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1

Thermodynamic properties of nitrogen

This volume covers the thermodynamic properties of gaseous and 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. This volume contains: experimental data on thermodynamic properties of nitrogen; methods of deriving the equation of state and calculating thermodynamic tables; the equation of state and evaluation of computed thermodynamic functions relative to experimental data; tables of the thermodynamic properties of nitrogen.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

2

Thermodynamic properties of propane

Propane is widely employed in a variety of applications, necessitating accurate thermodynamic data. This work fills a void in both Soviet and Western compilations by providing the properties in one convenient source. The temperature range spans 100 to 700 K, and the pressures extend from 0.01 to 100 MPa. This book includes: experimental data on the thermodynamic properties of propane; a method of constructing a single equation of state and calculating the tables of the thermodynamic properties; equation of states and table of the thermodynamic functions of propane; and tables of the thermodynamic properties of propane.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Tsymarny, V.A.

1991-01-01

3

Thermodynamic properties of oxygen

Even after almost a century of experimental analysis, thermodynamic property tables for oxygen were often based on limited data. However, this new volume incorporates new information about density and isochoric specific heat into an unmatched, reliable set of tables. Temperatures and pressures covered range from the triple point to 1500 K, and 0.1 to 100 MPa, respectively. This accurate information describes oxygen in both liquid and gaseous phases. This volume contains: experimental data on thermodynamic properties of oxygen; methods of deriving the equation of state and calculating thermodynamic tables; the equation of state and evaluation of computed thermodynamic functions relative to experimental data; these of the thermodynamic properties of oxygen.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

4

Thermodynamic properties of air

This volume treats air as a single fluid, rather than as a mixture of oxygen and nitrogen, enabling you to design using accurate air properties - not well characterized in extant publications. This is why your research demands Thermodynamic Properties of Air. Utilizing modern computer capabilities, this work presents exceptionally reliable tables of the thermodynamic properties of gaseous and liquid air - for temperatures from 70 to 1500 K, and pressures from 0.01 to 100 MPa. The new method used to compile these tables not only assures accuracy, but permits evaluation of the maximum possible errors in the form of tolerances. This volume contains: experimental data on thermodynamic properties of air; methods of deriving the equation of state and calculating thermodynamic tables; the equation of state and evaluation of computed thermodynamic functions relative to experimental data; tables of the thermodynamic properties of air.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

5

Thermodynamic properties of air

This book treats air as a single fluid, rather than as a mixture of oxygen and nitrogen. Exceptionally reliable tables of the thermodynamic properties of gaseous liquid air are presented for temperatures from 70 to 1500 K and pressures from 0.1 to 100 MPa. The experimental data on the thermodynamic properties of air are discussed, and the procedure used to

Viacheslav Vladimirovich Sychev; A. A. Vasserman; A. D. Kozlov; G. A. Spiridonov; V. A. Tsymarnyi

1987-01-01

6

Thermodynamic properties of ethane

Ethane is a major raw material for organic synthesis, and reliable thermodynamic data are particularly valuable - especially since the use of computers in engineering calculations has evolved. This book serves as one of the rare sources of this key information. The detailed tables present thermodynamic properties of ethane from the triple point to 700 K, and at pressures from 0.1 to 80 MPa. Properties along the liquid-vapor and liquid-crystal coexistence curves are also included.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Zagoruchenko, V.A.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

7

Thermodynamic properties of air

This volume treats air as a single fluid, rather than as a mixture of oxygen and nitrogen, facilitating design using accurate air properties that have not been well characterized in extant publications. Utilizing modern computer capabilities, this work presents exceptionally reliable tables of the thermodynamic properties of gaseous liquid air - for temperatures from 70 to 1500 K, and pressures from 0.1 to 100 MPa. The new method used to compile these tables not only assures accuracy, but permits evaluation of the maximum possible errors in the form of tolerances. Topics considered include experimental data on thermodynamic properties of air; procedure for compiling; tables of thermodynamic properties of air; and equations of state.

