RISM theory distribution functions for Lennard--Jones interaction site fluids

International Nuclear Information System (INIS)

Johnson, E.; Hazoume, R.P.

1978-01-01

Reference interaction site model (RISM) theory distribution functions for Lennard-Jones interaction site fluids are discussed. The comparison with computer simulation results suggests that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids

Analytic Debye-Grüneisen equation of state for a generalized Lennard-Jones solids

Institute of Scientific and Technical Information of China (English)

孙久勋; 吴强; 蔡灵仓; 经福谦

2003-01-01

The approximate method to treat the practical quantum anharmonic solids proposed by Hardy,Lacks and Shukla is reformulated with explicit physical meanings.It is shown that the quantum effect is important at low temperature,it can be treated in the harmonic framework; and the anharmonic effect is important at high temperature and tends to zero at low temperature,it can be treated by using a classical approximation.The alternative formulation is easier for various applications,and is applied to a Debye-Gruneisen solid with the generalized Lennard-Jones intermolecular interaction.The expressions for the Debye temperature and Gruneisen parameter as a function of volume are analytically derived.The analytic equation of state is applied to predict the thermodynamic properties of solid xenon at normal-pressure with the nearest-neighbour Lennard-Jones interaction,and is further applied to research the properties of solid xenon and krypton at high pressure by using an all-neighbour Lennard-Jones interaction.The theoretical results are in agreement with the experiments.

Binding energy of large icosahedral and cuboctahedral Lennard-Jones clusters

International Nuclear Information System (INIS)

Northby, J.A.; Xie, J.

1989-01-01

It is widely believed that the lowest energy configurations for small rare gas clusters have icosahedral symmetry. This contrasts with the bulk crystal structures which have cuboctahedral fcc symmetry. It is of interest to understand the transition between this finite and bulk behavior. To model this transition in rare gas clusters we have undertaken optimization studies within the Lennard-Jones pair potential model. Using a combination of Monte Carlo and Partan Search optimization methods, the lowest energy relaxed structures of Lennard-Jones clusters having icosahedral and cuboctahedral symmetry were found. Studies were performed for complete shell clusters ranging in size from one shell having 13 atoms to 14 shells having 10,179 atoms. It was found that the icosahedral structures are lower in energy than the cuboctahedral structures for cluster sizes having 13 shells or fewer. Additional studies were performed using the more accurate Aziz-Chen [HFD-C] pair potential parameterized for argon. The conclusions appear to be relatively insensitive to the form of the potential. (orig.)

Localized fluidity modes and the topology of the constant-potential-energy hypersurfaces of Lennard-Jones matter

DEFF Research Database (Denmark)

Cotterill, Rodney M J; Madsen, J.

1986-01-01

Sections of configuration space for Lennard-Jones matter were obtained by probing all the normal-mode energy profiles, following diagonalization of the dynamical matrix for a 240-particle system. For the crystal and sufficiently cold glass, these are single welled, whereas increasing numbers...... of double wells occur as the glass is warmed toward the fluid. This indicates that there might be a fundamental difference between the topologies of the constant-potential-energy hypersurfaces of crystalline and noncrystalline Lennard-Jones matter....

Collision kernels in the eikonal approximation for Lennard-Jones interaction potential

International Nuclear Information System (INIS)

Zielinska, S.

1985-03-01

The velocity changing collisions are conveniently described by collisional kernels. These kernels depend on an interaction potential and there is a necessity for evaluating them for realistic interatomic potentials. Using the collision kernels, we are able to investigate the redistribution of atomic population's caused by the laser light and velocity changing collisions. In this paper we present the method of evaluating the collision kernels in the eikonal approximation. We discuss the influence of the potential parameters Rsub(o)sup(i), epsilonsub(o)sup(i) on kernel width for a given atomic state. It turns out that unlike the collision kernel for the hard sphere model of scattering the Lennard-Jones kernel is not so sensitive to changes of Rsub(o)sup(i) as the previous one. Contrary to the general tendency of approximating collisional kernels by the Gaussian curve, kernels for the Lennard-Jones potential do not exhibit such a behaviour. (author)

A density functional perturbative approach for simple fluids: the structure of a nonuniform Lennard-Jones fluid at interfaces

International Nuclear Information System (INIS)

Kim, Soon-Chul; Lee, Song Hi

2004-01-01

A density functional perturbation approximation (DFPT), which is based both on the fundamental-measure theory (FMT) to the hard-sphere repulsion and on the weighted-density approximations (WDAs) to the attractive contribution, has been proposed for studying the structural properties of model fluids with an attractive part of the potential. The advantage of the present theory is the simplicity of the calculation of the weight function due to the attractive contribution. It has been applied to predict the equilibrium particle density distributions and adsorption isotherms of Lennard-Jones fluids at interfaces. The theoretical results show that the present theory describes quite well the adsorption isotherms of a Lennard-Jones ethane in a graphite slit pore as well as the equilibrium particle density distributions of a Lennard-Jones fluid near a planar slit pore

Icosahedral binary clusters of glass-forming Lennard-Jones binary alloy

International Nuclear Information System (INIS)

Iwamatsu, Masao

2007-01-01

It is widely believed that the local icosahedral structure is related to the formation of bulk metallic glasses (BMGs). Specifically the existence of 13-atom icosahedral cluster in undercooled liquid is imagined to play a key role to initiate the glass formation as the seed of amorphous structure or to block the nucleation of regular crystal as the impurity. The existence of 13-atom icosahedral clusters in one-component liquids was predicted more than half a century ago by Frank from his total energy calculation for isolated clusters. In BMG alloys, however, the situation is less clear. In this report, we present the lowest-energy structures of 13-atom Lennard-Jones binary cluster calculated from the modified space-fixed genetic algorithm. We study, in particular, the artificial Lennard-Jones potential designed by Kob and Andersen [W. Kob, H.C. Andersen, Phys. Rev. E 51 (1995) 4626] that is known to form BMG. Curiously, the lowest-energy structures of 13-atom cluster are non-icosahedral for almost all compositions. Our result suggests that the existence of the icosahedral cluster is not a necessary condition but only a sufficient condition for glass formation

An accurate expression for radial distribution function of the Lennard-Jones fluid

International Nuclear Information System (INIS)

Morsali, Ali; Goharshadi, Elaheh K.; Ali Mansoori, G.; Abbaspour, Mohsen

2005-01-01

A simple and accurate expression for radial distribution function (RDF) of the Lennard-Jones fluid is presented. The expression explicitly states the RDF as a continuous function of reduced interparticle distance, temperature, and density. It satisfies the limiting conditions of zero density and infinite distance imposed by statistical thermodynamics. The distance dependence of this expression is expressed by an equation which contains 11 adjustable parameters. These parameters are fitted to 353 RDF data, obtained by molecular dynamics calculations, and then expressed as functions of reduced distance, temperature and density. This expression, having a total of 65 constants, reproduces the RDF data with an average root-mean-squared deviation of 0.0152 for the range of state variables of 0.5= * = * = * =ρσ 3 are reduced temperature and density, respectively). The expression predicts the pressure and the internal energy of the Lennard-Jones fluid with an uncertainty that is comparable to that obtained directly from the molecular dynamics simulations

Fluctuations and thermodynamic response functions in a Lennard-Jones solid

International Nuclear Information System (INIS)

Li, M.; Johnson, W.L.

1992-01-01

Thermodynamic response functions of a nearest-neighbor Lennard-Jones solid--heat capacity, thermal-expansion coefficient, compressibility, and elastic constants--are calculated directly from fluctuations using molecular-dynamics simulations. The algorithm used is the earlier Parrinello-Rahman molecular dynamics modified to take into account symmetry and rotation invariance of the system under investigation. The convergence is very fast and results are in good agreement with existing Monte Carlo and molecular-dynamics results

Phase Diagram of Kob-Andersen-Type Binary Lennard-Jones Mixtures

Science.gov (United States)

Pedersen, Ulf R.; Schrøder, Thomas B.; Dyre, Jeppe C.

2018-04-01

The binary Kob-Andersen (KA) Lennard-Jones mixture is the standard model for computational studies of viscous liquids and the glass transition. For very long simulations, the viscous KA system crystallizes, however, by phase separating into a pure A particle phase forming a fcc crystal. We present the thermodynamic phase diagram for KA-type mixtures consisting of up to 50% small (B ) particles showing, in particular, that the melting temperature of the standard KA system at liquid density 1.2 is 1.028(3) in A particle Lennard-Jones units. At large B particle concentrations, the system crystallizes into the CsCl crystal structure. The eutectic corresponding to the fcc and CsCl structures is cutoff in a narrow interval of B particle concentrations around 26% at which the bipyramidal orthorhombic PuBr3 structure is the thermodynamically stable phase. The melting temperature's variation with B particle concentration at two constant pressures, as well as at the constant density 1.2, is estimated from simulations at pressure 10.19 using isomorph theory. Our data demonstrate approximate identity between the melting temperature and the onset temperature below which viscous dynamics appears. Finally, the nature of the solid-liquid interface is briefly discussed.

Ab initio study of the atomic motion in liquid metal surfaces: comparison with Lennard-Jones systems

International Nuclear Information System (INIS)

Gonzalez, Luis E; Gonzalez, David J

2006-01-01

It is established that liquid metals exhibit surface layering at the liquid-vapour interface, while dielectric simple systems, like those interacting through Lennard-Jones potentials, show a monotonic decay from the liquid density to that of the vapour. First principles molecular dynamics simulations of the free liquid surface of several liquid metals (Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl and Si), and the Na 3 K 7 alloy near their triple points have been performed in order to study the atomic motion at the interface, mainly at the outer layer. Comparison with the results of classical molecular dynamics simulations of a Lennard-Jones system shows interesting differences and similarities. The probability distribution function of the time of residence in a layer shows a peak at very short times and a long-lasting tail. The mean residence time in a layer increases when approaching the interfacial region, slightly in the Lennard-Jones system but strongly in the metallic systems. The motion within the layers, parallel to the interface, can be described as diffusion enhanced (strongly in the case of the outermost layer) with respect to the bulk, for both types of systems, despite its reduced dimensionality in metals

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.

Radiation damage in an amorphous Lennard-Jones solid

International Nuclear Information System (INIS)

Chaki, T.K.; Li, J.C.M.

1985-01-01

A molecular-dynamics simulation of radiation damage in an amorphous Lennard-Jones solid has been undertaken. A three-dimensional structure of 685 atoms with periodic boundary conditions was used. An atom was injected inward from the middle of one surface, and as it lost its energy its velocity and position were recorded. The temperature profile around the injection direction was also calculated. The amorphous structure was examined before and after irradiation by calculating the volume distribution of the Voronoi polyhedra and its time evolution. The production of vacancies and interstitials was observed. The interstitials were found to disappear rapidly, and the vacancies slowly. (author)

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

Vapour-liquid equilibrium properties for two- and three-dimensional Lennard-Jones fluids from equations of state

International Nuclear Information System (INIS)

Mulero, A.; Cuadros, F; Faundez, C.A.

1999-01-01

Vapour-liquid equilibrium properties for both three- and two-dimensional Lennard-Jones fluids were obtained using simple cubic-in-density equations of state proposed by the authors. Results were compared with those obtained by other workers from computer simulations and also with results given by other more complex semi-theoretical or semi-empirical equations of state. In the three-dimensional case good agreement is found for all properties and all temperatures. In the two-dimensional case only the coexistence densities were compared, producing good agreement for low temperatures only. The present work is the first to give numerical data for the vapour-liquid equilibrium properties of Lennard-Jones fluids calculated from equations of state. Copyright (1999) CSIRO Australia

Water in the presence of inert Lennard-Jones obstacles

Science.gov (United States)

Kurtjak, Mario; Urbic, Tomaz

2014-04-01

Water confined by the presence of a 'sea' of inert obstacles was examined. In the article, freely mobile two-dimensional Mercedes-Benz (MB) water put to a disordered, but fixed, matrix of Lennard-Jones disks was studied by the Monte Carlo computer simulations. For the MB water molecules in the matrix of Lennard-Jones disks, we explored the structures, hydrogen-bond-network formation and thermodynamics as a function of temperature and size and density of matrix particles. We found that the structure of model water is perturbed by the presence of the obstacles. Density of confined water, which was in equilibrium with the bulk water, was smaller than the density of the bulk water and the temperature dependence of the density of absorbed water did not show the density anomaly in the studied temperature range. The behaviour observed as a consequence of confinement is similar to that of increasing temperature, which can for a matrix lead to a process similar to capillary evaporation. At the same occupancy of space, smaller matrix molecules cause higher destruction effect on the absorbed water molecules than the bigger ones. We have also tested the hypothesis that at low matrix densities the obstacles induce an increased ordering and 'hydrogen bonding' of the MB model molecules, relative to pure fluid, while at high densities the obstacles reduce MB water structuring, as they prevent the fluid to form good 'hydrogen-bonding' networks. However, for the size of matrix molecules similar to that of water, we did not observe this effect.

Self-diffusion coefficients of the metastable Lennard-Jones vapor

International Nuclear Information System (INIS)

Nie Chu; Zhou Youhua; Marlow, W H; Hassan, Y A

2008-01-01

Self-diffusion coefficients of a metastable Lennard-Jones vapor were obtained using the memory function formalism and the frequency moments of the velocity autocorrelation function at reduced temperatures from 0.75 to 1.0. The radial density distribution functions used to evaluate the second, fourth and sixth frequency moments of the velocity autocorrelation function were obtained from the restricted canonical ensemble Monte Carlo simulation (Corti and Debenedetti 1994 Chem. Eng. Sci. 49 2717). The self-diffusion coefficients at reduced temperature 0.75 do not vary monotonically as the density increases, and for the other three temperatures the self-diffusion coefficients vary normally

Melting of 2D monatomic solids: Lennard-Jones system

International Nuclear Information System (INIS)

Yi, Y.M.; Guo, Z.C.

1987-09-01

The Lennard-Jones interaction has been introduced into the Collins mix lattice of 2D liquids. By means of rigorous calculation of the total potential and the free area, the Gibbs functions for 2D liquid and solid have been derived. The melting line obtained from the phase transition equation agrees quite well with the result of recent computer simulation experiments. The obtained reduced temperature of the triple point T* t =0.438 agrees with the data measured in experiments of some inert gas monolayers adsorbed on graphite as well as in computer simulation experiments. (author). 11 refs, 7 figs, 3 tabs

Self-diffusion coefficients of the metastable Lennard-Jones vapor

Energy Technology Data Exchange (ETDEWEB)

Nie Chu; Zhou Youhua [School of Physics and Information Engineering, Jianghan University, Wuhan 430056 (China); Marlow, W H; Hassan, Y A [Department of Nuclear Engineering, Texas A and M University, College Station, TX 77843 (United States)], E-mail: yhzhou@jhun.edu.cn

2008-10-15

Self-diffusion coefficients of a metastable Lennard-Jones vapor were obtained using the memory function formalism and the frequency moments of the velocity autocorrelation function at reduced temperatures from 0.75 to 1.0. The radial density distribution functions used to evaluate the second, fourth and sixth frequency moments of the velocity autocorrelation function were obtained from the restricted canonical ensemble Monte Carlo simulation (Corti and Debenedetti 1994 Chem. Eng. Sci. 49 2717). The self-diffusion coefficients at reduced temperature 0.75 do not vary monotonically as the density increases, and for the other three temperatures the self-diffusion coefficients vary normally.

Threshold and Lennard-Jones resonances and elastic lifetimes in the scattering of atoms from crystalline surfaces

International Nuclear Information System (INIS)

Garcia, N.

1978-01-01

The GR method for solving the scattering equations of atoms from a hard corrugated surface is applied on accelerated particles above a hard corrugated surface and a hard corrugated surface with an attractive well. The solutions are given for the Rayleigh hypothesis that under the range of corrugation presented in this paper leads to the exact ones. Threshold resonances are studied observing that the appearance and disappearance of beams must be for a general theory with vertical tangent. The structure of the Lennard-Jones resonances given for the model mentioned above. For the first time it is stressed that Lennard-Jones resonances are not observed in metal surfaces in general, and, accordingly, they are unobserved in compact metallic surfaces. This is correlated with the fact that diffraction has not been observed. Both facts are due to the very weak corrugation of the gas-metal interaction potential. According to our results, the Lennard-Jones resonances in metals present greater difficulties to be observed experimentally. It is also noted that the absence of diffraction in compact metal surfaces is because they are almost plane and not because of the Debye-Waller effect. Finally, the lifetimes of the atoms at the crystal surfaces are calculated. These are larger, the smaller the incident energy and the larger the corrugation. But the lifetimes are particularly large at resonance conditions (10 -11 s). (Auth.)

Simulasi Sifat Fisis Model Molekuler Dinamik Gas Argon dengan Potensial Lennard-Jones

Directory of Open Access Journals (Sweden)

Wira Bahari Nurdin

2014-01-01

Full Text Available DOWNLOAD PDFTelah  dilakukan  pembuatan  dan  pengujian  suatu  simulasi  tentang  sifat  fisis  gasargon  dengan  menggunakan  dinamika  molekuler  menggunakan  potensial Lennard-Jonesdalam sistem terisolasi (ensemble mikrokanonik. Jumlah molekul, energi total sistem danluas  kotak  simulasi  telah  divariasikan.  Untuk  menghitung  perubahan  posisi  digunakanalgoritma Verlet. Sifat fisis yang ditentukan dalam simulasi adalah temperatur dan energitotal  sistem  untuk  menentukan  adanya  fase  transisi.  Dari  hasil  simulasi,  terdapatkesesuaian antara simulasi dengan gas argon dan tidak diperoleh adanya fase transisi.Kata kunci: Simulasi dinamika molekul, argon, potensial Lennard-Jones, ensemblemikrokanonik, algoritma Verlet

Effect of Energy Polydispersity on the Nature of Lennard-Jones Liquids

OpenAIRE

Ingebrigtsen, Trond S.; Tanaka, Hajime

2016-01-01

In the companion paper [T. S. Ingebrigtsen and H. Tanaka, J. Phys. Chem. B 119, 11052 (2015)] the effect of size polydispersity on the nature of Lennard-Jones (LJ) liquids, which represent most molecular liquids without hydrogen bonds, was studied. More specifically, it was shown that even highly size polydisperse LJ liquids are Roskilde-simple (RS) liquids. RS liquids are liquids with strong correlation between constant volume equilibrium fluctuations of virial and potential energy and are s...

Numerical simulation of pool boiling of a Lennard-Jones liquid

KAUST Repository

Inaoka, Hajime; Ito, Nobuyasu

2013-01-01

We performed a numerical simulation of pool boiling by a molecular dynamics model. In the simulation, a liquid composed of Lennard-Jones particles in a uniform gravitational field is heated by a heat source at the bottom of the system. The model successfully reproduces the change in regimes of boiling from nucleate boiling to film boiling with the increase of the heat source temperature. We present the pool boiling curve by the model, whose general behavior is consistent with those observed in experiments of pool boiling. © 2013 Elsevier B.V. All rights reserved.

Numerical simulation of pool boiling of a Lennard-Jones liquid

KAUST Repository

Inaoka, Hajime

2013-09-01

We performed a numerical simulation of pool boiling by a molecular dynamics model. In the simulation, a liquid composed of Lennard-Jones particles in a uniform gravitational field is heated by a heat source at the bottom of the system. The model successfully reproduces the change in regimes of boiling from nucleate boiling to film boiling with the increase of the heat source temperature. We present the pool boiling curve by the model, whose general behavior is consistent with those observed in experiments of pool boiling. © 2013 Elsevier B.V. All rights reserved.

Formation of global energy minimim structures in the growth process of Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Koshelev, Andrey; Shutovich, Andrey

2003-01-01

that in this way all known global minimum structures of the Lennard-Jones (LJ) clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic numbers sequence for the clusters of noble gases atoms and compare...

Cell-model prediction of the melting of a Lennard-Jones solid

International Nuclear Information System (INIS)

Holian, B.L.

1980-01-01

The classical free energy of the Lennard-Jones 6-12 solid is computed from a single-particle anharmonic cell model with a correction to the entropy given by the classical correlational entropy of quasiharmonic lattice dynamics. The free energy of the fluid is obtained from the Hansen-Ree analytic fit to Monte Carlo equation-of-state calculations. The resulting predictions of the solid-fluid coexistence curves by this corrected cell model of the solid are in excellent agreement with the computer experiments

Molecular dynamics studies of the dynamics of supercooled Lennard-Jones liquids

International Nuclear Information System (INIS)

De Leeuw, S.W.; Brakkee, M.J.D.

1990-01-01

Results are presented of molecular dynamics experiments, in which the Lennard-Jones liquid is cooled isobarically into the metastable temperature region below the freezing temperature. The variation of the density-density and transverse current correlation functions with temperature is studied. We observed a power-law behaviour for the temperature dependence of dynamical properties (viscosity and coefficienty of self-diffusion) with an exponent in good agreement with prediction of mode coupling theories and recent experimental results. (author). 23 refs, 5 figs

Viscous Growth in Spinodal Decomposition of the Two-component Lennard-Jones Model in Two Dimensions

DEFF Research Database (Denmark)

Laradji, M.; Toxvaerd, S.; Mouritsen, Ole G.

1997-01-01

The dynamics of phase separation of a two-component Lennard-Jones model in three dimensions is investigated by means of large scale molecular dynamics simulation. A systematic study over a wide range of quench temperatures within the coexistence region shows that the binary system reaches...

Glass transitions in one-, two-, three-, and four-dimensional binary Lennard-Jones systems

Energy Technology Data Exchange (ETDEWEB)

Bruening, Ralf; St-Onge, Denis A; Patterson, Steve [Physics Department, Mount Allison University, Sackville, NB, E4L 1E6 (Canada); Kob, Walter [Laboratoire des Colloides, Verres et Nanomateriaux, UMR5587, Universite Montpellier II and CNRS, 34095 Montpellier Cedex (France)], E-mail: rbruening@mta.ca

2009-01-21

We investigate the calorimetric liquid-glass transition by performing simulations of a binary Lennard-Jones mixture in one through four dimensions. Starting at a high temperature, the systems are cooled to T = 0 and heated back to the ergodic liquid state at constant rates. Glass transitions are observed in two, three and four dimensions as a hysteresis between the cooling and heating curves. This hysteresis appears in the energy and pressure diagrams, and the scanning rate dependence of the area and height of the hysteresis can be described using power laws. The one-dimensional system does not experience a glass transition but its specific heat curve resembles the shape of the D{>=}2 results in the supercooled liquid regime above the glass transition. As D increases, the radial distribution functions reflect reduced geometric constraints. Nearest neighbor distances become smaller with increasing D due to interactions between nearest and next-nearest neighbors. Simulation data for the glasses are compared with crystal and melting data obtained with a Lennard-Jones system with only one type of particle and we find that with increasing D crystallization becomes increasingly more difficult.

Disordering scaling and generalized nearest-neighbor approach in the thermodynamics of Lennard-Jones systems

International Nuclear Information System (INIS)

Vorob'ev, V.S.

2003-01-01

We suggest a concept of multiple disordering scaling of the crystalline state. Such a scaling procedure applied to a crystal leads to the liquid and (in low density limit) gas states. This approach provides an explanation to a high value of configuration (common) entropy of liquefied noble gases, which can be deduced from experimental data. We use the generalized nearest-neighbor approach to calculate free energy and pressure of the Lennard-Jones systems after performing this scaling procedure. These thermodynamic functions depend on one parameter characterizing the disordering only. Condensed states of the system (liquid and solid) correspond to small values of this parameter. When this parameter tends to unity, we get an asymptotically exact equation of state for a gas involving the second virial coefficient. A reasonable choice of the values for the disordering parameter (ranging between zero and unity) allows us to find the lines of coexistence between different phase states in the Lennard-Jones systems, which are in a good agreement with the available experimental data

Melting in Two-Dimensional Lennard-Jones Systems: Observation of a Metastable Hexatic Phase

International Nuclear Information System (INIS)

Chen, K.; Kaplan, T.; Mostoller, M.

1995-01-01

Large scale molecular dynamics simulations of two-dimensional melting have been carried out using a recently revised Parrinello-Rahman scheme on massively parallel supercomputers. A metastable state is observed between the solid and liquid phases in Lennard-Jones systems of 36 864 and 102 400 atoms. This intermediate state shows the characteristics of the hexatic phase predicted by the theory of Kosterlitz, Thouless, Halperin, Nelson, and Young

Crystal phases of a glass-forming Lennard-Jones mixture

International Nuclear Information System (INIS)

Fernandez, Julian R.; Harrowell, Peter

2003-01-01

We compare the potential energy at zero temperature of a range of crystal structures for a glass-forming binary mixture of Lennard-Jones particles. The lowest-energy ordered state consists of coexisting phases of a single component face centered cubic structure and an equimolar cesium chloride structure. An infinite number of layered crystal structures are identified with energies close to this ground state. We demonstrate that the finite size increase of the energy of the coexisting crystal with incoherent interfaces is sufficient to destabilize this ordered phase in simulations of typical size. Two specific local coordination structures are identified as of possible structural significance in the amorphous state. We observe rapid crystal growth in the equimolar mixture

Third-order WKBJ eigenvalues for Lennard-Jones and Varshni V potentials

International Nuclear Information System (INIS)

Kesarwani, R.N.; Varshni, Y.P.

1978-01-01

The WKBJ method is applied to the third order for obtaining the eigenvalues for the fifth potential of Varshni, and the relevant integrals are analytically evaluated. Numerical results are obtained for the Lennard-Jones Potential, which is a special case of the Varshni V potential, and are compared to the results of Harrison and Bernstein obtained by a numerical integration of the wave equation. Error estimates are made. It is shown that for diatomic potentials, the Langer correction is not needed if the WKBJ approximation is carried to second and higher orders. (author)

Glass of monatomic Lennard-Jones system at nanoscale

International Nuclear Information System (INIS)

Vo Van Hoang

2010-01-01

Structure and stability of glass of monatomic Lennard-Jones (LJ) system at nanoscale compared with those of the bulk counterparts have been studied using the classical molecular dynamics (MD) method. Models have been obtained by cooling from the melts. Structure of the systems was analyzed via radial distribution function (RDF), interatomic distances, the Honeycutt-Andersen analysis and coordination number distributions. Surface and core structures of LJ nanoparticles have been analyzed in details. Density dependence and cooling rate effects on structure of the systems have been found and discussed. In addition, size dependence of structure and properties of nanoparticles has been analyzed in detail. Indeed, we found glass formation in monatomic LJ systems; however, their stability is not high. Evolution of structure and thermodynamics of the systems upon cooling from the melts was found. We also discussed annealing-induced crystallization of LJ glass.

Stability of relaxed Lennard-Jones models made of 500 to 6000 atoms

International Nuclear Information System (INIS)

Raoult, B.; Farges, J.; Feraudy, M.F. de; Torchet, G.

1989-01-01

We present a study of the stability of clusters models made of a number N of atoms in the range 500 to 6000 atoms, freely interacting through the Lennard-Jones potential. The potential energy per atom, calculated for relaxed models, shows that stable models belong to an icosahedral sequence when N<1600 and to a decahedral sequence beyond. A coexistence size range of both structures is discussed in connection with experimental results on argon clusters in free jet expansions. (orig.)

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.

Flory-Huggins parameter χ, from binary mixtures of Lennard-Jones particles to block copolymer melts

International Nuclear Information System (INIS)

Chremos, Alexandros; Nikoubashman, Arash; Panagiotopoulos, Athanassios Z.

2014-01-01

In this contribution, we develop a coarse-graining methodology for mapping specific block copolymer systems to bead-spring particle-based models. We map the constituent Kuhn segments to Lennard-Jones particles, and establish a semi-empirical correlation between the experimentally determined Flory-Huggins parameter χ and the interaction of the model potential. For these purposes, we have performed an extensive set of isobaric–isothermal Monte Carlo simulations of binary mixtures of Lennard-Jones particles with the same size but with asymmetric energetic parameters. The phase behavior of these monomeric mixtures is then extended to chains with finite sizes through theoretical considerations. Such a top-down coarse-graining approach is important from a computational point of view, since many characteristic features of block copolymer systems are on time and length scales which are still inaccessible through fully atomistic simulations. We demonstrate the applicability of our method for generating parameters by reproducing the morphology diagram of a specific diblock copolymer, namely, poly(styrene-b-methyl methacrylate), which has been extensively studied in experiments

Flory-Huggins parameter χ, from binary mixtures of Lennard-Jones particles to block copolymer melts

Energy Technology Data Exchange (ETDEWEB)

Chremos, Alexandros, E-mail: achremos@imperial.ac.uk [Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Nikoubashman, Arash, E-mail: arashn@princeton.edu; Panagiotopoulos, Athanassios Z. [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2014-02-07

In this contribution, we develop a coarse-graining methodology for mapping specific block copolymer systems to bead-spring particle-based models. We map the constituent Kuhn segments to Lennard-Jones particles, and establish a semi-empirical correlation between the experimentally determined Flory-Huggins parameter χ and the interaction of the model potential. For these purposes, we have performed an extensive set of isobaric–isothermal Monte Carlo simulations of binary mixtures of Lennard-Jones particles with the same size but with asymmetric energetic parameters. The phase behavior of these monomeric mixtures is then extended to chains with finite sizes through theoretical considerations. Such a top-down coarse-graining approach is important from a computational point of view, since many characteristic features of block copolymer systems are on time and length scales which are still inaccessible through fully atomistic simulations. We demonstrate the applicability of our method for generating parameters by reproducing the morphology diagram of a specific diblock copolymer, namely, poly(styrene-b-methyl methacrylate), which has been extensively studied in experiments.

Atomic size effect on the formation of ionized cluster beam epitaxy in Lennard-Jones systems

International Nuclear Information System (INIS)

Hsieh Horngming; Averback, R.S.

1991-01-01

Ionized cluster beam deposition is studied by molecular dynamics simulations in which the atomic size of incident cluster atoms is different from the size of substrate atoms. Lennard-Jones interatomic potentials are used for the two-component system. The results provide the morphologies of the overlayers for various atomic sizes and are compared to simulation results of molecular beam epitaxy. (orig.)

The potential energy landscape in the Lennard-Jones binary mixture model

International Nuclear Information System (INIS)

Sampoli, M; Benassi, P; Eramo, R; Angelani, L; Ruocco, G

2003-01-01

The potential energy landscape in the Kob-Andersen Lennard-Jones binary mixture model has been studied carefully from the liquid down to the supercooled regime, from T = 2 down to 0.46. One thousand independent configurations along the time evolution locus have been examined at each temperature investigated. From the starting configuration, we searched for the nearest saddle (or quasi-saddle) and minimum of the potential energy. The vibrational densities of states for the starting and the two derived configurations have been evaluated. Besides the number of negative eigenvalues of the saddles other quantities show some signature of the approach of the dynamical arrest temperature

Phase behavior of the 38-atom Lennard-Jones cluster

International Nuclear Information System (INIS)

Sehgal, Ray M.; Maroudas, Dimitrios; Ford, David M.

2014-01-01

We have developed a coarse-grained description of the phase behavior of the isolated 38-atom Lennard-Jones cluster (LJ 38 ). The model captures both the solid-solid polymorphic transitions at low temperatures and the complex cluster breakup and melting transitions at higher temperatures. For this coarse model development, we employ the manifold learning technique of diffusion mapping. The outcome of the diffusion mapping analysis over a broad temperature range indicates that two order parameters are sufficient to describe the cluster's phase behavior; we have chosen two such appropriate order parameters that are metrics of condensation and overall crystallinity. In this well-justified coarse-variable space, we calculate the cluster's free energy landscape (FEL) as a function of temperature, employing Monte Carlo umbrella sampling. These FELs are used to quantify the phase behavior and onsets of phase transitions of the LJ 38 cluster

Density-scaling exponents and virial potential-energy correlation coefficients for the (2n, n) Lennard-Jones system

DEFF Research Database (Denmark)

Friisberg, Ida Marie; Costigliola, Lorenzo; Dyre, Jeppe C.

2017-01-01

This paper investigates the relation between the density-scaling exponent γ and the virial potentialenergy coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ syste...

Finite-field evaluation of the Lennard-Jones atom-wall interaction constant C3 for alkali-metal atoms

International Nuclear Information System (INIS)

Johnson, W.R.; Dzuba, V.A.; Safronova, U.I.; Safronova, M.S.

2004-01-01

A finite-field scaling method is applied to evaluate the Lennard-Jones interaction constant C 3 for alkali-metal atoms. The calculations are based on the relativistic single-double approximation in which single and double excitations of Dirac-Hartree-Fock wave functions are included to all orders in perturbation theory

Evidence of hexatic phase formation in two-dimensional Lennard-Jones binary arrays

International Nuclear Information System (INIS)

Li, M.; Johnson, W.L.; Goddard, W.A. III

1996-01-01

We report evidence of the hexatic phase formation in Lennard-Jones binary substitutional random arrays from isothermal-isobaric molecular-dynamics simulations. The hexatic phase is analogous to those predicted in Kosterlitz-Thouless theory of melting that is characterized by short-range translational order and quasi-long-range orientational order. At the crystal to hexatic phase transition, dislocation pairs are observed to unbind into isolated dislocations. Further disordering of the hexatic phase, however, does not lead to dissociation of dislocations into disclinations. Instead, the dislocations become clustered and form dislocation networks which results in formation of amorphous phases. copyright 1996 The American Physical Society

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

Evaporation of Lennard-Jones fluids.

Science.gov (United States)

Cheng, Shengfeng; Lechman, Jeremy B; Plimpton, Steven J; Grest, Gary S

2011-06-14

Evaporation and condensation at a liquid/vapor interface are ubiquitous interphase mass and energy transfer phenomena that are still not well understood. We have carried out large scale molecular dynamics simulations of Lennard-Jones (LJ) fluids composed of monomers, dimers, or trimers to investigate these processes with molecular detail. For LJ monomers in contact with a vacuum, the evaporation rate is found to be very high with significant evaporative cooling and an accompanying density gradient in the liquid domain near the liquid/vapor interface. Increasing the chain length to just dimers significantly reduces the evaporation rate. We confirm that mechanical equilibrium plays a key role in determining the evaporation rate and the density and temperature profiles across the liquid/vapor interface. The velocity distributions of evaporated molecules and the evaporation and condensation coefficients are measured and compared to the predictions of an existing model based on kinetic theory of gases. Our results indicate that for both monatomic and polyatomic molecules, the evaporation and condensation coefficients are equal when systems are not far from equilibrium and smaller than one, and decrease with increasing temperature. For the same reduced temperature T/T(c), where T(c) is the critical temperature, these two coefficients are higher for LJ dimers and trimers than for monomers, in contrast to the traditional viewpoint that they are close to unity for monatomic molecules and decrease for polyatomic molecules. Furthermore, data for the two coefficients collapse onto a master curve when plotted against a translational length ratio between the liquid and vapor phase.

Nonlinear transport processes and fluid dynamics: Cylindrical Couette flow of Lennard-Jones fluids

International Nuclear Information System (INIS)

Khayat, R.E.; Eu, B.C.

1988-01-01

In this paper we report on calculations of flow profiles for cylindrical Couette flow of a Lennard-Jones fluid. The flow is subjected to a temperature gradient and thermoviscous effects are taken into consideration. We apply the generalized fluid dynamic equations which are provided by the modified moment method for the Boltzmann equation reported previously. The results of calculations are in good agreement with the Monte Carlo direct simulation method by K. Nanbu [Phys. Fluids 27, 2632 (1984)] for most of Knudsen numbers for which the simulation data are available

Analysis of a Lennard-Jones fcc structure melting to the corresponding frozen liquid: Differences between the bulk and the surface

International Nuclear Information System (INIS)

Olivi-Tran, N.; Faivre, A.

2009-01-01

We computed a Lennard-Jones frozen liquid with a free surface using classical molecular dynamics. The structure factor curves on the free surface of this sample were calculated for different depths knowing that we have periodic boundary conditions on the other parts of the sample. The resulting structure factor curves show an horizontal shift of their first peak depending on how deep in the sample the curves are computed. We analyze our resulting curves in the light of spatial correlation functions during melting. The conclusion is that the differences between bulk and surface are quite small during melting and that at the end of melting, only the very surface happens to be less dense than the bulk. This result is intrinsic to the shape of the Lennard-Jones potential and does not depend on any other parameter.

Dynamics of vacancies in two-dimensional Lennard-Jones crystals

Science.gov (United States)

Yao, Zhenwei; Olvera de La Cruz, Monica

2015-03-01

Vacancies represent an important class of crystallographic defects, and their behaviors can be strongly coupled with relevant material properties. We report the rich dynamics of vacancies in two-dimensional Lennard-Jones crystals in several thermodynamic states. Specifically, we numerically observe significantly faster diffusion of the 2-point vacancy with two missing particles in comparison with other types of vacancies; it opens the possibility of doping 2-point vacancies into atomic materials to enhance atomic migration. In addition, the resulting dislocations in the healing of a long vacancy suggest the intimate connection between vacancies and topological defects that may provide an extra dimension in the engineering of defects in extensive crystalline materials for desired properties. We thank the financial support from the U.S. Department of Commerce, National Institute of Standards and Technology, the Office of the Director of Defense Research and Engineering (DDR&E) and the Air Force Office of Scientific Research.

Thermal conductivity of the Lennard-Jones fluid: An empirical correlation

International Nuclear Information System (INIS)

Bugel, Mathilde; Galliero, Guillaume

2008-01-01

In this work, is presented an empirical correlation on the thermal conductivity of the Lennard-Jones fluid based on extensive non-equilibrium molecular dynamics simulations results (103 points). Finite size and cutoff radius effects are investigated and taken into account to develop the correlation. This last, composed of low-density, residual and critical enhancement contributions, is built for a wide range of thermodynamics states, even at the vicinity of the critical point, and yields an average absolute deviation of 1.29% compared to our simulations. In addition, a careful analysis of the different contributions to the microscopic flux is carried out which sheds light on the underlying mechanism of the results. Finally, are discussed the limitations of the proposed model when applied to real simple fluids and mixtures using a standard corresponding states scheme and the van der Waals one-fluid approximation

Freezing and melting line invariants of the Lennard-Jones system

DEFF Research Database (Denmark)

Costigliola, Lorenzo; Schrøder, Thomas; Dyre, Jeppe C.

2016-01-01

The invariance of several structural and dynamical properties of the Lennard-Jones (LJ) system along the freezing and melting lines is interpreted in terms of isomorph theory. First the freezing/melting lines of the LJ system are shown to be approximated by isomorphs. Then we show...... that the invariants observed along the freezing and melting isomorphs are also observed on other isomorphs in the liquid and crystalline phases. The structure is probed by the radial distribution function and the structure factor and dynamics are probed by the mean-square displacement, the intermediate scattering...... function, and the shear viscosity. Studying these properties with reference to isomorph theory explains why the known single-phase melting criteria hold, e.g., the Hansen–Verlet and the Lindemann criteria, and why the Andrade equation for the viscosity at freezing applies, e.g., for most liquid metals. Our...

The Monte Carlo dynamics of a binary Lennard-Jones glass-forming mixture

International Nuclear Information System (INIS)

Berthier, L; Kob, W

2007-01-01

We use a standard Monte Carlo algorithm to study the slow dynamics of a binary Lennard-Jones glass-forming mixture at low temperature. We find that the Monte Carlo approach is by far the most efficient way to simulate a stochastic dynamics since the relaxation is about 10 times faster than in Brownian dynamics and about 30 times faster than in stochastic dynamics. Moreover, the average dynamical behaviour of the system is in quantitative agreement with that obtained using Newtonian dynamics, apart from at very short times where thermal vibrations are suppressed. We show, however, that dynamic fluctuations quantified by four-point dynamic susceptibilities do retain a dependence on the microscopic dynamics, as recently predicted theoretically

Longitudinal and bulk viscosities of Lennard-Jones fluids

Science.gov (United States)

Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

1996-12-01

Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

A molecular dynamics study of Lennard-Jones physisorption on W(100)

International Nuclear Information System (INIS)

Broughton, J.Q.

1980-01-01

The physisorption of Xe on W(100) was modeled by Lennard-Jones pair-wise interaction potentials and the dynamics of coverages ranging from one to four adlayers obtained by molecular dynamics simulation. At 115 K, the first two layers were well-ordered and each adsorbed with c(2 x 2) symmetry. Further adsorption produced a surface similar to that of a distorted Xe(100) face. In accord with the work of Broughton and Woodcock, the top layers of the three- and four-adlayer coverages were rough and had liquid-like diffusion coefficients. The potential energies of all layers other than the first were similar, thus corroborating one of the postulates of BET theory. Generally, the effect of adsorbing a layer was to reduce the entropy of all those beneath. (orig.)

Shear viscosity of the Lennard-Jones fluid near the triple point: Green-Kubo results

International Nuclear Information System (INIS)

Erpenbeck, J.J.

1988-01-01

The long-standing disagreement over the shear viscosity coefficient of the Lennard-Jones fluid near the triple point is reexamined through a series of very extensive Monte Carlo molecular-dynamics calculations of this transport coefficient based on the Green-Kubo theory. The stress autocorrelation function is shown to exhibit a slow decay, principally in the kinetic-potential and the potential-potential terms, which is large compared with the kinetic-kinetic long-time tail predicted by simple mode-coupling theory. Nonetheless, the viscosity coefficient, exclusive of any correction for this tail for times greater than are accessible numerically, is found to agree with that of Schoen and Hoheisel (who discounted the existence of such a tail) as well as nonequilibrium molecular-dynamics calculations. The large value of the viscosity coefficient found by Levesque and co-workers for 864 particles is brought into statistical agreement with the present results by a modest, but not unrealistic, increase in its statistical uncertainty. The pressure is found to exhibit an anomalous dependence on the size of the system, but the viscosity as well as the self-diffusion constant appear to be linear in the inverse of the number of particles, within the precision of our calculations. The viscosity coefficient, including a long-time-tail contribution based on the extended mode-coupling theory is (3.796 +- 0.068)σepsilon-c/m)/sup 1/2/ for the Lennard-Jones potential, fitted to a cubic spline, and (3.345 +- 0.068)σepsilon-c/m)/sup 1/2/ for the potential truncated at 2.5σ

Vacancy behavior in a compressed fcc Lennard-Jones crystal

International Nuclear Information System (INIS)

Beeler, J.R. Jr.

1981-12-01

This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the stable vacancy configuration whenever cubic symmetry was present. This includes all of the isotropic compression cases and the particular uniaxial compression case (eta = √2) that give a bcc structure. In addition, the SCV was the stable configuration for uniaxial compression eta 1.20, the SV-OP is an extended defect and, therefore, a saddle point for SV-OP migration could not be determined. The mechanism for the transformation from the SCV to the SV-OP as the stable form at eta = 1.29 appears to be an alternating sign [101] and/or [011] shear process

Simple approach to approximate predictions of the vapor–liquid equilibrium curve near the critical point and its application to Lennard-Jones fluids

International Nuclear Information System (INIS)

Staśkiewicz, B.; Okrasiński, W.

2012-01-01

We propose a simple analytical form of the vapor–liquid equilibrium curve near the critical point for Lennard-Jones fluids. Coexistence densities curves and vapor pressure have been determined using the Van der Waals and Dieterici equation of state. In described method the Bernoulli differential equations, critical exponent theory and some type of Maxwell's criterion have been used. Presented approach has not yet been used to determine analytical form of phase curves as done in this Letter. Lennard-Jones fluids have been considered for analysis. Comparison with experimental data is done. The accuracy of the method is described. -- Highlights: ► We propose a new analytical way to determine the VLE curve. ► Simple, mathematically straightforward form of phase curves is presented. ► Comparison with experimental data is discussed. ► The accuracy of the method has been confirmed.

Liquid-vapour phase behaviour of a polydisperse Lennard-Jones fluid

International Nuclear Information System (INIS)

Wilding, Nigel B; Sollich, Peter

2005-01-01

We describe a simulation study of the liquid-vapour phase behaviour of a model polydisperse fluid. Particle interactions are given by a Lennard-Jones potential in which polydispersity features both in the particle sizes and the amplitude of their interactions. We address the computational problem of accurately locating the cloud curve for such a system using Monte Carlo simulations within the grand canonical ensemble. The strongly nonlinear variation of the fractional volumes of the phases across the coexistence region precludes naive extrapolation to determine the cloud point density. Instead we propose an improved estimator for the cloud point location and use scaling arguments to predicts its finite-size behaviour. Excellent agreement is found with the simulation results. Application of the method reveals that the measured cloud curve is highly sensitive to the presence of large particles, even when they are extremely rare. This finding is expected to have implications for the reproducibility of experimentally measured phase diagrams in colloids and polymers

Theoretical prediction of crystallization kinetics of a supercooled Lennard-Jones fluid

Science.gov (United States)

Gunawardana, K. G. S. H.; Song, Xueyu

2018-05-01

The first order curvature correction to the crystal-liquid interfacial free energy is calculated using a theoretical model based on the interfacial excess thermodynamic properties. The correction parameter (δ), which is analogous to the Tolman length at a liquid-vapor interface, is found to be 0.48 ± 0.05 for a Lennard-Jones (LJ) fluid. We show that this curvature correction is crucial in predicting the nucleation barrier when the size of the crystal nucleus is small. The thermodynamic driving force (Δμ) corresponding to available simulated nucleation conditions is also calculated by combining the simulated data with a classical density functional theory. In this paper, we show that the classical nucleation theory is capable of predicting the nucleation barrier with excellent agreement to the simulated results when the curvature correction to the interfacial free energy is accounted for.

Phase diagram and universality of the Lennard-Jones gas-liquid system

KAUST Repository

Watanabe, Hiroshi

2012-01-01

The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.

Dodecagonal order in a two-dimensional Lennard-Jones system

International Nuclear Information System (INIS)

Leung, P.W.; Henley, C.L.; Chester, G.V.

1989-01-01

We investigate a two-dimensional Lennard-Jones mixture with the interaction parameters chosen so as to favor configurations where the large atoms form squares and equilateral triangles. Many such configurations are possible which by our choice of interactions are nearly degenerate in energy. It is hypothesized that a thermal equilibrium state with 12-fold orientational order exists. Several Monte Carlo simulations were performed to cool the system to a temperature approaching zero. The ordering process was studied by following the evolution of the configurations with temperature. The onset of ordering seemed to be very diffuse in space rather than nucleated at a point. The resulting configurations consist of squares and triangles, except for a few dislocations, and thus have perfect orientational order. We also characterized the deviation from ideal quasiperiodicity in terms of the ''phason strain''; this was analyzed both by fitting a linear relation between the physical space coordinates of the atoms and the corresponding ''perpendicular space'' coordinates, and also by calculating the diffraction peaks. The latter are shifted and broadened, relative to an ideal 12-fold diffraction pattern, as in real quasicrystals

The effect of atom mismatch on the fragility of supercooled Lennard-Jones binary mixtures

International Nuclear Information System (INIS)

Sun Minhua; Sun Yongli; Wang Aiping; Ma Congxiao; Li Jiayun; Cheng Weidong; Liu Fang

2006-01-01

The shear viscosity of the well-known binary Lennard-Jones mixture is simulated under constant temperature and constant volume conditions (NVT) by a molecular-dynamics (MD) method. The effect of atomic size mismatch on the fragility parameter and glass-forming ability is studied. The fragility parameters calculated from shear viscosity data decrease with the increment of the atomic size mismatch. The value of the fragility changes from 168.963 to 22.976 when the mismatch changes from 0.023 to 0.25. It is shown that the fragility parameter is sensitive to the atomic size mismatch. The calculated pair distribution functions and mean square displacements indicate that the glass-forming ability increases with the atomic size mismatch

Exit Planning At Joost El

DEFF Research Database (Denmark)

Nellemann, Camilla

2017-01-01

This is a Danish version. This case focuses on an owner-manager's considerations regarding his exit. Carsten Joost established Joost El in 2005. It currently employs 10 people. He has two sons but no intention to hand over the business to them. Rather, he hopes that his key employee eventually...

Modeling Aggregation Processes of Lennard-Jones particles Via Stochastic Networks

Science.gov (United States)

Forman, Yakir; Cameron, Maria

2017-07-01

We model an isothermal aggregation process of particles/atoms interacting according to the Lennard-Jones pair potential by mapping the energy landscapes of each cluster size N onto stochastic networks, computing transition probabilities from the network for an N-particle cluster to the one for N+1, and connecting these networks into a single joint network. The attachment rate is a control parameter. The resulting network representing the aggregation of up to 14 particles contains 6427 vertices. It is not only time-irreversible but also reducible. To analyze its transient dynamics, we introduce the sequence of the expected initial and pre-attachment distributions and compute them for a wide range of attachment rates and three values of temperature. As a result, we find the configurations most likely to be observed in the process of aggregation for each cluster size. We examine the attachment process and conduct a structural analysis of the sets of local energy minima for every cluster size. We show that both processes taking place in the network, attachment and relaxation, lead to the dominance of icosahedral packing in small (up to 14 atom) clusters.

The 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)-imide ionic liquid nanodroplets on solid surfaces and in electric field: A molecular dynamics simulation study

Science.gov (United States)

Dong, Dengpan; Vatamanu, Jenel P.; Wei, Xiaoyu; Bedrov, Dmitry

2018-05-01

Atomistic molecular dynamics simulations were conducted to study the wetting states of 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)-imide ionic liquid (IL) nanodroplets on surfaces with different strengths of van der Waals (VDW) interactions and in the presence of an electric field. By adjusting the depth of Lennard-Jones potential, the van der Waals interaction between the solid surface and ionic liquid was systematically varied. The shape of the droplets was analyzed to extract the corresponding contact angle utilized to characterize wetting states of the nanodroplets. The explored range of surface-IL interactions allowed contact angles ranging from complete IL spreading on the surface to poor wettability. The effect of the external electrical field was explored by adding point charges to the surface atoms. Systems with two charge densities (±0.002 e/atom and ±0.004 e/atom) that correspond to 1.36 V/nm and 2.72 V/nm electric fields were investigated. Asymmetrical wetting states were observed for both cases. At 1.36 V/nm electric field, contributions of IL-surface VDW interactions and Coulombic interactions to the wetting state were competitive. At 2.72 V/nm field, electrostatic interactions dominate the interaction between the nanodroplet and surface, leading to enhanced wettability on all surfaces.

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.

