region of the nearby well-studied type-2 active galactic nucleus (AGN), NGC 1068, at HCN J = 3–2 and HCO{sup +} J = 3–2 emission lines. For the first time, due to a higher angular resolution than previous studies, we clearly detected dense molecular gas emission at the putative AGN location, identified as a ∼1.1 mm (∼266 GHz) continuum emission peak, by separating this emission from brighter emission located at 0.″5–2.″0 on the eastern and western sides of the AGN. The estimated intrinsic molecular emission size and dense molecular mass, which are thought to be associated with the putative dusty molecular torus around an AGN, were ∼10 pc and ∼several × 10{sup 5} M {sub ⊙}, respectively. HCN-to-HCO{sup +} J = 3–2 flux ratios substantially higher than unity were found throughout the nuclear region of NGC 1068. The continuum emission displayed an elongated morphology along the direction of the radio jet located at the northern side of the AGN, as well as a weak spatially-resolved component at ∼2.″0 on the southwestern side of the AGN. The latter component most likely originated from star formation, with the estimated luminosity more than one order of magnitude lower than the luminosity of the central AGN. No vibrationally excited ( v {sub 2} = 1f) J = 3–2 emission lines were detected for HCN and HCO{sup +} across the field of view.

  20. Electron scattering in dense atomic and molecular gases: An empirical correlation of polarizability and electron scattering length

    International Nuclear Information System (INIS)

    Rupnik, K.; Asaf, U.; McGlynn, S.P.

    1990-01-01

    A linear correlation exists between the electron scattering length, as measured by a pressure shift method, and the polarizabilities for He, Ne, Ar, Kr, and Xe gases. The correlative algorithm has excellent predictive capability for the electron scattering lengths of mixtures of rare gases, simple molecular gases such as H 2 and N 2 and even complex molecular entities such as methane, CH 4

  1. Coexistence of monatomic and diatomic molecular fluid character in liquid gallium

    Energy Technology Data Exchange (ETDEWEB)

    Gong, X.G. (International Centre for Theoretical Physics (ICTP), Trieste (Italy)); Chiarotti, G.L. (International School for Advanced Studies (SISSA), Trieste (Italy) Lab. Tecnologie Avanzate Superfici e Catalisi (TASC), Consorzio Interuniv. Nazionale per la Fisica della Materia (INFM), Trieste (Italy)); Parrinello, M. (IBM Research Div., Zurich Forschungslab., Rueschlikon (Switzerland) International School for Advanced Studies (SISSA), Trieste (Italy)); Tosatti, E. (International School for Advanced Studies (SISSA), Trieste (Italy) International Centre for Theoretical Physics (ICTP), Trieste (Italy) IBM Research Div., Zurich Forschungslab., Rueschlikon (Switzerland))

    1993-02-01

    We have performed an ab initio molecular-dynamics simulation of liquid Ga at high temperature (1000 K). Our results are in good agreement with scattering data and with Knight-shift experiments. A remarkable feature of our findings is the coexistence in the liquid state of metallic and covalent characters. Covalency manifests itself in the appearance of very short-lived Ga-Ga bonds, which represent remnants in the liquid of the crystalline form [alpha]-Ga. We set up a two-fluid scheme which can be used for the analysis of fluids where metallic and covalent characters coexist. (orig.).

  2. Coexistence of monatomic and diatomic molecular fluid character in liquid gallium

    International Nuclear Information System (INIS)

    Gong, X.G.; Chiarotti, G.L.; Parrinello, M.; Tosatti, E.

    1993-01-01

    We have performed an ab initio molecular-dynamics simulation of liquid Ga at high temperature (1000 K). Our results are in good agreement with scattering data and with Knight-shift experiments. A remarkable feature of our findings is the coexistence in the liquid state of metallic and covalent characters. Covalency manifests itself in the appearance of very short-lived Ga-Ga bonds, which represent remnants in the liquid of the crystalline form α-Ga. We set up a two-fluid scheme which can be used for the analysis of fluids where metallic and covalent characters coexist. (orig.)

  3. Self-diffusion in monodisperse three-dimensional magnetic fluids by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dobroserdova, A.B. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Kantorovich, S.S., E-mail: alla.dobroserdova@urfu.ru [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

    2017-06-01

    In the present work we study the self-diffusion behaviour in the three-dimensional monodisperse magnetic fluids using the Molecular Dynamics Simulation and Density Functional Theory. The peculiarity of computer simulation is to study two different systems: dipolar and soft sphere ones. In the theoretical method, it is important to choose the approximation for the main structures, which are chains. We compare the theoretical results and the computer simulation data for the self-diffusion coefficient as a function of the particle volume fraction and magnetic dipole-dipole interaction parameter and find the qualitative and quantitative agreement to be good. - Highlights: • The paper deals with the study of the self-diffusion in monodisperse three-dimensional magnetic fluids. • The theoretical approach contains the free energy density functional minimization. • Computer simulations are performed by the molecular dynamics method. • We have a good qualitative and quantitative agreement between the theoretical results and computer simulation data.

  4. Towards the design of new and improved drilling fluid additives using molecular dynamics simulations

    International Nuclear Information System (INIS)

    Anderson, Richard L.; Greenwel, H. Christopher; Suter, James L.; Coveney, Peter V.; Jarvis, Rebecca M.

    2010-01-01

    During exploration for oil and gas, a technical drilling fluid is used to lubricate the drill bit, maintain hydrostatic pressure, transmit sensor readings, remove rock cuttings and inhibit swelling of unstable clay based reactive shale formations. Increasing environmental awareness and resulting legislation has led to the search for new, improved biodegradable drilling fluid components. In the case of additives for clay swelling inhibition, an understanding of how existing effective additives interact with clays must be gained to allow the design of improved molecules. Owing to the disordered nature and nano scope dimension of the interlayer pores of clay minerals, computer simulations have become an increasingly useful tool for studying clay-swelling inhibitor interactions. In this work we briefly review the history of the development of technical drilling fluids, the environmental impact of drilling fluids and the use of computer simulations to study the interactions between clay minerals and swelling inhibitors. We report on results from some recent large-scale molecular dynamics simulation studies on low molecular weight water-soluble macromolecular inhibitor molecules. The structure and interactions of poly(propylene oxide)-diamine, poly(ethylene glycol) and poly(ethylene oxide)-diacrylate inhibitor molecules with montmorillonite clay are studied. (author)

  5. A comparison of molecular dynamics and diffuse interface model predictions of Lennard-Jones fluid evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Barbante, Paolo [Dipartimento di Matematica, Politecnico di Milano - Piazza Leonardo da Vinci 32 - 20133 Milano (Italy); Frezzotti, Aldo; Gibelli, Livio [Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano - Via La Masa 34 - 20156 Milano (Italy)

    2014-12-09

    The unsteady evaporation of a thin planar liquid film is studied by molecular dynamics simulations of Lennard-Jones fluid. The obtained results are compared with the predictions of a diffuse interface model in which capillary Korteweg contributions are added to hydrodynamic equations, in order to obtain a unified description of the liquid bulk, liquid-vapor interface and vapor region. Particular care has been taken in constructing a diffuse interface model matching the thermodynamic and transport properties of the Lennard-Jones fluid. The comparison of diffuse interface model and molecular dynamics results shows that, although good agreement is obtained in equilibrium conditions, remarkable deviations of diffuse interface model predictions from the reference molecular dynamics results are observed in the simulation of liquid film evaporation. It is also observed that molecular dynamics results are in good agreement with preliminary results obtained from a composite model which describes the liquid film by a standard hydrodynamic model and the vapor by the Boltzmann equation. The two mathematical model models are connected by kinetic boundary conditions assuming unit evaporation coefficient.

  6. Computational and Spectroscopic Investigations of the Molecular Scale Structure and Dynamics of Geologically Important Fluids and Mineral-Fluid Interfaces

    International Nuclear Information System (INIS)

    Kirkpatrick, R. James; Kalinichev, Andrey G.

    2008-01-01

    Research supported by this grant focuses on molecular scale understanding of central issues related to the structure and dynamics of geochemically important fluids, fluid-mineral interfaces, and confined fluids using computational modeling and experimental methods. Molecular scale knowledge about fluid structure and dynamics, how these are affected by mineral surfaces and molecular-scale (nano-) confinement, and how water molecules and dissolved species interact with surfaces is essential to understanding the fundamental chemistry of a wide range of low-temperature geochemical processes, including sorption and geochemical transport. Our principal efforts are devoted to continued development of relevant computational approaches, application of these approaches to important geochemical questions, relevant NMR and other experimental studies, and application of computational modeling methods to understanding the experimental results. The combination of computational modeling and experimental approaches is proving highly effective in addressing otherwise intractable problems. In 2006-2007 we have significantly advanced in new, highly promising research directions along with completion of on-going projects and final publication of work completed in previous years. New computational directions are focusing on modeling proton exchange reactions in aqueous solutions using ab initio molecular dynamics (AIMD), metadynamics (MTD), and empirical valence bond (EVB) approaches. Proton exchange is critical to understanding the structure, dynamics, and reactivity at mineral-water interfaces and for oxy-ions in solution, but has traditionally been difficult to model with molecular dynamics (MD). Our ultimate objective is to develop this capability, because MD is much less computationally demanding than quantum-chemical approaches. We have also extended our previous MD simulations of metal binding to natural organic matter (NOM) to a much longer time scale (up to 10 ns) for

  7. Cerebrospinal fluid tau levels are a marker for molecular subtype in sporadic Creutzfeldt-Jakob disease.

    Science.gov (United States)

    Karch, André; Hermann, Peter; Ponto, Claudia; Schmitz, Matthias; Arora, Amandeep; Zafar, Saima; Llorens, Franc; Müller-Heine, Annika; Zerr, Inga

    2015-05-01

    The molecular subtype of sporadic Creutzfeldt-Jakob disease (sCJD) is an important prognostic marker for patient survival. However, subtype determination is not possible during lifetime. Because the rate of disease progression is associated with the molecular subtype, this study aimed at investigating if total tau, a marker of neuronal death, allows premortem diagnosis of molecular subtype when codon 129 genotype is known. Two hundred ninety-six sCJD patients were tested for their cerebrospinal fluid total tau level at the time of diagnosis and were investigated for their sCJD subtype postmortem. There was a significant association between tau levels and the prion protein type in patients with codon 129 MM (p disease. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

    International Nuclear Information System (INIS)

    Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh; Aalto, Susanne; Doi, Akihiro; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki; Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi; Krips, Melanie; Martín, Sergio; Meier, David S.; Nakai, Naomasa

    2015-01-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO + (4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO + (4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO + (4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097

  9. ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, Susanne [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-439 94 Onsala (Sweden); Doi, Akihiro [Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara 252-5210 (Japan); Espada, Daniel [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Fathi, Kambiz [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Centre, SE-106 91 Stockholm (Sweden); Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Krips, Melanie; Martín, Sergio [Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d’Hères (France); Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Soccoro, NM 87801 (United States); Nakai, Naomasa, E-mail: takumaizumi@ioa.s.u-tokyo.ac.jp [Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8571 (Japan); and others

    2015-09-20

    We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO{sup +}(4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO{sup +}(4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO{sup +}(4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.

  10. Estimating thermodynamic properties by molecular dynamics simulations: The properties of fluids at high pressures and temperatures

    International Nuclear Information System (INIS)

    Fraser, D.G.; Refson, K.

    1992-01-01

    The molecular dynamics calculations reported above give calculated P-V-T properties for H 2 O up to 1500 K and 100 GPa, which agree remarkably well with the available experimental data. We also observe the phase transition to a crystalline, orientationally disordered cubic ice structure. No account was taken of molecular flexibility in these calculations nor of potential dissociation at high pressures as suggested by Hamman (1981). However, we note that the closest next-nearest-neighbour O-H approach remains significantly greater than the TIP4P fixed O-H bond length within the water molecule for all pressures studied. The equation of state proposed here should be useful for estimating the properties of H 2 O at up to 1500 K and 100 G Pa (1 Mbar) and is much easier to use in practice than modified Redlich Kwong equations. Extension of these methods to the studies of other fluids and of fluid mixtures at high temperatures and pressures will require good potential models for the species involved, and this is likely to involve a combination of good ab initio work and semiempirical modelling. Once developed, these models should allow robust predictions of thermodynamic properties beyond the range of the experimental data on the basis of fundamental molecular information

  11. Cerebrospinal fluid markers in the differentiation of molecular subtypes of sporadic Creutzfeldt-Jakob disease.

    Science.gov (United States)

    Gmitterová, K; Heinemann, U; Krasnianski, A; Gawinecka, J; Zerr, I

    2016-06-01

    Cerebrospinal fluid (CSF) analysis supports the clinical diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) when applied within an adequate clinical context. A diagnostic potential has been attributed to CSF proteins such as 14-3-3, but also tau protein, phosphorylated tau (181P) (p-tau) protein, amyloid β1-42 , S100B and neuron-specific enolase (NSE). There has been only limited information available about the contribution of CSF analysis in the differentiation of various molecular sCJD subtypes. The CSF levels of the aforementioned proteins from 73 sCJD patients with distinct molecular subtypes were determined. Differences in tau values were significant amongst the homozygous patients (MM and VV genotype) compared to the heterozygous group (P = 0.07 and P = 0.02 respectively). Significantly higher CSF tau levels (P = 0.003) and NSE (P = 0.02) but lower p-tau/tau ratio (P = 0.01) were observed in MM1 compared to MM2 patients. The p-tau/tau ratio enabled the differentiation of MV genotype with higher levels in PrP(sc) type 2 (P = 0.04). Elevation of S100B (P disease duration and clinical stage influenced the test sensitivity in all proteins. Cerebrospinal fluid protein levels might be useful in the pre-mortem differentiation of molecular sCJD subtypes when the codon 129 genotype is known. © 2016 EAN.

  12. Generalized extended Navier-Stokes theory: multiscale spin relaxation in molecular fluids.

    Science.gov (United States)

    Hansen, J S

    2013-09-01

    This paper studies the relaxation of the molecular spin angular velocity in the framework of generalized extended Navier-Stokes theory. Using molecular dynamics simulations, it is shown that for uncharged diatomic molecules the relaxation time decreases with increasing molecular moment of inertia per unit mass. In the regime of large moment of inertia the fast relaxation is wave-vector independent and dominated by the coupling between spin and the fluid streaming velocity, whereas for small inertia the relaxation is slow and spin diffusion plays a significant role. The fast wave-vector-independent relaxation is also observed for highly packed systems. The transverse and longitudinal spin modes have, to a good approximation, identical relaxation, indicating that the longitudinal and transverse spin viscosities have same value. The relaxation is also shown to be isomorphic invariant. Finally, the effect of the coupling in the zero frequency and wave-vector limit is quantified by a characteristic length scale; if the system dimension is comparable to this length the coupling must be included into the fluid dynamical description. It is found that the length scale is independent of moment of inertia but dependent on the state point.

  13. Cloud fluid compression and softening in spiral arms and the formation of giant molecular cloud complexes

    International Nuclear Information System (INIS)

    Cowie, L.L.

    1981-01-01

    In this, the second paper of a series on the galactodynamics of the cloudy interstellar medium, we consider the response of such a gas to a forcing potential in the tight-winding density wave theory. The cloud fluid is treated in the hydrodynamic limit with an equation of state which softens at high densities. It is shown that in the inner regions of the galaxy, cooling of the cloud fluid in the arms can result in gravitational instability and the formation of large bound complexes of clouds which we identify with the giant molecular clouds (GMCs). Masses dimensions, distributions, and scale heights of the GMCs are predicted by the theory. It is suggested that the interstellar gas density in the disk is regulated by the gravitational instability mechanism in the arms which siphons material into star formation. Implications for the evolution of individual GMCs and for galactic morphology are discussed

  14. Departure of microscopic friction from macroscopic drag in molecular fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Hanasaki, Itsuo [Institute of Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan); Fujiwara, Daiki; Kawano, Satoyuki, E-mail: kawano@me.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Machikaneyama-cho 1-3, Toyonaka, Osaka 560-8531 (Japan)

    2016-03-07

    Friction coefficient of the Langevin equation and drag of spherical macroscopic objects in steady flow at low Reynolds numbers are usually regarded as equivalent. We show that the microscopic friction can be different from the macroscopic drag when the mass is taken into account for particles with comparable scale to the surrounding fluid molecules. We illustrate it numerically by molecular dynamics simulation of chloride ion in water. Friction variation by the atomistic mass effect beyond the Langevin regime can be of use in the drag reduction technology as well as the electro or thermophoresis.

  15. Crystallisation of a Lennard-Jones fluid by large scale molecular dynamics simulation

    International Nuclear Information System (INIS)

    Snook, I.

    1998-01-01

    Full text: The evolution of the structure of a large system of atoms interacting via a Lennard-Jones pair potential was simulated by the use of the Molecular Dynamics computer simulation technique. The system was initially equilibrated in the one phase region of the phase diagram at a temperature above critical then a temperature quench was performed which placed the system in a region were the single fluid phase was unstable. Quenches to below the triple point temperature gave rise to crystallisation The mechanism and final morphology is shown to depend strongly on the starting conditions e.g. the starting density

  16. Radiation transport in dense interstellar dust clouds. II. Infrared emission from molecular clouds associated with H II regions

    International Nuclear Information System (INIS)

    Leung, C.M.

    1976-01-01

    Theoretical models are constructed to study the distribution of grain temperature (T/sub d/) and infrared emission from molecular clouds associated with H II regions (with embedded O: B stars). The effects of the following parameters on the temperature structure and the emergent spectrum are studied: grain type (graphite, silicate, and core-mantle grains), optical depth, density inhomogeneity, cloud size, anisotropic scattering, radiation field anisotropy, and characteristics of central heat source. T/sub d/ varies from approximately-greater-than100 K to approximately-less-than20 K throughout the major portion of a cloud, and dielectric grains attain lower temperatures. Due to an inward increase in T/sub d/, the radiation field is strongly forward-peaking, thereby producing a pronounced limb-darkening in the surface brightness. Important features of the computed emission spectra from typical models are compared with available observations, and the importance of beam dilution is emphasized. Theoretical surface brightnesses at selected infrared wavelengths are also presented. The outward radiation pressure on the dust grains is found to exceed the self-gravitational force of the gas over a large portion of a cloud, thus possibly causing the gas in the inner region to expand. Assumptions commonly used in the analysis of infrared observations are examined. Finally, observational methods of deriving the temperature structure (from color and brightness temperatures in the far-infrared), density distribution (from surface brightness at lambdaapproximately-greater-than1 mm), and optical depth (from multiaperture photometry) for the dust component in simple sources are discussed

  17. Improved thermodynamics of the dense solar plasma and molecular-dynamics simulations of the nuclear-reaction rates

    Science.gov (United States)

    Mao, Dan

    available, there is no alternative source. The official OPAL tables, however, have disadvantages. First, they are inflexible regarding the chemical mix, which is set once and for all by the producers of the tables. Our equation of state will allow the user to choose, in principle, an arbitrary mix. Second, the OPAL tables by their very nature are limited by the errors of interpolation within tables. The second equation of state model is a density expansion based on the Feynman-Kac path-integral formalism. By making use of the equivalence of quantum Hamiltonian matrix and the classical action of closed and open filaments (paths), an analytic formalism of equation of state. Although the character of density expansion limits its application, the formalism can still be valid in most region in the Sun. Our work provides the link between the abstract theoretical formalism that was developed in the 1990s and a numerically smooth realization that can be used in solar and stellar models. Since it is so far the most exact and systematic approach for an EOS, it provides another way to study the influence of different very fine physical effects, despite considerable limitations in its domain of applicability. In the nuclear-reaction part of the thesis, we have used a molecular-dynamics method to simulate the motion of protons in a hydrogen plasma (which is a good approximation for this purpose). Quantum tunneling explains why nuclear fusion can occur in the first place, considering the "low" temperature in the solar core. It is well known that this tunneling is enhanced (which leads to higher nuclear reaction rates) in the presence of Coulomb screening. In the 1950, Salpeter formulated a theory based on the static-screened Coulomb potential, as derived by Debye and H=FCckel in the 1920s. As expected, Salpeter obtained enhanced reaction rates. But from our simulation, we confirmed the results of a recent controversy about the existence of a dynamic effect. Since the bulk of fusion

  18. Direct electron and ion fluid computation of high electrostatic fields in dense inhomogeneous plasmas with subsequent nonlinear optical and dynamical laser interaction

    International Nuclear Information System (INIS)

    Lalousis, P.

    1984-01-01

    Nonthermal direct electrodynamic interaction between laser energy and a fully ionized plasma was studied. The particular emphasis is on the action of nonlinear forces, in which the optical electromagnetic fields act on the plasma electrons which then transfer their energy to the ions electrostatically. Instead of the usual single fluid model, the plasma is treated as two separate conducting fluids for electrons and ions, coupled by momentum and Coulomb interactions. The equations governing the two fluids are derived from first principles, and numerical algorithms for computing these equations are developed, enabling the plasma oscillatons to be resolved and studied. Fully ionized plasma expansion without laser irradiation is studied first numerically. Remarkable damping mechanisms by coupling to ion oscillations have been observed. Inhomogeneities in densities of the two fluids result in large electrostatic fields and double layers are generated. There is quite close agreement between numerically calculated electrostatic fields and analytical solutions. Laser interaction with fully ionized plasma is also studied numerically. The generation of cavitons is numerically observed, and it is inferred that laser plasma interactions produce very high electrostatic fields in the vicinity of cavitons. It is further shown that charge neutrality is not necessarily maintained in a caviton

  19. Magnetic nanoparticles in fluid environment: combining molecular dynamics and Lattice-Boltzmann

    Energy Technology Data Exchange (ETDEWEB)

    Melenev, Petr, E-mail: melenev@icmm.ru [Ural Federal University, 4, Turgeneva str., 620000 Ekaterinburg (Russian Federation); Institute of Continuous Media Mechanics, 1, Koroleva str., 614013 Perm (Russian Federation)

    2017-06-01

    Hydrodynamic interactions between magnetic nanoparticles suspended in the Newtonian liquid are accounted for using a combination of the lattice Boltzmann method and molecular dynamics simulations. Nanoparticle is modelled by the system of molecular dynamics material points (which form structure resembles raspberry) coupled to the lattice Boltzmann fluid. The hydrodynamic coupling between the colloids is studied by simulations of the thermo-induced rotational diffusion of two raspberry objects. It was found that for the considered range of model parameters the approaching of the raspberries leads to slight retard of the relaxation process. The presence of the weak magnetic dipolar interaction between the objects leads to modest decrease of the relaxation time and the extent of the acceleration of the diffusion is intensified along with magnetic forces. - Highlights: • The combination of molecular dynamics and lattice Boltzmann method is utilized for the reveal of the role of hydrodynamic interaction in rotational dynamics of colloid particles. • The verification of the model parameters is done based on the comparison with the results of Langevin dynamics. • For the task of free rotational diffusion of the pair of colloid particles the influence of the hydrodynamic interactions on the relaxation time is examined in the case of nonmagnetic particles and at the presence of weak dipolar interaction.

  20. Complex dynamics induced by strong confinement - From tracer diffusion in strongly heterogeneous media to glassy relaxation of dense fluids in narrow slits

    Science.gov (United States)

    Mandal, Suvendu; Spanner-Denzer, Markus; Leitmann, Sebastian; Franosch, Thomas

    2017-08-01

    We provide an overview of recent advances of the complex dynamics of particles in strong confinements. The first paradigm is the Lorentz model where tracers explore a quenched disordered host structure. Such systems naturally occur as limiting cases of binary glass-forming systems if the dynamics of one component is much faster than the other. For a certain critical density of the host structure the tracers undergo a localization transition which constitutes a critical phenomenon. A series of predictions in the vicinity of the transition have been elaborated and tested versus computer simulations. Analytical progress is achieved for small obstacle densities. The second paradigm is a dense strongly interacting liquid confined to a narrow slab. Then the glass transition depends nonmonotonically on the separation of the plates due to an interplay of local packing and layering. Very small slab widths allow to address certain features of the statics and dynamics analytically.

  1. THE BOLOCAM GALACTIC PLANE SURVEY. X. A COMPLETE SPECTROSCOPIC CATALOG OF DENSE MOLECULAR GAS OBSERVED TOWARD 1.1 mm DUST CONTINUUM SOURCES WITH 7.°5 ≤ l ≤ 194°

    International Nuclear Information System (INIS)

    Shirley, Yancy L.; Svoboda, Brian; Ellsworth-Bowers, Timothy P.; Schlingman, Wayne M.; Ginsburg, Adam; Battersby, Cara; Stringfellow, Guy; Glenn, Jason; Bally, John; Rosolowsky, Erik; Gerner, Thomas; Mairs, Steven; Dunham, Miranda K.

    2013-01-01

    The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey of dense clumps of dust throughout the Galaxy covering 170 deg 2 . We present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO + and N 2 H + 3-2, for all 6194 sources in the BGPS v1.0.1 catalog between 7.°5 ≤ l ≤ 194°. This is the largest targeted spectroscopic survey of dense molecular gas in the Milky Way to date. We find unique velocities for 3126 (50.5%) of the BGPS v1.0.1 sources observed. Strong N 2 H + 3-2 emission (T mb > 0.5 K) without HCO + 3-2 emission does not occur in this catalog. We characterize the properties of the dense molecular gas emission toward the entire sample. HCO + is very sub-thermally populated and the 3-2 transitions are optically thick toward most BGPS clumps. The median observed line width is 3.3 km s –1 consistent with supersonic turbulence within BGPS clumps. We find strong correlations between dense molecular gas integrated intensities and 1.1 mm peak flux and the gas kinetic temperature derived from previously published NH 3 observations. These intensity correlations are driven by the sensitivity of the 3-2 transitions to excitation conditions rather than by variations in molecular column density or abundance. We identify a subset of 113 sources with stronger N 2 H + than HCO + integrated intensity, but we find no correlations between the N 2 H + /HCO + ratio and 1.1 mm continuum flux density, gas kinetic temperature, or line width. Self-absorbed profiles are rare (1.3%)

  2. THE BOLOCAM GALACTIC PLANE SURVEY. X. A COMPLETE SPECTROSCOPIC CATALOG OF DENSE MOLECULAR GAS OBSERVED TOWARD 1.1 mm DUST CONTINUUM SOURCES WITH 7.°5 ≤ l ≤ 194°

    Energy Technology Data Exchange (ETDEWEB)

    Shirley, Yancy L.; Svoboda, Brian [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Ellsworth-Bowers, Timothy P.; Schlingman, Wayne M.; Ginsburg, Adam; Battersby, Cara; Stringfellow, Guy; Glenn, Jason; Bally, John [CASA, University of Colorado, CB 389, Boulder, CO 80309 (United States); Rosolowsky, Erik [Department of Physics, University of Alberta, 4-181 CCIS Edmonton AB T6G 2E1 (Canada); Gerner, Thomas [Max-Planck-Institut für Astronomie (MPIA), Knigstuhl 17, D-69117 Heidelberg (Germany); Mairs, Steven [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria, BC V8W 3P6 (Canada); Dunham, Miranda K. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

    2013-11-01

    The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey of dense clumps of dust throughout the Galaxy covering 170 deg{sup 2}. We present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO{sup +} and N{sub 2}H{sup +} 3-2, for all 6194 sources in the BGPS v1.0.1 catalog between 7.°5 ≤ l ≤ 194°. This is the largest targeted spectroscopic survey of dense molecular gas in the Milky Way to date. We find unique velocities for 3126 (50.5%) of the BGPS v1.0.1 sources observed. Strong N{sub 2}H{sup +} 3-2 emission (T {sub mb} > 0.5 K) without HCO{sup +} 3-2 emission does not occur in this catalog. We characterize the properties of the dense molecular gas emission toward the entire sample. HCO{sup +} is very sub-thermally populated and the 3-2 transitions are optically thick toward most BGPS clumps. The median observed line width is 3.3 km s{sup –1} consistent with supersonic turbulence within BGPS clumps. We find strong correlations between dense molecular gas integrated intensities and 1.1 mm peak flux and the gas kinetic temperature derived from previously published NH{sub 3} observations. These intensity correlations are driven by the sensitivity of the 3-2 transitions to excitation conditions rather than by variations in molecular column density or abundance. We identify a subset of 113 sources with stronger N{sub 2}H{sup +} than HCO{sup +} integrated intensity, but we find no correlations between the N{sub 2}H{sup +}/HCO{sup +} ratio and 1.1 mm continuum flux density, gas kinetic temperature, or line width. Self-absorbed profiles are rare (1.3%)

  3. Spatially resolved chemistry in nearby galaxies. III. Dense molecular gas in the inner disk of the LIRG IRAS 04296+2923

    Energy Technology Data Exchange (ETDEWEB)

    Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 (United States); Turner, Jean L. [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States); Beck, Sara C., E-mail: dmeier@nmt.edu, E-mail: turner@astro.ucla.edu, E-mail: sara@wise.tau.ac.il [Department of Physics and Astronomy, Tel Aviv University, 69978 Ramat Aviv (Israel)

    2014-11-10

    We present a survey of 3 mm molecular lines in IRAS 04296+2923, one of the brightest known molecular-line emitting galaxies, and one of the closest luminous infrared galaxies (LIRGs). Data are from the Owens Valley and CARMA millimeter interferometers. Species detected at ≲ 4'' resolution include C{sup 18}O, HCN, HCO{sup +}, HNC, CN, CH{sub 3}OH, and, tentatively, HNCO. Along with existing CO, {sup 13}CO, and radio continuum data, these lines constrain the chemical properties of the inner disk. Dense molecular gas in the nucleus fuels a star formation rate ≳10 M {sub ☉} yr{sup –1} and is traced by lines of HCN, HCO{sup +}, HNC, and CN. A correlation between HCN and star formation rate is observed on sub-kiloparsec scales, consistent with global relations. Toward the nucleus, CN abundances are similar to those of HCN, indicating emission comes from a collection (∼40-50) of moderate visual extinction, photon-dominated-region clouds. The CO isotopic line ratios are unusual: CO(1-0)/{sup 13}CO(1-0) and CO(1-0)/C{sup 18}O(1-0) line ratios are large toward the starburst, as is commonly observed in LIRGs, but farther out in the disk these ratios are remarkably low (≲ 3). {sup 13}CO/C{sup 18}O abundance ratios are lower than in Galactic clouds, possibly because the C{sup 18}O is enriched by massive star ejecta from the starburst. {sup 13}CO is underabundant relative to CO. Extended emission from CH{sub 3}OH indicates that dynamical shocks pervade both the nucleus and the inner disk. The unusual CO isotopologue ratios, the CO/HCN intensity ratio versus L {sub IR}, the HCN/CN abundance ratio, and the gas consumption time versus inflow rate all indicate that the starburst in IRAS 04296+2923 is in an early stage of development.

  4. Towards the design of new and improved drilling fluid additives using molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Richard L. Anderson

    2010-03-01

    Full Text Available During exploration for oil and gas, a technical drilling fluid is used to lubricate the drill bit, maintain hydrostatic pressure, transmit sensor readings, remove rock cuttings and inhibit swelling of unstable clay based reactive shale formations. Increasing environmental awareness and resulting legislation has led to the search for new, improved biodegradable drilling fluid components. In the case of additives for clay swelling inhibition, an understanding of how existing effective additives interact with clays must be gained to allow the design of improved molecules. Owing to the disordered nature and nanoscopic dimension of the interlayer pores of clay minerals, computer simulations have become an increasingly useful tool for studying clay-swelling inhibitor interactions. In this work we briefly review the history of the development of technical drilling fluids, the environmental impact of drilling fluids and the use of computer simulations to study the interactions between clay minerals and swelling inhibitors. We report on results from some recent large-scale molecular dynamics simulation studies on low molecular weight water-soluble macromolecular inhibitor molecules. The structure and interactions of poly(propylene oxide-diamine, poly(ethylene glycol and poly(ethylene oxide-diacrylate inhibitor molecules with montmorillonite clay are studied.Durante a exploração de óleo e gás um fluido de perfuração é usado para lubrificar 'bit' da perfuradora, manter a pressão hidrostática, transmitir sensores de leitura, remover resíduos da rocha e inibir o inchamento da argila instável baseada nas formações dos folhelhos. O aumento das preocupações ambientais bem como a legislação resultante levou à procura de novos fluidos de perfuração com componentes biodegradáveis. No caso dos aditivos para inibir o inchamento das argilas o entendimento das interações entre os aditivos e as argilas tem que ser adquirido para permitir o

  5. Properties of molecular solids and fluids at high pressures and temperatures. [Final report

    International Nuclear Information System (INIS)

    Etters, R.D.

    1985-01-01

    Equilibrium structures and orientations, lattice vibrational and librational model frequencies, intramolecular vibron mode frequencies, sound velocities, equations of state, compressibilities, and structural and orientational phase transitions in molecular solids are determined over a wide range of pressures and temperatures. In the high temperature fluid phase the equations of state, vibron frequencies, the melting transition, specific heats, compressibilities, second virial coefficients, viscosities and other transport properties, and the nature of orientational and magnetic correlations are determined. The techniques used include several strategies to optimize multi-dimensional functions as a means to determine equilibrium structures and orientations, self consistent phonon lattice dynamics methods, constant pressure and constant volume Monte-Carlo strategies with continuously deformable boundary conditions, mean field approximations, and classical perturbation methods. Systems studied include N 2 , O 2 , CO, CO 2 , F 2 , N 2 O, benzine, nitromethane, HCL, HBr, and H 2 . 50 refs., 4 figs

  6. Evidence for low molecular weight, non-transferrin-bound iron in rat brain and cerebrospinal fluid

    DEFF Research Database (Denmark)

    Moos, Torben; Morgan, Evan H.

    1998-01-01

    Neuroscience, blood-brain barrier, choroid plexus, interstitial fluid, transferrin receptor, uptake......Neuroscience, blood-brain barrier, choroid plexus, interstitial fluid, transferrin receptor, uptake...

  7. A History of constitutive modeling via molecular dynamics: Shock waves in fluids and gases

    Directory of Open Access Journals (Sweden)

    Holian B.L.

    2011-01-01

    Full Text Available From its inception in the mid-Fifties, the method of molecular-dynamics (MD computer simulations has been used to probe the foundations of statistical mechanics, first for equilibrium equation-of-state averages, and then for transport properties from equilibrium fluctuations. Traditional statistical mechanical theoreticians were shocked to see that this new-fangled computational physics approach was feasible, even with incredibly tiny samples (on the order of a hundred atoms. When direct measurement of transport coefficients by non-equilibrium molecular dynamics (NEMD was proposed in the early Seventies, even greater resistance was encountered from the traditionalists – though evidence for convergence with the equilibrium fluctuation method gradually accumulated. In the late Seventies and early Eighties, shock-wave simulations by NEMD made it possible to test directly the principal continuum constitutive theory for fluids, namely, Navier-Stokes viscous flow and Fourier’s Law of heat conduction. To everyone’s surprise – and the consternation of many – NEMD, once again, demonstrated that continuum theory applies at embarrassingly small (atomistic time and length scales. We pursue this early line of work into the modern era, showing how NEMD shock-wave simulations can still provide surprising insights and improvements upon our understanding of constitutive modeling.

  8. Nonequilibrium molecular dynamics simulation of coupling between nanoparticles and base-fluid in a nanofluid

    International Nuclear Information System (INIS)

    Kang, Hongbo; Zhang, Yuwen; Yang, Mo; Li, Ling

    2012-01-01

    The intent of this study is to examine nonequilibrium heat transfer in a copper–argon nanofluid by molecular dynamics simulation. Two different methods, the physical definition method and the curve fitting method, are introduced to calculate the coupling factor between nanoparticles and base fluid. The results show that the coupling factors obtained by these two methods are consistent. The coupling factor is proportional to the volume fraction of the nanoparticle and inversely proportional to nanoparticle diameter. In the temperature range of 90–200 K, the coupling factor is not affected by temperature. The nanoparticle aggregation results in a decrease of the coupling factor. -- Highlights: ► Nonequilibrium heat transfer in a copper–argon nanofluid is investigated by molecular dynamics simulation. ► The coupling factor is proportion to the volume fraction of the nanoparticle and inverse proportion to nanoparticle diameter. ► In the temperature range of 90–200 K, there is no temperature effect on the coupling factor. ► The nanoparticle aggregation results in a decrease of the coupling factor.

  9. A third order accurate Lagrangian finite element scheme for the computation of generalized molecular stress function fluids

    DEFF Research Database (Denmark)

    Fasano, Andrea; Rasmussen, Henrik K.

    2017-01-01

    A third order accurate, in time and space, finite element scheme for the numerical simulation of three- dimensional time-dependent flow of the molecular stress function type of fluids in a generalized formu- lation is presented. The scheme is an extension of the K-BKZ Lagrangian finite element me...

  10. Molecular dynamics studies of transport properties and equation of state of supercritical fluids

    Science.gov (United States)

    Nwobi, Obika C.

    Many chemical propulsion systems operate with one or more of the reactants above the critical point in order to enhance their performance. Most of the computational fluid dynamics (CFD) methods used to predict these flows require accurate information on the transport properties and equation of state at these supercritical conditions. This work involves the determination of transport coefficients and equation of state of supercritical fluids by equilibrium molecular dynamics (MD) simulations on parallel computers using the Green-Kubo formulae and the virial equation of state, respectively. MD involves the solution of equations of motion of a system of molecules that interact with each other through an intermolecular potential. Provided that an accurate potential can be found for the system of interest, MD can be used regardless of the phase and thermodynamic conditions of the substances involved. The MD program uses the effective Lennard-Jones potential, with system sizes of 1000-1200 molecules and, simulations of 2,000,000 time-steps for computing transport coefficients and 200,000 time-steps for pressures. The computer code also uses linked cell lists for efficient sorting of molecules, periodic boundary conditions, and a modified velocity Verlet algorithm for particle displacement. Particle decomposition is used for distributing the molecules to different processors of a parallel computer. Simulations have been carried out on pure argon, nitrogen, oxygen and ethylene at various supercritical conditions, with self-diffusion coefficients, shear viscosity coefficients, thermal conductivity coefficients and pressures computed for most of the conditions. Results compare well with experimental and the National Institute of Standards and Technology (NIST) values. The results show that the number of molecules and the potential cut-off radius have no significant effect on the computed coefficients, while long-time integration is necessary for accurate determination of the

  11. Structure and properties of simple molecular systems at very high density

    International Nuclear Information System (INIS)

    LeSar, R.

    1989-01-01

    The use of computer simulations in the study of molecular systems at very high density is reviewed. Applications to the thermodynamics of dense fluid nitrogen and phase transitions in solid oxygen are presented. The effects of changes in the atomic electronic structure on the equation of state of very dense helium are discussed. 19 refs., 2 figs

  12. Morphological and molecular features of oral fluid-derived exosomes: oral cancer patients versus healthy individuals.

    Science.gov (United States)

    Zlotogorski-Hurvitz, Ayelet; Dayan, Dan; Chaushu, Gavriel; Salo, Tuula; Vered, Marilena

    2016-01-01

    Oral cancer (OC) patients are at high risk to develop recurrent disease or secondary primary cancers with no available biomarkers to detect these events until a visible lesion is readily present and diagnosed by biopsy. Exosomes secreted by cancer cells are involved in tumor growth, invasion and metastasis. We aimed to determine morphological and molecular differences between oral fluid (OF)-derived exosomes of OC patients and those isolated from healthy individuals (HI). OF from OC patients (n = 36) and HI (n = 25) was initially assessed by nanoparticle tracking analysis (NTA). Following ultracentrifugation, exosomal pellets of OC patients and HI were morphologically examined by transmission electron microscopy and atomic force microscopy (AFM). Enzyme-linked immunosorbent assay (ELISA) and western blotting (WB) were used to analyze the expression of exosomal markers--CD9, CD81 and CD63. NTA showed that OC samples of OF had a significantly higher concentration of nanoparticles/ml (p = 0.01) and modal nanoparticle size (p = 0.002) compared to HI. The difference in size was structurally highlighted by AFM three-dimensional images applied on exosomal pellets. ELISA and WB showed differential expression of exosomal markers in OC exosomes compared to HI: lower expression of CD81 and CD9 in contrast to a higher expression of CD63 (~53 kDa). OF-derived exosomes from OC patients differ both morphologically and molecularly from exosomes present in HI. This study is a baseline that provides a starting point for finding exosomal biomarkers for early detection of malignant changes in high-risk patients without overt clinical signs/lesions.

  13. Dynamics of dense particle disks

    International Nuclear Information System (INIS)

    Araki, S.; Tremaine, S.; Toronto Univ., Canada)

    1986-01-01

    The present investigation of mechanical equilibrium and collisional transport processes in dense, differentially rotating particle disks is based on the Enskog (1922) theory of dense, hard sphere gases, with the single exception that the spheres are inelastic. The viscous instability suggested as a source of Saturn B ring structure does not arise in the models presented, although the ring may be subject to a phase transition analogous to the liquid-solid transition observed in molecular dynamics simulations of elastic hard spheres. In such a case, the ring would alternately exhibit zero-shear, or solid, and high shear, or liquid, zones. 29 references

  14. Fluids density functional theory and initializing molecular dynamics simulations of block copolymers

    Science.gov (United States)

    Brown, Jonathan R.; Seo, Youngmi; Maula, Tiara Ann D.; Hall, Lisa M.

    2016-03-01

    Classical, fluids density functional theory (fDFT), which can predict the equilibrium density profiles of polymeric systems, and coarse-grained molecular dynamics (MD) simulations, which are often used to show both structure and dynamics of soft materials, can be implemented using very similar bead-based polymer models. We aim to use fDFT and MD in tandem to examine the same system from these two points of view and take advantage of the different features of each methodology. Additionally, the density profiles resulting from fDFT calculations can be used to initialize the MD simulations in a close to equilibrated structure, speeding up the simulations. Here, we show how this method can be applied to study microphase separated states of both typical diblock and tapered diblock copolymers in which there is a region with a gradient in composition placed between the pure blocks. Both methods, applied at constant pressure, predict a decrease in total density as segregation strength or the length of the tapered region is increased. The predictions for the density profiles from fDFT and MD are similar across materials with a wide range of interfacial widths.

  15. Method of making supercritical fluid molecular spray films, powder and fibers

    Science.gov (United States)

    Smith, Richard D.

    1988-01-01

    Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a heated nozzle having a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. In another embodiment, the temperature of the solution and nozzle is elevated above the melting point of the solute, which is preferably a polymer, and the solution is maintained at a pressure such that, during expansion, the solute precipitates out of solution within the nozzle in a liquid state. Alternatively, a secondary solvent mutually soluble with the solute and primary solvent and having a higher critical temperature than that of primary solvent is used in a low concentration (<20%) to maintain the solute in a transient liquid state. The solute is discharged in the form of long, thin fibers. The fibers are collected at sufficient distance from the orifice to allow them to solidify in the low pressure/temperature region.

