Thermodynamic properties of tungsten
Göran Grimvall; Maria Thiessen; Armando Fernández Guillermet
1987-01-01
Tungsten has several unusual thermodynamic properties, e.g., very high values of the melting point, the entropy of fusion, the expansion on melting and the lattice anharmonicity. These features are given a semiquantitative explanation, based on the electron density of states N(E). Our treatment includes a numerical calculation of the electronic heat capacity from N(E) and a calculation of the entropy
Computing Thermodynamic And Transport Properties
NASA Technical Reports Server (NTRS)
Mcbride, B.; Gordon, Sanford
1993-01-01
CET89 calculates compositions in chemical equilibrium and properties of mixtures of any chemical system for which thermodynamic data available. Provides following options: obtains chemical-equilibrium compositions and corresponding thermodynamic mixture properties for assigned thermodynamic states; calculates dilute-gas transport properties of complex chemical mixtures; obtains Chapman-Jouguet detonation properties for gaseous mixtures; calculates properties of incident and reflected shocks in terms of assigned velocities; and calculates theoretical performance of rocket for both equilibrium and frozen compositions during expansion. Rocket performance based on optional models of finite or infinite area combustor.
Thermodynamic Properties of HCFC-124
NASA Astrophysics Data System (ADS)
Fukushima, Masato; Watanabe, Naohiro
Thermodynamic properties of HCFC-124, such as saturated densities, vapor pressures and PVT properties, were measured and the critical parameters were determined through those experimental results. The correlations for vapor pressure, saturated liquid density and PVT properties deduced from those experimental results were compared with the measured data and also with the estimates of the other correlations published in literatures. The thermodynamic functions, such as enthalpy, entropy, heat capacity, etc., can reasonably be calculated from the correlation equations in this paper.
Thermodynamic properties of cerium mononitride
NASA Astrophysics Data System (ADS)
Aristova, N. M.; Belov, G. V.
2014-09-01
Data on the thermodynamic properties of cerium mononitride CeN in the solid state are analyzed. Relations approximating the temperature dependence of the thermodynamic functions of CeN(cr.) in the temperature range of 298.15-2900 K are obtained. Using the relations of thermodynamics known for this temperature range, the thermodynamic functions of cerium mononitride (entropy, Gibbs energy, and enthalpy variation) are calculated. The resulting data is entered into the database of the IVTANTHERMO software package and is used to analyze the thermal stability of CeN(cr.), and to estimate its boiling point at atmospheric pressure.
Thermodynamic Properties of Supported Catalysts
Gorte, Raymond J.
2014-03-26
The goals of this work were to develop Coulometric Titration as a method for characterizing the thermodynamic redox properties of oxides and to apply this technique to the characterization of ceria- and vanadia-based catalysts. The redox properties of ceria and vanadia are a major part of what makes these materials catalytically active but their properties are also dependent on their structure and the presence of other oxides. Quantifying these properties through the measurement of oxidation energetics was the goal of this work.
Thermodynamic properties of uranium dioxide
NASA Astrophysics Data System (ADS)
Fink, J. K.; Chasanov, M. G.; Leibowitz, L.
1981-04-01
In order to provide reliable and consistent data on the thermophysical properties of reactor materials for rector safety studies, revision was prepared for the thermodynamic properties of the uranium dioxide portion of the fuel property section of the report Properties for Liquid Metal Fast Breeder Reactors Safety Analysis. International agreement was reached on a vapor pressure equation for the total pressure over UO2, for the calculation of enthalpy and heat capacity, and a phase change at 2670 K. An electronic term is used in place of the Frenkel defect term in the enthalpy and heat capacity equation and the phase transition is accepted.
Thermodynamical properties of dark energy
Yungui Gong; Bin Wang; Anzhong Wang
2007-01-01
We have investigated the thermodynamical properties of dark energy. Assuming that the dark energy temperature T˜a-n and considering that the volume of the Universe enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For dark energy with constant equation of state w>-1 and the generalized Chaplygin gas, the derived entropy can be positive
Thermodynamical properties of dark energy
Wang Anzhong; Wang Bin; Gong Yungui
2007-01-01
We have investigated the thermodynamical properties of dark energy. Assuming that the dark energy temperature Tâa{sup -n} and considering that the volume of the Universe enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For dark energy with constant equation of state w>-1 and the generalized Chaplygin gas, the derived entropy can be
Thermodynamic properties of chromium silicides
G. M. Lukashenko; V. R. Sidorko; L. M. Yupko
1986-01-01
In investigation of the thermodynamic properties of chromium silicides in the 973I133~ range by measurement of the emf's [i] for alloys located in the adjoining heterogeneous areas [CrbSi3 + CrSi] and [CrSi + CrSi2] values of the emf agreeing within the limits of measurement error and consequently of the partial Gibbs energies were obtained. This was related by the authors
Thermodynamical properties of dark energy
Gong Yungui; Wang Bin; Wang Anzhong [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China) and CASPER, Department of Physics, Baylor University, Waco, Texas 76798 (United States); Department of Physics, Fudan University, Shanghai 200433 (China); CASPER, Department of Physics, Baylor University, Waco, Texas 76798 (United States)
2007-06-15
We have investigated the thermodynamical properties of dark energy. Assuming that the dark energy temperature T{approx}a{sup -n} and considering that the volume of the Universe enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For dark energy with constant equation of state w>-1 and the generalized Chaplygin gas, the derived entropy can be positive and satisfy the entropy bound. The total entropy, including those of dark energy, the thermal radiation, and the apparent horizon, satisfies the generalized second law of thermodynamics. However, for the phantom with constant equation of state, the positivity of entropy, the entropy bound, and the generalized second law cannot be satisfied simultaneously.
Thermodynamical properties of dark energy
Yungui Gong; Bin Wang; Anzhong Wang
2007-06-22
We have investigated the thermodynamical properties of dark energy. Assuming that the dark energy temperature $T\\sim a^{-n}$ and considering that the volume of the Universe enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For dark energy with constant equation of state $w>-1$ and the generalized Chaplygin gas, the derived entropy can be positive and satisfy the entropy bound. The total entropy, including those of dark energy, the thermal radiation and the apparent horizon, satisfies the generalized second law of thermodynamics. However, for the phantom with constant equation of state, the positivity of entropy, the entropy bound, and the generalized second law cannot be satisfied simultaneously.
Thermodynamic and Properties of Nanophases
Wunderlich, Bernhard {nmn} [ORNL
2009-01-01
A large volume of today s research deals with nanophases of various types. The materials engineer, chemist, or physicist, however, when dealing with applications of nanophases is often unaware of the effect of the small size on structure and properties. The smallest nanophases reach the limit of phase definitions by approaching atomic dimensions. There, the required homogeneity of a phase is lost and undue property fluctuations destroy the usefulness of thermodynamic functions. In fact, itwas not expected that a definite nanophasewould exist belowthe size of a microphase.Aneffort ismadein this reviewto identify macrophases, microphases, and nanophases. It is shown that nanophases should contain no bulk matter as defined by macrophases and also found in microphases. The structure and properties of nanophases, thus, must be different from macrophases and microphases. These changes may include different crystal and amorphous structures, and phase transitions of higher or of lower temperature. The phase properties are changing continuously when going from one surface to the opposite one. The discussion makes use of results from structure determination, calorimetry, molecular motion evaluations, and molecular dynamics simulations.
Tables of thermodynamic properties of sodium
Fink, J.K.
1982-06-01
The thermodynamic properties of saturated sodium, superheated sodium, and subcooled sodium are tabulated as a function of temperature. The temperature ranges are 380 to 2508 K for saturated sodium, 500 to 2500 K for subcooled sodium, and 400 to 1600 K for superheated sodium. Tabulated thermodynamic properties are enthalpy, heat capacity, pressure, entropy, density, instantaneous thermal expansion coefficient, compressibility, and thermal pressure coefficient. Tables are given in SI units and cgs units.
Thermodynamic Properties of Aqueous Solution of Ammonia
NASA Astrophysics Data System (ADS)
Kitamura, Hiroshi; Oguchi, Kosei
Present status on the thermodynamic properties of experimental data and their correlations of both ammonia and aqueous solution of ammonia was introduced in this paper. The aqueous solution of ammonia is used for not only a working fluid in absorption refrigerator cycles but also working fluids in bottoming cycles of steam power plants and other heat recovering systems. Therefore, the thermodynamic properties of this substance are required in a wide range of temperatures, pressures and compositions. The experimental results of pVTx properties for ammonia and aqueous solution of ammonia and their comparisons with a formulation by Tillner-Roth and Friend1) were critically surveyed. The “Guideline on the IAPWS Formulation 2000 for the Thermodynamic Properties of Ammonia-Water Mixtures”, correlated by Tillner-Roth and Friend1), was approved on September, 2001, by the International Association for the Properties of Water and Steam (IAPWS) 2).
Thermodynamic properties of gallium nitride
NASA Astrophysics Data System (ADS)
Peshek, Timothy J.; Angus, John C.; Kash, Kathleen
2011-05-01
In this paper we reply to a critique of a recent publication of ours on the thermochemical properties of GaN. In the critique, it was claimed that our results for the Gibbs free energy of formation of GaN were biased to negative values because of the sluggish kinetics of formation and decomposition of GaN at the temperatures of interest. We show that this criticism is not well founded. We further show that the range of reported values of the Gibbs free energy of formation, the enthalpy of formation, and the entropy of formation of GaN permit a relatively wide range of self-consistent choices of these properties. Further refinement of the data is required before any one set of properties can be recommended.
Prediction of Thermodynamic Properties for Halogenated Hydrocarbon
NASA Astrophysics Data System (ADS)
Higashi, Yukihiro
The predictive methods of thermodynamic properties are discussed with respect to the halogenated hydrocarbons using as working fluids for refrigeration and heat pump cycles. The methods introduced into this paper can be calculated by the limited information; critical properties, normal boiling point and acentric factor. The results of prediction are compared with the experimental values of PVT property, vapor pressure and saturated liquid density. On the basis of these comparisons, Lydersen's method for predicting the critical properties, the generalized vapor pressure correlation by Ashizawa et, al., and Hankinson-Thomson's method for predicting saturated liquid density can be recommended. With respect to the equation of state, either Soave equation or Peng-Robinson equation is effective in calculating the thermodynamic properties except high density region.
Thermodynamic properties of wadsleyite with anharmonic effect
NASA Astrophysics Data System (ADS)
Wu, Zhongqing
2015-02-01
The thermodynamic properties of crystals can be routinely calculated by density functional theory calculations combining with quasi-harmonic approximation. Based on the method developed recently by Wu and Wentzcovitch (Phys Rev B 79:104304, 2009) and Wu (Phys Rev B 81:172301, 2010), we are able to further ab initio include anharmonic effect on thermodynamic properties of crystals by one additional canonical ensemble with numbers of particle, volume and temperature fixed (NVT) molecular dynamic simulations. Our study indicates that phonon-phonon interaction causes the renormalized phonon frequencies of wadsleyite decrease with temperature. This is consistent with the Raman experimental observation. The anharmonic free energy of wadsleyite is negative and its heat capacity at constant pressure can exceed the Dulong-Petit limit at high temperature. The anharmonicity still significantly affects thermodynamic properties of wadsleyite at pressure and temperature conditions correspond to the transition zone.
Thermodynamic properties of organic iodine compounds
NASA Astrophysics Data System (ADS)
Richard, Laurent; Gaona, Xavier
2011-11-01
A critical evaluation has been made of the thermodynamic properties reported in the literature for 43 organic iodine compounds in the solid, liquid, or ideal gas state. These compounds include aliphatic, cyclic and aromatic iodides, iodophenols, iodocarboxylic acids, and acetyl and benzoyl iodides. The evaluation has been made on the basis of carbon number systematics and group additivity relations, which also allowed to provide estimates of the thermodynamic properties of those compounds for which no experimental data were available. Standard molal thermodynamic properties at 25 °C and 1 bar and heat capacity coefficients are reported for 13 crystalline, 29 liquid, and 39 ideal gas organic iodine compounds, which can be used to calculate the corresponding properties as a function of temperature and pressure. Values derived for the standard molal Gibbs energy of formation at 25 °C and 1 bar of these crystalline, liquid, and ideal gas organic iodine compounds have subsequently been combined with either solubility measurements or gas/water partition coefficients to obtain values for the standard partial molal Gibbs energies of formation at 25 °C and 1 bar of 32 aqueous organic iodine compounds. The thermodynamic properties of organic iodine compounds calculated in the present study can be used together with those for aqueous inorganic iodine species to predict the organic/inorganic speciation of iodine in marine sediments and petroleum systems, or in the near- and far-field of nuclear waste repositories.
High-temperature thermodynamic properties of forsterite
Philippe Gillet; Pascal Richet; François Guyot; Guillaume Fiquet
1991-01-01
The high-temperature thermodynamic properties of forsterite were reviewed in the light of a new determination of the isobaric heat capacity (Cp), up to 1850 K, and Raman spectroscopic measurements, up to 1150 K and 10 GPa. The Cp measurements and available data on thermal expansion (alpha) and bulk modulus (K) show that the isochoric specific heat (Cnu) exceeds the harmonic
High temperature drop calorimetry and thermodynamic properties
Chandrasekhariah, M.S. [Houston Advanced Research Center, The Woodlands, TX (United States). Materials Science Research Center; Bautista, R.G. [Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering
1995-04-01
Experimental determination of thermodynamic properties (e.g. enthalpy of formation, heat capacity, Gibbs free energy, etc.) is still the recourse for accurate thermodynamic data for the condensed phases. Calorimetry is probably the best experimental method for their determination. Drop calorimetry in its various modifications is still the method of choice to determine the enthalpy functions for solids and liquids above 1,000 C. The conventional drop calorimeter for solids and a drop calorimeter coupled to an electromagnetic levitation coil useful for conductive samples in both the solid and molten phases are described. Experimental results obtained up to and above the melting point of rare earth metals are presented.
Thermodynamics and statistical mechanics. [thermodynamic properties of gases
NASA Technical Reports Server (NTRS)
1976-01-01
The basic thermodynamic properties of gases are reviewed and the relations between them are derived from the first and second laws. The elements of statistical mechanics are then formulated and the partition function is derived. The classical form of the partition function is used to obtain the Maxwell-Boltzmann distribution of kinetic energies in the gas phase and the equipartition of energy theorem is given in its most general form. The thermodynamic properties are all derived as functions of the partition function. Quantum statistics are reviewed briefly and the differences between the Boltzmann distribution function for classical particles and the Fermi-Dirac and Bose-Einstein distributions for quantum particles are discussed.
The calculation of thermodynamic properties of molecules.
van Speybroeck, Veronique; Gani, Rafiqul; Meier, Robert Johan
2010-05-01
Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain such quantities by computation are quantum mechanical methods and group contribution methods. Although a lot of progress was made over the last decade, for the majority of chemical species we are still quite a bit away from what is often referred to as chemical accuracy, i.e.'1 kcal mol(-1)'. Currently, for larger molecules the combination of group contribution methods with group additive values that are determined with the best available computational ab initio methods seems to be a viable alternative to obtain thermodynamic properties near chemical accuracy. New developments and full use of existing tools may lead to further improvements (critical review, 83 references). PMID:20419218
Thermodynamic Properties of Actinides and Actinide Compounds
NASA Astrophysics Data System (ADS)
Konings, Rudy J. M.; Morss, Lester R.; Fuger, Jean
The necessity of obtaining accurate thermodynamic quantities for the actinide elements and their compounds was recognized at the outset of the Manhattan Project, when a dedicated team of scientists and engineers initiated the program to exploit nuclear energy for military purposes. Since the end of World War II, both fundamental and applied objectives have motivated a great deal of further study of actinide thermodynamics. This chapter brings together many research papers and critical reviews on this subject. It also seeks to assess, to systematize, and to predict important properties of the actinide elements, ions, and compounds, especially for species in which there is significant interest and for which there is an experimental basis for the prediction.
On thermodynamical properties of dark energy
Gong, Y; Wang, B; Gong, Yungui; Wang, Anzhong; Wang, Bin
2006-01-01
We have investigated the thermodynamical properties of the dark energy. Assuming that the dark energy temperature $T\\sim a^{-n}$ and considering that the universe volume enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For the dark energy with constant equation of state $w>-1$ and the generalized Chaplygin gas dark energy models, the derived entropy can be positive and satisfy the entropy bound. The total entropy, including those of the dark energy, the thermal radiation and the geometric entropy on the apparent horizon, satisfies the generalized second law of thermodynamics. However, for the phantom dark energy with constant equation of state, the positivity of entropy, the entropy bound and the generalized second law cannot be satisfied simultaneously.
Thermodynamic properties of eight fluorinated olefins
J. Steven Brown; Claudio Zilio; Alberto Cavallini
2010-01-01
Group contribution methods are used to predict the critical temperatures, critical pressures, critical densities, acentric factors, and ideal gas specific heats at constant pressure for eight fluorinated olefins, namely: R-1225ye(E), R-1225ye(Z), R-1225zc, R-1234ye(E), R-1234yf, R-1234ze(E), R-1234ze(Z), and R-1243zf. For the same eight refrigerants, the Peng–Robinson equation of state is used to predict thermodynamic properties, which are presented in pressure-enthalpy and
Thermodynamic properties of a dipolar Fermi gas
Zhang, J.-N.; Yi, S. [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2010-03-15
Based on the semiclassical theory, we investigate the thermodynamic properties of a dipolar Fermi gas. Through a self-consistent procedure, we numerically obtain the phase-space distribution function at finite temperature. We show that the deformations in both momentum and real space become smaller and smaller as the temperature is increased. For the homogeneous case, we also calculate pressure, entropy, and heat capacity. In particular, at the low-temperature limit and in the weak interaction regime, we obtain an analytic expression for the entropy which agrees qualitatively with our numerical result. The stability of a trapped gas at finite temperature is also explored.
Thermodynamic properties of benzene under shock conditions.
Maillet, Jean-Bernard; Pineau, Nicolas
2008-06-14
We present in this paper a thermodynamic analysis of benzene properties under shock conditions as given by molecular dynamics (MD) simulations. Reactive MD simulations of benzene predict a decomposition threshold corresponding to the flection point on the experimental Hugoniot curve. A polymerlike carbonated structure is observed for pressures above this threshold, but the calculated Hugoniot curve is in disagreement with the experimental one at high pressure. On the contrary, a system consisting of a diamond cluster in hydrogen gas leads to a correct prediction of the pressure on the Hugoniot curves. The central question is then linked to the kinetics of the transition between the polymerlike structure and the diamond cluster. PMID:18554024
Prediction of thermodynamic properties of coal derivatives
Donohue, M.D.
1990-09-01
The purpose of this research program is to understand the relationship between macroscopic thermodynamic properties and the various types of intermolecular forces. Since coal-derived liquids contain a wide variety of compounds, a theory capable of successfully predicting the thermophysical properties for coal processes must take into account the molecular shapes and all significant intermolecular forces: dispersion forces, anisotropic forces due to dipoles and quadrupoles, as well as Lewis acid-base interactions. We have developed the Acid-Base-Perturbed-Anisotropic-Chain Theory (ABPACT), a comprehensive theory that is capable of predicting the thermophysical properties for many systems where these different intermolecular forces are present. The ABPACT can treat non-polar compounds, polar compounds and compounds that associate through Lewis acid-base interactions. In addition to our theoretical work, we have used computer simulations to evaluate (and in some cases correct) the assumptions made in this theory. We also have conducted experiments to help us better understand the interplay of different kinds of interactions in multicomponent mixtures.
Thermodynamic properties of a Kerr nonlinear blackbody.
Cheng, Ze
2012-11-01
Within the framework of quantum field theory, we present the superfluid state of photons in a blackbody whose interior is filled by a Kerr nonlinear crystal. The thermodynamic properties of a Kerr nonlinear blackbody are investigated. At the transition temperature, the Gibbs free energy of the two phases is continuous but the entropy density of the two phases is discontinuous. Hence, there is a jump in the entropy density and this leads to a latent heat density. The photon system undergoes a first-order phase transition from the normal to the superfluid state. The transition temperature is characteristic of a concrete crystal. The entropy density and specific heat capacity are monotonically increasing functions of the temperature but are monotonically decreasing functions of the Kerr nonlinear coefficient. PMID:23214733
Prediction of thermodynamic properties of coal derivatives
Donohue, M.D.
1992-11-01
The purpose of this research program is to understand and model the effect of the different intermolecular forces on the thermodynamic properties of systems containing pure compounds and mixtures. The compounds under consideration vary considerably in size, shape and energy. Therefore in order to develop a theory capable of describing accurately the thermodynamic properties and phase behavior of such systems over a wide range of temperature and pressure, one has to take into account explicitly the differences in shape and size among the various compounds as well as the different type of intermolecular interactions. We have developed equations of state for pure-component chain molecules. We have shown that the excellent performance of complicated theories such as the Generalized Flory Dimer (GFD) theory can be mimicked by simpler equations, if certain assumptions for the shape parameters are made. We developed engineering correlations based on the GFD theory, using local composition theory to take into account the attractive contribution. We compared various methods for the calculation of the repulsive and attractive contributions against computer simulation data for hard and square-well chains, and experimental data from the literature. We also have studied microstructure and local order in fluids that contain asymmetric molecules. In addition, simple cubic equations of state have been applied to calculate physical and chemical-reaction equilibria in non-ideal systems. In order to obtain a better understanding of the intermolecular forces and to test some of our recent models, we have performed considerable experimental work. We used FT-IR to examine the self-association of aliphatic alcohols due to hydrogen bonding. In addition, FT-IR spectroscopy was used to investigate Lewis acid-base interactions between probe and entrainer-cosolvent molecules.
EXTENDING THE PREDICTION OF THE THERMODYNAMIC PROPERTIES OF CLAY
Paris-Sud XI, Université de
EXTENDING THE PREDICTION OF THE THERMODYNAMIC PROPERTIES OF CLAY MINERALS TO THE TRAPPING OF TRACE The thermodynamic properties of clay minerals, which control the stability of these minerals in solution, are still are parameterised using a given set of minerals. For clay minerals, the latter are mainly composed by Si, Al, Fe
THERMODYNAMIC AND TRANSPORT PROPERTIES OF SODIUM LIQUID AND VAPOR
Kemner, Ken
THERMODYNAMIC AND TRANSPORT PROPERTIES OF SODIUM LIQUID AND VAPOR ANL/RE-95/2 Reactor Engineering;Thermodynamic and Transport Properties of Sodium Liquid and Vapor ANL/RE-95/2 by J. K. Fink and L. Leibowitz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Vapor
Paris-Sud XI, UniversitÃ© de
Pairing correlations and thermodynamic properties of inner crust matter 1 Chapter 1 PAIRING CORRELATIONS AND THERMODYNAMIC PROPERTIES OF INNER CRUST MATTER JÂ´er^ome Margueron1 and Nicolae Sandulescu2 1 properties of inner crust matter is still missing. The scope of this chapter is to show how the HFB approach
Universal relation for size dependent thermodynamic properties of metallic nanoparticles.
Xiong, Shiyun; Qi, Weihong; Cheng, Yajuan; Huang, Baiyun; Wang, Mingpu; Li, Yejun
2011-06-14
The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values. PMID:21523307
Calculation of the standard molal thermodynamic properties of crystalline peptides
NASA Astrophysics Data System (ADS)
LaRowe, Douglas E.; Dick, Jeffrey M.
2012-03-01
To augment the relatively sparse set of thermodynamic data available for high molecular weight biopolymers, group additivity algorithms have been developed to estimate the heat capacity power function coefficients and standard molal thermodynamic properties of crystalline peptides in the multitude of biogeochemical environments in which they are found. Group contributions representing the 20 common amino acids plus 5-hydroxylysine and 4-hydroxyproline for each coefficient and property were generated using the thermodynamic properties of crystalline amino acids, polypeptides and other organic compounds. These group contributions were in turn used to compute the thermodynamic properties of naturally occurring proteins that are found in a crystalline state in cells. The coefficients and properties of the model compounds, group contributions and proteins are tabulated. In a demonstration of the uncertainty of the thermodynamic properties of the groups generated in this study, experimentally determined heat capacities and entropies of crystalline homopolypeptides and proteins taken from the literature have been compared to estimates of these quantities. Additionally, standard molal volumes for 24 amino acids have been recalculated in light of inconsistencies in an earlier analysis, and the standard molal thermodynamic properties of aqueous and crystalline methionine at 25 °C and 0.1 MPa have been reassessed. Calculations of this kind can be carried out to thermodynamically describe the biogeochemical interactions throughout the broad range of environmental settings in which they are known to occur.
Measurement of Thermodynamic Properties of Titanium Aluminum Alloys
NASA Technical Reports Server (NTRS)
Mehrotra, Gopal
1995-01-01
This final report is a summary of the work done by Professor Mehrotra at NASA Lewis Research Center. He has worked extensively on the measurement of thermodynamic properties of titanium aluminum alloys over the past six years.
Composition and Thermodynamic Properties of Air in Chemical Equilibrium
NASA Technical Reports Server (NTRS)
Moeckel, W E; Weston, Kenneth C
1958-01-01
Charts have been prepared relating the thermodynamic properties of air in chemical equilibrium for temperatures to 15,000 degrees k and for pressures 10(-5) to 10 (plus 4) atmospheres. Also included are charts showing the composition of air, the isentropic exponent, and the speed of sound. These charts are based on thermodynamic data calculated by the National Bureau of Standards. (author)
Critical evaluation of the thermodynamic properties of molybdenum
A. Fernández Guillermet
1985-01-01
The thermodynamic properties and the pressure-temperature phase diagram of pure Mo have been evaluated from experimental information using thermodynamic models for the Gibbs energy of the individual phases. A set of parameters describing the Gibbs energy of the various phases as a function of temperature and pressure is presented. The agreement between experimental data and calculated values is satisfactory.
Thermodynamic properties of nuclear matter at finite temperature
V. Soma; P. Bozek
2006-09-17
A self-consistent approach based on finite temperature Green's functions is used to investigate thermodynamic properties of nuclear matter. The internal energy is derived from the diagrams associated to the interaction energy. Pressure and entropy up to T=20 MeV are obtained from the generating functional form of the thermodynamic potential.
Thermodynamic and transport properties of sodium liquid and vapor
Fink, J.K.; Leibowitz, L.
1995-01-01
Data have been reviewed to obtain thermodynamically consistent equations for thermodynamic and transport properties of saturated sodium liquid and vapor. Recently published Russian recommendations and results of equation of state calculations on thermophysical properties of sodium have been included in this critical assessment. Thermodynamic properties of sodium liquid and vapor that have been assessed include: enthalpy, heat capacity at constant pressure, heat capacity at constant volume, vapor pressure, boiling point, enthalpy of vaporization, density, thermal expansion, adiabatic and isothermal compressibility, speed of sound, critical parameters, and surface tension. Transport properties of liquid sodium that have been assessed include: viscosity and thermal conductivity. For each property, recommended values and their uncertainties are graphed and tabulated as functions of temperature. Detailed discussions of the analyses and determinations of the recommended equations include comparisons with recommendations given in other assessments and explanations of consistency requirements. The rationale and methods used in determining the uncertainties in the recommended values are also discussed.
Thermodynamic properties of the Co-W-C system
Armando Fernández Guillermet
1989-01-01
The thermodynamic properties of the Co-W-C system have been evaluated by using the CALPHAD method. The properties of the Co-C\\u000a and W-C systems are taken from recent analyses, whereas the properties of the Co-W system are evaluated in the first part\\u000a of the present work. In particular, the effect of W in decreasing the Curie temperature of fcc Co (Tc)
Thermodynamic property determination in low gravity
NASA Technical Reports Server (NTRS)
Margrave, J. L.
1977-01-01
Techniques for determining heat capacities and other properties of molten metals were investigated and critically evaluated. Precisely determining heat capacities calorimetrically in space poses several problems. The weight of a drop calorimeter block along with the necessity of obtaining a large number of data points tend to make traditional approaches appear infeasible. However, for many substances exhibiting sufficiently high thermal conductivities and with known emissivities, it appears possible to investigate their properties by observing the rate of cooling of a levitated sphere which is initially at a uniform temperature above the melting point. A special advantage of the levitation method is that considerable supercooling is expected, making the study of the heat capacities of molten metals both above and below their melting points possible.
Thermodynamical properties of graphene in noncommutative phase-space
NASA Astrophysics Data System (ADS)
Santos, Victor; Maluf, R. V.; Almeida, C. A. S.
2014-10-01
We investigated the thermodynamic properties of graphene in a noncommutative phase-space in the presence of a constant magnetic field. In particular, we determined the behaviour of the main thermodynamical functions: the Helmholtz free energy, the mean energy, the entropy and the specific heat. The high temperature limit is worked out and the thermodynamic quantities, such as mean energy and specific heat, exhibit the same features as the commutative case. Possible connections with the results already established in the literature are discussed briefly.
Thermodynamical properties of graphene in noncommutative phase-space
Victor Santos; R. V. Maluf; C. A. S. Almeida
2014-07-28
We investigated the thermodynamic properties of graphene in a noncommutative phase-space in the presence of a constant magnetic field. In particular, we determined the behaviour of the main thermodynamical functions: the Helmholtz free energy, the mean energy, the entropy and the specific heat. The high temperature limit is worked out and the thermodynamic quantities, such as mean energy and specific heat, exhibit the same features as the commutative case. Possible connections with the results already established in the literature are discussed briefly.
A Theoretical Survey of DNA Oligomers Thermodynamic Properties
NASA Astrophysics Data System (ADS)
Koehler, Ryan; Peyret, Nicolas
2002-08-01
Central to numerous techniques of molecular biology, some ubiquitous as PCR and Southern blotting, is the design of oligonucleotide probes possessing specific thermodynamic properties. Calculations of oligonucleotide thermodynamics, based on the nearest-neighbor model, have become increasingly accurate and have been extended to include not only canonical duplexes but also duplexes with mismatches. Here we use validated theoretical methods to explore the general behavior of melting temperature (Tm), free energy, and hybridization propensity in response to changes in experimental conditions and sequence. Distributions of these thermodynamic quantities are presented for DNA sequences of 5 to 50 bases sampled from the human genome. The effects of concentrations (oligonucleotide, cations), temperature, sequence composition constrains, and introduction of mismatches are considered. Thermodynamic quantities were computed using specially built softwares to facilitate our length sampling strategy. Our results provide a general survey of typical and limiting thermodynamic values that will be useful for the wide range of applications that rely on DNA probe design.
Thermodynamic Properties of Gaseous Strontium and Barium Ferrates
V. L. Stolyarova; S. I. Lopatin; S. M. Shugurov
2004-01-01
Study of vaporization and thermodynamic properties in complex oxide systems containing FeO is of considerable interest for consideration of high-temperature processes that accompany the interaction of fuel and construction materials in nuclear reactors under extreme conditions. Studying the reactivity of oxides in vapor showed that gaseous iron oxide (FeO) should exhibit amphoteric properties and react with both anion- and cationforming
Kinetic and thermodynamic properties of moganite, a novel silica polymorph
Sigurdur R. Gíslason; Peter J. Heaney; Eric H. Oelkers; Jacques Schott
1997-01-01
A growing body of evidence reveals that much of the silica that crystallizes at the Earth's surface is a finely intergrown mixture of quartz and moganite. To better understand the behaviour of both solid and aqueous silica in these systems, the kinetics and thermodynamic properties for endmember moganite have been determined as a function of temperature from 25° to 200°C.
Reference Fluid Thermodynamic and Transport Properties Database (REFPROP)
National Institute of Standards and Technology Data Gateway
SRD 23 NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP) (PC database for purchase) NIST 23 contains revised data in a Windows version of the database, including 105 pure fluids and allowing mixtures of up to 20 components. The fluids include the environmentally acceptable HFCs, traditional HFCs and CFCs and 'natural' refrigerants like ammonia
Thermodynamic properties of fluids from Fluctuation Solution Theory
O`Connell, J.P.
1990-12-31
Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.
Thermodynamic properties of fluids from Fluctuation Solution Theory
O'Connell, J.P.
1990-01-01
Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.
Diameter-dependent thermodynamic and elastic properties of metallic nanoparticles
NASA Astrophysics Data System (ADS)
Chandra, Jeewan; Kholiya, Kuldeep
2015-04-01
A simple theoretical model has been proposed to study the diameter-dependent properties of metallic nanoparticles, i.e. Ag, Au, Al, Ni, Pb, Cu and Fe. The diameter-dependent thermodynamic properties includes melting temperature, Debye temperature, evaporation temperature, melting enthapy and melting entropy. The model is also extended to study the diameter-dependent elastic properties including bulk modulus, Young's modulus and thermal expansion coefficient. On comparison with available experimental findings and other theoretical approaches, the results obtained with the present formulation depict a close agreement and demonstrate the validity of the method proposed in the present paper.
Non-LTE thermodynamic properties for combustion processes
Fentress, M.L.; Eddy, T.L.
1987-09-01
The nonequilibrium thermodynamic properties of a product-gas derived from fluidized combustion of Pittsburgh seam coal is obtained using a multitemperature statistical thermodynamic computer model. Concentrations of 18 species are determined as a function of translational temperature (500 < T < 2500 K), pressure (0.1, 1.0, and 10 atm), and vibrational-to-translational temperature ratios of 0.5, 1, 2, and 5. The rotational and electronic excitation temperatures are assumed equal to the translational temperature. The partition functions and usual thermodynamic properties are also calculated and a nonequilibrium Mollier diagram is presented. The multitemperature model assumes chemical equilibrium and therefore represents a first step in describing nonequilibrium combustion reactions in a semiclassical manner. The model can be applied to reactions via chemical kinetics and/or an extension to a multichemical nonequilibrium model. The results indicate the relative concentration of species usually considered to be pollutants, under the range of conditions examined.
Thermodynamic properties of rubidium niobium tungsten oxide
Aleksandr Knyazev; Miros?aw M?czka; Nataliya Kuznetsova; Jerzy Hanuza; Aleksey Markin
2009-01-01
In the present work temperature dependence of heat capacity of rubidium niobium tungsten oxide has been measured first in\\u000a the range from 7 to 395 K and then between 390 and 650 K, respectively, by precision adiabatic vacuum and dynamic calorimetry.\\u000a The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity $$ C_{\\\\text{p}}^{\\\\text{o}} (T), $$ enthalpy $$ H^{\\\\text{o}}
Thermodynamic properties of vanadium-tellurium alloys
Herbert Ipser
1984-01-01
Tellurium vapor pressures of vanadium-tellurium alloys were determined in the range of the NiAs-derivative structures between 765 and 1365 K and between 54 and 66.7 at.% Te by an isopiestic method. The partial molar thermodynamic quantities of tellurium were derived; they indicate the appearance of a miscibility gap below about 825 K with a critical point around 64.7 at.% Te.
Thermodynamic properties of vanadium-tellurium alloys
NASA Astrophysics Data System (ADS)
Ipser, Herbert
1984-08-01
Tellurium vapor pressures of vanadium-tellurium alloys were determined in the range of the NiAs-derivative structures between 765 and 1365 K and between 54 and 66.7 at.% Te by an isopiestic method. The partial molar thermodynamic quantities of tellurium were derived; they indicate the appearance of a miscibility gap below about 825 K with a critical point around 64.7 at.% Te. The solidus line was estimated between 773 and 1273 K from the tellurium activities and the experimentally determined liquidus line; good agreement was found between the calculated values and those obtained from differential thermal analysis.
Thermodynamic properties of vanadium-tellurium alloys
Ipser, H.
1984-01-01
Tellurium vapor pressures of vanadium-tellurium alloys were determined in the range of the NiAs-derivative structures between 765 and 1365 K and between 54 and 66.7 at.% Te by an isopiestic method. The partial molar thermodynamic quantities of tellurium were derived; they indicate the appearance of a miscibility gap below about 825 K with a critical point around 64.7 at.% Te. The solidus line was estimated between 773 and 1273 K from the tellurium activities and the experimentally determined liquidus line; good agreement was found between the calculated values and those obtained from differential thermal analysis.
Intermolecular interactions and the thermodynamic properties of supercritical fluids.
Yigzawe, Tesfaye M; Sadus, Richard J
2013-05-21
The role of different contributions to intermolecular interactions on the thermodynamic properties of supercritical fluids is investigated. Molecular dynamics simulation results are reported for the energy, pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound of fluids interacting via both the Lennard-Jones and Weeks-Chandler-Andersen potentials. These properties were obtained for a wide range of temperatures, pressures, and densities. For each thermodynamic property, an excess value is determined to distinguish between attraction and repulsion. It is found that the contributions of intermolecular interactions have varying effects depending on the thermodynamic property. The maxima exhibited by the isochoric and isobaric heat capacities, isothermal compressibilities, and thermal expansion coefficient are attributed to interactions in the Lennard-Jones well. Repulsion is required to obtain physically realistic speeds of sound and both repulsion and attraction are necessary to observe a Joule-Thomson inversion curve. Significantly, both maxima and minima are observed for the isobaric and isochoric heat capacities of the supercritical Lennard-Jones fluid. It is postulated that the loci of these maxima and minima converge to a common point via the same power law relationship as the phase coexistence curve with an exponent of ? = 0.32. This provides an explanation for the terminal isobaric heat capacity maximum in supercritical fluids. PMID:23697423
Intermolecular interactions and the thermodynamic properties of supercritical fluids
NASA Astrophysics Data System (ADS)
Yigzawe, Tesfaye M.; Sadus, Richard J.
2013-05-01
The role of different contributions to intermolecular interactions on the thermodynamic properties of supercritical fluids is investigated. Molecular dynamics simulation results are reported for the energy, pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound of fluids interacting via both the Lennard-Jones and Weeks-Chandler-Andersen potentials. These properties were obtained for a wide range of temperatures, pressures, and densities. For each thermodynamic property, an excess value is determined to distinguish between attraction and repulsion. It is found that the contributions of intermolecular interactions have varying effects depending on the thermodynamic property. The maxima exhibited by the isochoric and isobaric heat capacities, isothermal compressibilities, and thermal expansion coefficient are attributed to interactions in the Lennard-Jones well. Repulsion is required to obtain physically realistic speeds of sound and both repulsion and attraction are necessary to observe a Joule-Thomson inversion curve. Significantly, both maxima and minima are observed for the isobaric and isochoric heat capacities of the supercritical Lennard-Jones fluid. It is postulated that the loci of these maxima and minima converge to a common point via the same power law relationship as the phase coexistence curve with an exponent of ? = 0.32. This provides an explanation for the terminal isobaric heat capacity maximum in supercritical fluids.
Thermodynamical Property of Entanglement Entropy for Excited States
Bhattacharya, Jyotirmoy; Takayanagi, Tadashi; Ugajin, Tomonori
2012-01-01
We argue that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. We derive the results using holography and confirm them in two dimensional field theories. We will also comment on an example with negative specific heat and suggest a connection between the second law of thermodynamics and the strong subadditivity of entanglement entropy.
Thermodynamical Property of Entanglement Entropy for Excited States
Jyotirmoy Bhattacharya; Masahiro Nozaki; Tadashi Takayanagi; Tomonori Ugajin
2012-12-05
We argue that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. We derive the results using holography and confirm them in two dimensional field theories. We will also comment on an example with negative specific heat and suggest a connection between the second law of thermodynamics and the strong subadditivity of entanglement entropy.
Thermodynamical property of entanglement entropy for excited states.
Bhattacharya, Jyotirmoy; Nozaki, Masahiro; Takayanagi, Tadashi; Ugajin, Tomonori
2013-03-01
We argue that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. We derive the results using holography and confirm them in two-dimensional field theories. We will also comment on an example with negative specific heat and suggest a connection between the second law of thermodynamics and the strong subadditivity of entanglement entropy. PMID:23496702
Thermodynamic and melting properties of RDX at elevated pressures
NASA Technical Reports Server (NTRS)
Carlson, D. W.; Nauflett, G. W.; Brasch, J. W., Sr.; Austin, T. D.
1980-01-01
The laboratory set up for determination of melting and thermodynamic properties of RDX using a diamond anvil cell apparatus capable of pressures exceeding 10 kbar and 250 C is described. The slope of the melting temperature versus applied pressure curve for RDX, as determined in the diamond cell, was found to equal 4.09 + or - 0.6 C (kbar). The density of liquid RDX at its melting point was calculated from this slope to be approximately 1.63 gm/cu cm. Practical and theoretical considerations in using the diamond anvil cell to generate thermodynamic data on RDX are discussed.
Thermodynamic properties of massive dilaton black holes, 2
Tamaki, T
2002-01-01
We numerically reanalyze static and spherically symmetric black hole solutions in an Einstein-Maxwell-dilaton system with a dilaton potential $m_{d}^{2}\\phi^{2}$. We investigate thermodynamic properties for various dilaton coupling constants and find that thermodynamic properties change at a critical dilaton mass $m_{d,crit}$. For $m_{d}\\geq m_{d,crit}$, the black hole becomes an extreme solution for a nonzero horizon radius $r_{h,ex}$ as the Reissner-Nordstr\\"om black hole. However, if $m_{d}$ is nearly equal to $m_{d,crit}$, there appears a solution of smaller horizon radius than $r_{h,ex}$. For $m_{d}
Thermodynamic properties and diffusion of water + methane binary mixtures
Shvab, I.; Sadus, Richard J., E-mail: rsadus@swin.edu.au [Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218 Hawthorn, Victoria 3122 (Australia)
2014-03-14
Thermodynamic and diffusion properties of water + methane mixtures in a single liquid phase are studied using NVT molecular dynamics. An extensive comparison is reported for the thermal pressure coefficient, compressibilities, expansion coefficients, heat capacities, Joule-Thomson coefficient, zero frequency speed of sound, and diffusion coefficient at methane concentrations up to 15% in the temperature range of 298–650 K. The simulations reveal a complex concentration dependence of the thermodynamic properties of water + methane mixtures. The compressibilities, heat capacities, and diffusion coefficients decrease with increasing methane concentration, whereas values of the thermal expansion coefficients and speed of sound increase. Increasing methane concentration considerably retards the self-diffusion of both water and methane in the mixture. These effects are caused by changes in hydrogen bond network, solvation shell structure, and dynamics of water molecules induced by the solvation of methane at constant volume conditions.
Thermodynamic properties of liquid water from a polarizable intermolecular potential
NASA Astrophysics Data System (ADS)
Yigzawe, Tesfaye M.; Sadus, Richard J.
2013-01-01
Molecular dynamics simulation results are reported for the pressure, isothermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient and speed of sound of liquid water using a polarizable potential [Li et al., J. Chem. Phys. 127, 154509 (2007)]. These properties were obtained for a wide range of temperatures and pressures at a common liquid density using the treatment of Lustig [J. Chem. Phys. 100, 3048 (1994)] and Meier and Kabelac [J. Chem. Phys. 124, 064104 (2006)], whereby thermodynamic state variables are expressible in terms of phase-space functions determined directly from molecular dynamics simulations. Comparison with experimental data indicates that the polarizable potential can be used to predict most thermodynamic properties with a very good degree of accuracy.
ms2: A molecular simulation tool for thermodynamic properties
Stephan Deublein; Bernhard Eckl; Jürgen Stoll; Sergey V. Lishchuk; Gabriela Guevara-Carrion; Colin W. Glass; Thorsten Merker; Martin Bernreuther; Hans Hasse; Jadran Vrabec
2011-01-01
This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of bulk fluids in equilibrium consisting of small electro-neutral molecules. ms2 features the two main molecular simulation techniques, molecular dynamics (MD) and Monte-Carlo. It supports the calculation of vapor–liquid equilibria of pure fluids and multi-component mixtures described by rigid molecular models on the
Coefficients for calculating thermodynamic and transport properties of individual species
Bonnie J. McBride; Sanford Gordon; Martin A. Reno
1993-01-01
Libraries of thermodynamic data and transport properties are given for individual species in the form of least-squares coefficients. Values of C(sup 0)(sub p)(T), H(sup 0)(T), and S(sup 0)(T) are available for 1130 solid, liquid, and gaseous species. Viscosity and thermal conductivity data are given for 155 gases. The original C(sup 0)(sub p)(T) values were fit to a fourth-order polynomial with
Thermodynamic and Transport Properties of Two-temperature Oxygen Plasmas
S. Ghorui; Joachim V. R. Heberlein; E. Pfender
2007-01-01
Thermodynamic and transport properties of two-temperature oxygen plasmas are presented. Variation of species densities, mass\\u000a densities, specific heat, enthalpy, viscosity, thermal conductivity, collision frequency and electrical conductivity as a\\u000a function of temperature, pressure and different degree of temperature non-equilibrium are computed. Reactional, electronic\\u000a and heavy particle components of the total thermal conductivity are discussed. To meet practical needs of fluid-dynamic
Thermodynamic and magnetocaloric properties of geometrically frustrated Ising nanoclusters
NASA Astrophysics Data System (ADS)
Žukovi?, M.
2015-01-01
Thermodynamic and magnetocaloric properties of geometrically frustrated Ising spin clusters of selected shapes and sizes are studied by exact enumeration. In the ground state the magnetization and the entropy show step-wise variations with an applied magnetic field. The number of steps, their widths and heights depend on the cluster shape and size. While the character of the magnetization plateau heights is always increasing, the entropy is not necessarily decreasing function of the field, as one would expect. For selected clusters showing some interesting ground-state properties, the calculations are extended to finite temperatures by exact enumeration of densities of states in the energy-magnetization space. In zero field the focus is laid on a peculiar behavior of some thermodynamic quantities, such as the entropy, the specific heat and the magnetic susceptibility. In finite fields various thermodynamic functions are studied in the temperature-field parameter plane and particular attention is paid to the cases showing an enhanced magnetocaloric effect. The exact results on the finite clusters are compared with the thermodynamic limit behavior obtained from Monte Carlo simulations.
ERIC Educational Resources Information Center
Piele, Philip K.
Several court cases involving acquisition, use, and disposal of property by institutions of higher education are briefly summarized in this chapter. Cases discussed touch on such topics as municipal annexation of university property; repurchase of properties temporarily allocated to faculty members; implications of zoning laws and zoning board…
Detection of DNA Hybridization Properties Using Thermodynamic Method
NASA Astrophysics Data System (ADS)
Kim, Do-Kyun; Kwon, Young-Soo; Takamura, Yuzuru; Tamiya, Eiichi
2006-01-01
The determination of DNA hybridization reaction can apply the molecular biology research, clinic diagnostics, bioengineering, environment monitoring, food science and application area. So, the improvement of DNA hybridization detection method is very important for the determination of hybridization reaction. Several molecular biological techniques require accurate predictions of match versus mismatch hybridization thermodynamics, such as polymerase chain reaction (PCR), sequencing by hybridization, gene diagnostics and antisense DNA probes. In addition, recent developments of DNA chip array as means for biochemical assays and DNA sequencing requires accurate knowledge of hybridization thermodynamics and population ratios at match and mismatch target sites. In this study, we report the properties of the probe oligonucleotide and match, mismatch target oligonucleotide hybridization reaction using thermodynamic method. Thermodynamics of 5'-oligonucleotides with central and terminal mismatch sequences are obtained by measuring UV-absorbance as a function of temperature. The data show that the nearest-neighbor base-pair model is adequate for predicting thermodynamics of oligonucleotides with average deviations for enthalpy (? H0), entropy (? S0), free energy change at 37°C (?{G37}0) and melting temperature (Tm), respectively.
Structural and thermodynamics properties of organo-modified montmorillonite clay
NASA Astrophysics Data System (ADS)
Anoukou, K.; Zaoui, A.; Zaïri, F.; Naït-Abdelaziz, M.; Gloaguen, J. M.
2015-01-01
Polymer clay nanocomposites (PCNs) have been seen as the most novel materials in engineering applications since they exhibit significant improvement in mechanical and physical properties. Indeed, with few amount of organoclay, PCNs exhibit enhanced mechanical, optical, thermal and liquid or gas barrier properties compared to pure polymers and to their counterpart microcomposites. Thus, organoclays are extensively used as precursors in the preparation of PCNs. They are the best candidate in reinforcing PCNs because of the lightweight and the high availability of clay minerals in the nature. However, structure and physical phenomena arising at molecular level in organoclays, and subsequently in PCNs, are not completely or difficultly accessible with existing experimental techniques. In this work, molecular dynamics (MD) simulation was conducted using the combination of two force fields (CLAYFF and CHARMM) to evaluate the thermodynamics and structural properties of organoclay such as heat capacities, isothermal bulk modulus, density, basal spacing and chains arrangement in the interlayer spacing. Our results regarding the basal spacing and density are in fairly good agreement with available experimental data. This allows us to validate the use of the two force fields to represent interactions in organoclays. The effect of the cation exchange capacity (CEC) on the basal spacing and the thermodynamics properties is assessed. We found, through our MD simulation, that the calculated isothermal bulk modulus is in good agreement with the density value of organoclays with two different CEC.
Standard Chemical Thermodynamic Properties of Alkanethiol Isomer Groups
NASA Astrophysics Data System (ADS)
Alberty, Robert A.; Burmenko, Ellen; Kang, Tae H.; Chung, Michael B.
1987-04-01
The chemical thermodynamic properties of alkanethiol (RSH where R is an alkyl group) isomer groups from CH4S to C4H10S in the ideal gas phase have been calculated from 298.15 to 1000 K from tables of Stull, Westrum, and Sinke. In the absence of literature data on all isomers of higher isomer groups, the properties of isomers of C5H12S to C8H18S have been estimated using Benson group values. Equilibrium mole fractions within isomer groups have been calculated for the ideal gas state from 298.15 to 1000 K. For isomer group properties, increments per carbon atom have been calculated to show the extent to which thermodynamic properties of higher isomer groups may be obtained by linear extrapolation. Values of C?P, S°, ?fH°, and ?fG° are given for all species of alkanethiols from CH4S to C8H18S in SI units for a standard state pressure of 1 bar.
Optical and thermodynamic property measurements of liquid metals and alloys
NASA Technical Reports Server (NTRS)
Weber, J. K. R.; Krishnan, Shankar; Schiffman, Robert A.; Nordine, Paul C.
1991-01-01
Optical properties and spectral emissivities of liquid silicon, titanium, niobium, and zirconium were investigated by HeNe laser polarimetry at 632.8 nm. The metals were of a high purity and, except for zirconium, clean. The more demanding environmental requirements for eliminating oxide or nitride phases from zirconium were not met. Containerless conditions were achieved by electromagnetic levitation and heating. CO2 laser beam heating was also used to extend the temperature range for stable levitation and to heat solid silicon to form the metallic liquid phase. Corrections to previously reported calorimetric measurements of the heat capacity of liquid niobium were derived from the measured temperature dependence of its spectral emissivity. Property measurements were obtained for supercooled liquid silicon and supercooling of liquid zirconium was accomplished. The purification of liquid metals and the extension of this work on liquids to the measurement of thermodynamic properties and phase equilibria are discussed.
Thermodynamic properties of asymptotically Reissner–Nordström black holes
Hendi, S.H., E-mail: hendi@shirazu.ac.ir
2014-07-15
Motivated by possible relation between Born–Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner–Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariant metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points. -- Highlights: •We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. •We investigate thermodynamic stability and discuss about the size of stable black holes. •We obtain analytical solutions of higher dimensional theory.
Thermodynamic properties of liquid gallium from picosecond acoustic velocity measurements
NASA Astrophysics Data System (ADS)
Ayrinhac, S.; Gauthier, M.; Le Marchand, G.; Morand, M.; Bergame, F.; Decremps, F.
2015-07-01
Due to discrepancies in the literature data the thermodynamic properties of liquid gallium are still in debate. Accurate measurements of adiabatic sound velocities as a function of pressure and temperature have been obtained by the combination of laser picosecond acoustics and surface imaging on sample loaded in diamond anvil cell. From these results the thermodynamic parameters of gallium have been extracted by a numerical procedure up to 10 GPa and 570 K. It is demonstrated that a Murnaghan equation of state accounts well for the whole data set since the isothermal bulk modulus BT has been shown to vary linearly with pressure in the whole temperature range. No evidence for a previously reported liquid–liquid transition has been found in the whole pressure and temperature range explored.
Thermodynamic properties of liquid gallium from picosecond acoustic velocity measurements.
Ayrinhac, S; Gauthier, M; Le Marchand, G; Morand, M; Bergame, F; Decremps, F
2015-07-15
Due to discrepancies in the literature data the thermodynamic properties of liquid gallium are still in debate. Accurate measurements of adiabatic sound velocities as a function of pressure and temperature have been obtained by the combination of laser picosecond acoustics and surface imaging on sample loaded in diamond anvil cell. From these results the thermodynamic parameters of gallium have been extracted by a numerical procedure up to 10 GPa and 570 K. It is demonstrated that a Murnaghan equation of state accounts well for the whole data set since the isothermal bulk modulus BT has been shown to vary linearly with pressure in the whole temperature range. No evidence for a previously reported liquid-liquid transition has been found in the whole pressure and temperature range explored. PMID:26061830
ERIC Educational Resources Information Center
Bickel, Robert D.; Zeller, Trisha A.
A number of cases related to property issues involving institutions of higher education are examined in this chapter. Cases discussed touch on such topics as funding for property and equipment acquisition; opposition to building construction or demolition; zoning issues; building construction and equipment contracts; and lease agreements. Current…
Phase Equilibria and Thermodynamic Properties in the Fe-Cr System
Wei Xiong; Malin Selleby; Qing Chen; Joakim Odqvist; Yong Du
2010-01-01
Phase equilibria and thermodynamic properties in the Fe-Cr system have been reviewed comprehensively based on experimental information and available computer simulations in different scales. The evaluated phase equilibria show significant differences from the currently accepted thermodynamic description by CALPHAD (calculation of phase diagram) approach. The thermodynamic properties of the Fe-Cr system, such as heat capacity, enthalpy, and activity, have been
Thermodynamic Properties of Organometallic Dihydrogen Complexes for Hydrogen Storage Applications
NASA Astrophysics Data System (ADS)
Abrecht, David Gregory
The mechanism and thermodynamic properties of hydrogen binding to the solid-state complexes [M(CO)dppe2][BArF24] (M = Mn, Re, Tc) and [M'Hdppe2][NTf2] (M' = Fe, Ru, Os) were investigated experimentally and computationally over the temperature range 298K-373K and pressure range 0-2800 torr, based on the Sieverts method. The bulk absorption behavior was found to be accurately described by Langmuir isotherms. Enthalpy and entropy values of ?H° = -52.2 kJ/mol and ?S° = -99.6 J/mol-K were obtained experimentally for hydrogen absorption onto [Mn(CO)dppe2][BArF24] from the Langmuir equilibrium constant, and values obtained from electronic structure calculations using the LANL2DZ-ECP basis set were found to successfully reproduce both the pressure-temperature-composition behavior and the thermodynamic values to within 5% of those obtained through experiment. Results from simulations for all complexes yielded large enthalpy values similar to metal hydride formation enthalpies for all complexes studied, and the substitution of the metal center reproduced qualitative binding strength trends of 5d>3d>4d consistent with those previously reported for the group 6 metals. X-ray diffraction patterns and Mössbauer spectra were taken to determine the thermal decomposition pathway for [FeH(?2-H 2)dppe2][NTf2]. Simulations at the B3LYP/TZVP level of theory and experimental Mössbauer spectra confirmed the direct thermal decomposition from singlet-state [FeH(?2-H 2)dppe2][NTf2] to triplet-state [FeHdppe 2][NTf2] under vacuum conditions at 398K. Evaluation of the partial quadrupole splitting values of Q(H2) = -0.245 mm/s from Mössbauer spectroscopy significantly differ from typical values obtained for hydrides, indicating an underutilized mechanism for identification of dihydrogen ligands. Singlet-state thermodynamic values from simulation were consistent with experimental observations for Ru and Os, and ruthenium complexes were found to have thermodynamic properties within appropriate ranges for hydrogen storage applications. Simulated thermodynamic values for Fe complexes were found to significantly underestimate experimental behavior, demonstrating the importance of the magnetic spin state of the molecule to hydrogen binding properties.