Spray flow-network flow transition of binary Lennard-Jones particle system

KAUST Repository

Inaoka, Hajime

2010-07-01

We simulate gas-liquid flows caused by rapid depressurization using a molecular dynamics model. The model consists of two types of Lennard-Jones particles, which we call liquid particles and gas particles. These two types of particles are distinguished by their mass and strength of interaction: a liquid particle has heavier mass and stronger interaction than a gas particle. By simulations with various initial number densities of these particles, we found that there is a transition from a spray flow to a network flow with an increase of the number density of the liquid particles. At the transition point, the size of the liquid droplets follows a power-law distribution, while it follows an exponential distribution when the number density of the liquid particles is lower than the critical value. The comparison between the transition of the model and that of models of percolation is discussed. The change of the average droplet size with the initial number density of the gas particles is also presented. © 2010 Elsevier B.V. All rights reserved.

Spray flow-network flow transition of binary Lennard-Jones particle system

KAUST Repository

Inaoka, Hajime; Yukawa, Satoshi; Ito, Nobuyasu

2010-01-01

We simulate gas-liquid flows caused by rapid depressurization using a molecular dynamics model. The model consists of two types of Lennard-Jones particles, which we call liquid particles and gas particles. These two types of particles are distinguished by their mass and strength of interaction: a liquid particle has heavier mass and stronger interaction than a gas particle. By simulations with various initial number densities of these particles, we found that there is a transition from a spray flow to a network flow with an increase of the number density of the liquid particles. At the transition point, the size of the liquid droplets follows a power-law distribution, while it follows an exponential distribution when the number density of the liquid particles is lower than the critical value. The comparison between the transition of the model and that of models of percolation is discussed. The change of the average droplet size with the initial number density of the gas particles is also presented. © 2010 Elsevier B.V. All rights reserved.

Efficient Implementations of Molecular Dynamics Simulations for Lennard-Jones Systems

KAUST Repository

Watanabe, H.

2011-08-01

Efficient implementations of the classical molecular dynamics (MD) method for Lennard-Jones particle systems are considered. Not only general algorithms but also techniques that are efficient for some specific CPU architectures are also explained. A simple spatialdecomposition-based strategy is adopted for parallelization. By utilizing the developed code, benchmark simulations are performed on a HITACHI SR16000/J2 system consisting of IBM POWER6 processors which are 4.7 GHz at the National Institute for Fusion Science (NIFS) and an SGI Altix ICE 8400EX system consisting of Intel Xeon processors which are 2.93 GHz at the Institute for Solid State Physics (ISSP), the University of Tokyo. The parallelization efficiency of the largest run, consisting of 4.1 billion particles with 8192 MPI processes, is about 73% relative to that of the smallest run with 128 MPI processes at NIFS, and it is about 66% relative to that of the smallest run with 4 MPI processes at ISSP. The factors causing the parallel overhead are investigated. It is found that fluctuations of the execution time of each process degrade the parallel efficiency. These fluctuations may be due to the interference of the operating system, which is known as OS Jitter.

A perturbed Lennard-Jones chain equation of state for liquid metals

Energy Technology Data Exchange (ETDEWEB)

Mousazadeh, M H; Marageh, M Ghanadi [AEOI, JIH Research Laboratory, 11365/8486, Tehran (Iran, Islamic Republic of)

2006-05-24

The perturbed Lennard-Jones chain (PLJC) equation of state is formulated based on first-order variational perturbation theory. The model uses two parameters for a monatomic system, segment size, {sigma}, and segment energy, {epsilon}/k. In this work, we employed the PLJC equation to calculate the liquid density of 26 metals, including alkali and alkali earth metals, iron, cobalt, nickel, copper, silver, gold, zinc, cadmium, mercury, aluminium, gallium, indium, thallium, tin, lead, antimony, and bismuth, for which accurate experimental data exist in the literature. The calculations cover a broad range of temperatures ranging from the melting point to close to the critical point and pressures ranging from the vapour-pressure curve up to pressures as high as 2000 bar. The average absolute deviation in the liquid density predicted by the PLJC equation of state in the saturation line compared with experimental data is 1.26%. Also, using the normal melting temperature and liquid density at melting point (T{sub m}, {rho}{sub m}) as input data for the estimation of the equation of state parameters provides a good correlation of liquid density at saturated and compressed pressures.

Contact angle of sessile drops in Lennard-Jones systems.

Science.gov (United States)

Becker, Stefan; Urbassek, Herbert M; Horsch, Martin; Hasse, Hans

2014-11-18

Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.

Kinetic-contact-driven gigantic energy transfer in a two-dimensional Lennard-Jones fluid confined to a rotating pore

Science.gov (United States)

Karbowniczek, Paweł; Chrzanowska, Agnieszka

2017-11-01

A two-dimensional Lennard-Jones system in a circular and rotating container has been studied by means of molecular dynamics technique. A nonequilibrium transition to the rotating stage has been detected in a delayed time since an instant switching of the frame rotation. This transition is attributed to the increase of the density at the wall because of the centrifugal force. At the same time the phase transition occurs, the inner system changes its configuration of the solid-state type into the liquid type. Impact of angular frequency and molecular roughness on the transport properties of the nonrotating and rotating systems is analyzed.

Enhancement of the droplet nucleation in a dense supersaturated Lennard-Jones vapor

Energy Technology Data Exchange (ETDEWEB)

Zhukhovitskii, D. I., E-mail: dmr@ihed.ras.ru [Joint Institute of High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bd. 2, 125412 Moscow (Russian Federation)

2016-05-14

The vapor–liquid nucleation in a dense Lennard-Jones system is studied analytically and numerically. A solution of the nucleation kinetic equations, which includes the elementary processes of condensation/evaporation involving the lightest clusters, is obtained, and the nucleation rate is calculated. Based on the equation of state for the cluster vapor, the pre-exponential factor is obtained. The latter diverges as a spinodal is reached, which results in the nucleation enhancement. The work of critical cluster formation is calculated using the previously developed two-parameter model (TPM) of small clusters. A simple expression for the nucleation rate is deduced and it is shown that the work of cluster formation is reduced for a dense vapor. This results in the nucleation enhancement as well. To verify the TPM, a simulation is performed that mimics a steady-state nucleation experiments in the thermal diffusion cloud chamber. The nucleating vapor with and without a carrier gas is simulated using two different thermostats for the monomers and clusters. The TPM proves to match the simulation results of this work and of other studies.

Influence of DC electric field on the Lennard-Jones potential and phonon vibrations of carbon nanotube on catalyst

International Nuclear Information System (INIS)

Saeidi, Mohammadreza; Vaezzadeh, Majid; Badakhshan, Farzaneh

2011-01-01

Influence of DC electric field on carbon nanotube (CNT) growth in chemical vapor deposition is studied. Investigation of electric field effect in van der Waals interaction shows that increase in DC electric field raises the magnitude of attractive term of the Lennard-Jones potential. By using a theoretical model based on phonon vibrations of CNT on catalyst, it is shown that there is an optimum field for growth. Also it is observed that CNT under optimum electric field is longer than CNT in the absence of field. Finally, the relation between optimum DC electric field and type of catalyst is investigated and for some intervals of electric field, the best catalyst is introduced, which is very useful for experimental researches. -- Research highlights: → Influence of DC electric field on CNT growth in CVD. → Effect of electric field on van der Waals interaction between CNT and its catalyst. → Applying DC electric field increases attractive term of Lennard-Jonespotential. → There is an optimum DC field for CNT growth. → For catalyst with stronger van der Waals interaction, optimum field is smaller.

Numerical computations of the Lennard-Jones resonances and ''relative displacements'' of the scattered atomic beams from the system He/LiF(001)

International Nuclear Information System (INIS)

Garcia, N.

1976-01-01

This paper considers the effect of the attractive part of the interaction potential on the scattering of He atoms from a LiF(001) surface. We calculate, in particular, the Lennard-Jones resonances on the intensities and the phases of the scattered amplitudes, using a square well in the front of a hard corrugated surface model. We show that the amplitudes for incident energies smaller than the depth of the well are dominated by the resonances

Communication: Studies of the Lennard-Jones fluid in 2, 3, and 4 dimensions highlight the need for a liquid-state 1/d expansion

International Nuclear Information System (INIS)

Costigliola, Lorenzo; Schrøder, Thomas B.; Dyre, Jeppe C.

2016-01-01

The recent theoretical prediction by Maimbourg and Kurchan [e-print http://arxiv.org/abs/1603.05023 (2016)] that for regular pair-potential systems the virial potential-energy correlation coefficient increases towards unity as the dimension d goes to infinity is investigated for the standard 12-6 Lennard-Jones fluid. This is done by computer simulations for d = 2, 3, 4 going from the critical point along the critical isotherm/isochore to higher density/temperature. In both cases the virial potential-energy correlation coefficient increases significantly. For a given density and temperature relative to the critical point, with increasing number of dimension the Lennard-Jones system conforms better to the hidden-scale-invariance property characterized by high virial potential-energy correlations (a property that leads to the existence of isomorphs in the thermodynamic phase diagram, implying that it becomes effectively one-dimensional in regard to structure and dynamics). The present paper also gives the first numerical demonstration of isomorph invariance of structure and dynamics in four dimensions. Our findings emphasize the need for a universally applicable 1/d expansion in liquid-state theory; we conjecture that the systems known to obey hidden scale invariance in three dimensions are those for which the yet-to-be-developed 1/d expansion converges rapidly.

A model-adaptivity method for the solution of Lennard-Jones based adhesive contact problems

Science.gov (United States)

Ben Dhia, Hachmi; Du, Shuimiao

2018-05-01

The surface micro-interaction model of Lennard-Jones (LJ) is used for adhesive contact problems (ACP). To address theoretical and numerical pitfalls of this model, a sequence of partitions of contact models is adaptively constructed to both extend and approximate the LJ model. It is formed by a combination of the LJ model with a sequence of shifted-Signorini (or, alternatively, -Linearized-LJ) models, indexed by a shift parameter field. For each model of this sequence, a weak formulation of the associated local ACP is developed. To track critical localized adhesive areas, a two-step strategy is developed: firstly, a macroscopic frictionless (as first approach) linear-elastic contact problem is solved once to detect contact separation zones. Secondly, at each shift-adaptive iteration, a micro-macro ACP is re-formulated and solved within the multiscale Arlequin framework, with significant reduction of computational costs. Comparison of our results with available analytical and numerical solutions shows the effectiveness of our global strategy.

Kapitza thermal conductance at the interface between Lennard-Jones crystals using non-equilibrium molecular dynamics simulations

International Nuclear Information System (INIS)

Merabia, Samy; Termentzidis, Konstantinos

2012-01-01

We characterize the thermal Kapitza conductance between Lennard-Jones solids using non-equilibrium molecular dynamics simulations. We consider a series of perfect interfaces between mass-mismatched solids. We show that both the acoustic mismatch model (AMM) and the diffuse mismatch model (DMM) fail to predict the interfacial conductance even for large acoustic mismatched solids. This poor agreement may be explained by the use of equilibrium distributions of phonons in the expression of the conductance. On the other hand, we show that an extension of AMM taking into account the out-of-equilibrium phonon distribution on both sides of the interface leads to a good agreement with the simulation results, even for interfaces between almost similar materials. This opens the way to understand interfacial heat transport across real semi-conductors and dielectrics.

Relation between calculated Lennard-Jones potential and thermal stability of Cu-based bulk metallic glasses

International Nuclear Information System (INIS)

Lin, T.; Bian, X.F.; Jiang, J.

2006-01-01

Two metallic bulk glasses, Cu 60 Zr 30 Ti 10 and Cu 47 Ti 33 Zr 11 Ni 8 Si 1 , with a diameter of 3 mm were prepared by copper mold casting method. Dilatometric measurement was carried out on the two glassy alloys to obtain information about the average nearest-neighbour distance r 0 and the effective depth of pair potential V 0 . By assuming a Lennard-Jones potential, r 0 and V 0 were calculated to be 0.28 nm and 0.16 eV for Cu 60 Zr 30 Ti 10 and 0.27 nm and 0.13 eV for Cu 47 Ti 33 Zr 11 Ni 8 Si 1 , respectively. It was found that the glassy alloy Cu 60 Zr 30 Ti 10 was more stable than Cu 47 Ti 33 Zr 11 Ni 8 Si 1 against heating from both experiment and calculation

An efficient method for the determination of fourth virial coefficient with Lennard-Jones (12-6) potential and its application

Energy Technology Data Exchange (ETDEWEB)

Mamedov, Bahtiyar A. [Department of Physics, Gaziosmanpaşa University, 60250, Tokat (Turkey); Somuncu, Elif; Askerov, Iskender M. [Department of Physics, Giresun University, Giresun (Turkey)

2016-08-10

In this work, a new theoretical approach is proposed for calculating fourth virial coefficient with Lennard-Jones potential. The established algorithm can be used to evaluate the thermodynamics properties and the intermolecular interaction potentials of liquids and gases with an improved accuracy. Note that the evaluation of the high-order virial coefficients is very valuable for accurate calculation of thermodynamic parameters. By using the suggested method, the fourth virial coefficient of CH{sub 4}, Ar, C{sub 2}H{sub 6} and SF{sub 6} molecules are evaluated. The calculation results are useful for accurate interpretation of the experimental data and of the determination of related physical properties.

A test of the mean density approximation for Lennard-Jones mixtures with large size ratios

International Nuclear Information System (INIS)

Ely, J.F.

1986-01-01

The mean density approximation for mixture radial distribution functions plays a central role in modern corresponding-states theories. This approximation is reasonably accurate for systems that do not differ widely in size and energy ratios and which are nearly equimolar. As the size ratio increases, however, or if one approaches an infinite dilution of one of the components, the approximation becomes progressively worse, especially for the small molecule pair. In an attempt to better understand and improve this approximation, isothermal molecular dynamics simulations have been performed on a series of Lennard-Jones mixtures. Thermodynamic properties, including the mixture radial distribution functions, have been obtained at seven compositions ranging from 5 to 95 mol%. In all cases the size ratio was fixed at two and three energy ratios were investigated, 22 / 11 =0.5, 1.0, and 1.5. The results of the simulations are compared with the mean density approximation and a modification to integrals evaluated with the mean density approximation is proposed

Transport coefficients of liquid CF4 and SF6 computed by molecular dynamics using polycenter Lennard-Jones potentials

Science.gov (United States)

Hoheisel, C.

1989-01-01

For several liquid states of CF4 and SF4, the shear and the bulk viscosity as well as the thermal conductivity were determined by equilibrium molecular dynamics (MD) calculations. Lennard-Jones four- and six-center pair potentials were applied, and the method of constraints was chosen for the MD. The computed Green-Kubo integrands show a steep time decay, and no particular longtime behavior occurs. The molecule number dependence of the results is found to be small, and 3×105 integration steps allow an accuracy of about 10% for the shear viscosity and the thermal conductivity coefficient. Comparison with experimental data shows a fair agreement for CF4, while for SF6 the transport coefficients fall below the experimental ones by about 30%.

Transport coefficients of liquid CF4 and SF6 computed by molecular dynamics using polycenter Lennard-Jones potentials

International Nuclear Information System (INIS)

Hoheisel, C.

1989-01-01

For several liquid states of CF 4 and SF 6 , the shear and the bulk viscosity as well as the thermal conductivity were determined by equilibrium molecular dynamics (MD) calculations. Lennard-Jones four- and six-center pair potentials were applied, and the method of constraints were chosen for the MD. The computed Green-Kubo integrands show a steep time decay, and no particular longtime behavior occurs. The molecule number dependence of the results is found to be small, and 3 x 10 5 integration steps allow an accuracy of about 10% for the shear viscosity and the thermal conductivity coefficient. Comparison with experimental data shows a fair agreement for CF 4 , while for SF 6 the transport coefficients fall below the experimental ones by about 30%

Thermodynamic equivalence between the Lennard-Jones and hard-core attractive Yukawa systems

International Nuclear Information System (INIS)

Kadiri, Y.; Albaki, R.; Bretonnet, J.L.

2008-01-01

The investigation of the thermodynamic properties of the Lennard-Jones (LJ) fluid is made by means of a system of particles interacting with a potential of hard-core plus attractive Yukawa tail (HCY). Due to the similarity between the LJ potential and the HCY potential in its overall form, it is worthwhile seeking to approximate the LJ potential in much the same way that the hard-sphere reference potential has been so used. The study consists in describing the thermodynamics of the LJ fluid in terms of the equivalent HCY system, whose the properties are known accurately, by means of mapping the thermodynamic quantities for the HCY potential parameters. The method is feasible owing to a convenient analytical expression of the Helmholtz free energy from the mean-spherical approximation expanded in power of the inverse temperature. Two different procedures are used to determine the parameters of the HCY potential as a function of the thermodynamic states: one is based on the simultaneous fits of pressure and internal energy of the LJ system and the other uses the concept of collision frequency. The reasonable homogeneity of the results in both procedures of mapping makes that the HCY potential is a very good reference system, whose the proposed theoretical expressions can be used confidently to predict the thermodynamic properties of more realistic potentials

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)

Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation

KAUST Repository

Kadoura, Ahmad Salim

2016-06-01

In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard-Jones (LJ) particles. The main advantage of such surrogates, once generated, is the capability of accurately computing the needed thermodynamic quantities in a few seconds, thus efficiently replacing the computationally expensive MC molecular simulations. Benefiting from the tremendous computational time reduction, the PC surrogates were used to conduct large-scale optimization in order to propose single-site LJ models for several simple molecules. Experimental data, a set of supercritical isotherms, and part of the two-phase envelope, of several pure components were used for tuning the LJ parameters (ε, σ). Based on the conducted optimization, excellent fit was obtained for different noble gases (Ar, Kr, and Xe) and other small molecules (CH4, N2, and CO). On the other hand, due to the simplicity of the LJ model used, dramatic deviations between simulation and experimental data were observed, especially in the two-phase region, for more complex molecules such as CO2 and C2 H6.

Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited

International Nuclear Information System (INIS)

Mulero, A; Galan, C; Cuadros, F

2003-01-01

We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs

Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation

Energy Technology Data Exchange (ETDEWEB)

Kadoura, Ahmad, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa; Sun, Shuyu, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa [Computational Transport Phenomena Laboratory, The Earth Sciences and Engineering Department, The Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Siripatana, Adil, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa; Hoteit, Ibrahim, E-mail: ibrahim.hoteit@kaust.edu.sa [Earth Fluid Modeling and Predicting Group, The Earth Sciences and Engineering Department, The Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Knio, Omar, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa [Uncertainty Quantification Center, The Applied Mathematics and Computational Science Department, The Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)

2016-06-07

In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard-Jones (LJ) particles. The main advantage of such surrogates, once generated, is the capability of accurately computing the needed thermodynamic quantities in a few seconds, thus efficiently replacing the computationally expensive MC molecular simulations. Benefiting from the tremendous computational time reduction, the PC surrogates were used to conduct large-scale optimization in order to propose single-site LJ models for several simple molecules. Experimental data, a set of supercritical isotherms, and part of the two-phase envelope, of several pure components were used for tuning the LJ parameters (ε, σ). Based on the conducted optimization, excellent fit was obtained for different noble gases (Ar, Kr, and Xe) and other small molecules (CH{sub 4}, N{sub 2}, and CO). On the other hand, due to the simplicity of the LJ model used, dramatic deviations between simulation and experimental data were observed, especially in the two-phase region, for more complex molecules such as CO{sub 2} and C{sub 2} H{sub 6}.

Nematic-isotropic transition in some lattice models for rigid cores having semiflexible tails: segmental Lennard-Jones interactions

International Nuclear Information System (INIS)

Dowell, F.

1983-01-01

Two average-environment simple cubic lattice models: a refined model and a simple model, both having site-site (segmental) pair Lennard-Jones (LJ) interactions: for molecules composed of rigid cores having semiflexible tails are presented. The calculated values of the following properties at the nematic-isotropic transition for rigid rods of varying length are compared with relevant experimental data for PAA (p-azoxyanisole, or 4,4'-dimethoxyazoxybenzene): temperature, core orientational order parameter, nematic density and volume, relative density change, and relative entropy change. The temperature change as a function of volume change at constant order parameter is also discussed. In general, both LJ models give considerably better quantitative agreement with experiment, especially for the temperature and the relative density change, than do the earlier lattice models with hard repulsions, with or without constant segmental pair interaction energies. In most aspects, these LJ models give good quantitative agreement with experiment. These LJ models elucidate the importance of realistic intermolecular potentials, especially the role of soft repulsions, in describing an order-disorder transition between two condensed phases

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

Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited

Energy Technology Data Exchange (ETDEWEB)

Mulero, A [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Galan, C [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Cuadros, F [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain)

2003-04-16

We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs.

Comprehensive representation of the Lennard-Jones equation of state based on molecular dynamics simulation data

Science.gov (United States)

Pieprzyk, S.; Brańka, A. C.; Maćkowiak, Sz.; Heyes, D. M.

2018-03-01

The equation of state (EoS) of the Lennard-Jones fluid is calculated using a new set of molecular dynamics data which extends to higher temperature than in previous studies. The modified Benedict-Webb-Rubin (MBWR) equation, which goes up to ca. T ˜ 6, is reparametrized with new simulation data. A new analytic form for the EoS, which breaks the fluid range into two regions with different analytic forms and goes up to ca. T ≃ 35, is also proposed. The accuracy of the new formulas is at least as good as the MBWR fit and goes to much higher temperature allowing it to now encompass the Amagat line. The fitted formula extends into the high temperature range where the system can be well represented by inverse power potential scaling, which means that our specification of the equation of state covers the entire (ρ, T) plane. Accurate analytic fit formulas for the Boyle, Amagat, and inversion curves are presented. Parametrizations of the extrema loci of the isochoric, CV, and isobaric, CP, heat capacities are given. As found by others, a line maxima of CP terminates in the critical point region, and a line of minima of CP terminates on the freezing line. The line of maxima of CV terminates close to or at the critical point, and a line of minima of CV terminates to the right of the critical point. No evidence for a divergence in CV in the critical region is found.

Characterization of signaling and traffic in Joost

NARCIS (Netherlands)

Alhaisoni, M.; Liotta, A.

2009-01-01

Peer-to-Peer (P2P) IPTV applications have increasingly been considered as a potential approach to online broadcasting. Recently, many applications such as PPlive, PPStream, and Sopcast have been deployed to deliver live streaming via P2P. One of the latest systems is Joost, which can deliver both

Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

Energy Technology Data Exchange (ETDEWEB)

Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain)

2015-09-14

We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related

Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

International Nuclear Information System (INIS)

Martínez-Ruiz, F. J.; Blas, F. J.; Moreno-Ventas Bravo, A. I.

2015-01-01

We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ 11 = σ 22 , with the same dispersive energy between like species, ϵ 11 = ϵ 22 , but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r c and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r c is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the

Properties of Organic Liquids when Simulated with Long-Range Lennard-Jones Interactions.

Science.gov (United States)

Fischer, Nina M; van Maaren, Paul J; Ditz, Jonas C; Yildirim, Ahmet; van der Spoel, David

2015-07-14

In order to increase the accuracy of classical computer simulations, existing methodologies may need to be adapted. Hitherto, most force fields employ a truncated potential function to model van der Waals interactions, sometimes augmented with an analytical correction. Although such corrections are accurate for homogeneous systems with a long cutoff, they should not be used in inherently inhomogeneous systems such as biomolecular and interface systems. For such cases, a variant of the particle mesh Ewald algorithm (Lennard-Jones PME) was already proposed 20 years ago (Essmann et al. J. Chem. Phys. 1995, 103, 8577-8593), but it was implemented only recently (Wennberg et al. J. Chem. Theory Comput. 2013, 9, 3527-3537) in a major simulation code (GROMACS). The availability of this method allows surface tensions of liquids as well as bulk properties to be established, such as density and enthalpy of vaporization, without approximations due to truncation. Here, we report on simulations of ≈150 liquids (taken from a force field benchmark: Caleman et al. J. Chem. Theory Comput. 2012, 8, 61-74) using three different force fields and compare simulations with and without explicit long-range van der Waals interactions. We find that the density and enthalpy of vaporization increase for most liquids using the generalized Amber force field (GAFF, Wang et al. J. Comput. Chem. 2004, 25, 1157-1174) and the Charmm generalized force field (CGenFF, Vanommeslaeghe et al. J. Comput. Chem. 2010, 31, 671-690) but less so for OPLS/AA (Jorgensen and Tirado-Rives, Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 6665-6670), which was parametrized with an analytical correction to the van der Waals potential. The surface tension increases by ≈10(-2) N/m for all force fields. These results suggest that van der Waals attractions in force fields are too strong, in particular for the GAFF and CGenFF. In addition to the simulation results, we introduce a new version of a web server, http

Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation

KAUST Repository

Kadoura, Ahmad Salim; Siripatana, Adil; Sun, Shuyu; Knio, Omar; Hoteit, Ibrahim

2016-01-01

In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard

KAJIAN METODE ANALISA DATA GOAL SEEK (MICROSOFT EXCEL UNTUK PENYELESAIAN PERSAMAAN SCHRÖDINGER DALAM MENENTUKAN KUANTISASI ENERGI DIBAWAH PENGARUH POTENSIAL LENNARD-JONES

Directory of Open Access Journals (Sweden)

W. Kurniawan

2016-11-01

Full Text Available Penyelesaian persamaan Schrödinger dengan berbagai model potensial sangat penting dilakukan untuk memberikan gambaran perilaku zarah di bawah pengaruh potensial tersebut. Solusinya berupa fungsi gelombang yang memuat informasi penting tentang perilaku gelombang yang ditunjukkan dengan energi terikatnya. Pada penelitian ini kasus yang ingin diteliti adalah model potensial Lennard-Jones dengan menggunakan metode analisa goal seek yang tersedia pada Microsoft excel. Persamaannya dijabarkan dengan metode Euler terlebih dahulu selanjutnya syarat batas ditentukan agar ketelitian hasil diperoleh. Agar perhitungan goal seek  dapat dilakukan maka harus diubah dari besaran fisis menjadi besaran yang tidak berdimensi dimana parameter v menunjukkan keklasikan suatu sistem dan nilai  ε   menunjukkan kuantisasi energi. Hasil yang diperoleh adalah bahwa dengan memasukkan parameter kontrol nilai v tertentu, telah diperoleh beberapa keadaan energi dengan batas zkiri dan zkanan tertentu. Ketika masukan parameter v yang diberikan semakin besar keadaan energinya pun lebih rapat (ditunjukkan energy state yang diperoleh semakin banyak dibandingkan bila masukan v-nya lebih kecil. Penelitian ini bermanfaat untuk menyederhanakan kasus potensial yang lebih rumit, dimana solusinya dapat diperoleh dengan mudah dan konsep kuantisasi energi akibat model potensial L-J dapat dipahami secara utuh. Solution of the Schrödinger equation in various  potential model is very important in order to provide an overview of  behaviour’s particle under influence of potential model. The solution is a wave function that contains important information are shown by energy state. In this research, the investigated is Lennard Jones potential by using Goal Seek analysis which are available in Microsoft Excel. The equation is described by the Euler method and then boundary condition is determined to perecision result which are obtained. It must be changed in terms dimensionless where

Friction between Two Brownian Particles in a Lennard-Jones Solvent: A Molecular Dynamics Simulation Study

International Nuclear Information System (INIS)

Lee, Song Hi

2010-01-01

We presented a molecular dynamics (MD) simulation study of friction behavior between two very massive Brownian particles (BPs) oriented along the z axis with BP centers at -R 12 /2 and R 12 /2 in a Lennard-Jones solvent as a function of the inter-particle separation, R 12 . In order to fix the BPs in space an MD simulation method with the mass of the BP as 10 90 g/mol was employed in which the total momentum of the system was conserved. The cross friction coefficients of x- and y-components are nearly insensitive to R 12 but that of z-component varies with R 12 in good accord with the simple hydrodynamic approximation. On the other hand, the self-friction coefficients are estimated as a very small difference from the single particle friction coefficients, ξ 0 , at all inter-particle separations which agrees with the simple hydrodynamic approximation. Consequently ξ (-) xx is nearly independent of R 12 and equal to its asymptotic value of twice the single particle friction coefficient, and the other relative friction, ξ (-) zz , is in good agreement with the simple hydrodynamic approximation. Molecular theory of Brownian motion of a single heavy particle in a fluid had received a considerable attention in earlier years. After molecular dynamics (MD) simulation technique was utilized, this subject has been widely studied by a variety of MD simulation methods. The common issues here were about the long time behavior of the force and velocity autocorrelation functions, the system size dependent friction coefficient of a massive Brownian particle, and test of the Stokes-Einstein law

Scaling relation and regime map of explosive gas–liquid flow of binary Lennard-Jones particle system

KAUST Repository

Inaoka, Hajime

2012-02-01

We study explosive gasliquid flows caused by rapid depressurization using a molecular dynamics model of Lennard-Jones particle systems. A unique feature of our model is that it consists of two types of particles: liquid particles, which tend to form liquid droplets, and gas particles, which remain supercritical gaseous states under the depressurization realized by simulations. The system has a pipe-like structure similar to the model of a shock tube. We observed physical quantities and flow regimes in systems with various combinations of initial particle number densities and initial temperatures. It is observed that a physical quantity Q, such as pressure, at position z measured along a pipe-like system at time t follows a scaling relation Q(z,t)=Q(zt) with a scaling function Q(ζ). A similar scaling relation holds for time evolution of flow regimes in a system. These scaling relations lead to a regime map of explosive flows in parameter spaces of local physical quantities. The validity of the scaling relations of physical quantities means that physics of equilibrium systems, such as an equation of state, is applicable to explosive flows in our simulations, though the explosive flows involve highly nonequilibrium processes. In other words, if the breaking of the scaling relations is observed, it means that the explosive flows cannot be fully described by physics of equilibrium systems. We show the possibility of breaking of the scaling relations and discuss its implications in the last section. © 2011 Elsevier B.V. All rights reserved.

Equation of state and Helmholtz free energy for the atomic system of the repulsive Lennard-Jones particles.

Science.gov (United States)

Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

2017-12-07

Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6≤T * ≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0.06 and 0.14 for the fluid and solid phases, respectively. The thermodynamic integration method is used to calculate the free energy using the MC simulation results. The Helmholtz free energy of the ideal gas is employed as the reference state for the fluid phase. For the solid phase, the values of the free energy at the reduced density equivalent to the close-packed of a hard sphere are used as the reference state. To check the validity of the predicted values of the Helmholtz free energy, the Widom particle insertion method and the Einstein crystal technique of Frenkel and Ladd are employed. The results obtained from the MC simulation approaches are well agreed to the EOS results, which show that the proposed model can reliably be utilized in the framework of thermodynamic theories.

Gaussian approximation to single particle correlations at and below the picosecond scale for Lennard-Jones and nanoparticle fluids

International Nuclear Information System (INIS)

Van Zon, Ramses; Ashwin, S S; Cohen, E G D

2008-01-01

To describe short time (picosecond) and small scale (nanometre) transport in fluids, a Green's function approach was recently developed. This approach relies on an expansion of the distribution of single particle displacements around a Gaussian function, yielding an infinite series of correction terms. Applying a recent theorem (van Zon and Cohen 2006 J. Stat. Phys. 123 1–37) shows that for sufficiently small times the terms in this series become successively smaller, so that truncating the series near or at the Gaussian level might provide a good approximation. In this paper, we derive a theoretical estimate for the time scale at which truncating the series at or near the Gaussian level could be supposed to be accurate for equilibrium nanoscale systems. In order to numerically estimate this time scale, the coefficients for the first few terms in the series are determined in computer simulations for a Lennard-Jones (LJ) fluid, an isotopic LJ mixture and a suspension of a LJ-based model of nanoparticles in a LJ fluid. The results suggest that for LJ fluids an expansion around a Gaussian is accurate at time scales up to a picosecond, while for nanoparticles in suspension (a nanofluid), the characteristic time scale up to which the Gaussian is accurate becomes of the order of 5–10 ps. (invited article)

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.

Comparison of Green-Kubo and nonequilibrium calculations of the self-diffusion constant of a Lennard-Jones fluid

International Nuclear Information System (INIS)

Erpenbeck, J.J.

1987-01-01

We apply the so-called ''synthetic'' nonequilibrium molecular-dynamics method to the calculation of the self-diffusion constant of a Lennard-Jones fluid at a number density of 0.85/σ 3 and a temperature of 1.08 epsilon-c/k/sub B/ (where epsilon-c and σ are the energy and length parameters of the potential and k/sub B/ is the Boltzmann constant). By comparing with the Green-Kubo calculation for the same state of the system and for the same number of particles, N, we find the latter calculation to yield more precise values of the self-diffusion constant for a given number of molecular-dynamics time steps. Even at small values of the diffusion current, a nontrivial time is needed for the nonequilibrium calculation to reach the steady state. For larger values of the driving force, the steady-state flow appears to become unstable and evidence of a secondary flow pattern is presented. The presence of these instabilities acts as a limit to the range of the driving force for which the steady-state method can be applied. With increasing N the range of stable values of the diffusion current density decreases. For the Green-Kubo calculations, the N dependence of the self-diffusion constant is found to be anomalous for N = 108, with the 1/N dependence only exhibited for at least 500 particles. The nonequilibrium results, while approximately independent of N for 108 and 500 particles, are found to have a similar anomalous N dependence when we extend the calculations to 1372 particles, thereby bringing the Green-Kubo and nonequilibrium results into agreement in the large-system limit

Self-consistent phonons revisited. I. The role of thermal versus quantum fluctuations on structural transitions in large Lennard-Jones clusters.

Science.gov (United States)

Georgescu, Ionuţ; Mandelshtam, Vladimir A

2012-10-14

The theory of self-consistent phonons (SCP) was originally developed to address the anharmonic effects in condensed matter systems. The method seeks a harmonic, temperature-dependent Hamiltonian that provides the "best fit" for the physical Hamiltonian, the "best fit" being defined as the one that optimizes the Helmholtz free energy at a fixed temperature. The present developments provide a scalable O(N) unified framework that accounts for anharmonic effects in a many-body system, when it is probed by either thermal (ℏ → 0) or quantum fluctuations (T → 0). In these important limits, the solution of the nonlinear SCP equations can be reached in a manner that requires only the multiplication of 3N × 3N matrices, with no need of diagonalization. For short range potentials, such as Lennard-Jones, the Hessian, and other related matrices are highly sparse, so that the scaling of the matrix multiplications can be reduced from O(N(3)) to ~O(N). We investigate the role of quantum effects by continuously varying the de-Boer quantum delocalization parameter Λ and report the N-Λ (T = 0), and also the classical N-T (Λ = 0) phase diagrams for sizes up to N ~ 10(4). Our results demonstrate that the harmonic approximation becomes inadequate already for such weakly quantum systems as neon clusters, or for classical systems much below the melting temperatures.

Uhiuus orkester Tallinn Sinfonietta / Ivo Lille ja Risto Joost ; intervjueerinud Kristina Kõrver

Index Scriptorium Estoniae

Lille, Ivo, 1977-

2009-01-01

Kontserdiagentuurist HIMusic Agency ja Tallinn Sinfoniettast räägivad dirigent R. Joost ja I. Lille. Avakontserdist Vene Kultuurikeskuses, kus oli kavas Mozarti sümfooniad 1, 10 ja 40 ning kontsertaariad bulgaaria soprani Sonya Youncheva esituses

Fusion process of Lennard-Jones clusters: global minima and magic numbers formation

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2004-01-01

We present a new theoretical framework for modeling the fusion process of Lennard–Jones (LJ) clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing paths up to the cluster size of 150 atoms...

Density functional study of the pressure tensor for inhomogeneous Lennard—Jones fluids

International Nuclear Information System (INIS)

Sun Zong-Li; Liu Zhi-Cheng; Kang Yan-Shuang; Ma Heng-Xin; Kang Yan-Mei

2012-01-01

Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interfacial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid-fluid interfacial tension for Lennard—Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners. (condensed matter: structural, mechanical, and thermal properties)

Boekbespreking Ronald Meester en Joost Hulshof: Wiskunde in je vingers : Hogere wiskunde omlaaghalen

NARCIS (Netherlands)

Caspers, Wim; Timmer, Mark

“Een oppepcursus voor liefhebbers en andere freaks”, zo omschrijven Ronald Meester en Joost Hulshof hun boek W={kunde} in je vingers. Wim Caspers en Mark Timmer, allebei docent aan een middelbare school en lerarenopleider, bekeken het boek ieder vanuit beide rollen en gingen op bezoek bij de

Drug Release from Phase-Changeable Nanodroplets Triggered by Low-Intensity Focused Ultrasound

Science.gov (United States)

Cao, Yang; Chen, Yuli; Yu, Tao; Guo, Yuan; Liu, Fengqiu; Yao, Yuanzhi; Li, Pan; Wang, Dong; Wang, Zhigang; Chen, Yu; Ran, Haitao

2018-01-01

Background: As one of the most effective triggers with high tissue-penetrating capability and non-invasive feature, ultrasound shows great potential for controlling the drug release and enhancing the chemotherapeutic efficacy. In this study, we report, for the first time, construction of a phase-changeable drug-delivery nanosystem with programmable low-intensity focused ultrasound (LIFU) that could trigger drug-release and significantly enhance anticancer drug delivery. Methods: Liquid-gas phase-changeable perfluorocarbon (perfluoropentane) and an anticancer drug (doxorubicin) were simultaneously encapsulated in two kinds of nanodroplets. By triggering LIFU, the nanodroplets could be converted into microbubbles locally in tumor tissues for acoustic imaging and the loaded anticancer drug (doxorubicin) was released after the microbubble collapse. Based on the acoustic property of shell materials, such as shell stiffness, two types of nanodroplets (lipid-based nanodroplets and PLGA-based nanodroplets) were activated by different acoustic pressure levels. Ultrasound irradiation duration and power of LIFU were tested and selected to monitor and control the drug release from nanodroplets. Various ultrasound energies were introduced to induce the phase transition and microbubble collapse of nanodroplets in vitro (3 W/3 min for lipid nanodroplets; 8 W/3 min for PLGA nanodroplets). Results: We detected three steps in the drug-releasing profiles exhibiting the programmable patterns. Importantly, the intratumoral accumulation and distribution of the drug with LIFU exposure were significantly enhanced, and tumor proliferation was substantially inhibited. Co-delivery of two drug-loaded nanodroplets could overcome the physical barriers of tumor tissues during chemotherapy. Conclusion: Our study provides a new strategy for the efficient ultrasound-triggered chemotherapy by nanocarriers with programmable LIFU capable of achieving the on-demand drug release. PMID:29507623

Thermophoretic Motion of Water Nanodroplets confined inside Carbon Nanotubes

DEFF Research Database (Denmark)

Zambrano, Harvey A; Walther, Jens Honore; Koumoutsakos, Petros

2009-01-01

We study the thermophoretic motion of water nanodroplets confined inside carbon nanotubes using molecular dynamics simulations. We find that the nanodroplets move in the direction opposite the imposed thermal gradient with a terminal velocity that is linearly proportional to the gradient....... The translational motion is associated with a solid body rotation of the water nanodroplet coinciding with the helical symmetry of the carbon nanotube. The thermal diffusion displays a weak dependence on the wetting of the water-carbon nanotube interface. We introduce the use of the Moment Scaling Spectrum (MSS......) in order to determine the characteristics of the motion of the nanoparticles inside the carbon nanotube. The MSS indicates that affinity of the nanodroplet with the walls of the carbon nanotubes is important for the isothermal diffusion, and hence for the Soret coefficient of the system....

Phase separation of a Lennard-Jones fluid interacting with a long, condensed polymer chain: implications for the nuclear body formation near chromosomes.

Science.gov (United States)

Oh, Inrok; Choi, Saehyun; Jung, YounJoon; Kim, Jun Soo

2015-08-28

Phase separation in a biological cell nucleus occurs in a heterogeneous environment filled with a high density of chromatins and thus it is inevitably influenced by interactions with chromatins. As a model system of nuclear body formation in a cell nucleus filled with chromatins, we simulate the phase separation of a low-density Lennard-Jones (LJ) fluid interacting with a long, condensed polymer chain. The influence of the density variation of LJ particles above and below the phase boundary and the role of attractive interactions between LJ particles and polymer segments are investigated at a fixed value of strong self-interaction between LJ particles. For a density of LJ particles above the phase boundary, phase separation occurs and a dense domain of LJ particles forms irrespective of interactions with the condensed polymer chain whereas its localization relative to the polymer chain is determined by the LJ-polymer attraction strength. Especially, in the case of moderately weak attractions, the domain forms separately from the polymer chain and subsequently associates with the polymer chain. When the density is below the phase boundary, however, the formation of a dense domain is possible only when the LJ-polymer attraction is strong enough, for which the domain grows in direct contact with the interacting polymer chain. In this work, different growth behaviors of LJ particles result from the differences in the density of LJ particles and in the LJ-polymer interaction, and this work suggests that the distinct formation of activity-dependent and activity-independent nuclear bodies (NBs) in a cell nucleus may originate from the differences in the concentrations of body-specific NB components and in their interaction with chromatins.

Docetaxel-loaded multilayer nanoparticles with nanodroplets for cancer therapy.

Science.gov (United States)

Oh, Keun Sang; Kim, Kyungim; Yoon, Byeong Deok; Lee, Hye Jin; Park, Dal Yong; Kim, Eun-Yeong; Lee, Kiho; Seo, Jae Hong; Yuk, Soon Hong

2016-01-01

A mixture of docetaxel (DTX) and Solutol(®) HS 15 (Solutol) transiently formed nanodroplets when it was suspended in an aqueous medium. However, nanodroplets that comprised DTX and Solutol showed a rapid precipitation of DTX because of their unstable characteristics in the aqueous medium. The incorporation of nanodroplets that comprised DTX and Solutol through vesicle fusion and subsequent stabilization was designed to prepare multilayer nanoparticles (NPs) with a DTX-loaded Solutol nanodroplet (as template NPs) core for an efficient delivery of DTX as a chemotherapeutic drug. As a result, the DTX-loaded Solutol nanodroplets (~11.7 nm) were observed to have an increased average diameter (from 11.7 nm to 156.1 nm) and a good stability of the hydrated NPs without precipitation of DTX by vesicle fusion and multilayered structure, respectively. Also, a long circulation of the multilayer NPs was observed, and this was due to the presence of Pluronic F-68 on the surface of the multilayer NPs. This led to an improved antitumor efficacy based on the enhanced permeation and retention effect. Therefore, this study indicated that the multilayer NPs have a considerable potential as a drug delivery system with an enhanced therapeutic efficacy by blood circulation and with low side effects.

Theoretical Studies Of Nucleation Kinetics And Nanodroplet Microstructure

International Nuclear Information System (INIS)

Wilemski, Gerald

2009-01-01

The goals of this project were to (1) explore ways of bridging the gap between fundamental molecular nucleation theories and phenomenological approaches based on thermodynamic reasoning, (2) test and improve binary nucleation theory, and (3) provide the theoretical underpinning for a powerful new experimental technique, small angle neutron scattering (SANS) from nanodroplet aerosols, that can probe the compositional structure of nanodroplets. This report summarizes the accomplishments of this project in realizing these goals. Publications supported by this project fall into three general categories: (1) theoretical work on nucleation theory (2) experiments and modeling of nucleation and condensation in supersonic nozzles, and (3) experimental and theoretical work on nanodroplet structure and neutron scattering. These publications are listed and briefly summarized in this report.

Spinning superfluid 4He nanodroplets

Science.gov (United States)

Ancilotto, Francesco; Barranco, Manuel; Pi, Martí

2018-05-01

We have studied spinning superfluid 4He nanodroplets at zero temperature using density functional theory. Due to the irrotational character of the superfluid flow, the shapes of the spinning nanodroplets are very different from those of a viscous normal fluid drop in steady rotation. We show that when vortices are nucleated inside the superfluid droplets, their morphology, which evolves from axisymmetric oblate to triaxial prolate to two-lobed shapes, is in good agreement with experiments. The presence of vortex arrays confers to the superfluid droplets the rigid-body behavior of a normal fluid in steady rotation, and this is the ultimate reason for the surprising good agreement between recent experiments and the classical models used for their description.

Analysis of the Efficiency of Surfactant-Mediated Stabilization Reactions of EGaIn Nanodroplets.

Science.gov (United States)

Finkenauer, Lauren R; Lu, Qingyun; Hakem, Ilhem F; Majidi, Carmel; Bockstaller, Michael R

2017-09-26

A methodology based on light scattering and spectrophotometry was developed to evaluate the effect of organic surfactants on the size and yield of eutectic gallium/indium (EGaIn) nanodroplets formed in organic solvents by ultrasonication. The process was subsequently applied to systematically evaluate the role of headgroup chemistry as well as polar/apolar interactions of aliphatic surfactant systems on the efficiency of nanodroplet formation. Ethanol was found to be the most effective solvent medium in promoting the formation and stabilization of EGaIn nanodroplets. For the case of thiol-based surfactants in ethanol, the yield of nanodroplet formation increased with the number of carbon atoms in the aliphatic part. In the case of the most effective surfactant system-octadecanethiol-the nanodroplet yield increased by about 370% as compared to pristine ethanol. The rather low overall efficiency of the reaction process along with the incompatibility of surfactant-stabilized EGaIn nanodroplets in nonpolar organic solvents suggests that the stabilization mechanism differs from the established self-assembled monolayer formation process that has been widely observed in nanoparticle formation.

Atomic Scale Imaging of Nucleation and Growth Trajectories of an Interfacial Bismuth Nanodroplet.

Science.gov (United States)

Li, Yingxuan; Bunes, Benjamin R; Zang, Ling; Zhao, Jie; Li, Yan; Zhu, Yunqing; Wang, Chuanyi

2016-02-23

Because of the lack of experimental evidence, much confusion still exists on the nucleation and growth dynamics of a nanostructure, particularly of metal. The situation is even worse for nanodroplets because it is more difficult to induce the formation of a nanodroplet while imaging the dynamic process with atomic resolution. Here, taking advantage of an electron beam to induce the growth of Bi nanodroplets on a SrBi2Ta2O9 platelet under a high resolution transmission electron microscope (HRTEM), we directly observed the detailed growth pathways of Bi nanodroplets from the earliest stage of nucleation that were previously inaccessible. Atomic scale imaging reveals that the dynamics of nucleation involves a much more complex trajectory than previously predicted based on classical nucleation theory (CNT). The monatomic Bi layer was first formed in the nucleation process, which induced the formation of the prenucleated clusters. Following that, critical nuclei for the nanodroplets formed both directly from the addition of atoms to the prenucleated clusters by the classical growth process and indirectly through transformation of an intermediate liquid film based on the Stranski-Krastanov growth mode, in which the liquid film was induced by the self-assembly of the prenucleated clusters. Finally, the growth of the Bi nanodroplets advanced through the classical pathway and sudden droplet coalescence. This study allows us to visualize the critical steps in the nucleation process of an interfacial nanodroplet, which suggests a revision of the perspective of CNT.

Docetaxel-loaded multilayer nanoparticles with nanodroplets for cancer therapy

Directory of Open Access Journals (Sweden)

Oh KS

2016-03-01

Full Text Available Keun Sang Oh,1,* Kyungim Kim,1,* Byeong Deok Yoon,1 Hye Jin Lee,1 Dal Yong Park,1 Eun-yeong Kim,1 Kiho Lee,1 Jae Hong Seo,2 Soon Hong Yuk1,2 1College of Pharmacy, Korea University, Sejong, 2Biomedical Research Center, Korea University Guro Hospital, Guro-gu, Seoul, Republic of Korea *These authors contributed equally to this work Abstract: A mixture of docetaxel (DTX and Solutol® HS 15 (Solutol transiently formed nanodroplets when it was suspended in an aqueous medium. However, nanodroplets that comprised DTX and Solutol showed a rapid precipitation of DTX because of their unstable characteristics in the aqueous medium. The incorporation of nanodroplets that comprised DTX and Solutol through vesicle fusion and subsequent stabilization was designed to prepare multilayer nanoparticles (NPs with a DTX-loaded Solutol nanodroplet (as template NPs core for an efficient delivery of DTX as a chemotherapeutic drug. As a result, the DTX-loaded Solutol nanodroplets (~11.7 nm were observed to have an increased average diameter (from 11.7 nm to 156.1 nm and a good stability of the hydrated NPs without precipitation of DTX by vesicle fusion and multilayered structure, respectively. Also, a long circulation of the multilayer NPs was observed, and this was due to the presence of Pluronic F-68 on the surface of the multilayer NPs. This led to an improved antitumor efficacy based on the enhanced permeation and retention effect. Therefore, this study indicated that the multilayer NPs have a considerable potential as a drug delivery system with an enhanced therapeutic efficacy by blood circulation and with low side effects. Keywords: multilayer nanoparticles, Solutol, Pluronic F-68, docetaxel, cancer therapy

Molecular dynamics calculation of half-lives for thermal decay of Lennard-Jones clusters

International Nuclear Information System (INIS)

Smith, R.W.

1991-01-01

Molecular dynamics has been used with a Lenard-Jones (6-12) potential in order to study the decay behavior of neutral Argon clusters containing between 12 and 14 atoms. The clusters were heated to temperatures well above their melting points and then tracked in time via molecular dynamics until evaporation of one or more atoms was observed. In each simulation, the mode of evaporation, energy released during evaporation, and cluster lifetime were recorded. Results from roughly 2000 simulation histories were combined in order to compute statistically significant values of cluster half-lives and decay energies. It was found that cluster half-life decreases with increasing energy and that for a given value of excess energy (defined as E=(E tot -E gnd )/n), the 13 atom cluster is more stable against decay than clusters containing either 12 or 14 atoms. The dominant decay mechanism for all clusters was determined to be single atom emission. (orig.)

Novel ultrasound-responsive chitosan/perfluorohexane nanodroplets for image-guided smart delivery of an anticancer agent: Curcumin.

Science.gov (United States)

Baghbani, Fatemeh; Chegeni, Mahdieh; Moztarzadeh, Fathollah; Hadian-Ghazvini, Samaneh; Raz, Majid

2017-05-01

Ultrasound-responsive nanodroplets are a class of new emerging smart drug delivery systems which provide image-guided nano-therapy of various diseases, especially cancers. Here, we developed multifunctional smart curcumin-loaded chitosan/perfluorohexane nanodroplets for contrast-ultrasound imaging and on-demand drug delivery. The nanodroplets were synthesized via nanoemulsion process. The optimal formulation with the size of 101.2nm and 77.8% curcumin entrapment was chosen for release study and cytotoxicity evaluation. Sonication at the frequency of 1MHz, 2W/cm 2 for 4min triggered the release of 63.5% of curcumin from optimal formulation (Cur-NDs-2). Ultrasound aided release study indicated that the concentration of perfluorohexane and the degree of acoustic droplet vaporization play important role in ultrasound-active drug release. B-mode ultrasound imaging confirmed strong ultrasound contrast of chitosan nanodroplets even at low concentrations via droplet to bubble transition. Finally, cytotoxicity of the ultrasound-responsive nanodroplets in the presence of ultrasound was evaluated in-vitro on 4T1 human breast cancer cells. Cell growth inhibitory effects of curcumin-loaded nanodroplets significantly increased by ultrasound exposure. According to the obtained results, these ultrasound responsive curcumin-loaded chitosan/perfluorohexane nanodroplets have a great potential for imaged-guided cancer therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular Dynamics Study of Thermally Augmented Nanodroplet Motion on Chemical Energy Induced Wettability Gradient Surfaces.

