Thermodynamic properties of nitrogen
Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.
1987-01-01
This volume covers the thermodynamic properties of gaseous as well as liquid nitrogen... for temperatures between the triple point and 1500 K, and pressures from 0.01 to 100 MPa. The authors have analyzed and correlated a vast amount of international experimental data leading to these reliable tables that reflect the thermal properties of this important element. Highlighted in this work - and throughout the series - is a new method of statistical evaluation of the reliability of the entire body of experimental data, effectively utilizing modern computer capabilities.
Thermodynamic properties of methane
Sychev, V.V.; Vasserman, A.A.; Golovsky, E.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.
1987-01-01
This book is based on extensively verified material, providing a unified equation of state... calculating tables of properties... and presenting error of calculated - relative to experimental - methane properties. The temperature range spans the triple point to 1000 K, and the pressures extend from 0.1 to 100 MPa. This book examines engineering research, development, and design within the chemical and gas industries.
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.
The Thermodynamic Properties of Cubanite
NASA Technical Reports Server (NTRS)
Berger, E. L.; Lauretta, D. S.; Keller, L. P.
2012-01-01
CuFe2S3 exists in two polymorphs, a low-temperature orthorhombic form (cubanite) and a high-temperature cubic form (isocubanite). Cubanite has been identified in the CI-chondrite and Stardust collections. However, the thermodynamic properties of cubanite have neither been measured nor estimated. Our derivation of a thermodynamic model for cubanite allows constraints to be placed on the formation conditions. This data, along with the temperature constraint afforded by the crystal structure, can be used to assess the environments in which cubanite formation is (or is not) thermodynamically favored.
Thermodynamic properties of minerals
Robie, Richard A.
1962-01-01
In the ten years since the publication of the national Bureau of Standards comprehensive tables of thermochemical properties, by Rossini and other (1952), a very large body of modern calorimetric and equilibrium data has become available. Because of the complex interrelations among many thermochemical data and the necessity for internal consistency among these values, a complete revision of this standard reference is required. This is also true of the summaries of thermochemical data for the sulfides (Richardson and Jeffes 1952) and for the oxides (Coughlin 1954). The following tables present critically selected values for the heat and free energy of formation, the logarithm of the equilibrium constant of formation Log Kf, the entropy and the molar volume, at 298.15°K (25.0°C) and one atmosphere for minerals.
Thermodynamic properties of uranium dioxide
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 reactor safety studies, this revision is prepared for the thermodynamic properties of the uranium dioxide portion of the fuel property section of the report Properties for LMFBR Safety Analysis. Since the original report was issued in 1976, there has been international agreement on a vapor pressure equation for the total pressure over UO/sub 2/, new methods have been suggested for the calculation of enthalpy and heat capacity, and a phase change at 2670 K has been proposed. In this report, 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.
Advanced working fluids: Thermodynamic properties
NASA Astrophysics Data System (ADS)
Lee, Lloyd L.; Gering, Kevin L.
1990-10-01
Electrolytes are used as working fluids in gas fired heat pump chiller engine cycles. To find out which molecular parameters of the electrolytes impact on cycle performance, a molecular theory is developed for calculating solution properties, enthalpies, vapor-liquid equilibria, and engine cycle performance. Aqueous and ammoniac single and mixed salt solutions in single and multisolvent systems are investigated. An accurate correlation is developed to evaluate properties for concentrated electrolyte solutions. Sensitivity analysis is used to determine the impact of molecular parameters on the thermodynamic properties and cycle performance. The preferred electrolytes are of 1-1 valence type, small ion size, high molecular weight, and in strongly colligative cosolvent. The operating windows are determined for a number of absorption fluids of industrial importance.
Thermodynamic properties of sea air
NASA Astrophysics Data System (ADS)
Feistel, R.; Kretzschmar, H.-J.; Span, R.; Hagen, E.; Wright, D. G.; Herrmann, S.
2009-10-01
Very accurate thermodynamic potential functions are available for fluid water, ice, seawater and humid air covering wide ranges of temperature and pressure conditions. They permit the consistent computation of all equilibrium properties as, for example, required for coupled atmosphere-ocean models or the analysis of observational or experimental data. With the exception of humid air, these potential functions are already formulated as international standards released by the International Association for the Properties of Water and Steam (IAPWS), and have been adopted in 2009 for oceanography by IOC/UNESCO. In this paper, we derive a collection of formulas for important quantities expressed in terms of the thermodynamic potentials, valid for typical phase transitions and composite systems of humid air and water/ice/seawater. Particular attention is given to equilibria between seawater and humid air, referred to as ''sea air'' here. In a related initiative, these formulas will soon be implemented in a source-code library for easy practical use. The library is primarily aimed at oceanographic applications but will be relevant to air-sea interaction and meteorology as well. The formulas provided are valid for any consistent set of suitable thermodynamic potential functions. Here we adopt potential functions from previous publications in which they are constructed from theoretical laws and empirical data; they are briefly summarized in the appendix. The formulas make use of the full accuracy of these thermodynamic potentials, without additional approximations or empirical coefficients. They are expressed in the temperature scale ITS-90 and the 2008 Reference-Composition Salinity Scale.
Thermodynamic properties of sea air
NASA Astrophysics Data System (ADS)
Feistel, R.; Wright, D. G.; Kretzschmar, H.-J.; Hagen, E.; Herrmann, S.; Span, R.
2010-02-01
Very accurate thermodynamic potential functions are available for fluid water, ice, seawater and humid air covering wide ranges of temperature and pressure conditions. They permit the consistent computation of all equilibrium properties as, for example, required for coupled atmosphere-ocean models or the analysis of observational or experimental data. With the exception of humid air, these potential functions are already formulated as international standards released by the International Association for the Properties of Water and Steam (IAPWS), and have been adopted in 2009 for oceanography by IOC/UNESCO. In this paper, we derive a collection of formulas for important quantities expressed in terms of the thermodynamic potentials, valid for typical phase transitions and composite systems of humid air and water/ice/seawater. Particular attention is given to equilibria between seawater and humid air, referred to as "sea air" here. In a related initiative, these formulas will soon be implemented in a source-code library for easy practical use. The library is primarily aimed at oceanographic applications but will be relevant to air-sea interaction and meteorology as well. The formulas provided are valid for any consistent set of suitable thermodynamic potential functions. Here we adopt potential functions from previous publications in which they are constructed from theoretical laws and empirical data; they are briefly summarized in the appendix. The formulas make use of the full accuracy of these thermodynamic potentials, without additional approximations or empirical coefficients. They are expressed in the temperature scale ITS-90 and the 2008 Reference-Composition Salinity Scale.
Thermodynamic properties of lanthanum molybdates
NASA Astrophysics Data System (ADS)
Suponitskiy, Yu. L.; Proshina, O. P.; Dyunin, A. G.; Liashenko, S. E.
2016-02-01
The enthalpy of solution of LaOHMoO4 and Cs2MoO4 in aqueous HCl at 298 K has been determined by solution calorimetry, and the standard enthalpy of formation of lanthanum hydroxomolybdate has been calculated. The enthalpies of solution of NaLa(MoO4)2 and Na5La(MoO4)4 in molybdate melt at 973 K have been determined by high-temperature melt solution microcalorimetry, and the high-temperature enthalpies of the double molybdates in the 298-1000 K range have been measured by the mixing method. The standard enthalpies of formation of the double molybdates have been calculated using data available from the literature. The low-temperature heat capacity of NaLa(MoO4)2 in the 60-300 K range has been measured on an adiabatic vacuum calorimeter. The basic thermodynamic properties of NaLa(MoO4)2, Na5La(MoO4)4, and LaOHMoO4 have been calculated.
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.
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 Ar39 Cluster
NASA Astrophysics Data System (ADS)
Eryurek, M.; Guven, M. H.
2007-04-01
The solid-liquid phase transitions of Ar39 cluster was simulated by the microcanonical Molecular Dynamics (MD) and microcanonical Parallel Tempering (PT) Monte Carlo methods using Lennard-Jones potential, and thermodynamic quantities were calculated. All thermodynamic quantities (configurational entropy, thermodynamic temperature, microcanonical heat capacity, potential energy distribution) were evaluated by using multiple histogram method. The same results were found in both simulation methods. The thermodynamic properties of microcanonical results indicate that the caloric curve has S-dent and the negative heat capacity has negative values at the solid-liquid phase transition region. At the same time by using microcanonical results melting temperature, latent heat and entropy change upon melting values were reported and compared with the values reported in the literature and the values calculated from the thermodynamic relations offered for bulk matter and, consistent values were found.
Thermodynamic properties of hydrogen-helium plasmas.
NASA Technical Reports Server (NTRS)
Nelson, H. F.
1972-01-01
Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.
Thermodynamic properties of liquid metals and alloys
NASA Astrophysics Data System (ADS)
Kessel'Man, P. M.; Bykov, A. Yu.; Inshakov, S. A.
1990-11-01
A modified cellular model of liquids is used to develop a method for calculating thermodynamic properties of liquid metals and their alloys, which are widely used in compact modern heat exchange equipment operating at high thermal flux densities. The approach presented herein permits calculation of the properties of metals from various groups by a single consistent technique. Good agreement was found with experimental data for a significant number of liquid metals and their alloys.
Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium
NASA Technical Reports Server (NTRS)
Hunt, J. L.; Boney, L. R.
1973-01-01
Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented.
Thermodynamic properties of dimethylene urethane
NASA Astrophysics Data System (ADS)
Emel'yanenko, V. N.; Turovtsev, V. V.; Orlov, Yu. D.
2015-07-01
Enthalpies of the combustion and formation of crystalline dimethylene urethane (oxazolidin-2-one) are determined via combustion calorimetry. The enthalpy of sublimation is determined via the transpiration method, and the enthalpy of fusion is found by means of differential scanning calorimetry. The temperature dependence of the saturated vapor pressure is measured in the range of 323-353 K. Thermodynamic functions in the ideal gas state are calculated using the rigid rotator-anharmonic oscillator model in the range of T = 298.15-1500 K.
Prediction of Thermodynamic Properties of Alternative Refrigerants
NASA Astrophysics Data System (ADS)
Fukushima, Masato
The use of refrigerant mixtures for R22 alternative has recently been attracted in refrigerating and air conditioning industry. However, there has not been enough information about thermodynamic properties required to analyse the properties of mixtures. In this paper, stressing the adaptability of the modified van der Waals equation of state for refrigerant mixtures, the prediction methods of thermodynamic properties for the a1ternative refrigerant and mixture are explained. Seven generalized equations of state are chosen for the subjects of discussion. Data on R32,R125,R134a and their mixtures are applied to discuss the adaptability of these equations. Resu1ts of calculation using these equations are compared with available experimental and reference data. The optimum binary interaction parameters for those equations of state are a1so 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.
Thermodynamical properties of Strunz's quantum dissipative models
NASA Astrophysics Data System (ADS)
Zen, Freddy P.; Sulaiman, A.
2015-09-01
The existence of the negative of specific heat from quantum dissipative theory is investigated. Strunz's quantum dissipative model will be used in this studies. The thermodynamical properties will be studied starts out from the thermo-dynamic partition function of the dissipative system. The path integral technique is used to calculate the partition function under consideration. The results shows that the specific heat can be negative if the damping parameter more than a half the oscillator frequency and also occur at low temperatures. For damping factor greater than the frequency of harmonic oscillator then specific heat will oscillate at low temperatures and approaching normal conditions at a high temperature.
Prediction of thermodynamic properties of coal derivatives
Donohue, M.D.
1991-10-01
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. In order to get a better understanding of the intermolecular forces and to test some of our recent models, we have performed considerable experimental work. We used FTIR to examine hydrogen bonding interactions between small molecules and between small molecules and polymers. In addition, we investigated experimentally the high pressure phase behavior of ternary and quaternary systems exhibiting polar and hydrogen bonding interactions.
Thermodynamic properties of hydrogen-helium plasmas
NASA Technical Reports Server (NTRS)
Nelson, H. F.
1971-01-01
The thermodynamic properties of an atomic hydrogen-helium plasma are calculated and tabulated for temperatures from 10,000 to 100,000 K as a function of the mass fraction ratio of atomic hydrogen. The tabulation is for densities from 10 to the minus 10th power to 10 to the minus 6th power gm/cu cm and for hydrogen mass fraction ratios of 0, 0.333, 0.600, 0.800, and 1.0, which correspond to pure helium, 50 percent hydrogen per unit volume, 75 percent hydrogen per unit volume, 89 percent hydrogen per unit volume, and pure hydrogen plasmas, respectively. From an appended computer program, calculations can be made at other densities and mass fractions. The program output agrees well with previous thermodynamic property calculations for limiting cases of pure hydrogen and pure helium plasmas.
The thermodynamic properties of benzothiazole and benzoxazole
Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.
1991-08-01
This research program, funded by the Department of Energy, Office of Fossil Energy, Advanced Extraction and Process Technology, provides accurate experimental thermochemical and thermophysical properties for key'' organic diheteroatom-containing compounds present in heavy petroleum feedstocks, and applies the experimental information to thermodynamic analyses of key hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation reaction networks. Thermodynamic analyses, based on accurate information, provide insights for the design of cost-effective methods of heteroatom removal. The results reported here, and in a companion report to be completed, will point the way to the development of new methods of heteroatom removal from heavy petroleum. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for benzothiazole and benzoxazole. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclinded-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Critical property estimates are made for both compounds. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 280 K and near 650 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathways for the removal of the heteratoms by hydrogenolysis. The results obtained in this research are compared with values present in the literature. The failure of a previous adiabatic heat capacity study to see the phase transition in benzothiazole is noted. Literature vibrational frequency assignments were used to calculate ideal gas entropies in the temperature range reported here for both compounds. Resulting large deviations show the need for a revision of those assignments. 68 refs., 6 figs., 15 tabs.
The thermodynamic properties of benzothiazole and benzoxazole
NASA Astrophysics Data System (ADS)
Steele, W. V.; Chirico, R. D.; Knipmeyer, S. E.; Nguyen, A.
1991-08-01
This research program, funded by the Department of Energy, Office of Fossil Energy, Advanced Extraction and Process Technology, provides accurate experimental thermochemical and thermophysical properties for key organic diheteroatom-containing compounds present in heavy petroleum feedstocks, and applies the experimental information to thermodynamic analyses of key hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation reaction networks. Thermodynamic analyses, based on accurate information, provide insights for the design of cost-effective methods of heteroatom removal. The results reported here, and in a companion report to be completed, will point the way to the development of new methods of heteroatom removal from heavy petroleum. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for benzothiazole and benzoxazole. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclinded-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Critical property estimates are made for both compounds. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 280 K and near 650 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathways for the removal of the heteratoms by hydrogenolysis. The results obtained in this research are compared with values present in the literature. The failure of a previous adiabatic heat capacity study to see the phase transition in benzothiazole is noted. Literature vibrational frequency assignments were used to calculate ideal gas entropies in the temperature range reported here for both compounds. Resulting large deviations show the need for a revision of those assignments.
The thermodynamic properties of thianthrene and phenoxathiin
Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.
1993-04-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for thianthrene (Chemical Abstracts registry number [92-85-3]) and phenoxathiin (registry number [262-20-41]). Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, vibrating-tube densitometry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). Critical properties were estimated for both materials based on the measurement results. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 298.15 K and 700 K. The property-measurement results reported here for thianthrene and phenoxathiin provide the first experimental gas-phase Gibbs energies of formation for tricyclic diheteroatom-containing molecules.
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.
Statistical Thermodynamic Properties of Linear Protein Solutions
NASA Astrophysics Data System (ADS)
Li, Li-fen; Liang, Xi-xia; Li, Qian-zhong
2010-04-01
The thermodynamic properties of linear protein solutions are discussed by a statistical mechanics theory with a lattice model. The numerical results show that the Gibbs function of the solution decreases, and the protein chemical potential is enhanced with increase of the protein concentration for dilute solutions. The influences of chain length and temperature on the Gibbs function of the solution as well as the protein chemical potential are analyzed. As an application of the theory, the chemical potentials of some mutants of type I antifreeze proteins are computed and discussed.
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 in Triangular-Lattice Superconductors
NASA Astrophysics Data System (ADS)
Ma, Xixiao; Qin, Ling; Zhao, Huaisong; Lan, Yu; Feng, Shiping
2016-02-01
The study of superconductivity arising from doping a Mott insulator has become a central issue in the area of superconductivity. Within the framework of the kinetic-energy-driven superconducting (SC) mechanism, we discuss the thermodynamic properties in the triangular-lattice cobaltate superconductors. It is shown that a sharp peak in the specific heat appears at the SC transition temperature T_c , and then the specific heat varies exponentially as a function of temperature for temperatures T
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.
Thermodynamic properties and amorphization of Zr-Si melts
NASA Astrophysics Data System (ADS)
Arutyunyan, N. A.; Zaitsev, A. I.; Dunaev, S. F.; Shaposhnikov, N. G.
2016-02-01
The relationship between the thermodynamic properties of Zr-Si liquid alloys and their propensity to amorphization is studied. The temperature-concentration dependences of the thermodynamic properties of melts are presented using the concept of associated solutions. It is shown that the range of amorphization coincides with the range of the predominant concentration of Zr3Si associative groups with low formation entropy.
Thermodynamic approach to nano-properties of cell membrane
NASA Astrophysics Data System (ADS)
Lucia, Umberto
2014-08-01
Biomechanical analyses of DNA have pointed out the connections among forces, thermodynamics and kinetics. The entropy generation approach has been suggested as a thermodynamic approach to evaluate the accessible states for cancer systems, in relation to their specific thermodynamic quantities, including mechanical properties. In this paper, a theoretical approach for the thermodynamic evaluation of the nano-behaviour of the cell wall is suggested. The aim is to provide theoretical bases to the analysis of cells and their properties by applying the thermodynamic approach to irreversibility.
Thermopower Puck for Measurement of Thermodynamic Properties
NASA Astrophysics Data System (ADS)
Vargas, Andres; Fukuda, Ryan; Soliz, Nicholas; Ho, Pei-Chun
2014-03-01
A thermopower puck was created in order to measure the thermoelectric power and thermal conductance of strongly correlated electron materials from 10K to 300K. The puck consists of a 2k Î© resistivity heater and 2 thermometers. The heater is connected to the top of the sample and applies heat until thermal equilibrium is reached. This creates a temperature gradient across the sample and is read by the 2 thermometers, one reading the hotter temperature and the other reading the colder temperature. The wire that is used as the thermal anchor for the high temperature thermometer, which is electrically isolated from thermometer, is also used as one of the leads to measure the thermal voltage produced across the sample. To calibrate the measurement probe, the thermoelectric power and thermal conductance of a nickel sample, which was purchased from Quantum Design, was measured. The data obtained qualitatively agrees with the literature data provided to us by Quantum Design. For future work, we will be using the measurement probe to investigate the thermodynamic properties of intermetallic compounds. Research at CSU-Fresno is supported by NSF DMR-1104544. Felipe Vargas is also supported by Undergraduate Research Grant at CSU Fresno.
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.
Dimensionless thermodynamics: a new paradigm for liquid state properties.
Sanchez, Isaac C
2014-08-01
Equations of state in the van der Waals genre suggest that saturated liquids should adhere to the following corresponding states principle (CSP): saturated liquids at the same reduced density (?R = ?/?c) have comparable dimensionless thermodynamic properties. This CSP is shown to be applicable to a variety of thermodynamic properties that include entropy of vaporization, cohesive energy density, thermal expansion coefficient, isothermal compressibility, thermal pressure coefficient, compressibility factor, temperature coefficient of the vapor pressure, heat capacity difference, and surface tension. For two classes of liquids, all properties rendered dimensionless by the proper choice of scaling variables superpose to form "master curves" that illustrate the CSP. Using scaled particle theory, an improved van der Waals model is developed whose results are compared with existing experimental thermodynamic data in dimensionless form. Properly expressing thermodynamic properties in dimensionless form acts to consolidate and harmonize liquid state properties. PMID:25014632
Thermodynamic properties of doped lanthanum manganites
Hildrum, R.; Brustad, M. . Dept. of Electrochemistry); Wang Changzhen . Div. of Physicochemistry of Metallurgy); Johannesen, O. )
1994-08-01
The thermodynamic properties of the perovskite compounds La[sub 0.8]Sr[sub 0.2]MnO[sub 3] (LSM), La[sub 0.9]Na[sub 0.1]MnO[sub 3] (LNM), and LaMnO[sub 3] (LM) were studied by use of the solid electrolyte galvanic cell method at 1,000 C, 1,050 C, and 1,100 C. Two samples of each compound were investigated as well as decomposed samples of LSM and LNM. The cell assembly was constructed by means of eight small stabilized zirconia tubes and a common Ni/NiO reference electrode. The equilibrium partial pressures of the samples were calculated form the measured EMF values. The results reveal that the equilibrium pO[sub 2] of LM appears to be one or two orders of magnitude lower than that of LSM and LNM, respectively, which means that LM is more stable than the doped perovskites. The variation in the standard free energy with temperature for the perovskite decomposition reaction was calculated from the pO[sub 2] equilibrium values, i.e. [Delta]G[degree]d (LSM) = 140.86 [minus] 0.05199T kJ/mole and [Delta]G[degree]d (LNM) = 106.06 [minus] 0.02572T kJ/mole. On the basis of the above equations, the reaction enthalpy and entropy changes were calculated. Perovskite oxides have received considerable attention in recent years for their use as cathodes in solid oxide fuel cells.
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.
Thermodynamic properties of UF6 at high temperatures
NASA Technical Reports Server (NTRS)
Hassan, H. A.; Deese, J. E.
1974-01-01
The equilibrium composition and the thermodynamic properties of the mixture resulting from the decomposition of uranium hexafluoride is calculated for temperatures ranging from 600 K to 4000 K at pressures from 0.01 atmospheres to 10 atmospheres.
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)
Thermodynamic Properties and Thermodynamic Geometries of Black p-Branes
NASA Astrophysics Data System (ADS)
Yi-Huan, Wei; Xiao, Cui; Jia-Xin, Zhao
2016-01-01
The heat capacity and the electric capacitance of the black p-branes (BPB) are generally defined, then they are calculated for some special processes. It is found that the Ruppeiner thermodynamic geometry of BPB is flat. Finally, we give some discussions for the flatness of the Ruppeiner thermodynamic geometry of BPB and some black holes. Supported by National Natural Science Foundation of China under Grant No. 201210782
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.
Thermodynamical properties of graphene in noncommutative phaseâ€“space
Santos, Victor; Maluf, R.V.; Almeida, C.A.S.
2014-10-15
We investigated the thermodynamic properties of graphene in a noncommutative phaseâ€“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.
Thermodynamic properties and phase transitions in CO2 molecular clusters
NASA Technical Reports Server (NTRS)
Etters, R. D.; Flurchick, K.; Pan, R. P.; Chandrasekharan, V.
1981-01-01
The thermodynamic properties of (CO2)N molecular aggregates of size N between 2 and 13 have been investigated. These crystallites exhibit well defined orientational order-disorder rotational transitions accompanied by a structural transition into a plastic crystallite phase. In addition, they exhibit melting and disassociation transitions. It is shown that the interpretation of experimental data, based upon dimer properties, depends crucially on these results. Equilibrium structures and orientations are also given.
Computer programs for thermodynamic and transport properties of hydrogen
NASA Technical Reports Server (NTRS)
Hall, W. J.; Mc Carty, R. D.; Roder, H. M.
1968-01-01
Computer program subroutines provide the thermodynamic and transport properties of hydrogen in tabular form. The programs provide 18 combinations of input and output variables. This program is written in FORTRAN 4 for use on the IBM 7044 or CDC 3600 computers.
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)Â Â 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
NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species
NASA Technical Reports Server (NTRS)
McBride, Bonnie J.; Zehe, Michael J.; Gordon, Sanford
2002-01-01
This report documents the library of thermodynamic data used with the NASA Glenn computer program CEA (Chemical Equilibrium with Applications). This library, containing data for over 2000 solid, liquid, and gaseous chemical species for temperatures ranging from 200 to 20,000 K, is available for use with other computer codes as well. The data are expressed as least-squares coefficients to a seven-term functional form for C((sup o)(sub p)) (T) / R with integration constants for H (sup o) (T) / RT and S(sup o) (T) / R. The NASA Glenn computer program PAC (Properties and Coefficients) was used to calculate thermodynamic functions and to generate the least-squares coefficients. PAC input was taken from a variety of sources. A complete listing of the database is given along with a summary of thermodynamic properties at 0 and 298.15 K.
Composition and thermodynamic properties of thermal plasma with condensed phases
NASA Astrophysics Data System (ADS)
Coufal, O.; Å½ivnÃ½, O.
2011-01-01
The initial relations of a method for calculating the composition and thermodynamic properties of a closed heterogeneous system in thermodynamic equilibrium at constant pressure and temperature are given. The gaseous phase is always present in the system, and substances in the condensed state can also be present, which are divided into several condensed phases. The essence of the method consists in the minimizing the Gibbs energy of a system in ideal state. The application possibilities of the method described are discussed in detail. The main aim of the article is to provide solutions to problems arising in the calculations of composition and thermodynamic properties. These problems are not only of physico-chemical nature but they also relate to the numerical calculations and stability. The nature of the problems is general and independent of computation method.
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.
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 by non-calorimetric methods. Final report
Steele, W.V.; Chirico, R.D.; Collier, W.B.; Strube, M.M.; Klots, T.D. |
1992-12-31
This research program provided a valuable complement to the experimental programs currently in progress at NIPER for the Advanced Research and Technology Development (AR and TD) and Advanced Exploration and Process Technology (AEPT) divisions of the Department of Energy. These experimental programs are focused on the calorimetric determination of thermodynamic properties of key polynuclear heteroatom-containing aromatic molecules. The project for the Office of Energy Research focused on the non-calorimetric determination of thermodynamic properties through the extension of existing correlation methodologies and through molecular spectroscopy with statistical mechanics. The paper discusses the following studies: Group-contribution approach for polycyclic aromatic hydrocarbons (naphthalene, phenanthrene, anthracene, pyrene, 3-methylphenanthrene, benzoquinolines, biphenyl/hydrogen system); Group-contribution approach for key monocyclic organic compounds; Molecular spectroscopy and statistical mechanics; and Thermophysical property correlations.
Predicting Thermodynamic Properties of PBXTHs with New Quantum Topological Indexes
Peng, Guowen; Yu, Limei
2016-01-01
Novel group quantitative structure-property relationship (QSPR) models on the thermodynamic properties of PBXTHs were presented, by the multiple linear regression (MLR) analysis method. Four thermodynamic properties were studied: the entropy (SÎ¸), the standard enthalpy of formation (Î”fHÎ¸), the standard Gibbs energy of formation (Î”fGÎ¸), and the relative standard Gibbs energy of formation (Î”RGÎ¸). The results by the formula indicate that the calculated and predicted data in this study are in good agreement with those in literature and the deviation is within the experimental errors. To validate the estimation reliability for internal samples and the predictive ability for other samples, leave-one-out (LOO) cross validation (CV) and external validation were performed, and the results show that the models are satisfactory. PMID:26900689
Thermodynamic properties of bulk and confined water
Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H. Eugene
2014-11-14
The thermodynamic response functions of water display anomalous behaviors. We study these anomalous behaviors in bulk and confined water. We use nuclear magnetic resonance (NMR) to examine the configurational specific heat and the transport parameters in both the thermal stable and the metastable supercooled phases. The data we obtain suggest that there is a behavior common to both phases: that the dynamics of water exhibit two singular temperatures belonging to the supercooled and the stable phase, respectively. One is the dynamic fragile-to-strong crossover temperature (T{sub L} â‰ƒ 225Â K). The second, T{sup *} âˆ¼ 315 Â± 5Â K, is a special locus of the isothermal compressibility K{sub T}(T, P) and the thermal expansion coefficient Î±{sub P}(T, P) in the Pâ€“T plane. In the case of water confined inside a protein, we observe that these two temperatures mark, respectively, the onset of protein flexibility from its low temperature glass state (T{sub L}) and the onset of the unfolding process (T{sup *})
Simple estimation of thermodynamic properties of Yukawa systems.
Khrapak, S A; Khrapak, A G; Ivlev, A V; Morfill, G E
2014-02-01
A simple analytical approach to estimate thermodynamic properties of model Yukawa systems is presented. The approach extends the traditional Debye-HÃ¼ckel theory into the regime of moderate coupling and is able to qualitatively reproduce thermodynamics of Yukawa systems up to the fluid-solid phase transition. The simplistic equation of state (pressure equation) is derived and applied to the hydrodynamic description of the longitudinal waves in Yukawa fluids. The relevance of this study to the topic of complex (dusty) plasmas is discussed. PMID:25353581
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.
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.
Thermodynamic properties of highly undercooled liquid TiAl alloy
NASA Astrophysics Data System (ADS)
Wang, N.; Wei, B.
2002-05-01
The specific heat of an undercooled liquid TiAl alloy was measured by an electromagnetic levitation drop calorimeter and the related thermodynamic properties, difference in Gibbs free energy and change in entropy are calculated based on the experimental results and some well known models. Under the containerless processing condition, the liquid alloy was undercooled by up to 219 K (0.122TL). The change in enthalpy shows a linear relationship with the temperature and a nearly constant specific heat was determined even though this alloy was undercooled far below its liquidus temperature. The calculated results of the thermodynamic properties reveal that even though semiquantitative models fit with the experimental curve of the difference in Gibbs free energy well, they lead to different degrees of deviation in the entropy difference calculation.
Thermodynamic properties and diffusion of water + methane binary mixtures
Shvab, I.; Sadus, Richard J.
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 298â€“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.
Thermodynamic properties and diffusion of water + methane binary mixtures
NASA Astrophysics Data System (ADS)
Shvab, I.; Sadus, Richard J.
2014-03-01
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.
Yigzawe, Tesfaye M; Sadus, Richard J
2013-01-28
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. PMID:23387601
Thermodynamic properties and diffusion of water + methane binary mixtures.
Shvab, I; Sadus, Richard J
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. PMID:24628180
Thermodynamic properties of nitrogen gas from sound velocity measurements
NASA Technical Reports Server (NTRS)
Younglove, B. A.
1979-01-01
Thermodynamic properties of nitrogen gas have been calculated from 80 K to 350 K and at pressures to 10 bar from sound velocity measurements and existing P-V-T data using multiproperty fitting techniques. These new data are intended to improve existing predictive capability of the equation of state in the low density region needed for use with the NASA-Langley National Transonics Facility.
Coefficients for calculating thermodynamic and transport properties of individual species
NASA Technical Reports Server (NTRS)
Mcbride, Bonnie J.; Gordon, Sanford; Reno, Martin A.
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 integration constants for H(sup 0)(T) and S(sup 0)(T). For each species the integration constant for H(sup 0)(T) includes the heat of formation. Transport properties have a different functional form. The temperature range for most of the data is 300 to 5000 K, although some of the newer thermodynamic data have a range of 200 to 6000 K. Because the species are mainly possible products of reaction, the data are useful for chemical equilibrium and kinetics computer codes. Much of the data has been distributed for several years with the NASA Lewis equilibrium program CET89. The thermodynamic properties of the reference elements were updated along with about 175 species that involve the elements carbon, hydrogen, oxygen, and nitrogen. These sets of data will be distributed with the NASA Lewis personal computer program for calculating chemical equilibria, CETPC.
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.
Ideal Gas Thermodynamic Properties of Sulphur Heterocyclic Compounds
NASA Astrophysics Data System (ADS)
Dorofeeva, O. V.; Gurvich, L. V.
1995-05-01
The available structural parameters, fundamental frequencies and enthalpies of formation for thiirane, thiirene, thietane, 2H-thiete, 1,2-dithiete, tetrahydrothiophene, 2,3-dihydrothiophene, 2,5-dihydrothiophene, thiophene, 1,2-dithiolane, 1,3-dithiolane, 1,2.4-trithiolane, tetrahydro-2H-thiopyran, 5,6-dihydro-2H-thiopyran, 1,3-dithiane, 1,4-dithiane, 1,4-dithiin, 1,3,5-trithiane, thiepane and 1,3,5,7-tetrathiocane were critically evaluated and recommended values were selected. Molecular constants and enthalpies of formation for some of the molecules were estimated, as experimental values for these compounds are not available. Using the rigid-rotor harmonic-oscillator approximation, this information was used to calculate the chemical thermodynamic functions, Cp?, S°, -(G°-H0?)/T, H°-H0?, and the properties of formation, ?f H°, ?f G°, log Kf?, to 1500 K in the ideal gas state at a pressure of 1 bar. The contributions to the thermodynamic properties of compounds having inversion motion (thietane, 2,3- and 2,5-dihydrothiophene) or pseudo-rotation (tetrahydrothiophene) have been computed by employing a partition function formed by the summation of the inversional or pseudo-rotational energy levels. These energy levels have been calculated by solving the wave equation using appropriate potential functions. The calculated values of the thermodynamic functions are compared with those reported in other works. Comparison with experimental data, where such are available, is also presented. The thermodynamic properties for twelve of the compounds are reported for the first time.
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.
Anomalous thermodynamic properties of ice XVI and metastable hydrates
NASA Astrophysics Data System (ADS)
Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki
2016-02-01
A new ice polymorph, called ice XVI, has recently been discovered experimentally by extracting the guest molecules from Ne hydrate. The ice and its filled form (clathrate hydrate) have a unique network topology which results in several interesting properties. Here we provide a theoretical method to calculate thermodynamic properties of a semiopen system in equilibrium with guest gas and thus occupancy of the guest can be varied with temperature and pressure. Experimental observations such as the disappearance of negative thermal expansivity and contraction of the host lattice upon encaging guest molecules are well reproduced, and those behaviors are elucidated in terms of the free energy of cage occupation and its temperature and pressure dependence. We propose an application of the method for preparing ice XVI to create metastable clathrate hydrates having intriguing properties with much lower occupancy of guest molecules than that at equilibrium, which otherwise cannot form.
Thermodynamic properties of magnetic strings on a square lattice
NASA Astrophysics Data System (ADS)
Mol, Lucas; Oliveira, Denis Da Mata; Bachmann, Michael
2015-03-01
In the last years, spin ice systems have increasingly attracted attention by the scientific community, mainly due to the appearance of collective excitations that behave as magnetic monopole like particles. In these systems, geometrical frustration induces the appearance of degenerated ground states characterized by a local energy minimization rule, the ice rule. Violations of this rule were shown to behave like magnetic monopoles connected by a string of dipoles that carries the magnetic flux from one monopole to the other. In order to obtain a deeper knowledge about the behavior of these excitations we study the thermodynamics of a kind of magnetic polymer formed by a chain of magnetic dipoles in a square lattice. This system is expected to capture the main properties of monopole-string excitations in the artificial square spin ice. It has been found recently that in this geometry the monopoles are confined, but the effective string tension is reduced by entropic effects. To obtain the thermodynamic properties of the strings we have exactly enumerated all possible string configurations of a given length and used standard statistical mechanics analysis to calculate thermodynamic quantities. We show that the low-temperature behavior is governed by strings that satisfy ice rules. Financial support from FAPEMIG and CNPq (Brazilian agencies) are gratefully acknowledged.
Thermodynamic and structural properties of Bi-based liquid alloys
NASA Astrophysics Data System (ADS)
Yadav, S. K.; Jha, L. N.; Adhikari, D.
2015-10-01
Thermodynamic and microscopic structural properties of two Bi-based liquid alloys, such as In-Bi at 900 K and Tl-Bi at 750 K have been studied employing the regular associated solution model. We have estimated the mole fractions of the complexes and the free monomers assuming the existence of complexes In2 Bi in In-Bi melt and TlBi in Tl-Bi melt. The thermodynamic properties have been studied by computing the Gibbs free energy of mixing, enthalpy of mixing, entropy of mixing and activities of the monomers. The compositional contributions of the heat associated with the formation of complexes and the heat of mixing of the monomers to the net enthalpy change has also been studied. The structural properties of the liquid alloys have been studied by computing concentration fluctuation in the long-wavelength limit, chemical short-range order parameter and the ratio of mutual to intrinsic diffusion coefficients. For both of the alloy systems, the theoretical as well as the experimental values of SCC (0) are found to be lower than the corresponding ideal values over the whole composition range, indicating the hetero-coordinating nature of Bi-In and Bi-Tl alloy melts. All the interaction energy parameters are found to be negative and temperature dependent, and both the alloy systems are found to be weakly interacting.
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.
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Astrophysics Data System (ADS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1987-08-01
New, improved curve fits for the thermodynamic properties of equilibrium air have been developed. The curve fits are for pressure, speed of sound, temperature, entropy, enthalpy, density, and internal energy. These curve fits can be readily incorporated into new or existing computational fluid dynamics codes if real gas effects are desired. The curve fits are constructed from 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. These improvements are 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 -7 to 10 to the 3d power amagats.
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Technical Reports Server (NTRS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1987-01-01
New, improved curve fits for the thermodynamic properties of equilibrium air have been developed. The curve fits are for pressure, speed of sound, temperature, entropy, enthalpy, density, and internal energy. These curve fits can be readily incorporated into new or existing computational fluid dynamics codes if real gas effects are desired. The curve fits are constructed from 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. These improvements are 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 -7 to 10 to the 3d power amagats.
Interaction potentials and thermodynamic properties of two component semiclassical plasma
Ramazanov, T. S.; Moldabekov, Zh. A.; Ismagambetova, T. N.; Gabdullin, M. T.
2014-01-15
In this paper, the effective interaction potential in two component semiclassical plasma, taking into account the long-range screening and the quantum-mechanical diffraction effects at short distances, is obtained on the basis of dielectric response function method. The structural properties of the semiclassical plasma are considered. The thermodynamic characteristics (the internal energy and the equation of state) are calculated using two methods: the method of effective potentials and the method of micropotentials with screening effect taken into account by the Ornstein-Zernike equation in the HNC approximation.
Thermodynamic and optical properties of plasma, metals, and dielectrics
NASA Astrophysics Data System (ADS)
Boiko, Iu. V.; Grishin, Iu. M.; Kamrukov, A. S.; Kovalenko, L. V.; Chuvashev, S. N.
The handbook contains analytically derived data on the principal thermodynamic and optical properties of the plasma of a variety of metals and dielectrics. In particular, data are included on the partial composition, degree of ionization, pressure, internal energy, effective adiabatic exponent, absorption coefficients, and Rosseland-averaged radiation mean free path of the plasma of metals and dielectrics at temperatures between 1000 and 10 exp 6 K and plasma densities of 10 exp -4 to 1 kg/cu m. The materials covered include copper, stainless steel, tungsten, molybdenum, tantalum, zirconium, chromium, niobium, nickel, silicon, ZrO2, SiO2, Teflon, Plexiglas, textolite, polyformaldehyde, and caprolactum
Thermodynamic properties of real gases and BWR equation of state
NASA Astrophysics Data System (ADS)
VestfÃ¡lovÃ¡, 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.
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.
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.
Chemical and Thermodynamic Properties at High Temperatures: A Symposium
NASA Technical Reports Server (NTRS)
Walker, Raymond F.
1961-01-01
This book contains the program and all available abstracts of the 90' invited and contributed papers to be presented at the TUPAC Symposium on Chemical and Thermodynamic Properties at High Temperatures. The Symposium will be held in conjunction with the XVIIIth IUPAC Congress, Montreal, August 6 - 12, 1961. It has been organized, by the Subcommissions on Condensed States and on Gaseous States of the Commission on High Temperatures and Refractories and by the Subcommission on Experimental Thermodynamics of the Commission on Chemical Thermodynamics, acting in conjunction with the Organizing Committee of the IUPAC Congress. All inquiries concerning participation In the Symposium should be directed to: Secretary, XVIIIth International Congress of Pure and Applied Chemistry, National Research Council, Ottawa, 'Canada. Owing to the limited time and facilities available for the preparation and printing of the book, it has not been possible to refer the proofs of the abstracts to the authors for checking. Furthermore, it has not been possible to subject the manuscripts to a very thorough editorial examination. Some obvious errors in the manuscripts have been corrected; other errors undoubtedly have been introduced. Figures have been redrawn only when such a step was essential for reproduction purposes. Sincere apologies are offered to authors and readers for any errors which remain; however, in the circumstances neither the IUPAC Commissions who organized the Symposium, nor the U. S. Government Agencies who assisted in the preparation of this book can accept responsibility for the errors.
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.
Thermodynamic and kinetic properties of some diatomic gases
NASA Astrophysics Data System (ADS)
Holbrook, Robert Thomas, III
1997-11-01
In this work, the thermodynamic and kinetic properties of some diatomic gases are calculated and analyzed. In chapter 1, the partition functions of the species composing a dissociating and ionizing iodine vapor, specifically those for homonuclear diatomic 127I127I molecules, 127I atoms, 127I+ ions, and free electrons, are calculated. These partition functions are subsequently used in statistical mass action equations to determine the local thermal equilibrium dissociation degree a and the ionization degree Ï† of the iodine vapor over the temperature range 700 <= T/ /le 12000 K for total atomic number densities nA = 1014, 1016, 1018, and 1020 cm-3. With the equilibrium composition of the iodine vapor so specified and the partition functions, the thermodynamic properties of the iodine vapor are calculated for 700 <= T/ /le 12000 K from statistical thermodynamic equations for the four values of the total number density. In chapter 2, the statistical-mechanical treatment is extended to the more complicated cases of gas systems based on the rare earth halide molecules, DyF, HoF, and TmF. Such systems are composed of seven different species: LnF and F2 molecules (Lnâ‰¡Dy, Ho, and Tm), LnF+ molecular ions, Ln and F atoms, LnF+ atomic ions, and free electrons. Once again, the partition functions are calculated for the various species and used in statistical expressions to determine the local thermal equilibrium compositions and thermodynamic properties of the LnF-based gas mixtures for the temperature range 3000 <= T/ /le 9000 K and initial molecular number densities 1014, 1016, and 1018 cm-3. Finally, in chapter 3, the Monte Carlo trajectory method is used to study the probabilities P(Vr, b, v1, J1, v2, J2) for dissociation via collisions between two ground electronic state X1Î£(0g+) I2 molecules. The two molecules interact with an impact parameter b and a relative speed Vr. The incident molecule is in the vibrational-rotational state specified by the vibrational quantum number v1 and the rotational quantum number J1 while the target molecule is in the state specified by the quantum numbers v2 and J2.
Thermodynamic properties of pulverized coal during rapid heating devolatilization processes
Proscia, W.M.; Freihaut, J.D.; Rastogi, S.; Klinzing, G.E.
1994-07-01
The thermodynamic properties of coal under conditions of rapid heating have been determined using a combination of UTRC facilities including a proprietary rapid heating rate differential thermal analyzer (RHR-DTA), a microbomb calorimeter (MBC), an entrained flow reactor (EFR), an elemental analyzer (EA), and a FT-IR. The total heat of devolatilization, was measured for a HVA bituminous coal (PSOC 1451D, Pittsburgh No. 8) and a LV bituminous coal (PSOC 1516D, Lower Kittaning). For the HVA coal, the contributions of each of the following components to the overall heat of devolatilization were 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 coal and char samples was performed at the University of Pittsburgh using a PC-based image analysis system, BET apparatus, helium pcynometer, and mercury porosimeter. The bulk density, true density, CO{sub 2} surface area, pore volume distribution, and particle size distribution as a function of extent of reaction are reported for both the HVA and LV coal. Analyses of the data were performed to obtain the fractal dimension of the particles as well as estimates for the external surface area. The morphological data together with the thermodynamic data obtained in this investigation provides a complete database for a set of common, well characterized coal and char samples. This database can be used to improve the prediction of particle temperatures in coal devolatilization models. Such models are used both to obtain kinetic rates from fundamental studies and in predicting furnace performance with comprehensive coal combustion codes. Recommendations for heat capacity functions and heats of devolatilization for the HVA and LV coals are given. Results of sample particle temperature calculations using the recommended thermodynamic properties are provided.
ERIC Educational Resources Information Center
Goldblatt, Steven M.
In this chapter on decisions made by federal and state courts during 1983 concerning school property it is noted that no new trends emerged during the year. Among the topics addressed are the extent of school board authority over property use and other property matters; the attachment and detachment of land from school district holdings; school…
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 boardâ€¦
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…
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 Ï† _{{AiB}}(i) of solvated clusters, the extent of solvation of the polymer Î¦solv, the solvation transition lines T_{solv}(Ï† _{{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.
Thermodynamic properties for polycyclic systems by non-calorimetric methods
Steele, W.V.; Chirico, R.D.; Klots, T.D.
1993-03-01
A detailed vibrational spectroscopic study of furan, pyrrole, and thiophene has been completed. These compounds form part of the base of five-membered ring systems on which the rest of the research program will be built Several methyl-substituted derivatives were also studied. The results will be used to confirm the model for alkyl- substitution in the ring systems. Gas-phase spectra and fundamental- frequency assignments were completed for 2,3- and 2,5-dihydrofuran. Those compounds initiate work on ring-puckering within the research program. A paper describing the need for third virial estimation, when using the virial equation of state to derive thermodynamic properties at pressures greater than 1 bar was completed.