Thermodynamic properties of gases dissolved in electrolyte solutions.
NASA Technical Reports Server (NTRS)
Tiepel, E. W.; Gubbins, K. E.
1973-01-01
A method based on perturbation theory for mixtures is applied to the prediction of thermodynamic properties of gases dissolved in electrolyte solutions. The theory is compared with experimental data for the dependence of the solute activity coefficient on concentration, temperature, and pressure; calculations are included for partial molal enthalpy and volume of the dissolved gas. The theory is also compared with previous theories for salt effects and found to be superior. The calculations are best for salting-out systems. The qualitative feature of salting-in is predicted by the theory, but quantitative predictions are not satisfactory for such systems; this is attributed to approximations made in evaluating the perturbation terms.
Du, Yi; Cheng, Zhenxiang; Yu, Zhenwei; Dou, Shi Xue; Wang, Xiaolin; Liu, L Q
2012-02-01
A family of bismuth ferrites (BFO), including Bi2Fe4O9, BiFeO3, and Bi25FeO39 with different morphologies, has been prepared by the hydrothermal method assisted by different alkaline mineralizers. X-ray diffraction refinement calculations are carried out to study the crystal structures of bismuth ferrites. A thermodynamic calculation based on the dissolution-precipitation model was carried out to analyze the hydrothermal synthesis of BFO powders. Magnetic measurements of the obtained bismuth ferrites show different magnetic properties from 5 K to 350 K. PMID:22630029
Spectroscopic and thermodynamic properties of L-ornithine monohydrochloride
NASA Astrophysics Data System (ADS)
Raja, M. Dinesh; Kumar, C. Maria Ashok; Arulmozhi, S.; Madhavan, J.
2015-06-01
L-Ornithine Monohydrochloride (LOMHCL) has been investigated with the help of B3LYP density functional theory with 6-31 G (d, p) basis set. Fourier transform infrared and Fourier transform Raman spectra is to identify the various functional groups. The theoretical frequencies showed very good agreement with experimental values. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H) and temperatures. Second harmonic generation (SHG) efficiency of the grown crystal has been studied.
Thermodynamic properties of real gases and BWR equation of state
NASA Astrophysics Data System (ADS)
Vestfálová, Magda
2015-05-01
The fundamental base for the calculation of the thermodynamic properties of materials is thermal equation of state and dependence of some of the basic specific heat capacities on temperature. The dependence of the specific thermal capacity on the second independent variable (for example on the volume) it is already possible to deduce from the thermal equation of state. The aim of this paper is to assess the compliance values of specific heat capacity which was calculated using the BWR thermal equation of the state and experimentally obtained known values of specific heat capacity for the substance, whose characteristics are available in a wide range of state space.
2014-01-01
This work has considered the intrinsic influence of bond energy on the macroscopic, thermodynamic, and mechanical properties of crystalline materials. A general criterion is proposed to evaluate the properties of nanocrystalline materials. The interrelation between the thermodynamic and mechanical properties of nanomaterials is presented and the relationship between the variation of these properties and the size of the nanomaterials is explained. The results of our work agree well with thermodynamics, molecular dynamics simulations, and experimental results. This method is of significance in investigating the size effects of nanomaterials and provides a new approach for studying their thermodynamic and mechanical properties. PMID:25288913
Thermodynamic properties of {sup 56,57}Fe
Algin, E. [Department of Physics, Eskisehir Osmangazi University, Meselik 26480 (Turkey); Agvaanluvsan, U. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Guttormsen, M.; Larsen, A. C.; Rekstad, J.; Siem, S. [Department of Physics, University of Oslo, N-0316 Oslo (Norway); Mitchell, G. E. [North Carolina State University, Raleigh, North Carolina 27695 (United States); Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708 (United States); Schiller, A.; Voinov, A. [Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States)
2008-11-15
Nuclear level densities for {sup 56,57}Fe have been extracted from the primary {gamma}-ray spectra using ({sup 3}He, {sup 3}He{sup '}{gamma}) and ({sup 3}He, {alpha}{gamma}) reactions. Nuclear thermodynamic properties for {sup 56}Fe and {sup 57}Fe are investigated using the experimental level densities. These properties include entropy, Helmholtz free energy, caloric curves, chemical potential, and heat capacity. In particular, the breaking of Cooper pairs and single-quasiparticle entropy are discussed and shown to be important concepts for describing nuclear level density. Microscopic model calculations are performed for level densities of {sup 56,57}Fe. The experimental and calculated level densities are compared. The average number of broken Cooper pairs and the parity distribution are extracted as a function of excitation energy for {sup 56,57}Fe from the model calculations.
Thermodynamic properties of small aggregates of rare-gas atoms
NASA Technical Reports Server (NTRS)
Etters, R. D.; Kaelberer, J.
1975-01-01
The present work reports on the equilibrium thermodynamic properties of small clusters of xenon, krypton, and argon atoms, determined from a biased random-walk Monte Carlo procedure. Cluster sizes ranged from 3 to 13 atoms. Each cluster was found to have an abrupt liquid-gas phase transition at a temperature much less than for the bulk material. An abrupt solid-liquid transition is observed for thirteen- and eleven-particle clusters. For cluster sizes smaller than 11, a gradual transition from solid to liquid occurred over a fairly broad range of temperatures. Distribution of number of bond lengths as a function of bond length was calculated for several systems at various temperatures. The effects of box boundary conditions are discussed. Results show the importance of a correct description of boundary conditions. A surprising result is the slow rate at which system properties approach bulk behavior as cluster size is increased.
Xu, Xiao Juan; Xiao, He Ming; Gong, Xue Dong; Ju, Xue Hai; Chen, Zhao Xu
2005-12-15
To look for high energy density materials (HEDM), the relationships between the structures and the performances of polynitroadamantanes (PNAs) were studied. The assigned infrared spectra of PNAs obtained at the density functional theory (DFT) B3LYP/6-31G level were used to compute the thermodynamic properties on the basis of the principle of statistical thermodynamics. The thermodynamic properties are linearly related with the number of nitro groups as well as with the temperatures. Detonation properties of PNAs were evaluated by using the Kamlet-Jacobs equation based on the calculated densities and heats of formation for titled compounds, and it is found that only when the number of nitro groups of PNA is equal to or more than eight can it be possible for PNAs to be used as HEDMs. The relative stabilities of PNAs were studied by the pyrolysis mechanism using the UHF-PM3 method. The homolysis of the C-NO2 bond is predicted to be the initial step of thermal decomposition. The activation energies (Ea) for the homolysis decrease with the number of nitro groups being increased on the whole. The stability order of dinitroadamantane isomers derived from the interactions among nitro groups is consistent with what is determined by Ea. The relations between the Ea's and the electronic structure parameters were discussed. In combination with the stability, PNA (1,2,3,4,5,6,7,8,9,10-) is recommended as the target of HEDM with insensitivity. PMID:16331911
Thermodynamic properties of pulverized coal during rapid heating devolatilization processes
Proscia, W.M.; Freihaut, J.D.
1993-03-01
Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is required both, for the fundamental determination of kinetic parameters of coal devolatilization, and to refine existing devolatilization sub-models used in comprehensive coal combustion codes. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Calibration of the heated grid calorimeter (Task 2) was completed this reporting period. Several refinements to the heated grid apparatus have been implemented which allow quantitative determination of sample heat capacity at high heating rates.
Solvation of polymers as mutual association. II. Basic thermodynamic properties.
Dudowicz, Jacek; Freed, Karl F; Douglas, Jack F
2013-04-28
The theory of equilibrium solvation of polymers B by a relatively low molar mass solvent A, developed in the simplest form in Paper I, is used to explore some essential trends in basic thermodynamic properties of solvated polymer solutions, such as the equilibrium concentrations of solvated polymers AiB and free solvent molecules A, the mass distribution ?(AiB)(i) of solvated clusters, the extent of solvation of the polymer ?(solv), the solvation transition lines T(solv)(?B(o)), the specific heat C(V), the osmotic second virial coefficient B2, phase stability boundaries, and the critical temperatures associated with closed loop phase diagrams. We discuss the differences between the basic thermodynamic properties of solvated polymers and those derived previously for hierarchical mutual association processes involving the association of two different species A and B into AB complexes and the subsequent polymerization of these AB complexes into linear polymeric structures. The properties of solvated polymer solutions are also compared to those for solutions of polymers in a self-associating solvent. Closed loop phase diagrams for solvated polymer solutions arise in the theory from the competition between the associative and van der Waals interactions, a behavior also typical for dispersed molecular and nanoparticle species that strongly associate with the host fluid. Our analysis of the temperature dependence of the second osmotic virial coefficient reveals that the theory must be generalized to describe the association of multiple solvent molecules with each chain monomer, and this complex extension of the present model will be developed in subsequent papers aimed at a quantitative rather than qualitative treatment of solvated polymer solutions. PMID:23635166
Solvation of polymers as mutual association. II. Basic thermodynamic properties
NASA Astrophysics Data System (ADS)
Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.
2013-04-01
The theory of equilibrium solvation of polymers B by a relatively low molar mass solvent A, developed in the simplest form in Paper I, is used to explore some essential trends in basic thermodynamic properties of solvated polymer solutions, such as the equilibrium concentrations of solvated polymers AiB and free solvent molecules A, the mass distribution ? _{{AiB}}(i) of solvated clusters, the extent of solvation of the polymer ?solv, the solvation transition lines T_{solv}(? _{{B}}o), the specific heat CV, the osmotic second virial coefficient B2, phase stability boundaries, and the critical temperatures associated with closed loop phase diagrams. We discuss the differences between the basic thermodynamic properties of solvated polymers and those derived previously for hierarchical mutual association processes involving the association of two different species A and B into AB complexes and the subsequent polymerization of these AB complexes into linear polymeric structures. The properties of solvated polymer solutions are also compared to those for solutions of polymers in a self-associating solvent. Closed loop phase diagrams for solvated polymer solutions arise in the theory from the competition between the associative and van der Waals interactions, a behavior also typical for dispersed molecular and nanoparticle species that strongly associate with the host fluid. Our analysis of the temperature dependence of the second osmotic virial coefficient reveals that the theory must be generalized to describe the association of multiple solvent molecules with each chain monomer, and this complex extension of the present model will be developed in subsequent papers aimed at a quantitative rather than qualitative treatment of solvated polymer solutions.
ms2: A molecular simulation tool for thermodynamic properties
NASA Astrophysics Data System (ADS)
Deublein, Stephan; Eckl, Bernhard; Stoll, Jürgen; Lishchuk, Sergey V.; Guevara-Carrion, Gabriela; Glass, Colin W.; Merker, Thorsten; Bernreuther, Martin; Hasse, Hans; Vrabec, Jadran
2011-11-01
This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of bulk fluids in equilibrium consisting of small electro-neutral molecules. ms2 features the two main molecular simulation techniques, molecular dynamics (MD) and Monte-Carlo. It supports the calculation of vapor-liquid equilibria of pure fluids and multi-component mixtures described by rigid molecular models on the basis of the grand equilibrium method. Furthermore, it is capable of sampling various classical ensembles and yields numerous thermodynamic properties. To evaluate the chemical potential, Widom's test molecule method and gradual insertion are implemented. Transport properties are determined by equilibrium MD simulations following the Green-Kubo formalism. ms2 is designed to meet the requirements of academia and industry, particularly achieving short response times and straightforward handling. It is written in Fortran90 and optimized for a fast execution on a broad range of computer architectures, spanning from single processor PCs over PC-clusters and vector computers to high-end parallel machines. The standard Message Passing Interface (MPI) is used for parallelization and ms2 is therefore easily portable to different computing platforms. Feature tools facilitate the interaction with the code and the interpretation of input and output files. The accuracy and reliability of ms2 has been shown for a large variety of fluids in preceding work. Program summaryProgram title:ms2 Catalogue identifier: AEJF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Special Licence supplied by the authors No. of lines in distributed program, including test data, etc.: 82 794 No. of bytes in distributed program, including test data, etc.: 793 705 Distribution format: tar.gz Programming language: Fortran90 Computer: The simulation tool ms2 is usable on a wide variety of platforms, from single processor machines over PC-clusters and vector computers to vector-parallel architectures. (Tested with Fortran compilers: gfortran, Intel, PathScale, Portland Group and Sun Studio.) Operating system: Unix/Linux, Windows Has the code been vectorized or parallelized?: Yes. Message Passing Interface (MPI) protocol Scalability. Excellent scalability up to 16 processors for molecular dynamics and >512 processors for Monte-Carlo simulations. RAM:ms2 runs on single processors with 512 MB RAM. The memory demand rises with increasing number of processors used per node and increasing number of molecules. Classification: 7.7, 7.9, 12 External routines: Message Passing Interface (MPI) Nature of problem: Calculation of application oriented thermodynamic properties for rigid electro-neutral molecules: vapor-liquid equilibria, thermal and caloric data as well as transport properties of pure fluids and multi-component mixtures. Solution method: Molecular dynamics, Monte-Carlo, various classical ensembles, grand equilibrium method, Green-Kubo formalism. Restrictions: No. The system size is user-defined. Typical problems addressed by ms2 can be solved by simulating systems containing typically 2000 molecules or less. Unusual features: Feature tools are available for creating input files, analyzing simulation results and visualizing molecular trajectories. Additional comments: Sample makefiles for multiple operation platforms are provided. Documentation is provided with the installation package and is available at http://www.ms-2.de. Running time: The running time of ms2 depends on the problem set, the system size and the number of processes used in the simulation. Running four processes on a "Nehalem" processor, simulations calculating VLE data take between two and twelve hours, calculating transport properties between six and 24 hours.
Atomistic simulations of structural and thermodynamic properties of bilayer graphene
NASA Astrophysics Data System (ADS)
Zakharchenko, K. V.; Los, J. H.; Katsnelson, M. I.; Fasolino, A.
2010-06-01
We study the structural and thermodynamic properties of bilayer graphene, a prototype two-layer membrane, by means of Monte Carlo simulations based on the empirical bond order potential LCBOPII (long-range carbon bond order potential II). We present the temperature dependence of lattice parameter, bending rigidity, and high-temperature heat capacity as well as the correlation function of out-of-plane atomic displacements. The thermal-expansion coefficient changes sign from negative to positive above ?400K , which is lower than previously found for single-layer graphene and close to the experimental value of bulk graphite. The bending rigidity is twice larger than for single layer graphene, making the out-of-plane fluctuations smaller. The crossover from correlated to uncorrelated out-of-plane fluctuations of the two carbon planes occurs for wave vectors shorter than ?3nm-1 .
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Technical Reports Server (NTRS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1986-01-01
New improved curve fits for the thermodynamic properties of equilibrium air were developed. The curve fits are for p = p(e,rho), a = a(e,rho), T = T(e,rho), s = s(e,rho), T = T(p,rho), h = h(p,rho), rho = rho(p,s), e = e(p,s) and a = a(p,s). These curve fits can be readily incorporated into new or existing Computational Fluid Dynamics (CFD) codes if real-gas effects are desired. The curve fits were constructed using Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits appearing in NASA CR-2470. These improvements were due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25,000 K and densities from 10 to the minus 7th to 100 amagats (rho/rho sub 0).
The thermodynamic properties of hydrated ?-Al2O3 nanoparticles
NASA Astrophysics Data System (ADS)
Spencer, Elinor C.; Huang, Baiyu; Parker, Stewart F.; Kolesnikov, Alexander I.; Ross, Nancy L.; Woodfield, Brian F.
2013-12-01
In this paper we report a combined calorimetric and inelastic neutron scattering (INS) study of hydrated ?-Al2O3 (?-alumina) nanoparticles. These complementary techniques have enabled a comprehensive evaluation of the thermodynamic properties of this technological and industrially important metal oxide to be achieved. The isobaric heat capacity (Cp) data presented herein provide further critical insights into the much-debated chemical composition of ?-alumina nanoparticles. Furthermore, the isochoric heat capacity (Cv) of the surface water, which is so essential to the stability of all metal-oxides at the nanoscale, has been extracted from the high-resolution INS data and differs significantly from that of ice-Ih due to the dominating influence of strong surface-water interactions. This study also encompassed the analysis of four ?-alumina samples with differing pore diameters [4.5 (1), 13.8 (2), 17.9 (3), and 27.2 nm (4)], and the results obtained allow us to unambiguously conclude that the water content and pore size have no influence on the thermodynamic behaviour of hydrated ?-alumina nanoparticles.
The thermodynamic properties of hydrated ?-Al2O3 nanoparticles.
Spencer, Elinor C; Huang, Baiyu; Parker, Stewart F; Kolesnikov, Alexander I; Ross, Nancy L; Woodfield, Brian F
2013-12-28
In this paper we report a combined calorimetric and inelastic neutron scattering (INS) study of hydrated ?-Al2O3 (?-alumina) nanoparticles. These complementary techniques have enabled a comprehensive evaluation of the thermodynamic properties of this technological and industrially important metal oxide to be achieved. The isobaric heat capacity (C(p)) data presented herein provide further critical insights into the much-debated chemical composition of ?-alumina nanoparticles. Furthermore, the isochoric heat capacity (C(v)) of the surface water, which is so essential to the stability of all metal-oxides at the nanoscale, has been extracted from the high-resolution INS data and differs significantly from that of ice-Ih due to the dominating influence of strong surface-water interactions. This study also encompassed the analysis of four ?-alumina samples with differing pore diameters [4.5 (1), 13.8 (2), 17.9 (3), and 27.2 nm (4)], and the results obtained allow us to unambiguously conclude that the water content and pore size have no influence on the thermodynamic behaviour of hydrated ?-alumina nanoparticles. PMID:24387386
Predicting liquid-phase thermodynamic properties using COSMO-SAC
NASA Astrophysics Data System (ADS)
Burnett, Russell I.
Predicting thermodynamic properties of liquids remains a significant challenge in both academia and industry. This is because molecules in the liquid phase are relatively close together but are not arranged in an ordered structure. The COSMO-SAC model uses quantum and statistical mechanics to predict the thermodynamic properties of liquids. In this thesis, a variety of efforts have been made to improve the accuracy of this model. The most successful of these involves the inclusion of dispersion interactions in mixture calculations, which reduces the average prediction error for activity coefficients by over 30%. It has also been demonstrated that the misfit energy—the traditional interaction energy used in all known COSMO-based models—is limited in its ability to model intermolecular interactions. A variety of attempts to improve the electrostatics of the model have been made, but these have had little effect on the overall accuracy. These include use of an expanded hydrogen bonding description, use of an alternate molecular surface construction method, and incorporation of three-dimensional considerations. These results, coupled with the observed improvement obtained from including dispersion interactions, suggest that the greatest weakness in the model is the handling of electrodynamics (how molecules polarize one another), and that future efforts to improve the model should target this area. In addition, the model has been parameterized for the ADF density functional software package, thus making it available to a wider audience. Results are approximately equivalent to those obtained with DMol3, the only package for which a published parameterization was previously available. Of significance, the ADF implementation allows one of the adjustable model parameters to be eliminated. Also, a correlation was found between experimental liquid volumes and the quantum-based molecular volumes employed in COSMO-SAC. This eliminates the need to provide experimental volumes to the model. Finally, a Windows-based graphical user interface for COSMO-SAC has been developed. This expands the availability of the model to anyone with only a general familiarity with thermodynamics. Without this, use is restricted to those with an in-depth knowledge of quantum mechanics, statistical mechanics and computer programming.
Electronic, mechanical, and thermodynamic properties of americium dioxide
NASA Astrophysics Data System (ADS)
Lu, Yong; Yang, Yu; Zheng, Fawei; Wang, Bao-Tian; Zhang, Ping
2013-10-01
By performing density functional theory (DFT) +U calculations, we systematically study the electronic, mechanical, tensile, and thermodynamic properties of AmO2. It is found that the chemical bonding character in AmO2 is similar to that in PuO2, with smaller charge transfer and stronger covalent interactions between americium and oxygen atoms. The stress-strain relationship of AmO2 is examined along the three low-index directions, showing that the [1 0 0] and [1 1 1] directions are the strongest and weakest tensile directions, respectively, but the theoretical tensile strengths of AmO2 are smaller than those of PuO2. The phonon dispersion curves of AmO2 are calculated and the heat capacities as well as lattice expansion curve are subsequently determined. The lattice thermal conductivity of AmO2 is further evaluated and compared with attainable experiments. Our present work integrally reveals various physical properties of AmO2 and can be referenced for technological applications of AmO2 based materials.
Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals
NASA Technical Reports Server (NTRS)
Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.
1985-01-01
Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated.
T. Urbic
2013-12-16
Thermodynamic properties of the particles interacting through smooth version of Stell-Hemmer interaction were studied using Wertheim's thermodynamic perturbation theory. The temperature dependence of molar volume, heat capacity, isothermal compressibility and thermal expansion coefficient at constant pressure for different number of bonding sites on particle were evaluated. The model showed water-like anomalies for all evaluated quantities, but thermodynamic perturbation theory does not properly predict the dependence of these properties at a fixed number of bonding points.
Thermodynamic properties of a suitable working fluid mixture for absorption heat pumps
NASA Astrophysics Data System (ADS)
Eichholz, H. D.; Schulz, S.
1982-04-01
An absorption heat pump process was considered with reference to thermodynamic properties of methanol lithium bromide as a working fluid. The process was optimized for operating conditions and the binary mixture used. All available thermodynamic data of mixture properties were collected. They were then complemented by vapor-liquid equilibrium measurements and heat of mixing experiments with the result of a theoretical correlation. By a critical selection of properties, the binary mixture CH30H LiBr was qualified as a heat pump working fluid. In addition, thermodynamic properties of methanol are derived by a fundamental equation.
Thermodynamic properties and structural stability of thorium dioxide.
Lu, Y; Yang, Y; Zhang, P
2012-06-01
Using density functional theory (DFT) calculations, we have systematically investigated the thermodynamic properties and structural stabilities of thorium dioxide (ThO(2)). Based on the calculated phonon dispersion curves, we have calculated the thermal expansion coefficient, bulk modulus, and heat capacities at different temperatures for ThO(2) under the quasi-harmonic approximation. All the results are in good agreement with corresponding experiments proving the validity of our methods. Our theoretical studies can aid a clearer understanding of the thermodynamic behaviors of ThO(2) at different temperatures. In addition, we have also studied possible defect formations and diffusion behaviors of helium in ThO(2), to discuss its structural stability. It is found that in intrinsic ThO(2) without any Fermi energy shifts, the interstitial Th(i)(4+) defect rather than oxygen or thorium vacancies, interstitial oxygen, or any kinds of Frenkel pairs, is the most probable to form with an energy release of 1.74 eV. However, after upshifting the Fermi energy, the formation of the other defects also becomes possible. Regarding helium diffusion, we find that only through the thorium vacancy can it occur with the small energy barrier of 0.52 eV. Otherwise, helium atoms can hardly incorporate or diffuse in ThO(2). Our results indicate that upward shifting of the Fermi energy of ThO(2) should be prevented to avoid the formation of thorium vacancies so as to avert helium caused damage. PMID:22555111
Thermodynamic properties of liquid ³3He-?4He mixtures between 0.15 K and 1.8 K
Chaudhry, Gunaranjan
2009-01-01
Thermodynamic property relations for liquid ³3He-?4He mixtures between temperatures of 0.15 K and 1.8 K are determined. The relations are valid over the entire concentration range. Thermodynamic properties are first ...
Thermodynamic and transport properties of air/water mixtures
NASA Technical Reports Server (NTRS)
Fessler, T. E.
1981-01-01
Subroutine WETAIR calculates properties at nearly 1,500 K and 4,500 atmospheres. Necessary inputs are assigned values of combinations of density, pressure, temperature, and entropy. Interpolation of property tables obtains dry air and water (steam) properties, and simple mixing laws calculate properties of air/water mixture. WETAIR is used to test gas turbine engines and components operating in relatively humid air. Program is written in SFTRAN and FORTRAN.
Thermodynamic and electromagnetic properties of the Penson-Kolb model
NASA Astrophysics Data System (ADS)
Czart, W. R.; Robaszkiewicz, S.
2001-09-01
We study thermodynamic and electromagnetic properties of the Penson-Kolb model, i.e., the tight-binding model with the pair-hopping interaction J, and analyze the effects of phase fluctuations on the s-wave superconductivity in this system. The evolution of the critical fields, the coherence length, the Ginzburg ratio, and the London penetration depth ? with particle concentration n and pairing strength is determined at T=0 for d-dimensional hypercubic lattices d=2 (SQ) and d=3 (SC). Within the Kosterlitz-Thouless scenario the critical temperatures Tc are calculated for d=2 SQ lattice and compared with the ones from BCS-HFA Tp. The results show a substantial enhancement of the gap to critical temperature ratio due to the phase fluctuations as well as a separation of the energy scales for the pair formation (~kBTp) and the phase coherence (~kBTc). The Uemura type plots, i.e., the Tc vs ?-2(0) plots, are obtained both as a function of n and as a function of pairing strength. The results are compared with those found earlier for the attractive Hubbard model.
Thermodynamical properties of quantum double-well systems
Hasegawa, Hideo
2012-01-01
We have studied thermodynamical properties of two kinds of quantum double-well systems with a quadratic-quartic potential (model A) and a quadratic potential perturbed by a Gaussian barrier (model B). In numerical calculations of their specific heat and entropy, we have taken into account eigenvalues of $\\epsilon_n$ for $0 \\leq n \\leq N_m$ obtained by diagonalization of the energy matrix as well as their extrapolated ones for $N_m+1 \\leq n specific heat and entropy in both models A and B with symmetric potentials have the Schottky-type anomaly at very low temperatures, which arises from low-lying eigenstates with a small gap due to tunneling through the potential barrier. This anomaly is removed when an asymmetry is introduced into the double-well potential. In the high-temperature limit, the specific heat of model A approaches $C = (3/4) k_B$, while that of model B becomes $C = k_B$ which agrees with that of the harmonic oscillator. Results of the present...
Rhamnolipid surface thermodynamic properties and transport in agricultural soil.
Renfro, Tyler Dillard; Xie, Weijie; Yang, Guang; Chen, Gang
2014-03-01
Rhamnolipid is a biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension. Because of its biodegradability, rhamnolipid applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Subsequently, rhamnolipid applications have more advantages when used to improve irrigation in the agricultural soil, especially under draught conditions. In the presence of rhamnolipid, water surface tension dropped linearly with the increase of rhamnolipid concentration until the rhamnolipid critical micelle concentration (CMC) of 30 mg/L was reached. Below the CMC, rhamnolipid had linear adsorption isotherms on the soil with a partition coefficient of 0.126 L/kg. Rhamnolipid transport breakthrough curves had a broad and diffuse infiltration front, indicating retention of rhamnolipid on the soil increased with time. Rhamnolipid transport was found to be well represented by the advection-dispersion equation based on a local equilibrium assumption. When applied at concentrations above the CMC, the formed rhamnolipid micelles prevented rhamnolipid adsorption (both equilibrium adsorption and kinetic adsorption) in the soil. It was discovered in this research that rhamnolipid surface thermodynamic properties played the key role in controlling rhamnolipid transport. The attractive forces between rhamnolipid molecules contributed to micelle formation and facilitated rhamnolipid transport. PMID:24394947
Molecular Dynamics Simulation of Thermodynamic Properties in Uranium Dioxide
Wang, Xiangyu; Wu, Bin; Gao, Fei; Li, Xin; Sun, Xin; Khaleel, Mohammad A.; Akinlalu, Ademola V.; Liu, L.
2014-03-01
In the present study, we investigated the thermodynamic properties of uranium dioxide (UO2) by molecular dynamics (MD) simulations. As for solid UO2, the lattice parameter, density, and enthalpy obtained by MD simulations were in good agreement with existing experimental data and previous theoretical predictions. The calculated thermal conductivities matched the experiment results at the midtemperature range but were underestimated at very low and very high temperatures. The calculation results of mean square displacement represented the stability of uranium at all temperatures and the high mobility of oxygen toward 3000 K. By fitting the diffusivity constant of oxygen with the Vogel-Fulcher-Tamman law, we noticed a secondary phase transition near 2006.4 K, which can be identified as a ‘‘strong’’ to ‘‘fragile’’ supercooled liquid or glass phase transition in UO2. By fitting the oxygen diffusion constant with the Arrhenius equation, activation energies of 2.0 and 2.7 eV that we obtained were fairly close to the recommended values of 2.3 to 2.6 eV. Xiangyu Wang, Bin Wu, Fei Gao, Xin Li, Xin Sun, Mohammed A. Khaleel, Ademola V. Akinlalu and Li Liu
Hydrogrossular (Katoite): Vibrational, Crystal-Chemical and Thermodynamic Properties
NASA Astrophysics Data System (ADS)
Dachs, E.; Geiger, C. A.
2011-12-01
There is great current interest in understanding interactions between H2O and its components and various Earth materials. Here, questions such as the bulk water content of the mantle, and what phases can incorporate OH- and in what concentrations come immediately to mind. In this regard, the hydrogarnet substitution (i.e., O4H4?SiO4) has received special attention, because it is a verified mechanism for allowing the incorporation of OH- in garnet and possibly in other silicates as well. At relatively low temperatures there is complete solid solution between Ca3Al2Si3O12 and Ca3Al2O12H12. The latter, pure OH-containing end-member is termed katoite/hydrogrossular. Its crystal structure has been investigated by various workers using X-ray and neutron diffraction, including at high pressures. Little is known about its vibrational properties and its thermodynamic behavior is not fully understood. Thus, we studied the low temperature IR spectra and measured the heat capacity of katoite in order to investigate its vibrational, crystal-chemical and thermophysical properties. Katoite was synthesized hydrothermally in Au capsules at 250 °C and 3 kb water pressure. X-ray powder measurements show that about 98-99% katoite was obtained. Powder IR spectra were recorded between 298 K and 10 K. The spectra are considerably different in the high wavenumber region, where O-H stretching modes occur. At room temperature the IR-active O-H band located around 3662 cm-1 is broad and it narrows and shifts to higher wavenumbers and also develops structure below about 80 K. Concomitantly, additional weak intensity O-H bands located around 3600 cm-1 begin to appear and they become sharper and increase in intensity with further decreases in temperature. The spectra indicate that the vibrational behavior of individual OH groups and their collective interactions measurably affect the lattice dynamic (i.e. thermodynamic) behavior. The low temperature heat capacity behavior was investigated with a relaxation calorimeter between 5 and 300 K on a mg-sized sample. The heat capacity data are well behaved at T < 300 K and show a monotonic decrease in magnitude with decreasing temperature. A standard third-law entropy value of S° = 421.7 ± 1.6 J/mol.K was calculated. Using this new calorimetric-based S° value and published standard enthalpy of formation data for katoite, a calorimetric-based Gibbs free energy of formation at 298 K can be obtained as ?G°f = -5021.2 kJ/mol. The Cp data show no evidence for any phase transition as possibly expected by the change in OH-mode behavior with decreasing temperature. It is worth noting that the katoite, in terms of lattice dynamic or thermodynamic behavior, should be thought of having OH groups and not O4H4 clusters or polyhedral units as is often written in the literature. The single crystallographic OH group in katoite shows very weak, if any, hydrogen bonding and the H atoms have large amplitudes of vibration. Very weak H bonding or the lack of it affects the nature of low energy OH-related vibrations and this leads to katoite's large S° value.
THERMODYNAMIC PROPERTIES OF SEA-SALTAEROSOLS A. C. Tridico and I. N. Tang
, (he hygroscopic properties of aerosolparticles generated from filtered sea-water sampleswere studiedBNL- 63377 [Abstract] THERMODYNAMIC PROPERTIES OF SEA-SALTAEROSOLS A. C. Tridico and I. N. Tang,FL Oct. 14-18, 1996 ABSTRACT The thennodynamic properties of mixed salt microdropletsrepresentativeof sea
Thermodynamic properties of UF sub 6 measured with a ballistic piston compressor
NASA Technical Reports Server (NTRS)
Sterritt, D. E.; Lalos, G. T.; Schneider, R. T.
1973-01-01
From experiments performed with a ballistic piston compressor, certain thermodynamic properties of uranium hexafluoride were investigated. Difficulties presented by the nonideal processes encountered in ballistic compressors are discussed and a computer code BCCC (Ballistic Compressor Computer Code) is developed to analyze the experimental data. The BCCC unfolds the thermodynamic properties of uranium hexafluoride from the helium-uranium hexafluoride mixture used as the test gas in the ballistic compressor. The thermodynamic properties deduced include the specific heat at constant volume, the ratio of specific heats for UF6, and the viscous coupling constant of helium-uranium hexafluoride mixtures.
THERMODYNAMIC PROPERTIES OF MC (M = V, Nb, Ta): FIRST-PRINCIPLES CALCULATIONS
NASA Astrophysics Data System (ADS)
Cao, Yong; Zhu, Jingchuan; Liu, Yong; Long, Zhishen
2013-07-01
Through the quasi-harmonic Debye model, the pressure and temperature dependences of linear expansion coefficient, bulk modulus, Debye temperature and heat capacity have been investigated. The calculated thermodynamic properties were compared with experimental data and satisfactory agreement is reached.
Mounet, Nicolas (Nicolas Frank)
2005-01-01
The structural, dynamical, and thermodynamic properties of different carbon allotropes are computed using a combination of ab-initio methods: density-functional theory for total-energy calculations and density-functional ...
THERMODYNAMIC AND TRANSPORT PROPERTIES OF SILICATE MELTS AND MAGMA
Spera, Frank J.
PROPERTIES5 Density and Equation of State6 Enthalpy, Entropy and Heat Capacity7 VI. MAGMA TRANSPORT the temperature of a substance to its internal38 energy. These properties include the enthalpy, entropy and heat diverging plate boundaries. The density, specific heat, viscosity and thermal conductivity of a58 typical
First-principles calculations of the elastic, phonon and thermodynamic properties of Al12Mg17
Chen, Long-Qing
-principles calculations. The obtained structural parameters, phonon dispersion curves and the predicted thermodynamic-principles electron theory; Intermetallic compounds; Elastic behavior; Thermodynamics 1. Introduction As lightweight structural materials with a good combina- tion of castability and mechanical properties, AlMg-based alloys
WETAIR: A computer code for calculating thermodynamic and transport properties of air-water mixtures
NASA Technical Reports Server (NTRS)
Fessler, T. E.
1979-01-01
A computer program subroutine, WETAIR, was developed to calculate the thermodynamic and transport properties of air water mixtures. It determines the thermodynamic state from assigned values of temperature and density, pressure and density, temperature and pressure, pressure and entropy, or pressure and enthalpy. The WETAIR calculates the properties of dry air and water (steam) by interpolating to obtain values from property tables. Then it uses simple mixing laws to calculate the properties of air water mixtures. Properties of mixtures with water contents below 40 percent (by mass) can be calculated at temperatures from 273.2 to 1497 K and pressures to 450 MN/sq m. Dry air properties can be calculated at temperatures as low as 150 K. Water properties can be calculated at temperatures to 1747 K and pressures to 100 MN/sq m. The WETAIR is available in both SFTRAN and FORTRAN.
Thermodynamic and transport property modeling in super critical water
Kutney, Michael C. (Michael Charles)
2005-01-01
Supercritical water oxidation (SCWO) is a thermally-based, remediation and waste-treatment process that relies on unique property changes of water when water is heated and pressurized above its critical point. Above its ...
EquilTheTA: Thermodynamic and transport properties of complex equilibrium plasmas
Colonna, G.; D'Angola, A. [CNR-IMIP Bari, via Amendola 122/D - 70126 Bari (Italy); DIFA, Universita della Basilicata, via dell'Ateneo Lucano, 1085100 Potenza (Italy)
2012-11-27
EquilTheTA (EQUILibrium for plasma THErmodynamics and Transport Applications) is a web-based software which calculates chemical equilibrium product concentrations from any set of reactants and determines thermodynamic and transport properties for the product mixture in wide temperature and pressure ranges. The program calculates chemical equilibrium by using a hierarchical approach, thermodynamic properties and transport coefficients starting from recent and accurate databases of atomic and molecular energy levels and collision integrals. In the calculations, Debye length and cut-off are consistently updated and virial corrections (up to third order) can be considered. Transport coefficients are calculated by using high order approximations of the Chapman-Enskog method.
Williams, Michael Eric
2009-05-15
One of the great keys in the advancement of technology is the development of materials that have the optimal combination of properties for the desired application. For example, without heat resistant ceramics the space shuttle would burn up during..., entropy and specific heat of aluminum. : : : : : : : : : : : : : : 43 8 Volume thermal expansion for tungsten. : : : : : : : : : : : : : : : : : : : 44 9 Thermodynamic property calculations for tungsten. : : : : : : : : : : : : : 44 10 Effect of volume...
Two-Fluid Theory and Thermodynamic Properties of Liquid Mixtures: General Theory
V. Brandani; J. M. Prausnitz
1982-01-01
The two-fluid theory of binary mixtures postulates that the extensive thermodynamic properties of a binary mixture may be expressed by the contributions of two hypothetical fluids that mix ideally. This postulate, coupled with an expression for the partition function of the hypothetical fluid, permits evaluation of the properties of binary liquid mixtures by using only two adjustable binary parameters. Particular
M. B. Kanoun; W. Sekkal; H. Aourag; G. Merad
2000-01-01
In this work, structural, elastic and thermodynamic properties of cubic cadmium telluride (c-CdTe) have been investigated by molecular-dynamics (MD) simulation using the well-tested Tersoff potential under pressure and by varying temperature. Fundamental bulk properties, elastic constants, thermal expansion coefficient, heat capacity and Grüneisen parameter have been studied. The structural properties in the rock-salt structure are also studied and compared with
Thermodynamic properties of boron trioxide in the glass transition region
R. D. Corsaro; J. Jarzynski
1974-01-01
Knowledge of the physical properties of glasses in the transition region is of importance both from a theoreti cal and a practical point of view. These data are of practical importance since the structure of a glass is frozen-in at the transition temperature Tg and the prop erties of a glass at room temperature are to some ex tent determined
Thermodynamic properties of a quasi-harmonic model for ferroelectric transitions.
Mkam Tchouobiap, S E; Mashiyama, H
2011-03-30
Within a framework of a quasi-harmonic model for quantum particles in a local potential of the double Morse type and within the mean-field approximation for interactions between particles, we investigate the thermodynamic properties of ferroelectric materials. A quantum thermodynamic treatment gives analytic expressions for the internal energy, the entropy, the specific heat, and the static susceptibility. The calculated thermodynamic characteristics are studied as a function of temperature and energy barrier, where it is shown that at the proper choice of the theory parameters, particularly the energy barrier, the model system exhibits characteristic features of either second-order tricritical or first-order phase transitions. Our results indicate that the barrier energy seems to be an important criterion for the character of the structural phase transition. The influence of quantum fluctuations manifested on zero-point energy on the phase transition and thermodynamic properties is analyzed and discussed. This leads to several quantum effects, including the existence of a saturation regime at low temperatures, where the order parameter saturates giving thermodynamic saturation of the calculated thermodynamic quantities. It is found that both quantum effects and energy barrier magnitude have an important influence on the thermodynamic properties of the ferroelectric materials and on driving the phase transition at low temperatures. Also, the analytical parameters' effect on the transition temperature is discussed, which seems to give a general insight into the structural phase transition and its nature. PMID:21386368
Thermodynamic properties of supercritical carbon dioxide: Widom and Frenkel lines.
Fomin, Yu D; Ryzhov, V N; Tsiok, E N; Brazhkin, V V
2015-02-01
Supercritical fluids are widely used in a number of important technological applications, yet the theoretical progress in the field has been rather moderate. Fairly recently, a new understanding of the liquidlike and gaslike properties of supercritical fluids has come to the fore, particularly with the advent of the Widom and Frenkel lines that aim to demarcate different physical properties on the phase diagram. Here, we report the results of a computational study of supercritical carbon dioxide, one of the most important fluids in the chemical industry. We study the response functions of CO_{2} in the supercritical state and calculate the locations of their maxima (Widom lines). We also report the preliminary calculations of the Frenkel line, the line of crossover of microscopic dynamics of particles. Our insights are relevant to physical processes in the atmosphere of Venus and its evolution. PMID:25768462
Thermodynamic and Mechanical Properties of Skeletal Muscle Contraction
Yu. I. Prylutskyy; A. M. Shut; M. S. Miroshnychenko; A. D. Suprun
2005-01-01
Thermodynamic parameters such as the change of entropy, internal energy, and enthalpy were calculated as a function of the relative skeletal muscle strain within the framework of a proposed thermodynamic model. A value for the Young’s modulus for the skeletal muscle was also estimated. The obtained theoretical values are in a good agreement with available experimental results for the frog
Thermodynamical Properties of the ICM from Hydrodynamical Simulations
S. Borgani; A. Diaferio; K. Dolag; S. Schindler
2008-01-01
Modern hydrodynamical simulations offer nowadays a powerful means to trace the evolution of the X-ray properties of the intra-cluster\\u000a medium (ICM) during the cosmological history of the hierarchical build up of galaxy clusters. In this paper we review the\\u000a current status of these simulations and how their predictions fare in reproducing the most recent X-ray observations of clusters.\\u000a After briefly
NASA Technical Reports Server (NTRS)
Thompson, Richard A.; Lee, Kam-Pui; Gupta, Roop N.
1990-01-01
The computer codes developed provide data to 30000 K for the thermodynamic and transport properties of individual species and reaction rates for the prominent reactions occurring in an 11-species nonequilibrium air model. These properties and the reaction-rate data are computed through the use of curve-fit relations which are functions of temperature (and number density for the equilibrium constant). The curve fits were made using the most accurate data believed available. A detailed review and discussion of the sources and accuracy of the curve-fitted data used herein are given in NASA RP 1232.
E. S. Denisova
2000-01-01
The theory of the equilibrium properties of stripe domain structure (DS) of nonhomogeneous magnets, induced by a variable\\u000a magnetic field, is developed. It is shown that an induced DS is a thermodynamic system characterized by an effective temperature\\u000a which may be many orders of magnitude higher than the room temperature. For a DS of this kind, the thermodynamic functions\\u000a are
Thermodynamic properties and equations of state for fast reactor safety analysis
K Morita; E. A Fischer; K Thurnay
1998-01-01
In this paper, thermodynamic properties of reactor-core materials are newly evaluated for an analytic equation-of-state (EOS) model with flexible thermodynamic functions. This model has been developed for a multiphase, multicomponent fluid-dynamics code for fast reactor safety analysis. The most up-to-date and reliable sources for uranium dioxide, mixed-oxide fuel, stainless steel, and sodium available at present are first compiled, with particular
NASA Astrophysics Data System (ADS)
Boumali, Abdelmalek
2015-04-01
In this paper, we show, by using the approach of effective mass, that the model of a two-dimensional Dirac oscillator can be used to describe the thermodynamic properties of graphene under a uniform magnetic field. All thermodynamic quantities of graphene, such as the free energy, the mean energy, the entropy and the specific heat, have been found by using an approach based on the zeta function.
Tanasescu, Speranta; Maxim, Florentina; Teodorescu, Florina; Giurgiu, Liviu
2008-02-01
The thermodynamic behavior and spin dynamics of the colossal magnetoresistive (CMR) perovskites of general formula La(1-x)(A)xMn(1-y)(B)yO3 (where A is an alkaline earth, and B = Al, In) have been studied in order to evidence the effect of composition and the influence of nanocrystallinity on the thermodynamic and magnetic characteristics. By using electron paramagnetic resonance (EPR) spectroscopy, the behavior of the exchange coupling integral (J) between Mn spins and the polaron activation energy (Ea) have been investigated. The thermodynamic properties represented by the relative partial molar free energies, enthalpies and entropies of oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressures of oxygen have been obtained by using solid electrolyte electrochemical cells method. The influence of the oxygen stoichiometry change on the thermodynamic properties was examined using the data obtained by a coulometric titration technique coupled with measurements of the electromotive force (EMF). The results were correlated with the average Mn valence values as determined by redox titration. The properties of the rare-earth manganites are strongly affected by the A- and B-site substitution and by the oxygen nonstoichiometry. New features related to the modifications in properties connected with the nanocrystalline state were evidenced. The correlation existing between the magnetic and thermodynamic characteristics were discussed in relation to significant changes in the overall concentration of defects. PMID:18464427
Christian Perruchot; Mohamed M. Chehimi; Marie-Josèphe Vaulay; Karim Benzarti
2006-01-01
The surface thermodynamic properties of three main inorganic compounds formed during hydration of Portland cement: calcium hydroxide (Ca(OH)2), ettringite (3CaO·Al2O3·3CaSO4·32H2O) and calcium-silicate-hydrates (C-S-H), respectively, and one mineral filler: calcium carbonate (CaCO3), have been characterised by inverse gas chromatography at infinite dilution (IGC-ID) at 35 °C. The thermodynamic properties have been investigated using a wide range of non-polar (n-alkane series), Lewis
Electrolytes: transport properties and non-equilibrium thermodynamics
Miller, D.G.
1980-12-01
This paper presents a review on the application of non-equilibrium thermodynamics to transport in electrolyte solutions, and some recent experimental work and results for mutual diffusion in electrolyte solutions.
The Extended Thermodynamic Properties of Taub-NUT/Bolt-AdS spaces
Chong Oh Lee
2014-09-25
We investigate the extended thermodynamic properties of higher-dimensional Taub-NUT/Bolt-AdS spaces where a cosmological constant is treated as a pressure. We find a general form for thermodynamic volumes of Taub-NUT/Bolt-AdS black holes for arbitrary dimensions. Interestingly, it is found that the Taub-NUT-AdS metric has a thermodynamically stable range when the total number of dimensions is a multiple of 4 (4, 8, 12, ...). We also explore their phase structure and find the first order phase transition holds for higher-dimensional cases.
The Extended Thermodynamic Properties of Taub-NUT/Bolt-AdS spaces
Lee, Chong Oh
2014-01-01
We investigate the extended thermodynamic properties of higher-dimensional Taub-NUT/Bolt-AdS spaces where a cosmological constant is treated as a pressure. We find a general form for thermodynamic volumes of Taub-NUT/Bolt-AdS black holes for arbitrary dimensions. Interestingly, it is found that the Taub-NUT-AdS metric has a thermodynamically stable range when the total number of dimensions is a multiple of 4 (4, 8, 12, ...). We also explore their phase structure and find the first order phase transition holds for higher-dimensional cases.
Thermodynamic properties and bulk viscosity near phase transition in the Z(2) and O(4) models
Li Baochun [Department of Physics, Shanxi University, Taiyuan, Shanxi 030006 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Huang Mei [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing 100049 (China)
2009-08-01
We investigate the thermodynamic properties including equation of state, the trace anomaly, the sound velocity, and the specific heat, as well as transport properties like bulk viscosity in the Z(2) and O(4) models in the Hartree approximation of Cornwall-Jackiw-Tomboulis formalism. We study these properties in different cases, e.g. first-order phase transition, second-order phase transition, crossover and the case without phase transition, and discuss the correlation between the bulk viscosity and the thermodynamic properties of the system. We find that the bulk viscosity over entropy density ratio exhibits an upward cusp at the second-order phase transition, and a sharp peak at the first-order phase transition. However, this peak becomes smooth or disappears in the case of crossover. This result supports the idea that the bulk viscosity over entropy density ratio is a better quantity than the shear viscosity over entropy density ratio to locate the critical end point.
An Equation of State for the Thermodynamic Properties of Cyclohexane
NASA Astrophysics Data System (ADS)
Zhou, Yong; Liu, Jun; Penoncello, Steven G.; Lemmon, Eric W.
2014-12-01
An equation of state for cyclohexane has been developed using the Helmholtz energy as the fundamental property with independent variables of density and temperature. Multi-property fitting technology was used to fit the equation of state to data for p?T, heat capacities, sound speeds, virial coefficients, vapor pressures, and saturated densities. The equation of state was developed to conform to the Maxwell criteria for two-phase vapor-liquid equilibrium states, and is valid from the triple-point temperature to 700 K, with pressures up to 250 MPa and densities up to 10.3 mol dm-3. In general, the uncertainties (k = 2, indicating a level of confidence of 95%) in density for the equation of state are 0.1% (liquid and vapor) up to 500 K, and 0.2% above 500 K, with higher uncertainties within the critical region. Between 283 and 473 K with pressures lower than 30 MPa, the uncertainty is as low as 0.03% in density in the liquid phase. The uncertainties in the speed of sound are 0.2% between 283 and 323 K in the liquid, and 1% elsewhere. Other uncertainties are 0.05% in vapor pressure and 2% in heat capacities. The behavior of the equation of state is reasonable within the region of validity and at higher and lower temperatures and pressures. A detailed analysis has been performed in this article.
Pressure-enthalpy driven molecular dynamics for thermodynamic property calculation II: applications
Loukas I. Kioupis; Gaurav Arya; Edward J. Maginn
2002-01-01
The pressure-enthalpy driven molecular dynamics technique, developed in a companion paper [1], is used to compute various thermodynamic properties for the Lennard–Jones (LJ) fluid. These properties include the vapor–liquid coexistence curve, the critical point, the Joule–Thomson coefficient and inversion curve, and a complete vapor-compression refrigeration (VCR) cycle. The technique provides a simple and effective means of utilizing molecular dynamics to
Review and assessment of thermodynamic and transport properties for the CONTAIN Code
Valdez
1988-01-01
A study was carried out to review available data and correlations on the thermodynamic and transport properties of materials applicable to the CONTAIN computer code. CONTAIN is the NRC's best-estimate, mechanistic computer code for modeling containment response to a severe accident. Where appropriate, recommendations have been made for suitable approximations for material properties of interests. Based on a modified Benedict-Webb-Rubin
Precise thermodynamic properties for natural waters covering only the limnological range
Chen, C.T.A.; Millero, F.J.
1986-05-01
Dissolved salts affect the thermodynamic properties of lake waters. Equations are given to calculate the following properties over the range of 0-0.6 salinity, 0/sup 0/-30/sup 0/C, and 0-180 bars: density, thermal expansibility, temperature of maximum density, maximum density and minimum specific volume, isothermal compressibility, specific heat at constant pressure, specific heat at constant volume, sound speed, adiabatic compressibility, freezing point, adiabatic temperature gradient, and static stability.
Precise thermodynamic properties for natural waters covering only the limnological range
CHEN-TUNG A. CHEN; FRANK J. MILLERO
1986-01-01
Dissolved salts affect the thermodynamic properties of lake waters. Equations are given to calculate the following properties over the range of 0-0.6 salinity, 0Â°â»Â³Â°sup 0\\/C, and 0-180 bars: density, thermal expansibility, temperature of maximum density, maximum density and minimum specific volume, isothermal compressibility, specific heat at constant pressure, specific heat at constant volume, sound speed, adiabatic compressibility, freezing point, adiabatic
Thermodynamic property modeling for 2,3,3,3-tetrafluoropropene (HFO1234yf)
Ryo Akasaka; Katsuyuki Tanaka; Yukihiro Higashi
2010-01-01
This paper presents a timely and reliable equation of state for 2,3,3,3-tetrafluoropropene (HFO-1234yf) whose thermodynamic property information is strongly desired. The Patel–Teja (PT) equation of state and the extended corresponding state (ECS) model have been individually applied to property modeling for this new refrigerant. Comparisons of predicted values with the equation\\/model were made with the most recent experimental data. Both
Quantum and thermodynamic properties of spontaneous and low-energy induced fission of nuclei
S. G. Kadmensky
2005-01-01
It is shown that A. Bohr’s concept of transition fission states can be matched with the properties of Coriolis interaction\\u000a if an axisymmetric fissile nucleus near the scission point remains cold despite a nonadiabatic character of nuclear collective\\u000a deformation motion. The quantum and thermodynamic properties of various stages of binary and ternary fission after the descent\\u000a of a fissile nucleus
Duan, Yuhua
2012-11-02
Since current technologies for capturing CO{sub 2} to fight global climate change are still too energy intensive, there is a critical need for development of new materials that can capture CO{sub 2} reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO{sub 2} capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO{sub 2} sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO{sub 2} adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO{sub 2} capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. Only those selected CO{sub 2} sorbent candidates were further considered for experimental validations. The ab initio thermodynamic technique has the advantage of identifying thermodynamic properties of CO{sub 2} capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. Such methodology not only can be used to search for good candidates from existing database of solid materials, but also can provide some guidelines for synthesis new materials. In this presentation, we first introduce our screening methodology and the results on a testing set of solids with known thermodynamic properties to validate our methodology. Then, by applying our computational method to several different kinds of solid systems, we demonstrate that our methodology can predict the useful information to help developing CO{sub 2} capture Technologies.
From transport to disorder: Thermodynamic properties of finite dust clouds
NASA Astrophysics Data System (ADS)
Schella, André; Mulsow, Matthias; Melzer, André; Schablinski, Jan; Block, Dietmar
2013-06-01
The quantities entropy and diffusion are measured for two- and three-dimensional (3D) dust clusters in the fluid state. Entropy and diffusion are predicted to be closely linked via unstable modes. The method of instantaneous normal modes is applied for various laser-heated clusters to determine these unstable modes and the corresponding diffusive properties. The configurational entropy is measured for 2D and 3D clusters from structural rearrangements. The entropy shows a threshold behavior at a critical temperature for the 2D clusters, allowing us to estimate a configurational melting temperature. Further, the entropic disorder increases for larger clusters. Finally, the predicted relation between entropy and unstable modes has been confirmed from our experiments for 2D systems, whereas 3D systems do not show such a clear correlation.