Science.gov (United States)

Chakraborty, Monojit; Chowdhury, Anamika; Bhusan, Richa; DasGupta, Sunando

2015-10-20

Droplet motion on a surface with chemical energy induced wettability gradient has been simulated using molecular dynamics (MD) simulation to highlight the underlying physics of molecular movement near the solid-liquid interface including the contact line friction. The simulations mimic experiments in a comprehensive manner wherein microsized droplets are propelled by the surface wettability gradient against forces opposed to motion. The liquid-wall Lennard-Jones interaction parameter and the substrate temperature are varied to explore their effects on the three-phase contact line friction coefficient. The contact line friction is observed to be a strong function of temperature at atomistic scales, confirming their experimentally observed inverse functionality. Additionally, the MD simulation results are successfully compared with those from an analytical model for self-propelled droplet motion on gradient surfaces.

Adhesive contact: from atomistic model to continuum model

International Nuclear Information System (INIS)

Fan Kang-Qi; Jia Jian-Yuan; Zhu Ying-Min; Zhang Xiu-Yan

2011-01-01

Two types of Lennard-Jones potential are widely used in modeling adhesive contacts. However, the relationships between the parameters of the two types of Lennard-Jones potential are not well defined. This paper employs a self-consistent method to derive the Lennard-Jones surface force law from the interatomic Lennard-Jones potential with emphasis on the relationships between the parameters. The effect of using correct parameters in the adhesion models is demonstrated in single sphere-flat contact via continuum models and an atomistic model. Furthermore, the adhesion hysteresis behaviour is investigated, and the S-shaped force-distance relation is revealed by the atomistic model. It shows that the adhesion hysteresis loop is generated by the jump-to-contact and jump-off-contact, which are illustrated by the S-shaped force-distance curve. (atomic and molecular physics)

Alternative Hamiltonian for molecular dynamics simulations in the grand canonical ensemble

International Nuclear Information System (INIS)

Lo, C.; Palmer, B.

1995-01-01

An alternative to the Hamiltonian of Cagin and Pettitt for performing molecular dynamics simulations in the grand canonical ensemble is presented and used as the basis for a new algorithm. The algorithm is tested on the ideal gas and the truncated and shifted Lennard-Jones fluid. Simulations are used to calculate the vapor--liquid coexistence points for the Lennard-Jones system and are found to be in agreement with previous calculations using Gibbs ensemble calculations and with the Nicolas equation of state. Simulations are also performed on the Lennard-Jones solid

Positron probe to study the freezing of nanodroplets

International Nuclear Information System (INIS)

Pujari, P.K.

2010-01-01

Positron is an excellent in situ probe to study the phase behavior of fluid confined in nanodomains. The study of phase behavior (freezing/melting) of nano confined fluid or nanodroplet has great relevance in fundamental research as well as applications in nano-tribology, nanofabrication, membrane separation, interfacial adhesion and lubrication. It is seen that the properties of freezing/melting of nanodroplets are different from their bulk behavior due to the combined effects of finite size, surface force, surface anisotropy, pore disorder and reduced dimensionality. We have used positron annihilation spectroscopy (PAS) to study the freezing/melting behavior of different organic liquids like benzene, ethylene glycol and isopropanol confined in nanopores of ZSM5 zeolite and silica gel

Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

Energy Technology Data Exchange (ETDEWEB)

Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR5150, Université de Pau et des Pays de l’Adour, B. P. 1155, Pau Cedex 64014 (France); Moreno-Ventas Bravo, A. I. [Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain)

2014-11-14

We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial

Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

International Nuclear Information System (INIS)

Martínez-Ruiz, F. J.; Blas, F. J.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.

2014-01-01

We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r c = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r c = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness

Femtosecond water dynamics in reverse-micellar nanodroplets

NARCIS (Netherlands)

Cringus, D; Lindner, J; Milder, MTW; Pshenichnikov, MS; Vohringer, P; Wiersma, DA; Milder, Maaike T.W.; Pshenichnikov, Maxim S.; Vöhringer, Peter

2005-01-01

Vibrational energy relaxation and ultrafast thermalization following impulsive excitation of the OH-stretching band of water nanodroplets confined to reverse micelles is studied by infrared pump-probe spectroscopy with sub-100 fs time resolution. The self-consistent analysis of experimental data for

Two-pulse driving of D+D nuclear fusion within a single Coulomb exploding nanodroplet

International Nuclear Information System (INIS)

Last, Isidore; Jortner, Joshua; Peano, Fabio; Silva, Luis O.

2010-01-01

This paper presents a computational study of D+D fusion driven by Coulomb explosion (CE) within a single, homonuclear deuterium nanodroplet, subjected to double-pulse ultraintense laser irradiation. This irradiation scheme results in the attainment (by the first weaker pulse) of a transient inhomogeneous density profile, which serves as a target for the driving (by the second superintense pulse) of nonuniform CE that triggers overrun effects and induces intrananodroplet (INTRA) D+D fusion. Scaled electron and ion dynamics simulations were utilized to explore the INTRA D+D fusion yields for double-pulse, near-infrared laser irradiation of deuterium nanodroplets. The dependence of the INTRA yield on the nanodroplet size and on the parameters of the two laser pulses was determined, establishing the conditions for the prevalence of efficient INTRA fusion. The INTRA fusion yields are amenable to experimental observation within an assembly of nanodroplets. The INTRA D+D fusion can be distinguished from the concurrent internanodroplet D+D fusion reaction occurring in the macroscopic plasma filament and outside it in terms of the different energies of the neutrons produced in these two channels.

The effect of the molecular mass on the sputtering by electrosprayed nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Borrajo-Pelaez, Rafael; Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu

2015-07-30

Highlights: • We study the effect of the molecular mass on nanodroplet sputtering of silicon. • The impact phenomenology is a strong function of the projectile’s molecular mass. • Nanodroplet sputtering intrinsically is a molecular scale phenomenon. - Abstract: Energetic bombardment of covalently bonded materials by electrosprayed nanodroplets causes sputtering and topographic changes on the surface of the target. This work investigates the influence of the projectile's molecular mass on these phenomena by sputtering single-crystal silicon wafers with a variety of liquids (molecular masses between 45.0 and 773.3 amu), and acceleration voltages. The electrosprays are characterized via time of flight to determine the charge to mass ratio of the nanodroplets which, together with the acceleration voltage, yield the impact velocity, the stagnation pressure, and the molecular kinetic energy of the projectile. The estimated range of droplet diameters is 20–79 nm, while the impact velocity, the stagnation pressure and the molecular kinetic energy range between 2.9–10 km/s, 4.7–63 GPa, and 2.1–98 eV. We find that the damage on the surface of the targets strongly depends on the molecular mass of the projectile: liquids with low molecular mass sputter significantly less and produce nanometric indentations and low surface roughness, the latter increasing moderately with stagnation pressure; in contrast, the roughness and sputtering caused by the impacts of droplets with larger molecular mass reach significantly higher values, and exhibit non-monotonic behaviors. The maximum sputtering yields for formamide, EAN, EMI-BF{sub 4}, EMI-Im, TES, and TPP are 0.20, 0.75, 1.20, 2.80, 4.00 and 2.90 silicon atoms per molecule in the projectile. These trends indicate that despite their rather large diameters, the sputtering by electrosprayed nanodroplets is intrinsically a molecular scale phenomenon.

GPU-accelerated Gibbs ensemble Monte Carlo simulations of Lennard-Jonesium

Science.gov (United States)

Mick, Jason; Hailat, Eyad; Russo, Vincent; Rushaidat, Kamel; Schwiebert, Loren; Potoff, Jeffrey

2013-12-01

This work describes an implementation of canonical and Gibbs ensemble Monte Carlo simulations on graphics processing units (GPUs). The pair-wise energy calculations, which consume the majority of the computational effort, are parallelized using the energetic decomposition algorithm. While energetic decomposition is relatively inefficient for traditional CPU-bound codes, the algorithm is ideally suited to the architecture of the GPU. The performance of the CPU and GPU codes are assessed for a variety of CPU and GPU combinations for systems containing between 512 and 131,072 particles. For a system of 131,072 particles, the GPU-enabled canonical and Gibbs ensemble codes were 10.3 and 29.1 times faster (GTX 480 GPU vs. i5-2500K CPU), respectively, than an optimized serial CPU-bound code. Due to overhead from memory transfers from system RAM to the GPU, the CPU code was slightly faster than the GPU code for simulations containing less than 600 particles. The critical temperature Tc∗=1.312(2) and density ρc∗=0.316(3) were determined for the tail corrected Lennard-Jones potential from simulations of 10,000 particle systems, and found to be in exact agreement with prior mixed field finite-size scaling calculations [J.J. Potoff, A.Z. Panagiotopoulos, J. Chem. Phys. 109 (1998) 10914].

Efficient and controllable thermal ablation induced by short-pulsed HIFU sequence assisted with perfluorohexane nanodroplets.

Science.gov (United States)

Chang, Nan; Lu, Shukuan; Qin, Dui; Xu, Tianqi; Han, Meng; Wang, Supin; Wan, Mingxi

2018-07-01

A HIFU sequence with extremely short pulse duration and high pulse repetition frequency can achieve thermal ablation at a low acoustic power using inertial cavitation. Because of its cavitation-dependent property, the therapeutic outcome is unreliable when the treatment zone lacks cavitation nuclei. To overcome this intrinsic limitation, we introduced perfluorocarbon nanodroplets as extra cavitation nuclei into short-pulsed HIFU-mediated thermal ablation. Two types of nanodroplets were used with perfluorohexane (PFH) as the core material coated with bovine serum albumin (BSA) or an anionic fluorosurfactant (FS) to demonstrate the feasibility of this study. The thermal ablation process was recorded by high-speed photography. The inertial cavitation activity during the ablation was revealed by sonoluminescence (SL). The high-speed photography results show that the thermal ablation volume increased by ∼643% and 596% with BSA-PFH and FS-PFH, respectively, than the short-pulsed HIFU alone at an acoustic power of 19.5 W. Using nanodroplets, much larger ablation volumes were created even at a much lower acoustic power. Meanwhile, the treatment time for ablating a desired volume significantly reduced in the presence of nanodroplets. Moreover, by adjusting the treatment time, lesion migration towards the HIFU transducer could also be avoided. The SL results show that the thermal lesion shape was significantly dependent on the inertial cavitation in this short-pulsed HIFU-mediated thermal ablation. The inertial cavitation activity became more predictable by using nanodroplets. Therefore, the introduction of PFH nanodroplets as extra cavitation nuclei made the short-pulsed HIFU thermal ablation more efficient by increasing the ablation volume and speed, and more controllable by reducing the acoustic power and preventing lesion migration. Copyright © 2018. Published by Elsevier B.V.

Dynamical phases of attractive particles sliding on a structured surface

International Nuclear Information System (INIS)

Hasnain, J; Jungblut, S; Dellago, C

2015-01-01

Inspired by experiments on quartz crystal microbalance setups, we study the mobility of a monolayer of Lennard-Jones particles driven over a hexagonal external potential. We pay special attention to the changes in the dynamical phases that arise when the lattice constant of the external substrate potential and the Lennard-Jones interaction are mismatched. We find that if the average particle separation is such that the particles repel each other, or interact harmonically, the qualitative behavior of the system is akin to that of a monolayer of purely repulsive Yukawa particles. On the other hand, if the particles typically attract each other, the ensuing dynamical states are determined entirely by the relative strength of the Lennard-Jones interaction with respect to that of the external potential. (paper)

A Nanodroplet Processor for Advanced Microencapsulated Drug Formulations, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The objective of this proposal is to provide a demonstration of a nanodroplet synthesis of multifunctional liposomes for drug delivery based on immiscible...

A Nanodroplet Processor for Advanced Microencapsulated Drug Formulations, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — During this Phase II program we propose to build on the key aspects of the nanodroplet encapsulation technology to demonstrate optimized formulation and...

Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law

Science.gov (United States)

Zhu, Xinyao; Xu, Wei

2018-02-01

The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.

Koltunud Indiana Jones / Kutt Kommel

Index Scriptorium Estoniae

Kommel, Kutt

2008-01-01

Steven Spielbergi neljas Indiana Jones'i film Harrison Fordiga nimiosas "Indiana Jones ja kristallpealuu kuningriik" ("Indiana Jones and the Kingdom of the Crystal Skull") : Ameerika Ühendriigid 2008

Thermophoretic transport of water nanodroplets confined in carbon nanotubes: the role of friction

DEFF Research Database (Denmark)

Oyarzua, Elton; Walther, Jens Honore; Zambrano, Harvey

The development of efficient nanofluidic devices requires driving mechanisms that provide controlled transport of fluids through nanoconduits. Temperature gradients have been proposed as a mechanism to drive particles, fullerenes and nanodroplets inside carbon nanotubes (CNTs). In this work, molecular...... dynamics (MD) simulations are conducted to study thermophoresis of water nanodroplets inside CNTs. To gain insight into the interplay between the thermophoretic force acting on the droplet and the retarding liquid-solid friction, sets of constrained and unconstrained MD simulations are conducted...

Targeted drug delivery with focused ultrasound-induced blood-brain barrier opening using acoustically-activated nanodroplets.

Science.gov (United States)

Chen, Cherry C; Sheeran, Paul S; Wu, Shih-Ying; Olumolade, Oluyemi O; Dayton, Paul A; Konofagou, Elisa E

2013-12-28

Focused ultrasound (FUS) in the presence of systemically administered microbubbles has been shown to locally, transiently and reversibly increase the permeability of the blood-brain barrier (BBB), thus allowing targeted delivery of therapeutic agents in the brain for the treatment of central nervous system diseases. Currently, microbubbles are the only agents that have been used to facilitate the FUS-induced BBB opening. However, they are constrained within the intravascular space due to their micron-size diameters, limiting the delivery effect at or near the microvessels. In the present study, acoustically-activated nanodroplets were used as a new class of contrast agents to mediate FUS-induced BBB opening in order to study the feasibility of utilizing these nanoscale phase-shift particles for targeted drug delivery in the brain. Significant dextran delivery was achieved in the mouse hippocampus using nanodroplets at clinically relevant pressures. Passive cavitation detection was used in the attempt to establish a correlation between the amount of dextran delivered in the brain and the acoustic emission recorded during sonication. Conventional microbubbles with the same lipid shell composition and perfluorobutane core as the nanodroplets were also used to compare the efficiency of an FUS-induced dextran delivery. It was found that nanodroplets had a higher BBB opening pressure threshold but a lower stable cavitation threshold than microbubbles, suggesting that contrast agent-dependent acoustic emission monitoring was needed. A more homogeneous dextran delivery within the targeted hippocampus was achieved using nanodroplets without inducing inertial cavitation or compromising safety. Our results offered a new means of developing the FUS-induced BBB opening technology for potential extravascular targeted drug delivery in the brain, extending the potential drug delivery region beyond the cerebral vasculature. © 2013.

Diffusion processes and memory effects

International Nuclear Information System (INIS)

Mokshin, Anatolii V; Yulmetyev, Renat M; Haenggi, Peter

2005-01-01

We report the results of the numerical estimation of statistical memory effects in diffusion for two various systems: Lennard-Jones fluids and the model of the Brownian particle in a one-dimensional harmonic lattice. We have found the relation between the diffusion coefficient and the non-Markovity parameter, which is linear for the Lennard-Jones systems in liquid state. The relation between the memory measure and the excess entropy is also discussed here

Electron driven water formation from oxyhydrogen clusters in superfluid helium nanodroplets

International Nuclear Information System (INIS)

Renzler, Michael; Kranabetter, Lorenz; Barwa, Erik; Scheier, Paul; Illenberger, Eugen

2015-01-01

Helium nanodroplets provide an enviroment that allow studies of chemical reactions at ultracold temperatures. We use these droplets as a matrix to study the formation of water upon electron bombardment of oxyhydrogen clusters (paper)

Daniel Jones

DEFF Research Database (Denmark)

underrated, impact on the American structuralist school. This eight volume collection makes available the first editions of Jones' standard books, i.e. The Pronunciation of English (1909), An English Pronouncing Dictionary (1917) and An Outline of English Phonetics (1918). In addition, Jones' crucial...... pioneering works, now out of print for many decades, are made easily accessible to scholars once again. Numerous articles encompassing a variety of phonetic/phonological topics, for example, phonemic analysis, juncture, models of pronunciation, and historiography, are also included (converted where necessary...

Low pressure broadening and shift of the 540.06 nm line of neon

International Nuclear Information System (INIS)

Bielski, A.; Dokurno, W.; Szudy, J.; Wolnikowski, J.

1980-01-01

The collision broadening and shift of the 540.06 nm line of neon emitted from a low pressure glow discharge in pure neon and a neon-helium mixture have been measured. The values of the broadening and shift coefficients were determined and compared with the results of calculations based on the Lindholm-Foley impact theory assuming a Lennard-Jones potential. The results for pure neon demonstrate the inadequacy of the Lennard-Jones potential for the Ne-Ne interaction. (orig.)

Addendum to ''Density fluctuations in liquid rubidium''

International Nuclear Information System (INIS)

Haan, S.W.; Mountain, R.D.; Hsu, C.S.; Rahman, A.

1980-01-01

We performed molecular-dynamics simulations of liquid rubidium and the Lennard-Jones fluid at several densities and temperatures, and of a system whose pair potential is the repulsive core of the rubidium potential. In all cases, propagating density fluctuations occurred in the rubidiumlike systems at much shorter wavelengths than in the Lennard-Jones system. This indicates that the repulsive part of the pair potential is the dominant factor in determining the relaxation of short-wavelength density fluctuations

Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

DEFF Research Database (Denmark)

Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

2013-01-01

We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

Laser Photochemistry.

Science.gov (United States)

1981-07-01

inverted by the first, i.e., at the moment of time t = T, such that i = (2n+)lT, where 0 is the Rabi frequency (Oraevski et al., 1976). . classical... anisotropic molecule present. CW HeNe, Ar+ and Kr+ lasers are used, and the filter method is necessary because of time-scales lo8 - 10ll Hz. Some general...e.g., truncated harmonic oscillator, square well, spherically symmetric Morse or Lennard-Jones, anisotropic (angle-dependent) Morse or Lennard-Jones

Calculation of thermal-diffusion coefficients from plane-wave fluctuations in the heat energy density

International Nuclear Information System (INIS)

Palmer, B.J.

1994-01-01

A method to calculate the thermal diffusivity D T from spontaneous fluctuations in the local heat energy density is presented. Calculations of the thermal diffusivity are performed for the Lennard-Jones fluid, carbon dioxide, and water. The results for the Lennard-Jones fluid are in agreement with calculations of the thermal conductivity using Green-Kubo relations and nonequilibrium molecular-dynamics techniques. The results for carbon dioxide and water give thermal diffusivities within a factor of 2 of the experimental values

Adsorption of metal atoms at a buckled graphene grain boundary using model potentials

International Nuclear Information System (INIS)

Helgee, Edit E.; Isacsson, Andreas

2016-01-01

Two model potentials have been evaluated with regard to their ability to model adsorption of single metal atoms on a buckled graphene grain boundary. One of the potentials is a Lennard-Jones potential parametrized for gold and carbon, while the other is a bond-order potential parametrized for the interaction between carbon and platinum. Metals are expected to adsorb more strongly to grain boundaries than to pristine graphene due to their enhanced adsorption at point defects resembling those that constitute the grain boundary. Of the two potentials considered here, only the bond-order potential reproduces this behavior and predicts the energy of the adsorbate to be about 0.8 eV lower at the grain boundary than on pristine graphene. The Lennard-Jones potential predicts no significant difference in energy between adsorbates at the boundary and on pristine graphene. These results indicate that the Lennard-Jones potential is not suitable for studies of metal adsorption on defects in graphene, and that bond-order potentials are preferable

Focused ultrasound-facilitated brain drug delivery using optimized nanodroplets: vaporization efficiency dictates large molecular delivery

Science.gov (United States)

Wu, Shih-Ying; Fix, Samantha M.; Arena, Christopher B.; Chen, Cherry C.; Zheng, Wenlan; Olumolade, Oluyemi O.; Papadopoulou, Virginie; Novell, Anthony; Dayton, Paul A.; Konofagou, Elisa E.

2018-02-01

Focused ultrasound with nanodroplets could facilitate localized drug delivery after vaporization with potentially improved in vivo stability, drug payload, and minimal interference outside of the focal zone compared with microbubbles. While the feasibility of blood-brain barrier (BBB) opening using nanodroplets has been previously reported, characterization of the associated delivery has not been achieved. It was hypothesized that the outcome of drug delivery was associated with the droplet’s sensitivity to acoustic energy, and can be modulated with the boiling point of the liquid core. Therefore, in this study, octafluoropropane (OFP) and decafluorobutane (DFB) nanodroplets were used both in vitro for assessing their relative vaporization efficiency with high-speed microscopy, and in vivo for delivering molecules with a size relevant to proteins (40 kDa dextran) to the murine brain. It was found that at low pressures (300-450 kPa), OFP droplets vaporized into a greater number of microbubbles compared to DFB droplets at higher pressures (750-900 kPa) in the in vitro study. In the in vivo study, successful delivery was achieved with OFP droplets at 300 kPa and 450 kPa without evidence of cavitation damage using ¼ dosage, compared to DFB droplets at 900 kPa where histology indicated tissue damage due to inertial cavitation. In conclusion, the vaporization efficiency of nanodroplets positively impacted the amount of molecules delivered to the brain. The OFP droplets due to the higher vaporization efficiency served as better acoustic agents to deliver large molecules efficiently to the brain compared with the DFB droplets.

Contact angle hysteresis and motion behaviors of a water nano-droplet on suspended graphene under temperature gradient

Science.gov (United States)

Foroutan, Masumeh; Fatemi, S. Mahmood; Esmaeilian, Farshad; Fadaei Naeini, Vahid; Baniassadi, Majid

2018-05-01

In the present work, the effect of temperature gradient on the behavior of a water nano-droplet resting on a suspended graphene was studied based on a non-equilibrium molecular dynamics simulation. The acquired results indicate that the applied temperature gradient to the suspended graphene drives the water nano-droplet to the colder region. The droplet accelerates its motion toward the cold reservoir as the temperature gradient is increased. In addition to the translational motion of the nano-droplet, the vortical motion of the water molecules was also observed. Contact angle analysis was also utilized to describe the directional motion of the nano-droplet. The translational motion of the droplet leads to the estimation of contact angle hysteresis through advancing and receding contact angles while the rotational motion resulted in the advancing and receding fronts being switched with one another through the simulation. The average displacement vector of the water molecules shows that parts of the droplet seem to stagnate while other parts rotate around them. The reason behind this particular behavior was studied based on interaction energy contours between a water molecule and the suspended graphene. The obtained data indicate that the rotational motion is in agreement with the migration of the water molecules to low interaction energy regions in order to avoid high interaction energy areas.

Indiana Jones ja kristallpealuu kuningriik / Jaanus Noormets

Index Scriptorium Estoniae

Noormets, Jaanus

2008-01-01

Steven Spielbergi neljas Indiana Jones'i film Harrison Fordiga nimiosas "Indiana Jones ja kristallpealuu kuningriik" ("Indiana Jones and the Kingdom of the Crystal Skull") : Ameerika Ühendriigid 2008

The Jones Family's Culture of Literacy

Science.gov (United States)

Johnson, Amy Suzanne

2010-01-01

This article considers the uses of literacy within the Jones family (all names are pseudonyms), an African American family who lives in the rural South of the United States. Drawing on life history data with three women in the Jones family--Harriet Jones (grandmother), Sally Harris (mother), and Lola Harris (granddaughter)--the author traces how…

Tagging, Encoding, and Jones Optimality

DEFF Research Database (Denmark)

Danvy, Olivier; López, Pablo Ernesto Martínes

2003-01-01

A partial evaluator is said to be Jones-optimal if the result of specializing a self-interpreter with respect to a source program is textually identical to the source program, modulo renaming. Jones optimality has already been obtained if the self-interpreter is untyped. If the selfinterpreter...... is typed, however, residual programs are cluttered with type tags. To obtain the original source program, these tags must be removed. A number of sophisticated solutions have already been proposed. We observe, however, that with a simple representation shift, ordinary partial evaluation is already Jones...

Magnetoelectric Jones dichroism

International Nuclear Information System (INIS)

Andrews, D L; Daniels, G J; Stedman, G E

2003-01-01

Recent work on liquids has verified a novel magnetoelectrical birefringence predicted by Jones. Co-present static electric and magnetic fields generate a differential response to optical polarizations positively or negatively tilted against a plane orthogonal to the one containing the static field vectors. Reports indicated a dichroic counterpart; establishing its theory is the present aim. Results are trilinearly dependent on the irradiance, and the static electric and magnetic fields. For isotropic fluids a scalar quantifies propensity for Jones dichroism. In field-polarized fluids a second scalar also contributes; temperature dependence enables determination of both parameters. (letter to the editor)

Interaction of SO2 with the Surface of a Water Nanodroplet.

Science.gov (United States)

Zhong, Jie; Zhu, Chongqin; Li, Lei; Richmond, Geraldine L; Francisco, Joseph S; Zeng, Xiao Cheng

2017-11-29

We present a comprehensive computational study of interaction of a SO 2 with water molecules in the gas phase and with the surface of various sized water nanodroplets to investigate the solvation behavior of SO 2 in different atmospheric environments. Born-Oppenheimer molecular dynamics (BOMD) simulation shows that, in the gas phase and at a temperature of 300 K, the dominant interaction between SO 2 and H 2 O is (SO 2 ) S···O (H 2 O) , consistent with previous density-functional theory (DFT) computation at 0 K. However, at the surface of a water nanodroplet, BOMD simulation shows that the hydrogen-bonding interaction of (SO 2 ) O···H (H 2 O) becomes increasingly important with the increase of droplet size, reflecting a marked effect of the water surface on the SO 2 solvation. This conclusion is in good accordance with spectroscopy evidence obtained previously (J. Am. Chem. Soc. 2005, 127, 16806; J. Am. Chem. Soc. 2006, 128, 3256). The prevailing interaction (SO 2 ) O···H (H 2 O) on a large droplet is mainly due to favorable exposure of H atoms of H 2 O at the air-water interface. Indeed, the conversion of the dominant interaction in the gas phase (SO 2 ) S···O (H 2 O) to the dominant interaction on the water nanodroplet (SO 2 ) O···H (H 2 O) may incur effects on the SO 2 chemistry in atmospheric aerosols because the solvation of SO 2 at the water surface can affect the reactive sites and electrophilicity of SO 2 . Hence, the solvation of SO 2 on the aerosol surface may have new implications when studying SO 2 chemistry in the aerosol-containing troposphere.

Equation of state of a hard core fluid with a two-Yukawa tail: toward a simple analytic theory

International Nuclear Information System (INIS)

Jedrzejek, C.

1980-01-01

Thermodynamic properties of simple fluids are calculated using variational theory for a system of hard-core potential with a two-Yukawa tail. Likewise one Yukawa-tail case the working formulas are analytic. Five parameters of the two Yukawa system are chosen so as to get the best fit to a real argon potential or an ''argon-like'' Lennard-Jones potential. The results are fairly good in light of the extreme simplicity of the method. The discrepancies result from using the variational method and a different shape of Yukawa type potential in comparision to the real argon and Lennard-Jones potentials. (author)

Dipole moments of molecules solvated in helium nanodroplets

International Nuclear Information System (INIS)

Stiles, Paul L.; Nauta, Klaas; Miller, Roger E.

2003-01-01

Stark spectra are reported for hydrogen cyanide and cyanoacetylene solvated in helium nanodroplets. The goal of this study is to understand the influence of the helium solvent on measurements of the permanent electric dipole moment of a molecule. We find that the dipole moments of the helium solvated molecules, calculated assuming the electric field is the same as in vacuum, are slightly smaller than the well-known gas-phase dipole moments of HCN and HCCCN. A simple elliptical cavity model quantitatively accounts for this difference, which arises from the dipole-induced polarization of the helium

Helium nanodroplets. Pump-probe ionization of alkali dopings and spin-echo scattering on undoped drops

International Nuclear Information System (INIS)

Droppelmann, G.

2005-09-01

In the framework of this thesis several aspects of the properties of helium nanodroplets and their dopings. The formation of the exciplexes RbHe and KHe on helium droplets was studied by means of pump-probe ionization in real time, whereby the main interest lied on the influence of the applied helium isotopes. The experiments with cesium atoms on the droplet surface aimed on the elucidation of the relaxation dynamics of the surface under regardment both of isotope and size effects. From the pump-probe measurements on the formation of the exciplex RbHe on helium nanodroplets performed in the framework of this thesis formation times of 8.5 ps for Rb 4 He and 11.6 ps for Rb 3 He resulted

Electron attachment and electron ionization of acetic acid clusters embedded in helium nanodroplets

NARCIS (Netherlands)

da Silva, F. Ferreira; Jaksch, S.; Martins, G.; Dang, H. M.; Dampc, M.; Denifl, S.; Maerk, T. D.; Limao-Vieira, P.; Liu, J.; Yang, S.; Ellis, A. M.; Scheier, P.

2009-01-01

The effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic products ejected into the gas phase are detected by mass spectrometry. The cation chemistry (induced by

Phase transitions of quadrupolar fluids

International Nuclear Information System (INIS)

OShea, S.F.; Dubey, G.S.; Rasaiah, J.C.

1997-01-01

Gibbs ensemble simulations are reported for Lennard-Jones particles with embedded quadrupoles of strength Q * =Q/(εσ 5 ) 1/2 =2.0 where ε and σ are the Lennard-Jones parameters. Calculations revealing the effect of the dispersive forces on the liquid endash vapor coexistence were carried out by scaling the attractive r -6 term in the Lennard-Jones pair potential by a factor λ ranging from 0 to 1. Liquid endash vapor coexistence is observed for all values of λ including λ=0 for Q * =2.0, unlike the corresponding dipolar fluid studied by van Leeuwen and Smit et al. [Phys. Rev. Lett. 71, 3991 (1993)] which showed no phase transition below λ=0.35 when the reduced dipole moment μ * =2.0. The simulation data are analyzed to estimate the critical properties of the quadrupolar fluid and their dependence on the strength λ of the dispersive force. The critical temperature and pressure show a clear quadratic dependence on λ, while the density is less confidently identified as being linear in λ. The compressibility is roughly linear in λ. copyright 1997 American Institute of Physics

‘Men zou Virgilius zien opgaen in zijn’ tolck’. De functie van Vergilius in het artistiek ondernemerschap van Joost van den Vondel

Directory of Open Access Journals (Sweden)

Sophie Reinders

2012-03-01

Full Text Available This article analyzes Joost van den Vondel's career strategies and shows that the ambition for obtaining patronage as a poet played a crucial role in the dedications of his consecutive Vergil translations. In the period 1646-1660 Vondel published three Dutch translations of Vergil, one in prose, one 'preview' of the poetry translation, and a final translation of the complete works rendered in verse. For each of the individual dedicatees, the Prince of Orange, the son of the Amsterdam burgomaster Cornelis de Graeff, and the mighty burgomaster himself, the publications' paratexts work to achieve a single goal by means of this work of art: obtaining structural patronage for composing an epic.

Tagging, Encoding, and Jones Optimality

DEFF Research Database (Denmark)

Danvy, Olivier; Lopez, Pablo E. Martinez

2003-01-01

A partial evaluator is said to be Jones-optimal if the result of specializing a self-interpreter with respect to a source program is textually identical to the source program, modulo renaming. Jones optimality has already been obtained if the self-interpreter is untyped. If the selfinterpreter...... is typed, however, residual programs are cluttered with type tags. To obtain the original source program, these tags must be removed. A number of sophisticated solutions have already been proposed. We observe, however, that with a simple representation shift, ordinary partial evaluation is already Jones......-optimal, modulo an encoding. The representation shift amounts to reading the type tags as constructors for higherorder abstract syntax. We substantiate our observation by considering a typed self-interpreter whose input syntax is higher-order. Specializing this interpreter with respect to a source program yields...

Docetaxel-loaded multilayer nanoparticles with nanodroplets for cancer therapy

OpenAIRE

Oh, Keun Sang; Kim, Kyungim; Yoon, Byeong Deok; Lee, Hye Jin; Park, Dal Yong; Kim, Eun-yeong; Lee, Kiho; Seo, Jae Hong; Yuk, Soon Hong

2016-01-01

Keun Sang Oh,1,* Kyungim Kim,1,* Byeong Deok Yoon,1 Hye Jin Lee,1 Dal Yong Park,1 Eun-yeong Kim,1 Kiho Lee,1 Jae Hong Seo,2 Soon Hong Yuk1,2 1College of Pharmacy, Korea University, Sejong, 2Biomedical Research Center, Korea University Guro Hospital, Guro-gu, Seoul, Republic of Korea *These authors contributed equally to this work Abstract: A mixture of docetaxel (DTX) and Solutol® HS 15 (Solutol) transiently formed nanodroplets when it was suspended in an aqueous medium. However, n...

Tubo de Lester-Jones: indicações e resultados Lester-Jones tube: indications and results

Directory of Open Access Journals (Sweden)

Walberto Passos Junior

2004-12-01

Full Text Available OBJETIVO: Avaliar as indicações, resultados e complicações advindas do seu uso. MÉTODOS: Avaliaram-se retrospectivamente 25 pacientes submetidos a 27 conjuntivorrinostomias com colocação de tubo de Lester-Jones. Foram estudados os dados do portador, a etiologia da afecção e as complicações que ocorreram no intra e no pós-operatório. Os dados foram avaliados segundo a freqüência de ocorrência. RESULTADOS: O tubo de Lester-Jones foi usado igualmente em ambos os sexos, mais em indivíduos abaixo dos 10 ou acima dos 50 anos de idade. As causas mais freqüentes para utilização foram a idiopática ou a agenesia congênita de pontos e canalículos. Houve melhora dos sintomas em 88% dos pacientes. Complicações ocorreram em 59,25% dos casos, dentre as quais: extrusão (40,74% e a migração (14,8% do tubo. CONCLUSÃO: Apesar das complicações observadas, o índice de cura com a utilização do tubo de Lester-Jones é alto, sendo boa opção para o tratamento das obstruções lacrimais altas.PURPOSE: To evaluate the results and the complications occurring with this procedure. METHODS: The authors retrospectively reviewed charts of 25 patients (27 lacrimal viers with upper lacrimal system obstruction who underwent conjunctivorhinostomy and Lester-Jones tube bypass. The patients were evaluated according to gender, causative factors and the com plications during and after surgery. The data were submitted to statistical analysis. RESULTS: The Lester-Jones bypass tube was used in both sexes and most frequently in patients under 10 or above 50 years. The most common obstructive factor was unknown and congenital agenesis. Eighty-eight per cent of the patients had no epiphora at the end of the treatment. Complications occurred in 59.25% of the patients, most of them related to tube extrusion (40.74% or migration (14.8%. The authors concluded that the Lester-Jones bypass tube is a good option to treat the upper lacrimal obstruction, in spite

Molecular dynamics study of vacancy-like defects in a model glass : static behaviour

Science.gov (United States)

Delaye, J. M.; Limoge, Y.

1993-10-01

The possibility of defining vacancy-like defects in a Lennard-Jones glass is searched for in a systematic manner. Considering different relaxation levels of the same system, as well as different external pressures, we use a Molecular Dynamics simulation method, to study at constant volume or external pressure, the relaxation of a “piece” of glass, after the sudden removal of an atom. Three typical kinds of behaviour can be observed: the persistence of the empty volume left by the missing atom, its migration by clearly identifiable atomic jumps and the dissipation “on the spot”. A careful analysis of the probabilities of these three kinds of behaviour shows that a meaningful definition of vacancy-like defects can be given in a Lennard-Jones glass. Dans cet article, nous nous penchons de façon systématique sur la possibilité de définir des défauts de type lacunaire dans un verre de Lennard-Jones, à différents niveaux de relaxation et de pression, par une méthode de simulation numérique en dynamique moléculaire à volume ou à pression constants. Le défaut est créé en supprimant un atome et en suivant la réponse du système. Nous observons trois comportements typiques : la persistance sur place du “trou” laissé par l'atome supprimé, sa migration par des sauts atomiques clairement identifiés et enfin sa dissipation sur place. Une analyse détaillée de ces trois comportements montre qu'il est possible dans un verre de Lennard-Jones de définir des défauts de type lacunaire.

Resolving dispersion and induction components for polarisable molecular simulations of ionic liquids

Science.gov (United States)

Pádua, Agílio A. H.

2017-05-01

One important development in interaction potential models, or atomistic force fields, for molecular simulation is the inclusion of explicit polarisation, which represents the induction effects of charged or polar molecules on polarisable electron clouds. Polarisation can be included through fluctuating charges, induced multipoles, or Drude dipoles. This work uses Drude dipoles and is focused on room-temperature ionic liquids, for which fixed-charge models predict too slow dynamics. The aim of this study is to devise a strategy to adapt existing non-polarisable force fields upon addition of polarisation, because induction was already contained to an extent, implicitly, due to parametrisation against empirical data. Therefore, a fraction of the van der Waals interaction energy should be subtracted so that the Lennard-Jones terms only account for dispersion and the Drude dipoles for induction. Symmetry-adapted perturbation theory is used to resolve the dispersion and induction terms in dimers and to calculate scaling factors to reduce the Lennard-Jones terms from the non-polarisable model. Simply adding Drude dipoles to an existing fixed-charge model already improves the prediction of transport properties, increasing diffusion coefficients, and lowering the viscosity. Scaling down the Lennard-Jones terms leads to still faster dynamics and densities that match experiment extremely well. The concept developed here improves the overall prediction of density and transport properties and can be adapted to other models and systems. In terms of microscopic structure of the ionic liquids, the inclusion of polarisation and the down-scaling of Lennard-Jones terms affect only slightly the ordering of the first shell of counterions, leading to small decreases in coordination numbers. Remarkably, the effect of polarisation is major beyond first neighbours, significantly weakening spatial correlations, a structural effect that is certainly related to the faster dynamics of

STS-98 Crew Interview: Tom Jones

Science.gov (United States)

2001-01-01

The STS-98 Mission Specialist Tom Jones is seen being interviewed. He answers questions about his inspiration to become an astronaut, his career path, and his training. He gives details on the mission's goals and significance, and the payload and hardware it brings to the International Space Station (ISS). Mr. Jones discusses his role in the mission's spacewalks and activities.

God as burden: A theological reflection on art, death and God in the work of Joost Zwagerman

Directory of Open Access Journals (Sweden)

Rein Brouwer

2017-06-01

Full Text Available In one of his essays on art, Dutch author and essayist Joost Zwagerman (1963–2015 reflects onthe work of (Dutch South African artist Marlene Dumas (1953. Zwagerman addresses inparticular Dumas’ My Mother Before She Became My Mother (2010, painted 3 years after hermother died. In his reflections, Zwagerman proposes an interpretation of Dumas’ work. Hesuggests that Dumas, in her art, does not accept the omnipotence of death. Maybe againstbetter judgement, but Dumas keeps creating images that not only illustrate the desire formeaning but also embody this desire. The image and the desire for meaning merge in Dumas’paintings. The painting itself becomes an autonomous ‘desire machine’, according toZwagerman. In this article, a (practical theological reading of Zwagerman’s own posthumouslypublished volume of poetry, ‘Wakend over God’ (2016, is presented, with a specific interest inart, death and God. The sacramental hermeneutics of Richard Kearney and the theopoetics ofJohn Caputo are brought into the conversation to elicit the dimensions of faith and religion inZwagerman’s own ‘desire machine’.

The Performance of Dow Jones Country Islamic Indexes Against Dow Jones Country Conventional Indexes in Asia and the Middle East : An Empirical Study of the Last Decade

OpenAIRE

Suharwardy, Zain

2013-01-01

This paper attempts to examine the performance of six countries spanning from Asia and the Middle East. Countries are selected from the Dow Jones Islamic Market Index and the focus is kept to only choose countries that have an active Dow Jones Islamic Market Country Index along with a parallel Dow Jones Conventional Country Index. Further break down is made by comparing the country performances to their respective Dow Jones regional index’s (Dow Jones Asia Index and the Dow Jones MENA) in ord...

Influence of pressure on the crystallization of systems characterized by different intermolecular attraction

Science.gov (United States)

Koperwas, K.; Affouard, F.; Gerges, J.; Valdes, L.-C.; Adrjanowicz, K.; Paluch, M.

2017-12-01

In this paper, we examine, in terms of the classical nucleation theory, how the strengthening of the attractive intermolecular interactions influences the crystallization process for systems like Lennard-Jones at different isobaric conditions. For this purpose, we modify the standard Lennard-Jones potential, and as a result, we obtain three different systems characterized by various strengths of attractive potentials occurring between molecules, which are in direct relationship to the physical quantities describing molecules, e.g., its polarizability or dipole moment. Based on performed analysis, we demonstrate that the molecular attraction primarily impacts the thermodynamics of the interface between liquid and crystal. This is reflected in the behavior of nucleation and overall crystallization rates during compression of the system.

Graphene on Cu(111) at the nonzero temperatures: Molecular dynamic simulation

Science.gov (United States)

Sidorenkov, A. V.; Kolesnikov, S. V.; Saletsky, A. M.

2017-11-01

We present results of molecular dynamic simulation of continuous graphene monolayer on Cu(111). In this paper, we investigate the dependencies of the average binding energy and the average binding distance on the temperature. The interaction between carbon and copper atoms was described by Lennard-Jones potential. It is shown that the binding energy practically remains constant in a wide range of temperatures 0-800 K. However, in the same temperature range, the binding distance of graphene on Cu(111) surface has a linear dependence on temperature. The dependence of the linear thermal expansion coefficient of the binding distance on Lennard-Jones parameters has been calculated. We suggest a simple theoretical model to explain this dependence qualitatively.

Dislocation-like Structures in a Simulated Liquid

DEFF Research Database (Denmark)

Cotterill, Rodney M J

1979-01-01

The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times. If the ch......The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times....... If the chains are interpreted as dislocation cores, the observed dislocation density is 1.0×1014 cm-2, but the actual density is probably higher....

The non-separability of ''dielectric'' and ''mechanical'' friction in molecular systems: A simulation study

International Nuclear Information System (INIS)

Kumar, P. V.; Maroncelli, M.

2000-01-01

Simulations of the time-dependent friction controlling rotational, translational, and vibrational motions of dipolar diatomic solutes in acetonitrile and methanol have been used to examine the nature of ''dielectric'' friction. The way in which electrical interactions increase the friction beyond that present in nonpolar systems is found to be rather different than what is anticipated by most theories of dielectric friction. Long-range electrostatic forces do not simply add an independent contribution to the friction due to short-ranged or ''mechanical'' sources (modeled here in terms of Lennard-Jones forces). Rather, the electrical and Lennard-Jones contributions are found to be strongly anticorrelated and not separable in any useful way. For some purposes, the mechanism by which electrical interactions increase friction is better viewed as a static electrostriction effect: electrical forces cause a subtle increase in atomic density in the solute's first solvation shell, which increases the amplitude of the force fluctuations derived from the Lennard-Jones interactions, i.e., the mechanical friction. However, electrical interactions also modify the dynamics of the friction, typically adding a long-time tail, which significantly increases the integral friction. Both of these effects must be included in a correct description of friction in the presence of polar interactions. (c) 2000 American Institute of Physics

Communication: X-ray coherent diffractive imaging by immersion in nanodroplets

Directory of Open Access Journals (Sweden)

Rico Mayro P. Tanyag

2015-09-01

Full Text Available Lensless x-ray microscopy requires the recovery of the phase of the radiation scattered from a specimen. Here, we demonstrate a de novo phase retrieval technique by encapsulating an object in a superfluid helium nanodroplet, which provides both a physical support and an approximate scattering phase for the iterative image reconstruction. The technique is robust, fast-converging, and yields the complex density of the immersed object. Images of xenon clusters embedded in superfluid helium droplets reveal transient configurations of quantum vortices in this fragile system.

Magnetoelectric Jones spectroscopy of alkali atoms

International Nuclear Information System (INIS)

Chernushkin, V V; Mironova, P V; Ovsiannikov, V D

2008-01-01

The Jones effect in a medium of free atoms exposed to static electric and magnetic fields is a useful tool for determining details of an atomic structure. For atoms in their nS ground states irradiated by a monochromatic wave in resonance with a single-photon transition to an n' D state, the bilinear Jones effect is not shaded by the quadratic Kerr and Cotton-Mouton effects, nor by the linear in magnetic field Faraday effect. The position and shape of the amplitude resonance may provide information on spectroscopic properties of atomic levels. We generalize equations for the Jones-effect amplitude to the case of a doublet structure of energy levels and calculate corresponding parameters for alkali atoms. General equations are derived for the amplitude dependence on the relative orientation of the static electric and magnetic fields and on the angle between the static field and the major axis of the wave polarization vector. These equations demonstrate explicitly that the three bilinear-in-static-fields optical birefringence effects-(i) the Jones birefringence (in parallel fields), (ii) the linear birefringence and (iii) the directional birefringence (the last two in perpendicular fields)-correspond to particular cases of the bilinear-in-static-fields correction to the amplitude of Rayleigh forward scattering

Phononless soliton waves as early forerunners of crystalline material fracture

International Nuclear Information System (INIS)

Dubovskij, O.A.; Orlov, A.V.

2007-01-01

Phononless soliton waves of compression are shown to generate at a critical tension of crystals featuring real Lennard-Jones potential of interatomic interaction just before their fracture. A new method of nonlinear micro dynamics was applied to define the initial atomic displacements at high excitation energies. A solution is found that corresponds to a soliton wave running before the front of fracture. In a bounded crystal, the soliton being reflected from the crystal boundary passes the front of fracture and deforms while moving in the opposite direction. The amplitude and spectral characteristics of that type of soliton waves in crystals with a modified Lennard-Jones potential have been investigated. An approximate analytical solution was found for the soliton waves [ru

Parsing partial molar volumes of small molecules: a molecular dynamics study.

Science.gov (United States)

Patel, Nisha; Dubins, David N; Pomès, Régis; Chalikian, Tigran V

2011-04-28

We used molecular dynamics (MD) simulations in conjunction with the Kirkwood-Buff theory to compute the partial molar volumes for a number of small solutes of various chemical natures. We repeated our computations using modified pair potentials, first, in the absence of the Coulombic term and, second, in the absence of the Coulombic and the attractive Lennard-Jones terms. Comparison of our results with experimental data and the volumetric results of Monte Carlo simulation with hard sphere potentials and scaled particle theory-based computations led us to conclude that, for small solutes, the partial molar volume computed with the Lennard-Jones potential in the absence of the Coulombic term nearly coincides with the cavity volume. On the other hand, MD simulations carried out with the pair interaction potentials containing only the repulsive Lennard-Jones term produce unrealistically large partial molar volumes of solutes that are close to their excluded volumes. Our simulation results are in good agreement with the reported schemes for parsing partial molar volume data on small solutes. In particular, our determined interaction volumes() and the thickness of the thermal volume for individual compounds are in good agreement with empirical estimates. This work is the first computational study that supports and lends credence to the practical algorithms of parsing partial molar volume data that are currently in use for molecular interpretations of volumetric data.

A free energy study of the liquid-liquid phase transition of the Jagla ...

Indian Academy of Sciences (India)

Appendix” preliminary free energy surface calculations for select parameterizations of the generalized family of Jagla potentials spanning from the original (anomalous,water-like) Jagla model to the Lennard-Jones model. These calculations ...

Group leaders optimization algorithm

Science.gov (United States)

Daskin, Anmer; Kais, Sabre

2011-03-01

We present a new global optimization algorithm in which the influence of the leaders in social groups is used as an inspiration for the evolutionary technique which is designed into a group architecture. To demonstrate the efficiency of the method, a standard suite of single and multi-dimensional optimization functions along with the energies and the geometric structures of Lennard-Jones clusters are given as well as the application of the algorithm on quantum circuit design problems. We show that as an improvement over previous methods, the algorithm scales as N 2.5 for the Lennard-Jones clusters of N-particles. In addition, an efficient circuit design is shown for a two-qubit Grover search algorithm which is a quantum algorithm providing quadratic speedup over the classical counterpart.

On the equivalence of continuum and lattice models for fluids

International Nuclear Information System (INIS)

Panagiotopoulos, Athanassios Z.

2000-01-01

It was demonstrated that finely discretized lattice models for fluids with particles interacting via Lennard-Jones or exponential-6 potentials have essentially identical thermodynamic and structural properties to their continuum counterparts. Grand canonical histogram reweighting Monte Carlo calculations were performed for systems with repulsion exponents between 11 and 22. Critical parameters were determined from mixed-field finite-size scaling methods. Numerical equivalence of lattice and continuous space models, within simulation uncertainties, was observed for lattices with ratio of particle diameter σ to grid spacing of 10. The lattice model calculations were more efficient computationally by factors between 10 and 20. It was also shown that Lennard-Jones and exponential-6 based models with identical critical properties can be constructed by appropriate choice of the repulsion exponent. (c) 2000 American Institute of Physics

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.

Shear-induced phase changes in mixtures

International Nuclear Information System (INIS)

Romig, K.D.; Hanley, H.J.M.

1986-01-01

A thermodynamic theory to account for the behavior of liquid mixtures exposed to a shear is developed. One consequence of the theory is that shear-induced phase changes are predicted. The theory is based on a thermodynamics that includes specifically the shear rate in the formalism and is applied to mixtures by a straightforward modification of the corresponding states, conformalsolution approach. The approach is general but is used here for a mixture of Lennard-Jones particles with a Lennard-Jones equation of state as a reference fluid. The results are discussed in the context of the Scott and Van Konynenberg phase classification. It is shown that the influence of a shear does affect substantially the type of the phase behavior. Results from the model mixture are equated loosely with those from real polymeric liquids

Kinetic energy of solid and liquid para-hydrogen: a path integral Monte Carlo simulation

International Nuclear Information System (INIS)

Zoppi, M.; Neumann, M.