  16. Intense, ultrashort light and dense, hot matter

    Indian Academy of Sciences (India)

    tiphoton and tunneling ionization, the physics of plasma formed in dense matter is .... A typical Gaussian laser pulse of 100 fs dura- .... J range) – and finally it is compressed back to its .... bond-hardening, molecular orientation and reori-.

  17. Sensitivity analysis of Computer-aided molecular design problem for the development of novel working fluids for power cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    is vital. Multi-criteria database search and Computer Aided Molecular Design(CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance. The problem formulation for the development of novel working fluids...... is anadvanced CAMD challenge both in terms of data and computational demand, because includes process related as wellas property related equations.In CAMD problems the identification of target properties is often based on expert knowledge. To support identification of relevant target properties, in this study...... allows the ranking ofsignificance of properties and also the identification of a set of properties which are relevant for the design of a workingfluids.In this study the CAMD problem for the development of novel working fluids for organic Rankine cycles (ORC) isformulated as a mathematical optimization...

  18. Photoresponsive surface molecularly imprinted polymer on ZnO nanorods for uric acid detection in physiological fluids

    International Nuclear Information System (INIS)

    Tang, Qian; Li, Zai-yong; Wei, Yu-bo; Yang, Xia; Liu, Lan-tao; Gong, Cheng-bin; Ma, Xue-bing; Lam, Michael Hon-wah; Chow, Cheuk-fai

    2016-01-01

    A photoresponsive surface molecularly imprinted polymer for uric acid in physiological fluids was fabricated through a facile and effective method using bio-safe and biocompatible ZnO nanorods as a support. The strategy was carried out by introducing double bonds on the surface of the ZnO nanorods with 3-methacryloxypropyltrimethoxysilane. The surface molecularly imprinted polymer on ZnO nanorods was then prepared by surface polymerization using uric acid as template, water-soluble 5-[(4-(methacryloyloxy)phenyl)diazenyl]isophthalic acid as functional monomer, and triethanolamine trimethacryl ester as cross-linker. The surface molecularly imprinted polymer on ZnO nanorods showed good photoresponsive properties, high recognition ability, and fast binding kinetics toward uric acid, with a dissociation constant of 3.22 × 10"−"5 M in aqueous NaH_2PO_4 buffer at pH = 7.0 and a maximal adsorption capacity of 1.45 μmol g"−"1. Upon alternate irradiation at 365 and 440 nm, the surface molecularly imprinted polymer on ZnO nanorods can quantitatively uptake and release uric acid. - Highlights: • Novel surface molecularly imprinted polymer on ZnO nanorods was synthesized. • ZnO-SMIP showed good selectivity toward uric acid in physiological fluids. • ZnO-SMIP displayed good photoresponsive properties.

  19. Photoresponsive surface molecularly imprinted polymer on ZnO nanorods for uric acid detection in physiological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Qian [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Department of Science and Environmental Studies, The Hong Kong Institute of Education (Hong Kong); Li, Zai-yong; Wei, Yu-bo; Yang, Xia; Liu, Lan-tao [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Gong, Cheng-bin, E-mail: gongcbtq@swu.edu.cn [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Ma, Xue-bing [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Lam, Michael Hon-wah [Department of Biology and Chemistry, City University of Hong Kong (Hong Kong); Chow, Cheuk-fai, E-mail: cfchow@ied.edu.hk [Department of Science and Environmental Studies, The Hong Kong Institute of Education (Hong Kong)

    2016-09-01

    A photoresponsive surface molecularly imprinted polymer for uric acid in physiological fluids was fabricated through a facile and effective method using bio-safe and biocompatible ZnO nanorods as a support. The strategy was carried out by introducing double bonds on the surface of the ZnO nanorods with 3-methacryloxypropyltrimethoxysilane. The surface molecularly imprinted polymer on ZnO nanorods was then prepared by surface polymerization using uric acid as template, water-soluble 5-[(4-(methacryloyloxy)phenyl)diazenyl]isophthalic acid as functional monomer, and triethanolamine trimethacryl ester as cross-linker. The surface molecularly imprinted polymer on ZnO nanorods showed good photoresponsive properties, high recognition ability, and fast binding kinetics toward uric acid, with a dissociation constant of 3.22 × 10{sup −5} M in aqueous NaH{sub 2}PO{sub 4} buffer at pH = 7.0 and a maximal adsorption capacity of 1.45 μmol g{sup −1}. Upon alternate irradiation at 365 and 440 nm, the surface molecularly imprinted polymer on ZnO nanorods can quantitatively uptake and release uric acid. - Highlights: • Novel surface molecularly imprinted polymer on ZnO nanorods was synthesized. • ZnO-SMIP showed good selectivity toward uric acid in physiological fluids. • ZnO-SMIP displayed good photoresponsive properties.

  20. Estimation and Uncertainty Analysis of Flammability Properties for Computer-aided molecular design of working fluids for thermodynamic cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    Computer Aided Molecular Design (CAMD) is an important tool to generate, test and evaluate promising chemical products. CAMD can be used in thermodynamic cycle for the design of pure component or mixture working fluids in order to improve the heat transfer capacity of the system. The safety......, there is no information about the reliability of the data. Furthermore, the global optimality of the GC parameters estimation is often not ensured....

  1. Applications of Molecular Dynamics, Monte Carlo and Metadynamics Simulations Using ReaxFF Reactive Force Fields to Fluid/Solid Interfaces

    Science.gov (United States)

    Raju, Muralikrishna

    The interaction of dense fluids (water, polar organic solvents, room temperature ionic liquids, etc.) with solid substrates controls many chemical processes encountered in nature and industry. The key features of fluid-solid interfaces (FSIs) are the high mobility and often reactivity of the fluid phase, and the structural control provided by the solid phase. In this dissertation we apply molecular modeling methods to study FSIs in the following systems: 1. Dissociation of water on titania surfaces. We studied the adsorption and dissociation of water at 300 K on the following TiO2 surfaces: anatase (101), (100), (112), (001) and rutile (110) at various water coverages, using a recently developed ReaxFF reactive force field. The molecular and dissociative adsorption configurations predicted by ReaxFF for various water coverages agree with previous theoretical studies and experiment. 2. Mechanisms of Oriented Attachment in TiO2 nanocrystals. Oriented attachment (OA) of nanocrystals is now widely recognized as a key process in the solution-phase growth of hierarchical nanostructures. However, the microscopic origins of OA remain unclear. Using the same ReaxFF Ti/O/H reactive force field employed in the previous study, we perform molecular dynamics simulations to study the aggregation of various titanium dioxide (anatase) nanocrystals in vacuum and humid environments. 3. Li interactions in carbon based materials. Graphitic carbon is still the most ubiquitously used anode material in Li-ion batteries. In spite of its ubiquity, there are few theoretical studies that fully capture the energetics and kinetics of Li in graphite and related nanostructures at experimentally relevant length/time-scales and Li-ion concentrations. In this study we describe development and application of a ReaxFF reactive force field to describe Li interactions in perfect and defective carbon based materials using atomistic simulations. We develop force-field parameters for Li-C systems using van

  2. Generalized extended Navier-Stokes theory: Multiscale spin relaxation in molecular fluids

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt

    2013-01-01

    This paper studies the relaxation of the molecular spin angular velocity in the framework of generalized extended Navier-Stokes theory. Using molecular dynamics simulations, it is shown that for uncharged diatomic molecules the relaxation time decreases with increasing molecular moment of inertia...

  3. On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

    KAUST Repository

    Skarmoutsos, Ioannis; Eddaoudi, Mohamed; Maurin, Guillaume

    2018-01-01

    .e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour

  4. Molecular theory of chromatography for blocklike solutes in isotropic stationary phases and its application to supercritical fluid chromatographic retention of PAHs

    International Nuclear Information System (INIS)

    Chao Yan; Martire, D.E.

    1992-01-01

    This report discusses a molecular theory of chromatography for blocklike solutes in isotropic stationary phases as an extension to the anisotopic phase approach. Its it applied to gas, liquid, and supercritical fluid chromatography

  5. Numerical methodologies for investigation of moderate-velocity flow using a hybrid computational fluid dynamics - molecular dynamics simulation approach

    International Nuclear Information System (INIS)

    Ko, Soon Heum; Kim, Na Yong; Nikitopoulos, Dimitris E.; Moldovan, Dorel; Jha, Shantenu

    2014-01-01

    Numerical approaches are presented to minimize the statistical errors inherently present due to finite sampling and the presence of thermal fluctuations in the molecular region of a hybrid computational fluid dynamics (CFD) - molecular dynamics (MD) flow solution. Near the fluid-solid interface the hybrid CFD-MD simulation approach provides a more accurate solution, especially in the presence of significant molecular-level phenomena, than the traditional continuum-based simulation techniques. It also involves less computational cost than the pure particle-based MD. Despite these advantages the hybrid CFD-MD methodology has been applied mostly in flow studies at high velocities, mainly because of the higher statistical errors associated with low velocities. As an alternative to the costly increase of the size of the MD region to decrease statistical errors, we investigate a few numerical approaches that reduce sampling noise of the solution at moderate-velocities. These methods are based on sampling of multiple simulation replicas and linear regression of multiple spatial/temporal samples. We discuss the advantages and disadvantages of each technique in the perspective of solution accuracy and computational cost.

  6. Communication: A method to compute the transport coefficient of pure fluids diffusing through planar interfaces from equilibrium molecular dynamics simulations.

    Science.gov (United States)

    Vermorel, Romain; Oulebsir, Fouad; Galliero, Guillaume

    2017-09-14

    The computation of diffusion coefficients in molecular systems ranks among the most useful applications of equilibrium molecular dynamics simulations. However, when dealing with the problem of fluid diffusion through vanishingly thin interfaces, classical techniques are not applicable. This is because the volume of space in which molecules diffuse is ill-defined. In such conditions, non-equilibrium techniques allow for the computation of transport coefficients per unit interface width, but their weak point lies in their inability to isolate the contribution of the different physical mechanisms prone to impact the flux of permeating molecules. In this work, we propose a simple and accurate method to compute the diffusional transport coefficient of a pure fluid through a planar interface from equilibrium molecular dynamics simulations, in the form of a diffusion coefficient per unit interface width. In order to demonstrate its validity and accuracy, we apply our method to the case study of a dilute gas diffusing through a smoothly repulsive single-layer porous solid. We believe this complementary technique can benefit to the interpretation of the results obtained on single-layer membranes by means of complex non-equilibrium methods.

  7. Paper Spray Tandem Mass Spectrometry Based on Molecularly Imprinted Polymer Substrate for Cocaine Analysis in Oral Fluid

    Science.gov (United States)

    Tavares, Ludmyla S.; Carvalho, Thays C.; Romão, Wanderson; Vaz, Boniek G.; Chaves, Andréa R.

    2018-03-01

    This study proposes a new direct and fast method of analysis employing paper spray mass spectrometry (PS-MS). The paper used in the proposed method was modified with molecularly imprinted polymers (MIP) to create a specific site for cocaine analysis in oral fluid. MIP membrane was successfully synthetized and employed. The developed method showed to be linear in a concentration range from LOQ to 100 ng mL-1. The experimental value of LOQ obtained was 1 ng mL-1. The inter-day and intra-day precision and accuracy of the PS-MS method presented values lower than 15%. The total recoveries were also evaluated. The PS-MS method for the analysis of cocaine in oral fluid showed to be very promising and the validation parameters showed a good correlation with the literature. [Figure not available: see fulltext.

  8. Dynamical properties and transport coefficients of one-dimensional Lennard-Jones fluids: A molecular dynamics study

    Science.gov (United States)

    Bazhenov, Alexiev M.; Heyes, David M.

    1990-01-01

    The thermodynamics, structure, and transport coefficients, as defined by the Green-Kubo integrals, of the one-dimensional Lennard-Jones fluid are evaluated for a wide range of state points by molecular dynamics computer simulation. These calculations are performed for the first time for thermal conductivity and the viscosity. We observe a transition from hard-rod behavior at low number density to harmonic-spring fluid behavior in the close-packed limit. The self-diffusion coefficient decays with increasing density to a finite limiting value. The thermal conductivity increases with density, tending to ∞ in the close-packed limit. The viscosity in contrast maximizes at intermediate density, tending to zero in the zero density and close-packed limits.

  9. Magnetic Capture of a Molecular Biomarker from Synovial Fluid in a Rat Model of Knee Osteoarthritis.

    Science.gov (United States)

    Yarmola, Elena G; Shah, Yash; Arnold, David P; Dobson, Jon; Allen, Kyle D

    2016-04-01

    Biomarker development for osteoarthritis (OA) often begins in rodent models, but can be limited by an inability to aspirate synovial fluid from a rodent stifle (similar to the human knee). To address this limitation, we have developed a magnetic nanoparticle-based technology to collect biomarkers from a rodent stifle, termed magnetic capture. Using a common OA biomarker--the c-terminus telopeptide of type II collagen (CTXII)--magnetic capture was optimized in vitro using bovine synovial fluid and then tested in a rat model of knee OA. Anti-CTXII antibodies were conjugated to the surface of superparamagnetic iron oxide-containing polymeric particles. Using these anti-CTXII particles, magnetic capture was able to estimate the level of CTXII in 25 μL aliquots of bovine synovial fluid; and under controlled conditions, this estimate was unaffected by synovial fluid viscosity. Following in vitro testing, anti-CTXII particles were tested in a rat monoiodoacetate model of knee OA. CTXII could be magnetically captured from a rodent stifle without the need to aspirate fluid and showed tenfold changes in CTXII levels from OA-affected joints relative to contralateral control joints. Combined, these data demonstrate the ability and sensitivity of magnetic capture for post-mortem analysis of OA biomarkers in the rat.

  10. A continuous stochastic model for non-equilibrium dense gases

    Science.gov (United States)

    Sadr, M.; Gorji, M. H.

    2017-12-01

    While accurate simulations of dense gas flows far from the equilibrium can be achieved by direct simulation adapted to the Enskog equation, the significant computational demand required for collisions appears as a major constraint. In order to cope with that, an efficient yet accurate solution algorithm based on the Fokker-Planck approximation of the Enskog equation is devised in this paper; the approximation is very much associated with the Fokker-Planck model derived from the Boltzmann equation by Jenny et al. ["A solution algorithm for the fluid dynamic equations based on a stochastic model for molecular motion," J. Comput. Phys. 229, 1077-1098 (2010)] and Gorji et al. ["Fokker-Planck model for computational studies of monatomic rarefied gas flows," J. Fluid Mech. 680, 574-601 (2011)]. The idea behind these Fokker-Planck descriptions is to project the dynamics of discrete collisions implied by the molecular encounters into a set of continuous Markovian processes subject to the drift and diffusion. Thereby, the evolution of particles representing the governing stochastic process becomes independent from each other and thus very efficient numerical schemes can be constructed. By close inspection of the Enskog operator, it is observed that the dense gas effects contribute further to the advection of molecular quantities. That motivates a modelling approach where the dense gas corrections can be cast in the extra advection of particles. Therefore, the corresponding Fokker-Planck approximation is derived such that the evolution in the physical space accounts for the dense effects present in the pressure, stress tensor, and heat fluxes. Hence the consistency between the devised Fokker-Planck approximation and the Enskog operator is shown for the velocity moments up to the heat fluxes. For validation studies, a homogeneous gas inside a box besides Fourier, Couette, and lid-driven cavity flow setups is considered. The results based on the Fokker-Planck model are

  11. The Voronoi volume and molecular representation of molar volume: equilibrium simple fluids.

    Science.gov (United States)

    Hunjan, Jagtar Singh; Eu, Byung Chan

    2010-04-07

    The Voronoi volume of simple fluids was previously made use of in connection with volume transport phenomena in nonequilibrium simple fluids. To investigate volume transport phenomena, it is important to develop a method to compute the Voronoi volume of fluids in nonequilibrium. In this work, as a first step to this goal, we investigate the equilibrium limit of the nonequilibrium Voronoi volume together with its attendant related molar (molal) and specific volumes. It is proved that the equilibrium Voronoi volume is equivalent to the molar (molal) volume. The latter, in turn, is proved equivalent to the specific volume. This chain of equivalences provides an alternative procedure of computing the equilibrium Voronoi volume from the molar volume/specific volume. We also show approximate methods of computing the Voronoi and molar volumes from the information on the pair correlation function. These methods may be employed for their quick estimation, but also provide some aspects of the fluid structure and its relation to the Voronoi volume. The Voronoi volume obtained from computer simulations is fitted to a function of temperature and pressure in the region above the triple point but below the critical point. Since the fitting function is given in terms of reduced variables for the Lennard-Jones (LJ) model and the kindred volumes (i.e., specific and molar volumes) are in essence equivalent to the equation of state, the formula obtained is a reduced equation state for simple fluids obeying the LJ model potential in the range of temperature and pressure examined and hence can be used for other simple fluids.

  12. Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences

    Directory of Open Access Journals (Sweden)

    Redzic Zoran

    2011-01-01

    Full Text Available Abstract Efficient processing of information by the central nervous system (CNS represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB, which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF barrier (BCSFB, which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC transport proteins at those two barriers and underlines

  13. Atoms in dense plasmas

    International Nuclear Information System (INIS)

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs

  14. Atoms in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  15. Molecular Analyses Reveal Inflammatory Mediators in the Solid Component and Cyst Fluid of Human Adamantinomatous Craniopharyngioma.

    Science.gov (United States)

    Donson, Andrew M; Apps, John; Griesinger, Andrea M; Amani, Vladimir; Witt, Davis A; Anderson, Richard C E; Niazi, Toba N; Grant, Gerald; Souweidane, Mark; Johnston, James M; Jackson, Eric M; Kleinschmidt-DeMasters, Bette K; Handler, Michael H; Tan, Aik-Choon; Gore, Lia; Virasami, Alex; Gonzalez-Meljem, Jose Mario; Jacques, Thomas S; Martinez-Barbera, Juan Pedro; Foreman, Nicholas K; Hankinson, Todd C

    2017-09-01

    Pediatric adamantinomatous craniopharyngioma (ACP) is a highly solid and cystic tumor, often causing substantial damage to critical neuroendocrine structures such as the hypothalamus, pituitary gland, and optic apparatus. Paracrine signaling mechanisms driving tumor behavior have been hypothesized, with IL-6R overexpression identified as a potential therapeutic target. To identify potential novel therapies, we characterized inflammatory and immunomodulatory factors in ACP cyst fluid and solid tumor components. Cytometric bead analysis revealed a highly pro-inflammatory cytokine pattern in fluid from ACP compared to fluids from another cystic pediatric brain tumor, pilocytic astrocytoma. Cytokines and chemokines with particularly elevated concentrations in ACPs were IL-6, CXCL1 (GRO), CXCL8 (IL-8) and the immunosuppressive cytokine IL-10. These data were concordant with solid tumor compartment transcriptomic data from a larger cohort of ACPs, other pediatric brain tumors and normal brain. The majority of receptors for these cytokines and chemokines were also over-expressed in ACPs. In addition to IL-10, the established immunosuppressive factor IDO-1 was overexpressed by ACPs at the mRNA and protein levels. These data indicate that ACP cyst fluids and solid tumor components are characterized by an inflammatory cytokine and chemokine expression pattern. Further study regarding selective cytokine blockade may inform novel therapeutic interventions. © 2017 American Association of Neuropathologists, Inc. All rights reserved.

  16. Molecular energy transfer by fluid mixing. Progress report, 1 January 1968--1 January 1971

    International Nuclear Information System (INIS)

    Cool, T.A.

    1971-01-01

    Highlights are discussed of a program on the use of rapid mixing techniques and high speed flows for laser power enhancement. Three tasks are reviewed: (1) continuous wave chemical laser development, (2) N 2 --CO 2 electrically excited fluid mixing laser techniques, and (3) gas dynamic mixing behind shock waves. Purely chemical HF and DF laser operation is also discussed

  17. Comparison of oral fluid collection methods for the molecular detection of hepatitis B virus.

    Science.gov (United States)

    Portilho, M M; Mendonça, Acf; Marques, V A; Nabuco, L C; Villela-Nogueira, C A; Ivantes, Cap; Lewis-Ximenez, L L; Lampe, E; Villar, L M

    2017-11-01

    This study aims to compare the efficiency of four oral fluid collection methods (Salivette, FTA Card, spitting and DNA-Sal) to detect HBV DNA by qualitative PCR. Seventy-four individuals (32 HBV reactive and 42 with no HBV markers) donated serum and oral fluid. In-house qualitative PCR to detect HBV was used for both samples and commercial quantitative PCR for serum. HBV DNA was detected in all serum samples from HBV-infected individuals, and it was not detected in control group. HBV DNA from HBV group was detected in 17 samples collected with Salivette device, 16 samples collected by FTA Card device, 16 samples collected from spitting and 13 samples collected by DNA-Sal device. Samples that corresponded to a higher viral load in their paired serum sample could be detected using all oral fluid collection methods, but Salivette collection device yielded the largest numbers of positive samples and had a wide range of viral load that was detected. It was possible to detect HBV DNA using all devices tested, but higher number of positive samples was observed when samples were collected using Salivette device, which shows high concordance to viral load observed in the paired serum samples. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Warm Dense Matter: An Overview

    International Nuclear Information System (INIS)

    Kalantar, D H; Lee, R W; Molitoris, J D

    2004-01-01

    This document provides a summary of the ''LLNL Workshop on Extreme States of Materials: Warm Dense Matter to NIF'' which was held on 20, 21, and 22 February 2002 at the Wente Conference Center in Livermore, CA. The warm dense matter regime, the transitional phase space region between cold material and hot plasma, is presently poorly understood. The drive to understand the nature of matter in this regime is sparking scientific activity worldwide. In addition to pure scientific interest, finite temperature dense matter occurs in the regimes of interest to the SSMP (Stockpile Stewardship Materials Program). So that obtaining a better understanding of WDM is important to performing effective experiments at, e.g., NIF, a primary mission of LLNL. At this workshop we examined current experimental and theoretical work performed at, and in conjunction with, LLNL to focus future activities and define our role in this rapidly emerging research area. On the experimental front LLNL plays a leading role in three of the five relevant areas and has the opportunity to become a major player in the other two. Discussion at the workshop indicated that the path forward for the experimental efforts at LLNL were two fold: First, we are doing reasonable baseline work at SPLs, HE, and High Energy Lasers with more effort encouraged. Second, we need to plan effectively for the next evolution in large scale facilities, both laser (NIF) and Light/Beam sources (LCLS/TESLA and GSI) Theoretically, LLNL has major research advantages in areas as diverse as the thermochemical approach to warm dense matter equations of state to first principles molecular dynamics simulations. However, it was clear that there is much work to be done theoretically to understand warm dense matter. Further, there is a need for a close collaboration between the generation of verifiable experimental data that can provide benchmarks of both the experimental techniques and the theoretical capabilities. The conclusion of this

  19. Quantum dense key distribution

    International Nuclear Information System (INIS)

    Degiovanni, I.P.; Ruo Berchera, I.; Castelletto, S.; Rastello, M.L.; Bovino, F.A.; Colla, A.M.; Castagnoli, G.

    2004-01-01

    This paper proposes a protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than the Bennet-Brassard 1984 protocol. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility

  20. Understanding hydration of Zn(2+) in hydrothermal fluids with ab initio molecular dynamics

    NARCIS (Netherlands)

    Liu, X.; Lu, X.; Wang, R.; Meijer, E.J.

    2011-01-01

    With ab initio molecular dynamics simulations, the free-energy profiles of hydrated Zn2+ are calculated for both gaseous and aqueous systems from ambient to supercritical conditions, and from the derived free-energy information, the speciation of hydrated Zn2+ has been revealed. It is shown that the

  1. On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

    KAUST Repository

    Skarmoutsos, Ioannis

    2018-05-15

    Force field based-Molecular dynamics simulations were deployed to systematically explore the dynamics of confined molecules of different shapes and sizes, i.e. linear (CO2 and N2) and spherical (CH4) fluids, in a model small pore system, i.e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour is reflected by the extremely slow decay of the Legendre reorientational correlation functions of even-parity order for the linear fluids which is associated to jump-like orientation flips, while the spherical fluid shows a very fast decay taking place in a sub-picosecond time scale. Such a fundamental understanding is relevant to diverse disciplines such as in chemistry, physics, biology and materials science where diatomic or polyatomic molecules of different shapes/sizes diffuse through nanopores.

  2. Comparisons of perturbation and integral equation theories for the angular pair correlation function in molecular fluids

    International Nuclear Information System (INIS)

    Murad, S.; Gubbins, K.E.; Gray, C.G.

    1983-01-01

    We compare several recently proposed theories for the angular pair correlation function g(rω 1 ω 2 ), including first- and second-order perturbation theory (the u-expansion), a Pade approximant to this series, first-order f-expansion, the single superchain, generalized mean field, linearized hypernetted chain, and quadratic hypernetted chain approximations. Numerical results from these theories are compared with available computer simulation data for four model fluids whose intermolecular pair potential is of the form u 0 +usub(a), where u 0 is a hard-sphere of Lennard-Jones model, while usub(a) is a dipole-dipole or quadrupole-quadrupole interaction; we refer to these model fluids as HS+μμ, HS+QQ, LJ+μμ, and LJ+QQ. Properties studied include the angular pair correlation function and its spherical harmonic components, the thermodynamic properties, and the angular correlation parameters G 1 and G 2 that are related to the dielectric and Kerr constants. The second-order perturbation theory is superior to the integral equation theories for the thermodynamic harmonics of g(rω 1 ω 2 ) and for the thermodynamic properties themselves at moderate multipole strengths. For other harmonics and properties, the integral equation theories are better, with the quadratic hypernetted chain approximation being the best overall. (orig.)

  3. Silver in geological fluids from in situ X-ray absorption spectroscopy and first-principles molecular dynamics

    Science.gov (United States)

    Pokrovski, Gleb S.; Roux, Jacques; Ferlat, Guillaume; Jonchiere, Romain; Seitsonen, Ari P.; Vuilleumier, Rodolphe; Hazemann, Jean-Louis

    2013-04-01

    The molecular structure and stability of species formed by silver in aqueous saline solutions typical of hydrothermal settings were quantified using in situ X-ray absorption spectroscopy (XAS) measurements, quantum-chemical modeling of near-edge absorption spectra (XANES) and extended fine structure spectra (EXAFS), and first-principles molecular dynamics (FPMD). Results show that in nitrate-bearing acidic solutions to at least 200 °C, silver speciation is dominated by the hydrated Ag+ cation surrounded by 4-6 water molecules in its nearest coordination shell with mean Ag-O distances of 2.32 ± 0.02 Å. In NaCl-bearing acidic aqueous solutions of total Cl concentration from 0.7 to 5.9 mol/kg H2O (m) at temperatures from 200 to 450 °C and pressures to 750 bar, the dominant species are the di-chloride complex AgCl2- with Ag-Cl distances of 2.40 ± 0.02 Å and Cl-Ag-Cl angle of 160 ± 10°, and the tri-chloride complex AgCl32- of a triangular structure and mean Ag-Cl distances of 2.60 ± 0.05 Å. With increasing temperature, the contribution of the tri-chloride species decreases from ˜50% of total dissolved Ag in the most concentrated solution (5.9m Cl) at 200 °C to less than 10-20% at supercritical temperatures for all investigated solutions, so that AgCl2- becomes by far the dominant Ag-bearing species at conditions typical of hydrothermal-magmatic fluids. Both di- and tri-chloride species exhibit outer-sphere interactions with the solvent as shown by the detection, using FPMD modeling, of H2O, Cl-, and Na+ at distances of 3-4 Å from the silver atom. The species fractions derived from XAS and FPMD analyses, and total AgCl(s) solubilities, measured in situ in this work from the absorption edge height of XAS spectra, are in accord with thermodynamic predictions using the stability constants of AgCl2- and AgCl32- from Akinfiev and Zotov (2001) and Zotov et al. (1995), respectively, which are based on extensive previous AgCl(s) solubility measurements. These data

  4. A History of constitutive modeling via molecular dynamics: Shock waves in fluids and gases

    OpenAIRE

    Holian B.L.

    2011-01-01

    From its inception in the mid-Fifties, the method of molecular-dynamics (MD) computer simulations has been used to probe the foundations of statistical mechanics, first for equilibrium equation-of-state averages, and then for transport properties from equilibrium fluctuations. Traditional statistical mechanical theoreticians were shocked to see that this new-fangled computational physics approach was feasible, even with incredibly tiny samples (on the order of a hundred atoms). When direct me...

  5. Thermodynamic and transport properties of nitrogen fluid: Molecular theory and computer simulations

    Science.gov (United States)

    Eskandari Nasrabad, A.; Laghaei, R.

    2018-04-01

    Computer simulations and various theories are applied to compute the thermodynamic and transport properties of nitrogen fluid. To model the nitrogen interaction, an existing potential in the literature is modified to obtain a close agreement between the simulation results and experimental data for the orthobaric densities. We use the Generic van der Waals theory to calculate the mean free volume and apply the results within the modified Cohen-Turnbull relation to obtain the self-diffusion coefficient. Compared to experimental data, excellent results are obtained via computer simulations for the orthobaric densities, the vapor pressure, the equation of state, and the shear viscosity. We analyze the results of the theory and computer simulations for the various thermophysical properties.

  6. Electric discharge microplasmas generated in highly fluctuating fluids: Characteristics and application to the synthesis of molecular diamond

    Science.gov (United States)

    Stauss, Sven

    2014-10-01

    Plasma-based fabrication of novel nanomaterials and nanostructures is paramount for the development of next-generation electronic devices and for green energy applications. In particular, controlling the interactions between plasmas and materials interfaces, and the plasma fluctuations are crucial for further development of plasma-based processes and bottom-up growth of nanomaterials. Discharge microplasmas generated in supercritical fluids represent a special class of high-pressure plasmas, where fluctuations on the molecular scale influence the discharge properties and the possible bottom-up growth of nanomaterials. In the first part of the talk, we will discuss an anomaly observed for microplasmas generated near the critical point, a local decrease in the breakdown voltage, which has been observed for both molecular and monoatomic gases. This anomalous behavior is suggested to be caused by the concomitant decrease of the ionization potential due to the formation of clusters near the critical point, and the formation of extended electron mean free paths induced by the high-density fluctuation near the critical point. We will also show that when generating microplasma discharges close to the critical point, that the high-density fluctuation of the supercritical fluid persists. In the second part of the presentation, we will first introduce the basic properties of diamondoids and their potential for application in many different fields - biotechnology, medicine, opto- and nanoelectronics - before discussing their synthesis by microplasmas generated inside both conventional batch-type and continuous flow reactors, using the smallest diamondoid, adamantane, as a precursor and seed. Finally we show that one possible growth mechanism of larger diamondoids from smaller ones consists in the repeated abstraction of hydrogen terminations and the addition of methyl radicals. Supported financially in part by Grant No. 23760688 and Grant No. 21110002 from the Ministry of

  7. Density distribution function of a self-gravitating isothermal compressible turbulent fluid in the context of molecular clouds ensembles

    Science.gov (United States)

    Donkov, Sava; Stefanov, Ivan Z.

    2018-03-01

    We have set ourselves the task of obtaining the probability distribution function of the mass density of a self-gravitating isothermal compressible turbulent fluid from its physics. We have done this in the context of a new notion: the molecular clouds ensemble. We have applied a new approach that takes into account the fractal nature of the fluid. Using the medium equations, under the assumption of steady state, we show that the total energy per unit mass is an invariant with respect to the fractal scales. As a next step we obtain a non-linear integral equation for the dimensionless scale Q which is the third root of the integral of the probability distribution function. It is solved approximately up to the leading-order term in the series expansion. We obtain two solutions. They are power-law distributions with different slopes: the first one is -1.5 at low densities, corresponding to an equilibrium between all energies at a given scale, and the second one is -2 at high densities, corresponding to a free fall at small scales.

  8. A FIRST LOOK AT THE AURIGA-CALIFORNIA GIANT MOLECULAR CLOUD WITH HERSCHEL AND THE CSO: CENSUS OF THE YOUNG STELLAR OBJECTS AND THE DENSE GAS

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Paul M. [Astronomy Department, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Fallscheer, Cassandra [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2 (Canada); Ginsburg, Adam [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States); Terebey, Susan [Department of Physics and Astronomy PS315, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Andre, Philippe; Koenyves, Vera [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d' Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Bourke, Tyler L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Di Francesco, James; Matthews, Brenda C. [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Peterson, Dawn E., E-mail: pmh@astro.as.utexas.edu, E-mail: Cassandra.Fallscheer@nrc-cnrc.gc.ca, E-mail: adam.ginsburg@colorado.edu, E-mail: sterebe@calstatela.edu, E-mail: pandre@cea.fr, E-mail: vera.konyves@cea.fr, E-mail: tbourke@cfa.harvard.edu, E-mail: James.DiFrancesco@nrc-cnrc.gc.ca, E-mail: Brenda.Matthews@nrc-cnrc.gc.ca, E-mail: dpeterson@spacescience.org [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80303 (United States)

    2013-02-20

    We have mapped the Auriga/California molecular cloud with the Herschel PACS and SPIRE cameras and the Bolocam 1.1 mm camera on the Caltech Submillimeter Observatory with the eventual goal of quantifying the star formation and cloud structure in this giant molecular cloud (GMC) that is comparable in size and mass to the Orion GMC, but which appears to be forming far fewer stars. We have tabulated 60 compact 70/160 {mu}m sources that are likely pre-main-sequence objects and correlated those with Spitzer and WISE mid-IR sources. At 1.1 mm, we find 18 cold, compact sources and discuss their properties. The most important result from this part of our study is that we find a modest number of additional compact young objects beyond those identified at shorter wavelengths with Spitzer. We also describe the dust column density and temperature structure derived from our photometric maps. The column density peaks at a few Multiplication-Sign 10{sup 22} cm{sup -2} (N {sub H2}) and is distributed in a clear filamentary structure along which nearly all of the pre-main-sequence objects are found. We compare the young stellar object surface density to the gas column density and find a strong nonlinear correlation between them. The dust temperature in the densest parts of the filaments drops to {approx}10 K from values {approx}14-15 K in the low-density parts of the cloud. We also derive the cumulative mass fraction and probability density function of material in the cloud, which we compare with similar data on other star-forming clouds.

  9. A FIRST LOOK AT THE AURIGA-CALIFORNIA GIANT MOLECULAR CLOUD WITH HERSCHEL AND THE CSO: CENSUS OF THE YOUNG STELLAR OBJECTS AND THE DENSE GAS

    International Nuclear Information System (INIS)

    Harvey, Paul M.; Fallscheer, Cassandra; Ginsburg, Adam; Terebey, Susan; André, Philippe; Könyves, Vera; Bourke, Tyler L.; Di Francesco, James; Matthews, Brenda C.; Peterson, Dawn E.

    2013-01-01

    We have mapped the Auriga/California molecular cloud with the Herschel PACS and SPIRE cameras and the Bolocam 1.1 mm camera on the Caltech Submillimeter Observatory with the eventual goal of quantifying the star formation and cloud structure in this giant molecular cloud (GMC) that is comparable in size and mass to the Orion GMC, but which appears to be forming far fewer stars. We have tabulated 60 compact 70/160 μm sources that are likely pre-main-sequence objects and correlated those with Spitzer and WISE mid-IR sources. At 1.1 mm, we find 18 cold, compact sources and discuss their properties. The most important result from this part of our study is that we find a modest number of additional compact young objects beyond those identified at shorter wavelengths with Spitzer. We also describe the dust column density and temperature structure derived from our photometric maps. The column density peaks at a few × 10 22 cm –2 (N H2 ) and is distributed in a clear filamentary structure along which nearly all of the pre-main-sequence objects are found. We compare the young stellar object surface density to the gas column density and find a strong nonlinear correlation between them. The dust temperature in the densest parts of the filaments drops to ∼10 K from values ∼14-15 K in the low-density parts of the cloud. We also derive the cumulative mass fraction and probability density function of material in the cloud, which we compare with similar data on other star-forming clouds.

  10. Synthetic model for Doppler broadening of neutron absorption resonances in molecular fluids

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, Alejandro J., E-mail: villanueva@cab.cnea.gov.a [Comision Nacional de Energia Atomica, Centro Atomico Bariloche and Instituto Balseiro, 8400 S.C. de Bariloche (RN) (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Granada, J.R. [Comision Nacional de Energia Atomica, Centro Atomico Bariloche and Instituto Balseiro, 8400 S.C. de Bariloche (RN) (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina)

    2010-08-15

    A general and systematic approach expressed in modern language, accounting for molecular motion effects on Doppler Broadening of Neutron Absorption Resonances (DBNAR) is given the form of a new model. It relies on well validated hypothesis: The separability of atomic from nuclear degrees of freedom, the use of the Van Hove scattering formalism and the fact that a conceptually identical approach produced experimentally proved predictions when applied to DBNAR in solid systems. We treat the molecular internal degrees of freedom approximately as harmonic oscillators. As a second contribution of this work, a synthetic model is presented in order to make the more complete model mentioned above suitable for neutron calculation codes. This second synthetic model reduces to the exact expressions of the complete model in the low and high neutron energy regimes and provides a plausible transition in between. Numerical results are presented for a general hypothetical case to show its strengths and limitations. Also, both models are applied to a real case of the {sup 238}U 6.674 eV resonant effective broadened absorption cross-section in UF6 (uranium hexafluoride). A direct experimental validation of our models is still necessary for which a special high resolution neutron transmission experiment ought to be devised at low temperatures and pressures on a gaseous system. It is showed how the synthetic model can be used to make thermometric predictions in an improved fashion in comparison to the effective temperature gas model at low temperatures.

  11. THE SPITZER c2d SURVEY OF NEARBY DENSE CORES: JET AND MOLECULAR OUTFLOW ASSOCIATED WITH A YOUNG STELLAR OBJECT IN CORE A OF L1251

    International Nuclear Information System (INIS)

    Lee, Jeong-Eun; Kim, Il-Suk; Choi, Yunhee; Lee, Ho-Gyu; Shinn, Jong-Ho; Dunham, Michael M.; Evans, Neal J.; Kim, Chang Hee; Bourke, Tyler L.

    2010-01-01

    A long infrared jet has been discovered by the Spitzer c2d Legacy Program in core A of L1251. It is associated with a very embedded Class 0 object with an accretion luminosity of about 0.9 L sun derived by radiative transfer model fitting to the observed spectral energy distribution. Comparing the observed Infrared Array Camera colors along the infrared jet with those calculated from a model of an admixture of gas with a power-law temperature distribution indicates that the jet is possibly created by a paraboloidal bow shock propagating into the ambient medium of n(H 2 ) = 10 5 cm -3 . In addition, the variation of the power-law index along the jet suggests that the portion of hot gas decreases with distance from the jet engine. The molecular outflow in this region has been mapped for the first time using CO data. From the calculated outflow momentum flux, a very strong lower limit to the average accretion luminosity is 3.6 sin i/cos 3 i L sun , indicative of a decrease in the accretion rate with time.

  12. Molecular simulation of CO chemisorption on Co(0001) in presence of supercritical fluid solvent: A potential of mean force study

    Energy Technology Data Exchange (ETDEWEB)

    Asiaee, Alireza; Benjamin, Kenneth M., E-mail: kenneth.benjamin@sdsmt.edu [Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, South Dakota 57701 (United States)

    2016-08-28

    For several decades, heterogeneous catalytic processes have been improved through utilizing supercritical fluids (SCFs) as solvents. While numerous experimental studies have been established across a range of chemistries, such as oxidation, pyrolysis, amination, and Fischer-Tropsch synthesis, still there is little fundamental, molecular-level information regarding the role of the SCF on elementary heterogeneous catalytic steps. In this study, the influence of hexane solvent on the adsorption of carbon monoxide on Co(0001), as the first step in the reaction mechanism of many processes involving syngas conversion, is probed. Simulations are performed at various bulk hexane densities, ranging from ideal gas conditions (no SCF hexane) to various near- and super-critical hexane densities. For this purpose, both density functional theory and molecular dynamics simulations are employed to determine the adsorption energy and free energy change during CO chemisorption. Potential of mean force calculations, utilizing umbrella sampling and the weighted histogram analysis method, provide the first commentary on SCF solvent effects on the energetic aspects of the chemisorption process. Simulation results indicate an enhanced stability of CO adsorption on the catalyst surface in the presence of supercritical hexane within the reduced pressure range of 1.0–1.5 at a constant temperature of 523 K. Furthermore, it is shown that the maximum stability of CO in the adsorbed state as a function of supercritical hexane density at 523 K nearly coincides with the maximum isothermal compressibility of bulk hexane at this temperature.

  13. Dense Deposit Disease Mimicking a Renal Small Vessel Vasculitis

    Science.gov (United States)

    Singh, Lavleen; Bhardwaj, Swati; Sinha, Aditi; Bagga, Arvind; Dinda, Amit

    2016-01-01

    Dense deposit disease is caused by fluid-phase dysregulation of the alternative complement pathway and frequently deviates from the classic membranoproliferative pattern of injury on light microscopy. Other patterns of injury described for dense deposit disease include mesangioproliferative, acute proliferative/exudative, and crescentic GN. Regardless of the histologic pattern, C3 glomerulopathy, which includes dense deposit disease and C3 GN, is defined by immunofluorescence intensity of C3c two or more orders of magnitude greater than any other immune reactant (on a 0–3 scale). Ultrastructural appearances distinguish dense deposit disease and C3 GN. Focal and segmental necrotizing glomerular lesions with crescents, mimicking a small vessel vasculitis such as ANCA-associated GN, are a very rare manifestation of dense deposit disease. We describe our experience with this unusual histologic presentation and distinct clinical course of dense deposit disease, discuss the pitfalls in diagnosis, examine differential diagnoses, and review the relevant literature. PMID:26361799

  14. Immunodiagnosis and molecular validation of Toxoplasma gondii-recombinant dense granular (GRA) 7 protein for the detection of toxoplasmosis in patients with cancer.