Temperature-dependent thermodynamic properties of refractory metals: Nonempirical study
NASA Astrophysics Data System (ADS)
Davidov, Genady; Fuks, David; Dorfman, Simon
1996-06-01
The second and fourth moments of the phonon spectrum are calculated for the refractory metals Mo and W, with the effective interaction potentials fitted to the results of the local density approximation calculations. The temperature dependence of the Debye temperature is discussed. It is shown that the obtained potentials give a good agreement of cohesive properties with the data calculated from the universal function of Rose et al. [Phys. Rev. B 29, 2963 (1984)]. The Gibbs-Bogoliubov inequality and the variational procedure of Ross [J. Chem. Phys. 71, 1567 (1979)] are used for the calculations of the temperature dependence of free energy in liquid tungsten. The calculated thermodynamic functions of solid and liquid phases are employed to determine the melting temperature.
Thermodynamic properties derived from the free volume model of liquids
NASA Technical Reports Server (NTRS)
Miller, R. I.
1974-01-01
An equation of state and expressions for the isothermal compressibility, thermal expansion coefficient, heat capacity, and entropy of liquids have been derived from the free volume model partition function suggested by Turnbull. The simple definition of the free volume is used, and it is assumed that the specific volume is directly related to the cube of the intermolecular separation by a proportionality factor which is found to be a function of temperature and pressure as well as specific volume. When values of the proportionality factor are calculated from experimental data for real liquids, it is found to be approximately constant over ranges of temperature and pressure which correspond to the dense liquid phase. This result provides a single-parameter method for calculating dense liquid thermodynamic properties and is consistent with the fact that the free volume model is designed to describe liquids near the solidification point.
Note on electrical and thermodynamic properties of isolated horizons
NASA Astrophysics Data System (ADS)
Chen, Gerui; Wu, Xiaoning; Gao, Sijie
2015-03-01
The electrical laws and Carnot cycle of isolated horizons (IH) are investigated in this paper. We establish Ohm's law and Joule's law of isolated horizons and find that the conceptual picture of black holes (membrane paradigm) can also apply to this kind of quasilocal black holes. We also investigate the geometrical properties near nonrotating IHs and find that under the first-order approximation of r , there exist a Killing vector ??u/ and a Hamiltonian conjugate to it, so this vector can be thought to be a physical observer. We calculate the energy as measured at infinity of a particle at rest outside a nonrotating IH, and we use this result to construct a reversible Carnot cycle with the isolated horizon as a cold reservoir, which confirms the thermodynamic nature of isolated horizons.
Thermodynamic properties for polycyclic systems by non-calorimetric methods
NASA Astrophysics Data System (ADS)
Steele, W. V.; Chirico, R. D.; Klots, T. D.
1993-03-01
A detailed vibrational spectroscopic study of furan, pyrrole, and thiophene has been completed. These compounds form part of the base of five-membered ring systems on which the rest of the research program will be built. Several methyl-substituted derivatives were also studied. The results will be used to confirm the model for alkyl-substitution in the ring systems. Gas-phase spectra and fundamental frequency assignments were completed for 2,3- and 2,5-dihydrofuran. Those compounds initiate work on ring-puckering within the research program. A paper describing the need for third virial estimation, when using the virial equation of state to derive thermodynamic properties at pressures greater than 1 bar was completed.
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).
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Astrophysics Data System (ADS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1986-06-01
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
Spencer, Elinor; Huang, Baiyu; Parker, Stewart F.; Kolesnikov, Alexander I; Ross, Dr. Nancy; Woodfield, Brian
2013-01-01
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.
Thermodynamic properties of hydrate phases immersed in ice phase
NASA Astrophysics Data System (ADS)
Belosludov, V. R.; Subbotin, O. S.; Krupskii, D. S.; Ikeshoji, T.; Belosludov, R. V.; Kawazoe, Y.; Kudoh, J.
2006-01-01
Thermodynamic properties and the pressure of hydrate phases immersed in the ice phase with the aim to understand the nature of self-preservation effect of methane hydrate in the framework of macroscopic and microscopic molecular models was studied. It was show that increasing of pressure is happen inside methane hydrate phases immersed in the ice phase under increasing temperature and if the ice structure does not destroy, the methane hydrate will have larger pressure than ice phase. This is because of the thermal expansion of methane hydrate in a few times larger than ice one. The thermal expansion of the hydrate is constrained by the thermal expansion of ice because it can remain in a region of stability within the methane hydrate phase diagram. The utter lack of preservation behavior in CS-II methane- ethane hydrate can be explain that the thermal expansion of ethane-methane hydrate coincide with than ice one it do not pent up by thermal expansion of ice. The pressure and density during the crossing of interface between ice and hydrate was found and dynamical and thermodynamic stability of this system are studied in accordance with relation between ice phase and hydrate phase.
The thermodynamic properties of 2,3-benzothiophene
Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Steele, W.V.
1991-01-01
Upgrading of heavy fossil fuels is normally done by hydrotreating in the presence of catalysts at 5 to 15 MPa pressure of hydrogen and 575 to 700 K. The efficient use of expensive hydrogen in this process is essential to the economic viability of alternative fuel sources (heavy petroleum, tar sands, shale oil, and the products of the liquefaction of coal). 2,3-Benzothiophene is widely used as a model compound in catalyst-comparison and kinetic studies of the hydrodesulfurization (HDS) mechanism. To perform a thermodynamic analysis of the 2,3-benzothiophene/hydrogen reaction network at the process temperatures, Gibbs energies of reaction at those high temperatures are required for the molecules involved. Measurements leading to the calculation of the ideal-gas thermodynamic properties for 2,3-benzothiophene are reported. Experimental methods included adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). The critical temperature and critical density were determined with the d.s.c., and the critical pressure was derived. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for selected temperatures between 260 K and 750 K. These values were derived by combining the reported measurements with values published previously for the enthalpy of combustion, the enthalpy of fusion, and the absolute entropy and enthalpy of the liquid at the triple-point temperature. Measured and derived quantities were compared with available literature values. 55 refs., 6 figs., 13 tabs.
Non-BCS thermodynamic properties of H2 S superconductor
NASA Astrophysics Data System (ADS)
Durajski, Artur P.; Szcze&¸sacute; niak, Rados?aw; Li, Yinwei
2015-08-01
The present paper determines the thermodynamic properties of the superconducting state in the H2S compound. The values of the pressure from 130 GPa to 180 GPa were taken into consideration. The calculations were performed in the framework of the Eliashberg formalism. In the first step, the experimental course of the dependence of the critical temperature on the pressure was reproduced: TC ? < 31, 88 > K, whereas the Coulomb pseudopotential equal to 0.15 was adopted. Next, the following quantities were calculated: the order parameter at the temperature of zero Kelvin (? (0)), the specific heat jump at the critical temperature (?C (TC) ?CS (TC) -CN (TC)), and the thermodynamic critical field (HC (0)). It was found that the values of the dimensionless ratios: R? ? 2 ? (0) /kBTC , RC ? ?C(TC) /CN (TC) , and RH ?TCCN (TC) / HC2(0) deviate from the predictions of the BCS theory: R? ? < 3.64, 4.16 > , RC ? < 1.59, 2.24 > , and RH ? < 0.144, 0.163 > . Generalizing the results on the whole family of the HnS -type compounds, it was shown that the maximum value of the critical temperature can be equal to ˜290 K, while R?,RC and RH adopt the following values: 6.53, 3.99, and 0.093, respectively.
NASA Technical Reports Server (NTRS)
Nguyen, Huy H.; Martin, Michael A.
2004-01-01
The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to generate property tables from existing property packages and a method to facilitate the accurate interpretation of fluid thermodynamic property data from those tables. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package. The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.
NASA Technical Reports Server (NTRS)
Gordon, S.
1982-01-01
Thermodynamic and transport combustion properties were calculated for a wide range of conditions for the reaction of hydrocarbons with air. Three hydrogen-carbon atom ratios (H/C = 1.7, 2.0, 2.1) were selected to represent the range of aircraft fuels. For each of these H/C ratios, combustion properties were calculated for the following conditions: Equivalence ratio: 0, 0.25, 0.5, 0.75, 1.0, 1.25 Water - dry air mass ratio: 0, 0.03 Pressure, kPa: 1.01325, 10.1325, 101.325, 1013.25, 5066.25 (or in atm: 0.01, 0.1, 1, 10, 50) Temperature, K: every 10 degrees from 200 to 900 K; every 50 degrees from 900 to 3000 K Temperature, R: every 20 degrees from 360 to 1600 R; very 100 degrees from 1600 to 5400 R. The properties presented are composition, density, molecular weight, enthalphy, entropy, specific heat at constant pressure, volume derivatives, isentropic exponent, velocity of sound, viscosity, thermal conductivity, and Prandtl number. Property tables are based on composites that were calculated by assuming both: (1) chemical equilibrium (for both homogeneous and heterogeneous phases) and (2) constant compositions for all temperatures. Properties in SI units are presented in this report for the Kelvin temperature schedules.
ERIC Educational Resources Information Center
Goldblatt, Steven M.; Piele, Philip K.
This chapter reviews 1982 cases related to school property. Cases involving citizen efforts to overturn school board decisions to close schools dominate the property chapter, and courts continue to uphold school board authority to close schools, transfer students, and sell or lease the buildings. Ten cases involving detachment and attachment of…
ERIC Educational Resources Information Center
Piele, Philip K.; Johnson, Margaret M.
This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state could…
ERIC Educational Resources Information Center
Piele, Philip K.; Johnson, Margaret M.
This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state couldâ€¦
Generalized thermodynamic and transport properties. II. Molecular liquids
NASA Astrophysics Data System (ADS)
Bertolini, D.; Tani, A.
2011-03-01
In the present paper, we extend the method described in paper I [D. Bertolini and A. Tani, preceding paper, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.031201 83, 031201 (2011)] to molecular liquids, which allows us to solve the exact kinetic equation proposed by de Schepper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.38.271 38, 271 (1988)] without approximations. In particular, generalized thermodynamic properties (enthalpy, specific heat, and thermal expansion coefficient) and transport properties (longitudinal viscosity, thermal conductivity) have been calculated for three liquids of increasing complexity, namely dimethyl sulfoxide, hydrogen fluoride, and SPC/E water. All results have been obtained by the molecular formalism as well as the atomic one, corrected for intramolecular correlations that are due to the models adopted. As done for simple liquids, the coupling between the viscous stress tensor and the energy flux vector has been calculated exactly. We also show that the Markov assumption for the dynamics related to thermal conductivity can only be adopted with caution.
Optical and thermodynamic properties of mixed sulfate and nitrate aerosols
Tang, I.N.; Munkelwitz, H.R.
1995-12-31
Inorganic sulfates and nitrates in either pure or mixed forms constitute a major fraction of the ambient aerosol, which is formed from both natural and anthropogenic sources. It is well known that aerosol plays an important role in atmospheric processes affecting the local air quality and visibility. In addition, tropospheric aerosol contributes substantially to radiative forcing in an opposite manner to the green-house gases, thereby imposing a cooling effect to global climate change. Extensive optical and thermodynamic data are thus required as input to mathematical models predicting the dynamic behavior, visibility reduction, and radiative effects of atmospheric sulfate and nitrate aerosols. Using the single-particle levitation technique, in conjunction with Mie resonance spectroscopy, we have measured the refractive indices, densities, and water activities of solution droplets containing either single or mixed salts of (NH{sub 4}){sub 2}SO{sub 4}, Na{sub 2}SO{sub 4}, and NaNO{sub 3}. The single-particle levitation technique makes it possible to measure these properties over the supersaturated concentration region heretofore inaccessible for measurement with bulk samples. While density and water activity data are presented in the form of polynomials in solute wt%, the refractive index data are given in the form of partial molal refraction, which may be used for predicting the optical properties of a complex aerosol system. The data formats chosen here can be simply and directly incorporated into modelling computations.
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.
Investigation of thermodynamic properties of metal-oxide catalysts
NASA Astrophysics Data System (ADS)
Shah, Parag Rasiklal
An apparatus for Coulometric Titration was developed and used to measure the redox isotherms (i.e. oxygen fugacity P(O2) vs oxygen stoichiometry) of ceria-zirconia solid solutions, mixed oxides of vanadia, and vanadia supported on ZrO2. This data was used to correlate the redox thermodynamics of these oxides to their structure and catalytic properties. From the redox isotherms measured between 873 K and 973 K, the differential enthalpies of oxidation (DeltaH) for Ce0.81Zr0.19O 2.0 and Ce0.25Zr0.75O2.0 were determined, and they were found to be independent of extent of reduction or composition of the solid solution. They were also lower than DeltaH for ceria, which explains the better redox properties of ceria-zirconia solid solutions. The oxidation was driven by entropy in the low reduction region, and a structural model was proposed to explain the observed entropy effects. Redox isotherms were also measured for a number of bulk vanadates between 823 K and 973 K. DeltaG, DeltaH and DeltaS were reported for V 2O5, Mg3(VO4)2, CeVO 4 and ZrV2O7 along with DeltaG values for AlVO 4, LaVO4, CrVO4. V2O5 and ZrV2O7, which were the only oxides having V-O-V bonds, showed a two-step transition of vanadium for V+3â†”V +4 and V+4â†”V+5 equilibrium in the redox isotherms. The other oxides, all of which have only M-O-V (M=cation other than V), showed a direct one-step transition, V+3â†”V +5. The nature of the M-atom also influenced the P(O2) at which the V+3â†”V+5 transition occurs. Redox isotherms at 748 K were measured for vanadia supported on ZrO 2; with two different vanadia loadings corresponding to isolated vanadyls and polymeric vanadyls. The isotherm for the sample with isolated vanadyls showed a single-step transition, similar to the one seen in bulk vanadates with M-O-V linkages, while no such one-step transition was observed in the isotherm of the other sample. To study the affect of the varying redox properties of the vanadium-based catalysts on oxidation rates, kinetic studies were performed for methanol and propane oxidation reactions on some of these catalysts. The results suggested that there was no effect of thermodynamic properties of these catalysts on the rates of these oxidation reactions.
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 properties of model CdTe/CdSe mixtures
van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.
2015-02-20
We report on the thermodynamic properties of binary compound mixtures of model groups II–VI semiconductors. We use the recently introduced Stillinger–Weber Hamiltonian to model binary mixtures of CdTe and CdSe. We use molecular dynamics simulations to calculate the volume and enthalpy of mixing as a function of mole fraction. The lattice parameter of the mixture closely follows Vegard's law: a linear relation. This implies that the excess volume is a cubic function of mole fraction. A connection is made with hard sphere models of mixed fcc and zincblende structures. We found that the potential energy exhibits a positive deviation from ideal soluton behaviour; the excess enthalpy is nearly independent of temperatures studied (300 and 533 K) and is well described by a simple cubic function of the mole fraction. Using a regular solution approach (combining non-ideal behaviour for the enthalpy with ideal solution behaviour for the entropy of mixing), we arrive at the Gibbs free energy of the mixture. The Gibbs free energy results indicate that the CdTe and CdSe mixtures exhibit phase separation. The upper consolute temperature is found to be 335 K. Finally, we provide the surface energy as a function of composition. Moreover, it roughly follows ideal solution theory, but with a negative deviation (negative excess surface energy). This indicates that alloying increases the stability, even for nano-particles.
Thermodynamic properties of aluminum, magnesium, and calcium in molten silicon
Miki, Takahiro; Morita, Kazuki; Sano, Nobuo |
1998-10-01
The thermodynamic properties of aluminum, magnesium, and calcium in molten silicon were investigated using a chemical equilibration technique at 1723 to 1848 K, 1698 to 1798 K, and 1723 to 1823 K, respectively. The activity coefficient of aluminum in molten silicon was determined by equilibrating molten silicon-aluminum alloys with solid Al{sub 2}O{sub 3} and Al{sub 6}Si{sub 2}O{sub 13}, that of magnesium was determined by equilibrating molten silicon-magnesium alloys and MgO-SiO{sub 2}-Al{sub 2}O{sub 3} melts doubly saturated with MdSiO{sub 3} and SiO{sub 2}, and that of calcium was determined by equilibrating molten silicon-calcium alloys with SiO{sub 2}-saturated CaO-SiO{sub 2} melts. The activity coefficients at infinite dilution relative to the pure liquid state were determined as follows: log {gamma}{sub Al({ell})in Si}{sup o} = {minus} 1570/T + 0.236, (1723 to 1848 K); log {gamma}{sub Mg({ell}) in Si}{sup o} = {minus} 4900/T + 1.96, (1698 to 1798 K); and log {gamma}{sub Ca({ell})in Si}{sup o} = {minus} 7670/T + 1.53, (1723 to 1823 K).
Thermodynamic properties of model CdTe/CdSe mixtures
van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.
2015-02-20
We report on the thermodynamic properties of binary compound mixtures of model groups IIâ€“VI semiconductors. We use the recently introduced Stillingerâ€“Weber Hamiltonian to model binary mixtures of CdTe and CdSe. We use molecular dynamics simulations to calculate the volume and enthalpy of mixing as a function of mole fraction. The lattice parameter of the mixture closely follows Vegard's law: a linear relation. This implies that the excess volume is a cubic function of mole fraction. A connection is made with hard sphere models of mixed fcc and zincblende structures. We found that the potential energy exhibits a positive deviation frommoreÂ Â» ideal soluton behaviour; the excess enthalpy is nearly independent of temperatures studied (300 and 533 K) and is well described by a simple cubic function of the mole fraction. Using a regular solution approach (combining non-ideal behaviour for the enthalpy with ideal solution behaviour for the entropy of mixing), we arrive at the Gibbs free energy of the mixture. The Gibbs free energy results indicate that the CdTe and CdSe mixtures exhibit phase separation. The upper consolute temperature is found to be 335 K. Finally, we provide the surface energy as a function of composition. Moreover, it roughly follows ideal solution theory, but with a negative deviation (negative excess surface energy). This indicates that alloying increases the stability, even for nano-particles.Â«Â less
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 â€˜â€˜strongâ€™â€™ to â€˜â€˜fragileâ€™â€™ 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
Wüstite: electric, thermodynamic and optical properties of FeO
NASA Astrophysics Data System (ADS)
Schrettle, F.; Kant, Ch.; Lunkenheimer, P.; Mayr, F.; Deisenhofer, J.; Loidl, A.
2012-05-01
We report on a systematic optical investigation of wüstite. In addition, the sample under consideration, Fe0.93O, has been characterized in detail by electrical transport, dielectric, magnetic and thermodynamic measurements. From infrared reflectivity experiments, phonon properties, Drude-like conductivity contributions and electronic transitions have been systematically investigated. The phonon modes reveal a clear splitting below the antiferromagnetic ordering temperature, similar to observations in other transition-metal monoxides and in spinel compounds which have been explained in terms of a spin-driven Jahn-Teller effect. The electronic transitions can best be described assuming a crystal-field parameter Dq = 750 cm-1 and a spin-orbit coupling constant ? = 95 cm-1. A well defined crystal field excitation at low temperatures reveals significant broadening on increasing temperature with an overall transfer of optical weight into dc conductivity contributions. This fact seems to indicate a melting of the on-site excitation into a Drude behavior of delocalized charge carriers. The optical band gap in wüstite is close to 1.0 eV at room temperature. With decreasing temperature and passing the magnetic phase transition we have detected a strong blue shift of the correlation-induced band edge, which amounts to more than 15% and has been rarely observed in antiferromagnets.
Thermodynamic properties of model CdTe/CdSe mixtures
van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.
2015-02-20
We report on the thermodynamic properties of binary compound mixtures of model groups IIâ€“VI semiconductors. We use the recently introduced Stillingerâ€“Weber Hamiltonian to model binary mixtures of CdTe and CdSe. We use molecular dynamics simulations to calculate the volume and enthalpy of mixing as a function of mole fraction. The lattice parameter of the mixture closely follows Vegard's law: a linear relation. This implies that the excess volume is a cubic function of mole fraction. A connection is made with hard sphere models of mixed fcc and zincblende structures. We found that the potential energy exhibits a positive deviation from ideal soluton behaviour; the excess enthalpy is nearly independent of temperatures studied (300 and 533 K) and is well described by a simple cubic function of the mole fraction. Using a regular solution approach (combining non-ideal behaviour for the enthalpy with ideal solution behaviour for the entropy of mixing), we arrive at the Gibbs free energy of the mixture. The Gibbs free energy results indicate that the CdTe and CdSe mixtures exhibit phase separation. The upper consolute temperature is found to be 335 K. Finally, we provide the surface energy as a function of composition. Moreover, it roughly follows ideal solution theory, but with a negative deviation (negative excess surface energy). This indicates that alloying increases the stability, even for nano-particles.
NASA Technical Reports Server (NTRS)
Thompson, R. A.
1994-01-01
Accurate numerical prediction of high-temperature, chemically reacting flowfields requires a knowledge of the physical properties and reaction kinetics for the species involved in the reacting gas mixture. Assuming an 11-species air model at temperatures below 30,000 degrees Kelvin, SPECIES (Computer Codes for the Evaluation of Thermodynamic Properties, Transport Properties, and Equilibrium Constants of an 11-Species Air Model) computes values for the species thermodynamic and transport properties, diffusion coefficients and collision cross sections for any combination of the eleven species, and reaction rates for the twenty reactions normally occurring. The species represented in the model are diatomic nitrogen, diatomic oxygen, atomic nitrogen, atomic oxygen, nitric oxide, ionized nitric oxide, the free electron, ionized atomic nitrogen, ionized atomic oxygen, ionized diatomic nitrogen, and ionized diatomic oxygen. Sixteen subroutines compute the following properties for both a single species, interaction pair, or reaction, and an array of all species, pairs, or reactions: species specific heat and static enthalpy, species viscosity, species frozen thermal conductivity, diffusion coefficient, collision cross section (OMEGA 1,1), collision cross section (OMEGA 2,2), collision cross section ratio, and equilibrium constant. The program uses least squares polynomial curve-fits of the most accurate data believed available to provide the requested values more quickly than is possible with table look-up methods. The subroutines for computing transport coefficients and collision cross sections use additional code to correct for any electron pressure when working with ionic species. SPECIES was developed on a SUN 3/280 computer running the SunOS 3.5 operating system. It is written in standard FORTRAN 77 for use on any machine, and requires roughly 92K memory. The standard distribution medium for SPECIES is a 5.25 inch 360K MS-DOS format diskette. The contents of the diskettes are compressed using the PKWARE archiving tools. The utility to unarchive the files, PKUNZIP.EXE, is included. This program was last updated in 1991. SUN and SunOS are registered trademarks of Sun Microsystems, Inc.
NASA Technical Reports Server (NTRS)
Hansen, C Frederick; Heims, Steve P
1958-01-01
Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation region flow.
ERIC Educational Resources Information Center
Piele, Philip K.
A review of cases involving higher education property matters shows that many are concerned with building construction, equipment installation, or repair contracts. A number of other cases involve routine conflicts between colleges or universities and other governmental entities over matters such as requests for special exceptions to zoning…
ERIC Educational Resources Information Center
Piele, Philip K.; Johnson, Margaret M.
While the number of cases dealing with school property issues was significantly lower than in previous years, a significant number of cases involving the detachment and attachment of land to school districts arose. Eight of the eleven cases dealing with land detachment come from Illinois. The cases concerned requests from parents that their…
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.
NASA Technical Reports Server (NTRS)
Svehla, R. A.; Mcbride, B. J.
1973-01-01
A FORTRAN IV computer program for the calculation of the thermodynamic and transport properties of complex mixtures is described. The program has the capability of performing calculations such as:(1) chemical equilibrium for assigned thermodynamic states, (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. Condensed species, as well as gaseous species, are considered in the thermodynamic calculation; but only the gaseous species are considered in the transport calculations.
Thermodynamic properties of 1,1,1,2-tetrafluoroethane (R134a) in the critical region
NASA Astrophysics Data System (ADS)
Tang, S.; Jin, G. X.; Sengers, J. V.
1991-05-01
A theoretically based simplified crossover model, which is capable of representing the thermodynamic properties of fluids in a large range of temperatures and densities around the critical point, is presented. The model is used to predict the thermodynamic properties of R134a in the critical region from a limited amount of available experimental information. Values for various thermodynamic properties of R134a at densities from 2 to 8 mol·L-1 and at temperatures from 365 to 450 K are presented.
NASA Astrophysics Data System (ADS)
Wilson, H. F.
2013-12-01
First-principles atomistic simulation is a vital tool for understanding the properties of materials at the high-pressure high-temperature conditions prevalent in giant planet interiors, but properties such as solubility and phase boundaries are dependent on entropy, a quantity not directly accessible in simulation. Determining entropic properties from atomistic simulations is a difficult problem typically requiring a time-consuming integration over molecular dynamics trajectories. Here I will describe recent advances in first-principles thermodynamic calculations which substantially increase the simplicity and efficiency of thermodynamic integration and make entropic properties more readily accessible. I will also describe the use of first-principles thermodynamic calculations for understanding problems including core solubility in gas giants and superionic phase changes in ice giants, as well as future prospects for combining first-principles thermodynamics with planetary-scale models to help us understand the origin and consequences of compositional inhomogeneity in giant planet interiors.
Diagram analysis of the Hubbard model: Stationarity property of the thermodynamic potential
Moskalenko, V. A.; Dohotaru, L. A.; Cebotari, I. D.
2010-07-15
The diagram approach proposed many years ago for the strongly correlated Hubbard model is developed with the aim to analyze the thermodynamic potential properties. A new exact relation between renormalized quantities such as the thermodynamic potential, the one-particle propagator, and the correlation function is established. This relation contains an additional integration of the one-particle propagator with respect to an auxiliary constant. The vacuum skeleton diagrams constructed from the irreducible Green's functions and tunneling propagator lines are determined and a special functional is introduced. The properties of this functional are investigated and its relation to the thermodynamic potential is established. The stationarity property of this functional with respect to first-order variations of the correlation function is demonstrated; as a consequence, the stationarity property of the thermodynamic potential is proved.
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.
Thermodynamic equilibria in xylene isomerization. 2: The thermodynamic properties of m-xylene
Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Reynolds, J.W.; Steele, W.V.
1997-05-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties for m-xylene are reported. Experimental methods included adiabatic heat-capacity calorimetry (5 K to 430 K), vibrating-tube densitometry (323 K to 523 K), comparative ebulliometry (309 K to 453 K), and differential-scanning calorimetry (DSC). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 430 K and 550 K and the critical pressure were derived with the vapor-pressure and DSC results. Results were combined with an enthalpy of combustion reported in the literature to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra for the vapor phase. All results are compared with literature values.
Thermodynamic equilibria in xylene isomerization. 1: The thermodynamic properties of p-xylene
Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Steele, W.V.
1997-03-01
Measurements and calculations leading to the determination of thermodynamic properties for the gaseous and condensed phases of p-xylene (Chemical Abstracts registry number (supplied by the authors) [106-42-3]) are reported. All measurement results reported were obtained with a differential-scanning calorimeter (DSC). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 370 K and 550 K, the critical density and the critical pressure were derived with fitting procedures involving the new DSC results and literature vapor pressures and ensities. Results were combined with heat capacities reported in the literature obtained with adiabatic calorimetry and the enthalpy of combustion to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra. Results are compared with literature values. Literature vapor pressures, enthalpies of vaporization, virial coefficients, densities, and heat capacities for the condensed and gaseous phases are checked for consistency with the values used in this research.
Thermodynamic equilibria in xylene isomerization. 3: The thermodynamic properties of o-xylene
Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Cowell, A.B.; Reynolds, J.W.; Steele, W.V.
1997-07-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties for o-xylene (Chemical Abstracts registry number [95-47-6]) are reported. Experimental methods included adiabatic heat-capacity calorimetry (5 K to 420 K), comparative ebulliometry (313 K to 459 K), differential-scanning calorimetry (DSC), and vibrating-tube densitometry (323 K to 523 K). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 420 K and 550 K, the critical density, and the critical pressure were derived with the vapor-pressure, density, and DSC results. Results were combined with an enthalpy of combustion reported in the literature to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra from the literature for the vapor phase. A preliminary value for the barrier to methyl-group rotation is derived. All results are compared with literature values.
NASA Technical Reports Server (NTRS)
Nguyen, Huy H.; Martin, Michael A.
2003-01-01
The availability and proper utilization of fluid properties is of fundamental importance in the process of mathematical modeling of propulsion systems. Real fluid properties provide the bridge between the realm of pure analytiis and empirical reality. The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described, for example, in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to be used to facilitate the accurate interpretation of fluid thermodynamic property data generated by existing property packages. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package (based on fundamental equations of state approach). The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.
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.
EquilTheTA: Thermodynamic and transport properties of complex equilibrium plasmas
Colonna, G.; D'Angola, A.
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.
Mausbach, Peter; Sadus, Richard J
2011-03-21
The thermodynamic properties of pressure, energy, isothermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound are considered in a classical molecular dynamics ensemble. These properties were obtained 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. The complete thermodynamic information about an equilibrium system can be obtained from this general formalism. We apply this method to the gaussian core model fluid because the complex phase behavior of this simple model provides a severe test for this treatment. Waterlike and other anomalies are observed for some of the thermodynamic properties of the gaussian core model fluid. PMID:21428640
Structure and thermodynamic properties of relativistic electron gases
NASA Astrophysics Data System (ADS)
Liu, Yu; Wu, Jianzhong
2014-07-01
Relativistic effect is important in many quantum systems but theoretically complicated from both fundamental and practical perspectives. Herein we introduce an efficient computational procedure to predict the structure and energetic properties of relativistic quantum systems by mapping the Pauli principle into an effective pairwise-additive potential such that the properties of relativistic nonquantum systems can be readily predicted from conventional liquid-state methods. We applied our theoretical procedure to relativistic uniform electron gases and compared the pair correlation functions with those for systems of nonrelativistic electrons. A simple analytical expression has been developed to correlate the exchange-correlation free energy of relativistic uniform electron systems.
NASA Astrophysics Data System (ADS)
Singh, Gurpreet; Sharma, Rohit; Singh, Kuldip
2015-09-01
Thermodynamic properties (compressibility coefficient Z ? , specific heat at constant volume c v , adiabatic coefficient ? a , isentropic coefficient ? i s e n , and sound speed c s ) of non-local thermodynamic equilibrium hydrogen thermal plasma have been investigated for different values of pressure and non-equilibrium parameter ? (=Te/Th) in the electron temperature range from 6000 K to 60 000 K. In order to estimate the influence of pressure derivative of partition function on thermodynamic properties, two cases have been considered: (a) in which pressure derivative of partition function is taken into account in the expressions and (b) without pressure derivative of partition function in their expressions. Here, the case (b) represents expressions already available in literature. It has been observed that the temperature from which pressure derivative of partition function starts influencing a given thermodynamic property increases with increase of pressure and non-equilibrium parameter ?. Thermodynamic property in the case (a) is always greater than its value in the case (b) for compressibility coefficient and specific heat at constant volume, whereas for adiabatic coefficient, isentropic coefficient, and sound speed, its value in the case (a) is always less than its value in the case (b). For a given value of ?, the relationship of compressibility coefficient with degree of ionization depends upon pressure in the case (a), whereas it is independent of pressure in the case (b). Relative deviation between the two cases shows that the influence of pressure derivative of partition function is significantly large and increases with the augmentation of pressure and ? for compressibility coefficient, specific heat at constant volume, and adiabatic coefficient, whereas for isentropic coefficient and sound speed, it is marginal even at high values of pressure and non-equilibrium parameter ?.
Generalizing thermodynamic properties of bulk single-walled carbon nanotubes
NASA Astrophysics Data System (ADS)
Rodriguez, Kenneth R.; Malone, Marvin A.; Nanney, Warren A.; A. Maddux, Cassandra J.; Coe, James V.; Martínez, Hernán L.
2014-12-01
The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (n
Generalizing thermodynamic properties of bulk single-walled carbon nanotubes
Rodriguez, Kenneth R. Nanney, Warren A.; Maddux, Cassandra J.A.; MartÃnez, HernÃ¡n L.; Malone, Marvin A.; Coe, James V.
2014-12-15
The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (n
Generalizing thermodynamic properties of bulk single-walled carbon nanotubes
Rodriguez, Kenneth R.; Nanney, Warren A.; A. Maddux, Cassandra J.; Martínez, Hernán L.
2014-01-01
The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (n
Ideal-gas thermodynamic properties for natural-gas applications
NASA Astrophysics Data System (ADS)
Jaeschke, M.; Schley, P.
1995-11-01
Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of the c {p/0} correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were adjusted to selected c {p/0} data calculated from spectroscopic data for temperatures ranging from 10 to 1000 K. The data sources used are discussed and compared with literature data deduced from theoretic models and caloric measurements. The parameters presented will be applied in a current GERG project for evaluating equations of state (e.g., the AGA 8 equation) for their suitability for calculating caloric properties.
Nonlinear thermodynamic quantum master equation: Properties and examples
Oettinger, Hans Christian
2010-11-15
The quantum master equation obtained from two different thermodynamic arguments is seriously nonlinear. We argue that, for quantum systems, nonlinearity occurs naturally in the step from reversible to irreversible equations and we analyze the nature and consequences of the nonlinear contribution. The thermodynamic nonlinearity naturally leads to canonical equilibrium solutions and extends the range of validity to lower temperatures. We discuss the Markovian character of the thermodynamic quantum master equation and introduce a solution strategy based on coupled evolution equations for the eigenstates and eigenvalues of the density matrix. The general ideas are illustrated for the two-level system and for the damped harmonic oscillator. Several conceptual implications of the nonlinearity of the thermodynamic quantum master equation are pointed out, including the absence of a Heisenberg picture and the resulting difficulties with defining multitime correlations.
NASA Astrophysics Data System (ADS)
Chattopadhyay, Sankar P.; Bhowmik, Benoy B.
The thermodynamic and spectrophotometric properties of the hexamethylbenzene—iodine charge—transfer complex in different donor solvents such as benzene, toluene, xylene ( o-, m-, p-) and mesitylene are found to depend on the solvent. The results show that the oscillator strengths of the charge—transfer bands of the hexamethylbenzene—iodine complex in these donor solvents increase with the heats of formation but these values of oscillator strengths are found comparatively high in comparison with the results observed earlier in inert solvents. The charge—transfer interaction of donor solvents with iodine is responsible for changing both thermodynamic as well as spectrophotometric properties of the hexamethylbenzene—iodine complex. An attempt is made to calculate the thermodynamic and spectrophotometric properties of these complexes free from other interaction.
NASA Technical Reports Server (NTRS)
Allison, D. O.
1972-01-01
Computer programs for flow fields around planetary entry vehicles require real-gas equilibrium thermodynamic properties in a simple form which can be evaluated quickly. To fill this need, polynomial approximations were found for thermodynamic properties of air and model planetary atmospheres. A coefficient-averaging technique was used for curve fitting in lieu of the usual least-squares method. The polynomials consist of terms up to the ninth degree in each of two variables (essentially pressure and density) including all cross terms. Four of these polynomials can be joined to cover, for example, a range of about 1000 to 11000 K and 0.00001 to 1 atmosphere (1 atm = 1.0133 x 100,000 N/m sq) for a given thermodynamic property. Relative errors of less than 1 percent are found over most of the applicable range.
Thermodynamic properties of sophocarpine and oxysophocarpine alkaloids in aqueous glucose solutions
NASA Astrophysics Data System (ADS)
Li, Zongxiao; Zhao, Weiwei; Pu, Xiaohua
2012-04-01
Sophocarpine and oxysophocarpine's dissolution in aqueous glucose solutions were studied by a microcalorimetry method. The measured integral and differential heat of dissolution was used to build equations of the solute and the heat, so that dissolution thermodynamic equations, ?sol H m were achieved, which reveals the relationship between the substances structure and the thermodynamic properties. The current study provides theoretical bases for clinical applications of them.
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.
An Equation of State for the Thermodynamic Properties of Cyclohexane
Zhou, Yong Liu, Jun; Penoncello, Steven G.; Lemmon, Eric W.
2014-12-15
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 pÏT, 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 molâ€‰dm{sup âˆ’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.
Experimental verification of the thermodynamic properties for a jet-A fuel
NASA Technical Reports Server (NTRS)
Graciasalcedo, Carmen M.; Brabbs, Theodore A.; Mcbride, Bonnie J.
1988-01-01
Thermodynamic properties for a Jet-A fuel were determined by Shell Development Company in 1970 under a contract for NASA Lewis Research Center. The polynomial fit necessary to include Jet-A fuel (liquid and gaseous phases) in the library of thermodynamic properties of the NASA Lewis Chemical Equilibrium Program is calculated. To verify the thermodynamic data, the temperatures of mixtures of liquid Jet-A injected into a hot nitrogen stream were experimentally measured and compared to those calculated by the program. Iso-octane, a fuel for which the thermodynamic properties are well known, was used as a standard to calibrate the apparatus. The measured temperatures for the iso-octane/nitrogen mixtures reproduced the calculated temperatures except for a small loss due to the non-adiabatic behavior of the apparatus. The measurements for Jet-A were corrected for this heat loss and showed excellent agreement with the calculated temperatures. These experiments show that this process can be adequately described by the thermodynamic properties fitted for the Chemical Equilibrium Program.
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
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.
The extended thermodynamic properties of Taub-NUT/Bolt-AdS spaces
NASA Astrophysics Data System (ADS)
Lee, Chong Oh
2014-11-01
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 of aqueous polyatomic ions at extreme temperatures and pressures.
Djamali, Essmaiil; Cobble, James W
2010-03-25
Recently a theoretical treatment (J. Phys. Chem. B 2009, 113, 2398-2404) was developed for predicting the standard state thermodynamic properties of electrolytes up to and beyond the critical temperature of water (1273 K and at pressures up to 1000 MPa). In general, the model requires sufficient data at 298.15 K including the Gibbs free energy of hydration and at two higher temperatures to fix two constants for each electrolyte. This communication describes an extension of this "two constant" theory to thermodynamic properties of polyatomic ions for which no accurate data for the Gibbs free energy of hydration exits at 298.15 K. PMID:20192172
Numerical prediction of the thermodynamic properties of ternary Al-Ni-Hf alloys
NASA Astrophysics Data System (ADS)
Romanowska, Jolanta; Kotowski, S?awomir; Zagula-Yavorska, Maryana
2014-10-01
Thermodynamic properties of ternary Al-Hf-Ni system, such as exG, ?Al, ?Ni and ?Zr at 1373K were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting exG 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 exG on all legs of the triangle are known. exG and Lijk ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism are calculated numerically using Wolfram Mathematica 9 software.
A quantum model for bending vibrations and thermodynamic properties of C3.
NASA Technical Reports Server (NTRS)
Hansen, C. F.; Pearson, W. E.
1973-01-01
The investigation reported was conducted to clarify the thermodynamic properties of C3 by further developing the limit to the partition function suggested by Strauss and Thiele (1967). A quantum solution for the energy levels of a quadratically perturbed square well potential is presented and the consistency of this limit with observed energy levels is established. In the process a more complete physical picture of the bending C3 molecules emerges. The values of entropy deduced from various measurements of graphite pressure are compared with this limit, and the thermodynamic properties predicted for the limiting case are evaluated.
Symmetry, Optical Properties and Thermodynamics of Neptunium(V) Complexes
Rao, Linfeng; Tian, Guoxin
2009-12-21
Recent results on the optical absorption and symmetry of the Np(V) complexes with dicarboxylate and diamide ligands are reviewed. The importance of recognizing the 'silent' feature of centrosymmetric Np(V) species in analyzing the absorption spectra and calculating the thermodynamic constants of Np(V) complexes is emphasized.
Gas-Polymer Interactions: Key Thermodynamic Data and Thermophysical Properties
NASA Astrophysics Data System (ADS)
Grolier, Jean-Pierre E.; Boyer, Séverine A. E.
Gas-polymer interactions play a pivotal role in the formation of different molecular organizations/reorganizations of polymeric structures. Such structural modifications can have a negative impact on the material properties and should be understood in order to prevent them or these modifications are of engineering interest and they should be purposely tailored and properly controlled. Two newly developed techniques, gas-sorption/solubility and scanning transitiometry, are shown to be well adapted to provide the necessary (key) data to better understand and monitor the polymeric modifications observed under the triple constraints of temperature, elevated pressure, and gas sorption. This article illustrates the major contribution of gas-polymer interactions in different interconnected applied and engineering fields of the petroleum industry, polymer science, and microelectronics.
Thermodynamic critical and geometrical properties of charged BTZ black hole
Wei Yihuan
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 the itinerant-boson ferromagnet
Tao Chengjun; Wang Peilin; Qin Jihong; Gu Qiang
2008-10-01
Thermodynamics of a spin-1 Bose gas with ferromagnetic interactions is investigated via the mean-field theory. It is apparently shown in the specific-heat curve that the system undergoes two phase transitions, the ferromagnetic transition and Bose-Einstein condensation, with the Curie point above the condensation temperature. Above the Curie point, the susceptibility fits the Curie-Weiss law perfectly. At a fixed temperature, the reciprocal susceptibility is also in a good linear relationship with the ferromagnetic interaction.
Thermodynamic properties of uranium in gallium-aluminium based alloys
NASA Astrophysics Data System (ADS)
Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Chukin, A. V.; Smolenski, V. V.; Novoselova, A. V.; Osipenko, A. G.
2015-10-01
Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20Â wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga-Al alloys containing 0.014-20Â wt.% Al. Experiments were performed up to 1073Â K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated.
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.
dos Ramos, María Carolina; Blas, Felipe J
2005-06-23
A modification of the statistical associating fluid theory, the so-called Soft-SAFT equation of state, is proposed to predict the excess thermodynamic properties of binary mixtures of n-alkanes. n-Alkane molecules are modeled as fully flexible Lennard-Jones chains. This molecular model accounts for the most important microscopic features of real chainlike molecules: attractive and repulsive interactions between different chemical groups and the connectivity of the segments that form the molecules. In this work we consider an additional microscopic effect that can profoundly affect certain thermodynamic properties, namely, the conformational changes when two different n-alkane molecules are mixed. We propose, following the work of Vega and co-workers [J. Chem. Phys. 1999, 111, 3192], a simple model to account for the conformational changes in molecules. The resulting free energy is combined with the SAFT free energy to describe the excess thermodynamic properties of binary mixtures of n-alkanes. Predictions from the theory are compared with experimental data taken from the literature. The agreement between the experiments and the theoretical predictions is excellent in all cases. This work shows that although minor microscopic effects, such as the conformational changes in the molecules that form the mixtures, have only a very small effect on the usual thermodynamic properties, such as pressure, chemical potential, phase equilibria, and excess volumes, they can contribute significantly to other thermodynamic properties. In fact, one of the main conclusions of this work is that it is essential that conformational effects be taken into account in molecular-based theories if an accurate description of certain excess properties (excess enthalpy for instance) is desired. PMID:16852498
Thermodynamic Properties for A Drop-in Refrigerant R-SP34E
NASA Astrophysics Data System (ADS)
Kayukawa, Yohei; Hondo, Takashi; Watanabe, Koichi
Although a transition into several promising HFC alternative refrigerants and their mixtures from conventional CFC and/or HCFC refrigerants is steadily in progress, there still remains a niche to pursue a drop-in refrigerant in some limited engineering applications where the advantage of retrofitting can be emphasized.R-SP34E is one of such drop-in refrigerants to complement R-12 which is a ternary mixture refrigerant consisted of R-134a with minor fractions of propane and ethanol. In this paper, the fundamental thermodynamic properties such as VLE properties and gas-phase PVT properties of R-SP34E are presented. This paper reports the first sets of measured data including 7 dew-and bubble-point pressures and 73 gas-phase PVT properties in the extensive range of temperatures 300-380 K, pressures 0.1-5.2 MPa, and densities up to around the critical density, obtained by employing the Burnett apparatus. In order to complement and confirm the reliability of the measurements, thermodynamic models including a dew-point pressure correlation and a truncated virial equation of state were originally developed in this study. The models were confirmed to exhibit not only excellent reproducibility of the measurements but also the thermodynamic consistency regarding the temperature dependence of the second and third virial coefficients and derived properties such as specific heats or speed of sound. By presenting the reliable thermodynamic model, a systematic information about the thermodynamic properties of R-SP34E is provided in this paper.