1992-01-01

The translational (center of mass) kinetic energy of solid and liquid para-hydrogen have been recently measured by means of Deep Inelastic Neutron Scattering. We have evaluated the same quantity, in similar thermodynamic conditions, by means of Path Integral Monte Carlo computer simulation, modelling the system as composed of a set of spherical molecules interacting through a pairwise additive Lennard-Jones potential. In spite of the crude approximations on the interaction potential, the agreement is excellent. The pressure was also computed by means of the same simulations. This quantity, compared with the equation of state for solid para-hydrogen given by Driessen and Silvera, gives an agreement of a lesser quality and a negative value for the liquid state. We attribute this discrepancy to the limitations of the Lennard-Jones potential. (orig.)

Isomorph invariance of Couette shear flows simulated by the SLLOD equations of motion

DEFF Research Database (Denmark)

Separdar, Leila; Bailey, Nicholas; Schrøder, Thomas

2013-01-01

fluctuations of virial and potential energy. Such systems have good isomorphs (curves in the thermodynamic phase diagram along which structural, dynamical, and some thermodynamic quantities are invariant when expressed in reduced units). The SLLOD equations of motion were used to simulate Couette shear flows......Non-equilibrium molecular dynamics simulations were performed to study the thermodynamic, structural, and dynamical properties of the single-component Lennard-Jones and the Kob-Andersen binary Lennard-Jones liquids. Both systems are known to have strong correlations between equilibrium thermal...... of the two systems. We show analytically that these equations are isomorph invariant provided the reduced strain rate is fixed along the isomorph. Since isomorph invariance is generally only approximate, a range of strain rates were simulated to test for the predicted invariance, covering both the linear...

Crystallization kinetics of Ga metallic nano-droplets under As flux

International Nuclear Information System (INIS)

Bietti, S; Somaschini, C; Sanguinetti, S

2013-01-01

We present an experimental investigation of the crystallization dynamics of Ga nano-droplets under As flux. The transformation of the metallic Ga contained in the droplets into a GaAs nano-island proceeds by increasing the size of a tiny ring of GaAs which is formed just after the Ga deposition at the rim of a droplet. The GaAs crystallization rate depends linearly on the liquid–solid interface area. The maximum growth rate is set by the As flux impinging on the droplet, thus showing an efficient As incorporation and transport despite the predicted low solubility of the As in metallic Ga at the crystallization temperatures. (paper)

Technique to measure contact angle of micro/nanodroplets using atomic force microscopy

International Nuclear Information System (INIS)

Jung, Yong Chae; Bhushan, Bharat

2008-01-01

Contact angle is the primary parameter that characterizes wetting; however, the measurement techniques have been limited to droplets with a diameter as low as about 50 μm. The authors developed an atomic force microscopy-based technique to measure the contact angle of micro- and nanodroplets deposited using a modified nanoscale dispensing tip. The obtained contact angle results were compared with those of a macrodroplet (2.1 mm diameter). It was found that the contact angle on various surfaces decreases with decreasing the droplet size

Stabiilne Ashley Jones / Svea Suvi

Index Scriptorium Estoniae

Suvi, Svea

2006-01-01

Ameerika teleseriaali "Vaprad ja ilusad" ("The Bold and the Beautiful") osatäitja Ashley Jones (Bridget Forrester). Sama artikkel pealkirjaga "Uus Bridget" : Nädal, 30. jan. 2006, nr. 4, lk. 12 : ill

Alignment and Imaging of the CS2 Dimer Inside Helium Nanodroplets

Science.gov (United States)

Pickering, James D.; Shepperson, Benjamin; Hübschmann, Bjarke A. K.; Thorning, Frederik; Stapelfeldt, Henrik

2018-03-01

The carbon disulphide (CS2) dimer is formed inside He nanodroplets and identified using fs laser-induced Coulomb explosion, by observing the CS2+ ion recoil velocity. It is then shown that a 160 ps moderately intense laser pulse can align the dimer in advantageous spatial orientations which allow us to determine the cross-shaped structure of the dimer by analysis of the correlations between the emission angles of the nascent CS2+ and S+ ions, following the explosion process. Our method will enable fs time-resolved structural imaging of weakly bound molecular complexes during conformational isomerization, including formation of exciplexes.

Milking liquid nano-droplets by an IR laser: a new modality for the visualization of electric field lines

International Nuclear Information System (INIS)

Vespini, Veronica; Coppola, Sara; Grilli, Simonetta; Paturzo, Melania; Ferraro, Pietro

2013-01-01

Liquid handling at micron- and nano-scale is of paramount importance in many fields of application such as biotechnology and biochemistry. In fact, the microfluidics technologies play an important role in lab-on-a-chip devices and, in particular, the dispensing of liquid droplets is a required functionality. Different approaches have been developed for manipulating, dispensing and controlling nano-droplets under a wide variety of configurations. Here we demonstrate that nano-droplets can be drawn from liquid drop or film reservoirs through a sort of milking effect achieved by the absorption of IR laser radiation into a pyroelectric crystal. The generation of the pyroelectric field induced by the IR laser is calculated numerically and a specific experiment has been designed to visualize the electric field stream lines that are responsible for the liquid milking effect. The experiments performed are expected to open a new route for the visualization, measure and characterization procedures in the case of electrohydrodynamic applications. (paper)

NVU dynamics. II. Comparing to four other dynamics

DEFF Research Database (Denmark)

Ingebrigtsen, Trond; Toxværd, Søren; Schrøder, Thomas

2011-01-01

-potential-energy hypersurface. Here, simulations of NVU dynamics are compared to results for four other dynamics, both deterministic and stochastic. First, NVU dynamics is compared to the standard energy-conserving Newtonian NVE dynamics by simulations of the Kob-Andersen binary Lennard-Jones liquid, its WCA version (i.......e., with cut-off's at the pair potential minima), and the Lennard-Jones Gaussian liquid. We find identical results for all quantities probed: radial distribution functions, incoherent intermediate scattering functions, and mean-square displacement as function of time. Arguments are presented...... on the constant-potential-energy hypersurface, and to Nos-Hoover NVT dynamics. If time is scaled for the two stochastic dynamics to make single-particle diffusion constants identical to that of NVE dynamics, the simulations show that all five dynamics are equivalent at low temperatures except at short times....

Impact of wall potential on the fluid-wall interaction in a cylindrical capillary and a generalized Kelvin equation

International Nuclear Information System (INIS)

Jakubov, T.S.; Mainwaring, D.E.

2006-01-01

In the present work a generalized Kelvin equation for a fluid confined in thick-walled cylindrical capillary is developed. This has been accomplished by including the potential energy function for interaction between a solid wall of a capillary and a confined fluid into the Kelvin equation. Using the Lennard-Jones 12-6 potential, an explicit form of the potential energy functions as expressed by hypergeometrical functions have been derived-firstly, for the interaction between a solid wall and a test atom placed at an arbitrary point in a long open-end capillary, and thereafter for the body-body interaction between the solid wall and a confined Lennard-Jones fluid. Further, this generalized Kelvin equation has been applied to detailed description hysteresis phenomena in such capillaries. All numerical calculations have been carried out for the model argon-graphite system at 90 K

Forefoot Adduction Is a Risk Factor for Jones Fracture.

Science.gov (United States)

Fleischer, Adam E; Stack, Rebecca; Klein, Erin E; Baker, Jeffrey R; Weil, Lowell; Weil, Lowell Scott

Jones fractures are among the most common fractures of the foot; however, much remains unknown about their etiology. The purpose of the present study was to further examine the risk factors of forefoot and hindfoot alignment on Jones fractures using an epidemiologic study design. We used a retrospective, matched, case-control study design. Cases consisted of patients with acute, isolated Jones fractures confirmed on plain film radiographs seen at our institute from January 2009 to December 2013. Patients presenting with pain unrelated to metatarsal fractures served as controls. Controls were matched to cases by age (±2 years), gender, and year of presentation. Weightbearing foot radiographs were assessed for 13 angular relationships by a single rater. Conditional multivariable logistic regression was used to identify important risk factors. Fifty patients with acute Jones fractures and 200 controls were included. The only significant variables in the final multivariable model were the metatarsus adductus angle (odds ratio [OR] 1.16, 95% confidence interval [CI] 1.08 to 1.25) and fourth/fifth intermetatarsal angle (OR 0.69, 95% CI 0.57 to 0.83)-both measures of static forefoot adduction. The presence of metatarsus adductus (defined as >15°) on foot radiographs was associated with a 2.4 times greater risk of a Jones fracture (adjusted OR 2.4, 95% CI 1.2 to 4.8). We have concluded that the risk of Jones fracture increases with an adducted forefoot posture. In our population, which consisted primarily of patients presenting after a fall (10 of 50; 20%) or misstep/inversion injury (19 of 50; 38%), the hindfoot alignment appeared to be a less important factor. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Verina Morton Jones, MD.

Science.gov (United States)

Rishworth, Susan K

2012-01-01

The purpose of this historical article is to demonstrate, as the biography of Verina Morton Jones, MD, is uncovered, the difficulties inherent in researching original source material on the lives of 19th- and early 20th-century African American physicians as well as the great benefits derived from doing this research. The procedures used include basic archival research and close examination of published materials about her in the past, in conjunction with oral history. Original correspondence from Dr Morton Jones to her niece and nephew is used to illustrate events in her life and the thoughts and attitudes she expressed. Some of these thoughts and attitudes reflect those current situations in which African Americans found themselves, and others are quite unique, no doubt owing to her privileged position in the African American community. The principle conclusions reached include the great benefits derived from doing this kind of research, as difficult and time-consuming as that may be, with the enhanced knowledge and appreciation of the heritage of African American physicians, and insights into American social history during this period.

Topological quantum information, virtual Jones polynomials and Khovanov homology

International Nuclear Information System (INIS)

Kauffman, Louis H

2011-01-01

In this paper, we give a quantum statistical interpretation of the bracket polynomial state sum 〈K〉, the Jones polynomial V K (t) and virtual knot theory versions of the Jones polynomial, including the arrow polynomial. We use these quantum mechanical interpretations to give new quantum algorithms for these Jones polynomials. In those cases where the Khovanov homology is defined, the Hilbert space C(K) of our model is isomorphic with the chain complex for Khovanov homology with coefficients in the complex numbers. There is a natural unitary transformation U:C(K) → C(K) such that 〈K〉 = Trace(U), where 〈K〉 denotes the evaluation of the state sum model for the corresponding polynomial. We show that for the Khovanov boundary operator ∂:C(K) → C(K), we have the relationship ∂U + U∂ = 0. Consequently, the operator U acts on the Khovanov homology, and we obtain a direct relationship between the Khovanov homology and this quantum algorithm for the Jones polynomial. (paper)

A response to Dodds and Jones.

Science.gov (United States)

Purdy, Laura M

1989-01-01

In response to "Surrogacy and Autonomy," by Susan Dodds and Karen Jones in this issue of Bioethics, the author concedes that only a surrogacy practice stringently regulated by good counseling, escape clauses for pregnant women, and the prohibition of profit-making agencies will save women from exploitation, but she objects to singling out women for paternalistic "protection against themselves," and to defending women's autonomy to the extent of their right to behave in ways known to harm a fetus. Dodds and Jones' concerns about attitudes toward women, genetic bias, the concept of children as property, and the harm principle generated by surrogacy contracts are answered with arguments for why surrogacy should not be illegal.

Evaluating the Laplace pressure of water nanodroplets from simulations

Science.gov (United States)

Malek, Shahrazad M. A.; Sciortino, Francesco; Poole, Peter H.; Saika-Voivod, Ivan

2018-04-01

We calculate the components of the microscopic pressure tensor as a function of radial distance r from the centre of a spherical water droplet, modelled using the TIP4P/2005 potential. To do so, we modify a coarse-graining method for calculating the microscopic pressure (Ikeshoji et al 2003 Mol. Simul. 29 101) in order to apply it to a rigid molecular model of water. As test cases, we study nanodroplets ranging in size from 776 to 2880 molecules at 220 K. Beneath a surface region comprising approximately two molecular layers, the pressure tensor becomes approximately isotropic and constant with r. We find that the dependence of the pressure on droplet radius is that expected from the Young-Laplace equation, despite the small size of the droplets.

Contact angle dependence on the fluid-wall dispersive energy

NARCIS (Netherlands)

Horsch, M.; Heitzig, M.; Dan, C.M.; Harting, J.D.R.; Hasse, H.; Vrabec, J.

2010-01-01

Menisci of the truncated and shifted Lennard-Jones fluid between parallel planar walls are investigated by molecular dynamics simulation. Thereby, the characteristic energy of the unlike dispersive interaction between fluid molecules and wall atoms is systematically varied to determine its influence

Switching Between the NVT and NpT Ensembles Using the Reweighting and Reconstruction Scheme

KAUST Repository

Kadoura, Ahmad Salim; Salama, Amgad; Sun, Shuyu

2015-01-01

thermodynamic conditions from a single MC Markov chain. The latter scheme, was first developed to extrapolate quantities in NV T ensemble for struc- tureless Lennard-Jones particles. However, it is evident that for most real life applications the NpT ensemble

Validity of the Rosenfeld relationship: A comparative study of the ...

Indian Academy of Sciences (India)

ATREYEE BANERJEE

we find that the NTW model has mixed characteristics of simple liquids and ionic melts. Our study further ... and the value of the Rosenfeld exponents are differ- ent from that found for ..... Lennard-Jones chains J. Chem. Phys. 129 164904. 4.

Electron induced formation and stability of molecular and cluster ions in gas phase and superfluid helium nanodroplets

International Nuclear Information System (INIS)

Aleem, M. A.

2010-01-01

The present PhD thesis represents a broad range study of electron induced formation and stability of positive and negative ions in gas phase and superfluid helium nanodroplets. The molecules studied are of industrial, environmental, plasma and biological relevance. The knowledge obtained from the study provides new insight for the proper understanding and control on energetics and dynamics of the reactions involved in the formation and fragmentation processes of the studied molecules and clusters. The experiments are accomplished and investigated using mass spectrometric techniques for the formation of molecular and cluster ions using different mass spectrometers available in our laboratory. One part of the work is focused on electron-induced reactions of the molecules in gas phase. Especially focus is laid to electron attachment to the isomers of mononitrotolouene used as an additive to explosives. The fragile nature and high internal energy of these molecules has lead to extensive fragmentation following the ionisation process. Dissociative electron attachment to the three different isomers has shown different resonances and therefore this process can be utilized to explicitly distinguish these isomers. Anion efficiency curves of the isomers have been studied using effusive molecular beam source in combination with a hemispherical electron monochromator as well as a Nier-type ion source attached to a sector field mass spectrometer. The outcome of the experiment is a reliable and effective detection method highly desirable for environmental and security reasons. Secondly, dissociative electron ionization of acetylene and propene is studied and their data is directly related to the plasma modelling for plasma fusion and processing reactors. Temperature effects for dissociative electron attachment to halo-hydrocarbons are also measured using a trochoidal electron monochromator. The second part of the work is concerned with the investigation of electron

Elastic properties of surfactant monolayers at liquid-liquid interfaces: A molecular dynamics study

DEFF Research Database (Denmark)

Laradji, Mohamed; Mouritsen, Ole G.

2000-01-01

Using a simple molecular model based on the Lennard-Jones potential, we systematically study the elastic properties of liquid-liquid interfaces containing surfactant molecules by means of extensive and large-scale molecular dynamics simulations. The main elastic constants of the interface, corres...

Chuck Jones lahkus, tema kangelased elavad edasi / Neeme Korv

Index Scriptorium Estoniae

Korv, Neeme, 1974-

2002-01-01

Suri Chuck Jones (1912-2002), kuulus USA animafilmirežissöör, kelle animasari "Tom & Jerry" on praegugi Eestis väga populaarne. Ta on loonud enam kui 300 animafilmi, saanud 3 Oscarit ning 1996. aastal ka elutöö Oscari. Eesti lapsed nägid nõukogude ajal esmakordselt Chuck Jones'i loomingut Raivo Järvi lastesaadetes "Laupäeval koos isaga"

Guts of surfaces and the colored Jones polynomial

CERN Document Server

Futer, David; Purcell, Jessica

2013-01-01

This monograph derives direct and concrete relations between colored Jones polynomials and the topology of incompressible spanning surfaces in knot and link complements. Under mild diagrammatic hypotheses, we prove that the growth of the degree of the colored Jones polynomials is a boundary slope of an essential surface in the knot complement. We show that certain coefficients of the polynomial measure how far this surface is from being a fiber for the knot; in particular, the surface is a fiber if and only if a particular coefficient vanishes. We also relate hyperbolic volume to colored Jones polynomials. Our method is to generalize the checkerboard decompositions of alternating knots. Under mild diagrammatic hypotheses, we show that these surfaces are essential, and obtain an ideal polyhedral decomposition of their complement. We use normal surface theory to relate the pieces of the JSJ decomposition of the  complement to the combinatorics of certain surface spines (state graphs). Since state graphs have p...

Classical molecular dynamics simulation on the dynamical properties of H2 on silicene layer

Directory of Open Access Journals (Sweden)

Casuyac Miqueas

2016-01-01

Full Text Available This study investigates the diffusion of hydrogen molecule physisorbed on the surface of silicene nanoribbon (SiNRusing the classical molecular dynamic (MD simulation in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator. The interactions between silicon atoms are modeled using the modified Tersoff potential, the Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO potential for hydrogen – hydrogen interaction and the Lennard – Jones potential for the physisorbed H2 on SiNR. By varying the temperatures (60 K Δ 130 K, we observed that the Δxdisplacement of H2 on the surface SiNR shows a Brownian motion on a Lennard-Jones potential and a Gaussian probability distribution can be plotted describing the diffusion of H2. The calculated mean square displacement (MSD was approximately increasing in time and the activation energy barrier for diffusion has been found to be 43.23meV.

Nuclear-magnetic-resonance quantum calculations of the Jones polynomial

International Nuclear Information System (INIS)

Marx, Raimund; Spoerl, Andreas; Pomplun, Nikolas; Schulte-Herbrueggen, Thomas; Glaser, Steffen J.; Fahmy, Amr; Kauffman, Louis; Lomonaco, Samuel; Myers, John M.

2010-01-01

The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for a small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots.

Jones' instrument technology

CERN Document Server

Jones, Ernest Beachcroft; Kingham, Edward G; Radnai, Rudolf

1985-01-01

Jones' Instrument Technology, Volume 5: Automatic Instruments and Measuring Systems deals with general trends in automatic instruments and measuring systems. Specific examples are provided to illustrate the principles of such devices. A brief review of a considerable number of standards is undertaken, with emphasis on the IEC625 Interface System. Other relevant standards are reviewed, including the interface and backplane bus standards. This volume is comprised of seven chapters and begins with a short introduction to the principles of automatic measurements, classification of measuring system

Indiana Jones on tagasi ja näitab, kuidas käituda / Kristiina Davidjants

Index Scriptorium Estoniae

Davidjants, Kristiina, 1974-

2008-01-01

22 mail esilinastub Steven Spielbergi järjekordne Indiana Jones'i film, kaasstsenaristiks ja produtsendiks George Lucas ja Harrison Fordiga nimiosas "Indiana Jones ja kristallpealuu kuningriik" ("Indiana Jones and the Kingdom of the Crystal Skull"). Saaga varasemast kolmest filmist

Calculation of Liquid Water-Hydrate-Methane Vapor Phase Equilibria from Molecular Simulations

DEFF Research Database (Denmark)

Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

2010-01-01

using the TIP4P/ice potential and a united-atom Lennard-Jones potential. respectively. The equilibrium calculation method for this system has three components, (i) thermodynamic integration from a supercritical ideal gas to obtain the fluid-phase chemical potentials. (ii) calculation of the chemical...

Symmetric webs, Jones-Wenzl recursions and q-Howe duality

DEFF Research Database (Denmark)

Rose, David; Tubbenhauer, Daniel

We define and study the category of symmetric sl2-webs. This category is a combinatorial description of the category of all finite dimensional quantum sl2-modules. Explicitly, we show that (the additive closure of) the symmetric sl2-spider is (braided monoidally) equivalent to the latter. Our mai...... tool is a quantum version of symmetric Howe duality. As a corollary of our construction, we provide new insight into Jones-Wenzl projectors and the colored Jones polynomials....

The Jones polynomial as a new invariant of topological fluid dynamics

International Nuclear Information System (INIS)

Ricca, Renzo L; Liu, Xin

2014-01-01

A new method based on the use of the Jones polynomial, a well-known topological invariant of knot theory, is introduced to tackle and quantify topological aspects of structural complexity of vortex tangles in ideal fluids. By re-writing the Jones polynomial in terms of helicity, the resulting polynomial becomes then function of knot topology and vortex circulation, providing thus a new invariant of topological fluid dynamics. Explicit computations of the Jones polynomial for some standard configurations, including the Whitehead link and the Borromean rings (whose linking numbers are zero), are presented for illustration. In the case of a homogeneous, isotropic tangle of vortex filaments with same circulation, the new Jones polynomial reduces to some simple algebraic expression, that can be easily computed by numerical methods. This shows that this technique may offer a new setting and a powerful tool to detect and compute topological complexity and to investigate relations with energy, by tackling fundamental aspects of turbulence research. (paper)

G A Adebayo

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics. G A Adebayo. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.

Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

NARCIS (Netherlands)

Lerner, E.; Bailey, N.P.; Dyre, J.C.

2014-01-01

Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between the

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics. L A Hussain. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics. O akinlade. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.

Comparison of potentials for polymeric liquids

International Nuclear Information System (INIS)

Jung, Hae Young

2002-01-01

Many theories for polymeric liquids are based on the concepts of cell, hole, free volume of lattice etc. In this theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used. In this work, Mie(p,6)potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equation of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values changing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid theory, Flory's Equation of State Theory and Cho-Sanchez Theory using perturbation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p,6) potential for polymeric liquids were compared with each other

Statistical mechanical calculations of molecular pair correlation functions and scattering intensities

International Nuclear Information System (INIS)

Bertagnolli, H.

1978-01-01

For the case of special molecular models representing the acetonitrile molecule the expansion coefficients of the molecular par distribution function are calculated by use of pertubation theory. These results are used to get theoretical access to scattering intensities in the frame of several approximations. The first model describes the molecule by three hard spheres and uses a hard sphere liquid as reference. In the second cast the calculations are based on an anisotropic Lennard-Jones potential by application of a model of overlapping ellipsoids and by use of a Lennard-Jones liquid as a reference system. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. Finally all the calculations with different intermolecular potentials are compared with neutron scattering experiments. (orig.) 891 HK [de

The thermodynamic properties of normal liquid helium 3

Science.gov (United States)

Modarres, M.; Moshfegh, H. R.

2009-09-01

The thermodynamic properties of normal liquid helium 3 are calculated by using the lowest order constrained variational (LOCV) method. The Landau Fermi liquid model and Fermi-Dirac distribution function are considered as our statistical model for the uncorrelated quantum fluid picture and the Lennard-Jones and Aziz potentials are used in our truncated cluster expansion (LOCV) to calculate the correlated energy. The single particle energy is treated variationally through an effective mass. The free energy, pressure, entropy, chemical potential and liquid phase diagram as well as the helium 3 specific heat are evaluated, discussed and compared with the corresponding available experimental data. It is found that the critical temperature for the existence of the pure gas phase is about 4.90 K (4.45 K), which is higher than the experimental prediction of 3.3 K, and the helium 3 flashing temperature is around 0.61 K (0.50 K) for the Lennard-Jones (Aziz) potential.

Simplicity of condensed matter at its core: generic definition of a Roskilde-simple system.

Science.gov (United States)

Schrøder, Thomas B; Dyre, Jeppe C

2014-11-28

The isomorph theory is reformulated by defining Roskilde-simple systems by the property that the order of the potential energies of configurations at one density is maintained when these are scaled uniformly to a different density. If the potential energy as a function of all particle coordinates is denoted by U(R), this requirement translates into U(Ra) < U(Rb) ⇒ U(λRa) < U(λRb). Isomorphs remain curves in the thermodynamic phase diagram along which structure, dynamics, and excess entropy are invariant, implying that the phase diagram is effectively one-dimensional with respect to many reduced-unit properties. In contrast to the original formulation of the isomorph theory, however, the density-scaling exponent is not exclusively a function of density and the isochoric heat capacity is not an exact isomorph invariant. A prediction is given for the latter quantity's variation along the isomorphs. Molecular dynamics simulations of the Lennard-Jones and Lennard-Jones Gaussian systems validate the new approach.

Molecular dynamic simulation of Copper and Platinum nanoparticles Poiseuille flow in a nanochannels

Science.gov (United States)

Toghraie, Davood; Mokhtari, Majid; Afrand, Masoud

2016-10-01

In this paper, simulation of Poiseuille flow within nanochannel containing Copper and Platinum particles has been performed using molecular dynamic (MD). In this simulation LAMMPS code is used to simulate three-dimensional Poiseuille flow. The atomic interaction is governed by the modified Lennard-Jones potential. To study the wall effects on the surface tension and density profile, we placed two solid walls, one at the bottom boundary and the other at the top boundary. For solid-liquid interactions, the modified Lennard-Jones potential function was used. Velocity profiles and distribution of temperature and density have been obtained, and agglutination of nanoparticles has been discussed. It has also shown that with more particles, less time is required for the particles to fuse or agglutinate. Also, we can conclude that the agglutination time in nanochannel with Copper particles is faster that in Platinum nanoparticles. Finally, it is demonstrated that using nanoparticles raises thermal conduction in the channel.

Detailed balance method for chemical potential determination in Monte Carlo and molecular dynamics simulations

International Nuclear Information System (INIS)

Fay, P.J.; Ray, J.R.; Wolf, R.J.

1994-01-01

We present a new, nondestructive, method for determining chemical potentials in Monte Carlo and molecular dynamics simulations. The method estimates a value for the chemical potential such that one has a balance between fictitious successful creation and destruction trials in which the Monte Carlo method is used to determine success or failure of the creation/destruction attempts; we thus call the method a detailed balance method. The method allows one to obtain estimates of the chemical potential for a given species in any closed ensemble simulation; the closed ensemble is paired with a ''natural'' open ensemble for the purpose of obtaining creation and destruction probabilities. We present results for the Lennard-Jones system and also for an embedded atom model of liquid palladium, and compare to previous results in the literature for these two systems. We are able to obtain an accurate estimate of the chemical potential for the Lennard-Jones system at higher densities than reported in the literature

Solid phase stability of a double-minimum interaction potential system

International Nuclear Information System (INIS)

Suematsu, Ayumi; Yoshimori, Akira; Saiki, Masafumi; Matsui, Jun; Odagaki, Takashi

2014-01-01

We study phase stability of a system with double-minimum interaction potential in a wide range of parameters by a thermodynamic perturbation theory. The present double-minimum potential is the Lennard-Jones-Gauss potential, which has a Gaussian pocket as well as a standard Lennard-Jones minimum. As a function of the depth and position of the Gaussian pocket in the potential, we determine the coexistence pressure of crystals (fcc and bcc). We show that the fcc crystallizes even at zero pressure when the position of the Gaussian pocket is coincident with the first or third nearest neighbor site of the fcc crystal. The bcc crystal is more stable than the fcc crystal when the position of the Gaussian pocket is coincident with the second nearest neighbor sites of the bcc crystal. The stable crystal structure is determined by the position of the Gaussian pocket. These results show that we can control the stability of the solid phase by tuning the potential function

Dynamics of solvation and desolvation of rubidium attached to He nanodroplets

International Nuclear Information System (INIS)

Vangerow, J. von; John, O.; Stienkemeier, F.; Mudrich, M.

2015-01-01

The real-time dynamics of photoexcited and photoionized rubidium (Rb) atoms attached to helium (He) nanodroplets is studied by femtosecond pump-probe mass spectrometry. While excited Rb atoms in the perturbed 6p-state (Rb * ) desorb off the He droplets, Rb + photoions tend to sink into the droplet interior when created near the droplet surface. The transition from Rb + solvation to full Rb * desorption is found to occur at a delay time τ ∼ 600 fs for Rb * in the 6pΣ-state and τ ∼ 1200 fs for the 6pΠ-state. Rb + He ions are found to be created by directly exciting bound Rb * He exciplex states as well as by populating bound Rb + He-states in a photoassociative ionization process

Dynamics of solvation and desolvation of rubidium attached to He nanodroplets

Science.gov (United States)

von Vangerow, J.; John, O.; Stienkemeier, F.; Mudrich, M.

2015-07-01

The real-time dynamics of photoexcited and photoionized rubidium (Rb) atoms attached to helium (He) nanodroplets is studied by femtosecond pump-probe mass spectrometry. While excited Rb atoms in the perturbed 6p-state (Rb*) desorb off the He droplets, Rb+ photoions tend to sink into the droplet interior when created near the droplet surface. The transition from Rb+ solvation to full Rb* desorption is found to occur at a delay time τ ˜ 600 fs for Rb* in the 6pΣ-state and τ ˜ 1200 fs for the 6pΠ-state. Rb+He ions are found to be created by directly exciting bound Rb*He exciplex states as well as by populating bound Rb+He-states in a photoassociative ionization process.

A new approach to radiative transfer theory using Jones's vectors. I

International Nuclear Information System (INIS)

Fymat, A.L.; Vasudevan, R.

1975-01-01

Radiative transfer of partially polarized radiation in an anisotropically scattering, inhomogeneous atmosphere containing arbitrary polydispersion of particles is described using Jones's amplitude vectors and matrices. This novel approach exploits the close analogy between the quantum mechanical states of spin 1/2 systems and the polarization states of electromagnetic radiation described by Jones's vector, and draws on the methodology of such spin 1/2 systems. The complete equivalence between the transport equation for Jones's vectors and the classical radiative transfer equation for Stokes's intensity vectors is demonstrated in two independent ways after deriving the transport equations for the polarization coherency matrices and for the quaternions corresponding to the Jones's vectors. A compact operator formulation of the theory is provided, and used to derive the necessary equations for both a local and a global description of the transport of Jones's vectors. Lastly, the integro-differential equations for the amplitude reflection and transmission matrices are derived, and related to the usual corresponding equations. The present formulation is the most succinct and the most convenient one for both theoretical and experimental studies. It yields a simpler analysis than the classical formulation since it reduces by a factor of two the dimensionality of transfer problems. It preserves information on phases, and thus can be used directly across the entire electromagnetic spectrum without any further conversion into intensities. (Auth.)

Dynamics of photoexcited Ba+ cations in 4He nanodroplets

International Nuclear Information System (INIS)

2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Leal, Antonio; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Pi, Martí; Zhang, Xiaohang; Drabbels, Marcel; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" >Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo

2016-01-01

We present a joint experimental and theoretical study on the desolvation of Ba + cations in 4 He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba + cations and Ba + He n exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba + He n exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba + . In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba + cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba + cations or exciplexes, even when relaxation pathways to lower lying states are included.

Interaction forces between nanoparticles in Lennard-Jones (L-J) solvents

International Nuclear Information System (INIS)

Sinha, Indrajit; Mukherjee, Ashim K

2014-01-01

Molecular simulations, such as Monte Carlo (MC) and molecular dynamics (MD) have been recently used for understanding the forces between colloidal nanoparticles that determine the dispersion and stability of nanoparticle suspensions. Herein we review the current status of research in the area of nanoparticles immersed in L-J solvents. The first study by Shinto et al. used large smooth spheres to depict nanoparticles in L-J and soft sphere solvents. The nanoparticles were held fixed at a particular interparticle distance and only the solvents were allowed to equilibrate. Both Van-der-waals and solvation forces were computed at different but fixed interparticle separation. Later Qin and Fitchthorn improved on this model by considering the nanoparticles as collection of molecules, thus taking into the account the effect of surface roughness of nanoparticles. Although the inter particle distance was fixed, the rotation of such nanoparticles with respect to each other was also investigated. Recently, in keeping with the experimental situation, we modified this model by allowing the nanoparticles to move and rotate freely. Solvophilic, neutral and solvophobic interactions between the solvent atoms and those that make up the nanoparticles were modelled. While neutral and solvophobic nanoparticles coalesce even at intermediate distances, solvophilic nanoparticles are more stable in solution due to the formation of a solvent shield

Efficient Implementations of Molecular Dynamics Simulations for Lennard-Jones Systems

KAUST Repository

Watanabe, H.; Suzuki, M.; Ito, N.

2011-01-01

simple spatialdecomposition-based strategy is adopted for parallelization. By utilizing the developed code, benchmark simulations are performed on a HITACHI SR16000/J2 system consisting of IBM POWER6 processors which are 4.7 GHz at the National Institute

Gas Enrichment at Liquid-Wall Interfaces

NARCIS (Netherlands)

Dammer, S.M.; Lohse, Detlef

2006-01-01

Molecular dynamics simulations of Lennard-Jones systems are performed to study the effects of dissolved gas on liquid-wall and liquid-gas interfaces. Gas enrichment at walls, which for hydrophobic walls can exceed more than 2 orders of magnitude when compared to the gas density in the bulk liquid,

Molecular beam scattering experiments with polar molecules. 1. Differential elastic scattering of H2+NH3 and H2+H2O

International Nuclear Information System (INIS)

Bickes, R.W. Jr.; Scoles, G.; Smith, K.M.

1974-01-01

Differential elastic scattering cross sections with well resolved quantum oscillations have been measuremed for the systems H 2 +NH 3 and H 2 +H 2 O. Assuming a spherically symmetric interaction the data show that a simple spherical potential (i.e. Lennard-Jones) does not properly describe the scattering

Calculation of partial enthalpies in argon-krypton mixtures by NPT molecular dynamics

NARCIS (Netherlands)

Sindzingre, P.; Massobrio, C.; Ciccotti, G.; Frenkel, D.

1989-01-01

In an earlier paper, we have indicated how, by using a particle-insertion technique, partial molar enthalpies and related quantities can be evaluated from simulations on a single state point. In the present paper we apply this method to a Lennard-Jones argon-krypton mixture. For this particular

Study of structure and spectroscopy of water–hydroxide ion clusters ...

Indian Academy of Sciences (India)

Experimen- talists are interested in determining the bonding,1–18 structure and spectroscopy of these systems and the- oreticians have contributed to the logical explanation of experimental findings. There are different types of systems ranging from atomic clusters, especially noble gas clusters (modelled by Lennard Jones ...

Boundary layer energies for nonconvex discrete systems

NARCIS (Netherlands)

Scardia, L.; Schlömerkemper, A.; Zanini, C.

2011-01-01

In this work we consider a one-dimensional chain of atoms which interact through nearest and next-to-nearest neighbour interactions of Lennard-Jones type. We impose Dirichlet boundary conditions and in addition prescribe the deformation of the second and last but one atoms of the chain. This

Chitosan-shelled oxygen-loaded nanodroplets abrogate hypoxia dysregulation of human keratinocyte gelatinases and inhibitors: New insights for chronic wound healing

Energy Technology Data Exchange (ETDEWEB)

Khadjavi, Amina [Dipartimento di Neuroscienze, Università di Torino, Torino (Italy); Magnetto, Chiara [Istituto Nazionale di Ricerca Metrologica (INRIM), Torino (Italy); Panariti, Alice [Dipartimento di Scienze della Salute, Università di Milano Bicocca, Monza (Italy); Argenziano, Monica [Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Torino (Italy); Gulino, Giulia Rossana [Dipartimento di Oncologia, Università di Torino, Torino (Italy); Rivolta, Ilaria [Dipartimento di Scienze della Salute, Università di Milano Bicocca, Monza (Italy); Cavalli, Roberta [Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Torino (Italy); Giribaldi, Giuliana [Dipartimento di Oncologia, Università di Torino, Torino (Italy); Guiot, Caterina [Dipartimento di Neuroscienze, Università di Torino, Torino (Italy); Prato, Mauro, E-mail: mauro.prato@unito.it [Dipartimento di Neuroscienze, Università di Torino, Torino (Italy); Dipartimento di Scienze della Sanità Pubblica e Pediatriche, Università di Torino, Torino (Italy)

2015-08-01

Background: : In chronic wounds, efficient epithelial tissue repair is hampered by hypoxia, and balances between the molecules involved in matrix turn-over such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are seriously impaired. Intriguingly, new oxygenating nanocarriers such as 2H,3H-decafluoropentane-based oxygen-loaded nanodroplets (OLNs) might effectively target chronic wounds. Objective: : To investigate hypoxia and chitosan-shelled OLN effects on MMP/TIMP production by human keratinocytes. Methods: : HaCaT cells were treated for 24 h with 10% v/v OLNs both in normoxia or hypoxia. Cytotoxicity and cell viability were measured through biochemical assays; cellular uptake by confocal microscopy; and MMP and TIMP production by enzyme-linked immunosorbent assay or gelatin zymography. Results: : Normoxic HaCaT cells constitutively released MMP-2, MMP-9, TIMP-1 and TIMP-2. Hypoxia strongly impaired MMP/TIMP balances by reducing MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. After cellular uptake by keratinocytes, nontoxic OLNs abrogated all hypoxia effects on MMP/TIMP secretion, restoring physiological balances. OLN abilities were specifically dependent on time-sustained oxygen diffusion from OLN core. Conclusion: : Chitosan-shelled OLNs effectively counteract hypoxia-dependent dysregulation of MMP/TIMP balances in human keratinocytes. Therefore, topical administration of exogenous oxygen, properly encapsulated in nanodroplet formulations, might be a promising adjuvant approach to promote healing processes in hypoxic wounds. - Highlights: • Hypoxia impairs MMP9/TIMP1 and MMP2/TIMP2 balances in HaCaT human keratinocytes. • Chitosan-shelled oxygen-loaded nanodroplets (OLNs) are internalised by HaCaT cells. • OLNs are not toxic to HaCaT cells. • OLNs effectively counteract hypoxia effects on MMP/TIMP balances in HaCaT cells. • OLNs appear as promising and cost-effective therapeutic tools for hypoxic

Chitosan-shelled oxygen-loaded nanodroplets abrogate hypoxia dysregulation of human keratinocyte gelatinases and inhibitors: New insights for chronic wound healing

International Nuclear Information System (INIS)

Khadjavi, Amina; Magnetto, Chiara; Panariti, Alice; Argenziano, Monica; Gulino, Giulia Rossana; Rivolta, Ilaria; Cavalli, Roberta; Giribaldi, Giuliana; Guiot, Caterina; Prato, Mauro

2015-01-01

Background: : In chronic wounds, efficient epithelial tissue repair is hampered by hypoxia, and balances between the molecules involved in matrix turn-over such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are seriously impaired. Intriguingly, new oxygenating nanocarriers such as 2H,3H-decafluoropentane-based oxygen-loaded nanodroplets (OLNs) might effectively target chronic wounds. Objective: : To investigate hypoxia and chitosan-shelled OLN effects on MMP/TIMP production by human keratinocytes. Methods: : HaCaT cells were treated for 24 h with 10% v/v OLNs both in normoxia or hypoxia. Cytotoxicity and cell viability were measured through biochemical assays; cellular uptake by confocal microscopy; and MMP and TIMP production by enzyme-linked immunosorbent assay or gelatin zymography. Results: : Normoxic HaCaT cells constitutively released MMP-2, MMP-9, TIMP-1 and TIMP-2. Hypoxia strongly impaired MMP/TIMP balances by reducing MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. After cellular uptake by keratinocytes, nontoxic OLNs abrogated all hypoxia effects on MMP/TIMP secretion, restoring physiological balances. OLN abilities were specifically dependent on time-sustained oxygen diffusion from OLN core. Conclusion: : Chitosan-shelled OLNs effectively counteract hypoxia-dependent dysregulation of MMP/TIMP balances in human keratinocytes. Therefore, topical administration of exogenous oxygen, properly encapsulated in nanodroplet formulations, might be a promising adjuvant approach to promote healing processes in hypoxic wounds. - Highlights: • Hypoxia impairs MMP9/TIMP1 and MMP2/TIMP2 balances in HaCaT human keratinocytes. • Chitosan-shelled oxygen-loaded nanodroplets (OLNs) are internalised by HaCaT cells. • OLNs are not toxic to HaCaT cells. • OLNs effectively counteract hypoxia effects on MMP/TIMP balances in HaCaT cells. • OLNs appear as promising and cost-effective therapeutic tools for hypoxic

Thermal motion in proteins: Large effects on the time-averaged interaction energies

International Nuclear Information System (INIS)

Goethe, Martin; Rubi, J. Miguel; Fita, Ignacio

2016-01-01

As a consequence of thermal motion, inter-atomic distances in proteins fluctuate strongly around their average values, and hence, also interaction energies (i.e. the pair-potentials evaluated at the fluctuating distances) are not constant in time but exhibit pronounced fluctuations. These fluctuations cause that time-averaged interaction energies do generally not coincide with the energy values obtained by evaluating the pair-potentials at the average distances. More precisely, time-averaged interaction energies behave typically smoother in terms of the average distance than the corresponding pair-potentials. This averaging effect is referred to as the thermal smoothing effect. Here, we estimate the strength of the thermal smoothing effect on the Lennard-Jones pair-potential for globular proteins at ambient conditions using x-ray diffraction and simulation data of a representative set of proteins. For specific atom species, we find a significant smoothing effect where the time-averaged interaction energy of a single atom pair can differ by various tens of cal/mol from the Lennard-Jones potential at the average distance. Importantly, we observe a dependency of the effect on the local environment of the involved atoms. The effect is typically weaker for bulky backbone atoms in beta sheets than for side-chain atoms belonging to other secondary structure on the surface of the protein. The results of this work have important practical implications for protein software relying on free energy expressions. We show that the accuracy of free energy expressions can largely be increased by introducing environment specific Lennard-Jones parameters accounting for the fact that the typical thermal motion of protein atoms depends strongly on their local environment.

Thermal motion in proteins: Large effects on the time-averaged interaction energies

Energy Technology Data Exchange (ETDEWEB)

Goethe, Martin, E-mail: martingoethe@ub.edu; Rubi, J. Miguel [Departament de Física Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Fita, Ignacio [Institut de Biologia Molecular de Barcelona, Baldiri Reixac 10, 08028 Barcelona (Spain)

2016-03-15

As a consequence of thermal motion, inter-atomic distances in proteins fluctuate strongly around their average values, and hence, also interaction energies (i.e. the pair-potentials evaluated at the fluctuating distances) are not constant in time but exhibit pronounced fluctuations. These fluctuations cause that time-averaged interaction energies do generally not coincide with the energy values obtained by evaluating the pair-potentials at the average distances. More precisely, time-averaged interaction energies behave typically smoother in terms of the average distance than the corresponding pair-potentials. This averaging effect is referred to as the thermal smoothing effect. Here, we estimate the strength of the thermal smoothing effect on the Lennard-Jones pair-potential for globular proteins at ambient conditions using x-ray diffraction and simulation data of a representative set of proteins. For specific atom species, we find a significant smoothing effect where the time-averaged interaction energy of a single atom pair can differ by various tens of cal/mol from the Lennard-Jones potential at the average distance. Importantly, we observe a dependency of the effect on the local environment of the involved atoms. The effect is typically weaker for bulky backbone atoms in beta sheets than for side-chain atoms belonging to other secondary structure on the surface of the protein. The results of this work have important practical implications for protein software relying on free energy expressions. We show that the accuracy of free energy expressions can largely be increased by introducing environment specific Lennard-Jones parameters accounting for the fact that the typical thermal motion of protein atoms depends strongly on their local environment.

Structure, single-particle and many-particle coefficients of Lennard ...

Indian Academy of Sciences (India)

Molecular dynamics calculations; viscosity of liquids; structure of liquids; simple liquids and ... (UNAABMD) that uses the Verlet algorithm to perform the integration of equa- ... The input parameters for the Lennard–Jones model are σ = 2.62 Å and .... viscosity. This has been calculated using also the Green–Kubo relation and.

Not Fully Developed Turbulence in the Dow Jones Index

Science.gov (United States)

Trincado, Estrella; Vindel, Jose María

2013-08-01

The shape of the curves relating the scaling exponents of the structure functions to the order of these functions is shown to distinguish the Dow Jones index from other stock market indices. We conclude from the shape differences that the information-loss rate for the Dow Jones index is reduced at smaller time scales, while it grows for other indices. This anomaly is due to the construction of the index, in particular to its dependence on a single market parameter: price. Prices are subject to turbulence bursts, which act against full development of turbulence.

Dynamics of solvation and desolvation of rubidium attached to He nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Vangerow, J. von; John, O.; Stienkemeier, F.; Mudrich, M., E-mail: mudrich@physik.uni-freiburg.de [Physikalisches Institut, Universität Freiburg, 79104 Freiburg (Germany)

2015-07-21

The real-time dynamics of photoexcited and photoionized rubidium (Rb) atoms attached to helium (He) nanodroplets is studied by femtosecond pump-probe mass spectrometry. While excited Rb atoms in the perturbed 6p-state (Rb{sup *}) desorb off the He droplets, Rb{sup +} photoions tend to sink into the droplet interior when created near the droplet surface. The transition from Rb{sup +} solvation to full Rb{sup *} desorption is found to occur at a delay time τ ∼ 600 fs for Rb{sup *} in the 6pΣ-state and τ ∼ 1200 fs for the 6pΠ-state. Rb{sup +}He ions are found to be created by directly exciting bound Rb{sup *}He exciplex states as well as by populating bound Rb{sup +}He-states in a photoassociative ionization process.

Helium nanodroplets. Pump-probe ionization of alkali dopings and spin-echo scattering on undoped drops; Helium-Nanotroepfchen. Pump-Probe-Ionisation von Alkalidotierungen und Spinechostreuung an undotierten Tropfen

Energy Technology Data Exchange (ETDEWEB)

Droppelmann, G.

2005-09-15

In the framework of this thesis several aspects of the properties of helium nanodroplets and their dopings. The formation of the exciplexes RbHe and KHe on helium droplets was studied by means of pump-probe ionization in real time, whereby the main interest lied on the influence of the applied helium isotopes. The experiments with cesium atoms on the droplet surface aimed on the elucidation of the relaxation dynamics of the surface under regardment both of isotope and size effects. From the pump-probe measurements on the formation of the exciplex RbHe on helium nanodroplets performed in the framework of this thesis formation times of 8.5 ps for Rb{sup 4}He and 11.6 ps for Rb{sup 3}He resulted.

Birefringence of cellotape: Jones representation and experimental analysis

International Nuclear Information System (INIS)

Belendez, Augusto; Frances, Jorge; Neipp, Cristian; Fernandez, Elena

2010-01-01

In this paper, we analyse a simple experiment to study the effects of polarized light. A simple optical system composed of a polarizer, a retarder (cellotape) and an analyser is used to study the effect on the polarization state of the light which impinges on the setup. The optical system is characterized by means of a Jones matrix, and a simple procedure based on Jones vectors is used to obtain an expression for the intensity after the light passes through the optical system. The light intensity is measured by a photodetector and the expression obtained theoretically is experimentally validated. By fitting the experimental intensity data, the value of the retardation introduced by the retarder can also be obtained.

Fragmentation dynamics of ionized neon trimer inside helium nanodroplets: a theoretical study.

Science.gov (United States)

Bonhommeau, David; Viel, Alexandra; Halberstadt, Nadine

2004-06-22

We report a theoretical study of the fragmentation dynamics of Ne(3) (+) inside helium nanodroplets, following vertical ionization of the neutral neon trimer. The motion of the neon atoms is treated classically, while transitions between the electronic states of the ionic cluster are treated quantum mechanically. A diatomics-in-molecules description of the potential energy surfaces is used, in a minimal basis set consisting of three effective p orbitals on each neon atom for the missing electron. The helium environment is modeled by a friction force acting on the neon atoms when their speed exceeds the Landau velocity. A reasonable range of values for the corresponding friction coefficient is obtained by comparison with existing experimental measurements. (c) 2004 American Institute of Physics.

Regulatory restrictions and energy: The impact of the Jones Act on spot gasoline prices

International Nuclear Information System (INIS)

Gius, Mark

2013-01-01

The purpose of the present study is to estimate the effects of the Jones Act on spot gasoline prices. Although the Jones Act pertains to the domestic shipment of all types of goods, the present study will only focus on gasoline. The present study will use data obtained from the Energy Information Administration in order to determine if the price of gasoline declined during Jones Act waiver periods. Looking at daily prices, the results regarding the effects of the Jones Act on spot gasoline prices are mixed. When using a t-test, the results indicated either that there was no significant difference or that prices were actually higher during the waiver periods. When using a first-order autoregressive model, it was found that prices were lower during the 2005 waiver period but higher during the 2012 waiver. Given these inconclusive results, it is not possible to conclude that the Jones Act restrictions contribute to higher gasoline prices. - Highlights: • I examine the effect of the Jones Act on spot gasoline prices. • I use daily price data over a seven year period. • I find that the results are mixed. • For the Hurricane Katrina waiver, prices fell, but for the Hurricane Sandy waiver, prices rose

Role of the first coordination shell in determining the equilibrium structure and dynamics of simple liquids

DEFF Research Database (Denmark)

Toxværd, Søren; Dyre, J. C.

2011-01-01

. Lett. 103, 170601 (2009);10.1103/PhysRevLett.103.170601 J. Chem. Phys. 134, 214503 (2011)10.1063/1.3592709] . We present simulations of the standard Lennard-Jones liquid at several condensed-fluid state points, including a fairly low density state and a very high density state, as well as simulations...

Fragmentation dynamics of ionized neon clusters (Ne(n), n=3-14) embedded in helium nanodroplets.

Science.gov (United States)

Bonhommeau, David; Halberstadt, Nadine; Viel, Alexandra

2006-01-14

We report a theoretical study of the nonadiabatic fragmentation dynamics of ionized neon clusters embedded in helium nanodroplets for cluster sizes up to n=14 atoms. The dynamics of the neon atoms is modeled using the molecular dynamics with quantum transitions method of Tully [J. Chem. Phys. 93, 1061 (1990)] with the nuclei treated classically and transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole interactions are added. The effect of the spin-orbit interaction is also discussed. The helium environment is modeled by a friction force acting on charged atoms whose speed exceeds the critical Landau velocity. The dependence of the fragment size distribution on the friction strength and on the initial nanodroplet size is investigated. By comparing with the available experimental data obtained for Ne3+ and Ne4+, a reasonable value for the friction coefficient, the only parameter of the model, is deduced. This value is then used to predict the effect of the helium environment on the dissociation dynamics of larger neon clusters, n=5-14. The results show stabilization of larger fragments than in the gas phase, but fragmentation is not completely caged. In addition, two types of dynamics are characterized for Ne4+: fast and explosive, therefore leaving no time for friction to cool down the process when dynamics starts on one of the highest electronic states, and slower, therefore leading to some stabilization by helium when it starts on one of the lowest electronic states.