Sychen, V.V.; Vassekman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymakny, V.A.

1987-01-01

8

Generating Tables of Thermodynamic Properties

NASA Technical Reports Server (NTRS)

Thermodynamic Property Generation program produces tables for any fluid for which state equation, vapor pressure equation, specific heat equation, and critical constants are known. Program calculates thermodynamic properties at any state providing way of obtaining properties at extreme environmental conditions.

Nguyen, S. N.

1985-01-01

9

Thermodynamic properties of ethylene

This volume offers methods for calculating tables of thermodynamic properties based on results of a critical analysis of the most reliable PVT data published to date, and developing an averaged equation of state. Data is provided for both gaseous and liquid ethylene spanning the temperature range 110-60 K and pressures from 0.1 to 300 MPa including properties at the saturation and solidification curves.

Sychev, V.V.; Vasserman, A.A.; Golovsky, E.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

10

Thermodynamic properties of methanol

Offers data on key properties of saturated liquid and vapor, drawn from a not-widely-available but comprehensive and reliable Soviet reference. Recommends Thermophysical Properties of Methanol, by V.N. Zubarev, P.G. Prusakov and L.V. Sergeyeva, as the most comprehensive publication of thermodynamic and transport properties of methanol. In this 201-p. book, specific volume, specific enthalpy and specific entropy tables for the saturated liquid and vapor are given in 1 deg. C increments from the melting point to the critical point. Similar tables for the single phase for 0.01 to 500 bar, -95 deg. to 300 deg. C occupy 134 pages. For those without access to this book, the accompanying data, compiled from it, should augment available information on the chemical. The table includes data on specific volume, specific enthalpy, specific entropy and specific heat for temperatures between 175.4 K and 512.7 K. Also presents a thermodynamic diagram.

Liley, P.E.

1982-11-01

11

Thermodynamic properties of nitrogen

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.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

12

Thermodynamic properties of helium

This volume offers reliable data on the thermodynamic properties of helium over a wide variety of conditions. Spanning temperatures between the lambda line and 1500 K and pressures up to 100 MPa, these data are vital to helium extraction from natural gases and to the design of cryogenic apparatus. The equations of state are considered along with the construction of a single equation of state. 175 references.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarnyi, V.A.

1987-01-01

13

Thermodynamic properties of oxygen

In this monograph the authors analyze published experimental data on the thermodynamic properties of oxygen, give short descriptions of the methods of construction of the equation of state and of calculation of the tables, provide basic computational relations, and compare the calculated values of quantities with previously published experimental and tabulated data. The use of the authors' method of statistical treatment of many equations of state, equivalent in descriptive precision to the initial information, allowed an increase in the reliability of calculated values of caloric quantities and to evaluate their error. The tables show the values of density, compressibility, enthalpy, entropy, isochoric and isobaric specific heat, speed of sound and many other necessary practical thermodynamic functions for the liquid and gaseous phases and on the solidification and saturation curves in the temperature interval from the triple point to 1500 K and pressures between 0.1 and 100 MPa.

Sychen, V.V.; Vassekman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymakny, V.A.

1987-01-01

14

Thermodynamic properties of isomerization reactions

In handbook form, this book provides both experimental and theoretical data describing thermodynamic properties of groups of isomers of different classes, particularly for organic compound reactions. Data have been derived through chemical equilibria studies, statistical thermodynamics, and to some degree, calorimetry. Data based on equilibria studies are also valuable as a cross-check to thermodynamic functions derived purely from calorimetric measurements. Unique in its presentation, this book systematizes available data and compiles nearly 1,000 isomerization reactions of organic compounds. Contents include: specific aspects of determining the thermodynamic properties of isomerization reactions; qualitative regularities of changes in the enthalpy ad entropy functions of isomerization reactions; and description of tables.

Frenkel, M.L.; Kabo, G.Ya.; Roganov, G.H.