Lin, He; Chen, Peng-Yuan; Zhu, Shun-Guan; Zhang, Lin; Peng, Xin-Hua; Li, Kun; Li, Hong-Zhen
2013-06-01
Trinitromethyl-substituted aminotetrazoles with -NH?, -NO?, -N?, and -NHC(NO?)? groups were investigated at the B3LYP/6-31G(d) level of density functional theory. Their sublimation enthalpies, thermodynamic properties, and heats of formation were calculated. The thermodynamic properties of these compounds increase with temperature as well as with the number of nitro groups attached to the tetrazole ring. In addition, the detonation velocities and detonation pressures of these compounds were successfully predicted using the Kamlet-Jacobs equations. It was found that these compounds exhibit good detonation properties, and that compound G (D = 9.2 km/s, P = 38.8 GPa) has the most powerful detonation properties, which are similar to those of the well-known explosive HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Finally, the electronic structures and bond dissociation energies of these compounds were calculated. The BDEs of their C-NO? bonds were found to range from 101.9 to 125.8 kJ/mol(-1). All of these results should provide useful fundamental information for the design of novel HEDMs. PMID:23420400
ÄŒervinka, Ctirad; PÃ¡dua, Agilio A H; Fulem, Michal
2016-03-10
This work presents a molecular dynamics simulation study concerning the thermodynamic data of ionic liquids (ILs) including phase change enthalpies, liquid phase densities, radial and spatial distribution functions, and diffusive properties. Three homologous series of ILs were selected for this study, namely, 1-alkyl-3-methylimidazolium tetrafluoroborates, hexafluorophosphates, and 1,1,2,2-tetrafluoroethanesulfonates, so that properties of 36 ILs are calculated in total. The trends of calculated properties are compared to available experimental data and thoroughly discussed in context of the homologous series. The calculated trends of the vaporization enthalpies within the series are supported by analyzing the structural properties of the ILs. An excellent agreement of calculated structural properties (liquid phase density) with the experimental counterparts is reached. The calculated enthalpic properties are overestimated considerably; thus, further development of the force fields for ILs is required. PMID:26848831
Thermodynamic and Acoustic Properties of Mixtures of Dibromomethane + Heptane
NASA Astrophysics Data System (ADS)
Przyby?a, Anna; Chor??ewski, Miros?aw; Zor?bski, Edward; Marczak, Wojciech
2011-04-01
Densities and speeds of ultrasound in binary mixtures of dibromomethane with heptane have been measured within the temperature range from 288.15 K to 318.15 K. From the experimental data, the thermodynamic excess volume, molar isobaric expansion, molar isentropic compression, and ultrasonic speed were calculated. The excess volume and excess isentropic compression have opposite signs, whereas the excess isobaric expansion is an S-shaped function of the mole fraction. An explanation was suggested to account for the excesses in terms of intermolecular interactions. It involved energetic and steric factors. Moreover, it was shown that the positive excess sound speed results almost entirely from the negative excess compression.
The standard thermodynamic properties of 4 f metal dichlorides
NASA Astrophysics Data System (ADS)
Chervonnyi, A. D.; Chervonnaya, N. A.
2008-02-01
The experimental data on heterogeneous and homogeneous equilibria with the participation of 4f metal dichlorides LnCl2 (where Ln = La, â€¦, Lu) were analyzed using the thermodynamic functions of these substances in the gaseous and condensed states described earlier. These data and appearance potential AP(Ln+/LnCl2) measurements were used to calculate the enthalpies of sublimation Î”sub H {298/o}. The enthalpies of atomization of these compounds under standard conditions were also calculated. Correlations between the enthalpies of sublimation and crystal lattice structure of 4 f metal trifluorides, trichlorides, and dichlorides are described.
NASA Astrophysics Data System (ADS)
Satoh, Katsuhiko
2013-08-01
The thermodynamic scaling of molecular dynamic properties of rotation and thermodynamic parameters in a nematic phase was investigated by a molecular dynamic simulation using the Gay-Berne potential. A master curve for the relaxation time of flip-flop motion was obtained using thermodynamic scaling, and the dynamic property could be solely expressed as a function of TV^{? _? }, where T and V are the temperature and volume, respectively. The scaling parameter ?? was in excellent agreement with the thermodynamic parameter ?, which is the logarithm of the slope of a line plotted for the temperature and volume at constant P2. This line was fairly linear, and as good as the line for p-azoxyanisole or using the highly ordered small cluster model. The equivalence relation between ? and ?? was compared with results obtained from the highly ordered small cluster model. The possibility of adapting the molecular model for the thermodynamic scaling of other dynamic rotational properties was also explored. The rotational diffusion constant and rotational viscosity coefficients, which were calculated using established theoretical and experimental expressions, were rescaled onto master curves with the same scaling parameters. The simulation illustrates the universal nature of the equivalence relation for liquid crystals.
Levitation calorimetry. IV - The thermodynamic properties of liquid cobalt and palladium.
NASA Technical Reports Server (NTRS)
Treverton, J. A.; Margrave, J. L.
1971-01-01
Some of the thermodynamic properties of liquid cobalt and palladium investigated by means of levitation calorimetry are reported and discussed. The presented data include the specific heats and heats of fusion of the liquid metals, and the emissivities of the liquid metal surfaces.
Thermodynamically-robust Pitzer equations for volumetric properties of electrolyte solutions.
Rowland, Darren
2015-11-01
Pitzer equations are widely employed to correlate and predict the volumetric properties of aqueous electrolyte solutions over broad ranges of pressure and temperature. However, the currently-used pressure and temperature terms are empirical and tend to violate known thermodynamic behaviour. Three functional constraints have been identified that overcome this problem. PMID:26452795
The Problem of Counting the Number of Molecules and Calculating Thermodynamic Properties.
ERIC Educational Resources Information Center
Torres, Luis Alfonso; And Others
1995-01-01
Presents an experimental approach to illustrate that the thermodynamic properties of a system can be considered as the average of mechanical variables. Discusses the Knudsen effusion method to count the number of molecules, vapor pressure, the piezoelectric effect, the experimental setup, and sample experimental results. (JRH)
Kong, Fanjie; Hu, Yanfei; Hou, Haijun; Liu, Yanhua; Wang, Baolin; Wang, Lili
2012-12-15
The structural, electronic, thermoelectric and thermodynamic properties of ternary half-Heusler compound YPdSb are investigated using the first principle calculations. It is found that YPdSb is an indirect semiconductor. The calculated band gap is 0.161 eV with spin-orbital coupling including and 0.235 eV without spin-orbital coupling including, respectively. The electronic transport properties are obtained via Boltzman transport theory. The predicted Seebeck coefficient is 240 {mu}V/K and the thermoelectric performance can be optimized by n-type doping at room temperature. Moreover, the lattice dynamical results regarding the phonon dispersion curves, phonon density of states and thermodynamic properties are reported. Thermodynamics (heat capacity and Debye temperature) as well as mean phonon free path and the thermal conductivity in a temperature range of 0-300 K are determined. - Graphical Abstract: (a) The dependence of the Seebeck coefficient on chemical potential at 300 K. (b) The dependence of the thermopower factor on chemical potential at 300 K. Highlights: Black-Right-Pointing-Pointer The Seebeck coefficient and the thermopower factor are calculated. Black-Right-Pointing-Pointer The lattice dynamics and thermodynamic properties are obtained.
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 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.
Thermodynamic properties of a quantum Hall anti-dot interferometer
NASA Astrophysics Data System (ADS)
Levy Schreier, Sarah; Stern, Ady; Rosenow, Bernd; Halperin, Bertrand I.
2016-02-01
We study quantum Hall interferometers in which the interference loop encircles a quantum anti-dot. We base our study on thermodynamic considerations, which we believe reflect the essential aspects of interference transport phenomena. We find that similar to the more conventional Fabry-Perot quantum Hall interferometers, in which the interference loop forms a quantum dot, the anti-dot interferometer is affected by the electro-static Coulomb interaction between the edge modes defining the loop. We show that in the Aharonov-Bohm regime, in which effects of fractional statistics should be visible, is easier to access in interferometers based on anti-dots than in those based on dots. We discuss the relevance of our results to recent measurements on anti-dots interferometers.
The thermodynamic properties of 2-methylaniline and trans-(R,S)- decahydroquinoline
Steele, W.V.; Chirico, R.D.; Nguyen, A.; Knipmeyer, S.E.
1990-02-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties for 2-methylaniline and trans-(R,S)-decahydroquinoline are reported. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (dsc). Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas at selected temperatures for both compounds. Critical properties were determined for 2-methylaniline with the dsc. Measured combustion enthalpies, vapor pressures, critical properties, and ideal-gas entropies were compared with estimated and experimental literature values. 59 refs., 7 figs., 15 tabs.
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.
Thermodynamic and mechanical properties of TiC from ab initio calculation
Dang, D. Y.; Fan, J. L.; Gong, H. R.
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.
Mechanical, electronic and thermodynamic properties of full Heusler compounds Fe2VX(X = Al, Ga)
NASA Astrophysics Data System (ADS)
Khalfa, M.; Khachai, H.; Chiker, F.; Baki, N.; Bougherara, K.; Yakoubi, A.; Murtaza, G.; Harmel, M.; Abu-Jafar, M. S.; Omran, S. Bin; Khenata, R.
2015-11-01
The electronic structure, mechanical and thermodynamic properties of Fe2VX, (with X = Al and Ga), have been studied self consistently by employing state-of-the-art full-potential linearized approach of augmented plane wave plus local orbitals (FP-LAPW + lo) method. The exchange-correlation potential is treated with the local density and generalized gradient approximations (LDA and GGA). Our predicted ground state properties such as lattice constants, bulk modulus and elastic constants appear more accurate when we employed the GGA rather than the LDA, and these results are in very good agreement with the available experimental and theoretical data. Further, thermodynamic properties of Fe2VAl and Fe2VGa are predicted with pressure and temperature in the ranges of 0-40 GPa and 0-1500 K using the quasi-harmonic Debye model. We have obtained successfully the variations of the heat capacities, primitive cell volume and volume expansion coefficient.
NASA Astrophysics Data System (ADS)
Li, Wei; Ran, Shi-Ju; Gong, Shou-Shu; Zhao, Yang; Xi, Bin; Ye, Fei; Su, Gang
2011-03-01
A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic quantities of the quantum XY spin chain as well as the Heisenberg antiferromagnet on a honeycomb lattice are calculated by the linearized tensor renormalization group method, showing the pronounced precision and high efficiency.
Thermodynamics properties of copper-oxide superconductors described by an Ising frustrated model
NASA Astrophysics Data System (ADS)
Padilha, Igor T.; de Sousa, J. Ricardo; Neto, Minos A.; Salmon, Octavio R.; Viana, J. R.
2013-10-01
In this work we will study the thermodynamics properties of the quenched decorated Ising model with competitive interactions through the effective field theory (EFT) of a one-spin cluster. This model is used here to describe the thermodynamics properties of the cooper-based oxide superconductors compounds in its insulating phase (antiferromagnetic). The model consists of planes in which the nodal spins interact antiferromagnetically (JA<0) with their nearest-neighbors and ferromagnetically (JF>0) with the spins that decorated the bonds, which are quenched randomly distributed over the two-dimensional lattice. The planes interact antiferromagnetically with weak exchange interaction (i.e., JA?=?JA, ?=10-5). By using the framework of an effective-field theory, based on the differential operator technique, we discuss beyond thermodynamics properties the antiferromagnetic-phase stability limit in the temperature-decorated bond concentration space (T×p), for ?=10-5 and various values of frustration parameter (?=JA/JF), magnetic field (H) and concentration parameter (p). For certain range of the parameter ? we observe a reentrant behavior in low-temperature that it reflects in the properties behavior itself.
Thermodynamic, structural and surface properties in Sn-Zn melt at 750 K
NASA Astrophysics Data System (ADS)
Singh, B. P.; Koirala, R. P.; Jha, I. S.; Adhikari, D.
2015-09-01
Thermodynamic, microscopic and surface properties of liquid Sn-Zn alloys at 750 K are reviewed in the framework of different statistical mechanical models. Flory's model and quasi-chemical approximation (QCA) have been considered to deduce information on the concentration dependence of the thermodynamic and structural properties. The size-dependent atomic interaction has got special attention in Flory's model, while in QCA the atomic interaction leading to the formation of like-atom clusters is assumed. Both models predict almost the same value of the interaction energy parameter in the Sn-Zn alloys, and it is found to be temperature dependent. The asymmetry in the thermodynamic properties of the alloys is explained to a great extent, and the analysis of the microscopic properties suggests that the Sn-Zn alloys are weakly segregating in nature throughout the whole range of the composition. Meanwhile, the validity of these models in describing the thermodynamic behaviour of the alloys is also examined. QCA is found to be more appropriate choice for the study of the energetics of the Sn-Zn alloys at 750 K. The comparative analysis of the surface properties under different assumptions reveals that self-associating mixture method better explains the surface behaviour in the alloys. The study indicates nonlinear variation in the concentration dependence of both the surface concentration and the surface tension of the alloys. The surface tension is found to increase with increase in Zn concentration, and the surface of the alloys is enriched with Sn atoms which segregate to the surface.
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.
A web based program to visualize the transport and thermodynamic properties of thermal plasma
NASA Astrophysics Data System (ADS)
Sreekumar, Ambili; Thiyagarajan, T. K.; Ravi, Vijayalakshmi; Padmanabhan, P. V. A.
2010-02-01
The data of transport properties like viscosity, thermal conductivity and electrical conductivity of high temperature gases or gas mixtures used in thermal plasma devices, as a function of temperature is very much essential for the process modeling and theoretical simulation. Similarly the temperature variation of thermodynamic properties like density, specific heat and enthalpy also should be known. Calculated values of these properties of the gases or gas mixtures specific to thermal plasma devices are available as a function of temperature in tabular form. To share the knowledge about these values of properties, web based package of codes and database documents are developed. The modules present in the package works in client-server environment, where the inter communication is through HTTP protocol. The developed package is tested with Apache tomcat web container. The details of the code development and working procedure are described in this paper.
Perruchot, Christian; Chehimi, Mohamed M.; Vaulay, Marie-Josephe; Benzarti, Karim . 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)
NASA Astrophysics Data System (ADS)
Noh, Seunghyo; Kwak, Dohyun; Lee, Juseung; Kang, Joonhee; Han, Byungchan
2014-03-01
We utilized first-principles density-functional-theory (DFT) calculations to evaluate the thermodynamic feasibility of a pyroprocessing methodology for reducing the volume of high-level radioactive materials and recycling spent nuclear fuels. The thermodynamic properties of transuranium elements (Pu, Np and Cm) were obtained in electrochemical equilibrium with a LiCl-KCl molten salt as ionic phases and as adsorbates on a W(110) surface. To accomplish the goal, we rigorously calculated the double layer interface structures on an atomic resolution, on the thermodynamically most stable configurations on W(110) surfaces and the chemical activities of the transuranium elements for various coverages of those elements. Our results indicated that the electrodeposition process was very sensitive to the atomic level structures of Cl ions at the double-layer interface. Our studies are easily expandable to general electrochemical applications involving strong redox reactions of transition metals in non-aqueous solutions.
Accuracy Based Generation of Thermodynamic Properties for Light Water in RELAP5-3D
Cliff B. Davis
2010-09-01
RELAP5-3D interpolates to obtain thermodynamic properties for use in its internal calculations. The accuracy of the interpolation was determined for the original steam tables currently used by the code. This accuracy evaluation showed that the original steam tables are generally detailed enough to allow reasonably accurate interpolations in most areas needed for typical analyses of nuclear reactors cooled by light water. However, there were some regions in which the original steam tables were judged to not provide acceptable accurate results. Revised steam tables were created that used a finer thermodynamic mesh between 4 and 21 MPa and 530 and 640 K. The revised steam tables solved most of the problems observed with the original steam tables. The accuracies of the original and revised steam tables were compared throughout the thermodynamic grid.
Numerical prediction of the thermodynamic properties of ternary Al-Ni-Hf alloys
Romanowska, Jolanta; Kotowski, SÅ‚awomir; Zagula-Yavorska, Maryana
2014-10-06
Thermodynamic properties of ternary Al-Hf-Ni system, such as {sup ex}G, Î¼{sub Al}, Î¼{sub Ni} and Î¼{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.
Donohue, M.D.
1991-10-01
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. In order to get a better understanding of the intermolecular forces and to test some of our recent models, we have performed considerable experimental work. We used FTIR to examine hydrogen bonding interactions between small molecules and between small molecules and polymers. In addition, we investigated experimentally the high pressure phase behavior of ternary and quaternary systems exhibiting polar and hydrogen bonding interactions.
Elastic and thermodynamic properties of Fe3Ga from first-principles calculations
NASA Astrophysics Data System (ADS)
Lin, Ya-Ning; Li, Lin-Ling; Yan, Xiang-Hong; Zhang, Ya-Ping; Zhang, Dong-yun; Zhang, Peng
2016-03-01
First-principles calculations within the framework of density functional theory (DFT) are performed to investigate the elastic and thermodynamic properties of DO3-type Fe3Ga alloy. The obtained lattice constants and the bulk modulus are in good agreement with available experimental data. In terms of the calculated formation energy and Poisson's ratio, the Fe3Ga alloy is mechanically stable and exhibit a negative Poisson's ratio of -0.81 along the <110> direction. The thermodynamic properties such as the Gibbs free energy, thermal expansion, and the specific heat are obtained by the first-principles phonon calculations with the quasiharmonic approximation method. The predicted coefficient of linear thermal expansion and specific heat may provide a helpful reference for experimental work.
Thermodynamic properties of liquid Au-Cu-Sn alloys determined from electromotive force measurements.
Guo, Zhongnan; Hindler, Michael; Yuan, Wenxia; Mikula, Adolf
2011-10-20
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
Pressure effect on structural, elastic, and thermodynamic properties of tetragonal B4C4
NASA Astrophysics Data System (ADS)
Zheng, Baobing; Zhang, Meiguang; Luo, Hong-Gang
2015-03-01
The compressibility, elastic anisotropy, and thermodynamic properties of the recently proposed tetragonal B4C4 (t-B4C4) are investigated under high temperature and high pressure by using of first-principles calculations method. The elastic constants, bulk modulus, shear modulus, Young's modulus, Vickers hardness, Pugh's modulus ratio, and Poisson's ratio for t-B4C4 under various pressures are systematically explored, the obtained results indicate that t-B4C4 is a stiffer material. The elastic anisotropies of t-B4C4 are discussed in detail under pressure from 0 GPa to 100 GPa. The thermodynamic properties of t-B4C4, such as Debye temperature, heat capacity, and thermal expansion coefficient are investigated by the quasi-harmonic Debye model.
Elastic and thermodynamic properties of TiC from first-principles calculations
NASA Astrophysics Data System (ADS)
Li, Yanhong; Wang, Wanfeng; Zhu, Bo; Xu, Ming; Zhu, Jun; Hao, Yanjun; Li, Weihu; Long, Xiaojiang
2011-12-01
Using the pseudopotential plane-wave method, we investigate the elastic constants and thermodynamic properties of the rocksalt structure Titanium Carbide (TiC). The obtained lattice parameters, bulk modulus and elastic constants are in very good agreement with the available experimental data and other theoretical results. The thermodynamic properties of the cubic TiC are predicted by using the quasi-harmonic Debye model. The normalized volume V/ V 0, bulk modulus B, thermal expansion ?, heat capacity C V , Grüneisen parameter ? and Debye temperature ? dependence on the pressure and temperature are obtained successfully. At low temperature and low pressure, thermal expansion coefficient increases rapidly with temperature. At high temperature and high pressure, the increasing trend becomes tender. At low temperatures, C V is proportional to T 3, and C V tends to the Dulong-Petit limit at higher temperatures.
Quartz: heat capacities from 340 to 1000 K and revised values for the thermodynamic properties.
Hemingway, B.S.
1987-01-01
New heat-capacity data for quartz have been measured over the T interval 340-1000 K by differential scanning calorimetry. The data were combined with recent heat-content and heat-capacity data to provide a significantly revised set of thermodynamic properties for alpha -quartz and to resolve the problem of disparate heat-content and heat-capacity data for alpha - and beta -quartz.-J.A.Z.
NASA Technical Reports Server (NTRS)
Younglove, B.; Mccarty, R. D.
1979-01-01
A virial equation of state for nitrogen was determined by use of newly measured speed-of-sound data and existing pressure-density-temperature data in a multiproperty-fitting technique. The experimental data taken were chosen to optimize the equation of state for a pressure range of 0 to 10 atm and for a temperature range of 60 to 350 K. Comparisons are made for thermodynamic properties calculated both from the new equation and from existing equations of state.
Hung, N. Quang; Dang, N. Dinh
2010-10-15
The thermodynamic properties of hot nuclei are described within the canonical and microcanonical ensemble approaches. These approaches are derived based on the solutions of the BCS and self-consistent quasiparticle random-phase approximation at zero temperature embedded into the canonical and microcanonical ensembles. The results obtained agree well with the recent data extracted from experimental level densities by the Oslo group for {sup 94}Mo, {sup 98}Mo, {sup 162}Dy, and {sup 172}Yb nuclei.
New International Skeleton Tables for the Thermodynamic Properties of Ordinary Water Substance
NASA Astrophysics Data System (ADS)
Sato, H.; Uematsu, M.; Watanabe, K.; Saul, A.; Wagner, W.
1988-10-01
The current knowledge of thermodynamic properties of ordinary water substance is summarized in a condensed form of a set of skeleton steam tables, where the most probable values with the reliabilities on specific volume and enthalpy are provided in the range of temperatures from 273 to 1073 K and pressures from 101.325 kPa to 1 GPa and at the saturation state from the triple point to the critical point. These tables have been accepted as the IAPS Skeleton Tables 1985 for the Thermodynamic Properties of Ordinary Water Substance(IST-85) by the International Association for the Properties of Steam(IAPS). The former International Skeleton Steam Tables, October 1963(IST-63), have been withdrawn by IAPS. About 17 000 experimental thermodynamic data were assessed and classified previously by Working Group 1 of IAPS. About 10 000 experimental data were collected and evaluated in detail and especially about 7000 specific-volume data among them were critically analyzed with respect to their errors using the statistical method originally developed at Keio University by the first three authors. As a result, specific-volume and enthalpy values with associated reliabilities were determined at 1455 grid points of 24 isotherms and 61 isobars in the single-fluid phase state and at 54 temperatures along the saturation curve. The background, analytical procedure, and reliability of IST-85 as well as the assessment of the existing experimental data and equations of state are also discussed in this paper.
Thermodynamic and transport properties of two-temperature SF{sub 6} plasmas
Wang Weizong; Rong Mingzhe; Wu Yi; Spencer, Joseph W.; Yan, Joseph D.; Mei, DanHua
2012-08-15
This paper deals with thermodynamic and transport properties of SF{sub 6} plasmas in a two-temperature model for both thermal equilibrium and non-equilibrium conditions. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and Guldberg-Waage equation according to deviation of van de Sanden et al. Transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated with most recent collision interaction potentials by adopting Devoto's electron and heavy particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of Chapman-Enskog method. The results are computed for various values of pressures from 0.1 atm to 10 atm and ratios of the electron temperature to the heavy particle temperature from 1 to 20 with electron temperature range from 300 to 40 000 K. In the local thermodynamic equilibrium regime, results are compared with available results of previously published studies.
Pressure-Temperature Dependence of Thermodynamic Properties of Perovskite from First Principles
NASA Astrophysics Data System (ADS)
Abdollahi, Arash; Gholzan, Seyed Maghsoud
2015-08-01
First-principles calculations have been performed to obtain the thermodynamic properties of perovskite in a wide range of pressure (0 GPa to 30 GPa) and temperature (0 K to 1400 K). Calculations have been performed by using the pseudo-potential method within the generalized gradient approximation. Both pressure- and temperature-dependent thermodynamic properties including the bulk modulus, thermal expansion, thermal expansion coefficient, and the heat capacity at constant volume and constant pressure were calculated using three different approaches based on the quasi-harmonic Debye model: the Slater, Dugdale-MacDonald (DM), and Vaschenko-Zubarev (VZ) approaches. Also, empirical energy corrections are applied to the results of models to correct the systematic errors introduced by the functional. It is found that the VZ model provides more accurate estimates in comparison with the DM and Slater models, especially after an empirical energy correction. The results obtained from the VZ analysis on the corrected static energy show that this method can be used to determine the thermodynamic properties of compounds with reasonable accuracy.
An EQT-cDFT approach to determine thermodynamic properties of confined fluids
NASA Astrophysics Data System (ADS)
Mashayak, S. Y.; Motevaselian, M. H.; Aluru, N. R.
2015-06-01
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.
Singh, Kuldip; Singh, Gurpreet; Sharma, Rohit
2010-07-15
Thermodynamic and electron transport properties of the argon and argon-hydrogen plasmas have been calculated under the local thermodynamic equilibrium conditions in temperature range of 10 000-40 000 K over the wide range of pressures. Electronic excitation affects strongly these properties especially at high pressures. The inclusion of electronically excited states (EES) in relevant partition function influences the internal contribution to frozen and total specific heat for argon and argon-hydrogen plasma and it has been observed that although the total specific heat of argon plasma is less than that of hydrogen plasma, yet its internal contribution is more. Compensation between different contributions to total specific heat (by including and neglecting EES) occurring in hydrogen plasmas at low pressures has not been observed in argon and argon-hydrogen plasmas. As electron transport properties strongly depend upon the degree of ionization, therefore larger relative errors are found for these properties with and without EES, and in contrast to hydrogen plasma there exist a dominance of electron-atom cross section at low temperatures and EES dominance at intermediate temperatures.
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.
NASA Astrophysics Data System (ADS)
Kaplun, Alexander; Meshalkin, Arkadiy
2014-08-01
The new simple semi empirical equation of state for description of P-?-T data of "normal" substances was specified. New equation of state has 10 individual adjustable coefficients and it describes thermal properties of gas, liquid and fluid in the main with the accuracy within the error of experimental data, except of critical region. The caloric properties and the speed of sound of argon, nitrogen and carbon dioxide were calculated with the help of known thermodynamic equations and in general divergences between calculated and tabular caloric data do not exceed the experimental error. New equation can be used for engineering calculations at the deficit of experimental data, especially on the caloric properties of substances.
NASA Technical Reports Server (NTRS)
Thompson, Richard A.; Lee, Kam-Pui; Gupta, Roop N.
1991-01-01
The computer codes developed here provide self-consistent thermodynamic and transport properties for equilibrium air for temperatures from 500 to 30000 K over a temperature range of 10 (exp -4) to 10 (exp -2) atm. These properties are computed through the use of temperature dependent curve fits for discrete values of pressure. Interpolation is employed for intermediate values of pressure. The curve fits are based on mixture values calculated from an 11-species air model. Individual species properties used in the mixture relations are obtained from a recent study by the present authors. A review and discussion of the sources and accuracy of the curve fitted data used herein are given in NASA RP 1260.
Structural properties and thermodynamics of water clusters: A Wang-Landau study
NASA Astrophysics Data System (ADS)
Yin, Junqi; Landau, D. P.
2011-02-01
The temperature dependence of structural properties and thermodynamic behavior of water clusters has been studied using Wang-Landau sampling. Four potential models, simple point charge/extended (SPC/E), transferable intermolecular potential 3 point (TIP3P), transferable intermolecular potential 4 point (TIP4P), and Gaussian charge polarizable (GCP), are compared for ground states and properties at finite temperatures. Although the hydrogen bond energy and the distance of the nearest-neighbor oxygen pair are significantly different for TIP4P and GCP models, they approach to similar ground state structures and melting transition temperatures in cluster sizes we considered. Comparing with TIP3P, SPC/E model provides properties closer to that of TIP4P and GCP.
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.
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.
Free energy of formation of Mo2C and the thermodynamic properties of carbon in solid molybdenum
NASA Technical Reports Server (NTRS)
Seigle, L. L.; Chang, C. L.; Sharma, T. P.
1979-01-01
As part of a study of the thermodynamical properties of interstitial elements in refractory metals, the free energy of formation of Mo2C is determined, and the thermodynamical properties of C in solution in solid Mo evaluated. The activity of C in the two-phase region Mo + Mo2C is obtained from the C content of iron rods equilibrated with metal + carbide powder mixtures. The free energy of formation of alpha-Mo2C is determined from the activity data. The thermodynamic properties of C in the terminal solid solution are calculated from available data on the solid solubility of C in Mo. Lattice distortion due to misfit of the C atoms in the interstitial sites appears to play a significant role in determining the thermodynamic properties of C in solid Mo.
Thermodynamic properties of LnBa2Cu3O6 + z (Ln = Gd, Dy, Ho, Yb, and Y) compounds
NASA Astrophysics Data System (ADS)
Kovba, M. L.; Voskov, A. L.
2015-05-01
Thermodynamic properties of superconductors of LnBa2Cu3O6 + z (Ln = Gd, Dy, Ho, Yb, and Y) are determined by means of EMF using fluoro-ion electrolyte in the temperature range of 900-1250 K. Comparative analyses of the experimental data and thermodynamic models is performed for YBa2Cu3O6 + z compound.
Thermodynamic properties of asymptotically Reissnerâ€“NordstrÃ¶m black holes
Hendi, S.H.
2014-07-15
Motivated by possible relation between Bornâ€“Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissnerâ€“NordstrÃ¶m 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: â€¢We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. â€¢We investigate thermodynamic stability and discuss about the size of stable black holes. â€¢We obtain analytical solutions of higher dimensional theory.
First-principles study of structural, elastic, and thermodynamic properties of ZrHf alloy
NASA Astrophysics Data System (ADS)
Wei, Zhao; Zhai, Dong; Shao, Xiao-Hong; Lu, Yong; Zhang, Ping
2015-04-01
Structural parameters, elastic constants, and thermodynamic properties of ordered and disordered solid solutions of ZrHf alloys are investigated through first-principles calculations based on density-functional theory (DFT). The special quasi-random structure (SQS) method is used to model the disordered phase as a single unit cell, and two lamella structures are generated to model the ordered alloys. Small strains are applied to the unit cells to measure the elastic behavior and mechanical stability of ZrHf alloys and to obtain the independent elastic constants by the stress-strain relationship. Phonon dispersions and phonon density of states are presented to verify the thermodynamic stability of the considered phases. Our results show that both the ordered and disordered phases of ZrHf alloys are structurally stable. Based on the obtained phonon frequencies, thermodynamic properties, including Gibbs free energy, entropy, and heat capacity, are predicted within the quasi-harmonic approximation. It is verified that there are no obvious differences in energy between ordered and disordered phases over a wide temperature range. Project supported by the National Natural Science Foundation of China (Grant No. 51102009) and the Long-Term Subsidy Mechanism from the Ministry of Finance and the Ministry of Education of China.
Numerical Prediction of the Thermodynamic Properties of Ternary Al-Ni-Pd Alloys
NASA Astrophysics Data System (ADS)
Zagula-Yavorska, Maryana; Romanowska, Jolanta; Kotowski, S?awomir; Sieniawski, Jan
2016-01-01
Thermodynamic properties of ternary Al-Ni-Pd system, such as exGAlNPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) at 1,373 K, were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting exGAlNiPd values was regarded as calculation of values of the exG function inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of exG on all legs of the triangle are known (exGAlNi, exGAlPd, exGNiPd). This approach is contrary to finding a function value outside a certain area, if the function value inside this area is known. exG and LAl,Ni,Pd ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism were calculated numerically using the Excel program and Solver. The accepted values of the third component xx differed from 0.01 to 0.1 mole fraction. Values of LAlNiPd parameters in the Redlich-Kister formula are different for different xx values, but values of thermodynamic functions: exGAlNiPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) do not differ significantly for different xx values. The choice of xx value does not influence the accuracy of calculations.
Determination and modeling of the thermodynamic properties of liquid calcium-antimony alloys
Poizeau, S; Kim, H; Newhouse, JM; Spatocco, BL; Sadoway, DR
2012-08-01
The thermodynamic properties of Ca-Sb alloys were determined by emf measurements in a cell configured as Ca(s)vertical bar CaF2 vertical bar Ca-Sb over the temperature range 550-830 degrees C. Activity coefficients of Ca and Sb, enthalpy, Gibbs free energy, and entropy of mixing of Ca-Sb alloys were calculated for xc(a) < 0.55. To explain the connection between short-range order of liquid Ca-Sb alloys and the strong deviation from ideality in the thermodynamic properties, two thermodynamic models were invoked and reconciled: the regular associated solution model, assuming the presence of a CaSb2 associate, and the molecular interaction volume model (MIVM). For the first time, the MIVM was used successfully to model the activity coefficients of a system with high-melting intermetallics, reducing the number of fitting parameters necessary from 5 (regular associated model) to 2 (MIVM). From the interaction parameters optimized by fitting at 800 degrees C, the with an average error of less than value. (C) 2012 Elsevier Ltd. All rights reserved,
Numerical Prediction of the Thermodynamic Properties of Ternary Al-Ni-Pd Alloys
NASA Astrophysics Data System (ADS)
Zagula-Yavorska, Maryana; Romanowska, Jolanta; Kotowski, SÅ‚awomir; Sieniawski, Jan
2016-01-01
Thermodynamic properties of ternary Al-Ni-Pd system, such as exGAlNPd, ÂµAl(AlNiPd), ÂµNi(AlNiPd) and ÂµPd(AlNiPd) at 1,373 K, were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting exGAlNiPd values was regarded as calculation of values of the exG function inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of exG on all legs of the triangle are known (exGAlNi, exGAlPd, exGNiPd). This approach is contrary to finding a function value outside a certain area, if the function value inside this area is known. exG and LAl,Ni,Pd ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism were calculated numerically using the Excel program and Solver. The accepted values of the third component xx differed from 0.01 to 0.1 mole fraction. Values of LAlNiPd parameters in the Redlich-Kister formula are different for different xx values, but values of thermodynamic functions: exGAlNiPd, ÂµAl(AlNiPd), ÂµNi(AlNiPd) and ÂµPd(AlNiPd) do not differ significantly for different xx values. The choice of xx value does not influence the accuracy of calculations.
Optimization of the thermodynamic properties and phase diagrams of P2O5-containing systems
NASA Astrophysics Data System (ADS)
Hudon, Pierre; Jung, In-Ho
2014-05-01
P2O5 is an important oxide component in the late stage products of numerous igneous rocks such as granites and pegmatites. Typically, P2O5 combines with CaO and crystallizes in the form of apatite, while in volatile-free conditions, Ca-whitlockite is formed. In spite of their interest, the thermodynamic properties and phase diagrams of P2O5-containg systems are not well known yet. In the case of the pure P2O5 for example, no experimental thermodynamic data are available for the liquid and the O and O' solid phases. As a result, we re-evaluated all the thermodynamic and phase diagram data of the P2O5 unary system [1]. Optimization of the thermodynamic properties and phase diagrams of the binary P2O5 systems was then performed including the Li2O-, Na2O-, MgO-, CaO-, BaO-, MnO-, FeO-, Fe2O3-, ZnO-, Al2O3-, and SiO2-P2O5 [2] systems. All available thermodynamic and phase equilibrium data were simultaneously reproduced in order to obtain a set of model equations for the Gibbs energies of all phases as functions of temperature and composition. In particular, the Gibbs energy of the liquid solution was described using the Modified Quasichemical Model [3-5] implemented in the FactSage software [6]. Thermodynamic modeling of the Li2O-Na2O-K2O-MgO-CaO-FeO-Fe2O3-Al2O3-SiO2 system, which include many granite-forming minerals such as nepheline, leucite, pyroxene, melilite, feldspar and spinel is currently in progress. [1] Jung, I.-H., Hudon, P. (2012) Thermodynamic assessment of P2O5. J. Am. Ceram. Soc., 95 (11), 3665-3672. [2] Rahman, M., Hudon, P. and Jung, I.-H. (2013) A coupled experimental study and thermodynamic modeling of the SiO2-P2O5 system. Metall. Mater. Trans. B, 44 (4), 837-852. [3] Pelton, A.D. and Blander, M. (1984) Computer-assisted analysis of the thermodynamic properties and phase diagrams of slags. Proc. AIME Symp. Metall. Slags Fluxes, TMS-AIME, 281-294. [4] Pelton, A.D. and Blander, M. (1986) Thermodynamic analysis of ordered liquid solutions by a modified quasichemical approach application to silicate slags. Metall. Trans. B, 17, 805-815. [5] A.D. Pelton, S.A. Decterov, G. Eriksson, C. Robelin and Y. Dessureault (2000) The modified quasichemical model - I Binary solutions. Metall. Mater. Trans. B, 31, 651-660. [6] C.W. Bale, P. Chartrand, S.A. Decterov, G. Eriksson, K. Hack, R. Ben Mahfoud, J. MelanÃ§on, A.D. Pelton and S. Petersen. (2002) FactSage Thermochemical Software and Databases. Calphad, 26, 189-228.
Average thermodynamic and spectral properties of plasma in and around dipolarizing flux bundles
NASA Astrophysics Data System (ADS)
Runov, A.; Angelopoulos, V.; Gabrielse, C.; Liu, J.; Turner, D. L.; Zhou, X.-Z.
2015-06-01
Recent observations have suggested that spatially localized flows of high-temperature, low-density plasma carrying a dipolarized magnetic field (dipolarizing flux bundles, DFBs) play a key role in hot plasma transport toward the inner magnetosphere. What controls plasma heating in DFBs and how do thermodynamic parameters (such as density, temperature, pressure, and specific entropy) and spectral properties of the DFB population depend on ambient plasma sheet properties and geocentric distance R remains unknown. By statistical analysis of 271 DFB events detected by the Time History of Events and Macroscale Interactions during Substorms mission during the 2008-2009 tail seasons, we find that on average, plasma inside DFBs is a factor of 0.6 less dense and a factor of 1.5 to 2 hotter than ambient tail plasma. The radial profiles of average thermodynamic parameters inside and outside DFBs are similar; when fitted by the ?-function, their energy spectra have similar ?-exponents, but a factor of 2 larger peak energies inside DFBs. Our analysis suggests that average DFB plasma properties are closely linked to those of the ambient plasma sheet population. Estimations show that on average, adiabatic heating of the ambient plasma in the increased magnetic field is the major factor in DFB plasma heating.
Santos, Ana Filipa L O M; Oliveira, Juliana A S A; Ribeiro da Silva, Maria D M C; Monte, Manuel J S
2016-03-01
This work reports the experimental determination of relevant thermodynamic properties and the characterization of luminescence properties of the following polycyclic aromatic hydrocarbons (PAHs): 2,6-diethylnaphthalene, 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene. The standard (p(o)Â =Â 0.1Â MPa) molar enthalpies of combustion, Î”cHm(o), of the three compounds were determined using static bomb combustion calorimetry. The vapor pressures of the crystalline phase of 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene were measured at different temperatures using the Knudsen effusion method and the vapor pressures of both liquid and crystalline phases of 2,6-diethylnaphthalene were measured by means of a static method. The temperatures and the molar enthalpies of fusion of the three compounds were determined using differential scanning calorimetry. The gas-phase molar heat capacities and absolute entropies of the three 2,6-dialkylnaphthalenes studied were determined computationally. The thermodynamic stability of the compounds in both the crystalline and gaseous phases was evaluated by the determination of the Gibbs energies of formation and compared with the ones reported in the literature for 2,6-dimethylnaphthalene. From fluorescence spectroscopy measurements, the optical properties of the compounds studied and of naphthalene were evaluated in solution and in the solid state. PMID:26716880
NASA Astrophysics Data System (ADS)
Khlystov, A.; Lin, M.; Saleh, R.
2008-12-01
Ambient aerosol, a significant portion of which is composed of a complex mixture of semi-volatile organic compounds, has substantial impact on human welfare via adverse health effects and global climate change. Prediction of ambient semi-volatile organic aerosol remains highly problematic and air quality models often do not agree with observations. One of the pieces of knowledge needed for better predictions of ambient semi- volatile organic aerosol is understanding of the partitioning of semi-volatile compounds between the gas and the aerosol phases. In this study the equilibrium thermodynamic properties of a number of multi-component aerosols were investigated under controlled laboratory conditions, as well as in the field. In the laboratory experiments, model mixtures of organic compounds as well as modified ambient aerosols were tested. The ambient aerosols were modified in a controlled way by adding known amounts of different organic substances of known thermodynamic properties. The equilibrium gas / aerosol partitioning in a temperature range relevant to ambient conditions was investigated using the Integrated Volume Method (IVM). The field measurements of ambient aerosol equilibrium properties were carried out during June 2007 - January 2008 at the FACTS research facility in Duke Forest (Chapel Hill, NC). The results can be used to derive equilibrium vapor pressures and activity coefficients of test compounds and to verify and improve the parameterizations used in group contribution models, such as UNFAC.
Disalvo, E A; Martini, M F; Bouchet, A M; Hollmann, A; Frías, M A
2014-09-01
Water appears as a common intermediary in the mechanisms of interaction of proteins and polypeptides with membranes of different lipid composition. In this review, how water modulates the interaction of peptides and proteins with lipid membranes is discussed by correlating the thermodynamic response and the structural changes of water at the membrane interphases. The thermodynamic properties of the lipid-protein interaction are governed by changes in the water activity of monolayers of different lipid composition according to the lateral surface pressure. In this context, different water populations can be characterized below and above the phase transition temperature in relation to the CH? conformers' states in the acyl chains. According to water species present at the interphase, lipid membrane acts as a water state regulator, which determines the interfacial water domains in the surface. It is proposed that those domains are formed by the contact between lipids themselves and between lipids and the water phase, which are needed to trigger adsorption-insertion processes. The water domains are essential to maintain functional dynamical properties and are formed by water beyond the hydration shell of the lipid head groups. These confined water domains probably carries information in local units in relation to the lipid composition thus accounting for the link between lipidomics and aquaomics. The analysis of these results contributes to a new insight of the lipid bilayer as a non-autonomous, responsive (reactive) structure that correlates with the dynamical properties of a living system. PMID:25085854
Intermolecular potentials and the accurate prediction of the thermodynamic properties of water
Shvab, I.; Sadus, Richard J.
2013-11-21
The ability of intermolecular potentials to correctly predict the thermodynamic properties of liquid water at a density of 0.998 g/cm{sup 3} for a wide range of temperatures (298–650 K) and pressures (0.1–700 MPa) is investigated. Molecular dynamics simulations are reported for the pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, and Joule-Thomson coefficient of liquid water using the non-polarizable SPC/E and TIP4P/2005 potentials. The results are compared with both experiment data and results obtained from the ab initio-based Matsuoka-Clementi-Yoshimine non-additive (MCYna) [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] potential, which includes polarization contributions. The data clearly indicate that both the SPC/E and TIP4P/2005 potentials are only in qualitative agreement with experiment, whereas the polarizable MCYna potential predicts some properties within experimental uncertainty. This highlights the importance of polarizability for the accurate prediction of the thermodynamic properties of water, particularly at temperatures beyond 298 K.
Intermolecular potentials and the accurate prediction of the thermodynamic properties of water
NASA Astrophysics Data System (ADS)
Shvab, I.; Sadus, Richard J.
2013-11-01
The ability of intermolecular potentials to correctly predict the thermodynamic properties of liquid water at a density of 0.998 g/cm3 for a wide range of temperatures (298-650 K) and pressures (0.1-700 MPa) is investigated. Molecular dynamics simulations are reported for the pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, and Joule-Thomson coefficient of liquid water using the non-polarizable SPC/E and TIP4P/2005 potentials. The results are compared with both experiment data and results obtained from the ab initio-based Matsuoka-Clementi-Yoshimine non-additive (MCYna) [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] potential, which includes polarization contributions. The data clearly indicate that both the SPC/E and TIP4P/2005 potentials are only in qualitative agreement with experiment, whereas the polarizable MCYna potential predicts some properties within experimental uncertainty. This highlights the importance of polarizability for the accurate prediction of the thermodynamic properties of water, particularly at temperatures beyond 298 K.
Intermolecular potentials and the accurate prediction of the thermodynamic properties of water.
Shvab, I; Sadus, Richard J
2013-11-21
The ability of intermolecular potentials to correctly predict the thermodynamic properties of liquid water at a density of 0.998 g?cm(3) for a wide range of temperatures (298-650 K) and pressures (0.1-700 MPa) is investigated. Molecular dynamics simulations are reported for the pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, and Joule-Thomson coefficient of liquid water using the non-polarizable SPC?E and TIP4P?2005 potentials. The results are compared with both experiment data and results obtained from the ab initio-based Matsuoka-Clementi-Yoshimine non-additive (MCYna) [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] potential, which includes polarization contributions. The data clearly indicate that both the SPC?E and TIP4P?2005 potentials are only in qualitative agreement with experiment, whereas the polarizable MCYna potential predicts some properties within experimental uncertainty. This highlights the importance of polarizability for the accurate prediction of the thermodynamic properties of water, particularly at temperatures beyond 298 K. PMID:24320337
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.