Pressure–enthalpy driven molecular dynamics for thermodynamic property calculation
Loukas I Kioupis; Edward J Maginn
2002-01-01
An algorithm is presented which enables the direct simulation of isenthalpic pressure changes and isobaric enthalpy changes using molecular dynamics (MD). The pressure and enthalpy can be controlled using either a constraint or extended system formalism. By controlling the rate with which new state points are approached, reversible or irreversible thermodynamic cycles can be simulated directly. The method can be
SIGNIGICANT STRUCTURES IN LIQUIDS. V. THERMODYNAMIC AND TRANSPORT PROPERTIES OF MOLTEN METALS
C. M. Carlson; H. Eyring; T. Ree
1960-01-01
ABS>Thermodynamic properties calculated for molten metals by the method ; of significant structures of Eyring, Ree, and Hirai are presented. The ; application is discussed of the method of significant structures in predicting ; the viscosities and self-diffusion coefficients of moiten metals at various ; temperatures and pressures. Data are tabulated on sodium, mercury, copper, and ; lead. (C.H.);
Analysis of thermodynamic properties of molybdenum and tungsten at high temperatures
Armando Fernández Guillermet; Göran Grimvall
1991-01-01
Using recent and accurate experimental information on various thermodynamic quantities up to the melting temperature Tf of molybdenum and tungsten, we make a detailed study of some of their high-temperature properties. In particular, we consider the entropy, reduced to a fixed crystal volume, and interpret the result in terms of an electronic part and a temperature-dependent entropy Debye temperature. The
Thermodynamic properties of ni nitrides and phase stability in the NiN system
A. Fernández Guillermet; K. Frisk
1991-01-01
The thermodynamics of the Ni-N system is poorly known from experiments, and there is a need of information on the stability of the various nitride phases and the Ni-N phase diagram. This kind of information has been obtained by us, by combining the few measurements available with predictions, based on recently reported regularities in bonding properties and vibrational entropy of
W. V. Steele; R. D. Chirico; S. E. Knipmeyer; A. Nguyen
1990-01-01
Catalytic hydrodenitrogenation (HDN) is a key step in upgrading processes for conversion of heavy petroleum, shale oil, tar sands, and the products of the liquefaction of coal to economically viable products. This research program provides accurate experimental thermochemical and thermophysical properties for key organic nitrogen-containing compounds present in the range of alternative feedstocks, and applies the experimental information to thermodynamic
Mark David Asta
1993-01-01
In this dissertation it is shown how quantum and statistical mechanical computational techniques can be combined in order to make possible the calculation of thermodynamic properties for solid-state binary substitutional alloy phases from first principles, i.e., from a knowledge of only basic crystallographic information and the atomic numbers of the alloy constituents. The framework which is discussed here for performing
John Brodholt; Bernard Wood
1993-01-01
Molecular dynamics simulations of water properties over a wide pressure temperature range were performed using a realistic intermolecular potential (TIP4P) and a wide range of densities. An equation of state developed for water at pressures from 10 to 300 kbar is presented together with structural and other thermodynamic results. Comparisons of the PVT predictions of TIP4P to the experimental data
Chickos, James S.
Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures The vaporization enthalpies and vapor pressures of the liqiud phase from T ) 298.15 K to T ) 500 K of a series. The vaporization enthalpies at T ) 298.15 K measured in kilojoules per mole include: tri-n-butylamine (62.7 ( 1
Chickos, James S.
Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures and Biochemistry, University of MissourisSt. Louis, St. Louis, Missouri 63121 The vaporization enthalpies and liquid vapor pressures from T ) 298.15 K to T ) 510 K of a series of polyaromatic hydrocarbons have been
JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of State
NSDL National Science Digital Library
Cubic equations of state are widely used by chemists and chemical engineers to predict the thermodynamic properties of both pure substances and mixtures. In particular, these equations enable predictions concerning the temperature and pressure at which vapor liquid equilibrium occurs. These two educational JavaScript programs perform calculations using cubic equations of state and, equally importantly, explain how the calculations are performed.
Thermodynamic properties of an evaporation process in self-gravitating N -body systems.
Komatsu, Nobuyoshi; Kiwata, Takahiro; Kimura, Shigeo
2010-08-01
By means of N -body simulations, we consider self-gravitating open systems enclosed in a spherical container with semipermeable reflecting walls, in order to investigate the thermodynamics of the evaporation process in self-gravitating N -body systems (such as the escape of stars from globular clusters). To simulate the evaporation process, when the energy of a particle exceeds a certain threshold value, the particle passes through the semipermeable reflecting wall freely. We show that the thermodynamic properties of the evaporation process, such as the dependence of the temperature on energy, agree well with those of stellar polytropes, if the system is in an approximate virial equilibrium state. However, in a lower-energy region or for a rapid evaporation process, the thermodynamic properties deviate from those for the stellar polytrope. Nevertheless, we found that a negative specific heat occurs even in the lower-energy region or for a rapid evaporation process. PMID:20866786
Thermodynamic critical and geometrical properties of charged BTZ black hole
Wei Yihuan [Department of Physics, Bohai University, Jinzhou 121000, Liaoning (China)
2009-07-15
The heat capacities and the electric capacitances of charged Banados-Teitelboim-Zanelli (BTZ) black hole are first calculated. By using the equilibrium fluctuation theory of thermodynamics the second-order moments in three different ensembles are obtained, and it is found that in the microcanonical ensemble the extremal charged BTZ black hole is a critical point of the second-order phase transition. The critical exponents associated with some response coefficients satisfy the scaling law of the first kind and the effective spatial dimension is determined to be one from the scaling law of the second kind. The Ricci curvature scalar associated with the Ruppeiner thermodynamic metric is calculated, which suggests also that the effective spatial dimension of the charged BTZ black hole is one.
Thermodynamic properties of nuclear matter with three-body forces
Soma, V. [Institute of Nuclear Physics PAN, PL-31-342 Krakow (Poland); Bozek, P. [Institute of Physics, Rzeszow University, PL-35-959 Rzeszow (Poland); Institute of Nuclear Physics PAN, PL-31-342 Krakow (Poland)
2009-08-15
We calculate thermodynamic quantities in symmetric nuclear matter within the self-consistent Green's functions method including three-body forces. The thermodynamic potential is computed directly from a diagrammatic expansion, implemented with the CD-Bonn and Nijmegen nucleon-nucleon potentials and the Urbana three-body forces. We present results for entropy and pressure up to temperatures of 20 MeV and densities of 0.32 fm{sup -3}. While the pressure is sensitive to the inclusion of three-body forces, the entropy is not. The unstable spinodal region is identified and the critical temperature associated to the liquid-gas phase transition is determined. When three-body forces are added we find a strong reduction of the critical temperature, obtaining T{sub c}{approx_equal}12 MeV.
Transport properties of high temperature air in local thermodynamic equilibrium
M. Capitelli; G. Colonna; C. Gorse
2000-01-01
: In the paper new calculated transport coefficients of air in the temperature range 50-100 000 K are presented. The results\\u000a have been obtained by means of the perturbative Chapman-Enskog method, assuming that the plasma is in local thermodynamic\\u000a equilibrium (LTE). The calculations include viscosity, thermal conductivity, electric conductivity and multicomponent diffusion\\u000a coefficients. For the calculation, a recent compilation of
Thermodynamic properties of uranium in Ga-In based alloys
NASA Astrophysics Data System (ADS)
Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Melchakov, S. Yu; Shchetinskiy, A. V.; Osipenko, A. G.; Kormilitsyn, M. V.
2013-07-01
Activity of uranium was determined in gallium, indium and gallium-indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U-Ga-In alloys, uranium forms the intermetallic compound UGa3. Activity coefficients and solubility of uranium in Ga-In eutectic were also determined in the same temperature range. Partial thermodynamic functions of ?-U in saturated alloys with gallium, indium and Ga-In eutectic were calculated.
Thermodynamic and mechanical properties of TiC from ab initio calculation
Dang, D. Y.; Fan, J. L.; Gong, H. R., E-mail: gonghr@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)
2014-07-21
The temperature-dependent thermodynamic and mechanical properties of TiC are systematically investigated by means of a combination of density-functional theory, quasi-harmonic approximation, and thermal electronic excitation. It is found that the quasi-harmonic Debye model should be pertinent to reflect thermodynamic properties of TiC, and the elastic properties of TiC decease almost linearly with the increase of temperature. Calculations also reveal that TiC possesses a pronounced directional pseudogap across the Fermi level, mainly due to the strong hybridization of Ti 3d and C 2p states. Moreover, the strong covalent bonding of TiC would be enhanced (reduced) with the decrease (increase) of temperature, while the change of volume (temperature) should have negligible effect on density of states at the Fermi level. The calculated results agree well with experimental observations in the literature.
Thermodynamic properties of Cu-Zr melts: The role of chemical interaction
NASA Astrophysics Data System (ADS)
Kulikova, T. V.; Majorova, A. V.; Shunyaev, K. Yu.; Ryltsev, R. E.
2015-06-01
General statistical model is applied to analyze the role of chemical interaction in associated systems. We show that, at certain conditions, chemical interaction between associates may be not essential above a distectic point and so the model of ideal associated solutions is a good approximation for describing high temperature properties of associated system with chemical interaction. Within the frames of such conception, we calculate thermodynamic properties of Cu-Zr system in liquid state. The enthalpies of formation of Cu-Zr intermetallic compounds were redefined by using matching procedure taking into account the additive manifestation of chemical interaction. We conclude that simple model which is free of adjusting parameters allows us to calculate thermodynamic properties of Cu-Zr melts with quite good accuracy.
Probing the Thermodynamic Properties of Mantle Rocks in Solid and Liquid States
NASA Astrophysics Data System (ADS)
Wolf, Aaron S.
Our understanding of the structure and evolution of the deep Earth is strongly linked to knowledge of the thermodynamic properties of rocky materials at extreme temperatures and pressures. In this thesis, I present work that helps constrain the equation of state properties of iron-bearing Mg-silicate perovskite as well as oxide-silicate melts. I use a mixture of experimental, statistical, and theoretical techniques to obtain knowledge about these phases. These include laser-heated diamond anvil cell experiments, Bayesian statistical analysis of powder diffraction data, and the development of a new simplified model for understanding oxide and silicate melts at mantle conditions. By shedding light on the thermodynamic properties of such ubiquitous Earth-forming materials, I hope to aid our community's progress toward understanding the large-scale processes operating in the Earth's mantle, both in the modern day and early in Earth's history.
Coherent states for Landau levels: algebraic and thermodynamical properties
Isiaka Aremua; Mahouton Norbert Hounkonnou; Ezinvi Baloïtcha
2013-06-07
This work addresses a study of coherent states for a physical system governed by a Hamiltonian operator describing the motion, in two dimensional space, of spinless electrons subjected to a perpendicular magnetic field ${\\bf B}$ coupled with a harmonic potential $\\frac{1}{2}M\\omega^{2}_{0}r^{2}$. The underlying $su(1, 1)$ Lie algebra and Barut-Girardello coherent states are constructed and discussed. Further, the Berezin - Klauder - Toeplitz quantization, also known as coherent state (or anti-Wick) quantization, is also performed.The thermodynamics of such a quantum electron gas system is elaborated and analyzed.
Urrutia, Ignacio
2015-06-28
Recently, new insights into the relation between the geometry of the vessel that confines a fluid and its thermodynamic properties were traced through the study of cluster integrals for inhomogeneous fluids. In this work, I analyze the thermodynamic properties of fluids confined in wedges or by edges, emphasizing on the question of the region to which these properties refer. In this context, the relations between the line-thermodynamic properties referred to different regions are derived as analytic functions of the dihedral angle ?, for 0 < ? < 2?, which enables a unified approach to both edges and wedges. As a simple application of these results, I analyze the properties of the confined gas in the low-density regime. Finally, using recent analytic results for the second cluster integral of the confined hard sphere fluid, the low density behavior of the line thermodynamic properties is analytically studied up to order two in the density for 0 < ? < 2? and by adopting different reference regions. PMID:26133452
Bnuce S. HeurNcwAy; RrcHRno A. Roerr
The heat capacities of phillipsite and clinoptilolite have been measured between l5 and 305 K. Smoothed values of the thermodynamic properties, heat capacity, entropy, enthalpy function and Gibbs energy function have been calculated from the measured heat capacities for the phillipsite composition (Na1 ssKsro)Alr$Sio.rzOr6'6H2O and for the clinoptilolite composition (NaosoKoe6Cal 56Mg1 zr)(Alo.zFeo.:)Si?eo?2 . 22H2O. At 298.15 K,Slsn - Sfi is
H.-L Zhang; H Sato; K Watanabe
1997-01-01
Thermodynamic properties of the R-32\\/125 binary system are modeled by a new cubic equation of state which was developed and applied to the pure R-32 and R-125 in a previous paper by the present authors. The essential thermodynamic properties such as PVTx properties, vapor-liquid equilibrium, enthalpy, entropy, isobaric specific heat, and speed of sound are well represented by the new
Thermodynamic properties of some metal oxide-zirconia systems
NASA Technical Reports Server (NTRS)
Jacobson, Nathan S.
1989-01-01
Metal oxide-zirconia systems are a potential class of materials for use as structural materials at temperatures above 1900 K. These materials must have no destructive phase changes and low vapor pressures. Both alkaline earth oxide (MgO, CaO, SrO, and BaO)-zirconia and some rare earth oxide (Y2O3, Sc2O3, La2O3, CeO2, Sm2O3, Gd2O3, Yb2O3, Dy2O3, Ho2O3, and Er2O3)-zirconia system are examined. For each system, the phase diagram is discussed and the vapor pressure for each vapor species is calculated via a free energy minimization procedure. The available thermodynamic literature on each system is also surveyed. Some of the systems look promising for high temperature structural materials.
Thermodynamic properties of QCD in external magnetic fields
G. S. Bali; F. Bruckmann; M. Constantinou; M. Costa; G. Endrodi; Z. Fodor; S. D. Katz; S. Krieg; H. Panagopoulos; A. Schafer; K. K. Szabo
2013-01-24
We consider the effect of strong external electromagnetic fields on thermodynamic observables in QCD, through lattice simulations with 1+1+1 flavors of staggered quarks at physical quark masses. Continuum extrapolated results are presented for the light quark condensates and for their tensor polarizations, as functions of the temperature and the magnetic field. We find the light condensates to undergo inverse magnetic catalysis in the transition region, in a manner that the transition temperature decreases with growing magnetic field. We also compare the results to other approaches and lattice simulations. Furthermore, we relate the tensor polarization to the spin part of the magnetic susceptibility of the QCD vacuum, and show that this contribution is diamagnetic.
Thermodynamic properties of mesoscale convective systems observed during BAMEX
Correia, James; Arritt, R.
2008-11-01
Dropsonde observations from the Bow-echo and Mesoscale convective vortex EXperiment (BAMEX) are used to document the spatio-temporal variability of temperature, moisture and wind within mesoscale convective systems (MCSs). Onion type sounding structures are found throughout the stratiform region of MCSs but the temperature and moisture variability is large. Composite soundings were constructed and statistics of thermodynamic variability were generated within each sub-region of the MCS. The calculated air vertical velocity helped identify subsaturated downdrafts. We found that lapse rates within the cold pool varied markedly throughout the MCS. Layered wet bulb potential temperature profiles seem to indicate that air within the lowest several km comes from a variety of source regions. We also found that lapse rate transitions across the 0 C level were more common than isothermal, melting layers. We discuss the implications these findings have and how they can be used to validate future high resolution numerical simulations of MCSs.
A calorimetric study of the thermodynamic properties of potassium molybdate
NASA Astrophysics Data System (ADS)
Gavrichev, K. S.; Ryumin, M. A.; Tyurin, A. V.; Gurevich, V. M.; Komissarova, L. N.; Khoroshilov, A. V.; Sharpataya, G. A.
2009-03-01
The low-temperature heat capacity of K2MoO4 was measured by adiabatic calorimetry. The smoothed heat capacity values, entropies, reduced Gibbs energies, and enthalpies were calculated over the temperature range 0-330 K. The standard thermodynamic functions determined at 298.15 K were C {/p °} (298.15 K) = 143.1 ± 0.2 J/(mol K), S°(298.15 K) = 199.3 ± 0.4 J/(mol K), H°(298.15 K)- H°(0) = 28.41 ± 0.03 kJ/mol, and ?°(298.15 K) = 104.0 ± 0.4 J/(mol K). The thermal behavior of potassium molybdate at elevated temperatures was studied by differential scanning calorimetry. The parameters of polymorphic transitions and fusion of potassium molybdate were determined.
NASA Technical Reports Server (NTRS)
Mccarty, R. D.
1980-01-01
The thermodynamic and transport properties of selected cryogens had programmed into a series of computer routines. Input variables are any two of P, rho or T in the single phase regions and either P or T for the saturated liquid or vapor state. The output is pressure, density, temperature, entropy, enthalpy for all of the fluids and in most cases specific heat capacity and speed of sound. Viscosity and thermal conductivity are also given for most of the fluids. The programs are designed for access by remote terminal; however, they have been written in a modular form to allow the user to select either specific fluids or specific properties for particular needs. The program includes properties for hydrogen, helium, neon, nitrogen, oxygen, argon, and methane. The programs include properties for gaseous and liquid states usually from the triple point to some upper limit of pressure and temperature which varies from fluid to fluid.
Ignacio Urrutia
2015-05-08
Recently, new insights in the relation between the geometry of the vessel that confines a fluid and its thermodynamic properties were traced through the study of cluster integrals for inhomogeneous fluids. In this work I analyze the thermodynamic properties of fluids confined in wedges or by edges, emphasizing on the question of the region to which these properties refer. In this context, the relations between the line-thermodynamic properties referred to different regions are derived as analytic functions of the dihedral angle $\\alpha$ , for $0fluid, the low density behavior of the line thermodynamic properties is analytically studied up to order two in the density for $0<\\alpha<2\\pi$ and by adopting different reference regions.
Perruchot, Christian [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Chehimi, Mohamed M. [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Vaulay, Marie-Josephe [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Benzarti, Karim [Laboratoire Central des Ponts et Chaussees (LCPC), 58 Boulevard Lefevre, 75732 Paris Cedex 15 (France)]. E-mail: benzarti@lcpc.fr
2006-02-15
The surface thermodynamic properties of three main inorganic compounds formed during hydration of Portland cement: calcium hydroxide (Ca(OH){sub 2}), ettringite (3CaO.Al{sub 2}O{sub 3}.3CaSO{sub 4}.32H{sub 2}O) and calcium-silicate-hydrates (C-S-H), respectively, and one mineral filler: calcium carbonate (CaCO{sub 3}), have been characterised by inverse gas chromatography at infinite dilution (IGC-ID) at 35 deg. C. The thermodynamic properties have been investigated using a wide range of non-polar (n-alkane series), Lewis acidic (CH{sub 2}Cl{sub 2} and CHCl{sub 3}), Lewis basic (diethyl ether) and aromatic (benzene) and n-alkene series molecular probes, respectively. The tested samples are fairly high surface energy materials as judged by the high dispersive contribution to the total surface energy (the dispersive components {gamma} {sub s} {sup d} range from 45.6 up to 236.2 mJ m{sup -2} at 35 deg. C) and exhibit amphoteric properties, with a predominant acidic character. In the case of hydrated components (i.e. ettringite and C-S-H), the surface thermodynamic properties have been determined at various temperatures (from 35 up to 120 deg. C) in order to examine the influence of the water content. The changes of both dispersive and specific components clearly demonstrate that the material surface properties are activated with temperature. The changes in the acid-base properties are correlated with the extent of the overall water loss induced by the thermal treatment as demonstrated by thermogravimetric analysis (TGA). The elemental surface composition of these compounds has been determined by X-ray photoelectron spectroscopy (XPS)
Terwilliger, C.D.; Chiang, Y.M. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Eastman, J.A.; Liao, Y. (Argonne National Lab., IL (USA))
1991-06-01
This work explores the use of high temperature differential scanning calorimetry as a novel way in which to measure thermodynamic and kinetic properties of grain boundaries in ceramics. A calorimetric study of grain growth has become practical only recently, with the development of processing methods for nanocrystalline materials (10--50 nm grain size) that have enough grain boundary area and thus grain boundary excess properties to be detected by commercial calorimeters. Here we report results from experiments on nanocrystalline silicon and titanium dioxide. 14 refs., 6 figs.
NASA Astrophysics Data System (ADS)
Han, J. J.; Wang, C. P.; Liu, X. J.; Wang, Y.; Liu, Zi-Kui
2012-12-01
We report the results of our first-principles calculations of structural stability, mechanical, magnetic, and thermodynamic properties for ?-M23C6 (M = Fe, Cr) compounds with each of the four metal Wyckoff sites being occupied in turn by Fe. The thermodynamic properties and the temperature dependence of the mechanical behavior of ?-M23C6 compounds are investigated based on the quasi-harmonic Debye model. The results show that the thermodynamic properties of ?-M23C6 (M = Fe, Cr) compounds are more dependent on the position of Fe atoms than the amount of Fe.
Numerical prediction of the thermodynamic properties of ternary Al-Ni-Hf alloys
Romanowska, Jolanta; Kotowski, S?awomir; Zagula-Yavorska, Maryana [Rzeszów University of Technology (Poland)
2014-10-06
Thermodynamic properties of ternary Al-Hf-Ni system, such as {sup ex}G, ?{sub Al}, ?{sub Ni} and ?{sub Zr} at 1373K were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting {sup ex}G values was regarded as the calculation of excess Gibbs energy values inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of {sup ex}G on all legs of the triangle are known. {sup ex}G and L{sub ijk} ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism are calculated numerically using Wolfram Mathematica 9 software.
Ignacio Urrutia; Gabriela Castelletti
2014-09-29
This paper presents a modified grand canonical ensemble which provides a new simple and efficient scheme to study few-body fluid-like inhomogeneous systems under confinement. The new formalism is implemented to investigate the exact thermodynamic properties of a hard sphere (HS) fluid-like system with up to three particles confined in a spherical cavity. In addition, the partition function of this system was used to analyze the surface thermodynamic properties of the many-HS system and to derive the exact curvature dependence of both the surface tension and adsorption in powers of the density. The expressions for the surface tension and the adsorption were also obtained for the many- HS system outside of a fixed hard spherical object. We used these results to derive the dependence of the fluid-substrate Tolman length up to first order in density.
Structural, vibrational and thermodynamic properties of Mg2 FeH6 complex hydride
NASA Astrophysics Data System (ADS)
Zhou, H. L.; Yu, Y.; Zhang, H. F.; Gao, T.
2011-02-01
Mg2FeH6, which has one of the highest hydrogen storage capacities among Mg based 3d-transitional metal hydrides, is considered as an attractive material for hydrogen storage. Within density-functional perturbation theory (DFPT), we have investigated the structural, vibrational and thermodynamic properties of Mg2FeH6. The band structure calculation shows that this compound is a semiconductor with a direct X-X energy gap of 1.96 eV. The calculated phonon frequencies for the Raman-active and the infrared-active modes are assigned. The phonon dispersion curves together with the corresponding phonon density of states and longitudinal-transverse optical (LO-TO) splitting are also calculated. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as free energy, internal energy, entropy and heat capacity within the quasi-harmonic approximation based on the calculated phonon density of states.
Phase transition and thermodynamic properties of beryllium telluride under high pressure
NASA Astrophysics Data System (ADS)
Guo, Zhi-Cheng; Luo, Fen; Zhang, Xiu-Lu; Liu, Cheng-An; Cai, Ling-Cang
2015-04-01
A theoretical investigation on structural, dynamical, phase diagram and thermodynamic properties of beryllium telluride (BeTe) under high pressure and temperature is presented in the framework of density functional theory. The calculated structural parameters of BeTe in both zinc blende (ZB) and nickel arsenide (NiAs) structures are in reasonable agreement with available experimental data and previous theoretical work. The phonon dispersion relations, dielectric tensor and Born effective charge are investigated within the density functional perturbation theory (DFPT). The investigation of the phase diagram indicated that the NiAs structure BeTe becomes stable at high pressure and temperature. Based on the quasiharmonic Debye model, the pressure and temperature dependences of bulk modulus, Grüneisen parameter, Debye temperature, specific heat and thermal expansion coefficient are all successfully obtained. We hope that the theoretical results reported here can give more insight into the structural and thermodynamic properties of other semiconductors at high temperature and pressure.
Thermodynamic properties of liquid Au–Cu–Sn alloys determined from electromotive force measurements
Guo, Zhongnan; Hindler, Michael; Yuan, Wenxia; Mikula, Adolf
2011-01-01
The thermodynamic properties of the ternary Au–Cu–Sn system were determined with the electromotive force (EMF) method using a liquid electrolyte. Three different cross-sections with constant Au:Cu ratios of 3:1, 1:1, and 1:3 were applied to measure the thermodynamic properties of the ternary system in the temperature range between the liquidus temperature of the alloys and 1023 K. The partial free energies of Sn in liquid Au–Cu–Sn alloys were obtained from EMF data. The integral Gibbs free energy and the integral enthalpy at 900 K were calculated by Gibbs–Duhem integration. The ternary interaction parameters were evaluated using the Redlich–Kister–Muggianu polynomial. PMID:22039311
Thermodynamic and thermophysical properties of organic working fluids for Rankine-cycle engines
O. Badr; P. W. OCallaghan; S. D. Probert
1985-01-01
Refrigerants, especially the halocarbon compounds R-11, R-113 and R-114, are the most suitable organic working fluids for the majority of operational Rankine-cycle engines utilising low grade heat sources. Thus, the quick and accurate evaluation of the thermodynamic and thermo-physical properties of these refrigerants is desirable for the analytical prediction of the performances of individual components of such a Rankine-cycle engine,
Property evaluation in The Expert System for Thermodynamics (“TEST”) web application
Christopher Paolini
2009-01-01
Ever since its release, TEST has found use as thermodynamic courseware in many universities around the world. TEST offers web-based analysis tools–java applets called daemons–for property evaluation of working substances, energy, entropy, and exergy analysis of generic open and closed systems, IC engines, gas and vapor power cycles, refrigeration, HVAC, combustion, chemical equilibrium, and gas dynamics. Other modules of TEST
A correlation for thermodynamic properties of heavy fossil-fuel fractions
Barry J. Schwarz; John M. Prausnitz
1988-01-01
A correlation is developed for calculation of thermodynamic properties of heavy fossil fuels, based on a recent version of the perturbed-hard-chain equation of state. Since the correlation does not require experimental vapor pressures or densities as input data, it is useful for heavy fossil fuels where vapor pressures and densities are difficult or impossible to measure. For fossil-fuel fractions, equation-of-state
Gleb Pokrovski; Robert Gout; Jacques Schott; Alexandre Zotov; Jean-Claude Harrichoury
1996-01-01
The stoichiometry and thermodynamic properties of As (III) hydroxide complexes were determined from both solubility and Raman spectroscopic measurements. Arsenolite, claudetite, and orpiment solubilities were measured at temperatures to 250 and 300 °C, respectively, in acid solutions (pH < 6) at the saturated vapor pressure of the system. Raman spectroscopic measurements were performed on As2O3-H2O solutions (0.02 ? As ?
The thermodynamic properties of dilute solutions of oxygen in the liquid Fe-Ni-Co alloys
Edwin S. Tankins
1970-01-01
Thermodynamic properties of dilute solutions of oxygen in the system Fe-Ni-Co have been studied by means of the hydrogen-water vapor equilibrium. Evidence is presented which shows Henry's Law is obeyed by oxygen within experimental error over a substantial composition range. The standard Gibbs energy of solution of oxygen surface is presented for the entire system at 1550°C. Equations are presented
The thermodynamic properties of dilute solutions of oxygen in the liquid Fe-Ni-Co alloys
Edwin S. Tankins
1970-01-01
Thermodynamic properties of dilute solutions of oxygen in the system Fe-Ni-Co have been studied by means of the hydrogen-water\\u000a vapor equilibrium. Evidence is presented which shows Henry’s Law is obeyed by oxygen within experimental error over a substantial\\u000a composition range. The standard Gibbs energy of solution of oxygen surface is presented for the entire system at 1550C. Equations\\u000a are presented
Ionic melts with waterlike anomalies: Thermodynamic properties of liquid BeF2
Manish Agarwal; Ruchi Sharma; Charusita Chakravarty
2007-01-01
Thermodynamic properties of liquid beryllium difluoride (BeF2) are studied using canonical ensemble molecular dynamics simulations of the transferable rigid ion model potential. The negative slope of the locus of points of maximum density in the temperature-pressure plane is mapped out. The excess entropy, computed within the pair correlation approximation, is found to show an anomalous increase with isothermal compression at
Correlations between the thermodynamic properties of II–VI and III–VI phases
V. P. Vasil’ev
2007-01-01
Simple correlation models are considered that can be used to predict unknown and refine questionable thermodynamic properties\\u000a of II–VI and III–VI semiconductors. An empirical rule is proposed: for a particular combination of Periodic Groups, the enthalpy\\u000a and Gibbs energy of formation of isostructural A\\u000a n\\u000a B\\u000a m\\u000a compounds are linear functions of the melting point.
Thermodynamic properties for rare earths and americium in pyropartitioning process solvents
S. P. Fusselman; J. J. Roy; D. L. Grimmett
1999-01-01
The design of a molten metal-molten salt based chemical and electrochemical process for separation of actinides from plutonium-uranium extraction waste requires a consistent set of thermodynamic properties for the actinides and rare earths present in nuclear waste. Standard potential data for Y, La, Ce, Pr, and Gd in molten LiCl-KCl were obtained. Americium data obtained were standard potentials in molten
Daixin Li; Tianran Zhang; Siqi Yang; Zhanliang Tao; Jun Chen
2011-01-01
A systematic consideration of the compounds made up of Li, Mg and H has been taken with respect to the structural, electronic, and thermodynamic properties, by means of density functional theory (DFT). Through the database mining approach, the ground state structures of LiMgH3 and Li2MgH4 are identified to be R3c and Pbam, respectively. The Li–Mg–H ternary hydrides are insulators dominated
An EQT-cDFT approach to determine thermodynamic properties of confined fluids.
Mashayak, S Y; Motevaselian, M H; Aluru, N R
2015-06-28
We present a continuum-based approach to predict the structure and thermodynamic properties of confined fluids at multiple length-scales, ranging from a few angstroms to macro-meters. The continuum approach is based on the empirical potential-based quasi-continuum theory (EQT) and classical density functional theory (cDFT). EQT is a simple and fast approach to predict inhomogeneous density and potential profiles of confined fluids. We use EQT potentials to construct a grand potential functional for cDFT. The EQT-cDFT-based grand potential can be used to predict various thermodynamic properties of confined fluids. In this work, we demonstrate the EQT-cDFT approach by simulating Lennard-Jones fluids, namely, methane and argon, confined inside slit-like channels of graphene. We show that the EQT-cDFT can accurately predict the structure and thermodynamic properties, such as density profiles, adsorption, local pressure tensor, surface tension, and solvation force, of confined fluids as compared to the molecular dynamics simulation results. PMID:26133419
Brown, Greg [ORNL; Rusanu, Aurelian [ORNL; Daene, Markus W [ORNL; Nicholson, Don M [ORNL; Eisenbach, Markus [ORNL; Fidler, Jane L [ORNL
2011-01-01
The Wang-Landau method [F. Wang and D. P. Landau, Phys. Rev. E 64, 056101 (2001)] is an efficient way to calculate the density of states (DOS) for magnetic systems, and the DOS can then be used to rapidly calculate the thermodynamic properties of the system. A technique is presented that uses the DOS for a simple Hamiltonian to create a stratified sample of configurations which are then used calculate a warped DOS for more realistic Hamiltonians. This technique is validated for classical models of bcc Fe with exchange interactions of increasing range, but its real value is using the DOS for a model Hamiltonian calculated on a workstation to select the stratified set of configurations whose energies can then be calculated for a density-functional Hamiltonian. The result is an efficient first-principles calculation of thermodynamic properties such as the specific heat and magnetic susceptibility. Another technique uses the sample configurations to calculate the parameters of a model exchange interaction using a least-squares approach. The thermodynamic properties can be subsequently evaluated using traditional Monte Carlo techniques for the model exchange interaction. Finally, a technique that uses the configurations to train a neural network to estimate the configuration energy is also discussed. This technique could potentially be useful in identifying the configurations most important in calculating the warped DOS. VC2011 American Institute of Physics. [doi:10.1063/1.3565413
Thermodynamic properties and bulk viscosity near phase transition in the Z(2) and O(4) models
Bao-Chun Li; Mei Huang
2009-03-21
We investigate the thermodynamic properties including equation of state, the trace anomaly, the sound velocity and the specific heat, as well as transport properties like bulk viscosity in the Z(2) and O(4) models in the Hartree approximation of Cornwall-Jackiw-Tomboulis (CJT) formalism. We study these properties in different cases, e.g. first order phase transition, second order phase transition, crossover and the case without phase transition, and discuss the correlation between the bulk viscosity and the thermodynamic properties of the system. We find that the bulk viscosity over entropy density ratio exhibits an upward cusp at the second order phase transition, and a sharp peak at the 1st order phase transition. However, this peak becomes smooth or disappears in the case of crossover. This indicates that at RHIC, where there is no real phase transition and the system experiences a crossover, the bulk viscosity over entropy density might be small, and it will not affect too much on hadronization. We also suggest that the bulk viscosity over entropy density ratio is a better quantity than the shear viscosity over entropy density ratio to locate the critical endpoint.
Structural and Thermodynamic Properties of Amyloid-? Peptides: Impact of Fragment Size
NASA Astrophysics Data System (ADS)
Kitahara, T.; Wise-Scira, O.; Coskuner, O.
2010-10-01
Alzheimer's disease is a progressive neurodegenerative disease whose physiological characteristics include the accumulation of amyloid-containing deposits in the brain and consequent synapse and neuron loss. Unfortunately, most widely used drugs for the treatment can palliate the outer symptoms but cannot cure the disease itself. Hence, developing a new drug that can cure it. Most recently, the ``early aggregation and monomer'' hypothesis has become popular and a few drugs have been developed based on this hypothesis. Detailed understanding of the amyloid-? peptide structure can better help us to determine more effective treatment strategies; indeed, the structure of Amyloid has been studied extensively employing experimental and theoretical tools. Nevertheless, those studies have employed different fragment sizes of Amyloid and characterized its conformational nature in different media. Thus, the structural properties might be different from each other and provide a reason for the existing debates in the literature. Here, we performed all-atom MD simulations and present the structural and thermodynamic properties of A?1-16, A?1-28, and A?1-42 in the gas phase and in aqueous solution. Our studies show that the overall structures, secondary structures, and the calculated thermodynamic properties change with increasing peptide size. In addition, we find that the structural properties of those peptides are different from each other in the gas phase and in aqueous solution.
Improved relationships for the thermodynamic properties of carbon phases at detonation conditions
NASA Astrophysics Data System (ADS)
Stiel, L. I.; Baker, E. L.; Murphy, D. J.
2014-05-01
Accurate volumetric and heat capacity relationships have been developed for graphite and diamond carbon forms for use with the Jaguar thermochemical equilibrium program for the calculation of the detonation properties of explosives. Available experimental thermodynamic properties and Hugoniot values have been analyzed to establish the equations of state for the carbon phases. The diamond-graphite transition curve results from the equality of the chemical potentials of the phases. The resulting relationships are utilized to examine the actual phase behaviour of carbon under shock conditions. The existence of metastable carbon states is established by analyses of Hugoniot data for hydrocarbons and explosives at elevated temperatures and pressures. The accuracy of the resulting relationships is demonstrated by comparisons for several properties, including the Hugoniot behaviour of oxygen-deficient explosives at overdriven conditions.
Temperature Dependence of Thermodynamic Properties of Thallium Chloride and Thallium Bromide
NASA Astrophysics Data System (ADS)
Kavanoz, H. B.
2015-02-01
Thermodynamic properties as lattice parameters, thermal expansion, heat capacities Cp and Cv, bulk modulus, and Gruneisen parameter of ionic halides TlCl and TlBr in solid and liquid phases were studied using classical molecular dynamics simulation (MD) with interionic Vashistha-Rahman (VR) model potential. In addition to the static and transport properties which have been previously reported by the author [13], this study further confirms that temperature dependence of the calculated thermophysical properties of TlCl and TlBr are in agreement with the available experimental data at both solid and liquid phases in terms of providing an alternative rigid ion potential. The results give a fairly good description of TlCl and TlBr in the temperature range 10-1000 K.
Computer programs for thermodynamic and transport properties of hydrogen (tabcode-II)
NASA Technical Reports Server (NTRS)
Roder, H. M.; Mccarty, R. D.; Hall, W. J.
1972-01-01
The thermodynamic and transport properties of para and equilibrium hydrogen have been programmed into a series of computer routines. Input variables are the pair's pressure-temperature and pressure-enthalpy. The programs cover the range from 1 to 5000 psia with temperatures from the triple point to 6000 R or enthalpies from minus 130 BTU/lb to 25,000 BTU/lb. Output variables are enthalpy or temperature, density, entropy, thermal conductivity, viscosity, at constant volume, the heat capacity ratio, and a heat transfer parameter. Property values on the liquid and vapor boundaries are conveniently obtained through two small routines. The programs achieve high speed by using linear interpolation in a grid of precomputed points which define the surface of the property returned.
Milton Blander
2000-01-01
Modern concepts and theories have created the ability to predict the thermodynamic properties of high-temperature liquid solutions\\u000a (molten salts, metals, and slags) and vapors. These advances have made it possible to calculate thermodynamic properties and\\u000a total chemistries for many technologically and scientifically important systems. Specific theories include (1) a cycle for\\u000a accurately calculating the solubility products of relatively insoluble salts
S. Tanasescu; N. D. Totir; D. I. Marchidan; A. Turcanu
1997-01-01
In order to obtain a better understanding of the stability limits of perovskite phases used in new SOFC (solid oxide fuel cell) cathodes materials, a study of the thermodynamic properties of some perovskite-type oxides based on lanthanum strontium ferrite manganite and lanthanum strontium manganite was initiated. For the determination of thermodynamic quantities, a solid state electrochemical technique has been employed.
Compatible solutes: Thermodynamic properties and biological impact of ectoines and prolines.
Held, Christoph; Neuhaus, Thorsten; Sadowski, Gabriele
2010-11-01
Compatible solutes like ectoine and its derivatives are deployed by halophile organisms as osmolytes to sustain the high salt concentration in the environment. This work investigates the relation of the thermodynamic properties of compatible solutes and their impact as osmolytes. The ectoines considered in this work are ectoine, hydroxyectoine, and homoectoine. Besides solution densities (15-45°C) and solubilities in water (3-80°C), component activity coefficients in the aqueous solutions were determined in the temperature range between 0 and 50°C. The latter is important for adjusting a certain water activity and therewith a respective osmotic pressure within a cell. The characteristic effect of ectoines is compared to that of prolines, as well as to that of incompatible solutes as salts and urea. The experimental results show that the influence on the activity (coefficient) of water is quite different for compatible and incompatible solutes: whereas compatible solutes cause decreasing water activity coefficients, incompatible solutes lead to an increase in water activity coefficients. Based on this quantity, the paper discusses the impact of various osmolytes on biological systems and contributes to the explanation why some osmolytes are more often and at other temperatures used than others. Moreover, it was found that the anti-stress effect of an osmolyte is weakened in the presence of a salt. Finally, it is shown that the thermodynamic properties of compatible solutes can be modeled and even predicted using the thermodynamic model PC-SAFT (Perturbed-Chain Statistical Associating Fluid Theory). PMID:20719425
Tanasescu, S.; Totir, N.D.; Marchidan, D.I.; Turcanu, A. [Inst. of Physical Chemistry, Bucharest (Romania)] [Inst. of Physical Chemistry, Bucharest (Romania)
1997-07-01
In order to obtain a better understanding of the stability limits of perovskite phases used in new SOFC (solid oxide fuel cell) cathodes materials, a study of the thermodynamic properties of some perovskite-type oxides based on lanthanum strontium ferrite manganite and lanthanum strontium manganite was initiated. For the determination of thermodynamic quantities, a solid state electrochemical technique has been employed. The relative partial molar free energies, enthalpies, and entropies of oxygen dissolution in the perovskite phase, as well as the partial pressures of oxygen, have been obtained in the temperature range of 1,073--1,273 K. The results evidence the influence of different compositional variables on the thermodynamic properties.
Quantum topological method studies on the thermodynamic properties of polychlorinated phenoxazines
NASA Astrophysics Data System (ADS)
Xiao, Fangzhu; Peng, Guowen; Nie, Changming; Wu, Yaxin; Dai, Yimin
2014-09-01
The novel quantum topological indices PY1,2 were derived from molecular structure combined with the effect of atom space, the character of bonding atoms (such as equilibrium electro-negativity) and the branching effect between the atoms. The quantitative structure-property relationships (QSPRs) were proposed between PY1,2 and the thermodynamic properties (?fH?, ?fG? and ?fGR?) of phenoxazine (Phx) and 135 kinds of polychlorinated phenoxazines (PCPXs), by Multiple linear regression (MLR) analysis method. The high-quality prediction models were evidenced by the correlation coefficient R, the standard error of estimate S, the Fisher statistic value and the cross-validated correlation coefficient RCV. With the new QSPR model, we are able to predict a wide range of thermodynamic properties of an extensive number of molecules. And the model is statistically significant and shows good stability for data variation as tested by the leave-one-out cross-validation (LOO-CV).
Thermodynamic Properties of Ethylene from the Freezing Line to 450 K at Pressures to 260 MPa
NASA Astrophysics Data System (ADS)
Jahangiri, Majid; Jacobsen, Richard T.; Stewart, Richard B.; McCarty, Robert D.
1986-04-01
A new fundamental equation explicit in Helmholtz energy for thermodynamic properties of ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. Independent equations for the vapor pressure for the saturated liquid and vapor densities as functions of temperature, and for the ideal gas heat capacity are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least-squares fit to selected P-?-T data, saturated liquid, and saturated vapor density data to define the phase equilibrium criteria for coexistence, Cv data, velocity of sound data, and second virial coefficient data. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), and velocity of sound are included. Tables of thermodynamic properties of ethylene are given for liquid and vapor states within the range of validity of the fundamental equation. The fundamental equation reported here may generally be used to calculate pressures and densities with an uncertainty of ±0.1%, heat capacities within ±3%, and velocity of sound values within ±1%. Comparisons of calculated properties to experimental data are included to verify the accuracy of the formulation.
Critical evaluation and optimization of the thermodynamic properties of liquid tin solutions
NASA Astrophysics Data System (ADS)
Heuzey, Marie-Claude; Pelton, Arthur D.
1996-10-01
Thermodynamic and phase equilibrium data for the following 18 elements in molten Sn were collected and critically evaluated: Al, Ca, Ce, Co, Cr, Cu, Fe, H, Mg, Mo, Na, Ni, O, P, S, Se, Si, and Ti. Binary and ternary data were optimized to give polynomial expressions for the excess Gibbs energies as functions of temperature and composition. For some solutes, the optimized expressions are valid over the entire composition range 0 ? XSn ? 1. In other cases, the expressions apply to Snrich solutions. Solute-solute interaction terms were estimated where data were not available. The optimized Gibbs energy expressions are also presented in the form of interaction parameters, and the equivalence between the polynomial and interaction parameter formalisms is discussed. Through the Kohler equation, or the modified interaction parameter formalism, the thermodynamic properties of the multicomponent solution of 18 elements in Sn can be calculated. The database is suitable for computer storage and manipulation.
Fang, Yapeng; Al-Assaf, Saphwan; Sakata, Makoto; Phillips, Glyn O; Schultz, Matthias; Monnier, Vivianne
2007-10-31
The instability of some industrially important synthetic azo colorants, including sunset yellow, azorubine, and allura red, toward gum arabic in aqueous solution has been a long-standing problem for the beverage and confectionery industries. Precipitation of these colorants causes the deterioration of product appearance and properties. This work examines the origin and nature of the problem by analysis of the precipitate and thermodynamic studies of gum arabic-colorant interactions using isothermal titration calorimetry (ITC). The presence of divalent alkaline earth metals in gum arabic samples, that is, calcium and magnesium, is shown to be responsible for the precipitation of the azo colorants. There is no direct interaction between gum arabic and the colorant molecules, and the precipitate is formed likely due to the mediation/bridging by the divalent cations. The thermodynamic knowledge gained from the ITC studies, for example, binding affinity, stoichiometry, and enthalpy, enables interpretation of many industrial observations. PMID:17910512
Effects of heavy ion irradiation on the thermodynamic and transport properties of YBCO
NASA Astrophysics Data System (ADS)
Luo, Xu; Leroux, Maxime; Mishra, Vivek; Ling, Xinsheng; Welp, Ulrich; Kwok, Wai-Kwong
2015-03-01
The effects of Au heavy ion irradiation (HII) on the transport and thermodynamic properties of untwined YBCO crystals irradiated to dose matching fields of B? = 6 Tesla and 1 Tesla along the crystallographic c-axis were studied by angle resolved magnetoresistivtiy and high resolution AC specific heat measurements. Results from transport measurements confirm an enhancement in the ab-plane critical current for magnetic fields aligned along the columnar defects induced by HII. Surprisingly, specific heat measurements reveal a reduction in the thermodynamic upper critical field anisotropy of YBCO by about one half in the B? = 6T crystal. Moreover, for the B? = 1T crystal, we found the formation of an anomalous peak in the critical temperature near the direction of HII which may be associated with the Bose-glass transition. Work supported by Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.
Quasi-harmonic approximation of thermodynamic properties of ice Ih, II, and III
Ramirez, R; Fernandez-Serra, M -V; Herrero, C P; 10.1063/1.4737862
2012-01-01
Several thermodynamic properties of ice Ih, II, and III are studied by a quasi-harmonic approximation and compared to results of quantum path integral and classical simulations. This approximation allows to obtain thermodynamic information at a fraction of the computational cost of standard simulation methods, and at the same time permits studying quantum effects related to zero point vibrations of the atoms. Specifically we have studied the crystal volume, bulk modulus, kinetic energy, enthalpy and heat capacity of the three ice phases as a function of temperature and pressure. The flexible q-TIP4P/F model of water was employed for this study, although the results concerning the capability of the quasi-harmonic approximation are expected to be valid independently of the employed water model. The quasi-harmonic approximation reproduces with reasonable accuracy the results of quantum and classical simulations showing an improved agreement at low temperatures (T < 100 K). This agreement does not deteriorate ...
Thermodynamic Properties of Rock-Forming Garnets: How Well Known are They?
NASA Astrophysics Data System (ADS)
Geiger, C. A.; Dachs, E.
2011-12-01
Garnet is an important rock-forming mineral whose geological occurrence is widespread. The silicate garnets (E3G2Si3O12) show extensive compositional variability and the various end-members are stable over an enormous range of rock compositions and pressure and temperature conditions. Extensive geothermometry and geobarometry studies involving garnet have been made. Thus, much research has been done to determine garnet's thermodynamic properties. There are now several internally consistent mineralogical thermodynamic databases and their use is widespread. It is common belief in some/many circles that the present databases represent "the final word" on thermodynamic properties at least in terms of most end-member silicates. The question arises - How true is this assumption in the case of garnet? We have been and are presently engaged in investigating the thermodynamic properties of garnet, where volumetric properties and heat-capacity behavior play a central role. The volumes of the various end-member garnets are now known precisely. Only secondary effects arising from extra minor components (e.g., OH-,Fe3+,Mn3+) have yet to be worked out exactly. In terms of heat capacity Cp behavior, new calorimetric data allow improved understanding. Low T calorimetric measurements on spessartine were made recently and show that previous estimates for S° were in error (Dachs et al. 2009). New unpublished calorimetric results on grossular appear to have resolved long-standing uncertainty regarding its precise S° value. S° for silica-free hydrogrossular has also been determined for the first time. Cp measurements are now focusing on almandine and here low T electronic and magnetic properties must be considered. One can conclude that Cp, S°, ?H°f, V and ?G°f for the common silicate garnet end-members are now well determined to about 1000 K. Cp behavior above roughly 1000 K is less certain for some garnets (e.g., almandine, spessartine). What about thermodynamic behavior of garnet solid solutions? Here, there is much less is known (Geiger 1999). The precise mixing behavior of most garnet binaries, for example, is not understood. An exception is the pyrope-grossular binary, which has now been investigated numerous times and some consensus on its mixing properties now exist. In a related area, crystal-chemical investigations are providing good insight on possible macroscopic thermodynamic mixing behavior. Here, for example, low temperature synchrotron measurements on line broadening of powder diffraction lines give the first quantitative lattice-strain determinations on a solid solution (Dapiaggi et al. 20005). The asymmetric nature of the mixing functions ?Hex, ?Sex, and ?Vex can be explained via strain and local Ca/Mg-O bond behavior. Another area needing further investigation is short-range order. 29Si NMR spectroscopic study of synthetic Py-Gr garnets indicates that some short-range Ca-Mg order may be present. Bosenick et al. (1999) estimate that configurational entropy effects of about 2 J/mole.K may result at T > 1000 °C. It remains to be determined, however, what the structural state is at lower temperatures of 600 to 900 °C. The degree of short-range order could be substantial in metamorphic garnet solid solutions.
Emergence of equilibrium thermodynamic properties in quantum pure states. I. Theory
Fresch, Barbara; Moro, Giorgio J. [Department of Chemical Science, University of Padova, Via Marzolo 1, Padova 35131 (Italy)
2010-07-21
Investigation on foundational aspects of quantum statistical mechanics recently entered a renaissance period due to novel intuitions from quantum information theory and to increasing attention on the dynamical aspects of single quantum systems. In the present contribution a simple but effective theoretical framework is introduced to clarify the connections between a purely mechanical description and the thermodynamic characterization of the equilibrium state of an isolated quantum system. A salient feature of our approach is the very transparent distinction between the statistical aspects and the dynamical aspects in the description of isolated quantum systems. Like in the classical statistical mechanics, the equilibrium distribution of any property is identified on the basis of the time evolution of the considered system. As a consequence equilibrium properties of quantum system appear to depend on the details of the initial state due to the abundance of constants of the motion in the Schroedinger dynamics. On the other hand the study of the probability distributions of some functions, such as the entropy or the equilibrium state of a subsystem, in statistical ensembles of pure states reveals the crucial role of typicality as the bridge between macroscopic thermodynamics and microscopic quantum dynamics. We shall consider two particular ensembles: the random pure state ensemble and the fixed expectation energy ensemble. The relation between the introduced ensembles, the properties of a given isolated system, and the standard quantum statistical description are discussed throughout the presentation. Finally we point out the conditions which should be satisfied by an ensemble in order to get meaningful thermodynamical characterization of an isolated quantum system.
Livesay, Dennis R; Huynh, Dang H; Dallakyan, Sargis; Jacobs, Donald J
2008-01-01
Background Gram-negative bacteria use periplasmic-binding proteins (bPBP) to transport nutrients through the periplasm. Despite immense diversity within the recognized substrates, all members of the family share a common fold that includes two domains that are separated by a conserved hinge. The hinge allows the protein to cycle between open (apo) and closed (ligated) conformations. Conformational changes within the proteins depend on a complex interplay of mechanical and thermodynamic response, which is manifested as an increase in thermal stability and decrease of flexibility upon ligand binding. Results We use a distance constraint model (DCM) to quantify the give and take between thermodynamic stability and mechanical flexibility across the bPBP family. Quantitative stability/flexibility relationships (QSFR) are readily evaluated because the DCM links mechanical and thermodynamic properties. We have previously demonstrated that QSFR is moderately conserved across a mesophilic/thermophilic RNase H pair, whereas the observed variance indicated that different enthalpy-entropy mechanisms allow similar mechanical response at their respective melting temperatures. Our predictions of heat capacity and free energy show marked diversity across the bPBP family. While backbone flexibility metrics are mostly conserved, cooperativity correlation (long-range couplings) also demonstrate considerable amount of variation. Upon ligand removal, heat capacity, melting point, and mechanical rigidity are, as expected, lowered. Nevertheless, significant differences are found in molecular cooperativity correlations that can be explained by the detailed nature of the hydrogen bond network. Conclusion Non-trivial mechanical and thermodynamic variation across the family is explained by differences within the underlying H-bond networks. The mechanism is simple; variation within the H-bond networks result in altered mechanical linkage properties that directly affect intrinsic flexibility. Moreover, varying numbers of H-bonds and their strengths control the likelihood for energetic fluctuations as H-bonds break and reform, thus directly affecting thermodynamic properties. Consequently, these results demonstrate how unexpected large differences, especially within cooperativity correlation, emerge from subtle differences within the underlying H-bond network. This inference is consistent with well-known results that show allosteric response within a family generally varies significantly. Identifying the hydrogen bond network as a critical determining factor for these large variances may lead to new methods that can predict such effects. PMID:18700034
Calculating the thermodynamic properties of aqueous solutions of alkali metal carboxylates
NASA Astrophysics Data System (ADS)
Rudakov, A. M.; Sergievskii, V. V.; Zhukova, T. V.
2014-06-01
A modified Robinson-Stokes equation with terms that consider the formation of ionic hydrates and associates is used to describe thermodynamic properties of aqueous solutions of electrolytes. The model is used to describe data on the osmotic coefficients of aqueous solutions of alkali metal carboxylates, and to calculate the mean ionic activity coefficients of salts and excess Gibbs energies. The key contributions from ionic hydration and association to the nonideality of solutions is determined by analyzing the contributions of various factors. Relations that connect the hydration numbers of electrolytes with the parameters of the Pitzer-Mayorga equation and a modified Hückel equation are developed.
Thermodynamic and optical properties of mixed-salt aerosols of atmospheric importance
Ignatius N. Tang
1997-01-01
Extensive water activity, density, and refractive index data at 25øC are reported for mixed-salt solutions, NaC1-KCI, NaC1-NaNO 3, NaCI-Na2SO 4, Na2SO4-NaNO 3, and (NH4)2SO 4- Na2SO 4. The data are obtained from hydration experiments using the single-particle levitation technique developed recently for measuring the thermodynamic and optical properties of microdroplets. These data, coveting the whole concentration range from dilute solutions
Smith, W.H.; Costa, D.A.
1998-12-31
This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this work was to establish a capability for the measurement of fundamental thermodynamic properties of actinide elements in room temperature molten salts. This capability will be used to study in detail the actinide chloro- and oxo-coordination chemistries that dominate in the chloride-based molten salt media. Uranium will be the first actinide element under investigation.
Thermodynamic Properties and Decomposition of Lithium Hexafluoroarsenate, LiAsF 6
K. S. Gavrichev; G. A. Sharpataya; V. E. Gorbunov; L. N. Golushina; V. N. Plakhotnik; I. V. Goncharova; V. M. Gurevich
2003-01-01
The heat capacity of lithium hexafluoroarsenate is determined in the temperature range 50–750 K by adiabatic and differential scanning calorimetry techniques. The thermodynamic properties of LiAsF6 under standard conditions are evaluated: Cp0(298.15 K) = 162.5 ± 0.3 J\\/(K mol), S0(298.15 K) = 173.4 ± 0.4 J\\/(K mol), F0(298.15 K) = 81.69 ± 0.20 J\\/(K mol), and H0(298.15 K) – H0(0)
NASA Technical Reports Server (NTRS)
Rees, T. H.; Suttles, J. T.
1972-01-01
A computer study was conducted to compare the numerical behavior of two approaches to describing the thermodynamic properties of oxygen near the critical point. Data on the relative differences between values of specific heats at constant pressure (sub p) density, and isotherm and isochor derivatives of the equation of state are presented for selected supercritical pressures at temperatures in the range 100 to 300 K. The results of a more detailed study of the sub p representations afforded by the two methods are also presented.
Thermodynamic properties of HFO1234yf (2,3,3,3-tetrafluoropropene)
Katsuyuki Tanaka; Yukihiro Higashi
2010-01-01
Measurements of the thermodynamic properties of HFO-1234yf were conducted. The critical temperature TC, critical density ?C, and critical pressure PC, were measured by the visual observation of the meniscus disappearance, and were determined to be 367.85±0.01K, 478±3kg\\/m3, and 3382±3kPa, respectively. Vapor pressures were measured by a batch-type calorimeter with a metal-bellows in the temperature range from 310K to 360K and
Structural, electronic, elastic and thermodynamical properties of BaxSr1-xLiH3
NASA Astrophysics Data System (ADS)
Bahloul, B.; Bentabet, A.; Amirouche, L.; Bouhadda, Y.; Fenineche, N.