1992-10-01

15

Thermodynamic properties of methane

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.

Sychev, V.V.; Vasserman, A.A.; Golovsky, E.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

1987-01-01

16

Thermodynamic properties of cerium mononitride

NASA Astrophysics Data System (ADS)

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.

Aristova, N. M.; Belov, G. V.

2014-09-01

17

Tables on Thermodynamic Properties

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It provides the introduction to data tables and physical quantities involved.

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

18

Tables on Thermodynamic Properties

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It provides the introduction to data tables and physical quantities involved.

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

19

Tables on Thermodynamic Properties

NASA Astrophysics Data System (ADS)

This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It provides the introduction to data tables and physical quantities involved.

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

20

Thermodynamic properties of methane

This book provides a unified equation of state and calculating tables of properties for methane. The temperature range spans the triple point to 1000 K and the pressures extend from 0.1 to 100 MPa. The range of parameters of state and the scope of tabulated qualities far exceeds the data offered in most other sources. 185 references.

Sychev, V.V.; Vasserman, A.A.; Zagoruchenko, V.A.; Kozlov, A.D.; Spiridonov, G.A.

1987-01-01

21

Thermodynamic Properties of Supported Catalysts

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.

Gorte, Raymond J.

2014-03-26

22

The thermodynamic properties of radium

The enthalpy, Gibbs free energy, and entropies of aqueous radium species and radium solids have been evaluated from empirical data, or estimated when necessary for 25°C and 1 bar. Estimates were based on such approaches as extrapolation of the thermodynamic properties of Ca, Sr, and Ba complexes and solids plotted against cationic radii and charge to radius functions, and the

Donald Langmuir; Arthur C. Riese

1985-01-01

23

Thermodynamic properties of uranium dioxide

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.

Fink, J.K.; Chasanov, M.G.; Leibowitz, L.

1981-04-01

24

ASHRAE thermodynamic properties of refrigerants

This edition contains formulations with a higher degree of accuracy for many fluids and covers a wider range of values than formulations used to produce previous ASHRAE tables. Available in either Inch-Pound (I-P) or International System units (SI). Covers thermodynamic property formulations for halocarbons, ammonia, carbon dioxide, hydrocarbons, and cryogenic fluids. Appendix contains ANSI/ASHRAE Standard 34-78. ''Number Designation of Refrigerants.''

Not Available

1986-01-01

25

Thermodynamical properties of dark energy

We have investigated the thermodynamical properties of dark energy. Assuming that the dark energy temperature T{approx}a{sup -n} and considering that the volume of the Universe enveloped by the apparent horizon relates to the temperature, we have derived the dark energy entropy. For dark energy with constant equation of state w>-1 and the generalized Chaplygin gas, the derived entropy can be positive and satisfy the entropy bound. The total entropy, including those of dark energy, the thermal radiation, and the apparent horizon, satisfies the generalized second law of thermodynamics. However, for the phantom with constant equation of state, the positivity of entropy, the entropy bound, and the generalized second law cannot be satisfied simultaneously.

Gong Yungui; Wang Bin; Wang Anzhong [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China) and CASPER, Department of Physics, Baylor University, Waco, Texas 76798 (United States); Department of Physics, Fudan University, Shanghai 200433 (China); CASPER, Department of Physics, Baylor University, Waco, Texas 76798 (United States)

2007-06-15

26

Caustic aluminate: physical, thermodynamic, and transport properties

Experimental data in the literature on the physical, thermodynamic, and transport properties of caustic aluminate and its precipitate, hydrargillite, are summarized. An analytical expression for the vapor pressure of water over such solutions is derived.

Homsy, R.V.

1980-03-28

27

Tables of thermodynamic properties of sodium

NASA Astrophysics Data System (ADS)

The thermodynamic properties of saturated sodium, superheate 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.

Fink, J. K.

1982-06-01

28

Tables of thermodynamic properties of sodium

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.

Fink, J.K.

1982-06-01

29

Thermodynamic properties of liquid metals /A review/.