First-Principles Study for Thermodynamic Properties of Solid {KNO}2 System
NASA Astrophysics Data System (ADS)
Peng, Qiang; Ding, Jing; Wei, Xiaolan; Jiang, Gan; Yang, Xiaoxi
2015-11-01
To enable us better understand the performance of molten salt energy storage in a solar thermal power system, thermodynamic properties of the solid {KNO}2 system at ambient pressure and temperatures between 0 K and 711 K are determined by first-principles simulation based on density functional perturbation theory calculations with plane waves and pseudopotentials. Thermodynamic parameters of the Debye temperature, specific heat capacity at constant volume, phonon transfer speed, phonon mean free path, and phonon thermal conductivity as a function of temperature are estimated. The results show that the calculated phonon thermal conductivity is in good agreement with experimental values, but the calculated specific heat capacity at constant volume is lower than measured values. The isometric specific heat capacity of {KNO}2 is 75.03 {J}{\\cdot }{mol}^{-1}{\\cdot }{K}^{-1}, and the phonon thermal conductivity is 2.37 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} at ambient temperature.
NASA Astrophysics Data System (ADS)
Farsaci, F.; Ficarra, S.; Russo, A.; Galtieri, A.; Tellone, E.
2015-07-01
In this paper, we will show the possibility of studying physical properties and irreversible phenomena that occur in blood by applying the dielectric Kluitenberg's nonequilibrium thermodynamic theory. Namely, we shall use some recent extensions of this theory that allow to infer its main characteristic parameters from experimental measures. Applying these results to the study of normal and diabetic blood we show, by comparing them, that it is possible to determine the difference, in some details, of the amount of particular phenomena occurring inside them and give a biological meaning to these phenomena. Moreover, observing a correspondence between a particular value of the frequency for which state coefficients are equal and glucose levels we introduce an alternative diagnostic method to measure the values of the glucose in the blood by determining only this frequency value. The thermodynamic description will be completed by determining the trend of the entropy production.
Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.
1990-12-01
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 analyses of key HDN reaction networks. This report is the first in a series that will lead to an analysis of a three-ring HDN system; the carbazole/hydrogen reaction network. 2-Aminobiphenyl is the initial intermediate in the HDN pathway for carbazole, which consumes the least hydrogen possible. Measurements leading to the calculation of the ideal-gas thermodynamic properties for 2-aminobiphenyl are reported. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for selected temperatures between 298.15 K and 820 K. The critical temperature and critical density were determined for 2-aminobiphenyl with the d.s.c., and the critical pressure was derived. The Gibbs energies of formation are used in thermodynamic calculations to compare the feasibility of the initial hydrogenolysis step in the carbazole/H{sub 2} network with that of its hydrocarbon and oxygen-containing analogous; i.e., fluorene/H{sub 2} and dibenzofuran/H{sub 2}. Results of the thermodynamic calculations are compared with those of batch-reaction studies reported in the literature. 57 refs., 8 figs., 18 tabs.
Thermodynamic properties of a geothermal working fluid; 90% isobutane-10% isopentane: Final report
Gallagher, J.S.; Linsky, D.; Morrison, G.; Levelt Sengers, J.M.H.
1987-04-01
We present tables of thermodynamic properties, and dew and bubble properties, of a mixture of 90 mol % isobutane and 10 mol % isopentane, a working fluid in a binary geothermal power cycle. The tables are generated by a formulation of the Helmholtz free energy, in which the mixture properties are mapped onto the known properties of pure isobutane by means of the principle of generalized corresponding states. The data base for the Helmholtz free energy formulation is new. We report data obtained in three different apparatus: critical-line and isopentane vapor pressure data obtained in a visual cell; vapor-liquid equilibria data obtained in a mercury-operated variable-volume cell; and pressure-volume-temperature data for the 90 mol %-10 mol % mixture obtained in a semi-automated Burnett-isochoric apparatus. The principles of the methods, and estimates of the reliability, are discussed and all experimental data are compared with the surface. The results are tables of specific volume, enthalpy, entropy, specific heat and density and temperature derivatives of the pressure at 10 K temperature increments from 240 to 600 K along isobars from 0.01 to 20 MPa. Separate tables are prepared from the dew and bubble properties of the 90-10 mixture. Estimates of the effects of isomeric impurity of isobutane are given in graphical form.
Llovell, Fèlix; Vega, Lourdes F
2006-06-15
We present in this work the application of the soft-SAFT equation of state (EoS) to the calculation of some main derivative properties, including heat capacities, reduced bulk modulus, Joule-Thomson coefficient, and speed of sound. Calculations have been performed analytically through the derivation of a primary thermodynamic potential function. The application to the n-alkanes, n-alkenes, and 1-alkanols families has been done in a semipredictive manner, with the molecular parameters of the equation obtained from previous fitting to vapor-liquid equilibrium data of the same compounds. The equation is able to capture the typical extrema isothermal derivative properties exhibit with respect to density, providing quantitative agreement with experimental (or correlation) data in some cases. Results in the vicinity of the critical point are improved by adding a crossover treatment to take into account the long-range fluctuations present in this region. By taking advantage of the molecular nature of the equation, we have been able to separate and quantify the different contributions (reference fluid, chain, and association) to the total derivative properties. The association plays a predominant role in energetic properties, such as the heat capacities, while there is a competition between association and chain length as the chain length of the compound increases for volumetric properties, such as the isothermal compressibility. These results act in favor of the molecular-based equations, like soft-SAFT, as predictive tools for several applications. PMID:16771416
Emergence of equilibrium thermodynamic properties in quantum pure states. I. Theory.
Fresch, Barbara; Moro, Giorgio J
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 Schrodinger 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. PMID:20649339
Emergence of equilibrium thermodynamic properties in quantum pure states. I. Theory
Fresch, Barbara; Moro, Giorgio J.
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.
Thermodynamic properties of alloys of the Ni-Sc and Ni-Y systems
NASA Astrophysics Data System (ADS)
Shevchenko, M. A.; Ivanov, M. I.; Berezutskii, V. V.; Kudin, V. G.; Sudavtsova, V. S.
2014-06-01
Partial and integral enthalpies of mixing for Ni-Y melts at 1775 K (0 < x Y < 0.34), 1850 K (0.72 < x Y < 1) and Ni-Sc at 1880 K (0 < x Sc < 0.35, 0.51 < x Sc < 1) are determined by means of calorimetry. Thermodynamic properties of liquid and solid alloys and phase diagrams of Ni-Sc(Y) systems in wide ranges of concentration and temperature are modeled using the ideal associated solution theory. It is found that the activities of components exhibit strong negative deviations from the Raoult's law.
Thermodynamic properties of semiconductor compounds studied based on Debye-Waller factors
NASA Astrophysics Data System (ADS)
Van Hung, Nguyen; Toan, Nguyen Cong; Ba Duc, Nguyen; Vuong, Dinh Quoc
2015-08-01
Thermodynamic properties of semiconductor compounds have been studied based on Debye-Waller factors (DWFs) described by the mean square displacement (MSD) which has close relation with the mean square relative displacement (MSRD). Their analytical expressions have been derived based on the statistical moment method (SMM) and the empirical many-body Stillinger-Weber potentials. Numerical results for the MSDs of GaAs, GaP, InP, InSb, which have zinc-blende structure, are found to be in reasonable agreement with experiment and other theories. This paper shows that an elements value for MSD is dependent on the binary semiconductor compound within which it resides.
NASA Astrophysics Data System (ADS)
Moustafa, Sabry Gad Al-Hak Mohammad
Molecular simulation (MS) methods (e.g. Monte Carlo (MC) and molecular dynamics (MD)) provide a reliable tool (especially at extreme conditions) to measure solid properties. However, measuring them accurately and efficiently (smallest uncertainty for a given time) using MS can be a big challenge especially with ab initio-type models. In addition, comparing with experimental results through extrapolating properties from finite size to the thermodynamic limit can be a critical obstacle. We first estimate the free energy (FE) of crystalline system of simple discontinuous potential, hard-spheres (HS), at its melting condition. Several approaches are explored to determine the most efficient route. The comparison study shows a considerable improvement in efficiency over the standard MS methods that are known for solid phases. In addition, we were able to accurately extrapolate to the thermodynamic limit using relatively small system sizes. Although the method is applied to HS model, it is readily extended to more complex hard-body potentials, such as hard tetrahedra. The harmonic approximation of the potential energy surface is usually an accurate model (especially at low temperature and large density) to describe many realistic solid phases. In addition, since the analysis is done numerically the method is relatively cheap. Here, we apply lattice dynamics (LD) techniques to get the FE of clathrate hydrates structures. Rigid-bonds model is assumed to describe water molecules; this, however, requires additional orientation degree-of-freedom in order to specify each molecule. However, we were able to efficiently avoid using those degrees of freedom through a mathematical transformation that only uses the atomic coordinates of water molecules. In addition, the proton-disorder nature of hydrate water networks adds extra complexity to the problem, especially when extrapolating to the thermodynamic limit is needed. The finite-size effects of the proton disorder contribution is shown to vary slowly with system-size. This allow us to get the FE in the thermodynamic limit by extrapolating the one isomer results to infinity and correct for that by the effect from considering proton-disorder measured at a small system. These techniques are applied to empty hydrates (of types: SI, SII, and SH) to estimate their thermodynamic stability. For conditions where the harmonic model fails, performing MS is needed to estimate rigorously the full (harmonic plus anharmonic) quantity. Although several MS methods are available for that purpose, they do not benefit from the harmonic nature of crystals---which represents the main contribution and is cheap to compute. In other words, those "conventional" methods always "start from scratch" even at states where anharmonic part is negligible. In this work, we develop very efficient MS methods that leverage information, on-the-fly, from the harmonic behavior of configurations such that the anharmonic contributions are directly measured. The approach is named harmonically-mapped averaging (HMA) for the rest of this thesis. Since the major contribution of thermodynamic properties comes from the harmonic nature of crystal, the fluctuations in the anharmonic quantities is to be small; hence, uncertainty associated with the HMA method is small. The HMA method is given in a general formulation such that it can handle properties related to both first- and second-derivatives of free energy. The HMA approach is first applied to Lennard-Jones (LJ) model. First- and second-derivatives of FE with respect to temperature and volume yield the following properties: energy, pressure, isochoric heat capacity, bulk modulus, and thermal pressure coefficient. A considerable improvement in the efficiency of measuring those properties is observed even at melting conditions where anharmonicity is non-negligible. First-derivative properties are computed with 100 to 10,000 times less computational effort, while speedup for the second-derivative properties exceeds a millionfold for the highest density examined. In addition, the finite-size and long-range cutoff effects of the anharmonic contribution is much smaller than those due to harmonic part. Therefore, we were able to get the thermodynamic limit of thermodynamic properties by extrapolating the harmonic contribution to infinity and fix that with the anharmonic contribution from MS of small systems. Moreover, the anharmonic trajectory shows better features than the conventional one; it equilibrates almost instantaneously and data is less correlated (i.e. good statistics can be obtained with shorter trajectory). As a byproduct of the HMA, the free energy along an isochore is computed using thermodynamic integration (TI) technique of energy. Again, the HMA shows substantial improvement (50--1000 speedup) over the well-known Frenkel-Ladd integration (with Einstein crystal reference) method. Finally, to test the method against a more sophisticated model, we applied it to an embedded-atom-model (EAM) model of iron system. The results show a qualitatively similar behavior as that of LJ model. Finally, the method is applied to tackle one of the long-standing problems of Earth science; namely, the crystal structure of the Earth's inner core (IC). (Abstract shortened by UMI.).
Thermodynamic properties of a solid exhibiting the energy spectrum given by the logistic map
Curado; Rego-Monteiro
2000-06-01
We show that the infinite-dimensional representation of the recently introduced logistic algebra can be interpreted as a nontrivial generalization of the Heisenberg or oscillator algebra. This allows us to construct a quantum Hamiltonian having the energy spectrum given by the logistic map. We analyze the Hamiltonian of a solid whose collective modes of vibration are described by this generalized oscillator and compute the thermodynamic properties of the model in the two-cycle and r=3.6785 chaotic region of the logistic map. PMID:11088298
Messerly, J.F.; Todd, S.S.; Finke, H.L.; Gammon, B.E.
1987-01-01
Condensed-phase heat capacities and enthalpies were determined at temperatures from near 10 to 400 K for N-methylpyrrole, 2,5-dimethylpyrrole, piperidine, 2-methylpiperidine, 4-methylpyridine, and N-methylcarbazole and were used to provide the Gibbs energy, enthalpy, entropy and heat capacity along the vapor saturation line at temperatures from 0 to 400 K. The corresponding ideal gas thermodynamic properties were derived with available vapor pressure and enthalpy of vaporization data. The Gibbs energy, enthalpy, and entropy of formation were derived for the ideal gas at selected temperatures with available enthalpy of combustion data. 37 refs., 9 tabs.
Thermodynamic properties and oxygen stoichiometry of Ba2Cu3O5 + ?
NASA Astrophysics Data System (ADS)
Kovba, M. L.; Tiflova, L. A.; Istomin, S. Ya.; Skolis, Yu. Ya.; Monaenkova, A. S.
2014-03-01
The thermodynamic properties and oxygen stoichiometry of Ba2Cu3O5 + ? are studied by means of the electromotive force (EMF) with a fluoride electrolyte, dissolution calorimetry, and thermogravimetry. It is shown that the temperature dependence of the Gibbs energy of the formation of barium cuprate from simple oxides and oxygen in the temperature range of 860-1120 K can be described by the polynomial ?f, ox G ?(Ba2Cu3O5 + ?) ± 0.1 (kJ/mol) = -291.78 + 1.127 T - 0.13207 Tln T (kJ/mol).
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.
Structural, elastic and thermodynamic properties of Mo3Si and Mo3Ge
NASA Astrophysics Data System (ADS)
Zhong, Sheng-Yi; Chen, Zhe; Wang, Mingliang; Chen, Dong
2016-01-01
The structural, elastic and thermodynamic properties of the cubic Mo3Si and Mo3Ge intermetallics were investigated using density functional theory within the local density approximation (LDA) and generalized gradient approximation (GGA) methods. The results showed that the structural and elastic properties (i.e., elastic constants, bulk modulus, shear modulus and Young's modulus) derived by the GGA method were in good agreement with the available experimental and theoretical values. Using the quasi-harmonic Debye model, the variations of the Debye temperature, heat capacity and coefficient of thermal expansion under pressure ranging from 0 to 25 GPa and at temperature ranging from 0 to 1800 K were obtained and analyzed for both compounds.
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.
Atomic structure, mechanical quality, and thermodynamic property of TiHx phases
NASA Astrophysics Data System (ADS)
Liang, C. P.; Gong, H. R.
2013-07-01
Titanium hydrides TiHx (x = 1, 1.25, 1.5, 1.75, and 2) with the cubic fluorite-type (face-centered cubic, Î´ phase) and face-centered-tetragonal (É› phase, c/a < 1; Î³ phase, c/a > 1) structures were systematically investigated and compared through first-principles calculation. The H location of TiHx was carefully determined by comparing the calculated properties with experimental results. Moreover, the mechanical properties of É› and Î³ phases were calculated and found to play an important role in the brittle/ductile behavior of TiHx phases. In addition, the thermodynamic quantities were also derived for providing a deeper understanding of TiHx phases. The calculated results were widely compared with the available experimental results in the literature, and could clarify the three controversies regarding atomic configuration, stability, and hydrogen embrittlement of TiHx phases in the literature.
First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.
Bandura, Andrei V; Evarestov, Robert A
2012-07-01
The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and GrÃ¼neisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. PMID:22514059
Thermodynamic Properties of CaSiO3 Perovskite at High Pressure and High Temperature
NASA Astrophysics Data System (ADS)
Liu, Zi-Jiang; Tan, Xiao-Ming; Guo, Yuan; Zheng, Xiao-Ping; Wu, Wen-Zhao
2009-06-01
The thermodynamic properties of tetragonal CaSiO3 perovskite are predicted at high pressures and temperatures using the Debye model for the first time. This model combines the ab initio calculations within local density approximation using pseudopotentials and a plane wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. It is found that the calculated equation of state is in excellent agreement with the observed values at ambient condition. Based on the first-principles study and the Debye model, the thermal properties including the Debye temperature, the heat capacity, the thermal expansion and the entropy are obtained in the whole pressure range from 0 to 150 GPa and temperature range from 0 to 2000 K.
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
SteamTablesGrid: An ActiveX control for thermodynamic properties of pure water
NASA Astrophysics Data System (ADS)
Verma, Mahendra P.
2011-04-01
An ActiveX control, steam tables grid ( StmTblGrd) to speed up the calculation of the thermodynamic properties of pure water is developed. First, it creates a grid (matrix) for a specified range of temperature (e.g. 400-600 K with 40 segments) and pressure (e.g. 100,000-20,000,000 Pa with 40 segments). Using the ActiveX component SteamTables, the values of selected properties of water for each element (nodal point) of the 41×41 matrix are calculated. The created grid can be saved in a file for its reuse. A linear interpolation within an individual phase, vapor or liquid is implemented to calculate the properties at a given value of temperature and pressure. A demonstration program to illustrate the functionality of StmTblGrd is written in Visual Basic 6.0. Similarly, a methodology is presented to explain the use of StmTblGrd in MS-Excel 2007. In an Excel worksheet, the enthalpy of 1000 random datasets for temperature and pressure is calculated using StmTblGrd and SteamTables. The uncertainty in the enthalpy calculated with StmTblGrd is within ±0.03%. The calculations were performed on a personal computer that has a "Pentium(R) 4 CPU 3.2 GHz, RAM 1.0 GB" processor and Windows XP. The total execution time for the calculation with StmTblGrd was 0.3 s, while it was 60.0 s for SteamTables. Thus, the ActiveX control approach is reliable, accurate and efficient for the numerical simulation of complex systems that demand the thermodynamic properties of water at several values of temperature and pressure like steam flow in a geothermal pipeline network.
NASA Astrophysics Data System (ADS)
Pokrovski, Gleb; Gout, Robert; Schott, Jacques; Zotov, Alexandre; Harrichoury, Jean-Claude
1996-03-01
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 Â°C, respectively, in acid solutions (pH < 6) at the saturated vapor pressure of the system. Raman spectroscopic measurements were performed on As 2O 3-H 2O solutions (0.02 â‰¤ As â‰¤ 6 m; 0 â‰¤ pH â‰¤ 9) at temperatures from 20 to 275 Â°C. Results indicate that H 3AsO 30(aq) is the dominant As-bearing species at concentrations up to ~1 m over a wide range of pH (0-8) and temperature (20-300 Â°C). At higher As concentrations (â‰¥1-2 m), a polymerization-dehydration of H 3AsO 30(aq) occurs via the formation of As-O-As bonds, leading to the formation of poly-As aqueous complexes. These experimental results were combined with corresponding properties for arsenolite, claudetite, and orpiment obtained in this study to generate H 3AsO 30(aq) thermodynamic properties within the framework of the revised HKF equation of state ( Helgeson et al., 1981; Tanger and Helgeson, 1988). Calculations carried out using these properties indicate that orpiment, realgar, and native As can control As concentration in epithermal fluids at T â‰¤ 150-200 Â°C. At higher temperatures (â‰¥250 Â°C), it is shown that arsenopyrite in association with pyrite and pyrrhotite or cassiterite can control As deposition in hydrothermal environments.
NASA Technical Reports Server (NTRS)
Talcott, N. A., Jr.
1977-01-01
Equations and computer code are given for the thermodynamic properties of gaseous fluorocarbons in chemical equilibrium. In addition, isentropic equilibrium expansions of two binary mixtures of fluorocarbons and argon are included. The computer code calculates the equilibrium thermodynamic properties and, in some cases, the transport properties for the following fluorocarbons: CCl2F, CCl2F2, CBrF3, CF4, CHCl2F, CHF3, CCL2F-CCl2F, CCLF2-CClF2, CF3-CF3, and C4F8. Equilibrium thermodynamic properties are tabulated for six of the fluorocarbons(CCl3F, CCL2F2, CBrF3, CF4, CF3-CF3, and C4F8) and pressure-enthalpy diagrams are presented for CBrF3.
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.
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.
First principal studya of structural, electronic and thermodynamic properties of KTaO3-perovskite.
NASA Astrophysics Data System (ADS)
Bouafia, H.; Akriche, A.; Ascri, R.; Ghalouci, L.; Sahli, B.; Hiadsi, S.; Abidri, B.; Amrani, B.
2013-03-01
The results of first-principles theoretical study of structural, elastic, electronic and thermodynamic properties of KTaO3 compound, have been performed using the full-potential linear augmented plane-wave method plus local orbitals (FP-APW+lo) as implemented in the Wien2k code. The exchange-correlation energy, is treated in generalized gradient approximation (GGA) using the Perdew-Burke-Ernzerhof (PBE96) and PBEsol, Perdew 2008 parameterization. Also we have used the Engel-Vosko GGA optimizes the corresponding potential for band structure calculations. The calculated equilibrium parameter is in good agreement with other works. The elastic constants were calculated by using the Mehl method. The electronic band structure of this compound has been calculated using the Angel-Vosko (EV) generalized gradient approximation (GGA) for the exchange correlation potential. We deduced that KTaO3-perovskite exhibit an indirect from R to ? point. To complete the fundamental characterization of KTaO3 material we have analyzed the thermodynamic properties using the quasi-harmonic Debye model.
Thermodynamic properties of calcium-magnesium alloys determined by emf measurements
Newhouse, JM; Poizeau, S; Kim, H; Spatocco, BL; Sadoway, DR
2013-02-28
The thermodynamic properties of calcium-magnesium alloys were determined by electromotive force (emf) measurements using a Ca(in Bi)vertical bar CaF2 vertical bar Ca(in Mg) cell over the temperature range 713-1048 K. The activity and partial molar Gibbs free energy of calcium in magnesium were calculated for nine Ca-Mg alloys, calcium mole fractions varying from x(ca) = 0.01 to 0.80. Thermodynamic properties of magnesium in calcium and the molar Gibbs free energy of mixing were estimated using the Gibbs-Duhem relationship. In the all-liquid region at 1010 K, the activity of calcium in magnesium was found to range between 8.8 x 10(-4) and 0.94 versus pure calcium. The molecular interaction volume model (MIVM) was used to model the activity coefficient of Ca and Mg in Ca-Mg liquid alloys. Based on this work, Ca-Mg alloys show promise as the negative electrode of a liquid metal battery in which calcium is the itinerant species: alloying with Mg results in both a decrease in operating temperature and suppression of Ca metal solubility in the molten salt electrolyte. (C) 2012 Elsevier Ltd. All rights reserved.
Magneto-elastic effects and thermodynamic properties of ferromagnetic hcp Co
NASA Astrophysics Data System (ADS)
Kuang, Fang-Guang; Kuang, Xiao-Yu; Kang, Shu-Ying; Mao, Ai-Jie
2014-05-01
Using first principles projector augmented wave (PAW) potential method, the magneto-elastic effects and thermodynamic properties of ferromagnetic hcp Cobalt at high pressure and temperature are investigated. The calculated elastic constants from PBE+U method demonstrate a noticeable improvement with regard to experimental data. Various physical quantities under high pressure also present significant improvements, such as the bulk modulus, shear modulus, Young's modulus, Debye temperature, various sound velocities and the normalized acoustic velocities in the meridian plane. That is due to the fact that Cobalt system possesses large correlation effects. Meanwhile, the phonon dispersion curves are in excellent agreement with experimental data. It is not observed any anomaly or instability under compression. However, according to the E2g-phonon frequencies, the obtained pressure variation of C44 elastic modulus also suggests that the system has miraculous magneto-elastic effects. Moreover, the pressure and temperature dependence of thermodynamic properties are derived within the quasi-harmonic approximation for the first time. The obtained Grüneisen ratio, Anderon-Grüneisen parameter and the volume dependence of Grüneisen ratio display manifestly temperature and pressure dependences.
The thermodynamic properties to 700 K of naphthalene and 2,7-dimethylnaphthalene
NASA Astrophysics Data System (ADS)
Chirico, R. D.; Knipmeyer, S. E.; Nguyen, A.; Steele, W. V.
1993-08-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for naphthalene and 2,7-dimethylnaphthalene. Experimental methods included adiabatic heat-capacity calorimetry, vibrating-tube densitometry, comparative ebulliometry, and differential-scanning calorimetry (d.s.c.). The critical temperature and critical density were determined experimentally for each compound and the critical pressures were derived from fitting procedures. Vapor-pressure measurements reported in the literature were compared with the results obtained in this research. Enthalpies of vaporization and sublimation were derived from the experimental measurements and compared with literature results. New self-consistent equations for the variation of sublimation pressure with temperature for naphthalene and 2,7-dimethylnaphthalene were derived. Literature values for entropies and enthalpies of the liquid phases and energies of combustion were combined with the present results to derive entropies, enthalpies, and Gibbs energies of formation for the ideal gases for selected temperatures between 298.15 K and 700 K. The ideal-gas properties for naphthalene were compared with values obtained using statistical mechanics with various fundamental vibrational frequency assignments available in the literature. A scheme to estimate the ideal-gas thermodynamic functions for alkylnaphthalenes was updated. The barrier to methyl-group rotation in 2,7-dimethylnaphthalene was shown to be of the same order of magnitude as that published for toluene. Values for ideal-gas entropies for 2-methylnaphthalene in the temperature range 300 K to 700 K were estimated.
Computer-assisted analyses of the thermodynamic properties of slags in coal-combustion systems
Blander, M.; Pelton, A.D.
1983-09-01
Equations were developed for the analysis of the thermodynamic properties of molten silicate solutions; the equations take into account the unusual concentration and temperature dependence of the solution properties of ordered systems. For binary systems, these equations were coupled with an optimization computer program to analyze all reliable thermodynamic data, including phase diagrams, free energies and enthalpies of formation of compounds, activities of components, enthalpies of mixing, entropies of fusion, miscibility gaps, etc. In this manner, we analyzed data for five binary systems: CaO-SiO/sub 2/, Na/sub 2/O-SiO/sub 2/, CaO-Al/sub 2/O/sub 3/, Na/sub 2/O-Al/sub 2/O/sub 3/, and Al/sub 2/O/sub 3/-SiO/sub 2/. The results of the binary systems were combined, and an analysis done of three ternary systems: CaO-Al/sub 2/O/sub 3/-SiO/sub 2/, Na/sub 2/O-CaO-SiO/sub 2/, and Na/sub 2/O-Al/sub 2/O/sup 3/-SiO/sub 2/. A tentative analysis of the quaternary system, Na/sub 2/O-CaO-Al/sub 2/O/sub 3/-SiO/sub 2/, was also undertaken. 53 references, 51 figures, 3 tables.
Liu, Ze; Han, Jiuqiang; Lv, Hongqiang; Liu, Jun; Liu, Ruiling
2016-04-01
Circular RNAs (circRNAs) were found more than 30 years ago, but have been treated as molecular flukes in a long time. Combining deep sequencing studies with bioinformatics technique, thousands of endogenous circRNAs have been found in mammalian cells, and some researchers have proved that several circRNAs act as competing endogenous RNAs (ceRNAs) to regulate gene expression. However, the mechanism by which the precursor mRNA to be transformed into a circular RNA or a linear mRNA is largely unknown. In this paper, we attempted to bioinformatically identify shared genomic features that might further elucidate the mechanism of formation and proposed a SVM-based model to distinguish circRNAs from non-circularized, expressed exons. Firstly, conformational and thermodynamic dinucleotide properties in the flanking introns were extracted as potential features. Secondly, two feature selection methods were applied to gain the optimal feature subset. Our 10-fold cross-validation results showed that the model can be used to distinguish circRNAs from non-circularized, expressed exons with an Sn of 0.884, Sp of 0.900, ACC of 0.892, MCC of 0.784, respectively. The identification results suggest that conformational and thermodynamic properties in the flanking introns are closely related to the formation of circRNAs. Datasets and the tool involved in this paper are all available at https://sourceforge.net/projects/predicircrnatool/files/. PMID:26917277
Evaluation of the thermodynamic properties of hydrated metal oxide nanoparticles by INS techniques
Spencer, Elinor; Ross, Dr. Nancy; Parker, Stewart F.; Kolesnikov, Alexander I
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].
Correlation of thermodynamic and genetic properties in the Tn10 encoded TET gene control region.
Hillen, W; Unger, B
1982-01-01
The thermal stability of the Tn10 encoded tetracycline resistance (TET) gene control region is investigated by melting studies using purified DNA restriction fragments containing various amounts of flanking sequences. In order to study the thermodynamic properties of this control region under conditions, where enough flanking DNA is present to mimic the situation in the chromosome, the five step melting process of a 1450-bp DNA fragment is analyzed. Because most of the sequence of this DNA is not known, the assignment of the melting transitions to segments of the DNA is done by an experimental method. This employs the preparation of subfragments from the 1450-bp DNA and comparison of their denaturation profiles with the one of the intact sequence. This approach results in the complete assignment of the five denaturation steps. Rather than from the ends, the unwinding starts from the TET gene control region in the middle of the 1450-bp sequence. A clear correlation between the thermodynamic and genetic properties of this DNA is observed. The regulatory sequence forms a small cooperative unit with the lowest stability in the entire fragment. The thermal denaturation of the TET repressor. TET operator complex reveals, that the TET repressor specifically recognizes the double stranded TET operator DNA and stabilizes this structure by 2.4 degrees C. This results is also discussed as an example of the possible action of denaturing or stabilizing proteins on this genetic control region. PMID:6281740
NASA Astrophysics Data System (ADS)
Varshney, Dinesh; Shriya, S.; Varshney, M.; Singh, N.; Khenata, R.
2015-08-01
Pressure-dependent first-order phase transition, mechanical, elastic, and thermodynamical properties of cubic zinc blende to rock-salt structures in 3 C silicon carbide (SiC) are presented. An effective interatomic interaction potential for SiC is formulated. The potential for SiC incorporates long-range Coulomb, charge transfer interactions, covalency effect, Hafemeister and Flygare type short-range overlap repulsion extended up to the second-neighbour ions, van der Waals interactions and zero point energy effects. The developed potential including many body non-central forces validates the Cauchy discrepancy successfully to explain the high-pressure structural transition, and associated volume collapse. The 3 C SiC ceramics lattice infers mechanical stiffening, thermal softening, and ductile (brittle) nature from the pressure (temperature) dependent elastic constants behaviour. To our knowledge, these are the first quantitative theoretical predictions of the pressure and temperature dependence of mechanical and thermodynamical properties explicitly the mechanical stiffening, thermally softening, and brittle/ductile nature of 3 C SiC and still awaits experimental confirmations.
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
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
Prediction of the thermodynamic properties of aqueous metal complexes to 1000 degrees C and 5 kb.
Sverjensky, D A; Shock, E L; Helgeson, H C
1997-04-01
A large number of aqueous metal complexes contribute significantly to hydrothermal, metamorphic, and magmatic processes in the crust of the Earth. Nevertheless, relatively few thermodynamic data other than dissociation constants (K) for a few dozen of these complexes have been determined experimentally at elevated temperatures and pressures. The calculations summarized below are intended to supplement these experimental data by providing interim predictions of the thermodynamic properties of supercritical aqueous metal complexes using the revised HKF (Helgeson et al., 1981) equations of state for aqueous species (Tanger and Helgeson, 1988; Shock et al., 1992) and correlations among equations of state parameters and standard partial molal properties at 25 degrees C and 1 bar (Shock and Helgeson, 1988, 1990; Shock et al., 1989). These equations and correlations permit retrieval of the conventional standard partial molal entropies (mean S0), volumes (mean V0), and heat capacities (mean C0P) of aqueous metal complexes at 25 degrees C and 1 bar from published values of log K in the supercritical region and the limited number of experimental dissociation constants available in the literature over relatively short ranges of elevated temperature at PSAT (PSAT and SAT are used in the present communication to refer to pressures corresponding to liquid-vapor equilibrium for the system H2O except at temperatures <100 degrees C, where they refer to the reference pressure of 1 bar). The standard partial molal properties computed in this way can then be used to generate corresponding values of delta mean S0, delta mean V0, and delta mean C0P of association, which for similar complexes correlate linearly with mean S0, mean V0 and mean C0P, respectively, of the constituent cations and ligands at 25 degrees C and 1 bar. Generalizing these correlations and combining them with the equations of state permits prediction of the temperature and pressure dependence of log K and other thermodynamic properties of a large number of aqueous metal complexes. As a consequence, it is possible to retrieve values of log K at 25 degrees C and 1 bar from the results of hydrothermal experiments at higher temperatures and pressures or to predict values of log K at hydrothermal conditions when no experimental data are available at temperatures and pressures above 25 degrees C and 1 bar. Such predictions can be made for temperatures and pressures from 0 degrees C and 1 bar to 1000 degrees C and 5000 bars. PMID:11541435
NASA Astrophysics Data System (ADS)
Neuenschwander, Wilmer
1989-06-01
Simple relationships are presented that accurately approximate the thermodynamic properties of equilibrium air mixtures from 360 to 25,000 R over the pressure range from 0.00005 to 10 atmospheres. Relationships of this approximation are based on a newly introduced concept of kinetic specific heat that relates air temperature to the kinetic energy component of enthalpy. Unique features of this methodology include: (1) explicitness of relationships, (2) enhanced computational efficiency by orders of magnitude, and (3) comparable or improved accuracy when compared with accepted approximations. Additionally, the kinetic specific heat parameter can be directly applied for accurate, computationally efficient calculation of the thermodynamic properties of nonequilibrium, dissociated air mixtures. Summary descriptions of the kinetic specific heat concept and development of the thermodynamic relationships are presented. The relationship accuracies are identified and demonstrated by extensive comparisons with the exact solution data of Hilsenrath and Beckett. A similar thermodynamic concept and analysis capability is not known to be available in the published literature.
Mesoscopic modeling of structural and thermodynamic properties of fluids confined by rough surfaces.
TerrÃ³n-MejÃa, Ketzasmin A; LÃ³pez-RendÃ³n, Roberto; Gama Goicochea, Armando
2015-10-21
The interfacial and structural properties of fluids confined by surfaces of different geometries are studied at the mesoscopic scale using dissipative particle dynamics simulations in the grand canonical ensemble. The structure of the surfaces is modeled by a simple function, which allows us to simulate readily different types of surfaces through the choice of three parameters only. The fluids we have modeled are confined either by two smooth surfaces or by symmetrically and asymmetrically structured walls. We calculate structural and thermodynamic properties such as the density, temperature and pressure profiles, as well as the interfacial tension profiles for each case and find that a structural order-disorder phase transition occurs as the degree of surface roughness increases. However, the magnitude of the interfacial tension is insensitive to the structuring of the surfaces and depends solely on the magnitude of the solid-fluid interaction. These results are important for modern nanotechnology applications, such as in the enhanced recovery of oil, and in the design of porous materials with specifically tailored properties. PMID:26387742
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.
Advanced working fluids: Thermodynamic properties. Final report, 1 December 1987-30 November 1989
Lee, L.L.; Gering, K.L.
1990-09-01
Electrolytes are used as working fluids in gas-fired heat pump-chiller engine cycles. To find out which molecular parameters of the electrolytes impact on cycle performance, a molecular theory, the EXP-MSA correlation, is developed for calculating solution properties, enthalpies, vapor-liquid equilibria, and engine cycle performance. Aqueous and ammoniac single and mixed salt solutions in single and multisolvent systems are investigated. The outcomes are: (1) an accurate correlation is developed to evaluate properties for concentrated electrolyte solutions (e.g., for aqueous LiBr to 19 molal); (2) sensitivity analysis is used to determine the impact of molecular parameters on the thermodynamic properties and cycle performance. The preferred electrolytes are of 1-1 valence type, small ion size, high molecular weight, and in a strongly colligative cosolvent; (3) the abilities of correlation on single-effect and double-effect engine cycles are demonstrated; (4) the operating windows are determined for a number of absorption fluids of industrial importance.
Phonon densities of states and related thermodynamic properties of high temperature ceramics.
Loong, C.-K.
1998-08-28
Structural components and semiconductor devices based on silicon nitride, aluminum nitride and gallium nitride are expected to function more reliably at elevated temperatures and at higher levels of performance because of the strong atomic bonding in these materials. The degree of covalency, lattice specific heat, and thermal conductivity are important design factors for the realization of advanced applications. We have determined the phonon densities of states of these ceramics by the method of neutron scattering. The results provide a microscopic interpretation of the mechanical and thermal properties. Moreover, experimental data of the static, structures, and dynamic excitations of atoms are essential to the validation of interparticle potentials employed for molecular-dynamics simulations of high-temperature properties of multi-component ceramic systems. We present an overview of neutron-scattering investigations of the atomic organization, phonon excitations, as well as calculations of related thermodynamic properties of Si{sub 3}N{sub 4}, {beta}-sialon, AlN and GaN. The results are compared with those of the oxide analogs such as SiO{sub 2} and Al{sub 2}O{sub 3}.
NASA Astrophysics Data System (ADS)
Abu-Shady, M.
2015-05-01
A midpoint method is introduced to calculate the chiral phase transition and thermodynamic properties in the Nambu-Jona-Lasinio (NJL) model with two flavors ( u, d). The constituent quark mass, the pressure, the energy density, and the entropy are calculated in the mean-field approximation using the midpoint technique. The phase transition was found to be crossover for all values of bare quark mass. The effect of finite temperature and chemical potential on the thermodynamic properties is studied. A comparison with other models is presented. In addition, the advantages of the midpoint technique are discussed. In conclusion, the midpoint technique successfully predicts the phase transition and thermodynamic properties with a good accuracy for numerical integrals.
NASA Astrophysics Data System (ADS)
Abu-Shady, M.
2014-09-01
A midpoint method is introduced to calculate the chiral phase transition and thermodynamic properties in the Nambu-Jona-Lasinio (NJL) model with two flavors (u,d). The constituent quark mass, the pressure, the energy density, and the entropy are calculated in the mean-field approximation using the midpoint technique. The phase transition was found to be crossover for all values of bare quark mass. The effect of finite temperature and chemical potential on the thermodynamic properties is studied. A comparison with other models is presented. In addition, the advantages of the midpoint technique are discussed. In conclusion, the midpoint technique successfully predicts the phase transition and thermodynamic properties with a good accuracy for numerical integrals.
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.
Mao, Pingli Yu, Bo; Liu, Zheng; Wang, Feng; Ju, Yang
2015-03-21
The structural, mechanical, electronic, and thermodynamic properties of Mg{sub 2}Sr 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.
Electronic, vibrational and thermodynamic properties of Ca10(AsO4)6(OH)2: first principles study
NASA Astrophysics Data System (ADS)
Zheng, Yuanlei; Gao, Tao; Gong, Yanrong; Ma, Shenggui; Yang, Mingli; Chen, Piheng
2015-12-01
The electronic, vibrational and thermodynamic properties of johnbaumite (AHAP Ca10(AsO4)6(OH)2) have been performed by First principles approach. AHAP is an indirect band-gap material of 3.98 eV. The calculated phonon dispersion indicates that AHAP is stable. For AHAP, the optical vibrational modes at the ?-point are assigned: 21E1 + 19A + 22E2 + 24B, and the frequencies agree well with available experimental data. The largest LO-TO phonon frequency splitting occurs at A mode (770.2 cm-1 to 807.6 cm-1). Finally, the thermodynamic properties of AHAP are predicted.
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)
Pardo, L. C.; Parat, B.; Barrio, M.; Tamarit, J. Ll.; López, D. O.; Salud, J.; Negrier, P.; Mondieig, D.
2005-02-01
The orientationally disordered stable and metastable mixed crystals of the two-component system (CH 3)CCl 3 (1,1,1-trichloroethane) + CBrCl 3(bromotrichloro-methane) have been characterised by means of X-ray powder diffraction and thermal analysis techniques. The thermodynamic assessment coherently reproduces the melting equilibria (the stable [R + L] and the partially metastable [FCC + L]) and provides a coherent set of data for the thermodynamic properties of non-experimentally available phase transitions of pure compounds which agree perfectly with those properties obtained from the pressure-temperature phase diagrams.
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.
Sumpter, Bobby G; Goswami, Monojoy
2009-01-01
The structural and dynamical properties of polymer nanocomposites are investigated using stochastic molecular dynamics simulations. For spherical nanoparticles dispersed in a polymer matrix the results indicate that the polymer-nanoparticle interaction strength and the overall system temperature are primarily responsible for the type of dispersed state (clustering and homogeneous dispersion) achieved. A systematic study probing temperature, polymerization, polymer-nanoparticle and nanoparticle-nanoparticle interactions strengths have been performed. In this paper, however, we focus the discussion on the results for varying polymer-nanoparticle interactions strengths at different temperatures. By examining the structure and dynamics, we show there are two kinds of `clustering transitions'; one due to thermodynamic and another due to the dynamical response of the system. From these results a representative phase diagram is developed that captures the entire simulated space and allows the easy identification of the highly dispersed and the clustered states.
The thermodynamic properties of a spin-1/2 Heisenberg ferromagnetic system using Oguchi's method
NASA Astrophysics Data System (ADS)
Mert, Gülistan
2015-11-01
The thermodynamic properties of spin-1/2 Heisenberg ferromagnetic system on the simple cubic lattice are investigated by using of Oguchi's approximation. The effects of the second-nearest-neighbor exchange interactions on the magnetization, internal energy, heat capacity, entropy and free energy of the Heisenberg ferromagnet are considered. One obtains typical ferromagnetic magnetization curves and obtains that the critical temperature increases when the second-nearest-neighbor exchange parameter increases. In the heat capacity curve, Schottky-like peaks are observed for a certain values of the second-nearest-neighbor interactions. The behaviors of magnetic entropy and free energy are presented. When the only nearest neighbor interaction is included, magnetic entropy does not reach maximum value, but the system with the second-nearest-neighbor exchange interaction reaches it. Free energy has a discontinuity point at the critical temperature.
Thermodynamic properties of aqueous solutions of sodium ibuprofen at 293.15-318.15 K
NASA Astrophysics Data System (ADS)
Manin, N. G.; Perlovich, G. L.
2015-04-01
The enthalpies of solution and dilution of aqueous solutions of sodium ibuprofen (NaIBP) with concentrations of m < 1.4 mol/kg water are measured at 293.15, 298.15, 308.15, and 318.5 K using an isoperibolic calorimeter. The heat capacity of NaIBP in the temperature range of 273.15-528.15 K is measured using a DSC 204 F1 Phoenix differential scanning calorimeter (NETZSCH, Germany). The virial coefficients of the enthalpies of aqueous solutions of NaIBP are derived in terms of the Pitzer model, and the thermodynamic properties of both the solutions and the solution components are calculated over the range of compound solubility. The variation in these characteristics as a function of concentration and temperature is analyzed.
Ab initio calculation of the thermodynamic properties and phase diagram of gallium nitride
NASA Astrophysics Data System (ADS)
Zhou, Ying; Wang, Shaofeng; Wang, Rui; Jiang, Na
2013-12-01
The thermodynamic properties of gallium nitride (GaN) with wurtzite (WZ) and rocksalt (RS) phases have been investigated by carrying out the first principles-calculations, in which the density-functional theory (DFT) and density-functional perturbation theory (DFPT) have been employed. The quasiharmonic approximation (QHA) has been utilized to estimate the free energies. The phonon dispersion, thermal expansion coefficients, bulk modulus, and heat capacities are presented and provided good agreement with the previous calculation and experimental data. Furthermore, the pressure-temperature (P-T) diagram of WZ-RS phase transition of GaN is predicted and the values of transition pressure range from 32.2 GPa at 0 K to about 21 GPa at 2480 K.
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.
Investigations on thermodynamic properties of the three sub-lattice spin frustrated chain
NASA Astrophysics Data System (ADS)
Wang, Jue; Zhou, Hong-Fei; Li, Qian-Chun; Dong, Hui-Ning
2015-08-01
The spin frustration related to the high-Tc superconductivity has received much attention. In this paper, based on the Jordan-Wigner transformation and Green’s function method, we study the magnetic and thermodynamic properties of the three sub-lattice spin frustrated chains. It is found that there are three branches for the spin-wave excitation spectra at zero temperature. Among them, two belong to nature excitation patterns with antiferromagnetic interaction and the third one is band gap excitation spectrum with ferromagnetic nature. The specific heat capacity of sub-lattice spin system presents complex characteristics with the change of temperature due to the intense competition between the ferromagnetic and antiferromagnetic interactions. It is also shown that the increase of the ferromagnetic action is helpful to the value of net spin.
Dalg?ç, Ali Co?kun; Pekmez, Hatice; Beliba?l?, Kadir Bülent
2012-08-01
Mint leaves were dried by three different types of dryers, namely; tray, freeze and distributed (indirect)-type solar dryer. Sorption isotherms of fresh, solar, tray and freeze dried mint were determined at temperatures of 15 °C, 25 °C and 35 °C over a range of relative humidities (10-90%). The effect of drying method on the water sorption isotherms of dried mint samples was evaluated. Experimental data were used to determine the best models for predicting the moisture sorption content of mint. Among nine sorption models tested, Peleg, GAB, Lewicki and modified Mizrahi equations gave the best fit to experimental data. The sorption data were analyzed for determination of monolayer moisture content, density of sorbed water, number of adsorbed monolayers, percent bound water, and surface area of adsorbance. The experimental data were also used to determine some thermodynamic properties of mint. PMID:23904652
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
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
Thermodynamic properties of non-conformal soft-sphere fluids with effective hard-sphere diameters.