2011-12-01
In this paper, we aim to study the structural, electronic, elastic and thermodynamical properties of BaxSr1-xLiH3 using ab initio calculations within the generalized gradient approximation and local density approximation. In particular, the lattice constant, bulk modulus, second-order elastic constants (Cij) and electronic band structures are calculated and compared with the available experimental and other theoretical values. In addition, we have also predicted the variation of Young's modulus (E), Poisson's ratio (v), anisotropy factor (A), sound velocities, Debye temperature (?D) and melting temperature (Tm) as a function of the Ba concentration (x).
Thermodynamic properties and equation of state of zircon ZrSiO{sub 4}
Mittal, R.; Chaplot, S.L.; Choudhury, N. [Bhabha Atomic Research Centre, Trombay (India). Solid State Physics Div.; Loong, C.K. [Argonne National Lab., IL (United States)
1998-11-01
The silicate mineral zircon is a host material for radioactive materials in the earth`s crust and is a natural candidate for usage as a nuclear waste storage material. Lattice dynamical calculations have been carried out to understand its thermodynamic properties and high pressure behavior. The calculated phonon density of states, variation of phonon frequencies with pressure and equation of state are in good agreement with the available experimental data. One of the zone center optic mode involving SiO{sub 4} rotations becomes soft at 47 GPa.
Exact thermodynamics and Luttinger liquid properties of the integrable t-J model
G. Juttner; A. Klumper; J. Suzuki
1996-11-08
A Trotter-Suzuki mapping is used to calculate the finite-temperature properties of the one-dimensional supersymmetric $t-J$ model. This approach allows for the exact calculation of various thermodynamical properties by means of the quantum transfer matrix (QTM). The free energy and other interesting quantities are obtained such as the specific heat and compressibility. For the largest eigenvalue of the QTM leading to the free energy a set of just two non-linear integral equations is presented. These equations are studied analytically and numerically for different particle densities and temperatures. The structure of the specific heat is discussed in terms of the elementary charge as well as spin excitations. Special emphasis is placed on the study of the low-temperature behavior confirming scaling predictions by conformal field theory and Luttinger liquid theory. To our knowledge this is the first complete investigation of a strongly correlated electron system on a lattice at finite temperature.
NASA Astrophysics Data System (ADS)
Mishra, Rashmi; Srivastava, Anubha; Sharma, Anamika; Tandon, Poonam; Baraldi, Cecilia; Gamberini, Maria Christina
2013-01-01
The global problem of advancing bacterial resistance to newer drugs has led to renewed interest in the use of Chloramphenicol Palmitate (C27H42Cl2N2O6) [Palmitic acid alpha ester with D-threo-(-),2-dichloro-N-(beta-hydroxy-alpha-(hydroxymethyl)-p-nitrophenethyl)acetamide also known as Detereopal]. The characterization of the three polymorphic forms of Chloramphenicol Palmitate (CPP) was done spectroscopically by employing FT-IR and FT-Raman techniques. The equilibrium geometry, various bonding features, and harmonic wavenumbers have been investigated for most stable form A with the help of DFT calculations and a good correlation was found between experimental data and theoretical values. Electronic properties have been analyzed employing TD-DFT for both gaseous and solvent phase. The theoretical calculation of thermodynamical properties along with NBO analysis has also been performed to have a deep insight into the molecule for further applications.
Improved Relationships for the Thermodynamic Properties of Carbon Phases at Detonation Conditions
NASA Astrophysics Data System (ADS)
Stiel, Leonard; Baker, Ernest; Murphy, Daniel
2013-06-01
In order to improve the procedures utilized in the Jaguar thermochemical program for carbon, volumetric and heat capacity relationships have been developed for graphite, diamond, and liquid carbon forms. Available experimental thermodynamic property and Hugoniot data have been analyzed to establish optimum equations of state for the carbon phases. The appropriate carbon form or multiple forms at equilibrium results from the minimization of the Gibbs free energy of the system. The resulting relationships are utilized to examine the phase behavior of carbon at elevated temperatures and pressures. The behavior of metastable carbon states is optimized by analyses of Hugoniot data for hydrocarbons, and C-J and cylinder velocities for a database of CHNO explosives. The accuracy of the resulting relationships is demonstrated by comparisons for several properties, including the Hugoniot behavior of oxygen-deficient explosives at overdriven conditions.
Physical and thermodynamic properties of Al(n)C(m) clusters: quantum-chemical study.
Loukhovitski, Boris I; Sharipov, Alexander S; Starik, Alexander M
2015-02-26
Geometrical structures and physical properties, such as rotational constants and characteristic vibrational temperatures, collision diameter, enthalpy of formation, dipole moment, static isotropic polarizability, and magnetic moment of different forms of Al(n)C(m) clusters with n = 0-5, m = 0-5, have been studied with the usage of density functional theory. Different forms of clusters with the electronic energy up to 5 eV have been identified by using the original multistep heuristic algorithm based on semiempirical calculations and density functional theory. Temperature dependencies of thermodynamic properties such as enthalpy, entropy, and specific heat capacity were calculated for both the individual isomers and the Boltzmann ensembles of each class of clusters. PMID:25629238
Thermodynamic and optical properties of mixed-salt aerosols of atmospheric importance
NASA Astrophysics Data System (ADS)
Tang, Ignatius N.
1997-01-01
Extensive water activity, density, and refractive index data at 25°C are reported for mixed-salt solutions, NaCl-KCl, NaCl-NaNO3, NaCl-Na2SO4, Na2SO4-NaNO3, and (NH4)2SO4-Na2SO4. The data are obtained from hydration experiments using the single-particle levitation technique developed recently for measuring the thermodynamic and optical properties of microdroplets. These data, covering the whole concentration range from dilute solutions to high supersaturations, provide an opportunity to explore the light-scattering properties of both internal and external mixtures of the chloride, sulfate, and nitrate aerosols of atmospheric importance. It is shown that for sulfate and nitrate aerosols as solution droplets, the light-scattering properties do not differ appreciably among all mixture types and compositions, as long as the dry-salt aerosols have the same particle-size distribution. However, for mixed-salt aerosols containing NaCl, the light-scattering properties do depend upon the composition and particle-size distribution, although not so much on the mixture type.
Calculations and curve fits of thermodynamic and transport properties for equilibrium air to 30000 K
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Lee, Kam-Pui; Thompson, Richard A.; Yos, Jerrold M.
1991-01-01
A self-consistent set of equilibrium air values were computed for enthalpy, total specific heat at constant pressure, compressibility factor, viscosity, total thermal conductivity, and total Prandtl number from 500 to 30,000 K over a range of 10(exp -4) atm to 10(exp 2) atm. The mixture values are calculated from the transport and thermodynamic properties of the individual species provided in a recent study by the authors. The concentrations of the individual species, required in the mixture relations, are obtained from a free energy minimization calculation procedure. Present calculations are based on an 11-species air model. For pressures less than 10(exp -2) atm and temperatures of about 15,000 K and greater, the concentrations of N(++) and O(++) become important, and consequently, they are included in the calculations determining the various properties. The computed properties are curve fitted as a function of temperature at a constant value of pressure. These curve fits reproduce the computed values within 5 percent for the entire temperature range considered here at specific pressures and provide an efficient means for computing the flowfield properties of equilibrium air, provided the elemental composition remains constant at 0.24 for oxygen and 0.76 for nitrogen by mass.
Thermodynamic properties of solid helium using an anharmonic anisotropic continuum model
Berker, Terrell Dunlap
1980-01-01
An anharmonic anisotropic continuum model is used to describe the thermodynamic properties of solid helium for all three structures (hcp, fcc, and bcc) and both isotopes. Using a 6-n potential with the de Boer value for the attractive parameter, the two repulsive parameters b/sub n/ and n are varied to obtain a best fit to experimental hcp /sup 4/He data. The n = 11 potential gives good volume dependence over the entire experimentally accessible volume range, but too large an isotope effect. The n = 10 potential gives a better mass dependence, but a less satisfactory volume dependence. A detailed comparison of the calculations with experimental data shows that while it is possible to fit the volume dependence of the pressure, bulk modulus, and Debye temperature over a very wide range, the model overestimates the zero-point contribution to the free energy. The conclusion is reached that the major discrepancies obtained result from the failure of the continuum model to take account of dispersion. This failure can be remedied by artificially endowing the continuum with dispersion. A program for the further development of the model is outlined. It appears that the approach should be a practical one for realistic calculations of thermodynamic properties over wide volume ranges and useful for the estimation of interatomic potentials from solid state data.
Thermodynamic Properties of Ising Spins on the Triangular Kagom'e Lattice
NASA Astrophysics Data System (ADS)
Zhuang, Bilin; Lannert, Courtney
2009-03-01
The triangular Kagom'e lattice can be constructed by inserting a lattice site on each bond of the Kagom'e lattice. Each unit cell contains 6 a-sites, 3 b-sites, 6 aa-bonds and 12 ab-bonds. The lattice with antiferromagnetic aa-bonds is known to exhibit geometrical frustration at low temperatures. We applied analytical methods and Monte Carlo simulations to study a system of Ising Spins on the lattice and investigated its thermodynamics properties. In particular, the heat capacity of the model exhibits interesting features based on the strength and the sign of coupling constants Jaa and Jab. In the case when the aa-interaction is antiferromagnetic, the heat capacity shows two broad peaks at kT/|Jab|1.8 and at kT/|Jaa|1.8. In the case when the aa-interaction is ferromagnetic, the heat capacity shows a sharp peak at kT/|Jab|1.9 and another low broad peak at around kT/|Jaa|1.4. We also studied a much simpler system of two a-trimers connected with b-sites to reproduce the thermodynamics behaviors of the more complicated triangular Kagom'e lattice and to further understand the origin of its interesting properties.
Evaluation of the thermodynamic properties of hydrated metal oxide nanoparticles by INS techniques
Spencer, Elinor [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Ross, Dr. Nancy [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Parker, Stewart F. [ISIS Facility, Rutherford Appleton Laboratory (ISIS)] [ISIS Facility, Rutherford Appleton Laboratory (ISIS); Kolesnikov, Alexander I [ORNL] [ORNL
2013-01-01
In this contribution we will present a detailed methodology for the elucidation of the following aspects of the thermodynamic properties of hydrated metal oxide nanoparticles from high-resolution, low-temperature inelastic neutron scattering (INS) data: (i) the isochoric heat capacity and entropy of the hydration layers both chemi- and physisorbed to the particle surface; (ii) the magnetic contribution to the heat capacity of the nanoparticles. This will include the calculation of the vibrational density of states (VDOS) from the raw INS spectra, and the subsequent extraction of the thermodynamic data from the VDOS. This technique will be described in terms of a worked example namely, cobalt oxide (Co3O4 and CoO). To complement this evaluation of the physical properties of metal oxide nanoparticle systems, we will emphasise the importance of high-resolution, high-energy INS for the determination of the structure and dynamics of the water species, namely molecular (H2O) and dissociated water (OH, hydroxyl), confined to the oxide surfaces. For this component of the chapter we will focus on INS investigations of hydrated isostructural rutile (a-TiO2) and cassiterite (SnO2) nanoparticles. We will complete this discussion of nanoparticle analysis by including an appraisal of the INS instrumentation employed in such studies with particular focus on TOSCA [ISIS, Rutherford Appleton Laboratory (RAL), U.K.] and the newly developed spectrometer SEQUOIA [SNS, Oak Ridge National Laboratory (ORNL), U.S.A].
NASA Astrophysics Data System (ADS)
Asta, Mark David
In this dissertation it is shown how quantum and statistical mechanical computational techniques can be combined in order to make possible the calculation of thermodynamic properties for solid-state binary substitutional alloy phases from first principles, i.e., from a knowledge of only basic crystallographic information and the atomic numbers of the alloy constituents. The framework which is discussed here for performing such calculations is based on the formalism of cluster expansions. Using this formalism the statistical mechanical problem of computing substitutional alloy thermodynamic properties can be reduced to that of solving a generalized Ising model. It is shown how the parameters describing atomic interactions in such an Ising model can be derived with the structure inversion method from the results of quantum mechanical calculations of zero-temperature total energies for a number of ordered stoichiometric alloy compounds sharing a common underlying parent structure. Once the parameters in the generalized Ising model have been derived, alloy thermodynamic properties can be calculated by a variety of statistical mechanical techniques. In the work presented here the quantum and statistical mechanical calculations have been performed using the linear muffin-tin orbital and cluster variation methods, respectively. These computational methods are both described in some detail. The formalism and computational techniques mentioned in the previous paragraph are applied to the study of alloy phase stability in the Ti-Al and Cd-Mg systems. For Cd -Mg an effort is made to determine the relative magnitudes of the contributions to the alloy free energy arising from configurational disorder, structural relaxations, as well as vibrational and electronic excitations. It is shown that when all of these different contributions to the free energy are included, the calculated solid-state portion of the composition-temperature phase diagram for the Cd -Mg system is in excellent agreement with experimental measurements. For the Ti-Al system, the thermodynamic stability of phases with fcc- and hcp-based crystal structures is studied. It is shown that the complexity of the Ti-Al phase diagram can be understood as being the result of a very close competition between stable and metastable ordered phases in this system.
The use of molecular dynamics for the thermodynamic properties of simple and transition metals
Straub, G.K.
1987-04-01
The technique of computer simulation of the molecular dynamics in metallic systems to calculate thermodynamic properties is discussed. The nature of a metal as determined by its electronic structure is used to determine the total adiabatic potential. The effective screened ion-ion interaction can then be used in a molecular dynamics simulation. The method for the construction of a molecular dynamics ensemble, its relation to the canonical ensemble, and the definition of thermodynamic functions from the Helmholtz free energy is given. The method for the analysis of the molecular dynamics results from quasiharmonic lattice dynamics and the decomposition in terms of harmonic and anharmonic contributions is given for solids. For fluid phase metals, procedures for calculating the thermodynamics and determining the constant of entropy are presented. The solid-fluid phase boundary as a function of pressure and temperature is determined using the results of molecular dynamics. Throughout, examples and results for metallic sodium are used. The treatment of the transition metal electronic d-states in terms of an effective pair-wise interaction is also discussed and the phonon dispersion curves of Al, Ni, and Cu are calculated.
NASA Astrophysics Data System (ADS)
Smirnova, N. N.; Markin, A. V.; Letyanina, I. A.; Sologubov, S. S.; Novozhilova, N. A.; Tatarinova, E. A.; Muzafarov, A. M.
2014-05-01
The temperature dependences of the heat capacities of carbosilane dendrimers of the third and sixth generations with ethyleneoxide terminal groups are examined for the first time by means of precision adiabatic vacuum calorimetry at temperatures between 6.5 and 350 K. In this temperature range, physical transformations are observed and their standard thermodynamic characteristics are determined and discussed. The standard thermodynamic functions are calculated per nominal mole of a chosen unit using the obtained experimental data: C° p ( T), H°( T) - H°(0), S°( T) - S°(0), and G°( T) - H°(0) in the interval T ? 0 to 350 K, and the standard entropies of formation at T = 298.15 K. The low-temperature ( T ? 50 K) heat capacity is analyzed using the Debye theory of specific heat and a multifractal model. The values of fractal dimension D are also determined, and conclusions on the investigated structures' topology are drawn. The corresponding thermodynamic properties of the studied dendrimers are compared as well.
Thermodynamic model for calorimetric and phase coexistence properties of coal derived fluids
Kabadi, V.N.
1991-10-01
On September 1, 1989 work was initiated on a project to extend the available vapor-liquid equilibrium (VLE) model for coal fluids to allow satisfactory predictions of excess enthalpies of coal liquids at high pressures. The available vapor liquid equilibrium model was developed with support from previous grant from DOE-PETC (Grant no. DE-FG22-89PC90541). The current project also involves measurement of some model compound VLE data and chromatographic characterization of coal liquids for distribution of heteroatoms. A computational thermodynamic model for VLE, excess enthalpies and heat capacities of coal derived liquids has been developed. The model uses the modified UNIFAC correlation for the liquid phase. Some unavailable UNIFAC interactions parameters have been regressed from experimental VLE and excess enthalpy data. The computations are carried out using the method of continuous thermodynamics. Mode is used to derive interesting conclusions on the effect of oxygen, nitrogen, and sulfur heteroatoms on the thermodynamic properties of coal liquids. When compared with limited experimental data available for coal liquids the model shows good agreement. Some progress has been made on binary VLE measurements and size exclusion chromatography of coal liquids.
Kabadi, V.N.
1991-10-01
On September 1, 1989 work was initiated on a project to extend the available vapor-liquid equilibrium (VLE) model for coal fluids to allow satisfactory predictions of excess enthalpies of coal liquids at high pressures. The available vapor liquid equilibrium model was developed with support from previous grant from DOE-PETC (Grant no. DE-FG22-89PC90541). The current project also involves measurement of some model compound VLE data and chromatographic characterization of coal liquids for distribution of heteroatoms. A computational thermodynamic model for VLE, excess enthalpies and heat capacities of coal derived liquids has been developed. The model uses the modified UNIFAC correlation for the liquid phase. Some unavailable UNIFAC interactions parameters have been regressed from experimental VLE and excess enthalpy data. The computations are carried out using the method of continuous thermodynamics. Mode is used to derive interesting conclusions on the effect of oxygen, nitrogen, and sulfur heteroatoms on the thermodynamic properties of coal liquids. When compared with limited experimental data available for coal liquids the model shows good agreement. Some progress has been made on binary VLE measurements and size exclusion chromatography of coal liquids.
NASA Astrophysics Data System (ADS)
Becker, U.; Fernández-González, A.; Prieto, M.; Harrison, R.; Putnis, A.
Thermodynamic properties of the barite-celestite solid solution were calculated using molecular principles. Cation-cation (Ba-Ba, Sr-Sr, and Ba-Sr) interaction energies were derived from a number of random and ordered cation distributions which were energy-optimized using force potentials as incorporated in the program package GULP. With these interaction energies, diagrams for the enthalpy and free energy of mixing could be computed for the entire range of the solid solution between the barite and celestite end members and for a number of annealing temperatures. These thermodynamic data show that the solid solution is nonideal. The system has a tendency for Ba2+ and Sr2+ cations to order onto alternating layers ||(100). However, this ordering scheme is thermodynamically only relevant for annealing temperatures below approximately 500K and systems that are kinetically inhibited during crystal growth. For sufficiently long annealing times at room temperature, the solid solution tends to exsolve with barite-celestite interfaces ||(100). The cell parameters a and c were calculated to have almost linear behavior for the whole solid solution, suggesting close to ideal behavior according to Vegard's law. In contrast, b tends to deviate positively from linearity, in agreement with experimental values.
Thermodynamic properties and entropy scaling law for diffusivity in soft spheres
NASA Astrophysics Data System (ADS)
Pieprzyk, S.; Heyes, D. M.; Bra?ka, A. C.
2014-07-01
The purely repulsive soft-sphere system, where the interaction potential is inversely proportional to the pair separation raised to the power n, is considered. The Laplace transform technique is used to derive its thermodynamic properties in terms of the potential energy and its density derivative obtained from molecular dynamics simulations. The derived expressions provide an analytic framework with which to explore soft-sphere thermodynamics across the whole softness-density fluid domain. The trends in the isochoric and isobaric heat capacity, thermal expansion coefficient, isothermal and adiabatic bulk moduli, Grüneisen parameter, isothermal pressure, and the Joule-Thomson coefficient as a function of fluid density and potential softness are described using these formulas supplemented by the simulation-derived equation of state. At low densities a minimum in the isobaric heat capacity with density is found, which is a new feature for a purely repulsive pair interaction. The hard-sphere and n =3 limits are obtained, and the low density limit specified analytically for any n is discussed. The softness dependence of calculated quantities indicates freezing criteria based on features of the radial distribution function or derived functions of it are not expected to be universal. A new and accurate formula linking the self-diffusion coefficient to the excess entropy for the entire fluid softness-density domain is proposed, which incorporates the kinetic theory solution for the low density limit and an entropy-dependent function in an exponential form. The thermodynamic properties (or their derivatives), structural quantities, and diffusion coefficient indicate that three regions specified by a convex, concave, and intermediate density dependence can be expected as a function of n, with a narrow transition region within the range 5
Thermodynamic properties and entropy scaling law for diffusivity in soft spheres.
Pieprzyk, S; Heyes, D M; Bra?ka, A C
2014-07-01
The purely repulsive soft-sphere system, where the interaction potential is inversely proportional to the pair separation raised to the power n, is considered. The Laplace transform technique is used to derive its thermodynamic properties in terms of the potential energy and its density derivative obtained from molecular dynamics simulations. The derived expressions provide an analytic framework with which to explore soft-sphere thermodynamics across the whole softness-density fluid domain. The trends in the isochoric and isobaric heat capacity, thermal expansion coefficient, isothermal and adiabatic bulk moduli, Grüneisen parameter, isothermal pressure, and the Joule-Thomson coefficient as a function of fluid density and potential softness are described using these formulas supplemented by the simulation-derived equation of state. At low densities a minimum in the isobaric heat capacity with density is found, which is a new feature for a purely repulsive pair interaction. The hard-sphere and n = 3 limits are obtained, and the low density limit specified analytically for any n is discussed. The softness dependence of calculated quantities indicates freezing criteria based on features of the radial distribution function or derived functions of it are not expected to be universal. A new and accurate formula linking the self-diffusion coefficient to the excess entropy for the entire fluid softness-density domain is proposed, which incorporates the kinetic theory solution for the low density limit and an entropy-dependent function in an exponential form. The thermodynamic properties (or their derivatives), structural quantities, and diffusion coefficient indicate that three regions specified by a convex, concave, and intermediate density dependence can be expected as a function of n, with a narrow transition region within the range 5 < n < 8. PMID:25122250
Siddiqui, Khawar Sohail; Cavicchioli, Ricardo; Thomas, Torsten
2002-04-01
In this study, the thermodynamic activation parameters of cold-adapted proteins from Archaeaa are described for the first time for the irreversible protein unfolding and ribosome-dependent GTPase activity of elongation factor 2 (EF-2) from the psychrotolerant Methanococcoides burtonii and the thermophilic Methanosarcina thermophila. Thermolability of Methanococcoides burtonii EF-2 was demonstrated by a low activation free-energy of unfolding as a result of low activation-enthalpy. Although structural data for EF-2 are presently limited to protein homology modeling, the observed thermodynamic properties are consistent with a low number of noncovvalent bonds or an altered solvent interaction, causing a loss of entropy during the unfolding process. A physiological concentration of potassium aspartate or potassium glutamate was shown to stabilize both proteins against irreversible denaturation by strengthening noncovalent interactions, as indicated by increased activation enthalpies. The transition state of GTPase activity for Methanococcoides burtonii EF-2 was characterized by a lower activation enthalpy than for Methanosarcina thermophila EF-2. The relative entropy changes could be explained by differential displacement of water molecules during catalysis, resulting in similar activation free energies for both proteins. The presence of solutes was shown to facilitate the breaking of enthalpy-driven interactions and structuring of more water molecules during the reaction. By studying the thermodynamic activation parameters of both GTPase activity and unfolding and examining the effects of intracellular solutes and partner proteins (ribosomes), we were able to identify enthalpic and entropic properties that have evolved in the archaeal EF-2 proteins to enable Methanococcoides burtonii and Methanosarcina thermophila to adapt to their respective thermal environments. PMID:12013435
Kang, H.S.; Ree, F.H.
1997-12-01
Recently, we developed the perturbative hypernetted-chain (PHNC) integral equation which can predict reliable thermodynamic and structural data for a system of particles interacting with either short range or long range (Coulomb) potential. The present work extends this earlier work to mixtures. This is done by employing a reference potential which is designed to satisfy a thermodynamic consistency on the isothermal compressibility as described in the next section. We test the present theory in Sec. III by applying it to plasma mixtures interacing with either an unscreened or a screened Coulomb potential. We made comparisons of results from the present theory with those from the best available theory, i.e., Rosenfeld`s density functional theory (DFT). The DFT was shown to give internal energy with three to five fignre accuracy compared to a wide range of Monte Carlo data. Meanwhile, small deviations of excess internal energy from the so-called ``liner mixing rule`` (LMR) are better predicted by a less sophiscated theory like the hypernetted- chain (HNC) equation. This rule relates thermodynamics of an unscreened mixture to those for individual components in a strongly coupled regime where the potential energy of a constituent particle is much larger than its kinetic energy. We also apply the present theory to a H{sub 2} + H mixture interacting with Morse potentials. For this sytem, comparison of thermodynamic properties and radial distribution functions from the present theory will be made with those from another successful theory of dense fluid, i.e., the HMSA equation of Zerah and Hansen.
A Thermodynamic Property Model for R-125/143a Mixtures Based on a New Cubic Equation of State
NASA Astrophysics Data System (ADS)
Zhang, Heng-Liang; Tada, Satoru; Waranabe, Koichi
The binary mixture of two hydrofluorocarbons, R-125 and R-143a, behaves almost like an azeotrope and has been considered as a promising refrigerant to substitute R-502. In this paper, we present a thermodynamic property model for the R-125/143a system, which was developed on the basis of a new cubic equation of state proposed in our previous publications. The essential thermodynamic properties such as PVTx properties, vapor-liquid equilibrium, enthalpy, entropy, isobaric specific heat, and speed of sound are well represented simultaneously by the new model in the entire fluid-phase of theR-125/143a system including the pure components.The model is valid for any composition with thermodynamic consistency to cover a range broad enough for refrigeration engineering applications. A pressure-enthalpy diagram for the R-125/143a mixture with 50 mass% R-125 is also presented.
Donohue, M.D.
1990-09-01
The purpose of this research program is to understand the relationship between macroscopic thermodynamic properties and the various types of intermolecular forces. Since coal-derived liquids contain a wide variety of compounds, a theory capable of successfully predicting the thermophysical properties for coal processes must take into account the molecular shapes and all significant intermolecular forces: dispersion forces, anisotropic forces due to dipoles and quadrupoles, as well as Lewis acid-base interactions. We have developed the Acid-Base-Perturbed-Anisotropic-Chain Theory (ABPACT), a comprehensive theory that is capable of predicting the thermophysical properties for many systems where these different intermolecular forces are present. The ABPACT can treat non-polar compounds, polar compounds and compounds that associate through Lewis acid-base interactions. In addition to our theoretical work, we have used computer simulations to evaluate (and in some cases correct) the assumptions made in this theory. We also have conducted experiments to help us better understand the interplay of different kinds of interactions in multicomponent mixtures.
Mechanical, electronic, optical, thermodynamic properties and superconductivity of ScGa3
NASA Astrophysics Data System (ADS)
Parvin, F.; Hossain, M. A.; Ali, M. S.; Islam, A. K. M. A.
2015-01-01
The rare occurrence of type-I superconductivity in binary system ScGa3 has experimentally been shown recently. In the present paper we study the electronic, optical, thermodynamic properties and some aspects of superconductivity of this compound using first-principles calculations. The mechanical properties like elastic constants, bulk modulus, shear modulus, Pugh's ductility index, Young's modulus, Poisson's ratio, elastic anisotropy factor, Peierls stress are calculated for the first time. The material is anisotropic and brittle. Electronic band structure, density of states, Fermi surfaces and bonding nature have also been studied. The optical functions are estimated and discussed for the first time. The high reflectivity is found in the ultraviolet regions up to ~13 eV and thus ScGa3 can serve as a possible shielding material for ultraviolet radiation. Thermal effects on some macroscopic properties of ScGa3 are predicted using the quasi-harmonic Debye model and phonon approximation in the temperature and hydrostatic pressure in the ranges of 0-1000 K and 0-40 GPa, respectively. The calculated electron-phonon coupling constant ?=0.52 yields Tc=2.6 K, which is in very good agreement with the experimentally observed value. The value of the coupling constant and the Ginzburg-Landau parameter (?=0.09) indicate that the compound is a weak-coupled type-I rare binary BCS superconductor.
Magnetic and thermodynamic properties of Americium-II: An Ab Initio Study
NASA Astrophysics Data System (ADS)
Wang, Jianguang; Ma, Li; Ray, Asok
2011-03-01
Hybrid density functional theory based method has been used to study the structural, magnetic, electronic, and thermodynamic properties of Americium-II. Non-magnetic, ferromagnetic (FM), and anti-ferromagnetic (AFM) configurations without and with spin-orbit coupling (SOC) have been considered. The experimental NM ground state configuration is indeed obtained for Am-II at a level of 40% HF exchange with SOC and the computed structural properties and electronic density of states are in good agreement with experimental observations. The importance of SOC is found to be significant. The phonon related properties of Am-II are presented for the NM ground state configuration and the computed heat capacity and entropy are in good agreement with the experimental measurements. The lattice constant, bulk modulus, heat capacity, and entropy of Am-II are predicted to be 9.44 a.u., 21.7 GPa, 24.3 JK-1 mol -1 , and 55.7 JK-1 mol -1 , respectively. This work is partially supported by the Welch Foundation, Houston, Texas (Grant No. Y-1525) and by the Department of Energy.
NASA Technical Reports Server (NTRS)
Weber, L. A.
1975-01-01
Compressibility measurements and thermodynamic properties data for parahydrogen were extended to higher temperatures and pressures. Results of an experimental program are presented in the form of new pressure, volume and temperature data in the temperature range 23 to 300 K at pressures up to 800 bar. Also given are tables of thermodynamic properties on isobars to 1000 bar including density, internal energy, enthalpy, entropy, specific heats at constant volume and constant pressure, velocity of sound, and surface derivatives. The accuracy of the data is discussed and comparisons are made with previous data.
NASA Astrophysics Data System (ADS)
Mao, Pingli; Yu, Bo; Liu, Zheng; Wang, Feng; Ju, Yang
2015-03-01
The structural, mechanical, electronic, and thermodynamic properties of Mg2Sr with C14-type structure under pressures ranging from 0 to 40 GPa have been systematically studied within the framework of density functional theory in this work. The results at zero pressure were in good agreement with the available theoretical and experimental values. The pressure dependence of structure and elastic constants, elastic anisotropy, Cauchy pressure, melting points, and hardness was successfully calculated and discussed. In addition, the electronic density of states (DOSs) under various pressures were investigated. Debye temperature and the dependences of thermodynamic properties on temperature and pressure were also discussed in the present paper.
NASA Technical Reports Server (NTRS)
Simmonds, A. L.; Miller, C. G., III; Nealy, J. E.
1976-01-01
Equilibrium thermodynamic properties for pure ammonia were generated for a range of temperature from 500 to 50,000 K and pressure from 0.01 to 40 MN/sq m and are presented in tabulated and graphical form. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, specific heat at constant pressure, specific heat at constant volume, isentropic exponent, and species mole fractions. These properties were calculated by the method which is based on minimization of the Gibbs free energy. The data presented herein are for an 18-species ammonia model. Heats of formation and spectroscopic constants used as input data are presented. Comparison of several thermodynamic properties calculated with the present program and a second computer code is performed for a range of pressure and for temperatures up to 30,000 K.
Acoustic and Thermodynamic Properties of the Binary Liquid Mixture n-Octane + n-Dodecane
NASA Astrophysics Data System (ADS)
Khasanshin, T. S.; Golubeva, N. V.; Samuilov, V. S.; Shchemelev, A. P.
2014-01-01
The velocity of sound in the binary liquid mixture n-octane + n-dodecane has been investigated by the method of direct measurement of the pulse-transmission time in the interval of temperatures 298-433 K and pressures 0.1-100.1 MPa. The maximum measurement error amounts to 0.1%. The density, isobaric expansion coefficient, isobaric and isochoric heat capacities, and isothermal compressibility of a mixture of three compositions have been determined in the intervals of temperatures 298-393 K and pressures 0.1-100 MPa from the data on the velocity of sound. Also, the excess molar volume, the excess isothermal compressibility, and the deviation of the velocity of sound from its value for an ideal liquid have been determined. The coefficients of the Tate equation have been computed in the above temperature interval. A table of thermodynamic properties of the mixture has been presented.
Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation
Feng, ShiQuan; Cheng, XinLu [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China) [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu, 610064 (China); Zhao, JianLing [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)] [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Zhang, Hong [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China)] [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China)
2013-07-28
In this paper, phonon spectra of InSb at different electronic temperatures are presented. Based on the phonon dispersion relationship, we further perform a theoretical investigation of the thermodynamic properties of InSb under intense laser irradiation. The phonon entropy, phonon heat capacity, and phonon contribution to Helmholtz free energy and internal energy of InSb are calculated as functions of temperature at different electronic temperatures. The abrupt change in the phonon entropy- temperature curve from T{sub e} = 0.75 to 1.0 eV provides an indication of InSb undergoing a phase transition from solid to liquid. It can be considered as a collateral evidence of non-thermal melting for InSb under intense electronic excitation effect.
Quantum phase transition and thermodynamic properties of a fourfold magnetic periodic system
NASA Astrophysics Data System (ADS)
Wang, Shuling; Li, Ruixue; Ding, Linjie; Fu, Hua-Hua; Zhu, Si-cong; Ni, Yun; Meng, Yan; Yao, Kailun
2014-12-01
Based on the experimental synthesis of organic compound verdazyl radical ?-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl, consisting of four antiferromagnetic couplings, we study the magnetic properties and thermodynamic behaviors for different antiferromagnetic interactions using Green’s function theory. Under different fields, there are five regimes containing two gapless phases and three magnetization plateaus (M=0, 1/2 and saturated magnetization) distinguished by four critical lines, which are evidenced by the two-site entanglement entropy and closely related to the energy spectra. In addition, we calculate the susceptibility and specific heat, to demonstrate the low-lying excitations at low temperatures. It will provide guidance for us to synthesize varieties of unconventional magnetic materials, and stimulate future studies on quantum spin systems.
Fast interpolation algorithm for the calculation of thermodynamic property maps of microstructures
NASA Astrophysics Data System (ADS)
Rettig, Ralf; Singer, Robert F.
2014-12-01
A fast method for the calculation of thermodynamic property mappings of alloy microstructures is presented. It uses surrogate interpolation models instead of the direct CALPHAD calculation of each data point. With the best algorithm, a speed-up of nearly 30 can be achieved compared to the direct method. If repeated calculations of similar microstructures are required, a speed-up of around 300 can even be realized. Different surrogate models have been evaluated. The universal kriging method gives the most accurate results, while polynomial surface response models turn out to generate larger interpolation errors. In order to minimize the number of calculation points of the surrogate interpolation model, the microstructure is classified into similar regions, in which the design points are chosen randomly. The algorithm is applicable independent of alloy composition. Within the paper, we present the application of the algorithm for two single-crystalline nickel-based superalloys.
Molecular-dynamic modeling of thermodynamic properties of the lunar Fe-S core
NASA Astrophysics Data System (ADS)
Belashchenko, D. K.; Kuskov, O. L.
2015-01-01
The physical properties (density, modules of compression, heat capacity, and velocity of the P-waves) of the lunar Fe-S core are modeled with molecular dynamics and the Embedded Atom Model potential at 0-18 at % S content, temperatures up to 2500 K, and pressures up to 5 GPa. The thermodynamic calculations of the velocity of P-waves in the liquid lunar core are consistent with the interpreted results of seismic processing of the Apollo observations. According to calculations, the density of the liquid core may vary from 7.4 (pure liquid iron) to 6.75 (10 at % S at 1950 ± 50 K) g/cm3. This approach provides more reliable restrictions for the inner structure of the Moon.
NASA Astrophysics Data System (ADS)
Suntsov, Yu. K.; Vlasov, M. V.; Chuikov, A. M.
2015-06-01
The boiling points of solutions of five binary systems are measured using the ebulliometric method in the pressure range of 4.4-101.3 kPa. Compositions of the equilibrium vapor phases of systems are calculated, based on the constructed pressure isotherms of saturated vapor. The values of excess Gibbs energy and the enthalpy and entropy of solutions are calculated from the data on the liquid-vapor equilibrium. The patterns of change in the phase equilibria and thermodynamic properties of the solutions are established, based on the composition and temperature of the systems. The liquid-vapor equilibrium of systems is described using the equations of Wilson and the NRTL (Non-Random Two-Liquid model).
Estimation of the Thermodynamic Limit of Overheating for Bulk Water from Interfacial Properties
NASA Astrophysics Data System (ADS)
Imre, A. R.; Baranyai, A.; Deiters, U. K.; Kiss, P. T.; Kraska, T.; Quiñones Cisneros, S. E.
2013-11-01
The limit of overheating or expanding is an important property of liquids, which is relevant for the design and safety assessment of processes involving pressurized liquids. In this work, the thermodynamic stability limit—the so-called spinodal—of water is calculated by molecular dynamics computer simulation, using the molecular potential model of Baranyai and Kiss. The spinodal pressure is obtained from the maximal tangential pressure within a liquid-vapor interface layer. The results are compared to predictions of various equations of state. Based on these comparisons, a set of equations of state is identified which gives reliable results in the metastable (overheated or expanded) liquid region of water down to MPa.
Some physical and thermodynamic properties of rocket exhaust clouds measured with infrared scanners
NASA Technical Reports Server (NTRS)
Gomberg, R. I.; Kantsios, A. G.; Rosensteel, F. J.
1977-01-01
Measurements using infrared scanners were made of the radiation from exhaust clouds from liquid- and solid-propellant rocket boosters. Field measurements from four launches were discussed. These measurements were intended to explore the physical and thermodynamic properties of these exhaust clouds during their formation and subsequent dispersion. Information was obtained concerning the initial cloud's buoyancy, the stabilized cloud's shape and trajectory, the cloud volume as a function of time, and it's initial and stabilized temperatures. Differences in radiation intensities at various wavelengths from ambient and stabilized exhaust clouds were investigated as a method of distinguishing between the two types of clouds. The infrared remote sensing method used can be used at night when visible range cameras are inadequate. Infrared scanning techniques developed in this project can be applied directly to natural clouds, clouds containing certain radionuclides, or clouds of industrial pollution.
Thermodynamic and Ultrasonic Properties of Ascorbic Acid in Aqueous Protic Ionic Liquid Solutions
Singh, Vickramjeet; Sharma, Gyanendra; Gardas, Ramesh L.
2015-01-01
In this work, we report the thermodynamic and ultrasonic properties of ascorbic acid (vitamin C) in water and in presence of newly synthesized ammonium based protic ionic liquid (diethylethanolammonium propionate) as a function of concentration and temperature. Apparent molar volume and apparent molar isentropic compression, which characterize the solvation state of ascorbic acid (AA) in presence of protic ionic liquid (PIL) has been determined from precise density and speed of sound measurements at temperatures (293.15 to 328.15) K with 5 K interval. The strength of molecular interactions prevailing in ternary solutions has been discussed on the basis of infinite dilution partial molar volume and partial molar isentropic compression, corresponding volume of transfer and interaction coefficients. Result has been discussed in terms of solute-solute and solute-solvent interactions occurring between ascorbic acid and PIL in ternary solutions (AA + water + PIL). PMID:26009887
NASA Technical Reports Server (NTRS)
Miller, C. G., III; Wilder, S. E.
1976-01-01
Equilibrium thermodynamic properties for pure carbon dioxide are presented in tabulated and graphical form for temperatures from 100 K to 25,000 K and pressures from 40 mN/sq m to 1 GN/sq m. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, specific heat at constant pressure, specific heat at constant volume, isentropic exponent, and species mole fractions.
Aurea R Vasconcellos; Roberto Luzzi; Justino R Madureira
2000-01-01
We present an analysis of the nonequilibrium thermodynamics and, mainly, a response function theory for the study of optical properties in ultrafast-spectroscopy pump-probe experiments. These experiments give rise to the formation of a photoinjected plasma in semiconductors in far-from-equilibrium conditions. The dissipative processes that evolve in this medium greatly influence optical and transport properties. The theory is centred on the
Structural, thermodynamic and optical properties of MgF{sub 2} studied from first-principles theory
Ramesh Babu, K. [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Andhra Pradesh, Hyderabad 500 046 (India); Bheema Lingam, Ch. [School of Physics, University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Andhra Pradesh, Hyderabad 500 046 (India); Auluck, S. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, Uttar Pradesh (India); Tewari, Surya P. [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Andhra Pradesh, Hyderabad 500 046 (India); School of Physics, University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Andhra Pradesh, Hyderabad 500 046 (India); Vaitheeswaran, G., E-mail: gvsp@uohyd.ernet.i [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Andhra Pradesh, Hyderabad 500 046 (India)
2011-02-15
A detailed theoretical study of structural, electronic, elastic, thermodynamic and optical properties of rutile type MgF{sub 2} has been carried out by means of first-principles Density Functional Theory (DFT) calculations using plane wave pseudo-potentials within the local density approximation and generalized-gradient approximation for the exchange and correlation functionals. The calculated ground state properties and elastic constants agree quite well with experimental values. From the calculated elastic constants we conclude that MgF{sub 2} is relatively hard when compared to other alkaline-earth fluorides and ductile in nature. The thermodynamic properties such as heat capacity, entropy, free energy, phonon density of states and Debye temperatures are calculated at various temperatures from the lattice dynamical data obtained through the quasi-harmonic Debye model. From free energy and entropy it is found that the system is thermodynamically stable up to 1200 K. The imaginary part of the calculated dielectric function {epsilon}{sub 2}({omega}) could reproduce the six prominent peaks which are observed in experiment. From the calculated {epsilon}({omega}), other optical properties such as refractive index, reflectivity and electron energy-loss spectrum are obtained up to the photon energy range of 30 eV. -- Graphical abstract: The calculated imaginary part {epsilon}{sub 2}({omega}) of the complex dielectric function {epsilon}({omega}) of MgF{sub 2} as a function of photon energy is shown. The calculated {epsilon}{sub 2}({omega}) could reproduce the major peaks observed in experiment. All the peaks observed are corresponds to interband transitions from 'p' states of Fluorine in valence band to the 's' states of Mg in conduction band. Display Omitted Research highlights: > Structural and bonding properties. > Optical properties. > Single and polycrystalline elastic properties. > Thermodynamic properties.
Donohue, M.D.
1992-11-01
The purpose of this research program is to understand and model the effect of the different intermolecular forces on the thermodynamic properties of systems containing pure compounds and mixtures. The compounds under consideration vary considerably in size, shape and energy. Therefore in order to develop a theory capable of describing accurately the thermodynamic properties and phase behavior of such systems over a wide range of temperature and pressure, one has to take into account explicitly the differences in shape and size among the various compounds as well as the different type of intermolecular interactions. We have developed equations of state for pure-component chain molecules. We have shown that the excellent performance of complicated theories such as the Generalized Flory Dimer (GFD) theory can be mimicked by simpler equations, if certain assumptions for the shape parameters are made. We developed engineering correlations based on the GFD theory, using local composition theory to take into account the attractive contribution. We compared various methods for the calculation of the repulsive and attractive contributions against computer simulation data for hard and square-well chains, and experimental data from the literature. We also have studied microstructure and local order in fluids that contain asymmetric molecules. In addition, simple cubic equations of state have been applied to calculate physical and chemical-reaction equilibria in non-ideal systems. In order to obtain a better understanding of the intermolecular forces and to test some of our recent models, we have performed considerable experimental work. We used FT-IR to examine the self-association of aliphatic alcohols due to hydrogen bonding. In addition, FT-IR spectroscopy was used to investigate Lewis acid-base interactions between probe and entrainer-cosolvent molecules.
Kabadi, V.N.
1995-06-30
The work on this project was initiated on September 1, 1991. The project consisted of two different tasks: (1) Development of a model to compute viscosities of coal derived liquids, and (2) Investigate new models for estimation of thermodynamic properties of solid and liquid compounds of the type that exist in coal, or are encountered during coal processing. As for task 1, a model for viscosity computation of coal model compound liquids and coal derived liquids has been developed. The detailed model is presented in this report. Two papers, the first describing the pure liquid model and the second one discussing the application to coal derived liquids, are expected to be published in Energy & Fuels shortly. Marginal progress is reported on task 2. Literature review for this work included compilation of a number of data sets, critical investigation of data measurement techniques available in the literature, investigation of models for liquid and solid phase thermodynamic computations. During the preliminary stages it was discovered that for development of a liquid or solid state equation of state, accurate predictive models for a number of saturation properties, such as, liquid and solid vapor pressures, saturated liquid and solid volumes, heat capacities of liquids and solids at saturation, etc. Most the remaining time on this task was spent in developing predictive correlations for vapor pressures and saturated liquid volumes of organic liquids in general and coal model liquids in particular. All these developments are discussed in this report. Some recommendations for future direction of research in this area are also listed.
High-Precision Thermodynamic and Critical Properties from Tensor Renormalization-Group Flows
NASA Astrophysics Data System (ADS)
Hinczewski, Michael; Berker, A. Nihat
2008-03-01
The recently developed tensor renormalization-group (TRG) method [1] provides a highly precise technique for deriving thermodynamic and critical properties of lattice Hamiltonians. The TRG is a local coarse-graining transformation, with the elements of the tensor at each lattice site playing the part of the interactions that undergo the renormalization-group flows. These tensor flows are directly related [2] to the phase diagram structure of the infinite system, with each phase flowing to a distinct surface of fixed points. Fixed-point analysis and summation along the flows give the critical exponents, as well as thermodynamic functions along the entire temperature range. Thus, for the ferromagnetic triangular lattice Ising model, the free energy is calculated to better than 10-5 along the entire temperature range. Unlike previous position-space renormalization-group methods, the truncation (of the tensor index range D) in this general method converges under straightforward and systematic improvements. Our best results are easily obtained with D=24, corresponding to 4624-dimensional renormalization-group flows. [1] M. Levin and C.P. Nave, Phys. Rev. Lett. 99, 120601 (2007). [2] M. Hinczewski and A.N. Berker, arXiv:0709.2803v1 [cond-mat.stat-mech], Phys. Rev. E, in press.
Paganini, Iván E; Pastorino, Claudio; Urrutia, Ignacio
2015-06-28
We study a system of few colloids confined in a small spherical cavity with event driven molecular dynamics simulations in the canonical ensemble. The colloidal particles interact through a short range square-well potential that takes into account the basic elements of attraction and excluded-volume repulsion of the interaction among colloids. We analyze the structural and thermodynamic properties of this few-body confined system in the framework of inhomogeneous fluids theory. Pair correlation function and density profile are used to determine the structure and the spatial characteristics of the system. Pressure on the walls, internal energy, and surface quantities such as surface tension and adsorption are also analyzed for a wide range of densities and temperatures. We have characterized systems from 2 to 6 confined particles, identifying distinctive qualitative behavior over the thermodynamic plane T - ?, in a few-particle equivalent to phase diagrams of macroscopic systems. Applying the extended law of corresponding states, the square well interaction is mapped to the Asakura-Oosawa model for colloid-polymer mixtures. We link explicitly the temperature of the confined square-well fluid to the equivalent packing fraction of polymers in the Asakura-Oosawa model. Using this approach, we study the confined system of few colloids in a colloid-polymer mixture. PMID:26133449
Structure, thermodynamic properties, and phase diagrams of few colloids confined in a spherical pore
Iván Paganini; Claudio Pastorino; Ignacio Urrutia
2015-04-09
We study a system of few colloids confined in a small spherical cavity by event driven molecular dynamics simulations in the canonical ensemble. The colloidal particles interact through a short range square-well potential, which takes into account the basic elements of attraction and excluded-volume repulsion of the interaction among colloids. We analyze the structural and thermodynamic properties of this few-body confined system in the framework of the theory of inhomogeneous fluids. Pair correlation functions and density profiles across the cavity are used to determine the structure of the system and the spatial characteristics of its inhomogeneities. Pressure on the walls, internal energy and surface quantities such as surface tension and adsorption are also analyzed for the whole range of densities, temperatures and number of particles considered. We have characterized the structure of systems from 2 to 6 confined particles as function of density and temperature, identifying the distinctive qualitative behaviors all over the thermodynamic plane $T-\\rho$ in a few-particle equivalence to phase diagrams of macroscopic systems. Applying the extended law of corresponding states the square well interaction is mapped to the Asakura-Oosawa model for colloid-polymer mixtures. We link explicitly the temperature in the confined square-well fluid to the equivalent packing fraction of polymers in the Asakura-Oosawa model. Using this approach we study the confined system of few colloids in a colloid-polymer mixture.
Atmospheric amines - Part II. Thermodynamic properties and gas/particle partitioning
NASA Astrophysics Data System (ADS)
Ge, Xinlei; Wexler, Anthony S.; Clegg, Simon L.
2011-01-01
Amines enter the atmosphere from a wide range of sources, but relatively little is known about their atmospheric behavior, especially their role in gas/particle partitioning. In Part I of this work ( Ge et al., 2011) a total of 154 amines, 32 amino acids and urea were identified as occurring in the atmosphere, based upon a survey of the literature. In this work we compile data for the thermodynamic properties of the amines which control gas/particle partitioning (Henry's Law constant, liquid vapor pressure, acid dissociation constant, activity coefficient and solubility in water), and also estimate the solid/gas dissociation constants of their nitrate and chloride salts. Prediction methods for boiling point, liquid vapor pressure, acid dissociation constant and the solubility of the amines in water are evaluated, and used to estimate values of the equilibrium constants where experimental data are lacking. Partitioning of amines into aqueous aerosols is strongly dependent upon pH and is greatest for acidic aerosols. For several common amines the tendency to partition to the particle phase is similar to or greater than that of ammonia. Our results are presented as tables of values of thermodynamic equilibrium constants, which are also incorporated into the Extended Aerosol Inorganics Model ( E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) to enable gas/aerosol partitioning and other calculations to be carried out.
Meneni, Srinivasa Rao; D'Mello, Rhijuta; Norigian, Gregory; Baker, Gregory; Gao, Lan; Chiarelli, M. Paul; Cho, Bongsup P.
2006-01-01
Circular dichroism (CD) and UV-melting experiments were conducted with 16 oligodeoxynucleotides modified by the carcinogen 2-aminofluorene, whose sequence around the lesion was varied systematically [d(CTTCTNG[AF]NCCTC), N = G, A, C, T], to gain insight into the factors that determine the equilibrium between base-displaced stacked (S) and external B-type (B) duplex conformers. Differing stabilities among the duplexes can be attributed to different populations of S and B conformers. The AF modification always resulted in sequence-dependent thermal (Tm) and thermodynamic (??G°) destabilization. The population of B-type conformers derived from eight selected duplexes (i.e. -AG*N- and -CG*N-) was inversely proportional to the ??G° and Tm values, which highlights the importance of carcinogen/base stacking in duplex stabilization even in the face of disrupted Watson–Crick base pairing in S-conformation. CD studies showed that the extent of the adduct-induced negative ellipticities in the 290–350 nm range is correlated linearly with ??G° and Tm, but inversely with the population of B-type conformations. Taken together, these results revealed a unique interplay between the extent of carcinogenic interaction with neighboring base pairs and the thermodynamic properties of the AF-modified duplexes. The sequence-dependent S/B heterogeneities have important implications in understanding how arylamine–DNA adducts are recognized in nucleotide excision repair. PMID:16449208
Quasi-harmonic approximation of thermodynamic properties of ice Ih, II, and III.
Ramírez, R; Neuerburg, N; Fernández-Serra, M-V; Herrero, C P
2012-07-28
Several thermodynamic properties of ice Ih, II, and III are studied by a quasi-harmonic approximation and compared to results of quantum path integral and classical simulations. This approximation allows to obtain thermodynamic information at a fraction of the computational cost of standard simulation methods, and at the same time permits studying quantum effects related to zero-point vibrations of the atoms. Specifically, we have studied the crystal volume, bulk modulus, kinetic energy, enthalpy, and heat capacity of the three ice phases as a function of temperature and pressure. The flexible q-TIP4P/F model of water was employed for this study, although the results concerning the capability of the quasi-harmonic approximation are expected to be valid independently of the employed water model. The quasi-harmonic approximation reproduces with reasonable accuracy the results of quantum and classical simulations showing an improved agreement at low temperatures (T< 100 K). This agreement does not deteriorate as a function of pressure as long as it is not too close to the limit of mechanical stability of the ice phases. PMID:22852626
Quasi-harmonic approximation of thermodynamic properties of ice Ih, II, and III
NASA Astrophysics Data System (ADS)
Ramírez, R.; Neuerburg, N.; Fernández-Serra, M.-V.; Herrero, C. P.
2012-07-01
Several thermodynamic properties of ice Ih, II, and III are studied by a quasi-harmonic approximation and compared to results of quantum path integral and classical simulations. This approximation allows to obtain thermodynamic information at a fraction of the computational cost of standard simulation methods, and at the same time permits studying quantum effects related to zero-point vibrations of the atoms. Specifically, we have studied the crystal volume, bulk modulus, kinetic energy, enthalpy, and heat capacity of the three ice phases as a function of temperature and pressure. The flexible q-TIP4P/F model of water was employed for this study, although the results concerning the capability of the quasi-harmonic approximation are expected to be valid independently of the employed water model. The quasi-harmonic approximation reproduces with reasonable accuracy the results of quantum and classical simulations showing an improved agreement at low temperatures (T< 100 K). This agreement does not deteriorate as a function of pressure as long as it is not too close to the limit of mechanical stability of the ice phases.
NASA Astrophysics Data System (ADS)
Boukheddaden, Kamel; Nishino, Masamichi; Miyashita, Seiji; Varret, François
2005-07-01
After the discovery of the phenomena of light-induced excited spin-state trapping (LIESST), the functional properties of metal complexes have been studied intensively. Among them, cooperative phenomena involving low spin-high spin (spin-crossover) transition and magnetic ordering have attracted interests, and it has become necessary to formulate a unified description of both phenomena. In this work, we propose a model in which they can be treated simultaneously by extending the Wajnflasz-Pick model to include a magnetic interaction. We found that this model is equivalent to Blume-Emery-Griffiths (BEG) Hamiltonian with degenerate levels. It provides a unified description of the thermodynamic properties associated with various types of systems, such as spin-crossover (SC) solids and Prussian blue analog. Here, the high spin fraction and the magnetization are the order parameters describing the cooperative phenomena of the model. We present several typical temperature dependences of the order parameters and determine the phase diagram of the system using the mean-field theory and Monte Carlo simulations. We found that the magnetic interaction drives the SC transition leading to reentrant magnetic and first-order SC transitions.