Estimating Depolarization with the Jones Matrix Quality Factor

Science.gov (United States)

Hilfiker, James N.; Hale, Jeffrey S.; Herzinger, Craig M.; Tiwald, Tom; Hong, Nina; Schöche, Stefan; Arwin, Hans

2017-11-01

Mueller matrix (MM) measurements offer the ability to quantify the depolarization capability of a sample. Depolarization can be estimated using terms such as the depolarization index or the average degree of polarization. However, these calculations require measurement of the complete MM. We propose an alternate depolarization metric, termed the Jones matrix quality factor, QJM, which does not require the complete MM. This metric provides a measure of how close, in a least-squares sense, a Jones matrix can be found to the measured Mueller matrix. We demonstrate and compare the use of QJM to other traditional calculations of depolarization for both isotropic and anisotropic depolarizing samples; including non-uniform coatings, anisotropic crystal substrates, and beetle cuticles that exhibit both depolarization and circular diattenuation.

Wetting kinetics of water nano-droplet containing non-surfactant nanoparticles: A molecular dynamics study

International Nuclear Information System (INIS)

Lu, Gui; Hu, Han; Sun, Ying; Duan, Yuanyuan

2013-01-01

In this Letter, dynamic wetting of water nano-droplets containing non-surfactant gold nanoparticles on a gold substrate is examined via molecular dynamics simulations. The results show that the addition of non-surfactant nanoparticles hinders the nano-second droplet wetting process, attributed to the increases in both surface tension of the nanofluid and friction between nanofluid and substrate. The droplet wetting kinetics decreases with increasing nanoparticle loading and water-particle interaction energy. The observed wetting suppression and the absence of nanoparticle ordering near the contact line of nano-sized droplets differ from the wetting behaviors reported from nanofluid droplets of micron size or larger

A Viola-Jones based hybrid face detection framework

Science.gov (United States)

Murphy, Thomas M.; Broussard, Randy; Schultz, Robert; Rakvic, Ryan; Ngo, Hau

2013-12-01

Improvements in face detection performance would benefit many applications. The OpenCV library implements a standard solution, the Viola-Jones detector, with a statistically boosted rejection cascade of binary classifiers. Empirical evidence has shown that Viola-Jones underdetects in some instances. This research shows that a truncated cascade augmented by a neural network could recover these undetected faces. A hybrid framework is constructed, with a truncated Viola-Jones cascade followed by an artificial neural network, used to refine the face decision. Optimally, a truncation stage that captured all faces and allowed the neural network to remove the false alarms is selected. A feedforward backpropagation network with one hidden layer is trained to discriminate faces based upon the thresholding (detection) values of intermediate stages of the full rejection cascade. A clustering algorithm is used as a precursor to the neural network, to group significant overlappings. Evaluated on the CMU/VASC Image Database, comparison with an unmodified OpenCV approach shows: (1) a 37% increase in detection rates if constrained by the requirement of no increase in false alarms, (2) a 48% increase in detection rates if some additional false alarms are tolerated, and (3) an 82% reduction in false alarms with no reduction in detection rates. These results demonstrate improved face detection and could address the need for such improvement in various applications.

Growing correlation length on cooling below the onset of caging in a simulated glass-forming liquid

DEFF Research Database (Denmark)

Lačević, N.; Starr, F. W.; Schrøder, Thomas

2002-01-01

We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporal correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale...... of the dynamics of the liquid in the alpha-relaxation regime....

Dextran-shelled oxygen-loaded nanodroplets reestablish a normoxia-like pro-angiogenic phenotype and behavior in hypoxic human dermal microvascular endothelium

International Nuclear Information System (INIS)

Basilico, Nicoletta; Magnetto, Chiara; D'Alessandro, Sarah; Panariti, Alice; Rivolta, Ilaria; Genova, Tullio; Khadjavi, Amina; Gulino, Giulia Rossana; Argenziano, Monica; Soster, Marco

2015-01-01

In chronic wounds, hypoxia seriously undermines tissue repair processes by altering the balances between pro-angiogenic proteolytic enzymes (matrix metalloproteinases, MMPs) and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) released from surrounding cells. Recently, we have shown that in human monocytes hypoxia reduces MMP-9 and increases TIMP-1 without affecting TIMP-2 secretion, whereas in human keratinocytes it reduces MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. Provided that the phenotype of the cellular environment is better understood, chronic wounds might be targeted by new oxygenating compounds such as chitosan- or dextran-shelled and 2H,3H-decafluoropentane-cored oxygen-loaded nanodroplets (OLNs). Here, we investigated the effects of hypoxia and dextran-shelled OLNs on the pro-angiogenic phenotype and behavior of human dermal microvascular endothelium (HMEC-1 cell line), another cell population playing key roles during wound healing. Normoxic HMEC-1 constitutively released MMP-2, TIMP-1 and TIMP-2 proteins, but not MMP-9. Hypoxia enhanced MMP-2 and reduced TIMP-1 secretion, without affecting TIMP-2 levels, and compromised cell ability to migrate and invade the extracellular matrix. When taken up by HMEC-1, nontoxic OLNs abrogated the effects of hypoxia, restoring normoxic MMP/TIMP levels and promoting cell migration, matrix invasion, and formation of microvessels. These effects were specifically dependent on time-sustained oxygen diffusion from OLN core, since they were not achieved by oxygen-free nanodroplets or oxygen-saturated solution. Collectively, these data provide new information on the effects of hypoxia on dermal endothelium and support the hypothesis that OLNs might be used as effective adjuvant tools to promote chronic wound healing processes. - Highlights: • Hypoxia enhances MMP-2 and reduces TIMP-1 secretion by dermal HMEC-1 cell line. • Hypoxia compromises migration and matrix invasion abilities of

Dextran-shelled oxygen-loaded nanodroplets reestablish a normoxia-like pro-angiogenic phenotype and behavior in hypoxic human dermal microvascular endothelium

Energy Technology Data Exchange (ETDEWEB)

Basilico, Nicoletta, E-mail: nicoletta.basilico@unimi.it [Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università di Milano, via Pascal 36, 20133 Milano (Italy); Magnetto, Chiara, E-mail: c.magnetto@inrim.it [Istituto Nazionale di Ricerca Metrologica (INRIM), Strada delle Cacce, 91, 10135 Torino (Italy); D' Alessandro, Sarah, E-mail: sarah.dalessandro@unimi.it [Dipartimento di Scienze Farmacologiche e Biomolecolari, Università di Milano, via Pascal 36, 20133 Milano (Italy); Panariti, Alice, E-mail: alice.panariti@mail.mcgill.ca [Dipartimento di Scienze della Salute, Università di Milano Bicocca, Via Cadore 48, 20900 Monza (Italy); Rivolta, Ilaria, E-mail: ilaria.rivolta@unimib.it [Dipartimento di Scienze della Salute, Università di Milano Bicocca, Via Cadore 48, 20900 Monza (Italy); Genova, Tullio, E-mail: tullio.genova@unito.it [Dipartimento di Scienze della Vita e Biologia dei Sistemi, Via Accademia Albertina 13, 10123 Torino (Italy); Khadjavi, Amina, E-mail: amina.khadjavi@unito.it [Dipartimento di Neuroscienze, Università di Torino, Corso Raffaello 30, 10125 Torino (Italy); Gulino, Giulia Rossana, E-mail: giuliarossana.gulino@unito.it [Dipartimento di Oncologia, Università di Torino, Via Santena 5 bis, 10126 Torino (Italy); Argenziano, Monica, E-mail: monica.argenziano@unito.it [Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via Giuria, 9, 10125 Torino (Italy); Soster, Marco, E-mail: marco.soster@unito.it [Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via Giuria, 9, 10125 Torino (Italy); and others

2015-11-01

In chronic wounds, hypoxia seriously undermines tissue repair processes by altering the balances between pro-angiogenic proteolytic enzymes (matrix metalloproteinases, MMPs) and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) released from surrounding cells. Recently, we have shown that in human monocytes hypoxia reduces MMP-9 and increases TIMP-1 without affecting TIMP-2 secretion, whereas in human keratinocytes it reduces MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. Provided that the phenotype of the cellular environment is better understood, chronic wounds might be targeted by new oxygenating compounds such as chitosan- or dextran-shelled and 2H,3H-decafluoropentane-cored oxygen-loaded nanodroplets (OLNs). Here, we investigated the effects of hypoxia and dextran-shelled OLNs on the pro-angiogenic phenotype and behavior of human dermal microvascular endothelium (HMEC-1 cell line), another cell population playing key roles during wound healing. Normoxic HMEC-1 constitutively released MMP-2, TIMP-1 and TIMP-2 proteins, but not MMP-9. Hypoxia enhanced MMP-2 and reduced TIMP-1 secretion, without affecting TIMP-2 levels, and compromised cell ability to migrate and invade the extracellular matrix. When taken up by HMEC-1, nontoxic OLNs abrogated the effects of hypoxia, restoring normoxic MMP/TIMP levels and promoting cell migration, matrix invasion, and formation of microvessels. These effects were specifically dependent on time-sustained oxygen diffusion from OLN core, since they were not achieved by oxygen-free nanodroplets or oxygen-saturated solution. Collectively, these data provide new information on the effects of hypoxia on dermal endothelium and support the hypothesis that OLNs might be used as effective adjuvant tools to promote chronic wound healing processes. - Highlights: • Hypoxia enhances MMP-2 and reduces TIMP-1 secretion by dermal HMEC-1 cell line. • Hypoxia compromises migration and matrix invasion abilities of

Divergence of activity expansions: Is it actually a problem?

Science.gov (United States)

Ushcats, M. V.; Bulavin, L. A.; Sysoev, V. M.; Ushcats, S. Yu.

2017-12-01

For realistic interaction models, which include both molecular attraction and repulsion (e.g., Lennard-Jones, modified Lennard-Jones, Morse, and square-well potentials), the asymptotic behavior of the virial expansions for pressure and density in powers of activity has been studied taking power terms of high orders into account on the basis of the known finite-order irreducible integrals as well as the recent approximations of infinite irreducible series. Even in the divergence region (at subcritical temperatures), this behavior stays thermodynamically adequate (in contrast to the behavior of the virial equation of state with the same set of irreducible integrals) and corresponds to the beginning of the first-order phase transition: the divergence yields the jump (discontinuity) in density at constant pressure and chemical potential. In general, it provides a statistical explanation of the condensation phenomenon, but for liquid or solid states, the physically proper description (which can turn the infinite discontinuity into a finite jump of density) still needs further study of high-order cluster integrals and, especially, their real dependence on the system volume (density).

The importance of accurate interaction potentials in the melting of argon nanoclusters

Science.gov (United States)

Pahl, E.; Calvo, F.; Schwerdtfeger, P.

The melting temperatures of argon clusters ArN (N = 13, 55, 147, 309, 561, and 923) and of bulk argon have been obtained from exchange Monte Carlo simulations and are compared using different two-body interaction potentials, namely the standard Lennard-Jones (LJ), Aziz and extended Lennard-Jones (ELJ) potentials. The latter potential has many advantages: while maintaining the computational efficiency of the commonly used LJ potential, it is as accurate as the Aziz potential but the computer time scales more favorably with increasing cluster size. By applying the ELJ form and extrapolating the cluster data to the infinite system, we are able to extract the melting point of argon already in good agreement with experimental measurements. By considering the additional Axilrod-Teller three-body contribution as well, we calculate a melting temperature of T meltELJ = 84.7 K compared to the experimental value of T meltexp = 83.85 K, whereas the LJ potential underestimates the melting point by more than 7 K. Thus melting temperatures within 1 K accuracy are now feasible.

A simple extrapolation of thermodynamic perturbation theory to infinite order

International Nuclear Information System (INIS)

Ghobadi, Ahmadreza F.; Elliott, J. Richard

2015-01-01

Recent analyses of the third and fourth order perturbation contributions to the equations of state for square well spheres and Lennard-Jones chains show trends that persist across orders and molecular models. In particular, the ratio between orders (e.g., A 3 /A 2 , where A i is the ith order perturbation contribution) exhibits a peak when plotted with respect to density. The trend resembles a Gaussian curve with the peak near the critical density. This observation can form the basis for a simple recursion and extrapolation from the highest available order to infinite order. The resulting extrapolation is analytic and therefore cannot fully characterize the critical region, but it remarkably improves accuracy, especially for the binodal curve. Whereas a second order theory is typically accurate for the binodal at temperatures within 90% of the critical temperature, the extrapolated result is accurate to within 99% of the critical temperature. In addition to square well spheres and Lennard-Jones chains, we demonstrate how the method can be applied semi-empirically to the Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT)

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.

Carbon nanotori as traps for atoms and ions

International Nuclear Information System (INIS)

Chan Yue; Cox, Barry J.; Hill, James M.

2012-01-01

Carbon nanotori surely represent an ideal location to trap both charged and uncharged atoms, since they are open, accessible and possess strong attractive energy. In this paper, we investigate the plausibility of carbon nanotori as atomic traps and we use the continuum approximation together with the Lennard-Jones potential to model the encapsulation of an atom or ion by a nanotorus. The critical geometric factors such as the minor and major radii, i.e. r and R of the nanotorus, for which the maximum interaction between the atom and the nanotorus occurs, are determined. For various atoms, assumed situated along the axis of the torus, the minimum potential energy between the atom and the nanotorus is calculated and compared, and shown to be approximately kηεσ 2 , where η is the uniform atomic density, ε and σ are the Lennard-Jones well depth and the van der Waals radius, respectively, and k is a universal non-dimensional constant with the approximate value -12.42. The results given in this paper might be used for future drug delivery and biosensing design.

Droplet spreading driven by van der Waals force: a molecular dynamics study

KAUST Repository

Wu, Congmin

2010-07-07

The dynamics of droplet spreading is investigated by molecular dynamics simulations for two immiscible fluids of equal density and viscosity. All the molecular interactions are modeled by truncated Lennard-Jones potentials and a long-range van der Waals force is introduced to act on the wetting fluid. By gradually increasing the coupling constant in the attractive van der Waals interaction between the wetting fluid and the substrate, we observe a transition in the initial stage of spreading. There exists a critical value of the coupling constant, above which the spreading is pioneered by a precursor film. In particular, the dynamically determined critical value quantitatively agrees with that determined by the energy criterion that the spreading coefficient equals zero. The latter separates partial wetting from complete wetting. In the regime of complete wetting, the radius of the spreading droplet varies with time as R(t) ∼ √t, a behavior also found in molecular dynamics simulations where the wetting dynamics is driven by the short-range Lennard-Jones interaction between liquid and solid. © 2010 IOP Publishing Ltd.

Interaction of 3D dewetting nanodroplets on homogeneous and chemically heterogeneous substrates

International Nuclear Information System (INIS)

Asgari, M; Moosavi, A

2014-01-01

Long-time interaction of dewetting nanodroplets is investigated using a long-wave approximation method. Although three-dimensional (3D) droplets evolution dynamics exhibits qualitative behavior analogous to two-dimensional (2D) dynamics, there is an extensive quantitative difference between them. 3D dynamics is substantially faster than 2D dynamics. This can be related to the larger curvature and, as a consequence, the larger Laplace pressure difference between the droplets in 3D systems. The influence of various chemical heterogeneities on the behavior of droplets has also been studied. In the case of gradient surfaces, it is shown how the gradient direction could change the dynamics. For a chemical step located between the droplets, the dynamics is enhanced or weakened depending on the initial configuration of the system. (paper)

Staging Henry Fielding: The Author-Narrator in Tom Jones On Screen

OpenAIRE

Løfaldli, Eli

2017-01-01

As recent adaptation theory has shown, classic-novel adaptation typically sets issues connected to authorship and literal and figurative ownership into play. This key feature of such adaptations is also central to the screen versions of Henry Fielding’s Tom Jones (1749). In much of Fielding’s fiction, the narrator, typically understood as an embodiment of Fielding himself, is a particularly prominent presence. The author-narrator in Tom Jones is no exception: not only is his presence strongly...

Magnetoelectric Jones birefringence and dichroism in a medium of free atoms

International Nuclear Information System (INIS)

Mironova, P V; Ovsiannikov, V D; Chernushkin, V V

2006-01-01

Theoretical treatment of the magnetoelectric Jones birefringence and dichroism is developed through the bilinearity in static electric and magnetic field dipole-forbidden corrections to the amplitude of Rayleigh scattering. In particular cases of orientation of the static fields relative to the polarization and wave vectors of monochromatic radiation, the amplitude determines corrections to the refractive index of atomic gas responsible for (i) the Jones birefringence and dichroism (ii) linear birefringence and dichroism and (iii) directional anisotropy for the monochromatic wave. The analytical equations and numerical data for the indicated corrections, calculated for alkaline-earth-like atoms, determine optimal conditions for observing the effects in vapours. For resonance on 1 D 2 state essential enhancement is discovered in the frequency dependence for the ratio of refractive index anisotropy of the Jones effect to the square-root product of corresponding anisotropies determining the Kerr and Cotton-Mouton effects

Prevalence of Jones Fracture Repair and Impact on Short-Term NFL Participation.

Science.gov (United States)

Tu, Leigh-Anne; Knapik, Derrick M; Sheehan, Joseph; Salata, Michael J; Voos, James E

2018-01-01

Elite American football athletes are at high risk for Jones fractures. Fixation is recommended to minimize nonunion and allow early return to play. The purpose of this investigation was to evaluate the prevalence of Jones fracture repair in athletes invited to the National Football League (NFL) Combine and the impact of fracture repair on short-term NFL participation compared to athletes with no history of repair. A total of 1311 athletes participating in the Combine from 2012 to 2015 were evaluated. Athletes with history of Jones fracture repair were identified. Athlete demographic information was collected while physical examination findings were recorded. Radiographs were evaluated to determine fixation type and the presence of nonunion. Future participation in the NFL was evaluated based on draft status, games played, and games started in the athlete's first season following the Combine. Fixation was performed for 41 Jones fractures in 40 athletes (3.1%). The highest prevalence was in defensive linemen (n = 10 athletes), with the greatest rate in tight ends (5.1%, n = 4 of 79 athletes). Intramedullary screw fixation was used for all fractures. Incomplete bony union was present in 3 (8%) fractures. Athletes with a history of repair were not at significant risk for going undrafted ( P = .61), playing ( P = .23), or starting ( P = .76) fewer NFL games compared to athletes with no history of repair during athletes' first NFL season. Athletes with a history of Jones fracture repair were not at significant risk of going undrafted or for diminished participation during their first season in the NFL. Level IV, case series.

Density-scaling exponents and virial potential-energy correlation ...

Indian Academy of Sciences (India)

This paper investigates the relation between the density-scaling exponent γ and the virial potential energy correlation coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ system in two,three, and ...

HNC variational calculations of boson matter

International Nuclear Information System (INIS)

Lantto, L.J.; Jackson, A.D.; Siemens, P.J.

1977-01-01

A simple and reliable numerical technique is given for determining the two-body distribution function which minimizes the HNC energy of boson matter. Numerical results are presented for the neutron matter homework problem and the 4 He Lennard-Jones potential. The resulting distribution function is found to have proper asymptotic behaviour and yields reasonable binding energies. (Auth.)

Early Experience with the StopLoss Jones Tube.

Science.gov (United States)

Bagdonaite, Laura; Pearson, Andrew R

2015-06-01

Extrusion is the most common reason for failure after Jones tube placement. The StopLoss Jones tube (SLJT) is a new innovation in Jones tubes that incorporates a flexible silicone internal flange to resist extrusion. We present our early experience of using this new tube and associated introducer system. We retrospectively analysed the case notes of a single surgeon consecutive series of patients having SLJT placement from November 2011 to November 2013. 29 SLJTs were placed in 25 eyes of 19 patients. Tube follow-up ranged from 1-25 months (mean 10 months) with a total of 291 tube-months. The indications for SLJT placement were: previous LJT complications (52%), failed canalicular-DCR surgery (31%), primary placement for inoperable canalicular occlusion (14%) and patent non-functioning DCR (3%). Tube length ranged from 10-16 mm. The tube introducer system was simple and effective and there were no intra-operative complications. The tube extrusion rate was 0%. Complications occurred in 5 tubes: 1 was too long, and 4 others (14%) developed conjunctival overgrowth/medial tube migration. Patient satisfaction with the tube was: 86% fully satisfied, 10% was moderately satisfied, 3% not satisfied. The overall final surgical success rate at last follow-up was 92%. In this short follow-up initial study the SLJT is simple to use and has a high rate of success and patient satisfaction. The addition of the internal silicone flange appears to prevent the previously common problem of extrusion.

Nanodroplet processing platform for deep and quantitative proteome profiling of 10-100 mammalian cells.

Science.gov (United States)

Zhu, Ying; Piehowski, Paul D; Zhao, Rui; Chen, Jing; Shen, Yufeng; Moore, Ronald J; Shukla, Anil K; Petyuk, Vladislav A; Campbell-Thompson, Martha; Mathews, Clayton E; Smith, Richard D; Qian, Wei-Jun; Kelly, Ryan T

2018-02-28

Nanoscale or single-cell technologies are critical for biomedical applications. However, current mass spectrometry (MS)-based proteomic approaches require samples comprising a minimum of thousands of cells to provide in-depth profiling. Here, we report the development of a nanoPOTS (nanodroplet processing in one pot for trace samples) platform for small cell population proteomics analysis. NanoPOTS enhances the efficiency and recovery of sample processing by downscaling processing volumes to 3000 proteins are consistently identified from as few as 10 cells. Furthermore, we demonstrate quantification of ~2400 proteins from single human pancreatic islet thin sections from type 1 diabetic and control donors, illustrating the application of nanoPOTS for spatially resolved proteome measurements from clinical tissues.

Dow Jones tugevdab oma koostist / Virge Lahe

Index Scriptorium Estoniae

Lahe, Virge

2008-01-01

USA tööstusettevõtteid koondav indeks Dow Jones vahetab nimekirjast välja kaks firmat ning lisab finants- ja kütusesektori osakaalu suurendamiseks Bank of America ja Chevroni. Vt. samas: Dow Jonesi tööstuskeskmisse lisandumine pole aktsiatele tiibu andnud; Dow Jonesi tööstuskeskmine

Return to Play and Performance After Jones Fracture in National Basketball Association Athletes

Science.gov (United States)

Begly, John P.; Guss, Michael; Ramme, Austin J.; Karia, Raj; Meislin, Robert J.

2015-01-01

Background: Basketball players are at risk for foot injuries, including Jones fractures. It is unknown how this injury affects the future play and performance of athletes. Hypothesis: National Basketball Association (NBA) players who sustain Jones fractures of the base of the fifth metatarsal have high rates of return to play and do not experience a decrease in performance on return to competition when compared with preinjury and with control-matched peers. Study Design: Retrospective cohort study. Level of Evidence: Level 5. Methods: Data on 26 elite basketball players with Jones fractures over 19 NBA seasons (1994-1995 to 2012-2013) were obtained from injury reports, press releases, player profiles, and online public databases. Variables included age, body mass index (BMI), player position, experience, and surgical treatment. Individual season statistics pre- and postinjury were collected. Twenty-six controls were identified by matched player position, age, and performance statistics. Results: The mean age at the time of injury was 24.8 years, mean BMI was 24.7 kg/m2, and the mean experience prior to injury was 4.1 NBA seasons. Return to previous level of competition was achieved by 85% of athletes. There was no change in player efficiency rating (PER) when pre- and postinjury performance was compared. When compared with controls, no decline in PER measured performance was identified. Conclusion: The majority of NBA players sustaining a Jones fracture return to their preinjury level of competition. These elite athletes demonstrate no decrease in performance on their return to play. Clinical Relevance: Jones fractures are well-studied injuries in terms of etiology, diagnosis, and management. However, the effect of these injuries on future performance of athletes is unknown. Using the findings of our study, orthopaedic surgeons may be better prepared to counsel and educate elite athletes who sustain a Jones fracture. PMID:26627111

Return to Play and Performance After Jones Fracture in National Basketball Association Athletes.

Science.gov (United States)

Begly, John P; Guss, Michael; Ramme, Austin J; Karia, Raj; Meislin, Robert J

2016-07-01

Basketball players are at risk for foot injuries, including Jones fractures. It is unknown how this injury affects the future play and performance of athletes. National Basketball Association (NBA) players who sustain Jones fractures of the base of the fifth metatarsal have high rates of return to play and do not experience a decrease in performance on return to competition when compared with preinjury and with control-matched peers. Retrospective cohort study. Level 5. Data on 26 elite basketball players with Jones fractures over 19 NBA seasons (1994-1995 to 2012-2013) were obtained from injury reports, press releases, player profiles, and online public databases. Variables included age, body mass index (BMI), player position, experience, and surgical treatment. Individual season statistics pre- and postinjury were collected. Twenty-six controls were identified by matched player position, age, and performance statistics. The mean age at the time of injury was 24.8 years, mean BMI was 24.7 kg/m(2), and the mean experience prior to injury was 4.1 NBA seasons. Return to previous level of competition was achieved by 85% of athletes. There was no change in player efficiency rating (PER) when pre- and postinjury performance was compared. When compared with controls, no decline in PER measured performance was identified. The majority of NBA players sustaining a Jones fracture return to their preinjury level of competition. These elite athletes demonstrate no decrease in performance on their return to play. Jones fractures are well-studied injuries in terms of etiology, diagnosis, and management. However, the effect of these injuries on future performance of athletes is unknown. Using the findings of our study, orthopaedic surgeons may be better prepared to counsel and educate elite athletes who sustain a Jones fracture. © 2015 The Author(s).

System of multifunctional Jones matrix tomography of phase anisotropy in diagnostics of endometriosis

Science.gov (United States)

Ushenko, V. O.; Koval, G. D.; Ushenko, Yu. O.; Pidkamin, L. Y.; Sidor, M. I.; Vanchuliak, O.; Motrich, A. V.; Gorsky, M. P.; Meglinskiy, I.

2017-09-01

The paper presents the results of Jones-matrix mapping of uterine wall histological sections with second-degree and third-degree endometriosis. The technique of experimental measurement of coordinate distributions of the modulus and phase values of Jones matrix elements is suggested. Within the statistical and cross-correlation approaches the modulus and phase maps of Jones matrix images of optically thin biological layers of polycrystalline films of plasma and cerebrospinal fluid are analyzed. A set of objective parameters (statistical and generalized correlation moments), which are the most sensitive to changes in the phase of anisotropy, associated with the features of polycrystalline structure of uterine wall histological sections with second-degree and third-degree endometriosis are determined.

Dynamics of photoexcited Ba{sup +} cations in {sup 4}He nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Leal, Antonio; Pi, Martí [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Zhang, Xiaohang; Drabbels, Marcel [Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Barranco, Manuel [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France); Cargnoni, Fausto [Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano (Italy); Hernando, Alberto [Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Bâtiment C, CH-1015 Lausanne (Switzerland); Mateo, David [Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, California 91330 (United States); Mella, Massimo [Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell’Insubria, via Valleggio 11, 22100 Como (Italy)

2016-03-07

We present a joint experimental and theoretical study on the desolvation of Ba{sup +} cations in {sup 4}He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba{sup +} cations and Ba{sup +}He{sub n} exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba{sup +} He{sub n} exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba{sup +}. In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba{sup +} cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba{sup +} cations or exciplexes, even when relaxation pathways to lower lying states are included.

E-tailing in Australia: A preliminary analysis of David Jones

Directory of Open Access Journals (Sweden)

Jun Xu

2017-06-01

Full Text Available Compared with other countries, especially China, United States, United Kingdom, Japan and Germany, Australiars online retail fall behind in terms of both its sale and percentage contribution to the total retail. This paper analyses David Jones, which is typical of large department store chains, and Australian e-tailing environment as a case study to identify enablers for and obstacle to the advancement of e-tailing in Australia. Based on the analysis, the paper provides David Jones with recommendations on internal improvement, supply chain, customer relationship, and adoption of emerging technologies. Future research will be conducted to investigate if the recommendations are also applicable for other Australian retailers.

Four crystal forms of a Bence-Jones protein

International Nuclear Information System (INIS)

Makino, Debora L.; Henschen-Edman, Agnes H.; McPherson, Alexander

2004-01-01

Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40 y ago. The trigonal crystal form may shed some light on the formation of fibrils common to certain storage diseases. Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40 years ago. Closely related tetragonal and orthorhombic forms belonging to space groups P4 3 2 1 2 and P2 1 2 1 2 1 , with unit-cell parameters a = b = 68.7, c = 182.1 and a = 67.7, b = 69.4, c = 87.3 Å, diffract to 1.5 and 1.9 Å, respectively. Two closely related trigonal forms, both belonging to space group P3 1 21 with unit-cell parameters a = b = 154.3 Å but differing by a doubling of the c axis, one 46.9 Å and the other 94.0 Å, diffract to 2.9 and 2.6 Å resolution, respectively. The trigonal crystal of short c-axis length shows a positive indication of twinning. The trigonal crystal of longer c axis, which appeared only after eight months of incubation at room temperature, is likely to be composed of proteolytically degraded molecules and unlike the other crystal forms contains two entire Bence-Jones dimers in the asymmetric unit. This latter crystal form may shed some light on the formation of fibrils common to certain storage diseases

Shelley Jones: Helping Ugandan girls stay in school | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Shelley Jones with her Masters of Education students debating gender issues ... early pregnancies, limited family support, or educational gender discrimination.” ... Girls' Secondary Education in Uganda: Assessing Policy within the Women's ...

Do America's Schools Need a "Dow Jones Index"?

Science.gov (United States)

Guthrie, James W.

1994-01-01

Discusses America's fascination with measuring education. Discusses the advantages and disadvantages of a single composite indicator, akin to the Dow Jones Index, to measure educational productivity. Describes progress in the California State Education Department in developing a composite index to measure student performance. (SR)

Obituary: Frank Culver Jones, 1932-2007

Science.gov (United States)

Ormes, Johnathan F.; Streitmatter, Robert E.

2007-12-01

Frank C. Jones, an emeritus theoretical physicist at NASA, died May 2, 2007 at age 74 after a struggle with a rare form of cancer. He died at his home in Silver Spring, Maryland, surrounded by his family. Frank was born July 30, 1932 in Fort Worth, Texas, the oldest of three boys. His parents were Kenneth Hugh and Nancy Culver Jones. Frank's father was a lawyer, and his grandfather was a Methodist minister. Frank graduated from Rice University in 1954 and earned a master's degree in 1955 and a doctorate in 1961, both in physics, from the University of Chicago. He did his graduate work with Prof. John Simpson. Dr. Jones began his professional career as an instructor in physics at Princeton University before joining NASA's Goddard Space Flight Center in 1963 as a National Research Council associate. He subsequently became a member of the Theory Division and the Laboratory for High Energy Astrophysics. His area of expertise was the origin, transport, and electromagnetic interactions of cosmic rays. His particular focus was the stochastic physics related to the diffusion of particles in random fields, plasma turbulence, and the shock acceleration of charged particles in collisionless plasmas. From 1993 to 1995, Frank was head of Goddard's Theoretical High Energy Astrophysics Office and continued to serve as Head of the Theory group. In 2003 he served as Acting Chief of the Laboratory for High Energy Astrophysics. He retired in 2005 and continued his affiliation with NASA as an emeritus scientist at Goddard until his death. As a youngster, Frank showed the signs of curiosity and initiative that indicated he might become an experimentalist. At the memorial service for Frank, his brother related the stories of how Frank had rigged a hidden microphone to play through the family television as his brother courted a young woman on the front porch swing, and how one of Frank's early chemistry experiments caused all the family silverware to turn black. Although Frank started

Stochasticity thresholds in the Fermi-Pasta-Ulam model

Energy Technology Data Exchange (ETDEWEB)

Callegari, B [Ferrara Univ. (Italy). Ist. di Matematica; Carotta, M C; Ferrario, C [Ferrara Univ. (Italy). Ist. di Fisica; Lo Vecchio, G [Ferrara Univ. (Italy). Ist. di Fisica; Gruppo Nazionale di Struttura della Materia, Ferrara (Italy)); Galgani, L [Milan Univ. (Italy). Ist. di Fisica; Milan Univ. (Italy). Ist. di Matematica)

1979-12-11

The authors consider the celebrated model of Fermi, Pasta and Ulam and give a numerical estimate for its thresholds of stochasticity, thus determining a critical energy as a function of the frequency of the corresponding oscillators. The results turn out to be qualitatively similar to those already obtained for a chain of particles with nearest-neighbour Lennard-Jones interaction potential.

The second virial coefficients of some halogenated ethanes

Science.gov (United States)

Kohler, Friedrich; van Nhu, Nguyen

The second virial coefficients of 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane and 1-chloro-1,1-difluoroethane have been calculated on the basis of two-centre-Lennard-Jones + superimposed dipole model potentials and compared with experimental results. These can be explained taking into account the reduced dipole moments and the angle between dipole moment and molecular axis.

Stochasticity thresholds in the Fermi-Pasta-Ulam model

International Nuclear Information System (INIS)

Callegari, B.; Galgani, L.; Milan Univ.

1979-01-01

The authors consider the celebrated model of Fermi, Pasta and Ulam and give a numerical estimate for its thresholds of stochasticity, thus determining a critical energy as a function of the frequency of the corresponding oscillators. The results turn out to be qualitatively similar to those already obtained for a chain of particles with nearest-neighbour Lennard-Jones interaction potential. (author)

Some aspects of equations of state

International Nuclear Information System (INIS)

Frisch, H.L.

1979-02-01

Some elementary properties of the equation of state of molecules repulsing each other as point centers of force are developed briefly. An inequality for the Lennard--Jones gas is presented. The scaled particle theory equation of state of hard spheres is also reviewed briefly. Means of possibly applying these concepts to represent thermodynamic data on model detonating gases are suggested

Pendeteksian Bagian Tubuh Manusia untuk Filter Pornografi dengan Metode Viola-Jones

Directory of Open Access Journals (Sweden)

Benny Senjaya

2012-06-01

Full Text Available Information Technology does help people to get information promptly anytime and anywhere. Unfortunately, the information gathered from the Internet does not always come out positive. Some information can be destructive, such as porn images. To mitigate this problem, the study aims to create a desktop application that could detect parts of human body which can be expanded in the future to become an image filter application for pornography. The detection methodology in this study is Viola-Jones method which provides a complete framework for extracting and recognizing image features. A combination of Viola-Jones method with Haar-like features, integral image, boosting algorithm, and cascade classifier provide a robust detector for the application. First, several parts of the human body are chosen to be detected as the data training using the Viola-Jones method. Then, another set of images (similar body parts but different images are run through the application to be recognized. The result shows 86.25% of successful detection. The failures are identified and show that the inputted data are completely different with the data training.

Occurrence of pathotypes of Ascochyta pinodes (Jones in the Olsztyn district

Directory of Open Access Journals (Sweden)

Helena Furgał-Węgrzycka

2013-12-01

Full Text Available The causal agent of leaf and pods spot-pot of peas and field peas in the Olsztyn district was the fungus Ascochyta pinodes (Jones. Investigated isolates of A. pinoides different by macroscopic and microscopic features. From diseased leaves and pods of peas and field peas saprophytic fungi were also obtained. Among them Alternaria alternata, Cladosporium cladosporioides, Epicoccum purpurascens, Stemphylium botryosum, Sordaria fimicola and mycelia sterilia were dominant. In the study on the identification and distribution of pathotypes of A. pinodes (Jones six pathotypes were identified among which pathotypes 3 dominated. The identified pathotypes differed by macroscopic and microscopic features.

Four crystal forms of a Bence-Jones protein

Energy Technology Data Exchange (ETDEWEB)

Makino, Debora L.; Henschen-Edman, Agnes H.; McPherson, Alexander, E-mail: amcphers@uci.edu [Molecular Biology and Biochemistry, University of California, Irvine, 560 Steinhaus Hall, Irvine, CA 92697-3900 (United States)

2005-01-01

Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40 y ago. The trigonal crystal form may shed some light on the formation of fibrils common to certain storage diseases. Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40 years ago. Closely related tetragonal and orthorhombic forms belonging to space groups P4{sub 3}2{sub 1}2 and P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = b = 68.7, c = 182.1 and a = 67.7, b = 69.4, c = 87.3 Å, diffract to 1.5 and 1.9 Å, respectively. Two closely related trigonal forms, both belonging to space group P3{sub 1}21 with unit-cell parameters a = b = 154.3 Å but differing by a doubling of the c axis, one 46.9 Å and the other 94.0 Å, diffract to 2.9 and 2.6 Å resolution, respectively. The trigonal crystal of short c-axis length shows a positive indication of twinning. The trigonal crystal of longer c axis, which appeared only after eight months of incubation at room temperature, is likely to be composed of proteolytically degraded molecules and unlike the other crystal forms contains two entire Bence-Jones dimers in the asymmetric unit. This latter crystal form may shed some light on the formation of fibrils common to certain storage diseases.

High and Crazy Niggers: Anti-Rationalism in Leroi Jones

Science.gov (United States)

Brown, Lloyd W.

1974-01-01

Suggests that the assumption that the theme of anti-rationalism in Jones is an attack on reason as such and that such a theme rests on an exclusive commitment to the irrational needs to be tested. (Author/AM)

Solvation in atomic liquids: connection between Gaussian field theory and density functional theory

Directory of Open Access Journals (Sweden)

V. Sergiievskyi

2017-12-01

Full Text Available For the problem of molecular solvation, formulated as a liquid submitted to the external potential field created by a molecular solute of arbitrary shape dissolved in that solvent, we draw a connection between the Gaussian field theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical density functional theory. We show that Chandler's results concerning the solvation of a hard core of arbitrary shape can be recovered by either minimising a linearised HNC functional using an auxiliary Lagrange multiplier field to impose a vanishing density inside the core, or by minimising this functional directly outside the core — indeed a simpler procedure. Those equivalent approaches are compared to two other variants of DFT, either in the HNC, or partially linearised HNC approximation, for the solvation of a Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to Monte-Carlo simulations, all those theories give acceptable results for the inhomogeneous solvent structure, but are completely out-of-range for the solvation free-energies. This can be fixed in DFT by adding a hard-sphere bridge correction to the HNC functional.

A study on the contact angles of a water droplet on smooth and rough solid surfaces

International Nuclear Information System (INIS)

Park, Ju Young; Ha, Man Yeong; Choi, Ho Jin; Hong, Seung Do; Yoon, Hyun Sik

2011-01-01

We investigated the wetting characteristics such as contact angle, wetting radius and topography of water droplets on smooth and random solid surfaces. Molecular dynamic simulation is employed to analyze the wetting behavior of water droplets on smooth and rough surfaces by considering different potential energy models of bond, angle, Lennard-Jones and Coulomb to calculate the interacting forces between water molecules. The Lennard-Jones potential energy model is adopted as an interaction model between water molecules and solid surface atoms. The randomly rough surface is generated by changing the standard deviation of roughness height from 1 A to 3 A with the fixed autocorrelation length. The size of water droplet considered is in the range from 2,000 to 5,000 molecules. The contact angles increase generally with increasing number of water molecules. For a hydrophobic surface whose characteristic energy is 0.1 kcal/mol, the contact angles depend rarely on the standard deviation of the roughness height. However, when the surface energy is 0.5 and 1.0 kcal/mol, the contact angles depend on both the roughness height of surfaces and droplet size

Combination Rules for Morse-Based van der Waals Force Fields.

Science.gov (United States)

Yang, Li; Sun, Lei; Deng, Wei-Qiao

2018-02-15

In traditional force fields (FFs), van der Waals interactions have been usually described by the Lennard-Jones potentials. Conventional combination rules for the parameters of van der Waals (VDW) cross-termed interactions were developed for the Lennard-Jones based FFs. Here, we report that the Morse potentials were a better function to describe VDW interactions calculated by highly precise quantum mechanics methods. A new set of combination rules was developed for Morse-based FFs, in which VDW interactions were described by Morse potentials. The new set of combination rules has been verified by comparing the second virial coefficients of 11 noble gas mixtures. For all of the mixed binaries considered in this work, the combination rules work very well and are superior to all three other existing sets of combination rules reported in the literature. We further used the Morse-based FF by using the combination rules to simulate the adsorption isotherms of CH 4 at 298 K in four covalent-organic frameworks (COFs). The overall agreement is great, which supports the further applications of this new set of combination rules in more realistic simulation systems.

Effect of temperature dependence of the Langmuir constant molecular pair potentials on gas hydrates formation mechanism

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, B.; Enayati, M. [Iranian Offshore Oil Co., Tehran (Iran, Islamic Republic of); Heidaryan, E. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Masjidosolayman Branch

2008-07-01

Theoretical methods show that crystalline hydrates can form from single-phase systems consisting of both vapor water with gaseous hydrate former and liquid water with dissolved hydrate former. Two phase systems consist of both liquid water with gaseous hydrate former and with liquid hydrate former on the surface. This paper presented a Langmuir constant related model for the prediction of equilibrium pressures and cage occupancies of pure component hydrates. Intermolecular potentials were fit to quantum mechanical energies to obtain the Langmuir constants, which differed from the procedure utilized with the vdWP model. The paper described the experimental method and model calculations. This included the Fugacity model and Van der Waals and Platteeuw model. The paper also discussed pair potential of non-spherical molecules, including the multicentre (site-site) potential; Gaussian overlap potential; Lennard-Jones potential; and Kihara generalized pair potential. It was concluded that fraction of occupied cavities is a function of pair potentials between hard core and empty hydrate lattice. These pair potentials could be calculated from some model as Kihara cell potential, Gaussian potential, Lennard-Jones potential and multicentre pair potential. 49 refs., 3 figs.

Spatial updating grand canonical Monte Carlo algorithms for fluid simulation: generalization to continuous potentials and parallel implementation.

Science.gov (United States)

O'Keeffe, C J; Ren, Ruichao; Orkoulas, G

2007-11-21

Spatial updating grand canonical Monte Carlo algorithms are generalizations of random and sequential updating algorithms for lattice systems to continuum fluid models. The elementary steps, insertions or removals, are constructed by generating points in space either at random (random updating) or in a prescribed order (sequential updating). These algorithms have previously been developed only for systems of impenetrable spheres for which no particle overlap occurs. In this work, spatial updating grand canonical algorithms are generalized to continuous, soft-core potentials to account for overlapping configurations. Results on two- and three-dimensional Lennard-Jones fluids indicate that spatial updating grand canonical algorithms, both random and sequential, converge faster than standard grand canonical algorithms. Spatial algorithms based on sequential updating not only exhibit the fastest convergence but also are ideal for parallel implementation due to the absence of strict detailed balance and the nature of the updating that minimizes interprocessor communication. Parallel simulation results for three-dimensional Lennard-Jones fluids show a substantial reduction of simulation time for systems of moderate and large size. The efficiency improvement by parallel processing through domain decomposition is always in addition to the efficiency improvement by sequential updating.

Instantaneous, parameter-free methods to define a solute’s hydration shell

International Nuclear Information System (INIS)

Chatterjee, Anupam; Higham, Jonathan; Henchman, Richard H.

2015-01-01

A range of methods are presented to calculate a solute’s hydration shell from computer simulations of dilute solutions of monatomic ions and noble gas atoms. The methods are designed to be parameter-free and instantaneous so as to make them more general, accurate, and consequently applicable to disordered systems. One method is a modified nearest-neighbor method, another considers solute-water Lennard-Jones overlap followed by hydrogen-bond rearrangement, while three methods compare various combinations of water-solute and water-water forces. The methods are tested on a series of monatomic ions and solutes and compared with the values from cutoffs in the radial distribution function, the nearest-neighbor distribution functions, and the strongest-acceptor hydrogen bond definition for anions. The Lennard-Jones overlap method and one of the force-comparison methods are found to give a hydration shell for cations which is in reasonable agreement with that using a cutoff in the radial distribution function. Further modifications would be required, though, to make them capture the neighboring water molecules of noble-gas solutes if these weakly interacting molecules are considered to constitute the hydration shell

Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

DEFF Research Database (Denmark)

Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

2010-01-01

e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air......Silicon dioxides-water systems are abundant in nature and play fundamental roles in a diversity of novel science and engineering applications. Although extensive research has been devoted to study the nature of the interaction between silica and water a complete understanding of the system has...... perform extensive simulations of the water- air equilibrium and calibrate the water-air interaction to match the experimental solubility of N2 and O2 in water. For the silica-water system we calibrate the water-silica interaction to match the experimental contact angle of 27º. We subsequently study...

75 FR 20802 - Safety Zone; New York Air Show at Jones Beach State Park, Atlantic Ocean off of Jones Beach...

Science.gov (United States)

2010-04-21

... meeting would be beneficial. If we determine that one would aid this rulemaking, we will hold one at a... to the shows, as well as providing additional time should they run over the scheduled period. The... running east along the shoreline of Jones Beach State Park to approximate position 40[deg]35'49'' N, 073...

Dynamics of metal nanodroplets; Dynamik metallischer Nanotroepfchen

Energy Technology Data Exchange (ETDEWEB)

Habenicht, Anja

2007-11-12

In this work flat metal nanostructures on inert substrates like glass, silicon or graphite have been illuminated by single intensive laser pulses with fluences above the melting threshold. The liquid structures produced in this way are far from their equilibrium shape and a dewetting process starts. On a timescale of a few nanoseconds, the liquid but still flat nanostructure transforms toward a sphere. During this deformation the center of mass moves upward, which can lead to detachment of droplets from the surface due to inertia. The velocity of the detaching nanodroplets is measured with a light barrier technique. The experiment shows that the velocity of the detached droplet is constant over a large range of laser energy densities. This supports the model of a dewetting driven process: The droplet gains surface energy by transforming toward a sphere which is then converted into kinetic energy. Loss mechanisms like excitation of droplet oscillations and dissipation due to viscous friction are discussed. With this model the escape velocity was predicted for nanostructures of different materials and forms, hence other material parameters like surface tension or density and has been confirmed experimentally. The droplets are landed on another surface. Two scenarios are found: There are spheres with a similar shape as the droplet or heavily deformed structures. These structures of splashing and rebounding are identical to the structures which can be observed in the macroscopic impact of liquids. The two scenarios can be explained by different temperatures of the droplets when reaching the substrate. (orig.)

Proton transfer dynamics in a polar nanodroplet: ESIPT of 4'-n,n-dimethylamino-3-hydroxyflavone in AOT/alkane/water reverse micelles

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Deborin [Department of Chemistry, University College of Science & Technology, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009 (India); Batuta, Shaikh; Begum, Naznin Ara [Bio-Organic Chemistry Lab, Department of Chemistry, Visva-Bharati University, Santiniketan 731 235 (India); Mandal, Debabrata, E-mail: dmandal.chemistry@gmail.com [Department of Chemistry, University College of Science & Technology, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009 (India)

2017-04-15

The excited state intramolecular proton transfer (ESIPT) of the well-known fluorophore 4'-N,N-Dimethylamino-3-hydroxyflavone (DMA3HF) was studied in AOT/n-heptane/water reverse micelle solutions. For DMA3HF molecules located inside the AOT encapsulated polar nanodroplets, ESIPT from excited enol (E*) to tautomer (T*) forms was markedly inhibited, yielding time-constants of ≥100 ps, and followed the same trend as solvent relaxation when the ratio W= [H{sub 2}O]/[AOT] was varied. At W=0, the DMA3HF molecules were attached to the ionic AOT headgroups via strong intermolecular H-bonding, which hindered ESIPT. Addition of water changes the situation radically: water molecules form stronger H-bonds with AOT headgroups, displacing the DMA3HF, which are instead engaged in intermolecular H-bonded complexes of the type [DMA3HF···water]. ESIPT of these complex-bound fluorophores involves substantial rearrangement of H-bonding, and is coupled to solvation dynamics. With increasing W-value, solvation becomes faster, and so does ESIPT, reducing the yield of E* species. At the same time, the local environment within the nanodroplets become more more polar with gradual accumulation of water, which causes a monotonic red-shift of the E* emission peak.

Molecular dynamics simulation of a chemical reaction

International Nuclear Information System (INIS)

Gorecki, J.; Gryko, J.

1988-06-01

Molecular dynamics is used to study the chemical reaction A+A→B+B. It is shown that the reaction rate constant follows the Arrhenius law both for Lennard-Jones and hard sphere interaction potentials between substrate particles. A. For the denser systems the reaction rate is proportional to the value of the radial distribution function at the contact point of two hard spheres. 10 refs, 4 figs

Are there Long-Run Diversification Gains from the Dow Jones Islamic Finance Index?

OpenAIRE

Mehmet Balcilar; Charl Jooste; Shawkat Hammoudeh; Rangan Gupta; Vassilios Babalos

2014-01-01

We compare nonlinear cointegration tests with the standard cointegration tests in studying the relationship of the Dow Jones Islamic finance index with three other conventional equity market indices. Our results show that there is a long-run nonlinear cointegrating relationship between the Dow Jones Islamic stock market index and other conventional stock market indices. Our findings rely on a battery of standard tests as well as on the Bierens and Martins (2010) test that investigates time-va...

Volatility Transmission between Dow Jones Stock Index and Emerging Bond Index

Directory of Open Access Journals (Sweden)

Amir Saadaoui

2016-04-01

Full Text Available In this paper, we use a bivariate GARCH model to estimate simultaneously of the mean and the conditional variance between the Dow Jones stock index and some emerging bond indices. We used the DCC-GARCH model to graphically demonstrate the peaks of the volatility transmission. We examined this transmission using daily returns between July, 30, 2009 and January, 18, 2011 extracted from Datastream. Our results demonstrate that there is a significant transmission of shocks and volatility between the Dow Jones stock index and bond indices of the emerging countries. The results also confirm the idea that the crisis was transmitted from the United States to the emerging countries due to foreign investment made in these countries.

Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

Science.gov (United States)

McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

2017-09-20

The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

Highlight: Dr David Butler-Jones on fighting pandemics | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

2016-04-15

Apr 15, 2016 ... In the context of developing countries, Butler-Jones drew attention to the importance of public healthcare teams of doctors and paramedics, data, and accreditation standards in identifying appropriate interventions. There is a need to explore the public-private nexus, traditional medicines, and public health ...

A note on Valeriana jatamansi Jones (Caprifoliaceae s.l.)

NARCIS (Netherlands)

Mabberley, D.J.; Noltie, H.J.

2014-01-01

The tangled arguments around the names of jatamansi drug plants are examined and the correct synonymies and typifications for Nardostachys jatamansi (D.Don) DC. and V. jatamansi Jones (both Caprifoliaceae s.l.) are provided. The conservation status of the former, and the need for further work on the

Microcanonical Monte Carlo approach for computing melting curves by atomistic simulations

OpenAIRE

Davis, Sergio; Gutiérrez, Gonzalo

2017-01-01

We report microcanonical Monte Carlo simulations of melting and superheating of a generic, Lennard-Jones system starting from the crystalline phase. The isochoric curve, the melting temperature $T_m$ and the critical superheating temperature $T_{LS}$ obtained are in close agreement (well within the microcanonical temperature fluctuations) with standard molecular dynamics one-phase and two-phase methods. These results validate the use of microcanonical Monte Carlo to compute melting points, a ...