Rodríguez-López, Tonalli; del Río, Fernando
2012-01-28
In this work we study a set of soft-sphere systems characterised by a well-defined variation of their softness. These systems represent an extension of the repulsive Lennard-Jones potential widely used in statistical mechanics of fluids. This type of soft spheres is of interest because they represent quite accurately the effective intermolecular repulsion in fluid substances and also because they exhibit interesting properties. The thermodynamics of the soft-sphere fluids is obtained via an effective hard-sphere diameter approach that leads to a compact and accurate equation of state. The virial coefficients of soft spheres are shown to follow quite simple relationships that are incorporated into the equation of state. The approach followed exhibits the rescaling of the density that produces a unique equation for all systems and temperatures. The scaling is carried through to the level of the structure of the fluids. PMID:22158949
Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation
Feng, ShiQuan; Cheng, XinLu; Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu, 610064 ; Zhao, JianLing; Zhang, Hong
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.
NASA Technical Reports Server (NTRS)
Klich, G. F.
1976-01-01
Results of calculations to determine thermodynamic, transport, and flow properties of combustion product gases are presented. The product gases are those resulting from combustion of methane-air-oxygen and methane-oxygen mixtures. The oxygen content of products resulting from the combustion of methane-air-oxygen mixtures was similiar to that of air; however, the oxygen contained in products of methane-oxygen combustion ranged from 20 percent by volume to zero for stoichiometric combustion. Calculations were made for products of reactant mixtures with fuel percentages, by mass, of 7.5 to 20. Results are presented for specific mixtures for a range of pressures varying from 0.0001 to 1,000 atm and for temperatures ranging from 200 to 3,800 K.
First-principles study of structural, elastic and thermodynamic properties of AuIn2
NASA Astrophysics Data System (ADS)
Wu, Hai Ying; Chen, Ya Hong; Deng, Chen Rong; Yin, Peng Fei; Cao, Hong
2015-12-01
The structural, elastic and thermodynamic properties of AuIn2 in the CaF2 structure under pressure have been investigated using ab initio plane wave pseudopotential method within the generalized gradient approximation. The calculated structural parameters and equation of state are in excellent agreement with the available experimental and theoretical results. The elastic constants of AuIn2 at ambient condition are calculated, and the bulk modulus obtained from these calculated elastic constants agrees well with the experimental data. The pressure dependence of the elastic constants, bulk modulus, shear modulus and Young’s modulus has also been investigated. The Debye temperature presents a slight increase with pressure. AuIn2 exhibits ductibility and low hardness characteristics, the ductibility increases while the hardness decreases with the increasing of pressure. The pressure effect on the heat capacity and thermal expansion coefficient for AuIn2 is much larger.
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).
Kozlov, Sergey S; Blennow, Andreas; Krivandin, Alexei V; Yuryev, Vladimir P
2007-04-10
A combined DSC-SAXS approach was employed to study the effects of amylose and phosphate esters on the assembly structures of amylopectin in B-type polymorphic potato tuber starches. Amylose and phosphate levels in the starches were specifically engineered by antisense suppression of the granule bound starch synthase (GBSS) and the glucan water dikinase (GWD), respectively. Joint analysis of the SAXS and DSC data for the engineered starches revealed that the sizes of amylopectin clusters, thickness of crystalline lamellae and the polymorphous structure type remained unchanged. However, differences were found in the structural organization of amylopectin clusters reflected in localization of amylose within these supramolecular structures. Additionally, data for annealed starches shows that investigated potato starches possess different types of amylopectin defects. The relationship between structure of investigated potato starches and their thermodynamic properties was recognized. PMID:17188347
Kabadi, V.N.
1992-10-01
The work on this project was initiated on September 1, 1989. The project consisted of three different tasks. 1. A thermodynamic model to predict VLE and calorimetric properties of coal liquids. 2. VLE measurements at high temperature and high pressure for coal model compounds and 3. Chromatographic characterization of coal liquids for distribution of heteroatoms. The thermodynamic model developed is an extension of the previous model developed for VLE of coal derived fluids (DOE Grant no. FG22-86PC90541). 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 model is successful in predicting binary VLE and excess enthalpy data. Further refinements of the model are suggested. An apparatus for the high pressure high temperature VLE data measurements has been built and tested. Tetralin-Quinoline is the first binary system selected for data measurements. The equipment was tested by measuring 325{degree}C isotherm for this system and comparing it with literature data. Additional isotherms at 350{degree}C and 370{degree}C have been measured. The framework for a characterization procedure for coal derived liquids has been developed. A coal liquid is defined by a true molecular weight distribution and distribution of heteroatoms as a function of molecular weights. Size exclusions liquid chromatography, elemental analysis and FTIR spectroscopy methods are used to obtain the molecular weight and hetroatom distributions. Further work in this area should include refinements of the characterization procedure, high temperature high pressure VLE data measurements for selective model compound binary systems, and improvement of the thermodynamic model using the new measured data and consistent with the developments in the characterization procedure.
NASA Astrophysics Data System (ADS)
Fournier, RenÃ©; Mohareb, Amir
2016-01-01
We devised a global optimization (GO) strategy for optimizing molecular properties with respect to both geometry and chemical composition. A relative index of thermodynamic stability (RITS) is introduced to allow meaningful energy comparisons between different chemical species. We use the RITS by itself, or in combination with another calculated property, to create an objective function F to be minimized. Including the RITS in the definition of F ensures that the solutions have some degree of thermodynamic stability. We illustrate how the GO strategy works with three test applications, with F calculated in the framework of Kohn-Sham Density Functional Theory (KS-DFT) with the Perdew-Burke-Ernzerhof exchange-correlation. First, we searched the composition and configuration space of CmHnNpOq (m = 0-4, n = 0-10, p = 0-2, q = 0-2, and 2 â‰¤ m + n + p + q â‰¤ 12) for stable molecules. The GO discovered familiar molecules like N2, CO2, acetic acid, acetonitrile, ethane, and many others, after a small number (5000) of KS-DFT energy evaluations. Second, we carried out a GO of the geometry of Cu m Snn + (m = 1, 2 and n = 9-12). A single GO run produced the same low-energy structures found in an earlier study where each Cu m S nn + species had been optimized separately. Finally, we searched bimetallic clusters AmBn (3 â‰¤ m + n â‰¤ 6, A,B= Li, Na, Al, Cu, Ag, In, Sn, Pb) for species and configurations having a low RITS and large highest occupied Molecular Orbital (MO) to lowest unoccupied MO energy gap (Eg). We found seven bimetallic clusters with Eg > 1.5 eV.
On the ease of predicting the thermodynamic properties of beta-cyclodextrin inclusion complexes
Steffen, Andreas; Apostolakis, Joannis
2007-01-01
Background In this study we investigated the predictability of three thermodynamic quantities related to complex formation. As a model system we chose the host-guest complexes of ?-cyclodextrin (?-CD) with different guest molecules. A training dataset comprised of 176 ?-CD guest molecules with experimentally determined thermodynamic quantities was taken from the literature. We compared the performance of three different statistical regression methods – principal component regression (PCR), partial least squares regression (PLSR), and support vector machine regression combined with forward feature selection (SVMR/FSS) – with respect to their ability to generate predictive quantitative structure property relationship (QSPR) models for ?G°, ?H° and ?S° on the basis of computed molecular descriptors. Results We found that SVMR/FFS marginally outperforms PLSR and PCR in the prediction of ?G°, with PLSR performing slightly better than PCR. PLSR and PCR proved to be more stable in a nested cross-validation protocol. Whereas ?G° can be predicted in good agreement with experimental values, none of the methods led to comparably good predictive models for ?H°. In using the methods outlined in this study, we found that ?S° appears almost unpredictable. In order to understand the differences in the ease of predicting the quantities, we performed a detailed analysis. As a result we can show that free energies are less sensitive (than enthalpy or entropy) to the small structural variations of guest molecules. This property, as well as the lower sensitivity of ?G° to experimental conditions, are possible explanations for its greater predictability. Conclusion This study shows that the ease of predicting ?G° cannot be explained by the predictability of either ?H° or ?S°. Our analysis suggests that the poor predictability of T?S° and, to a lesser extent, ?H° has to do with a stronger dependence of these quantities on the structural details of the complex and only to a lesser extent on experimental error. PMID:18005419
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.
Fournier, René; Mohareb, Amir
2016-01-14
We devised a global optimization (GO) strategy for optimizing molecular properties with respect to both geometry and chemical composition. A relative index of thermodynamic stability (RITS) is introduced to allow meaningful energy comparisons between different chemical species. We use the RITS by itself, or in combination with another calculated property, to create an objective function F to be minimized. Including the RITS in the definition of F ensures that the solutions have some degree of thermodynamic stability. We illustrate how the GO strategy works with three test applications, with F calculated in the framework of Kohn-Sham Density Functional Theory (KS-DFT) with the Perdew-Burke-Ernzerhof exchange-correlation. First, we searched the composition and configuration space of CmHnNpOq (m = 0-4, n = 0-10, p = 0-2, q = 0-2, and 2 ? m + n + p + q ? 12) for stable molecules. The GO discovered familiar molecules like N2, CO2, acetic acid, acetonitrile, ethane, and many others, after a small number (5000) of KS-DFT energy evaluations. Second, we carried out a GO of the geometry of CumSnn (+) (m = 1, 2 and n = 9-12). A single GO run produced the same low-energy structures found in an earlier study where each CumSnn (+) species had been optimized separately. Finally, we searched bimetallic clusters AmBn (3 ? m + n ? 6, A,B= Li, Na, Al, Cu, Ag, In, Sn, Pb) for species and configurations having a low RITS and large highest occupied Molecular Orbital (MO) to lowest unoccupied MO energy gap (Eg). We found seven bimetallic clusters with Eg > 1.5 eV. PMID:26772561
NASA Astrophysics Data System (ADS)
Song, Mei-Ying; Hou, Yi-Fang; Wen, Long-Mei; Wang, Shu-Ping; Yang, Shu-Tao; Zhang, Jian-Jun; Geng, Li-Na; Shi, Shi-Kao
2016-03-01
Four new nitronyl nitroxide radical-Ln(III) complexes, Ln(hfac)3(NITPhSCF3)2 (Ln(III)Â =Â Sm(1), Gd(2), Tb(3), Dy(4); NITPhSCF3Â =Â 2-(4-trifluoromethylthiophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl- 3-oxide; hfacÂ =Â hexafluoroacetylacetonate), have been synthesized and characterized. They are isostructural, which show mononuclear tri-spin structures. The central Ln(III) ion is eight-coordinated by three hfac anions and two NITPhSCF3 molecules. Direct-current magnetic study shows that there exist ferromagnetic interactions between Gd(III) ion and radicals (NITPhSCF3) with JGd-RadÂ =Â 1.61Â cm-1, and antiferromagnetic interactions between radicals with JRad-RadÂ =Â -2.83Â cm-1 in complex 2. The magnetic analysis with the rough approximate model show that a ferromagnetic coupling exists between Tb(III) and radical in 3, while a antiferromagnetic coupling between Dy(III) and radical in 4. The thermodynamics properties of four complexes were studied with differential scanning calorimetry (DSC), such as heat capacity, thermodynamic functions (HT-H298.15K), (ST-S298.15K), and (GT-G298.15K).
Ergodic properties of a generic nonintegrable quantum many-body system in the thermodynamic limit.
Prosen, T
1999-10-01
We study a generic but simple nonintegrable quantum many-body system of locally interacting particles, namely, a kicked-parameter (t,V) model of spinless fermions on a one-dimensional lattice (equivalent to a kicked Heisenberg XX-Z chain of 1/2 spins). The statistical properties of the dynamics (quantum ergodicity and quantum mixing) and the nature of quantum transport in the thermodynamic limit are considered as the kick parameters (which control the degree of nonintegrability) are varied. We find and demonstrate ballistic transport and nonergodic, nonmixing dynamics (implying infinite conductivity at all temperatures) in the integrable regime of zero or very small kick parameters, and more generally and importantly, also in the nonintegrable regime of intermediate values of kicked parameters, whereas only for sufficiently large kick parameters do we recover quantum ergodicity and mixing implying normal (diffusive) transport. We propose an order parameter (charge stiffness D) which controls the phase transition from nonmixing and nonergodic dynamics (ordered phase, D>0) to mixing and ergodic dynamics (disordered phase, D=0) in the thermodynamic limit. Furthermore, we find exponential decay of time correlation functions in the regime of mixing dynamics. The results are obtained consistently within three different numerical and analytical approaches: (i) time evolution of a finite system and direct computation of time correlation functions, (ii) full diagonalization of finite systems and statistical analysis of stationary data, and (iii) algebraic construction of quantum invariants of motion of an infinite system, in particular the time-averaged observables. PMID:11970231
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
NASA Astrophysics Data System (ADS)
Paganini, Iván E.; Pastorino, Claudio; Urrutia, Ignacio
2015-06-01
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.
NASA Technical Reports Server (NTRS)
Fessler, T. E.
1977-01-01
A computer program subroutine, FLUID, was developed to calculate thermodynamic and transport properties of pure fluid substances. It provides for determining the thermodynamic state from assigned values for temperature-density, pressure-density, temperature-pressure, pressure-entropy, or pressure-enthalpy. Liquid or two-phase (liquid-gas) conditions are considered as well as the gas phase. A van der Waals model is used to obtain approximate state values; these values are then corrected for real gas effects by model-correction factors obtained from tables based on experimental data. Saturation conditions, specific heat, entropy, and enthalpy data are included in the tables for each gas. Since these tables are external to the FLUID subroutine itself, FLUID can implement any gas for which a set of tables has been generated. (A setup phase is used to establish pointers dynamically to the tables for a specific gas.) Data-table preparation is described. FLUID is available in both SFTRAN and FORTRAN
Mittal, Shruti; Singh, Laishram Rajendrakumar
2013-01-01
Understanding of protein structure and stability gained to date has been acquired through investigations made under dilute conditions where total macromolecular concentration never surpasses 10 g lâˆ’1. However, biological macromolecules are known to evolve and function under crowded intracellular environments that comprises of proteins, nucleic acids, ribosomes and carbohydrates etc. Crowded environment is known to result in altered biological properties including thermodynamic, structural and functional aspect of macromolecules as compared to the macromolecules present in our commonly used experimental dilute buffers (for example, Tris HCl or phosphate buffer). In this study, we have investigated the thermodynamic and structural consequences of synthetic crowding agent (Ficoll 70) on three different proteins (Ribonuclease-A, lysozyme and holo Î±-lactalbumin) at different pH values. We report here that the effect of crowding is protein dependent in terms of protein thermal stability and structure. We also observed that the structural characteristics of the denatured state determines if crowding will have an effect or not on the protein stability. PMID:24265729
Structural, thermodynamic, and electronic properties of plutonium oxides from first principles
NASA Astrophysics Data System (ADS)
Jomard, Gérald; Amadon, Bernard; Bottin, François; Torrent, Marc
2008-08-01
We report ab initio calculations of the structural, electronic, optical, and thermodynamic properties of plutonium oxides ( PuO2 and ?-Pu2O3 ). In order to describe the basic features of the electronic structure, a method suited to take into account strong local correlations has to be used. We apply the local density approximation/generalized gradient approximation ( LDA/GGA)+U approximations to these compounds and compare them with the calculations of Sun [J. Chem. Phys. 128, 084705 (2008)]. Whereas a good agreement is obtained for PuO2 , our LDA and LDA+U results differ strongly from this study in the case of Pu2O3 . In particular, the effect of the Hubbard parameter U on the volume is qualitatively and quantitatively different. Moreover, thermodynamic quantities differ. We thus focus our study on Pu2O3 and emphasize the importance of a careful and systematic search of the ground state in LDA+U : In particular, different hints for the occupation matrices corresponding to the electronic configurations allowed by symmetry have to be tried. This procedure is absolutely necessary to find the absolute minimum of the energy. Reliable and accurate quantitative results are given for Pu2O3 . We thus recover a more physical behavior coherent with calculations on other systems, such as cerium oxides.
The thermodynamic properties of hydrated Î³-Al{sub 2}O{sub 3} nanoparticles
Spencer, Elinor C.; Ross, Nancy L.; Huang, Baiyu; Woodfield, Brian F.; Parker, Stewart F.; Kolesnikov, Alexander I.
2013-12-28
In this paper we report a combined calorimetric and inelastic neutron scattering (INS) study of hydrated Î³-Al{sub 2}O{sub 3} (Î³-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{sub p}) data presented herein provide further critical insights into the much-debated chemical composition of Î³-alumina nanoparticles. Furthermore, the isochoric heat capacity (C{sub 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 iceâ€‘Ih due to the dominating influence of strong surface-water interactions. This study also encompassed the analysis of four Î³-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 Î³-alumina nanoparticles.
NASA Astrophysics Data System (ADS)
Ran, Shi-Ju; Xi, Bin; Liu, Tao; Su, Gang
2013-08-01
Based on the tensor network state representation, we develop a nonlinear dynamic theory, coined network contractor dynamics (NCD), to explore the thermodynamic properties of two-dimensional quantum lattice models. By invoking the rank-1 decomposition in the multilinear algebra, the NCD scheme makes the contraction of the tensor network of the partition function be realized through a contraction of a local tensor cluster with vectors on its boundary. An imaginary-time-sweep algorithm for implementation of the NCD method is proposed for practical numerical simulations. We benchmark the NCD scheme on the square Ising model, which shows great accuracy. Also, the results on the spin-1/2 Heisenberg antiferromagnet on a honeycomb lattice are disclosed to be in good agreement with the quantum Monte Carlo calculations. The quasientanglement entropy S, Lyapunov exponent ILya, and loop character Iloop are introduced within the dynamic scheme, which are found to display “nonlocality” near the critical point, and can be applied to determine the thermodynamic phase transitions of both classical and quantum systems.
Thermodynamic properties of 9-methylcarbazole and 1,2,3,4-tetrahydro-9-methylcarbazole
Steele, W.V.; Knipmeyer, S.E.; Nguyen, A.; Chirico, R.D.
1991-04-01
Removal of carbazole and its derivatives from heavy petroleum has proved to be particularly difficult using present technology. Studies have shown carbazole and its alkyl-homologs are the dominant nitrogen-containing components in clarified slurry oils, thereby indicating their low reactivity and/or formation during cat-cracking processes. The results reported here will point the way to the development of new methods of nitrogen removal from carbazole and its derivatives. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for 9-methylcarbazole and 1,2,3,4-tetrahydro-9-methylcarbazole. For studies on 1,2,3,4-tetrahydro-9-methylcarbazole experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, vibrating-tube densitometry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). Adiabatic heat-capacity and combustion calorimetric studies were reported previously for 9-methylcarbazole. Vapor pressures by comparative ebulliometry and inclined-piston gauge manometry, and heat-capacities for the liquid phase by d.s.c. are reported here. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 298.15 K and near 700 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathway of the initial hydrogenation step in the carbazole/H{sub 2} hydrodenitrogenation network. 52 refs., 9 figs., 15 tabs.
Thermodynamic properties of an alternating-spin (1/2,1) two-leg ladder
NASA Astrophysics Data System (ADS)
Chen, X. Y.; Jiang, Q.; Shen, W. Z.
2004-01-01
With the aid of the Schwinger-boson mean-field method, we study the low-lying excitations and thermodynamic properties of a ferrimagnetic Heisenberg two-leg ladder (i.e., a ferrimagnetic double-chain with an antiferromagnetic interaction). The interaction between the two chains plays an important role in producing a low-lying excitation energy gap, affecting the low-lying excited spectrum, and increasing the disorder of the ferrimagnetic double-chain. The excitation spectrum, energy gap, and spin reduction in the ground state are calculated. Thermodynamic quantities such as the short-range spin correlation and short-range order are also obtained at low temperatures. In this gapful system, we observed the exponential behaviors in both the specific heat (C_V) and the product of magnetic susceptibility and temperature (Ï‡ T) at low temperatures. The exponential behavior of the Ï‡ T versus temperature agrees qualitatively with the experimental results in NiCu(pba)(D_2O)_3\\cdot D_2O at low temperatures.
Thermodynamic and Transport Properties of Superconducting Mg{sup 10}B{sub 2}
Finnemore, D. K.; Ostenson, J. E.; Bud'ko, S. L.; Lapertot, G.; Canfield, P. C.
2001-03-12
Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB{sub 2} superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, H{sub c2} , with magnetization data giving dH{sub c2}/dT=0.44 T/ K at the transition temperature of T{sub c}=40.2 K . Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1T. The value of dH{sub c}/dT at T{sub c} is estimated to be about 12 mT/K , a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter {kappa}{approx}26 . Estimates of the critical supercurrent density, J{sub c} , using hysteresis loops and the Bean model, give critical current densities on the order of 10{sup 5} A/cm {sup 2} . Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb{sub 3}Sn .
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.
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.
Structural, thermodynamic and optical properties of MgF{sub 2} studied from first-principles theory
Ramesh Babu, K.; Bheema Lingam, Ch.; Auluck, S.; Tewari, Surya P.; Vaitheeswaran, G.
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.
NASA Astrophysics Data System (ADS)
Antoshechkina, P. M.; Wolf, A. S.; Hamecher, E. A.; Asimow, P. D.; Ghiorso, M. S.
2013-12-01
Community databases such as EarthChem, LEPR, and AMCSD both increase demand for quantitative petrological tools, including thermodynamic models like the MELTS family of algorithms, and are invaluable in development of such tools. The need to extend existing solid solution models to include minor components such as Cr and Na has been evident for years but as the number of components increases it becomes impossible to completely separate derivation of end-member thermodynamic data from calibration of solution properties. In Hamecher et al. (2012; 2013) we developed a calibration scheme that directly interfaces with a MySQL database based on LEPR, with volume data from AMCSD and elsewhere. Here we combine that scheme with a Bayesian approach, where independent constraints on parameter values (e.g. existence of miscibility gaps) are combined with uncertainty propagation to give a more reliable best-fit along with associated model uncertainties. We illustrate the scheme with a new model of molar volume for (Ca,Fe,Mg,Mn,Na)3(Al,Cr,Fe3+,Fe2+,Mg,Mn,Si,Ti)2Si3O12 cubic garnets. For a garnet in this chemical system, the model molar volume is obtained by adding excess volume terms to a linear combination of nine independent end-member volumes. The model calibration is broken into three main stages: (1) estimation of individual end-member thermodynamic properties; (2) calibration of standard state volumes for all available independent and dependent end members; (3) fitting of binary and mixed composition data. For each calibration step, the goodness-of-fit includes weighted residuals as well as Ï‡2-like penalty terms representing the (not necessarily Gaussian) prior constraints on parameter values. Using the Bayesian approach, uncertainties are correctly propagated forward to subsequent steps, allowing determination of final parameter values and correlated uncertainties that account for the entire calibration process. For the aluminosilicate garnets, optimal values of the bulk modulus and its pressure derivative are obtained by fitting published compression data using the Vinet equation of state, with the Mie-GrÃ¼neisen-Debye thermal pressure formalism to model thermal expansion. End-member thermal parameters are obtained by fitting volume data while ensuring that the heat capacity is consistent with the thermodynamic database of Berman and co-workers. For other end members, data for related compositions are used where such data exist; otherwise ultrasonic data or density functional theory results are taken or, for thermal parameters, systematics in cation radii are used. In stages (2) and (3) the remaining data at ambient conditions are fit. Using this step-wise calibration scheme, most parameters are modified little by subsequent calibration steps but some, such as the standard state volume of the Ti-bearing end member, can vary within calculated uncertainties. The final model satisfies desired criteria and fits almost all the data (more than 1000 points); only excess parameters that are justified by the data are activated. The scheme can be easily extended to calibration of end-member and solution properties from experimental phase equilibria. As a first step we obtain the internally consistent standard state entropy and enthalpy of formation for knorringite and discuss differences between our results and those of Klemme and co-workers.
Structural and thermodynamic properties of Fe{sub 1.12}Te with multiple phase transitions
Cherian, Dona Elizabeth, Suja; Rößler, S.; Koz, C.; Schwarz, U.; Wirth, S.; Tsirlin, A. A.
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}
NASA Astrophysics Data System (ADS)
Kocak, B.; Ciftci, Y. O.; Colakoglu, K.; Deligoz, E.
2010-10-01
First principles calculations are performed to investigate the structural, electronic, elastic, and thermodynamic properties of the less known PrN compound for various space groups: NaCl(Fm3m(2 2 5)), CsCl(Pm3m (2 2 1)), ZB(F43m(2 1 6)), Wc(P6m2(1 8 7)), and CuAu (P4/mmm (1 2 3)). Our calculation indicates that the NaCl type structure is energetically more stable than the other phases. The calculated lattice parameters are consisted with available theoretical and experimental results. Our band structure calculations show that PrN possessess a semi-metallic character for both with and without spin polarized (SP) cases. The calculated elastic constants satisfy the mechanical stability conditions at all considered pressures and the present values are significantly higher than those of the previous results. The related mechanical properties such as Zener anisotropy factor ( A), Poisson’s ratio ( ?), Young’s modulus ( E), and shear modulus ( C) are also computed for NaCl structure. The temperature/pressure-dependent behaviours of bulk modulus, Debye temperature, heat capacity, thermal expansion coeffient, and V/ V0 ratio estimated within the quasi-harmonic Debye model.
Donohue, M.D.
1988-11-01
The progress of our efforts toward understanding molecular behavior and its effect on thermodynamic properties is presented. This included work in the following areas: The repulsive and attractive terms in various equations for chain molecules have been compared with computer simulation results. We found that PHCT fit the data more closely than the other equations. For non-polar, polar and hydrogen bonding pure substances, APACT molecular parameters were correlated with molecular size. The density dependence in the SPHCT has been modified in order to improve the accuracy of pure-component property calculations. Our knowledge of the partitioning of intermolecular interactions has been used to study how the solubility parameter in Regular Solution Theory can be related to fundamental molecular constants. We have made substantial progress toward understanding how our theories can be applied to polymer solutions. Computer simulations of chain molecules have been carried out in order to test our equations and to determine radial distribution functions of various groups used in a group-group interaction approach. Finally, our theoretical efforts have been supplemented by appropriate experimental measurements. 10 refs.
NASA Astrophysics Data System (ADS)
Yanilkin, Alexey; Migdal, Kirill; Pokatashkin, Pavel; Sergeev, Oleg
2015-06-01
The application of molecular dynamics allows us to take into account the influence of thermal properties on thermodynamic properties and phase transitions. In this work different uranium phases are investigated at finite temperatures by means quantum and classical molecular dynamics. In order to verify simulations the lattice constants, elastic modulus, isotherms, Gruniesen coefficient and heat expansion are calculated for ?, ? and liquid phases. The results are in good agreement with experimental data. The stability of high temperature ? phase is discussed. The diffusion coefficient is calculated for liquid phase at different densities and pressure. The boundaries of phase stability are estimated based on QMD results. Furthermore hugoniot calculated is in a good agreement with other calculations and experimental data up to 2TPa. In order to investigate phase transitions EAM interatomic potentials are derived by force-matching method. Different parameterizations are used for different part of phase diagram to improve the reproduction of QMD data. The coexistence and transition rates of two phases are investigated based on Z- and two phase methods.
Influence of volume magnetostriction on the thermodynamic properties of Ni-Mn-Ga shape memory alloys
NASA Astrophysics Data System (ADS)
Kosogor, Anna; L'vov, Victor A.; Cesari, Eduard
2015-10-01
In the present article, the thermodynamic properties of Ni-Mn-Ga ferromagnetic shape memory alloys exhibiting the martensitic transformations (MTs) above and below Curie temperature are compared. It is shown that when MT goes below Curie temperature, the elastic and thermal properties of alloy noticeably depend on magnetization value due to spontaneous volume magnetostriction. However, the separation of magnetic parts from the basic characteristics of MT is a difficult task, because the volume magnetostriction does not qualitatively change the transformational behaviour of alloy. This problem is solved for several Ni-Mn-Ga alloys by means of the quantitative theoretical analysis of experimental data obtained in the course of stress-strain tests. For each alloy, the entropy change and the transformation heat evolved in the course of MT are evaluated, first, from the results of stress-strain tests and, second, from differential scanning calorimetry data. For all alloys, a quantitative agreement between the values obtained in two different ways is observed. It is shown that the magnetic part of transformation heat exceeds the non-magnetic one for the Ni-Mn-Ga alloys undergoing MTs in ferromagnetic state, while the elevated values of transformation heat measured for the alloys undergoing MTs in paramagnetic state are caused by large MT strains.
NASA Astrophysics Data System (ADS)
Mysen, B.; Lee, S.; Cody, G. D.; Fei, Y.
2006-12-01
Recent developments and advances in solid state NMR and synchrotron x-ray techniques, together with theoretical analyses using quantum-chemical calculations and statistical mechanical modeling, make it possible to quantify the detailed distribution of cations and anions in model oxide glasses and melts with varying pressure, temperature, and composition (e.g. Lee SK. Geochim. Cosmochim. Acta 2005, 69, p3695; J. Phys. Chem. B. 2006, 110, p16408 Lee SK et al. Nature Materials 2005, 4, p851). These results allow us to estimate quantitatively the configurational thermodynamic properties of oxide glasses and their precursor liquids. We present several examples that establish a link among microscopic spectroscopic and scattering measurements, quantification of disorder, and the configurational thermodynamic properties. These examples include enthalpy of mixing, activity coefficient of silica in archetypal and complex silicate, germanate glasses and melts at ambient and high pressure. Most glasses and melts show a tendency toward chemical ordering among framework cations (Si and Al) at ambient pressure. This information provides a basis for quantitative understanding of the degree of Al-avoidance and phase separation in more complex multi-component melts and glasses. This chemical ordering, a manifestation of energetics in the melts and glasses, also contributes to the total negative deviation of activity of oxides from ideal solution in silicate melts (reduced activity). While no definite evidence of clustering among non-framework cations was found, these cations tend to form dissimilar pairs upon mixing with other types of network modifying cations. The chemical order appears maintained at high pressure where there exists higher- coordinated framework units (^{[5,6]}Si and ^{[5,6]}Al). It appears that the distribution of these units is not random, but shows significant chemical order, favoring mixing between different types of framework units (e.g. ^{[4]}Si -O-^{[5,6]}Si). Topologically, the peak width of each oxygen site, as seen in NMR spectra, increases with increasing pressure. This implies that bond angle and length, as well as the distortion of framework polyhedra, increase with increasing pressure, thus increasing topological entropy. We then calculate key macroscopic properties, including the activity coefficient of silica and configurational enthalpy from the quantitative estimates of the extent of disorder from solid-state NMR. These results are remarkably similar to existing experimental solution calorimetric data for aluminosilicates and borosilicate glasses (Navrotsky et al. Geochim. Cosmochim. Acta 1982, 46, p2036; Hervig et al. 1985 J. Am. Ceram. Soc.68, p314).
Konings, Rudy J. M. Beneš, Ondrej; Kovács, Attila; Manara, Dario; Sedmidubský, David; Gorokhov, Lev; Iorish, Vladimir S.; Yungman, Vladimir; Shenyavskaya, E.; Osina, E.
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.
NASA Technical Reports Server (NTRS)
Myles, K. M.
1967-01-01
Vapor pressure data obtained by the torsion-effusion method provides the thermodynamic properties of several transition-metal alloy systems. The vapor pressure of silver over solid silver and over palladium-silver alloys was measured and the results were more accurate than those found previously by other techniques.
Equation of state and thermodynamic properties of 1,1,1,2-tetrafluoroethane (refrigerant R134a)
NASA Astrophysics Data System (ADS)
Vas'kov, E. T.
1995-01-01
An equation of state and tables of thermodynamic properties of R134a in the saturation state and in the one-phase region are obtained in the temperature interval 320 500 K at pressures ranging from 0.01 to 7.5 MPa.
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 Â± 9.69, -3072.27 Â± 4.76, and -6138.95 Â± 12.24 kJ mol-1 for CaUP, HUP, and UP, respectively), and calorimetry data to calculate standard state enthalpies of formation of -3223.22 Â± 4.00 and -7001.01 Â± 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 Â± 10.48 and -2893.12 Â± 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.
NASA Astrophysics Data System (ADS)
Hallett, Paul; Ogden, Mike; Karim, Kamal; Schmidt, Sonja; Yoshida, Shuichiro
2014-05-01
Soil aggregates are a figment of your energy input and initial boundary conditions, so the basic thermodynamics that drive soil structure formation are needed to understand soil structure dynamics. Using approaches from engineering and materials science, it is possible quantify basic thermodynamic properties, but at present tests are generally limited to highly simplified, often remoulded, soil structures. Although this presents limitations, the understanding of underlying processes driving soil structure dynamics is poor, which could be argued is due to the enormity of the challenge of such an incredibly complex system. Other areas of soil science, particularly soil water physics, relied on simplified structures to develop theories that can now be applied to more complex pore structures. We argue that a similar approach needs to gain prominence in the study of soil aggregates. An overview will be provided of approaches adapted from other disciplines to quantify particle bonding, fracture resistance, rheology and capillary cohesion of soil that drive its aggregation and structure dynamics. All of the tests are limited as they require simplified soil structures, ranging from repacked soils to flat surfaces coated with mineral particles. A brief summary of the different approaches will demonstrate the benefits of collecting basic physical data relevant to soil structure dynamics, including examples where they are vital components of models. The soil treatments we have tested with these engineering and materials science approaches include field soils from a range of management practices with differing clay and organic matters contents, amendment and incubation of soils with a range of microorganisms and substrates in the laboratory, model clay-sand mixes and planar mineral surfaces with different topologies. In addition to advocating the wider adoption of these approaches, we will discuss limitations and hope to stimulate discussion on how approaches could be improved and made more useful for studying soil structure dynamics in the future.
Free-standing silicene obtained by cooling from 2D liquid Si: structure and thermodynamic properties
NASA Astrophysics Data System (ADS)
Van Hoang, Vo; Thi Cam Mi, Huynh
2014-12-01
The structure and various thermodynamic properties of free-standing silicene have been studied by computer simulation. Models are obtained by cooling from buckling two-dimensional (2D) liquid Si via molecular dynamics (MD) simulation with Stillinger-Weber interatomic potential. The temperature dependence of total energy, heat capacity, mean ring size and mean coordination number shows that silicenization of 2D liquid Si exhibits a first-order-like behavior. The evolution of radial distribution function upon cooling from the melt also shows that solidification occurs in the system. The final configuration of silicene is analyzed via coordination, bond-angle, interatomic distance and ring distributions or distribution of buckling in the system. 2D visualization of atomic configurations clearly demonstrated that silicene obtained ‘naturally’ by cooling from the melt exhibits various structural previously unreported behaviors. We find the formation of polycrystalline silicene with clear grain boundaries containing various defects including various vacancies, Stone-Wales defects or skew rings and multimembered rings unlike those proposed in the literature. However, atoms in the obtained silicene are mostly involved in six-fold rings, forming a buckling honeycomb structure like that found in practice. We find that buckling is not unique for all atoms in the models although the majority of atoms reveal buckling of the most stable low-buckling silicene found in the literature. The buckling distribution is broad and symmetric. Our comprehensive MD simulation of a relatively large silicene model containing 104 atoms and obtained ‘naturally’ by cooling from the melt provides original insights into the structure and thermodynamics of this important 2D material.
Experimental Study of the Thermodynamic Properties of Diethyl Ether (DEE) at Saturation
NASA Astrophysics Data System (ADS)
Polikhronidi, N. G.; Abdulagatov, I. M.; Batyrova, R. G.; Stepanov, G. V.; Ustuzhanin, E. E.; Wu, J. T.
2011-03-01
The isochoric heat capacities {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')}, saturation densities ({? _S^' and ({?_S^'')}), vapor pressures ( P S), thermal-pressure coefficients {?_V=left({partial P/partial T}right)_V}, and first temperature derivatives of the vapor pressure ? S = (d P S/d T) of diethyl ether (DEE) on the liquid-gas coexistence curve near the critical point have been measured with a high-temperature and high-pressure nearly constant-volume adiabatic piezo-calorimeter. The measurements of {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')} were made in the liquid and vapor one- and two-phase regions along the coexistence curve. The calorimeter was additionally supplied with a calibrated extensometer to accurately and simultaneously measure the PVT, C V VT, and thermal-pressure coefficient, ? V , along the saturation curve. The measurements were carried out in the temperature range from 416 K to 466.845 K (the critical temperature) for 17 liquid and vapor densities from 212.6 kg · m-3 to 534.6 kg · m-3. The quasi-static thermo- (reading of PRT, T - ? plot) and baro-gram (readings of the tensotransducer, P - ? plot) techniques were used to accurately measure the phase-transition parameters ( P S , ? S , T S) and ? V . The total experimental uncertainty of density ( ? S), pressure ( P S), temperature ( T S), isochoric heat capacities {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')}, and thermal-pressure coefficient, ? V , were estimated to be 0.02 % to 0.05 %, 0.05 %, 15 mK, 2 % to 3 %, and 0.12 % to 1.5 %, respectively. The measured values of saturated caloric {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')} and saturated thermal ( P S, ? S, T S) properties were used to calculate other derived thermodynamic properties C P , C S, W, K T , P int, ? H vap, and {left({partial V/partial T}right)_P^' of DEE near the critical point. The second temperature derivatives of the vapor pressure, (d2 P S/d T 2), and chemical potential, (d2 ?/d T 2), were also calculated directly from the measured one- and two-phase liquid and vapor isochoric heat capacities {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')} near the critical point. The derived values of (d2 P S/d T 2) from calorimetric measurements were compared with values calculated from vapor-pressure equations. The measured and derived thermodynamic properties of DEE near the critical point were interpreted in terms of the "complete scaling" theory of critical phenomena. In particular, the effect of a Yang-Yang anomaly of strength R ? on the coexistence-curve diameter behavior near the critical point was studied. Extended scaling-type equations for the measured properties P S ( T), ? S ( T), and {({C_{V1}^' ,{C_{V1}^'',{C_{V2}^',{C_{V2}^'')} as a function of temperature were developed.
Elstnerová, Pavlína; Friák, Martin; Fabritius, Helge Otto; Lymperakis, Liverios; Hickel, Tilmann; Petrov, Michal; Nikolov, Svetoslav; Raabe, Dierk; Ziegler, Andreas; Hild, Sabine; Neugebauer, Jörg
2010-12-01
Arthropoda, which represent nearly 80% of all known animal species, are protected by an exoskeleton formed by their cuticle. The cuticle represents a hierarchically structured multifunctional biocomposite based on chitin and proteins. Some groups, such as Crustacea, reinforce the load-bearing parts of their cuticle with calcite. As the calcite sometimes contains Mg it was speculated that Mg may have a stiffening impact on the mechanical properties of the cuticle (Becker et al., Dalton Trans. (2005) 1814). Motivated by these facts, we present a theoretical parameter-free quantum-mechanical study of the phase stability and structural and elastic properties of Mg-substituted calcite crystals. The Mg-substitutions were chosen as examples of states that occur in complex chemical environments typical for biological systems in which calcite crystals contain impurities, the role of which is still the topic of debate. Density functional theory calculations of bulk (Ca,Mg)CO? were performed employing 30-atom supercells within the generalized gradient approximation as implemented in the Vienna Ab-initio Simulation Package. Based on the calculated thermodynamic results, low concentrations of Mg atoms are predicted to be stable in calcite crystals in agreement with experimental findings. Examining the structural characteristics, Mg additions nearly linearly reduce the volume of substituted crystals. The predicted elastic bulk modulus results reveal that the Mg substitution nearly linearly stiffens the calcite crystals. Due to the quite large size-mismatch of Mg and Ca atoms, Mg substitution results in local distortions such as off-planar tilting of the CO?²? group. PMID:20650336
NASA Astrophysics Data System (ADS)
Yuan, Jiaonan; Ji, Guangfu; Chen, Xiangrong; Wei, Dongqing; Zhao, Feng; Wu, Qiang
2016-01-01
In present letter, based on density functional theory plus dispersion (DFT-D) and a self-consistent charge density-functional tight-binding (SCC-DFTB) method, the structural and electronic properties are reported, and the phase transition are investigated by analyzing its thermodynamics properties and IR spectrum of RDX. The anisotropy of ?- and ?-RDX were discussed at 0-10 GPa. By fitting the third-order Birch-Murnaghan equation of states, the bulk modulus and its pressure derivative of RDX were determined. The ?-RDX phase is found stable at ambient condition, however, under pressures, both the values of lattice constants a, b, c and the ?Evdw at around 4 GPa show abrupt changes which indicate a structural transition occurred. By analyzing the linear compressibility of a, b, c axes at 0-8 GPa, one clearly see that the molecules in ?-RDX phase underwent rotations and translational motion to their position in the ?-RDX phase at about 4 GPa, which validates the ?-? phase transition. The IR spectra of ?-form and ?-form RDX was calculated by analyzing the trajectory of molecules motion, which also show the phase transition from the spectra changes. Employing the quasi-harmonic Debye model, the enthalpy and specific heat were investigated at various pressures of both phases. The condition of equal enthalpies in both phases also indicates the phase transition of ?-form to ?-form at around 4 GPa. The variation of specific heat with temperature approaches to the classical Dulong-Petit's law at high temperature, while at low-temperature it obeys the Debye's T3 law.
Ab initio calculation of thermodynamic, transport, and optical properties of CH{sub 2} plastics
Knyazev, D. V.; Levashov, P. R.
2015-05-15
This work covers an ab initio calculation of thermodynamic, transport, and optical properties of plastics of the effective composition CH{sub 2} at density 0.954?g/cm{sup 3} 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 ?{sub 1{sub D{sub C}}}(T) has a step-like shape: ?{sub 1{sub D{sub C}}}(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 ?{sub 1{sub D{sub C}}}(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 ?{sub 1}(?) at 5 kK has the distinct non-Drude shape with the peak at ????10?eV. This behavior of ?{sub 1}(?) was explained by the dip at the electron DOS.
NASA Astrophysics Data System (ADS)
Xu, Wen-Sheng; Freed, Karl F.
2015-07-01
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.
NASA Astrophysics Data System (ADS)
Dogan, Ali; Arslan, HÃ¼seyin
2015-08-01
In the present study, the enthalpies of mixing associated with the liquid phase in Ni-Cr-Co-Al-Ti-Cu, Au-In-Sn-Zn, and In-Pd-Sn systems at a temperature of 2000 K (1727 Â°C) through the six components, ternary, and quaternary geometric models are calculated. The values calculated from different geometric models are compared with those obtained in the experiments. In this respect, the results of some thermodynamic prediction methods were applied to the six-component Ni-Cr-Co-Al-Ti-Cu system, the quaternary alloy Au-In0.45-Sn0.45-Zn0.1, and the subsystem ternary alloy In-Pd-Sn in the present study in order to analytically determine the integral properties associated with the six-component alloy systems in the liquid phase. The Chou's general solution model and the traditional models of Toop, Colinet, Muggianu, and Kohler were included in the calculation for comparison and discussion. A comparison among the results of the models and experiments carried out for ternary and quaternary systems displays good mutual agreement.
Phonon spectrum, thermodynamic properties, and pressure-temperature phase diagram of uranium dioxide
NASA Astrophysics Data System (ADS)
Wang, Bao-Tian; Zhang, Ping; Lizárraga, Raquel; Di Marco, Igor; Eriksson, Olle
2013-09-01
We present a study of the structural phase transition and the mechanical and thermodynamic properties of UO2 by means of the local density approximation (LDA)+U approach. A phase transition pressure of 40 GPa is obtained from theory at 0 K, and agrees well with the experimental value of 42 GPa. The pressure-induced enhancements of elastic constants, elastic moduli, elastic wave velocities, and Debye temperature of the ground-state fluorite phase are predicted. The phonon spectra of both the ground state fluorite structure and high-pressure cotunnite structure calculated by the supercell approach show that the cotunnite structure is dynamically unstable under ambient pressure. Based on the imaginary mode along the ?-X direction and soft phonon mode along the ?-Z direction, a transition path from cotunnite to fluorite has been identified. We calculate the lattice vibrational energy in the quasiharmonic approximation using both first-principles phonon density of state and the Debye model. The calculated temperature dependence of lattice parameter, entropy, and specific heat agrees well with experimental observations in the low temperature domain. The difference of the Gibbs free energy between the two phases of UO2 has predicted a boundary in the pressure-temperature phase diagram. The solid-liquid boundary is approximated by an empirical equation using our calculated elastic constants.