Structural and thermodynamic properties of Fe{sub 1.12}Te with multiple phase transitions
Cherian, Dona, E-mail: donacherian@physics.iisc.ernet.in; Elizabeth, Suja [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Rößler, S.; Koz, C.; Schwarz, U.; Wirth, S. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Tsirlin, A. A. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia)
2014-03-28
The parent compound of iron chalcogenide superconductors, Fe{sub 1+y}Te, with a range of excess Fe concentrations exhibits intriguing structural and magnetic properties. Here, the interplay of magnetic and structural properties of Fe{sub 1.12}Te single crystals have been probed by low-temperature synchrotron X-ray powder diffraction, magnetization, and specific heat measurements. Thermodynamic measurements reveal two distinct phase transitions, considered unique to samples possessing excess Fe content in the range of 0.11?y?0.13. On cooling, an antiferromagnetic transition, T{sub N}?57?K is observed. A closer examination of powder diffraction data suggests that the transition at T{sub N} is not purely magnetic, but accompanied by the commencement of a structural phase transition from tetragonal to orthorhombic symmetry. This is followed by a second prominent first-order structural transition at T{sub S} with T{sub S}
First principle study of elastic and thermodynamic properties of FeB4 under high pressure
NASA Astrophysics Data System (ADS)
Zhang, Xinyu; Qin, Jiaqian; Ning, Jinliang; Sun, Xiaowei; Li, Xinting; Ma, Mingzhen; Liu, Riping
2013-11-01
The elastic properties, elastic anisotropy, and thermodynamic properties of the lately synthesized orthorhombic FeB4 at high pressures are investigated using first-principles density functional calculations. The calculated equilibrium parameters are in good agreement with the available experimental and theoretical data. The obtained normalized volume dependence of high pressure is consistent with the previous experimental data investigated using high-pressure synchrotron x-ray diffraction. The complete elastic tensors and crystal anisotropies of the FeB4 are also determined in the pressure range of 0-100 GPa. By the elastic stability criteria and vibrational frequencies, it is predicted that the orthorhombic FeB4 is stable up to 100 GPa. In addition, the calculated B/G ratio reveals that FeB4 possesses brittle nature in the range of pressure from 0 to 100 GPa. The calculated elastic anisotropic factors suggest that FeB4 is elastically anisotropic. By using quasi-harmonic Debye model, the compressibility, bulk modulus, the coefficient of thermal expansion, the heat capacity, and the Grüneisen parameter of FeB4 are successfully obtained in the present work.
Why thermodynamic properties of normal and heavy water are similar to those of argon-like liquids?
Sergey V. Lishchuk; Nikolay P. Malomuzh; Pavel V. Makhlaichuk
2010-01-01
The Letter is devoted to the explanation of the argon-like behavior of the thermodynamic properties of water. It is shown that this phenomenon is caused by the averaged inter-particle potentials which form due to rotation of water molecules. The general structure of the averaged potentials is proposed. The physical nature for the considerable shift of the triple point of water
Berry, R. Stephen
Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy Available online 25 November 2011 Keywords: Clusters Interaction potentials Range of interactions Topography for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures
E. J. Moon; J. E. Yoo; H. W. Choi; C. K. Kim
2002-01-01
Gas transport and thermodynamic properties of polymethylmethacrylate (PMMA) blended with polyvinylmethylether (PVME) containing diblock copolymer of styrene and methylmethacrylate (PS-b-PMMA) as a compatibilizer were studied. Phase separation temperatures of PVME blends with styrenic random copolymer containing various amounts of methyl methacrylate (MMA) were determined to calculate the interaction energies of the binary pairs involved in this system using lattice fluid
Konings, Rudy J. M., E-mail: rudy.konings@ec.europa.eu; Beneš, Ondrej; Kovács, Attila; Manara, Dario; Sedmidubský, David [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Gorokhov, Lev; Iorish, Vladimir S.; Yungman, Vladimir; Shenyavskaya, E.; Osina, E. [Joint Institute for High Temperatures, Russian Academy of Sciences, 13-2 Izhorskaya Street, Moscow 125412 (Russian Federation)
2014-03-15
A comprehensive review of the thermodynamic properties of the oxide compounds of the lanthanide and actinide elements is presented. The available literature data for the solid, liquid, and gaseous state have been analysed and recommended values are presented. In case experimental data are missing, estimates have been made based on the trends in the two series, which are extensively discussed.
Alfè, Dario
Ab initio calculation of lattice dynamics and thermodynamic properties of beryllium Fen Luo, Ling: Application to free energy calculations in alloys J. Chem. Phys. 135, 044127 (2011) Particle-based multiscale calculation of lattice dynamics and thermodynamic properties of beryllium Fen Luo,1,2 Ling-Cang Cai,1,a) Xiang
Molecular simulation of thermodynamic and transport properties for the H2O+NaCl system
NASA Astrophysics Data System (ADS)
Orozco, Gustavo A.; Moultos, Othonas A.; Jiang, Hao; Economou, Ioannis G.; Panagiotopoulos, Athanassios Z.
2014-12-01
Molecular dynamics and Monte Carlo simulations have been carried out to obtain thermodynamic and transport properties of the binary mixture H2O+NaCl at temperatures from T = 298 to 473 K. In particular, vapor pressures, liquid densities, viscosities, and vapor-liquid interfacial tensions have been obtained as functions of pressure and salt concentration. Several previously proposed fixed-point-charge models that include either Lennard-Jones (LJ) 12-6 or exponential-6 (Exp6) functional forms to describe non-Coulombic interactions were studied. In particular, for water we used the SPC and SPC/E (LJ) models in their rigid forms, a semiflexible version of the SPC/E (LJ) model, and the Errington-Panagiotopoulos Exp6 model; for NaCl, we used the Smith-Dang and Joung-Cheatham (LJ) parameterizations as well as the Tosi-Fumi (Exp6) model. While none of the model combinations are able to reproduce simultaneously all target properties, vapor pressures are well represented using the SPC plus Joung-Cheathem model combination, and all LJ models do well for the liquid density, with the semiflexible SPC/E plus Joung-Cheatham combination being the most accurate. For viscosities, the combination of rigid SPC/E plus Smith-Dang is the best alternative. For interfacial tensions, the combination of the semiflexible SPC/E plus Smith-Dang or Joung-Cheatham gives the best results. Inclusion of water flexibility improves the mixture densities and interfacial tensions, at the cost of larger deviations for the vapor pressures and viscosities. The Exp6 water plus Tosi-Fumi salt model combination was found to perform poorly for most of the properties of interest, in particular being unable to describe the experimental trend for the vapor pressure as a function of salt concentration.
NASA Astrophysics Data System (ADS)
Ionova, Galina V.
2002-05-01
Experimental and theoretical data on the structures and properties of compounds of tetravalent transactinides (TAnIV) Rf (Z = 104), Db (Z = 105), Sg (Z = 106), Bh (Z = 107), Hs (Z = 108), Mt (Z = 109), and 110TAn (Z = 110) are described systematically. The problem of disposition of the transactinide elements in the Periodic system is discussed and the properties of the 6d-, 5d-, 4d-, 3d- and 5f-elements are compared. Regularities of changes in the thermodynamic characteristics of TAnIV compounds versus the atomic number, Z(TAn), are elucidated. Peculiarities of changes in thermodynamic properties upon the formation of nitrate, fluoride and chloride TAnIV complexes in solution are discussed. The bibliography includes 140 references.
Gorman-Lewis, Drew; Shareva, Tatiana; kubatko, Karrie-Ann; burns, Peter; Wellman, Dawn M.; McNamara, Bruce K.; szymanowski, jennifer; Navrotsky, Alexandra; Fein, Jeremy B.
2009-10-01
In this study, we use solubility and oxide melt solution calorimetry measurements to determine the thermodynamic properties of the uranyl phosphate phases autunite (abbreviated: CaUP), uranyl hydrogen phosphate (HUP), and uranyl orthophosphate (UP). Solubility measurements from both supersaturated and undersaturated conditions, as well as under different pH conditions, rigorously demonstrate attainment of equilibrium and yield well-constrained solubility product values of -48.36 (-0.03 /+ 0.03), -13.17 (-0.11 / +0.07), and -49.36 (-0.04 / +0.02) for CaUP, HUP, and UP, respectively. We use the solubility data to calculate standard state Gibbs free energies of formation for all phases (-7630.61 ± 9.69, -3072.27 ± 4.76, and -6138.95 ± 12.24 kJ mol-1 for CaUP, HUP, and UP, respectively), and calorimetry data to calculate standard state enthalpies of formation of -3223.22 ± 4.00 and -7001.01 ± 15.10 kJ mol-1 for HUP and UP, respectively. Combining these results allows us also to calculate the standard state entropies of formation of -506.54 ± 10.48 and -2893.12 ± 19.44 kJ mol-1 K-1 for HUP and UP phases, respectively. The results from this study are part of a combined effort to develop reliable and internally consistent thermodynamic data for environmentally relevant uranyl minerals. Data such as these are required in order to optimize and quantitatively assess the effect of phosphate amendment remediation technologies for uranium contaminated systems.
Thermodynamic properties and phase transtions in the H2O/CO2/CH4 system.
Svandal, Atle; Kuznetsova, Tatyana; Kvamme, Bjørn
2006-04-14
The availability of free energy densities as functions of temperature, pressure and the composition of all components is required for the development of a three-component phase field theory for hydrate phase transitions. We have broadened the extended adsorption theory due to Kvamme and Tanaka (J. Phys. Chem., 1995, 99, 7114) through derivation of the free energy density surface in case of CO(2) and CH(4) hydrates. A combined free energy surface for the liquid phases has been obtained from a SRK equation of state and solubility measurements outside hydrate stability. The full thermodynamic model is shown to predict water-hydrate equilibrium properties in agreement with experiments. Molecular dynamics simulations of hydrates in contact with water at 200 bar and various temperatures allowed us to estimate hard-to-establish properties needed as input parameters for the practical applications of proposed theories. The 5-95 confidence interval for the interface thickness for the methane hydrate/liquid water is estimated to 8.54 A. With the additional information on the interface free energy, the phase field theory will contain no adjustable parameters. We provide a demonstration of how this theory can be applied to model the kinetics of hydrate phase transitions. The growth of hydrate from aqueous solution was found to be rate limited by mass transport, with the concentration of solute close to the hydrate approaching the value characterizing the equilibrium between the hydrate and the aqueous solution. The depth of the interface was estimated by means of the phase field analysis; its value is close to the interface thickness yielded by molecular simulations. The variation range of the concentration field was estimated to approximately 1/3 of the range of the phase field. PMID:16633655
Influence of Alloying Elements on the Thermodynamic Properties of Titanium in Molten Steel
NASA Astrophysics Data System (ADS)
Yoshikawa, Takeshi; Morita, Kazuki
2007-08-01
The influences of alloying elements of chromium, nickel, manganese, molybdenum, copper, and oxygen on the thermodynamic property of titanium in molten iron were investigated at 1873 K to improve control of the formation of titanium compounds in the steelmaking processes. At a certain titanium potential controlled by the coexistence of Ti3O5 and Ti2O3 with steel, the interaction parameters between alloying elements and titanium in molten iron were determined as follows. \\varepsilon ^{{{text{Mn}}}}_{{{text{Ti}}}} = - 27.4( ± 0.66),quad \\varepsilon ^{{{text{Cr}}}}_{{{text{Ti}}}} = 5.33( ± 0.84),quad \\varepsilon ^{{{text{Ni}}}}_{{{text{Ti}}}} = - 3.93( ± 0.51),quad \\varepsilon ^{{{text{Mo}}}}_{{{text{Ti}}}} = 5.76( ± 0.69),quad \\varepsilon ^{{{text{Cu}}}}_{{{text{Ti}}}} = 3.44( ± 0.69) Through the investigation of titanium deoxidation equilibria in molten iron, the activity coefficient of titanium and the first-order interaction parameter between oxygen and titanium were determined as follows: ? _{{{text{Ti}}}}^{ circ} = 0.0215(±0.00062),quad \\varepsilon ^{{{text{Ti}}}}_{{text{O}}} = - 160(±10) Also, titanium deoxidation of molten 304 stainless steel was measured and compared with the calculated results using the determined interaction parameters.
Ab initio calculation of thermodynamic, transport, and optical properties of CH2 plastics
NASA Astrophysics Data System (ADS)
Knyazev, D. V.; Levashov, P. R.
2015-05-01
This work covers an ab initio calculation of thermodynamic, transport, and optical properties of plastics of the effective composition CH2 at density 0.954 g/cm3 in the temperature range from 5 kK up to 100 kK. The calculation is based on the quantum molecular dynamics, density functional theory, and the Kubo-Greenwood formula. The temperature dependence of the static electrical conductivity ?1DC(T) has a step-like shape: ?1DC(T ) grows rapidly for 5 kK ? T ? 10 kK and is almost constant for 20 kK ? T ? 60 kK. The additional analysis based on the investigation of the electron density of states (DOS) is performed. The rapid growth of ?1DC(T ) at 5 kK ? T ? 10 kK is connected with the increase of DOS at the electron energy equal to the chemical potential ? = ?. The frequency dependence of the dynamic electrical conductivity ?1(?) at 5 kK has the distinct non-Drude shape with the peak at ? ? 10 eV. This behavior of ?1(?) was explained by the dip at the electron DOS.
Ionic melts with waterlike anomalies: thermodynamic properties of liquid BeF2.
Agarwal, Manish; Sharma, Ruchi; Chakravarty, Charusita
2007-10-28
Thermodynamic properties of liquid beryllium difluoride (BeF(2)) are studied using canonical ensemble molecular dynamics simulations of the transferable rigid ion model potential. The negative slope of the locus of points of maximum density in the temperature-pressure plane is mapped out. The excess entropy, computed within the pair correlation approximation, is found to show an anomalous increase with isothermal compression at low temperatures which will lead to diffusional as well as structural anomalies resembling those in water. The anomalous behavior of the entropy is largely connected with the behavior of the Be-F pair correlation function. The internal energy shows a T(35) temperature dependence. The pair correlation entropy shows a T(-25) temperature dependence only at high densities and temperatures. The correlation plots between internal energy and the pair correlation entropy for isothermal compression show the characteristic features expected of network-forming liquids with waterlike anomalies. The tagged particle potential energy distributions are shown to have a multimodal form at low temperatures and densities similar to those seen in other liquids with three-dimensional tetrahedral networks, such as water and silica. PMID:17979355
Ionic melts with waterlike anomalies: Thermodynamic properties of liquid BeF2
NASA Astrophysics Data System (ADS)
Agarwal, Manish; Sharma, Ruchi; Chakravarty, Charusita
2007-10-01
Thermodynamic properties of liquid beryllium difluoride (BeF2) are studied using canonical ensemble molecular dynamics simulations of the transferable rigid ion model potential. The negative slope of the locus of points of maximum density in the temperature-pressure plane is mapped out. The excess entropy, computed within the pair correlation approximation, is found to show an anomalous increase with isothermal compression at low temperatures which will lead to diffusional as well as structural anomalies resembling those in water. The anomalous behavior of the entropy is largely connected with the behavior of the Be-F pair correlation function. The internal energy shows a T3/5 temperature dependence. The pair correlation entropy shows a T-2/5 temperature dependence only at high densities and temperatures. The correlation plots between internal energy and the pair correlation entropy for isothermal compression show the characteristic features expected of network-forming liquids with waterlike anomalies. The tagged particle potential energy distributions are shown to have a multimodal form at low temperatures and densities similar to those seen in other liquids with three-dimensional tetrahedral networks, such as water and silica.
Wen-Sheng Xu; Karl F. Freed
2015-06-26
The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction $\\phi$ or temperature $T$ is high, but opposes self-assembly when both $\\phi$ and $T$ are sufficiently low. This allows us to identify a boundary line in the $\\phi$-$T$ plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.
Kaya, Ismet; Pala, Cigdem Yigit
2014-07-01
In this work, some thermodynamic properties of poly (cyclohexyl methacrylate) were studied by inverse gas chromatography (IGC). For this purpose, the polymeric substance was coated on Chromosorb W and which was filled into a glass column. The retention times (t(r)) of the probes were determined from the interactions of poly (cyclohexyl methacrylate) with n-pentane, n-hexane, n-heptane, n-octane, n-decane, methanol, ethanol, 2-propanol, butanol, acetone, ethyl methyl ketone, benzene, toluene and o-xylene by IGC technique. Then, the specific volume (Vg(0)) was determined for each probe molecule. By using (1/T; lnVg(0)) graphics, the glass transition temperature of poly (cyclohexyl methacrylate) was found to be 373 K. The adsorption heat under the glass transition temperature (deltaH(a)), and partial molar heat of sorption above the glass transition (deltaH1(S)), partial molar free energy of sorption (deltaG1(S)) and partial molar entropy of sorption (deltaS1(S)) belonging to sorption for every probe were calculated. The partial molar heat of mixing at infinite dilution (deltaH1(infinity)), partial molar free energy of mixing at infinite dilution (deltaG1(infinity)), Flory-Huggins interaction parameter (chi12(infinity)) and weight fraction activity coefficient (a1/w1)(infinity) values of polymer-solute systems were calculated at different column temperatures. The solubility parameters (delta2) of the polymer were obtained by IGC technique. PMID:25255568
Thermodynamic Properties of He Gas in the Temperature Range 4.2-10 K
NASA Astrophysics Data System (ADS)
Mosameh, S. M.; Sandouqa, A. S.; Ghassib, H. B.; Joudeh, B. R.
2014-05-01
The thermodynamic properties of He gas are investigated in the temperature-range 4.2-10 K, with special emphasis on the second virial coefficient in both the classical and quantum regimes. The main input in computing the quantum coefficient is the `effective' phase shifts. These are calculated within the framework of the Galitskii-Migdal-Feynman (GMF) formalism, using the HFDHE2 and Sposito potentials. The virial equation of state is constructed. Extensive calculations are carried out for the pressure-volume-temperature (P-V-T) behavior, as well as chemical potential, and nonideality of the system. The following results are obtained. First, the validity of the GMF formalism for the present system is demonstrated beyond any doubt. Second, the boiling point (phase-transition point) of He gas is determined from the P-V behavior using the virial equation of state, its value being closest than all previous results to the experimental value. Third, the chemical potential is evaluated from the quantum second virial coefficient. It is found that increases (becomes less negative) as the temperature decreases or the number density n increases. Further, shows no sensitivity to the differences between the potentials used up to n = 10 m. Finally, the compressibility Z is computed and discussed as a measure of the nonideality of the system.
Xu, Wen-Sheng; Freed, Karl F
2015-07-14
The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ? or temperature T is high, but opposes self-assembly when both ? and T are sufficiently low. This allows us to identify a boundary line in the ?-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts. PMID:26178122
Nichols, T.T.; Taylor, D.D.
2002-07-18
A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.
Galliero, Guillaume; Boned, Christian
2008-08-21
In this work, using extensive molecular dynamics simulations of several thermophysical properties, it is proposed to analyze possible relationships (in the corresponding state sense) between monoatomic fluids for which the repulsive interactions are modeled by an inverse n-power form, the Lennard-Jones 12-6 (LJ), or by an exponential one, the exponential-6 (Exp-6). To compare results between them, two possible definitions of Exp-6 potentials "equivalent" to the LJ one are proposed. In pure fluids, for a large range of thermodynamic conditions, the properties computed are the surface tension, liquid/vapor equilibrium densities, one-phase potential energy, pressure, isometric heat capacity, thermal pressure coefficient, self-diffusion, shear viscosity, and thermal conductivity. Additionally, thermodiffusion (Soret effect) has been considered in "isotopic" equimolar mixtures. It is shown that despite similarities exhibited by alike radial distribution functions, differences exist between the thermodynamic properties values provided by the LJ fluid and the two equivalent Exp-6 fluids. Nevertheless, quite surprisingly, when temperature and density are used as inputs, all three direct transport properties are shown to be nearly independent of the choice of the potential tested. Unexpectedly, these similarities hold even for thermodiffusion which is a priori very sensitive to the nature of the interactions. These results indicate that the use of an Exp-6 potential form to describe nonbonded/nonpolar interaction in molecular simulation is an alternative (more physically acceptable) to the LJ potential when dealing simultaneously with thermodynamic and transport properties. However, when only transport properties are considered (including thermodiffusion), the Exp-6 potential form should not lead to any differences compared to the LJ one. PMID:19044782
National Institute of Standards and Technology Data Gateway
SRD 10 NIST/ASME Steam Properties Database (PC database for purchase) Based upon the International Association for the Properties of Water and Steam (IAPWS) 1995 formulation for the thermodynamic properties of water and the most recent IAPWS formulations for transport and other properties, this updated version provides water properties over a wide range of conditions according to the accepted international standards.
Thermodynamic Properties of SPIN-1/2 Ising-Like Heisenberg Model on Triangle-Based Lattices
NASA Astrophysics Data System (ADS)
Isoda, Makoto; Nakano, Hiroki; Sakai, Tôru
Thermodynamic properties, specific heat and magnetic susceptibility, of spin-1/2 Ising-like Heisenberg model are investigated by an exact diagonalization method for small finite size kagome- and triangular-lattices up to 18-spins. The enhancement of magnetic susceptibility from the Curie-Weiss law and the peaks-structure of specific heat, rather generally detected experimentally in triangle-based spin systems including herbertsmithite, are interpreted as an intrinsic property of triangle-based frustrated spin systems with some extent of exchange anisotropy and are inferred as owing to a quantum-classical crossover.
Thermodynamic properties of CexTh1-xO2 solid solution from first-principles calculations
Xiao, Haiyan [University of Tennessee, Knoxville (UTK); Zhang, Yanwen [ORNL; Weber, William J [ORNL
2013-01-01
A systematic study based on first-principles calculations along with the quasi-harmonic approximation has been conducted to calculate the thermodynamic properties of the CexTh1-xO2 solid solution. The predicted density, thermal expansion coefficients, heat capacity and thermal conductivity for the CexTh1-xO2 solid solution all agree well with available experimental data. The thermal expansion coefficient for ThO2 increases with CeO2 substitution, and complete substitution shows the highest expansion coefficient. On the other hand, the mixed CexTh1-xO2 (0
Thermodynamic properties of CexTh1-xO2 solid solution from first-principles calculations
Xiao, Haiyan Y.; Zhang, Yanwen; Weber, William J.
2012-11-02
A systematic study based on first-principles calculations along with a quasi-harmonic approximation has been conducted to calculate the thermodynamic properties of the CexTh1xO2 solid solution. The predicted density, thermal expansion coefficients, heat capacity and thermal conductivity for the CexTh1xO2 solid solution all agree well with the available experimental data. The thermal expansion coefficient for ThO2 increases with CeO2 substitution, and complete substitution shows the highest expansion coefficient. On the other hand, the mixed CexTh1xO2 (0 < x < 1) solid solution generally exhibits lower heat capacity and thermal conductivity than the ThO2 and CeO2 end members. Our calculations indicate a strong effect of Ce concentration on the thermodynamic properties of the CexTh1xO2 solid solution.
M. Brühwiler; S. M. Kazakov; J. Karpinski; B. Batlogg
2005-01-01
We develop a general procedure for the analysis of bulk thermodynamic data of a superconductor for samples containing a metallic nonsuperconducting second phase. The method is based on the condensation energy and it allows the extraction of the intrinsic properties of a superconductor even for nonideal samples. Applying this procedure to the recently discovered geometrically frustrated beta -pyrochlore superconductor RbOs2O6
Richard T. Scalettar; Warren E. Pickett
2004-01-01
This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal
NASA Technical Reports Server (NTRS)
Gordon, S.
1982-01-01
The equilibrium compositions that correspond to the thermodynamic and transport combustion properties for a wide range of conditions for the reaction of hydrocarbons with air are presented. Initially 55 gaseous species and 3 coin condensed species were considered in the calculations. Only 17 of these 55 gaseous species had equilibrium mole fractions greater than 0.000005 for any of the conditions studied and therefore these were the only ones retained in the final tables.
J. E. Garcés; G. B. Grad; A. Fernández Guillermet; S. J. Sferco
1999-01-01
Using the full potential-linearised-muffin-tin-orbitals (FP-LMTO) method, we have studied the structural properties and the thermodynamic stability of the AlB2 (C32) type-structure, so-called omega (?) phase, of Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd and Ag. The equilibrium volume, lattice parameters, interatomic distances, and density-of-electron-states at the Fermi level of the stable or metastable ? phase of these elements are
Zhao-Chun Zhang; Jing-Kang Guo
2002-01-01
The non-random two-liquid equation has been applied to evaluate the thermodynamic properties of the liquid solution at elevated temperatures in a binary alloy system with a liquid phase miscibility gap. Only upon making use of the phase equilibrium data at the critical and monotectic points of the miscibility gap from a T-X phase diagram and thermochemical data, the parameters needed
Souraya Goumri-Said; Mohammed Benali Kanoun; Abdelkarim E Merad; Ghouti Merad; Hafid Aourag
2004-01-01
A three-body potential coupled with a molecular-dynamics method is used to calculate structural and thermodynamic properties of the hypothetical IV–IV compound SiGe in zinc-blende phase. A good agreement between the calculated and theoretical values of the lattice constant, the bulk modulus and its derivative, and the cohesive energy is obtained. We also compute the elastic constants, Debye temperature, lattice thermal
Aleksandr Vasserman C; Valentine Malchevsky S
Mixtures of refrigerants are widely used as working substances for refrigerating plants. Among them, mixtures of ozone-safe and natural refrigerants, in particular R23\\/R744 and R41\\/R744, are important. For calculating their thermodynamic properties, we compiled equations of state on the basis of the method in (1). According to this reference, the equation of state for a mixture is presented as a
Venkatarangan, Lata; Sivaprasad, A.; Johnson, Francis; Basu, Ashis K.
2001-01-01
2-Nitropropane (2-NP), an important industrial solvent and a component of cigarette smoke, is mutagenic in bacteria and carcinogenic in rats. 8-Amino-2?-deoxyguanosine (8-amino-dG) is one of the types of DNA damage found in liver, the target organ in 2-NP-treated rats. To investigate the thermodynamic properties of 8-amino-dG opposite each of the four DNA bases, we have synthesized an 11mer, d(CCATCG*CTACC), in which G* represents the modified base. By annealing a complementary DNA strand to this modified 11mer, four sets of duplexes were generated each containing one of the four DNA bases opposite the lesion. Circular dichroism studies indicated that 8-amino-dG did not alter the global helical properties of natural right-handed B-DNA. The thermal stability of each duplex was examined by UV melting measurements and compared with its unmodified counterpart. For the unmodified 11mer, the relative stability of the complementary DNA bases opposite G was in the order C > T > G > A, as determined from their –?G° values. The free energy change of each modified duplex was lower than its unmodified counterpart, except for the G*:G pair that exhibited a higher melting transition and a larger –?G° than the G:G duplex. Nevertheless, the stability of the modified 11mer duplex also followed the order C > T > G > A when placed opposite 8-amino-dG. To explore if 8-amino-dG opposite another 8-amino-dG has any advantage in base pairing, a G*:G* duplex was evaluated, which showed that the stability of this duplex was similar to the G*:G duplex. Mutagenesis of 8-amino-dG in this sequence context was studied in Escherichia coli, which showed that the lesion is weakly mutagenic (mutation frequency ?10–3) but still can induce a variety of targeted and semi-targeted mutations. PMID:11266546
EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL
Ramanathan Sampath
2000-01-01
This final technical report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period September 24, 1996 to September 23, 1999 which covers the entire performance period of the project. During this period, modification, alignment, and calibration of the measurement system, measurement of devolatilization time-scales for single coal particles subjected to a range of heating rates and temperature data at these time-scales, and analysis of the temperature data to understand the effect of heating rates on coal thermal properties were carried out. A new thermodynamic model was developed to predict the heat transfer behavior for single coal particles using one approach based on the analogy for thermal property of polymers. Results of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 5} K/s. At these heating rates during the early stages of heating, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatilization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are a few data available in the coal literature for low heating rate experiments (10{sup 2}-10{sup 3} K/s) conducted by UTRC, our industrial partner, in this project. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time of the single particle experiments discussed above. The polymer analogy model was modified to include longer heating time on the order of several seconds to test these data. However, the model failed to predict these low heating rate data. It should be noted that UTRC's work showed reasonably good agreement with Merrick model heat capacity predictions at these low heating rates, but at higher heating rates UTRC observed that coal thermal response was heat flux dependent. It is concluded that at combustion level heating rates (10{sup 4}-10{sup 5} K/s) coal structural changes are delayed and attendant increases in heat capacity and thermal conductivity are pushed to higher temperatures or require significant hold times to become manifest.
NASA Astrophysics Data System (ADS)
Geiger, C. A.; Dachs, E.
2012-04-01
The garnet class of phases is extremely broad in terms of composition and structural properties. Garnet is found in nature and various synthetic garnet phases have a number of important technical applications. There exist the rock-forming silicate garnets that are so widespread geologically. An additional class is given by the so-called "hydrogarnets" in which the tetrahedral site (Wyckoff position 24d) is empty. At relatively low temperatures there is complete solid solution between Ca3Al2Si3O12 and Ca3Al2H12O12, for example. The substitution mechanism can be written as O4H4 \\lrarr SiO4. The latter, pure OH-containing end-member, which has not been found in nature, is termed katoite/hydrogrossular. Its structure has been investigated by various workers by X-ray and neutron diffraction and by proton NMR, IR and Raman spectroscopic methods. At ambient conditions the structure has the "standard" garnet cubic symmetry of Ia-3d. At high pressures, and possibly at low temperatures, a different structure may occur. We measured the low temperature IR spectra and heat capacity of katoite in order to understand its structural, crystal-chemical and thermophysical properties. A sample of Ca3Al2H12O12 was synthesized hydrothermally in Au capsules at 250 °C and 3 kb water pressure. X-ray powder measurements show that about 98-99% katoite was obtained. Powder IR spectra were recorded between 298 K and 10 K. The measured spectra are considerably different in the high wavenumber region, where O-H stretching modes occur, between 298 K and 10 K. At room temperature the IR-active O-H band located around 3662 cm-1 is broad and it narrows and shifts to higher wavenumbers and also develops structure below about 80 K. Concomitantly, additional weak intensity O-H bands located around 3600 cm-1 begin to appear and they become sharper and increase in intensity with further decreases in temperature down to 10 K. The spectra indicate that the vibrational behavior of individual OH groups and their collective interactions measurably affect the lattice dynamic (i.e. thermodynamic) behavior. The low temperature heat capacity behavior was investigated with a commercially designed relaxation calorimeter between 5 and 300 K on a mg-sized sample. The heat capacity data are well behaved at T < 300 K and show a monotonic decrease in magnitude with decreasing temperature. A standard third-law entropy value of So = 421.7 ± 1.6 J/mol·K was calculated. Using this new calorimetric-based So value and published standard enthalpy of formation data for katoite, a calorimetric-based Gibbs free energy of formation at 298 K can be obtained as ?G°f = -5021.2 kJ/mol. The Cp data show no evidence for any phase transition as possibly expected by the change in OH-mode behavior with decreasing temperature. We have no explanation for the appearance of the additional modes. It is worth noting that the katoite crystal structure in terms of lattice dynamic or thermodynamic behavior should be thought of having OH groups and not O4H4 clusters or polyhedral units as is often written in the literature. The single crystallographic OH group in katoite shows very weak, if any, hydrogen bonding and the H atoms have large amplitudes of vibration. The weak H bonding controls the nature of low energy OH-related vibrations and this leads to its large So value.
Tei, Lorenzo; Baranyai, Zsolt; Gaino, Luca; Forgács, Attila; Vágner, Adrienn; Botta, Mauro
2015-03-28
A complete thermodynamic and kinetic solution study on lanthanide(III) complexes with monoacetamide (DOTAMA, L1) and monopropionamide (DOTAMAP, L2) derivatives of DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was undertaken with the aim to elucidate their stability and inertness in aqueous media. The stability constants of GdL1 and GdL2 are comparable, whereas a more marked difference is found in the kinetic inertness of the two complexes. The formation of the Eu(III) and Ce(III) complexes takes place via the formation of the protonated intermediates which can deprotonate and transform into the final complex through a OH(-) assisted pathway. GdL2 shows faster rates of acid catalysed decomplexation with respect to GdL1, which has a kinetic inertness comparable to GdDOTA. Nevertheless, GdL2 is one order of magnitude more inert than GdDO3A. A novel DOTAMAP-based bifunctional chelating ligand and its deoxycholic acid derivative (L5) were also synthesized. Since the coordinated water molecule in GdL2 is characterized by an exchange rate ca. two orders of magnitude greater than in GdL1, the relaxivity of the macromolecular derivatives of L5 should not be limited by the slow water exchange process. The relaxometric properties of the supramolecular adduct of GdL5 with human serum albumin (HSA) were investigated in aqueous solution by measuring the magnetic field dependence of the (1)H relaxivity which, at 20 MHz and 298 K, shows a 430% increase over that of the unbound GdL5 chelate. Thus, Gd(III) complexes with DOTAMAP macrocyclic ligands can represent good candidates for the development of stable and highly effective bioconjugate systems for molecular imaging applications. PMID:25695351
Structural and Thermodynamic Properties of Septin 3 Investigated by Small-Angle X-Ray Scattering.
Ortore, Maria Grazia; Macedo, Joci N A; Araujo, Ana Paula U; Ferrero, Claudio; Mariani, Paolo; Spinozzi, Francesco; Itri, Rosangela
2015-06-16
Septins comprise a family of proteins involved in a variety of cellular processes and related to several human pathologies. They are constituted by three structural domains: the N- and C-terminal domains, highly variable in length and composition, and the central domain, involved in the guanine nucleotide (GTP) binding. Thirteen different human septins are known to form heterogeneous complexes or homofilaments, which are stabilized by specific interactions between the different interfaces present in the domains. In this work, we have investigated by in-solution small-angle x-ray scattering the structural and thermodynamic properties of a human septin 3 construct, SEPT3-GC, which contains both of both interfaces (G and NC) responsible for septin-septin interactions. In order to shed light on the role of these interactions, small-angle x-ray scattering measurements were performed in a wide range of temperatures, from 2 up to 56°C, both with and without a nonhydrolysable form of GTP (GTP?S). The acquired data show a temperature-dependent coexistence of monomers, dimers, and higher-order aggregates that were analyzed using a global fitting approach, taking into account the crystallographic structure of the recently reported SEPT3 dimer, PDB:3SOP. As a result, the enthalpy, entropy, and heat capacity variations that control the dimer-monomer dissociation equilibrium in solution were derived and GTP?S was detected to increase the enthalpic stability of the dimeric species. Moreover, a temperature increase was observed to induce dissociation of SEPT3-GC dimers into monomers just preceding their reassembling into amyloid aggregates, as revealed by the Thioflavin-T fluorescence assays. PMID:26083929
NASA Astrophysics Data System (ADS)
Seddik, T.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Bin-Omran, S.; Rached, D.
2012-03-01
The elastic, electronic and thermodynamic properties of fluoro-perovskite KZnF3 have been calculated using the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated with the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE). Also, we have used the Engel and Vosko GGA formalism (GGA-EV) to improve the electronic band structure calculations. The calculated structural properties are in good agreement with available experimental and theoretical data. The elastic constants C ij are calculated using the total energy variation with strain technique. The shear modulus, Young's modulus, Poisson's ratio and the Lamé coefficients for polycrystalline KZnF3 aggregates are estimated in the framework of the Voigt-Reuss-Hill approximations. The ductility behavior of this compound is interpreted via the calculated elastic constants C ij . Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The thermodynamic properties are predicted through the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variation of bulk modulus, lattice constant, heat capacities and the Debye temperature with pressure and temperature are successfully obtained.
NSDL National Science Digital Library
Huguet, Jesse
For engineering graduates entering the job market, experience with appropriate computational tools and techniques is increasingly necessary. Therefore, the University of Alabama's Mechanical Engineering Department is introducing students to computational problem solving earlier in their college careers by developing Microsoft Excel-based modules to be used as teaching tools in the sophomore and junior-level thermodynamics and heat transfer courses. The MS Excel package was chosen as a software platform for this purpose because of its ubiquitous nature and its ability to utilize Visual Basic for Applications (VBA) macros in a spreadsheet format. In the sophomore-level thermodynamics course, much of the class material focuses on the properties of steam and ideal gases. Therefore, a suite of Microsoft Excel functions to compute steam and ideal gas properties and assist in analyzing properties of states and processes has been developed. A number of Excel packages that pertained to the computation of steam properties were already available in the public domain. In a companion paper1, these packages were compared and Magnus Holmgrens Xsteam functions were chosen as a starting point for the current project.
Pandey, Ravi
1999 Abstract. Structural, thermodynamic and electronic properties of CdGeAs2 with chalcopyrite of the chalcopyrite group [17, 18], we are not aware of any such calculations on CdGeAs2. In this paper, we report
NASA Astrophysics Data System (ADS)
Fisenko, Anatoliy I.; Lemberg, Vladimir
2014-07-01
Using the explicit form of the functions to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies v 1? v? v 2 are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60-600 GHz frequency interval at the temperature T=2.72548 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant ? are calculated. In the case of the dipole spectrum, the constants a and ?, and the radiative and thermodynamic properties of the CMB radiation are obtained using the mean amplitude T amp=3.358 mK. It is shown that the Doppler shift leads to a renormalization of the radiation density constant a, the Stefan-Boltzmann constant ?, and the corresponding constants for the thermodynamic functions. The expressions for new astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of CMB photons are obtained. The radiative and thermodynamic properties of the Cosmic Microwave Background radiation for the monopole and dipole spectra at redshift z?1089 are calculated.
NASA Astrophysics Data System (ADS)
Di Genova, D.; Romano, C.; Alletti, M.; Behrens, H.; Scaillet, B.
2011-12-01
The rheological and thermodynamic properties of silicate melts control fluid-dynamics of transport, eruption style and rates of physico-chemical processes (degassing and crystallization) in natural magmas. In this study we investigated the effect of H2O and CO2 on the liquid viscosity and heat capacity on several multicomponent systems. Measurements were conducted on four series of melts, obtained by remelting and homogenization of natural pantelleritic (Khaggiar dome, Pantelleria), trachytic (Agnano Monte Spina eruption, Phlegrean Fields), latitic (Fondo Riccio eruption, Phlegrean Fields) and trachybasaltic (Etna 1992 eruption) magmas. CO2 or H2O synthesis experiments were conducted in piston cylinder apparatus. The volatile -bearing samples were measured with a differential scanning calorimeter (DSC) and a vertical dilatometer (micropenetration technique). Water and CO2 content were measured by Karl Fisher Titration and FTIR spectroscopy. Compositions were analyzed over a range of water contents up to 5.3 wt% and CO2 content up to 4000 ppm. Viscosity ranged from 108 to 1013 Pa s with decreasing temperature from 630 to 1100 K. Viscosity is strongly affected by H2O and CO2. The effect of CO2 on viscosity appears to be a function of speciation and chemical composition. The heat capacity of glasses and liquids and the glass transition interval were also investigated. Base chemical composition have a strong influences on Tg: high alkali contents can lower Tg of low NBO/T liquids. This behavior is demonstrated by Pantellerite samples. Glass transition temperatures are also strongly affected by H2O and CO2. The CO2 effect, such as water, is to decrease Tg and it appears to be a function of chemical composition. We present data for partial molar CpH2Omol and CpOH- and derive a simple expression to evaluate the relative contributions of different H-bearing species to the total heat capacity of hydrous melts. Experimental viscosity and calorimetric data were fitted according to the Adam and Gibbs theory in which configurational entropy (Sconf) is the main factor controlling the viscosity of melts. From calorimetric measurements, and assuming that the vibrational contribution to the liquid Cp remains constant above Tg, we determined the configurational contribution to Cpliq and thus calculated the variation of the Sconf as a function of T, H2O and CO2 content in the liquid state. Combining viscosity measurements with the configurational entropies for our liquids, we parameterized the variation of viscosity as a function of temperature and volatiles content within the framework of the Adam and Gibbs theory of structural relaxation.
Boscia, Alexander L.; Treece, Bradley W.; Mohammadyani, Dariush; Klein-Seetharaman, Judith; Braun, Anthony R.; Wassenaar, Tsjerk A.; Klösgen, Beate; Tristram-Nagle, Stephanie
2014-01-01
Cardiolipins (CLs) are important biologically for their unique role in biomembranes that couple phosphorylation and electron transport like bacterial plasma membranes, chromatophores, chloroplasts and mitochondria. CLs are often tightly coupled to proteins involved in oxidative phosphorylation. The first step in understanding the interaction of CL with proteins is to obtain the pure CL structure, and the structure of mixtures of CL with other lipids. In this work we use a variety of techniques to characterize the fluid phase structure, material properties and thermodynamics of mixtures of dimyristoylphosphatidylcholine (DMPC) with tetramyristoylcardiolipin (TMCL), both with 14-carbon chains, at several mole percentages. X-ray diffuse scattering was used to determine structure, including bilayer thickness and area/lipid, the bending modulus, KC, and Sxray, a measure of chain orientational order. Our results reveal that TMCL thickens DMPC bilayers at all mole percentages, with a total increase of ~6 Å in pure TMCL, and increases AL from 64 Å2 (DMPC at 35°C) to 109 Å2 (TMCL at 50°C). KC increases by ~50%, indicating that TMCL stiffens DMPC membranes. TMCL also orders DMPC chains by a factor of ~2 for pure TMCL. Coarse grain molecular dynamics simulations confirm the experimental thickening of 2 Å for 20 mol% TMCL and locate the TMCL headgroups near the glycerol-carbonyl region of DMPC; i.e., they are sequestered below the DMPC phosphocholine headgroup. Our results suggest that TMCL plays a role similar to cholesterol in that it thickens and stiffens DMPC membranes, orders chains, and is positioned under the umbrella of the PC headgroup. CL may be necessary for hydrophobic matching to inner mitochondrial membrane proteins. Differential scanning calorimetry, Sxray and CGMD simulations all suggest that TMCL does not form domains within the DMPC bilayers. We also determined the gel phase structure of TMCL, which surprisingly displays diffuse X-ray scattering, like a fluid phase lipid. AL = 40.8 Å2 for the ½TMCL gel phase, smaller than the DMPC gel phase with AL = 47.2 Å2, but similar to AL of DLPE = 41 Å2, consistent with untilted chains in gel phase TMCL. PMID:24378240
Xiong, Yongliang
2007-05-01
MgO is the only engineered barrier certified by EPA for the Waste Isolation Pilot Plant (WIPP) in USA. The German Asse repository will also employ an Mg(OH){sub 2} (brucite)-based engineered barrier. The chemical function of the engineered barrier is to consume CO{sub 2} that may be generated by the microbial degradation of organic materials in waste packages. Experimental results at SNL indicate that MgO is first hydrated as brucite, and then brucite is carbonated as hydromagnesite (5424) (Mg{sub 5}(CO{sub 3}){sub 4}(OH){sub 2} {center_dot} 4H{sub 2}O). As MgO is in excess relative to CO{sub 2} that may be produced, the brucite-hydromagnesite (5424) assemblage would buffer f{sub CO2} in the repository. Consequently, the thermodynamic properties of this assemblage is of great significance to the performance assessment (PA) as actinide solubility is strongly affected by f{sub CO2}. In turn, PA is important to the demonstration of the long-term safety of nuclear waste repositories, as assessed by the use of probabilistic performance calculations. There is a substantial discrepancy for {Delta}{sub f}G{sub brucite}{sup 0} in recent publications, ranging from -830.4 (Harvie et al., 1984; Geochim. Cosmochim. Acta, 723-751), through -831.9 (Brown et al., 1996; J. Chem. Soc., Dalton Trans., 3071-3075), through -833.5 (Robie and Hemingway, 1995; USGS Bull., 2131), and to -835.9 kJ mol{sup -1} (Konigsberger et al., 1999; Geochim. Cosmochim. Acta, 3105-3119). Using the {Delta}{sub f}G{sub hydromagnesite (5424)}{sup 0} from Konigsberger et al., the predicted log f{sub CO2} for this assemblage would range from -5.96 ({Delta}{sub f}G{sub brucite}{sup 0} from Harvie et al.) to -4.84 ({Delta}{sub f}G{sub brucite}{sup 0} from Konigsberger et al.). Therefore, it is desirable to better constrain the {Delta}{sub f}G{sub brucite}{sup 0}. For this reason, a series of solubility experiments involving brucite in NaCl solutions ranging from 0.01 M to 4.0 M have being conducted at SNL. The derived {Delta}{sub f}G{sub brucite}{sup 0} from this study by extrapolation to infinite dilution via Pitzer formalism is -830.8 kJ mol{sup -1}, which is in excellent agreement with recommended values of Harvie et al. and Brown et al.
NASA Astrophysics Data System (ADS)
Johann, Robert
2001-10-01
Research on monolayers of amphiphilic lipids on aqueous solution is of basic importance in surface science. Due to the applicability of a variety of surface sensitive techniques, floating insoluble monolayers are very suitable model systems for the study of order, structure formation and material transport in two dimensions or the interactions of molecules at the interface with ions or molecules in the bulk (headword 'molecular recognition'). From the behavior of monolayers conclusions can be drawn on the properties of lipid layers on solid substrates or in biological membranes. This work deals with specific and fundamental interactions in monolayers both on the molecular and on the microscopic scale and with their relation to the lattice structure, morphology and thermodynamic behavior of monolayers at the air-water interface. As model system especially monolayers of long chain fatty acids are used, since there the molecular interactions can be gradually adjusted by varying the degree of dissociation by means of the suphase pH value. For manipulating the molecular interactions besides the subphase composition also temperature and monolayer composition are systematically varied. The change in the monolayer properties as a function of an external parameter is analyzed by means of isotherm and surface potential measurements, Brewster-angle microscopy, X-ray diffraction at grazing incidence and polarization modulated infrared reflection absorption spectroscopy. For this a quantitative measure for the molecular interactions and for the chain conformational order is derived from the X-ray data. The most interesting results of this work are the elucidation of the origin of regular polygonal and dendritic domain shapes, the various effects of cholesterol on molecular packing and lattice order of long chain amphiphiles, as well as the detection of an abrupt change in the head group bonding interactions, the chain conformational order and the phase transition pressure between tilted phases in fatty acid monolayers near pH 9. For the interpretation of the latter point a model of the head group bonding structure in fatty acid monolayers as a function of the pH value is developed. Untersuchungen an Monoschichten amphiphiler Lipide auf wässriger Lösung sind in der Grenzflächenforschung von grundlegender Bedeutung. Aufgrund der Anwendbarkeit zahlreicher analytischer Methoden sind schwimmende unlösliche Monoschichten als Modellsysteme sehr geeignet, um Ordnung und Strukturbildung sowie den Transport von Materie in zwei Dimensionen oder die Wechselwirkung von Molekülen an der Grenzfläche mit Teilchen in Lösung (Stichwort “molekulare Erkennung”) zu studieren. Aus dem Verhalten von Monoschichten lassen sich z. B. Rückschlüsse ziehen auf die Eigenschaften von Lipidschichten auf festen Substraten oder in biologischen Membranen. Diese Arbeit befasst sich mit spezifischen und fundamentalen Wechselwirkungen in Monoschichten sowohl auf molekularer als auch auf mikroskopischer Ebene und deren Beziehung zu Gitterstruktur, Aussehen und thermodynamischem Verhalten von Monoschichten an der Wasser/Luft Grenzfläche. Als Modellsystem werden hauptsächlich Monoschichten langkettiger Fettsäuren verwendet, da in ihnen die molekularen Wechselwirkungen durch Änderung des Subphasen-pH-Werts über den Dissoziationsgrad gezielt und schrittweise verändert werden können. Ausser über die Subphasenzusammensetzung werden die molekularen Wechselwirkungen auch über die Temperatur und die Monoschichtzusammensetzung systematisch variiert. Mit Hilfe von Isothermen- und Oberflächenpotentialmessungen, Brewsterwinkel-Mikroskopie, Röntgenbeugung unter streifendem Einfall und polarisationsmodulierter Infrarot-Reflexions-Absorptions-Spektroskopie wird die Änderung der Monoschichteigenschaften als Funktion eines äusseren Parametern analysiert. Dabei werden aus den Röntgenbeugungsdaten quantitative Masse für die molekularen Wechselwirkungen und für die Kettenkonformationsordnung in Monoschichten abgeleitet. Zu den interessantesten Erge
Rational design of ion force fields based on thermodynamic solvation properties
NASA Astrophysics Data System (ADS)
Horinek, Dominik; Mamatkulov, Shavkat I.; Netz, Roland R.
2009-03-01
Most aqueous biological and technological systems contain solvated ions. Atomistic explicit-water simulations of ionic solutions rely crucially on accurate ionic force fields, which contain most commonly two adjustable parameters: the Lennard-Jones diameter and the interaction strength. Assuming these parameters to be properly optimized, the plethora of parameters one finds in the literature for one and the same ion is surprising. In principle, the two parameters should be uniquely determined by matching two ionic properties obtained for a particular water model and within a given simulation protocol with the corresponding experimental observables. Traditionally, ion parameters were chosen in a somewhat unsystematic way to reproduce the solvation free energy and to give the correct ion size when compared with scattering results. Which experimental observable one chooses to reproduce should in principle depend on the context within which the ionic force field is going to be used. In the present work we suggest to use the solvation free energy in conjunction with the solvation entropy to construct thermodynamically sound force fields for the alkali and halide ions for the simulation of ion-specific effects in aqueous environment. To that end we determine the solvation free energy and entropy of both cations and anions in the entire relevant parameter space. As an independent check on the quality of the resulting force fields we also determine the effective ionic radius from the first peak of the radial ion-water distribution function. Several difficulties during parameter optimization are discussed in detail. (i) Single-ion solvation depends decisively on water-air surface properties, which experimentally becomes relevant when introducing extrathermodynamic assumptions on the hydronium (H3O+) solvation energy. Fitting ion pairs circumvents this problem but leaves the parameters of one reference ion (here we choose chloride) undetermined. (ii) For the halides the problem is almost underdetermined, i.e., there is a whole set of degenerate parameters that equally well describe, e.g., chloride and bromide ions. (iii) For the heavy cations the problem is overdetermined, i.e., no combination of Lennard-Jones parameters is able to reproduce simultaneously energy and entropy of solvation. We discuss various possibilities to deal with these problems and finally present an optimized force field for the halide anions that reproduces the free energy and the entropy of solvation. For the alkali metal cations there is no unambiguous choice of parameters. Therefore, we give three different parameter sets for every ion with a small, intermediate, or large Lennard-Jones interaction strength, where the Lennard-Jones diameters are optimized to reproduce the solvation free energy. The ionic radius is reproduced with acceptable accuracy by this optimization strategy, meaning that the proposed force fields are reliable beyond the target observables (i.e., free energy and entropy of solvation).
Rational design of ion force fields based on thermodynamic solvation properties.
Horinek, Dominik; Mamatkulov, Shavkat I; Netz, Roland R
2009-03-28
Most aqueous biological and technological systems contain solvated ions. Atomistic explicit-water simulations of ionic solutions rely crucially on accurate ionic force fields, which contain most commonly two adjustable parameters: the Lennard-Jones diameter and the interaction strength. Assuming these parameters to be properly optimized, the plethora of parameters one finds in the literature for one and the same ion is surprising. In principle, the two parameters should be uniquely determined by matching two ionic properties obtained for a particular water model and within a given simulation protocol with the corresponding experimental observables. Traditionally, ion parameters were chosen in a somewhat unsystematic way to reproduce the solvation free energy and to give the correct ion size when compared with scattering results. Which experimental observable one chooses to reproduce should in principle depend on the context within which the ionic force field is going to be used. In the present work we suggest to use the solvation free energy in conjunction with the solvation entropy to construct thermodynamically sound force fields for the alkali and halide ions for the simulation of ion-specific effects in aqueous environment. To that end we determine the solvation free energy and entropy of both cations and anions in the entire relevant parameter space. As an independent check on the quality of the resulting force fields we also determine the effective ionic radius from the first peak of the radial ion-water distribution function. Several difficulties during parameter optimization are discussed in detail. (i) Single-ion solvation depends decisively on water-air surface properties, which experimentally becomes relevant when introducing extrathermodynamic assumptions on the hydronium (H(3)O(+)) solvation energy. Fitting ion pairs circumvents this problem but leaves the parameters of one reference ion (here we choose chloride) undetermined. (ii) For the halides the problem is almost underdetermined, i.e., there is a whole set of degenerate parameters that equally well describe, e.g., chloride and bromide ions. (iii) For the heavy cations the problem is overdetermined, i.e., no combination of Lennard-Jones parameters is able to reproduce simultaneously energy and entropy of solvation. We discuss various possibilities to deal with these problems and finally present an optimized force field for the halide anions that reproduces the free energy and the entropy of solvation. For the alkali metal cations there is no unambiguous choice of parameters. Therefore, we give three different parameter sets for every ion with a small, intermediate, or large Lennard-Jones interaction strength, where the Lennard-Jones diameters are optimized to reproduce the solvation free energy. The ionic radius is reproduced with acceptable accuracy by this optimization strategy, meaning that the proposed force fields are reliable beyond the target observables (i.e., free energy and entropy of solvation). PMID:19334851
Proscia, W.M.; Freihaut, J.D.
1993-08-01
Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is essential to the fundamental determination of kinetic parameters of coal devolatilization. These same properties are also needed to refine existing devolatilization sub-models utilized in large-scale modeling of coal combustion systems. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. The coal ranks to be investigated will include a high volatile A bituminous (PSOC 1451 D) and a low volatile bituminous (PSOC 1516D). An anthracite (PSOC 1468) will be used as a non-volatile coal reference. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars.
NASA Astrophysics Data System (ADS)
Dri, Fernando L.; Shang, ShunLi; Hector, Louis G., Jr.; Saxe, Paul; Liu, Zi-Kui; Moon, Robert J.; Zavattieri, Pablo D.
2014-12-01
Anisotropy and temperature dependence of structural, thermodynamic and elastic properties of crystalline cellulose I? were computed with first-principles density functional theory (DFT) and a semi-empirical correction for van der Waals interactions. Specifically, we report the computed temperature variation (up to 500 K) of the monoclinic cellulose I? lattice parameters, constant pressure heat capacity, Cp, entropy, S, enthalpy, H, the linear thermal expansion components, ?i, and components of the isentropic and isothermal (single crystal) elastic stiffness matrices, CijS (T) and CijT (T) , respectively. Thermodynamic quantities from phonon calculations computed with DFT and the supercell method provided necessary inputs to compute the temperature dependence of cellulose I? properties via the quasi-harmonic approach. The notable exceptions were the thermal conductivity components, ?i (the prediction of which has proven to be problematic for insulators using DFT) for which the reverse, non-equilibrium molecular dynamics approach with a force field was applied. The extent to which anisotropy of Young's modulus and Poisson's ratio is temperature-dependent was explored in terms of the variations of each with respect to crystallographic directions and preferred planes containing specific bonding characteristics (as revealed quantitatively from phonon force constants for each atomic pair, and qualitatively from charge density difference contours). Comparisons of the predicted quantities with available experimental data revealed reasonable agreement up to 500 K. Computed properties were interpreted in terms of the cellulose I? structure and bonding interactions.
NASA Astrophysics Data System (ADS)
Behnejad, Hassan; Cheshmpak, Hashem; Jamali, Asma
2015-01-01
In this paper, a theoretical method has been introduced for developing the crossover Peng-Robinson (CPR) equation of state (EoS) which incorporates the non-classical scaling laws asymptotically near the critical point into a classical analytic equation further away from the critical point. The CPR EoS has been adopted to describe the thermodynamic properties of some pure fluids (normal alkanes from methane to n-butane and carbon dioxide) such as density, saturated pressure, isochoric heat capacity and speed of sound. Unlike the original method for the crossover transformation made by Chen et al. (Phys Rev A 42:4470-4484, 1990), we have proposed a procedure which adding an additional term into the crossover transformation to obtain the thermophysical properties at the critical point more exactly. It is shown that this new crossover method yields a satisfactory representation of the thermodynamic properties close to the critical point for pure fluids relative to the original PR EoS.