NASA Technical Reports Server (NTRS)

Summary of the current state of knowledge about the thermodynamic properties of liquid metals, including heats of fusion and heat capacities. A table is presented of consistent thermodynamic data for liquid metals, including estimates for the many high-melting transition metals which have not yet been studied, based on new levitation data and on periodic table correlations.

Margrave, J. L.

1970-01-01

30

Thermodynamic Properties of Aqueous Solution of Ammonia

NASA Astrophysics Data System (ADS)

Present status on the thermodynamic properties of experimental data and their correlations of both ammonia and aqueous solution of ammonia was introduced in this paper. The aqueous solution of ammonia is used for not only a working fluid in absorption refrigerator cycles but also working fluids in bottoming cycles of steam power plants and other heat recovering systems. Therefore, the thermodynamic properties of this substance are required in a wide range of temperatures, pressures and compositions. The experimental results of pVTx properties for ammonia and aqueous solution of ammonia and their comparisons with a formulation by Tillner-Roth and Friend1) were critically surveyed. The “Guideline on the IAPWS Formulation 2000 for the Thermodynamic Properties of Ammonia-Water Mixtures”, correlated by Tillner-Roth and Friend1), was approved on September, 2001, by the International Association for the Properties of Water and Steam (IAPWS) 2).

Kitamura, Hiroshi; Oguchi, Kosei

31

Thermodynamic properties of wadsleyite with anharmonic effect

NASA Astrophysics Data System (ADS)

The thermodynamic properties of crystals can be routinely calculated by density functional theory calculations combining with quasi-harmonic approximation. Based on the method developed recently by Wu and Wentzcovitch (Phys Rev B 79:104304, 2009) and Wu (Phys Rev B 81:172301, 2010), we are able to further ab initio include anharmonic effect on thermodynamic properties of crystals by one additional canonical ensemble with numbers of particle, volume and temperature fixed (NVT) molecular dynamic simulations. Our study indicates that phonon-phonon interaction causes the renormalized phonon frequencies of wadsleyite decrease with temperature. This is consistent with the Raman experimental observation. The anharmonic free energy of wadsleyite is negative and its heat capacity at constant pressure can exceed the Dulong-Petit limit at high temperature. The anharmonicity still significantly affects thermodynamic properties of wadsleyite at pressure and temperature conditions correspond to the transition zone.

Wu, Zhongqing

2015-02-01

32

Thermodynamic properties of organic iodine compounds

NASA Astrophysics Data System (ADS)

A critical evaluation has been made of the thermodynamic properties reported in the literature for 43 organic iodine compounds in the solid, liquid, or ideal gas state. These compounds include aliphatic, cyclic and aromatic iodides, iodophenols, iodocarboxylic acids, and acetyl and benzoyl iodides. The evaluation has been made on the basis of carbon number systematics and group additivity relations, which also allowed to provide estimates of the thermodynamic properties of those compounds for which no experimental data were available. Standard molal thermodynamic properties at 25 °C and 1 bar and heat capacity coefficients are reported for 13 crystalline, 29 liquid, and 39 ideal gas organic iodine compounds, which can be used to calculate the corresponding properties as a function of temperature and pressure. Values derived for the standard molal Gibbs energy of formation at 25 °C and 1 bar of these crystalline, liquid, and ideal gas organic iodine compounds have subsequently been combined with either solubility measurements or gas/water partition coefficients to obtain values for the standard partial molal Gibbs energies of formation at 25 °C and 1 bar of 32 aqueous organic iodine compounds. The thermodynamic properties of organic iodine compounds calculated in the present study can be used together with those for aqueous inorganic iodine species to predict the organic/inorganic speciation of iodine in marine sediments and petroleum systems, or in the near- and far-field of nuclear waste repositories.

Richard, Laurent; Gaona, Xavier

2011-11-01

33

Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

NASA Technical Reports Server (NTRS)

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.

Hunt, J. L.; Boney, L. R.