Phase diagram of oxygen adsorbed on Ni(111) and thermodynamic properties from first-principles
NASA Astrophysics Data System (ADS)
Lazo, C.; Keil, F. J.
2009-06-01
The thermodynamic properties and the surface phase diagram of O/Ni(111) have been calculated from Metropolis and Wang-Landau Monte Carlo simulations based on lateral interactions derived from density-functional theory (DFT) calculations. The DFT energies were mapped onto an Ising-like Hamiltonian according to the cluster expansion technique formalism. Both fcc and hcp adsorption sites were included in the Hamiltonian. Different criteria were used to evaluate competing parameter sets: cross-validation score CV, Mallow’s Cp statistics, and adjusted R2 statistics. The parameter space was searched using genetic algorithms in order to find optimum parameter sets. The different parameter sets obtained from different criteria lead essentially to the same transition temperatures. Excellent agreement is found when comparing the shape and the stability regions of the theoretical and the experimental (from the literature) phase diagrams. We investigate the nature of the p(2×2) and (3×3)R30° phase transitions at ?=1/4 and 1/3 ML, respectively. Differences arise when comparing the values of the calculated and the experimental transition temperatures owing to imprecision in present-day DFT calculations.
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.
Effects of abasic sites on structural, thermodynamic and kinetic properties of quadruplex structures
Esposito, Veronica; Martino, Luigi; Citarella, Giuseppe; Virgilio, Antonella; Mayol, Luciano; Giancola, Concetta; Galeone, Aldo
2010-01-01
Abasic sites represent the most frequent lesion in DNA. Since several events generating abasic sites concern guanines, this damage is particularly important in quadruplex forming G-rich sequences, many of which are believed to be involved in several biological roles. However, the effects of abasic sites in sequences forming quadruplexes have been poorly studied. Here, we investigated the effects of abasic site mimics on structural, thermodynamic and kinetic properties of parallel quadruplexes. Investigation concerned five oligodeoxynucleotides based on the sequence d(TGGGGGT), in which all guanines have been replaced, one at a time, by an abasic site mimic (dS). All sequences preserve their ability to form quadruplexes; however, both spectroscopic and kinetic experiments point to sequence-dependent different effects on the structural flexibility and stability. Sequences d(TSGGGGT) and d(TGGGGST) form quite stable quadruplexes; however, for the other sequences, the introduction of the dS in proximity of the 3â€²-end decreases the stability more considerably than the 5â€²-end. Noteworthy, sequence d(TGSGGGT) forms a quadruplex where dS does not hamper the stacking between the G-tetrads adjacent to it. These results strongly argue for the central role of apurinic/apyrimidinic site damages and they encourage the production of further studies to better delineate the consequences of their presence in the biological relevant regions of the genome. PMID:20026588
Magnetic and thermodynamic properties of face-centered cubic Fe-Ni alloys.
Lavrentiev, M Yu; Wróbel, J S; Nguyen-Manh, D; Dudarev, S L
2014-08-14
A model lattice ab initio parameterized Heisenberg-Landau magnetic cluster expansion Hamiltonian spanning a broad range of alloy compositions and a large variety of chemical and magnetic configurations has been developed for face-centered cubic Fe-Ni alloys. The thermodynamic and magnetic properties of the alloys are explored using configuration and magnetic Monte Carlo simulations over a temperature range extending well over 1000 K. The predicted face-centered cubic-body-centered cubic coexistence curve, the phase stability of ordered Fe3Ni, FeNi, and FeNi3 intermetallic compounds, and the predicted temperatures of magnetic transitions simulated as functions of alloy composition agree well with experimental observations. Simulations show that magnetic interactions stabilize the face-centered cubic phase of Fe-Ni alloys. Both the model Hamiltonian simulations and ab initio data exhibit a particularly large number of magnetic configurations in a relatively narrow range of alloy compositions corresponding to the occurrence of the Invar effect. PMID:24964377
Thermodynamical and electronic properties of Bx Al1-x N alloys: A first principle study
NASA Astrophysics Data System (ADS)
Kumar, S.; Joshi, Suman; Joshi, B.; Auluck, S.
2015-11-01
A series of first principle calculations were carried out to investigate thermodynamical, electronic and optical properties of cubic Bx Al1-x N ordered alloys using supercell approach within density functional theory (DFT). Here we calculate the lattice constants using van der Waals density functional (vdW-DF) at several concentrations (x) of boron. We find that the vdW-DF prediction shows slightly better agreement with experiment in contrast to local density approximation (LDA)/generalized gradient approximation (GGA). The results show that the direct energy band gap (?v-?c) has strong nonlinear dependence on the concentration (x). At x=0.04 and 0.84, Bx Al1-x N has a phase transition from direct to an indirect band gap semiconductor. To describe the alloys' solubility, formation enthalpy were calculated and fitted to quadratic function to obtain interaction parameter. The calculated T-x phase diagram shows a broad miscibility gap with a high critical temperature equal to 3063 K. The calculated dielectric function is explained in terms of band structure and density of states and compared with the available experimental data, showing good agreement.
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.
Structural, Elastic, Electronic Optical and Thermodynamic Properties of {ZnAl}2{S}4
NASA Astrophysics Data System (ADS)
Haddou, A.; Murtaza, G.; Khachai, H.; Khenata, R.; Bin Omran, S.; Ullah, Naeem; Varshney, Dinesh; Bouhemadou, A.
2015-11-01
The structural, elastic, electronic, optical, and thermodynamic properties of the {ZnAl}2{S}_{4 } compound are calculated in the frame work of the density functional theory where the calculated structural parameters are found to be in good agreement with the experimental data and other theoretical calculations. The calculations show that the material is elastically stable and isotropic. Furthermore, the calculated band gap is observed to be wide and direct and is comparable with earlier experimental data as well as with other theoretical calculations; hence, it is an optically active material for optoelectronic applications. In addition, the compound is found to have mixed ionic and covalent bonding nature. The optical nature of the compound is described in terms of the complex dielectric function, complex refractive index, reflectivity, and energy loss function. On the other hand, variation of the unit cell volume, bulk modulus, heat capacity, and Debye temperature are described as a function of temperature at different pressures for the {ZnAl}2{S}4 compound.
NASA Astrophysics Data System (ADS)
Zaghloul, Mofreh R.
2015-11-01
We present computational results and tables of the equation-of-state, thermodynamic properties, and shock Hugoniot for hot dense fluid deuterium. The present results are generated using a recently developed chemical model that takes into account different high density effects such as Coulomb interactions among charged particles, partial degeneracy, and intensive short range hard core repulsion. Internal partition functions are evaluated in a statistical-mechanically consistent way implementing recent developments in the literature. The shock Hugoniot curve derived from the present tables is overall in reasonable agreement with the Hugoniot derived from the Nova-laser shock wave experiments on liquid deuterium, showing that deuterium has a significantly higher compressibility than predicted by the SESAME tables or by Path Integral Monte Carlo calculations. Computational results are presented as surface plots for the dissociated fraction, degree of ionization, pressure, and specific internal energy for densities ranging from 0.0001 to 40 g/cm3 and temperatures from 2000 to ˜106 K. Tables for values of the above mentioned quantities in addition to the specific heat at constant pressure, cp, ratio of specific heats, cp/cv, sound speed and Hugoniot curve (for a specific initial state) are presented for practical use.
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
NASA Astrophysics Data System (ADS)
Yang, Xiao-Yong; Lu, Yong; Zheng, Fa-Wei; Zhang, Ping
2015-11-01
Mechanical, electronic, and thermodynamic properties of zirconium carbide have been systematically studied using the ab initio calculations. The calculated equilibrium lattice parameter, bulk modulus, and elastic constants are all well consistent with the experimental data. The electronic band structure indicates that the mixture of C 2p and Zr 4d and 4p orbitals around the Fermi level makes a large covalent contribution to the chemical bonds between the C and Zr atoms. The Bader charge analysis suggests that there are about 1.71 electrons transferred from each Zr atom to its nearest C atom. Therefore, the Zrâ€“C bond displays a mixed ionic/covalent character. The calculated phonon dispersions of ZrC are stable, coinciding with the experimental measurement. A drastic expansion in the volume of ZrC is seen with increasing temperature, while the bulk modulus decreases linearly. Based on the calculated phonon dispersion curves and within the quasi-harmonic approximation, the temperature dependence of the heat capacities is obtained, which gives a good description compared with the available experimental data. Project supported by the National Natural Science Foundation of China (Grant No. 51071032).
Determination of thermodynamic properties of ternary Al-Cu-Zn alloys by electromotive force method
Van, T.D.; Winand, R. . Dept. of Metallurgy-Electrochemistry)
1994-04-01
The thermodynamic properties of ternary Al-Cu-Zn alloys containing 25 to 62 at % Al have been determined by electromotive force (EMF) measurements between 420 and 920 C by an aluminum concentration cell of the type Al[AlCl[sub 3]-LiCl-KC1] alloy. This concentration cell was evaluated via comparison with known partial free energy for Al measured in liquid Al-Cu alloys by Wilder, and several liquidus temperatures of Al-Cu phase diagram have been determined. From EMF values, activities of Al with respect to mole fraction of Al in ternary Al-Cu-Zn alloys for three quasi-binary sections (x[sub cu]/x[sub zn] = 7/3, 1, and 3/7) at 850 C were determined. The negative deviation from Raoultian behavior observed was more pronounced at high x[sub cu]/x[sub zn] ratios in agreement with binary Al-Zn and Al-Cu phase diagrams.
Structural and thermodynamic properties of WB at high pressure and high temperature
NASA Astrophysics Data System (ADS)
Chen, Hai-Hua; Bi, Yan; Cheng, Yan; Ji, Guangfu; Peng, Fang; Hu, Yan-Fei
2012-12-01
The structure parameters and electronic structures of tungsten boride (WB) have been investigated by using the density functional theory (DFT). Our calculating results display the bulk modulus of WB are 352±2 GPa (K?0=4.29) and 322±3 GPa (K?0=4.21) by LDA and GGA methods, respectively. We have analyzed the probable reason of the discrepancy from the bulk modulus between theoretical and experimental results. The compression behavior of the unit cell axes is anisotropic, with the c-axis being more compressible than the a-axis. By analyzing the bond lengths information, it also demonstrated that WB has a lower compressibility at high pressure. From the partial densities of states (PDOS) of WB, we found that the Fermi lever is mostly contributed by the d states of W atom and p states of B atom and that the contributions from the s, p states of W atom and s states of B atom are small. Moreover, using the Gibbs 2 program, the thermodynamic properties of WB are obtained in a wide temperature range at high pressure for the first time in this work.
Thermodynamics of A?16-21 dissociation from a fibril: Enthalpy, entropy, and volumetric properties.
Rao Jampani, Srinivasa; Mahmoudinobar, Farbod; Su, Zhaoqian; Dias, Cristiano L
2015-11-01
Here, we provide insights into the thermodynamic properties of A ?16-21 dissociation from an amyloid fibril using all-atom molecular dynamics simulations in explicit water. An umbrella sampling protocol is used to compute potentials of mean force (PMF) as a function of the distance ? between centers-of-mass of the A ?16-21 peptide and the preformed fibril at nine temperatures. Changes in the enthalpy and the entropic energy are determined from the temperature dependence of these PMF(s) and the average volume of the simulation box is computed as a function of ?. We find that the PMF at 310 K is dominated by enthalpy while the entropic energy does not change significantly during dissociation. The volume of the system decreases during dissociation. Moreover, the magnitude of this volume change also decreases with increasing temperature. By defining dock and lock states using the solvent accessible surface area (SASA), we find that the behavior of the electrostatic energy is different in these two states. It increases (unfavorable) and decreases (favorable) during dissociation in lock and dock states, respectively, while the energy due to Lennard-Jones interactions increases continuously in these states. Our simulations also highlight the importance of hydrophobic interactions in accounting for the stability of A ?16-21. PMID:26264694
Dahlgren, Björn; Reif, Maria M; Hünenberger, Philippe H; Hansen, Niels
2012-10-01
The raw ionic solvation free energies calculated on the basis of atomistic (explicit-solvent) simulations are extremely sensitive to the boundary conditions and treatment of electrostatic interactions used during these simulations. However, as shown recently [Kastenholz, M. A.; Hünenberger, P. H. J. Chem. Phys.2006, 124, 224501 and Reif, M. M.; Hünenberger, P. H. J. Chem. Phys.2011, 134, 144104], the application of an appropriate correction scheme allows for a conversion of the methodology-dependent raw data into methodology-independent results. In this work, methodology-independent derivative thermodynamic hydration and aqueous partial molar properties are calculated for the Na(+) and Cl(-) ions at P° = 1 bar and T(-) = 298.15 K, based on the SPC water model and on ion-solvent Lennard-Jones interaction coefficients previously reoptimized against experimental hydration free energies. The hydration parameters considered are the hydration free energy and enthalpy. The aqueous partial molar parameters considered are the partial molar entropy, volume, heat capacity, volume-compressibility, and volume-expansivity. Two alternative calculation methods are employed to access these properties. Method I relies on the difference in average volume and energy between two aqueous systems involving the same number of water molecules, either in the absence or in the presence of the ion, along with variations of these differences corresponding to finite pressure or/and temperature changes. Method II relies on the calculation of the hydration free energy of the ion, along with variations of this free energy corresponding to finite pressure or/and temperature changes. Both methods are used considering two distinct variants in the application of the correction scheme. In variant A, the raw values from the simulations are corrected after the application of finite difference in pressure or/and temperature, based on correction terms specifically designed for derivative parameters at P° and T(-). In variant B, these raw values are corrected prior to differentiation, based on corresponding correction terms appropriate for the different simulation pressures P and temperatures T. The results corresponding to the different calculation schemes show that, except for the hydration free energy itself, accurate methodological independence and quantitative agreement with even the most reliable experimental parameters (ion-pair properties) are not yet reached. Nevertheless, approximate internal consistency and qualitative agreement with experimental results can be achieved, but only when an appropriate correction scheme is applied, along with a careful consideration of standard-state issues. In this sense, the main merit of the present study is to set a clear framework for these types of calculations and to point toward directions for future improvements, with the ultimate goal of reaching a consistent and quantitative description of single-ion hydration thermodynamics in molecular dynamics simulations. PMID:26593002
NASA Astrophysics Data System (ADS)
Fisenko, Anatoliy I.; Lemberg, Vladimir
2015-07-01
The thermodynamics of blackbody radiation has been constructed for the entire range of the spectrum. However, in practical applications, thermodynamic functions must be calculated within a finite range of frequencies. The analytical expressions for the radiative and thermodynamic properties of blackbody radiation over an arbitrary spectral range of the electromagnetic spectrum are obtained. The Wien displacement law, Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, and pressure are expressed in terms of the polylogarithm functions. These expressions are important when we build a theoretical model of radiative heat transfer, for example. The thermodynamic functions of blackbody radiation are calculated for various ranges of the spectrum at different temperatures. As an example of practical applications, thermodynamics of the cosmic microwave background radiation measured by the COBE FIRAS instrument is constructed. The expressions obtained for the radiative and thermodynamic functions of blackbody radiation can easily be presented in wavelength and wavenumber domains.
Thermodynamic properties of bromomethanes and bromomethyl radicals: An ab initio study
Paddison, S.J.; Tschuikow-Roux, E.
1998-05-01
Thermochemical data on volatile organic compounds containing bromine are needed for atmospheric modeling, in view of their ozone depletion potential upon photodissociation and the release of atomic bromine. Yet even for the bromomethane series, with the exception of CH{sub 3}Br, thermodynamic properties are not well established. Similarly, structural and thermochemical information on brominated methyl radicals is incomplete or not available. In this paper the authors have adopted a computational approach to obtain this needed information. Equilibrium geometries for the molecules CH{sub 4{minus}n}Br{sub n} (n = 0--4) and radicals CH{sub 3{minus}m}Br{sub m} (m = 0--3) were optimized at both HF/6-31G{sup *} and MP2/6-31G{sup *} levels of theory. Moments of inertia, harmonic vibrational frequencies, and thermodynamic functions were determined at the HF/6-31G{sup *} level. Electron correlation contributions were performed by single-point calculations at both second- and fourth-order Moeller-Plesset perturbation theory for derived MP2/6-31G{sup *} geometries. Enthalpies of formation were obtained from a consideration of applicable isodesmic reactions using the derived MP4/6-31G{sup **}//MP2/6-31G{sup *} total energies in conjunction with experimentally established enthalpies of formation for CH{sub 3}Br, CH{sub 4}, and CH{sub 3}. These data were then used in the determination of {Delta}H{degree}{sub f,T}, {Delta}G{degree}{sub f,T}, and K{sub f,T} for all species over the temperature range 0 to 1500 K. A comparison was made to the existing standard enthalpies of formation at 298 K, both experimentally measured and theoretically estimated, for CH{sub 2}Br{sub 2}, CHBr{sub 3}, CBr{sub 4}, CH{sub 2}Br{sm_bullet}, CHBr{sub 2}{sm_bullet}, and CBr{sub 3}{sm_bullet}.
NASA Astrophysics Data System (ADS)
Chai, Weisin
The scarcity and sustainability of energy sources have always been a concern while seeking for alternative fuels. Biofuels have drawn the attention of various researchers due to their abundancy and renewability. Understanding the physical and chemical properties of these molecules is essential to determining their potential as alternative fuels or fuel additives. In this work, the properties of these molecules are predicted through methods developed from quantum mechanics and statistical mechanics theories. The heats of formations are calculated with the Gaussian program and combined with the Benson group contribution method to predict the Benson parameters of unknown functional groups in a molecule. The methods developed are used to expand the Benson database and improve the practicability of the group contribution method. The heats of formations are also used to predict and correlate heat capacities across a range of temperatures and energy densities in this study.
NASA Astrophysics Data System (ADS)
Jacobs, M.; Schmid-Fetzer, R.
2012-04-01
A prerequisite for the determination of pressure in static high pressure measurements, such as in diamond anvil cells is the availability of accurate equations of state for reference materials. These materials serve as luminescence gauges or as X-ray gauges and equations of state for these materials serve as secondary pressure scales. Recently, successful progress has been made in the development of consistency between static, dynamic shock-wave and ultrasonic measurements of equations of state (e.g. Dewaele et al. Phys. Rev. B70, 094112, 2004, Dorogokupets and Oganov, Doklady Earth Sciences, 410, 1091-1095, 2006, Holzapfel, High Pressure Research 30, 372-394, 2010) allowing testing models to arrive at consistent thermodynamic descriptions for X-ray gauges. Apart from applications of metallic elements in high-pressure work, thermodynamic properties of metallic elements are also of mandatory interest in the field of metallurgy for studying phase equilibria of alloys, kinetics of phase transformation and diffusion related problems, requiring accurate thermodynamic properties in the low pressure regime. Our aim is to develop a thermodynamic data base for metallic alloy systems containing Ag, Al, Au, Cu, Fe, Ni, Pt, from which volume properties in P-T space can be predicted when it is coupled to vibrational models. This mandates the description of metallic elements as a first step aiming not only at consistency in the pressure scales for the elements, but also at accurate representations of thermodynamic properties in the low pressure regime commonly addressed in metallurgical applications. In previous works (e.g. Jacobs and de Jong, Geochim. Cosmochim. Acta, 71, 3630-3655, 2007, Jacobs and van den Berg, Phys. Earth Planet. Inter., 186, 36-48, 2011) it was demonstrated that a lattice vibrational framework based on Kieffer's model for the vibrational density of states, is suitable to construct a thermodynamic database for Earth mantle materials. Such a database aims at, when coupled to a thermodynamic computation program, the calculation and prediction of phase equilibria and thermo-physical properties of phase equilibrium assemblages in pressure-temperature-composition space. In Jacobs and van den Berg (2011) the vibrational method, together with a thermodynamic data base, was successfully applied to mantle convection of materials in the Earth. These works demonstrate that the vibrational method has the advantages of (1) computational speed, (2) coupling or making comparisons with ab initio methods and (3) making reliable extrapolations to extreme conditions. We present results of thermodynamic analyses, using lattice vibrational methods, of Ag, Al, Au, Cu and MgO covering the pressure and temperature regime of the Earth's interior. We show results on consistency of the pressure scales for these materials using different equations of state, under the constraint that thermodynamic properties in the low-pressure regime are accurately represented.
Wen, X.J.; Zhong, X.H.; Peng, G.X.; Shen, P.N.; Ning, P.Z.
2005-07-01
Thermodynamic formulas for investigating systems with density- and/or temperature-dependent particle masses are generally derived from the fundamental derivation equality of thermodynamics. Various problems in the previous treatments are discussed and modified. Properties of strange quark matter in bulk and strangelets at both zero and finite temperature are then calculated based on the new thermodynamic formulas with a new quark mass scaling, which indicates that low-mass strangelets near {beta} equilibrium are multiquark states with an antistrange quark, such as the pentaquark (u{sup 2}d{sup 2}s) for baryon number 1 and the octaquark (u{sup 4}d{sup 3}s) for dibaryon, etc.
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.
Thermodynamic properties of CexTh1-xO2 solid solution from first-principles calculations
Xiao, Haiyan; Zhang, Yanwen; Weber, William J
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
NASA Technical Reports Server (NTRS)
Colon, G.
1981-01-01
The evaluation of the thermodynamic properties of a gas mixture can be performed using a generalized correlation which makes use of the second virial coefficient. This coefficient is based on statistical mechanics and is a function of temperature and composition, but not of pressure. The method provides results accurate to within 3 percent for gases which are nonpolar or only slightly polar. When applied to highly polar gases, errors of 5 to 10 percent may result. For gases which associate, even larger errors are possible. The sequences of calculations can be routinely programmed for a digital computer. The thermodynamic properties of a mixture of neon, argon and ethane were calculated by such a program. The result will be used for the design of the gas replenishment system for the Energetic Gamma Ray Experiment Telescope.
NASA Astrophysics Data System (ADS)
Loktionov, I. K.
2015-03-01
The equilibrium thermodynamic properties of simple liquids are described quantitatively using a statistical approach based on the model with a four-parametric oscillating interaction potential. The problem of selecting the constants of the initial potential for reproducing of the experimental pattern correctly is reduced to determining a single variable parameter. Asymptotically exact concepts are obtained for the inter-particle potential and for thermodynamic functions, which depend only on this parameter (the optimal value of this parameter is used for calculating the properties of the model on the phase-equilibrium line and in the supercritical region). The results of calculations are compared with experimental data and the results of the models with two-constant equations of state of the cubic type.
NASA Astrophysics Data System (ADS)
Nezbeda, Ivo; Lisal, Martin
Three realistic potential models of water, the non-polarizable ST2 and TIP4P models, and the polarizable TIP4P/P model, were used in computer simulations to study the effect of the range of intermolecular interactions on the thermodynamic properties of water. Following the results of recent studies, a short range system is constructed to the full pair potential u (1,2) in such a way that a perturbation expansion can be formulated in powers of the dipole-dipole interaction only. Computations of low density properties and computer simulations performed for several densities on three subcritical and one supercritical isotherms show that the short range reference not only reproduces the structure but approximates also the internal energy and pressure of water surprisingly well. Differences in the internal energy between the full and short range water do not exceed 5% for all models used over the entire range of the thermodynamic conditions considered.
First-principles study of the elastic and thermodynamic properties of CaSiO3 perovskite
NASA Astrophysics Data System (ADS)
Liu, Z. J.; Sun, X. W.; Chen, Q. F.; Cai, L. C.; Wu, H. Y.; Ge, S. H.
2007-06-01
The thermodynamic and elastic properties of CaSiO3 perovskite are investigated at high pressures and temperatures using the plane wave pseudopotential method within the local density approximation. The athermal elastic moduli of CaSiO3 perovskite are calculated as a function of pressure up to 200 GPa. The calculated results are in excellent agreement with available experimental data at high pressure, and compare favourably with other pseudopotential predictions over the pressure regime studied. It is also found that the elastic anisotropy drops rapidly with the increase of pressure initially, and then decreases more slowly at higher pressures. The thermodynamic properties of CaSiO3 perovskite are predicted using the quasi-harmonic Debye model for the first time; the heat capacity and the thermal expansion coefficient agree with the observed values at ambient conditions and the other calculations at high pressures and temperatures.
First-principles study of the elastic and thermodynamic properties of CaSiO(3) perovskite.
Liu, Z J; Sun, X W; Chen, Q F; Cai, L C; Wu, H Y; Ge, S H
2007-06-20
The thermodynamic and elastic properties of CaSiO(3) perovskite are investigated at high pressures and temperatures using the plane wave pseudopotential method within the local density approximation. The athermal elastic moduli of CaSiO(3) perovskite are calculated as a function of pressure up to 200 GPa. The calculated results are in excellent agreement with available experimental data at high pressure, and compare favourably with other pseudopotential predictions over the pressure regime studied. It is also found that the elastic anisotropy drops rapidly with the increase of pressure initially, and then decreases more slowly at higher pressures. The thermodynamic properties of CaSiO(3) perovskite are predicted using the quasi-harmonic Debye model for the first time; the heat capacity and the thermal expansion coefficient agree with the observed values at ambient conditions and the other calculations at high pressures and temperatures. PMID:21694039
NASA Astrophysics Data System (ADS)
Zhang, Shen; Zhao, Shijun; Kang, Wei; Zhang, Ping; He, Xian-Tu
2016-03-01
A precise calculation that translates shifts of x-ray K absorption edges to variations of thermodynamic properties allows quantitative characterization of interior thermodynamic properties of warm dense plasmas by x-ray absorption techniques, which provides essential information for inertial confinement fusion and other astrophysical applications. We show that this interpretation can be achieved through an improved first-principles method. Our calculation shows that the shift of K edges exhibits selective sensitivity to thermal parameters and thus would be a suitable temperature index to warm dense plasmas. We also show with a simple model that the shift of K edges can be used to detect inhomogeneity inside warm dense plasmas when combined with other experimental tools.
NASA Astrophysics Data System (ADS)
Wentzcovitch, R. M.; Da Silveira, P. R.; Wu, Z.; Yu, Y.
2013-12-01
Today first principles calculations in mineral physics play a fundamental role in understanding of the Earth. They complement experiments by expanding the pressure and temperature range for which properties can be obtained and provide access to atomic scale phenomena. Since the wealth of predictive first principles results can hardly be communicated in printed form, we have developed online applications where published results can be reproduced/verified online and extensive unpublished results can be generated in customized form. So far these applications have included thermodynamics properties of end-member phases and thermal elastic properties of end-member phases and few solid solutions. Extension of this software infrastructure to include other properties is in principle straightforward. This contribution will review the nature of results that can be generated (methods, thermodynamics domain, list of minerals, properties, etc) and nature of the software infrastructure. These applications are part of a more extensive cyber-infrastructure operating in the XSEDE - the VLab Science Gateway [1]. [1] https://www.xsede.org/web/guest/gateways-listing Research supported by NSF grants ATM-0428744 and EAR-1047629.
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 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.
NASA Astrophysics Data System (ADS)
Zhang, JunMin; Lu, ChunRong; Guan, YongGang; Liu, WeiDong
2015-10-01
Because the fault arc in aircraft electrical system often causes a fire, it is particularly important to analyze its energy and transfer for aircraft safety. The calculation of arc energy requires the basic parameters of the arc. This paper is mainly devoted to the calculations of equilibrium composition, thermodynamic properties (density, molar weight, enthalpy, and specific heat at constant pressure) and transport coefficients (thermal conductivity, electrical conductivity, and viscosity) of plasmas produced by a mixture of air, Cu, and polytetrafluoroethylene under the condition of local thermodynamic equilibrium. The equilibrium composition is determined by solving a system of equations around the number densities of each species. The thermodynamic properties are obtained according to the standard thermodynamic relationships. The transport coefficients are calculated using the Chapman-Enskog approximations. Results are presented in the temperature range from 3000 to 30 000 K for pressures of 0.08 and 0.1 MPa, respectively. The results are more accurate and are reliable reference data for theoretical analysis and computational simulation of the behavior of fault arc.
Thermodynamic properties of alloys of the Al-Co and Al-Co-Sc systems
NASA Astrophysics Data System (ADS)
Shevchenko, M. A.; Berezutskii, V. V.; Ivanov, M. I.; Kudin, V. G.; Sudavtsova, V. S.
2014-05-01
Enthalpies of mixing for melts of the binary Al-Co system at 1870 K in the range 0 < x Co < 0.25, and at 1620 K, 0 < x Co < 0.12, are investigated by means of isoperibolic calorimetry. Enthalpies of mixing for melts of the ternary Al-Co-Sc system are investigated at 1870 K for sections Al0.75(1 - x)Co0.25(1 - x)Sc x , 0 < x < 0.024, and Al0.88(1 - x)Co0.12(1 - x)Sc x , 0 < x < 0.044. Using the literature data on the enthalpies of mixing for liquid and solid alloys, the activities of melt components, and the phase diagram of the Al-Co system, the thermodynamic properties of liquid and solid alloys of the Al-Co system over a wide range of temperatures and compositions are calculated using a software package of our own design, based on the model of ideal associated solutions (IAS). The enthalpies of mixing and the liquidus surface of the phase diagram of the ternary Al-Co-Sc system over the interval of concentrations are estimated by modeling with data on binary boundary subsystems. All of the components of both the binary Al-Co and ternary Al-Co-Sc systems tend to interact with one another quite strongly: ? H min(Al-Co) = -32.5 kJ/mol at x Co = 0.44; ? H min(Al-Co-Sc) = -46 kJ/mol for Al0.4Co0.3Sc0.3 (estimated).
Thermodynamic properties for rare earths and americium in pyropartitioning process solvents
Fusselman, S.P.; Roy, J.J.; Grimmett, D.L.
1999-07-01
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 LiCl-KCl and activity coefficients for Cd and Bi. Data were obtained between 400 and 500 C. Results for the rare earth chlorides using an improved experimental technique were consistent with theory, with standard free energy of formation values somewhat more negative than those found in the literature. Special attention was given to Am in the LiCl-KCl/Cd system because it can exist as the +2 and/or +3 ion in this system. Americium ions existed only as the +3 ion in LiCl-KCl/Bi. Standard electrochemical potentials for Am/Am{sup +2} in LiCl-KCl eutectic at 400, 450, and 500 C were {minus}2.893, {minus}2.853, and {minus}2.838 V, respectively, relative to Cl{sup 2}/Cl{sup {minus}}. Standard electrochemical potentials vs. Cl{sub 2}/Cl{sup {minus}} for Am/Am{sup +3} in LiCl-KCl eutectic were {minus}2.83 V at 450 C and {minus}2.78 V at 500 C. Activity coefficients for Am in molten Cd were 1 {times} 10{sup {minus}5} and 8 {times} 10{sup {minus}5} at 450 and 500 C.
NASA Astrophysics Data System (ADS)
Martelli, Fausto; Vuilleumier, Rodolphe; Simonin, Jean-Pierre; Spezia, Riccardo
2012-10-01
In this work, we show how increasing the charge of small cations affects the structural, thermodynamical, and dynamical properties of these ions in liquid water. We have studied the case of lanthanoid and actinoid ions, for which we have recently developed accurate polarizable force fields, and the ionic radius is in the 0.995-1.250 Å range, and explored the valency range from 0 to 4+. We found that the ion charge strongly structures the neighboring water molecules and that, in this range of charges, the hydration enthalpies exhibit a quadratic dependence with respect to the charge, in line with the Born model. The diffusion process follows two main regimes: a hydrodynamical regime for neutral or low charges, and a dielectric friction regime for high charges in which the contraction of the ionic radius along the series of elements causes a decrease of the diffusion coefficient. This latter behavior can be qualitatively described by theoretical models, such as the Zwanzig and the solvated ion models. However, these models need be modified in order to obtain agreement with the observed behavior in the full charge range. We have thus modified the solvated ion model by introducing a dependence of the bare ion radius as a function of the ionic charge. Besides agreement between theory and simulation this modification allows one to obtain an empirical unified model. Thus, by analyzing the contributions to the drag coefficient from the viscous and the dielectric terms, we are able to explain the transition from a regime in which the effect of viscosity dominates to one in which dielectric friction governs the motion of ions with radii of ca. 1 Å.
2014-01-01
Background Urease, one of the highly efficient known enzymes, catalyzes the hydrolysis of urea into ammonia and carbon dioxide. The present study aimed to extract urease from pea seeds (Pisum Sativum L). The enzyme was then purified in three consequence steps: acetone precipitation, DEAE-cellulose ion-exchange chromatography, and gel filtration chromatography (Sephacryl S-200 column). Results The purification fold was 12.85 with a yield of 40%. The molecular weight of the isolated urease was estimated by chromatography to be 269,000 Daltons. Maximum urease activity (190 U/g) was achieved at the optimum conditions of 40°C and pH of 7.5 after 5 min of incubation. The kinetic parameters, K m and V max , were estimated by Lineweaver-Burk fits and found to be 500 mM and 333.3 U/g, respectively. The thermodynamic constants of activation, ?H, E a , and ?S, were determined using Arrhenius plot and found to be 21.20 kJ/mol, 23.7 kJ/mol, and 1.18 kJ/mol/K, respectively. Conclusions Urease was purified from germinating Pisum Sativum L. seeds. The purification fold, yield, and molecular weight were determined. The effects of pH, concentration of enzyme, temperature, concentration of substrate, and storage period on urease activity were examined. This may provide an insight on the various aspects of the property of the enzyme. The significance of extracting urease from different sources could play a good role in understanding the metabolism of urea in plants. PMID:25065975
Structural, vibrational, and thermodynamic properties of Al-Sc alloys and intermetallic compounds
NASA Astrophysics Data System (ADS)
Asta, M.; Ozoli?š, V.
2001-09-01
We present results of a theoretical study of the temperature-dependent structural and thermodynamic properties of solid-phase Al-Sc alloys and compounds based upon first-principles calculations of electronic free energies and ionic vibrational spectra. This work extends a previous first-principles study of the fcc portion of the Al-Sc phase diagram which demonstrated a large effect of vibrational free energy upon calculated Sc solid-solubility limits [V. Ozoli?š and M. Asta, Phys. Rev. Lett. 86, 448 (2001)]. Here the contributions of nonconfigurational (electronic and vibrational) entropies to the free energies of solid-phase Al-Sc alloys and compounds are analyzed in further detail, and the accuracy of the approximations employed in these calculations is assessed. For each of the reported intermetallic compounds in this system, calculated formation enthalpies agree to within 10% (0.05 eV/atom) of published calorimetry measurements. Large negative entropies of formation, equal to -0.77kB/atom, -0.58kB/atom, and -0.24kB/atom are calculated for cubic Al3Sc, cubic AlSc, and orthorhombic AlSc compounds, respectively, resulting primarily from the stiffening of nearest-neighbor Al-Sc bonds in the intermetallic phases relative to elemental Al and Sc. The net effects of nonconfigurational free energy contributions to the fcc portion of the Al-Sc phase diagram are 100 and 450 K decreases in the calculated Al solvus phase boundary temperatures associated with electronic and vibrational entropy, respectively, at the maximum measured Sc solid-solubility limit.
Thermodynamic properties of calcium-bismuth alloys determined by emf measurements
Kim, H; Boysen, DA; Bradwell, DJ; Chung, BC; Jiang, K; Tomaszowska, AA; Wang, KL; Wei, WF; Sadoway, DR
2012-01-15
The thermodynamic properties of Ca-Bi alloys were determined by electromotive force (emf) measurements to assess the suitability of Ca-Bi electrodes for electrochemical energy storage applications. Emf was measured at ambient pressure as a function of temperature between 723 K and 1173 K using a Ca(s)vertical bar CaF2(s)vertical bar Ca(in Bi) cell for twenty different Ca-Bi alloys spanning the entire range of composition from chi(Ca) = 0 to 1. Reported are the temperature-independent partial molar entropy and enthalpy of calcium for each Ca-Bi alloy. Also given are the measured activities of calcium, the excess partial molar Gibbs energy of bismuth estimated from the Gibbs-Duhem equation, and the integral change in Gibbs energy for each Ca-Bi alloy at 873 K, 973 K, and 1073 K. Calcium activities at 973 K were found to be nearly constant at a value a(Ca) = 1 x 10(-8) over the composition range chi(Ca) = 0.32-0.56, yielding an emf of similar to 0.77 V. Above chi(Ca) = 0.62 and coincident with Ca5Bi3 formation, the calcium activity approached unity. The Ca-Bi system was also characterized by differential scanning calorimetry over the entire range of composition. Based upon these data along with the emf measurements, a revised Ca-Bi binary phase diagram is proposed. (C) 2011 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Tanaka, Hideki; Gubbins, Keith E.
1992-08-01
Thermodynamic properties and structures of water-methanol mixtures at various temperatures have been investigated by means of Monte Carlo simulations and subsequent analyses. The OPLS model by Jorgensen was used for the methanol-methanol interaction and both the Caravetta-Clementi (CC) potential and TIP4P potential by Jorgensen et al. were used for the water-water interaction. We show that the role of water-water interaction is very important in discussing aqueous solutions of alcohols, and examine the origin of the exothermic mixing processes. We have investigated the sensitivity of the temperature dependence of the enthalpy of mixing to the water-water interaction. The CC potential is able to reproduce the temperature dependence observed in experiments, although the absolute values of the mixing enthalpy were larger than the experimental ones. While the TIP4P potential results in better agreement for the excess enthalpy and volume near room temperature, the temperature dependence of the excess enthalpy did not agree with experiment. The difference in the magnitude of the exothermic hydration for different water-water interactions is explained in terms of the energetic stability of the clathrate hydrate compared with ice, on the basis that the structure of water in the vicinity of a methanol molecule is similar to the clathrate hydrate. It is found that the energetic stability of the clathrate hydrate for the CC model is higher than that for TIP4P, and this is responsible for the larger exothermic hydration. The higher stability of the clathrate hydrate structure for the CC potential, in turn, arises from the difference in the pair interaction energy surface between two kinds of potential functions; the minimum energy structure and the flexibility of the hydrogen bonded pair.
NASA Astrophysics Data System (ADS)
Khedr, M. Bahaa; Osman, S. M.
2011-10-01
A brief review is presented for the pre-history and discovery of fullerenes. Single-site potentials with parameters proposed by Girifalco was used to describe the interactions of the fullerene molecules C70 and C96. We present theoretical model for calculating the thermodynamic properties of liquid for both C70 and C96 by means of an improved equation of state (EOS), in which the particles are interacting via pair wise interaction composed of suitable linear combination of three Yukawa functions (3YK). The proposed equation of state provides a powerful mathematical formalism for the Helmholtz free energy and the pressure within the series mean-spherical approximation (SMSA) which are the basic ingredients to compute the liquid-vapour coexistence curve of C70 and C96 as well as the other thermodynamic properties for the bulk liquid and the vapour phases. The comparisons with Gibbs ensemble Monte Carlo (GEMC) simulations and the self-consistent Ornstein-Zernike approximation (SCOZA) were carried out. The estimated critical parameters for both C70 and C96 are TC = 2176 K, ?C = 0.44 nm-3, PC = 51.64 bars and TC = 2477 K, ?C = 0.32 nm-3, PC = 44.28 bars respectively. It is to be noted that the obtained results of the thermodynamic properties along the binodal curves of C70 and C96 are exhibit interesting features.
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.
NASA Astrophysics Data System (ADS)
Muhammad, Zafar; Shabbir, Ahmed; Shakil, M.; A. Choudhary, M.
2014-10-01
In this study the pseudo-potential method is used to investigate the structural, electronic, and thermodynamic properties of ZnO1-xSx semiconductor materials. The results show that the electronic properties are found to be improved when calculated by using LDA + U functional as compared with local density approximation (LDA). At various concentrations the ground-state properties are determined for bulk materials ZnO, ZnS, and their tertiary alloys in cubic zinc-blende phase. From the results, a minor difference is observed between the lattice parameters from Vegard's law and other calculated results, which may be due to the large mismatch between lattice parameters of binary compounds ZnO and ZnS. A small deviation in the bulk modulus from linear concentration dependence is also observed for each of these alloys. The thermodynamic properties, including the phonon contribution to Helmholtz free energy ?F, phonon contribution to internal energy ?E, and specific heat at constant-volume CV, are calculated within quasi-harmonic approximation based on the calculated phonon dispersion relations.
NASA Astrophysics Data System (ADS)
Liu, Chun Mei; Xu, Chao; Duan, Man Yi
2015-10-01
SnS has potential technical applications, but many of its properties are still not well studied. In this work, the structural, thermodynamic, elastic, and electronic properties of ?-SnS have been investigated by the plane wave pseudo-potential density functional theory with the framework of generalised gradient approximation. The calculated pressure-dependent lattice parameters agree well with the available experimental data. Our thermodynamic properties of ?-SnS, including heat capacity CP , entropy S, and Gibbs free energy relation of -(GT -H0) curves, show similar growth trends as the experimental data. At T=298.15 K, our CP =52.31 J/mol·K, S=78.93 J/mol·K, and -(GT -H0)=12.03 J/mol all agree very well with experimental data CP =48.77 J/mol·K and 49.25 J/mol·K, S=76.78 J/mol·K, and -(GT -H0)=12.38 J/mol. The elastic constants, together with other elastic properties, are also computed. The anisotropy analyses indicate obvious elastic anisotropy for ?-SnS along different symmetry planes and axes. Moreover, calculations demonstrate that ?-SnS is an indirect gap semiconductor, and it transforms to semimetal with pressure increasing up to 10.2 GPa. Combined with the density of states, the characters of the band structure have been analysed in detail.
Wu, C.K.; Law, C.K.
1984-01-01
The charts of thermodynamic properties of burned gas in chemical equilibrium have been used for many years in the calculation of engine cycles in which the real thermodynamic nature of the gases needs to be considered. With the development of computer programs for engine cycle calculations and for computing the equilibrium composition and thermodynamic properties of gases, it is natural in research work to include the calculation of gas properties in the computer program for the modeling of engine cycle without the use of charts. However, for instructional purposes, it is important for the students to have a clear understanding of the thermodynamics of engine cycles, and the charts are a convenient tool for learning. In a textbook of internal combustion engines, such charts are still useful. They can also be used in some practical work when the computer programs are not readily available. In this country, the often used charts of Hottel, et al. and Newhall-Starkman are in English units. It would be desirable to have the charts given in SI units so as to be consistent with textbooks using the international system of units. The octane-air charts are intended for calculation of engine cycles using ordinary petroleum fuel, and the other charts are for examples with new or alternate fuels. Equilibrium compositions of the three burned mixtures of octane and air at a pressure of 5 x 10/sup 6/ pa are shown. These charts have been calculated with the NASA program, run on the CDC Cyber 170/730 computer and plotted in colored lines on the Calcommp 1051 plotter in the Vogelbeck Computing Center of Northwestern University.
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 1â‰¤ vâ‰¤ 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 Ïƒ are calculated. In the case of the dipole spectrum, the constants a and Ïƒ, 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 Ïƒ, 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 zâ‰ˆ1089 are calculated.
The thermodynamic properties of 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene
Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K.; Steele, W.V.
1992-12-01
Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, vibrating-tube densitometry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). Critical properties were estimated for both materials based on the measurement results. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gases for selected temperatures between 380 K and 700 K. The property-measurement results reported here for 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene are the first for these important intermediates in the pyrene/H{sub 2} hydrogenation reaction network.
NASA Astrophysics Data System (ADS)
Yang, Aijun; Liu, Yang; Sun, Bowen; Wang, Xiaohua; Cressault, Yann; Zhong, Linlin; Rong, Mingzhe; Wu, Yi; Niu, Chunping
2015-12-01
This paper is devoted to the calculation of fundamental properties of CO2 mixed with C2F4. The species composition and thermodynamic properties (mass density, entropy, enthalpy and specific heat at constant pressure) are based on Gibbs free energy minimization. The transport properties (electrical conductivity, viscosity and thermal conductivity) are calculated by the well-known Chapman-Enskog method. The Lennard-Jones like phenomenological potential and some recently updated transport cross sections are adopted to obtain collision integrals. The calculation is developed in the temperature range between 300 and 30?000?K, for a pressure between 1 to 16 bar and for several C2F4 proportions. Transport coefficients for CO2 are also compared with previous published values, and the reasons for discrepancies are analyzed. The results obtained for CO2–C2F4 mixtures provide reliable reference data for the simulation of switching arcs in CO2 circuit breakers with the ablation of PTFE.
Crystal structure and thermodynamic properties of NdCu4Au compound
NASA Astrophysics Data System (ADS)
Tchoula TchokontÃ©, Moise Bertin; Bashir, Aiman Kamal; Strydom, A. M.