Nagashima, H., E-mail: nagashima@nanoint.ifs.tohoku.ac.jp [School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsuda, S. [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan)] [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan); Tsuboi, N. [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan)] [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Koshi, M. [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan)] [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan); Hayashi, K. A. [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan)] [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan); Tokumasu, T. [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)] [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)
2014-04-07
In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density–temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure–volume–temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases.
Julian Gonzalez-Ayala; J. Perez-Oregon; Rubén Cordero; F. Angulo-Brown
2015-02-19
In this work we present the generalization of some thermodynamic properties of the black body radiation (BBR) towards an $n-$dimensional Euclidean space. For this case the Planck function and the Stefan-Boltzmann law have already been given by Landsberg and de Vos and some adjustments by Menon and Agrawal. However, since then no much more has been done on this subject and we believe there are some relevant aspects yet to explore. In addition to the results previously found we calculate the thermodynamic potentials, the efficiency of the Carnot engine, the law for adiabatic processes and the heat capacity at constant volume. There is a region at which an interesting behavior of the thermodynamic potentials arise, maxima and minima appear for the $n-d$ BBR system at very high temperatures and low dimensionality, suggesting a possible application to cosmology. Finally we propose that an optimality criterion in a thermodynamic framework could have to do with the $3-d$ nature of the universe.
Thermodynamic properties of relaxed (TMTSF)2ClO{4} in magnetic field; the one-electron picture
NASA Astrophysics Data System (ADS)
Radi?, D.; Bjeliš, A.; Zanchi, D.
2005-12-01
We analyse thermodynamic properties of band electrons in the normal state of relaxed (TMTSF){2}ClO{4} with transverse dimerization potential V due to anion ordering and with a finite external magnetic field. Providing the exact solution for electron spectrum, we extend the scope of analysis from perturbative limit covered in previous literature to the physically relevant regime of large dimerizing potentials comparable to the electron interchain hopping t. The one-electron spectrum shows characteristic oscillations, periodic in inverse magnetic field, best fitted with V/t? 0.8. The same oscillations are present in electron free energy and specific heat. We find that the amplitude of thermodynamic oscillations drastically increases by changing the magnitude of dimerizing potential towards V ˜ t, thus adding an important contribution to the set of already known oscillatory mechanisms.
NASA Astrophysics Data System (ADS)
Zhang, Xu-Dong; Cui, Shou-Xin; Shi, Hai-Feng
2014-01-01
In extended pressure and temperature ranges, a theoretical study of the isothermal bulk modulus of SiC in B3 structure under high pressure and temperature is carried out by means of first-principles density functional theoretical calculations combined with the quasi-harmonic Debye model. Through the quasi-harmonic Debye model, the isothermal bulk modulus and its first and second pressure derivatives are successfully obtained. The thermodynamics properties of 3C-SiC are investigated in the pressure range of 0-100 GPa and the temperature range of 0-2000 K.
Richard T. Scalettar; Warren E. Pickett
2005-08-02
This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.
Richard T. Scalettar; Warren E. Pickett
2005-01-01
This project involves research into the thermodynamic properties;\\u000aof f-electron metals, transition metal oxides, and half-metallic;\\u000amagnets at high pressure. These materials are ones in which the;\\u000achanging importance of electron-electron interactions as;\\u000athe distance between atoms is varied;\\u000acan tune the system through phase transitions;\\u000afrom localized to delocalized electrons,;\\u000afrom screened to unscreened magnetic moments,;\\u000aand from normal
Scalettar, Richard T.; Pickett, Warren E.
2004-07-01
This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.
NASA Astrophysics Data System (ADS)
Cheng, Yan; Hu, Cui-E; Zeng, Zhao-Yi; Gong, Min; Gou, Qing-Quan
2009-05-01
The phonon and thermodynamics properties of face-centered cubic CaF2 at high pressure and high temperature are investigated by using the shell model interatomic pair potential within General Utility Lattice Program (GULP). The phonon dispersion curves and the corresponding density of state (PDOS) in this work are consistent with the experimental data and other theoretical results. The transverse optical (TO) and longitudinal optical (LO) mode splitting as well as heat capacity at constant volume CV and entropy S versus pressure and temperature are also obtained.
NASA Technical Reports Server (NTRS)
Weber, L. A.
1977-01-01
The results of an experimental program are presented in the form of PVT data in the temperature range 58 to 300 K at pressures up to 800 bar. Tables of the derived thermodynamic properties on isobars to 1000 bar are given, including density, internal energy, enthalpy, entropy, specific heats at constant volume and constant pressure, velocity of sound, and the surface derivatives (delta P/delta T) sub rho and (delta P/delta Rho) sub T. Auxiliary tables in engineering units are also given. The accuracy of the data is discussed and comparisons are made with previous data.
Ryo Akasaka
2010-01-01
A new thermodynamic property model is presented for trans-1,3,3,3-tetrafluoropropene (trans-CHFCHCF3, HFO-1234ze(E)) based upon available experimental data. This model is an application of the extended corresponding states principle, which is one approach in property modeling for fluids with limited experimental databases. The model is capable of calculating with reasonable accuracies various properties of HFO-1234ze(E), including the PVT relation, energies, heat capacities,
NASA Astrophysics Data System (ADS)
Wu, Yurong; Xu, Longshan; Hu, Wangyu
2015-02-01
The thermodynamic and thermo-elastic properties of ductility intermetallic compounds DyCu with B2 structure are investigated with molecular dynamics. The calculated structural properties are in reasonable agreement with the available experimental and previously calculated data. At 300 K, the heat capacity of DyCu is 23.93 J mol-1 K-1. At the whole range 0-900 K, the elastic constants decrease with increasing temperature, and satisfy the stability criterions for DyCu compound. The value of B/G ratio for DyCu is greater than 1.75 implying the DyCu intermetallics are ductile, and increases with elevating temperature. Our results mean that the ductility of DyCu can be improved by increasing temperature.
Decremps, F; Gauthier, M; Ayrinhac, S; Bove, L; Belliard, L; Perrin, B; Morand, M; Le Marchand, G; Bergame, F; Philippe, J
2015-02-01
Based on the original combination of picosecond acoustics and diamond anvils cell, recent improvements to accurately measure hypersonic sound velocities of liquids and solids under extreme conditions are described. To illustrate the capability of this technique, results are given on the pressure and temperature dependence of acoustic properties for three prototypical cases: polycrystal (iron), single-crystal (silicon) and liquid (mercury) samples. It is shown that such technique also enables the determination of the density as a function of pressure for liquids, of the complete set of elastic constants for single crystals, and of the melting curve for any kind of material. High pressure ultrafast acoustic spectroscopy technique clearly opens opportunities to measure thermodynamical properties under previously unattainable extreme conditions. Beyond physics, this state-of-the-art experiment would thus be useful in many other fields such as nonlinear acoustics, oceanography, petrology, in of view. A brief description of new developments and future directions of works conclude the article. PMID:24852260
Thermodynamic Properties of o-Xylene, m-Xylene, p-Xylene, and Ethylbenzene
NASA Astrophysics Data System (ADS)
Zhou, Yong; Wu, Jiangtao; Lemmon, Eric W.
2012-06-01
Equations of state for the xylene isomers (o-xylene, m-xylene, and p-xylene) and ethylbenzene have been developed with the use of the Helmholtz energy as the fundamental property with independent variables of density and temperature. The general uncertainties of the equations of state are 0.5% in vapor pressure above the normal boiling point, and increase as the temperature decreases due to a lack of experimental data. The uncertainties in density range from 0.1% in the liquid region to 1.0% elsewhere (the critical and vapor-phase regions). The uncertainties in properties related to energy (such as heat capacity and sound speed) are estimated to be 1.0%. In the critical region, the uncertainties are higher for all properties. The behavior of the equations of state is reasonable within the region of validity and at higher and lower temperatures and pressures. Detailed analyses between the equations and experimental data are reported.
J Pátek; J Klomfar
1995-01-01
A set of five equations describing vapour-liquid equilibrium properties of the ammonia-water system is presented. They are intended for use in the design of absorption processes. Using variable dependences of technical relevance the equations make it possible to avoid iterative evaluations. The equations were constructed by fitting critically assessed experimental data using simple functional forms. They cover the region within
NASA Astrophysics Data System (ADS)
Akasaka, Ryo
This paper overviews Helmholtz energy equations of state for pure HFC and natural refrigerants. The equations of state consist of the ideal-gas part and the residual part. The ideal-gas part can be calculated from the ideal-gas isobaric heat capacity according to the ideal-gas law, and the residual part is determined empirically by fitting to experimental thermodynamic property data. Polynomial and exponential terms are used to represent the residual part. Some equations have more complex terms for accurate descriptions of critical behavior. Mixture models for applications of the pure-fluid equations of state to refrigerant mixtures are summarized. Until now, two mixture models have been developed for HFC refrigerant mixtures. This paper also discusses calculation methods for the pvT relation, vapor-liquid equilibrium, and critical point using Helmholtz energy equations of state. Few literature discusses the methods in detail, although such information is very precious to make a computer program for calculating thermodynamic properties.
Proscia, W.M.; Freihaut, J.D.
1993-03-01
Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is required both, for the fundamental determination of kinetic parameters of coal devolatilization, and to refine existing devolatilization sub-models used in comprehensive coal combustion codes. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Calibration of the heated grid calorimeter (Task 2) was completed this reporting period. Several refinements to the heated grid apparatus have been implemented which allow quantitative determination of sample heat capacity at high heating rates.
Thermodynamic properties of PbTe, PbSe, and PbS: a ?rst-principles study
Zhang, Yi [University of Nevada, Las Vegas; Ke, Xuezhi [University of Nevada, Las Vegas; Chen, Changfeng [University of Nevada, Las Vegas; Yang, Jihui [General Motors Corporation-R& D; Kent, Paul R [ORNL
2009-01-01
The recent discovery of novel lead chalcogenide-based thermoelectric materials has attracted great interest. These materials exhibit low thermal conductivity which is closely related to their lattice dynamics and thermodynamic properties. In this paper, we report a systematic study of electronic structures and lattice dynamics of the lead chalcogenides PbX (X=Te, Se, S) using ?rst-principles density functional theory calculations and a direct force-constant method. We calculate the struc- tural parameters, elastic moduli, electronic band structures, dielectric constants, and Born e?ective charges. Moreover, we determine phonon dispersions, phonon density of states, and phonon softening modes in these materials. Based on the results of these calculations, we further employ quasihar- monic approximation to calculate the heat capacity, internal energy, and vibrational entropy. The obtained results are in good agreement with experimental data. Lattice thermal conductivities are evaluated in terms of the Gruneisen parameters. The mode Gruneisen parameters are calculated to explain the anharmonicity in these materials. The e?ect of the spin-orbit interaction is found to be negligible in determining the thermodynamic properties of PbTe, PbSe, and PbS.
NASA Astrophysics Data System (ADS)
Yokomizu, Yasunobu; Ochiai, Ryusuke; Matsumura, Toshiro
Fundamental investigations were carried out to find out the admixing influence of CF3I to CO2. Firstly, thermodynamic properties at 0.1MPa were derived in a temperature range of 300-30,000K for various CF3I-concentrations XCF3I. Secondly, from the thermodynamic properties, a temperature-reduction factor was determined as a function of the temperature for different XCF3I. This determination led to the suggestion that admixture of CF3I to CO2 at XCF3I above 0.9 can produce a rapid effect on decay in the temperature of an extinguishing arc. Finally, the principal particles present after an arc extinction were obtained in consideration of the phase transformation of iodine molecules at 0.1MPa. For instance, the principal particles proved to be CO2, CF4 and CO in the gaseous phase and I2 in the solid phase for XCF3I of 0.01-0.94.
NASA Astrophysics Data System (ADS)
Jahangiri, M.; Jacobsen, R. T.; Stewart, R. B.; McCarty, R. D.
1986-05-01
A new thermodynamic property formulation based upon a fundamental equation explicit in Helmholtz energy of the form A= A( ?, T) for ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. A vapor pressure equation, equations for the saturated liquid and vapor densities as functions of temperature, and an equation for the ideal-gas heat capacity are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least-squares fit to selected P-?-T data, saturated liquid and saturated vapor density data to define the phase equilibrium criteria for coexistence, C v data, velocity of sound data, and second virial coefficients. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity ( C v), isobaric heat capacity ( C p), and velocity of sound are included. The fundamental equation reported here may be used to calculate pressures and densities with an uncertainty of ±0.1%, heat capacities within ±3 %, and velocity of sound values within ±1 %, except in the region near the critical point. The fundamental equation is not intended for use near the critical point. This formulation is proposed as part of a new international standard for thermodynamic properties of ethylene.
NASA Astrophysics Data System (ADS)
Hummer, Gerhard; Pratt, Lawrence R.; García, Angel E.; Neumann, Martin
1999-11-01
We review the treatment of electrostatic interactions in computer simulations under periodic boundary conditions, with emphasis on Ewald summation. Connections between Ewald summation and reaction field approaches will be made within a unifying picture of electrostatic potentials in Wigner lattices. The calculation of thermodynamic pressures in simulations of polar and ionic media will be discussed. Effects of finite system size on charging free energies will be analyzed. In addition, we will briefly review the problem of defining proper thermodynamic limits for single-ion properties. We find that cluster (or droplet) calculations of ionic solvation enthalpies or free energies (e.g., based on quantum mechanical methods) contain a contribution stemming from the charge ordering in the cluster-vacuum interface. This interfacial potential can lead to deviations of calculated single-ion enthalpies and free energies from the values in a properly defined thermodynamic limit at infinite ionic dilution. Finally, we will study the validity of linear response approximations for Coulomb systems. The origin of non-linearities in charging free energies will be traced to variations in the microscopic structure. We will conclude with a discussion of accurate integration methods for non-linear free energy expressions.
NASA Astrophysics Data System (ADS)
Runov, A.; Angelopoulos, V.; Gabrielse, C.; Liu, J.; Turner, D. L.; Zhou, X.
2014-12-01
Numerous studies involving space-born and ground-based observations as well as simulations have suggested that a few Earth's radii-wide narrow channels of fast plasma flow carrying a dipolarized magnetic field play the key role in the magnetic flux, plasma, and energy transport in the magnetotail and toward the inner magnetosphere. These structures were theoretically described as ``plasma bubbles''. Recently, the term ``dipolairizing flux bundle'' (DFB) has been introduced to describe the plasma bubble-like structure on the basis of local spacecraft measurements. We present statistical analysis of DFB observations by THEMIS probes during 2008 and 2009 tail-science seasons. The goal of this study is to understand how the DFB plasma is energized and how its thermodynamic (density, temperature, specific entropy, and bulk velocity) and spectral properties depend on the geocentric distance. To achieve this goal, 271 events observed at radial distances from ~7 to 25 RE downtail were selected. We compare i) the thermodynamic parameters and energy spectra inside DFBs with those in the ambient plasma sheet and ii) the thermodynamic parameters and the spectra inside DFBs observed at different geocentric distances.
NASA Astrophysics Data System (ADS)
Rajamani, T.; Muthu, S.
2013-02-01
The Fourier transform infrared (FT-IR) and FT-Raman of 9-[(2-hydroxyethoxy) methyl] guanine (9-2HEMG) have been recorded in the regions 4000-100 and 4000-400 cm-1, respectively. A complete assignment and analysis of the fundamental vibrational modes of the molecule were carried out. The observed fundamental modes have been compared with the harmonic vibrational frequencies computed using DFT (B3LYP) method by employing 6-31G(d,p) and 3-21G basis sets. The vibrational studies were interpreted in terms of potential energy distribution. The first order hyperpolarizability (?0) and related properties (?, ? and ??) of this molecular system are calculated using B3LYP/6-31G(d,p) method based on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that electron density (ED) in the ?* and ?* antibonding orbitals and second-order delocalization energies (E(2)) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound has been recorded and electronic properties such as excitation energies, oscillator strength and wavelength are calculated by TD-DFT and CIS methods using B3LYP/6-31G (d,p) basis set. Molecular electrostatic potential (MEP) and HOMO-LUMO energy levels are also constructed. The thermodynamic properties of the title compound have been calculated at different temperatures and the results reveal that the standard heat capacities (Cp,m), standard entropies (Sm) and standard enthalpy changes (Hm) increase with rise in temperature.
THE ELASTIC AND THERMODYNAMIC PROPERTIES OF Lu DOPED ScVO3
NASA Astrophysics Data System (ADS)
Parveen, Atahar; Gaur, N. K.
2012-12-01
We have investigated the elastic, cohesive and thermal properties of (Lu, Sc) VO3 and Sc1-xLuxVO3(0.6 ? x ? 0.9) perovskites by means of a modified rigid ion model (MRIM). The variation of specific heat is determined following the temperature driven structural phase transitions. Also, the effect of lattice distortions on the elastic and thermal properties of the present pure and doped vanadates has been studied by an atomistic approach. The calculated bulk modulus (BT), reststrahlen frequency (?0), cohesive energy (?), Debye temperature (?D) and Gruneisen parameter (?) reproduce well with the corresponding experimental data. The specific heat results can further be improved by including the magnetic ordering contributions to the specific heat.
Thermodynamical and microscopic properties of turbulent transport in the edge plasma
NASA Astrophysics Data System (ADS)
Ghendrih, Ph; Norscini, C.; Hasenbeck, F.; Dif-Pradalier, G.; Abiteboul, J.; Cartier-Michaud, T.; Garbet, X.; Grandgirard, V.; Marandet, Y.; Sarazin, Y.; Tamain, P.; Zarzoso, D.
2012-12-01
Edge plasma turbulence modelled with 2D interchange is shown to exhibit convective transport at the microscale level. This transport property is related to avalanche like transport in such a flux-driven system. Correlation functions and source modulation are used to analyse the transport properties but do not allow one to recover the Fick law that must characterise the system at large scales. Coarse graining is then introduced to average out the small scales in order to recover the Fick law. One finds that the required space averaging is comparable to the system size while the time averaging is comparable to the confinement time. The system is then reduced to a single reservoir such that transport is characterised by a single scalar, either the diffusion coefficient of the Fick law or a characteristic evolution time constant.
Murphy, R.W.
1994-12-01
Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.
Ab initio calculation of lattice dynamics and thermodynamic properties of beryllium
NASA Astrophysics Data System (ADS)
Luo, Fen; Cai, Ling-Cang; Chen, Xiang-Rong; Jing, Fu-Qian; Alfè, Dario
2012-03-01
We investigate the phase transition, elastic constants, phonon dispersion curves, and thermal properties of beryllium (Be) at high pressures and high temperatures using density functional theory. By comparing the Gibbs free energy, in the quasiharmonic approximation (QHA), of hexagonal-closed-packed (hcp) with those of the face-centered cubic (fcc) and body-centered-cubic (bcc) we find that the hcp Be is stable up to 390 GPa, and then transforms to the bcc Be. The calculated phonon dispersion curves are in excellent agreement with experiments. Under compression, the phonon dispersion curves of hcp Be do not show any anomaly or instability. At low pressure the phonon dispersion of bcc Be display imaginary along ?-N in the T1 branches. Within the quasiharmonic approximation, we predict the thermal equation of state and other properties including the thermal expansion coefficient, Hugoniot curves, heat capacity, Grüneisen parameter, and Debye temperature.
Seung-Kyo Oh; Chol-Ho Sim
2002-01-01
Earlier work of the group contribution method presented by Oh and Campbell [Oh and Campbell, 1997] for prediction of second\\u000a virial coefficients and dilute gas transport properties has been repeated with a new set of normal alkane second virial coefficient\\u000a data (methane, ethane, propane, and normal pentane critically compiled by Dymond and Smith [1980], normal hexane recommended\\u000a by Dymond et
Molecular dynamics simulations of the structural, elastic and thermodynamic properties of cubic BBi
K. Amara; B. Soudini; D. Rached; A. Boudali
2008-01-01
We present the molecular dynamics simulations results of the structural and dynamical properties of the zinc-blende BBi over a wide range of temperature (400–1500K). Our simulations were carried out using the three-body Tersoff potential, which accurately reproduces the lattice and elastic constants of the BBi. A good agreement was found between our calculated results and the available theoretical data of
Structural, thermodynamic, mechanical, and magnetic properties of FeW system
Ren, Q. Q.; Fan, J. L.; Han, Y.; Gong, H. R., E-mail: gonghr@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)
2014-09-07
The Fe-W system is systematically investigated through a combined use of first-principles calculation, cluster expansion, special quasirandom structures, and experiments. It is revealed that the ferromagnetic state of BCC Fe-W solid solution has lower heat of formation than its nonmagnetic state within the entire composition range, and intermetallic ?-Fe{sub 2}W and ?-Fe{sub 7}W{sub 6} phases are energetically favorable with negative heats of formation. Calculations also show that the Fe-W solid solution has much lower coefficient of thermal expansion than its mechanical mixture, and that the descending sequence of temperature-dependent elastic moduli of each Fe-W solid solution is E?>?G?>?B. Moreover, magnetic state should have an important effect on mechanical properties of Fe-W phases, and electronic structures can provide a deeper understanding of various properties of Fe-W. The derived results agree well with experimental observations, and can clarify two experimental controversies regarding structural stability and magnetic property of Fe-W phases in the literature.
Wettig, Shawn D; Wang, Chuanzhong; Verrall, Ronald E; Foldvari, Marianna
2007-02-21
Improving the efficiency of gene delivery by using non-viral vectors is currently an area of considerable research interest. Novel derivatives of gemini surfactants having aza- (12-5N-12, 12-7N-12, 12-8N-12) and imino- (12-7NH-12) substituted spacer groups and C12 tails have been designed to improve DNA transfection. Physicochemical characterization of micelle and interfacial properties of these cationic compounds are reported. The effect of these substitutions on the aggregation properties of the gemini surfactants is discussed in the context of results for the 12-s-12 and 12-EOx-12 gemini series, previously reported in the literature. Aza substitution results in a spacer of intermediate hydrophobicity to the above series, reflected by the magnitude of both the critical micelle concentrations and head group areas. Enthalpy and apparent molar volume of micellization data illustrate the differences in the aggregation properties that result from the bulkier and more hydrophobic aza-substituent in the spacer as compared to an ether oxygen (for the 12-EOx-12 series) containing spacer. The 12-7N-12 and 12-8N-12 compounds show aberrant features in the surface tension and enthalpy of dilution results that are not observed for the 12-5N-12 and 12-7NH-12 compounds. Premicelle association is considered to be a source of this behaviour. PMID:17287881
Zaghloul, Mofreh R. [Department of Physics, College of Sciences, United Arab Emirates University, Al-Ain, 177551 (United Arab Emirates)
2010-12-15
The problem of the calculation of equilibrium thermodynamic properties and the establishment of statistical-thermodynamically consistent finite bound-state partition functions in nonideal multicomponent plasma systems is revised within the chemical picture. The present exploration accompanied by the introduction of a generalized consistent formulation, in terms of the solution of the inverse problem, clears ambiguities and gives a better understanding of the problem on top of pointing out weaknesses and inaccuracies/inconsistencies buried in widely used models in literature.
Gallagher, J.S.; Levelt Sengers, J.M.H.; Morrison, G.; Sengers, J.V.
1984-07-01
The Helmholtz function for pure isobutane from a recent correlation has been converted to a dimensionless form and a pressure-enthalpy chart based on this function has been generated by computer. A Helmholtz function for mixtures of isobutane and isopentane has been formed based upon the dimensionless isobutane Helmholtz function as the reference fluid by means of an extended corresponding-states principle. Scarce literature data for saturation properties of isopentane, and new data for its vapor pressure and for the critical line of the mixture were used. The accuracy of the surface was checked by comparing with literature enthalpy data and with new VLE data for the mixture. Tables of thermodynamic properties have been generated from this Helmholtz function for the 0.1 mole fraction isopentane-in-isobutane mixture in the single-phase region and on the dew- and bubble-point curves, together with properties of the coexisting phase. A pressure-enthalpy chart for this mixture has also been generated.
Calculation of the thermodynamic properties of fuel-vapor species from spectroscopic data
Green, D.W.
1980-09-01
Measured spectroscopic data, estimated molecular parameters, and a densty-of-states model for electronic structure have been used to calculate thermodynamic functions for gaseous ThO, ThO/sub 2/, UO, UO/sub 2/, UO/sub 3/, PuO, and PuO/sub 2/. Various methods for estimating parameters have been considered and numerically evaluated. The sensitivity of the calculated thermodynamic functions to molecular parameters has been examined quantitatively. New values of the standard enthalpies of formation at 298.15/sup 0/K have been derived from the best available ..delta..G/sup 0//sub f/ equations and the calculated thermodynamic functions. Estimates of the uncertainties have been made for measured and estimated data as well as for various mathematical and physical approximations. Tables of the thermodynamic functions to 6000/sup 0/K are recommended for gaseous thorium, uranium, and plutonium oxides.
Density functional theory study of the thermodynamic and elastic properties of Ni-based superalloys.
Wu, Xiaoxia; Wang, Chongyu
2015-07-29
The thermophysical properties of Ni-based single-crystal superalloys were investigated using first-principles calculations combined with the quasiharmonic approximation. The effect of alloying elements X (X = Re, Ru, Ta, W, Mo, Cr, and Co) on the thermophysical properties of the ?-Ni and ?'-Ni3Al phases was investigated. The calculations showed that alloying can effectively adjust the lattice misfit between the two phases, and Cr can suppress lattice misfit and may improve the creep resistance of alloys. At 0?K, doping with refractory elements leads to tetragonal shear softening of the ?-Ni phase. For ?-Ni, Re, Ru, Cr, and Co slightly increase c44, while Mo, W, and Ta decrease c44. Importantly, high-temperature relative hardening was found to occur close to the service temperature of the superalloy, at which Ru and Cr increase c' and Mo and W increase c44 of ?-Ni. For the ?'-Ni3Al phase, all of the alloying elements except Co considerably increase c' and c44. Re and W at the Al site were found to most effectively harden the ?'-Ni3Al phase. The thermophysical and elastic properties were fully understood by analysis of the electronic structures and phonon spectra. It was found that the electronic density of states (DOS) can account for elastic hardening due to alloying. The phonon spectra along with electronic DOS analysis showed that alloying not only strengthens the first nearest neighbor Ni-X bond through additional d-d hybridization, but it is also important for stiffening the second nearest neighbor Al-X bonding through p-band filling. PMID:26139707
Thermodynamic properties of alloys of the Co-Sc and Co-Y systems
NASA Astrophysics Data System (ADS)
Shevchenko, M. A.; Ivanov, M. I.; Berezutski, V. V.; Kudin, V. G.; Sudavtsova, V. S.
2015-06-01
The thermochemical properties of melts of the Co-Sc(Y) systems were studied by the calorimetry method at 1873 K over the wide concentration intervals. It was shown that moderate negative heat effects of mixing are characteristic for these melts. Using the ideal associated solution (IAS) model, the activities of components, mixing Gibbs energies and entropies in the alloys of these systems, and their phase diagrams were calculated, and they agree well with the data from literature and undergo the general dependences for the Fe(Co, Ni, Cu)- d-metal systems.
NASA Astrophysics Data System (ADS)
Akasaka, Ryo; Kayukawa, Yohei; Tanaka, Katsuyuki; Higashi, Yukihiro
A comprehensive review is presented for the study on the thermodynamic properties of R 1234yf (2,3,3,3- tetrafluoropropene) and R 1234ze(E) (trans-1,3,3,3-tetrafluoropropene), which are considered as a possible replacement for conventional refrigerants with far from negligible global warming potential. Available experimental data for the critical parameters, vapor pressures, liquid/vapor densities, heat capacities, and speeds of sound are compiled, and reliability of each data is evaluated. A brief summary is also given for equations of state developed for these refrigerants, including comparison of deviations from experimental values and valid ranges of each equation of state. Recommended equations are selected which can be applied to refrigeration system analysis.
Fei, Weibin [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States)] [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States); Kara, Abdelkader [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States)] [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States); Rahman, Talat S. [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States)] [Cardwell Hall, Department of Physics, Kansas State University, Manhattan, Kansas 66502 (United States)
2000-06-15
In a comparative study of the local and excess thermodynamic properties of ordered (100), (110), and (111) surfaces of Cu{sub 3}Au using interaction potentials from the embedded atom method, and a real space Green's function method for the calculation of the local vibrational density of states, we find surface effects to be most pronounced on (110). The enhancement of the low frequency modes resulting from the softening of intralayer force constants causes a remarkable lowering of the vibrational free energy on (110). On Cu{sub 3}Au(100) the stiffening of interlayer force constants leads to the appearance of modes above the bulk band that reduce the effect of the enhancement of low frequency modes. Atoms on all three surfaces display characteristics that are distinct from those in the bulk. (c) 2000 The American Physical Society.
Proscia, W.M.; Freihaut, J.D.
1994-03-01
The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. The coal ranks to be investigated will include a high volatile A bituminous (PSOC 1451D) and a low volatile bituminous (PSOC 1516D). An anthracite (PSOC 1468) will be used as a non-volatile coal reference. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars.
Proscia, W M; Freihaut, J D
1993-12-01
The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. The coal ranks to be investigated will include a high volatile A bituminous (PSOC 1451D) and a low volatile bituminous (PSOC 1516D). An anthracite (PSOC 1468) will be used as a non-volatile coal reference. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Partial results on some of the tasks are given.
NASA Astrophysics Data System (ADS)
Lu, Yan; Wei, Guanghong; Derreumaux, Philippe
2012-07-01
Characterizing the early formed oligomeric intermediates of amyloid peptides is of particular interest due to their links with neurodegenerative diseases. Here we study the NNQQ peptide, known to display parallel ?-strands in amyloid fibrils by x-ray microcrystallography, and investigate the structural, thermodynamical, and dynamical properties of 20 NNQQ peptides using molecular dynamics and replica exchange molecular dynamics simulations coupled to a coarse-grained force field. All simulations are initiated from randomized and fully dispersed monomeric conformations. Our simulations reveal that the phase transition is characterized by a change in the oligomer and ?-sheet size distributions and the percentage of mixed parallel/antiparallel ?-strands when the sheets are formed. At all temperatures, however, the fraction of parallel ?-strands remains low, though there are many association/fragmentation events. This work and a growing body of computational studies provide strong evidence that the critical nucleus goes beyond 20 chains and reordering of the ?-strands occurs in larger oligomers.
Duan, Yuhua; Luebke, David; Pennline, Henry; Li, Liyu; King, David; Zhang; Keling; Zhao; Lifeng; Xiao, Yunhan
2012-01-01
It is generally accepted that current technologies for capturing CO{sub 2} are still too energy intensive. Hence, there is a critical need for development of new materials that can capture CO{sub 2} reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO{sub 2} capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO{sub 2} sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO{sub 2} adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO{sub 2} capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. These CO{sub 2} sorbent candidates were further considered for experimental validations. In this presentation, we first introduce our screening methodology with validating by solid dataset of alkali and alkaline metal oxides, hydroxides and bicarbonates which thermodynamic properties are available. Then, by studying a series of lithium silicates, we found that by increasing the Li{sub 2}O/SiO{sub 2} ratio in the lithium silicates their corresponding turnover temperatures for CO{sub 2} capture reactions can be increased. Compared to anhydrous K{sub 2}CO{sub 3}, the dehydrated K{sub 2}CO{sub 3}?1.5H{sub 2}O can only be applied for post-combustion CO{sub 2} capture technology at temperatures lower than its phase transition (to anhydrous phase) temperature, which depends on the CO{sub 2} pressure and the steam pressure with the best range being PH{sub 2}O?1.0 bar. Above the phase-transition temperature, the sorbent will be regenerated into anhydrous K{sub 2}CO{sub 3}. Our theoretical investigations on Na-promoted MgO sorbents revealed that the sorption process takes place through formation of the Na{sub 2}Mg(CO{sub 3}){sub 2} double carbonate with better reaction kinetics over porous MgO, that of pure MgO sorbent. The experimental sorption tests also indicated that the Na-promoted MgO sorbent has high reactivity and capacity towards CO{sub 2} sorption and can be easily regenerated either through pressure or temperature swing processes.
Galan, Brandon R.; Wiedner, Eric S.; Helm, Monte L.; Linehan, John C.; Appel, Aaron M.
2014-05-12
Nickel(II) complexes containing chelating N-heterocyclic carbene-phosphine ligands ([NiL2](BPh4)2, for which L = [MeIm(CH2)2PR2]) have been synthesized for the purpose of studying how this class of ligand effects the electrochemical properties compared to the nickel bis- diphosphine analogues. The nickel complexes were synthesized and characterized by x-ray crystallography and electrochemical methods. Based on the half wave potentials (E1/2), substitution of an NHC for one of the phosphines in a diphoshine ligand results in shifts in potential to 0.6 V to 1.2 V more negative than the corresponding nickel bis-diphosphine complexes. These quantitative results highlight the substantial effect that NHC ligands can have upon the electronic properties of the metal complexes. BRG, JCL, and AMA acknowledge the support by the US Department of Energy Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. MLH acknoledges the support of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.
1989-01-01
Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.
Proscia, W.M.; Freihaut, J.D.
1993-07-01
Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is required both, for the fundamental determination of kinetic parameters of coal devolatilization, and to refine existing devolatilization sub-models used in comprehensive coal combustion codes. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Morphological characterization of the parent coal samples has been completed by the University of Pittsburgh. Results are presented for true density, CO{sub 2} surface area, mercury porosimetry, and particle size and shape measurements using image analysis. The heat of thermal decomposition of PSOC 1451D (Task 5) will be calculated from the data reported here. The Task 10 effort, Morphological Characterization of Coal/Char Samples as a Function of Extent of Devolatilization, will continue at the University of Pittsburgh. Work will focus on measurement of the morphological characteristics of the char samples as a function of extent of reaction.
NASA Astrophysics Data System (ADS)
Suarez Negreira, Ana; Vandenberghe, William G.; Fischetti, Massimo V.
2015-06-01
Using density-functional theory (DFT), we study the growth of pristine and functionalized tin monolayers (Sn-MLs) on three different substrates, CdTe, InSb, and Si(111), and the impact these substrates have on the topological insulating properties of the electronic band structure. The presence of the substrate leads to strain and electronic charge transfer, which cause significant changes in the stability and electronic properties of the supported Sn-ML. Growth of pristine Sn-MLs on Si(111) leads to metallic behavior resembling that of the high-buckled Sn-ML phase; pristine Sn-MLs grown on InSb do not maintain a gap throughout the entire Brillouin zone; and pristine Sn-MLs grown on CdTe are unlikely to exhibit an experimentally observable gap. Provided the charge transfer from the substrate can be compensated, halogen-functionalized Sn-MLs grown on CdTe and InSb are topological insulators, albeit with a reduced band gap compared to their free-standing counterparts (from 0.34 eV for Sn-ML-I to 0.17 eV for InSb-Sn-ML-I). We employ ab initio thermodynamics calculations to study the thermodynamic stability of the halogenated InSb-Sn-MLs and CdTe-Sn-MLs surfaces for a temperature range of 100-1000 K under two extreme environments: ultrahigh vacuum (used in most of the laboratory characterization techniques) and rich-halogen conditions (10% vol. halogen environment). Our results indicate that it is possible to obtain stable topologically insulating Sn-MLs grown epitaxially on lattice-matched substrates.
Djamali, Essmaiil; Kan, Amy T; Tomson, Mason B
2012-08-01
The unified theory of electrolytes (J. Phys. Chem. B 2009, 113, 2398-2404) for predicting the standard state thermodynamic properties of aqueous electrolytes has been extended to include mixed solvent systems. The solubility of solid sodium chloride in mixed solvents (methanol/water concentration up to 75% w/w) was also measured up to 466 K and pressures near 7 MPa. The present model, together with a simple modification of Pitzer's thermodynamic treatment of aqueous solutions, allows a priori prediction of solubility of electrolytes in aqueous/organic systems to extreme temperatures and pressures. Solubility is predicted for sodium chloride and potassium chloride in mixed solvents (methanol/water, ethanol/water) over a wide range of temperatures and compositions from the extension of the unified theory of electrolytes to mixed solvents. Comparisons indicate good agreement in all cases to well within the uncertainties of the experimental data. The stoichiometric activity coefficients of saturated solution of sodium chloride in methanol/water mixed solvents were calculated up to 473.15 K. The stoichiometric activity coefficients, as a function of temperature at all concentrations (0 ? m ? m(sat)) and the entire range of mole fraction of methanol, were also calculated up to 473.15 K. The novelty of the present approach is that no additional parameters are required to account for the medium effect. PMID:22747332
Analysis of elevated temperature data for thermodynamic properties of selected radionuclides
Wruck, D.A.; Palmer, C.E.A.
1997-08-01
This report is a review of chemical thermodynamic data for Ni, Zr, Tc, U, Np, Pu and Am in aqueous solutions at elevated temperatures. Thermodynamic data for aqueous reactions over the temperature range 20-150{degrees}C are needed for geochemical modeling studies of the Yucca Mountain Project. The present review is focused on the aqueous complexes relevant to expected conditions in the Yucca Mountain region: primarily the hydroxide, carbonate, sulfate and fluoride complexes with the metal ions. Existing thermodynamic data are evaluated, and means of extrapolating 25{degrees}C data to the temperatures of interest are discussed. There will be a separate review of solubility data for relevant Ni, Zr, Tc, Np, Pu and Am compounds.
NASA Astrophysics Data System (ADS)
Hieu, Ho Khac; Hung, Vu Van
Using the statistical moment method (SMM), the temperature and pressure dependences of thermodynamic quantities of zinc-blende-type semiconductors have been investigated. The analytical expressions of the nearest-neighbor distances, the change of volumes and the mean-square atomic displacements (MSDs) have been derived. Numerical calculations have been performed for a series of zinc-blende-type semiconductors: GaAs, GaP, GaSb, InAs, InP and InSb. The agreement between our calculations and both earlier other theoretical results and experimental data is a support for our new theory in investigating the temperature and pressure dependences of thermodynamic quantities of semiconductors.
Karnan, M; Balachandran, V; Murugan, M; Murali, M K
2014-09-15
The solid phase FT-IR and FT-Raman spectra of 1-methyl-2-phenyl benzimidazole (MPBZ) have been recorded in the condensed state. In this work, experimental and theoretical study on the molecular structure, quantum chemical calculations of energies and vibrational wavenumbers of MPBZ is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311+G(d,p) and 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 4000-400 cm(-1) and with Fourier transform Raman spectrum in the region of 4000-100 cm(-1). Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential (MEP) surfaces, polarizability, Mulliken charges and thermodynamic properties of the title compound. PMID:24785089
NASA Astrophysics Data System (ADS)
Karnan, M.; Balachandran, V.; Murugan, M.; Murali, M. K.
2014-09-01
The solid phase FT-IR and FT-Raman spectra of 1-methyl-2-phenyl benzimidazole (MPBZ) have been recorded in the condensed state. In this work, experimental and theoretical study on the molecular structure, quantum chemical calculations of energies and vibrational wavenumbers of MPBZ is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311+G(d,p) and 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 4000-400 cm-1 and with Fourier transform Raman spectrum in the region of 4000-100 cm-1. Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential (MEP) surfaces, polarizability, Mulliken charges and thermodynamic properties of the title compound.
NASA Astrophysics Data System (ADS)
Almasi, Mohammad
2014-11-01
Densities and viscosities for binary mixtures of Diethanolamine (DEA) + 2 alkanol (2 propanol up to 2 pentanol) were measured over the entire composition range and temperature interval of 293.15-323.15 K. From the density and viscosity data, values of various properties such as isobaric thermal expansibility, excess isobaric thermal expansibility, partial molar volumes, excess molar volumes and viscosity deviations were calculated. The observed variations of these parameters, with alkanols chain length and temperature, are discussed in terms of the intermolecular interactions between the unlike molecules of the binary mixtures. The ability of the perturbed chain statistical associating fluid theory (PC-SAFT) to correlate accurately the volumetric behavior of the binary mixtures is demonstrated.
Correlation corrections to the thermodynamic properties of spin asymmetric QGP matter
Kausik Pal
2015-02-06
We calculate the free energy, entropy and pressure of the Quark Gluon Plasma (QGP) at finite temperature and density with a given fraction of spin-up and spin-down quarks using a MIT bag model with corrections up to ${\\cal O} (g^4 \\ln g^2)$. The expressions for the specific heat and the spin susceptibility are derived in terms of Fermi momentum and temperature. The effects of interaction between the quarks on the properties of the QGP phase are also investigated. Within our phenomenological model, we estimate the transition temperature $T_c$ by constructing the phase boundary between the hadronic phase and the QGP phase. Finally, we compute the equation of state of the QGP and its dependence on the temperature and the density.
Correlation corrections to the thermodynamic properties of spin-asymmetric QGP matter
NASA Astrophysics Data System (ADS)
Pal, Kausik
2015-02-01
We calculate the free energy, entropy and pressure of the Quark Gluon Plasma (QGP) at finite temperature and density with a given fraction of spin-up and spin-down quarks using a MIT bag model with corrections up to . The expressions for the specific heat and the spin susceptibility are derived in terms of Fermi momentum and temperature. The effects of the interaction between the quarks on the properties of the QGP phase are also investigated. Within our phenomenological model, we estimate the transition temperature T c by constructing the phase boundary between the hadronic phase and the QGP phase. Finally, we compute the equation of state of the QGP and its dependence on the temperature and the density.
Landscape Excitation Profiles and Excess Thermodynamic Properties of Disaccharide Aqueous Solutions
S. Magazù; C. Mondelli; G. Romeo
2006-01-01
We will consider the use of the bond model in characterizing, by the direct calculation route, the full excitation profile. The present work sets the temperature behaviour of the excessive value of some thermodynamic quantities, such as configurational entropy and heat capacity of two homologous disaccharide aqueous solutions. The findings represent important data for understanding the better lyoprotectant effectiveness of
Florentina Pena; Bogdan Amuzescu; Emil Neaga; Maria-Luiza Flonta
2006-01-01
Ih is a poorly selective cation current that activates upon hyperpolarization, present in various types of neurons. Our aim was to perform a detailed thermodynamic analysis of Ih gating kinetics, in order to assess putative structural changes associated with its activation and deactivation. To select dorsal root ganglia neurons that exhibit large Ih, we applied a current signature method by
Ionization equilibrium and thermodynamic and transport properties of a non-ideal hydrogen plasma
T. S. Ramazanov; K. N. Dzhumagulova
2001-01-01
The composition of a non-ideal plasma and the thermodynamic functions and conductivity of the system are calculated using the minimum Gibbs free energy method. Interactions of charged particles are described by a pseudopotential model that takes into account collective phenomena (high-order correlation effects) in the plasma.
Thermodynamic bounds and general properties of optimal efficiency and power in linear responses.
Jiang, Jian-Hua
2014-10-01
We study the optimal exergy efficiency and power for thermodynamic systems with an Onsager-type "current-force" relationship describing the linear response to external influences. We derive, in analytic forms, the maximum efficiency and optimal efficiency for maximum power for a thermodynamic machine described by a N×N symmetric Onsager matrix with arbitrary integer N. The figure of merit is expressed in terms of the largest eigenvalue of the "coupling matrix" which is solely determined by the Onsager matrix. Some simple but general relationships between the power and efficiency at the conditions for (i) maximum efficiency and (ii) optimal efficiency for maximum power are obtained. We show how the second law of thermodynamics bounds the optimal efficiency and the Onsager matrix and relate those bounds together. The maximum power theorem (Jacobi's Law) is generalized to all thermodynamic machines with a symmetric Onsager matrix in the linear-response regime. We also discuss systems with an asymmetric Onsager matrix (such as systems under magnetic field) for a particular situation and we show that the reversible limit of efficiency can be reached at finite output power. Cooperative effects are found to improve the figure of merit significantly in systems with multiply cross-correlated responses. Application to example systems demonstrates that the theory is helpful in guiding the search for high performance materials and structures in energy researches. PMID:25375457
Thermodynamic bounds and general properties of optimal efficiency and power in linear responses
NASA Astrophysics Data System (ADS)
Jiang, Jian-Hua
2014-10-01
We study the optimal exergy efficiency and power for thermodynamic systems with an Onsager-type "current-force" relationship describing the linear response to external influences. We derive, in analytic forms, the maximum efficiency and optimal efficiency for maximum power for a thermodynamic machine described by a N ×N symmetric Onsager matrix with arbitrary integer N. The figure of merit is expressed in terms of the largest eigenvalue of the "coupling matrix" which is solely determined by the Onsager matrix. Some simple but general relationships between the power and efficiency at the conditions for (i) maximum efficiency and (ii) optimal efficiency for maximum power are obtained. We show how the second law of thermodynamics bounds the optimal efficiency and the Onsager matrix and relate those bounds together. The maximum power theorem (Jacobi's Law) is generalized to all thermodynamic machines with a symmetric Onsager matrix in the linear-response regime. We also discuss systems with an asymmetric Onsager matrix (such as systems under magnetic field) for a particular situation and we show that the reversible limit of efficiency can be reached at finite output power. Cooperative effects are found to improve the figure of merit significantly in systems with multiply cross-correlated responses. Application to example systems demonstrates that the theory is helpful in guiding the search for high performance materials and structures in energy researches.
Thermodynamic properties of citric acid and the system citric acid-water
C. G. de Kruif; J. C. van Miltenburg; A. J. J. Sprenkels; G. Stevens; W. de Graaf; H. G. M. de Wit
1982-01-01
The binary system citric acid-water has been investigated with static vapour pressure measurements, adiabatic calorimetry, solution calorimetry, solubility measurements and powder X-ray measurements. The data are correlated by thermodynamics and a large part of the phase diagram is given. Molar heat capacities of citric acid are given from 90 to 330 K and for citric acid monohydrate from 120 to
Conformational and thermodynamic properties of peptide binding to the human S100P protein.
Gribenko, Alexey V; Guzmán-Casado, Mercedes; Lopez, Maria M; Makhatadze, George I
2002-06-01
S100P is a member of the S100 subfamily of calcium-binding proteins that are believed to be associated with various diseases, and in particular deregulation of S100P expression has been documented for prostate and breast cancer. Previously, we characterized the effects of metal binding on the conformational properties of S100P and proposed that S100P could function as a Ca2+ conformational switch. In this study we used fluorescence and CD spectroscopies and isothermal titration calorimetry to characterize the target-recognition properties of S100P using a model peptide, melittin. Based on these experimental data we show that S100P and melittin can interact in a Ca2+-dependent and -independent manner. Ca2+-independent binding occurs with low affinity (Kd approximately 0.2 mM), has a stoichiometry of four melittin molecules per S100P dimer and is presumably driven by favorable electrostatic interactions between the acidic protein and the basic peptide. In contrast, Ca2+-dependent binding of melittin to S100P occurs with high affinity (Kd approximately 5 microM) has a stoichiometry of two molecules of melittin per S100P dimer, appears to have positive cooperativity, and is driven by hydrophobic interactions. Furthermore, Ca2+-dependent S100P-melittin complex formation is accompanied by significant conformational changes: Melittin, otherwise unstructured in solution, adopts a helical conformation upon interaction with Ca2+-S100P. These results support a model for the Ca2+-dependent conformational switch in S100P for functional target recognition. PMID:12021435
First principle study of elastic and thermodynamic properties of FeB{sub 4} under high pressure
Zhang, Xinyu, E-mail: xyzhang@ysu.edu.cn, E-mail: jiaqianqin@gmail.com, E-mail: riping@ysu.edu.cn; Ning, Jinliang; Sun, Xiaowei; Li, Xinting; Ma, Mingzhen; Liu, Riping, E-mail: xyzhang@ysu.edu.cn, E-mail: jiaqianqin@gmail.com, E-mail: riping@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Qin, Jiaqian, E-mail: xyzhang@ysu.edu.cn, E-mail: jiaqianqin@gmail.com, E-mail: riping@ysu.edu.cn [Metallurgy and Materials Science Research Institute, Chulalongkorn University, Bangkok 10330 (Thailand); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)
2013-11-14
The elastic properties, elastic anisotropy, and thermodynamic properties of the lately synthesized orthorhombic FeB{sub 4} at high pressures are investigated using first-principles density functional calculations. The calculated equilibrium parameters are in good agreement with the available experimental and theoretical data. The obtained normalized volume dependence of high pressure is consistent with the previous experimental data investigated using high-pressure synchrotron x-ray diffraction. The complete elastic tensors and crystal anisotropies of the FeB{sub 4} are also determined in the pressure range of 0–100?GPa. By the elastic stability criteria and vibrational frequencies, it is predicted that the orthorhombic FeB{sub 4} is stable up to 100 GPa. In addition, the calculated B/G ratio reveals that FeB{sub 4} possesses brittle nature in the range of pressure from 0 to 100?GPa. The calculated elastic anisotropic factors suggest that FeB{sub 4} is elastically anisotropic. By using quasi-harmonic Debye model, the compressibility, bulk modulus, the coefficient of thermal expansion, the heat capacity, and the Grüneisen parameter of FeB{sub 4} are successfully obtained in the present work.
NASA Astrophysics Data System (ADS)
Huang, Liang Feng; Ni, Mei Yan; Zhang, Guo Ren; Zhou, Wang Huai; Li, Yong Gang; Zheng, Xiao Hong; Zeng, Zhi
2011-08-01
The thermodynamic, kinetic, and magnetic properties of the hydrogen monomer on doped graphene layers were studied by ab initio simulations. Electron doping heightens the diffusion potential barrier, while hole doping lowers it. However, both kinds of dopings heighten the desorption potential barrier. The underlying mechanism was revealed by investigating the effect of charge doping on the bond strength of graphene and on the electron transfer and the coulomb interaction between the hydrogen monomer and graphene. The kinetic properties of H and D monomers on doped graphene layers during both the annealing process (annealing time t0 = 300 s) and the constant-rate heating process (heating rate ? = 1.0 K/s) were simulated. Macroscopic diffusion of hydrogen monomers on graphene can be achieved when the doping-hole density reaches 5.0 × 1013 cm-2. Both electron and hole dopings linearly reduce the total magnetic moment and exchange splitting, which was explained by a simple exchange model. The laws found in this work had been generalized to explain many phenomena reported in literature. This study can further enhance the understanding of the interaction between hydrogen and graphene and was expected to be helpful in the design of hydrogenated-graphene-based devices.
Zhou, C L; Fang, D Q; Zhang, G Q
2013-01-01
Thermodynamic and transport properties of nuclear fireball created in the central region of heavy-ion collisions below 200 MeV/nucleon are investigated within the isospin-dependent quantum molecular dynamic (IQMD) model. These properties include time evolutions of the density, temperature, chemical potential, entropy density ($s$) and shear viscosity ($\\eta$) as well as density and temperature dependencies of the ratio of shear viscosity over entropy density ($\\eta/s$) etc. Based on the shear viscosity parametrization developed by Danilewicz and entropy density which is obtained by a generalized hot Thomas Fermi formalism, the ratio of shear viscosity over entropy density is calculated in the whole collision process as well as in the freeze-out stage. With the collision goes on, a transient minimal $\\eta/s$ with the value around 5/$4\\pi$ occurs in the largest compression stage. While, the relationship of $\\eta/s$ to tempertaure ($T$) in the freeze-out stage displays a local minimum which is about 9-10 times $...
NASA Technical Reports Server (NTRS)
Venkateswaran, S.; Hunt, L. Roane; Prabhu, Ramadas K.
1992-01-01
The Langley 8 foot high temperature tunnel (8 ft HTT) is used to test components of hypersonic vehicles for aerothermal loads definition and structural component verification. The test medium of the 8 ft HTT is obtained by burning a mixture of methane and air under high pressure; the combustion products are expanded through an axisymmetric conical contoured nozzle to simulate atmospheric flight at Mach 7. This facility was modified to raise the oxygen content of the test medium to match that of air and to include Mach 4 and Mach 5 capabilities. These modifications will facilitate the testing of hypersonic air breathing propulsion systems for a wide range of flight conditions. A computational method to predict the thermodynamic, transport, and flow properties of the equilibrium chemically reacting oxygen enriched methane-air combustion products was implemented in a computer code. This code calculates the fuel, air, and oxygen mass flow rates and test section flow properties for Mach 7, 5, and 4 nozzle configurations for given combustor and mixer conditions. Salient features of the 8 ft HTT are described, and some of the predicted tunnel operational characteristics are presented in the carpet plots to assist users in preparing test plans.
Z.-S. Liu; M. Divis; V. Sechovský
2010-01-01
We report our theoretical studies on the magnetic and thermodynamic properties of DyFe2Si2 using the crystal-field parameters (CFPs) proposed by Chatterji et al. recently [1]. Our calculated magnetization and magnetic specific heat curves obtained with the above CFPs based on the two-ion model we developed recently show reasonable agreement with the experimental data.
R. C. Hendricks; A. K. Baron; I. C. Peller
1975-01-01
A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple
NASA Astrophysics Data System (ADS)
Duong, Thien; Gibbons, Sean; Kinra, Rajeev; Arróyave, Raymundo
2011-11-01
In this work, the electronic, structural, elastic, and thermodynamic properties of Ti2AX MAX phases (A = Al or Ga, X = C or N) were investigated using density functional theory (DFT). It is shown that the calculations of the electronic, structural, and elastic properties of these structures, using local density approximation (LDA) and generalized gradient approximation (GGA) coupled with projected augmented-wave (PAW) pseudopotentials, agree well with experiments. A thermodynamic model, which considers the vibrational and electronic contributions to the total free energy of the system, was used to investigate the finite-temperature thermodynamic properties of Ti2AX. The vibrational contribution was calculated using the supercell method, whereas the electronic contribution resulted from one-dimensional integration of electronic density of states (DOSs). To verify the model, the specific heats of pure elements were calculated and compared to experimental data. The DFT-D2 technique was used to calculate the heat capacity of graphite, taking into account the van der Waals (vdW) effect. Good agreement between the calculations and experiments for the specific heats of graphite and other pure elements lends validity to the approach used. The calculated results for the specific heats of Ti2AlC and Ti2AlN match well with experimental data. These strengthen the results of specific heats of Ti2GaC and Ti2GaN as well as other calculated thermodynamic properties, including the energies of formation and thermal expansion coefficient.
Zhi-Chang Wang; Lin-Shan Wang [Northeastern Univ., Liaoning (China)
1997-04-09
The rare earth element complexes have never been analyzed in the gaseous state due to experimental concerns. The thermodynamic properties of rare earth element complexes are important for various applications, from high-intensity discharge lamps to recovery of rare earth metals. 46 refs., 4 figs., 1 tab.