Effective diameters and corresponding states of fluids

Science.gov (United States)

Del Río, Fernando

Effective hard-sphere diameters of fluids with purely repulsive interactions are derived from a generalized corresponding-states principle of Leland, Rowlinson and coworkers. Various alternative definitions are discussed and related. Virial expansions of the effective diameters and their corresponding volumes are obtained and compared with results of perturbation theory. Applications are made to inverse-power potentials, the repulsive part of the Lennard-Jones potential and hard spherocylinders and dumbells.

Fast-switching optically isotropic liquid crystal nano-droplets with improved depolarization and Kerr effect by doping high k nanoparticles.

Science.gov (United States)

Kim, Byeonggon; Kim, Hyun Gyu; Shim, Gyu-Yeop; Park, Ji-Sub; Joo, Kyung-Il; Lee, Dong-Jin; Lee, Joun-Ho; Baek, Ji-Ho; Kim, Byeong Koo; Choi, Yoonseuk; Kim, Hak-Rin

2018-01-10

We proposed and analyzed an optically isotropic nano-droplet liquid crystal (LC) doped with high k nanoparticles (NPs), exhibiting enhanced Kerr effects, which could be operated with reduced driving voltages. For enhancing the contrast ratio together with the light efficiencies, the LC droplet sizes were adjusted to be shorter than the wavelength of visible light to reduce depolarization effects by optical scattering of the LC droplets. Based on the optical analysis of the depolarization effects, the influence of the relationship between the LC droplet size and the NP doping ratio on the Kerr effect change was investigated.

Marine geophysics. By E.J.W. Jones

Digital Repository Service at National Institute of Oceanography (India)

Rao, D.G.

.Earth-Science Reviews 52 2001 381–384 www.elsevier.comrlocaterearscirev Book reviews Marine Geophysics E.J.W. Jones, University College, London, UK, Wiley, Chichester, West Sussex PO19IUD, England, 1999, 466 pp. As a practicing marine geophysicist working... principles, theory, state-of-the-art instruments, latest techniques in data acquisition, processing and interpretation. The book contains 16 chapters, in which the author has done commendable job in presenting the best examples of case studies in critical...

Formation times of RbHe exciplexes on the surface of superfluid versus normal fluid helium nanodroplets

International Nuclear Information System (INIS)

Droppelmann, G.; Buenermann, O.; Stienkemeier, F.; Schulz, C.P.

2004-01-01

Nanodroplets of either superfluid He 4 or normal fluid He 3 are doped with Rb atoms that are bound to the surface of the droplets. The formation of RbHe exciplexes upon 5P 3/2 excitation is monitored in real time by femtosecond pump-probe techniques. We find formation times of 8.5 and 11.6 ps for Rb He 4 and Rb He 3 , respectively. A comparison to calculations based on a tunneling model introduced for these systems by Reho et al. [J. Chem. Phys. 113, 9694 (2000)] shows that the proposed mechanism cannot account for our findings. Apparently, a different relaxation dynamics of the superfluid opposed to the normal fluid surface is responsible for the observed formation times

Final Technical Report: Vibrational Spectroscopy of Transient Combustion Intermediates Trapped in Helium Nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Douberly, Gary Elliott [Univ. of Georgia, Athens, GA (United States)

2017-11-16

The objective of our experimental research program is to isolate and stabilize transient intermediates and products of prototype combustion reactions. This will be accomplished by Helium Nanodroplet Isolation, a novel technique where liquid helium droplets freeze out high energy metastable configurations of a reacting system, permitting infrared spectroscopic characterizations of products and intermediates that result from hydrocarbon radical reactions with molecular oxygen and other small molecules relevant to combustion environments. The low temperature (0.4 K) and rapid cooling associated with He droplets provides a perfectly suited medium to isolate and probe a broad range of molecular radical and carbene systems important to combustion chemistry. The sequential addition of molecular species to He droplets often leads to the stabilization of high-energy, metastable cluster configurations that represent regions of the potential energy surface far from the global minimum. Single and double resonance IR laser spectroscopy techniques, along with Stark and Zeeman capabilities, are being used to probe the structural and dynamical properties of these systems.

Käsitsi tegemise võlu / David Jones ; intervjueerinud Kai Lobjakas

Index Scriptorium Estoniae

Jones, David, 1953-

2010-01-01

10. Kohila keraamikasümpoosionil osalenud briti keraamik ja teoreetik David Jones endast, rakutehnikast, huvist põletamisega seonduvate teemade vastu, Kohila sümpoosioni raames tehtust, keraamika õpetamisest Inglismaal, käsitöö ja keraamika positsioonist praegu ja tulevikus jm.

Highlight: Dr David Butler-Jones on fighting pandemics | CRDI ...

International Development Research Centre (IDRC) Digital Library (Canada)

15 avr. 2016 ... Dr David Butler-Jones, professor in the Faculty of Medicine at the University of Manitoba and former Chief Medical Health Officer of Canada, delivered a lecture on lessons learned from the 2009 flu pandemic in Canada. He also commented on India's draft National Health Policy 2015 at the India ...

Diagnostic reference range of κ/λ free light chain ratio to screen for Bence Jones proteinuria is not significantly influenced by GFR.

Science.gov (United States)

Schmidt-Hieltjes, Yvonne; Elshof, Clemens; Roovers, Lian; Ruinemans-Koerts, Janneke

2016-05-01

The aim of our study was to analyse whether the κ/λ free light chain ratio reference range for screening for Bence Jones proteinuria should be dependent on the estimated glomerular filtration rate (eGFR). The serum κ/λ free light chain ratio, eGFR, serum M-protein and Bence Jones protein were measured in 544 patients for whom Bence Jones protein analysis was ordered. In the population of patients without Bence Jones proteinuria or a M-protein (n = 402), there is no gradual increase in κ/λ free light chain ratio with diminishing eGFR. The κ/λ free light chain ratio in this group was 0.56-1.86 (95% interval). With this diagnostic reference range of the κ/λ ratio, 105 of the 110 patients with Bence Jones protein could be identified correctly. Only five patients with Bence Jones proteinuria (free light chain ratio was measured without the presence of Bence Jones proteinuria. A κ/λ free light chain ratio in serum can be used safely and efficiently to select urine samples which should be analysed for Bence Jones proteinuria with an electrophoresis/immunofixation technique. Using this diagnostic reference range, the number of urine samples which should be analysed by electrophoresis/immunofixation could be reduced by 74%. The diagnostic reference interval can be determined best in a group of patients for whom Bence Jones analysis is indicated. For calculation of this reference range, the eGFR value does not need to be taken into account. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Stimulated phase-shift acoustic nanodroplets enhance vancomycin efficacy against methicillin-resistant Staphylococcus aureus biofilms

Directory of Open Access Journals (Sweden)

Guo H

2017-06-01

Full Text Available Hao Guo,1 Ziming Wang,1 Quanyin Du,1 Pan Li,2 Zhigang Wang,2 Aimin Wang1 1Department of Orthopedics, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China; 2Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging, Second Affiliated Hospital of Chongqing Medical University, Chongqing, China Purpose: Bacterial biofilms on the surface of prostheses are becoming a rising concern in managing prosthetic joint infections. The inherent resistant features of biofilms render traditional antimicrobial therapy unproductive and revision surgery outcomes uncertain. This situation has prompted the exploration of novel antimicrobial strategies. The synergy of ultrasound microbubbles and vancomycin has been proposed as an efficient alternative for biofilm eradication. The purpose of this study was to evaluate the anti-biofilm effect of stimulated phase-shift acoustic nanodroplets (NDs combined with vancomycin.Materials and methods: We fabricated lipid phase-shift NDs with a core of liquid perfluoropentane. A new phase change mode for NDs incorporating an initial unfocused low-intensity pulsed ultrasound for 5 minutes and a subsequent incubation at 37°C into a 24-hour duration was developed. Methicillin-resistant Staphylococcus aureus (MRSA biofilms were incubated with vancomycin and NDs under the hybrid stimulation. Biofilm morphology following treatment was determined using confocal laser scanning microscopy and scanning electron microscopy. Resazurin assay was used to quantify bactericidal efficacy against MRSA biofilm bacteria.Results: NDs treated sequentially with ultrasound and heating at 37°C achieved gradual and substantial ND vaporization and cavitation in a successive process. NDs after stimulation were capable of generating stronger destruction on biofilm structure which was best characterized by residual circular arc margins and more dead bacteria. Furthermore, NDs

Cracks and nanodroplets produced on tungsten surface samples by dense plasma jets

Science.gov (United States)

Ticoş, C. M.; Galaţanu, M.; Galaţanu, A.; Luculescu, C.; Scurtu, A.; Udrea, N.; Ticoş, D.; Dumitru, M.

2018-03-01

Small samples of 12.5 mm in diameter made from pure tungsten were exposed to a dense plasma jet produced by a coaxial plasma gun operated at 2 kJ. The surface of the samples was analyzed using a scanning electron microscope (SEM) before and after applying consecutive plasma shots. Cracks and craters were produced in the surface due to surface tensions during plasma heating. Nanodroplets and micron size droplets could be observed on the samples surface. An energy-dispersive spectroscopy (EDS) analysis revealed that the composition of these droplets coincided with that of the gun electrode material. Four types of samples were prepared by spark plasma sintering from powders with the average particle size ranging from 70 nanometers up to 80 μm. The plasma power load to the sample surface was estimated to be ≈4.7 MJ m-2 s-1/2 per shot. The electron temperature and density in the plasma jet had peak values 17 eV and 1.6 × 1022 m-3, respectively.

Cephalometric effects of the Jones Jig appliance followed by fixed appliances in Class II malocclusion treatment.

Science.gov (United States)

Patel, Mayara Paim; Henriques, José Fernando Castanha; Freitas, Karina Maria Salvatore; Grec, Roberto Henrique da Costa

2014-01-01

The aim of this study was to cephalometrically assess the skeletal and dentoalveolar effects of Class II malocclusion treatment performed with the Jones Jig appliance followed by fixed appliances. The sample comprised 25 patients with Class II malocclusion treated with the Jones Jig appliance followed by fixed appliances, at a mean initial age of 12.90 years old. The mean time of the entire orthodontic treatment was 3.89 years. The distalization phase lasted for 0.85 years, after which the fixed appliance was used for 3.04 years. Cephalograms were used at initial (T1), post-distalization (T2) and final phases of treatment (T3). For intragroup comparison of the three phases evaluated, dependent ANOVA and Tukey tests were used. Jones Jig appliance did not interfere in the maxillary and mandibular component and did not change maxillomandibular relationship. Jones Jig appliance promoted distalization of first molars with anchorage loss, mesialization and significant extrusion of first and second premolars, as well as a significant increase in anterior face height at the end of treatment. The majority of adverse effects that occur during intraoral distalization are subsequently corrected during corrective mechanics. Buccal inclination and protrusion of mandibular incisors were identified. By the end of treatment, correction of overjet and overbite was observed. Jones Jig appliance promoted distalization of first molars with anchorage loss represented by significant mesial movement and extrusion of first and second premolars, in addition to a significant increase in anterior face height.

Shelley Jones — Aider les jeunes Ougandaises à poursuivre leurs ...

International Development Research Centre (IDRC) Digital Library (Canada)

18 nov. 2014 ... ... d'entre elles abandonnent l'école à cause de leur cycle menstruel. ... Shelley Jones with her Masters of Education students debating gender issues ... limité ou à la discrimination sexospécifique en matière d'éducation.

Quantum complex rotation and uniform semiclassical calculations of complex energy eigenvalues

International Nuclear Information System (INIS)

Connor, J.N.L.; Smith, A.D.

1983-01-01

Quantum and semiclassical calculations of complex energy eigenvalues have been carried out for an exponential potential of the form V 0 r 2 exp(-r) and Lennard-Jones (12,6) potential. A straightforward method, based on the complex coordinate rotation technique, is described for the quantum calculation of complex eigenenergies. For singular potentials, the method involves an inward and outward integration of the radial Schroedinger equation, followed by matching of the logarithmic derivatives of the wave functions at an intermediate point. For regular potentials, the method is simpler, as only an inward integration is required. Attention is drawn to the World War II researches of Hartree and co-workers who anticipated later quantum mechanical work on the complex rotation method. Complex eigenenergies are also calculated from a uniform semiclassical three turning point quantization formula, which allows for the proximity of the outer pair of complex turning points. Limiting cases of this formula, which are valid for very narrow or very broad widths, are also used in the calculations. We obtain good agreement between the semiclassical and quantum results. For the Lennard-Jones (12,6) potential, we compare resonance energies and widths from the complex energy definition of a resonance with those obtained from the time delay definition

Termodinâmica estatística de líquidos com o método de Monte Carlo. II. O líquido clorofórmio

Directory of Open Access Journals (Sweden)

Barlette Vania Elisabeth

1999-01-01

Full Text Available Thermodynamic properties and radial distribution functions for liquid chloroform were calculated using the Monte Carlo method implemented with Metropolis algorithm in the NpT ensemble at 298 K and 1 atm. A five site model was developed to represent the chloroform molecules. A force field composed by Lennard-Jones and Coulomb potential functions was used to calculate the intermolecular energy. The partial charges needed to represent the Coulombic interactions were obtained from quantum chemical ab initio calculations. The Lennard-Jones parameters were adjusted to reproduce experimental values for density and enthalpy of vaporization for pure liquid. All thermodynamic results are in excelent agreement with experimental data. The correlation functions calculated are in good accordance with theoretical results avaliable in the literature. The free energy for solvating one chloroform molecule into its own liquid at 298 K and 1 atm was computed as an additional test of the potential model. The result obtained compares well with the experimental value. The medium effects on cis/trans convertion of a hypotetical solute in water TIP4P and chloroform solvents were also accomplished. The results obtained from this investigation are in agreement with estimates of the continuous theory of solvation.

Evolution of short range order in Ar: Liquid to glass and solid transitions-A computational study

Science.gov (United States)

Shor, Stanislav; Yahel, Eyal; Makov, Guy

2018-04-01

The evolution of the short range order (SRO) as a function of temperature in a Lennard-Jones model liquid with Ar parameters was determined and juxtaposed with thermodynamic and kinetic properties obtained as the liquid was cooled (heated) and transformed between crystalline solid or glassy states and an undercooled liquid. The Lennard-Jones system was studied by non-equilibrium molecular dynamics simulations of large supercells (approximately 20000 atoms) rapidly cooled or heated at selected quenching rates and at constant pressure. The liquid to solid transition was identified by discontinuities in the atomic volume and molar enthalpy; the glass transition temperature range was identified from the temperature dependence of the self-diffusion. The SRO was studied within the quasi-crystalline model (QCM) framework and compared with the Steinhardt bond order parameters. Within the QCM it was found that the SRO evolves from a bcc-like order in the liquid through a bct-like short range order (c/a=1.2) in the supercooled liquid which persists into the glass and finally to a fcc-like ordering in the crystalline solid. The variation of the SRO that results from the QCM compares well with that obtained with Steinhardt's bond order parameters. The hypothesis of icosahedral order in liquids and glasses is not supported by our results.

An adaptive immune optimization algorithm with dynamic lattice searching operation for fast optimization of atomic clusters

International Nuclear Information System (INIS)

Wu, Xia; Wu, Genhua

2014-01-01

Highlights: • A high efficient method for optimization of atomic clusters is developed. • Its performance is studied by optimizing Lennard-Jones clusters and Ag clusters. • The method is proved to be quite efficient. • A new Ag 61 cluster with stacking-fault face-centered cubic motif is found. - Abstract: Geometrical optimization of atomic clusters is performed by a development of adaptive immune optimization algorithm (AIOA) with dynamic lattice searching (DLS) operation (AIOA-DLS method). By a cycle of construction and searching of the dynamic lattice (DL), DLS algorithm rapidly makes the clusters more regular and greatly reduces the potential energy. DLS can thus be used as an operation acting on the new individuals after mutation operation in AIOA to improve the performance of the AIOA. The AIOA-DLS method combines the merit of evolutionary algorithm and idea of dynamic lattice. The performance of the proposed method is investigated in the optimization of Lennard-Jones clusters within 250 atoms and silver clusters described by many-body Gupta potential within 150 atoms. Results reported in the literature are reproduced, and the motif of Ag 61 cluster is found to be stacking-fault face-centered cubic, whose energy is lower than that of previously obtained icosahedron

The role of binary and many-centre molecular interactions in spin crossover in the solid state. Part II. Non-ideality parameters defined via binary molecular potentials

International Nuclear Information System (INIS)

Koudriavtsev, A.B.; Linert, W.

2005-01-01

Parameters of the formalism [1-6] describing spin crossover in the solid state have been defined via molecular potentials in model systems of neutral and ionic complexes. In the first instance Lennard-Jones and electric dipole-dipole potentials have been used whereas in ionic systems Lennard-Jones and electric point-charge potentials have been used. Electric dipole-dipole interaction of neutral complexes brings about a positive excess energy controlled by the difference of electric dipole moments of HS and LS molecules. Differences of the order of Δμ = 1-2D cause an abrupt spin crossover in systems with T 1/2 = 100-150K. Magnetic coupling contributes both to the excess energy and excess entropy, however the overall effect is equivalent to a modest positive excess energy. Ionic systems in the absence of specific interactions are characterized by very small excess energies corresponding to practically linear van't Hoff plots. Detectable positive and negative excess energies in these systems may arise from interactions of ligands belonging to neighbouring complexes. The HOMO-LUMO overlap in HS-LS pairs can bring about a nontrivial variation of the shape of transition curves. Examples of regression analysis of experimental transition curves in terms of molecular potentials are given. (author)

Thermophysical properties of H2O - Ar plasmas at temperatures 400 - 50000K and pressure 0.1 MPa

Czech Academy of Sciences Publication Activity Database

Křenek, Petr

2008-01-01

Roč. 28, č. 1 (2008), s. 107-122 ISSN 0272-4324 Institutional research plan: CEZ:AV0Z20430508 Keywords : thermophysical properties of thermal plasmas * ionized gas mixtures * plasma composition * thermodynamic properties * Lennard – Jones interaction potential * screened Coulomb potential * effective collision cross sections * collision integrals * Chapman-Enskog method in the 4th approximation * viscosity * electrical conductivity * thermal conductivity Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.167, year: 2008

Effects of Surface Structure and of Embedded-Atom Pair Functionals on Adatom Diffusion on FCC Metallic Surfaces

Science.gov (United States)

1992-11-01

is more compact relative to that in the [001] direction. Detailed MD studies (De Lorenzi, Jacucci, and Pontikis 1982), using Lennard-Jones...Jacucci, and Pontikis 1982) have shown that the predominance of the adatom exchange mechanism results in nearly isotropic diffusion which is further...G., G. Jacucci, and V. Pontikis . Surface Science, vol. 116, p. 391, 1982. Doll, J. D., and A. F. Voter. Ann. Rev. Phys. Chem., vol. 38, p. 413, 1987

Molecular dynamics simulations of the penetration lengths: application within the fluctuation theory for diffusion coefficients

DEFF Research Database (Denmark)

Galliero, Guillaume; Medvedev, Oleg; Shapiro, Alexander

2005-01-01

A 322 (2004) 151). In the current study, a fast molecular dynamics scheme has been developed to determine the values of the penetration lengths in Lennard-Jones binary systems. Results deduced from computations provide a new insight into the concept of penetration lengths. It is shown for four different...... fluctuation theory and molecular dynamics scheme exhibit consistent trends and average deviations from experimental data around 10-20%. (c) 2004 Elsevier B.V. All rights reserved....

Algumas considerações sobre o termo afânise a partir de E. Jones e J. Lacan

Directory of Open Access Journals (Sweden)

Daniela Scheinkman Chatelard

2001-12-01

Full Text Available Em sua primeira parte, este artigo propõe-se a retomar e a desenvolver o termo afânise, tal como foi forjado por Ernest Jones. Na segunda parte, trata-se de acrescentar a importância dada por Jacques Lacan a este termo: do registro do puro desaparecimento do desejo, em sua relação com a castração, como foi sustentado por E. Jones, passamos ao registro do desaparecimento do sujeito, enquanto sujeito dividido e desejante. Para isso, recorremos ao exemplo do personagem literário, Hamlet, da tragédia de Shakespeare.Some considerations about the aphanisis term from E. Jones and J. Lacan. The aim of the article in its first part is to retake and to develop the term aphanisis, such as forged by Ernest Jones. In its second part, the purpose is to add to this term the importance given by Jacques Lacan : from the register of the pure disappearing of desire in its relation to castration, as supported by Jones, we will pass on to the register of the disappearing of the subject, while in the form of a divided and desiring subject. Therefore, we will use the example of the literary character, Hamlet, taken from Shakespeare's tragedy.

The Kauffman bracket and the Jones polynomial in quantum gravity

International Nuclear Information System (INIS)

Griego, J.

1996-01-01

In the loop representation the quantum states of gravity are given by knot invariants. From general arguments concerning the loop transform of the exponential of the Chern-Simons form, a certain expansion of the Kauffman bracket knot polynomial can be formally viewed as a solution of the Hamiltonian constraint with a cosmological constant in the loop representation. The Kauffman bracket is closely related to the Jones polynomial. In this paper the operation of the Hamiltonian on the power expansions of the Kauffman bracket and Jones polynomials is analyzed. It is explicitly shown that the Kauffman bracket is a formal solution of the Hamiltonian constraint to third order in the cosmological constant. We make use of the extended loop representation of quantum gravity where the analytic calculation can be thoroughly accomplished. Some peculiarities of the extended loop calculus are considered and the significance of the results to the case of the conventional loop representation is discussed. (orig.)

"Armastuse retsepti" tippkokk Zeta Jones ei oska muna keeta / Triin Tael

Index Scriptorium Estoniae

Tael, Triin

2007-01-01

Scott Hicksi romantiline komöödiafilm "Armastuse retsept" ("No Reservations"), mille peaosas Walesist pärit näitlejanna Catherine Zeta Jones. Näitlejanna muljeid oma rolliks ettevalmistustest, mille hulka käis ka praktika pärisrestoranis

The impact of modifying the Jones Act on US coastal shipping.

Science.gov (United States)

2014-06-01

The study assesses exempt coastal shipping defined as exempted from the US-built stipulation of the : Jones Act, operating with functional crews and exempted from Harbor Maintenance Tax (HMT). The : study focuses on two research questions: (a) the im...

The homological content of the Jones representations at $q = -1$

DEFF Research Database (Denmark)

Egsgaard, Jens Kristian; Fuglede Jørgensen, Søren

We generalize a discovery of Kasahara and show that the Jones representations of braid groups, when evaluated at $q = -1$, are related to the action on homology of a branched double cover of the underlying punctured disk. As an application, we prove for a large family of pseudo-Anosov mapping...

C. Rick Jones Is IRPA Keynote Lecturer on Stakeholder Engagement

International Nuclear Information System (INIS)

Strom, Daniel J.

2008-01-01

At the recent IRPA 12 Conference in Buenos Aires, Argentina, C. Rick Jones gave the keynote lecture 'Stakeholder Engagement in Practice - Now Is the Time to Act' This was one of the very best talks at the conference, covering IRPA's draft 'Guiding Principles for Radiation Protection Professionals on Stakeholder Engagement'

Lithium atoms on helium nanodroplets: Rydberg series and ionization dynamics

Science.gov (United States)

Lackner, Florian; Krois, Günter; Ernst, Wolfgang E.

2017-11-01

The electronic excitation spectrum of lithium atoms residing on the surface of helium nanodroplets is presented and analyzed employing a Rydberg-Ritz approach. Utilizing resonant two-photon ionization spectroscopy, two different Rydberg series have been identified: one assigned to the nS(Σ) series and the other with predominantly nP(Π) character. For high Rydberg states, which have been resolved up to n = 13, the surrounding helium effectively screens the valence electron from the Li ion core, as indicated by the apparent red-shift of Li transitions and lowered quantum defects on the droplet with respect to their free atom counterparts. For low n states, the screening effect is weakened and the prevailing repulsive interaction gives rise to strongly broadened and blue-shifted transitions. The red-shifts originate from the polarization of nearby He atoms by the positive Li ion core. As a consequence of this effect, the ionization threshold is lowered by 116 ± 10 cm-1 for Li on helium droplets with a radius of about 40 Å. Upon single-photon ionization, heavy complexes corresponding to Li ions attached to intact helium droplets are detected. We conclude that ionization close to the on-droplet ionization threshold triggers a dynamic process in which the Li ion core undergoes a transition from a surface site into the droplet.

The BQP-hardness of approximating the Jones polynomial

International Nuclear Information System (INIS)

Aharonov, Dorit; Arad, Itai

2011-01-01

A celebrated important result due to Freedman et al (2002 Commun. Math. Phys. 227 605-22) states that providing additive approximations of the Jones polynomial at the kth root of unity, for constant k=5 and k≥7, is BQP-hard. Together with the algorithmic results of Aharonov et al (2005) and Freedman et al (2002 Commun. Math. Phys. 227 587-603), this gives perhaps the most natural BQP-complete problem known today and motivates further study of the topic. In this paper, we focus on the universality proof; we extend the result of Freedman et al (2002) to ks that grow polynomially with the number of strands and crossings in the link, thus extending the BQP-hardness of Jones polynomial approximations to all values to which the AJL algorithm applies (Aharonov et al 2005), proving that for all those values, the problems are BQP-complete. As a side benefit, we derive a fairly elementary proof of the Freedman et al density result, without referring to advanced results from Lie algebra representation theory, making this important result accessible to a wider audience in the computer science research community. We make use of two general lemmas we prove, the bridge lemma and the decoupling lemma, which provide tools for establishing the density of subgroups in SU(n). Those tools seem to be of independent interest in more general contexts of proving the quantum universality. Our result also implies a completely classical statement, that the multiplicative approximations of the Jones polynomial, at exactly the same values, are P-hard, via a recent result due to Kuperberg (2009 arXiv:0908.0512). Since the first publication of those results in their preliminary form (Aharonov and Arad 2006 arXiv:quant-ph/0605181), the methods we present here have been used in several other contexts (Aharonov and Arad 2007 arXiv:quant-ph/0702008; Peter and Stephen 2008 Quantum Inf. Comput. 8 681). The present paper is an improved and extended version of the results presented by Aharonov and Arad

The BQP-hardness of approximating the Jones polynomial

Energy Technology Data Exchange (ETDEWEB)

Aharonov, Dorit; Arad, Itai, E-mail: itaia@cs.huji.ac.il [Department of Computer Science and Engineering, Hebrew University, Jerusalem (Israel)

2011-03-15

A celebrated important result due to Freedman et al (2002 Commun. Math. Phys. 227 605-22) states that providing additive approximations of the Jones polynomial at the kth root of unity, for constant k=5 and k{>=}7, is BQP-hard. Together with the algorithmic results of Aharonov et al (2005) and Freedman et al (2002 Commun. Math. Phys. 227 587-603), this gives perhaps the most natural BQP-complete problem known today and motivates further study of the topic. In this paper, we focus on the universality proof; we extend the result of Freedman et al (2002) to ks that grow polynomially with the number of strands and crossings in the link, thus extending the BQP-hardness of Jones polynomial approximations to all values to which the AJL algorithm applies (Aharonov et al 2005), proving that for all those values, the problems are BQP-complete. As a side benefit, we derive a fairly elementary proof of the Freedman et al density result, without referring to advanced results from Lie algebra representation theory, making this important result accessible to a wider audience in the computer science research community. We make use of two general lemmas we prove, the bridge lemma and the decoupling lemma, which provide tools for establishing the density of subgroups in SU(n). Those tools seem to be of independent interest in more general contexts of proving the quantum universality. Our result also implies a completely classical statement, that the multiplicative approximations of the Jones polynomial, at exactly the same values, are P-hard, via a recent result due to Kuperberg (2009 arXiv:0908.0512). Since the first publication of those results in their preliminary form (Aharonov and Arad 2006 arXiv:quant-ph/0605181), the methods we present here have been used in several other contexts (Aharonov and Arad 2007 arXiv:quant-ph/0702008; Peter and Stephen 2008 Quantum Inf. Comput. 8 681). The present paper is an improved and extended version of the results presented by Aharonov and

Revised Jones Criteria For The Diagnosis of Acute Rheumatic Fever (AHA 2015 - An Indian Perspective

Directory of Open Access Journals (Sweden)

KV Sahasranam

2015-07-01

Full Text Available Acute Rheumatic Fever (ARF is still a major problem in some developing and low middle income countries though the incidence and prevalence has remarkably reduced in North America and Europe. Ever since T. Duckett Jones in 1944 proposed the Jones criteria, it was modified and later revised by the American Heart Association (AHA in 1992. This was reconfirmed in and AHA sponsored Work shop in 2002. No modification or change was suggested after the introduction of Doppler Echocardiography (DE for the diagnosis of clinical and "subclinical carditis". When a clinical diagnosis by the clinician fails to show evidence of carditis, DE may pick up cases of "subclinical carditis". Moreover, previous recommendations did not include the Classification of Recommendations (Class I, II a, II b, and III and Levels of Evidence (Levels A, B and C. Recently, however, a scientific statement from the American Heart Association (AHA has published an update to the Jones criteria including the use of DE in the diagnosis of ARF.

Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

Science.gov (United States)

Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

2016-03-01

Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions.

Wetting and evaporation of salt-water nanodroplets: A molecular dynamics investigation.

Science.gov (United States)

Zhang, Jun; Borg, Matthew K; Sefiane, Khellil; Reese, Jason M

2015-11-01

We employ molecular dynamics simulations to study the wetting and evaporation of salt-water nanodroplets on platinum surfaces. Our results show that the contact angle of the droplets increases with the salt concentration. To verify this, a second simulation system of a thin salt-water film on a platinum surface is used to calculate the various surface tensions. We find that both the solid-liquid and liquid-vapor surface tensions increase with salt concentration and as a result these cause an increase in the contact angle. However, the evaporation rate of salt-water droplets decreases as the salt concentration increases, due to the hydration of salt ions. When the water molecules have all evaporated from the droplet, two forms of salt crystals are deposited, clump and ringlike, depending on the solid-liquid interaction strength and the evaporation rate. To form salt crystals in a ring, it is crucial that there is a pinned stage in the evaporation process, during which salt ions can move from the center to the rim of the droplets. With a stronger solid-liquid interaction strength, a slower evaporation rate, and a higher salt concentration, a complete salt crystal ring can be deposited on the surface.

Imaginando Palmares: a obra de Gayl Jones Imagining Palmares: the work of Gayl Jones

Directory of Open Access Journals (Sweden)

Stelamaris Coser

2005-12-01

Full Text Available O longo poema narrativo Song for Anninho (1981, da escritora negra Gayl Jones (Estados Unidos, interfere na narrativa da história colonial brasileira ao resgatar a figura feminina na República de Palmares, reescrever a saga de resistência dos palmaristas do ponto de vista imaginário de uma mulher negra do século XVII e, através dela, reinventar o cotidiano, os amores, as disputas e os sonhos das pessoas comuns que integravam o quilombo. O texto reflete sobre a verdade histórica, o aspecto construído de documentos, as seleções e exclusões da linguagem, e a importância do relato oral para o conhecimento de vivências e identidades à margem da história oficial. Nessa versão especial, o relato dramático do sonho, da luta e da destruição do mais famoso quilombo brasileiro usa a imaginação literária para expandir a memória e os arquivos de um dos fatos mais importantes da história das Américas, contribuindo para estimular o diálogo interamericano e iluminar a diáspora africana no Brasil e no continente.The long narrative poem Song for Anninho (1981, written by black U.S. writer Gayl Jones, interferes in the narrative of Brazilian colonial history as it highlights the female presence in the Republic of Palmares, rewrites the tale of resistance from the point of view of a black woman in the 17th Century, and, through her, reinvents the everyday lives, loves, disputes, and dreams of common people in the quilombo. The text reflects about historical truth, the constructed character of documents, selections and exclusions in language, and the importance of oral accounts to give visibility to experiences and identities marginalized by official history. In this special version, the dramatic report of the dreams, struggles, and destruction of the most famous Brazilian quilombo uses literary imagination to expand the memory and the archives of one of the most important facts in the history of the Americas, contributing to stimulate

The interpersonal relationship in clinical practice. The Barrett-Lennard Relationship Inventory as an assessment instrument.

Science.gov (United States)

Simmons, J; Roberge, L; Kendrick, S B; Richards, B

1995-03-01

The biomedical model that has long been central to medical practice is gradually being expanded to a broader biopsychosocial model. Relationship-building skills commensurate with the new paradigm need to be understood by educators and taught to medical practitioners. The person-centered, or humanistic, model of psychologist Carl Rogers provides a theoretical approach for the development of effective biopsychosocial relationships. The Barrett-Lennard Relationship Inventory (BLRI) was developed in 1962 as an assessment instrument for the person-centered model. In this article, the person-centered model and the use of the BLRI as an assessment instrument of this model are discussed. Current and potential uses of the BLRI are explored.

Staging Henry Fielding: The Author-Narrator in Tom Jones On Screen

Directory of Open Access Journals (Sweden)

Eli Løfaldli

2017-06-01

Full Text Available As recent adaptation theory has shown, classic-novel adaptation typically sets issues connected to authorship and literal and figurative ownership into play. This key feature of such adaptations is also central to the screen versions of Henry Fielding’s Tom Jones (1749. In much of Fielding’s fiction, the narrator, typically understood as an embodiment of Fielding himself, is a particularly prominent presence. The author-narrator in Tom Jones is no exception: not only is his presence strongly felt throughout the novel, but through a variety of means, ‘The History of Tom Jones, A Foundling’ is also distinctly marked as being under his control and ownership. The two adaptations of Fielding’s novel, a 1963 film and a 1997 television series, both retain the figure of the author-narrator, but differ greatly in their handling of this device and its consequent thematic ramifications. Although the 1963 film de-emphasises Henry Fielding’s status as proprietor of the story, the author-narrator as represented in the film’s voiceover commentary is a figure of authority and authorial control. In contrast, the 1997 adaptation emphasises Fielding’s ownership of the narrative and even includes the author-narrator as a character in the series, but this ownership is undermined by the irreverent treatment to which he is consistently subjected. The representations of Henry Fielding in the form of the author-narrator in both adaptations are not only indicative of shifting conceptions of authorship, but also of the important interplay between authorship, ownership and adaptation more generally.

Acute Plasma Cell Leukemia Associated with Bence-Jones Proteinuria: A case Report

Directory of Open Access Journals (Sweden)

M. Morshed

1972-07-01

Full Text Available Acute plasma cell leukemia with Bence-Jones proteinuria is reported in a 60 year old lranien male with a 25 day history of acute onset of fever. weakness, weight loss, diarrhea and bloody stools. The patient was noted to be cachectic and anemic. He had purpuric and petechial skin lesions, generalized lymphadenopathy and splenomegaly. Up to 80% immature plasma cells were present in the peripheral blood and the platelet count was 10,000. Bone marrow was hypercellular and that most of it was composed of immature plasma cells. Serum electrophoresis showed increased beta globulins and Bence-Jones protein was strongly positive in the urine. The patient died after nine days in uremic coma with haemorrhagic diathesis. Auto psy showed wide spread infi ltra tion of plasmocytes and plasmocytoblasts in all organs.

SIMPLE FLUID IN AN ATTRACTIVE, DISORDERED POLYDISPERSE MATRIX

Directory of Open Access Journals (Sweden)

T.Patsahan

2004-01-01

Full Text Available The extension of the replica Ornstein-Zernike (ROZ equations is applied to the study of the structural properties of a Lennard-Jones fluid confined in an attractive polydisperse disordered matrix. The ROZ equations in combination with the orthogonal polynomial expansions for the correlation functions are used. The radial distribution functions are calculated for the adsorbed fluid at different temperatures. The effect of matrix polydispersity on the excess internal energy is considered in our study as well.

Condensation and Evaporation Transitions in Deep Capillary Grooves

OpenAIRE

Malijevský, A. (Alexandr); Parry, A.O.

2014-01-01

We study the order of capillary condensation and evaporation transitions of a simple fluid adsorbed in a deep capillary groove using a fundamental measure density functional theory (DFT). The walls of the capillary interact with the fluid particles via long-ranged, dispersion, forces while the fluid-fluid interaction is modelled as a truncated Lennard-Jones-like potential. We find that below the wetting temperature $T_w$ condensation is first-order and evaporation is continuous with the metas...

First order phase transition of expanding matter and its fragmentation

International Nuclear Information System (INIS)

Chikazumi, Shinpei; Iwamoto, Akira

2002-01-01

Using an expanding matter model with a Lennard-Jones potential, the instability of the expanding system is investigated. The pressure, the temperature, and the density fluctuations are calculated as functions of density during the time evolution of the expanding matter, which are compared to the coexistence curve calculated by the Gibbs ensemble. The expanding matter undergoes the first order phase transition in the limit of the quasistatic expansion. The resultant fragment mass distributions are also investigated. (author)

Public lecture | "Science and society" by Bob Jones | 22 May

CERN Multimedia

2014-01-01

Public lecture: "Science and society: the impact of computing at CERN on society" by Bob Jones 22 May at 7.30 p.m. Globe of Science and Innovation Lecture in English, translated in French. Entrance free. Limited number of seats. Reservation essential: +41 22 767 76 76 or cern.reception@cern.ch

Enhancing Undergraduates' Capabilities through Team-Based Competitions: The Edward Jones Challenge

Science.gov (United States)

Umble, Elisabeth J.; Umble, Michael; Artz, Kendall

2008-01-01

The Edward Jones Company recently initiated financial sponsorship of team-based competitions in six undergraduate business core classes at Baylor University. The challenges were chosen to take place in an introductory freshman business class, Managerial Accounting, Principles of Marketing, Corporate Finance, Operations Management, and Strategic…

Technical considerations for surgical intervention of Jones fractures.

Science.gov (United States)

Mendicino, Robert W; Hentges, Matthew J; Mendicino, Michael R; Catanzariti, Alan R

2013-01-01

Jones fractures are a common injury treated by foot and ankle surgeons. Surgical intervention is recommended because of the high rate of delayed union, nonunion, and repeat fracture, when treated conservatively. Percutaneous intramedullary screw fixation is commonly used in the treatment of these fractures. We present techniques that can increase the surgical efficiency and decrease the complications associated with percutaneous delivery of internal fixation. Copyright © 2013 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

An EQT-based cDFT approach for a confined Lennard-Jones fluid mixture

Energy Technology Data Exchange (ETDEWEB)

Motevaselian, M. H.; Mashayak, S. Y.; Aluru, N. R., E-mail: aluru@illinois.edu [Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2015-09-28

Empirical potential-based quasi-continuum theory (EQT) provides a route to incorporate atomistic detail into continuum framework such as the Nernst-Planck equation. EQT can also be used to construct a grand potential functional for classical density functional theory (cDFT). The combination of EQT and cDFT provides a simple and fast approach to predict the inhomogeneous density, potential profiles, and thermodynamic properties of confined fluids. We extend the EQT-cDFT approach to confined fluid mixtures and demonstrate it by simulating a mixture of methane and hydrogen inside slit-like channels of graphene. We show that the EQT-cDFT predictions for the structure of the confined fluid mixture compare well with the molecular dynamics simulation results. In addition, our results show that graphene slit nanopores exhibit a selective adsorption of methane over hydrogen.

Analysis of three-phase equilibrium conditions for methane hydrate by isometric-isothermal molecular dynamics simulations

Science.gov (United States)

Yuhara, Daisuke; Brumby, Paul E.; Wu, David T.; Sum, Amadeu K.; Yasuoka, Kenji

2018-05-01

To develop prediction methods of three-phase equilibrium (coexistence) conditions of methane hydrate by molecular simulations, we examined the use of NVT (isometric-isothermal) molecular dynamics (MD) simulations. NVT MD simulations of coexisting solid hydrate, liquid water, and vapor methane phases were performed at four different temperatures, namely, 285, 290, 295, and 300 K. NVT simulations do not require complex pressure control schemes in multi-phase systems, and the growth or dissociation of the hydrate phase can lead to significant pressure changes in the approach toward equilibrium conditions. We found that the calculated equilibrium pressures tended to be higher than those reported by previous NPT (isobaric-isothermal) simulation studies using the same water model. The deviations of equilibrium conditions from previous simulation studies are mainly attributable to the employed calculation methods of pressure and Lennard-Jones interactions. We monitored the pressure in the methane phase, far from the interfaces with other phases, and confirmed that it was higher than the total pressure of the system calculated by previous studies. This fact clearly highlights the difficulties associated with the pressure calculation and control for multi-phase systems. The treatment of Lennard-Jones interactions without tail corrections in MD simulations also contributes to the overestimation of equilibrium pressure. Although improvements are still required to obtain accurate equilibrium conditions, NVT MD simulations exhibit potential for the prediction of equilibrium conditions of multi-phase systems.

Optimization of partial multicanonical molecular dynamics simulations applied to an alanine dipeptide in explicit water solvent.

Science.gov (United States)

Okumura, Hisashi

2011-01-07

The partial multicanonical algorithm for molecular dynamics and Monte Carlo simulations samples a wide range of an important part of the potential energy. Although it is a strong technique for structure prediction of biomolecules, the choice of the partial potential energy has not been optimized. In order to find the best choice, partial multicanonical molecular dynamics simulations of an alanine dipeptide in explicit water solvent were performed with 15 trial choices for the partial potential energy. The best choice was found to be the sum of the electrostatic, Lennard-Jones, and torsion-angle potential energies between solute atoms. In this case, the partial multicanonical simulation sampled all of the local-minimum free-energy states of the P(II), C(5), α(R), α(P), α(L), and C states and visited these states most frequently. Furthermore, backbone dihedral angles ϕ and ψ rotated very well. It is also found that the most important term among these three terms is the electrostatic potential energy and that the Lennard-Jones term also helps the simulation to overcome the steric restrictions. On the other hand, multicanonical simulation sampled all of the six states, but visited these states fewer times. Conventional canonical simulation sampled only four of the six states: The P(II), C(5), α(R), and α(P) states.

Analysis of three-phase equilibrium conditions for methane hydrate by isometric-isothermal molecular dynamics simulations.

Science.gov (United States)

Yuhara, Daisuke; Brumby, Paul E; Wu, David T; Sum, Amadeu K; Yasuoka, Kenji

2018-05-14

To develop prediction methods of three-phase equilibrium (coexistence) conditions of methane hydrate by molecular simulations, we examined the use of NVT (isometric-isothermal) molecular dynamics (MD) simulations. NVT MD simulations of coexisting solid hydrate, liquid water, and vapor methane phases were performed at four different temperatures, namely, 285, 290, 295, and 300 K. NVT simulations do not require complex pressure control schemes in multi-phase systems, and the growth or dissociation of the hydrate phase can lead to significant pressure changes in the approach toward equilibrium conditions. We found that the calculated equilibrium pressures tended to be higher than those reported by previous NPT (isobaric-isothermal) simulation studies using the same water model. The deviations of equilibrium conditions from previous simulation studies are mainly attributable to the employed calculation methods of pressure and Lennard-Jones interactions. We monitored the pressure in the methane phase, far from the interfaces with other phases, and confirmed that it was higher than the total pressure of the system calculated by previous studies. This fact clearly highlights the difficulties associated with the pressure calculation and control for multi-phase systems. The treatment of Lennard-Jones interactions without tail corrections in MD simulations also contributes to the overestimation of equilibrium pressure. Although improvements are still required to obtain accurate equilibrium conditions, NVT MD simulations exhibit potential for the prediction of equilibrium conditions of multi-phase systems.

Searching for globally optimal functional forms for interatomic potentials using genetic programming with parallel tempering.

Science.gov (United States)

Slepoy, A; Peters, M D; Thompson, A P

2007-11-30

Molecular dynamics and other molecular simulation methods rely on a potential energy function, based only on the relative coordinates of the atomic nuclei. Such a function, called a force field, approximately represents the electronic structure interactions of a condensed matter system. Developing such approximate functions and fitting their parameters remains an arduous, time-consuming process, relying on expert physical intuition. To address this problem, a functional programming methodology was developed that may enable automated discovery of entirely new force-field functional forms, while simultaneously fitting parameter values. The method uses a combination of genetic programming, Metropolis Monte Carlo importance sampling and parallel tempering, to efficiently search a large space of candidate functional forms and parameters. The methodology was tested using a nontrivial problem with a well-defined globally optimal solution: a small set of atomic configurations was generated and the energy of each configuration was calculated using the Lennard-Jones pair potential. Starting with a population of random functions, our fully automated, massively parallel implementation of the method reproducibly discovered the original Lennard-Jones pair potential by searching for several hours on 100 processors, sampling only a minuscule portion of the total search space. This result indicates that, with further improvement, the method may be suitable for unsupervised development of more accurate force fields with completely new functional forms. Copyright (c) 2007 Wiley Periodicals, Inc.

Nanodroplet processing platform for deep and quantitative proteome profiling of 10–100 mammalian cells

Energy Technology Data Exchange (ETDEWEB)

Zhu, Ying; Piehowski, Paul D.; Zhao, Rui; Chen, Jing; Shen, Yufeng; Moore, Ronald J.; Shukla, Anil K.; Petyuk, Vladislav A.; Campbell-Thompson, Martha; Mathews, Clayton E.; Smith, Richard D.; Qian, Wei-Jun; Kelly, Ryan T.

2018-02-28

Nanoscale or single cell technologies are critical for biomedical applications. However, current mass spectrometry (MS)-based proteomic approaches require samples comprising a minimum of thousands of cells to provide in-depth profiling. Here, we report the development of a nanoPOTS (Nanodroplet Processing in One pot for Trace Samples) platform as a major advance in overall sensitivity. NanoPOTS dramatically enhances the efficiency and recovery of sample processing by downscaling processing volumes to <200 nL to minimize surface losses. When combined with ultrasensitive LC-MS, nanoPOTS allows identification of ~1500 to ~3,000 proteins from ~10 to ~140 cells, respectively. By incorporating the Match Between Runs algorithm of MaxQuant, >3000 proteins were consistently identified from as few as 10 cells. Furthermore, we demonstrate robust quantification of ~2400 proteins from single human pancreatic islet thin sections from type 1 diabetic and control donors, illustrating the application of nanoPOTS for spatially resolved proteome measurements from clinical tissues.

Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

Science.gov (United States)

2013-01-01

We report on the formation of mixed alkali–alkaline earth molecules (LiCa) on helium nanodroplets and present a comprehensive experimental and theoretical study of the ground and excited states of LiCa. Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) spectroscopy and laser induced fluorescence (LIF) spectroscopy were used for the experimental investigation of LiCa from 15000 to 25500 cm–1. The 42Σ+ and 32Π states show a vibrational structure accompanied by distinct phonon wings, which allows us to determine molecular parameters as well as to study the interaction of the molecule with the helium droplet. Higher excited states (42Π, 52Σ+, 52Π, and 62Σ+) are not vibrationally resolved and vibronic transitions start to overlap. The experimental spectrum is well reproduced by high-level ab initio calculations. By using a multireference configuration interaction (MRCI) approach, we calculated the 19 lowest lying potential energy curves (PECs) of the LiCa molecule. On the basis of these calculations, we could identify previously unobserved transitions. Our results demonstrate that the helium droplet isolation approach is a powerful method for the characterization of tailor-made alkali–alkaline earth molecules. In this way, important contributions can be made to the search for optimal pathways toward the creation of ultracold alkali–alkaline earth ground state molecules from the corresponding atomic species. Furthermore, a test for PECs calculated by ab initio methods is provided. PMID:24028555

Communication: Simple liquids' high-density viscosity.

Science.gov (United States)

Costigliola, Lorenzo; Pedersen, Ulf R; Heyes, David M; Schrøder, Thomas B; Dyre, Jeppe C

2018-02-28

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.

Cluster pair correlation function of simple fluids: energetic connectivity criteria

OpenAIRE

Pugnaloni, Luis A.; Zarragoicoechea, Guillermo J.; Vericat, Fernando

2006-01-01

We consider the clustering of Lennard-Jones particles by using an energetic connectivity criterion proposed long ago by T.L. Hill [J. Chem. Phys. 32, 617 (1955)] for the bond between pairs of particles. The criterion establishes that two particles are bonded (directly connected) if their relative kinetic energy is less than minus their relative potential energy. Thus, in general, it depends on the direction as well as on the magnitude of the velocities and positions of the particles. An integ...

Communication: Simple liquids' high-density viscosity

Science.gov (United States)

Costigliola, Lorenzo; Pedersen, Ulf R.; Heyes, David M.; Schrøder, Thomas B.; Dyre, Jeppe C.

2018-02-01

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.

Analysis of bound-state spectra near the threshold of neutral particle interaction potentials

International Nuclear Information System (INIS)

Ou Fang; Cao Zhuangqi; Chen Jianping; Xu Junjie

2006-01-01

It is understood that conventional semiclassical approximations deteriorate towards threshold in a typical neutral particle interaction potential which is important for the study of ultra-cold atoms and molecules. In this Letter we give an example of the Lennard-Jones potential with tuning of the strength parameter on the basis of the analytical transfer matrix (ATM) method. Highly accurate quantum mechanical results, such as number of the bound states, energy level density and the eigenvalues with extremely low energies have been derived

Microscopic theory of warm ionized gases: equation of state and kinetic Schottky anomaly

International Nuclear Information System (INIS)

Capolupo, A; Giampaolo, S M; Illuminati, F

2013-01-01

Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed.

Application of Ultrasound to Selectively Localize Nanodroplets for Targeted Imaging and Therapy

Directory of Open Access Journals (Sweden)

Paul A. Dayton

2006-07-01

Full Text Available Lipid-coated perfluorocarbon nanodroplets are submicrometer-diameter liquid-filled droplets with proposed applications in molecularly targeted therapeutics and ultrasound (US imaging. Ultrasonic molecular imaging is unique in that the optimal application of these agents depends not only on the surface chemistry, but also on the applied US field, which can increase receptor-ligand binding and membrane fusion. Theory and experiments are combined to demonstrate the displacement of perfluorocarbon nanoparticles in the direction of US propagation, where a traveling US wave with a peak pressure on the order of megapascals and frequency in the megahertz range produces a particle translational velocity that is proportional to acoustic intensity and increases with increasing center frequency. Within a vessel with a diameter on the order of hundreds of micrometers or larger, particle velocity on the order of hundreds of micrometers per second is produced and the dominant mechanism for droplet displacement is shown to be bulk fluid streaming. A model for radiation force displacement of particles is developed and demonstrates that effective particle displacement should be feasible in the microvasculature. In a flowing system, acoustic manipulation of targeted droplets increases droplet retention. Additionally, we demonstrate the feasibility of US-enhanced particle internalization and therapeutic delivery.