    Science.gov (United States)

    Arab-Mazar, Zahra; Fallahi, Shirzad; Koochaki, Ameneh; Haghighi, Ali; Seyyed Tabaei, Seyyed Javad

    2016-02-01

    Serological assays for the diagnosis of toxoplasmosis mostly rely on the tachyzoite specific antigens of Toxoplasma gondii, which are difficult to produce by conventional methods. The aim of this study was to clone and express of GRA7 protein of T. gondii and evaluate its potential for immunodiagnosis of toxoplasmosis in cancer patients. As well as validate the results using a new molecular assay, LAMP technique. The GRA7 gene was successfully cloned, expressed and purified by affinity chromatography and the production was evaluated by SDS PAGE, dot blot and western blot analyses. The rGRA7 was used for developing an ELISA based on the rGRA7 using sera from patients with toxoplasmosis and healthy controls. Furthermore, 50 serum samples from leukemic children infected with toxoplasmosis and 50 seronegative controls were included to evaluate the sensitivity and specificity of rGRA7 based ELISA. Finally, the LAMP technique was used to assess the accuracy and validity of the results obtained by rGRA7 based ELISA. The consistency of the results of two tests was determined by using the Kappa coefficient of agreement. The rGRA7 showed higher and optimum immunoreactivity with 1:100 dilution of serum from Toxoplasma infected patients. The sensitivity and specificity of test were calculated as 92 and 94%, respectively. According to the Kappa coefficient of agreement, there was a significant conformance between the results obtained by ELISA based on the rGRA7 and the results of LAMP technique (≈96%, Ptoxoplasmosis in patients including patients with cancer. Copyright © 2015. Published by Elsevier GmbH.

  15. Molecular identification of bacteria in tracheal aspirate fluid from mechanically ventilated preterm infants.

    Directory of Open Access Journals (Sweden)

    Peter M Mourani

    Full Text Available BACKGROUND: Despite strong evidence linking infections to the pathogenesis of bronchopulmonary dysplasia (BPD, limitations of bacterial culture methods have precluded systematic studies of airway organisms relative to disease outcomes. Application of molecular bacterial identification strategies may provide new insight into the role of bacterial acquisition in the airways of preterm infants at risk for BPD. METHODS: Serial (within 72 hours, 7, 14, and 21 days of life tracheal aspirate samples were collected from 10 preterm infants with gestational age ≤34 weeks at birth, and birth weight of 500-1250 g who required mechanical ventilation for at least 21 days. Samples were analyzed by quantitative real time PCR assays for total bacterial load and by pyrosequencing for bacterial identification. RESULTS: Subjects were diagnosed with mild (1, moderate (3, or severe (5 BPD. One patient died prior to determination of disease severity. 107,487 sequences were analyzed, with mean of 3,359 (range 1,724-4,915 per sample. 2 of 10 samples collected 70copies/reaction. 72 organisms were observed in total. Seven organisms represented the dominant organism (>50% of total sequences in 31/32 samples with positive sequences. A dominant organism represented>90% of total sequences in 13 samples. Staphylococcus, Ureaplasmaparvum, and Ureaplasmaurealyticum were the most frequently identified dominant organisms, but Pseudomonas, Enterococcus, and Escherichia were also identified. CONCLUSIONS: Early bacterial colonization with diverse species occursafter the first 3 days of life in the airways of intubated preterm infants, and can be characterized by bacterial load and marked species diversity. Molecular identification of bacteria in the lower airways of preterm infants has the potential to yield further insight into the pathogenesis of BPD.

  16. Unrevealing Parasitic Trophic Interactions—A Molecular Approach for Fluid-Feeding Fishes

    Directory of Open Access Journals (Sweden)

    Karine O. Bonato

    2018-03-01

    Full Text Available Fish diets have been traditionally studied through the direct visual identification of food items found in their stomachs. Stomach contents of Vandeliinae and Stegophilinae (family Trichomycteridae parasite catfishes, however, cannot be identified by usual optical methods due to their mucophagic, lepidophagic, or hematophagic diets, in such a way that the trophic interactions and the dynamics of food webs in aquatic systems involving these catfishes are mostly unknown. The knowledge about trophic interactions, including difficult relation between parasites and hosts, are crucial to understand the whole working of food webs. In this way, molecular markers can be useful to determine the truly hosts of these catfishes, proving a preference in their feeding behavior for specific organisms and not a generalist. Sequences of cytochrome oxidase subunit 1 (COI were successfully extracted and amplified from mucus or scales found in the stomach contents of two species of stegophilines, Homodiaetus anisitsi, and Pseudostegophilus maculatus, to identify the host species. The two species were found to be obligatory mucus-feeders and occasionally lepidophagic. Selection of host species is associated to host behavior, being constituted mainly by substrate-sifting benthivores. Characiformes are preferred hosts, but host choice depends on what characiform species are available in their environments, usually corresponding to the most abundant species. This is the first time that host species of parasitic fishes bearing mucophagous habits are identified, and demonstrates the effectiveness of the extraction and amplification of mitochondrial DNA from the ingested mucus in gut contents. The molecular markers effectively allowed determine parasite preferences and helps in better understanding the food web and trophic interaction on which fish species are involved. Despite, the methodology applied here can be used for an infinitive of organisms improving ecological

  17. Chemical association in simple models of molecular and ionic fluids. III. The cavity function

    Science.gov (United States)

    Zhou, Yaoqi; Stell, George

    1992-01-01

    Exact equations which relate the cavity function to excess solvation free energies and equilibrium association constants are rederived by using a thermodynamic cycle. A zeroth-order approximation, derived previously by us as a simple interpolation scheme, is found to be very accurate if the associative bonding occurs on or near the surface of the repulsive core of the interaction potential. If the bonding radius is substantially less than the core radius, the approximation overestimates the association degree and the association constant. For binary association, the zeroth-order approximation is equivalent to the first-order thermodynamic perturbation theory (TPT) of Wertheim. For n-particle association, the combination of the zeroth-order approximation with a ``linear'' approximation (for n-particle distribution functions in terms of the two-particle function) yields the first-order TPT result. Using our exact equations to go beyond TPT, near-exact analytic results for binary hard-sphere association are obtained. Solvent effects on binary hard-sphere association and ionic association are also investigated. A new rule which generalizes Le Chatelier's principle is used to describe the three distinct forms of behaviors involving solvent effects that we find. The replacement of the dielectric-continuum solvent model by a dipolar hard-sphere model leads to improved agreement with an experimental observation. Finally, equation of state for an n-particle flexible linear-chain fluid is derived on the basis of a one-parameter approximation that interpolates between the generalized Kirkwood superposition approximation and the linear approximation. A value of the parameter that appears to be near optimal in the context of this application is obtained from comparison with computer-simulation data.

  18. Modelling dense relational data

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard

    2012-01-01

    they are not naturally suited for kernel K-means. We propose a generative Bayesian model for dense matrices which generalize kernel K-means to consider off-diagonal interactions in matrices of interactions, and demonstrate its ability to detect structure on both artificial data and two real data sets....

  19. Is dense codeswitching complex?

    NARCIS (Netherlands)

    Dorleijn, M.

    In this paper the question is raised to what extent dense code switching can be considered complex. Psycholinguistic experiments indicate that code switching involves cognitive costs, both in production and comprehension, a conclusion that could indicate that code switching is indeed complex. In

  20. Simulation of dense colloids

    NARCIS (Netherlands)

    Herrmann, H.J.; Harting, J.D.R.; Hecht, M.; Ben-Naim, E.

    2008-01-01

    We present in this proceeding recent large scale simulations of dense colloids. On one hand we simulate model clay consisting of nanometric aluminum oxide spheres in water using realistic DLVO potentials and a combination of MD and SRD. We find pronounced cluster formation and retrieve the shear

  1. Theory for site-site pair distribution functions of molecular fluids. II. Approximations for the Percus--Yevick site-site direct correlation functions

    International Nuclear Information System (INIS)

    Johnson, E.

    1977-01-01

    A theory for site-site pair distribution functions of molecular fluids is derived from the Ornstein-Zernike equation. Atom-atom pair distribution functions of this theory which were obtained by using different approximations for the Percus-Yevick site-site direct correlation functions are compared

  2. Collision frequency of Lennard-Jones fluids at high densities by equilibrium molecular dynamics simulation

    International Nuclear Information System (INIS)

    Adebayo, G.A.; Anusionwu, B.C.; Njah, A.N.; Adeniran, O.J.; Mathew, B.; Sunmonu, R.S.

    2009-01-01

    Arising from the inability of theoretical calculations to give accurate descriptions of (shear) viscosity in rare gases at high densities, we investigated the likely cause of discrepancy between theory and experiments. Molecular Dynamics simulations were performed to calculate transport coefficients and collision frequency of rare gases at high densities and different temperatures using a Lennard-Jones modelled pair potential. The results, when compared with experiments show an underestimation of the viscosity calculated through the Green-Kubo formalism, but in agreement with some other calculations performed by other groups. In the present work the origin of the underestimation is considered. Analyses of the transport coefficients show a very high collision frequency which suggests an atom may spend much less time in the neighbourhood of the fields of force of another atom and that the distribution in the systems studied adjusts itself to a nearly Maxwellian type which resulted in a locally and temporarily slowly varying temperature. We show that the time spent in the fields of force is so small compared with relaxation time thereby leading to a possible reduction in local velocity auto-correlation between atoms. (author)

  3. Molecularly imprinted polymer-based bulk optode for the determination of itopride hydrochloride in physiological fluids.

    Science.gov (United States)

    Abdel-Haleem, F M; Madbouly, Adel; El Nashar, R M; Abdel-Ghani, N T

    2016-11-15

    We report here for the first time on the use of Molecularly Imprinted Polymers as modifiers in bulk optodes, Miptode, for the determination of a pharmaceutical compound, itopride hydrochloride as an example in a concentration range of 1×10(-1)-1×10(-4)molL(-1). In comparison to the optode containing the ion exchanger only (Miptode 3), the optode containing the ion exchanger and the MIP particles (Miptode 2) showed improved selectivity over the most lipophilic species, Na(+) and K(+), by more than two orders of magnitude. For instance, the optical selectivity coefficients using Miptode 2, [Formula: see text] , were as follow: NH4(+)˂-6; Na(+)=-4.0, which were greatly enhanced in comparison with that obtained by Miptode 3. This work opens a new avenue for using miptodes for the determination of all the pharmaceutical preparations without the need for the development of new ionophores. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Bayesian quantification of thermodynamic uncertainties in dense gas flows

    International Nuclear Information System (INIS)

    Merle, X.; Cinnella, P.

    2015-01-01

    A Bayesian inference methodology is developed for calibrating complex equations of state used in numerical fluid flow solvers. Precisely, the input parameters of three equations of state commonly used for modeling the thermodynamic behavior of the so-called dense gas flows, – i.e. flows of gases characterized by high molecular weights and complex molecules, working in thermodynamic conditions close to the liquid–vapor saturation curve – are calibrated by means of Bayesian inference from reference aerodynamic data for a dense gas flow over a wing section. Flow thermodynamic conditions are such that the gas thermodynamic behavior strongly deviates from that of a perfect gas. In the aim of assessing the proposed methodology, synthetic calibration data – specifically, wall pressure data – are generated by running the numerical solver with a more complex and accurate thermodynamic model. The statistical model used to build the likelihood function includes a model-form inadequacy term, accounting for the gap between the model output associated to the best-fit parameters and the true phenomenon. Results show that, for all of the relatively simple models under investigation, calibrations lead to informative posterior probability density distributions of the input parameters and improve the predictive distribution significantly. Nevertheless, calibrated parameters strongly differ from their expected physical values. The relationship between this behavior and model-form inadequacy is discussed. - Highlights: • Development of a Bayesian inference procedure for calibrating dense-gas flow solvers. • Complex thermodynamic models calibrated by using aerodynamic data for the flow. • Preliminary Sobol analysis used to reduce parameter space. • Piecewise polynomial surrogate model constructed to reduce computational cost. • Calibration results show the crucial role played by model-form inadequacies

  5. Atomistic Modeling of the Fluid-Solid Interface in Simple Fluids

    Science.gov (United States)

    Hadjiconstantinou, Nicolas; Wang, Gerald

    2017-11-01

    Fluids can exhibit pronounced structuring effects near a solid boundary, typically manifested in a layered structure that has been extensively shown to directly affect transport across the interface. We present and discuss several results from molecular-mechanical modeling and molecular-dynamics (MD) simulations aimed at characterizing the structure of the first fluid layer directly adjacent to the solid. We identify a new dimensionless group - termed the Wall number - which characterizes the degree of fluid layering, by comparing the competing effects of wall-fluid interaction and thermal energy. We find that in the layering regime, several key features of the first layer layer - including its distance from the solid, its width, and its areal density - can be described using mean-field-energy arguments, as well as asymptotic analysis of the Nernst-Planck equation. For dense fluids, the areal density and the width of the first layer can be related to the bulk fluid density using a simple scaling relation. MD simulations show that these results are broadly applicable and robust to the presence of a second confining solid boundary, different choices of wall structure and thermalization, strengths of fluid-solid interaction, and wall geometries.

  6. Densely crosslinked polycarbosiloxanes .2. Thermal and mechanical properties

    NARCIS (Netherlands)

    Flipsen, T.A C; Derks, R.; van der Vegt, H.A.; Stenekes, R.; Pennings, A.J; Hadziioannou, G

    1997-01-01

    The thermal and mechanical properties of two densely crosslinked polycarbosiloxane systems were investigated in relation to the molecular structure. The networks were prepared from functional branched prepolymers and crosslinked via a hydrosilylation curing reaction. The prepolymers having only

  7. Atoms in dense plasmas

    International Nuclear Information System (INIS)

    More, R.M.

    1987-01-01

    This paper covers some aspects of the theory of atomic processes in dense plasmas. Because the topic is very broad, a few general rules which give useful guidance about the typical behavior of dense plasmas have been selected. These rules are illustrated by semiclassical estimates, scaling laws and appeals to more elaborate calculations. Included in the paper are several previously unpublished results including a new mechanism for electron-ion heat exchange (section II), and an approximate expression for oscillator-strengths of highly charged ions (section V). However the main emphasis is not upon practical formulas but rather on questions of fundamental theory, the structural ingredients which must be used in building a model for plasma events. What are the density effects and how does one represent them? Which are most important? How does one identify an incorrect theory? The general rules help to answer these questions. 106 references, 23 figures, 2 tables

  8. Dense Plasma Focus Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Li, Shengtai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jungman, Gerard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hayes-Sterbenz, Anna Catherine [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-31

    The mechanisms for pinch formation in Dense Plasma Focus (DPF) devices, with the generation of high-energy ions beams and subsequent neutron production over a relatively short distance, are not fully understood. Here we report on high-fidelity 2D and 3D numerical magnetohydrodynamic (MHD) simulations using the LA-COMPASS code to study the pinch formation dynamics and its associated instabilities and neutron production.

  9. Algorithms for GPU-based molecular dynamics simulations of complex fluids: Applications to water, mixtures, and liquid crystals.

    Science.gov (United States)

    Kazachenko, Sergey; Giovinazzo, Mark; Hall, Kyle Wm; Cann, Natalie M

    2015-09-15

    A custom code for molecular dynamics simulations has been designed to run on CUDA-enabled NVIDIA graphics processing units (GPUs). The double-precision code simulates multicomponent fluids, with intramolecular and intermolecular forces, coarse-grained and atomistic models, holonomic constraints, Nosé-Hoover thermostats, and the generation of distribution functions. Algorithms to compute Lennard-Jones and Gay-Berne interactions, and the electrostatic force using Ewald summations, are discussed. A neighbor list is introduced to improve scaling with respect to system size. Three test systems are examined: SPC/E water; an n-hexane/2-propanol mixture; and a liquid crystal mesogen, 2-(4-butyloxyphenyl)-5-octyloxypyrimidine. Code performance is analyzed for each system. With one GPU, a 33-119 fold increase in performance is achieved compared with the serial code while the use of two GPUs leads to a 69-287 fold improvement and three GPUs yield a 101-377 fold speedup. © 2015 Wiley Periodicals, Inc.

  10. A molecular Debye-Hückel theory of solvation in polar fluids: An extension of the Born model

    Science.gov (United States)

    Xiao, Tiejun; Song, Xueyu

    2017-12-01

    A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. Our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.

  11. WARM EXTENDED DENSE GAS AT THE HEART OF A COLD COLLAPSING DENSE CORE

    International Nuclear Information System (INIS)

    Shinnaga, Hiroko; Phillips, Thomas G.; Furuya, Ray S.; Kitamura, Yoshimi

    2009-01-01

    In order to investigate when and how the birth of a protostellar core occurs, we made survey observations of four well-studied dense cores in the Taurus molecular cloud using CO transitions in submillimeter bands. We report here the detection of unexpectedly warm (∼30-70 K), extended (radius of ∼2400 AU), dense (a few times 10 5 cm -3 ) gas at the heart of one of the dense cores, L1521F (MC27), within the cold dynamically collapsing components. We argue that the detected warm, extended, dense gas may originate from shock regions caused by collisions between the dynamically collapsing components and outflowing/rotating components within the dense core. We propose a new stage of star formation, 'warm-in-cold core stage (WICCS)', i.e., the cold collapsing envelope encases the warm extended dense gas at the center due to the formation of a protostellar core. WICCS would constitute a missing link in evolution between a cold quiescent starless core and a young protostar in class 0 stage that has a large-scale bipolar outflow.

  12. Changes of synovial fluid protein concentrations in supra-patellar bursitis patients after the injection of different molecular weights of hyaluronic acid.

    Science.gov (United States)

    Chen, Carl P C; Hsu, Chih Chin; Pei, Yu-Cheng; Chen, Ruo Li; Zhou, Shaobo; Shen, Hsuan-Chen; Lin, Shih-Cherng; Tsai, Wen Chung

    2014-04-01

    Knee pain is commonly seen in orthopedic and rehabilitation outpatient clinical settings, and in the aging population. Bursitis of the knee joint, especially when the volume of the synovial fluid is large enough, can compress and distend the nearby soft tissues, causing pain in the knee joint. Out of all the bursae surrounding the knee joint, supra-patellar bursitis is most often associated with knee pain. Treatment strategies in managing supra-patellar bursitis include the aspiration of joint synovial fluid and then followed by steroid injection into the bursa. When supra-patellar bursitis is caused by degenerative disorders, the concept of viscosupplementation treatment may be effective by injecting hyaluronic acid into the bursa. However, the rheology or the changes in the concentrations of proteins (biomarkers) that are related to the development of bursitis in the synovial fluid is virtually unexplored. Therefore, this study aimed to identify the concentration changes in the synovial fluid total protein amount and individual proteins associated with supra-patellar bursitis using the Bradford protein assay and western immunoglobulin methods. A total of 20 patients were divided into two groups with 10 patients in each group. One group received the high molecular weight hyaluronic acid product of Synvisc Hylan G-F 20 and the other group received the low molecular weight hyaluronic acid product of Hya-Joint Synovial Fluid Supplement once per week injection into the bursa for a total of 3 weeks. Significant decreases in the synovial fluid total protein concentrations were observed after the second dosage of high molecular weight hyaluronic acid injections. Apolipoprotein A-I, interleukin 1 beta, alpha 1 antitrypsin, and matrix metalloproteinase 1 proteins revealed a trend of decreasing western immunoblotting band densities after hyaluronic acid injections. The decreases in apolipoprotein A-I and interleukin 1 beta protein band densities were significant in the high

  13. Adapting SAFT-γ perturbation theory to site-based molecular dynamics simulation. II. Confined fluids and vapor-liquid interfaces

    Science.gov (United States)

    Ghobadi, Ahmadreza F.; Elliott, J. Richard

    2014-07-01

    In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-γ WCA EOS and selective applications are studied for confined fluids and vapor-liquid interfaces. The acronym WCA (Weeks-Chandler-Andersen) refers to the characterization of the reference part of the third-order thermodynamic perturbation theory applied in formulating the EOS. SAFT-γ refers to the particular form of "statistical associating fluid theory" that is applied to the fused-sphere, heteronuclear, united-atom molecular models of interest. For the monomer term, the modified fundamental measure theory is extended to WCA-spheres. A new chain functional is also introduced for fused and soft heteronuclear chains. The attractive interactions are taken into account by considering the structure of the fluid, thus elevating the theory beyond the mean field approximation. The fluctuations of energy are also included via a non-local third-order perturbation theory. The theory includes resolution of the density profiles of individual groups such as CH2 and CH3 and satisfies stoichiometric constraints for the density profiles. New molecular simulations are conducted to demonstrate the accuracy of each Helmholtz free energy contribution in reproducing the microstructure of inhomogeneous systems at the united-atom level of coarse graining. At each stage, comparisons are made to assess where the present theory stands relative to the current state of the art for studying inhomogeneous fluids. Overall, it is shown that the characteristic features of real molecular fluids are captured both qualitatively and quantitatively. For example, the average pore density deviates ˜2% from simulation data for attractive pentadecane in a 2-nm slit pore. Another example is the surface tension of ethane/heptane mixture, which deviates ˜1% from simulation data while the theory reproduces the excess

  14. Adapting SAFT-γ perturbation theory to site-based molecular dynamics simulation. II. Confined fluids and vapor-liquid interfaces

    International Nuclear Information System (INIS)

    Ghobadi, Ahmadreza F.; Elliott, J. Richard

    2014-01-01

    In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-γ WCA EOS and selective applications are studied for confined fluids and vapor-liquid interfaces. The acronym WCA (Weeks-Chandler-Andersen) refers to the characterization of the reference part of the third-order thermodynamic perturbation theory applied in formulating the EOS. SAFT-γ refers to the particular form of “statistical associating fluid theory” that is applied to the fused-sphere, heteronuclear, united-atom molecular models of interest. For the monomer term, the modified fundamental measure theory is extended to WCA-spheres. A new chain functional is also introduced for fused and soft heteronuclear chains. The attractive interactions are taken into account by considering the structure of the fluid, thus elevating the theory beyond the mean field approximation. The fluctuations of energy are also included via a non-local third-order perturbation theory. The theory includes resolution of the density profiles of individual groups such as CH 2 and CH 3 and satisfies stoichiometric constraints for the density profiles. New molecular simulations are conducted to demonstrate the accuracy of each Helmholtz free energy contribution in reproducing the microstructure of inhomogeneous systems at the united-atom level of coarse graining. At each stage, comparisons are made to assess where the present theory stands relative to the current state of the art for studying inhomogeneous fluids. Overall, it is shown that the characteristic features of real molecular fluids are captured both qualitatively and quantitatively. For example, the average pore density deviates ∼2% from simulation data for attractive pentadecane in a 2-nm slit pore. Another example is the surface tension of ethane/heptane mixture, which deviates ∼1% from simulation data while the theory reproduces

  15. Dense ceramic articles

    International Nuclear Information System (INIS)

    Cockbain, A.G.

    1976-01-01

    A method is described for the manufacture of articles of substantially pure dense ceramic materials, for use in severe environments. Si N is very suitable for use in such environments, but suffers from the disadvantage that it is not amenable to sintering. Some disadvantages of the methods normally used for making articles of Si N are mentioned. The method described comprises mixing a powder of the substantially pure ceramic material with an additive that promotes densification, and which is capable of nuclear transmutation into a gas when exposed to radiation, and hot pressing the mixture to form a billet. The billet is then irradiated to convert the additive into a gas which is held captive in the billet, and it is then subjected to a hot forging operation, during which the captive gas escapes and an article of substantially pure dense ceramic material is forged. The method is intended primarily for use for Si N, but may be applied to other ceramic materials. The additive may be Li or Be or their compounds, to the extent of at least 5 ppm and not more than 5% by weight. Irradiation is effected by proton or neutron bombardment. (UK)

  16. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  17. Thermodynamic properties of fluids from Fluctuation Solution Theory

    International Nuclear Information System (INIS)

    O'Connell, J.P.

    1990-01-01

    Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested

  18. On the Brownian motion of a massive sphere suspended in a hard-sphere fluid. II. Molecular dynamics estimates of the friction coefficient

    International Nuclear Information System (INIS)

    Bocquet, L.; Hansen, J.P.; Piasecki, J.

    1994-01-01

    The friction coefficient γ exerted by a hard-sphere fluid on an infinitely massive Brownian sphere is calculated for several size ratios Σ/σ where Σ and σ are the diameters of the Brownian and fluid spheres, respectively. The exact microscopic expression derived in part I of this work from kinetic theory is transformed and shown to be proportional to the time integral of the autocorrelation function of the momentum transferred from the fluid to the Brownian sphere during instantaneous collisions. Three different methods are described to extract the friction coefficient from molecular dynamics simulations carried out on finite systems. The three independent methods lead to estimates of γ which agree within statistical errors (typically 5%). The results are compared to the predictions of Enskog theory and of the hydrodynamic Stokes law. The former breaks down as the size ratio and/or the packing fraction of the fluid increase. Somewhat surprisingly, Stokes' law is found to hold with stick boundary conditions, in the range 1 ≤ Σ/σ ≤ 4.5 explored in the present simulations, with a hydrodynamic diameter d=Σ. The analysis of the molecular dynamics data on the basis of Stokes' law with slip boundary conditions is less conclusive, although the right trend is found as Σ/σ increases

  19. Atomic physics in dense plasmas. Recent advances

    International Nuclear Information System (INIS)

    Leboucher-Dalimier, E.; Angelo, P.; Ceccotti, T.; Derfoul, H.; Poquerusse, A.; Sauvan, P.; Oks, E.

    2000-01-01

    This paper presents observations and simulations of novel density-dependent spectroscopic features in hot and dense plasmas. Both time-integrated and time-resolved results using ultra-high resolutions spectrometers are presented; they are justified within the standard spectral line shape theory or the quasi-molecular alternative treatment. A particular attention is paid to the impact of the spatio-temporal evolution of the plasma on the experimental spectra. Satellite-like features and molecular lines in the cases of Flyβ, Heβ are discussed emphasizing their importance for the density diagnostics when ion-ion correlations are significant. (authors)

  20. The influence of polyanion molecular weight on polyelectrolyte multilayers at surfaces: elasticity and susceptibility to saloplasticity of strongly dissociated synthetic polymers at fluid-fluid interfaces.

    Science.gov (United States)

    Cramer, Ashley D; Dong, Wen-Fei; Benbow, Natalie L; Webber, Jessie L; Krasowska, Marta; Beattie, David A; Ferri, James K

    2017-09-13

    We studied the interfacial mechanical properties of polyelectrolyte multilayer assemblies of poly(diallylamine hydrochloride) (PAH) and poly(4-styrenesulfonate)sodium salt (PSS) at the air-water interface using axisymmetric drop shape analysis (ADSA) during hydrostatic inflation as a function of aqueous salt concentration and two different polyanion molecular weights (M w ∼ 13 and 70 kDa). Surface elastic moduli (G s ) ranged from 50 to 300 mN m -1 . Using the measured film thickness, the bulk moduli (G) ranged from 10 to 90 MPa consistent with elastomeric solids. This solid-like interface was evidenced by a systematic departure of the inflated shape from the Young-Laplace equation, which assumes a liquid-like interface. Surface elastic moduli increased and bulk elastic moduli decreased with increasing nanomembrane transverse dimension, and multilayers with the lower molecular weight anion were more transversely compact than those of higher molecular weight and displayed a larger elastic modulus. The bulk moduli of both types of multilayer assemblies asymptotically approach a constant value for films with more than two bilayers of polyelectrolyte, consistent with the observed transition from a 'glassy' to 'rubbery' state. Both types of multilayer assemblies displayed plasticization with increasing sodium chloride concentration in the adjoining aqueous phase, i.e. saloplasticity, and exhibited a transition from elastic to plastic response to deformation. The restored mobility of the polyelectrolyte resulting from the shift from intrinsic to extrinsic charge complexation, restores fluidity to the interface and is evidenced by experimental observation of a liquid-like interface when loaded. The higher molecular weight polyanion multilayers plasticized at lower salt concentrations suggesting that the lower melting point of the higher molecular weight polyanion assembly is attributable to a lesser extent of electrostatic cross-linking underscoring the unconventional

  1. Hyperons in dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Dapo, Haris

    2009-01-28

    The hyperon-nucleon YN low momentum effective interaction (V{sub low} {sub k}) allows for an extensive study of the behavior of hyperons in dense matter, together with an investigation of effects of the presence of hyperons on dense matter. The first step towards this goal is the construction of the matrix elements for the hyperon-nucleon low momentum potential. In order to assess the different properties of hyperons within these potentials we calculate the hyperon single-particle potentials in the Hartree-Fock approximation for all of the interactions. Their dependence on both momentum and density, is studied. The single-particle potentials are then used to determine the chemical potential of hyperons in neutron stars. For nucleonic properties, the nucleon-nucleon V{sub low} {sub k} can be used with the caveat that the calculation of the ground-state energy of symmetric nuclear matter does not correctly reproduce the properties of matter at saturation. With the nucleon-nucleon V{sub low} {sub k} one is unable to reach the densities needed for the calculation of neutron star masses. To circumvent this problem we use two approaches: in the first one, we parametrize the entire nucleonic sector. In the second one, we replace only the three-body force. The former will enable us to study neutron star masses, and the latter for studying the medium's response to the external probe. In this thesis we take the external probe to be the neutrino. By combining this parametrization with the YN V{sub low} {sub k} potential, we calculate the equation of state of equilibrated matter. Performing the calculation in the Hartree-Fock approximation at zero temperature, the concentrations of all particles are calculated. From these we can ascertain at which densities hyperons appear for a wide range of parameters. Finally, we calculate the masses of neutron stars with these concentrations. For the calculation of the medium's response to an external probe, we replace the three

  2. Hyperons in dense matter

    International Nuclear Information System (INIS)

    Dapo, Haris

    2009-01-01

    The hyperon-nucleon YN low momentum effective interaction (V low k ) allows for an extensive study of the behavior of hyperons in dense matter, together with an investigation of effects of the presence of hyperons on dense matter. The first step towards this goal is the construction of the matrix elements for the hyperon-nucleon low momentum potential. In order to assess the different properties of hyperons within these potentials we calculate the hyperon single-particle potentials in the Hartree-Fock approximation for all of the interactions. Their dependence on both momentum and density, is studied. The single-particle potentials are then used to determine the chemical potential of hyperons in neutron stars. For nucleonic properties, the nucleon-nucleon V low k can be used with the caveat that the calculation of the ground-state energy of symmetric nuclear matter does not correctly reproduce the properties of matter at saturation. With the nucleon-nucleon V low k one is unable to reach the densities needed for the calculation of neutron star masses. To circumvent this problem we use two approaches: in the first one, we parametrize the entire nucleonic sector. In the second one, we replace only the three-body force. The former will enable us to study neutron star masses, and the latter for studying the medium's response to the external probe. In this thesis we take the external probe to be the neutrino. By combining this parametrization with the YN V low k potential, we calculate the equation of state of equilibrated matter. Performing the calculation in the Hartree-Fock approximation at zero temperature, the concentrations of all particles are calculated. From these we can ascertain at which densities hyperons appear for a wide range of parameters. Finally, we calculate the masses of neutron stars with these concentrations. For the calculation of the medium's response to an external probe, we replace the three-body force with a density-dependent interaction. This

  3. Geometrical optics of dense aerosols: forming dense plasma slabs.

    Science.gov (United States)

    Hay, Michael J; Valeo, Ernest J; Fisch, Nathaniel J

    2013-11-01

    Assembling a freestanding, sharp-edged slab of homogeneous material that is much denser than gas, but much more rarefied than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed field, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the finite particle density reduces the effective Stokes number of the flow, a critical result for controlled focusing.

  4. Study of simple super-critical fluids (CO2, C2D6) through neutron scattering, Raman spectroscopy and molecular dynamic simulations

    International Nuclear Information System (INIS)

    Longelin, St.

    2004-04-01

    Super-critical fluids are largely used in industrial sectors. However the knowledge of the physical phenomena in which they are involved stays insufficient because of their particular properties. A new model of adjusting molecular structures is proposed, this model has been validated through neutron scattering experiments with high momentum transfer on C 2 D 6 . The experimental representation of the critical universal function for C 2 D 6 and CO 2 has been obtained through the neutron echo spin and by relying on structure measurements made through neutron elastic scattering at small angles. Raman spectroscopy and molecular dynamics simulation have been used to feature structure and dynamics. Scattering as well as microscopic molecular density fluctuations have been analysed

  5. Occurrence of tetrodotoxin-binding high molecular weight substances in the body fluid of shore crab (Hemigrapsus sanguineus).

    Science.gov (United States)

    Shiomi, K; Yamaguchi, S; Kikuchi, T; Yamamori, K; Matsui, T

    1992-12-01

    The shore crab (Hemigrapsus sanguineus) is highly resistant to tetrodotoxin (TTX) although it contains no detectable amount of TTX (less than 5 MU/g, where 1 MU is defined as the amount of TTX killing a 20 g mouse in 30 min). Its body fluid was examined for neutralizing effects against the lethal activity of TTX. When the mixture of the body fluid and TTX was injected i.p. into mice, the lethal activity of TTX was significantly reduced; 1 ml of the body fluid was evaluated to neutralize 3.6-4.0 MU of TTX. Higher neutralizing activity (7.2-12.5 MU/ml of the body fluid) was exhibited by i.v. administration of the body fluid into mice before or after i.p. challenge of TTX. The lethal effect of paralytic shellfish poisons was not counteracted by the body fluid. Analysis by gel filtration on Sepharose 6B revealed that the body fluid contained TTX-binding high mol. wt substances (> 2,000,000) responsible for the neutralizing activity of the body fluid against TTX, which accounts for the high resistibility of the crab to TTX. When the crude toxin extracted from the liver of puffer (Takifugu niphobles) was mixed with the body fluid and chromatographed on Sepharose 6B, almost pure TTX was obtained from the fractions containing the TTX-binding high mol. wt substances, suggesting that the TTX-binding high mol. wt substances could be useful in purification of TTX from biological samples.

  6. Environmentally Friendly Procedure Based on Supercritical Fluid Chromatography and Tandem Mass Spectrometry Molecular Networking for the Discovery of Potent Antiviral Compounds from Euphorbia semiperfoliata.

    Science.gov (United States)

    Nothias, Louis-Félix; Boutet-Mercey, Stéphanie; Cachet, Xavier; De La Torre, Erick; Laboureur, Laurent; Gallard, Jean-François; Retailleau, Pascal; Brunelle, Alain; Dorrestein, Pieter C; Costa, Jean; Bedoya, Luis M; Roussi, Fanny; Leyssen, Pieter; Alcami, José; Paolini, Julien; Litaudon, Marc; Touboul, David

    2017-10-27

    A supercritical fluid chromatography-based targeted purification procedure using tandem mass spectrometry and molecular networking was developed to analyze, annotate, and isolate secondary metabolites from complex plant extract mixture. This approach was applied for the targeted isolation of new antiviral diterpene esters from Euphorbia semiperfoliata whole plant extract. The analysis of bioactive fractions revealed that unknown diterpene esters, including jatrophane esters and phorbol esters, were present in the samples. The purification procedure using semipreparative supercritical fluid chromatography led to the isolation and identification of two new jatrophane esters (13 and 14) and one known (15) and three new 4-deoxyphorbol esters (16-18). The structure and absolute configuration of compound 16 were confirmed by X-ray crystallography. This compound was found to display antiviral activity against Chikungunya virus (EC 50 = 0.45 μM), while compound 15 proved to be a potent and selective inhibitor of HIV-1 replication in a recombinant virus assay (EC 50 = 13 nM). This study showed that a supercritical fluid chromatography-based protocol and molecular networking can facilitate and accelerate the discovery of bioactive small molecules by targeting molecules of interest, while minimizing the use of toxic solvents.

  7. Mean-field density functional theory of a nanoconfined classical, three-dimensional Heisenberg fluid. I. The role of molecular anchoring

    Science.gov (United States)

    Cattes, Stefanie M.; Gubbins, Keith E.; Schoen, Martin

    2016-05-01

    In this work, we employ classical density functional theory (DFT) to investigate for the first time equilibrium properties of a Heisenberg fluid confined to nanoscopic slit pores of variable width. Within DFT pair correlations are treated at modified mean-field level. We consider three types of walls: hard ones, where the fluid-wall potential becomes infinite upon molecular contact but vanishes otherwise, and hard walls with superimposed short-range attraction with and without explicit orientation dependence. To model the distance dependence of the attractions, we employ a Yukawa potential. The orientation dependence is realized through anchoring of molecules at the substrates, i.e., an energetic discrimination of specific molecular orientations. If the walls are hard or attractive without specific anchoring, the results are "quasi-bulk"-like in that they can be linked to a confinement-induced reduction of the bulk mean field. In these cases, the precise nature of the walls is completely irrelevant at coexistence. Only for specific anchoring nontrivial features arise, because then the fluid-wall interaction potential affects the orientation distribution function in a nontrivial way and thus appears explicitly in the Euler-Lagrange equations to be solved for minima of the grand potential of coexisting phases.

  8. Mercury's Densely Cratered Surface

    Science.gov (United States)

    1974-01-01

    Mariner 10 took this picture (FDS 27465) of the densely cratered surface of Mercury when the spacecraft was 18,200 kilometers (8085 miles) from the planet on March 29. The dark line across top of picture is a 'dropout' of a few TV lines of data. At lower left, a portion of a 61 kilometer (38 mile) crater shows a flow front extending across the crater floor and filling more than half of the crater. The smaller, fresh crater at center is about 25 kilometers (15 miles) in diameter. Craters as small as one kilometer (about one-half mile) across are visible in the picture.The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.Image Credit: NASA/JPL/Northwestern University

  9. Green-function description of dense polymeric systems

    NARCIS (Netherlands)

    Schoot, van der P.P.A.M.

    2000-01-01

    A self-consistent Green-function description of concentrated polymer solutions and dense polymeric melts is presented. The method, which applies to both uniform and nonuniform systems, is used in this work to calculate the static structure factor of a homogeneous fluid of Gaussian model chains.

  10. Hadrons in dense matter. Proceedings

    International Nuclear Information System (INIS)

    Buballa, M.; Noerenberg, W.; Schaefer, B.J.; Wambach, J.

    2000-03-01

    The following topics were dealt with: Elementary hadronic reactions, Delta dynamics in nuclei, in-medium s-wave ππ-correlations, strangeness in hot and dense matter, medium modifications of vector mesons and dilepton production, medium modifications of charmonium, thermal properties of hot and dense hadronic matter, nuclear matter, spectral functions and QCD sum rules

  11. Seleção de concretos refratários densos antierosivos para unidades de craqueamento catalítico fluidizado de petróleo Selection of dense antierosive refractory castables for fluid catalytic cracking units

    Directory of Open Access Journals (Sweden)

    F. A. S. Serra

    2012-03-01

    characterized under cold crushing strength and cold erosion tests. Additional tests that are actually not used in the selection were also performed, such as: thermal shock cycling, hot modulus of rupture and carbon deposition by CO atmosphere exposure. The analysis showed that the present specifications are mainly based in the experience with the use of products not designed for this application and that the development of more suitable castables is inhibited due to the close restrictions of the present specifications. It is also verified that the materials selection is limited by the absence of tests for the performance evaluation next to in-service conditions. In this sense, the carbon deposition test by CO atmosphere exposure was interesting in order to provide the better selection of dense antierosive refractory castables.

  12. Dense hydrogen plasma: Comparison between models

    International Nuclear Information System (INIS)

    Clerouin, J.G.; Bernard, S.

    1997-01-01

    Static and dynamical properties of the dense hydrogen plasma (ρ≥2.6gcm -3 , 0.1< T<5eV) in the strongly coupled regime are compared through different numerical approaches. It is shown that simplified density-functional molecular-dynamics simulations (DFMD), without orbitals, such as Thomas-Fermi Dirac or Thomas-Fermi-Dirac-Weiszaecker simulations give similar results to more sophisticated descriptions such as Car-Parrinello (CP), tight binding, or path-integral Monte Carlo, in a wide range of temperatures. At very low temperature, screening effects predicted by DFMD are still less pronounced than CP simulations. copyright 1997 The American Physical Society

  13. Electrical and thermal conductivities in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  14. Unified approach to dense matter

    International Nuclear Information System (INIS)

    Park, Byung-Yoon; Lee, Hee-Jung; Vento, Vicente; Kim, Joon-Il; Min, Dong-Pil; Rho, Mannque

    2005-01-01

    We apply the Skyrme model to dense hadronic matter, which provides a unified approach to high density, valid in the large N c limit. In our picture, dense hadronic matter is described by the classical soliton configuration with minimum energy for the given baryon number density. By incorporating the meson fluctuations on such ground state we obtain an effective Lagrangian for meson dynamics in a dense medium. Our starting point has been the Skyrme model defined in terms of pions, thereafter we have extended and improved the model by incorporating other degrees of freedom such as dilaton, kaons and vector mesons

  15. Formation and fragmentation of protostellar dense cores

    International Nuclear Information System (INIS)

    Maury, Anaelle

    2009-01-01

    Stars form in molecular clouds, when they collapse and fragment to produce protostellar dense cores. These dense cores are then likely to contract under their own gravity, and form young protostars, that further evolve while accreting their circumstellar mass, until they reach the main sequence. The main goal of this thesis was to study the formation and fragmentation of protostellar dense cores. To do so, two main studies, described in this manuscript, were carried out. First, we studied the formation of protostellar cores by quantifying the impact of protostellar outflows on clustered star formation. We carried out a study of the protostellar outflows powered by the young stellar objects currently formed in the NGc 2264-C proto-cluster, and we show that protostellar outflows seem to play a crucial role as turbulence progenitors in clustered star forming regions, although they seem unlikely to significantly modify the global infall processes at work on clump scales. Second, we investigated the formation of multiple systems by core fragmentation, by using high - resolution observations that allow to probe the multiplicity of young protostars on small scales. Our results suggest that the multiplicity rate of protostars on small scales increase while they evolve, and thus favor dynamical scenarios for the formation of multiple systems. Moreover, our results favor magnetized scenarios of core collapse to explain the small-scale properties of protostars at the earliest stages. (author) [fr

  16. Value of PCR in sonication fluid for the diagnosis of orthopedic hardware-associated infections: Has the molecular era arrived?