Johnson R. Haas; Everett L. Shock; David C. Sassani
1995-01-01
Standard partial molal thermodynamic properties including association constants for 246 inorganic aqueous rare earth element (REE) complexes with chloride, fluoride, hydroxide, carbonate, sulfate, bicarbonate, nitrate, and orthophosphate can be calculated at pressures from 1 to 5000 bars and temperatures from 0 to 1000°C, using experimental data from the literature and correlation algorithms. Predicted association constants for REE complexes are used
within- cloud variability. Ignoring subgrid variability can lead to errors when computing the rate be parameterized in numerical models and used, for instance, to compute cloud fraction. Since a pdf is completelyVARIABILITY OF THERMODYNAMIC PROPERTIES OF CLOUDS Vincent E. Larson 1, Robert Wood2, Paul R. Field2
M. P. Burgess; G. L. Fuller; A. H. Kaiser
1976-01-01
In 1921, the American Society of Mechanical Engineers began an effort to provide reliable and consistent tables of the thermodynamic properties of steam and water. In 1936, J.H. Keenan and F.G. Keyes published a set of steam tables that served as an accepted reference. These tables were revised in 1969 using the least squares technique on a computer to interpolate
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Ivanov, Yu. B.; Fortov, V. E.; Bonitz, M.; Levashov, P. R.
2013-03-01
Based on the quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for the calculation of thermodynamic properties and—closely related to the latter—a Wigner dynamics method for calculation of transport properties of the QGP are formulated. The QGP partition function is presented in the form of a color path integral with a new relativistic measure instead of the Gaussian one traditionally used in the Feynman-Wiener path integral. A procedure of sampling color variables according to the SU(3) group Haar measure is developed for integration over the color variable. It is shown that the PIMC method is able to reproduce the lattice QCD equation of state at zero baryon chemical potential at realistic model parameters (i.e., quasiparticle masses and coupling constant) and also yields valuable insight into the internal structure of the QGP. Our results indicate that the QGP reveals quantum liquidlike(rather than gaslike) properties up to the highest considered temperature of 525 MeV. The pair distribution functions clearly reflect the existence of gluon-gluon bound states, i.e., glueballs, at temperatures just above the phase transition, while mesonlike qq¯ bound states are not found. The calculated self-diffusion coefficient agrees well with some estimates of the heavy-quark diffusion constant available from recent lattice data and also with an analysis of heavy-quark quenching in experiments on ultrarelativistic heavy-ion collisions, however, appreciably exceeds other estimates. The lattice and heavy-quark-quenching results on the heavy-quark diffusion are still rather diverse. The obtained results for the shear viscosity are in the range of those deduced from an analysis of the experimental elliptic flow in ultrarelativistic heavy-ions collisions, i.e., in terms the viscosity-to-entropy ratio, 1/4???/S<2.5/4?, in the temperature range from 170 to 440 MeV.
Thermodynamic properties of the generalized Murnaghan equation of state of solids
A. Fernández Guillermet; Guillermet I
1995-01-01
In the Murnaghan approximation, an isothermal relation between pressure (P) and volume (V) for solids is derived from the assumption that the isothermal bulk modulus (B) is a linear function ofP. This paper presents a thermodynamic analysis of a generalized form of the equation, based on treating all its various parameters [viz., V, B, and (?B\\/?P)T atP=0] as functions of
Temperature dependence of thermodynamic properties for DNA\\/DNA and RNA\\/DNA duplex formation
Peng Wu; Shu-ichi Nakano; Naoki Sugimoto
2002-01-01
A clear difference in the enthalpy changes derived from spectroscopic and calorimetric measurements has recently been shown. The exact interpretation of this deviation varied from study to study, but it was generally attributed to the non-two-state transition and heat capacity change. Although the temperature-dependent thermodynamics of the duplex formation was often implied, systemic and extensive studies have been lacking in
Anca Filimon; Raluca Marinica Albu; Ecaterina Avram; Silvia Ioan
2012-01-01
Theoretical and experimental aspects of the association phenomena generated by hydrogen bonding, dispersive and electrostatic interactions in ternary systems consisting of a proton-donor solvent (N,N-dimethylformamide or methanol), a proton-acceptor solvent (water), and a proton-acceptor polymer (polysulfones with different alkyl side groups), are investigated. In this context, binary and ternary thermodynamic interaction parameters are corrected on the basis of the different
M. Arita; R. Kinaka; M. Someno
1979-01-01
A technique has been proposed for determining thermodynamic activities in a binary alloy from measurements of the pressure\\u000a of hydrogen gas equilibrated with the alloy and the hydride of one of the components. The technique is similar to a method\\u000a by equilibration of oxygen gas with an alloy and the oxide of a component. With the use of this technique,
Low-temperature transport, thermodynamic, and optical properties of FeSi
S. Paschen; E. Felder; M. A. Chernikov; L. Degiorgi; H. Schwer; H. R. Ott; D. P. Young; J. L. Sarrao; Z. Fisk
1997-01-01
We present a comprehensive series of electrical transport (conductivity, magnetoresistance, and Hall effect), thermodynamic (specific heat, magnetic susceptibility, and magnetization), and optical (reflectivity) measurements in varying temperature ranges between 0.05 and 330 K on high-quality FeSi single crystals grown by vapor transport. The entire set of data can consistently be described with the usual relations for a (compensated n type)
A Unified Fundamental Equation for the Thermodynamic Properties of H2O
Philip G. Hill
1990-01-01
A new unified equation of state for H2O is presented, which includes the revised and extended scaling equation of Levelt Sengers, Kamgar–Parsi, Balfour and Sengers, is continuous over all single phase states of H2O from triple point pressure and temperature to 1000 MPa (or the melting line) and 1000 °C and provides accurate representation of existing thermodynamic data in that
Properties of radiation near the black-hole horizon and the second law of thermodynamics
Li-Xin Li; Liao Liu
1992-01-01
By considering a gedanken experiment of adiabatically lowering a box containing matter with rest energy E and entropy S into a black hole, Bekenstein claimed that the necessary condition for the validity of the generalized second law of thermodynamics is S\\/E<=2piR, where R is the effective radius of the box. Unruh and Wald claimed that this condition is not necessary
Christophe Coquelet; Dominique Richon
2007-01-01
In 1987, the Montreal Protocol prohibited the worldwide use and production of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons\\u000a (HCFCs) and hydro fluorocarbons (HFCs) were proposed as alternative refrigerants. Unfortunately, HFCs have non negligible\\u000a global warning potential and therefore new refrigerants must be proposed or old refrigerants must be used associated with\\u000a HFC. Accurate experimental thermodynamic data and predictive techniques are required for
Thermodynamic Properties of Dioxygen Difluoride (O2F2) and Dioxygen Fluoride (O2F)
John L. Lyman
1989-01-01
Recent spectroscopic and chemical kinetic studies have provided sufficient data for construction of reliable thermodynamic tables for both dioxygen difluoride (O2F2; Chemical Abstracts Registry Number, 7783-44-0) and dioxygen fluoride (O2F; Chemical Abstracts Registry Number, 15499-23-7). This paper contains those tables for these species in both SI units (0.1 MPa standard state) and cal K mol units (1.0 atm standard state).
Critical evaluation and optimization of the thermodynamic properties of liquid tin solutions
Marie-Claude Heuzey; Arthur D. Pelton
1996-01-01
Thermodynamic and phase equilibrium data for the following 18 elements in molten Sn were collected and critically evaluated:\\u000a Al, Ca, Ce, Co, Cr, Cu, Fe, H, Mg, Mo, Na, Ni, O, P, S, Se, Si, and Ti. Binary and ternary data were optimized to give polynomial\\u000a expressions for the excess Gibbs energies as functions of temperature and composition. For some
Excessive thermodynamic properties of praseodymium in a gallium-indium alloy
NASA Astrophysics Data System (ADS)
Mel'chakov, S. Yu.; Yamshchikov, L. F.; Ivanov, V. A.; Volkovich, V. A.; Osipenko, A. G.; Kormilitsyn, M. V.; Nagovitsyn, V. A.
2013-08-01
The equilibrium potentials of praseodymium-diluted homogeneous Pr-Ga-In alloys in a (Li-K-Cs)Cleut-based salt electrolyte were measured between 573-1073 K by the emf method. These potentials are used to calculate the activity coefficients of ?-praseodymium in liquid Ga-In eutectic alloys. PrIn3 alloy with well-known thermodynamic characteristics and without phase transitions in the temperature range 428-1483 K was employed as the reference electrode.
A class of black holes in dRGT massive gravity and their thermodynamical properties
Ghosh, Sushant G; Wongjun, Pitayuth
2015-01-01
We present exact spherical black hole solutions in de Rham, Gabadadze and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and canonical ensembles (for charged case). It turns out that the dGRT black hole solutions includes the known solutions to the Einstein field equations, such as, the monopole-de Sitter-Schwarzschild ones with the coefficients for the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature, and entropy of dGRT black hole solutions and also perform thermodynamical stability. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which is also true for the obtained charged black holes. Interestingly, the entropy ...
Pairing Mechanism for the High-TC Superconductivity: Symmetries and Thermodynamic Properties
Szcz??niak, Rados?aw
2012-01-01
The pairing mechanism for the high- superconductors based on the electron-phonon (EPH) and electron-electron-phonon (EEPH) interactions has been presented. On the fold mean-field level, it has been proven, that the obtained s-wave model supplements the predictions based on the BCS van Hove scenario. In particular: (i) For strong EEPH coupling and the energy gap () is very weak temperature dependent; up to the critical temperature extends into the anomalous normal state to the Nernst temperature. (ii) The model explains well the experimental dependence of the ratio on doping for the reported superconductors in the terms of the few fundamental parameters. In the presented paper, the properties of the d-wave superconducting state in the two-dimensional system have been also studied. The obtained results, like for s-wave, have shown the energy gap amplitude crossover from the BCS to non-BCS behavior, as the value of the EEPH potential increases. However, for the energy gap amplitude extends into the anomalous normal state to the pseudogap temperature. Finally, it has been presented that the anisotropic model explains the dependence of the ratio on doping for the considered superconductors. PMID:22529891
NASA Astrophysics Data System (ADS)
Helgeson, Harold C.; Owens, Christine E.; Knox, Annette M.; Richard, Laurent
1998-03-01
Calculation of the thermodynamic properties of organic solids, liquids, and gases at high temperatures and pressures is a requisite for characterizing hydrothermal metastable equilibrium states involving these species and quantifying the chemical affinities of irreversible reactions of organic molecules in natural gas, crude oil, kerogen, and coal with minerals and organic, inorganic, and biomolecular aqueous species in interstitial waters in sedimentary basins. To facilitate calculations of this kind, coefficients for the Parameters From Group Contributions (PFGC) equation of state have been compiled for a variety of groups in organic liquids and gases. In addition, molecular weights, critical temperatures and pressures, densities at 25°C and 1 bar, transition, melting, and boiling temperatures ( Tt,Pr, Tm,Pr, and Tv,Pr, respectively) and standard molal enthalpies of transition (? H° t,Pr), melting (? H° m,Pr), and vaporization (? H° v,Pr) of organic species at 1 bar ( Pr) have been tabulated, together with an internally consistent and comprehensive set of standard molal Gibbs free energies and enthalpies of formation from the elements in their stable state at 298.15 K ( Tr) and Pr (? G° f and ? H° f, respectively). The critical compilation also includes standard molal entropies ( S°) and volumes ( V°) at Tr and Pr, and standard molal heat capacity power function coefficients to compute the standard molal thermodynamic properties of organic solids, liquids, and gases as a function of temperature at 1 bar. These properties and coefficients have been tabulated for more than 500 crystalline solids, liquids, and gases, and those for many more can be computed from the equations of state group additivity algorithms. The crystalline species correspond to normal alkanes (C nH 2( n+1) ) with carbon numbers ( n, which is equal to the number of moles of carbon atoms in one mole of the species) ranging from 5 to 100, and 23 amino acids including glycine (C 2H 5NO 2), alanine (C 3H 7NO 2), valine (C 5H 11NO 2), leucine (C 6H 13NO 2), isoleucine (C 6H 13NO 2), aspartic acid (C 4H 7NO 4), glutamic acid (C 5H 9NO 4), asparagine (C 4H 8N 2O 3), glutamine (C 5H 10N 2O 3), proline (C 5H 9NO 2), phenylalanine (C 9H 11NO 2), tryptophan (C 11H 12N 2O 2), methionine (C 5H 11SNO 2), serine (C 3H 7NO 3), threonine (C 4H 9NO 3), cysteine (C 3H 7SNO 2), tyrosine (C 9H 11NO 3), lysine (C 6H 14N 2O 2), lysine:HCl (C 6H 15N 2O 2Cl), arginine (C 6H 14N 4O 2), arginine:HCl (C 6H 15N 4O 2Cl), histidine (C 6H 9N 3O 2), and histidine:HCl (C 6H 10N 3O 2Cl). The data for the latter compounds permit calculation of the standard molal thermodynamic properties of protein unfolding in biogeochemical processes (Helgeson et al 1998). The liquids and gases considered in the present study include normal alkanes (C nH 2( n+1) ) for carbon numbers ranging from 1 to 100, 2- and 3-methylalkanes (C nH 2( n+1) ) for 4 ? n ? 20 and 6 ? n ? 20, respectively, 2,3-dimethylpentane (C 7H 16), 4-methylheptane (C 8H 18), cycloalkanes (C nH 2 n) for 3 ? n ? 8, methylated benzenes (C nH 2( n-3) ) for 7 ? n ? 12, normal alkylbenzenes (C nH 2( n-3) ) for 6 ? n ? 20, normal 1-alcohols (C nH 2( n+1) O) for 1 ? n ? 20, ethylene glycol (C 2H 6O 2), glycerol (C 3H 8O 3), normal 1-alkanethiols (C nH 2( n+1) S) for 1 ? n ? 20, normal carboxylic acids (C nH 2 nO 2) for 2 ? n ? 20, and the following miscellaneous species: 2-thiabutane (C 3H 8S), thiophene (C 4H 4S), thiophenol (C 6H 6S), acetone (C 3H 6O), 2-butanone (C 4H 8O), ethyl acetate (C 4H 8O 2), pyridine (C 5H 5N), 3-methylpyridine (C 6H 7N), and quinoline (C 9H 7N). One additional liquid (2-methylthiacyclopentane (C 5H 10S)) was also considered along with crystalline and gaseous carbazole (C 12H 9N). The thermodynamic data and equations summarized below can be used together with the standard molal thermodynamic properties of high molecular weight organic compounds ( Richard and Helgeson 1995, Richard and Helgeson 1998a, Richard and Helgeson 1998b) and minerals, inorganic gases, and aqueo
NASA Astrophysics Data System (ADS)
Hadi, M. A.; Ali, M. S.; Naqib, S. H.; Islam, A. K. M. A.
2013-06-01
First-principles investigation of the geometry, electronic band structure, Vickers hardness, thermodynamic and optical properties of three superconducting MAX compounds Nb2AsC, Nb2InC and Mo2GaC have been carried out by the plane-wave pseudopotential method based on density functional theory (DFT) implemented in the CASTEP code. The theoretical Vickers hardness has been studied by means of Mulliken bond population analysis and electronic densities of states. The thermodynamic properties such as the temperature and pressure dependent bulk modulus, Debye temperature, specific heats and thermal expansion coefficient of the three 211 MAX phases are derived from the quasi-harmonic Debye model with phononic effect for the first time. Furthermore, all the optical properties are determined and analyzed for the first time for two different polarization directions. The theoretical findings are compared with relevant experiments (where available) and the various implications are discussed in details.
Starling, K.E.; Lee, L.L.; Kumar, K.H.
1981-01-01
During the first half year of this research program the following elements of research have been performed: (1) the development of an improved pure component data bank, including collection and processing of data which is 70% complete as to substance, (2) calculation of distillable coal fluid thermodynamic properties using a multiparameter corresponding states correlation, (3) application of the most general density-cubic equation of pure fluids and (4) initiation of research to extend the corresponding states correlation framework to polar fluids. Primary conclusions of the first phase of this research program are that the three parameter corresponding states correlation predicts lighter coal fluid properties to a reasonable level of accuracy, and that a cubic equation can predict pure fluid thermodynamic properties on par with non-cubic equations of state.
NASA Astrophysics Data System (ADS)
Zhang, Xudong; Ying, Caihong; Li, Zhijie; Shi, Guimei
2012-09-01
A first-principles calculations, based on the norm-conserving pseudopotentials and the density functional theory (DFT) and the density functional perturbation theory (DFPT) as implemented in the ABINIT code, have been performed to investigate the structural stability, elastic, lattice dynamic and thermodynamic properties of the ordered SiGe, SiSn and GeSn cubic alloy in zinc-blende (B3) structure. The calculated lattice parameters and bulk modulus agree with the previous results. The second-order elastic constants have been calculated and other related quantities such as the Young's modulus, shear modulus, anisotropy factor are also estimated. We also obtain the data of lattice dynamics and the temperature dependent properties currently lacking for SiGe, SiSn and GeSn. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as the internal energy, Helmholtz free energy, entropy and heat capacity.
Thermodynamic properties of diosgenin determined by oxygen-bomb calorimetry and DSC
NASA Astrophysics Data System (ADS)
Zhao, Ming-Rui; Wang, Hong-Jie; Wang, Shu-Yu; Yue, Xiao-Xin
2014-12-01
The combustion enthalpy of diosgenin was determined by oxygen-bomb calorimetry. The standard mole combustion enthalpy and the standard mole formation enthalpy have been calculated to be -16098.68 and -528.52 kJ mol-1, respectively. Fusion enthalpy and melting temperature for diosgenin were also measured to be -34.43 kJ mol-1 and 212.33°C, respectively, according to differential scanning calorimetry (DSC) data. These studies can provide useful thermodynamic data for this compound.
Thermodynamic properties and transport coefficients of arc lamp plasmas: argon, krypton and xenon
NASA Astrophysics Data System (ADS)
Murphy, Anthony B.; Tam, Eugene
2014-07-01
Calculated values of the density, specific heat, enthalpy, viscosity, thermal conductivity and electrical conductivity of thermal plasmas formed from three gases used in arc lamps, krypton, argon and xenon, are presented. The calculations, which assume local thermodynamic equilibrium, were performed for pressures from 1 to 100 atm and for the temperature range 300-30?000 K. The results were compared with those of previously published studies. Some discrepancies were found for krypton and xenon; these are attributed to the improved values of the collision integrals used here in calculating the transport coefficients.
NASA Astrophysics Data System (ADS)
Szcz&?acute; niak, Rados?aw; Durajski, Artur P.
2013-11-01
The ab initio calculations suggest that the superconducting state in CaH6 under the pressure (p) at 150 GPa has the highest critical temperature among the examined hydrogen-rich compounds. For this reason, the relevant thermodynamic parameters of the superconducting state in CaH6 have been determined; a wide range of the Coulomb pseudopotential has been assumed: ???<0.1,0.3>. It has been found that: (i) The critical temperature (TC) changes in the range from 243 K to 180 K (ii) The values of the ratio of the energy gap to the critical temperature (R? ? 2?(0)/kBTC) can be found in the range from 5.42 to 5.02. (iii) The ratio of the specific heat jump (?C(TC)) to the value of the specific heat in the normal state (CN(TC)), which has been represented by the symbol RC, takes the values from 3.30 to 3.18. (iv) The ratio R?TC(T)/HC2(0), where HC(0) denotes the critical thermodynamic field, changes from 0.122 to 0.125. The above results mean that even for the strong electron depairing correlations the superconducting state in CaH6 is characterized by a very high value of TC, and the remaining thermodynamic parameters significantly deviate from the predictions of the BCS theory. The study has brought out the expressions that correctly predict the values of the thermodynamic parameters for the superconducting state in CaH6 and for the compounds: SiH4(H2)2, Si2H6, B2H6, SiH4, GeH4, and PtH. Next, in the whole family of the hydrogen-rich compounds, the possible ranges of the values have been determined for TC, R?, RC, and RH. It has been found that the maximum value of the critical temperature can be equal to 764 K, which very well correlates with TC for metallic hydrogen (p = 2 TPa). Other parameters (R?, RC, and RH) should not deviate from the predictions of the BCS theory more than the analogous parameters for CaH6.
Thermodynamic properties, melting temperature and viscosity of the mantles of Super Earths
NASA Astrophysics Data System (ADS)
Stamenkovic, V.; Spohn, T.; Breuer, D.
2010-12-01
The recent dicscovery of extrasolar planets with radii of about twice the Earth radius and masses of several Earth masses such as e.g., Corot-7b (approx 5Mearth and 1.6Rearth, Queloz et al. 2009) has increased the interest in the properties of rock at extremely high pressures. While the pressure at the Earth’s core-mantle boundary is about 135GPa, pressures at the base of the mantles of extraterrestrial rocky planets - if these are at all differentiated into mantles and cores - may reach Tera Pascals. Although the properties and the mineralogy of rock at extremely high pressure is little known there have been speculations about mantle convection, plate tectonics and dynamo action in these “Super-Earths”. We assume that the mantles of these planets can be thought of as consisting of perovskite but we discuss the effects of the post-perovskite transition and of MgO. We use the Keane equation of state and the Slater relation (see e.g., Stacey and Davies 2004) to derive an infinite pressure value for the Grüneisen parameter of 1.035. To derive this value we adopted the infinite pressure limit for K’ (pressure derivative of the bulk modulus) of 2.41 as derived by Stacey and Davies (2004) by fitting PREM. We further use the Lindeman law to calculate the melting curve. We gauge the melting curve using the available experimental data for pressures up to 120GPa. The melting temperature profile reaches 6000K at 135GPa and increases to temperatures between 12,000K and 24,000K at 1.1TPa with a preferred value of 21,000K. We find the adiabatic temperature increase to reach 2,500K at 135GPa and 5,400K at 1.1TPa. To calculate the pressure dependence of the viscosity we assume that the rheology is diffusion controlled and calculate the partial derivative with respect to pressure of the activation enthalpy. We cast the partial derivative in terms of an activation volume and use the semi-empirical homologous temperature scaling (e.g., Karato 2008). We find that the activation volume decreases from 2.4cm^3/mol at 135GPa to 1.6cm^3/mol at 1.1TPa. An estimate of the viscosity increase across the mantle to a pressure of 1.1TPa using the adiabat calculated above results in an increase of the viscosity of 19 orders of magnitude. This value raises questions about the differentiation of these planets, heat transfer in their deep interiors, and magnetic field generation.(Ref.: Karato, S. 2008. Deformation of Earth Materials, Cambridge University Press.; Stacey, F.D., Davies, P.M. 2004. PEPI 142: 137; Queloz, D. et al., 2009. Astronomy and Astrophysics 506: 303.)
Thermodynamic Properties Of Alkali Species In Coal Based Combined Cycle Power Systems
Willenborg, W.; Wolf, K.J.; Fricke, C.; Moeller, M.; Prikhodovsky, A.; Hilpert, K.; Singheiser, L.
2002-09-20
The aim of this project is to support the development of a concept for a successful alkali removal. Two strategies are possible: optimizing the alkali retention potential of the coal ash slag in the combustion chamber and the liquid slag separators and separate alkali removal with solid sorbents (getters) at temperatures below 1450 C. Therefore in a first step the alkali partial pressure over coal ash slag should be determined in order to get information about the retention potential of the slag. The influence of additives on the retention potential of the slag should be investigated. The measurements should show if the alkali partial pressure over the slag is generally low enough in case of thermodynamic equilibrium. In case of too high alkali partial pressures a separate alkali removal is needed. Therefore in a second step commercial sorbent materials should be investigated concerning their sorption potential for alkalis. To get information about the influence of getter components on the sorption potential some mixtures of pure components, predicted by thermodynamic modeling to be most effective, should be investigated.
A Thermodynamic Investigation of the Redox Properties of Ceria-Titania Mixed Oxides
Zhou,G.; Hanson, J.; Gorte, R.
2008-01-01
Ceria-titania solutions with compositions of Ce0.9Ti0.1O2 and Ce0.8Ti0.2O2 were prepared by the citric-acid (Pechini) method and characterized using X-ray diffraction (XRD) for structure, coulometric titration for redox thermodynamics, and water-gas-shift (WGS) reaction rates. Following calcination at 973 K, XRD suggests that the mixed oxides exist as single phase, fluorite structures, although there was no significant change in the lattice parameter compared to pure ceria. The mixed oxides are shown to be significantly more reducible than bulk ceria, with enthalpies for re-oxidation being approximately -500 kJ/mol O2, compared to -760 kJ/mol O2 for bulk ceria. However, WGS rates over 1 wt% Pd supported on ceria, Ce0.8Ti0.2O2, and Ce0.8Zr0.2O2 were nearly the same. For calcination at 1323 K, the mixed oxides separated into ceria and titania phases, as indicated by both the XRD and thermodynamic results.
A thermodynamic approach to model the caloric properties of semicrystalline polymers
NASA Astrophysics Data System (ADS)
Lion, Alexander; Johlitz, Michael
2015-02-01
It is well known that the crystallisation and melting behaviour of semicrystalline polymers depends in a pronounced manner on the temperature history. If the polymer is in the liquid state above the melting point, and the temperature is reduced to a level below the glass transition, the final degree of crystallinity, the amount of the rigid amorphous phase and the configurational state of the mobile amorphous phase strongly depend on the cooling rate. If the temperature is increased afterwards, the extents of cold crystallisation and melting are functions of the heating rate. Since crystalline and amorphous phases exhibit different densities, the specific volume depends also on the temperature history. In this article, a thermodynamically based phenomenological approach is developed which allows for the constitutive representation of these phenomena in the time domain. The degree of crystallinity and the configuration of the amorphous phase are represented by two internal state variables whose evolution equations are formulated under consideration of the second law of thermodynamics. The model for the specific Gibbs free energy takes the chemical potentials of the different phases and the mixture entropy into account. For simplification, it is assumed that the amount of the rigid amorphous phase is proportional to the degree of crystallinity. An essential outcome of the model is an equation in closed form for the equilibrium degree of crystallinity in dependence on pressure and temperature. Numerical simulations demonstrate that the process dependences of crystallisation and melting under consideration of the glass transition are represented.
Wereszczynski, Jeff; McCammon, J. Andrew
2012-01-01
Molecular recognition plays a central role in biochemical processes. Although well studied, understanding the mechanisms of recognition is inherently difficult due to the range of potential interactions, the molecular rearrangement associated with binding, and the time and length scales involved. Computational methods have the potential for not only complementing experiments that have been performed, but also in guiding future ones through their predictive abilities. In this review, we discuss how molecular dynamics (MD) simulations may be used in advancing our understanding of the thermodynamics that drive biomolecular recognition. We begin with a brief review of the statistical mechanics that form a basis for these methods. This is followed by a description of some of the most commonly used methods: thermodynamic pathways employing alchemical transformations and potential of mean force calculations, along with end-point calculations for free energy differences, and harmonic and quasi-harmonic analysis for entropic calculations. Finally, a few of the fundamental findings that have resulted from these methods are discussed, such as the role of configurational entropy and solvent in intermolecular interactions, along with selected results of the model system T4 lysozyme to illustrate potential and current limitations of these methods. PMID:22082669
NASA Astrophysics Data System (ADS)
Hozumi, Tsutomu; Sato, Haruki; Watanabe, Koichi
This paper proposes a procedure on the thermodynamically consistent determination of virial coefficients from speed-of-sound measurements. Using the speed-of-sound values for gaseous Difluoromethane (R-32) +Pentafluoroethane (R-125), R -32+ 1, 1, 1, 2 - tetrafluoroethane (R-134a), R125/134a and R-32/125/134a which have already been reported in the previous paper, the second virial coefficients of R-32/125, R -32/134a, R-125/134a and R-32/125/134a were determined by means of thermodynamic relation among the virial coefficients of two different virial equations of state with respect to pressure and density. The present virial equation of state regarding density expansion can represent not only the speed-of-sound values but also the P?T-data for R-32/125, R -32/134a, R -125/134a and R-32/125/134a. The deviation of the speed-of-sound data from the virial equation of state is about±100ppm.And the deviation of the P?T-measurements by Kleemiss and Tillner-Roth (1997) from the virial equation of state against density is about ±0.l%. The behavior of the second virial coefficient is shown at the available compositions.
Jutte, Lisa S.; Smith, Michael E.
2003-01-01
Objective: To compare surface cooling and deep cooling produced by 3 common forms of cryotherapy. Design and Setting: We used a 3 × 4 × 4 factorial with repeated measures on measurement depth and treatment. Independent variables were measurement depth (surface, fat + 1 cm, and fat + 2 cm), treatment (ice bag, Wet-Ice, Flex-i-Cold, and control), and treatment order (first, second, third, and fourth). The lowest temperature recorded was the dependent variable. The treatment order was counterbalanced using a Latin square. Data were analyzed with a repeated-measures analysis of variance. Subjects: Fifteen collegiate volunteers who were free of lower extremity abnormalities. Measurements: Thigh skin and thigh intramuscular temperatures (1- and 2-cm subadipose) were measured at 30-second intervals both before and during the 30-minute treatments using fine-wire implantable and surface thermocouples. The coldest recorded temperatures were analyzed. Results: Statistical differences were observed for the depth-by-treatment interaction as well as for the depth and treatment main effects. During cold treatments, superficial depths were colder than deeper depths, and all cold treatments were colder than controls at all depths. For the interaction effect at both the skin surface and at 1-cm subadipose, the ice-bag and Wet-Ice treatments were colder than the Flex-i-Cold treatment. For the interaction at 2-cm subadipose, the cold treatments did not differ from each other. Order of treatments did not produce a significant effect. Conclusions: During a 30-minute cryotherapy treatment, modalities that undergo a phase change caused lower skin and 1-cm intramuscular temperatures than cold modalities that do not possess these properties. These differences were not seen at 2-cm subadipose but may become apparent with longer treatments. PMID:12937469
Thermodynamic properties and neutron diffraction studies of silver ferrite AgFeO2
NASA Astrophysics Data System (ADS)
Vasiliev, A.; Volkova, O.; Presniakov, I.; Baranov, A.; Demazeau, G.; Broto, J.-M.; Millot, M.; Leps, N.; Klingeler, R.; Büchner, B.; Stone, M. B.; Zheludev, A.
2010-01-01
We present thermodynamic and neutron scattering data on silver ferrite AgFeO2. The data imply that strong magnetic frustration ?/TN~10 and magnetic ordering arise via two successive phase transitions at T2 = 7 K and T1 = 16 K. At T
Thermodynamic Properties of Dioxygen Difluoride (O2F2) and Dioxygen Fluoride (O2F)
NASA Astrophysics Data System (ADS)
Lyman, John L.
1989-04-01
Recent spectroscopic and chemical kinetic studies have provided sufficient data for construction of reliable thermodynamic tables for both dioxygen difluoride (O2F2; Chemical Abstracts Registry Number, 7783-44-0) and dioxygen fluoride (O2F; Chemical Abstracts Registry Number, 15499-23-7). This paper contains those tables for these species in both SI units (0.1 MPa standard state) and cal K mol units (1.0 atm standard state). The experimental basis includes three recent assignments of the fundamental vibrational frequencies for O2F2, a new set of rotational constants for O2F, an enthalpy change for dissociation of O2F, and an updated standard enthalpy of formation for O2F2.
Investigation of fundamental transport properties and thermodynamics in diglyme-salt solutions.
Petrowsky, Matt; Frech, Roger; Suarez, Sophia N; Jayakody, J R P; Greenbaum, Steven
2006-11-23
Ionic mobility, the thermodynamics of ionic association, and the structure of associated species are studied in solutions of diglyme containing either lithium triflate or tetrabutylammonium triflate. Infrared spectroscopic, PFG NMR, thermodynamic, and crystallographic data suggest that the solute species existing in diglyme-lithium triflate are "free" ions, contact ion pairs, and dimers. Equilibrium constants, S(o), deltaH(o), and deltaG(o) are calculated for processes occurring between these species. In particular, the equilibrium constant, corrected for nonideality using a modified Debye-Hückel expression, is calculated for the dissociation of contact ion pairs into "free" cations and anions. A second equilibrium constant for the formation of dimers from contact ion pairs is also calculated; these constants do not significantly vary with salt concentration up to about 1.3 x 10(-3) mol cm(-3). The measured temperature dependence of equilibrium constants was used to calculate deltaH(o) and deltaS(o) for the two processes. The value of deltaS(o) = -102 J mol(-1) K(-1) for the dissociation of contact ion pairs shows that the large entropy decrease due to cation solvation outweighs the entropy increase due to dissociation of a contact ion pair. Ionic mobilities are calculated in lithium triflate-diglyme solutions using conductivity data in conjunction with information about the nature and concentrations of solute species obtained from IR spectroscopy. Mobilities in tetrabutlyammonium triflate-diglyme solutions are calculated directly from conductivity data. It was concluded that the concentration dependence of the molar conductivity is due in large part to the variation of the ion mobilities with concentration. PMID:17107139
Peguin, Robson P S; Selvam, Parthiban; da Rocha, Sandro R P
2006-10-10
A combined computational and experimental approach is used to determine the interfacial thermodynamic and structural properties of the liquid 1,1,1,2-tetrafluoroethane (HFA134a)-vapor and liquid HFA134a-water (HFA134a|W) interfaces at 298 K and saturation pressure. Molecular dynamics (MD) computer simulations reveal a stable interface between HFA134a and water. The "10-90" interfacial thickness is comparable with those typically reported for organic-water systems. The interfacial tension of the HFA134a|W interface obtained from the pressure tensor analysis of the MD trajectory is in good agreement with the experimental value determined using in situ high-pressure tensiometry. These results indicate that the potential models utilized are capable of describing the intermolecular interactions between these two fluids. The tension of the HFA134a|W interface is significantly lower than those typically observed for conventional oil-water interfaces and similar to that of the compressed CO(2)-water interface, observed at moderate CO(2) pressures. The MD and tensiometric results are also compared and contrasted with the HFA134a|W and chlorofluorocarbon-water tension values estimated from a parametric relationship. This represents the first report of the interfacial and microscopic properties of the (propellant) hydrofluoroalkanes (HFA)|W interface. The results presented here are of relevance in the design of surfactants capable of forming and stabilizing water-in-HFA microemulsions. Reverse aqueous microemulsions in HFA-based pressurized metered-dose inhalers are candidate formulations for the systemic delivery of biomolecules to and through the lungs. PMID:17014124
Thermodynamic mixing properties and behavior of almandine-spessartine solid solutions
NASA Astrophysics Data System (ADS)
Dachs, Edgar; Geiger, Charles A.; Benisek, Artur; Grodzicki, Michael
2014-01-01
The heat capacity, Cp, of five solid-solution members of the almandine(Alm)-spessartine(Sps) binary, consisting of three synthetic polycrystalline and two natural single-crystal samples, was measured in the temperature range between 2 and 300 K using relaxation calorimetry and between 282 and 764 K using DSC methods. All garnets exhibit a ?-type heat-capacity anomaly at low temperatures resulting from a paramagnetic to antiferromagnetic phase transition. The temperature of the magnetic transition in Fe-rich garnets occurs between those of the two end-members (i.e. 9.2 K for almandine and 6.2 K for spessartine), but lies at lower values between 3.5 and 4.5 K for more Sps-rich compositions with XMngrt>0.5. The calorimetric entropy at 298 K shows mechanical-mixture behavior for Sps-rich garnets and a slight possible negative deviation from such behavior for Alm-rich compositions. At the 2? level all data are, however, consistent with ideal mixing behavior and the Margules entropy interaction parameter, WS,FeMngrt, is zero for the Alm-Sps binary. Thermodynamic analysis of published high P and T phase-equilibrium Fe-Mn exchange experiments between garnet and ilmenite shows that the excess Gibbs free energy of mixing, ?Gex, for Fe-Mn in garnet is positive and asymmetric towards spessartine. Margules enthalpy interaction parameters of WH,FeMngrt=4170±518 J/cation?mol and WH,MnFe=1221±588 J/cation?mol are derived giving a maximum of ?Gex?0.7 kJ/cation?mol at XMngrt?0.6. ?Hex obtained using autocorrelation analysis of published IR spectra of Alm-Sps solid solutions is in reasonable agreement with that derived from phase-equilibrium and calorimetry data. Previous diffraction and spectroscopic results on Alm-Sps garnets and quantum mechanical calculations made on almandine are used to interpret the macroscopic thermodynamic behavior from a microscopic basis. The relevance of the new garnet Fe-Mn mixing model for petrological calculations is demonstrated by incorporating it into the quaternary garnet mixing model of Berman (1990). Thus, better agreement for temperatures calculated using Fe-Mn garnet-ilmenite and Fe-Mg garnet-biotite geothermometry could be achieved. Temperatures calculated for Mn-poor and Mn-rich garnet-bearing assemblages, applying garnet-biotite thermometry, are in better agreement taking Fe-Mn mixing into account.
Donohue, M.D.
1993-09-01
We have developed new equations of state for pure-component chain molecules. The excellent performance of complicated theories, such as the Generalized Flory Dimer (GFD) theory can be mimicked by simpler equations, if assumptions for the shape parameters are made. We developed engineering correlations based on GFD theory, using local composition theory to take into account attractive forces. During this period, we compared methods for calculating repulsive and attractive contributions to equation of state against computer simulation data for hard and square-well chains, and against experimental data from the literature. We also have studied microstructure and local order in fluids that contain asymmetric molecules. We developed a thermodynamic model for polar compounds based on a site-site interaction approach. We have shown the equivalence of various classes of theories for hydrogen bonding, and used this equivalence to derive a multiple site model for water. In addition, simple cubic equations of state have been applied to calculate physical and chemical-reaction equilibria in nonideal systems. We measured infinite dilution activity coefficients using HPLC. We also measured high pressure vapor liquid equilibria of ternary and quaternary systems containing supercritical solvents. We used FT-IR spectroscopy to examine self-association of aliphatic alcohols due to hydrogen bonding, and to investigate the hydrogen bonding in polymer-solvent mixtures.
Thermodynamic properties of a layered S = 7/2 Heisenberg magnet Gd(OH)CO3
NASA Astrophysics Data System (ADS)
Orendac, Martin; Ulicny, Martin; Cizmar, Erik; Orendacova, Alzbeta; Chen, Yan-Cong; Meng, Zhao-Sha; Tong, Ming-Liang
2015-03-01
Thermodynamic quantities and ESR spectra of Gd(OH)CO3 (I) are reported. The material may be considered to consist of weakly coupled layers with potentially triangular arrangement of exchange paths within each layer. Different bridging groups and distances among Gd3+ ions may be responsible for spatial anisotropy of magnetic coupling. Preliminary analysis of magnetic susceptibility using Curie-Weiss law yielded ? = -1.05 K indicating weak antiferromagnetic coupling and consequently, spin frustration in (I). More detailed simultaneous analysis of specific heat, susceptibility and magnetization studied down to nominally 0.45 K revealed non-negligible role of single-ion anisotropy. Using the model of weakly interacting S =7/2 trimers, the gross features of measured data may be explained while assuming single-ion anisotropy D /kB ~ 0.6 K and effective intratrimer magnetic coupling | J /kB | ~0.3 K. The obtained D value reasonably reproduces the position and shape of ESR line. The performed analysis suggests that magnetism in (I) is governed predominantly by crystal field effects and frustration plays a minor role. Supported by ITMS26220120005 and VEGA 1/0143/13.
Moisture sorption isotherms and thermodynamic properties of mexican mennonite-style cheese.
Martinez-Monteagudo, Sergio I; Salais-Fierro, Fabiola
2014-10-01
Moisture adsorption isotherms of fresh and ripened Mexican Mennonite-style cheese were investigated using the static gravimetric method at 4, 8, and 12 °C in a water activity range (aw) of 0.08-0.96. These isotherms were modeled using GAB, BET, Oswin and Halsey equations through weighed non-linear regression. All isotherms were sigmoid in shape, showing a type II BET isotherm, and the data were best described by GAB model. GAB model coefficients revealed that water adsorption by cheese matrix is a multilayer process characterized by molecules that are strongly bound in the monolayer and molecules that are slightly structured in a multilayer. Using the GAB model, it was possible to estimate thermodynamic functions (net isosteric heat, differential entropy, integral enthalpy and entropy, and enthalpy-entropy compensation) as function of moisture content. For both samples, the isosteric heat and differential entropy decreased with moisture content in exponential fashion. The integral enthalpy gradually decreased with increasing moisture content after reached a maximum value, while the integral entropy decreased with increasing moisture content after reached a minimum value. A linear compensation was found between integral enthalpy and entropy suggesting enthalpy controlled adsorption. Determination of moisture content and aw relationship yields to important information of controlling the ripening, drying and storage operations as well as understanding of the water state within a cheese matrix. PMID:25328178
Thermodynamic properties of a symmetrical binary mixture in the coexistence region
Das, Subir K. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India); Institut fuer Physik, Johannes Gutenberg-Universitaet, Staudinger Weg 7, D-55099 Mainz (Germany); Binder, Kurt [Institut fuer Physik, Johannes Gutenberg-Universitaet, Staudinger Weg 7, D-55099 Mainz (Germany)
2011-12-15
A three-dimensional symmetric binary fluid is studied, as a function of temperature, in the two-phase (liquid-liquid) coexistence region via Monte Carlo simulations. Particular focus has been in the understanding of curvature-dependent interfacial tension, which is observed to vary as {sigma}(R)={sigma}({infinity})/[1+2((l/R)){sup 2}], implying that a Tolman length is zero in the limit R{yields}{infinity}. The length l is found to have a critical divergence the same as the correlation length, but its amplitude is significantly larger (l{approx_equal}4{xi}). Our findings hence imply that the barrier against homogeneous nucleation is significantly reduced (in comparison with the classical nucleation theory) in the critical region. We also report results for the critical behavior of the flat interfacial tension {sigma}({infinity}) and the concentration susceptibility, as well as the amplitude ratios involving these thermodynamic quantities. Noting that the interatomic potential in our model is described by the Lennard-Jones form that decays faster that 1/r{sup 3}, all of our results for critical phenomena are expectedly consistent with the Ising universality class of three spatial dimensions.
Black holes with non-Abelian hair and their thermodynamical properties
NASA Astrophysics Data System (ADS)
Torii, Takashi; Maeda, Kei-Ichi
1993-08-01
We present some black-hole solutions of the Einstein-Yang-Mills-dilaton system and calculate their Hawking temperatures. We find that if the coupling constant of the dilaton is smaller than some critical value, the thermodynamical behavior of these black holes includes two phase transitions at points determined by the value of the mass parameter. The black holes with masses between those two critical values have a positive specific heat. This is also true for the known colored black-hole solutions. We also reanalyze Skyrme black holes and find that there exist two types of solutions (a stable type and an unstable excited type) and these two types converge to a bifurcation point at some critical horizon radius, beyond which there is no Skyrme black hole. The stable black holes have two possible fates: they can evaporate via the Hawking process, and so evolve into a particlelike (Skyrmion) solution, or they can accrete matter and evolve into the Schwarzschild solution. When a Skyrme black hole evolves into a Schwarzschild black hole, its area changes discontinuously, so that we may regard this evolution as a kind of first-order phase transition. The specific heat of stable Skyrme black holes is always negative, while there are either one or three transition points for unstable Skyrme black holes.
NASA Astrophysics Data System (ADS)
Pascal, Tod A.; Karasawa, Naoki; Goddard, William A.
2010-10-01
As assemblies of graphene sheets, carbon nanotubes, and fullerenes become components of new nanotechnologies, it is important to be able to predict the structures and properties of these systems. A problem has been that the level of quantum mechanics practical for such systems (density functional theory at the PBE level) cannot describe the London dispersion forces responsible for interaction of the graphene planes (thus graphite falls apart into graphene sheets). To provide a basis for describing these London interactions, we derive the quantum mechanics based force field for carbon (QMFF-Cx) by fitting to results from density functional theory calculations at the M06-2X level, which demonstrates accuracies for a broad class of molecules at short and medium range intermolecular distances. We carried out calculations on the dehydrogenated coronene (C24) dimer, emphasizing two geometries: parallel-displaced X (close to the observed structure in graphite crystal) and PD-Y (the lowest energy transition state for sliding graphene sheets with respect to each other). A third, eclipsed geometry is calculated to be much higher in energy. The QMFF-Cx force field leads to accurate predictions of available experimental mechanical and thermodynamics data of graphite (lattice vibrations, elastic constants, Poisson ratios, lattice modes, phonon dispersion curves, specific heat, and thermal expansion). This validates the use of M06-2X as a practical method for development of new first principles based generations of QMFF force fields.
NASA Astrophysics Data System (ADS)
Mehta, Rakhi N.; More, Utkarsh; Malek, Naved; Chakraborty, Mousumi; Parikh, Parimal A.
2015-01-01
The present work addresses the formation of water-in-diesel (W/D) nanoemulsion by blending different percentages of water along with nano-Al additive in various propositions to enhance the combustion characteristics. The roles of various surfactants such as Sorbitan monooleate (Span 80), Triton X-100, Tetradecyltrimethylammonium bromide, and newly synthesized and characterized dicationic surfactants were discussed based upon their ability to stabilize the nanoemulsions. Surface active properties of the surfactants were determined by measuring their interfacial tension and subsequently by measuring the critical micelle concentration of the surfactants. Triton X-100 was found to be the most efficient surfactant for the current water-in-diesel nanoemulsion as it stabilized the suspensions for more than 8 h. Particle size analysis proved emulsion size to be in the order of nanometer, and zeta potential values were found to have neutral behavior at water-diesel interface. Experimental studies confirmed that that blends W/D [1 % (vol.) water] and W/DA [1 % (vol.) water, 0.1 % (wt.) nano-Al] were thermodynamically stable.
NASA Astrophysics Data System (ADS)
Dachs, E.; Geiger, C. A.; Benisek, A.
2012-12-01
The aluminosilicate garnets (E3Al2Si3O12 with E = Fe2+, Mn2+, Ca, Mg) form an important rock-forming mineral group. Much study has been directed toward determining their thermodynamic properties. The iron end-member almandine (Fe3Al2Si3O12) is a key phase in many petrologic investigations. As part of an ongoing calorimetric and thermodynamic study of the aluminosilicate garnets, the heat capacity of three synthetic well-characterized polycrystalline almandine garnets and one natural almandine-rich single crystal was measured. The various garnets were characterized by optical microscopy, electron-microprobe analysis, X-ray powder diffraction and 57Fe Mössbauer spectroscopy. Heat capacity measurements were performed in the temperature range 3 to 300 K using relaxation calorimetry and between 282 and 764 K using DSC methods. From the former, So values between 336.7 ± 0.8 and 337.8 ± 0.8 J/molK are calculated for the different samples. The smaller value is considered the best So for end-member stoichiometric almandine, because it derives from the "best" Fe3+-free synthetic sample. The Cp behavior for almandine at T > 298 K is given by the polynomial (in J/molK): Cp = 649.06(±4) - 3837.57(±122)T-0.5 - 1.44682(±0.06)107T-2 + 1.94834(±0.09)109T-3, which is calculated using DSC data together with one published heat-content datum determined by transposed-drop calorimetry along with a new determination that gives H1181K - H302K = 415.0 ± 3.2 kJ/mole. Almandine shows a ?-type heat-capacity anomaly at low temperatures resulting from a paramagnetic-antiferromagnetic phase transition at about 9 K. The lattice heat capacity was calculated using the single-parameter phonon dispersion model of Komada and Westrum (1997), which allows the non-lattice heat capacity (Cex) behavior to be modelled. An analysis shows the presence of an electronic heat-capacity contribution (Cel - Schottky anomaly) around 17 K that is superimposed on a larger magnetic heat-capacity effect (Cmag). The calculated lattice entropy at 298.15 K is Svib = 303.3 J/molK and it contributes about 90% to the total standard entropy at 298 K. The non-lattice entropy is Sex = 33.4 J/molK and consists of Smag = 32.1 J/molK and Sel = 1.3 J/molK contributions. Using the So = 336.7 J/molK value and the Cp polynomial for almandine, we derived its enthalpy of formation, ?Hof, from an analysis of experimental phase equilibrium results on the reactions almandine + 3rutile = 3ilmenite + sillimanite + 2quartz and 2ilmenite = 2iron + 2rutile + O2. ?Hof = -5269.63 kJ/mol was obtained. So for grossular, pyrope, spessartine, and almandine, as well as their Cp behavior to high temperatures, have all been measured calorimetrically. Uncertainties in older calorimetric studies appear to have been resolved. The standard thermodynamic properties Vo and So are now well determined for all four garnets. In addition, ?Hof for all, except possibly spessartine, also appear to be well known.
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.; Lee, Kam-Pui
1990-01-01
Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature.
NASA Astrophysics Data System (ADS)
Yang, Chun-Yan; Dai, Fu-Ping; Zhang, Rong; Li, Liu-Hui; Zhou, Qian
2015-02-01
First-principles calculations are performed to investigate the elastic, phonon and thermodynamic properties of ZnAl2O4 and ZnAl2S4 structures. The equations of state are fitted by a four-parameter Birch-Murnaghan equation upon the first-principles energy vs. volume data. Three independent elastic constants c11, c12 and c44 at zero pressure are determined by strain energy vs. strain relationships, and the two structures are both mechanically stable. Elastic properties including bulk moduli, shear moduli, Young's moduli, Poisson's ratios and anisotropy values for both phases are estimated by Voigt-Reuss-Hill averaging scheme. The mechanical properties such as ductility and brittleness are further analyzed. The density functional perturbation theory is utilized to calculate the phonon properties and both phases are found to be dynamically stable. The phonon and Debye models are used to predict the thermodynamic properties such as the Gibbs free energies, entropies and specific heats at constant pressure for ZnAl2O4 and ZnAl2S4 compounds.
NASA Astrophysics Data System (ADS)
Niu, Zhen-Wei; Zeng, Zhao-Yi; Hu, Cui-E.; Cai, Ling-Cang; Chen, Xiang-Rong
2015-01-01
The thermodynamic properties of CeO2 have been reevaluated by a simple but accurate scheme. All our calculations are based on the self-consistent ab initio lattice dynamical (SCAILD) method that goes beyond the quasiharmonic approximation. Through this method, the effects of phonon-phonon interactions are included. The obtained thermodynamic properties and phonon dispersion relations are in good agreement with experimental data when considering the correction of phonon-phonon interaction. We find that the correction of phonon-phonon interaction is equally important and should not be neglected. At last, by comparing with quasiharmonic approximation, the present scheme based on SCAILD method is probably more suitable for high temperature systems.
Eric W. Lemmon; Richard T Jacobsen; Steven G. Penoncello; Daniel G. Friend
2000-01-01
A thermodynamic property formulation for standard dry air based upon available experimental p–&rgr;–T, heat capacity, speed of sound, and vapor–liquid equilibrium data is presented. This formulation is valid for liquid, vapor, and supercritical air at temperatures from the solidification point on the bubble-point curve (59.75 K) to 2000 K at pressures up to 2000 MPa. In the absence of reliable
M. O. McLinden; J. S. Gallagher; L. A. Weber; G. Morrison; D. Ward; A. R. H. Goodwin; M. R. Moldover; J. W. Schmidt; H. B. Chae; T. J. Bruno; J. F. Ely; M. L. Huber
1989-01-01
The thermodynamic properties of R134a and R123 are formulated using a modified Benedict-Webb-Rubin (MBWR) equation of state fit to experimental measurements of the critical point, vapor pressure, saturated liquid and vapor volumes, superheated pressure-volume-temperature (p-V-T) behavior, and second virial coefficients derived from p-V-T- and sound speed measurements. The heat capacity of the ideal gas reference state is determined from sound
E. K. Riedel; H. Meyer; R. P. Behringer
1976-01-01
The scaling theory for tricritical phenomena by Riedel is applied to the analysis of thermodynamic properties of liquid3He-4He mixtures near the tricritical point. Within this theory experimental data for the phase diagram, the3He molar concentration X, and the concentration susceptibility (? X\\/?Delta) T are discussed in terms of two scaling fields that are functions of the temperature T and the
J. L. Holm; Edgar F. Westrum Jr.; O. J. Kleppa
1967-01-01
Cryogenic heat-capacity measurements on coesite and stishovite provide thermo-dynamic properties from 5 to 350°K. The heat capacities ( C p ), entropies ( S °), and Gibbs energy functions [-( G ° - H ° 0 )\\/ T ] are 10.85, 9.65, 4.124, and 10.27, 6.64, 2.362 at 298.15°K for coesite and stishovite, respectively, in cal\\/(mole °K). Enthalpies of transition
Mark Asta; Stephen M. Foiles
1996-01-01
The structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions have been studied using a computational approach which combines an embedded-atom-method (EAM) description of alloy energetics with a second-order-expansion (SOE) treatment of compositional and displacive disorder. It is discussed in detail how the SOE approach allows the EAM expression for the energy of a substitutional alloy to be
S. L. Clegg; M. J. Kleeman; R. J. Griffin; J. H. Seinfeld
2008-01-01
Air quality models that generate the concentrations of semi-volatile and other condensable organic compounds using an explicit reaction mechanism require estimates of the physical and thermodynamic properties of the compounds that affect gas\\/aerosol partitioning: vapour pressure (as a subcooled liquid), and activity coefficients in the aerosol phase. The model of Griffin, Kleeman and co-workers (e.g., Griffin et al., 2003; Kleeman
S. L. Clegg; M. J. Kleeman; R. J. Griffin; J. H. Seinfeld
2007-01-01
Air quality models that generate the concentrations of semi-volatile and other condensable organic compounds using an explicit reaction mechanism require estimates of the physical and thermodynamic properties of the compounds that affect gas\\/aerosol partitioning: vapour pressure (as a subcooled liquid), and activity coefficients in the aerosol phase. The model of Griffin, Kleeman and co-workers (e.g., Griffin et al., 1999; Kleeman
Lenz, T.G.; Vaughan, J.D. (Colorado State Univ., Fort Collins (USA))
1989-02-23
Although there have been many experimental investigations of the Diels-Alder dimerization of 1,3-cyclopentadiene, there remains considerable uncertainty in such thermodynamic properties as {Delta}H{degree}, {Delta}S{degree}, {Delta}G{degree}, and K{sub p} for the reaction at various temperatures. Despite this uncertainty, the reaction is a good subject for computational models, because it is one of the few Diels-Alder reactions which has been studied extensively in the laboratory both in the gas and liquid phase over a wide range of temperatures. This paper describes application of a force-field model to calculate thermodynamic properties of the monomer and both endo and exo isomers of the dimer for temperatures ranging from 273 to 500 K. The Boyd MOLBD3 force-field program modified to include (1) -ene and -diene parameters introduced by Anet and Yavari and (2) five-member and methylene bridge parameters suggested by the present authors was used for the calculations. Calculated equilibrium constants for both the gas and liquid phase, and other thermodynamic properties, agreed satisfactorily with what appear to be somewhat inconsistent existing experimental data. This work thus indicates that force-field methods hold promise as a useful alternative to experimental methods for the study of equilibrium of chemically reactive systems involving nontrivial molecules.