On the localisation of antigenic determinants in a Bence Jones protein

NARCIS (Netherlands)

Eyk, H.G. van; Myszkowska, K.

1967-01-01

1. 1. The presence of a low molecular weight protein (1.2 S), having antigenic determinants in common with the homologous Bence Jones protein (3.4 S), has been observed in the urine of a patient with multiple myeloma. Its amino acid composition and α-NH2-terminal amino acid residue make it likely

Fairy tales? Marion Jones, C.J. Hunter and the framing of doping in American newspapers

DEFF Research Database (Denmark)

Pfister, Gertrud Ursula; Gems, Gerald

2015-01-01

This article deals with the images, metaphors and narratives in the media coverage of doping in the United States. It presents a case study with a focus on Marion Jones, the most celebrated track athlete of the turn of the millennium, and her husband, C.J. Hunter, a shot put world champion...... under suspicion. At the same time, the 2000 Olympics can be considered a watershed in American anti-doping policy. The media portrayed Jones and Hunter as the Beauty and the Beast or Svengali and his victim, using a famous fairy tale and a well-known novel to capture attention, label the protagonists...

PHYTOREMEDIATION OF DREDGED SEDIMENTS: A CASE STUDY AT THE JONES ISLAND CDF

Science.gov (United States)

The Jones Island Confined Disposal Facility (CDF) is a 44 acre in-lake area that receives dredged material from Milwaukee Harbor and the surrounding waterways. Some of those materials are contaminated with industrial waste and urban run-off. The CDF is nearing the end of its desi...

Flexible equation of state for a hard sphere and Lennard–Jones fluid ...

Indian Academy of Sciences (India)

Equation of state; Lennard–Jones potential; hard-sphere potential; liquid mixture; computer simulation. ... deviation than Barker–Henderson BH2 for LJ fluids, and results are much closer to molecular dynamics (MD) simulations than expectations and reproduce the existing simulation data and present EoS for LJ potential, ...

Solitons on H bonds in proteins

DEFF Research Database (Denmark)

d'Ovidio, F.; Bohr, H.G.; Lindgård, Per-Anker

2003-01-01

system shows that the solitons are spontaneously created and are stable and moving along the helix axis. A perturbation on one of the three H-bond lines forms solitons on the other H bonds as well. The robust solitary wave may explain very long-lived modes in the frequency range of 100 cm(-1) which...... are found in recent x-ray laser experiments. The dynamics parameters of the Toda lattice are in accordance with the usual Lennard-Jones parameters used for realistic H-bond potentials in proteins....

An Analytical Model of Nanometer Scale Viscoelastic Properties of Polymer Surfaces Measured Using an Atomic Force Microscope

Science.gov (United States)

2011-03-01

have been developed ranging from measuring surface details to modifying surface structures . This chapter focuses on aspects of AFM modeling the- ory and...how far apart they are. An example of a poten- tial function is the Lennard-Jones potential, which is also called the 6-12 potential. It can be...γ1 + γ2 + γ12, (31) where γ1 and γ2 are the surface energies of the two adhering spheres, and γ12 is the interfacial energy between the two spheres

Intermolecular potential for Ar + D2O from differential scattering cross sections, and its implications for the water pair potential

International Nuclear Information System (INIS)

Brooks, R.; Porter, R.A.R.; Kalos, F.; Grosser, A.E.

1975-01-01

A velocity selected molecular beam of D 2 O was crossed with a nozzle beam of Ar and the angular distribution of the scattered D 2 O was measured mass spectrometrically. By varying the velocity of the D 2 O beam, the differential cross section was measured at two collision energies. The experimental results were compared with synthetic differential cross sections calculated from Lennard-Jones and Kihara-Stockmayer trial potentials to determine potential parameters. Implications for the H 2 O pair potential are discussed

Mutability and Deformity: Models of the Body and the Art of Edward Burne-Jones

Directory of Open Access Journals (Sweden)

Caroline Arscott

2008-10-01

Full Text Available This essay discusses the alternatives that emerged in the Victorian period to a perfect and regular neoclassical conception of the heroic male body. It charts the evolving fascination with mutable forms, whether heroic or monstrous, imagined first of all in the 1850s in terms of a body conceived of as bolted together or modified by the fusion of organic and inorganic substances. The early work of Burne-Jones is discussed in relation to investigations of cell structure and mechanical inventions in the Great Exhibition of 1851 such as the 'Expanding Model of a Man' invented by Count Dunin. Arscott also discusses the cybernetic implications of Burne-Jones's gouache, 'The Merciful Knight' (1863. Later works of Burne-Jones, in particular 'Perseus and the Graiae' (1878 and the reworked composition 'Love Among the Ruins' (1894, are discussed in terms of a turn towards a sense of the spread and mutation of organic being through and beyond the self. Arscott considers this alongside contemporary investigations of the role of bacilli in disease, looking at leprosy and the heroisation of the Leper Priest of Molokai, Father Damien in the 1880s and 1890s. In the late-Victorian period, Arscott concludes, monstrous distortion was imagined as the unpredictable and unruly proliferation of the organic by the organism in both its vital and morbid states.

Does the Watson-Jones or Modified Smith-Petersen Approach Provide Superior Exposure for Femoral Neck Fracture Fixation?

Science.gov (United States)

Lichstein, Paul M; Kleimeyer, John P; Githens, Michael; Vorhies, John S; Gardner, Michael J; Bellino, Michael; Bishop, Julius

2018-04-24

A well-reduced femoral neck fracture is more likely to heal than a poorly reduced one, and increasing the quality of the surgical exposure makes it easier to achieve anatomic fracture reduction. Two open approaches are in common use for femoral neck fractures, the modified Smith-Petersen and Watson-Jones; however, to our knowledge, the quality of exposure of the femoral neck exposure provided by each approach has not been investigated. (1) What is the respective area of exposed femoral neck afforded by the Watson-Jones and modified Smith-Petersen approaches? (2) Is there a difference in the ability to visualize and/or palpate important anatomic landmarks provided by the Watson-Jones and modified Smith-Petersen approaches? Ten fresh-frozen human pelvi underwent both modified Smith-Petersen (utilizing the caudal extent of the standard Smith-Petersen interval distal to the anterosuperior iliac spine and parallel to the palpable interval between the tensor fascia lata and the sartorius) and Watson-Jones approaches. Dissections were performed by three fellowship-trained orthopaedic traumatologists with extensive experience in both approaches. Exposure (in cm) was quantified with calibrated digital photographs and specialized software. Modified Smith-Petersen approaches were analyzed before and after rectus femoris tenotomy. The ability to visualize and palpate seven clinically relevant anatomic structures (the labrum, femoral head, subcapital femoral neck, basicervical femoral neck, greater trochanter, lesser trochanter, and medial femoral neck) was also recorded. The quantified area of the exposed proximal femur was utilized to compare which approach afforded the largest field of view of the femoral neck and articular surface for assessment of femoral neck fracture and associated femoral head injury. The ability to visualize and palpate surrounding structures was assessed so that we could better understand which approach afforded the ability to assess structures that

Measurement of the Jones matrix of liquid crystal displays using a common path interferometer

International Nuclear Information System (INIS)

Sarkadi, Tamás; Koppa, Pál

2011-01-01

We propose a robust interferometric method to measure the Jones matrix of polarization components, especially liquid crystal displays. Phase values are measured by a simple common path interferometer containing a birefringent crystal as beam splitter and a polarizer as beam combiner. This solution eliminates the sensitivity of traditional interferometric techniques to vibration, temperature variation or wavefront distortion. The proposed phase measurement method is applicable to the measurement of both spatially homogeneous and binary modulated states, thus the modulation transfer function and inter-pixel interference can also be studied. We demonstrate this technique by the measurement of a liquid crystal on silicon display. The resulting Jones matrix, as a function of displayed gray level, can be efficiently embedded in any numeric model of an optical system containing the analyzed spatial light modulator

Performance improvement of multi-class detection using greedy algorithm for Viola-Jones cascade selection

Science.gov (United States)

Tereshin, Alexander A.; Usilin, Sergey A.; Arlazarov, Vladimir V.

2018-04-01

This paper aims to study the problem of multi-class object detection in video stream with Viola-Jones cascades. An adaptive algorithm for selecting Viola-Jones cascade based on greedy choice strategy in solution of the N-armed bandit problem is proposed. The efficiency of the algorithm on the problem of detection and recognition of the bank card logos in the video stream is shown. The proposed algorithm can be effectively used in documents localization and identification, recognition of road scene elements, localization and tracking of the lengthy objects , and for solving other problems of rigid object detection in a heterogeneous data flows. The computational efficiency of the algorithm makes it possible to use it both on personal computers and on mobile devices based on processors with low power consumption.

Importance of dispersion and electron correlation in ab initio protein folding.

Science.gov (United States)

He, Xiao; Fusti-Molnar, Laszlo; Cui, Guanglei; Merz, Kenneth M

2009-04-16

Dispersion is well-known to be important in biological systems, but the effect of electron correlation in such systems remains unclear. In order to assess the relationship between the structure of a protein and its electron correlation energy, we employed both full system Hartree-Fock (HF) and second-order Møller-Plesset perturbation (MP2) calculations in conjunction with the Polarizable Continuum Model (PCM) on the native structures of two proteins and their corresponding computer-generated decoy sets. Because of the expense of the MP2 calculation, we have utilized the fragment molecular orbital method (FMO) in this study. We show that the sum of the Hartree-Fock (HF) energy and force field (LJ6)-derived dispersion energy (HF + LJ6) is well correlated with the energies obtained using second-order Møller-Plesset perturbation (MP2) theory. In one of the two examples studied, the correlation energy as well as the empirical dispersive energy term was able to discriminate between native and decoy structures. On the other hand, for the second protein we studied, neither the correlation energy nor dispersion energy showed discrimination capabilities; however, the ab initio MP2 energy and the HF+LJ6 both ranked the native structure correctly. Furthermore, when we randomly scrambled the Lennard-Jones parameters, the correlation between the MP2 energy and the sum of the HF energy and dispersive energy (HF+LJ6) significantly drops, which indicates that the choice of Lennard-Jones parameters is important.

Solute-solvent cavity and bridge functions. I. Varying size of the solute

International Nuclear Information System (INIS)

Vyalov, I.; Chuev, G.; Georgi, N.

2014-01-01

In this work we present the results of the extensive molecular simulations of solute-solvent cavity and bridge functions. The mixtures of Lennard-Jones solvent with Lennard-Jones solute at infinite dilution are considered for different solute-solvent size ratios—up to 4:1. The Percus-Yevick and hypernetted chain closures deviate substantially from simulation results in the investigated temperature and density ranges. We also find that the behavior of the indirect and cavity correlation functions is non-monotonous within the hard-core region, but the latter can be successfully approximated by mean-field theory if the solute-solvent interaction energy is divided into repulsive and attractive contribution, according to Weeks-Chandler-Andersen theory. Furthermore, in spite of the non-monotonous behavior of logarithm of the cavity function and the indirect correlation function, their difference, i.e., the bridge function remains constant within the hard-core region. Such behavior of the bridge and indirect correlation functions at small distances and for small values of indirect correlation function is well known from the Duh-Haymet plots, where the non-unique relationship results in loops of the bridge function vs. indirect correlation function graphs. We show that the same pathological behavior appears also when distance is small and indirect correlation function is large. We further show that the unique functional behavior of the bridge function can be established when bridge is represented as a function of the renormalized, repulsive indirect correlation function

Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions

Energy Technology Data Exchange (ETDEWEB)

Kadoura, Ahmad; Sun, Shuyu, E-mail: shuyu.sun@kaust.edu.sa; Salama, Amgad

2014-08-01

Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system's potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (ε, σ) for single site models were proposed for methane, nitrogen and carbon monoxide.

From interatomic interaction potentials via Einstein field equation techniques to time dependent contact mechanics

International Nuclear Information System (INIS)

Schwarzer, N

2014-01-01

In order to understand the principle differences between rheological or simple stress tests like the uniaxial tensile test to contact mechanical tests and the differences between quasistatic contact experiments and oscillatory ones, this study resorts to effective first principles. This study will show how relatively simple models simulating bond interactions in solids using effective potentials like Lennard-Jones and Morse can be used to investigate the effect of time dependent stress-induced softening or stiffening of these solids. The usefulness of the current study is in the possibility of deriving relatively simple dependences of the bulk-modulus B on time, shear and pressure P with time t. In cases where it is possible to describe, or at least partially describe a material by Lennard-Jones potential approaches, the above- mentioned dependences are even completely free of microscopic material parameters. Instead of bond energies and length, only specific integral parameters like Young’s modulus and Poisson’s ratio are required. However, in the case of time dependent (viscose) material behavior the parameters are not constants anymore. They themselves depend on time and the actual stress field, especially the shear field. A body completely consisting of so called standard linear solid interacting particles will then phenomenologically show a completely different and usually much more complicated mechanical behavior. The influence of the time dependent pressure-shear-induced Young’s modulus change is discussed with respect to mechanical contact experiments and their analysis in the case of viscose materials. (papers)

Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions

KAUST Repository

Kadoura, Ahmad Salim

2014-08-01

Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system\\'s potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (ε, σ) for single site models were proposed for methane, nitrogen and carbon monoxide. © 2014 Elsevier Inc.

Vere-Jones' self-similar branching model

International Nuclear Information System (INIS)

Saichev, A.; Sornette, D.

2005-01-01

Motivated by its potential application to earthquake statistics as well as for its intrinsic interest in the theory of branching processes, we study the exactly self-similar branching process introduced recently by Vere-Jones. This model extends the ETAS class of conditional self-excited branching point-processes of triggered seismicity by removing the problematic need for a minimum (as well as maximum) earthquake size. To make the theory convergent without the need for the usual ultraviolet and infrared cutoffs, the distribution of magnitudes m ' of daughters of first-generation of a mother of magnitude m has two branches m ' ' >m with exponent β+d, where β and d are two positive parameters. We investigate the condition and nature of the subcritical, critical, and supercritical regime in this and in an extended version interpolating smoothly between several models. We predict that the distribution of magnitudes of events triggered by a mother of magnitude m over all generations has also two branches m ' ' >m with exponent β+h, with h=d√(1-s), where s is the fraction of triggered events. This corresponds to a renormalization of the exponent d into h by the hierarchy of successive generations of triggered events. For a significant part of the parameter space, the distribution of magnitudes over a full catalog summed over an average steady flow of spontaneous sources (immigrants) reproduces the distribution of the spontaneous sources with a single branch and is blind to the exponents β,d of the distribution of triggered events. Since the distribution of earthquake magnitudes is usually obtained with catalogs including many sequences, we conclude that the two branches of the distribution of aftershocks are not directly observable and the model is compatible with real seismic catalogs. In summary, the exactly self-similar Vere-Jones model provides an attractive new approach to model triggered seismicity, which alleviates delicate questions on the role of

RASW : a Run-time Adaptive Sliding Window to Improve Viola-Jones object detection.

NARCIS (Netherlands)

Comaschi, F.; Stuijk, S.; Basten, T.; Corporaal, H.

2013-01-01

Abstract—In recent years accurate algorithms for detecting objects in images have been developed. Among these algorithms, the object detection scheme proposed by Viola and Jones gained great popularity, especially after the release of high-quality face classifiers by the OpenCV group. However, as

The fish and fisheries of Jones Bank and the wider Celtic Sea

Science.gov (United States)

Martinez, I.; Ellis, J. R.; Scott, B.; Tidd, A.

2013-10-01

The Celtic Sea is a diverse fishing ground that supports important commercial fisheries for a range of demersal fish, large and small-bodied pelagic fish and a variety of cephalopods and other shellfish. A regional overview of the main commercial fish stocks of the Celtic Sea and of the fish that occur in the vicinity of Jones Bank are provided through analyses of landings data from English and Welsh vessels, and from scientific trawl surveys. Dedicated smaller scale sampling via trawl surveys combined with baited cameras on and around the Jones Bank were also analysed to investigate the importance of sandbank habitats with attention paid to the differences in the species occurring on the top of the bank in comparison to adjacent off-bank habitats. Official landing statistics for UK (English and Welsh) vessels indicated that the predominant commercial demersal species in ICES Divisions VIIg,h (in terms of quantities landed) were anglerfish, megrim, pollack and skates (Rajidae). There were, however, regional differences in the distribution of fish and fisheries, and the area surrounding Jones Bank (ICES Rectangles 28E1 and 28E2) supports fisheries for megrim, anglerfish, skates, hake, ling and turbot, with otter trawl, gillnet and beam trawl the main gears used. Recent survey data collected with GOV (Grande Ouverture Verticale) trawl from the Celtic Sea (ICES Divisions VIIe-h, 2007-2010) were used to highlight the broad scale distribution of the main fish assemblages in the Celtic Sea. Analyses of the fish and cephalopod catches from these surveys indicated that there were four broad assemblages in the area, including (i) a region around the Cornwall (which will also be partly influenced by the necessity to use rockhopper ground gear on these rough grounds), (ii) the shallower regions of the north-western Celtic Sea (including parts of the Bristol Channel), (iii) the deeper parts of the outer shelf and (iv) the central Celtic Sea. These data also provided

Lennard-Jones fluids in two-dimensional nano-pores. Multi-phase coexistence and fluid structure

Science.gov (United States)

Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim

2014-03-01

We present a number of fundamental findings on the wetting behaviour of nano-pores. A popular model for fluid confinement is a one-dimensional (1D) slit pore formed by two parallel planar walls and it exhibits capillary condensation (CC): a first-order phase transition from vapour to capillary-liquid (Kelvin shift). Capping such a pore at one end by a third orthogonal wall forms a prototypical two-dimensional (2D) pore. We show that 2D pores possess a wetting temperature such that below this temperature CC remains of first order, above it becomes a continuous phase transition manifested by a slab of capillary-liquid filling the pore from the capping wall. Continuous CC exhibits hysteresis and can be preceded by a first-order capillary prewetting transition. Additionally, liquid drops can form in the corners of the 2D pore (remnant of 2D wedge prewetting). The three fluid phases, vapour, capillary-liquid slab and corner drops, can coexist at the pore triple point. Our model is based on the statistical mechanics of fluids in the density functional formulation. The fluid-fluid and fluid-substrate interactions are dispersive. We analyze in detail the microscopic fluid structure, isotherms and full phase diagrams. Our findings also suggest novel ways to control wetting of nano-pores. We are grateful to the European Research Council via Advanced Grant No. 247031 for support.

The heat current density correlation function: sum rules and thermal conductivity

International Nuclear Information System (INIS)

Singh, Shaminder; Tankeshwar, K; Pathak, K N; Ranganathan, S

2006-01-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed

The heat current density correlation function: sum rules and thermal conductivity

Energy Technology Data Exchange (ETDEWEB)

Singh, Shaminder [Department of Physics, Panjab University, Chandigarh-160 014 (India); Tankeshwar, K [Department of Physics, Panjab University, Chandigarh-160 014 (India); Pathak, K N [Department of Physics, Panjab University, Chandigarh-160 014 (India); Ranganathan, S [Department of Physics, Royal Military College, Kingston, ON, K7K 7B4 (Canada)

2006-02-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed.

Communication: An exact bound on the bridge function in integral equation theories.

Science.gov (United States)

Kast, Stefan M; Tomazic, Daniel

2012-11-07

We show that the formal solution of the general closure relation occurring in Ornstein-Zernike-type integral equation theories in terms of the Lambert W function leads to an exact relation between the bridge function and correlation functions, most notably to an inequality that bounds possible bridge values. The analytical results are illustrated on the example of the Lennard-Jones fluid for which the exact bridge function is known from computer simulations under various conditions. The inequality has consequences for the development of bridge function models and rationalizes numerical convergence issues.

Variation along liquid isomorphs of the driving force for crystallization

DEFF Research Database (Denmark)

Pedersen, Ulf Rørbæk; Adrjanowicz, Karolina; Niss, Kristine

2017-01-01

at a reference temperature. More general analysis allows interpretation of experimental data for molecular liquids such as dimethyl phthalate and indomethacin, and suggests that the isomorph scaling exponent γ in these cases is an increasing function of density, although this cannot be seen in measurements......We investigate the variation of the driving force for crystallization of a supercooled liquid along isomorphs, curves along which structure and dynamics are invariant. The variation is weak, and can be predicted accurately for the Lennard-Jones fluid using a recently developed formalism and data...

Estimating the density-scaling exponent of a monatomic liquid from its pair potential

DEFF Research Database (Denmark)

Bøhling, Lasse; Bailey, Nicholas; Schrøder, Thomas

2014-01-01

This paper investigates two conjectures for calculating the density dependence of the density-scaling exponent γ of a single-component, pair-potential liquid with strong virial potential-energy correlations. The first conjecture gives an analytical expression for γ directly in terms of the pair...... potential. The second conjecture is a refined version of this involving the most likely nearest-neighbor distance determined from the pair-correlation function. The conjectures are tested by simulations of three systems, one of which is the standard Lennard-Jones liquid. While both expressions give...

Feasibility of a single-parameter description of equilibrium viscous liquid dynamics

DEFF Research Database (Denmark)

Pedersen, Ulf Rørbæk; Christensen, Tage Emil; Schrøder, Thomas

2008-01-01

Molecular dynamics results for the dynamic Prigogine-Defay ratio are presented for two glass-forming liquids, thus evaluating the experimentally relevant quantity for testing whether metastable-equilibrium liquid dynamics is described by a single parameter to a good approximation. For the Kob......-Andersen binary Lennard-Jones mixture as well as for an asymmetric dumbbell model liquid, a single-parameter description works quite well. This is confirmed by time-domain results where it is found that energy and pressure fluctuations are strongly correlated on the alpha time scale in the constant...

Note: Modification of the Gay-Berne potential for improved accuracy and speed

Science.gov (United States)

Persson, Rasmus A. X.

2012-06-01

A modification of the Gay-Berne (GB) potential is proposed which is about 10% to 20% more speed efficient and statistically more accurate in reproducing the energy of interaction of two linear Lennard-Jones tetratomics when averaged over all orientations. For the special cases of end-to-end and side-by-side configurations, the new potential is equivalent to the GB one. A simple generalization to dissimilar particles of D∞h symmetry is presented but does not retain the superior agreement with respect to its GB counterpart, except at close range.

Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

DEFF Research Database (Denmark)

Lerner, Edan; Bailey, Nicholas; Dyre, J. C.

2014-01-01

Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between...... the flow events. We show that simulations at a single density in conjunction with an equilibrium-liquid simulation at the same density allow one to predict the plastic flow-event statistics at other densities. This is done by applying the recently established “hidden scale invariance” of simple liquids...

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

Electro-suppression of water nano-droplets' solidification in no man's land: Electromagnetic fields' entropic trapping of supercooled water

Science.gov (United States)

Nandi, Prithwish K.; Burnham, Christian J.; English, Niall J.

2018-01-01

Understanding water solidification, especially in "No Man's Land" (NML) (150 K < T < 235 K) is crucially important (e.g., upper-troposphere cloud processes) and challenging. A rather neglected aspect of tropospheric ice-crystallite formation is inevitably present electromagnetic fields' role. Here, we employ non-equilibrium molecular dynamics of aggressively quenched supercooled water nano-droplets in the gas phase under NML conditions, in externally applied electromagnetic (e/m) fields, elucidating significant differences between effects of static and oscillating fields: although static fields induce "electro-freezing," e/m fields exhibit the contrary - solidification inhibition. This anti-freeze action extends not only to crystal-ice formation but also restricts amorphisation, i.e., suppression of low-density amorphous ice which forms otherwise in zero-field NML environments. E/m-field applications maintain water in the deeply supercooled state in an "entropic trap," which is ripe for industrial impacts in cryo-freezing, etc.

Machine News and Volatility: The Dow Jones Industrial Average and the TRNA Sentiment Series

NARCIS (Netherlands)

D.E. Allen (David); A.K. Singh (Abhay)

2014-01-01

markdownabstract__Abstract__ This paper features an analysis of the relationship between the volatility of the Dow Jones Industrial Average (DJIA) Index and a sentiment news series using daily data obtained from the Thomson Reuters News Analytics (TRNA) provided by SIRCA (The Securities Industry

Nephrotoxicity of Bence-Jones proteins: correlation with endocytosis by BHK cells and intracellular movement

Directory of Open Access Journals (Sweden)

Ana Lucia Nicastri

2001-06-01

Full Text Available The aim of this investigation was to evaluate the endocytosis of two Bence-Jones proteins by renal cells in order to elucidate the interference of their physical and chemical characteristics on nephrotoxicity. Bence-Jones proteins (AK and GL were purified and isolated from the urine of two patients with multiple myeloma. The isotype of both proteins was characterised as being human monoclonal lambda light chain. The AK protein presented mainly an Ip>7.0, a high content of galactose and a low amount of sialic acid molecules. On the other hand, the GL protein presented a single band with an Ip of 4.3, a higher level of sialic acid and a reduced amount of galactose, in comparison with the AK protein. Baby Hamster Kidney (BHK cells were maintained in culture in bottles at 37ºC, using DMEM culture media supplemented with 10% of calf serum with a pH of 7.4. Once the monolayer was observed to be confluent, the BHK cells were incubated with the two proteins, dissolved in a serum-free medium for 1, 5, 15, 30, 60 minutes and 24 hours. Control cells were established omitting the incubation with Bence-Jones proteins, but maintaining all of the other conditions. After, this the cells were washed, trypsinised, centrifuged and fixed in a solution of 4% paraformaldehyde and 0.5% glutaraldehyde on a 0.1 M, pH 7.4 phosphate buffer. Cells were processed for immunocytochemical reactions by using protein A coupled with colloidal gold and further silver enhancement. Semi-thin sections of the pellets were obtained and submitted to the cytochemical reactions. Detection of labelling was made by using light microscopy. It was observed that GL protein tended to be directed towards a perinuclear position, whereas the AK protein tended to suffer lysosomal deviation, suggesting that there is a direct contribution of physical and chemical characteristics on intracellular direction taken by Bence-Jones proteins.O objetivo deste trabalho foi avaliar a endocitose de duas prote

Ejection of solvated ions from electrosprayed methanol/water nanodroplets studied by molecular dynamics simulations.

Science.gov (United States)

Ahadi, Elias; Konermann, Lars

2011-06-22

The ejection of solvated small ions from nanometer-sized droplets plays a central role during electrospray ionization (ESI). Molecular dynamics (MD) simulations can provide insights into the nanodroplet behavior. Earlier MD studies have largely focused on aqueous systems, whereas most practical ESI applications involve the use of organic cosolvents. We conduct simulations on mixed water/methanol droplets that carry excess NH(4)(+) ions. Methanol is found to compromise the H-bonding network, resulting in greatly increased rates of ion ejection and solvent evaporation. Considerable differences in the water and methanol escape rates cause time-dependent changes in droplet composition. Segregation occurs at low methanol concentration, such that layered droplets with a methanol-enriched periphery are formed. This phenomenon will enhance the partitioning of analyte molecules, with possible implications for their ESI efficiencies. Solvated ions are ejected from the tip of surface protrusions. Solvent bridging prior to ion secession is more extensive for methanol/water droplets than for purely aqueous systems. The ejection of solvated NH(4)(+) is visualized as diffusion-mediated escape from a metastable basin. The process involves thermally activated crossing of a ~30 kJ mol(-1) free energy barrier, in close agreement with the predictions of the classical ion evaporation model.

Robert T. Jones, One of a Kind

Science.gov (United States)

Vincenti, Walter G.

2005-01-01

His contemporaries saw R.T. Jones as one of the notably creative aerodynamicists of the twentieth century. This essay reviews his remarkable life and career, including his years as a farm-country boy, college dropout, and fledgling airplane designer in Missouri, his time as an elevator operator and self-directed student in Washington, D.C., and his long professional career as an aerodynamicist at the Langley and Ames Aeronautical Laboratories and Stanford University. The focus in his career is on his fundamental discovery of the benefits of sweepback for the wings of high-speed airplanes. This includes speculation about his highly intuitive thought processes in arriving at his creative ideas. I also give an account of his work on blood flow and the mechanical heart, his avocational accomplishments as a maker of telescopes and violins, and his philosophical interest in human affairs.

Molecular rotation and dynamics in superfluid helium-4 nanodroplets

Science.gov (United States)

Callegari, Carlo

2000-11-01

Cavity-enhanced laser radiation, coupled to molecular- beam bolometric detection has been used to study the spectroscopy of acetylenic molecules embedded in helium nanodroplets. The 2ν1 transition (CH stretch overtone) of HCN, DCCH, NCCCH, CH3CCH, CF3CCH, (CH 3)3CCCH, (CH3)3SiCCH, has been investigated in the 1.5 μm spectral region by means of a color center laser coupled to a resonant build-up cavity, which enhances the laser power experienced by the molecules in the beam by up to a factor of 400, thus overcoming the weakness of the (dipole forbidden) transitions. All molecules are observed to rotate freely in the liquid cluster environment, with strongly enhanced moments of inertia, but with negligible matrix induced shifts (less than 1 cm-1). We show that this enhancement is largely accounted for by hydrodynamic effects, which we have modeled and numerically calculated. While in the gas phase the rotational lines have instrument-limited widths (a few MHZ), in the droplets we have observed linewidths ranging from 600 MHz for (CH3)3SiCCH to 2.8GHz for (CH3) 3CCCH. To investigate the nature of the broadening (which was widely believed to be homogeneous), we have performed a series of infrared (IR) saturation experiments on the 2ν1 transition. We have also thoroughly investigated NCCCH by means of microwave (MW) single-resonance experiments (on rotational transitions) and double-resonance (MW-MW and MW-IR) experiments. The results demonstrate that the spectral features of molecules in He droplets are inhomogeneously broadened, and allow an estimate of the importance of the different broadening contributions. In particular, MW-IR measurements show that the size of the cluster greatly affects the way rotational energy is relaxed. Large clusters seem to follow a ``strong collision model'' where memory of the initial rotational state is completely lost after each ``relaxation'' event, while for smaller clusters relaxation rates are probably affected by the lower

Molecular rotation and dynamics in superfluid ^4He nanodroplets

Science.gov (United States)

Callegari, Carlo

2001-05-01

Cavity-enhanced laser radiation, coupled to molecular-beam bolometric detection has been used to study the spectroscopy of acetylenic molecules embedded in helium nanodroplets. The 2ν1 transition (CH stretch overtone) of HCN, DCCH, NCCCH, CH_3CCH, CF_3CCH, (CH_3)_3CCCH, (CH_3)_3SiCCH, has been investigated in the 1.5 μm spectral region by means of a color center laser coupled to a resonant buildup cavity, which enhances the laser power experienced by the molecules in the beam by up to a factor of 400, thus overcoming the weakness of the (harmonically forbidden) transitions. All molecules are observed to rotate freely in the liquid cluster environment, with strongly enhanced moments of inertia, but with negligible matrix induced shifts (less than 1 cm-1). We show that this enhancement is largely accounted for by hydrodynamic effects, which we have modeled and numerically calculated. While in the gas phase the rotational lines have instrument-limited widths (a few MHz), in the droplets we have observed linewidths ranging from 600 MHz for (CH_3)_3SiCCH to 2.8 GHz for (CH_3)_3CCCH. To investigate the nature of the broadening (which was widely believed to be homogeneous), we have performed a series of infrared (IR) saturation experiments on the 2ν1 transition. We have also thoroughly investigated NCCCH by means of microwave (MW) single-resonance experiments (on rotational transitions) and double-resonance (MW-MW and MW-IR) experiments. The results demonstrate that the spectral features of molecules in He droplets are inhomogeneously broadened, and allow an estimate of the importance of the different broadening contributions. In particular, MW-IR measurements show that the size of the cluster greatly affects the way rotational energy is relaxed. Large clusters seem to follow a ``strong collision model'' where memory of the initial rotational state is completely lost after each ``relaxation'' event, while for smaller clusters relaxation rates are probably affected by

Robin Huws Jones (United Kingdom, President 1976- 1980

Directory of Open Access Journals (Sweden)

2008-07-01

Full Text Available Robin Huws Jones, President of the International Association of Schools of Social Work from 1976 to 1980, lived a life of challenge and change. Born in Wales in 1909, he often remarked that learning to speak Welsh at age two was such a challenge that he didn’t bother to learn English until he was six. The death of his mother when he was three led to the first of many changes in a life that was not easy in the formative years. Robin remained in the care of his father while his sister became the ward of two aunts. With his father, a draper’sassistant, he left Wales to live in a crowded boarding house in Liverpool.

Mainekas teadlane soovitab Eestil enam väliskapitali ligi meelitada / Simon Jones ; interv. Aleksei Günter

Index Scriptorium Estoniae

Jones, Simon

2005-01-01

Pärnus telekommunikatsiooni- ja infofoorumil viibiv innovatsiooniekspert vastab küsimustele, mis puudutavad tema hinnangut Eesti teadus- ja arendustegevusele, tehnoloogia kasutamist sotsiaalprobleemide lahendamisel ning Eesti varustamist tasuta internetiühendusega. Lisa: Simon Jones

Heat conduction in diatomic chains with correlated disorder

Science.gov (United States)

Savin, Alexander V.; Zolotarevskiy, Vadim; Gendelman, Oleg V.

2017-01-01

The paper considers heat transport in diatomic one-dimensional lattices, containing equal amounts of particles with different masses. Ordering of the particles in the chain is governed by single correlation parameter - the probability for two neighboring particles to have the same mass. As this parameter grows from zero to unity, the structure of the chain varies from regular staggering chain to completely random configuration, and then - to very long clusters of particles with equal masses. Therefore, this correlation parameter allows a control of typical cluster size in the chain. In order to explore different regimes of the heat transport, two interatomic potentials are considered. The first one is an infinite potential wall, corresponding to instantaneous elastic collisions between the neighboring particles. In homogeneous chains such interaction leads to an anomalous heat transport. The other one is classical Lennard-Jones interatomic potential, which leads to a normal heat transport. The simulations demonstrate that the correlated disorder of the particle arrangement does not change the convergence properties of the heat conduction coefficient, but essentially modifies its value. For the collision potential, one observes essential growth of the coefficient for fixed chain length as the limit of large homogeneous clusters is approached. The thermal transport in these models remains superdiffusive. In the Lennard-Jones chain the effect of correlation appears to be not monotonous in the limit of low temperatures. This behavior stems from the competition between formation of long clusters mentioned above, and Anderson localization close to the staggering ordered state.

Interaction potentials and their effect on crystal nucleation and symmetry

International Nuclear Information System (INIS)

Hsu, C.S.; Rahman, A.

1979-01-01

Molecular dynamics technique has been used to study the effect of the interaction potential on crystal nucleation and the symmetry of the nucleated phase. Four systems, namely rubidium, Lennard-Jones, rubidium-truncated, and Lennard-Jones-truncated, have been studied each at reduced density 0.95. Two types of calculations were performed. Firstly, starting from a liquid state, each system was quenched rapidly to a reduced temperature of approx.0.1. The nucleation process for these systems was monitored by studying the time dependence of temperature and the pair correlation function, and the resulting crystalline structure analyzed using among other properties the Voronoi polyhedra. Only in the case of rubidium was a b.c.c. structure nucleated. In the other three cases we obtained a f.c.c. ordering. Secondly, we have studied the effect of changing the interaction potential in a system which has already achieved an ordered state under the action of some other potential. After establishing a b.c.c. structure in a rubidium system, the change in the symmetry of the system was studied when the pair potential was modified to one of the other three forms. The results from both types of calculations are consistent: the rubidium potential leads to a b.c.c. structure while the other three potentials give an f.c.c. structure. Metastable disordered structures were not obtained in any of the calculations. However, the time elapse between the moment when the system is quick-quenched and the moment when nucleation occurs appears to depend upon the potential of interaction

MCCE analysis of the pKas of introduced buried acids and bases in staphylococcal nuclease.

Science.gov (United States)

Gunner, M R; Zhu, Xuyu; Klein, Max C

2011-12-01

The pK(a)s of 96 acids and bases introduced into buried sites in the staphylococcal nuclease protein (SNase) were calculated using the multiconformation continuum electrostatics (MCCE) program and the results compared with experimental values. The pK(a)s are obtained by Monte Carlo sampling of coupled side chain protonation and position as a function of pH. The dependence of the results on the protein dielectric constant (ε(prot)) in the continuum electrostatics analysis and on the Lennard-Jones non-electrostatics parameters was evaluated. The pK(a)s of the introduced residues have a clear dependence on ε(prot,) whereas native ionizable residues do not. The native residues have electrostatic interactions with other residues in the protein favoring ionization, which are larger than the desolvation penalty favoring the neutral state. Increasing ε(prot) scales both terms, which for these residues leads to small changes in pK(a). The introduced residues have a larger desolvation penalty and negligible interactions with residues in the protein. For these residues, changing ε(prot) has a large influence on the calculated pK(a). An ε(prot) of 8-10 and a Lennard-Jones scaling of 0.25 is best here. The X-ray crystal structures of the mutated proteins are found to provide somewhat better results than calculations carried out on mutations made in silico. Initial relaxation of the in silico mutations by Gromacs and extensive side chain rotamer sampling within MCCE can significantly improve the match with experiment. Copyright © 2011 Wiley-Liss, Inc.

Avaliação radiográfica dos efeitos do aparelho Jones Jig nas distalizações intra-bucais: um estudo piloto Radiographic evaluation of the effects of Jones Jig appliance in intrabuccal distalizations: a pilot study

Directory of Open Access Journals (Sweden)

Juliana Maria Monteiro de Oliveira

2004-10-01

Full Text Available Na Classe II dentária, aparelhos extra ou intra-bucais são utilizados na distalização dos molares superiores, sendo que o dispositivo extra-bucal, apesar de ser eficiente, apresenta uma série de inconvenientes, destacando-se entre eles, a necessidade de cooperação do paciente. Em virtude da total dependência da colaboração e aceitação do paciente, aparelhos alternativos intra-bucais foram sendo criados, promovendo assim, um maior controle do tratamento por parte do profissional. Dentre esses aparelhos, destaca-se o Jones Jig. Foram selecionados para a pesquisa seis pacientes, com idades compreendidas entre 12 a 18 anos, que apresentavam um padrão esquelético de Classe I ou Classe II suave, vertical normal e má oclusão de Classe II dentária. Esses pacientes utilizaram o Jones Jig numa primeira fase do tratamento ortodôntico. Radiografias laterais cefalométricas foram obtidas antes e após o tratamento com o Jones Jig e a partir delas, traçados cefalométricos foram feitos para obter medidas de tecidos moles, esqueléticas e dentárias. Os resultados encontrados foram determinados, comparando-se as medidas do pré e do pós-tratamento. A fim de avaliar a significância estatística desses resultados, utilizou-se o teste de Wilcoxon. A ocorrência de uma inclinação distal dos primeiros e segundos molares superiores foi a única alteração estatisticamente significante encontrada.In dental Class II relationship, extra or intrabuccal appliances are used during the upper molars distalization. The extrabuccal appliance, although to be efficient, present many inconveniences, such as the patient compliance. For these reasons, alternative intrabuccal appliances were created in order to get more control during the treatment of no compliances patients. One of these appliances is the Jones Jig. Six patients, as standard as possible, were selected for this research, with the age ranged from 12 to 18 years old. These patients shown a

Role of attractive forces in determining the equilibrium structure and dynamics of simple liquids

DEFF Research Database (Denmark)

Toxværd, Søren

2015-01-01

Molecular Dynamics simulations of a Lennard-Jones system with different range of attraction show that the attractive forces modify the radial distribution of the particles. For condensed liquids only, the forces within the the first coordination shell (FCS) are important, but for gases and moderate...... condensed fluids, even the attractive forces outside the FCS play a role. The changes in the distribution caused by neglecting the attractive forces, lead to a too high pressure. The weak long-range attractions damp the dynamics and the diffusion of the particles in gas-, super critical fluid- and in liquid...

Nucleation and droplet growth from supersaturated vapor at temperatures below the triple point temperature

DEFF Research Database (Denmark)

Toxværd, Søren

2016-01-01

temperature Ttr.p. crystallizes via a liquid droplet is an example of Ostwald's step rule. The homogeneous nucleation in the supersaturated gas is not to a crystal, but to a liquid-like critical nucleus. We have for the first time performed constant energy (NVE) Molecular Dynamics (MD) of homogeneous...... nucleation without the use of a thermostat. The simulations of homogeneous nucleation in a Lennard-Jones system from supersaturated vapor at temperatures below Ttr.p. reveals that the nucleation to a liquid-like critical nucleus is initiated by a small cold cluster [S. Toxvaerd, J. Chem. Phys. \\textbf{143...

Time-dependent friction and solvation time correlation function

International Nuclear Information System (INIS)

Samanta, Alok; Ali, Sk Musharaf; Ghosh, Swapan K

2005-01-01

We have derived a new relation between the time-dependent friction and solvation time correlation function (STCF) for non-polar fluids. The friction values calculated using this relation and simulation results on STCF for a Lennard-Jones fluid are shown to have excellent agreement with the same obtained through mode-coupling theory. Also derived is a relation between the time-dependent dielectric friction and STCF for polar fluids. Routes are thus provided to obtain the time-dependent friction (non-polar as well as dielectric) from an experimentally measured quantity like STCF, even if the interparticle interaction potential is not known

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.

Phase equilibria of binary mixtures by molecular simulation and cubic equations of state

Directory of Open Access Journals (Sweden)

Cabral V.F.

2001-01-01

Full Text Available Molecular simulation data were used to study the performance of equations of state (EoS and combining rules usually employed in thermodynamic property calculations. The Monte Carlo method and the Gibbs ensemble technique were used for determining composition and densities of vapor and liquid phases in equilibrium for binary mixtures of Lennard-Jones fluids. Simulation results are compared to data in the literature and to those calculated by the t-PR-LJ EoS. The use of adequate combining rules has been shown to be very important for the satisfactory representation of molecular simulation data.

Markov state modeling and dynamical coarse-graining via discrete relaxation path sampling.

Science.gov (United States)

Fačkovec, B; Vanden-Eijnden, E; Wales, D J

2015-07-28

A method is derived to coarse-grain the dynamics of complex molecular systems to a Markov jump process (MJP) describing how the system jumps between cells that fully partition its state space. The main inputs are relaxation times for each pair of cells, which are shown to be robust with respect to positioning of the cell boundaries. These relaxation times can be calculated via molecular dynamics simulations performed in each cell separately and are used in an efficient estimator for the rate matrix of the MJP. The method is illustrated through applications to Sinai billiards and a cluster of Lennard-Jones discs.

Similarity Laws for the Lines of Ideal Free Energy and Chemical Potential in Supercritical Fluids.

Science.gov (United States)

Apfelbaum, E M; Vorob'ev, V S

2017-09-21

We have found the curves on the density-temperature plane, along which the values of free energy and chemical potential correspond to ideal gas quantities. At first, we have applied the van der Waals equation to construct them and to derive their equations. Then we have shown that the same lines for real substances (Ar, N 2 , CH 4 , SF 6 , H 2 , H 2 O) and for the model Lennard-Jones system constructed on the basis of the measurements data and calculations are well matched with the derived equations. The validity and deviations from the obtained similarity laws are discussed.

Experimental studies of the NaRb ground-state potential up to the v''=76 level

International Nuclear Information System (INIS)

Docenko, O.; Nikolayeva, O.; Tamanis, M.; Ferber, R.; Pazyuk, E.A.; Stolyarov, A.V.

2002-01-01

Laser induced fluorescence spectra of the C 1 Σ + -X 1 Σ + system of 23 Na 85 Rb and 23 Na 87 Rb have allowed vibrational levels of the electronic ground state up to v '' =76, spanning 99.85% of the potential well to be observed. The ground-state term values have been fitted to a Dunham polynomial expansion, and also to a direct modified Lennard-Jones (MLJ) potential. The analytical MLJ construction allowed us to match previous measured term values for v '' ≤30 with long-range behavior of the potential through the intermediate internuclear distance region covered by the present investigation

Calculations on isotope separation by laser induced photodissociation of polyatomic molecules. Progress report, February 1, 1977--June 30, 1978

International Nuclear Information System (INIS)

Lamb, W.E. Jr.

1978-07-01

The molecule SF 6 is treated as a classical dynamical system obeying Newton's laws of motion. This report describes how the current SF 6 potential is determined. The initial approach is described in terms of a pair of Lennard--Jones potential functions with arbitrary coefficients. A method for determining the potential constants is developed. The SF 6 spectrum was reproduced by including three-body forces. By specifying certain parameters such as the 1/r 6 F-F constant and the total dissociation energy of the molecule, a satisfactory global potential was obtained. The laser-molecule interaction energy was developed

On the sighting of unicorns: A variational approach to computing invariant sets in dynamical systems

Science.gov (United States)

Junge, Oliver; Kevrekidis, Ioannis G.

2017-06-01

We propose to compute approximations to invariant sets in dynamical systems by minimizing an appropriate distance between a suitably selected finite set of points and its image under the dynamics. We demonstrate, through computational experiments, that this approach can successfully converge to approximations of (maximal) invariant sets of arbitrary topology, dimension, and stability, such as, e.g., saddle type invariant sets with complicated dynamics. We further propose to extend this approach by adding a Lennard-Jones type potential term to the objective function, which yields more evenly distributed approximating finite point sets, and illustrate the procedure through corresponding numerical experiments.

Capillary condensation in pores with rough walls: a density functional approach.

Science.gov (United States)

Bryk, P; Rzysko, W; Malijevsky, Al; Sokołowski, S

2007-09-01

The effect of surface roughness of slit-like pore walls on the capillary condensation of a spherical particles and short chains is studied. The gas molecules interact with the substrate by a Lennard-Jones (9,3) potential. The rough layer at each pore wall has a variable thickness and density and consists of a disordered quenched matrix of spherical particles. The system is described in the framework of a density functional approach and using computer simulations. The contribution due to attractive van der Waals interactions between adsorbate molecules is described by using first-order mean spherical approximation and mean-field approximation.

Theoretical Assessment of Compressibility Factor of Gases by Using Second Virial Coefficient

Science.gov (United States)

Mamedov, Bahtiyar A.; Somuncu, Elif; Askerov, Iskender M.

2018-01-01

We present a new analytical approximation for determining the compressibility factor of real gases at various temperature values. This algorithm is suitable for the accurate evaluation of the compressibility factor using the second virial coefficient with a Lennard-Jones (12-6) potential. Numerical examples are presented for the gases H2, N2, He, CO2, CH4 and air, and the results are compared with other studies in the literature. Our results showed good agreement with the data in the literature. The consistency of the results demonstrates the effectiveness of our analytical approximation for real gases.

Identifying Structural Flow Defects in Disordered Solids Using Machine-Learning Methods

Science.gov (United States)

Cubuk, E. D.; Schoenholz, S. S.; Rieser, J. M.; Malone, B. D.; Rottler, J.; Durian, D. J.; Kaxiras, E.; Liu, A. J.

2015-03-01

We use machine-learning methods on local structure to identify flow defects—or particles susceptible to rearrangement—in jammed and glassy systems. We apply this method successfully to two very different systems: a two-dimensional experimental realization of a granular pillar under compression and a Lennard-Jones glass in both two and three dimensions above and below its glass transition temperature. We also identify characteristics of flow defects that differentiate them from the rest of the sample. Our results show it is possible to discern subtle structural features responsible for heterogeneous dynamics observed across a broad range of disordered materials.

Cluster structures influenced by interaction with a surface.

Science.gov (United States)

Witt, Christopher; Dieterich, Johannes M; Hartke, Bernd

2018-05-30

Clusters on surfaces are vitally important for nanotechnological applications. Clearly, cluster-surface interactions heavily influence the preferred cluster structures, compared to clusters in vacuum. Nevertheless, systematic explorations and an in-depth understanding of these interactions and how they determine the cluster structures are still lacking. Here we present an extension of our well-established non-deterministic global optimization package OGOLEM from isolated clusters to clusters on surfaces. Applying this approach to intentionally simple Lennard-Jones test systems, we produce a first systematic exploration that relates changes in cluster-surface interactions to resulting changes in adsorbed cluster structures.

Oscillations of spherical fullerenes interacting with graphene sheet

Energy Technology Data Exchange (ETDEWEB)

Ghavanloo, Esmaeal, E-mail: ghavanloo@shirazu.ac.ir; Fazelzadeh, S. Ahmad

2017-01-01

In the present study, the oscillations of spherical fullerenes in the vicinity of a fully constrained graphene sheet are investigated. Using the continuous approximation and Lennard-Jones potential, the van der Waals (vdW) potential energy and interaction forces are obtained. The equation of motion is derived and directly solved based on the actual force distribution between the fullerene molecules and the graphene sheet. Numerical results are obtained and shown that the oscillation is sensitive to the size of the fullerene as well as the distance between the center of the fullerene and the graphene sheet.

Cluster growing process and a sequence of magic numbers

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2003-01-01

demonstrate that in this way all known global minimum structures of the Lennard-Jones (LJ) clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence for the clusters of noble gas atoms......We present a new theoretical framework for modeling the cluster growing process. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system, and absorbing its energy at each step, we find cluster growing paths up to the cluster sizes of more than 100 atoms. We...

A new shared-memory programming paradigm for molecular dynamics simulations on the Intel Paragon

International Nuclear Information System (INIS)

D'Azevedo, E.F.; Romine, C.H.

1994-12-01

This report describes the use of shared memory emulation with DOLIB (Distributed Object Library) to simplify parallel programming on the Intel Paragon. A molecular dynamics application is used as an example to illustrate the use of the DOLIB shared memory library. SOTON-PAR, a parallel molecular dynamics code with explicit message-passing using a Lennard-Jones 6-12 potential, is rewritten using DOLIB primitives. The resulting code has no explicit message primitives and resembles a serial code. The new code can perform dynamic load balancing and achieves better performance than the original parallel code with explicit message-passing

Um modelo para a superfície líquida no estudo da dinâmica do espalhamento de Xe e Ne pelo esqualano

Directory of Open Access Journals (Sweden)

Leal Alexandre S.

2004-01-01

Full Text Available In this work we present a theoretical model to investigate the scattering of Xe and Ne by a liquid squalane surface. The liquid surface is modeled as a grid of harmonic oscillators with frequencies adjusted to experimental vibration as frequencies of the liquid squalane and the atom-surface interaction potential is modeled by a Lennard-Jones function. The three dimensional description of the dynamics of the process which occurs at the gas-liquid interface is obtained by the classical trajectory method. The general characteristics of the dynamics of the scattering process are in good agreement with experimental data.