    Science.gov (United States)

    Renz, Nora; Cabric, Sabrina; Morgenstern, Christian; Schuetz, Michael A; Trampuz, Andrej

    2018-04-01

    Bone healing disturbance following fracture fixation represents a continuing challenge. We evaluated a novel fully automated polymerase chain reaction (PCR) assay using sonication fluid from retrieved orthopedic hardware to diagnose infection. In this prospective diagnostic cohort study, explanted orthopedic hardware materials from consecutive patients were investigated by sonication and the resulting sonication fluid was analyzed by culture (standard procedure) and multiplex PCR (investigational procedure). Hardware-associated infection was defined as visible purulence, presence of a sinus tract, implant on view, inflammation in peri-implant tissue or positive culture. McNemar's chi-squared test was used to compare the performance of diagnostic tests. For the clinical performance all pathogens were considered, whereas for analytical performance only microorganisms were considered for which primers are included in the PCR assay. Among 51 patients, hardware-associated infection was diagnosed in 38 cases (75%) and non-infectious causes in 13 patients (25%). The sensitivity for diagnosing infection was 66% for peri-implant tissue culture, 84% for sonication fluid culture, 71% (clinical performance) and 77% (analytical performance) for sonication fluid PCR, the specificity of all tests was >90%. The analytical sensitivity of PCR was higher for gram-negative bacilli (100%), coagulase-negative staphylococci (89%) and Staphylococcus aureus (75%) than for Cutibacterium (formerly Propionibacterium) acnes (57%), enterococci (50%) and Candida spp. (25%). The performance of sonication fluid PCR for diagnosis of orthopedic hardware-associated infection was comparable to culture tests. The additional advantage of PCR was short processing time (PCR has the potential to complement conventional cultures. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Transport properties of dense matter

    International Nuclear Information System (INIS)

    Itoh, Naoki; Mitake, Shinichi; Iyetomi, Hiroshi; Ichimaru, Setsuo

    1983-01-01

    Transport coefficients, electrical and thermal conductivities in particular, are essential physical quantities for the theories of stellar structure. Since the discoveries of pulsars and X-ray stars, an accurate evaluation of the transport coefficients in the dense matter has become indispensable to the quantitative understanding of the observed neutron stars. The authors present improved calculations of the electrical and thermal conductivities of the dense matter in the liquid metal phase, appropriate to white dwarfs and neutron stars. (Auth.)

  18. Exploring a multi-scale method for molecular simulation in continuum solvent model: Explicit simulation of continuum solvent as an incompressible fluid.

    Science.gov (United States)

    Xiao, Li; Luo, Ray

    2017-12-07

    We explored a multi-scale algorithm for the Poisson-Boltzmann continuum solvent model for more robust simulations of biomolecules. In this method, the continuum solvent/solute interface is explicitly simulated with a numerical fluid dynamics procedure, which is tightly coupled to the solute molecular dynamics simulation. There are multiple benefits to adopt such a strategy as presented below. At this stage of the development, only nonelectrostatic interactions, i.e., van der Waals and hydrophobic interactions, are included in the algorithm to assess the quality of the solvent-solute interface generated by the new method. Nevertheless, numerical challenges exist in accurately interpolating the highly nonlinear van der Waals term when solving the finite-difference fluid dynamics equations. We were able to bypass the challenge rigorously by merging the van der Waals potential and pressure together when solving the fluid dynamics equations and by considering its contribution in the free-boundary condition analytically. The multi-scale simulation method was first validated by reproducing the solute-solvent interface of a single atom with analytical solution. Next, we performed the relaxation simulation of a restrained symmetrical monomer and observed a symmetrical solvent interface at equilibrium with detailed surface features resembling those found on the solvent excluded surface. Four typical small molecular complexes were then tested, both volume and force balancing analyses showing that these simple complexes can reach equilibrium within the simulation time window. Finally, we studied the quality of the multi-scale solute-solvent interfaces for the four tested dimer complexes and found that they agree well with the boundaries as sampled in the explicit water simulations.

  19. The Green Bank Ammonia Survey: Dense Cores under Pressure in Orion A

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, Helen; Di Francesco, James [NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Rd, Victoria, BC, V9E 2E7 (Canada); Friesen, Rachel K. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario M5S 3H4 (Canada); Pineda, Jaime E.; Caselli, Paola; Alves, Felipe O.; Chacón-Tanarro, Ana; Punanova, Anna [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748, Garching (Germany); Rosolowsky, Erik [Department of Physics, University of Alberta, Edmonton, AB (Canada); Offner, Stella S. R. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Matzner, Christopher D.; Singh, Ayushi [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Myers, Philip C.; Chen, How-Huan [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Chen, Michael Chun-Yuan; Keown, Jared [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Rd., Victoria, BC, V8P 5C2 (Canada); Seo, Young Min [Jet Propulsion Laboratory, NASA, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States); Shirley, Yancy [Steward Observatory, 933 North Cherry Ave., Tucson, AZ 85721 (United States); Ginsburg, Adam [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Hall, Christine [Department of Physics, Engineering Physics and Astronomy, Queen’s University, Kingston, Ontario, K7L 3N6 (Canada); and others

    2017-09-10

    We use data on gas temperature and velocity dispersion from the Green Bank Ammonia Survey and core masses and sizes from the James Clerk Maxwell Telescope Gould Belt Survey to estimate the virial states of dense cores within the Orion A molecular cloud. Surprisingly, we find that almost none of the dense cores are sufficiently massive to be bound when considering only the balance between self-gravity and the thermal and non-thermal motions present in the dense gas. Including the additional pressure binding imposed by the weight of the ambient molecular cloud material and additional smaller pressure terms, however, suggests that most of the dense cores are pressure-confined.

  20. The Green Bank Ammonia Survey: Dense Cores under Pressure in Orion A

    International Nuclear Information System (INIS)

    Kirk, Helen; Di Francesco, James; Friesen, Rachel K.; Pineda, Jaime E.; Caselli, Paola; Alves, Felipe O.; Chacón-Tanarro, Ana; Punanova, Anna; Rosolowsky, Erik; Offner, Stella S. R.; Matzner, Christopher D.; Singh, Ayushi; Myers, Philip C.; Chen, How-Huan; Chen, Michael Chun-Yuan; Keown, Jared; Seo, Young Min; Shirley, Yancy; Ginsburg, Adam; Hall, Christine

    2017-01-01

    We use data on gas temperature and velocity dispersion from the Green Bank Ammonia Survey and core masses and sizes from the James Clerk Maxwell Telescope Gould Belt Survey to estimate the virial states of dense cores within the Orion A molecular cloud. Surprisingly, we find that almost none of the dense cores are sufficiently massive to be bound when considering only the balance between self-gravity and the thermal and non-thermal motions present in the dense gas. Including the additional pressure binding imposed by the weight of the ambient molecular cloud material and additional smaller pressure terms, however, suggests that most of the dense cores are pressure-confined.

  1. Linear and nonlinear viscous flow in two-dimensional fluids

    International Nuclear Information System (INIS)

    Gravina, D.; Ciccotti, G.; Holian, B.L.

    1995-01-01

    We report on molecular dynamics simulations of shear viscosity η of a dense two-dimensional fluid as a function of the shear rate γ. We find an analytic dependence of η on γ, and do not find any evidence whatsoever of divergence in the Green-Kubo (GK) value that would be caused by the well-known long-time tail for the shear-stress autocorrelation function, as predicted by the mode-coupling theory. In accordance with the linear response theory, the GK value of η agrees remarkably well with nonequilibrium values at small shear rates. (c) 1995 The American Physical Society

  2. Statistical mechanics of dense granular media

    International Nuclear Information System (INIS)

    Coniglio, A; Fierro, A; Nicodemi, M; Ciamarra, M Pica; Tarzia, M

    2005-01-01

    We discuss some recent results on the statistical mechanics approach to dense granular media. In particular, by analytical mean field investigation we derive the phase diagram of monodisperse and bidisperse granular assemblies. We show that 'jamming' corresponds to a phase transition from a 'fluid' to a 'glassy' phase, observed when crystallization is avoided. The nature of such a 'glassy' phase turns out to be the same as found in mean field models for glass formers. This gives quantitative evidence for the idea of a unified description of the 'jamming' transition in granular media and thermal systems, such as glasses. We also discuss mixing/segregation transitions in binary mixtures and their connections to phase separation and 'geometric' effects

  3. Molecular Simulations As a Tool for Predicting Phase Equilibria and Transport Properties of Fluids Les simulations moléculaires comme outils pour prédire les équilibres de phases et les propriétés de transport des fluides

    Directory of Open Access Journals (Sweden)

    Fuchs A.

    2006-12-01

    Full Text Available koWe briefly review the molecular simulation methods which can be used to predict thermophysical properties of fluids and fluid mixtures. It is shown in this paper, on the one hand, how the Gibbs Ensemble Monte Carlo Method allows phase behavior predictions for real fluids under conditions for which experimental data are difficult or impossible to obtain. On the other hand, the molecular dynamics methods used for predicting transport properties of molecular fluids are described. Finally we discuss possible future applications of these methods. Dans cet article, nous passons brièvement en revue les méthodes de simulation moléculaire applicables à la prédiction des propriétés thermophysiques des fluides et des mélanges. Nous montrons, d'une part, comment la méthode de Monte-Carlo dans l'ensemble de Gibbs permet de prédire le comportement de phase de fluides réels dans des conditions telles que l'acquisition de données expérimentales serait difficile, voire impossible. D'autre part, nous décrivons les méthodes de dynamique moléculaire utilisées pour prédire les propriétés de transport de fluides moléculaires. Enfin, nous discutons le potentiel de ces méthodes pour les applications futures.

  4. Global sensitivity analysis of computer-aided molecular design problem for the development of novel working fluids for power cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    2016-01-01

    This study compares two methods for global sensitivity analysis as a new approach for the identification and ranking of target properties in molecular design problems: A modified Morris Screening technique and Monte Carlo based standard regression. The two methodologies are highlighted in a case ...

  5. A constitutive law for dense granular flows.

    Science.gov (United States)

    Jop, Pierre; Forterre, Yoël; Pouliquen, Olivier

    2006-06-08

    A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.

  6. Gas-particle interactions in dense gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.

    2003-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects gas¿solid contacting and transport processes in dense gas-fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore the

  7. PASCAL: a multidisciplinary data base. Its use in atomic and molecular physics and plasma and fluid physics

    International Nuclear Information System (INIS)

    Buhr, J.M.; Degen, C.

    1977-01-01

    Description is given of the system PASCAL of the 'Centre de Documentation' of C.N.R.S., which deals with a multidisciplinary data base. PASCAL is an automated system for input, treatment and selective dissemination on a wide scope of scientific and technical fields. Its products are tape series, 'Bulletins Signaletiques', documentary profiles, retrospective searching as well in batch as on line. As illustration, an example is given in atomic and molecular Physics [fr

  8. TWO-FLUID MAGNETOHYDRODYNAMICS SIMULATIONS OF CONVERGING H I FLOWS IN THE INTERSTELLAR MEDIUM. II. ARE MOLECULAR CLOUDS GENERATED DIRECTLY FROM A WARM NEUTRAL MEDIUM?

    International Nuclear Information System (INIS)

    Inoue, Tsuyoshi; Inutsuka, Shu-ichiro

    2009-01-01

    Formation of interstellar clouds as a consequence of thermal instability is studied using two-dimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the interstellar medium that generate a shocked slab of thermally unstable gas in which clouds form. We find, as speculated in Paper I, that in the shocked slab magnetic pressure dominates thermal pressure and the thermal instability grows in the isochorically cooling, thermally unstable slab that leads to the formation of H I clouds whose number density is typically n ∼ -3 , even if the angle between magnetic field and converging flows is small. We also find that even if there is a large dispersion of magnetic field, evolution of the shocked slab is essentially determined by the angle between the mean magnetic field and converging flows. Thus, the direct formation of molecular clouds by piling up warm neutral medium does not seem to be a typical molecular cloud formation process, unless the direction of supersonic converging flows is biased to the orientation of mean magnetic field by some mechanism. However, when the angle is small, the H I shell generated as a result of converging flows is massive and possibly evolves into molecular clouds, provided gas in the massive H I shell is piled up again along the magnetic field line. We expect that another subsequent shock wave can again pile up the gas of the massive shell and produce a larger cloud. We thus emphasize the importance of multiple episodes of converging flows, as a typical formation process of molecular clouds.

  9. Computation and analysis of the transverse current autocorrelation function, Ct(k,t), for small wave vectors: A molecular-dynamics study for a Lennard-Jones fluid

    Science.gov (United States)

    Vogelsang, R.; Hoheisel, C.

    1987-02-01

    Molecular-dynamics (MD) calculations are reported for three thermodynamic states of a Lennard-Jones fluid. Systems of 2048 particles and 105 integration steps were used. The transverse current autocorrelation function, Ct(k,t), has been determined for wave vectors of the range 0.5viscosities which showed a systematic behavior as a function of k. Extrapolation to the hydrodynamic region at k=0 gave shear viscosity coefficients in good agreement with direct Green-Kubo results obtained in previous work. The two-exponential model fit for the memory function proposed by other authors does not provide a reasonable description of the MD results, as the fit parameters show no systematic wave-vector dependence, although the Ct(k,t) functions are somewhat better fitted. Similarly, the semiempirical interpolation formula for the decay time based on the viscoelastic concept proposed by Akcasu and Daniels fails to reproduce the correct k dependence for the wavelength range investigated herein.

  10. Relationship between theoretical molecular weight and blister fluid/serum ratio of cytokines and five other molecules evaluated in patients with bullous pemphigoid.

    Science.gov (United States)

    D'Auria, L; Pimpinelli, F; Ferraro, C; D'Ambrogio, G; Giacalone, B; Bellocci, M; Ameglio, F

    1998-01-01

    Bullous pemphigoid (BP) blisters contain several molecules, some of which spread into the blisters from the interstitial fluid, while others are produced locally and migrate into the circulation. The calculation of the ratios between blister/serum concentrations may help to distinguish between these two types of molecules. The rules regulating the diffusion of the molecules have been described only in suction blisters, where the theoretical molecular weight (MW) represents one of the principal influencing factors. The aim of the present study was to analyse the relationship between theoretical MWs and the ratios of concentrations of several molecules evaluated both in sera and in blister fluids. Eight cytokines (interleukin-2, interleukin-3, interleukin-4, interleukin-5, interleukin-10, tumor necrosis factor-alpha, oncostatin-M and vascular endothelial growth factor), two acute phase reactants (alpha-1 acid glycoprotein, haptoglobin), albumin, one soluble membrane molecule with adhesion functions (sICAM-1) and the eosinophil cathionic protein (ECP) were measured in samples from 15 patients affected with BP by means of commercially available tests. The data suggest that the MW may influence the rate of diffusion throughout the blister, both in input and output directions, despite the discontinuity observed at the basement membrane level on the BP blister floor.

  11. Chemical potential calculations in dense liquids using metadynamics

    Science.gov (United States)

    Perego, C.; Giberti, F.; Parrinello, M.

    2016-10-01

    The calculation of chemical potential has traditionally been a challenge in atomistic simulations. One of the most used approaches is Widom's insertion method in which the chemical potential is calculated by periodically attempting to insert an extra particle in the system. In dense systems this method fails since the insertion probability is very low. In this paper we show that in a homogeneous fluid the insertion probability can be increased using metadynamics. We test our method on a supercooled high density binary Lennard-Jones fluid. We find that we can obtain efficiently converged results even when Widom's method fails.

  12. Dense Crowds of Virtual Humans

    NARCIS (Netherlands)

    Stüvel, S.A.

    2016-01-01

    This thesis presents a novel crowd simulation method `Torso Crowds', aimed at the simulation of dense crowds. The method is based on the results of user studies and a motion capture experiment, which are also described in this thesis. Torso Crowds introduces a capsule shape to represent people in

  13. Enhanced Productivity of Chemical Processes Using Dense Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Sibashis Banerjee; Alvin Chen; Rutton Patel; Dale Snider; Ken Williams; Timothy O' Hern; Paul Tortora

    2008-02-29

    The work detailed in this report addresses Enabling Technologies within Computational Technology by integrating a “breakthrough” particle-fluid computational technology into traditional Process Science and Engineering Technology. The work completed under this DOE project addresses five major development areas 1) gas chemistry in dense fluidized beds 2) thermal cracking of liquid film on solids producing gas products 3) liquid injection in a fluidized bed with particle-to-particle liquid film transport 4) solid-gas chemistry and 5) first level validation of models. Because of the nature of the research using tightly coupled solids and fluid phases with a Lagrangian description of the solids and continuum description of fluid, the work provides ground-breaking advances in reactor prediction capability. This capability has been tested against experimental data where available. The commercial product arising out of this work is called Barracuda and is suitable for a wide (dense-to-dilute) range of industrial scale gas-solid flows with and without reactions. Commercial applications include dense gas-solid beds, gasifiers, riser reactors and cyclones.

  14. Kinetic theory of the interdiffusion coefficient in dense plasmas

    International Nuclear Information System (INIS)

    Boercker, D.B.

    1986-08-01

    Naive applications of Spitzer's theory to very dense plasmas can lead to negative diffusion coefficients. The interdiffusion coefficients in Binary Ionic Mixtures (two species of point ions in a uniform neutralizing background) have been calculated recently using molecular dynamics techniques. These calculations can provide useful benchmarks for theoretical evaluations of the diffusion coefficient in dense plasma mixtures. This paper gives a brief description of a kinetic theoretic approximation to the diffusion coefficient which generalizes Spitzer to high density and is in excellent agreement with the computer simulations. 15 refs., 1 fig., 2 tabs

  15. From gas to stars in energetic environments: dense gas clumps in the 30 Doradus region within the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Anderson, Crystal N.; Meier, David S.; Ott, Jürgen; Hughes, Annie; Wong, Tony; Looney, Leslie; Henkel, Christian; Chen, Rosie; Indebetouw, Remy; Muller, Erik; Pineda, Jorge L.; Seale, Jonathan

    2014-01-01

    We present parsec-scale interferometric maps of HCN(1-0) and HCO + (1-0) emission from dense gas in the star-forming region 30 Doradus, obtained using the Australia Telescope Compact Array. This extreme star-forming region, located in the Large Magellanic Cloud (LMC), is characterized by a very intense ultraviolet ionizing radiation field and sub-solar metallicity, both of which are expected to impact molecular cloud structure. We detect 13 bright, dense clumps within the 30 Doradus-10 giant molecular cloud. Some of the clumps are aligned along a filamentary structure with a characteristic spacing that is consistent with formation via varicose fluid instability. Our analysis shows that the filament is gravitationally unstable and collapsing to form stars. There is a good correlation between HCO + emission in the filament and signatures of recent star formation activity including H 2 O masers and young stellar objects (YSOs). YSOs seem to continue along the same direction of the filament toward the massive compact star cluster R136 in the southwest. We present detailed comparisons of clump properties (masses, linewidths, and sizes) in 30Dor-10 to those in other star forming regions of the LMC (N159, N113, N105, and N44). Our analysis shows that the 30Dor-10 clumps have similar masses but wider linewidths and similar HCN/HCO + (1-0) line ratios as clumps detected in other LMC star-forming regions. Our results suggest that the dense molecular gas clumps in the interior of 30Dor-10 are well shielded against the intense ionizing field that is present in the 30 Doradus region.

  16. The dissociation mechanism and thermodynamic properties of HCl(aq) in hydrothermal fluids (to 700 °C, 60 kbar) by ab initio molecular dynamics simulations

    Science.gov (United States)

    Mei, Yuan; Liu, Weihua; Brugger, Joël; Sherman, David M.; Gale, Julian D.

    2018-04-01

    HCl is one of the most significant volatiles in the Earth's crust. It is well established that chloride activity and acidity (pH) play important roles in controlling the solubility of metals in aqueous hydrothermal fluids. Thus, quantifying the dissociation of HCl in aqueous solutions over a wide range of temperature and pressure is crucial for the understanding and numerical modeling of element mobility in hydrothermal fluids. Here we have conducted ab initio molecular dynamics (MD) simulations to investigate the mechanism of HCl(aq) dissociation and to calculate the thermodynamic properties for the dissociation reaction at 25-700 °C, 1 bar to 60 kbar, i.e. including high temperature and pressure conditions that are geologically important, but difficult to investigate via experiments. Our results predict that HCl(aq) tends to associate with increasing temperature, and dissociate with increasing pressure. In particular, HCl(aq) is highly dissociated at extremely high pressures, even at high temperatures (e.g., 60 kbar, 600-700 °C). At 25 °C, the calculated logKd values (6.79 ± 0.81) are close to the value (7.0) recommended by IUPAC (International Union of Pure and Applied Chemistry) and some previous experimental and theoretical studies (Simonson et al.., 1990; Sulpizi and Sprik, 2008, 2010). The MD simulations indicate full dissociation of HCl at low temperature; in contrast, some experiments were interpreted assuming significant association at high HCl concentrations (≥1 m HCltot) even at room T (logKd ∼0.7; e.g., Ruaya and Seward, 1987; Sretenskaya, 1992; review in Tagirov et al., 1997). This discrepancy is most likely the result of difficulties in the experimental determination of minor (if any) concentration of associated HCl(aq) under ambient conditions, and thus reflects differences in the activity models used for the interpretation of the experiments. With increasing temperature, the discrepancy between our MD results and previous experimental

  17. Crowding of Interacting Fluid Particles in Porous Media through Molecular Dynamics: Breakdown of Universality for Soft Interactions

    Science.gov (United States)

    Schnyder, Simon K.; Horbach, Jürgen

    2018-02-01

    Molecular dynamics simulations of interacting soft disks confined in a heterogeneous quenched matrix of soft obstacles show dynamics which is fundamentally different from that of hard disks. The interactions between the disks can enhance transport when their density is increased, as disks cooperatively help each other over the finite energy barriers in the matrix. The system exhibits a transition from a diffusive to a localized state, but the transition is strongly rounded. Effective exponents in the mean-squared displacement can be observed over three decades in time but depend on the density of the disks and do not correspond to asymptotic behavior in the vicinity of a critical point, thus, showing that it is incorrect to relate them to the critical exponents in the Lorentz model scenario. The soft interactions are, therefore, responsible for a breakdown of the universality of the dynamics.

  18. Fluid mechanics in fluids at rest.

    Science.gov (United States)

    Brenner, Howard

    2012-07-01

    Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.

  19. Holographic Renormalization in Dense Medium

    International Nuclear Information System (INIS)

    Park, Chanyong

    2014-01-01

    The holographic renormalization of a charged black brane with or without a dilaton field, whose dual field theory describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space

  20. Suprathermal viscosity of dense matter

    International Nuclear Information System (INIS)

    Alford, Mark; Mahmoodifar, Simin; Schwenzer, Kai

    2010-01-01

    Motivated by the existence of unstable modes of compact stars that eventually grow large, we study the bulk viscosity of dense matter, taking into account non-linear effects arising in the large amplitude regime, where the deviation μ Δ of the chemical potentials from chemical equilibrium fulfills μ Δ > or approx. T. We find that this supra-thermal bulk viscosity can provide a potential mechanism for saturating unstable modes in compact stars since the viscosity is strongly enhanced. Our study confirms previous results on strange quark matter and shows that the suprathermal enhancement is even stronger in the case of hadronic matter. We also comment on the competition of different weak channels and the presence of suprathermal effects in various color superconducting phases of dense quark matter.

  1. Bronchial Mucus as a Complex Fluid: Molecular Interactions and Influence of Nanostructured Particles on Rheological and Transport Properties

    Directory of Open Access Journals (Sweden)

    Odziomek Marcin

    2017-06-01

    Full Text Available Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a rheological properties and (b mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method. First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.

  2. Dilute and dense axion stars

    Science.gov (United States)

    Visinelli, Luca; Baum, Sebastian; Redondo, Javier; Freese, Katherine; Wilczek, Frank

    2018-02-01

    Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core |θ0 | ≡ | θ (r = 0) |, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of |θ0 |. For small |θ0 | ≲ 1, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes |θ0 | ≳ 1, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the dense branch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

  3. Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro/nano-channel : heat flux predictions using combined molecular dynamics and Monte Carlo techniques

    NARCIS (Netherlands)

    Gaastra - Nedea, S.V.; Steenhoven, van A.A.; Markvoort, A.J.; Spijker, P.; Giordano, D.

    2014-01-01

    The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and

  4. Reciprocal locomotion of dense swimmers in Stokes flow

    International Nuclear Information System (INIS)

    Gonzalez-Rodriguez, David; Lauga, Eric

    2009-01-01

    Due to the kinematic reversibility of Stokes flow, a body executing a reciprocal motion (a motion in which the sequence of body configurations remains identical under time reversal) cannot propel itself in a viscous fluid in the limit of negligible inertia; this result is known as Purcell's scallop theorem. In this limit, the Reynolds numbers based on the fluid inertia and on the body inertia are all zero. Previous studies characterized the breakdown of the scallop theorem with fluid inertia. In this paper we show that, even in the absence of fluid inertia, certain dense bodies undergoing reciprocal motion are able to swim. Using Lorentz's reciprocal theorem, we first derive the general differential equations that govern the locomotion kinematics of a dense swimmer. We demonstrate that no reciprocal swimming is possible if the body motion consists only of tangential surface deformation (squirming). We then apply our general formulation to compute the locomotion of four simple swimmers, each with a different spatial asymmetry, that perform normal surface deformations. We show that the resulting swimming speeds (or rotation rates) scale as the first power of a properly defined 'swimmer Reynolds number', demonstrating thereby a continuous breakdown of the scallop theorem with body inertia.

  5. Dense Breasts: Answers to Commonly Asked Questions

    Science.gov (United States)

    ... Cancer Prevention Genetics of Breast & Gynecologic Cancers Breast Cancer Screening Research Dense Breasts: Answers to Commonly Asked Questions What are dense breasts? Breasts contain glandular, connective, and fat tissue. Breast density is a term that describes the ...

  6. Dynamical density functional theory for dense atomic liquids

    International Nuclear Information System (INIS)

    Archer, A J

    2006-01-01

    Starting from Newton's equations of motion, we derive a dynamical density functional theory (DDFT) applicable to atomic liquids. The theory has the feature that it requires as input the Helmholtz free energy functional from equilibrium density functional theory. This means that, given a reliable equilibrium free energy functional, the correct equilibrium fluid density profile is guaranteed. We show that when the isothermal compressibility is small, the DDFT generates the correct value for the speed of sound in a dense liquid. We also interpret the theory as a dynamical equation for a coarse grained fluid density and show that the theory can be used (making further approximations) to derive the standard mode coupling theory that is used to describe the glass transition. The present theory should provide a useful starting point for describing the dynamics of inhomogeneous atomic fluids

  7. Senescence-Associated Molecular and Epigenetic Alterations in Mesenchymal Stem Cell Cultures from Amniotic Fluid of Normal and Fetus-Affected Pregnancy

    Directory of Open Access Journals (Sweden)

    Jūratė Savickienė

    2016-01-01

    Full Text Available Human amniotic-fluid-derived mesenchymal stem cells (AF-MSCs are interesting for their multilineage differentiation potential and wide range of therapeutic applications due to the ease of culture expansion. However, MSCs undergo replicative senescence. So far, the molecular mechanisms that underlie fetal diseases and cell senescence are still poorly understood. Here, we analyzed senescence-associated morphologic, molecular, and epigenetic characteristics during propagation of MSCs derived from AF of normal and fetus-affected pregnancy. AF-MSCs cultures from both cell sources displayed quite similar morphology and expression of specific cell surface (CD44, CD90, and CD105 and stemness (Oct4, Nanog, Sox2, and Rex1 markers but had interindividual variability in proliferation capability and time to reach senescence. Within passages 4 and 8, senescent cultures exhibited typical morphological features, senescence-associated β-galactosidase activity, increased levels of p16, and decreased levels of miR-17 and miR-21 but showed differential expression of p21, p53, and ATM dependently on the onset of cell senescence. These differences correlated with changes in the level of chromatin modifiers (DNMT1 and HDAC1 and polycomb group proteins (EZH2, SUZ12, and BMI1 paralleling with changes in the expression of repressive histone marks (H3K9me3 and H3K27me3 and stemness markers (Oct4, Nanog, Sox2, and Rex1. Therefore epigenetic factors are important for AF-MSCs senescence process that may be related with individuality of donor or a fetus malignancy status.

  8. Thermal conductivity of the Lennard-Jones chain fluid model.

    Science.gov (United States)

    Galliero, Guillaume; Boned, Christian

    2009-12-01

    Nonequilibrium molecular dynamics simulations have been performed to estimate, analyze, and correlate the thermal conductivity of a fluid composed of short Lennard-Jones chains (up to 16 segments) over a large range of thermodynamic conditions. It is shown that the dilute gas contribution to the thermal conductivity decreases when the chain length increases for a given temperature. In dense states, simulation results indicate that the residual thermal conductivity of the monomer increases strongly with density, but is weakly dependent on the temperature. Compared to the monomer value, it has been noted that the residual thermal conductivity of the chain was slightly decreasing with its length. Using these results, an empirical relation, including a contribution due to the critical enhancement, is proposed to provide an accurate estimation of the thermal conductivity of the Lennard-Jones chain fluid model (up to 16 segments) over the domain 0.8values of the Lennard-Jones chain fluid model merge on the same "universal" curve when plotted as a function of the excess entropy. Furthermore, it is shown that the reduced configurational thermal conductivity of the Lennard-Jones chain fluid model is approximately proportional to the reduced excess entropy for all fluid states and all chain lengths.

  9. Rheology of dense suspensions of non colloidal particles

    Science.gov (United States)

    Guazzelli, Élisabeth

    2017-06-01

    Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids that we will also address.

  10. Rheology of dense suspensions of non colloidal particles

    Directory of Open Access Journals (Sweden)

    Guazzelli Élisabeth

    2017-01-01

    Full Text Available Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing and in natural phenomena (e.g. flows of slurries, debris, and lava. Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers or non-Newtonian fluids that we will also address.

  11. Constructing Dense Graphs with Unique Hamiltonian Cycles

    Science.gov (United States)

    Lynch, Mark A. M.

    2012-01-01

    It is not difficult to construct dense graphs containing Hamiltonian cycles, but it is difficult to generate dense graphs that are guaranteed to contain a unique Hamiltonian cycle. This article presents an algorithm for generating arbitrarily large simple graphs containing "unique" Hamiltonian cycles. These graphs can be turned into dense graphs…

  12. Hugoniot measurements of double-shocked precompressed dense xenon plasmas

    Science.gov (United States)

    Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

    2012-12-01

    The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ˜6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

  13. The Seminal fluid proteome of the polyandrous Red junglefowl offers insights into the molecular basis of fertility, reproductive ageing and domestication.

    Science.gov (United States)

    Borziak, Kirill; Álvarez-Fernández, Aitor; L Karr, Timothy; Pizzari, Tommaso; Dorus, Steve

    2016-11-02

    Seminal fluid proteins (SFPs) are emerging as fundamental contributors to sexual selection given their role in post-mating reproductive events, particularly in polyandrous species where the ejaculates of different males compete for fertilisation. SFP identification however remains taxonomically limited and little is known about avian SFPs, despite extensive work on sexual selection in birds. We characterize the SF proteome of the polyandrous Red junglefowl, Gallus gallus, the wild species that gave rise to the domestic chicken. We identify 1,141 SFPs, including proteins involved in immunity and antimicrobial defences, sperm maturation, and fertilisation, revealing a functionally complex SF proteome. This includes a predominant contribution of blood plasma proteins that is conserved with human SF. By comparing the proteome of young and old males with fast or slow sperm velocity in a balanced design, we identify proteins associated with ageing and sperm velocity, and show that old males that retain high sperm velocity have distinct proteome characteristics. SFP comparisons with domestic chickens revealed both qualitative and quantitative differences likely associated with domestication and artificial selection. Collectively, these results shed light onto the functional complexity of avian SF, and provide a platform for molecular studies of fertility, reproductive ageing, and domestication.

  14. Molecular Genetic Diversity and Quantitation of Methanogen in Ruminal Fluid of Buffalo (Bubalus bubalis Fed Ration (Wheat Straw and Concentrate Mixture Diet

    Directory of Open Access Journals (Sweden)

    K. M. Singh

    2013-01-01

    Full Text Available High roughage diet causes more methane emissions; however, the total methanogen abundance is not influenced by roughage proportion. Technologies to reduce methane emissions are lacking, and development of inhibitors and vaccines that mitigate rumen-derived methane by targeting methanogens relies on present knowledge of the methanogens. In this work, we have investigated molecular diversity of rumen methanogens of Surti buffalo. DNA from rumen fluid was extracted, and 16S rRNA encoding genes were amplified using methanogen specific primer to generate 16S rDNA clone libraries. Seventy-six clones were randomly selected and analysed by RFLP resulting in 21 operational taxonomic units (OTUs. BLAST analysis with available sequences in database revealed sequences of 13 OTUs (55 clones showing similarity with Methanomicrobium sp, 3 OTUs (15 clones with Methanobrevibacter sp. The remaining 5 OTUs (6 clones belonged to uncultured archaea. The phylogenetic analysis indicated that methanogenic communities found in the library were clustered in the order of Methanomicrobiales (18 OTUs and Methanobacteriales (3 OTUs. The population of Methanomicrobiales, Methanobacteriales, and Methanococcales were also observed, accounting for 1.94%, 0.72%, and 0.47% of total archaea, respectively.

  15. Application of computational fluid dynamics for the simulation of cryogenic molecular sieve bed absorber of hydrogen isotopes recovery system for Indian LLCB-TBM

    Energy Technology Data Exchange (ETDEWEB)

    Gayathri Devi, V.; Sircar, A.; Sarkar, B. [Institute of Plasma Research, Bhat, Gandhinagar, Gujarar (India)

    2015-03-15

    One of the most challenging tasks in the design of the fuel cycle system lies in the effective design of Tritium Extraction System (TES) which involves proper extraction and purification of tritium in the fuel cycle of the fusion reactor. Indian Lead Lithium cooled Ceramic Breeder Test Blanket Module (LLCB-TBM) would extract hydrogen isotopes through Cryogenic Molecular Sieve Bed (CMSB) adsorber system. A prototype Hydrogen Isotopes Recovery System (HIRS) is being developed to validate the concepts for tritium extraction by adsorption mass transfer mechanism. In this study, a design model has been developed and analyzed to simulate the adsorption mass transfer kinetics in a fixed bed adsorption column. The simulation leads primarily to effective design of HIRS, which is a state-of-the-art technology. The paper describes the process simulation approach and the results of Computational Fluid Dynamics (CFD) analysis. The effects of different operating conditions are studied to investigate their influence on the hydrogen isotopes adsorption capacity. The results of the present simulation study would be used to understand the best optimized transport phenomenon before realizing the TES as a system for LLCB-TBM. (authors)

  16. OH megamasers: dense gas & the infrared radiation field

    Science.gov (United States)

    Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

    2018-06-01

    To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

  17. Statistical mechanics of dense plasmas: numerical simulation and theory

    International Nuclear Information System (INIS)

    DeWitt, H.E.

    1977-10-01

    Recent Monte Carlo calculations from Paris and from Livermore for dense one and two component plasmas have led to systematic and accurate results for the thermodynamic properties of dense Coulombic fluids. This talk will summarize the results of these numerical experiments, and the simple analytic expressions for the equation of state and other thermodynamic functions that have been obtained. The thermal energy for the one component plasma has a simple power law dependence on temperature that is identical to Monte Carlo results on strongly coupled fluids governed by l/r/sup n/ potentials. A universal model for fluids governed by simple repulsive forces is suggested. For two component plasmas the ion-sphere model is shown to accurately reproduce the Monte Carlo data for the static portion of the energy. Electron screening is included using the Lindhard dielectric function and linear response theory. Free energy expressions have been constructed for one and two component plasmas that allow easy computation of all thermodynamic functions

  18. Molecular Diagnostics

    OpenAIRE

    Choe, Hyonmin; Deirmengian, Carl A.; Hickok, Noreen J.; Morrison, Tiffany N.; Tuan, Rocky S.

    2015-01-01

    Orthopaedic infections are complex conditions that require immediate diagnosis and accurate identification of the causative organisms to facilitate appropriate management. Conventional methodologies for diagnosis of these infections sometimes lack accuracy or sufficient rapidity. Current molecular diagnostics are an emerging area of bench-to-bedside research in orthopaedic infections. Examples of promising molecular diagnostics include measurement of a specific biomarker in the synovial fluid...

  19. Molecular Rheology of Complex Fluids

    DEFF Research Database (Denmark)

    Huang, Qian; Rasmussen, Henrik Koblitz

    following a stress maximum were reported for two LDPE melts. However the rheological significance of the stress maximum as well as the existence of steady flow conditions following the maximum is still a matter of some debate. This thesis focuses on the experimental study of extensional rheology of linear...... and branched polymer melts. We report the stress–strain measurements in extensional flows using a unique Filament Stretching Rheometer (FSR) in controlled strain rate mode and controlled stress mode. Extensional flow is difficult to measure reliably in Laboratory circumstances. In this thesis we first present...

  20. Viscosity kernel of molecular fluids

    DEFF Research Database (Denmark)

    Puscasu, Ruslan; Todd, Billy; Daivis, Peter

    2010-01-01

    , temperature, and chain length dependencies of the reciprocal and real-space viscosity kernels are presented. We find that the density has a major effect on the shape of the kernel. The temperature range and chain lengths considered here have by contrast less impact on the overall normalized shape. Functional...... forms that fit the wave-vector-dependent kernel data over a large density and wave-vector range have also been tested. Finally, a structural normalization of the kernels in physical space is considered. Overall, the real-space viscosity kernel has a width of roughly 3–6 atomic diameters, which means...

  1. Deterministic and unambiguous dense coding

    International Nuclear Information System (INIS)

    Wu Shengjun; Cohen, Scott M.; Sun Yuqing; Griffiths, Robert B.

    2006-01-01

    Optimal dense coding using a partially-entangled pure state of Schmidt rank D and a noiseless quantum channel of dimension D is studied both in the deterministic case where at most L d messages can be transmitted with perfect fidelity, and in the unambiguous case where when the protocol succeeds (probability τ x ) Bob knows for sure that Alice sent message x, and when it fails (probability 1-τ x ) he knows it has failed. Alice is allowed any single-shot (one use) encoding procedure, and Bob any single-shot measurement. For D≤D a bound is obtained for L d in terms of the largest Schmidt coefficient of the entangled state, and is compared with published results by Mozes et al. [Phys. Rev. A71, 012311 (2005)]. For D>D it is shown that L d is strictly less than D 2 unless D is an integer multiple of D, in which case uniform (maximal) entanglement is not needed to achieve the optimal protocol. The unambiguous case is studied for D≤D, assuming τ x >0 for a set of DD messages, and a bound is obtained for the average . A bound on the average requires an additional assumption of encoding by isometries (unitaries when D=D) that are orthogonal for different messages. Both bounds are saturated when τ x is a constant independent of x, by a protocol based on one-shot entanglement concentration. For D>D it is shown that (at least) D 2 messages can be sent unambiguously. Whether unitary (isometric) encoding suffices for optimal protocols remains a major unanswered question, both for our work and for previous studies of dense coding using partially-entangled states, including noisy (mixed) states

  2. Thermodynamics of Fluid Polyamorphism

    Directory of Open Access Journals (Sweden)

    Mikhail A. Anisimov

    2018-01-01

    Full Text Available Fluid polyamorphism is the existence of different condensed amorphous states in a single-component fluid. It is either found or predicted, usually at extreme conditions, for a broad group of very different substances, including helium, carbon, silicon, phosphorous, sulfur, tellurium, cerium, hydrogen, and tin tetraiodide. This phenomenon is also hypothesized for metastable and deeply supercooled water, presumably located a few degrees below the experimental limit of homogeneous ice formation. We present a generic phenomenological approach to describe polyamorphism in a single-component fluid, which is completely independent of the molecular origin of the phenomenon. We show that fluid polyamorphism may occur either in the presence or in the absence of fluid phase separation depending on the symmetry of the order parameter. In the latter case, it is associated with a second-order transition, such as in liquid helium or liquid sulfur. To specify the phenomenology, we consider a fluid with thermodynamic equilibrium between two distinct interconvertible states or molecular structures. A fundamental signature of this concept is the identification of the equilibrium fraction of molecules involved in each of these alternative states. However, the existence of the alternative structures may result in polyamorphic fluid phase separation only if mixing of these structures is not ideal. The two-state thermodynamics unifies all the debated scenarios of fluid polyamorphism in different areas of condensed-matter physics, with or without phase separation, and even goes beyond the phenomenon of polyamorphism by generically describing the anomalous properties of fluids exhibiting interconversion of alternative molecular states.

  3. Breaking Dense Structures: Proving Stability of Densely Structured Hybrid Systems

    Directory of Open Access Journals (Sweden)

    Eike Möhlmann

    2015-06-01

    Full Text Available Abstraction and refinement is widely used in software development. Such techniques are valuable since they allow to handle even more complex systems. One key point is the ability to decompose a large system into subsystems, analyze those subsystems and deduce properties of the larger system. As cyber-physical systems tend to become more and more complex, such techniques become more appealing. In 2009, Oehlerking and Theel presented a (de-composition technique for hybrid systems. This technique is graph-based and constructs a Lyapunov function for hybrid systems having a complex discrete state space. The technique consists of (1 decomposing the underlying graph of the hybrid system into subgraphs, (2 computing multiple local Lyapunov functions for the subgraphs, and finally (3 composing the local Lyapunov functions into a piecewise Lyapunov function. A Lyapunov function can serve multiple purposes, e.g., it certifies stability or termination of a system or allows to construct invariant sets, which in turn may be used to certify safety and security. In this paper, we propose an improvement to the decomposing technique, which relaxes the graph structure before applying the decomposition technique. Our relaxation significantly reduces the connectivity of the graph by exploiting super-dense switching. The relaxation makes the decomposition technique more efficient on one hand and on the other allows to decompose a wider range of graph structures.

  4. Optimal super dense coding over memory channels

    OpenAIRE

    Shadman, Zahra; Kampermann, Hermann; Macchiavello, Chiara; Bruß, Dagmar

    2011-01-01

    We study the super dense coding capacity in the presence of quantum channels with correlated noise. We investigate both the cases of unitary and non-unitary encoding. Pauli channels for arbitrary dimensions are treated explicitly. The super dense coding capacity for some special channels and resource states is derived for unitary encoding. We also provide an example of a memory channel where non-unitary encoding leads to an improvement in the super dense coding capacity.

  5. Deuterium fractionation in dense interstellar clouds

    International Nuclear Information System (INIS)

    Millar, T.J.; Bennett, A.; Herbst, E.

    1989-01-01

    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized. 60 refs

  6. Deuterium fractionation in dense interstellar clouds

    Science.gov (United States)

    Millar, T. J.; Bennett, A.; Herbst, Eric

    1989-05-01

    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized.

  7. Dense module enumeration in biological networks

    Science.gov (United States)

    Tsuda, Koji; Georgii, Elisabeth

    2009-12-01

    Analysis of large networks is a central topic in various research fields including biology, sociology, and web mining. Detection of dense modules (a.k.a. clusters) is an important step to analyze the networks. Though numerous methods have been proposed to this aim, they often lack mathematical rigorousness. Namely, there is no guarantee that all dense modules are detected. Here, we present a novel reverse-search-based method for enumerating all dense modules. Furthermore, constraints from additional data sources such as gene expression profiles or customer profiles can be integrated, so that we can systematically detect dense modules with interesting profiles. We report successful applications in human protein interaction network analyses.

