Thermodynamic Properties Of Matter Research Articles

Thermodynamic explanation and criterion for the exhibition of melting inability in molecular species

<abstract> <p>Thermodynamic properties of matter e.g., melting point, are important for various applications. However, in some substances the primary observed effect upon heating is decomposition which in some cases is accompanied by fluidization. Thus, it would be very useful to be able to predict if a given substance will be able to melt or will exhibit melting inability upon heating. In this work, a thermodynamic explanation for the melting inability of molecular solids is provided and a corresponding criterion is proposed for the prediction of melting ability or inability of a given substance. One key concept is to study the strength of the weakest chemical bond rather than overall enthalpy of reaction. This arises from the fact that if decomposition occurs, then, regardless of the extent of decomposition, the transition cannot be considered to be melting. The criterion can be combined with sophisticated modeling in order to derive accurate values. Here, a simple method is proposed and an approximate index is developed which allows for a rapid and massive implementation of the criterion. The index is based on the concept of group contributions methods (estimation of the enthalpy of the maximum possible interactions, ${\mathit{\Delta}} H_{max }$) and on a distorted version of Trouton's rule (correlation of $ {\mathit{\Delta}} H_{max }$ with the heat required for melting). The correlation factor (${x}_{melting}$) was found to be equal to 40.6%. The index is successfully applied in various organic substances, including (bio)molecules of pharmaceutical/nutraceutical interest. Index values between −30 and 0 correspond to marginal cases of rather high uncertainty. Positive index values clearly point out melting inability. The proposed index successfully predicts the melting ability/inability in more than 80% of the studied substances.</p> </abstract>

Determination of thermodynamic and structural quantities of polymers by scattering techniques

Abstract Scattering techniques (i.e. light scattering, X-ray scattering, or neutron scattering) are very powerful tools to gain insights into structural and thermodynamic properties of matter which often cannot be obtained by other methods. While classical thermodynamics is independent of length scale or applies for indefinitely long length scale, scattering can disclose thermodynamic properties like the free energy or free enthalpy as functions of length scale. Scattering is caused by density or composition fluctuations, which are functions of the length scale in one- or multicomponent systems. Therefore scattering techniques can give informations about the size, shape and molecular weight of scattering objects, their thermodynamic interactions with a surrounding matrix and their dynamics if correlations of the fluctuations as function of time are investigated (i.e. dynamic light scattering). As scattering techniques are less intuitive in comparison to complementary techniques, i.e. microscopic techniques, the aim of this article is to highlight some relevant relationships with a focus on polymer systems. This may encourage polymer scientists to consider the use of scattering techniques to learn more about the thermodynamics of their systems and/or to gain informations about their structural properties.

Influence of shell effects on thermodynamic properties of matter at high pressures

We analyze the influence of shell effects on thermodynamic properties of matter at high pressures. Spherically symmetric average atom models show significant contribution of electronic transitions to cold pressure which is not confirmed by more accurate density functional theory models. In particular, the s–d transition in aluminum and potassium does not reveal itself on the shock Hugoniots. Oscillations on shock Hugoniots at very high pressures predicted earlier by many authors should be confirmed by precise first-principle calculations.

Thermodynamics of an Attractive 2D Fermi Gas.

Thermodynamic properties of matter are conveniently expressed as functional relations between variables known as equations of state. Here we experimentally determine the compressibility, density, and pressure equations of state for an attractive 2D Fermi gas in the normal phase as a function of temperature and interaction strength. In 2D, interacting gases exhibit qualitatively different features to those found in 3D. This is evident in the normalized density equation of state, which peaks at intermediate densities corresponding to the crossover from classical to quantum behavior.

Transverse Momentum Distributions in AuAu and dAu Collisions atsNN=200 GeV

We study the transverse momentum distributions of identified particles produced in Au + Au and d + Au collisions atSNN=200 GeV. The Tsallis description is applied in the multisource model. The results are compared with the experimental data in detail. We obtain some information of the thermodynamic properties of matter produced in the collisions. The difference of the transverse momentum distributions in Au + Au and d + Au collisions is not significant.

Coupling of transport and thermodynamic properties of nonideal multicomponent matter

The general relations between thermophysical properties of non-ideal matter are investigated to check the approximations for the calculation of the properties in the linear response case. In particular for the examination of the approach which is proposed for the full set of the transport coefficients, determining currents of pulse, heat, mass and charge in high energy density matter with strong interparticle interactions and chemical reactions. To do this the detailed analysis has been carried out of available experimental data of non-ideal matter transport coefficients of various substances, The effective transport coefficients (these coefficients first of all couple the thermodynamic and transport properties of a non-ideal matter) are introduced, relating the mass currents of chemical elements and the convective heat current to temperature and element concentrations gradients and the effective fields in a matter. The number of conditions imposed on the nonlinear, nondiagonal matrix of the effective transport coefficients and on the high derivative coefficients matrix of the set of conservation equations for a non-ideal medium are derived. The properties of these matrixes are the next result of coupling of transport and thermodynamic properties of a matter. It is considered also the relations between transport and thermodynamic properties of matter in the case of a nonlinear response. At last the coupling is studied for a system under the plasma phase transition within the framework of Cahn-Hilliard approach.

Ablative Acceleration of Foils, Their Pulsations, and Interchange Instability

The problem of hydrodynamic stability is important for inertial confinement fusion (ICF) systems based upon high compression of fuel before its ignition. This problem for the case of complicated multilayer foils has been studied here by a new approach describing the development of Rayleigh-Taylor or interchange instability in compressible media with inhomogeneous distribution of “entropy”s = ρ/ρk, ∂ where K = (∂ In ρ/∂ In ρ)s is an adiabatic derivative taken in the local hydrostatic values of ρ and ρ. Inhomogeneous distribution of s simulates the dynamics of development of perturbations of multilayer flyer foils and shells. Besides instability, the same approach has been used for analysis of ID pulsations of a levitated foil. The problem of pulsations is real in the case of foils. Indeed, (1) an ablative acceleration is equivalent to an effective gravity field, which causes the appearance of an atmospheric-type distribution of thermodynamic functions, (2) the duration of ablative flight of foil is at least several times larger than the time that is necessary for an acoustic wave to travel from one side of the foil to another side, and (3) there is a strong initial impulse that initiates the motion of foil. This impulse together with (1, 2) is a reason for the powerful pulsations of foils. The period of pulsations is defined by the velocity of sound in the foil material, which is dependent on the derivatives of an equation of state (EOS). The check of the derivatives gives us finer information concerning the current state of matter and the EOS than the usual measurements of material velocity and pressure that are rougher measures. Therefore, an analysis of pulsations seems to be a promising tool for tracking the dynamics of flyer foil and for the definition of thermodynamic properties of matter.

Der Drehimpulssatz in der Thermodynamik der irreversiblen Prozesse

The conservation law of the angular momentum has not been given sufficient attention in thermodynamics of irreversible processes. It plays an important part, however, when irreversible processes in the presence of electromagnetic fields are examined and the intrinsic angular momentum, due to spins of electrons and nuclei and electron orbits in atoms and molecules, is taken account of. Then the thermodynamic properties of matter with the macroscopic intrinsic angular momentum as an additional extensive parameter can be developed. Thermodynamics of irreversible processes is completed by the fact that a characteristic irreversible process is now associated also with the conservation law of angular momentum and Bloch's equation of nuclear induction is thus obtained in a straightforward way as one of the phenomenological equations.