Yang, F; Romanova, E; Kubareva, E; Dolinnaya, N; Gajdos, V; Burenina, O; Fedotova, E; Ellis, J S; Oretskaya, T; Hianik, T; Thompson, M
2009-01-01
Thymidine glycol residues in DNA are biologically active oxidative molecular damage sites caused by ionizing radiation and other factors. One or two thymidine glycol residues were incorporated in 19- to 31-mer DNA fragments during automatic oligonucleotide synthesis. These oligonucleotide models were used to estimate the effect of oxidized thymidines on the thermodynamic, substrate and interfacial acoustic properties of DNA. UV-monitoring melting data revealed that modified residues in place of thymidines destabilize the DNA double helix by 8-22 degrees C, depending on the number of lesions, the length of oligonucleotide duplexes and their GC-content. The diminished hybridizing capacity of modified oligonucleotides is presumably due to the loss of aromaticity and elevated hydrophilicity of thymine glycol in comparison to the thymine base. According to circular dichroism (CD) data, the modified DNA duplexes retain B-form geometry, and the thymidine glycol residue introduces only local perturbations limited to the lesion site. The rate of DNA hydrolysis by restriction endonucleases R.MvaI, R.Bst2UI, R.MspR9I and R.Bme1390I is significantly decreased as the thymidine glycol is located in the central position of the double-stranded recognition sequences 5'-CC / WGG-3' (W = A, T) or 5'-CC / NGG-3' (N = A, T, G, C) adjacent to the cleavage site. On the other hand, the catalytic properties of enzymes R.Psp6I and R.BstSCI recognizing the similar sequence are not changed dramatically, since their cleavage site is separated from the point of modification by several base-pairs. Data obtained by gel-electrophoretic analysis of radioactive DNA substrates were confirmed by direct spectrophotometric assay developed by the authors. The effect of thymidine glycol was also observed on DNA hybridization at the surface of a thickness-shear mode acoustic wave device. A 1.9-fold decrease in the rate of duplex formation was noted for oligonucleotides carrying one or two thymidine glycol residues in relation to the unmodified analog. PMID:19082173
NASA Astrophysics Data System (ADS)
Spera, Frank J.; Nevins, Dean; Ghiorso, Mark; Cutler, Ian
2009-11-01
Molecular dynamics simulations for liquid CaAl 2Si 2O 8 have been carried out at 72 state points spanning ranges in density ( ?: 2398-4327 kg/m 3), temperature ( T: 3490-6100 K) and pressure ( P: 0.84-120 GPa) relevant to geosystems. The atomic scale structure of the melt is determined by analysis of nearest neighbor coordination statistics as a function of T and P. Dramatic structural change occurs as pressure increases especially for 0 < P <20 GPa at all temperatures. Changes in structure are encapsulated by examining the coordination of Si, Al, Ca and O around oxygen and vice versa. Si and Al change from predominantly fourfold at low- P to dominantly sixfold for P >˜ 20 GPa. Pentahedrally coordinated Si and Al in distorted trigonal bipyramids attain abundance maxima corresponding to ˜60% of total (Si, Al)O n at 3-5 GPa and weakly depend on T. The coordination of Ca by oxygen increases from 7 to 10 for 0 < P < 20 GPa and changes slowly for P > 20 GPa at 3500 K. Similar behavior is seen at 6000 K except that the interval of rapid changes occurs at higher pressure. Oxygen with only one nearest Si or Al neighbor (i.e., non-bridging oxygen, NBO) decreases whereas oxygen with two or three nearest neighbors of Si, Al or Ca increases as pressure increases. Changes in melt structure are reflected in the variation of thermodynamic and transport properties of the liquid. Values of the self-diffusivities of Ca, Al, Si and O are fit to a modified Arrhenian expression and compare well to limited laboratory data. Self-diffusivities are best fit using 'low P' and 'high- P' expressions, identical in form but with different parameters, with activation energies and activation volumes in the range 150-200 kJ/mol and +5 to -1 cm 3/mol, respectively. Green-Kubo calculations for liquid shear viscosity are presented and compare well with limited laboratory results. Application of the Eyring model to determine the characteristic size and number of atoms in the activated cluster based on independently computed D and ? suggests that the activated cluster decreases from ˜8 to ˜3 atoms from low to high pressure while its characteristic size shrinks from ˜14 Å to ˜3 Å providing insight into dynamics of atom mobility and possible cooperative behavior. The equation of state and variation of internal energy with T and V are used in Part II ( Ghiorso et al., 2009) to derive a comprehensive thermodynamic description of liquid CaAl 2Si 2O 8. This is best accomplished by allowing for EOS expressions broken into high and low pressure intervals consistent with coordination statistics and MD-derived transport properties.
O. Olendski
2015-04-07
Thermodynamic properties of the one-dimensional (1D) quantum well (QW) with miscellaneous permutations of the Dirichlet (D) and Neumann (N) boundary conditions (BCs) at its edges in the perpendicular to the surfaces electric field $\\mathscr{E}$ are calculated. For the canonical ensemble, analytical expressions involving theta functions are found for the mean energy and heat capacity $c_V$ for the box with no applied voltage. Pronounced maximum accompanied by the adjacent minimum of the specific heat dependence on the temperature $T$ for the pure Neumann QW and their absence for other BCs are predicted and explained by the structure of the corresponding energy spectrum. Applied field leads to the increase of the heat capacity and formation of the new or modification of the existing extrema what is qualitatively described by the influence of the associated electric potential. A remarkable feature of the Fermi grand canonical ensemble is, at any BC combination in zero fields, a salient maximum of $c_V$ observed on the $T$ axis for one particle and its absence for any other number $N$ of corpuscles. Qualitative and quantitative explanation of this phenomenon employs the analysis of the chemical potential and its temperature dependence for different $N$. It is proved that critical temperature $T_{cr}$ of the Bose-Einstein (BE) condensation increases with the applied voltage for any number of particles and for any BC permutation except the ND case at small intensities $\\mathscr{E}$ what is explained again by the modification by the field of the interrelated energies. It is shown that even for the temperatures smaller than $T_{cr}$ the total dipole moment $\\langle P\\rangle$ may become negative for the quite moderate $\\mathscr{E}$. For either Fermi or BE system, the influence of the electric field on the heat capacity is shown to be suppressed with $N$ growing.
Anders Larsson; Philippe Lalande; Anne Bondiou-Clergerie; Alain Delannoy
2000-01-01
During a lightning strike to an aircraft in flight, the lightning channel becomes deformed in the airflow and displaced along the aircraft, a so-called swept stroke. The deformation and the displacement are caused by the interaction between the aerodynamic flow and the plasma properties of the channel together with the properties of the surface. The main part of the lightning
R. V Gopala Rao; R Venkatesh
2003-01-01
A short survey has been made on the extensive work that is being done on the pressure derivatives of the second order elastic constants (SOEC) to ascertain various properties of substances. Hence an attempt has been made to correlate the pressure derivatives to some properties of the substances. Thus some equations have been derived to correlate the Grüneisen parameter which
Hydrogen technology survey: Thermophysical properties
NASA Technical Reports Server (NTRS)
Mccarty, R. D.
1975-01-01
The thermodynamic functions, transport properties, and physical properties of both liquid and gaseous hydrogen are presented. The low temperature regime is emphasized. The tabulation of the properties of normal hydrogen in both Si and engineering units is given along with the tabulation of parahydrogen.
Senegas, Jean-Michel; Bernardinelli, Gérald; Imbert, Daniel; Bünzli, Jean-Claude G; Morgantini, Pierre-Yves; Weber, Jacques; Piguet, Claude
2003-07-28
The hydrolysis of terminal (t)butyl-ester groups provides the novel nonadentate podand tris[2-[N-methylcarbamoyl-(6-carboxypyridine-2)-ethyl]amine] (L13) which exists as a mixture of slowly interconverting conformers in solution. At pH = 8.0 in water, its deprotonated form [L13 - 3H](3-) reacts with Ln(ClO(4))(3) to give the poorly soluble and stable podates [Ln(L13 - 3H)] (log(beta(110)) = 6.7-7.0, Ln = La-Lu). The isolated complexes [Ln(L13 - 3H)](H(2)O)(7) (Ln = Eu, 8; Tb, 9; Lu, 10) are isostructural, and their crystal structures show Ln(III) to be nine-coordinate in a pseudotricapped trigonal prismatic site defined by the donor atoms of the three helically wrapped tridentate binding units of L13. The Ln-O(carboxamide) bonds are only marginally longer than the Ln-O(carboxylate) bonds in [Ln(L13 - 3H)], thus producing a regular triple helix around Ln(III) which reverses its screw direction within the covalent Me-TREN tripod. High-resolution emission spectroscopy demonstrates that (i) the replacement of terminal carboxamides with carboxylates induces only minor electronic changes for the metallic site, (ii) the solid-state structure is maintained in water, and (iii) the metal in the podate is efficiently protected from interactions with solvent molecules. The absolute quantum yields obtained for [Eu(L13 - 3H)] (Phi(Eu)(tot)= 1.8 x 10(-3)) and [Tb(L13 - 3H)] (Phi(Eu)(tot)= 8.9 x 10(-3)) in water remain modest and strongly contrast with that obtained for the lanthanide luminescence step (Phi(Eu) = 0.28). Detailed photophysical studies assign this discrepancy to the small energy gap between the ligand-centered singlet ((1)pi pi*) and triplet ((3)pi pi*) states which limits the efficiency of the intersystem crossing process. Theoretical TDDFT calculations suggest that the connection of a carboxylate group to the central pyridine ring prevents the sizable stabilization of the triplet state required for an efficient sensitization process. The thermodynamic and electronic origins of the advantages (stability, lanthanide quantum yield) and drawbacks (solubility, sensitization) brought by the "carboxylate effect" in lanthanide complexes are evaluated for programming predetermined properties in functional devices. PMID:12870960
Nedd, Sean; DeYonker, Nathan; Wilson, Angela; Piecuch, Piotr; Gordon, Mark
2012-04-12
The correlation consistent composite approach (ccCA), using the S4 complete basis set two-point extrapolation scheme (ccCA-S4), has been modified to incorporate the left-eigenstate completely renormalized coupled cluster method, including singles, doubles, and non-iterative triples (CR-CC(2,3)) as the highest level component. The new ccCA-CC(2,3) method predicts thermodynamic properties with an accuracy that is similar to that of the original ccCA-S4 method. At the same time, the inclusion of the single-reference CR-CC(2,3) approach provides a ccCA scheme that can correctly treat reaction pathways that contain certain classes of multi-reference species such as diradicals, which would normally need to be treated by more computationally demanding multi-reference methods. The new ccCA-CC(2,3) method produces a mean absolute deviation of 1.7 kcal/mol for predicted heats of formation at 298 K, based on calibration with the G2/97 set of 148 molecules, which is comparable to that of 1.0 kcal/mol obtained using the ccCA-S4 method, while significantly improving the performance of the ccCA-S4 approach in calculations involving more demanding radical and diradical species. Both the ccCA-CC(2,3) and ccCA-S4 composite methods are used to characterize the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to trans-1,3-butadiene, for which conventional coupled cluster methods, such as the CCSD(T) approach used in the ccCA-S4 model and, in consequence, the ccCA-S4 method itself might fail by incorrectly placing the disrotatory pathway below the conrotatory one. The ccCA-CC(2,3) scheme provides correct pathway ordering while providing an accurate description of the activation and reaction energies characterizing the lowest-energy conrotatory pathway. The ccCA-CC(2,3) method is thus a viable method for the analyses of reaction mechanisms that have significant multi-reference character, and presents a generally less computationally intensive alternative to true multi-reference methods, with computer costs and ease of use that are similar to those that characterize the more established, CCSD(T)-based, ccCA-S4 methodology.
NASA Astrophysics Data System (ADS)
Nedd, Sean A.; DeYonker, Nathan J.; Wilson, Angela K.; Piecuch, Piotr; Gordon, Mark S.
2012-04-01
The correlation consistent composite approach (ccCA), using the S4 complete basis set two-point extrapolation scheme (ccCA-S4), has been modified to incorporate the left-eigenstate completely renormalized coupled cluster method, including singles, doubles, and non-iterative triples (CR-CC(2,3)) as the highest level component. The new ccCA-CC(2,3) method predicts thermodynamic properties with an accuracy that is similar to that of the original ccCA-S4 method. At the same time, the inclusion of the single-reference CR-CC(2,3) approach provides a ccCA scheme that can correctly treat reaction pathways that contain certain classes of multi-reference species such as diradicals, which would normally need to be treated by more computationally demanding multi-reference methods. The new ccCA-CC(2,3) method produces a mean absolute deviation of 1.7 kcal/mol for predicted heats of formation at 298 K, based on calibration with the G2/97 set of 148 molecules, which is comparable to that of 1.0 kcal/mol obtained using the ccCA-S4 method, while significantly improving the performance of the ccCA-S4 approach in calculations involving more demanding radical and diradical species. Both the ccCA-CC(2,3) and ccCA-S4 composite methods are used to characterize the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to trans-1,3-butadiene, for which conventional coupled cluster methods, such as the CCSD(T) approach used in the ccCA-S4 model and, in consequence, the ccCA-S4 method itself might fail by incorrectly placing the disrotatory pathway below the conrotatory one. The ccCA-CC(2,3) scheme provides correct pathway ordering while providing an accurate description of the activation and reaction energies characterizing the lowest-energy conrotatory pathway. The ccCA-CC(2,3) method is thus a viable method for the analyses of reaction mechanisms that have significant multi-reference character, and presents a generally less computationally intensive alternative to true multi-reference methods, with computer costs and ease of use that are similar to those that characterize the more established, CCSD(T)-based, ccCA-S4 methodology.
Nedd, Sean A; DeYonker, Nathan J; Wilson, Angela K; Piecuch, Piotr; Gordon, Mark S
2012-04-14
The correlation consistent composite approach (ccCA), using the S4 complete basis set two-point extrapolation scheme (ccCA-S4), has been modified to incorporate the left-eigenstate completely renormalized coupled cluster method, including singles, doubles, and non-iterative triples (CR-CC(2,3)) as the highest level component. The new ccCA-CC(2,3) method predicts thermodynamic properties with an accuracy that is similar to that of the original ccCA-S4 method. At the same time, the inclusion of the single-reference CR-CC(2,3) approach provides a ccCA scheme that can correctly treat reaction pathways that contain certain classes of multi-reference species such as diradicals, which would normally need to be treated by more computationally demanding multi-reference methods. The new ccCA-CC(2,3) method produces a mean absolute deviation of 1.7 kcal/mol for predicted heats of formation at 298 K, based on calibration with the G2/97 set of 148 molecules, which is comparable to that of 1.0 kcal/mol obtained using the ccCA-S4 method, while significantly improving the performance of the ccCA-S4 approach in calculations involving more demanding radical and diradical species. Both the ccCA-CC(2,3) and ccCA-S4 composite methods are used to characterize the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to trans-1,3-butadiene, for which conventional coupled cluster methods, such as the CCSD(T) approach used in the ccCA-S4 model and, in consequence, the ccCA-S4 method itself might fail by incorrectly placing the disrotatory pathway below the conrotatory one. The ccCA-CC(2,3) scheme provides correct pathway ordering while providing an accurate description of the activation and reaction energies characterizing the lowest-energy conrotatory pathway. The ccCA-CC(2,3) method is thus a viable method for the analyses of reaction mechanisms that have significant multi-reference character, and presents a generally less computationally intensive alternative to true multi-reference methods, with computer costs and ease of use that are similar to those that characterize the more established, CCSD(T)-based, ccCA-S4 methodology. PMID:22502503
Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India) [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); School of Instrumentation, USIC Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Dagaonkar, Geetanjali [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India)] [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Varshney, Meenu [Department of Physics, M.B. Khalsa College, Indore 452002 (India)] [Department of Physics, M.B. Khalsa College, Indore 452002 (India)
2010-08-15
Using a phenomenological lattice model incorporating the long-range Coulomb and charge transfer caused by the deformation of the electron shells of the overlapping ions and the Hafemeister and Flygare type short-range overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction, we present a comprehensive study to understand the effects of pressure on the elastic behavior as ductility (brittleness) and thermodynamical properties of Ga{sub 1-x}In{sub x}P. Estimated phase-transition pressure and the vast volume discontinuity in pressure-volume phase diagram confirm the structural phase transition from zinc blende (B3) to rock salt (B1) phase. From the elastic constants the Poisson's ratio {nu}, the ratio R{sub S/B} of S (Voigt averaged shear modulus) over B (bulk modulus), elastic wave velocity, average wave velocity and thermodynamical property Debye temperature is calculated. The Poisson's ratio {nu} and the ratio R{sub S/B} allows one to conclude that Ga{sub 1-x}In{sub x}P is brittle in zinc blende (B3) and ductile nature is inferred in sodium chloride (B1) phase. To our knowledge this is the first quantitative theoretical prediction of the doping and pressure dependent elastic properties for mixed valent Ga{sub 1-x}In{sub x}P compounds and still awaits experimental confirmations.
NASA Astrophysics Data System (ADS)
Fisenko, Anatoliy I.; Lemberg, Vladimir
2014-07-01
Using formula to describe the average spectrum of the extragalactic far infrared background (FIRB) radiation measured by the COBE FIRAS instrument in the 0.15-2.4 THz frequency interval at mean temperature T=18.5 K, the radiative and thermodynamic properties, such as the total emissivity, total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure are calculated. The value for the total intensity received in the 0.15-2.4 THz frequency interval is equal to 13.6 nW m-2 sr-1. This value is about 19.4 % of the total intensity expected from the energy released by stellar nucleosynthesis over cosmic history. The radiative and thermodynamic functions of the extragalactic far infrared background (FIRB) radiation are calculated at redshift z=1.5.
NASA Astrophysics Data System (ADS)
Xu, Xiao; Nagasako, Makoto; Kataoka, Mitsuo; Umetsu, Rie Y.; Omori, Toshihiro; Kanomata, Takeshi; Kainuma, Ryosuke
2015-03-01
Electronic, magnetic, and thermodynamic properties of Co2Cr(Ga,Si) -based shape-memory alloys, which exhibit reentrant martensitic transformation (RMT) behavior, were studied experimentally. For electric resistivity (ER), an inverse (semiconductor-like) temperature dependence in the parent phase was found, along with anomalous behavior below its Curie temperature. A pseudobinary phase diagram was determined, which gives a "martensite loop" clearly showing the reentrant behavior. Differential scanning calorimetry and specific-heat measurements were used to derive the entropy change ? S between martensite and parent phases. The temperature dependence of the derived ? S was analyzed thermodynamically to confirm the appearances of both the RMT and normal martensitic transformation. Detailed studies on the specific heat in martensite and parent phases at low temperatures were also conducted.
NSDL National Science Digital Library
lhalls
2009-09-22
Standard 1 Objective 2: Students will recognize and use the identity properties of addition and multiplication, the multiplicative property of zero, the commutative and associative properties of addition and multiplication, and the distributive property of multiplication over addition. This lesson is self-paced so here are some guidelines to insure that you have learned everything you need to know by the end of the lesson: 1. What does it mean to distribute? 2. How to simplify an expression. 3. How to combine like terms once you distribute. Today you will be learning about ...
Thermophysical properties of argon
Jaques, A.
1988-02-01
The entire report consists of tables of thermodynamic properties (including sound velocity, thermal conductivity and diffusivity, Prandtl number, density) of argon at 86 to 400/degree/K, in the form of isobars over 0.9 to 100 bars. (DLC)
The Fundamental Property Relation.
ERIC Educational Resources Information Center
Martin, Joseph J.
1983-01-01
Discusses a basic equation in thermodynamics (the fundamental property relation), focusing on a logical approach to the development of the relation where effects other than thermal, compression, and exchange of matter with the surroundings are considered. Also demonstrates erroneous treatments of the relation in three well-known textbooks. (JN)
NASA Technical Reports Server (NTRS)
Hippensteele, S. A.; Colladay, R. S.
1978-01-01
A computer program for determining desired thermodynamic and transport property values by means of a three-dimensional (pressure, fuel-air ratio, and either enthalpy or temperature) interpolation routine was developed. The program calculates temperature (or enthalpy), molecular weight, viscosity, specific heat at constant pressure, thermal conductivity, isentropic exponent (equal to the specific heat ratio at conditions where gases do not react), Prandtl number, and entropy for air and a combustion gas mixture of ASTM-A-1 fuel and air over fuel-air ratios from zero to stoichiometric, pressures from 1 to 40 atm, and temperatures from 250 to 2800 K.
Wolfgang Preis; Heinz Gamsjäger
2001-01-01
The thermodynamic properties ofZn5(OH)6(CO3)2 , hydrozincite, have been determined by performing solubility and d.s.c. measurements. The solubility constant in aqueous NaClO4media has been measured at temperatures ranging from 288.15 K to 338.15 K at constant ionic strength (I= 1.00 mol · kg?1). Additionally, the dependence of the solubility constant on the ionic strength has been investigated up to I= 3.00
Blanco, Sofía T; Gil, Laura; García-Giménez, Pilar; Artal, Manuela; Otín, Santos; Velasco, Inmaculada
2009-05-21
Critical properties and volumetric behavior for the {CO2(1)+C3H8(2)} system have been studied. The critical locus was measured with a flow apparatus and detected by critical opalescence. For the mixtures, repeatabilities in critical temperature and pressure are rTc
NASA Astrophysics Data System (ADS)
Rykounov, A. A.
2015-06-01
The influence of pressure on the thermodynamic, structural, and elastic properties of the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) molecular crystal at T = 0 is systematically studied. Calculations are carried out using density functional theory methods in a plane wave basis set with dispersion corrections for the exchange-correlation part of total energy, and ultrasoft pseudopotentials. The equilibrium unit cell parameters, the cold compression curve in the pressure range of 0-50 GPa and the sound speeds are computed. The effect of finite pressure on the molecular structure of TATB is elucidated from the analysis of relative changes in the intra- and intermolecular geometrical parameters. For the first time, the full set of elastic constants of this crystal at zero and non-zero pressures is determined from ab initio calculations. The resulted structural, elastic, and acoustic properties of TATB are shown to be in a good agreement with available experimental and theoretical data.
NSDL National Science Digital Library
Mineralogy 4 Kids
This site from the Mineralogical Society of America describes the physical properties of minerals in terms that kids will understand. The site also includes the definition of a mineral, an identification chart, and links to descriptions of the physical properties used to identify minerals.
Paris-Sud XI, Université de
. Introduction 5 0 The thermodynamic properties of the liquid mix- tures of the alkali metals with their halides of the thermodynamic freezing point depression. A small correction for properties of the liquid cesium-cesium halide PROPERTIES OF LIQUID CESIUM-CESIUM HALIDE MIXTURES AT 9 2 5 K H. yokokawaf and O.J. Kleppa The James Frunck
Huang, Jianbin
March 2012 Available online 23 March 2012 Keywords: Gemini surfactants Ethyl ammonium headgroups Enhanced aggregation capability Full understanding a b s t r a c t Cationic gemini surfactant homologues properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants
Duan, Yuhua
2013-06-28
The structural, electronic, and phonon properties of Li8ZrO6 are investigated with the application of density functional theory and lattice phonon dynamics. Based on the calculated data, the thermodynamics of CO2 absorption-desorption for Li8ZrO6 is analyzed and compared with those of Li2ZrO3 and Li6Zr2O7. The band gap of Li8ZrO6 is indirect along ?-L with a value of 4.74 eV. From the calculated thermodynamic properties of Li8ZrO6 reacting with CO2, we found that Li8ZrO6 could be regenerated at high temperatures (>1100 K). Our results indicated that the lithium zirconate with a lower Li2O/ZrO2 ratio has a lower turnover temperature. Hence, by mixing or doping two or more materials to form a new material, it is possible to find or synthesize CO2 sorbents that can fit the industrial needs for optimal performance. Although the CO2 capture capacity of Li8ZrO6 is much higher than that of Li2ZrO3, the high energy required for regeneration, the capacity loss during long absorption-desorption cycles, solid sintering at high temperature, and the material cost may affect its overall capture performance. Our results also provided some general guidelines for designing new CO2 sorbents. PMID:23674075
NASA Astrophysics Data System (ADS)
Seddik, T.; Khenata, R.; Bouhemadou, A.; Guechi, N.; Sayede, A.; Varshney, D.; Al-Douri, Y.; Reshak, A. H.; Bin-Omran, S.
2013-11-01
The full potential linearized augmented plane wave method within the framework of density functional theory is employed to investigate the structural, thermodynamic and elastic properties of the yttrium chalcogenides (YX: X=S, Se, and Te) in their low-pressure phase (Fm3barm) and high-pressure phase (Pm3barm). The exchange-correlation potential is treated with the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE). Temperature dependence of the volume and both adiabatic and isothermal bulk moduli is predicted for a temperature range from 0 to 1200 K for the both phases of the herein considered materials. Furthermore, we have analyzed the thermodynamic properties such as the heat capacities, CV and CP, thermal expansion, ?, and Debye temperature, ?D, under variable pressure and temperature. We have calculated the isothermal elastic constants CijT of the YX monochalcogenides in both NaCl-B1 and CsCl-B2 phases at zero pressure and a temperature range 0-1200 K. The results show that rare earth yttrium monochalcogenides are mechanically stable at high temperature. The elastic anisotropy of all studied materials in the two phases has been studied using three different methods.
NASA Astrophysics Data System (ADS)
Zhang, Xudong; Jiang, Wei
2015-06-01
The lattice dynamics, thermodynamic, mechanical properties and thermal conductivity of L12 Al3X (X = Sc, Er, Tm, Yb) intermetallics have been investigated from first-principles calculations by means of using the VASP code. Our results agree well with the previous experiments and calculations. The phonon dispersion curves and the density of phonon states have been calculated by means of using the PHONONPY code and compared with the experimental results. The four compounds stay dynamically stable in the L12 structure. We also calculated the thermodynamics properties and give the relationships between thermal parameters and temperature. The elastic constants of the considered compounds are satisfied with mechanical stability criteria. The related mechanical parameters predict that Al3Sc has higher hardness than the other three compounds, and four compounds all posses a brittle nature. The mechanical anisotropy is predicted by anisotropic constants AU and AZ. The results show that the four compounds are all elastically isotropic. We also calculated the thermal conductivity by means of the Clarke’s model and Cahill’s model and found that the thermal conductivity of the four intermetallics follows the order: Al3Sc > Al3Er > Al3Tm > Al3Yb.
NASA Astrophysics Data System (ADS)
Yang, Jinwen; Gao, Tao; Liu, Benqiong; Sun, Guangai; Chen, Bo
2015-03-01
Structural, elastic anisotropy, dynamical, and thermodynamic properties of U2Ti have been studied by employing density functional theory and density functional perturbative theory. The optimized lattice parameters a, c, unit volume V, bulk modulus B, and bond lengths dU-U, dU-Ti of U2Ti are in favorable agreement with the available experimental data and other theoretical values. The elastic constants under pressure were obtained using "energy-strain" method. The polycrystalline modulus, Poisson's ratio, brittle/ductile characteristics, Debye temperature and the integration of elastic wave velocities over different directions, and hardness under pressure are also evaluated successfully. The anisotropy of the directional bulk modulus and the Young's modulus is systematically predicted for the first time. It turns out that U2Ti should be stabilized mechanically up to 100 GPa, this compound just possesses slightly elastic anisotropy at zero pressure; however, the anisotropy becomes more and more significant with the increasing pressure. In particular, the phonon dispersion curves and phonon density of state under pressure are reported for the first time. The Raman and infrared-active phonon modes at C point are further assigned. Our results indicate that U2Ti is also stable dynamically up to 100 GPa. Additionally, within the calculated phonon density of states, the thermodynamic properties are predicted.
Yang, Xiao; He, Ling; Qin, Song; Tao, Guo-Hong; Huang, Ming; Lv, Yi
2014-01-01
The electrochemical behavior and thermodynamic properties of Ln(III) (Ln?=?Eu, Sm, Dy, Nd) were studied in 1-butyl-3-methylimidazolium bromide ionic liquid (BmimBr) at a glassy carbon (GC) electrode in the range of 293–338 K. The electrode reaction of Eu(III) was found to be quasi-reversible by the cyclic voltammetry, the reactions of the other three lanthanide ions were regarded as irreversible systems. An increase of the current intensity was obtained with the temperature increase. At 293 K, the cathodic peak potentials of ?0.893 V (Eu(III)), ?0.596 V (Sm(III)), ?0.637 V (Dy(III)) and ?0.641 V (Nd(III)) were found, respectively, to be assigned to the reduction of Ln(III) to Ln(II). The diffusion coefficients (Do), the transfer coefficients (?) of Ln(III) (Ln?=?Eu, Sm, Dy, Nd) and the charge transfer rate constants (ks) of Eu(III) were estimated. The apparent standard potential (E0*) and the thermodynamic properties of the reduction of Eu(III) to Eu(II) were also investigated. PMID:24752584
Stiegler, Thomas; Sadus, Richard J
2015-02-28
General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form. PMID:25725742
Wood, Robert H.
2005-10-11
The objective of this research was to combine new experimental measurements on heat capacities, volumes, and association constants of key compounds with theoretical equations of state and with first principles quantum mechanical calculations to generate predictions of thermodynamic data. The resulting thermodynamic data allow quantitative models of geochemical processes at high temperatures and pressures. Research funded by a DOE grant to Prof. Robert Wood at the University of Delaware involved the development of new theoretical equations of state for aqueous solutions of electrolytes and non-electrolytes, methods to estimate thermodynamic data not available from experiments, collection of data on model compounds through experiments and predictions of properties using ab initio quantum mechanics. During the last three and a half years, with support from our DOE grant, 16 papers have been accepted or published, and 3 more are in preparation. Results of this research have been reported in numerous invited and contributed presentations at national and international meetings. For this report, we will briefly comment on the highlights of the last 3 and a half years and give a complete list of papers published, accepted, or submitted during these years.
Fisicaro; Ghiozzi; Pelizzetti; Viscardi; Quagliotto
1996-12-01
We report a thermodynamic study of the aqueous solutions of 1-(3,3,4,4,5,5,6,6,6-nonafluorohexyl) pyridinium chloride, bromide, and iodide and N-octyl pyridinium iodide. Dilution enthalpies and osmotic coefficients of the aqueous solutions of these cationic surfactants have been measured at 313 K as a function of the concentration. The experimental data are expressed in terms of apparent and partial molar quantities. The changes in thermodynamic properties upon micellization have been obtained from the experimental data by using a pseudo phase transition approach. The cmc at 313 K have been evaluated from the plot of the milliosmolality, the measured quantity, vs molality. From the comparison with the trends of the enthalpies at 298 K of the same set of compounds, the effect of temperature on the energetics of their solutions can be derived. The trends of thermodynamic properties vs molality and the micellization parameters confirm that the effect of the counterions, however strong and inversely proportional to the radius of the hydrated counterion, seems to be reduced with respect to the hydrogenated analogs. The curves of the apparent and partial molar enthalpies vs m for the bromide and the iodide are lowered, with respect to the curve of the chloride, by an amount comparable to that at 298 K. This observation suggests that the changes in the absolute trends of the curves and in the micellization enthalpies are due to the modification of the more mobile hydrophobic hydration shell of the perfluoroalkyl chain, whereas the hydration sphere of the counterions is practically unaffected. The heat capacity data and the comparison with the behaviour of hydrogenated analogs is in agreement with the above observation. The trends of the free energies confirm that the degree of counterion binding, beta, and the aggregation number, n, increase with the increasing of the radius of the hydrated counterion. PMID:8954648
NSDL National Science Digital Library
2009-11-04
This simple description of the chemical and physical properties of water was produced by the U.S. Geological Survey. It includes a brief quiz to assess prior knowledge, diagrams of water molecules, and important numerical data about water.
NSDL National Science Digital Library
One of several such initiatives in recent years, this site from the UK government hosts a database of some 30,000 records of bank accounts and other property held in the UK by residents of countries classed as "belligerent enemies" (e.g., Germany) and "technical enemies" (Nazi-occupied countries) that were confiscated by the British government during the war. Individuals who were victims of persecution in these countries or their heirs are now entitled to claim their property or compensation. The database may be searched initially by country and then by name and/or address. Returns include name and address, types of property seized, and the value of the property. The site also includes the full text of several reports that "give the complete background of wartime and postwar policy and procedures for settlement." While obviously aimed at victims of Nazi (and satellite state) persecution, this site may also prove useful to historians of the era.
Fakhraee, Mostafa; Zandkarimi, Borna; Salari, Hadi; Gholami, Mohammad Reza
2014-12-11
The influences of hydroxyl functional group (-OH) on the thermodynamic and structural properties of ionic liquids (ILs) composed of 1-(2-Hydroxyethyl)-3-methyl imidazolium ([C2OHmim](+)) cation and the six different conventional anions, including [Cl](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) have been extensively investigated using classical molecular dynamics (MD) simulations combined with ab initio calculations over a wide range of temperature (298-550 K). The volumetric thermodynamic properties, enthalpy of vaporization, cohesive energy density, Hildebrand solubility parameter, and heat capacity at constant pressure were estimated at desired temperature. The simulated densities were in good agreement with the experimental data with a slight overestimation. The interionic interaction of selected ILs was also computed using both the MD simulations and ab initio calculations. It was found that the highest association of cation and anion is attributed to [C2OHmim][Cl] followed by [C2OHmim][NO3], and [C2OHmim][Tf2N] with the bulkiest anion has the weakest interionic interaction among chosen ILs. The similar trend of interactions energies was nearly observed from cohesive energy density results. Additional structural details were comprehensively yielded by calculating radial distribution functions (RDFs) and spatial distribution function (SDFs) at 358 K. The most stable configurations of isolated and dimer ion pairs of these ILs were in excellent consistency with RDFs and SDFs results. Significant changes in arrangement of anions around the [C2OHmim](+) cation in comparison with conventional imidazolium-based ILs can be inferred from the MD simulations and ab initio results. Also, microscopic structural properties disclosed that the most strong cation-cation interaction is ascribed to the hydroxyl-functionalized ILs composed of bulkier anions, whereas ILs incorporating [Cl](-) and [NO3](-) anions are mainly involved in cation-anion interactions. The formation of the intramolecular hydrogen bonding in the [C2OHmim](+) cation is another interesting result of the present study. PMID:25394200
NASA Astrophysics Data System (ADS)
Fisenko, Anatoliy I.; Lemberg, Vladimir
2015-07-01
Using the three-component spectral model describing the FIRAS average continuum spectra, the exact analytical expressions for thermodynamic and radiative functions of Galactic far-infrared radiation are obtained. The COBE FIRAS instrument data in the 0.15–2.88 THz frequency interval at the mean temperatures of T1 = 17.72 K, T2 = 14 K and T3 = 6.73 K are used for calculating the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, total emissivity, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume and pressure for the warm, intermediate-temperature and very cold components of the Galactic continuum spectra. The generalized Stefan-Boltzmann law for warm, intermediate-temperature and very cold components is constructed. The temperature dependence of each component is determined by the formula IS–B(T) = ??T6. This result is important when we construct the cosmological models of radiative transfer that can be applied inside the Galaxy. Within the framework of the three-component spectral model, the total number of photons in our Galaxy and the total radiation power (total luminosity) emitted from a surface of the Galaxy are calculated. Their values are NGtotal = 1.3780 × 1068 and IGtotal(T) = 1.0482 × 1036 W. Other radiative and thermodynamic properties of the Galactic far-infrared radiation (photon gas) of the Galaxy are calculated. The expressions for astrophysical parameters, such as the entropy density/Boltzmann constant and number density of the Galactic far-infrared photons are obtained. We assume that the obtained analytical expressions for thermodynamic and radiative functions may be useful for describing the continuum spectra of the far-infrared radiation for other galaxies.
NASA Astrophysics Data System (ADS)
Aouzi, M.; El Hafidi, M.; Sakhaf, E. M.
2005-01-01
Using the effective-field theory with correlations (EFT), the effects of a longitudinal field on the magnetic properties of a ferrimagnetic system, consisting of two triangular magnetic sublattices A and B (with a coordination number z=6) with spins SA={1}/{2} and SB={3}/{2}, are investigated. The influence of the crystal-field interaction DB within the sublattice B and the longitudinal applied field on these properties are examined. We determine the total magnetization in absence and under the magnetic field, whereas the initial susceptibility is carried out. The Arrott plots shapes in the (H0/M,M2)-plane are determined. They indicate a region of strong competition between the inter-sublattices (JAB) exchange coupling and the applied field. Other striking features have been revealed in the magnetization behavior especially near the critical and the compensation temperatures.
NASA Astrophysics Data System (ADS)
Walker, H. C.; McEwen, K. A.; Griveau, J.-C.; Eloirdi, R.; Amador, P.; Maldonado, P.; Oppeneer, P. M.; Colineau, E.
2015-05-01
We present bulk property measurements of NpIr, a newly synthesized member of the Np-Ir binary phase diagram, which is isostructural to the noncentrosymmetric pressure-induced ferromagnetic superconductor UIr. Magnetic susceptibility, electronic transport properties at ambient and high pressure, and heat capacity measurements have been performed for temperatures T =0.55 -300 K in a range of magnetic fields up to 14 T and under pressure up to 17.3 GPa. These reveal that NpIr is a moderately heavy fermion Kondo system with strong antiferromagnetic interactions, but there is no evidence of any phase transition down to 0.55 K or at the highest pressure achieved. Experimental results are compared with ab initio calculations of the electronic band structure and lattice heat capacity. An extremely low lattice thermal conductivity is predicted for NpIr at temperatures above 300 K.
S. Ramos de Debiaggi; G. F. Cabeza; C. Deluque Toro; A. M. Monti; S. Sommadossi; A. Fernández Guillermet
2011-01-01
The physico-chemical properties of the intermetallic phases in the Cu–In system have been a matter of considerable theoretical and experimental interest in connection with, i.a., the application of In–Sn alloys as lead-free micro-soldering alloys. Recently, a new binary compound with the chemical formula Cu10In7 has been detected in a study of the ?-phase field. The structure of the Cu10In7 phase
NASA Astrophysics Data System (ADS)
Gladis Anitha, E.; Joseph Vedhagiri, S.; Parimala, K.
2015-04-01
The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 2-amino-5-bromo-6-methyl-4-pyrimidinol (ABrMP) were recorded in the region 4000-400 and 3500-100 cm-1, respectively. The conformational stability, geometrical structure, vibrational frequencies, infrared intensities and Raman activities were carried out by DFT (B3LYP and LSDA) methods with 6-311++G(d,p) basis set. The calculated results show good agreement with observed spectra. The charge delocalization have been analyzed using NBO analysis by LSDA/6-311++G(d,p) level of theory. The NLO properties (?, ?0, ??, ?0 and ?vec) have been computed quantum mechanically. The calculated HOMO and LUMO energies show that, the charge transfer occurs within the molecule. The solvent effects have been calculated using TD-DFT and the results are in good agreement with experimental measurements. The other molecular properties like Mulliken population analysis, electrostatic potential (ESP) and thermodynamic properties of the title compound at the different temperatures have been calculated.
NASA Astrophysics Data System (ADS)
Kichakova, Olga; Kunz, Jutta; Radu, Eugen; Shnir, Yasha
2015-07-01
We investigate the thermodynamics of spherically symmetric black hole solutions in a four-dimensional Einstein-Yang-Mills-SU(2) theory with a negative cosmological constant. Special attention is paid to configurations with a unit magnetic charge. We find that a set of Reissner-Nordström-Anti-de Sitter black holes can become unstable to forming non-Abelian hair. However, the hairy black holes are never thermodynamically favoured over the full set of abelian monopole solutions. The thermodynamics of the generic configurations possessing a noninteger magnetic charge is also discussed.
Liu, Fang-Yu, S.M. Massachusetts Institute of Technology
2014-01-01
This thesis investigates microgrid control stability with respect to thermodynamics behaviors of generation and demand. First, a new integrated microgrid model is introduced. This model consists of a combined cycle power ...
Z. Pakowski; Z. Bartczak; C. Strumio; S. Stenström
1991-01-01
Over 70 equations approximating thermodynamic and transport of water and steam at pressure 1 bar and saturated pressure as well as air at pressure 1 bar were tested against reference data. Their accuracy and relative computing time were reported.
Material property correlations for uranium mononitride
Hayes, Steven Lowe
1989-01-01
linear thermal expansion coefficient), mechanical properties (creep rate, Young's modulus, shear modulus, bulk modulus, Poisson's ratio, and hardness), transport properties (diffusion coefficients, electrical resistivity, and thermal conductivity... Creep Rate Young's Modulus Shear Modulus . Bulk Modulus . . . . . . Poisson's Ratio Hardness. IV TRANSPORT PROPERTY CORRELATIONS Diffusion Coefficient Electrical Resistivity . Thermal Conductivity V THERMODYNAMIC PROPERTY CORRELATIONS...
Myers, A.L.; Minka, C.; Ou, D.Y.
1982-01-01
Experimental data at 30/degree/C are reported for the adsorption of mixtures of benzene and cyclohexane on two types of carbon surface: graphitized carbon and activated charcoal. The properties of the adsorbed solution approach those of bulk liquid at vapor saturation for graphitized carbon, but not for activated charcoal. The mixtures adsorbed on graphitized carbon are nonideal, and the deviations from ideality increase with surface coverage. For activated charcoal, the adsorbed mixtures are nearly ideal at all coverages. Mixture behavior for both adsorbents can be predicted without using experimental data for the adsorbed mixtures. 11 refs.
PROPERTY MANUAL Berkeley Laboratory Property Management
Knowles, David William
Management must approve all assignments of Laboratory equipment to non-laboratory employees. NonPROPERTY MANUAL Issued by Berkeley Laboratory Property Management Lawrence Berkeley National of Property Management Policies · I. Parties and Organizations Responsible for Property · II. Acquiring
Richard, Ryan M; Ball, David W
2009-05-30
Recent studies have suggested that octanitrocubane and heptanitrocubane may be two of the most powerful non-nuclear high-energy materials currently known. Progressive substitution of the hydrogen atoms on cubane for nitroso groups is expected to also produce a new potential high-energy material, which should have thermodynamic properties similar to nitrocubane. In this study we predict optimized structures, vibrational frequencies, enthalpies of formation, and specific enthalpies of combustion for a series of nitrosocubanes ranging from mononitrosocubane to octanitrosocubane. Our results indicate, on the basis of the specific enthalpies of combustion alone, that mononitrosocubane should make the best new high-energy material; however, we speculate that the velocity of detonation of octa- and heptanitrosocubane will make them better high-energy materials. PMID:18819750
NASA Technical Reports Server (NTRS)
Tannehill, J. C.; Mugge, P. H.
1974-01-01
Simplified curve fits for the thermodynamic properties of equilibrium air were devised for use in either the time-dependent or shock-capturing computational methods. For the time-dependent method, curve fits were developed for p = p(e, rho), a = a(e, rho), and T = T(e, rho). For the shock-capturing method, curve fits were developed for h = h(p, rho) and T = T(p, rho). The ranges of validity for these curves fits were for temperatures up to 25,000 K and densities from 10 to the minus 7th power to 10 to the 3d power amagats. These approximate curve fits are considered particularly useful when employed on advanced computers such as the Burroughs ILLIAC 4 or the CDC STAR.
NASA Astrophysics Data System (ADS)
Zhang, Ziying; Zhang, Huizhen; Zhao, Hui; Yu, Zhishui; He, Liang; Li, Jin
2015-04-01
The crystal structures, electronic structures, thermodynamic and mechanical properties of Mg2Ni alloy and its saturated hydride with different Mn-doping contents are investigated using first-principles density functional theory. The lattice parameters for the Mn-doped Mg2Ni alloys and their saturated hydrides decreased with an increasing Mn-doping content because of the smaller atomic size of Mn compared with that of Mg. Analysis of the formation enthalpies and electronic structures reveal that the partial substitution of Mg with Mn reduces the stability of Mg2Ni alloy and its saturated hydride. The calculated elastic constants indicate that, although the partial substitution of Mg with Mn lowers the toughness of the hexagonal Mg2Ni alloy, the charge/discharge cycles are elevated when the Mn-doping content is high enough to form the predicted intermetallic compound Mg3MnNi2.
Murphy, K.; Simon, R.; Phillips, B.; Marsala, J.; Whitlow, E.
1985-08-01
This report covers the development work on the R123a/ETFE (ethyltetrahydro furfuryl ether) pair and an economic analysis of the system. Extensive thermodynamic and physical properties of the R123a/ETFE system were developed. Theoretical analysis of the data was made and showed very good performance. Subsequent testings on equipment not fully developed for R123a/ETFE confirmed this very good performance. The economic analysis showed the system competitive in most areas of the US if improved performance goals (COP = 1.5) can be met. The most important factors in determining the competitiveness are heating to cooling ratios and the relative cost of gas and electric.
Loosli, Frédéric; Berret, Jean-François; Stoll, Serge
2015-01-01
Interaction between engineered nanoparticles and natural organic matter is investigated by measuring the exchanged heat during binding process with isothermal titration calorimetry. TiO2 anatase nanoparticles and alginate are used as engineered nanoparticles and natural organic matter to get an insight into the thermodynamic association properties and mechanisms of adsorption and agglomeration. Changes of enthalpy, entropy and total free energy, reaction stoichiometry and affinity binding constant are determined or calculated at a pH value where the TiO2 nanoparticles surface charge is positive and the alginate exhibits a negative structural charge. Our results indicate that strong TiO2-alginate interactions are essentially entropy driven and enthalpically favorable with exothermic binding reactions. The reaction stoichiometry and entropy gain are also found dependent on the mixing order. Finally correlation is established between the binding enthalpy, the reaction stoichiometry and the zeta potential values ...
Benilova, Iryna; Gallardo, Rodrigo; Ungureanu, Andreea-Alexandra; Castillo Cano, Virginia; Snellinx, An; Ramakers, Meine; Bartic, Carmen; Rousseau, Frederic; Schymkowitz, Joost; De Strooper, Bart
2014-11-01
Missense mutations in alanine 673 of the amyloid precursor protein (APP), which corresponds to the second alanine of the amyloid ? (A?) sequence, have dramatic impact on the risk for Alzheimer disease; A2V is causative, and A2T is protective. Assuming a crucial role of amyloid-A? in neurodegeneration, we hypothesized that both A2V and A2T mutations cause distinct changes in A? properties that may at least partially explain these completely different phenotypes. Using human APP-overexpressing primary neurons, we observed significantly decreased A? production in the A2T mutant along with an enhanced A? generation in the A2V mutant confirming earlier data from non-neuronal cell lines. More importantly, thioflavin T fluorescence assays revealed that the mutations, while having little effect on A?42 peptide aggregation, dramatically change the properties of the A?40 pool with A2V accelerating and A2T delaying aggregation of the A? peptides. In line with the kinetic data, A? A2T demonstrated an increase in the solubility at equilibrium, an effect that was also observed in all mixtures of the A2T mutant with the wild type A?40. We propose that in addition to the reduced ?-secretase cleavage of APP, the impaired propensity to aggregate may be part of the protective effect conferred by A2T substitution. The interpretation of the protective effect of this mutation is thus much more complicated than proposed previously. PMID:25253695
Onken, U.; Rarey-Nies, J.; Gmehling, J. (Universitaet Dortmund (West Germany))
1989-05-01
The Dortmund Data Bank (DDB) was started in 1973 with the intention to employ the vast store of vapor-liquid equilibrium (VLE) data from the literature for the development of models for the prediction of VLE. From the beginning, the structure of the DDB has been organized in such a way that it was possible to take advantage of the full potential of electronic computers. With the experience gained in fitting and processing VLE data, the authors extended the DDB system to other types of mixture properties, i.e., liquid-liquid equilibria (LLE), gas solubilities (GLE), activity coefficients at infinite dilution ({gamma}{sup {infinity}}), heats of mixing h{sup E}, and excess heat capacities. Besides the files for mixture properties, the DDB contains pure-component data and program packages for various applications. New experimental data are checked for consistency before they are stored. For data retrieval user-specified search masks can be used. The data files are available via an online data service and through the Dechema Chemistry Data Series. For the purpose of data correlation and model testing, parameter fitting is performed with an optimization routine (Nelder-Mead). In the past years the DDB system has been successfully employed for the development of prediction methods for VLE, LLE, GLE, {gamma}{sup {infinity}}, and h{sup E} (UNIFAC, mod. UNIFAC, etc.).
NASA Astrophysics Data System (ADS)
Onken, U.; Rarey-Nies, J.; Gmehling, J.
1989-05-01
The Dortmund Data Bank (DDB) was started in 1973 with the intention to employ the vast store of vapor-liquid equilibrium (VLE) data from the literature for the development of models for the prediction of VLE. From the beginning, the structure of the DDB has been organized in such a way that it was possible to take advantage of the full potential of electronic computers. With the experience gained in fitting and processing VLE data, we extended the DDB system to other types of mixture properties, i.e., liquid-liquid equilibria (LLE), gas solubilities (GLE), activity coefficients at infinite dilution ??, heats of mixing ( h E), and excess heat capacities. Besides the files for mixture properties, the DDB contains pure-component data and program packages for various applications. New experimental data are checked for consistency before they are stored. For data retrieval user-specified search masks can be used. The data files are available via an online data service and through the Dechema Chemistry Data Series. For the purpose of data correlation and model testing, parameter fitting is performed with an optimization routine (Nelder-Mead). In the past years the DDB system has been successfully employed for the development of prediction methods for VLE, LLE, GLE, ??, and h E (UNIFAC, mod. UNIFAC, etc.).
Zou, Qi-Chao; Zhang, Shi-Ling; Wang, Shi-Min; Wu, Li-Min
2006-10-01
The thermodynamic properties of poly(methyl methacrylate-co-butyl acrylate-co-cyclo -pentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were investigated by means of inverse gas chromatography (IGC) using 20 different kinds of solvents as the probes. Some thermodynamic parameters, such as molar heats of sorption, weight fraction activity coefficient, Flory-Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions between POSS-contained polymers and solvents and the solubility of the polymers in these solvents. It was found that acetates, aromatic hydrocarbons and hydrocarbon halides were good solvents, n-hexane, ethanol, n-propanol, n-butanol and n-pentanol were moderate solvents, while n-heptane, n-octane, n-nonane, n-decane and methanol were poor solvents for all POSS-contained polymers within the experimental temperature range. Incorporation of POSS in polymer increased the solubility of polymers in solvents, and the more the POSS in polymer was, the better the solubility was and stronger the hydrogen bonding interaction was, but the POSS content in polymers seemed to have no obvious influence on the solubility parameter of polymers. PMID:16846607
Study of thermodynamic properties of SiH4(H2)2 superconductor under high pressure
NASA Astrophysics Data System (ADS)
Durajski, A. P.
2013-02-01
The thermodynamic parameters of the superconducting state for SiH4(H2)2 compound under the pressure at 250 GPa have been investigated. The calculations have been made in the framework of the Eliashberg formalism. In particular, the free energy difference (?F) between the superconducting (S) and normal (N) state, the specific heat (C), as well as, the thermodynamic critical field (HC) have been determined. It has been shown that the considered thermodynamic functions are beyond the BCS predictions; the ratio CS(TC-CNTC)/CNTC decreases from 2.43 to 2.34 with increase of the Coulomb pseudopotential (???0.1,0.3), and the parameter TCCNTC/HC20 increases from 0.140 to 0.145. The numerical results have been supplemented with the interpolation approach.
Gerhard Hummer; Lawrence R. Pratt; Angel E. García; Martin Neumann
1999-01-01
We review the treatment of electrostatic interactions in computer simulations under periodic boundary conditions, with emphasis on Ewald summation. Connections between Ewald summation and reaction field approaches will be made within a unifying picture of electrostatic potentials in Wigner lattices. The calculation of thermodynamic pressures in simulations of polar and ionic media will be discussed. Effects of finite system size
Haohua Tu
2001-01-01
A variety of subjects related to an isolated microdroplet, including precise optical measurement, fundamental light scattering theory, in situ droplet spectroscopy, transport mechanism, solution thermodynamics, and electrical stability, have been studied. A technique based on optical resonance alignment is developed to automate the measurement of the optical parameters for a single component droplet. The technique is able to determine the
M. Lapuerta; O. Armas; J. J. Hernández
1999-01-01
Combustion diagnostic methods based on the in-cylinder pressure signal are extensively used for calculating the heat release law or the burned fuel mass as well as the mean gas temperature from combining both the first principle of thermodynamics and the state equation. In both equations the instantaneous gas composition has great influence, even through the internal energy or through the
NASA Astrophysics Data System (ADS)
Chen, Zhe; Zhang, Peng; Chen, Dong; Wu, Yi; Wang, Mingliang; Ma, Naiheng; Wang, Haowei
2015-02-01
The thermodynamic, elastic, and electronic properties of D022-type Al3V and Al3Nb intermetallics were studied using the first-principle method. The results showed the pressure has profound effects on the structural, mechanical and electronic properties in both Al3V and Al3Nb. Thermodynamically, the formation enthalpies for Al3V and Al3Nb were derived, which agreed well with available experimental and theoretical values. Comparably, Al3Nb was a more stable phase with the more negative Hf than Al3V. Mechanically, the calculated elastic constants showed linearly increasing tendencies, and satisfied the Born's criteria from 0-20 GPa, indicating the mechanically stability of Al3V and Al3Nb under this pressure range. Further, the mechanical parameters (i.e., bulk modulus (B), shear modulus (G), and Young's modulus (E)) were derived using the Voigt-Reuss-Hill (VRH) method, and in good agreement with available experimental results at the ground state. All these parameters presented the linearly increasing dependences on the external pressure. The B/G ratios and Poisson's ratio indicated that the Al3V and Al3Nb crystals should exhibit brittle behavior at 0-20 GPa. Additionally, the bulk modulus can be obtained through fitting the Birch-Murnaghan equation (B0), computing by VRH method (BH), and deriving from the elastic theory (Brelax) in both intermetallics. The uniformity of these calculated bulk moduli in each compound exhibited the excellent reliability and self-consistency. In addition, Debye temperature was estimated from the average sound velocity. The Debye temperature showed an increasing dependence on the pressures. Finally, through density of states analysis, Al3V and Al3Nb were suggested to possess naturally metallic behavior. Under pressures, it was noted that the shapes of peaks and pseudogaps exhibited relative few changes, suggesting Al3V and Al3Nb has kept structurally stable up to 20 GPa. At zero pressure, Al3Nb was considered as a more structurally stable phase with the more number of bonding electrons per atom than Al3V. This conclusion was in consistent with the one drawn from the thermodynamic analysis.
Zhao, Guo-zheng; Lu, Ming
2013-01-01
The B3LYP/6-31G (d) method of density functional theory (DFT) was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. The heat of formation (HOF) and calculated density were estimated to evaluate the detonation properties using Kamlet-Jacobs equations. Thermal stability of 3,5,7,10,12,14,15,16-octanitro- 3,5,7,10,12,14,15,16-octaaza-heptacyclo[7.5.1.1(2,8).0(1,11).0(2,6).0(4,13).0(6,11)]hexadecane (cage-tetranitrotetraazabicyclooctane) was investigated by calculating the bond dissociation energy (BDE) at unrestricted B3LYP/6-31G (d) level. The calculated results show that the N-NO2 bond is a trigger bond during thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to Pna2(1) space group, with cell parameters a=12.840 Å, b=9.129 Å, c=14.346 Å, Z=6 and ?=2.292 g·cm(-3). Both the detonation velocity of 9.96 km·s(-1) and the detonation pressure of 47.47 GPa are better than those of CL-20. According to the quantitative standard of energetics and stability, as a high energy density compound (HEDC), cage-tetranitrotetraazabicyclooctane essentially satisfies this requirement. PMID:22790340