  8. Dense module enumeration in biological networks

    International Nuclear Information System (INIS)

    Tsuda, Koji; Georgii, Elisabeth

    2009-01-01

    Analysis of large networks is a central topic in various research fields including biology, sociology, and web mining. Detection of dense modules (a.k.a. clusters) is an important step to analyze the networks. Though numerous methods have been proposed to this aim, they often lack mathematical rigorousness. Namely, there is no guarantee that all dense modules are detected. Here, we present a novel reverse-search-based method for enumerating all dense modules. Furthermore, constraints from additional data sources such as gene expression profiles or customer profiles can be integrated, so that we can systematically detect dense modules with interesting profiles. We report successful applications in human protein interaction network analyses.

  9. THE JCMT GOULD BELT SURVEY: DENSE CORE CLUSTERS IN ORION A

    Energy Technology Data Exchange (ETDEWEB)

    Lane, J.; Kirk, H.; Johnstone, D.; Mairs, S.; Francesco, J. Di [NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Sadavoy, S. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Hatchell, J. [Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Berry, D. S. [East Asian Observatory, 660 N. A‘ohōkū Place, University Park, Hilo, Hawaii 96720 (United States); Jenness, T. [Joint Astronomy Centre, 660 N. A‘ohōkū Place, University Park, Hilo, Hawaii 96720 (United States); Hogerheijde, M. R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Ward-Thompson, D. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE (United Kingdom); Collaboration: JCMT Gould Belt Survey Team

    2016-12-10

    The Orion A molecular cloud is one of the most well-studied nearby star-forming regions, and includes regions of both highly clustered and more dispersed star formation across its full extent. Here, we analyze dense, star-forming cores identified in the 850 and 450 μ m SCUBA-2 maps from the JCMT Gould Belt Legacy Survey. We identify dense cores in a uniform manner across the Orion A cloud and analyze their clustering properties. Using two independent lines of analysis, we find evidence that clusters of dense cores tend to be mass segregated, suggesting that stellar clusters may have some amount of primordial mass segregation already imprinted in them at an early stage. We also demonstrate that the dense core clusters have a tendency to be elongated, perhaps indicating a formation mechanism linked to the filamentary structure within molecular clouds.

  10. THE JCMT GOULD BELT SURVEY: DENSE CORE CLUSTERS IN ORION A

    International Nuclear Information System (INIS)

    Lane, J.; Kirk, H.; Johnstone, D.; Mairs, S.; Francesco, J. Di; Sadavoy, S.; Hatchell, J.; Berry, D. S.; Jenness, T.; Hogerheijde, M. R.; Ward-Thompson, D.

    2016-01-01

    The Orion A molecular cloud is one of the most well-studied nearby star-forming regions, and includes regions of both highly clustered and more dispersed star formation across its full extent. Here, we analyze dense, star-forming cores identified in the 850 and 450 μ m SCUBA-2 maps from the JCMT Gould Belt Legacy Survey. We identify dense cores in a uniform manner across the Orion A cloud and analyze their clustering properties. Using two independent lines of analysis, we find evidence that clusters of dense cores tend to be mass segregated, suggesting that stellar clusters may have some amount of primordial mass segregation already imprinted in them at an early stage. We also demonstrate that the dense core clusters have a tendency to be elongated, perhaps indicating a formation mechanism linked to the filamentary structure within molecular clouds.

  11. Mixing and Processing of Complex Biological Fluids

    National Research Council Canada - National Science Library

    Liepmann, Dorian

    2003-01-01

    ... of microfluidic control on the makeup and molecular structure of biological fluids. For this project, we focused on two critical fluids that are biologically significant and that are of critical importance to DoD...

  12. Dense sheet Z-pinches

    International Nuclear Information System (INIS)

    Tetsu, Miyamoto

    1999-01-01

    The steady state and quasi-steady processes of infinite- and finite-width sheet z-pinches are studied. The relations corresponding to the Bennett relation and Pease-Braginskii current of cylindrical fiber z-pinches depend on a geometrical factor in the sheet z-pinches. The finite-width sheet z-pinch is approximated by a segment of infinite-width sheet z-pinch, if it is wide enough, and corresponds to a number of (width/thickness) times fiber z-pinch plasmas of the diameter that equals the sheet thickness. If the sheet current equals this number times the fiber current, the plasma created in the sheet z-pinches is as dense as in the fiber z-pinches. The total energy of plasma and magnetic field per unit mass is approximately equal in both pinches. Quasi-static transient processes are different in several aspects from the fiber z-pinch. No radiation collapse occurs in the sheet z-pinch. The stability is improved in the sheet z-pinches. The fusion criterions and the experimental arrangements to produce the sheet z-pinches are also discussed. (author)

  13. STAR FORMATION IN DENSE CLUSTERS

    International Nuclear Information System (INIS)

    Myers, Philip C.

    2011-01-01

    A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while the surrounding clump gas accretes as a power of protostar mass. Short accretion flows resemble Shu accretion and make low-mass stars. Long flows resemble reduced Bondi accretion and make massive stars. Accretion stops due to environmental processes of dynamical ejection, gravitational competition, and gas dispersal by stellar feedback, independent of initial core structure. The model matches the field star initial mass function (IMF) from 0.01 to more than 10 solar masses. The core accretion rate and the mean accretion duration set the peak of the IMF, independent of the local Jeans mass. Massive protostars require the longest accretion durations, up to 0.5 Myr. The maximum protostar luminosity in a cluster indicates the mass and age of its oldest protostar. The distribution of protostar luminosities matches those in active star-forming regions if protostars have a constant birthrate but not if their births are coeval. For constant birthrate, the ratio of young stellar objects to protostars indicates the star-forming age of a cluster, typically ∼1 Myr. The protostar accretion luminosity is typically less than its steady spherical value by a factor of ∼2, consistent with models of episodic disk accretion.

  14. Observations of non-linear plasmon damping in dense plasmas

    Science.gov (United States)

    Witte, B. B. L.; Sperling, P.; French, M.; Recoules, V.; Glenzer, S. H.; Redmer, R.

    2018-05-01

    We present simulations using finite-temperature density-functional-theory molecular-dynamics to calculate dynamic dielectric properties in warm dense aluminum. The comparison between exchange-correlation functionals in the Perdew, Burke, Ernzerhof approximation, Strongly Constrained and Appropriately Normed Semilocal Density Functional, and Heyd, Scuseria, Ernzerhof (HSE) approximation indicates evident differences in the electron transition energies, dc conductivity, and Lorenz number. The HSE calculations show excellent agreement with x-ray scattering data [Witte et al., Phys. Rev. Lett. 118, 225001 (2017)] as well as dc conductivity and absorption measurements. These findings demonstrate non-Drude behavior of the dynamic conductivity above the Cooper minimum that needs to be taken into account to determine optical properties in the warm dense matter regime.

  15. Three-phase flow analysis of dense nonaqueous phase liquid infiltration in horizontally layered porous media

    NARCIS (Netherlands)

    Wipfler, E.L.; Dijke, van M.I.J.; Zee, van der S.E.A.T.M.

    2004-01-01

    We considered dense nonaqueous phase liquid (DNAPL) infiltration into a water-unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. DNAPL is the intermediate-wetting fluid with respect to the wetting water

  16. Dense image correspondences for computer vision

    CERN Document Server

    Liu, Ce

    2016-01-01

    This book describes the fundamental building-block of many new computer vision systems: dense and robust correspondence estimation. Dense correspondence estimation techniques are now successfully being used to solve a wide range of computer vision problems, very different from the traditional applications such techniques were originally developed to solve. This book introduces the techniques used for establishing correspondences between challenging image pairs, the novel features used to make these techniques robust, and the many problems dense correspondences are now being used to solve. The book provides information to anyone attempting to utilize dense correspondences in order to solve new or existing computer vision problems. The editors describe how to solve many computer vision problems by using dense correspondence estimation. Finally, it surveys resources, code, and data necessary for expediting the development of effective correspondence-based computer vision systems.   ·         Provides i...

  17. Fluid Mechanics.

    Science.gov (United States)

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  18. Fluids with highly directional attractive forces. IV. Equilibrium polymerization

    International Nuclear Information System (INIS)

    Wertheim, M.S.

    1986-01-01

    The author investigates approximation methods for systems of molecules interacting by core repulsion and highly directional attraction due to several attraction sites. The force model chosen imitates a chemical bond by providing for bond saturation when binding occurs. The dense fluid is an equilibrium mixture of s-mers with mutual repulsion. The author uses a previously derived reformulation of statistical thermodynamics in which the particle species are monomeric units with a specified set of attraction sites bonded. Thermodynamic perturbation theory (TPT) and integral equations of two types are derived. The use of TPT is illustrated by explicit calculation for a molecular model with two attraction sites capable of forming chain and ring polymers. Successes and defects of TPT are discussed. The integral equations for pair correlations between particles of specified bonding include calculation of self-consistent densities of species. Methods of calculating thermodynamic properties from the solutions of integral equations are given

  19. 16. Hot dense plasma atomic processes

    International Nuclear Information System (INIS)

    Werner, Dappen; Totsuji, H.; Nishii, Y.

    2002-01-01

    This document gathers 13 articles whose common feature is to deal with atomic processes in hot plasmas. Density functional molecular dynamics method is applied to the hydrogen plasma in the domain of liquid metallic hydrogen. The effects of the density gradient are taken into account in both the electronic kinetic energy and the exchange energy and it is shown that they almost cancel with each other, extending the applicability of the Thomas-Fermi-Dirac approximation to the cases where the density gradient is not negligible. Another article reports about space and time resolved M-shell X-ray measurements of a laser-produced gas jet xenon plasma. Plasma parameters have been measured by ion acoustic and electron plasma waves Thomson scattering. Photo-ionization becomes a dominant atomic process when the density and the temperature of plasmas are relatively low and when the plasma is submitted to intense external radiation. It is shown that 2 plasmas which have a very different density but have the same ionization parameters, are found in a similar ionization state. Most radiation hydrodynamics codes use radiative opacity data from available libraries of atomic data. Several articles are focused on the determination of one group Rosseland and Planck mean analytical formulas for several single elements used in inertial fusion targets. In another paper the plasma density effect on population densities, effective ionization, recombination rate coefficients and on emission lines from carbon and Al ions in hot dense plasma, is studied. The last article is devoted to a new atomic model in plasmas that considers the occupation probability of the bound state and free state density in the presence of the plasma micro-field. (A.C.)

  20. Laboratory and modeling studies of chemistry in dense molecular clouds

    Science.gov (United States)

    Huntress, W. T., Jr.; Prasad, S. S.; Mitchell, G. F.

    1980-01-01

    A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

  1. Plasmon-polariton modes of dense Au nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hongdan; Lemmens, Peter; Wulferding, Dirk; Cetin, Mehmet Fatih [IPKM, TU-BS, Braunschweig (Germany); Tornow, Sabine; Zwicknagl, Gertrud [IMP, TU-BS, Braunschweig (Germany); Krieg, Ulrich; Pfnuer, Herbert [IFP, LU Hannover (Germany); Daum, Winfried; Lilienkamp, Gerhard [IEPT, TU Clausthal (Germany); Schilling, Meinhard [EMG, TU-BS, Braunschweig (Germany)

    2011-07-01

    Using optical absorption and other techniques we study plasmon-polariton modes of dense Au nanowire arrays as function of geometrical parameters and coupling to molecular degrees of freedom. For this instance we electrochemically deposit Au nanowires in porous alumina with well controlled morphology and defect concentration. Transverse and longitudinal modes are observed in the absorption spectra resulting from the anisotropic plasmonic structure. The longitudinal mode shows a blue shift of energy with increasing length of the wires due to the more collective nature of this response. We compare our observations with model calculations and corresponding results on 2D Ag nanowire lattices.

  2. Composite systems of dilute and dense couplings

    International Nuclear Information System (INIS)

    Raymond, J R; Saad, D

    2008-01-01

    Composite systems, where couplings are of two types, a combination of strong dilute and weak dense couplings of Ising spins, are examined through the replica method. The dilute and dense parts are considered to have independent canonical disordered or uniform bond distributions; mixing the models by variation of a parameter γ alongside inverse temperature β we analyse the respective thermodynamic solutions. We describe the variation in high temperature transitions as mixing occurs; in the vicinity of these transitions we exactly analyse the competing effects of the dense and sparse models. By using the replica symmetric ansatz and population dynamics we described the low temperature behaviour of mixed systems

  3. DFT studies of fluid-minerals interactions at the molecular level: examples and perspectives; Etudes DFT des interactions fluides-mineraux a l'echelle moleculaire: exemples et perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Toulhoat, H.; Digne, M.; Arrouvel, C.; Raybaud, P. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    2005-03-15

    The scope of applications of first-principle theoretical chemistry methods has been vastly expanded over the past years due to the combination of improved methods and algorithms for solving the poly-electronic Schroedinger equation with exponential growth of computer power available at constant cost (the so-called 'Moore law'). In particular, atomistic studies of solid-fluid interfaces are now routinely producing new qualitative and quantitative insights into adsorption, surface speciation as a function of the prevailing chemical potentials, and reactivity of surface species. This approach is currently widely exploited in the fields of heterogeneous catalysis and surface physics, and so far to a lesser extent for geochemical purposes, although the situation is rapidly evolving. Many fundamental issues of fluid-minerals interaction phenomena can indeed be addressed ab initio with atomistic 3D periodic models of fluid-solid interfaces involving up to 200-300 un-equivalent atoms. We illustrate this proposal with recent IFP results, some of which are of primary interest with respect to the manufacture of catalysts supports, but which also show some relevance for inorganic geochemical issues in the context of the sequestration of acid gases in subsurface porous rocks: - reactive wetting of boehmite AlOOH and morphology prediction; - acid-basic surface properties of a transition alumina; - hydroxylation and sulfhydrylation of anatase TiO{sub 2} surfaces. Through these examples, the performances of DFT and a variety of up-to-date modeling techniques and strategies are discussed. (authors)

  4. Isotopologues of dense gas tracers in NGC 1068

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junzhi; Qiu, Jianjie [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, 200030, Shanghai (China); Zhang, Zhi-Yu [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Shi, Yong [School of Astronomy and Space Science, Nanjing University, Nanjing, 210093 (China); Zhang, Jiangshui [Center For Astrophysics, GuangZhou University, 510006, GuangZhou (China); Fang, Min, E-mail: jzwang@shao.ac.cn [ESO, Karl Schwarzschild Strasse 2, D-85748 Garching bei Munich (Germany)

    2014-11-20

    We present observations of isotopic lines of dense gas tracers toward the nuclear region of nearby Seyfert 2 galaxy NGC 1068 with the IRAM 30 m telescope and the Atacama Pathfinder Experiment (APEX) 12 m telescope. We detected four isotopic lines (H{sup 13}CN 1-0, H{sup 13}CO{sup +} 1-0, HN{sup 13}C 1-0, and HC{sup 18}O{sup +} 1-0) at the 3 mm band with the IRAM 30 m telescope and obtained upper limits of other lines. We calculated optical depths of dense gas tracers with the detected isotopic lines of HCN 1-0, HCO{sup +} 1-0, and HNC 1-0. We find that the {sup 14}N/{sup 15}N abundance ratio is greater than 420 if we adopt the upper limit of HC{sup 15}N(1-0) emission. Combining this with fluxes of 1-0 lines from IRAM 30 m observations and the upper limit of 3-2 lines from APEX 12 m observations, we also estimated the excitation condition of molecular gas in the nuclear region of NGC 1068, which is less dense than that in the extreme starburst regions of galaxies.

  5. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    International Nuclear Information System (INIS)

    Kepley, Amanda A.; Frayer, David; Leroy, Adam K.; Usero, Antonio; Marvil, Josh; Walter, Fabian

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO + . Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO + in the starburst galaxy M82. The HCN and HCO + in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO + emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction

  6. The Linked Neighbour List (LNL) method for fast off-lattice Monte Carlo simulations of fluids

    Science.gov (United States)

    Mazzeo, M. D.; Ricci, M.; Zannoni, C.

    2010-03-01

    We present a new algorithm, called linked neighbour list (LNL), useful to substantially speed up off-lattice Monte Carlo simulations of fluids by avoiding the computation of the molecular energy before every attempted move. We introduce a few variants of the LNL method targeted to minimise memory footprint or augment memory coherence and cache utilisation. Additionally, we present a few algorithms which drastically accelerate neighbour finding. We test our methods on the simulation of a dense off-lattice Gay-Berne fluid subjected to periodic boundary conditions observing a speedup factor of about 2.5 with respect to a well-coded implementation based on a conventional link-cell. We provide several implementation details of the different key data structures and algorithms used in this work.

  7. Finding dense locations in indoor tracking data

    DEFF Research Database (Denmark)

    Ahmed, Tanvir; Pedersen, Torben Bach; Lu, Hua

    2014-01-01

    for semi-constrained indoor movement, and then uses this to map raw tracking records into mapping records representing object entry and exit times in particular locations. Then, an efficient indexing structure, the Dense Location Time Index (DLT-Index) is proposed for indexing the time intervals...... of the mapping table, along with associated construction, query processing, and pruning techniques. The DLT-Index supports very efficient aggregate point queries, interval queries, and dense location queries. A comprehensive experimental study with real data shows that the proposed techniques can efficiently......Finding the dense locations in large indoor spaces is very useful for getting overloaded locations, security, crowd management, indoor navigation, and guidance. Indoor tracking data can be very large and are not readily available for finding dense locations. This paper presents a graph-based model...

  8. Interference Coordination for Dense Wireless Networks

    DEFF Research Database (Denmark)

    Soret, Beatriz; Pedersen, Klaus I.; Jørgensen, Niels T.K.

    2015-01-01

    and dense deployment in Tokyo are compared. Evolution to DenseNets offers new opportunities for further development of downlink interference cooperation techniques. Various mechanisms in LTE and LTE-Advanced are revisited. Some techniques try to anticipate the future in a proactive way, whereas others......The promise of ubiquitous and super-fast connectivity for the upcoming years will be in large part fulfilled by the addition of base stations and spectral aggregation. The resulting very dense networks (DenseNets) will face a number of technical challenges. Among others, the interference emerges...... as an old acquaintance with new significance. As a matter of fact, the interference conditions and the role of aggressor and victim depend to a large extent on the density and the scenario. To illustrate this, downlink interference statistics for different 3GPP simulation scenarios and a more irregular...

  9. Skyrmions, dense matter and nuclear forces

    International Nuclear Information System (INIS)

    Pethick, C.J.

    1984-12-01

    A simple introduction to a number of properties of Skyrme's chiral soliton model of baryons is given. Some implications of the model for dense matter and for nuclear interactions are discussed. (orig.)

  10. Fluids engineering

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Fluids engineering has played an important role in many applications, from ancient flood control to the design of high-speed compact turbomachinery. New applications of fluids engineering, such as in high-technology materials processing, biotechnology, and advanced combustion systems, have kept up unwaining interest in the subject. More accurate and sophisticated computational and measurement techniques are also constantly being developed and refined. On a more fundamental level, nonlinear dynamics and chaotic behavior of fluid flow are no longer an intellectual curiosity and fluid engineers are increasingly interested in finding practical applications for these emerging sciences. Applications of fluid technology to new areas, as well as the need to improve the design and to enhance the flexibility and reliability of flow-related machines and devices will continue to spur interest in fluids engineering. The objectives of the present seminar were: to exchange current information on arts, science, and technology of fluids engineering; to promote scientific cooperation between the fluids engineering communities of both nations, and to provide an opportunity for the participants and their colleagues to explore possible joint research programs in topics of high priority and mutual interest to both countries. The Seminar provided an excellent forum for reviewing the current state and future needs of fluids engineering for the two nations. With the Seminar ear-marking the first formal scientific exchange between Korea and the United States in the area of fluids engineering, the scope was deliberately left broad and general

  11. Dynamical theory of dense groups of galaxies

    Science.gov (United States)

    Mamon, Gary A.

    1990-01-01

    It is well known that galaxies associate in groups and clusters. Perhaps 40% of all galaxies are found in groups of 4 to 20 galaxies (e.g., Tully 1987). Although most groups appear to be so loose that the galaxy interactions within them ought to be insignificant, the apparently densest groups, known as compact groups appear so dense when seen in projection onto the plane of the sky that their members often overlap. These groups thus appear as dense as the cores of rich clusters. The most popular catalog of compact groups, compiled by Hickson (1982), includes isolation among its selection critera. Therefore, in comparison with the cores of rich clusters, Hickson's compact groups (HCGs) appear to be the densest isolated regions in the Universe (in galaxies per unit volume), and thus provide in principle a clean laboratory for studying the competition of very strong gravitational interactions. The $64,000 question here is then: Are compact groups really bound systems as dense as they appear? If dense groups indeed exist, then one expects that each of the dynamical processes leading to the interaction of their member galaxies should be greatly enhanced. This leads us to the questions: How stable are dense groups? How do they form? And the related question, fascinating to any theorist: What dynamical processes predominate in dense groups of galaxies? If HCGs are not bound dense systems, but instead 1D change alignments (Mamon 1986, 1987; Walke & Mamon 1989) or 3D transient cores (Rose 1979) within larger looser systems of galaxies, then the relevant question is: How frequent are chance configurations within loose groups? Here, the author answers these last four questions after comparing in some detail the methods used and the results obtained in the different studies of dense groups.

  12. Kinetic chemistry of dense interstellar clouds

    International Nuclear Information System (INIS)

    Graedel, T.E.; Langer, W.D.; Frerking, M.A.

    1982-01-01

    A detailed model of the time-dependent chemistry of dense interstellar clouds has been developed to study the dominant chemical processes in carbon and oxygen isotope fractionation, formation of nitrogen-containing molecules, evolution of product molecules as a function of cloud density and temperature, and other topics of interest. The full computation involves 328 individual reactions (expanded to 1067 to study carbon and oxygen isotope chemistry); photodegradation processes are unimportant in these dense clouds and are excluded

  13. Quantum Simulations for Dense Matter

    International Nuclear Information System (INIS)

    Ceperley, David M.

    2010-01-01

    High pressure systems are important, for example, to understand the interiors of giant planets (Jupiter and Saturn), for experiments at NIF (the National Ignition Facility at Livermore) related to inertially confined fusion and for other interests of DOE. In this project, we are developing innovative simulation methods (Quantum Monte Carlo methods) to allow more accurate calculation of properties of systems under extreme conditions of pressure and temperature. These methods can use the power of current day supercomputers made of very many processors, starting from the basic equations of physics to model quantum phenomena important at the microscopic scale. During the grant period, we have settled two important questions of the physics of hydrogen and helium under extreme conditions. We have found the pressures and temperatures when hydrogen and helium mix together; this is important to understand the difference of the interiors of the planets Jupiter and Saturn. Secondly, we have shown that there exists a sharp transition as a function of pressure between molecular and atomic liquid hydrogen at temperatures below 2000K. This prediction can be confirmed with high pressure experiments.

  14. Buffer fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mirzadzhanzade, A Kh; Dedusanko, G Ya; Dinaburg, L S; Markov, Yu M; Rasizade, Ya N; Rozov, V N; Sherstnev, N M

    1979-08-30

    A drilling fluid is suggested for separating the drilling and plugging fluids which contains as the base increased solution of polyacrylamide and additive. In order to increase the viscoelastic properties of the liquid with simultaneous decrease in the periods of its fabrication, the solution contains as an additive dry bentonite clay. In cases of the use of a buffer fluid under conditions of negative temperatures, it is necessary to add to it table salt or ethylene glycol.

  15. Supercritical fluid analytical methods

    International Nuclear Information System (INIS)

    Smith, R.D.; Kalinoski, H.T.; Wright, B.W.; Udseth, H.R.

    1988-01-01

    Supercritical fluids are providing the basis for new and improved methods across a range of analytical technologies. New methods are being developed to allow the detection and measurement of compounds that are incompatible with conventional analytical methodologies. Characterization of process and effluent streams for synfuel plants requires instruments capable of detecting and measuring high-molecular-weight compounds, polar compounds, or other materials that are generally difficult to analyze. The purpose of this program is to develop and apply new supercritical fluid techniques for extraction, separation, and analysis. These new technologies will be applied to previously intractable synfuel process materials and to complex mixtures resulting from their interaction with environmental and biological systems

  16. A Thermodynamically-Consistent Non-Ideal Stochastic Hard-Sphere Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Donev, A; Alder, B J; Garcia, A L

    2009-08-03

    A grid-free variant of the Direct Simulation Monte Carlo (DSMC) method is proposed, named the Isotropic DSMC (I-DSMC) method, that is suitable for simulating collision-dominated dense fluid flows. The I-DSMC algorithm eliminates all grid artifacts from the traditional DSMC algorithm and is Galilean invariant and microscopically isotropic. The stochastic collision rules in I-DSMC are modified to introduce a non-ideal structure factor that gives consistent compressibility, as first proposed in [Phys. Rev. Lett. 101:075902 (2008)]. The resulting Stochastic Hard Sphere Dynamics (SHSD) fluid is empirically shown to be thermodynamically identical to a deterministic Hamiltonian system of penetrable spheres interacting with a linear core pair potential, well-described by the hypernetted chain (HNC) approximation. We develop a kinetic theory for the SHSD fluid to obtain estimates for the transport coefficients that are in excellent agreement with particle simulations over a wide range of densities and collision rates. The fluctuating hydrodynamic behavior of the SHSD fluid is verified by comparing its dynamic structure factor against theory based on the Landau-Lifshitz Navier-Stokes equations. We also study the Brownian motion of a nano-particle suspended in an SHSD fluid and find a long-time power-law tail in its velocity autocorrelation function consistent with hydrodynamic theory and molecular dynamics calculations.

  17. Thermostating highly confined fluids.

    Science.gov (United States)

    Bernardi, Stefano; Todd, B D; Searles, Debra J

    2010-06-28

    In this work we show how different use of thermostating devices and modeling of walls influence the mechanical and dynamical properties of confined nanofluids. We consider a two dimensional fluid undergoing Couette flow using nonequilibrium molecular dynamics simulations. Because the system is highly inhomogeneous, the density shows strong fluctuations across the channel. We compare the dynamics produced by applying a thermostating device directly to the fluid with that obtained when the wall is thermostated, considering also the effects of using rigid walls. This comparison involves an analysis of the chaoticity of the fluid and evaluation of mechanical properties across the channel. We look at two thermostating devices with either rigid or vibrating atomic walls and compare them with a system only thermostated by conduction through vibrating atomic walls. Sensitive changes are observed in the xy component of the pressure tensor, streaming velocity, and density across the pore and the Lyapunov localization of the fluid. We also find that the fluid slip can be significantly reduced by rigid walls. Our results suggest caution in interpreting the results of systems in which fluid atoms are thermostated and/or wall atoms are constrained to be rigid, such as, for example, water inside carbon nanotubes.

  18. Potential of mean force for electrical conductivity of dense plasmas

    Science.gov (United States)

    Starrett, C. E.

    2017-12-01

    The electrical conductivity in dense plasmas can be calculated with the relaxation-time approximation provided that the interaction potential between the scattering electron and the ion is known. To date there has been considerable uncertainty as to the best way to define this interaction potential so that it correctly includes the effects of ionic structure, screening by electrons and partial ionization. Current approximations lead to significantly different results with varying levels of agreement when compared to bench-mark calculations and experiments. We present a new way to define this potential, drawing on ideas from classical fluid theory to define a potential of mean force. This new potential results in significantly improved agreement with experiments and bench-mark calculations, and includes all the aforementioned physics self-consistently.

  19. Flow of Dense Granular Suspensions on an Inclined Plane

    Science.gov (United States)

    Bonnoit, C.; Lanuza, J.; Lindner, A.; Clément, E.

    2008-07-01

    We investigate the flow behavior of dense granular suspensions, by the use of an inclined plane. The suspensions are prepared at high packing fractions and consist of spherical non-Brownian particles density matched with the suspending fluid. On the inclined plane, we perform a systematic study of the surface velocity as a function of the layer thickness for various flow rates and tilt angles. We perform measurements on a classical rheometer (parallel-plate rheometer) that is shown to be in good agreement with existing models, up to a volume fraction of 50%. Comparing these results, we show that the flow on an inclined plane can, up to a volume fraction of 50%, indeed be described by a purely viscous model in agreement with the results from classical rheometry.

  20. Schroedinger fluid

    International Nuclear Information System (INIS)

    Kan, K.K.

    1983-01-01

    The relationship of nuclear internal flow and collective inertia, the difference of this flow from that of a classical fluid, and the approach of this flow to rigid flow in independent-particle model rotation are elucidated by reviewing the theory of Schroedinger fluid and its implications for collective vibration and rotation. (author)

  1. Is trabecular bone permeability governed by molecular ordering-induced fluid viscosity gain? Arguments from re-evaluation of experimental data in the framework of homogenization theory.

    Science.gov (United States)

    Abdalrahman, T; Scheiner, S; Hellmich, C

    2015-01-21

    It is generally agreed on that trabecular bone permeability, a physiologically important quantity, is governed by the material׳s (vascular or intertrabecular) porosity as well as by the viscosity of the pore-filling fluids. Still, there is less agreement on how these two key factors govern bone permeability. In order to shed more light onto this somewhat open issue, we here develop a random homogenization scheme for upscaling Poiseuille flow in the vascular porosity, up to Darcy-type permeability of the overall porous medium "trabecular bone". The underlying representative volume element of the macroscopic bone material contains two types of phases: a spherical, impermeable extracellular bone matrix phase interacts with interpenetrating cylindrical pore channel phases that are oriented in all different space directions. This type of interaction is modeled by means of a self-consistent homogenization scheme. While the permeability of the bone matrix equals to zero, the permeability of the pore phase is found through expressing the classical Hagen-Poiseuille law for laminar flow in the format of a "micro-Darcy law". The upscaling scheme contains pore size and porosity as geometrical input variables; however, they can be related to each other, based on well-known relations between porosity and specific bone surface. As two key results, validated through comprehensive experimental data, it appears (i) that the famous Kozeny-Carman constant (which relates bone permeability to the cube of the porosity, the square of the specific surface, as well as to the bone fluid viscosity) needs to be replaced by an again porosity-dependent rational function, and (ii) that the overall bone permeability is strongly affected by the pore fluid viscosity, which, in case of polarized fluids, is strongly increased due to the presence of electrically charged pore walls. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Affinity chromatographic purification of tetrodotoxin by use of tetrodotoxin-binding high molecular weight substances in the body fluid of shore crab (Hemigrapsus sanguineus) as ligands.

    Science.gov (United States)

    Shiomi, K; Yamaguchi, S; Shimakura, K; Nagashima, Y; Yamamori, K; Matsui, T

    1993-12-01

    A purification method for tetrodotoxin (TTX), based on affinity chromatography using the TTX-binding high mol. wt substances in the body fluid of shore crab (Hemigrapsus sanguineus) as ligands, was developed. This method was particularly useful for analysis of TTX in biological samples with low concentrations of TTX. The affinity gel prepared was highly specific for TTX, having no ability to bind 4-epi-TTX and anhydro-TTX as well as saxitoxin.

  3. Ab initio calculation of the sound velocity of dense hydrogen: implications for models of Jupiter

    NARCIS (Netherlands)

    Alavi, A.; Parrinello, M.; Frenkel, D.

    1995-01-01

    First-principles molecular dynamics simulations were used to calculate the sound velocity of dense hydrogen, and the results were compared with extrapolations of experimental data that currently conflict with either astrophysical models or data obtained from recent global oscillation measurements of

  4. Calculation of Transport Coefficients in Dense Plasma Mixtures

    Science.gov (United States)

    Haxhimali, T.; Cabot, W. H.; Caspersen, K. J.; Greenough, J.; Miller, P. L.; Rudd, R. E.; Schwegler, E. R.

    2011-10-01

    We use classical molecular dynamics (MD) to estimate species diffusivity and viscosity in mixed dense plasmas. The Yukawa potential is used to describe the screened Coulomb interaction between the ions. This potential has been used widely, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green- Kubo relation over a range of thermodynamic conditions including the viscosity and the self - diffusivity for each component of the mixture. The interdiffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate interdiffusivity during the broadening of the interface between two regions each with a high concentration of either species. Here we present results for an asymmetric mixture between Ar and H. These can easily be extended to other plasma mixtures. A main motivation for this study is to develop accurate transport models that can be incorporated into the hydrodynamic codes to study hydrodynamic instabilities. We use classical molecular dynamics (MD) to estimate species diffusivity and viscosity in mixed dense plasmas. The Yukawa potential is used to describe the screened Coulomb interaction between the ions. This potential has been used widely, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green- Kubo relation over a range of thermodynamic conditions including the viscosity and the self - diffusivity for each component of the mixture. The interdiffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate interdiffusivity during

  5. Constitutive law of dense granular matter

    International Nuclear Information System (INIS)

    Hatano, Takahiro

    2010-01-01

    The frictional properties of dense granular matter under steady shear flow are investigated using numerical simulation. Shear flow tends to localize near the driving boundary unless the coefficient of restitution is close to zero and the driving velocity is small. The bulk friction coefficient is independent of shear rate in dense and slow flow, whereas it is an increasing function of shear rate in rapid flow. The coefficient of restitution affects the friction coefficient only in such rapid flow. Contrastingly, in dense and slow regime, the friction coefficient is independent of the coefficient of restitution and mainly determined by the elementary friction coefficient and the rotation of grains. It is found that the mismatch between the vorticity of flow and the angular frequency of grains plays a key role to the frictional properties of sheared granular matter.

  6. INTERACTIONS BETWEEN FORMING STARS AND DENSE GAS IN THE SMALL LOW-MASS CLUSTER CEDERBLAD 110

    Energy Technology Data Exchange (ETDEWEB)

    Ladd, E. F. [Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837 (United States); Wong, T. [Department of Astronomy, University of Illinois, Urbana, IL 61801 (United States); Bourke, T. L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Thompson, K. L., E-mail: ladd@bucknell.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)

    2011-12-20

    We present observations of dense gas and outflow activity in the Cederblad 110 region of the Chamaeleon I dark cloud complex. The region contains nine forming low-mass stars in evolutionary stages ranging from Class 0 to Class II/III crowded into a 0.2 pc region with high surface density ({Sigma}{sub YSO} {approx} 150 pc{sup -2}). The analysis of our N{sub 2}H{sup +} (J = 1{yields}0) maps indicates the presence of 13 {+-} 3 solar masses of dense (n {approx} 10{sup 5} cm{sup -3}) gas in this region, much of which is unstable against gravitational collapse. The most unstable material is located near the Class 0 source MMS-1, which is almost certainly actively accreting material from its dense core. Smaller column densities of more stable dense gas are found toward the region's Class I sources, IRS 4, 11, and 6. Little or no dense gas is colocated with the Class II and III sources in the region. The outflow from IRS 4 is interacting with the dense core associated with MMS-1. The molecular component of the outflow, measured in the (J = 1{yields}0) line of {sup 12}CO, appears to be deflected by the densest part of the core, after which it appears to plow through some of the lower column density portions of the core. The working surface between the head of the outflow lobe and the dense core material can be seen in the enhanced velocity dispersion of the dense gas. IRS 2, the Class III source that produces the optical reflection nebula that gives the Cederblad 110 region its name, may also be influencing the dense gas in the region. A dust temperature gradient across the MMS-1 dense core is consistent with warming from IRS 2, and a sharp gradient in dense gas column density may be caused by winds from this source. Taken together, our data indicate that this region has been producing several young stars in the recent past, and that sources which began forming first are interacting with the remaining dense gas in the region, thereby influencing current and future star

  7. Magnetic fluid seals for DWDM filter manufacturing

    International Nuclear Information System (INIS)

    Li Zhixin

    2002-01-01

    Performance requirements of rotary magnetic fluid seals for thin film dense wavelength division multiplexing filter manufacturing are discussed. High speed, large diameter, tight tolerance for rotating accuracy and motion control are some of the technical challenges in this application. Analytical methods for studying these technical issues and experimental data are presented. Innovative design approaches are also discussed. It is shown that using the most advanced magnetic fluid technology and seal design technology, magnetic fluid seals can provide satisfactory performance in this challenging new application

  8. Nucleon structure and properties of dense matter

    International Nuclear Information System (INIS)

    Kutschera, M.; Pethick, C.J.; Illinois Univ., Urbana, IL

    1988-01-01

    We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n 4/3 , n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)

  9. Fast Solvers for Dense Linear Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kauers, Manuel [Research Institute for Symbolic Computation (RISC), Altenbergerstrasse 69, A4040 Linz (Austria)

    2008-10-15

    It appears that large scale calculations in particle physics often require to solve systems of linear equations with rational number coefficients exactly. If classical Gaussian elimination is applied to a dense system, the time needed to solve such a system grows exponentially in the size of the system. In this tutorial paper, we present a standard technique from computer algebra that avoids this exponential growth: homomorphic images. Using this technique, big dense linear systems can be solved in a much more reasonable time than using Gaussian elimination over the rationals.

  10. Flexible fiber in interaction with a dense granular flow close to the jamming transition

    Directory of Open Access Journals (Sweden)

    Algarra Nicolas

    2017-01-01

    Full Text Available We propose a new fluid/structure interaction in the unusual case of a dense granular medium flowing against an elastic fiber acting as a flexible intruder. We study experimentally the reconfiguration and the forces exerted on the flexible fiber produced by the flow at a constant and low velocity of a two-dimensional disordered packing of grains close but below the jamming transition.

  11. Flexible fiber in interaction with a dense granular flow close to the jamming transition

    Science.gov (United States)

    Algarra, Nicolas; Leang, Marguerite; Lazarus, Arnaud; Vandembroucq, Damien; Kolb, Evelyne

    2017-06-01

    We propose a new fluid/structure interaction in the unusual case of a dense granular medium flowing against an elastic fiber acting as a flexible intruder. We study experimentally the reconfiguration and the forces exerted on the flexible fiber produced by the flow at a constant and low velocity of a two-dimensional disordered packing of grains close but below the jamming transition.

  12. Stable solitary waves in super dense plasmas at external magnetic fields

    Science.gov (United States)

    Ghaani, Azam; Javidan, Kurosh; Sarbishaei, Mohsen

    2015-07-01

    Propagation of localized waves in a Fermi-Dirac distributed super dense matter at the presence of strong external magnetic fields is studied using the reductive perturbation method. We have shown that stable solitons can be created in such non-relativistic fluids in the presence of an external magnetic field. Such solitary waves are governed by the Zakharov-Kuznetsov (ZK) equation. Properties of solitonic solutions are studied in media with different values of background mass density and strength of magnetic field.

  13. Effect of particle size distribution and concentration on flow behavior of dense slurries

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Chára, Zdeněk

    2011-01-01

    Roč. 29, č. 1 (2011), s. 53-65 ISSN 0272-6351 R&D Projects: GA ČR(CZ) GAP105/10/1574 Institutional research plan: CEZ:AV0Z20600510 Keywords : concentration effect * dense complex slurry * experimental investigation * flow behavior * particle size distribution effect * pressure drop Subject RIV: BK - Fluid Dynamics Impact factor: 0.545, year: 2011

  14. Fluid dynamics

    CERN Document Server

    Bernard, Peter S

    2015-01-01

    This book presents a focused, readable account of the principal physical and mathematical ideas at the heart of fluid dynamics. Graduate students in engineering, applied math, and physics who are taking their first graduate course in fluids will find this book invaluable in providing the background in physics and mathematics necessary to pursue advanced study. The book includes a detailed derivation of the Navier-Stokes and energy equations, followed by many examples of their use in studying the dynamics of fluid flows. Modern tensor analysis is used to simplify the mathematical derivations, thus allowing a clearer view of the physics. Peter Bernard also covers the motivation behind many fundamental concepts such as Bernoulli's equation and the stream function. Many exercises are designed with a view toward using MATLAB or its equivalent to simplify and extend the analysis of fluid motion including developing flow simulations based on techniques described in the book.

  15. Dense high temperature ceramic oxide superconductors

    Science.gov (United States)

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  16. Dense high-temperature plasma transport processes

    International Nuclear Information System (INIS)

    Giniyatova, Sh.G.

    2002-01-01

    In this work the transport processes in dense high-temperature semiclassical plasma are studied on the base of the kinetic equation, where the semiclassical potential was used, in its collision integral. The coefficient of plasma electrical conductivity, viscosity and thermal conductivity were received. There were compared with the other authors' results. The Grad's method was used obtaining of viscosity and thermal coefficients. (author)

  17. The electronic pressure in dense plasmas

    International Nuclear Information System (INIS)

    Pozwolski, A.E.

    1982-01-01

    A thermodynamic calculation of the electronic pressure in a dense plasma is given. Approximations involved by the use of the Debye length are avoided, so the above theory remains valid even if the Debye length is smaller than the interionic distance. (author)

  18. APT: Action localization Proposals from dense Trajectories

    NARCIS (Netherlands)

    van Gemert, J.C.; Jain, M.; Gati, E.; Snoek, C.G.M.; Xie, X.; Jones, M.W.; Tam, G.K.L.

    2015-01-01

    This paper is on action localization in video with the aid of spatio-temporal proposals. To alleviate the computational expensive video segmentation step of existing proposals, we propose bypassing the segmentations completely by generating proposals directly from the dense trajectories used to

  19. Dense Alternating Sign Matrices and Extensions

    Czech Academy of Sciences Publication Activity Database

    Fiedler, Miroslav; Hall, F.J.; Stroev, M.

    2014-01-01

    Roč. 444, 1 March (2014), s. 219-226 ISSN 0024-3795 Institutional support: RVO:67985807 Keywords : alternating sign matrix * dense matrix * totally unimodular matrix * combined matrix * generalized complementary basic matrix Subject RIV: BA - General Mathematics Impact factor: 0.939, year: 2014

  20. Coalescence preference in dense packing of bubbles

    Science.gov (United States)

    Kim, Yeseul; Gim, Bopil; Gim, Bopil; Weon, Byung Mook

    2015-11-01

    Coalescence preference is the tendency that a merged bubble from the contact of two original bubbles (parent) tends to be near to the bigger parent. Here, we show that the coalescence preference can be blocked by densely packing of neighbor bubbles. We use high-speed high-resolution X-ray microscopy to clearly visualize individual coalescence phenomenon which occurs in micro scale seconds and inside dense packing of microbubbles with a local packing fraction of ~40%. Previous theory and experimental evidence predict a power of -5 between the relative coalescence position and the parent size. However, our new observation for coalescence preference in densely packed microbubbles shows a different power of -2. We believe that this result may be important to understand coalescence dynamics in dense packing of soft matter. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST and also was supported by Ministry of Science, ICT and Future Planning (2009-0082580) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry and Education, Science and Technology (NRF-2012R1A6A3A04039257).