Butterflies (Lepidoptera: Papilionoidea and Hesperoidea) and other protected fauna of Jones Estate, a dying watershed in the Kumaon Himalaya, Uttarakhand, India

OpenAIRE

P. Smetacek

2012-01-01

Two hundred and forty three species of butterflies recorded from Jones Estate, Uttarakhand between 1951 and 2010 are reported. The ongoing rapid urbanization of Jones Estate micro-watershed will destroy the habitat of 49 species of wildlife protected under Indian law, as well as several species of narrow endemic moths and butterflies. The only known Indian habitat for the butterfly Lister’s Hairstreak Pamela dudgeoni will be destroyed. The effect on the water flow of both the Bhimtal and Sa...

Molecular dynamics of nanodroplet impact: The effect of the projectile’s molecular mass on sputtering

Energy Technology Data Exchange (ETDEWEB)

Saiz, Fernan [Department of Chemistry, Imperial College of Science, Technology and Medicine, South Kensington, London, SW7 2A7 (United Kingdom); Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu [Department of Mechanical and Aerospace Engineering, University of California, Irvine, California, 92697 (United States)

2016-06-15

The impact of electrosprayed nanodroplets on ceramics at several km/s alters the atomic order of the target, causing sputtering, surface amorphization and cratering. The molecular mass of the projectile is known to have a strong effect on the impact phenomenology, and this article aims to rationalize this dependency using molecular dynamics. To achieve this goal, the article models the impact of four projectiles with molecular masses between 45 and 391 amu, and identical diameters and kinetic energies, 10 nm and 63 keV, striking a silicon target. In agreement with experiments, the simulations show that the number of sputtered atoms strongly increases with molecular mass. This is due to the increasing intensity of collision cascades with molecular mass: when the fixed kinetic energy of the projectile is distributed among fewer, more massive molecules, their collisions with the target produce knock-on atoms with higher energies, which in turn generate more energetic and larger numbers of secondary and tertiary knock-on atoms. The more energetic collision cascades intensify both knock-on sputtering and, upon thermalization, thermal sputtering. Besides enhancing sputtering, heavier molecules also increase the fraction of the projectile’s energy that is transferred to the target, as well as the fraction of this energy that is dissipated.

Molecular dynamics of nanodroplet impact: The effect of the projectile’s molecular mass on sputtering

International Nuclear Information System (INIS)

Saiz, Fernan; Gamero-Castaño, Manuel

2016-01-01

The impact of electrosprayed nanodroplets on ceramics at several km/s alters the atomic order of the target, causing sputtering, surface amorphization and cratering. The molecular mass of the projectile is known to have a strong effect on the impact phenomenology, and this article aims to rationalize this dependency using molecular dynamics. To achieve this goal, the article models the impact of four projectiles with molecular masses between 45 and 391 amu, and identical diameters and kinetic energies, 10 nm and 63 keV, striking a silicon target. In agreement with experiments, the simulations show that the number of sputtered atoms strongly increases with molecular mass. This is due to the increasing intensity of collision cascades with molecular mass: when the fixed kinetic energy of the projectile is distributed among fewer, more massive molecules, their collisions with the target produce knock-on atoms with higher energies, which in turn generate more energetic and larger numbers of secondary and tertiary knock-on atoms. The more energetic collision cascades intensify both knock-on sputtering and, upon thermalization, thermal sputtering. Besides enhancing sputtering, heavier molecules also increase the fraction of the projectile’s energy that is transferred to the target, as well as the fraction of this energy that is dissipated.

Lennard–Jones interactions between nano-rod like particles at an arbitrary orientation and an infinite flat solid surface

International Nuclear Information System (INIS)

Hamady, Saleem; Hijazi, Abbas; Atwi, Ali

2013-01-01

An analytical expression for the Lennard–Jones interaction between nano-rods and an infinite flat solid surface is presented. Starting from the elementary Lennard–Jones interaction between two particles, and taking the shape of the nano-rod to be a filled cylinder of radius r and length L, the obtained expression was valid for arbitrary orientation of the nano-rod at variable elevation from the surface. By differentiating the potential with respect to the orientation and elevation we were able to extract the torque and force, respectively, exerted on the nano-rods when approaching a flat surface. The derivation is subjected to the assumption of additivity and approximated for some limiting case

The Game TV Plays: Or, Why an English Teacher Came to Hate Barnaby Jones.

Science.gov (United States)

Shaw, Patrick W.

The message of current popular television shows in which the hero is, or appears to be, a dumb clod (e.g., Archie Bunker, Fred Sanford, Columbo, and Barnaby Jones), apparently is that corruption may be equated with articulation, wealth, and education, while virtue may be equated with poverty and, often, illiteracy. Unfortunately, the effect of…

Molecular Simulation of the Vapor-Liquid Phase Behavior of Lennard-Jones Mixtures in Porous Solids

Science.gov (United States)

2006-09-01

sur la Catalyse, Centre National de la Recherche Scientifique, Group de Chimie Theorique, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex, France...and Group de Chimie Theorique, Ecole Normale Superieure de Lyon, 46 Allee d’Italie, 69364 Lyon, Cedex 07, France 14. ABSTRACT We present vapor...Scientifique, Group de Chimie Theorique, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex, France and Group de Chimie Theorique, Ecole Normale

75 FR 43563 - Dow Jones & Company, Sharon Pennsylvania Print Plant a Subsidiary of News Corporation, West...

Science.gov (United States)

2010-07-26

..., Sharon Pennsylvania Print Plant a Subsidiary of News Corporation, West Middlesex, Pennsylvania; Notice of..., Sharon Pennsylvania Print Plant, a subsidiary of News Corporation, West Middlesex, Pennsylvania, was... between Dow Jones & Company, West Middlesex, Pennsylvania, and any Konica facility. The petitioner did not...

Lake Holocene Use of Wetland Habitats in Central California: A Reply to Jones

OpenAIRE

Hildebrandt, William R

1997-01-01

In this volume, Terry Jones (1997) provided a thorough critique of my summary (also in this volume [Hildebrandt 1977a]) of prehistoric hunter- gatherer adaptations in the southern Santa Clara Valley, California (also see Hildebrandt and Mikkelsen 1993). His review identified a variety of issues that warrant additional consideration, particularly those pertaining to settlement chronology, paleoenvironmental change, and Late Holocene subsistence intensification. I appreciate his comments, as my...

77 FR 59899 - Proposed Information Collection; Comment Request; Coastal Zone Management Act Walter B. Jones and...

Science.gov (United States)

2012-10-01

... Collection; Comment Request; Coastal Zone Management Act Walter B. Jones and NOAA Excellence Awards AGENCY... approved information collection. The 1990 reauthorization of the Coastal Zone Management Act (CZMA) authorized an awards program to ``implement a program to promote excellence in coastal zone management by...

Butterflies (Lepidoptera: Papilionoidea and Hesperoidea and other protected fauna of Jones Estate, a dying watershed in the Kumaon Himalaya, Uttarakhand, India

Directory of Open Access Journals (Sweden)

P. Smetacek

2012-08-01

Full Text Available Two hundred and forty three species of butterflies recorded from Jones Estate, Uttarakhand between 1951 and 2010 are reported. The ongoing rapid urbanization of Jones Estate micro-watershed will destroy the habitat of 49 species of wildlife protected under Indian law, as well as several species of narrow endemic moths and butterflies. The only known Indian habitat for the butterfly Lister’s Hairstreak Pamela dudgeoni will be destroyed. The effect on the water flow of both the Bhimtal and Sattal lake systems will clearly be adverse, as is evident from the drying up of Kua Tal and the reduced flow of perennial water springs during the dry season on the Estate. The undoubtedly negative effect of urbanization on these valuable fresh water resources will be irreversible in the long term. The trend can be reversed by extending protection to Jones Estate by re-declaring it a Green Belt of Bhimtal and by banning construction in the catchment area of Bhimtal lake, as has been done in Nainital and Mussoorie, both in Uttarakhand.

A density functional theory study of magneto-electric Jones birefringence of noble gases, furan homologues, and mono-substituted benzenes

International Nuclear Information System (INIS)

Fahleson, Tobias; Norman, Patrick; Coriani, Sonia; Rizzo, Antonio; Rikken, Geert L. J. A.

2013-01-01

We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analytic linear and nonlinear response functions in the framework of time-dependent density functional theory. A correlation is made between the observable (the Jones constant) and the atomic radius for noble gases, or the permanent electric dipole and a structure/chemical reactivity descriptor as the para Hammett constant for substituted benzenes

How long the singular value decomposed entropy predicts the stock market? - Evidence from the Dow Jones Industrial Average Index

Science.gov (United States)

Gu, Rongbao; Shao, Yanmin

2016-07-01

In this paper, a new concept of multi-scales singular value decomposition entropy based on DCCA cross correlation analysis is proposed and its predictive power for the Dow Jones Industrial Average Index is studied. Using Granger causality analysis with different time scales, it is found that, the singular value decomposition entropy has predictive power for the Dow Jones Industrial Average Index for period less than one month, but not for more than one month. This shows how long the singular value decomposition entropy predicts the stock market that extends Caraiani's result obtained in Caraiani (2014). On the other hand, the result also shows an essential characteristic of stock market as a chaotic dynamic system.

Surface Weather Observations Log Sheets from the USS John Paul Jones, April 12 - 23, 2004 (NODC Accession 0001512)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Meteorological data were collected using meteorological sensors from the USS JOHN PAUL JONES in the Northeast Pacific Ocean. Data were collected and recorded into...

Strategic Analysis and Associated Management Products Supporting the Reengineering of Bayne-Jones Army Community Hospital: Consultative Products and Findings

National Research Council Canada - National Science Library

Fulton, Larry

1998-01-01

.... ̂Product 2 - "Bayne-Jones Army Community Hospital Web Site," a strategic Internet web site for marketing health and wellness, the TRICARE medical network, the Joint Readiness Training Center Surgeon's...

Thermodynamical Properties of the Solidified Rare Gases

Energy Technology Data Exchange (ETDEWEB)

Ebbsjoe, I

1971-12-15

Lattice parameter, isothermal bulk modulus and specific heat at constant volume are calculated from Helmholtz free energy for solid Ne, Ar, Kr and Xe. The lattice potential energy is expanded to the fourth order in the nuclear displacements. A perturbation treatment in the quasi harmonic approximation of the partition function includes the cubic anharmonic term to second order and the quartic to first order. Detailed numerical calculations are presented for two interatomic pair potentials, the Lennard-Jones (12,6) and the (exp,a,6). The three nearest neighbours have been taken into account. It is shown that earlier nearest neighbour calculations exaggerate the breakdown of the theory at higher temperatures

Computer simulation of the thermal pressure in solids and the equation of state

International Nuclear Information System (INIS)

Welch, D.O.; Dienes, G.J.; Paskin, A.

1976-01-01

The equation of state of solids was investigated with molecular dynamics techniques by obtaining the pressure as a function of temperature over a wide range of compressions. Data were obtained for fcc crystals with Lennard--Jones interactions and for bcc crystals with Morse interactions. The results were analyzed in terms of the Mie--Gruneisen equation of state. The Gruneisen constant at zero temperature is found to be essentially that obtained from the volume dependence of the mean-squared lattice vibration frequency, and its temperature dependence can be approximated well with a self-consistent cell model. Calculated results are compared with experimental data for argon along the melting line

Layered interfaces between immiscible liquids studied by density-functional theory and molecular-dynamics simulations.

Science.gov (United States)

Geysermans, P; Elyeznasni, N; Russier, V

2005-11-22

We present a study of the structure in the interface between two immiscible liquids by density-functional theory and molecular-dynamics calculations. The liquids are modeled by Lennard-Jones potentials, which achieve immiscibility by suppressing the attractive interaction between unlike particles. The density profiles of the liquids display oscillations only in a limited part of the simple liquid-phase diagram (rho,T). When approaching the liquid-vapor coexistence, a significant depletion appears while the layering behavior of the density profile vanishes. By analogy with the liquid-vapor interface and the analysis of the adsorption this behavior is suggested to be strongly related to the drying transition.

Classically exact surface diffusion constants at arbitrary temperature

International Nuclear Information System (INIS)

Voter, A.F.; Cohen, J.M.

1989-01-01

An expression is presented for computing the classical diffusion constant of a point defect (e.g., an adatom) in an infinite lattice of binding sites at arbitrary temperature. The transition state theory diffusion constant is simply multiplied by a dynamical correction factor that is computed from short-time classical trajectories initiated at the site boundaries. The time scale limitations of direct molecular dynamics are thus avoided in the low- and middle-temperature regimes. The expression results from taking the time derivative of the particle mean-square displacement in the lattice-discretized coordinate system. Applications are presented for surface diffusion on fcc(100) and fcc(111) Lennard-Jones crystal faces

Effect of pairwise additivity on finite-temperature behavior of classical ideal gas

Science.gov (United States)

Shekaari, Ashkan; Jafari, Mahmoud

2018-05-01

Finite-temperature molecular dynamics simulations have been applied to inquire into the effect of pairwise additivity on the behavior of classical ideal gas within the temperature range of T = 250-4000 K via applying a variety of pair potentials and then examining the temperature dependence of a number of thermodynamical properties. Examining the compressibility factor reveals the most deviation from ideal-gas behavior for the Lennard-Jones system mainly due to the presence of both the attractive and repulsive terms. The systems with either attractive or repulsive intermolecular potentials are found to present no resemblance to real gases, but the most similarity to the ideal one as temperature rises.

Molecular Dynamics Simulation for the Mechanical Properties of CNT/Polymer Nanocomposites

International Nuclear Information System (INIS)

Yang, Seung Hwa; Cho, Maeg Hyo

2007-01-01

In order to obtain mechanical properties of CNT/Polymer nano-composites, molecular dynamics simulation is performed. Overall system was modeled as a flexible unit cell in which carbon nanotubes are embedded into a polyethylene matrix for N σ T ensemble simulation. COMPASS force field was chosen to describe inter and intra molecular potential and bulk effect was achieved via periodic boundary conditions. In CNT-polymer interface, only Lennard-Jones non-bond potential was considered. Using Parrinello-Rahman fluctuation method, mechanical properties of orthotropic nano-composites under various temperatures were successfully obtained. Also, we investigated thermal behavior of the short CNT reinforced nanocomposites system with predicting glass transition temperature

Exploring the free energy surfaces of clusters using reconnaissance metadynamics

Science.gov (United States)

Tribello, Gareth A.; Cuny, Jérôme; Eshet, Hagai; Parrinello, Michele

2011-09-01

A new approach is proposed for exploring the low-energy structures of small to medium-sized aggregates of atoms and molecules. This approach uses the recently proposed reconnaissance metadynamics method [G. A. Tribello, M. Ceriotti, and M. Parrinello. Proc. Natl. Acad. Sci. U.S.A. 107(41), 17509 (2010), 10.1073/pnas.1011511107] in tandem with collective variables that describe the average structure of the coordination sphere around the atoms/molecules. We demonstrate this method on both Lennard-Jones and water clusters and show how it is able to quickly find the global minimum in the potential energy surface, while exploring the finite temperature free energy surface.

Note: Nonpolar solute partial molar volume response to attractive interactions with water

Energy Technology Data Exchange (ETDEWEB)

Williams, Steven M.; Ashbaugh, Henry S., E-mail: hanka@tulane.edu [Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118 (United States)

2014-01-07

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size.

Algebraic relaxation of a time correlation function

International Nuclear Information System (INIS)

Srivastava, S.; Kumar, C.N.; Tankeshwar, K.

2004-06-01

A second order non-linear differential equation obtained from Mori's integro- differential equation is shown to transform to another form which provides algebraic decay to a time correlation function. Involved parameters in algebraic formula are related to exact properties of the corresponding correlation function. The model has been used to study a sol-gel system which is known, experimentally, to exhibit a power law decay to stress auto-correlation function. The expression obtained for the viscosity shows a logarithmic divergence at some critical value of the parameter. Some features of the model have also been tested using available information about Lennard-Jones fluids. (author)

Isomorphs in the phase diagram of a model liquid without inverse power law repulsion

DEFF Research Database (Denmark)

Veldhorst, Arnold Adriaan; Bøhling, Lasse; Dyre, J. C.

2012-01-01

scattering function are calculated. The results are shown to reflect a hidden scale invariance; despite its exponential repulsion the Buckingham potential is well approximated by an inverse power-law plus a linear term in the region of the first peak of the radial distribution function. As a consequence...... the dynamics of the viscous Buckingham liquid is mimicked by a corresponding model with purely repulsive inverse-power-law interactions. The results presented here closely resemble earlier results for Lennard-Jones type liquids, demonstrating that the existence of strong correlations and isomorphs does...... not depend critically on the mathematical form of the repulsion being an inverse power law....

Exponential and Bessel fitting methods for the numerical solution of the Schroedinger equation

International Nuclear Information System (INIS)

Raptis, A.D.; Cash, J.R.

1987-01-01

A new method is developed for the numerical integration of the one dimensional radial Schroedinger equation. This method involves using different integration formulae in different parts of the range of integration rather than using the same integration formula throughout. Two new integration formulae are derived, one which integrates Bessel and Neumann functions exactly and another which exactly integrates certain exponential functions. It is shown that, for large r, these new formulae are much more accurate than standard integration methods for the Schroedinger equation. The benefit of using this new approach is demonstrated by considering some numerical examples based on the Lennard-Jones potential. (orig.)

Molecular dynamics of contact behavior of self-assembled monolayers on gold using nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Fang, Te-Hua [Institute of Mechanical and Electromechanical Engineering National Formosa University, Yunlin 632, Taiwan (China); Chang, Win-Jin, E-mail: changwj@mail.ksu.edu.tw [Department of Mechanical Engineering Kun Shan University, Tainan 710, Taiwan (China); Fan, Yu-Cheng [Institute of Mechanical and Electromechanical Engineering National Formosa University, Yunlin 632, Taiwan (China); Weng, Cheng-I [Department of Mechanical Engineering National Cheng Kung University, Tainan, 710, Taiwan (China)

2009-08-15

Molecular dynamics simulation is used to study nanoindentation of the self-assembled monolayers (SAMs) on an Au surface. The interaction of SAM atoms is described by a general universal force field (UFF), the tight-binding second-moment approximation (TB-SMA) is used for Au substrate, and the Lennard-Jones potential function is employed to describe interaction among the indenter, the SAMs, and the Au substrate atoms. The model consists of a planar Au substrate with n-hexadecanethiol SAM chemisorbed to the substrate. The simulation results show that the contact pressure increases as the SAMs temperature increases. In addition, the contact pressure also increases as the depth and velocity of indentation increase.

Molecular dynamics of contact behavior of self-assembled monolayers on gold using nanoindentation

International Nuclear Information System (INIS)

Fang, Te-Hua; Chang, Win-Jin; Fan, Yu-Cheng; Weng, Cheng-I

2009-01-01

Molecular dynamics simulation is used to study nanoindentation of the self-assembled monolayers (SAMs) on an Au surface. The interaction of SAM atoms is described by a general universal force field (UFF), the tight-binding second-moment approximation (TB-SMA) is used for Au substrate, and the Lennard-Jones potential function is employed to describe interaction among the indenter, the SAMs, and the Au substrate atoms. The model consists of a planar Au substrate with n-hexadecanethiol SAM chemisorbed to the substrate. The simulation results show that the contact pressure increases as the SAMs temperature increases. In addition, the contact pressure also increases as the depth and velocity of indentation increase.

Recasting a model atomistic glassformer as a system of icosahedra

Energy Technology Data Exchange (ETDEWEB)

Pinney, Rhiannon [HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Bristol Centre for Complexity Science, University of Bristol, Bristol BS8 1TS (United Kingdom); Liverpool, Tanniemola B. [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Royall, C. Patrick, E-mail: paddy.royall@bristol.ac.uk [HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); School of Chemistry, University of Bristol, Cantock Close, Bristol BS8 1TS (United Kingdom); Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol BS8 1FD (United Kingdom)

2015-12-28

We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics are correlated with the formation of icosahedral structures. Upon cooling, these icosahedra organize into mesoclusters. We recast this glassformer as an effective system of icosahedra which we describe with a population dynamics model. This model we parameterize with data from the temperature regime accessible to molecular dynamics simulations. We then use the model to determine the population of icosahedra in mesoclusters at arbitrary temperature. Using simulation data to incorporate dynamics into the model, we predict relaxation behavior at temperatures inaccessible to conventional approaches. Our model predicts super-Arrhenius dynamics whose relaxation time remains finite for non-zero temperature.

Bridging scales from molecular simulations to classical thermodynamics: density functional theory of capillary condensation in nanopores

International Nuclear Information System (INIS)

Neimark, Alexander V; Ravikovitch, Peter I; Vishnyakov, Aleksey

2003-01-01

With the example of the capillary condensation of Lennard-Jones fluid in nanopores ranging from 1 to 10 nm, we show that the non-local density functional theory (NLDFT) with properly chosen parameters of intermolecular interactions bridges the scale gap from molecular simulations to macroscopic thermodynamics. On the one hand, NLDFT correctly approximates the results of Monte Carlo simulations (shift of vapour-liquid equilibrium, spinodals, density profiles, adsorption isotherms) for pores wider than about 2 nm. On the other hand, NLDFT smoothly merges (above 7-10 nm) with the Derjaguin-Broekhoff-de Boer equations which represent augmented Laplace-Kelvin equations of capillary condensation and desorption

Modulation of capillary condensation by trace component

Directory of Open Access Journals (Sweden)

Shiqi Zhou

2011-06-01

Full Text Available Impact of trace component on capillary condensation (CC is investigated systematically using a classical density functional theory. It is discovered that (i presence of the trace component makes the CC to occur at much lower condensation pressure than when its absence; (ii Lennard-Jones potential parameters like size parameter and energy parameter of the trace component, and its concentration in the bulk adsorption system, show their effects the most remarkably within a particular range beyond which the effects eventually become insignificant. The present discoveries have implications in low pressure storage of gases, separation and enrichment of low concentration component, and easy control of CC transition, etc.

Argon line broadening by neutral atoms and application to the measurement of oscillator strengths of AI resonance lines

International Nuclear Information System (INIS)

Vallee, O.; Ranson, P.; Chapelle, J.

1977-01-01

AI line broadening was studied from collisions between neutral argon atoms (3p 5 4p-3p 5 4s transitions) in a weakly ionised plasma jet (neutral atoms temperature T 0 approximately 4000K, electrons temperature Tsub(e) approximately 6000K, electronic density Nsub(e) 15 cm -3 , ionisation rate α -4 , and pressure range from 1 to 3 kg/cm 2 ). A satisfactory description of Van der Waals broadened lines is obtained by means of a Lennard-Jones potential. Measurement of line widths whose corresponding transitions occur on resonant levels, gives with relatively good accuracy the oscillator strength of the argon resonance lines [fr

Note: Nonpolar solute partial molar volume response to attractive interactions with water.

Science.gov (United States)

Williams, Steven M; Ashbaugh, Henry S

2014-01-07

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size.

Free energy evaluation in polymer translocation via Jarzynski equality

Energy Technology Data Exchange (ETDEWEB)

Mondaini, Felipe, E-mail: fmondaini@if.ufrj.br [Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Petrópolis, 25.620-003, RJ (Brazil); Moriconi, L., E-mail: moriconi@if.ufrj.br [Instituto de Física, Universidade Federal do Rio de Janeiro, C.P. 68528, 21945-970, Rio de Janeiro, RJ (Brazil)

2014-05-01

We perform, with the help of cloud computing resources, extensive Langevin simulations, which provide free energy estimates for unbiased three-dimensional polymer translocation. We employ the Jarzynski equality in its rigorous setting, to compute the variation of the free energy in single monomer translocation events. In our three-dimensional Langevin simulations, the excluded-volume and van der Waals interactions between beads (monomers and membrane atoms) are modeled through a repulsive Lennard-Jones (LJ) potential and consecutive monomers are subject to the Finite-Extension Nonlinear Elastic (FENE) potential. Analysing data for polymers with different lengths, the free energy profile is noted to have interesting finite-size scaling properties.

Free energy evaluation in polymer translocation via Jarzynski equality

International Nuclear Information System (INIS)

Mondaini, Felipe; Moriconi, L.

2014-01-01

We perform, with the help of cloud computing resources, extensive Langevin simulations, which provide free energy estimates for unbiased three-dimensional polymer translocation. We employ the Jarzynski equality in its rigorous setting, to compute the variation of the free energy in single monomer translocation events. In our three-dimensional Langevin simulations, the excluded-volume and van der Waals interactions between beads (monomers and membrane atoms) are modeled through a repulsive Lennard-Jones (LJ) potential and consecutive monomers are subject to the Finite-Extension Nonlinear Elastic (FENE) potential. Analysing data for polymers with different lengths, the free energy profile is noted to have interesting finite-size scaling properties.

Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.

Science.gov (United States)

Capolupo, A; Giampaolo, S M; Illuminati, F

2013-10-01

Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments.

Cluster dynamics: A classical trajectory study of A + A/sub n/arrow-right-leftA*/sub n/+1

International Nuclear Information System (INIS)

Brady, J.W.; Doll, J.D.; Thompson, D.L.

1979-01-01

The dynamics of the collision of an atom A with a small cluster of atoms, A/sub n/, leading to the formation of a quasibound A*/sub n/+1 complex, which subsequently decays, has been studied using classical trajectories. Pairwise Lennard-Jones potentials (with parameters appropriate for argon) were used to describe the identical point masses (Ar). The results illustrate the feasibility of direct calculations of microscopic rates for nucleation processes. The dissociation of collisionally formed A*/sub n/+1 (n=3,4, and 5) occurs by first-order exponential decay. Furthermore the energy dependence of the dissociation rate constants appears to be well described by the RRK functional form

Atomistic simulation of processes in Ni-base alloys with account for local relaxations

International Nuclear Information System (INIS)

Bursik, Jiri

2007-01-01

Ordering in Ni-base superalloys is the crucial process controlling the development of the characteristic two-phase microstructure and subsequently the mechanical properties. Systems containing up to six alloying elements typical of advanced Ni-based superalloys are modelled in this work using a Monte Carlo approach with phenomenological Lennard-Jones pair potentials and interactions up to the third coordination sphere. Three-dimensional crystal block is used with over 10 5 atoms. Molecular dynamics approach is used to relax local atomic positions in course of ordering processes under applied stress. The importance of taking into account both relaxation of modelled block dimensions and relaxation of local atomic positions is discussed

Complexity, rate of energy exchanges and stochasticity

International Nuclear Information System (INIS)

Casartelli, M.; Sello, S.

1987-01-01

The complexity of trajectories in the phase of anharmonic crystal (mostly a Lennard-Jones chain) is analysed by the variance of microcanonical density and by new parameters P and chi defined, respectively, as the mean value of the time averages and the relative variance of the absolute exchange rate of energies among the normal modes. Evidence is given to the trapping action of residual invariant surfaces in low stochastic regime of motion. The parameter chi, moreover, proves efficient in exploring the border of stochasticity. A simple power law for P vs. the specific energy is obtained and proved to be independent of stochasticity and of the type of anharmonic potential

An entropy based analysis of the relationship between the DOW JONES Index and the TRNA Sentiment series

NARCIS (Netherlands)

D.E. Allen (David); M.J. McAleer (Michael); A.K. Singh (Abhay)

2016-01-01

textabstractThis paper features an analysis of the relationship between the DOW JONES Industrial Average Index (DJIA) and a sentiment news series using daily data obtained from the Thomson Reuters News Analytics (TRNA)1 provided by SIRCA (The Securities Industry Research Centre of the Asia Pacic).

Bacterial Biofilms in Jones Tubes.

Science.gov (United States)

Ahn, Eric S; Hauck, Matthew J; Kirk Harris, Jonathan; Robertson, Charles E; Dailey, Roger A

To investigate the presence and microbiology of bacterial biofilms on Jones tubes (JTs) by direct visualization with scanning electron microscopy and polymerase chain reaction (PCR) of representative JTs, and to correlate these findings with inflammation and/or infection related to the JT. In this study, prospective case series were performed. JTs were recovered from consecutive patients presenting to clinic for routine cleaning or recurrent irritation/infection. Four tubes were processed for scanning electron microscopy alone to visualize evidence of biofilms. Two tubes underwent PCR alone for bacterial quantification. One tube was divided in half and sent for scanning electron microscopy and PCR. Symptoms related to the JTs were recorded at the time of recovery. Seven tubes were obtained. Five underwent SEM, and 3 out of 5 showed evidence of biofilms (60%). Two of the 3 biofilms demonstrated cocci and the third revealed rods. Three tubes underwent PCR. The predominant bacteria identified were Pseudomonadales (39%), Pseudomonas (16%), and Staphylococcus (14%). Three of the 7 patients (43%) reported irritation and discharge at presentation. Two symptomatic patients, whose tubes were imaged only, revealed biofilms. The third symptomatic patient's tube underwent PCR only, showing predominantly Staphylococcus (56%) and Haemophilus (36%) species. Two of the 4 asymptomatic patients also showed biofilms. All symptomatic patients improved rapidly after tube exchange and steroid antibiotic drops. Bacterial biofilms were variably present on JTs, and did not always correlate with patients' symptoms. Nevertheless, routine JT cleaning is recommended to treat and possibly prevent inflammation caused by biofilms.

Scaling relation and regime map of explosive gas–liquid flow of binary Lennard-Jones particle system

KAUST Repository

Inaoka, Hajime; Yukawa, Satoshi; Ito, Nobuyasu

2012-01-01

liquid droplets, and gas particles, which remain supercritical gaseous states under the depressurization realized by simulations. The system has a pipe-like structure similar to the model of a shock tube. We observed physical quantities and flow regimes

Index der Titelbestandteile zu Dilwyn Jones: An Index of Ancient Egyptian Titles, Epithets and Phrases of the Old Kingdom

OpenAIRE

Schweitzer, Simon D.

2006-01-01

Vorliegender Index erschließt die nicht-ersten Titelbestandteile der in Dilwyn Jones: An index of ancient Egyptian titles, epithets and phrases of the Old Kingdom. Oxford : Archaeopress, 2000, verzettelten Titel und Epitheta des Alten Reiches.

Malaria and the Decline of Ancient Greece: Revisiting the Jones Hypothesis in an Era of Interdisciplinarity

Science.gov (United States)

Baron, Christopher; Hamlin, Christopher

2015-01-01

Between 1906 and 1909 the biologist Ronald Ross and the classicist W.H.S. Jones pioneered interdisciplinary research in biology and history in advancing the claim that malaria had been crucial in the decline of golden-age Greece (fourth century BCE). The idea had originated with Ross, winner of the Nobel Prize for demonstrating the importance of…

Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

International Nuclear Information System (INIS)

Pentlehner, D.; Slenczka, A.

2015-01-01

Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

[Effectiveness of mini locking plate combined with Kirschner wire in treatment of comminuted Jones fracture].

Science.gov (United States)

Yan, Rongliang; Qu, Jiafu; Cao, Lihai; Liu, Hongda; Chen, Jianghua; Gao, Yan; Peng, Yi

2018-05-01

To summarize the effectiveness of mini locking plate combined with Kirschner wire in treatment of comminuted Jones fracture. Between January 2011 and October 2016, 25 cases with comminuted Jones fracture were treated with mini locking plate combined with Kirschner wire. There were 9 males and 16 females with an average age of 31.4 years (range, 16-66 years). The fractures located on the left side in 11 cases and on the right side in 14 cases. The causes of injury included spraining in 21 cases, falling down in 3 cases, and bruise in 1 case. The bone fragment of all cases was more than 3 pieces. The fracture line was mostly Y-shape or T-shape. Twelve of them were combined with other fractures. The time from injury to operation was 1-9 days (mean, 5 days). The mini locking plate and Kirschner wire were removed at 9-12 months postoperatively. At 12 months postoperatively, the pain was evaluated by the visual analogue scale (VAS) score, and the function by the American Orthopaedic Foot & Ankle Society (AOFAS) score. All incisions healed by first intention. All cases were followed up 12-36 months with an average of 21.7 months. Fracture union was observed in all patients without complications such as nonunion, delayed union, and malunion. The fracture union time was 8-12 weeks (mean, 9.4 weeks). At 12 months postoperatively, the VAS score was 1.15±0.87; the AOFAS score was 89.45±6.24, and the results were excellent in 14 cases, good in 9 cases, fair in 1 case, and poor in 1 case, with an excellent and good rate of 92%. The procedure of mini locking plate combined with Kirschner wire for comminuted Jones fracture has such advantages as convenient operation, more rigid fixation, high rate of fracture healing, and good functional recovery in foot.

77 FR 38051 - Jones Canyon Hydro, LLC; Notice of Application for Amendment of Preliminary Permit Accepted for...

Science.gov (United States)

2012-06-26

... proposed reservoirs from 6,225 feet to 7,330 feet; and (7) change the name of the project from ``Jones Canyon Pumped Storage Project'' to ``Oregon Winds Pumped Storage''. FERC Contact: Jennifer Harper, 202..., using the eComment system at http://www.ferc.gov/docs-filing/ecomment.asp . You must include your name...

Evaluation of linkages between equity indices : evidence from İstanbul Stock Exchange and Dow Jones

OpenAIRE

Ertan, Aytekin

2009-01-01

Ankara : The Department of Management, Bilkent Univiversity, 2009. Thesis (Master's) -- Bilkent University, 2009. Includes bibliographical references leaves 30-33. This study investigates the linkage between the major stock market indices of Turkey (ISE National 100) and USA (Dow Jones Industrial Average). Main purpose of this research is to measure the interdependence and cointegration between these indices and figure out the significance and the direction of short run r...

Percutaneous internal fixation of proximal fifth metatarsal jones fractures (Zones II and III) with Charlotte Carolina screw and bone marrow aspirate concentrate: an outcome study in athletes.

Science.gov (United States)

Murawski, Christopher D; Kennedy, John G

2011-06-01

Internal fixation is a popular first-line treatment method for proximal fifth metatarsal Jones fractures in athletes; however, nonunions and screw breakage can occur, in part because of nonspecific fixation hardware and poor blood supply. To report the results from 26 patients who underwent percutaneous internal fixation with a specialized screw system of a proximal fifth metatarsal Jones fracture (zones II and III) and bone marrow aspirate concentrate. Case series; Level of evidence, 4. Percutaneous internal fixation for a proximal fifth metatarsal Jones fracture (zones II and III) was performed on 26 athletic patients (mean age, 27.47 years; range, 18-47). All patients were competing at some level of sport and were assessed preoperatively and postoperatively using the Foot and Ankle Outcome Score and SF-12 outcome scores. The mean follow-up time was 20.62 months (range, 12-28). Of the 26 fractures, 17 were traditional zone II Jones fractures, and the remaining 9 were zone III proximal diaphyseal fractures. The mean Foot and Ankle Outcome Score significantly increased, from 51.15 points preoperatively (range, 14-69) to 90.91 at final follow-up (range, 71-100; P fracture healing on standard radiographs was 5 weeks after surgery (range, 4-24). Two patients did not return to their previous levels of sporting activity. One patient experienced a delayed union, and 1 healed but later refractured. Percutaneous internal fixation of proximal fifth metatarsal Jones fractures, with a Charlotte Carolina screw and bone marrow aspirate concentrate, provides more predictable results while permitting athletes a return to sport at their previous levels of competition, with few complications.

Application of a non-integer Bessel uniform approximation to inelastic molecular collisions

International Nuclear Information System (INIS)

Connor, J.N.L.; Mayne, H.R.

1979-01-01

A non-integer Bessel uniform approximation has been used to calculate transition probabilities for collinear atom-oscillator collisions. The collision systems used are a harmonic oscillator interacting via a Lennard-Jones potential and a Morse oscillator interacting via an exponential potential. Both classically allowed and classically forbidden transitions have been treated. The order of the Bessel function is chosen by a physical argument that makes use of information contained in the final-action initial-angle plot. Limitations of this procedure are discussed. It is shown that the non-integer Bessel approximation is accurate for elastic 0 → 0 collisions at high collision energies, where the integer Bessel approximation is inaccurate or inapplicable. (author)

Isoviscosity lines and the liquid-glass transition in simple liquids.

Science.gov (United States)

Fomin, Yu D; Brazhkin, V V; Ryzhov, V N

2012-07-01

This article presents the study of the generic behavior of viscosity of liquids based on some simple theoretical models, the soft-spheres and Lennard-Jones systems. The use of these simple models allows us to investigate in detail the viscosity behavior in a wide range of temperatures and pressures including the high-temperature-high-pressure limits. Based on the simulation results, we discuss the shape of isoviscosity lines and analyze the glass transition at high temperatures and high pressures. Despite the fact that the viscosity drastically increases in the limit of high temperatures and high pressures along the melting line, the relaxation time rapidly decreases in this region, and the system becomes further from the glass transition.

Continuous approximation for interaction energy of adamantane encapsulated inside carbon nanotubes

Science.gov (United States)

Baowan, Duangkamon; Hill, James M.; Bacsa, Wolfgang

2018-02-01

The interaction energy for two adjacent adamantane molecules and that of adamantane molecules encapsulated inside carbon nanotubes are investigated considering only dipole-dipole induced interaction. The Lennard-Jones potential and the continuous approximation are utilised to derive analytical expressions for these interaction energies. The equilibrium distance 3.281 Å between two adamantane molecules is determined. The smallest carbon nanotube radius b0 that can encapsulate the adamantane molecule and the radius of the tube bmax that gives the maximum suction energy, linearly depend on the adamantane radius, are calculated. For larger diameter tubes, the off axis position has been calculated, and equilibrium distance between molecule and tube wall is found to be close to the interlayer spacing in graphene.

Comment on 'Path integral solution for a Mie-type potential'

International Nuclear Information System (INIS)

Steiner, F.

1985-01-01

We comment on several incorrect results given in a recent paper by Erkoc and Sever (ES). In particular, it is pointed out that their path integral formula for the one-dimensional Mie-Lennard-Jones potential is wrong, since a quantum correction proportional to (h/2π) 2 - which is a consequence of the stochastic nature of the Feynman paths - has been overlooked. The correct expression can be obtained from a general path integral formula, which we have derived in a previous paper. For the particular potential discussed in detail by ES, we give a complete path integral treatment, which allows us to derive the energies and normalized wave functions of the discrete spectrum. (orig.)

Influence of attractions on the static and dynamic properties of simulated single and multichain systems

International Nuclear Information System (INIS)

Bishop, M.; Kalos, M.H.; Frisch, H.L.

1983-01-01

The influence of the attractive portion of the Lennard-Jones potential on the statics and dynamics of both single chain and multichain systems is investigated by reptation and molecular dynamics simulations. There is no significant effect at a reduced temperature of 10.0. At a temperature of 1.7 the single chain and multichain system at low densities (0.1) indicate that the attractions cause both the chains to be significantly more compact and a slowing of the time autocorrelation functions of the square of the end-to-end distance and radius of gyration. At a moderate density of 0.5, the attractions have almost no effect on the static structure, but they still influence the dynamic properties

Response functions for crystals and surfaces, with applications to surface scattering

International Nuclear Information System (INIS)

Barker, J.A.; Steele, W.A.

1978-01-01

A general solution of the equations of forced motion of a harmonic crystal or other vibrating system with arbitrary time-dependent forces acting on the atoms is given. The solution is given in terms of dynamical 'response functions', for which expressions in terms of the normal mode frequencies and eigenvectors (polarization vectors) are given. Numerical calculations of the response functions are described for (111) and (100) surfaces of face-centered cubic crystals interacting with Lennard-Jones 6-12 potentials, and the qualitative features of the surface and bulk response functions are discussed. The use of these functions in problems of atomic scattering from surface is outlined, and convenient parametrized forms for this application are given. (Auth.)

Structural models for amorphous transition metal binary alloys

International Nuclear Information System (INIS)

Ching, W.Y.; Lin, C.C.

1976-01-01

A dense random packing of 445 hard spheres with two different diameters in a concentration ratio of 3 : 1 was hand-built to simulate the structure of amorphous transition metal-metalloid alloys. By introducing appropriate pair potentials of the Lennard-Jones type, the structure is dynamically relaxed by minimizing the total energy. The radial distribution functions (RDF) for amorphous Fe 0 . 75 P 0 . 25 , Ni 0 . 75 P 0 . 25 , Co 0 . 75 P 0 . 25 are obtained and compared with the experimental data. The calculated RDF's are resolved into their partial components. The results indicate that such dynamically constructed models are capable of accounting for some subtle features in the RDF of amorphous transition metal-metalloid alloys

Application of Statistical Thermodynamics in Refrigeration

International Nuclear Information System (INIS)

Avsec, J.; Marcic, M.

1999-01-01

The paper presents the mathematical model for computing the thermodynamical properties in the liquid, gas and two-phase domain by means of statistical thermodynamics. The paper features all important components (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). To calculate the thermodynamic properties of real gases, we have developed the cluster theory, which yields better results than the virial equation. In case of real liquids, the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin (BWR) equation was applied. The Lennard-Jones intermolecular potential was used. The analytical results are compared with the thermodynamical data and models obtained from classical thermodynamics, and they show relatively good agreement. (author)

Curvature Dependence of Interfacial Properties for Associating Lennard—Jones Fluids: A Density Functional Study

International Nuclear Information System (INIS)

Sun Zong-Li; Kang Yan-Shuang

2011-01-01

Classical density functional theory is used to study the associating Lennard—Jones fluids in contact with spherical hard wall of different curvature radii. The interfacial properties including contact density and fluid-solid interfacial tension are investigated. The influences of associating energy, curvature of hard wall and the bulk density of fluids on these properties are analyzed in detail. The results may provide helpful clues to understand the interfacial properties of other complex fluids. (condensed matter: structure, mechanical and thermal properties)

77 FR 17530 - Order Granting an Application of Edward Jones & Co. LLP Exemption From Exchange Act Section 11(d...

Science.gov (United States)

2012-03-26

...'') requested that the Securities and Exchange Commission (``Commission'') issue to Edward Jones an exemption... subject to the conditions contained in this order, is exempt from the new issue lending restriction of... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-66624] Order Granting an Application of Edward...

Platform for Manipulating Polarization Modes Realized with Jones Vectors in MATHEMATICA

Directory of Open Access Journals (Sweden)

Yong-Dae Choi

2015-06-01

Full Text Available The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

Communication: Fourier-transform infrared probing of remarkable quantities of gas trapped in cold homogeneously nucleated nanodroplets

Science.gov (United States)

Uras-Aytemiz, Nevin; Devlin, J. Paul

2013-07-01

Studies of catalyzed all-vapor gas-hydrate formation on a sub-second timescale have been extended with a special focus on liquid-droplet compositions at the instant of hydrate crystallization. This focus has been enabled by inclusion of methanol in the all-vapor mixture. This slows droplet to gas-hydrate conversion near 200 K to a time scale suited for standard FTIR sampling. Such droplet data are sought as a guide to ongoing efforts to reduce the amount of guest catalyst required for instant formation of the gas hydrates. For the same reason, all-vapor sampling has also been extended to the generation of long-lived liquid droplets with reduced or no water content. Observations of single-solvent droplets show that surprising quantities of gas molecules are trapped during rapid droplet growth. For example, CO2 is trapped at levels near 50 mol. % in droplets of acetone, tetrahydrofuran, or trimethylene oxide formed under CO2 pressures of several Torr in a cold-chamber at 170 K. Less but significant amounts of gas are trapped at higher temperatures, or in methanol or water-methanol droplets. The droplet metastability appears to commonly lead to formation of bubbles larger than the original nanodroplets. Besides serving as a guide for the all-vapor gas-hydrate studies, the semiquantitative evidence of extensive trapping of gases is expected to have a role in future studies of atmospheric aerosols.

Idiopathic gingival fibromatosis associated with progressive hearing loss: A nonfamilial variant of Jones syndrome

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Bagavad Gita

2014-01-01

Full Text Available Gingival fibromatosis is characterized by gingival tissue overgrowth of a firm and fibrotic nature. The growth is slow and progressive and is drug-induced, idiopathic, or hereditary in etiology. It occurs isolated or frequently as a component of various syndromes. Our patient presented with the complaint of gingival enlargement associated with progressive deafness, characteristic of Jones syndrome. This case report is important and unique since it is the first known one to have a Jones syndrome-like presentation without a family history. A male patient aged 14 years reported with the chief complaint of swelling of gums and progressive hearing loss in both ears for the past one year. There was no family history or history of drug intake. Enlargement was generalized, fibrotic and bulbous, involving the free and attached gingiva, extending up to the middle 1/3 rd of the crown. Investigations such as pure tone audiogram, impedance audiometry, and Tone decay test concluded that there was severe right and moderate left sensorineural hearing loss. The case was diagnosed to be idiopathic, generalized gingival fibromatosis with progressive hearing loss. The gingival overgrowth was managed by gingivectomy and periodic review. The patient was advised to use high occlusion computer generated hearing aids for his deafness as it was not treatable by medicines or surgery. This unique case report once again emphasizes the heterogeneity of gingival fibromatosis, which can present in an atypical manner.

Volatility Transmission Between Dow Jones Stock Index And Emerging Islamic Stock Index: Case Of Subprime Financial Crises

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Amir Saadaoui

2015-02-01

Full Text Available In the course of the recent global crisis, the stock shocks are distributed and transmitted from their homes in the developed stock market to emerging stock markets. By supporting the development of emerging stock markets, this study aims to see the transmission of volatility between the Dow Jones stock index and the Dow Jones emerging Islamic stock indiex. In this study we have divided the period into three, periods, before, during and after this crisis to demonstrate the resilience of the Islamic market index in response to the global financial crisis. Another aim of this study is to provide a new guide line for investors in emerging stock market before making investment decisions. The data are daily, going from 02/01/2005 until 31/12/2012. To measure the transmission we used bivariate BEKK-GARCH and DCC-GARCH model. The result shows that there is a transmission mainly during the crisis period which means that the crisis affects all the financial assets whether Islamic or not. The same result also shows the preference to invest in both Islamic and classical stock indexes since they are less risky.

Imaginando Palmares: a obra de Gayl Jones

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Stelamaris Coser

2005-01-01

Full Text Available http://dx.doi.org/10.1590/S0104-026X2005000300010 O longo poema narrativo Song for Anninho (1981, da escritora negra Gayl Jones (Estados Unidos, interfere na narrativa da história colonial brasileira ao resgatar a figura feminina na República de Palmares, reescrever a saga de resistência dos palmaristas do ponto de vista imaginário de uma mulher negra do século XVII e, através dela, reinventar o cotidiano, os amores, as disputas e os sonhos das pessoas comuns que integravam o quilombo. O texto reflete sobre a verdade histórica, o aspecto construído de documentos, as seleções e exclusões da linguagem, e a importância do relato oral para o conhecimento de vivências e identidades à margem da história oficial. Nessa versão especial, o relato dramático do sonho, da luta e da destruição do mais famoso quilombo brasileiro usa a imaginação literária para expandir a memória e os arquivos de um dos fatos mais importantes da história das Américas, contribuindo para estimular o diálogo interamericano e iluminar a diáspora africana no Brasil e no continente.

Avaliação cefalométrica das alterações dentoesqueléticas de jovens com má oclusão de Classe II dentária tratados com distalizadores Jones jig Cephalometric evaluation of dentoskeletal changes in Class II young patients treated with Jones jig appliances

Directory of Open Access Journals (Sweden)

Mayara Paim Patel

2009-06-01

Full Text Available OBJETIVO: esta pesquisa objetivou avaliar cefalometricamente as alterações dentoesqueléticas de jovens com Classe II dentária tratados com o distalizador Jones jig. METODOLOGIA: foram avaliados 30 pacientes, sendo 15 de cada gênero, com média de idades iniciais de 13,63 anos; brasileiros, naturais da cidade de Bauru/SP, caracterizados por má oclusão de Classe II, 1ª e 2ª divisões de Angle sem comprometimento esquelético. Os jovens foram tratados com aparelho Jones jig a fim de distalizar os molares superiores a uma relação molar de "super Classe I"; sendo que esse dispositivo permaneceu, em média, por 0,55 anos. Ao final da sobrecorreção, os molares distalizados receberam um botão de Nance e, como ancoragem extrabucal, o aparelho extrabucal (AEB com tração média-alta, com o intuito de verticalizar e corrigir a angulação radicular dos molares distalizados. Foram realizadas telerradiografias em normal lateral inicial (T1 e pós-distalização (T2. As medidas cefalométricas foram submetidas ao teste t dependente de Student para avaliar as alterações de T1 para T2. RESULTADOS: com base nos resultados obtidos e a partir da metodologia empregada, observou-se alterações dentárias significativas, como a movimentação distal linear e angular, assim como a intrusão dos segundos e primeiros molares superiores no sentido vertical. Também se confirmou efeitos indesejáveis, como a perda de ancoragem refletida em mesialização, extrusão e angulação mesial dos segundos pré-molares, a protrusão dos incisivos superiores e o aumento do trespasse vertical e horizontal. Pode-se confirmar que certas movimentações dentárias promovem significativas alterações esqueléticas de estruturas localizadas à distância, ou seja, observou-se extrusão significativa dos segundos pré-molares superiores, o que resultou em rotação mandibular, aumento significativo da altura facial anteroinferior e protrusão do lábio inferior

Lennard-Jones triple-point bulk and shear viscosities. Green-Kubo theory, Hamiltonian mechanics, and nonequilibrium molecular dynamics

International Nuclear Information System (INIS)

Hoover, W.G.; Evans, D.J.; Hickman, R.B.; Ladd, A.J.C.; Ashurst, W.T.; Moran, B.

1980-01-01

A new Hamiltonian method for deformation simulations is related to the Green-Kubo fluctuation theory through perturbation theory and linear-response theory. Numerical results for the bulk and shear viscosity coefficients are compared to corresponding Green-Kubo calculations. Both viscosity coefficients depend similarly on frequency, in a way consistent with enhanced ''long-time tails.''

Shape matters: The case for Ellipsoids and Ellipsoidal Water

Energy Technology Data Exchange (ETDEWEB)

Tillack, Andreas F. [ORNL; Robinson, Bruce H. [University of Washington, Seattle

2017-11-01

We describe the shape potentials used for the van der Waals interactions between soft-ellipsoids used to coarse-grain molecular moieties in our Metropolis Monte-Carlo simulation software. The morphologies resulting from different expressions for these van der Waals interaction potentials are discussed for the case of a prolate spheroid system with a strong dipole at the ellipsoid center. We also show that the calculation of ellipsoids is, at worst, only about fivefold more expensive computationally when compared to a simple Lennard- Jones sphere. Finally, as an application of the ellipsoidal shape we parametrize water from the original SPC water model and observe – just through the difference in shape alone – a significant improvement of the O-O radial distribution function when compared to experimental data.