2016-03-01
We report the synthesis of the antiferromagnet cubic-type structure NdCu4Au derived by substituting Au for Cu in the parent binary NdCu5 compound. The room temperature X-ray diffraction analysis indicates a cubic MgCu4Sn-type structure with space group F 4 bar 3 m (No. 216) for the NdCu4Au compound. The thermodynamic properties of NdCu4Au have been probed by magnetic susceptibility, Ï‡(T), magnetization, M(Î¼0 H), and specific heat, Cp(T), measured down to 1.8 K. The low temperature Ï‡(T) data shows probably an antiferromagnetic (AFM)-like anomaly associated with a NÃ©el temperature TN=3.9 K. In the paramagnetic region, Ï‡(T) data follows the modified Curie-Weiss law with an effective magnetic moment Î¼eff = 3.547(5) Î¼B and Weiss temperature Î¸p = - 10.19(8) K. The value for Î¼eff is close to the value of 3.62 Î¼B expected for the Nd3+-ion. No evidence of metamagnetic transition was observed from the isothermal M(Î¼0 H) results. Cp(T) data confirm the AFM phase transition at TN=3.5 K close to the value of 3.9 K observed in Ï‡(T). The 4f-electron specific heat shows a Schottky-type anomaly around 20 K associated with crystalline-electric-field (CEF), with energy splitting Î”1=62(5) K and Î”2=109(9) K of the Nd3+ (J=9/2) multiplet, that are associated with the first and second excited state of Nd3+-ion. From the results of the 4f-electron magnetic entropy, it is speculated that the CEF ground state of Nd3+ (J=9/2) ions is the Î“6 doublet for NdCu4Au.
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
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
Asta, M.; Foiles, S.M.; Quong, A.A.
1998-05-01
The configurational thermodynamic properties of fcc-based Al-Sc alloys and coherent Al/Al{sub 3}Sc interphase-boundary interfaces have been calculated from first principles. The computational approach used in this study combines the results of pseudopotential total-energy calculations with a cluster-expansion description of the alloy energetics. Bulk and interface configurational-thermodynamic properties are computed using a low-temperature-expansion technique. Calculated values of the {l_brace}100{r_brace} and {l_brace}111{r_brace} Al/Al{sub 3}Sc interfacial energies at zero temperature are, respectively, 192 and 226mJ/m{sup 2}. The temperature dependence of the calculated interfacial free energies is found to be very weak for {l_brace}100{r_brace} and more appreciable for {l_brace}111{r_brace} orientations; the primary effect of configurational disordering at finite temperature is to reduce the degree of crystallographic anisotropy associated with calculated interfacial free energies. The first-principles-computed solid-solubility limits for Sc in bulk fcc Al are found to be underestimated significantly in comparison with experimental measurements. It is argued that this discrepancy can be largely attributed to nonconfigurational contributions to the entropy which have been neglected in the present thermodynamic calculations. {copyright} {ital 1998} {ital The American Physical Society}
Urrutia, Ignacio
2014-12-28
This work is devoted to analyze the relation between the thermodynamic properties of a confined fluid and the shape of its confining vessel. Recently, new insights in this topic were found through the study of cluster integrals for inhomogeneous fluids that revealed the dependence on the vessel shape of the low density behavior of the system. Here, the statistical mechanics and thermodynamics of fluids confined in wedges or by edges is revisited, focusing on their cluster integrals. In particular, the well known hard sphere fluid, which was not studied in this framework so far, is analyzed under confinement and its thermodynamic properties are analytically studied up to order two in the density. Furthermore, the analysis is extended to the confinement produced by a corrugated wall. These results rely on the obtained analytic expression for the second cluster integral of the confined hard sphere system as a function of the opening dihedral angle 0 < Î² < 2Ï€. It enables a unified approach to both wedges and edges.
NASA Astrophysics Data System (ADS)
Tian, Yali; Zhou, Wei; Wu, Ping
2015-11-01
The structural, elastic and thermodynamic properties of AuSn, AuSn2, AuSn4 and Au5Sn are investigated by first-principles calculations. Through calculation, the four intermetallic compounds are all thermodynamically stable and AuSn has the largest negative formation energy. They are all ductile, anisotropic and have low stiffness. In addition, Au5Sn is different from the others, since it is elastically unstable and possesses the highest anisotropy and hardness, mainly due to the strong Au-Au covalent bonds. Based on the quasi-harmonic Debye model, the thermodynamic properties of AuSn, such as the volume, thermal expansion coefficient, bulk modulus, Debye temperature and heat capacity with temperature variation in the range of 0-20 GPa, are obtained. The results indicate the increments of both the volume and thermal expansion coefficient with temperature become slow when the pressure is more than 10 GPa, and the bulk modulus and Debye temperature are almost constant below 100 K and then become linear decreasing as temperature increases. It is found that the influence of temperature on heat capacity is much more obvious than that of pressure.
NASA Astrophysics Data System (ADS)
Tian, Yali; Zhou, Wei; Wu, Ping
2016-01-01
The structural, elastic and thermodynamic properties of AuSn, AuSn2, AuSn4 and Au5Sn are investigated by first-principles calculations. Through calculation, the four intermetallic compounds are all thermodynamically stable and AuSn has the largest negative formation energy. They are all ductile, anisotropic and have low stiffness. In addition, Au5Sn is different from the others, since it is elastically unstable and possesses the highest anisotropy and hardness, mainly due to the strong Au-Au covalent bonds. Based on the quasi-harmonic Debye model, the thermodynamic properties of AuSn, such as the volume, thermal expansion coefficient, bulk modulus, Debye temperature and heat capacity with temperature variation in the range of 0-20 GPa, are obtained. The results indicate the increments of both the volume and thermal expansion coefficient with temperature become slow when the pressure is more than 10 GPa, and the bulk modulus and Debye temperature are almost constant below 100 K and then become linear decreasing as temperature increases. It is found that the influence of temperature on heat capacity is much more obvious than that of pressure.
Mairhofer, Jonas; Sadus, Richard J
2013-10-21
Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima?minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties. PMID:24160523
NASA Astrophysics Data System (ADS)
Mairhofer, Jonas; Sadus, Richard J.
2013-10-01
Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima/minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties.
NASA Astrophysics Data System (ADS)
Duff, Andrew Ian; Davey, Theresa; Korbmacher, Dominique; Glensk, Albert; Grabowski, Blazej; Neugebauer, Jörg; Finnis, Michael W.
2015-06-01
Thermodynamic properties of ZrC are calculated up to the melting point (Tmelt?3700 K ), using density functional theory (DFT) to obtain the fully anharmonic vibrational contribution, and including electronic excitations. A significant improvement is found in comparison to results calculated within the quasiharmonic approximation. The calculated thermal expansion is in better agreement with experiment and the heat capacity reproduces rather closely a CALPHAD estimate. The calculations are presented as an application of a development of the upsampled thermodynamic integration using Langevin dynamics (UP-TILD) approach. This development, referred to here as two-stage upsampled thermodynamic integration using Langevin dynamics (TU-TILD), is the inclusion of tailored interatomic potentials to characterize an intermediate reference state of anharmonic vibrations on a two-stage path of thermodynamic integration between the original DFT quasiharmonic free energy and the fully anharmonic DFT free energy. This approach greatly accelerates the convergence of the calculation, giving a factor of improvement in efficiency of ˜50 in the present case compared to the original UP-TILD approach, and it can be applied to a wide range of materials.
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.
NASA Astrophysics Data System (ADS)
Zhang, Wei; Chen, Qing Yun; Li, Bin; Zeng, Zhao Yi; Cai, Ling Cang
2015-09-01
The ground state properties of the silicon clathrate Si46 intercalated by alkali metal sodium atoms (Na8Si46) are investigated by first-principle methods. Birch-Murnaghan equation of state is fitted to two sets of the E-V data calculated by density functional theory based on the plane-wave basis set within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Through quasi-harmonic Debye model, some thermodynamic properties comprise the heat capacity, the thermal expansion coefficient, Debye temperature and the Grüneisen parameter for this clathrate compounds Na8Si46 are obtained, which agree well with experimental results. Comparing the calculated heat specific in two ways with experimental results, we find that it is more accurate to describe the “rattle” modes of gust Na atoms in the cages as Einstein oscillators. Moreover, the effects of high pressure on these thermodynamic properties are also investigated which will be very helpful for a synthesis of these clathrate compounds in experiments under high pressure and high temperature condition.
NASA Astrophysics Data System (ADS)
Wei, Ning; Zhang, Xiaoli; Zhang, Chuanguo; Hou, Songjun; Zeng, Z.
2015-10-01
We have investigated the elastic and thermodynamic properties of ZrO2 under pressure up to 120 Gpa by the plane wave pseudopotential density functional theory with the generalized gradient approximation (GGA) method. The elastic constants of ZrO2 are calculated and meet the generalized stability criteria, suggesting that ZrO2 is mechanically stable within this pressure range. The pressure effects on the elastic properties reveal that the elastic modulus B, shear modulus G and Young's modulus Y increase linearly with the pressure increasing, implying that the resistance to deformation is enhanced. In addition, by analyzing the Poisson's ratio Î½ and the value of B/G, we notice that ZrO2 is regarded as being a ductile material under high pressure and the ductility can be improved by the pressure increasing. Then, we employ the quasi-harmonic Debye model considering the phononic effects to obtain the thermodynamic properties of ZrO2. Debye temperature Î˜D, thermal expansion coefficient Î±, heat capacity Cp and GrÃ¼neisen parameter Î³ are systematically explored at pressure of 0-80 Gpa and temperature of 0-1000 K. Our results have provided fundamental facts and evidences for further experimental and theoretical researches.
Nagashima, H; Tsuda, S; Tsuboi, N; Koshi, M; Hayashi, K A; Tokumasu, T
2014-04-01
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. PMID:24712800
NASA Astrophysics Data System (ADS)
Nagashima, H.; Tsuda, S.; Tsuboi, N.; Koshi, M.; Hayashi, K. A.; Tokumasu, T.
2014-04-01
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.
NASA Astrophysics Data System (ADS)
Bernazzani, Paul; Delmas, Genevieve
1998-03-01
Amylose, a major component of starch, is one of the most important biopolymers, being mainly associated with the pharmacological and food industries. Although widely studied, a complete control and understanding of the physical properties of amylose is still lacking. It is well known that structure and phase transition are important aspects of the functionality of biopolymers since they influence physical attributes such as appearance, digestibility, water holding capacity, etc. In the past, we have studied polyethylene phase composition by DSC in a very slow temperature (T) ramp (1K/h) and have demonstrated the presence and importance of short-range order on the polymer and its characteristics. In this study, we evaluated the phase composition of potato amylose and associated the thermodynamic properties with the presence of short-range order. Two methods were correlated, DSC (in a 1K/h T-ramp) and FTIR as a function of temperature, also in a 1K/h T-ramp. The effects of the various phases on thermodynamic properties such as gelation and enzyme or chemical resistance are discussed.
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.
Nagashima, H.; Tsuda, S.; Tsuboi, N.; Koshi, M.; Hayashi, K. A.; Tokumasu, T.
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 densityâ€“temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressureâ€“volumeâ€“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.
NASA Astrophysics Data System (ADS)
Liu, Yong; Hu, Wen-Cheng; Li, De-Jiang; Zeng, Xiao-Qin; Xu, Chun-Shui
2014-04-01
The structural and thermodynamic properties of MgZn2 Laves phase under hydrostatic pressure have been investigated by using a first-principles method based on the density functional theory within the generalized gradient approximation. The calculated equilibrium structural parameters are consistent with the previous experimental and theoretical data. Especially, we study the pressure dependence of the elastic constants, polycrystalline elastic moduli, Poisson's ratio, elastic anisotropy, and theoretical Vickers hardness of MgZn2. It is found that the pressure plays a significant role in the elastic properties of MgZn2 due to the variations of inter-atomic distance. In addition, the density of states and Mulliken analysis are performed to reveal the bonding characteristics of MgZn2. It is observed that the total density of states exhibits a certain offset with the increase of external pressure. Finally, the dependences of thermodynamic properties on pressure and temperature of MgZn2 Laves phase have been also successfully predicted and analyzed within the quasi-harmonic Debye model for the first time.
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.
Equation of State for the Thermodynamic Properties of 1,1,2,2,3-Pentafluoropropane (R-245ca)
NASA Astrophysics Data System (ADS)
Zhou, Yong; Lemmon, Eric W.
2016-03-01
An equation of state for the calculation of the thermodynamic properties of 1,1,2,2,3-pentafluoropropane (R-245ca), which is a hydrofluorocarbon refrigerant, is presented. The equation of state (EOS) is expressed in terms of the Helmholtz energy as a function of temperature and density, and can calculate all thermodynamic properties through the use of derivatives of the Helmholtz energy. The equation is valid for all liquid, vapor, and supercritical states of the fluid, and is valid from the triple point to 450 K, with pressures up to 10 MPa. Comparisons to experimental data are given to verify the stated uncertainties in the EOS. The estimated uncertainty for density is 0.1 % in the liquid phase between 243 K and 373 K with pressures up to 6.5 MPa; the uncertainties increase outside this range, and are unknown. The uncertainty in vapor-phase speed of sound is 0.1 %. The uncertainty in vapor pressure is 0.2 % between 270 K and 393 K. The uncertainties in other regions and properties are unknown due to a lack of experimental data.
NASA Astrophysics Data System (ADS)
Gering, Kevin Leslie
A molecular formulation based on modern liquid state theory is applied to the properties and phase behavior of electrolyte systems containing volatile species. An electrolyte model based on the exponential modification of the Mean Spherical Approximation (EXP-MSA) is used to describe the cation-cation, cation-anion, and anion-anion distributions of the ionic species. This theory represents an improvement over the nonmodified MSA approach, and goes beyond the usual Debye-Huckel theory and Pitzer correlation for treating concentrated solutions. Electrolyte solutions such as water-salt, ammonia-salt, mixed salts, and mixed -solvent systems are investigated over a wide range of temperatures, pressures, and compositions. The usual salt properties, such as osmotic and mean activity coefficients and other thermodynamic properties (enthalpies), are calculated. The predictions are accurate to saturation limits. In addition, an iterative method is presented that is used to predict vapor-liquid equilibria (VLE) and thermodynamic properties of single-salt multisolvent electrolytes of the form solvent-cosolvent-salt. In this method, a local composition model (LCM) and EXP-MSA theory are combined with traditional phase equilibria relations to estimate the pressures and compositions of a vapor phase in equilibrium with a binary-solvent electrolyte. Also, a pseudo-solvent model is proposed as a means of obtaining a variety of averaged liquid phase electrolyte properties. To predict preferential solvation in mixed solvents, a general framework is developed that is based on predicted solvation numbers of each solvent. Preferential solvation will be shown to influence VLE. Results show that phase equilibria is accurately predicted by the above iterative method. Three mixed-solvent electrolyte systems are investigated: water -ethylene glycol-LiBr, ammonia-water-LiBr, and methanol -water-LiCl. Finally, the above electrolyte model is utilized in predicting design criteria for a single-effect absorption cooling cycle.
Wang, Han; Nakamura, Haruki; Fukuda, Ikuo
2016-03-21
We performed extensive and strict tests for the reliability of the zero-multipole (summation) method (ZMM), which is a method for estimating the electrostatic interactions among charged particles in a classical physical system, by investigating a set of various physical quantities. This set covers a broad range of water properties, including the thermodynamic properties (pressure, excess chemical potential, constant volume/pressure heat capacity, isothermal compressibility, and thermal expansion coefficient), dielectric properties (dielectric constant and Kirkwood-G factor), dynamical properties (diffusion constant and viscosity), and the structural property (radial distribution function). We selected a bulk water system, the most important solvent, and applied the widely used TIP3P model to this test. In result, the ZMM works well for almost all cases, compared with the smooth particle mesh Ewald (SPME) method that was carefully optimized. In particular, at cut-off radius of 1.2 nm, the recommended choices of ZMM parameters for the TIP3P system are Î± â‰¤ 1 nm(-1) for the splitting parameter and l = 2 or l = 3 for the order of the multipole moment. We discussed the origin of the deviations of the ZMM and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and SPME, while the magnitude of the density deviations is very small. PMID:27004883
Bertoli, Alexandre C; Garcia, Jerusa S; Trevisan, Marcello G; Ramalho, Teodorico C; Freitas, Matheus P
2016-04-01
The use of theoretical calculation to determine structural properties of fulvate-metal complex (zinc, copper and iron) is here related. The species were proposed in the ratio 1:1 and 2:1 for which the molecular structure was obtained through the semi-empirical method PM6. The calculation of thermodynamic stability ([Formula: see text]) predicted that the iron complex were more exo-energetic. Metallic ions were coordinated to the phtalate groups of the model-structure of fulvic acid Suwannee River and the calculations of vibrational frequencies suggested that hydrogen bonds may help on the stability of the complex formation. PMID:26857737
Thermodynamic properties of carbon in b.c.c. and f.c.c. iron-silicon-carbon solid solutions.
NASA Technical Reports Server (NTRS)
Chraska, P.; Mclellan, R. B.
1971-01-01
The equilibrium between hydrogen-methane gas mixtures and Fe-Si-C solid solutions has been investigated both as a function of temperature and carburizing gas composition. The thermodynamic properties of the carbon atoms in both b.c.c. and f.c.c. solid solution have been derived from the equilibrium measurements. The results found have been compared with those of earlier investigations and with the predictions of recent theoretical models on ternary solid solutions containing both substitutional and interstitial solute atoms.
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.
NASA Astrophysics Data System (ADS)
Wang, Xiao-Dan; Han, Chun; Fan, Hong-Tao
2015-07-01
Task-specific ionic liquid 1-butyl-3-methylimidazolium salicylate ([BMI]Sal) was synthesized in two steps. In the temperature range of 298.15-353.15 K, the density and surface tension for pure ionic liquid were determined and the thermodynamic properties of the ionic liquid were discussed in terms of Glasser's theory. The standard molar entropy and lattice energy for [BMI]Sal have been estimated. In addition, the thermal expansion coefficient, ? = 5.53 × 10-4 K-1, calculated by the interstice model is in extreme agreement with ? (experimental) = 5.50 × 10-4 K-1.
NASA Astrophysics Data System (ADS)
Chakravorty, Susmita; Lee, Julia C.; Neilsen, Joseph
2013-11-01
We present a systematic theory-motivated study of the thermodynamic stability condition as an explanation for the observed accretion disc wind signatures in different states of low-mass black hole binaries (BHB). The variability in observed ions is conventionally explained either by variations in the driving mechanisms or by the changes in the ionizing flux or due to density effects, whilst thermodynamic stability considerations have been largely ignored. It would appear that the observability of particular ions in different BHB states can be accounted for through simple thermodynamic considerations in the static limit. Our calculations predict that in the disc-dominated soft thermal and intermediate states, the wind should be thermodynamically stable and hence observable. On the other hand, in the power-law-dominated spectrally hard state the wind is found to be thermodynamically unstable for a certain range of 3.55 ? log ? ? 4.20. In the spectrally hard state, a large number of the He-like and H-like ions (including e.g. Fe XXV, Ar XVIII and S XV) have peak ion fractions in the unstable ionization parameter (?) range, making these ions undetectable. Our theoretical predictions have clear corroboration in the literature reporting differences in wind ion observability as the BHBs transition through the accretion states While this effect may not be the only one responsible for the observed gradient in the wind properties as a function of the accretion state in BHBs, it is clear that its inclusion in the calculations is crucial for understanding the link between the environment of the compact object and its accretion processes.
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.
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
NASA Technical Reports Server (NTRS)
Thompson, R. A.
1994-01-01
EQAIRS is a set of FORTRAN 77 routines for computing the thermodynamic and transport properties of equilibrium air for temperatures from 100 to 30000 K. EQAIRS computes these properties over a pressure range of 1.0e-4 to 1.0e2 atm. The properties computed include enthalpy, total specific heat, compressibility factor, viscosity, and the total values of thermal conductivity and Prandtl number. The various properties are calculated through the use of temperature dependent curve-fits for the pressure range given above. The curve fits are based on mixture values calculated from an 11-species air model. Individual species properties used in the mixture relations were obtained from a recent study by the program authors. It is desirable to have these equilibrium air properties computed by curve-fits as opposed to tabulated values because curve-fits generally permit more efficient computation for flow-field analyses. In addition, for accurate calculations, it is preferable that the thermodynamic and transport properties be computed in a self-consistent manner from the same set of data as in the present case. The EQAIRS routines were written in the form of FORTRAN subroutines for easy adaptation to existing programs. The subroutines are commented and can be easily modified to suit the user's needs. In an attempt to maintain generality, a total of six separate subroutines are available for use: 1) ENTHLPY (specific enthalpy); 2) SPECIFC (total specific heat at constant pressure); 3) COMPRES (compressibility factor); 4) VISCSTY (viscosity); 5) CONDUCT (total thermal conductivity; and 6) PRANDTL (total Prandtl number). EQAIRS has been successfully implemented on a DEC VAX series computer running VMS, a Sun4 series computer running SunOS, and an IBM PC compatible computer running MS-DOS. Sample input/output and a sample driver program are provided. The standard distribution medium for EQAIRS is one 5.25 inch 360K MS-DOS format diskette. This program is also available on a .25 inch streaming magnetic tape cartridge in UNIX tar format. EQAIRS was developed in 1991.
NASA Astrophysics Data System (ADS)
Woolley, H. W.
1983-03-01
A study is presented of the still-unsolved problem of estimating thermodynamic property values in a region intermediate between the critical region in which the scaling laws apply, and regions further from critical, where classical behavior prevails. A procedure has been developed in which a varying weighting function is used in obtaining a weighted “average” of the scaled and the classical Helmholtz free energy. Other properties are then obtained by differentiation. It is first demonstrated that it is fundamentally impossible for the “averaged” Helmholtz free energy and its first two derivatives to all be intermediate between the corresponding values from the scaled and the classical formulations. The procedure has been developed and tested for steam. The scaled function is the simple linear model of Murphy et al., the classical equation that of Pollak. The properties of power-weighted switch functions, particularly with respect to the behavior of higher-order derivatives, and the choice of the boundaries of the switching region, were examined in detail and optimized by proper choice of parameters. It is shown that a reasonably smooth transfer from the scaled to the classical region can be achieved as far as free energy, energy, and specific heat C V are concerned. For satisfactory behavior of all second derivative properties, the two formulations need to be more compatible in the switching region than they are in the present case.
NASA Technical Reports Server (NTRS)
Langhoff, Stephen; Bauschlicher, Charles; Jaffe, Richard
1992-01-01
One of the primary goals of NASA's high-speed research program is to determine the feasibility of designing an environmentally safe commercial supersonic transport airplane. The largest environmental concern is focused on the amount of ozone destroying nitrogen oxides (NO(x)) that would be injected into the lower stratosphere during the cruise portion of the flight. The limitations placed on NO(x) emission require more than an order of magnitude reduction over current engine designs. To develop strategies to meet this goal requires first gaining a fundamental understanding of the combustion chemistry. To accurately model the combustor requires a computational fluid dynamics approach that includes both turbulence and chemistry. Since many of the important chemical processes in this regime involve highly reactive radicals, an experimental determination of the required thermodynamic data and rate constants is often very difficult. Unlike experimental approaches, theoretical methods are as applicable to highly reactive species as stable ones. Also our approximation of treating the dynamics classically becomes more accurate with increasing temperature. In this article we review recent progress in generating thermodynamic properties and rate constants that are required to understand NO(x) formation in the combustion process. We also describe our one-dimensional modeling efforts to validate an NH3 combustion reaction mechanism. We have been working in collaboration with researchers at LeRC, to ensure that our theoretical work is focused on the most important thermodynamic quantities and rate constants required in the chemical data base.
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)
Fisenko, Anatoliy I.; Lemberg, Vladimir
2015-11-01
There are several classes of materials and space objects for which the frequency dependence of the spectral emissivity is represented as a power series. Therefore, the study of the properties of thermal radiation for these real bodies is an important task for both fundamental science and industrial applications. The general analytical expressions for the thermal radiative and thermodynamic functions of a real body are obtained in a finite range of frequencies at different temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and total emissivity are expressed in terms of the polylogarithm functions. The obtained general expressions for the thermal radiative and thermodynamic functions are applied for the study of thermal radiation of liquid and solid zirconium carbide. These functions are calculated using experimental data for the frequency dependence of the normal spectral emissivity in the visible and near-infrared range at the melting (freezing) point. The gaps between the thermal radiative and thermodynamic functions of liquid and solid zirconium carbide are observed. The general analytical expressions obtained can easily be presented in the wavenumber domain.
NASA Astrophysics Data System (ADS)
Morrison, J. D.; Barley, M. H.; Murphy, F. T.; Parker, I. B.; Wheelhouse, R. W.
1995-09-01
This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.
NASA Astrophysics Data System (ADS)
GÃ³mez-MarÃn, Ana M.; Feliu, Juan M.
2016-04-01
In this work, the effect of temperature on the adsorption states of Pt(111) vicinal surface electrodes in perchloric acid is studied through a thermodynamic analysis. The method allows calculating thermodynamic properties of the interface. In this framework, the concept of the generalized isotherm and the statistical thermodynamics description are applied to calculate formal entropies, enthalpies and Gibbs energies, Î”Gbari0, of the adsorption processes at two-dimensional terraces and one-dimensional steps. These values are compared with data from literature. Additionally, the effect of the step density on Î”Gbari0 and on the lateral interactions between adsorbed species, Ï‰ij, at terraces and steps is also determined. Calculated Î”Gbari0, entropies and enthalpies are almost temperature-independent, especially at steps, but they depend on the step orientation. In contrast, Î”Gbari0 and Ï‰ij at terraces depend on the step density, following a linear tendency for terrace lengths larger than 5 atoms. However, while Î”Gbari0 increases with the step density, Ï‰ij decreases. Results were explained by considering the modification in the energetic surface balance by hydrogen, Hads, and water, H2Oads, co-adsorption on the electrode, which in turn determines the whole adsorption processes on terraces and steps.
Thermodynamic properties of PbTe, PbSe, and PbS: a ?rst-principles study
Zhang, Yi; Ke, Xuezhi; Chen, Changfeng; Yang, Jihui; Kent, Paul R
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.
Canneaux, Sébastien; Bohr, Frédéric; Henon, Eric
2014-01-01
Kinetic and Statistical Thermodynamical Package (KiSThelP) is a cross-platform free open-source program developed to estimate molecular and reaction properties from electronic structure data. To date, three computational chemistry software formats are supported (Gaussian, GAMESS, and NWChem). Some key features are: gas-phase molecular thermodynamic properties (offering hindered rotor treatment), thermal equilibrium constants, transition state theory rate coefficients (transition state theory (TST), variational transition state theory (VTST)) including one-dimensional (1D) tunnelling effects (Wigner, and Eckart) and Rice-Ramsperger-Kassel-Marcus (RRKM) rate constants, for elementary reactions with well-defined barriers. KiSThelP is intended as a working tool both for the general public and also for more expert users. It provides graphical front-end capabilities designed to facilitate calculations and interpreting results. KiSThelP enables to change input data and simulation parameters directly through the graphical user interface and to visually probe how it affects results. Users can access results in the form of graphs and tables. The graphical tool offers customizing of 2D plots, exporting images and data files. These features make this program also well-suited to support and enhance students learning and can serve as a very attractive courseware, taking the teaching content directly from results in molecular and kinetic modelling. PMID:24190715
NASA Technical Reports Server (NTRS)
Sutton, K.
1981-01-01
Thermodynamic and transport properties of gaseous CF4 that can be used in flow field computer codes and theoretical analyses for comparison of results with experimental data from the Langley Hypersonic CF4 Tunnel are presented. The thermodynamic relations which are based on thermally perfect but calorifically imperfect gas are adequate for the testing environment of the CF4 tunnel and are simpler to use than the imperfect gas relations required to define the complete expansion from the tunnel reservoir. Relations for the transport properties are based on the kinetic theory of gases in which published experimental data are used in the derivation of the relations. Extensive experimental data were located for viscosity and the derived relation should provide values for viscosity with errors of less than 1 percent. The experimental data for thermal conductivity were limited with significant disagreement between the various sources. The derived relation will probably provide values for the thermal conductivity with errors of no more than 5 percent which is within the accuracy of the experimental data.
Lead-free solder alloys: Thermodynamic properties of the (Au + Sb + Sn) and the (Au + Sb) system
Hindler, Michael; Guo, Zhongnan; Mikula, Adolf
2012-01-01
The thermodynamic properties of liquid (Au–Sb–Sn) alloys were studied with an electromotive force (EMF) method using the eutectic mixture of KCl/LiCl with addition of SnCl2 as a liquid electrolyte. Activities of Sn in the liquid alloys were measured at three cross-sections with constant molar ratios of Au:Sb = 2:1, 1:1, and 1:2 with tin in the concentration range between 5 at.% and 90 at.% from the liquidus of the samples up to 1073 K. The integral Gibbs excess energies and the integral enthalpies at 873 K were calculated by Gibbs–Duhem integration. Additionally liquid Au–Sb alloys have been measured at 913 K with the EMF method as no reliable data for the Gibbs excess energies have been found in literature. The eutectic mixture of KCl/LiCl with addition of SbCl3 has been used as an electrolyte for the measurements. The Gibbs excess energies from the (Au + Sb) system were necessary for the integration of the thermodynamic properties of the ternary (Au + Sb + Sn) system. PMID:24926101
Djamali, Essmaiil; Cobble, James W
2009-08-01
Standard state thermodynamic properties for completely dissociated hydrochloric acid were fixed by ionic additivity, using the data from other strong electrolytes perrhenic acid, sodium perrhenate, and sodium chloride from 298.15 to 598.15 K and at p(sat). The standard electrode potential for the important silver-silver chloride electrode system and the equilibrium constants for the volatility of HCl from aqueous solutions were then calculated and compared with literature data. Using the experimental data from this study and auxiliary data from literature, the logarithm of the molal association constant of HCl at the critical temperature of water and at 673.15 K up to 1000 MPa was predicted from the unified theory of electrolytes (UTE). The standard state thermodynamic properties for completely dissociated aqueous sodium hydroxide were also calculated by ionic additivity over the same temperature range from aqueous sodium chloride, hydrochloric acid, and the dissociation constant of water. The results were compared with literature data. PMID:19606908
Djamali, Essmaiil; Chen, Keith; Cobble, James W
2009-08-27
Pabalan and Pitzer (Geochim. Cosmochim. Acta 1988, 52, 2393-2404) reported a comprehensive set of thermodynamic properties of aqueous solutions of sodium sulfate without using ion association or hydrolysis. However, there is now ample evidence available indicating that the ion association cannot be ignored at temperatures T>or=373 K. For example, even at the lowest concentration of their studies (m>or=0.05) and at 573.15 K, less than 20% of SO4(2-)(aq) is available as free ions. In the present study, the integral heats of solution of sodium sulfate were measured to very low concentrations (10(-4) m) up to 573.16 K. The data were analyzed correcting for the hydrolysis of SO4(2-)(aq) and the association of Na+(aq) with SO4(2-)(aq) and NaSO4-(aq) in order to obtain the final standard state thermodynamic properties of completely ionized aqueous sodium sulfate, Na2SO4(aq). From these and the available solubility data, the stoichiometric activity coefficients of saturated aqueous solutions of sodium sulfate were calculated up to 573.15 K and compared with literature data. The stoichiometric activity coefficients of aqueous solutions of sodium sulfate, as a function of temperature at all concentrations (0
Equation of State for the Thermodynamic Properties of trans-1,3,3,3-Tetrafluoropropene [R-1234ze(E)
NASA Astrophysics Data System (ADS)
Thol, Monika; Lemmon, Eric W.
2016-03-01
An equation of state for the calculation of the thermodynamic properties of the hydrofluoroolefin refrigerant R-1234ze(E) is presented. The equation of state (EOS) is expressed in terms of the Helmholtz energy as a function of temperature and density. The formulation can be used for the calculation of all thermodynamic properties through the use of derivatives of the Helmholtz energy. Comparisons to experimental data are given to establish the uncertainty of the EOS. The equation of state is valid from the triple point (169 K) to 420 K, with pressures to 100 MPa. The uncertainty in density in the liquid and vapor phases is 0.1 % from 200 K to 420 K at all pressures. The uncertainty increases outside of this temperature region and in the critical region. In the gaseous phase, speeds of sound can be calculated with an uncertainty of 0.05 %. In the liquid phase, the uncertainty in speed of sound increases to 0.1 %. The estimated uncertainty for liquid heat capacities is 5 %. The uncertainty in vapor pressure is 0.1 %.
NASA Astrophysics Data System (ADS)
Dallaire-Demers, Pierre-Luc; Wilhelm, Frank K.
2016-03-01
Many phenomena of strongly correlated materials are encapsulated in the Fermi-Hubbard model whose thermodynamic properties can be computed from its grand-canonical potential. In general, there is no closed-form expression of the grand-canonical potential for lattices of more than one spatial dimension, but solutions can be numerically approximated using cluster methods. To model long-range effects such as order parameters, a powerful method to compute the cluster's Green's function consists of finding its self-energy through a variational principle. This allows the possibility of studying various phase transitions at finite temperature in the Fermi-Hubbard model. However, a classical cluster solver quickly hits an exponential wall in the memory (or computation time) required to store the computation variables. Here it is shown theoretically that the cluster solver can be mapped to a subroutine on a quantum computer whose quantum memory usage scales linearly with the number of orbitals in the simulated cluster and the number of measurements scales quadratically. A quantum computer with a few tens of qubits could therefore simulate the thermodynamic properties of complex fermionic lattices inaccessible to classical supercomputers.
NASA Astrophysics Data System (ADS)
Wei, Yong-Kai; Ge, Ni-Na; Ji, Guang-Fu; Chen, Xiang-Rong; Cai, Ling-Cang; Zhou, Su-Qin; Wei, Dong-Qing
2013-09-01
The lattice dynamic, elastic, superconducting, and thermodynamic properties of the high-pressure cubic metallic phase AlH3 are studied within density function theory. The calculated elastic modulus and phonon dispersion curves at various pressures indicate that the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature was calculated using Allen-Dynes modification of the McMillan formula based on the Bardeen-Cooper-Schrieffer theory. It is found that Tc approaches a linear decrease in the low pressure range at the rate dTC/dP â‰ˆ-0.22 K/GPa but gradually decreases exponentially at higher pressure, and then it becomes 0 K upon further compression. The calculations indicate that Tc is about 2.042 K at 110 GPa, in agreement with experimental results. The soft phonon modes, especially the lowest acoustic mode, contribute almost 79% to the total electron-phonon coupling parameter sÎ» for cubic AlH3 at 73 GPa. However, they disappear gradually with increasing pressure, showing a responsibility for the variation of Tc. The thermodynamic properties of cubic AlH3, such as the dependence of thermal expansion coefficient Î±V on pressure and temperature, the specific heat capacity CP, as well as the electronic specific heat coefficient Cel, were also investigated by the quasi-harmonic approximation theory.
NASA Astrophysics Data System (ADS)
Li, L. H.; Hu, L.; Yang, S. J.; Wang, W. L.; Wei, B.
2016-01-01
The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni7Zr2 alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni7Zr2 has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni7Zr2 alloy fitted by Vogel-Fulcher-Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni7Zr2 compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s-1 at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s-1.
Lead-free solder alloys: Thermodynamic properties of the (Au + Sb + Sn) and the (Au + Sb) system.
Hindler, Michael; Guo, Zhongnan; Mikula, Adolf
2012-12-01
The thermodynamic properties of liquid (Au-Sb-Sn) alloys were studied with an electromotive force (EMF) method using the eutectic mixture of KCl/LiCl with addition of SnCl2 as a liquid electrolyte. Activities of Sn in the liquid alloys were measured at three cross-sections with constant molar ratios of Au:Sb = 2:1, 1:1, and 1:2 with tin in the concentration range between 5 at.% and 90 at.% from the liquidus of the samples up to 1073 K. The integral Gibbs excess energies and the integral enthalpies at 873 K were calculated by Gibbs-Duhem integration. Additionally liquid Au-Sb alloys have been measured at 913 K with the EMF method as no reliable data for the Gibbs excess energies have been found in literature. The eutectic mixture of KCl/LiCl with addition of SbCl3 has been used as an electrolyte for the measurements. The Gibbs excess energies from the (Au + Sb) system were necessary for the integration of the thermodynamic properties of the ternary (Au + Sb + Sn) system. PMID:24926101
Proscia, W.M.; Freihaut, J.D.
1992-11-01
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.
Proscia, W.M.; Freihaut, J.D.
1994-06-01
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 decompose ion of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Progress reports are presented for the following tasks: heat of devoltalization of voltaile coal samples; specific heat and heat of fusion of tars; heat of vaporization of tars from rapid heating; and morphological characterization of coal/char samples as a function of extent of devoltalization.
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.
NASA Astrophysics Data System (ADS)
Li, Zhen-Li; Cheng, Xin-Lu
2014-04-01
First-principles calculations are used to investigate the mechanical and thermodynamic properties of cubic YH2 at different pressures and temperatures. The generalized gradient approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) method is used to describe the exchange-correlation energy in the present work. The calculated equilibrium lattice constant a and bulk modulus B are in good accordance with the available experimental values. According to the Born-Huang criteria for mechanical stability, elastic constants are calculated from the strain-induced stress method in a pressure range from 0 to 67.1 GPa. Isotropic wave velocities and sound velocities are discussed in detail. It is found that the Debye temperature decreases monotonically with the increase of pressure and that YH2 has low anisotropy in both longitudinal and shear-wave velocities. The calculated elastic anisotropic factors indicate that YH2 has low anisotropy at zero pressure and that its elastic anisotropy increases as pressure increases. Through the quasi-harmonic Debye model, in which phononic effects are considered, the thermodynamic properties of YH2, such as the relations of (V-V0)/V0 to the temperature and the pressure, the dependences of heat capacity Cv and thermal expansion coefficient ? on temperature and pressure ranging from 0 to 2400 K and from 0 to 65 GPa, respectively, are also discussed.
NASA Astrophysics Data System (ADS)
Tseng, Huan-Chang; Chang, Rong-Yeu; Wu, Jiann-Shing
2011-01-01
Extensive computer experiments have been conducted in order to shed light on the macroscopic shear flow behavior of liquid n-hexadecane fluid under isobaric-isothermal conditions through the nonequilibrium molecular dynamic methodology. With respect to shear rates, the accompanying variations in structural properties of the fluid span the microscopic range of understanding from the intrinsic to extrinsic characteristics. As drawn from the average value of bond length and bond angle, the distribution of dihedral angle, and the radius distribution function of intramolecular and intermolecular van der Waals distances, these intrinsic structures change with hardness, except in the situation of extreme shear rates. The shear-induced variation of thermodynamic state curve along with the shear rate studied is shown to consist of both the quasiequilibrium state plateau and the nonequilibrium-thermodynamic state slope. Significantly, the occurrence of nonequilibrium-thermodynamic state behavior is attributed to variations in molecular potential energies, which include bond stretching, bond bending, bond torsion, and intra- and intermolecular van der Waals interactions. To unfold the physical representation of extrinsic structural deformation, under the aggressive influence of a shear flow field, the molecular dimension and appearance can be directly described via the squared radius of gyration and the sphericity angle, Rg2 and ?, respectively. In addition, a specific orientational order Sx defines the alignment of the molecules with the flow direction of the x-axis. As a result, at low shear rates, the overall molecules are slightly stretched and shaped in a manner that is increasingly ellipsoidal. Simultaneously, there is an obvious enhancement in the order. In contrast to high shear rates, the molecules spontaneously shrink themselves with a decreased value of Rg2, while their shape and order barely vary with an infinite value of ? and Sx. It is important to note that under different temperatures and pressures, these three parameters are integrated within a molecular description in response to thermodynamic state variable of density and rheological material function of shear viscosity.
Thermodynamic properties of alloys of the binary Gd-In system
NASA Astrophysics Data System (ADS)
Shevchenko, M. A.; Ivanov, M. I.; Berezutski, V. V.; Sudavtsova, V. S.
2016-01-01
The thermochemical properties of melts of the binary Gd-In system were studied by the calorimetry method at 1470-1700 K over the whole concentration interval. It was shown that significant negative heat effects of mixing are characteristic features for these melts. Using the ideal associated solution (IAS) model, the activities of components, Gibbs energies and the entropies of mixing in the alloys of this systems and its phase diagram were calculated. They agree with the data from literature.
Structural, thermodynamic, mechanical, and magnetic properties of FeW system
Ren, Q. Q.; Fan, J. L.; Han, Y.; Gong, H. R.
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 Î»-Fe{sub 2}W and Î¼-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 Eâ€‰>â€‰Gâ€‰>â€‰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.
Eriksson, Jan Christer; Henriksson, Ulf
2013-04-16
In the course of a long-term effort to cope with surface force data for thin films of water between hydrophobic surfaces, we have applied the bridging-cluster model (Eriksson, J. C.; Henriksson, U. Bridging-cluster model for hydrophobic attraction . Langmuir 2007, 23, 10026 - 10033) to the recently published surface force isotherms for water films between hexadecylthiolated gold surfaces in the thickness range of 20-100 nm and temperature range of 10-40 °C (Wang, J.; Yoon, R.-H.; Eriksson, J. C. Excess thermodynamic properties of thin water films confined between hydrophobized gold surfaces. J. Colloid Interface Sci. 2011, 364, 257 - 263). We show that these isotherms can be faithfully reproduced on the basis of the bridging-cluster model. The thermodynamic excess properties (?Gc?, ?Hc?, and T?Sc) of linear clusters that are assumed to bridge the core of the films were calculated from the experimental surface force isotherms. A crucial step taken was to infer two-dimensional ideal mixing of the clusters with the surrounding film water. We find that ?Hc and T?Sc are both negative quantities, with the latter being larger than the former, which implies a positive excess Gibbs energy of a cluster, ?Gc = ?Hc - T?Sc. Typically, for temperatures between 10 and 40 °C, these cluster properties are of the order of some kBT units, corresponding to 10(-4)-10(-3)kBT per water molecule entailed. Our analysis yields support of the notion that elongated aggregates can arise in thin films of water between hydrophobic surfaces driven by entropy of mixing. PMID:23521404
NASA Astrophysics Data System (ADS)
Chelli, S.; Meradji, H.; Amara Korba, S.; Ghemid, S.; El Haj Hassan, F.
2014-12-01
The structural, electronic thermodynamic and thermal properties of BaxSr1-xTe ternary mixed crystals have been studied using the ab initio full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). In this approach, the Perdew-Burke-Ernzerhof-generalized gradient approximation (PBE-GGA) was used for the exchange-correlation potential. Moreover, the recently proposed modified Becke Johnson (mBJ) potential approximation, which successfully corrects the band-gap problem was also used for band structure calculations. The ground-state properties are determined for the cubic bulk materials BaTe, SrTe and their mixed crystals at various concentrations (x = 0.25, 0.5 and 0.75). The effect of composition on lattice constant, bulk modulus and band gap was analyzed. Deviation of the lattice constant from Vegard's law and the bulk modulus from linear concentration dependence (LCD) were observed for the ternary BaxSr1-xTe alloys. The microscopic origins of the gap bowing were explained by using the approach of Zunger and co-workers. On the other hand, the thermodynamic stability of these alloys was investigated by calculating the excess enthalpy of mixing, ?Hm as well as the phase diagram. It was shown that these alloys are stable at high temperature. Thermal effects on some macroscopic properties of BaxSr1-xTe alloys were investigated using the quasi-harmonic Debye model, in which the phononic effects are considered.
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.
NASA Astrophysics Data System (ADS)
Liu, Lei; Bi, Yan; Xu, Jian; Chen, Xiangrong
2013-03-01
Tungsten monocarbide (WC) exhibits unique physical and chemical properties. It is an indispensable industrial material used as cutting tools and has many potential applications in catalyst, energy storage, and so on. We performed calculations of the electronic structure in the framework of the density functional theory (DFT) with generalized gradient approximation (GGA) to investigate structural and elastic properties of WC. Bulk WC is very incompressible, but its bulk modulus is still smaller than diamond though Lin et al. reported that nano-crystalline WC was as incompressible as diamond. WC undergoes different compressibilities along a and c directions: the a-axis is more compressible than the c-axis. The ratio of shear modulus to bulk modulus (G/B) was studied and it was found that WC translated from the brittle to ductile state at ?63 GPa. In order to compare with the EOS determined at finite temperature, the vibration effects of the crystal lattice are taken into account based on quasi-harmonic Debye model. The temperature effect on bulk modulus is discussed and the thermodynamic properties of WC, such as heat capacity CV, Debye temperature ?D, and thermal expansion ?, are calculated simultaneously.