  1. Probing dense matter with strange hadrons

    CERN Document Server

    Rafelski, Johann; Rafelski, Johann; Letessier, Jean

    2002-01-01

    Analysis of hadron production experimental data allows to understand the properties of the dense matter fireball produced in relativistic heavy ion collisions. We interpret the analysis results and argue that color deconfined state has been formed at highest CERN-SPS energies and at BNL-RHIC.

  2. Description of a method for computing fluid-structure interaction

    International Nuclear Information System (INIS)

    Gantenbein, F.

    1982-02-01

    A general formulation allowing computation of structure vibrations in a dense fluid is described. It is based on fluid modelisation by fluid finite elements. For each fluid node are associated two variables: the pressure p and a variable π defined as p=d 2 π/dt 2 . Coupling between structure and fluid is introduced by surface elements. This method is easy to introduce in a general finite element code. Validation was obtained by analytical calculus and tests. It is widely used for vibrational and seismic studies of pipes and internals of nuclear reactors some applications are presented [fr

  3. Lattice cluster theory for dense, thin polymer films.

    Science.gov (United States)

    Freed, Karl F

    2015-04-07

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L - 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential "transport" constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends.

  4. Synthesis of Dense and Chiral Dendritic Polyols Using Glyconanosynthon Scaffolds

    Directory of Open Access Journals (Sweden)

    Tze Chieh Shiao

    2016-04-01

    Full Text Available Most classical dendrimers are frequently built-up from identical repeating units of low valency (usually AB2 monomers. This strategy necessitates several generations to achieve a large number of surface functionalities. In addition, these typical monomers are achiral. We propose herein the use of sugar derivatives consisting of several and varied functionalities with their own individual intrinsic chirality as both scaffolds/core as well as repeating units. This approach allows the construction of chiral, dense dendrimers with a large number of surface groups at low dendrimer generations. Perpropargylated β-D-glucopyranoside, serving as an A5 core, together with various derivatives, such as 2-azidoethyl tetra-O-allyl-β-D-glucopyranoside, serving as an AB4 repeating moiety, were utilized to construct chiral dendrimers using “click chemistry” (CuAAC reaction. These were further modified by thiol-ene and thiol-yne click reactions with alcohols to provide dendritic polyols. Molecular dynamic simulation supported the assumption that the resulting polyols have a dense structure.

  5. Lattice cluster theory for dense, thin polymer films

    International Nuclear Information System (INIS)

    Freed, Karl F.

    2015-01-01

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L − 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential “transport” constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends

  6. Stochastic entangled chain dynamics of dense polymer solutions.

    Science.gov (United States)

    Kivotides, Demosthenes; Wilkin, S Louise; Theofanous, Theo G

    2010-10-14

    We propose an adjustable-parameter-free, entangled chain dynamics model of dense polymer solutions. The model includes the self-consistent dynamics of molecular chains and solvent by describing the former via coarse-grained polymer dynamics that incorporate hydrodynamic interaction effects, and the latter via the forced Stokes equation. Real chain elasticity is modeled via the inclusion of a Pincus regime in the polymer's force-extension curve. Excluded volume effects are taken into account via the combined action of coarse-grained intermolecular potentials and explicit geometric tracking of chain entanglements. We demonstrate that entanglements are responsible for a new (compared to phantom chain dynamics), slow relaxation mode whose characteristic time scale agrees very well with experiment. Similarly good agreement between theory and experiment is also obtained for the equilibrium chain size. We develop methods for the solution of the model in periodic flow domains and apply them to the computation of entangled polymer solutions in equilibrium. We show that the number of entanglements Π agrees well with the number of entanglements expected on the basis of tube theory, satisfactorily reproducing the latter's scaling of Π with the polymer volume fraction φ. Our model predicts diminishing chain size with concentration, thus vindicating Flory's suggestion of excluded volume effects screening in dense solutions. The predicted scaling of chain size with φ is consistent with the heuristic, Flory theory based value.

  7. Phase diagram and transport properties for hydrogen-helium fluid planets

    International Nuclear Information System (INIS)

    Stevenson, D.J.; Salpeter, E.E.

    1977-01-01

    Hydrogen and helium are the major constituents of Jupiter and Saturn, and phase transitions can have important effects on the planetary structure. In this paper, the relevant phase diagrams and microscopic transport properties are analyzed in detail. The following paper (Paper II) applies these results to the evolution and present dynamic structure of the Jovian planets.Pure hydrogen is first discussed, especially the nature of the molecular-metallic transition and the melting curves for the two phases. It is concluded that at the temperatures and pressures of interest (Tapprox. =10 4 K, Papprox. =1--10 Mbar), both phases are fluid, but the transition between them might nevertheless be first-order. The insulator-metal transition in helium occurs at a much higher pressure (approx.70 Mbars) and is not of interest.The phase diagrams for both molecular and metallic hydrogen-helium mixtures are discussed. In the metallic mixture, calculations indicate a miscibility gap for T9 or approx. =10 4 K. Immiscibility in the molecular mixture is more difficult to predict but almost certainly occurs at much lower temperatures. A fluid-state model is constructed which predicts the likely topology of the three-dimensional phase diagram. The greater solubility of helium in the molecular phase leads to the prediction that the He/H mass ratio is typically twice as large in the molecular phase as in the coexisting metallic phase. Under these circumstances a ''density inversion'' is possible in which the molecular phase becomes more dense than the metallic phase.The partitioning of minor constituents is also considered: The deuterium/hydrogen mass ratio is essentially the same for all coexisting hydrogen-helium phases, at least for T> or approx. =5000 K. The partitioning of H 2 O, CH 4 , and NH 3 probably favors the molecular (or helium-rich) phase. Substances with high conduction electron density (e.g., Al) may partition into the metallic phase

  8. Molecular diagnosis of eosinophilic meningitis due to Angiostrongylus cantonensis (Nematoda: Metastrongyloidea by polymerase chain reaction-DNA sequencing of cerebrospinal fluids of patients

    Directory of Open Access Journals (Sweden)

    Praphathip Eamsobhana

    2013-02-01

    Full Text Available Cerebrospinal fluid (CSF samples from clinically diagnosed patients with detectable Angiostrongylus canto-nensis-specific antibodies (n = 10, patients with clinically suspected cases that tested negative for A. cantonensis-an-tibodies (n = 5 and patients with cerebral gnathostomiasis (n = 2 and neurocysticercosis (n = 2 were examined by a single-step polymerase chain reaction (PCR method using the AC primers for the 66-kDa native protein gene. The PCR method detected A. cantonensis DNA in CSF samples from four of 10 serologically confirmed angiostrongyliasis cases. The PCR results were negative for the remaining CSF samples. The nucleotide sequences of three positive CSF-PCR samples shared 98.8-99.2% similarity with the reference sequence of A. cantonensis. These results indicate the potential application of this PCR assay with clinical CSF samples for additional support in the confirmation of eosinophilic meningitis due to A. cantonensis.

  9. Fluid-bed process for SYNROC production

    International Nuclear Information System (INIS)

    Ackerman, F.J.; Grens, J.Z.; Ryerson, F.J.; Hoenig, C.L.; Bazan, F.; Peters, P.E.; Smith, R.; Campbell, J.H.

    1983-01-01

    SYNROC is a titanate-based ceramic waste developed for the immobilization of high-level nuclear reactor waste. Lawrence Livermore National Laboratory (LLNL) has investigated a fluid-bed technique for the large-scale production of SYNROC precursor powders. Making SYNROC in a fluid bed permits slurry drying, calcination and reduction-oxidation reactions to be carried out in a single unit. We present the results of SYNROC fluid-bed studies from two fluid-bed units 10 cm in diameter: an internally heated fluid-bed unit developed by Exxon Idaho and an externally heated unit constructed at LLNL. Bed operation over a range of temperatures, feed rates, fluidizing rates, and redox conditions indicate that SYNROC powders of a high density and a uniform particle size can be produced. These powders facilitate the densification step and yield dense ceramics (greater than 95% theoretical density) with well-developed phases and low leaching rates

  10. Modelling the Multiphase Flow in Dense Medium Cyclones

    Directory of Open Access Journals (Sweden)

    Kaiwei Chu

    2010-12-01

    Full Text Available Dense medium cyclone (DMC is widely used in mineral industry to separate solids by density. It is simple in design but the flow pattern within it is complex due to the size and density distributions of the feed and process medium solids, and the turbulent vortex formed. Recently, the so-called combined computational fluid dynamics (CFD and discrete element method (DEM (CFD-DEM was extended from two-phase flow to model the flow in DMCs at the University of New South Wales (UNSW. In the CFD-DEM model, the flow of coal particles is modelled by DEM and that of medium flow by CFD, allowing consideration of medium-coal mutual interaction and particle-particle collisions. In the DEM model, Newton's laws of motion are applied to individual particles, and in the CFD model the local-averaged Navier-Stokes equations combined with the volume of fluid (VOF and mixture multiphase flow models are solved. The application to the DMC studies requires intensive computational effort. Therefore, various simplified versions have been proposed, corresponding to the approaches such as Lagrangian particle tracking (LPT method where dilute phase flow is assumed so that the interaction between particles can be ignored, one-way coupling where the effect of particle flow on fluid flow is ignored, and the use of the concept of parcel particles whose properties are empirically determined. In this paper, the previous works on the modelling of DMCs at UNSW are summarized and the features and applicability of the models used are discussed.

  11. Quantum statistical mechanics of dense partially ionized hydrogen.

    Science.gov (United States)

    Dewitt, H. E.; Rogers, F. J.

    1972-01-01

    The theory of dense hydrogenic plasmas beginning with the two component quantum grand partition function is reviewed. It is shown that ionization equilibrium and molecular dissociation equilibrium can be treated in the same manner with proper consideration of all two-body states. A quantum perturbation expansion is used to give an accurate calculation of the equation of state of the gas for any degree of dissociation and ionization. In this theory, the effective interaction between any two charges is the dynamic screened potential obtained from the plasma dielectric function. We make the static approximation; and we carry out detailed numerical calculations with the bound and scattering states of the Debye potential, using the Beth-Uhlenbeck form of the quantum second virial coefficient. We compare our results with calculations from the Saha equation.

  12. Carbon molecular sieve membranes derived from Matrimid® polyimide for nitrogen/methane separation

    KAUST Repository

    Ning, Xue; Koros, William J.

    2014-01-01

    A commercial polyimide, Matrimid® 5218, was pyrolyzed under an inert argon atmosphere to produce carbon molecular sieve (CMS) dense film membranes for nitrogen/methane separation. The resulting CMS dense film separation performance was evaluated

  13. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2016-12-10

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step-size restriction as the method itself. A general recipe for first-order SSP dense output formulae for SSP methods is given, and second-order dense output formulae for several optimal SSP methods are developed. It is shown that SSP dense output formulae of order three and higher do not exist, and that in any method possessing a second-order SSP dense output, the coefficient matrix A has a zero row.

  14. Dense plasma focus - a literature review

    International Nuclear Information System (INIS)

    Tendys, J.

    1976-01-01

    The dense plasma focus (DPF) is a convenient source of short, intense neutron pulses, and dense, high temperature plasma. This review of the literature on the DPF indicates that its operation is still not understood, and attempts to show where the present data is either inadequate or inconsistent. Because the plasma conditions and neutron and x-ray fluxes vary from shot to shot, it is maintained that, to resolve inconsistencies in the present data, spectra need to be measured with energy and time resolution simultaneously, and cannot be built up from a large number of shots. Time resolutions of the order of 1 nsec for pulse lengths of about 100 nsec make these requirements especially difficult. Some theoretical models are presented for the neutron output and its spectrum, but no self-consistent description of the plasma in the focus region is likely for some time. (author)

  15. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei

    2015-01-01

    -ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation......Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X...

  16. Anomalous properties of hot dense nonequilibrium plasmas

    International Nuclear Information System (INIS)

    Ferrante, G; Zarcone, M; Uryupin, S A

    2005-01-01

    A concise overview of a number of anomalous properties of hot dense nonequilibrium plasmas is given. The possibility of quasistationary megagauss magnetic field generation due to Weibel instability is discussed for plasmas created in atom tunnel ionization. The collisionless absorption and reflection of a test electromagnetic wave normally impinging on the plasma with two-temperature bi-maxwellian electron velocity distribution function are studied. Due to the wave magnetic field influence on the electron kinetics in the skin layer the wave absorption and reflection significantly depend on the degree of the electron temperature anisotropy. The linearly polarized impinging wave during reflection transforms into an elliptically polarized one. The problem of transmission of an ultrashort laser pulse through a layer of dense plasma, formed as a result of ionization of a thin foil, is considered. It is shown that the strong photoelectron distribution anisotropy yields an anomalous penetration of the wave field through the foil

  17. Deterministic dense coding with partially entangled states

    Science.gov (United States)

    Mozes, Shay; Oppenheim, Jonathan; Reznik, Benni

    2005-01-01

    The utilization of a d -level partially entangled state, shared by two parties wishing to communicate classical information without errors over a noiseless quantum channel, is discussed. We analytically construct deterministic dense coding schemes for certain classes of nonmaximally entangled states, and numerically obtain schemes in the general case. We study the dependency of the maximal alphabet size of such schemes on the partially entangled state shared by the two parties. Surprisingly, for d>2 it is possible to have deterministic dense coding with less than one ebit. In this case the number of alphabet letters that can be communicated by a single particle is between d and 2d . In general, we numerically find that the maximal alphabet size is any integer in the range [d,d2] with the possible exception of d2-1 . We also find that states with less entanglement can have a greater deterministic communication capacity than other more entangled states.

  18. Dense-plasma research using ballistic compressors

    International Nuclear Information System (INIS)

    Hess, H.

    1986-01-01

    An introduction is given to research on dense (or nonideal) plasmas which can be generated to advantage by ballistic compressors. Some properties of ballistic compressors are discussed especially in comparison with shock tubes. A short review is given on the history of these devices for high-pressure plasma generation. The present state of the art is reported including research on the two ZIE (Central Institute for Electron Physics) ballistic compressors. (author)

  19. Studying dense plasmas with coherent XUV pulses

    International Nuclear Information System (INIS)

    Stabile, H.

    2006-12-01

    The investigation of dense plasma dynamic requires the development of diagnostics able to ensure the measurement of electronic density with micro-metric space resolution and sub-nanosecond, or even subpicosecond, time resolution (indeed this must be at least comparable with the characteristic tune scale of plasma evolution). In contrast with low-density plasmas, dense plasmas cannot be studied using optical probes in the visible domain, the density range accessible being limited to the critical density (N c equals 1.1*10 21 λ -2 (μm) ∼ 10 21 cm -3 for infrared). In addition, light is reflected even at smaller densities if the medium exhibits sharp density gradients. Hence probing of dense plasmas, for instance those produced by laser irradiation of solids, requires using shorter wavelength radiation. Thanks to their physical properties, high order harmonics generated in rare gases are particularly adapted to the study of dense plasmas. Indeed, they can naturally be synchronized with the generating laser and their pulse duration is very short, which makes it possible to use them in pump-probe experiments. Moreover, they exhibit good spatial and temporal coherencies. Two types of diagnostics were developed during this thesis. The first one was used to study the instantaneous creation of hot-solid-density plasma generated by focusing a femtosecond high-contrast laser on an ultra-thin foil (100 nm) in the 10 18 W/cm 2 intensity regime. The use of high order harmonics, providing a probe beam of sufficiently short wavelengths to penetrate such a medium, enables the study of its dynamics on the 100 fs time scale. The second one uses the harmonics beam as probe beam (λ equals 32 nm) within an interferometric device. This diagnostic was designed to ensure a micro-metric spatial resolution and a temporal resolution in the femtosecond range. The first results in presence of plasma created by irradiation of an aluminum target underline the potentialities of this new

  20. Particle identification system based on dense aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Barnyakov, A.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Barnyakov, M.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Beloborodov, K.I., E-mail: K.I.Beloborodov@inp.nsk.su [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Bobrovnikov, V.S.; Buzykaev, A.R. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Danilyuk, A.F. [Boreskov Institute of Catalysis, 5, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Golubev, V.B. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Gulevich, V.V. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Kononov, S.A.; Kravchenko, E.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Onuchin, A.P.; Martin, K.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Serednyakov, S.I. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); and others

    2013-12-21

    A threshold Cherenkov counter based on dense aerogel with refraction index n=1.13 is described. This counter is used for kaon identification at momenta below 1 GeV/c in the SND detector, which takes data at the VEPP-2000 e{sup +}e{sup −} collider. The results of measurements of the counter efficiency using electrons, muons, pions, and kaons produced in e{sup +}e{sup −} annihilation are presented.

  1. Leeuwpan fine coal dense medium plant

    CSIR Research Space (South Africa)

    Lundt, M

    2010-11-01

    Full Text Available Beneficiation 2010, 4–6 May 2010. 671The Journal of The Southern African Institute of Mining and Metallurgy VOLUME 110 NOVEMBER 2010 L Leeuwpan fine coal dense medium plant mixed with magnetite in the launder and enters... with production. Plant equipment operational changes Cyclone spigot changes In an attempt to lower the cut-point density, the spigot on the L 672 NOVEMBER 2010 VOLUME 110 The Journal of The Southern African Institute of Mining and Metallurgy Figure 1...

  2. Protein and Molecular Characterization of a Clinically Compliant Amniotic Fluid Stem Cell-Derived Extracellular Vesicle Fraction Capable of Accelerating Muscle Regeneration Through Enhancement of Angiogenesis.

    Science.gov (United States)

    Mellows, Ben; Mitchell, Robert; Antonioli, Manuela; Kretz, Oliver; Chambers, David; Zeuner, Marie-Theres; Denecke, Bernd; Musante, Luca; Ramachandra, Durrgah L; Debacq-Chainiaux, Florence; Holthofer, Harry; Joch, Barbara; Ray, Steve; Widera, Darius; David, Anna L; Huber, Tobias B; Dengjel, Joern; De Coppi, Paolo; Patel, Ketan

    2017-09-15

    The secretome of human amniotic fluid stem cells (AFSCs) has great potential as a therapeutic agent in regenerative medicine. However, it must be produced in a clinically compliant manner before it can be used in humans. In this study, we developed a means of producing a biologically active secretome from AFSCs that is free of all exogenous molecules. We demonstrate that the full secretome is capable of promoting stem cell proliferation, migration, and protection of cells against senescence. Furthermore, it has significant anti-inflammatory properties. Most importantly, we show that it promotes tissue regeneration in a model of muscle damage. We then demonstrate that the secretome contains extracellular vesicles (EVs) that harbor much, but not all, of the biological activity of the whole secretome. Proteomic characterization of the EV and free secretome fraction shows the presence of numerous molecules specific to each fraction that could be key regulators of tissue regeneration. Intriguingly, we show that the EVs only contain miRNA and not mRNA. This suggests that tissue regeneration in the host is mediated by the action of EVs modifying existing, rather than imposing new, signaling pathways. The EVs harbor significant anti-inflammatory activity as well as promote angiogenesis, the latter may be the mechanistic explanation for their ability to promote muscle regeneration after cardiotoxin injury.

  3. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; hide

    2017-01-01

    Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid

  4. Dynamics of molecular rotors confined in two dimensions: transition from a 2D rotational glass to a 2D rotational fluid in a periodic mesoporous organosilica.

    Science.gov (United States)

    Vogelsberg, Cortnie S; Bracco, Silvia; Beretta, Mario; Comotti, Angiolina; Sozzani, Piero; Garcia-Garibay, Miguel A

    2012-02-09

    The motional behavior of p-phenylene-d(4) rotators confined within the 2D layers of a hierarchically ordered periodic mesoporous p-divinylbenzenesilica has been elucidated to evaluate the effects of reduced dimensionality on the engineered dynamics of artificial molecular machines. The hybrid mesoporous material, characterized by a honeycomb lattice structure, has arrays of alternating p-divinylbenzene rotors and siloxane layers forming the molecularly ordered walls of the mesoscopic channels. The p-divinylbenzene rotors are strongly anchored between two adjacent siloxane sheets, so that the p-phenylene rotators are unable to experience translational diffusion and are allowed to rotate about only one fixed axis. Variable-temperature (2)H NMR experiments revealed that the p-phenylene rotators undergo an exchange process between sites related by 180° and a non-Arrhenius temperature dependence of the dynamics, with reorientational rates ranging from 10(3) to 10(8) Hz between 215 to 305 K. The regime of motion changes rapidly at about 280 K indicating the occurrence of a dynamical transition. The transition was also recognized by a steep change in the heat capacity at constant pressure. As a result of the robust lamellar architecture comprising the pore walls, the orientational dynamic disorder related to the phase transition is only realized in two dimensions within the layers, that is in the plane perpendicular to the channel axis. Thus, the aligned rotors that form the organic layers exhibit unique anisotropic dynamical properties as a result of the architecture's reduced dimensionality. The dynamical disorder restricted to two dimensions constitutes a highly mobile fluidlike rotational phase at room temperature, which upon cooling undergoes a transition to a more rigid glasslike phase. Activation energies of 5.9 and 9.5 kcal/mol respectively have been measured for the two dynamical regimes of rotation. Collectively, our investigation has led to the discovery of an

  5. Hybrid-Based Dense Stereo Matching

    Science.gov (United States)

    Chuang, T. Y.; Ting, H. W.; Jaw, J. J.

    2016-06-01

    Stereo matching generating accurate and dense disparity maps is an indispensable technique for 3D exploitation of imagery in the fields of Computer vision and Photogrammetry. Although numerous solutions and advances have been proposed in the literature, occlusions, disparity discontinuities, sparse texture, image distortion, and illumination changes still lead to problematic issues and await better treatment. In this paper, a hybrid-based method based on semi-global matching is presented to tackle the challenges on dense stereo matching. To ease the sensitiveness of SGM cost aggregation towards penalty parameters, a formal way to provide proper penalty estimates is proposed. To this end, the study manipulates a shape-adaptive cross-based matching with an edge constraint to generate an initial disparity map for penalty estimation. Image edges, indicating the potential locations of occlusions as well as disparity discontinuities, are approved by the edge drawing algorithm to ensure the local support regions not to cover significant disparity changes. Besides, an additional penalty parameter 𝑃𝑒 is imposed onto the energy function of SGM cost aggregation to specifically handle edge pixels. Furthermore, the final disparities of edge pixels are found by weighting both values derived from the SGM cost aggregation and the U-SURF matching, providing more reliable estimates at disparity discontinuity areas. Evaluations on Middlebury stereo benchmarks demonstrate satisfactory performance and reveal the potency of the hybrid-based dense stereo matching method.

  6. Fluid mechanics

    International Nuclear Information System (INIS)

    Granger, R.A.

    1985-01-01

    This text offers the most comprehensive approach available to fluid mechanics. The author takes great care to insure a physical understanding of concepts grounded in applied mathematics. The presentation of theory is followed by engineering applications, helping students develop problem-solving skills from the perspective of a professional engineer. Extensive use of detailed examples reinforces the understanding of theoretical concepts

  7. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    Energy Technology Data Exchange (ETDEWEB)

    Kepley, Amanda A.; Frayer, David [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944-0002 (United States); Leroy, Adam K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Usero, Antonio [Observatorio Astronómico Nacional, C/Alfonso XII, 3, E-28014 Madrid (Spain); Marvil, Josh [Department of Physics, New Mexico Tech., 801 Leroy Place, Socorro, NM 87801 (United States); Walter, Fabian, E-mail: akepley@nrao.edu [Max Planck Institute fur Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO{sup +}. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO{sup +} in the starburst galaxy M82. The HCN and HCO{sup +} in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO{sup +} emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction.

  8. Star Forming Dense Cloud Cores in the TeV -ray SNR RX J1713.7-3946

    Energy Technology Data Exchange (ETDEWEB)

    Sano, H.; Sato, J.; Yamamoto, H.; Hayakawa, T.; Torii, K.; Moribe, N.; Kawamura, A.; Okuda, T.; Mizuno, N.; Onishi, T.; Maezawa, H.; Inoue, T.; Inutsuka, S.; Tanaka, T.; Mizuno, A.; Ogawa, H.; Stutzki, J.; Bertoldi, F.; Anderl, S.; Bronfman, L.; Koo, B.C.

    2010-10-27

    RX J1713.7-3946 is one of the TeV {gamma}-ray supernova remnants (SNRs) emitting synchrotron X rays. The SNR is associated with molecular gas located at {approx}1 kpc. We made new molecular observations toward the dense cloud cores, peaks A, C and D, in the SNR in the {sup 12}CO(J=2-1) and {sup 13}CO(J=2-1) transitions at angular resolution of 90 degrees. The most intense core in {sup 13}CO, peak C, was also mapped in the {sup 12}CO(J=4-3) transition at angular resolution of 38 degrees. Peak C shows strong signs of active star formation including bipolar outflow and a far-infrared protostellar source and has a steep gradient with a r{sup -2.2 {+-} 0.4} variation in the average density within radius r. Peak C and the other dense cloud cores are rim-brightened in synchrotron X rays, suggesting that the dense cloud cores are embedded within or on the outer boundary of the SNR shell. This confirms the earlier suggestion that the X rays are physically associated with the molecular gas (Fukui et al. 2003). We present a scenario where the densest molecular core, peak C, survived against the blast wave and is now embedded within the SNR. Numerical simulations of the shock-cloud interaction indicate that a dense clump can indeed survive shock erosion, since shock propagation speed is stalled in the dense clump. Additionally, the shock-cloud interaction induces turbulence and magnetic field amplification around the dense clump that may facilitate particle acceleration in the lower-density inter-clump space leading to the enhanced synchrotron X rays around dense cores.

  9. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.; Loczi, Lajos; Jangabylova, Aliya; Kusmanov, Adil

    2016-01-01

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step

  10. About chiral models of dense matter and its magnetic properties

    International Nuclear Information System (INIS)

    Kutschera, M.

    1990-12-01

    The chiral models of dense nucleon matter are discussed. The quark matter with broken chiral symmetry is described. The magnetic properties of dense matter are presented and conclusions are given. 37 refs. (A.S.)

  11. Molecular simulation of fluids with non-identical intermolecular potentials: Thermodynamic properties of 10-5 + 12-6 Mie potential binary mixtures

    International Nuclear Information System (INIS)

    Stiegler, Thomas; Sadus, Richard J.

    2015-01-01

    General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form

  12. Poly(3,6-diamino-9-ethylcarbazole) based molecularly imprinted polymer sensor for ultra-sensitive and selective detection of 17-β-estradiol in biological fluids.

    Science.gov (United States)

    Liu, Weilu; Li, Haifeng; Yu, Shangmin; Zhang, Jiaxing; Zheng, Weihua; Niu, Liting; Li, Gengen

    2018-05-01

    In this work, we reported the synthesis of 3, 6-diamino-9-ethylcarbazole and its application as a new monomer for preparation of molecularly imprinted polymer (MIP) electrochemical sensor. The as prepared MIP sensor exhibited ultrahigh sensitivity and selectivity for the detection of 17-β-estradiol in attomolar levels (1 × 10 -18 molL -1 ). The sensor works by detecting the change of the interfacial impedance that is derived from recognition of 17-β-estradiol on the MIP layer. The MIP sensor based on 3, 6-diamino-9-ethylcarbazole monomer revealed better performance than that of unmodified carbazole monomer. The monomer/template ratio, electropolymerization scanning cycles, and the incubation pH values were optimised in order to obtain the best detection efficiency. Under the optimised condition, the MIP sensor exhibits a wide linear range from 1aM to 10μM (1 × 10 -18 ̶ 1 × 10 -5 molL -1 ). A low detection limit of 0.36aM (3.6 × 10 -19 molL -1 ) and a good selectivity towards structurally similar compounds were obtained. The proposed MIP sensor also exhibits long-term stability and applicability in human serum samples. These advantages enabled this MIP sensor to be a promising alternative of electrochemical sensor and may be extended to detection of other endogenous compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Fluid dynamics of dilatant fluid

    DEFF Research Database (Denmark)

    Nakanishi, Hiizu; Nagahiro, Shin-ichiro; Mitarai, Namiko

    2012-01-01

    of the state variable, we demonstrate that the model can describe basic features of the dilatant fluid such as the stress-shear rate curve that represents discontinuous severe shear thickening, hysteresis upon changing shear rate, and instantaneous hardening upon external impact. An analysis of the model...

  14. Fluid Instabilities of Magnetar-Powered Supernovae

    Science.gov (United States)

    Chen, Ke-Jung

    2017-05-01

    Magnetar-powered supernova explosions are competitive models for explaining very luminous optical transits. Until recently, these explosion models were mainly calculated in 1D. Radiation emitted from the magnetar snowplows into the previous supernovae ejecta and causes a nonphysical dense shell (spike) found in previous 1D studies. This suggests that strong fluid instabilities may have developed within the magnetar-powered supernovae. Such fluid instabilities emerge at the region where luminous transits later occur, so they can affect the consequent observational signatures. We examine the magnetar-powered supernovae with 2D hydrodynamics simulations and find that the 1D dense shell transforms into the development of Rayleigh-Taylor and thin shell instabilities in 2D. The resulting mixing is able to fragment the entire shell and break the spherical symmetry of supernovae ejecta.

  15. Transport Coefficients of Fluids

    CERN Document Server

    Eu, Byung Chan

    2006-01-01

    Until recently the formal statistical mechanical approach offered no practicable method for computing the transport coefficients of liquids, and so most practitioners had to resort to empirical fitting formulas. This has now changed, as demonstrated in this innovative monograph. The author presents and applies new methods based on statistical mechanics for calculating the transport coefficients of simple and complex liquids over wide ranges of density and temperature. These molecular theories enable the transport coefficients to be calculated in terms of equilibrium thermodynamic properties, and the results are shown to account satisfactorily for experimental observations, including even the non-Newtonian behavior of fluids far from equilibrium.

  16. Fluid dynamics

    CERN Document Server

    Ruban, Anatoly I

    This is the first book in a four-part series designed to give a comprehensive and coherent description of Fluid Dynamics, starting with chapters on classical theory suitable for an introductory undergraduate lecture course, and then progressing through more advanced material up to the level of modern research in the field. The present Part 1 consists of four chapters. Chapter 1 begins with a discussion of Continuum Hypothesis, which is followed by an introduction to macroscopic functions, the velocity vector, pressure, density, and enthalpy. We then analyse the forces acting inside a fluid, and deduce the Navier-Stokes equations for incompressible and compressible fluids in Cartesian and curvilinear coordinates. In Chapter 2 we study the properties of a number of flows that are presented by the so-called exact solutions of the Navier-Stokes equations, including the Couette flow between two parallel plates, Hagen-Poiseuille flow through a pipe, and Karman flow above an infinite rotating disk. Chapter 3 is d...

  17. Molecularly imprinted polymer for the selective extraction of cocaine and its metabolites, benzoylecgonine and ecgonine methyl ester, from biological fluids before LC-MS analysis.

    Science.gov (United States)

    Thibert, Valérie; Legeay, Patrice; Chapuis-Hugon, Florence; Pichon, Valérie

    2014-02-15

    Considering the important complexity of biological samples, a molecularly imprinted polymer (MIP) was applied to the selective extraction of cocaine and its two main metabolites, benzoylecgonine and ecgonine methyl ester from biological samples. The MIP was imprinted with cocaine and it was synthesized in acetonitrile with methacrylic acid as a functional monomer and ethylene glycol dimethacrylate as a crosslinker. The selectivity of the MIP was first assessed for the three target analytes in acetonitrile with recoveries higher than 80% on the MIP and lower than 30% on the non-imprinted polymer (NIP). The MIP was then evaluated for the selective extraction of these targets from real aqueous media, i.e. serum and urine samples. The pH adjustment of the sample as well as the optimization of the washing step led to a very selective extraction of cocaine from these media. A LOQ of 0.5ng/mL was obtained for cocaine in urine. Concerning cocaine metabolites, benzoylecgonine and ecgonine methyl ester, they were first extracted from urine by liquid-liquid extraction and the resulting extract was purified on the MIP. The results obtained with the MIP as compared to the LLE alone showed the great potential of the MIP extraction for the clean-up of the biological matrix. This procedure was tested for the extraction of the analytes from urine samples, leading to a very selective protocol with LOQs of 0.09ng/mL, 0.4ng/mL and 1.1ng/mL for cocaine, benzolecgonine and ecgonine methyl ester respectively in urine samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Evolution of dense spatially modulated electron bunches

    Science.gov (United States)

    Balal, N.; Bratman, V. L.; Friedman, A.

    2018-03-01

    An analytical theory describing the dynamics of relativistic moving 1D electron pulses (layers) with the density modulation affected by a space charge has been revised and generalized for its application to the formation of dense picosecond bunches from linear accelerators with laser-driven photo injectors, and its good agreement with General Particle Tracer simulations has been demonstrated. Evolution of quasi-one-dimensional bunches (disks), for which the derived formulas predict longitudinal expansion, is compared with that for thin and long electron cylinders (threads), for which the excitation of non-linear waves with density spikes was found earlier by Musumeci et al. [Phys. Rev. Lett. 106(18), 184801 (2011)] and Musumeci et al. [Phys. Rev. Spec. Top. -Accel. Beams 16(10), 100701 (2013)]. Both types of bunches can be used for efficiency enhancement of THz sources based on the Doppler frequency up-shifted coherent spontaneous radiation of electrons. Despite the strong Coulomb repulsion, the periodicity of a preliminary modulation in dense 1D layers persists during their expansion in the most interesting case of a relatively small change in particle energy. However, the period of modulation increases and its amplitude decreases in time. In the case of a large change in electron energy, the uniformity of periodicity is broken due to different relativistic changes in longitudinal scales along the bunch: the "period" of modulation decreases and its amplitude increases from the rear to the front boundary. Nevertheless, the use of relatively long electron bunches with a proper preliminary spatial modulation of density can provide a significantly higher power and a narrower spectrum of coherent spontaneous radiation of dense bunches than in the case of initially short single bunches with the same charge.

  19. Damping of Resonantly Forced Density Waves in Dense Planetary Rings

    Science.gov (United States)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2016-10-01

    We address the stability of resonantly forced density waves in dense planetary rings.Already by Goldreich and Tremaine (1978) it has been argued that density waves might be unstable, depending on the relationship between the ring's viscosity and the surface mass density. In the recent paper (Schmidt et al. 2016) we have pointed out that when - within a fluid description of the ring dynamics - the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping.We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model.This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts linear instability of density waves in a ring region where the conditions for viscous overstability are met. In this case, sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. In general the model wave damping lengths depend on a set of input parameters, such as the distance to the threshold for viscous overstability and the ground state surface mass density.Our new model compares reasonably well with the streamline model for nonlinear density waves of Borderies et al. 1986.Deviations become substantial in the highly nonlinear regime, corresponding to strong satellite forcing.Nevertheless, we generally observe good or at least qualitative agreement between the wave amplitude profiles of both models. The streamline approach is superior at matching the total wave profile of waves observed in Saturn's rings, while our new damping relation is a comparably handy tool to gain insight in the evolution of the wave amplitude with distance from resonance, and the different regimes of

  20. Nonlinear quantum fluid equations for a finite temperature Fermi plasma

    International Nuclear Information System (INIS)

    Eliasson, Bengt; Shukla, Padma K

    2008-01-01

    Nonlinear quantum electron fluid equations are derived, taking into account the moments of the Wigner equation and by using the Fermi-Dirac equilibrium distribution for electrons with an arbitrary temperature. A simplified formalism with the assumptions of incompressibility of the distribution function is used to close the moments in velocity space. The nonlinear quantum diffraction effects into the fluid equations are incorporated. In the high-temperature limit, we retain the nonlinear fluid equations for a dense hot plasma and in the low-temperature limit, we retain the correct fluid equations for a fully degenerate plasma

  1. Electron conductivity model for dense plasmas

    International Nuclear Information System (INIS)

    Lee, Y.T.; More, R.M.

    1984-01-01

    An electron conductivity model for dense plasmas is described which gives a consistent and complete set of transport coefficients including not only electrical conductivity and thermal conductivity, but also thermoelectric power, and Hall, Nernst, Ettinghausen, and Leduc--Righi coefficients. The model is useful for simulating plasma experiments with strong magnetic fields. The coefficients apply over a wide range of plasma temperature and density and are expressed in a computationally simple form. Different formulas are used for the electron relaxation time in plasma, liquid, and solid phases. Comparisons with recent calculations and available experimental measurement show the model gives results which are sufficiently accurate for many practical applications

  2. Dense ceramic membranes for methane conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bouwmeester, Henny J.M. [Laboratory for Inorganic Materials Science, Department of Science and Technology and MESA Research Institute, University of Twente, 7500 AE Enschede (Netherlands)

    2003-07-30

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor, this technology is expected to significantly reduce the capital costs of conversion of natural gas to liquid added-value products. The present survey is mainly concerned with the material properties that govern the performance of the mixed-conducting membranes in real operating conditions and highlights significant developments in the field.

  3. The Magpie dense z-pinch project

    International Nuclear Information System (INIS)

    Chittenden, J.; Choi, P.; Mitchell, I.; Dangor, A.E.; Haines, M.G.

    1990-01-01

    The authors present a design study on the Mega Ampere Generator for Plasma Implosion Experiments (MAGPIE), a project currently under construction at Imperial College London, to study radiative collapse of a dense Z-pinch plasma created from a 20 um diameter cryogenic hydrogen fiber. The 2 TW generator is composed of four individual 2.4 MV Marx banks of the HERMES III type design with a maximum stored energy of 336 kJ. They drive four 5 ohm Pulse Forming Lines which are combined into a single 1.25 MA in 150 ns to a 150 nH load

  4. Strange mesons in dense nuclear matter

    International Nuclear Information System (INIS)

    Senger, P.

    2000-10-01

    Experimental data on the production of kaons and antikaons in heavy ion collisions at relativistic energies are reviewed with respect to in-medium effects. The K - /K + ratios measured in nucleus-nucleus collisions are 1-2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of K + mesons indicate a repulsive kaon-nucleon potential. Microscopic transport calculations consistently explain both the yields and the emission patterns of kaons and antikaons when assuming that their properties are modified in dense nuclear matter. The K + production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state. (orig.)

  5. Structure of a new dense amorphous ice

    International Nuclear Information System (INIS)

    Finney, J.L.; Bowron, D.T.; Soper, A.K.; Loerting, T.; Mayer, E.; Hallbrucker, A.

    2002-01-01

    The detailed structure of a new dense amorphous ice, VHDA, is determined by isotope substitution neutron diffraction. Its structure is characterized by a doubled occupancy of the stabilizing interstitial location that was found in high density amorphous ice, HDA. As would be expected for a thermally activated unlocking of the stabilizing 'interstitial', the transition from VHDA to LDA (low-density amorphous ice) is very sharp. Although its higher density makes VHDA a better candidate than HDA for a physical manifestation of the second putative liquid phase of water, as for the HDA case, the VHDA to LDA transition also appears to be kinetically controlled

  6. Fabrication of dense panels in lithium fluoride

    International Nuclear Information System (INIS)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-01

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated

  7. Graph Quasicontinuous Functions and Densely Continuous Forms

    Directory of Open Access Journals (Sweden)

    Lubica Hola

    2017-07-01

    Full Text Available Let $X, Y$ be topological spaces. A function $f: X \\to Y$ is said to be graph quasicontinuous if there is a quasicontinuous function $g: X \\to Y$ with the graph of $g$ contained in the closure of the graph of $f$. There is a close relation between the notions of graph quasicontinuous functions and minimal usco maps as well as the notions of graph quasicontinuous functions and densely continuous forms. Every function with values in a compact Hausdorff space is graph quasicontinuous; more generally every locally compact function is graph quasicontinuous.

  8. Consequences of the Solar System passage through dense interstellar clouds

    Directory of Open Access Journals (Sweden)

    A. G. Yeghikyan

    2003-06-01

    Full Text Available Several consequences of the passage of the solar system through dense interstellar molecular clouds are discussed. These clouds, dense (more than 100 cm-3, cold (10–50 K and extended (larger than 1 pc, are characterized by a gas-to-dust mass ratio of about 100, by a specific power grain size spectrum (grain radii usually cover the range 0.001–3 micron and by an average dust-to-gas number density ratio of about 10-12. Frequently these clouds contain small-scale (10–100 AU condensations with gas concentrations ranging up to 10 5 cm-3. At their casual passage over the solar system they exert pressures very much enhanced with respect to today’s standards. Under these conditions it will occur that the Earth is exposed directly to the interstellar flow. It is shown first that even close to the Sun, at 1 AU, the cloud’s matter is only partly ionized and should mainly interact with the solar wind by charge exchange processes. Dust particles of the cloud serve as a source of neutrals, generated by the solar UV irradiation of dust grains, causing the evaporation of icy materials. The release of neutral atoms from dust grains is then followed by strong influences on the solar wind plasma flow. The behavior of the neutral gas inflow parameters is investigated by a 2-D hydrodynamic approach to model the interaction processes. Because of a reduction of the heliospheric dimension down to 1 AU, direct influence of the cloud’s matter to the terrestrial environment and atmosphere could be envisaged.Key words. Interplanetary physics (heliopause and solar wind termination; interplanetary dust; interstellar gas

  9. Consequences of the Solar System passage through dense interstellar clouds

    Directory of Open Access Journals (Sweden)

    A. G. Yeghikyan

    Full Text Available Several consequences of the passage of the solar system through dense interstellar molecular clouds are discussed. These clouds, dense (more than 100 cm-3, cold (10–50 K and extended (larger than 1 pc, are characterized by a gas-to-dust mass ratio of about 100, by a specific power grain size spectrum (grain radii usually cover the range 0.001–3 micron and by an average dust-to-gas number density ratio of about 10-12. Frequently these clouds contain small-scale (10–100 AU condensations with gas concentrations ranging up to 10 5 cm-3. At their casual passage over the solar system they exert pressures very much enhanced with respect to today’s standards. Under these conditions it will occur that the Earth is exposed directly to the interstellar flow. It is shown first that even close to the Sun, at 1 AU, the cloud’s matter is only partly ionized and should mainly interact with the solar wind by charge exchange processes. Dust particles of the cloud serve as a source of neutrals, generated by the solar UV irradiation of dust grains, causing the evaporation of icy materials. The release of neutral atoms from dust grains is then followed by strong influences on the solar wind plasma flow. The behavior of the neutral gas inflow parameters is investigated by a 2-D hydrodynamic approach to model the interaction processes. Because of a reduction of the heliospheric dimension down to 1 AU, direct influence of the cloud’s matter to the terrestrial environment and atmosphere could be envisaged.

    Key words. Interplanetary physics (heliopause and solar wind termination; interplanetary dust; interstellar gas

  10. Mesoscopic model for binary fluids

    Science.gov (United States)

    Echeverria, C.; Tucci, K.; Alvarez-Llamoza, O.; Orozco-Guillén, E. E.; Morales, M.; Cosenza, M. G.

