Search results for "THERMODYNAMICS"

Thermodynamical derivation of a hydrodynamical model of inhomogeneous superfluid turbulence

2007

In this paper, we build up a thermodynamical model of inhomogeneous superfluid turbulence to describe vortex diffusion in inhomogeneous turbulent tangles, and a coupling between second sound and vortex-density waves. The theory chooses as fundamental fields the density, the velocity, the energy density, the heat flux, and the averaged vortex line length per unit volume. The restrictions on the constitutive quantities are deduced from the entropy principle, using the Liu method of Lagrange multipliers. Field equations are written and the wave propagation is studied with the aim to describe the mutual interactions between the second sound and the vortex tangle.

Thermomechanical Phenomena in Extended Thermodynamics of an Ideal Monoatomic Superfluid

1992

Computer simulation of disordering and premelting of low-index faces of copper.

1992

Molecular dynamics and the effective-medium theory have been applied to investigate the structure and dynamics of (110), (100), and (111) faces of copper in the whole temperature range from 0 K up to the bulk melting point, which has been determined to be 1240\ifmmode\pm\else\textpm\fi{}25 K. The observed order in the surface stability follows the order in the packing density. (110) disorders first via anharmonic effects (up to 700 K), then by vacancy-adatom formation and finally by premelting of the surface at about 1200 K. The (110) solid-melt interface is anisotropic and broadened, having a tendency to form small fluctuating (111) facets in equilibrium, which is suggested to be the atomi…

Porphyroblast crystallization kinetics: the role of the nutrient production rate

2011

The mechanisms that govern porphyroblast crystallization are investigated by comparing quantitative textural data with predictions from different crystallization models. Such numerical models use kinetic formulations of the main crystallization mechanism to predict textural characteristics, such as grain size distributions. In turn, data on porphyroblast textures for natural samples are used to infer which mechanism dominated during their formation. Whereas previous models assume that the rate-limiting step for a porphyroblast producing reaction is either transport or growth, the model advanced in this study considers the production of nutrients for porphyroblasts as a potentially rate-limi…

Nucleation in Supersaturated Vapors

2009

Geminal Imidazolium Salts: A new Class of Gelators

2012

The gelling behavior of some geminal diimidazolium salts was investigated in solvents differing in polarity and hydrogen bond donor ability. The used salts, namely the 3,3'-di-n-decyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(decim)(2)][Br](2) (1), the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(dodecim)(2)][Br](2) (2), and the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate [p-Xyl-(dodecim)(2)][BF(4)](2) (3), differ in the alkyl chain length and in the anion properties, such as size, shape, and coordination ability. In all cases in which gelation process was observed, the obtained gels were characteri…

Size and shape effects on the thermodynamic properties of nanoscale volumes of water

2017

Small systems are known to deviate from the classical thermodynamic description, among other things due to their large surface area to volume ratio compared to corresponding big systems. As a consequence, extensive thermodynamic properties are no longer proportional to the volume, but are instead higher order functions of size and shape. We investigate such functions for second moments of probability distributions of fluctuating properties in the grand-canonical ensemble, focusing specifically on the volume and surface terms of Hadwiger's theorem, explained in Klain, Mathematika, 1995, 42, 329–339. We resolve the shape dependence of the surface term and show, using Hill's nanothermodynamics…

Surface Effects on Block Copolymer Melts Above the Order-Disorder Transition: Linear Theory of Equilibrium Properties and the Kinetics of Surface-Ind…

1997

A phenomenological theory is developed for static and dynamic aspects ofsurface- induced ordering of symmetrical block copolymers taking fluctuation corrections into account, but, considering conditions where the bulk block copolymer melt is still disordered, and a lin- earized version of the resulting Ginzburg-Landau type equation suffices. Both the semi-infinite geometry and symmetrical films of thickness 2L are treated, applying the same boundary con- ditions as used previously for a treatment of wetting in polymer blends, assuming short range surface forces and a long Wavelength approximation. For the static order parameter profile in thin film geometry, We derive an oscillatory converg…

Toward a density functional description of liquid pH2.

2010

A finite-temperature density functional approach to describe the properties of parahydrogen in the liquid-vapor coexistence region is presented. The first proposed functional is zero-range, where the density-gradient term is adjusted so as to reproduce the surface tension of the liquid-vapor interface at low temperature. The second functional is finite-range and, while it is fitted to reproduce bulk pH2 properties only, it is shown to yield surface properties in good agreement with experiments. These functionals are used to study the surface thickness of the liquid-vapor interface, the wetting transition of parahydrogen on a planar Rb model surface, and homogeneous cavitation in bulk liquid…

Water interaction with perfect and fluorine-doped Co3O4 (100) surface

2015

Abstract We report the results of theoretical investigations of water adsorption on undoped and fluorine-doped Co3O4 (100) surface by means of the plane-wave periodic density functional theory (DFT) calculations combined with the Hubbard-U approach and statistical thermodynamics. We discuss the effect of fluorine-doping of the Co3O4 (100) surface and calculated oxygen evolution reaction overpotential based on the Gibbs free-energy diagram of undoped and F-doped surfaces.