NASA Astrophysics Data System (ADS)
Gao, Cheng; Zeng, Jiaolong; Li, Yongqiang; Jin, Fengtao; Yuan, Jianmin
2013-09-01
A versatile code DLAYZ based on collisional-radiative model is developed for investigating the population kinetics and radiative properties of plasmas in non-local thermodynamic equilibrium. DLAYZ is implemented on the detailed level accounting (DLA) approach and can be extended to detailed configuration accounting (DCA) and hybrid DLA/DCA approaches. The code can treat both steady state and time-dependent problems. The implementation of the main modules of DLAYZ is discussed in detail including atomic data, rates, population distributions and radiative properties modules. The complete set of basic atomic data is obtained using relativistic quantum mechanics. For dense plasmas, the basic atomic data with plasma screening effects can be obtained. The populations are obtained by solving the coupled rate equations, which are used to calculate the radiative properties. A parallelized version is implemented in the code to treat the large-scale rate equations. Two illustrative examples of a steady state case for carbon plasmas and a time-dependent case for the relaxation of a K-shell excited argon are employed to show the main features of the present code.
Dong, Bing; Zhou, Xiao-Lin E-mail: lkworld@126.com; Chang, Jing; Liu, Ke E-mail: lkworld@126.com
2014-08-07
The structural and elastic properties of RuN{sub 2} were investigated through the first-principles calculation using generalized gradient approximation (GGA) and local density approximation (LDA) within the plane-wave pseudopotential density functional theory. The obtained equilibrium structure and mechanical properties are in excellent agreement with other theoretical results. Then we compared the elastic modulus of RuN{sub 2} with several other isomorphic noble metal nitrides. Results show that RuN{sub 2} can nearly rival with OsN{sub 2} and IrN{sub 2}, which indicate RuN{sub 2} is a potentially ultra-incompressible and hard material. By the elastic stability criteria, it is predicted that RuN{sub 2} is stable in our calculations (0–100?GPa). The calculated B/G ratios indicate that RuN{sub 2} possesses brittle nature at 0?GPa and when the pressure increases to 13.4?GPa (for LDA) or 20.8?GPa (for GGA), it begins to prone to ductility. Through the quasi-harmonic Debye model, we also investigated the thermodynamic properties of RuN{sub 2}.
Density functional theory study of the thermodynamic and elastic properties of Ni-based superalloys
NASA Astrophysics Data System (ADS)
Wu, Xiaoxia; Wang, Chongyu
2015-07-01
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 Î³-Ni and Î³â€§-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 0â€‰K, doping with refractory elements leads to tetragonal shear softening of the Î³-Ni phase. For Î³-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 câ€§ and Mo and W increase c44 of Î³-Ni. For the Î³â€§-Ni3Al phase, all of the alloying elements except Co considerably increase câ€§ and c44. Re and W at the Al site were found to most effectively harden the Î³â€§-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.
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
Isotope effects in solution thermodynamics: Excess properties in solution of isotopomers
Jancso, G. . Central Research Inst. for Physics); Rebelo, L.P.N. ); Van Hook, W.A. . Chemistry Dept.)
1993-12-01
In this review the authors consider recent studies of isotope effects (IE's) on the physical properties of solution, such as vapor pressure, molar volume, compressibility, etc. Such IE's are of interest for two reasons: first, because they can sometimes be capitalized to separation processes, and samples of separated isotopes may be scientifically and commercially valuable and second, and more importantly to use, because the sign and magnitude of condensed phase isotope effects (CPIE's) are closely related to the nature of the intermolecular forces in liquids and solutions. Thus, appropriate IE data can probe the nature of molecular interaction and structure. 91 refs.
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.
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)
Tychengulova, A.; Aldiyarov, A.; Drobyshev, A.
2015-06-01
The results of modeling of isotopic water mixture clusters in nitrogen and argon cryomatrices are presented. Earlier, our experimental studies of water mixture in cryomatrix have shown that changes in the concentration of analyte in matrix leads to a splitting of the absorption bands characteristic frequencies of the molecules in the IR spectrum. Moreover the multiplicity of characteristic absorption bands in the IR spectrum remained unchanged during heating of the samples from the condensation temperature to the sublimation temperature of the matrix element. In order to find out what structure of clusters is responsible for the immutability of the absorption bands in the vibrational spectrum during thermal cycling of the samples, computer research of water molecules enclosed in nitrogen and argon cryomatrices by the molecular dynamics simulation was conducted. For this purpose, theoretical studies were carried out using computer software packages, that implement used by us semi empirical and ab initio molecular dynamics methods. As a result of the research, the data must be obtained are of theoretical interest for summarizing the physical and chemical properties of systems, consisting of water molecules, and their combination with inert gases for studying the properties of molecular crystals composed of small molecules.
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.
Shirani, Ali; Shahbazi Mojarrad, Javid; Mussa Farkhani, Samad; yari khosroshahi, Ahmad; Zakeri-Milani, Parvin; Samadi, Naser; Sharifi, Simin; Mohammadi, Samaneh; Valizadeh, Hadi
2015-01-01
Purpose: Cell-penetrating peptides (CPPs) are used for delivering drugs and other macromolecular cargo into living cells. In this paper, we investigated the relationship between the structural/physicochemical properties of four new synthetic peptides containing arginine-tryptophan in terms of their cell membrane penetration efficiency. Methods: The peptides were prepared using solid phase synthesis procedure using FMOC protected amino acids. Fluorescence-activated cell sorting and ?uorescence imaging were used to evaluate uptake efficiency. Prediction of the peptide secondary structure and estimation of physicochemical properties was performed using the GOR V method and MPEx 3.2 software (Wimley-White scale, helical wheel projection and total hydrophobic moment). Results: Our data showed that the uptake e?ciency of peptides with two tryptophans at the C- and N-terminus were significantly higher (about 4-fold) than that of peptides containing three tryptophans at both ends. The distribution of arginine at both ends also increased the uptake e?ciency 2.52- and 7.18-fold, compared with arginine distribution at the middle of peptides. Conclusion: According to the obtained results the value of transfer free energies of peptides from the aqueous phase to membrane bilayer could be a good predictor for the cellular uptake efficiency of CPPs. PMID:26236653
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.
Properties of hadronic systems according to the non-extensive self-consistent thermodynamics
Deppman, A.
2014-11-11
The non-extensive self-consistent theory describing the thermodynamics of hadronic systems at high temperatures is used to derive some thermodynamical quantities, as pressure, entropy, speed of sound and trace-anomaly. The calculations are free of fitting parameters, and the results are compared to lattice QCD calculations, showing a good agreement between theory and data up to temperatures around 175 MeV. Above this temperature the effects of a singularity in the partition function at T{sub o} = 192 MeV results in a divergent behaviour in respect with the lattice calculation.
Sun, Na; Zhang, Xinyu Ning, Jinliang; Zhang, Suhong; Liang, Shunxing; Ma, Mingzhen; Liu, Riping; Qin, Jiaqian
2014-02-28
A comprehensive investigation of the structural, elastic, and thermodynamic properties for Laves-phases ZrZn{sub 2} and HfZn{sub 2} are conducted using density functional total energy calculations combined with the quasi-harmonic Debye model. The optimized lattice parameters of ZrZn{sub 2} and HfZn{sub 2} compare well with available experimental values. We estimated the mechanical behaviors of both compounds under compression, including mechanical stability, Young's modulus, Poisson's ratio, ductility, and anisotropy. Additionally, the thermodynamic properties as a function of pressure and temperature are analyzed and found to be in good agreement with the corresponding experimental data.
First principle study of elastic and thermodynamic properties of ZrZn2 and HfZn2 under high pressure
NASA Astrophysics Data System (ADS)
Sun, Na; Zhang, Xinyu; Qin, Jiaqian; Ning, Jinliang; Zhang, Suhong; Liang, Shunxing; Ma, Mingzhen; Liu, Riping
2014-02-01
A comprehensive investigation of the structural, elastic, and thermodynamic properties for Laves-phases ZrZn2 and HfZn2 are conducted using density functional total energy calculations combined with the quasi-harmonic Debye model. The optimized lattice parameters of ZrZn2 and HfZn2 compare well with available experimental values. We estimated the mechanical behaviors of both compounds under compression, including mechanical stability, Young's modulus, Poisson's ratio, ductility, and anisotropy. Additionally, the thermodynamic properties as a function of pressure and temperature are analyzed and found to be in good agreement with the corresponding experimental data.
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
Einstein-Born-Infeld-massive gravity: adS-black hole solutions and their thermodynamical properties
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panah, B. Eslam; Panahiyan, S.
2015-11-01
In this paper, we study massive gravity in the presence of Born-Infeld nonlinear electrodynamics. First, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ( r = 0). It will be shown that due to contribution of the massive part, the number, type and place of horizons may be changed. Next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. We also investigate thermal stability of these black holes in context of canonical ensemble. It will be shown that number, type and place of phase transition points are functions of different parameters which lead to dependency of stability conditions to these parameters. Also, it will be shown how the behavior of temperature is modified due to extension of massive gravity and strong nonlinearity parameter. Next, critical behavior of the system in extended phase space by considering cosmological constant as pressure is investigated. A study regarding neutral Einstein-massive gravity in context of extended phase space is done. Geometrical approach is employed to study the thermodynamical behavior of the system in context of heat capacity and extended phase space. It will be shown that GTs, heat capacity and extended phase space have consistent results. Finally, critical behavior of the system is investigated through use of another method. It will be pointed out that the results of this method is in agreement with other methods and follow the concepts of ordinary thermodynamics.
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.
Steele, W.V.; Chirico, R.D.; Klots, T.D.
1993-03-01
A detailed vibrational spectroscopic study of furan, pyrrole, and thiophene has been completed. These compounds form part of the base of five-membered ring systems on which the rest of the research program will be built Several methyl-substituted derivatives were also studied. The results will be used to confirm the model for alkyl- substitution in the ring systems. Gas-phase spectra and fundamental- frequency assignments were completed for 2,3- and 2,5-dihydrofuran. Those compounds initiate work on ring-puckering within the research program. A paper describing the need for third virial estimation, when using the virial equation of state to derive thermodynamic properties at pressures greater than 1 bar was completed.
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}Î‡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}Oâ‰¤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.
Eckert, C.A.
1987-01-01
Supercritical fluids (SCF's) are the medium for an exciting new separation technology which has the potential to provide a way to selectively remove the desirable or undesirable components from coal. Our objective is to investigate the thermodynamic properties of supercritical fluids pertinent to the extraction and/or reaction of coal. Specifically, we are measuring the solubilities of representative coal compounds in a variety of supercritical fluids. During this quarter, we measured the solubility of anthracene, thioxanthone, and xanthone in SC butane at 157, 162, and 182/sup 0/C. In order to expand the current solubility database of low temperature solvent studies, measurements were made with carbon dioxide at temperatures of 35, 50, and 70/sup 0/C and at pressures in the range of 100 to 420 bars. The solutes that were investigated include dibenzofuran, dibenzothiophene, and thianthrene. Results indicate higher solubilities can be obtained using SC butane. This solvent is likely to be better suited to coal processing applications.
Wasserman, Luybov A; Sergeev, Andrey I; Vasil'ev, Viktor G; Plashchina, Irina G; Aksenova, Nina P; Konstantinova, Tatyana N; Golyanovskaya, Svetlana A; Sergeeva, Lidiya I; Romanov, Georgy A
2015-07-10
Potato plants harboring Phytochrome B (PHYB) gene from Arabidopsis thaliana or rol genes from Agrobacterium rhizogenes were used to study the effect of transgene expression on structure and properties of starch in tubers. Thermodynamic characteristics of starch (melting temperature, enthalpy of melting, thickness of crystalline lamellae) were shown to be variable depending on the transgene expression and plant culturing mode: in vitro or in soil. The expression of rolB or rolC genes in in vitro cultured plants evoked opposite effects on starch melting temperature and crystalline lamellae thickness. AtPHYB or rolB expression in the soil-grown potato led to the formation of more defective or more ordered starch structures, respectively, in comparison with starches of the same lines grown in vitro. On the whole, our study revealed genotype-dependent differences between starches extracted from tubers of in vitro or in vivo grown plants. PMID:25857977
NASA Technical Reports Server (NTRS)
Johnson, R. C.
1972-01-01
Procedures for calculating the mass flow rate of methane and natural gas through nozzles are given, along with the FORTRAN 4 subroutines used to make these calculations. Three sets of independent variables are permitted in these routines. In addition to the plenum pressure and temperature, the third independent variable is either nozzle exit pressure, Mach number, or temperature. A critical-flow factor that becomes a convenient means for determining the mass flow rate of methane through critical-flow nozzles is tabulated. Other tables are included for nozzle throat velocity and critical pressure, density, and temperature ratios, along with some thermodynamic properties of methane, including compressibility factor, enthalpy, entropy, specific heat, specific-heat ratio, and speed of sound. These tabulations cover a temperature range from 120 to 600 K and pressures to 3 million N/sq m.
NASA Astrophysics Data System (ADS)
Ghoufi, Aziz; Malfreyt, Patrice
2006-12-01
The authors report calculations of the intermolecular potential of mean force (PMF) in the case of the host-guest interaction. The host-guest system is defined by a water soluble calixarene and a cation. With an organic cation such as the tetramethylammonium cation, the calixarene forms an insertion complex, whereas with the Lanthane cation, the supramolecular assembly is an outer-sphere complex. The authors apply a modified free energy perturbation method and the force constraint technique to establish the PMF profiles as a function of the separation distance between the host and guest. They use the PMF profile for the calculation of the absolute thermodynamic properties of association that they compare to the experimental values previously determined. They finish by giving some structural features of the insertion and outer-sphere complexes at the Gibbs free energy minimum.
Ghoufi, Aziz; Malfreyt, Patrice
2006-12-14
The authors report calculations of the intermolecular potential of mean force (PMF) in the case of the host-guest interaction. The host-guest system is defined by a water soluble calixarene and a cation. With an organic cation such as the tetramethylammonium cation, the calixarene forms an insertion complex, whereas with the Lanthane cation, the supramolecular assembly is an outer-sphere complex. The authors apply a modified free energy perturbation method and the force constraint technique to establish the PMF profiles as a function of the separation distance between the host and guest. They use the PMF profile for the calculation of the absolute thermodynamic properties of association that they compare to the experimental values previously determined. They finish by giving some structural features of the insertion and outer-sphere complexes at the Gibbs free energy minimum. PMID:17176145
NASA Astrophysics Data System (ADS)
Tian, Wenyan; Chen, Haichuan
2016-01-01
Using the first-principles calculations, the electronic structure, chemical bonding, mechanical, thermodynamics and superconductor properties of NbRuB are investigated. The optimized lattice parameters were in good agreement with the experimental data. The analysis of the density of states and chemical bonding implies that the metallic behavior of NbRuB originates from the Ru and Nb, and the bonding behaviors are a mixture of covalent-ionic bonds. The bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and hardness of NbRuB were calculated. The results reveal that the NbRuB is ductility and the Vickers hardness is 15.06?GPa. Moreover, the 3D dependences of reciprocals of Young’s modulus is also calculated and discussed, showing strong anisotropic character for NbRuB. Finally, the Debye temperature and superconducting transition temperature are obtained.
Tian, Wenyan; Chen, Haichuan
2016-01-01
Using the first-principles calculations, the electronic structure, chemical bonding, mechanical, thermodynamics and superconductor properties of NbRuB are investigated. The optimized lattice parameters were in good agreement with the experimental data. The analysis of the density of states and chemical bonding implies that the metallic behavior of NbRuB originates from the Ru and Nb, and the bonding behaviors are a mixture of covalent-ionic bonds. The bulk modulus, shear modulus, Young's modulus, Poisson's ratio and hardness of NbRuB were calculated. The results reveal that the NbRuB is ductility and the Vickers hardness is 15.06?GPa. Moreover, the 3D dependences of reciprocals of Young's modulus is also calculated and discussed, showing strong anisotropic character for NbRuB. Finally, the Debye temperature and superconducting transition temperature are obtained. PMID:26754861
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.
Tian, Wenyan; Chen, Haichuan
2016-01-01
Using the first-principles calculations, the electronic structure, chemical bonding, mechanical, thermodynamics and superconductor properties of NbRuB are investigated. The optimized lattice parameters were in good agreement with the experimental data. The analysis of the density of states and chemical bonding implies that the metallic behavior of NbRuB originates from the Ru and Nb, and the bonding behaviors are a mixture of covalent-ionic bonds. The bulk modulus, shear modulus, Youngâ€™s modulus, Poissonâ€™s ratio and hardness of NbRuB were calculated. The results reveal that the NbRuB is ductility and the Vickers hardness is 15.06â€‰GPa. Moreover, the 3D dependences of reciprocals of Youngâ€™s modulus is also calculated and discussed, showing strong anisotropic character for NbRuB. Finally, the Debye temperature and superconducting transition temperature are obtained. PMID:26754861
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.
NASA Astrophysics Data System (ADS)
Berdichevsky, Daniel B.; Schefers, Kendric
2015-05-01
It is shown that the occurrence of magnetization work is a consistent thermodynamic explanation of the property of anti-correlation between temperature and density of the electrons gas in a class of magnetic-field-dominated structures observed in the interplanetary medium. In this model, a 7/4 scaling ratio for magnetization work to electron-gas work explains the often observed anomalous adiabatic polytropic exponent {{? }a}=1/2. This interpretation is built on the theoretical conjecture of a matter state having spatial confinement of most hadronic elements of matter, i.e., matter held in place by the action of what is here denominated as a “super-strong” magnetic field, which together with the plasma it contains satisfies—on medium to large spatial-temporal scales—ideal magnetohydrodynamics. Several elements of the interpretation are tested for a case study, the flux-rope (FR) structure passing Wind SC on 1998 June 2. This allows us to extract, for a 185 s sample interval inside the FR, the following constitutive properties of this diamagnetic state of matter: (i) sound speed, (ii) thermal temperature, (iii) magnetic permeability, and (iv) a low limit to its dielectric permittivity. The intervals of coherence, i.e., thermodynamic homogeneity, extend from a few to many 104 km for plasma and magnetic field average with a sampling rate of 3s per value. We point out that this state of matter, which we identify to be an amorphous three-dimensional Langmuir lattice, differs from other materials studied in the laboratory at extreme low temperatures and is well described as BCS-superconductors because in our case we understand that (a) the magnetic permeability is non-zero, and (b) substantial field-aligned, convected-current density exists.
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 Technical Reports Server (NTRS)
Hendricks, R. C.
1994-01-01
A computer program, GASP, has been written to calculate the thermodynamic and transport properties of argon, carbon dioxide, carbon monoxide, fluorine, methane, neon, nitrogen, and oxygen. GASP accepts any two of pressure, temperature, or density as input. In addition, entropy and enthalpy are possible inputs. Outputs are temperature, density, pressure, entropy, enthalpy, specific heats, expansion coefficient, sonic velocity, viscosity, thermal conductivity, and surface tension. A special technique is provided to estimate the thermal conductivity near the thermodynamic critical point. GASP is a group of FORTRAN subroutines. The user typically would write a main program that invoked GASP to provide only the described outputs. Subroutines are structured so that the user may call only those subroutines needed for his particular calculations. Allowable pressures range from 0.l atmosphere to 100 to l,000 atmospheres, depending on the fluid. Similarly, allowable pressures range from the triple point of each substance to 300 degrees K to 2000 degrees K, depending on the substance. The GASP package was developed to be used with heat transfer and fluid flow applications. It is particularly useful in applications of cryogenic fluids. Some problems associated with the liquefication, storage, and gasification of liquefied natural gas and liquefied petroleum gas can also be studied using GASP. This program is written in FORTRAN IV for batch execution and is available for implementation on IBM 7000 series computers. GASP was developed in 1971.
NASA Astrophysics Data System (ADS)
Haas, Johnson R.; Shock, Everett L.
1999-10-01
Standard partial molal thermodynamic parameters for the aqueous chlorinated-ethylene species, perchloroethylene (PCE), trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), cis-1,2-dichloroethylene (cis-1,2-DCE), trans-1,2-dichloroethylene (trans-1,2,-DCE), and vinyl chloride (VC) have been estimated by using experimental gas-solubility data and correlation algorithms. The provided thermodynamic values may be used to calculate properties of reactions involving the aqueous chloroethylene species at a wide range of temperatures and pressures. Estimated values for the chloroethylenes were used, along with published values for minerals, gases, aqueous ions, and aqueous neutral organic species, to calculate the stability of chloroethylene species in equilibrium with the minerals magnetite, hematite, pyrite, and pyrrhotite in the subsurface. Estimated values for the aqueous chloroethylenes were also used to calculate reduction potentials for microbially-mediated reductive dechlorination half-reactions at elevated temperatures. Calculations indicate that all aqueous chloroethylene species are energetically favored to decompose to ethylene(aq) under a wide range of conditions in the subsurface, by both abiotic and biotic pathways. Anaerobic microbially mediated degradation is especially favored under conditions at least sufficiently reducing to promote sulfate-reduction, but not under conditions sufficient for microbial denitrification, pyrolusite reduction, or ferric-iron reduction.
Haas, J.R.; Shock, E.L.
1999-10-01
Standard partial molal thermodynamic parameters for the aqueous chlorinated-ethylene species, perchloroethylene (PCE), trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), cis-1,2-dichloroethylene (cis-1,2-DCE), trans-1,2-dichloroethylene (trans-1,2-DCE), and vinyl chloride (VC) have been estimated by using experimental gas-solubility data and correlation algorithms. The provided thermodynamic values may be used to calculate properties of reactions involving the aqueous chloroethylene species at a wide range of temperatures and pressures. Estimated values for the chloroethylenes were used, along with published values for minerals, gases, aqueous ions, and aqueous neutral organic species, to calculate the stability of chloroethylene species in equilibrium with the minerals magnetite, hematite, pyrite, and pyrrhotite in the subsurface. Estimated values for the aqueous chloroethylenes were also used to calculate reduction potentials for microbially-mediated reductive dechlorination half-reactions at elevated temperatures. Calculations indicate that all aqueous chloroethylene species are energetically favored to decompose to ethylene(aq) under a wide range of conditions in the subsurface, by both abiotic and biotic pathways. Anaerobic microbially mediated degradation is especially favored under conditions at least sufficiently reducing to promote sulfate-reduction, but not under conditions sufficient for microbial denitrification, pyrolusite reduction, or ferric-iron reduction.
Vítek, Aleš; Arismendi-Arrieta, D J; Rodríguez-Cantano, R; Prosmiti, R; Villarreal, P; Kalus, R; Delgado-Barrio, G
2015-04-14
Classical parallel-tempering Monte Carlo simulations in the isothermal-isobaric ensemble were carried out for the (H2O)20 and Ar(H2O)20 clusters, over a wide range of temperatures (30-1000 K) and pressures (3 kPa-10 GPa) in order to study their thermodynamic properties and structural changes. The TIP4P/ice water model is employed for the water-water interactions, while both semiempirical and ab initio-based potentials are used to model the interaction between the rare-gas atoms and the water molecules. Temperature-pressure phase diagrams for these cluster systems were constructed by employing a two-dimensional multiple-histogram method. Structural changes were detected by analyzing the heat capacity landscape and the Pearson correlation coefficient profile for the interaction energy and volume. Those at high pressure correspond to solid-to-solid transitions and are found to be related to clathrate-like cages around the Ar atom. It is also shown that the formation and thermodynamic stability of such structures are determined by the intermolecular interaction between the rare-gas atoms and the host water molecules. PMID:25745673
Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re ?-phase
Palumbo, Mauro Fries, Suzana G.; Pasturel, Alain; Alfè, Dario
2014-04-14
Using density-functional theory in combination with the direct force method and molecular dynamics we investigate the vibrational properties of a binary Cr-Re ?-phase. In the harmonic approximation, we have computed phonon dispersion curves and density of states, evidencing structural and chemical effects. We found that the ?-phase is mechanically unstable in some configurations, for example, when all crystallographic sites are occupied by Re atoms. By using a molecular-dynamics-based method, we have analysed the anharmonicity in the system and found negligible effects (?0.5 kJ/mol) on the Helmholtz energy of the binary Cr-Re ?-phase up to 2000 K (?0.8T{sub m}). Finally, we show that the vibrational contribution has significant consequences on the disordering of the ?-phase at high temperature.
NASA Astrophysics Data System (ADS)
Steinebrunner, Gerold; Dyson, Anthony J.; Kirchner, Barbara; Huber, Hanspeter
1998-08-01
An intermolecular potential energy surface for the carbon dioxide dimer is calculated fully ab initio using a large basis set and including electron correlation. From this potential the dimer structure and the second virial coefficients are determined. In addition, it is applied in molecular dynamics simulations to obtain the fluid structure, the pressure, the internal energy, the thermal pressure coefficient, and the molar heat at constant volume. The results are compared with those from simulations with a previous ab initio potential. In this way we gain information regarding the sensitivity of each property to the quality of the quantum chemically obtained potential. Equilibration of carbon dioxide simulations must be done with great care due to the very slow energy transfer between the intramolecular vibrations and the other degrees of freedom. This point is addressed in some detail.
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.
Polymer chain properties and thermodynamic stability in oriented-platelet nanocomposites.
Termonia, Yves
2013-07-01
We present a Monte Carlo study of the conformational properties of polymer chains in platelet nanocomposites. We find that high platelet orientation leads to an increase in chain confinement and to a substantial decrease in polymer entropy. The latter may be responsible for the observed aging of these systems in which the platelets gradually lose their orientation with time. As a test of our entropy-driven hypothesis, we suggest that aging could be substantially slowed down by the addition of small spherical nanoparticles. Using a generalized Stokes-Einstein relation, a calculation of the thermal random motion of the platelets predicts a fivefold increase in shear modulus during aging, in agreement with experimental observation on compatibilized layered silicate nanocomposites. PMID:23944482
Polymer chain properties and thermodynamic stability in oriented-platelet nanocomposites
NASA Astrophysics Data System (ADS)
Termonia, Yves
2013-07-01
We present a Monte Carlo study of the conformational properties of polymer chains in platelet nanocomposites. We find that high platelet orientation leads to an increase in chain confinement and to a substantial decrease in polymer entropy. The latter may be responsible for the observed aging of these systems in which the platelets gradually lose their orientation with time. As a test of our entropy-driven hypothesis, we suggest that aging could be substantially slowed down by the addition of small spherical nanoparticles. Using a generalized Stokes-Einstein relation, a calculation of the thermal random motion of the platelets predicts a fivefold increase in shear modulus during aging, in agreement with experimental observation on compatibilized layered silicate nanocomposites.
Thermodynamic properties of short-range attractive Yukawa fluid: simulation and theory.
Orea, Pedro; Tapia-Medina, Carlos; Pini, Davide; Reiner, Albert
2010-03-21
Coexistence properties of the hard-core attractive Yukawa potential with inverse-range parameter kappa=9, 10, 12, and 15 are calculated by applying canonical Monte Carlo simulation. As previously shown for longer ranges, we show that also for the ranges considered here the coexistence curves scaled by the critical density and temperature obey the law of corresponding states, and that a linear relationship between the critical density and the reciprocal of the critical temperature holds. The simulation results are compared to the predictions of the self-consistent Ornstein-Zernike approximation, and a good agreement is found for both the critical points and the coexistence curves, although some slight discrepancies are present. PMID:20331282
FP-LAPW investigation of the structural, electronic and thermodynamic properties of Al3Ta compound
NASA Astrophysics Data System (ADS)
Boulechfar, R.; Meradji, H.; Chouahda, Z.; Ghemid, S.; Drablia, S.; Khenata, R.
2015-09-01
The phase stability and electronic properties in Al3Ta compound are studied using the FP-LAPW method. In this approach, the generalized gradient approximation (GGA) is used for the exchange-correlation potential calculation. The total energy calculations show that the D022 structure is more stable than that of D023 and L12. The densities of states exhibit a pseudo gap near the Fermi level for all considered structures. By analyzing the electronic charge density we find a build-up of electrons in the interstitial region, and the bonds are directed from the Ta atoms to the Al atoms, which is the characteristic of covalent bonding. The temperature and pressure effects on the structural parameters, Debye temperature, Grüneisen parameter, heat capacities (Cv, Cp) and thermal expansion are predicted through the quasi-harmonic Debye model.
NASA Technical Reports Server (NTRS)
Lovell, Conrad S.; Wise, Kristopher E.; Kim, Jae-Woo; Lillehei, Peter T.; Harrison, Joycelyn S.; Park, Cheol
2009-01-01
A high molecular weight synthetic polypeptide has been designed which exhibits favorable interactions with single wall carbon nanotubes (SWCNTs). The enthalpic and entropic penalties of mixing between these two molecules are reduced due to the polypeptide's aromatic sidechains and helical secondary structure, respectively. These enhanced interactions result in a well dispersed SWCNT/Poly (L-Leucine-ran-L-Phenylalanine) nanocomposite with enhanced mechanical and electrical properties using only shear mixing and sonication. At 0.5 wt% loading of SWCNT filler, the nanocomposite exhibits simultaneous increases in the Young's modulus, failure strain, and toughness of 8%, 120%, and 144%, respectively. At one kHz, the same nanotube loading level also enhances the dielectric constant from 2.95 to 22.81, while increasing the conductivity by four orders of magnitude.
NASA Astrophysics Data System (ADS)
Çoban, C.; Çolako?lu, K.; Çiftçi, Y. Ö.
2015-09-01
We studied the structural, mechanical, phonon, optical and thermodynamic properties of MgAgAs-based NbFeSb compound by means of first-principles based on the density functional theory. The calculated lattice constant is in good agreement with the available experimental data. The electronic structure and corresponding density of states (DOS) were also calculated to give insight into the bonding mechanism and an indirect band gap was observed as ?1.77 eV, which is significantly higher than the previously reported one (0.529 eV). The elastic properties such as shear modulus, Young’s modulus etc under pressure, up to 65 GPa, were analyzed. The phonon dispersion curves, one-phonon DOS, and optical properties were obtained. In addition, the thermodynamic properties such as heat capacity, Debye temperature etc of NbFeSb were calculated at various temperatures and pressures by applying the quasi-harmonic Debye model.
NASA Astrophysics Data System (ADS)
Sudolská, Mária; Cantrel, Laurent; Budzák, Šimon; ?ernušák, Ivan
2014-03-01
Monohydrated complexes of iodine species (I, I2, HI, and HOI) have been studied by correlated ab initio calculations. The standard enthalpies of formation, Gibbs free energy and the temperature dependence of the heat capacities at constant pressure were calculated. The values obtained have been implemented in ASTEC nuclear accident simulation software to check the thermodynamic stability of hydrated iodine compounds in the reactor coolant system and in the nuclear containment building of a pressurised water reactor during a severe accident. It can be concluded that iodine complexes are thermodynamically unstable by means of positive Gibbs free energies and would be represented by trace level concentrations in severe accident conditions; thus it is well justified to only consider pure iodine species and not hydrated forms.
Lin, M.E.; Ramachandra, A.; Andres, R.P.; Reifenberger, R.
1991-12-31
Field emission techniques devised to measure the melting temperature and electronic structure of individual, nanometer-size clusters supported on electrically conducting substrates are reviewed. Data on the size-dependent reduction in melting temperature of Au cluster are compared to existing thermodynamic descriptions and molecular dynamic calculations. Data on the electronic structure of an individual 1nm Au cluster are compared to the predictions of simple electron shell models for cluster electronic states.
An analytical investigation for thermodynamic properties of the Fe-Cr-Ni-Mg-O system
NASA Astrophysics Data System (ADS)
Arslan, H.; Dogan, A.
2015-02-01
Present study performs excess energy values, activity coefficients and partial free energy associated with the quinary Fe-Cr-Ni-Mg-O, quaternary Au-In-Sn-Zn and ternary Pb-Au-Bi liquid alloys, based on published binary thermodynamic descriptions and Chou's model for extension into higher order systems. Using Kohler, Muggianu and Chou's model the obtained results in the present study were compared to available experimental data.
Study of Thermodynamic Properties of AuCu Superlattice by the Statistical Moment Method
NASA Astrophysics Data System (ADS)
Van Hung, Vu; Phuong, Cao Huy; Thi Hoa, Nguyen
2014-09-01
We have investigated the thermodynamic quantities of AuCu superlattice using the statistical moment method in the statistical physics. The free energy, thermal lattice expansion coefficients, mean-square atomic displacements, and specific heats at the constant volume and those at the constant pressure, Cv and Cp, are derived in closed analytic forms in terms of the power moments of the atomic displacements. The present analytic formulas including the anharmonic effects of the lattice vibration give the predicted values of these quantities.
Measuring Thermodynamic Properties of Metals and Alloys With Knudsen Effusion Mass Spectrometry
NASA Technical Reports Server (NTRS)
Copland, Evan H.; Jacobson, Nathan S.
2010-01-01
This report reviews Knudsen effusion mass spectrometry (KEMS) as it relates to thermodynamic measurements of metals and alloys. First, general aspects are reviewed, with emphasis on the Knudsen-cell vapor source and molecular beam formation, and mass spectrometry issues germane to this type of instrument are discussed briefly. The relationship between the vapor pressure inside the effusion cell and the measured ion intensity is the key to KEMS and is derived in detail. Then common methods used to determine thermodynamic quantities with KEMS are discussed. Enthalpies of vaporization, the fundamental measurement, are determined from the variation of relative partial pressure with temperature using the second-law method or by calculating a free energy of formation and subtracting the entropy contribution using the third-law method. For single-cell KEMS instruments, measurements can be used to determine the partial Gibbs free energy if the sensitivity factor remains constant over multiple experiments. The ion-current ratio method and dimer-monomer method are also viable in some systems. For a multiple-cell KEMS instrument, activities are obtained by direct comparison with a suitable component reference state or a secondary standard. Internal checks for correct instrument operation and general procedural guidelines also are discussed. Finally, general comments are made about future directions in measuring alloy thermodynamics with KEMS.
A class of black holes in dRGT massive gravity and their thermodynamical properties
NASA Astrophysics Data System (ADS)
Ghosh, Suchant G.; Tannukij, Lunchakorn; Wongjun, Pitayuth
2016-03-01
We present an exact spherical black hole solution 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 the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of 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 the dRGT black hole, and also perform thermodynamical stability analysis. 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 also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit m_g â†’ 0, reduced exactly to the results of general relativity.
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.
NASA Astrophysics Data System (ADS)
Falkowski, M.; Kowalczyk, A.; Toli?ski, T.
2013-04-01
We present extended studies including the dc and ac magnetic susceptibility, magnetization, specific heat, electrical resistivity and magnetoresistivity measurements for the Dy5Si3 compound with the hexagonal Mn5Si3-type structure. The results indicate that this compound orders antiferromagnetically below TN=137 K. The magnetic properties of Dy5Si3 are mainly governed by the presence of the magnetic moments of Dy3+ ions. In the paramagnetic range, the magnetic susceptibility follows the Curie-Weiss law with ?eff=10.57 ?B/Dy, which is very close to the theoretical value of 10.6 ?B. From the magnetometric, specific heat and transport data it has been found that below 50 K this compound reveals a non-collinear magnetic order, associated with a phase transition, probably of the first order type. On the basis of the thermodynamic approach, we report the magnetocaloric properties in the whole temperature range but concentrate mainly on the region around 50 K. The magnetocaloric effect was calculated in terms of the isothermal magnetic entropy change ?SM as well as the adiabatic temperature change ?Tad using the specific heat data. In spite of the only moderate ?SM values a significant relative cooling power has been observed.
First principle study of elastic and thermodynamic properties of FeB{sub 4} under high pressure
Zhang, Xinyu E-mail: jiaqianqin@gmail.com Ning, Jinliang; Sun, Xiaowei; Li, Xinting; Ma, Mingzhen; Liu, Riping E-mail: jiaqianqin@gmail.com; Qin, Jiaqian E-mail: jiaqianqin@gmail.com
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 0â€“100â€‰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 100â€‰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 GrÃ¼neisen parameter of FeB{sub 4} are successfully obtained in the present work.
NASA Astrophysics Data System (ADS)
Wang, Leini; Hou, Songjun; Liang, Dewei
2015-06-01
In this paper, we employ first-principles methods based on electronic density functional theory (DFT) to investigate the phase stability, elastic and thermodynamic properties of Zr-Al binary substitutional alloys which are Zr3Al, Zr2Al, ZrAl, ZrAl2 and ZrAl3. By analyzing the elastic constants and enthalpy of formation, those phases both satisfy the generalized stability criteria and the results show that ZrAl2 is the most stable. Due to high bulk modulus B, shear modulus G and Youngs modulus Y, ZrAl2 also possesses excellent mechanical properties. Moreover, it is expected that there will be covalent bonding between Zr and Al atom in ZrAl2 compound, which is confirmed by the electronic structure and the differences of charge density discussions. In the end, based on the calculated elastic modulus, the elastic wave velocity, Debye temperature ?D and specific heat CV are discussed. As a result, ZrAl3 possesses the highest Debye temperature and sound velocity, meaning a larger associated thermal conductivity and higher melting temperature.
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.
NASA Astrophysics Data System (ADS)
Li, Shi-Chang; Zheng, Yuan-Lei; Ma, Sheng-Gui; Gao, Tao; Ao, Bing-Yun
2015-12-01
The electronic structure, magnetic states, chemical bonding, and thermodynamic properties of Î²-US2 are investigated by using first-principles calculation through the density functional theory (DFT) +U approach. The obtained band structure exhibits a direct band gap semiconductor at Î“ point with a band gap of 0.9 eV for Î²-US2, which is in good agreement with the recent experimental data. The charge-density differences, the Bader charge analysis, and the Born effective charges suggest that the Uâ€“S bonds of the Î²-US2 have a mixture of covalent and ionic characters, but the ionic character is stronger than covalent character. The Raman-active, infrared-active, and silent modes at the Î“ point are further assigned and discussed. The obtained optical-mode frequencies indicate that the three apparent LOâ€“TO (longitudinal opticalâ€“transverse optical) splittings occur in B1u, B2u, and B3u modes, respectively. Furthermore, the Helmholtz free energy Î”F, the specific heat Î”E, vibrational entropy S, and constant volume CV are studied over a range from 0 Kâˆ¼100 K. We expect that our work can provide some valuable information for further experimental investigation of the dielectric properties and the infrared reflectivity spectrum of uranium chalcogenide. Project supported by the National Natural Science Foundation of China (Grant Nos.Â 21371160 and 21401173).
Asim, Sadia; Mansha, Asim; Landgraf, Stephan; Grampp, GÃ¼nter; Zahid, Muhammad; Bhatti, Haq Nawaz
2014-01-24
The exciplex emission spectra of N-ethylcarbazole with 1,2-dicyanobenzene (NEC/1,2-DCB), N-methylcarbazole with 1,2-dicyanobenzene (NMC/1,2-DCB), 1,3-dicyanobenzene (NMC/1,3-DCB), and 1,4-dicyanobenzene (NMC/1,4-DCB) are studied in tetrahydrofuran (THF) for the temperature range starting from 253 K to 334 K. Thermochromic shifts along with the spectral properties including change in peak intensities and the ratio of exciplex peak intensity to fluorophore peak intensity are studied. Effect of temperature on the energy of zero-zero transitions hÎ½o('), Huang-Rhys factor (S), Gauss broadening of vibronic level (Ïƒ) and the dominant high-frequency vibration (hÎ½Î½) are also part of investigation. Enthalpy of exciplex formation (Î”H(EX)(âˆ—)) calculated by the model proposed by A. Weller and the Gibb's energy of electron transfer (Î”G(et)(âˆ—)) for all exciplex systems are also discussed in the present paper. All the exciplexes under study were observed to be dipolar in nature. The exciplex of the N-methylcarbazole/1,4-dicyanobenzene was found to be the most stable and the N-methylcarbazole/1,3-dicyanobenzene was the weakest exciplex system. PMID:24051282
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
Calculations of the thermodynamic and kinetic properties of Li1+xV3O8
NASA Astrophysics Data System (ADS)
Jiang, Tonghu; Falk, Michael L.
2012-06-01
The phase behavior and kinetic pathways of Li1+xV3O8 are investigated by means of density-functional theory (DFT) and a cluster expansion method that approximates the system Hamiltonian in order to identify the lowest-energy configurations. Although DFT calculations predict the correct ground state for a given composition, both generalized gradient approximation (GGA) and local-density approximation fail to obtain phase stability consistent with experiment due to strongly localized vanadium 3d electrons. A DFT+U method recovers the correct phase stability for an optimized U value of 3.0 eV. GGA+U calculations with this value of U predict electronic structures that qualitatively agree with experiment. The resulting calculations indicate solid solution behavior from Li1V3O8 to Li2.5V3O8 and two-phase coexistence between Li2.5V3O8 and Li4V3O8. Analysis of the lithiation sequence from Li1V3O8 to Li2.5V3O8 reveals the mechanism by which lithium intercalation proceeds in this material. Calculations of lithium migration energies for different lithium concentrations and configurations provide insight into the relevant diffusion pathways and their relationship to structural properties.
Thermodynamic properties of hyperbranched polymer, Boltorn U3000, using inverse gas chromatography.
Doma?ska, Urszula; Zo?ek-Tryznowska, Zuzanna
2009-11-19
Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated. PMID:19852451
Melting and thermodynamic properties of pyrope (Mg3Al2Si3O12)
Tequi, C.; Robie, R.A.; Hemingway, B.S.; Neuville, D.R.; Richet, P.
1991-01-01
The heat capacity of Mg3Al2Si3O12 glass has been measured from 10 to 1000 K by adiabatic and differential scanning calorimetry. The heat capacity of crystalline pyrope has been determined from drop-calorimetry measurements between 820 and 1300 K. From these and previously published results a consistent set of thermodynamic data is presented for pyrope and Mg3Al2Si3O12 glass and liquid for the interval 0-2000 K. The enthalpy of fusion at 1570 ?? 30 K, the metastable congruent 1-bar melting point, is 241 ?? 12 kJ/mol. ?? 1991.
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 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.
The thermodynamic properties of Fe(II) complexes with 1,2,4-triazoles
NASA Astrophysics Data System (ADS)
Berezovskii, G. A.; Pishchur, D. P.; Shakirova, O. G.; Lavrenova, L. G.
2009-11-01
The temperature dependences of the heat capacities at 106-330 K of the monoligand Fe(NH2trz)3I2 ( I) and mixed-ligand Fe(Htrz)0.3(NH2trz)2.7SiF6 · H2O ( II) complexes (Htrz is 1,2,4-triazole, and NH2trz is 4-amino-1,2,4-triazole) were studied by adiabatic vacuum calorimetry. The 1A1 ? 5T2 spin transition was observed in these compounds. The thermodynamic parameters of phase transitions in I and II were determined.
NASA Astrophysics Data System (ADS)
Duan-Liang, Xiao; Meng-Yun, Lai; Xiao-Yin, Pan
2016-01-01
We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic potential and a constant magnetic field. Using an accurate density of states, we calculate analytically the thermodynamic potential and consequently various intriguing thermodynamic properties, including the Bose–Einstein transition temperature, the specific heat, magnetization, and the corrections to these quantities due to the finite number of particles are also given explicitly. In contrast to the infinite number of particles scenarios, we show that those thermodynamic properties, particularly the Bose–Einstein transition temperature depends upon the strength of the magnetic field due to the finiteness of the particle numbers, and the collective effects of a finite number of particles become larger when the particle number decreases. Moreover, the magnetization varies with the temperature due to the finiteness of the particle number while it keeps invariant in the thermodynamic limit N ? ?. Project supported by the National Natural Science Foundation of China (Grant No. 11375090), and the K. C. Wong Magna Foundation of Ningbo University, China.
Liu, Qingzhu; Qiu, Ling; Wang, Yang; Lv, Gaochao; Liu, Guiqing; Wang, Shanshan; Lin, Jianguo
2016-04-01
Zoledronic acid (ZL) has been used widely for treating skeletal diseases because of its high potency in inhibiting bone resorption. A detailed understanding of its physicochemical characteristics may be of great significance in both medicinal chemistry and structural biology for the design of novel bisphosphonates with higher activity. In the present work, the monoclinic (IM) and triclinic (IT) polymorphs of ZL in the gas phase and the aqueous phase were studied by density functional theory (DFT) method at the B3LYP/6-311++G** level. The polarizable continuum model (PCM) was employed to study the solvent effect on structures and properties. The optimized IM and IT conformations in both phases are in reasonable agreement with the experimental structures with the overall mean absolute percent deviation (MAPD%) less than 3.1Â %. The presence of intramolecular hydrogen bond within both conformations was identified in the solvent. The IR spectra were simulated and assigned in detail, which agreed well with the experimental data. The intramolecular hydrogen bonding interactions resulted in the shift of vibrational frequencies of hydroxyl to the low band by 12-22Â cm(-1) and 24-26Â cm(-1) for IM and IT conformations, respectively. Their thermodynamic properties were also calculated based on the harmonic vibrational analysis, including standard heat capacity (C (Â°) p,m), entropy (S (Â°) m), and enthalpy (H (Â°) m). The molecular stability, hydrogen bonding interaction and other electronic properties have been further analyzed by the natural bond orbital (NBO), atoms in molecules (AIM), molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis. Graphical abstract FMOs of IM and IT conformations in the gas phase and in the water. PMID:26994018