    2017-10-01

    We propose a model for studying binary fluids based on the mesoscopic molecular simulation technique known as multiparticle collision, where the space and state variables are continuous, and time is discrete. We include a repulsion rule to simulate segregation processes that does not require calculation of the interaction forces between particles, so binary fluids can be described on a mesoscopic scale. The model is conceptually simple and computationally efficient; it maintains Galilean invariance and conserves the mass and energy in the system at the micro- and macro-scale, whereas momentum is conserved globally. For a wide range of temperatures and densities, the model yields results in good agreement with the known properties of binary fluids, such as the density profile, interface width, phase separation, and phase growth. We also apply the model to the study of binary fluids in crowded environments with consistent results.

  11. Local order and crystallization of dense polydisperse hard spheres

    Science.gov (United States)

    Coslovich, Daniele; Ozawa, Misaki; Berthier, Ludovic

    2018-04-01

    Computer simulations give precious insight into the microscopic behavior of supercooled liquids and glasses, but their typical time scales are orders of magnitude shorter than the experimentally relevant ones. We recently closed this gap for a class of models of size polydisperse fluids, which we successfully equilibrate beyond laboratory time scales by means of the swap Monte Carlo algorithm. In this contribution, we study the interplay between compositional and geometric local orders in a model of polydisperse hard spheres equilibrated with this algorithm. Local compositional order has a weak state dependence, while local geometric order associated to icosahedral arrangements grows more markedly but only at very high density. We quantify the correlation lengths and the degree of sphericity associated to icosahedral structures and compare these results to those for the Wahnström Lennard-Jones mixture. Finally, we analyze the structure of very dense samples that partially crystallized following a pattern incompatible with conventional fractionation scenarios. The crystal structure has the symmetry of aluminum diboride and involves a subset of small and large particles with size ratio approximately equal to 0.5.

  12. Monte Carlo simulations of ionization potential depression in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stransky, M., E-mail: stransky@fzu.cz [Department of Radiation and Chemical Physics, Institute of Physics ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2016-01-15

    A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model.

  13. Monte Carlo simulations of ionization potential depression in dense plasmas

    International Nuclear Information System (INIS)

    Stransky, M.

    2016-01-01

    A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model

  14. Neutrino interactions in hot and dense matter

    International Nuclear Information System (INIS)

    Reddy, S.; Prakash, M.; Lattimer, J.M.

    1998-01-01

    We study the charged and neutral current weak interaction rates relevant for the determination of neutrino opacities in dense matter found in supernovae and neutron stars. We establish an efficient formalism for calculating differential cross sections and mean free paths for interacting, asymmetric nuclear matter at arbitrary degeneracy. The formalism is valid for both charged and neutral current reactions. Strong interaction corrections are incorporated through the in-medium single particle energies at the relevant density and temperature. The effects of strong interactions on the weak interaction rates are investigated using both potential and effective field-theoretical models of matter. We investigate the relative importance of charged and neutral currents for different astrophysical situations, and also examine the influence of strangeness-bearing hyperons. Our findings show that the mean free paths are significantly altered by the effects of strong interactions and the multi-component nature of dense matter. The opacities are then discussed in the context of the evolution of the core of a protoneutron star. copyright 1998 The American Physical Society

  15. Cold dense baryonic matter and compact stars

    International Nuclear Information System (INIS)

    Hyun Kyu Lee; Sang-Jin Sin; Mannque Rho

    2011-01-01

    Probing dense hadronic matter is thus far an uncharted field of physics. Here we give a brief summary of the highlights of what has been so far accomplished and what will be done in the years ahead by the World Class University III Project at Hanyang University in the endeavor to unravel and elucidate the multi-facet of the cold dense baryonic matter existing in the interior of the densest visible stable object in the universe, i.e. neutron stars, strangeness stars and/or quark stars, from a modest and simplified starting point of an effective field theory modeled on the premise of QCD as well as from a gravity dual approach of hQCD. The core of the matter of our research is the possible origin of the ∼ 99% of the proton mass that is to be accounted for and how the 'vacuum' can be tweaked so that the source of the mass generation can be uncovered by measurements made in terrestrial as well as space laboratories. Some of the issues treated in the program concern what can be done - both theoretically and experimentally - in anticipation of what's to come for basic physics research in Korea. (authors)

  16. Collective dynamics in dense Hg vapour

    International Nuclear Information System (INIS)

    Ishikawa, D; Inui, M; Matsuda, K; Tamura, K; Baron, A Q R; Tsutsui, S; Tanaka, Y; Ishikawa, T

    2004-01-01

    The dynamic structure factor, S(Q,ο), of dense Hg vapour has been measured by high resolution inelastic x-ray scattering for densities of 3.0, 2.1 and 1.0 g cm -3 corresponding to 0.52, 0.36 and 0.17 times the critical density, respectively, and for momentum transfers between 2.0 and 48 nm -1 . Analysis of the longitudinal current-current correlation function in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The ratios of the frequencies were found to be 1.27 at 3.0 g cm -3 , 1.12 at 2.1 g cm -3 and 1.10 at 1.0 g cm -3 . The sound velocity obtained from the present experiments is well reproduced by a wavenumber dependent adiabatic sound velocity, which means that the collective modes remain in the spectra of dense Hg vapour. (letter to the editor)

  17. Redesigning Triangular Dense Matrix Computations on GPUs

    KAUST Repository

    Charara, Ali

    2016-08-09

    A new implementation of the triangular matrix-matrix multiplication (TRMM) and the triangular solve (TRSM) kernels are described on GPU hardware accelerators. Although part of the Level 3 BLAS family, these highly computationally intensive kernels fail to achieve the percentage of the theoretical peak performance on GPUs that one would expect when running kernels with similar surface-to-volume ratio on hardware accelerators, i.e., the standard matrix-matrix multiplication (GEMM). The authors propose adopting a recursive formulation, which enriches the TRMM and TRSM inner structures with GEMM calls and, therefore, reduces memory traffic while increasing the level of concurrency. The new implementation enables efficient use of the GPU memory hierarchy and mitigates the latency overhead, to run at the speed of the higher cache levels. Performance comparisons show up to eightfold and twofold speedups for large dense matrix sizes, against the existing state-of-the-art TRMM and TRSM implementations from NVIDIA cuBLAS, respectively, across various GPU generations. Once integrated into high-level Cholesky-based dense linear algebra algorithms, the performance impact on the overall applications demonstrates up to fourfold and twofold speedups, against the equivalent native implementations, linked with cuBLAS TRMM and TRSM kernels, respectively. The new TRMM/TRSM kernel implementations are part of the open-source KBLAS software library (http://ecrc.kaust.edu.sa/Pages/Res-kblas.aspx) and are lined up for integration into the NVIDIA cuBLAS library in the upcoming v8.0 release.

  18. Asymmetric continuum extreme processes in solids and fluids

    CERN Document Server

    Teisseyre, Roman

    2014-01-01

    This book deals with a class of basic deformations in asymmetric continuum theory. It describes molecular deformations and transport velocities in fluids, strain deformations in solids as well as the molecular transport, important in fracture processes.

  19. Coulomb interactions in charged fluids.

    Science.gov (United States)

    Vernizzi, Graziano; Guerrero-García, Guillermo Iván; de la Cruz, Monica Olvera

    2011-07-01

    The use of Ewald summation schemes for calculating long-range Coulomb interactions, originally applied to ionic crystalline solids, is a very common practice in molecular simulations of charged fluids at present. Such a choice imposes an artificial periodicity which is generally absent in the liquid state. In this paper we propose a simple analytical O(N(2)) method which is based on Gauss's law for computing exactly the Coulomb interaction between charged particles in a simulation box, when it is averaged over all possible orientations of a surrounding infinite lattice. This method mitigates the periodicity typical of crystalline systems and it is suitable for numerical studies of ionic liquids, charged molecular fluids, and colloidal systems with Monte Carlo and molecular dynamics simulations.

  20. THE JCMT GOULD BELT SURVEY: A FIRST LOOK AT DENSE CORES IN ORION B

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, H.; Francesco, J. Di; Johnstone, D. [NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Rd, Victoria, BC, V9E 2E7 (Canada); Duarte-Cabral, A.; Hatchell, J. [Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Sadavoy, S.; Mottram, J. C. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Buckle, J.; Salji, C. [Astrophysics Group, Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE (United Kingdom); Berry, D. S.; Currie, M. J.; Jenness, T. [Joint Astronomy Centre, 660 N. A‘ohōkū Place, University Park, Hilo, Hawaii 96720 (United States); Broekhoven-Fiene, H. [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada); Fich, M.; Tisi, S. [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Nutter, D.; Quinn, C. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA (United Kingdom); Pattle, K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE (United Kingdom); Pineda, J. E. [European Southern Observatory (ESO), Garching (Germany); Hogerheijde, M. R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); and others

    2016-02-01

    We present a first look at the SCUBA-2 observations of three sub-regions of the Orion B molecular cloud: LDN 1622, NGC 2023/2024, and NGC 2068/2071, from the JCMT Gould Belt Legacy Survey. We identify 29, 564, and 322 dense cores in L1622, NGC 2023/2024, and NGC 2068/2071 respectively, using the SCUBA-2 850 μm map, and present their basic properties, including their peak fluxes, total fluxes, and sizes, and an estimate of the corresponding 450 μm peak fluxes and total fluxes, using the FellWalker source extraction algorithm. Assuming a constant temperature of 20 K, the starless dense cores have a mass function similar to that found in previous dense core analyses, with a Salpeter-like slope at the high-mass end. The majority of cores appear stable to gravitational collapse when considering only thermal pressure; indeed, most of the cores which have masses above the thermal Jeans mass are already associated with at least one protostar. At higher cloud column densities, above 1–2 × 10{sup 23} cm{sup −2}, most of the mass is found within dense cores, while at lower cloud column densities, below 1 × 10{sup 23} cm{sup −2}, this fraction drops to 10% or lower. Overall, the fraction of dense cores associated with a protostar is quite small (<8%), but becomes larger for the densest and most centrally concentrated cores. NGC 2023/2024 and NGC 2068/2071 appear to be on the path to forming a significant number of stars in the future, while L1622 has little additional mass in dense cores to form many new stars.

  1. THE JCMT GOULD BELT SURVEY: A FIRST LOOK AT DENSE CORES IN ORION B

    International Nuclear Information System (INIS)

    Kirk, H.; Francesco, J. Di; Johnstone, D.; Duarte-Cabral, A.; Hatchell, J.; Sadavoy, S.; Mottram, J. C.; Buckle, J.; Salji, C.; Berry, D. S.; Currie, M. J.; Jenness, T.; Broekhoven-Fiene, H.; Fich, M.; Tisi, S.; Nutter, D.; Quinn, C.; Pattle, K.; Pineda, J. E.; Hogerheijde, M. R.

    2016-01-01

    We present a first look at the SCUBA-2 observations of three sub-regions of the Orion B molecular cloud: LDN 1622, NGC 2023/2024, and NGC 2068/2071, from the JCMT Gould Belt Legacy Survey. We identify 29, 564, and 322 dense cores in L1622, NGC 2023/2024, and NGC 2068/2071 respectively, using the SCUBA-2 850 μm map, and present their basic properties, including their peak fluxes, total fluxes, and sizes, and an estimate of the corresponding 450 μm peak fluxes and total fluxes, using the FellWalker source extraction algorithm. Assuming a constant temperature of 20 K, the starless dense cores have a mass function similar to that found in previous dense core analyses, with a Salpeter-like slope at the high-mass end. The majority of cores appear stable to gravitational collapse when considering only thermal pressure; indeed, most of the cores which have masses above the thermal Jeans mass are already associated with at least one protostar. At higher cloud column densities, above 1–2 × 10 23 cm −2 , most of the mass is found within dense cores, while at lower cloud column densities, below 1 × 10 23 cm −2 , this fraction drops to 10% or lower. Overall, the fraction of dense cores associated with a protostar is quite small (<8%), but becomes larger for the densest and most centrally concentrated cores. NGC 2023/2024 and NGC 2068/2071 appear to be on the path to forming a significant number of stars in the future, while L1622 has little additional mass in dense cores to form many new stars

  2. Fluid mechanics

    International Nuclear Information System (INIS)

    Paraschivoiu, I.; Prud'homme, M.; Robillard, L.; Vasseur, P.

    2003-01-01

    This book constitutes at the same time theoretical and practical base relating to the phenomena associated with fluid mechanics. The concept of continuum is at the base of the approach developed in this work. The general advance proceeds of simple balances of forces as into hydrostatic to more complex situations or inertias, the internal stresses and the constraints of Reynolds are taken into account. This advance is not only theoretical but contains many applications in the form of solved problems, each chapter ending in a series of suggested problems. The major part of the applications relates to the incompressible flows

  3. Lattice Boltzmann Simulation of Permeability and Tortuosity for Flow through Dense Porous Media

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2014-01-01

    Full Text Available Discrete element method (DEM is used to produce dense and fixed porous media with rigid mono spheres. Lattice Boltzmann method (LBM is adopted to simulate the fluid flow in interval of dense spheres. To simulating the same physical problem, the permeability is obtained with different lattice number. We verify that the permeability is irrelevant to the body force and the media length along flow direction. The relationships between permeability, tortuosity and porosity, and sphere radius are researched, and the results are compared with those reported by other authors. The obtained results indicate that LBM is suited to fluid flow simulation of porous media due to its inherent theoretical advantages. The radius of sphere should have ten lattices at least and the media length along flow direction should be more than twenty radii. The force has no effect on the coefficient of permeability with the limitation of slow fluid flow. For mono spheres porous media sample, the relationship of permeability and porosity agrees well with the K-C equation, and the tortuosity decreases linearly with increasing porosity.

  4. Principles of fluid mechanics

    International Nuclear Information System (INIS)

    Kreider, J.F.

    1985-01-01

    This book is an introduction on fluid mechanics incorporating computer applications. Topics covered are as follows: brief history; what is a fluid; two classes of fluids: liquids and gases; the continuum model of a fluid; methods of analyzing fluid flows; important characteristics of fluids; fundamentals and equations of motion; fluid statics; dimensional analysis and the similarity principle; laminar internal flows; ideal flow; external laminar and channel flows; turbulent flow; compressible flow; fluid flow measurements

  5. Disappearing fluid?

    International Nuclear Information System (INIS)

    Graney, K.; Chu, J.; Lin, P.C.

    2002-01-01

    Full text: A 78-year old male in end stage renal failure (ESRF) with a background of NIDDM retinopathy, nephropathy, and undergoing continuous ambulatory peritoneal dialysis (CAPD) presented with anorexia, clinically unwell, decreased mobility and right scrotal swelling. There was no difficulty during CAPD exchange except there was a positive fluid balance Peritoneal dialysates remained clear A CAPD peritoneal study was requested. 100Mbq 99mTc Sulphur Colloid was injected into a standard dialysate bag containing dialysate. Anterior dynamic images were acquired over the abdomen pelvis while the dialysate was infused Static images with anatomical markers were performed 20 mins post infusion, before and after patient ambulation and then after drainage. The study demonstrated communication between the peritoneal cavity and the right scrotal sac. Patient underwent right inguinal herniaplasty with a marlex mesh. A repeat CAPD flow study was performed as follow up and no abnormal connection between the peritoneal cavity and the right scrotal sac was demonstrated post operatively. This case study shows that CAPD flow studies can be undertaken as a simple, minimally invasive method to evaluate abnormal peritoneal fluid flow dynamics in patients undergoing CAPD, and have an impact on dialysis management. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  6. Auxillary Fluid Flowmeter

    DEFF Research Database (Denmark)

    RezaNejad Gatabi, Javad; Forouzbakhsh, Farshid; Ebrahimi Darkhaneh, Hadi

    2010-01-01

    The Auxiliary Fluid Flow meter is proposed to measure the fluid flow of any kind in both pipes and open channels. In this kind of flow measurement, the flow of an auxiliary fluid is measured Instead of direct measurement of the main fluid flow. The auxiliary fluid is injected into the main fluid ...

  7. ALMA FOLLOWS STREAMING OF DENSE GAS DOWN TO 40 pc FROM THE SUPERMASSIVE BLACK HOLE IN NGC 1097

    International Nuclear Information System (INIS)

    Fathi, Kambiz; Piñol-Ferrer, Nuria; Lundgren, Andreas A.; Wiklind, Tommy; Kohno, Kotaro; Izumi, Takuma; Martín, Sergio; Espada, Daniel; Hatziminaoglou, Evanthia; Imanishi, Masatoshi; Krips, Melanie; Matsushita, Satoki; Meier, David S.; Nakai, Naomasa; Sheth, Kartik; Turner, Jean; Van de Ven, Glenn

    2013-01-01

    We present a kinematic analysis of the dense molecular gas in the central 200 pc of the nearby galaxy NGC 1097, based on Cycle 0 observations with the Atacama Large Millimeter/submillimeter Array (ALMA). We use the HCN(4-3) line to trace the densest interstellar molecular gas (n H 2 ∼10 8 cm –3 ), and quantify its kinematics, and estimate an inflow rate for the molecular gas. We find a striking similarity between the ALMA kinematic data and the analytic spiral inflow model that we have previously constructed based on ionized gas velocity fields on larger scales. We are able to follow dense gas streaming down to 40 pc distance from the supermassive black hole in this Seyfert 1 galaxy. In order to fulfill marginal stability, we deduce that the dense gas is confined to a very thin disk, and we derive a dense gas inflow rate of 0.09 M ☉ yr –1 at 40 pc radius. Combined with previous values from the Hα and CO gas, we calculate a combined molecular and ionized gas inflow rate of ∼0.2 M ☉ yr –1 at 40 pc distance from the central supermassive black hole of NGC 1097.

  8. Dense CO2 as a Solute, Co-Solute or Co-Solvent in Particle Formation Processes: A Review

    Directory of Open Access Journals (Sweden)

    Ana V. M. Nunes

    2011-11-01

    Full Text Available The application of dense gases in particle formation processes has attracted great attention due to documented advantages over conventional technologies. In particular, the use of dense CO2 in the process has been subject of many works and explored in a variety of different techniques. This article presents a review of the current available techniques in use in particle formation processes, focusing exclusively on those employing dense CO2 as a solute, co-solute or co-solvent during the process, such as PGSS (Particles from gas-saturated solutions®, CPF (Concentrated Powder Form®, CPCSP (Continuous Powder Coating Spraying Process, CAN-BD (Carbon dioxide Assisted Nebulization with a Bubble Dryer®, SEA (Supercritical Enhanced Atomization, SAA (Supercritical Fluid-Assisted Atomization, PGSS-Drying and DELOS (Depressurization of an Expanded Liquid Organic Solution. Special emphasis is given to modifications introduced in the different techniques, as well as the limitations that have been overcome.

  9. Glaciations and dense interstellar clouds; and reply

    Energy Technology Data Exchange (ETDEWEB)

    McCrea, W H [Sussex Univ., Brighton (UK); Dennison, B; Mansfield, V N

    1976-09-16

    Reference is made to Dennison and Mansfield (Nature 261:32 (1976)) who offered comments on a previous paper by the author (Nature 255:607 (1975)), in which he suggested that a possible cause of an ice age on the Earth was the passage of the solar system through an interstellar matter compression region bordering a spiral arm of the Galaxy. Dennison and Mansfield criticised this suggestion because it led them to expect to find a dense cloud of interstellar matter still very close to the Earth, whereas no such cloud is known. It is stated here that this criticism ignores the structure of the Galaxy, that provided the basis of the suggestion. A reply by Dennison and Mansfield is appended.

  10. Charmonium propagation through a dense medium

    Directory of Open Access Journals (Sweden)

    Kopeliovich B.Z.

    2015-01-01

    Full Text Available Attenuation of a colourless c̄c dipole propagating with a large momentum through a hot medium originates from two sources, Debye screening (melting, and inelastic collisions with surrounding scattering centres (absorption. The former never terminates completely production of a bound charmonium in heavy ion collisions, even at very high temperatures. The latter, is controlled my the magnitude of the dipole cross section, related to the transport coefficient, which is the rate of transverse momentum broadening in the medium. A novel procedure of Lorentz boosting of the Schrödinger equation is developed, which allows to calculate the charmonium survival probability employing the path-integral technique, incorporating both melting and absorption. A novel mechanism of charmonium regeneration in a dense medium is proposed.

  11. Frontiers and challenges in warm dense matter

    CERN Document Server

    Desjarlais, Michael; Redmer, Ronald; Trickey, Samuel

    2014-01-01

    Warm Dense Matter (WDM) occupies a loosely defined region of phase space intermediate between solid, liquid, gas, and plasma, and typically shares characteristics of two or more of these phases. WDM is generally associated with the combination of strongly coupled ions and moderately degenerate electrons, and careful attention to quantum physics and electronic structure is essential. The lack of a small perturbation parameter greatly limits approximate attempts at its accurate description. Since WDM resides at the intersection of solid state and high energy density physics, many high energy density physics (HEDP) experiments pass through this difficult region of phase space. Thus, understanding and modeling WDM is key to the success of experiments on diverse facilities. These include the National Ignition Campaign centered on the National Ignition Facility (NIF), pulsed-power driven experiments on the Z machine, ion-beam-driven WDM experiments on the NDCX-II, and fundamental WDM research at the Linear Coherent...

  12. Intrinsically secure fast reactors with dense cores

    International Nuclear Information System (INIS)

    Slessarev, Igor

    2007-01-01

    Secure safety, resistance to weapons material proliferation and problems of long-lived wastes remain the most important 'painful points' of nuclear power. Many innovative reactor concepts have been developed aimed at a radical enhancement of safety. The promising potential of innovative nuclear reactors allows for shifting accents in current reactor safety 'strategy' to reveal this worth. Such strategy is elaborated focusing on the priority for intrinsically secure safety features as well as on sure protection being provided by the first barrier of defence. Concerning the potential of fast reactors (i.e. sodium cooled, lead-cooled, etc.), there are no doubts that they are able to possess many favourable intrinsically secure safety features and to lay the proper foundation for a new reactor generation. However, some of their neutronic characteristics have to be radically improved. Among intrinsically secure safety properties, the following core parameters are significantly important: reactivity margin values, reactivity feed-back and coolant void effects. Ways of designing intrinsically secure safety features in fast reactors (titled hereafter as Intrinsically Secure Fast Reactors - ISFR) can be found in the frame of current reactor technologies by radical enhancement of core neutron economy and by optimization of core compositions. Simultaneously, respecting resistance to proliferation, by using non-enriched fuel feed as well as a core breeding gain close to zero, are considered as the important features (long-lived waste problems will be considered in a separate paper). This implies using the following reactor design options as well as closed fuel cycles with natural U as the reactor feed: ·Ultra-plate 'dense cores' of the ordinary (monolithic) type with negative total coolant void effects. ·Modular type cores. Multiple dense modules can be embedded in the common reflector for achieving the desired NPP total power. The modules can be used also independently (as

  13. Coherent neutrino interactions in a dense medium

    International Nuclear Information System (INIS)

    Kiers, K.; Weiss, N.

    1997-01-01

    Motivated by the effect of matter on neutrino oscillations (the MSW effect) we study in more detail the propagation of neutrinos in a dense medium. The dispersion relation for massive neutrinos in a medium is known to have a minimum at nonzero momentum p∼G F ρ/√(2). We study in detail the origin and consequences of this dispersion relation for both Dirac and Majorana neutrinos both in a toy model with only neutral currents and a single neutrino flavor and in a realistic open-quotes standard modelclose quotes with two neutrino flavors. We find that for a range of neutrino momenta near the minimum of the dispersion relation, Dirac neutrinos are trapped by their coherent interactions with the medium. This effect does not lead to the trapping of Majorana neutrinos. copyright 1997 The American Physical Society

  14. Equation of state of dense baryonic matter

    International Nuclear Information System (INIS)

    Weber, F.; Weigel, M.K.

    1989-01-01

    In a previous investigation we treated nuclear matter as well as neutron matter at zero and finite temperatures in the frame of different relativistic field theoretical models, but with the restriction to nucleons as the only present baryons. This approach is extended by including a larger fraction of baryons and mesons, necessary for a description of baryon matter under extreme conditions. The equation of state (EOS) is calculated in both the Hartree and Hartree-Fock (HF) approximations for dense nuclear as well as neutron matter. Self-interactions of the σ field up to fourth order have been taken into account. For the treatment of many-baryon matter in the HF approach the parameters of the theory had to be readjusted. A phase transition of both many-baryon systems (neutron as well as nuclear matter) in the high-pressure and high-energy-density region has been found. (author)

  15. Nonlinear extraordinary wave in dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Krasovitskiy, V. B., E-mail: krasovit@mail.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Turikov, V. A. [Russian University of Peoples’ Friendship (Russian Federation)

    2013-10-15

    Conditions for the propagation of a slow extraordinary wave in dense magnetized plasma are found. A solution to the set of relativistic hydrodynamic equations and Maxwell’s equations under the plasma resonance conditions, when the phase velocity of the nonlinear wave is equal to the speed of light, is obtained. The deviation of the wave frequency from the resonance frequency is accompanied by nonlinear longitudinal-transverse oscillations. It is shown that, in this case, the solution to the set of self-consistent equations obtained by averaging the initial equations over the period of high-frequency oscillations has the form of an envelope soliton. The possibility of excitation of a nonlinear wave in plasma by an external electromagnetic pulse is confirmed by numerical simulations.

  16. Dense gas dispersion in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Morten

    1998-09-01

    Dense gas dispersion is characterized by buoyancy induced gravity currents and reduction of the vertical mixing. Liquefied gas releases from industrial accidents are cold because of the heat of evaporation which determines the density for a given concentration and physical properties. The temperature deficit is moderated by the heat flux from the ground, and this convection is an additional source of turbulence which affects the mixing. A simple model as the soil heat flux is used to estimate the ability of the ground to sustain the heat flux during release. The initial enthalpy, release rate, initial entrainment and momentum are discussed for generic source types and the interaction with obstacles is considered. In the MTH project BA experiments source with and without momentum were applied. The continuously released propane gas passed a two-dimensional removable obstacle perpendicular to the wind direction. Ground-level gas concentrations and vertical profiles of concentration, temperature, wind speed and turbulence were measured in front of and behind the obstacle. Ultrasonic anemometers providing fast velocity and concentration signals were mounted at three levels on the masts. The observed turbulence was influenced by the stability and the initial momentum of the jet releases. Additional information were taken from the `Dessert tortoise` ammonia jet releases, from the `Fladis` experiment with transition from dense to passive dispersion, and from the `Thorney Island` continuous releases of isothermal freon mixtures. The heat flux was found to moderate the negative buoyancy in both the propane and ammonia experiments. The heat flux measurements are compared to an estimate by analogy with surface layer theory. (au) 41 tabs., 146 ills., 189 refs.

  17. Ab initio calculation of the zero-point energy in dense hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takezawa, Tomoki [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Nagara, Hitose [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Nagao, Kazutaka [Laboratory of Atomic and Solid State Physics, Cornel University, Ithaca, NY (United States)

    2002-11-11

    We have studied the vibrational modes and their frequencies in both atomic and molecular phases of dense hydrogen to find the stable structures and evaluated the zero-point energies (ZPEs) and the effect on molecular dissociation. The most probable structure in the atomic phase is Cs IV whose vibrational modes have real frequencies over the whole Brillouin zone. And the structure in the molecular phase is very close to Cmca, whose vibrational modes with imaginary frequencies work as guides to the stable structure. Our estimates of the ZPE are very close to those of Kagan et al (Kagan Yu, Pushkarev V V and Kholas A 1977 Sov. Phys.-JETP 46 511). Adding the ZPE to the static energy, we estimated its effect on the pressure of the molecular dissociation. The reduction of the dissociation pressure due to the inclusion of the ZPE becomes over 100 GPa.

  18. Ab initio calculation of the zero-point energy in dense hydrogen

    International Nuclear Information System (INIS)

    Takezawa, Tomoki; Nagara, Hitose; Nagao, Kazutaka

    2002-01-01

    We have studied the vibrational modes and their frequencies in both atomic and molecular phases of dense hydrogen to find the stable structures and evaluated the zero-point energies (ZPEs) and the effect on molecular dissociation. The most probable structure in the atomic phase is Cs IV whose vibrational modes have real frequencies over the whole Brillouin zone. And the structure in the molecular phase is very close to Cmca, whose vibrational modes with imaginary frequencies work as guides to the stable structure. Our estimates of the ZPE are very close to those of Kagan et al (Kagan Yu, Pushkarev V V and Kholas A 1977 Sov. Phys.-JETP 46 511). Adding the ZPE to the static energy, we estimated its effect on the pressure of the molecular dissociation. The reduction of the dissociation pressure due to the inclusion of the ZPE becomes over 100 GPa

  19. X-ray Thomson scattering measurement of temperature in warm dense carbon

    Czech Academy of Sciences Publication Activity Database

    Falk, Kateřina; Fryer, C.L.; Gamboa, E. J.; Greeff, C.W.; Johns, H.M.; Schmidt, D.W.; Šmíd, Michal; Benage, J. F.; Montgomery, D. S.

    2017-01-01

    Roč. 57, č. 1 (2017), s. 47-53 ISSN 0741-3335 R&D Projects: GA MŠk EF15_008/0000162; GA MŠk LQ1606 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : warm dense matter * equation of state * laser plasmas * dynamic compression * shock physics Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016

  20. Excitation of hydrogen atom by ultrashort laser pulses in optically dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Calisti, A. [Aix Marseille Universite, CNRS, PIIM, Marseille (France); Astapenko, V.A. [Moscow Institute of Physics and Technology, Dolgoprudnyi (Russian Federation); Lisitsa, V.S. [Moscow Institute of Physics and Technology, Dolgoprudnyi (Russian Federation); Russian Research Center ' ' Kurchatov Institute' ' , Moscow (Russian Federation); National Research Nuclear University MEPhI, Moscow (Russian Federation)

    2017-10-15

    The features of excitation of a hydrogen atom by ultrashort laser pulses (USP) with a Gaussian envelope in optically dense plasma at a Lyman-beta transition are studied theoretically. The problem is of interest for diagnostics of optically dense media. USP have two doubtless advantages over conventional laser excitation: (a) the USP carrier frequency is shifted to the region of short wavelengths allowing exciting atoms from the ground state and (b) the wide spectrum of USP allows them to penetrate into optically dense media to much longer distances as compared with monochromatic radiation. As actual realistic cases, two examples are considered: hot rarefied plasma (the coronal limit) and dense cold plasma (the Boltzmann equilibrium). Universal expressions for the total probability of excitation of the transition under consideration are obtained in view of absorption of radiation in a medium. As initial data for the spectral form of a line, the results of calculations by methods of molecular dynamics are used. The probability of excitation of an atom is analysed for different values of problem parameters: the pulse duration, the optical thickness of a medium, and the detuning of the pulse carrier frequency from the eigenfrequency of an electron transition. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Gyroelastic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Kerbel, G.D.

    1981-01-20

    A study is made of a scale model in three dimensions of a guiding center plasma within the purview of gyroelastic (also known as finite gyroradius-near theta pinch) magnetohydrodynamics. The (nonlinear) system sustains a particular symmetry called isorrhopy which permits the decoupling of fluid modes from drift modes. Isorrhopic equilibria are analyzed within the framework of geometrical optics resulting in (local) dispersion relations and ray constants. A general scheme is developed to evolve an arbitrary linear perturbation of a screwpinch equilibrium as an invertible integral transform (over the complete set of generalized eigenfunctions defined naturally by the equilibrium). Details of the structure of the function space and the associated spectra are elucidated. Features of the (global) dispersion relation owing to the presence of gyroelastic stabilization are revealed. An energy principle is developed to study the stability of the tubular screwpinch.

  2. Gyroelastic fluids

    International Nuclear Information System (INIS)

    Kerbel, G.D.

    1981-01-01

    A study is made of a scale model in three dimensions of a guiding center plasma within the purview of gyroelastic (also known as finite gyroradius-near theta pinch) magnetohydrodynamics. The (nonlinear) system sustains a particular symmetry called isorrhopy which permits the decoupling of fluid modes from drift modes. Isorrhopic equilibria are analyzed within the framework of geometrical optics resulting in (local) dispersion relations and ray constants. A general scheme is developed to evolve an arbitrary linear perturbation of a screwpinch equilibrium as an invertible integral transform (over the complete set of generalized eigenfunctions defined naturally by the equilibrium). Details of the structure of the function space and the associated spectra are elucidated. Features of the (global) dispersion relation owing to the presence of gyroelastic stabilization are revealed. An energy principle is developed to study the stability of the tubular screwpinch

  3. Capillary waves of compressible fluids

    International Nuclear Information System (INIS)

    Falk, Kerstin; Mecke, Klaus

    2011-01-01

    The interplay of thermal noise and molecular forces is responsible for surprising features of liquids on sub-micrometer lengths-in particular at interfaces. Not only does the surface tension depend on the size of an applied distortion and nanoscopic thin liquid films dewet faster than would be expected from hydrodynamics, but also the dispersion relation of capillary waves differ at the nanoscale from the familiar macroscopic behavior. Starting with the stochastic Navier-Stokes equation we study the coupling of capillary waves to acoustic surface waves which is possible in compressible fluids. We find propagating 'acoustic-capillary waves' at nanometer wavelengths where in incompressible fluids capillary waves are overdamped.

  4. Bulk and shear viscosities of hot and dense hadron gas

    International Nuclear Information System (INIS)

    Kadam, Guru Prakash; Mishra, Hiranmaya

    2015-01-01

    We estimate the bulk and the shear viscosity at finite temperature and baryon densities of hadronic matter within a hadron resonance gas model which includes a Hagedorn spectrum. The parameters of the Hagedorn spectrum are adjusted to fit recent lattice QCD simulations at finite chemical potential. For the estimation of the bulk viscosity we use low energy theorems of QCD for the energy momentum tensor correlators. For the shear viscosity coefficient, we estimate the same using molecular kinetic theory to relate the shear viscosity coefficient to average momentum of the hadrons in the hot and dense hadron gas. The bulk viscosity to entropy ratio increases with chemical potential and is related to the reduction of velocity of sound at nonzero chemical potential. The shear viscosity to entropy ratio on the other hand, shows a nontrivial behavior with the ratio decreasing with chemical potential for small temperatures but increasing with chemical potential at high temperatures and is related to decrease of entropy density with chemical potential at high temperature due to finite volume of the hadrons

  5. Breast cancer screening in Korean woman with dense breast tissue

    International Nuclear Information System (INIS)

    Shin, Hee Jung; Ko, Eun Sook; Yi, Ann

    2015-01-01

    Asian women, including Korean, have a relatively higher incidence of dense breast tissue, compared with western women. Dense breast tissue has a lower sensitivity for the detection of breast cancer and a higher relative risk for breast cancer, compared with fatty breast tissue. Thus, there were limitations in the mammographic screening for women with dense breast tissue, and many studies for the supplemental screening methods. This review included appropriate screening methods for Korean women with dense breasts. We also reviewed the application and limitation of supplemental screening methods, including breast ultrasound, digital breast tomosynthesis, and breast magnetic resonance imaging; and furthermore investigated the guidelines, as well as the study results

  6. Breast cancer screening in Korean woman with dense breast tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hee Jung [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Ko, Eun Sook [Dept. of Radiology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul (Korea, Republic of); Yi, Ann [Dept. of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul (Korea, Republic of)

    2015-11-15

    Asian women, including Korean, have a relatively higher incidence of dense breast tissue, compared with western women. Dense breast tissue has a lower sensitivity for the detection of breast cancer and a higher relative risk for breast cancer, compared with fatty breast tissue. Thus, there were limitations in the mammographic screening for women with dense breast tissue, and many studies for the supplemental screening methods. This review included appropriate screening methods for Korean women with dense breasts. We also reviewed the application and limitation of supplemental screening methods, including breast ultrasound, digital breast tomosynthesis, and breast magnetic resonance imaging; and furthermore investigated the guidelines, as well as the study results.

  7. Monte Carlo simulations for thermodynamical properties calculations of plasmas at thermodynamical equilibrium. Applications to opacity and equation of state calculations; Apport d'un code de simulation Monte Carlo pour l'etude des proprietes thermodynamiques d'un plasma a l'equilibre et application au calcul de l'elargissement des profils de raies ioniques emises dans les plasmas denses, aux opacites spectrales et aux equations d'etat de systemes fluides

    Energy Technology Data Exchange (ETDEWEB)

    Gilles, D

    2005-07-01

    This report is devoted to illustrate the power of a Monte Carlo (MC) simulation code to study the thermodynamical properties of a plasma, composed of classical point particles at thermodynamical equilibrium. Such simulations can help us to manage successfully the challenge of taking into account 'exactly' all classical correlations between particles due to density effects, unlike analytical or semi-analytical approaches, often restricted to low dense plasmas. MC simulations results allow to cover, for laser or astrophysical applications, a wide range of thermodynamical conditions from more dense (and correlated) to less dense ones (where potentials are long ranged type). Therefore Yukawa potentials, with a Thomas-Fermi temperature- and density-dependent screening length, are used to describe the effective ion-ion potentials. In this report we present two MC codes ('PDE' and 'PUCE') and applications performed with these codes in different fields (spectroscopy, opacity, equation of state). Some examples of them are discussed and illustrated at the end of the report. (author)

  8. Connecting Molecular Dynamics and Computational Fluid Dynamics

    NARCIS (Netherlands)

    Markesteijn, A.P.

    2011-01-01

    One of the most important developments in the last centuries is the process of miniaturisation and understanding everything that it entails. For the physical sciences this meant the continuing discovery what matter is and how it behaves, while from a practical point of view it meant that more

  9. Spiers Memorial Lecture. Molecular mechanics and molecular electronics.

    Science.gov (United States)

    Beckman, Robert; Beverly, Kris; Boukai, Akram; Bunimovich, Yuri; Choi, Jang Wook; DeIonno, Erica; Green, Johnny; Johnston-Halperin, Ezekiel; Luo, Yi; Sheriff, Bonnie; Stoddart, Fraser; Heath, James R

    2006-01-01

    We describe our research into building integrated molecular electronics circuitry for a diverse set of functions, and with a focus on the fundamental scientific issues that surround this project. In particular, we discuss experiments aimed at understanding the function of bistable rotaxane molecular electronic switches by correlating the switching kinetics and ground state thermodynamic properties of those switches in various environments, ranging from the solution phase to a Langmuir monolayer of the switching molecules sandwiched between two electrodes. We discuss various devices, low bit-density memory circuits, and ultra-high density memory circuits that utilize the electrochemical switching characteristics of these molecules in conjunction with novel patterning methods. We also discuss interconnect schemes that are capable of bridging the micrometre to submicrometre length scales of conventional patterning approaches to the near-molecular length scales of the ultra-dense memory circuits. Finally, we discuss some of the challenges associated with fabricated ultra-dense molecular electronic integrated circuits.

  10. Transport coefficients for dense hard-disk systems.

    Science.gov (United States)

    García-Rojo, Ramón; Luding, Stefan; Brey, J Javier

    2006-12-01

    A study of the transport coefficients of a system of elastic hard disks based on the use of Helfand-Einstein expressions is reported. The self-diffusion, the viscosity, and the heat conductivity are examined with averaging techniques especially appropriate for event-driven molecular dynamics algorithms with periodic boundary conditions. The density and size dependence of the results are analyzed, and comparison with the predictions from Enskog's theory is carried out. In particular, the behavior of the transport coefficients in the vicinity of the fluid-solid transition is investigated and a striking power law divergence of the viscosity with density is obtained in this region, while all other examined transport coefficients show a drop in that density range in relation to the Enskog's prediction. Finally, the deviations are related to shear band instabilities and the concept of dilatancy.

  11. Physical properties of dense, low-temperature plasmas

    International Nuclear Information System (INIS)

    Redmer, R.

    1997-01-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied wthin linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). mercury within the MHNC scheme via effective ion-ion potentials which are derived from the polarization function within an extended RPA. The optical properties of dense plasmas, the shift

  12. Gas suspension flows of a moderately dense binary mixture of solid particles in vertical tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zamankhan, P.; Huotari, J. [VTT Energy, Jyvaeskylae (Finland). Combustion and Conversion Lab.

    1996-12-01

    The turbulent, steady, fully-developed flow of a moderately dense (solid volume faction >>0.001) binary mixture of spherical particles in a gaseous carrier is investigated for the case of flow in a vertical riser. The suspended particles are considered to be in turbulent motion, driven by random aerodynamic forces acting between the particle and the gaseous carrier as well as particle-particle interactive forces. A model is constructed based on the combination of the time-averaged after volume-averaged conservation equations of mass, momentum and mechanical energy of the gas phase in the continuum theory and the corresponding equations for the solid particles obtained using the recently developed Enskog theory for dense multi-component mixtures of slightly inelastic spherical particles. The model properly takes into account the contributions of particle-particle collisions, as well as the fluid-dynamic fluctuating forces on individual particles. To demonstrate the validity of this approach, the fully-developed steady-state mean velocity and concentration distributions of a moderately dense binary mixture of solid particles in a turbulent vertical flow calculated by the present model are compared with available experimental measurements. The results provide a qualitative description of the experimentally observed motion of coarse particles in a fast bed of fine solids. (author)

  13. Characterisation of Ferrosilicon Dense Medium Separation Material

    International Nuclear Information System (INIS)

    Waanders, F. B.; Mans, A.

    2003-01-01

    Ferrosilicon is used in the dense medium separation of iron ore at Kumba resources, Sishen, South Africa. Due to high cost and losses that occur during use, maximum recovery by means of magnetic separation is aimed for. The purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and use thereof. Scanning electron microscopy was used to determine the composition of each sample, whilst Moessbauer spectroscopy yielded a two-sextet spectrum with hyperfine magnetic field strengths of 20 and 31 T, respectively, for the fresh samples. Additional hematite oxide peaks appeared in the Moessbauer spectra after use of the Fe-Si over a length of time, but this did not result in a dramatic degradation of the medium. No definite changes occurred during correct storage methods. It was, however, found that the biggest loss of Fe-Si was due to the abrasion of the particles, which resulted in the formation of an oxihydroxide froth, during the process.

  14. Improved models of dense anharmonic lattices

    Energy Technology Data Exchange (ETDEWEB)

    Rosenau, P., E-mail: rosenau@post.tau.ac.il; Zilburg, A.