1973-01-01

34

Thermodynamic properties of aqueous sodium chloride solutions

Experimental measurements of the osmotic and activity coefficients, the enthalpy, and the heat capacity were used to derive a semiempirical equation for the thermodynamic properties of NaCl(aq) at constant pressure. This equation may be combined with results contained in the previous paper on the volumetric properties to yield a complete equation of state valid in the region 273 K< or =T< or =573 K, saturation pressure < or =P< or =1 kbar, 0< or =m< or =6.0 mol kg/sup -1/. It is shown that this equation may be extrapolated to higher solute molalities at lower pressures. An estimation of uncertainties in various quantities is given. Tables of values for various thermodynamic properties are presented in the appendix.

Pitzer, K.S.; Peiper, J.C.; Busey, R.H.

1984-01-01

35

High temperature drop calorimetry and thermodynamic properties

Experimental determination of thermodynamic properties (e.g. enthalpy of formation, heat capacity, Gibbs free energy, etc.) is still the recourse for accurate thermodynamic data for the condensed phases. Calorimetry is probably the best experimental method for their determination. Drop calorimetry in its various modifications is still the method of choice to determine the enthalpy functions for solids and liquids above 1,000 C. The conventional drop calorimeter for solids and a drop calorimeter coupled to an electromagnetic levitation coil useful for conductive samples in both the solid and molten phases are described. Experimental results obtained up to and above the melting point of rare earth metals are presented.

Chandrasekhariah, M.S. [Houston Advanced Research Center, The Woodlands, TX (United States). Materials Science Research Center; Bautista, R.G. [Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering

1995-04-01

36

Thermodynamics and statistical mechanics. [thermodynamic properties of gases

NASA Technical Reports Server (NTRS)

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.

1976-01-01

37

Thermodynamic properties of ammonia in the critical region

A theoretically based crossover model, which incorporates a crossover from singular thermodynamic behavior at the critical point to regular thermodynamic behavior far away from the critical point, is presented for the thermodynamic properties of ammonia. The equation is capable of representing the thermodynamic properties of ammonia between 398 and 500K in an appreciable range of densities around the critical density.

T. A. Edison; J. V. Sengers

1999-01-01

38

Thermodynamic properties of hydrogen-helium plasmas

NASA Technical Reports Server (NTRS)

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.

Nelson, H. F.

1971-01-01

39

Thermodynamic properties for the alternative refrigerants

Models commonly used to calculate the thermodynamic properties of refrigerants are summarized. For pure refrigerants, the virial, cubic, Martin-Hou, Benedict-Webb-Rubin, and Helmholtz energy equations of state and the extended corresponding states model are discussed. High-accuracy formulations for 16 refrigerants are recommended. These models may be extended to mixtures through the use of mixing rules applied either to the parameters of

Mark O McLinden; Eric W Lemmon; Richard T Jacobsen

1998-01-01

40

Specification properties and thermodynamical properties of semigroup actions

In the present paper we study the thermodynamical properties of finitely generated continuous subgroup actions. We address a notion of topological entropy and pressure functions that does not depend on the growth rate of the semigroup and introduce strong and orbital specification properties, under which, the semigroup actions have positive topological entropy and all points are entropy points. Moreover, we study the convergence and Lipschitz regularity of the pressure function and obtain relations between topological entropy and exponential growth rate of periodic points in the context of semigroups of expanding maps. The specification properties for semigroup actions and the corresponding one for its generators and the action of push-forward maps is also discussed.

Fagner B. Rodrigues; Paulo Varandas

2015-03-27

41

The thermodynamic properties of thianthrene and phenoxathiin

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.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.

1993-04-01

42

Thermodynamic Properties of Actinides and Actinide Compounds

NASA Astrophysics Data System (ADS)

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.