    2017-01-15

    We present two improved quasi-continuous models of dense, strictly anharmonic chains. The direct expansion which includes the leading effect due to lattice dispersion, results in a Boussinesq-type PDE with a compacton as its basic solitary mode. Without increasing its complexity we improve the model by including additional terms in the expanded interparticle potential with the resulting compacton having a milder singularity at its edges. A particular care is applied to the Hertz potential due to its non-analyticity. Since, however, the PDEs of both the basic and the improved model are ill posed, they are unsuitable for a study of chains dynamics. Using the bond length as a state variable we manipulate its dispersion and derive a well posed fourth order PDE. - Highlights: • An improved PDE model of a Newtonian lattice renders compacton solutions. • Compactons are classical solutions of the improved model and hence amenable to standard analysis. • An alternative well posed model enables to study head on interactions of lattices' solitary waves. • Well posed modeling of Hertz potential.

  15. Load Designs For MJ Dense Plasma Foci

    Science.gov (United States)

    Link, A.; Povlius, A.; Anaya, R.; Anderson, M. G.; Angus, J. R.; Cooper, C. M.; Falabella, S.; Goerz, D.; Higginson, D.; Holod, I.; McMahon, M.; Mitrani, J.; Koh, E. S.; Pearson, A.; Podpaly, Y. A.; Prasad, R.; van Lue, D.; Watson, J.; Schmidt, A. E.

    2017-10-01

    Dense plasma focus (DPF) Z-pinches are compact pulse power driven devices with coaxial electrodes. The discharge of DPF consists of three distinct phases: first generation of a plasma sheath, plasma rail gun phase where the sheath is accelerated down the electrodes and finally an implosion phase where the plasma stagnates into a z-pinch geometry. During the z-pinch phase, DPFs can produce MeV ion beams, x-rays and neutrons. Megaampere class DPFs with deuterium fills have demonstrated neutron yields in the 1012 neutrons/shot range with pulse durations of 10-100 ns. Kinetic simulations using the code Chicago are being used to evaluate various load configurations from initial sheath formation to the final z-pinch phase for DPFs with up to 5 MA and 1 MJ coupled to the load. Results will be presented from the preliminary design simulations. LLNL-ABS-734785 This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and with support from the Computing Grand Challenge program at LLNL.

  16. Kinetic Simulations of Dense Plasma Focus Breakdown

    Science.gov (United States)

    Schmidt, A.; Higginson, D. P.; Jiang, S.; Link, A.; Povilus, A.; Sears, J.; Bennett, N.; Rose, D. V.; Welch, D. R.

    2015-11-01

    A dense plasma focus (DPF) device is a type of plasma gun that drives current through a set of coaxial electrodes to assemble gas inside the device and then implode that gas on axis to form a Z-pinch. This implosion drives hydrodynamic and kinetic instabilities that generate strong electric fields, which produces a short intense pulse of x-rays, high-energy (>100 keV) electrons and ions, and (in deuterium gas) neutrons. A strong factor in pinch performance is the initial breakdown and ionization of the gas along the insulator surface separating the two electrodes. The smoothness and isotropy of this ionized sheath are imprinted on the current sheath that travels along the electrodes, thus making it an important portion of the DPF to both understand and optimize. Here we use kinetic simulations in the Particle-in-cell code LSP to model the breakdown. Simulations are initiated with neutral gas and the breakdown modeled self-consistently as driven by a charged capacitor system. We also investigate novel geometries for the insulator and electrodes to attempt to control the electric field profile. The initial ionization fraction of gas is explored computationally to gauge possible advantages of pre-ionization which could be created experimentally via lasers or a glow-discharge. Prepared by LLNL under Contract DE-AC52-07NA27344.

  17. Neutrino ground state in a dense star

    International Nuclear Information System (INIS)

    Kiers, K.; Tytgat, M.H.

    1998-01-01

    It has recently been argued that long range forces due to the exchange of massless neutrinos give rise to a very large self-energy in a dense, finite-ranged, weakly charged medium. Such an effect, if real, would destabilize a neutron star. To address this issue we have studied the related problem of a massless neutrino field in the presence of an external, static electroweak potential of finite range. To be precise, we have computed to one loop the exact vacuum energy for the case of a spherical square well potential of depth α and radius R. For small wells, the vacuum energy is reliably determined by a perturbative expansion in the external potential. For large wells, however, the perturbative expansion breaks down. A manifestation of this breakdown is that the vacuum carries a non-zero neutrino charge. The energy and neutrino charge of the ground state are, to a good approximation for large wells, those of a neutrino condensate with chemical potential μ=α. Our results demonstrate explicitly that long-range forces due to the exchange of massless neutrinos do not threaten the stability of neutron stars. copyright 1998 The American Physical Society

  18. Neutral helium spectral lines in dense plasmas

    International Nuclear Information System (INIS)

    Omar, Banaz; Wierling, August; Roepke, Gerd; Guenter, Sibylle

    2006-01-01

    Shift and broadening of isolated neutral helium lines 7281 A ring (2 1 P-3 1 S), 7065 A ring (2 3 P-3 3 S), 6678 A ring (2 1 P-3 1 D), 5048 A ring (2 1 P-4 1 S), 4922 A ring (2 1 P-4 1 D), and 4713 A ring (2 3 P-4 3 S) in a dense plasma are investigated. Based on a quantum statistical theory, the electronic contributions to the shift and width are considered, using the method of thermodynamic Green functions. Dynamic screening of the electron-atom interaction is included. Compared to the width, the electronic shift is more affected by dynamical screening. This effect increases at high density. A cut-off procedure for strong collisions is used. The contribution of the ions is taken into account in a quasi-static approximation, with both the quadratic Stark effect and the quadrupole interaction included. The results for shift and width agree well with the available experimental and theoretical data

  19. Deterministic dense coding and entanglement entropy

    International Nuclear Information System (INIS)

    Bourdon, P. S.; Gerjuoy, E.; McDonald, J. P.; Williams, H. T.

    2008-01-01

    We present an analytical study of the standard two-party deterministic dense-coding protocol, under which communication of perfectly distinguishable messages takes place via a qudit from a pair of nonmaximally entangled qudits in a pure state |ψ>. Our results include the following: (i) We prove that it is possible for a state |ψ> with lower entanglement entropy to support the sending of a greater number of perfectly distinguishable messages than one with higher entanglement entropy, confirming a result suggested via numerical analysis in Mozes et al. [Phys. Rev. A 71, 012311 (2005)]. (ii) By explicit construction of families of local unitary operators, we verify, for dimensions d=3 and d=4, a conjecture of Mozes et al. about the minimum entanglement entropy that supports the sending of d+j messages, 2≤j≤d-1; moreover, we show that the j=2 and j=d-1 cases of the conjecture are valid in all dimensions. (iii) Given that |ψ> allows the sending of K messages and has √(λ 0 ) as its largest Schmidt coefficient, we show that the inequality λ 0 ≤d/K, established by Wu et al. [Phys. Rev. A 73, 042311 (2006)], must actually take the form λ 0 < d/K if K=d+1, while our constructions of local unitaries show that equality can be realized if K=d+2 or K=2d-1

  20. Thermochemistry of dense hydrous magnesium silicates

    Science.gov (United States)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  1. Borehole stability in densely welded tuffs

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1992-07-01

    The stability of boreholes, or more generally of underground openings (i.e. including shafts, ramps, drifts, tunnels, etc.) at locations where seals or plugs are to be placed is an important consideration in seal design for a repository (Juhlin and Sandstedt, 1989). Borehole instability or borehole breakouts induced by stress redistribution could negate the effectiveness of seals or plugs. Breakout fractures along the wall of repository excavations or exploratory holes could provide a preferential flowpath for groundwater or gaseous radionuclides to bypass the plugs. After plug installation, swelling pressures exerted by a plug could induce radial cracks or could open or widen preexisting cracks in the rock at the bottom of the breakouts where the tangential compressive stresses have been released by the breakout process. The purpose of the work reported here is to determine experimentally the stability of a circular hole in a welded tuff sample subjected to various external boundary loads. Triaxial and biaxial borehole stability tests have been performed on densely welded Apache Leap tuff samples and Topopah Spring tuff samples. The nominal diameter of the test hole is 13.3 or 14.4 mm for triaxial testing, and 25.4 mm for biaxial testing. The borehole axis is parallel to one of the principal stress axes. The boreholes are drilled through the samples prior to applying external boundary loads. The boundary loads are progressively increased until breakouts occur or until the maximum load capacity of the loading system has been reached. 74 refs

  2. Matching Cost Filtering for Dense Stereo Correspondence

    Directory of Open Access Journals (Sweden)

    Yimin Lin

    2013-01-01

    Full Text Available Dense stereo correspondence enabling reconstruction of depth information in a scene is of great importance in the field of computer vision. Recently, some local solutions based on matching cost filtering with an edge-preserving filter have been proved to be capable of achieving more accuracy than global approaches. Unfortunately, the computational complexity of these algorithms is quadratically related to the window size used to aggregate the matching costs. The recent trend has been to pursue higher accuracy with greater efficiency in execution. Therefore, this paper proposes a new cost-aggregation module to compute the matching responses for all the image pixels at a set of sampling points generated by a hierarchical clustering algorithm. The complexity of this implementation is linear both in the number of image pixels and the number of clusters. Experimental results demonstrate that the proposed algorithm outperforms state-of-the-art local methods in terms of both accuracy and speed. Moreover, performance tests indicate that parameters such as the height of the hierarchical binary tree and the spatial and range standard deviations have a significant influence on time consumption and the accuracy of disparity maps.

  3. The Green Bank Ammonia Survey: Observations of Hierarchical Dense Gas Structures in Cepheus-L1251

    Science.gov (United States)

    Keown, Jared; Di Francesco, James; Kirk, Helen; Friesen, Rachel K.; Pineda, Jaime E.; Rosolowsky, Erik; Ginsburg, Adam; Offner, Stella S. R.; Caselli, Paola; Alves, Felipe; Chacón-Tanarro, Ana; Punanova, Anna; Redaelli, Elena; Seo, Young Min; Matzner, Christopher D.; Chun-Yuan Chen, Michael; Goodman, Alyssa A.; Chen, How-Huan; Shirley, Yancy; Singh, Ayushi; Arce, Hector G.; Martin, Peter; Myers, Philip C.

    2017-11-01

    We use Green Bank Ammonia Survey observations of NH3 (1, 1) and (2, 2) emission with 32″ FWHM resolution from a ˜10 pc2 portion of the Cepheus-L1251 molecular cloud to identify hierarchical dense gas structures. Our dendrogram analysis of the NH3 data results in 22 top-level structures, which reside within 13 lower-level parent structures. The structures are compact (0.01 {pc}≲ {R}{eff}≲ 0.1 {pc}) and are spatially correlated with the highest H2 column density portions of the cloud. We also compare the ammonia data to a catalog of dense cores identified by higher-resolution (18.″2 FWHM) Herschel Space Observatory observations of dust continuum emission from Cepheus-L1251. Maps of kinetic gas temperature, velocity dispersion, and NH3 column density, derived from detailed modeling of the NH3 data, are used to investigate the stability and chemistry of the ammonia-identified and Herschel-identified structures. We show that the dust and dense gas in the structures have similar temperatures, with median T dust and T K measurements of 11.7 ± 1.1 K and 10.3 ± 2.0 K, respectively. Based on a virial analysis, we find that the ammonia-identified structures are gravitationally dominated, yet may be in or near a state of virial equilibrium. Meanwhile, the majority of the Herschel-identified dense cores appear to be not bound by their own gravity and instead confined by external pressure. CCS (20 - 10) and HC5N (9-8) emission from the region reveal broader line widths and centroid velocity offsets when compared to the NH3 (1, 1) emission in some cases, likely due to these carbon-based molecules tracing the turbulent outer layers of the dense cores.

  4. Dynamic aerofracture or hydrofracture of dense granular packing: pressure and viscosity control of the fracture patterns

    Science.gov (United States)

    Niebling, Michael J.; Toussaint, Renaud; Flekkøy, Eirik G.; Jørgen Måløy, Knut

    2013-04-01

    Stress induced by fluid or gases can cause diverse materials to break and fracture. Such hydraulic fractures are a natural and common phenomenon in the field of volcanism and are artificially initiated to enhance the recovery of natural gas and mineral oil by fracturing the reservoir rock with pressurized fluids. A procedure also known as fracking. Recently a new perspective on hydrofractures was added with the storage of supercritical CO2. In this respect two scenarios are considered. First it is one option to inject CO2 into existing hydrofractures, and second the injection of the CO2 can create additional fractures. The typical components for such fractures are a porous material and a compressible gas. The dynamics of such fractures and displacement patterns are simulated and studied in a rectangular Hele-Shaw cell filled with a dense but permeable two-dimensional granular layer. The model used, mixing highly deformable solid and fluid components, can simulate sedimentation problems [1,2], as well as hydrofracture or aerofracture ones. The emerging displacement patterns and fractures variate according to the properties of the injected fluid or gas and the characteristics of the granular phase [3]. The physics behind these variations is discussed and explained. The role of the fluid viscosity and system size shows to lead to a transition from fracturing to compaction, depending on the dynamics of convection versus diffusion of overpressure. The dependence of the obtained patterns on the injection pressure is also explored [4]. References: [1] Niebling, M.J., E.G. Flekkøy, K.J. Måløy, R. Toussaint, Sedimentation instabilities: impact of the fluid compressibility and viscosity, Phys. Rev. E 82, 051302, 2010. doi: 10.1103/PhysRevE.82.051302 [2] Niebling, M.J., E.G. Flekkøy, K.J. Måløy, R. Toussaint, Mixing of a granular layer falling through a fluid, Phys. Rev. E 82, 011301 (2010) doi: 10.1103/PhysRevE.82.011301 [3] Niebling, M., R. Toussaint, E.G. Flekk

  5. Description of a general method to compute the fluid-structure interaction

    International Nuclear Information System (INIS)

    Jeanpierre, F.; Gibert, R.J.; Hoffmann, A.; Livolant, M.

    1979-01-01

    The vibrational characteristics of a structure in air may be considerably modified when the structure is immersed in a dense fluid. Such fluid structure interaction effects are important for the seismic or flow induced vibrational studies of various nuclear equipments, as for example the PWR internals, the fast reactor vessels, heat exchangers and fuel elements. In some simple situations, the fluid effects can be simulate by added masses, but in general, they are much more complicated. A general formulation to calculate precisely the vibrational behaviour of structures containing dense fluids is presented in this paper. That formulation can be easily introduced in finite elements computer codes, the fluid being described by special fluid elements. Its use is in principle limited to the linear range: small movements of structures, small pressure fluctuations. (orig.)

  6. Molecular diffusion in monolayer and submonolayer nitrogen

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter

    2001-01-01

    The orientational and translational motions in a monolayer fluid of physisorbed molecular nitrogen are treated using molecular dynamics simulations. Dynamical response functions and several approximations to the coefficient of translational diffusion are determined for adsorption on the basal plane...

  7. Mining connected global and local dense subgraphs for bigdata

    Science.gov (United States)

    Wu, Bo; Shen, Haiying

    2016-01-01

    The problem of discovering connected dense subgraphs of natural graphs is important in data analysis. Discovering dense subgraphs that do not contain denser subgraphs or are not contained in denser subgraphs (called significant dense subgraphs) is also critical for wide-ranging applications. In spite of many works on discovering dense subgraphs, there are no algorithms that can guarantee the connectivity of the returned subgraphs or discover significant dense subgraphs. Hence, in this paper, we define two subgraph discovery problems to discover connected and significant dense subgraphs, propose polynomial-time algorithms and theoretically prove their validity. We also propose an algorithm to further improve the time and space efficiency of our basic algorithm for discovering significant dense subgraphs in big data by taking advantage of the unique features of large natural graphs. In the experiments, we use massive natural graphs to evaluate our algorithms in comparison with previous algorithms. The experimental results show the effectiveness of our algorithms for the two problems and their efficiency. This work is also the first that reveals the physical significance of significant dense subgraphs in natural graphs from different domains.

  8. Dense chlorinated solvents and other DNAPLs in groundwater

    DEFF Research Database (Denmark)

    Broholm, K.

    1996-01-01

    Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996......Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996...

  9. Dry processing versus dense medium processing for preparing thermal coal

    CSIR Research Space (South Africa)

    De Korte, GJ

    2013-10-01

    Full Text Available of the final product. The separation efficiency of dry processes is, however, not nearly as good as that of dense medium and, as a result, it is difficult to effectively beneficiate coals with a high near-dense content. The product yield obtained from some raw...

  10. Interparticle interaction and transport processes in dense semiclassical plasmas

    International Nuclear Information System (INIS)

    Baimbetov, F.B.; Giniyatova, Sh.G.

    2005-01-01

    On the basis of the density response formalism an expression for the pseudopotential of dense semiclassical plasma, which takes account of quantum-mechanical effects, local field corrections, and electronic screening effects is obtained. The static structure factors taking into account both local fields and quantum-mechanical effects are calculated. An electrical conductivity, thermal conductivity, and viscosity of dense semiclassical plasma are studied

  11. Cleaning fluid emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Prikryl, J; Kotyza, R; Krulikovsky, J; Mjartan, V; Valisova, I

    1981-09-15

    Composition of cleaning fluid emulsion are presented for drilling small diameter wells in clay soils, at high drill bit rotation velocity. The emulsions have lubricating properties and the abilty to improve stability of the drilled soil. The given fluids have a high fatty acid content with 12-24 carbon atoms in a single molecule, with a predominance of resinous acids 1-5% in mass, and having been emulsified in water or clay suspension without additives, or in a clay suspension with high-molecular polymer additives (glycobate cellulose compounds and/or polysaccharides, and/or their derivatives) in an amount of 0.1-3% per mass; thinning agents - huminite or lignite compounds in the amount of 0.01 to 0.5% in mass; weighting material - barite or lime 0.01 to 50% per mass; medium stabilizers - organic poly-electrolyte with polyacrylate in the amount of 0.05 to 2% in mass, or alkaline chloride/alkaline-ground metals 1-10% per mass. A cleaning emulsion fluid was prepared in the laboratory according to the given method. Add 3 kg tall oil to a solution of 1 kg K/sub 2/CO/sub 3/ per 100 l of water. Dynamic viscosity was equal to 1.4 x 10-/sup 3/ Pa/s. When drilling in compacted clay soils, when the emulsions require improved stability, it is necessary to add the maximum amount of tall oil whose molecules are absorbed by the clay soil and increase its durability.

  12. Synovial fluid analysis

    Science.gov (United States)

    Joint fluid analysis; Joint fluid aspiration ... El-Gabalawy HS. Synovial fluid analysis, synovial biopsy, and synovial pathology. In: Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. Kelly's Textbook of ...

  13. Rainbow Particle Imaging Velocimetry for Dense 3D Fluid Velocity Imaging

    KAUST Repository

    Xiong, Jinhui; Idoughi, Ramzi; Aguirre-Pablo, Andres; Aljedaani, Abdulrahman Barakat; Dun, Xiong; Fu, Qiang; Thoroddsen, Sigurdur T; Heidrich, Wolfgang

    2017-01-01

    , to three dimensions by encoding depth into color. The encoding is achieved by illuminating the flow volume with a continuum of light planes (a “rainbow”), such that each depth corresponds to a specific wavelength of light. A diffractive component

  14. Self lubricating fluid bearings

    International Nuclear Information System (INIS)

    Kapich, D.D.

    1980-01-01

    The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid [fr

  15. Modern fluid dynamics

    CERN Document Server

    Kleinstreuer, Clement

    2018-01-01

    Modern Fluid Dynamics, Second Edition provides up-to-date coverage of intermediate and advanced fluids topics. The text emphasizes fundamentals and applications, supported by worked examples and case studies. Scale analysis, non-Newtonian fluid flow, surface coating, convection heat transfer, lubrication, fluid-particle dynamics, microfluidics, entropy generation, and fluid-structure interactions are among the topics covered. Part A presents fluids principles, and prepares readers for the applications of fluid dynamics covered in Part B, which includes computer simulations and project writing. A review of the engineering math needed for fluid dynamics is included in an appendix.

  16. Molecular Simulation towards Efficient and Representative Subsurface Reservoirs Modeling

    KAUST Repository

    Kadoura, Ahmad Salim

    2016-01-01

    This dissertation focuses on the application of Monte Carlo (MC) molecular simulation and Molecular Dynamics (MD) in modeling thermodynamics and flow of subsurface reservoir fluids. At first, MC molecular simulation is proposed as a promising method

  17. Fabrication of dense panels in lithium fluoride; Fabrication de panneaux denses en fluorure de lithium

    Energy Technology Data Exchange (ETDEWEB)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-15

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated.

  18. Acoustic modes in dense dusty plasmas

    International Nuclear Information System (INIS)

    Avinash, K.; Bhattacharjee, A.; Hu, S.

    2002-01-01

    Properties of acoustic modes in high dust density dusty plasmas are studied. The solutions of fluid equations for electrons, ions, and dust grains with collisional and ionization effects are solved along with an equation for grain charging. The high dust density effects on the acoustic modes are interpreted in terms of a change in the screening properties of the grain charge. At low dust density, the grain charge is screened due to electrons and ions. However, at high dust density, the screening of the grain charge due to other grains also becomes important. This leads to a reduction of the phase-velocity, which in turn is shown to make the plasma more unstable at high dust density. In this regime the role of the ion acoustic mode is replaced by the charging mode. The relevance of these results to earlier theoretical studies and experimental results are discussed

  19. FttC-Based Fronthaul for 5G Dense/Ultra-Dense Access Network: Performance and Costs in Realistic Scenarios

    Directory of Open Access Journals (Sweden)

    Franco Mazzenga

    2017-10-01

    Full Text Available One distinctive feature of the next 5G systems is the presence of a dense/ultra-dense wireless access network with a large number of access points (or nodes at short distances from each other. Dense/ultra-dense access networks allow for providing very high transmission capacity to terminals. However, the deployment of dense/ultra-dense networks is slowed down by the cost of the fiber-based infrastructure required to connect radio nodes to the central processing units and then to the core network. In this paper, we investigate the possibility for existing FttC access networks to provide fronthaul capabilities for dense/ultra-dense 5G wireless networks. The analysis is realistic in that it is carried out considering an actual access network scenario, i.e., the Italian FttC deployment. It is assumed that access nodes are connected to the Cabinets and to the corresponding distributors by a number of copper pairs. Different types of cities grouped in terms of population have been considered. Results focus on fronthaul transport capacity provided by the FttC network and have been expressed in terms of the available fronthaul bit rate per node and of the achievable coverage.

  20. Surveying the Dense Gas in Barnard 1 and NGC 1333 from Cloud to Core Scales

    Science.gov (United States)

    Storm, Shaye; Mundy, Lee; Teuben, Peter; Lee, Katherine; Fernandez-Lopez, Manuel; Looney, Leslie; Rosolowsky, Erik; Classy Collaboration

    2013-07-01

    The CARMA Large Area Star formation Survey (CLASSy) is mapping molecular emission across large areas of the nearby Perseus and Serpens Molecular Clouds. With an angular resolution of 7 arcsec, CLASSy probes dense gas on scales from a few thousand AU to parsecs with CARMA-23 and single-dish observations. The resulting maps of N2H+, HCN, and HCO+ J=1-0 trace the kinematics and structure of the high-density gas in regions covering a wide range of intrinsic star formation activity. This poster presents an overview of three completed CLASSy fields, NGC 1333, Barnard 1, and Serpens Main, and then focuses on the dendrogram analysis that CLASSy is using to characterize the emission structure. We have chosen a dendrogram analysis over traditional clump finding because dendrograms better encode the hierarchical nature of cloud structure and better facilitate analysis of cloud properties across the range of size scales probed by CLASSy. We present a new dendrogram methodology that allows for non-binary mergers of kernels, which results in a gas hierarchy that is more true to limitations of the S/N in the data. The resulting trees from Barnard 1 and NGC 1333 are used to derive physical parameters of the identified gas structures, and to probe the kinematic relationship between gas structures at different spatial scales and evolutionary stages. We derive a flat relation between mean internal turbulence and structure size for the dense gas in both regions, but find a difference between the magnitude of the internal turbulence in regions with and without protostars; the dense gas in the B1 main core and NGC 1333 are characterized by mostly transonic to supersonic turbulence, while the B1 filaments and clumps southwest of the main core have mostly subsonic turbulence. These initial results, along with upcoming work analyzing the completed CLASSy observations, will be used to test current theories for star formation in turbulent molecular clouds.

  1. Rates of Thermonuclear Reactions in Dense Plasmas

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Bornatici, M.

    2000-01-01

    The problem of plasma screening of thermonuclear reactions has attracted considerable scientific interest ever since Salpeter's seminal paper, but it is still faced with controversial statements and without any definite conclusion. It is of relevant importance to thermonuclear reactions in dense astrophysical plasmas, for which charge screening can substantially affect the reaction rates. Whereas Salpeter and a number of subsequent investigations have dealt with static screening, Carraro, Schafer, and Koonin have drawn attention to the fact that plasma screening of thermonuclear reactions is an essentially dynamic effect. In addressing the issue of collective plasma effects on the thermonuclear reaction rates, the first critical overview of most of the work carried out so far is presented and the validity of the test particle approach is assessed. In contrast to previous investigations, we base our description on the kinetic equation for nonequilibrium plasmas, which accounts for the effects on the rates of thermonuclear reactions of both plasma fluctuations and screening and allows one to analyze explicitly the effects of the fluctuations on the reaction rates. Such a kinetic formulation is more general than both Salpeter's approach and the recently developed statistical approaches and makes it possible to obtain a more comprehensive understanding of the problem. A noticeable result of the fluctuation approach is that the static screening, which affects both the interaction and the self-energy of the reacting nuclei, does not affect the reaction rates, in contrast with the results obtained so far. Instead, a reduction of the thermonuclear reaction rates is obtained as a result of the effect of plasma fluctuations related to the free self-energy of the reacting nuclei. A simple physical explanation of the slowing down of the reaction rates is given, and the relation to the dynamically screened test particle approach is discussed. Corrections to the reaction rates

  2. Neutrino reactions in hot and dense matter

    International Nuclear Information System (INIS)

    Lohs, Andreas

    2015-01-01

    In this thesis, neutrino reactions in hot and dense matter are studied. In particular, this work is concerned with neutrino-matter interactions that are relevant for neutrino transport in core-collapse supernovae (CCSNe). The majority of the energy from a CCSN is released in the form of neutrinos. Accurate understanding and computation of these interactions is most relevant to achieve sufficiently reliable predictions for the evolution of CCSNe and other related question such as the production of heavy elements or neutrino oscillations. For this purpose this work follows the combined approach of searching for new important neutrino reactions and improving the computation of those reactions that are already implemented. First we estimate the relevance of charged-current weak interactions that include muon-neutrinos or muons, as well as the role of neutron decay for neutrino transport in CCSNe. All of these reactions were previously neglected in CCSN-simulations. We derive and compute the matrix element and subsequent semi-analytic expressions for transport properties like the inverse mean free path of the new reactions. It is found that these reactions are important for muon neutrinos and low energy electron antineutrinos at very high densities in the protoneutron star surface. Consequently their implementation might lead to several changes in the prediction of CCSNe signatures such as the nucleosynthesis yields. Second we improve the precision in the computation of well known neutrino-nucleon reactions like neutrino absorption on neutrons. We derive semi-analytic expressions for transport properties that use less restrictive approximations while keeping the computational demand constant. Therefore we consider the full relativistic kinematics of all participating particles i.e. allowing for relativistic nucleons and finite lepton masses. Also the weak magnetism terms of the matrix elements are explicitly included to all orders. From our results we suggest that the

  3. Neutrino reactions in hot and dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Lohs, Andreas

    2015-04-13

    In this thesis, neutrino reactions in hot and dense matter are studied. In particular, this work is concerned with neutrino-matter interactions that are relevant for neutrino transport in core-collapse supernovae (CCSNe). The majority of the energy from a CCSN is released in the form of neutrinos. Accurate understanding and computation of these interactions is most relevant to achieve sufficiently reliable predictions for the evolution of CCSNe and other related question such as the production of heavy elements or neutrino oscillations. For this purpose this work follows the combined approach of searching for new important neutrino reactions and improving the computation of those reactions that are already implemented. First we estimate the relevance of charged-current weak interactions that include muon-neutrinos or muons, as well as the role of neutron decay for neutrino transport in CCSNe. All of these reactions were previously neglected in CCSN-simulations. We derive and compute the matrix element and subsequent semi-analytic expressions for transport properties like the inverse mean free path of the new reactions. It is found that these reactions are important for muon neutrinos and low energy electron antineutrinos at very high densities in the protoneutron star surface. Consequently their implementation might lead to several changes in the prediction of CCSNe signatures such as the nucleosynthesis yields. Second we improve the precision in the computation of well known neutrino-nucleon reactions like neutrino absorption on neutrons. We derive semi-analytic expressions for transport properties that use less restrictive approximations while keeping the computational demand constant. Therefore we consider the full relativistic kinematics of all participating particles i.e. allowing for relativistic nucleons and finite lepton masses. Also the weak magnetism terms of the matrix elements are explicitly included to all orders. From our results we suggest that the

  4. Soft particles at a fluid interface

    Science.gov (United States)

    Mehrabian, Hadi; Harting, Jens; Snoeijer, Jacco H.

    2015-11-01

    Particles added to a fluid interface can be used as a surface stabilizer in the food, oil and cosmetic industries. As an alternative to rigid particles, it is promising to consider highly deformable particles that can adapt their conformation at the interface. In this study, we compute the shapes of soft elastic particles using molecular dynamics simulations of a cross-linked polymer gel, complemented by continuum calculations based on the linear elasticity. It is shown that the particle shape is not only affected by the Young's modulus of the particle, but also strongly depends on whether the gel is partially or completely wetting the fluid interface. We find that the molecular simulations for the partially wetting case are very accurately described by the continuum theory. By contrast, when the gel is completely wetting the fluid interface the linear theory breaks down and we reveal that molecular details have a strong influence on the equilibrium shape.

  5. Dense-gas dispersion advection-diffusion model

    International Nuclear Information System (INIS)

    Ermak, D.L.

    1992-07-01

    A dense-gas version of the ADPIC particle-in-cell, advection- diffusion model was developed to simulate the atmospheric dispersion of denser-than-air releases. In developing the model, it was assumed that the dense-gas effects could be described in terms of the vertically-averaged thermodynamic properties and the local height of the cloud. The dense-gas effects were treated as a perturbation to the ambient thermodynamic properties (density and temperature), ground level heat flux, turbulence level (diffusivity), and windfield (gravity flow) within the local region of the dense-gas cloud. These perturbations were calculated from conservation of energy and conservation of momentum principles along with the ideal gas law equation of state for a mixture of gases. ADPIC, which is generally run in conjunction with a mass-conserving wind flow model to provide the advection field, contains all the dense-gas modifications within it. This feature provides the versatility of coupling the new dense-gas ADPIC with alternative wind flow models. The new dense-gas ADPIC has been used to simulate the atmospheric dispersion of ground-level, colder-than-ambient, denser-than-air releases and has compared favorably with the results of field-scale experiments

  6. Finding Hierarchical and Overlapping Dense Subgraphs using Nucleus Decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Seshadhri, Comandur [The Ohio State Univ., Columbus, OH (United States); Pinar, Ali [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sariyuce, Ahmet Erdem [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Catalyurek, Umit [The Ohio State Univ., Columbus, OH (United States)

    2014-11-01

    Finding dense substructures in a graph is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasiclique, k-densest subgraph) are NP-hard. Furthermore, the goal is rarely to nd the \\true optimum", but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine a hierarchical structure among them. Current dense subgraph nding algorithms usually optimize some objective, and only nd a few such subgraphs without providing any hierarchy. It is also not clear how to account for overlaps in dense substructures. We de ne the nucleus decomposition of a graph, which represents the graph as a forest of nuclei. Each nucleus is a subgraph where smaller cliques are present in many larger cliques. The forest of nuclei is a hierarchy by containment, where the edge density increases as we proceed towards leaf nuclei. Sibling nuclei can have limited intersections, which allows for discovery of overlapping dense subgraphs. With the right parameters, the nuclear decomposition generalizes the classic notions of k-cores and k-trusses. We give provable e cient algorithms for nuclear decompositions, and empirically evaluate their behavior in a variety of real graphs. The tree of nuclei consistently gives a global, hierarchical snapshot of dense substructures, and outputs dense subgraphs of higher quality than other state-of-theart solutions. Our algorithm can process graphs with tens of millions of edges in less than an hour.

  7. Relativistic nuclear fluid dynamics and VUU kinetic theory

    International Nuclear Information System (INIS)

    Molitoris, J.J.; Hahn, D.; Alonso, C.; Collazo, I.; D'Alessandris, P.; McAbee, T.; Wilson, J.; Zingman, J.

    1987-01-01

    Relativistic kinetic theory may be used to understand hot dense hadronic matter. We address the questions of collective flow and pion production in a 3 D relativistic fluid dynamic model and in the VUU microscopic theory. The GSI/LBL collective flow and pion data point to a stiff equation of state. The effect of the nuclear equation of state on the thermodynamic parameters is discussed. The properties of dense hot hadronic matter are studied in Au + Au collisions from 0.1 to 10 GeV/nucleon. 22 refs., 5 figs

  8. Electronic transport coefficients from ab initio simulations and application to dense liquid hydrogen

    International Nuclear Information System (INIS)

    Holst, Bastian; French, Martin; Redmer, Ronald

    2011-01-01

    Using Kubo's linear response theory, we derive expressions for the frequency-dependent electrical conductivity (Kubo-Greenwood formula), thermopower, and thermal conductivity in a strongly correlated electron system. These are evaluated within ab initio molecular dynamics simulations in order to study the thermoelectric transport coefficients in dense liquid hydrogen, especially near the nonmetal-to-metal transition region. We also observe significant deviations from the widely used Wiedemann-Franz law, which is strictly valid only for degenerate systems, and give an estimate for its valid scope of application toward lower densities.

  9. Stark broadening of isolated lines from high-Z emitters in dense plasmas

    International Nuclear Information System (INIS)

    Weisheit, J.C.; Pollock, E.L.

    1980-09-01

    The joint distribution of the electric microfield and its longitudinal derivative is required for the calculation of line profiles for the He-like ions in very dense plasmas. We used a molecular dynamics code to compute exact distributions in single- and multi-component plasmas, and then we investigated various analytical approximations to these results. We found that a simplified, two-nearest-neighbor scheme leads to surprisingly accurate distribution functions. Our results are illustrated by sample profiles for Ne +8 and Ar +16 resonance lines

  10. Dense interstellar cloud chemistry: Basic issues and possible dynamical solution

    International Nuclear Information System (INIS)

    Prasad, S.S.; Heere, K.R.; Tarafdar, S.P.

    1989-01-01

    Standing at crossroad of enthusiasm and frustration, dense intertellar cloud chemistry has a squarely posed fundamental problem: Why do the grains appear to play at best a minor role in the chemistry? Grain surface chemistry creates considerable difficulties when the authors treat dense clouds as static objects and ignore the implications of the processes by which the clouds became dense in the first place. A new generation of models which treat chemical and dynamical evolutions concurrently are therefore presented as possible solution to the current frustrations. The proposed modeling philosophy and agenda could make the next decade quite exciting for interstellar chemistry

  11. Dense time discretization technique for verification of real time systems

    International Nuclear Information System (INIS)

    Makackas, Dalius; Miseviciene, Regina

    2016-01-01

    Verifying the real-time system there are two different models to control the time: discrete and dense time based models. This paper argues a novel verification technique, which calculates discrete time intervals from dense time in order to create all the system states that can be reached from the initial system state. The technique is designed for real-time systems specified by a piece-linear aggregate approach. Key words: real-time system, dense time, verification, model checking, piece-linear aggregate

  12. Photons in dense nuclear matter: Random-phase approximation

    Science.gov (United States)

    Stetina, Stephan; Rrapaj, Ermal; Reddy, Sanjay

    2018-04-01

    We present a comprehensive and pedagogic discussion of the properties of photons in cold and dense nuclear matter based on the resummed one-loop photon self-energy. Correlations among electrons, muons, protons, and neutrons in β equilibrium that arise as a result of electromagnetic and strong interactions are consistently taken into account within the random phase approximation. Screening effects, damping, and collective excitations are systematically studied in a fully relativistic setup. Our study is relevant to the linear response theory of dense nuclear matter, calculations of transport properties of cold dense matter, and investigations of the production and propagation of hypothetical vector bosons such as the dark photons.

  13. Connection Between Thermodynamics and Dynamics of Simple Fluids in Pores: Impact of Fluid-Fluid Interaction Range and Fluid-Solid Interaction Strength.

    Science.gov (United States)

    Krekelberg, William P; Siderius, Daniel W; Shen, Vincent K; Truskett, Thomas M; Errington, Jeffrey R

    2017-08-03

    Using molecular simulations, we investigate how the range of fluid-fluid (adsorbate-adsorbate) interactions and the strength of fluid-solid (adsorbate-adsorbent) interactions impact the strong connection between distinct adsorptive regimes and distinct self-diffusivity regimes reported in [Krekelberg, W. P.; Siderius, D. W.; Shen, V. K.; Truskett, T. M.; Errington, J. R. Langmuir 2013 , 29 , 14527-14535]. Although increasing the fluid-fluid interaction range changes both the thermodynamics and the dynamic properties of adsorbed fluids, the previously reported connection between adsorptive filling regimes and self-diffusivity regimes remains. Increasing the fluid-fluid interaction range leads to enhanced layering and decreased self-diffusivity in the multilayer-formation regime but has little effect on the properties within film-formation and pore-filling regimes. We also find that weakly attractive adsorbents, which do not display distinct multilayer formation, are hard-sphere-like at super- and subcritical temperatures. In this case, the self-diffusivity of the confined and bulk fluid has a nearly identical scaling-relationship with effective density.

  14. Reduced abrasion drilling fluid

    NARCIS (Netherlands)

    2010-01-01

    A reduced abrasion drilling fluid system and method of drilling a borehole by circulating the reduced abrasion drilling fluid through the borehole is disclosed. The reduced abrasion drilling fluid comprises a drilling fluid, a first additive and a weighting agent, wherein the weighting agent has a

  15. Reduced abrasion drilling fluid

    NARCIS (Netherlands)

    2012-01-01

    A reduced abrasion drilling fluid system and method of drilling a borehole by circulating the reduced abrasion drilling fluid through the borehole is disclosed. The reduced abrasion drilling fluid comprises a drilling fluid, a first additive and a weighting agent, wherein the weighting agent has a

  16. Process fluid cooling system

    International Nuclear Information System (INIS)

    Farquhar, N.G.; Schwab, J.A.

    1977-01-01

    A system of heat exchangers is disclosed for cooling process fluids. The system is particularly applicable to cooling steam generator blowdown fluid in a nuclear plant prior to chemical purification of the fluid in which it minimizes the potential of boiling of the plant cooling water which cools the blowdown fluid

  17. Dense breasts: a review of reporting legislation and available supplemental screening options.

    Science.gov (United States)

    Ho, Jessica M; Jafferjee, Nasima; Covarrubias, Gabriel M; Ghesani, Munir; Handler, Bradley

    2014-08-01

    The objectives of this article are to discuss the Mammography Quality Standards Act (MQSA) and what it means for patients, define breast density and explain how it is measured, review the new state-based legislation regarding the reporting of dense breast tissue directly to patients and the possibility of an adjunct screening examination, describe possible supplemental screening options and the advantages and disadvantages of each, and outline the current shortcomings and unanswered questions regarding new legislation. Breast density is now established as an independent risk factor for developing breast cancer irrespective of other known risk factors. Women with breast density in the upper quartile have an associated four to five times greater risk of developing breast cancer relative to women with breast density in the lower quartile. Many states have enacted or proposed legislation requiring mammographers to report to patients directly if they have dense breast tissue and recommend discussing the possibility of a supplemental screening examination with their physicians. However, there is currently no consensus as to whether a supplemental screening examination should be pursued or which modality to use. Possible supplemental screening modalities include ultrasound, MRI, digital breast tomosynthesis, and molecular breast imaging. The U.S. Food and Drug Administration recently approved an automated breast ultrasound system for screening whole-breast ultrasound in patients with dense breasts. However, many questions are still unanswered including the impact on morbidity and mortality, cost-effectiveness, and insurance coverage.

  18. Dual-affinity peptides to generate dense surface coverages of nanoparticles

    International Nuclear Information System (INIS)

    Del Re, Julia; Blum, Amy Szuchmacher

    2014-01-01

    Graphical abstract: - Highlights: • Stable nanoparticles were created with the Flg-A3 fusion peptide as a ligand. • Interactions of transition metal ions with Flg control aggregation of the nanoparticles in solution. • The QBP1-A3 fusion peptide improves surface attachment of gold nanoparticles. • Solution pre-aggregation of nanoparticles results in dense surface coverage. - Abstract: Depositing gold nanoparticles is of great interest because of the many potential applications of nanoparticle films; however, generating dense surface nanoparticle coverage remains a difficult challenge. Using dual-affinity peptides we have synthesized gold nanoparticles and then pre-aggregated the particles in solution via interactions with metal ions. These nanoparticle aggregates were then deposited onto silicon dioxide surfaces using another dual-affinity peptide to control binding to the substrate. The results demonstrate that when divalent ions like Zn 2+ or Ni 2+ are used, densely packed gold nanoparticle monolayers are formed on the silicon dioxide substrate, which may have applications in fields like molecular electronics

  19. Anomalous optical emission in hot dense oxygen

    Science.gov (United States)

    Santoro, Mario; Gregoryanz, Eugene; Mao, Ho-kwang; Hemley, Russell J.

    2007-11-01

    We report the observation of unusually strong, broad-band optical emission peaked between 590 and 650 nm when solid and fluid oxygen are heated by a near infrared laser at pressures from 3 to 46 GPa. In situ Raman spectra of oxygen were collected and corresponding temperatures were measured from the Stokes/anti-Stokes intensity ratios of vibrational transitions. The intense optical emission overwhelmed the Raman spectrum at temperatures exceeding 750 K. The spectrum was found to be much narrower than Planck-type thermal emission, and the intensity increase with input power was much steeper than expected for the thermal emission. The result places an important general caveat on calculating temperatures based on optical emission spectra in high-pressure laser-heating experiments. The intense emission in oxygen is photo-induced rather than being purely thermal, through multiphoton or multi-step single photon absorption processes related to the interaction with infrared radiation. The results suggest that short lived ionic species are induced by this laser-matter interaction.

  20. RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

    Directory of Open Access Journals (Sweden)

    W. Silva

    Full Text Available ABSTRACT This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50ºC. Meanwhile, flow rates of feed wine and supercritical CO2 varied from 0.1 to 0.5 mL min-1 and from 60 to 80 mL min-1 (NCPT, respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35ºC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE per 100 g of extract.