Konings, Rudy J. M.; Morss, Lester R.; Fuger, Jean

43

Thermodynamic properties of water and steam

This book provides a working knowledge of water and steam and their various properties, and how their values relate to the addition or withdrawal of heat. Values of thermodynamic properties can be displayed for all the intermediate values between those in the tables. It explains working with heat cycles and their performance, heat exchangers, heat flow and heart distribution accounting, and heat balances. It also explains the determination of turbine efficiency in converting steam to work. The other application routine is for the determination of correction factors for steam or water flowmeters; covers formulation of calculated values and accuracy, superheated steam, saturated or moist steam, compressed or sat water, turbine efficiency, flowmeter correction factors, terms and expressions with reference to water and steam.

Dukelow, S.G.

1985-01-01

44

Prediction of thermodynamic properties of coal derivatives

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.

Donohue, M.D.

1990-09-01

45

Thermodynamic properties for R-404A

An 18-coefficient modified Benedict-Webb-Rubin equation of state has been developed for R-404A, a ternary mixture of 44% by mass of pentafluoroethane (R-125), 52% by mass of 1,1,1-trifluoroethane (R-143a), and 4% by mass of 1,1,1,2-tetrafluoroethane (R-134a). Correlations of bubble point pressures, dew point pressures, saturated liquid densities, and saturated vapor densities are also presented. This equation of state has been developed based on the reported experimental data of PVT properties, saturation properties, and isochoric heat capacities by using least-squares fitting. These correlations are valid in the temperature range from 250 K to the critical temperature. This equation of state is valid at pressures up to 19 MPa, densities to 1,300 kg {center_dot} m{sup {minus}3}, and temperatures from 250 to 400 K. The thermodynamic properties except for the saturation pressures are calculated from this equation of state.

Fujiwara, K.; Nakamura, S.; Noguchi, M. [Daikin Industries, Ltd., Settsu, Osaka (Japan). Chemical Div.] [Daikin Industries, Ltd., Settsu, Osaka (Japan). Chemical Div.

1999-01-01

46

Universal relation for size dependent thermodynamic properties of metallic nanoparticles.

The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values. PMID:21523307

Xiong, Shiyun; Qi, Weihong; Cheng, Yajuan; Huang, Baiyun; Wang, Mingpu; Li, Yejun

2011-06-14

47

(Relationships between microscope structure and thermodynamic properties)

This paper exhibits on the molecular level, the relationships between the microscopic structure and thermodynamic properties of dilute supercritical solutions by application of the integral equation theories for molecular distribution functions. To solve the integral equations, the authors use Baxter's Wiener-Hopf factorization of the Ornstein-Zernike equations and then apply this method to binary Lennard-Jones mixtures. A number of closure relations have been used: such as the Percus-Yevick (PY), the reference hypernetted chain (RHNC), the hybrid mean spherical approximation (HMSA), and the reference interaction-site (RISM) methods. The authors examine the microstructures of several important classes of supercritical mixtures, including the usual attractive-type and the less known repulsive-type solutions. The clustering of solvent molecules for solvent-solute structures in the attractive mixtures and, correspondingly, the solvent cavitation in the repulsive mixtures are clearly demonstrated. These are shown to be responsible for the large negative growth of the solute partial molar volumes in the attractive case and the positive growth in the repulsive case.

Wu, R.S.; Lee, L.L. (School of Chemical Engineering and Materials Science, Univ. of Oklahoma, Norman, OK (US)); Cochran, D. (Chemical Technology Div., Oak Ridge National Lab., Oak Ridge, TN (US))

1990-06-01

48

Dimensionless thermodynamics: a new paradigm for liquid state properties.

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

Sanchez, Isaac C

2014-08-01

49

THERMODYNAMIC AND TRANSPORT PROPERTIES OF SILICATE MELTS AND MAGMA

-1- THERMODYNAMIC AND TRANSPORT PROPERTIES OF SILICATE MELTS AND MAGMA Charles E. Lesher Pliny the Elder (c. AD 23-79) ________________________________________ TABLE OF CONTENTS I. GLOSSARY1 II. NOMENCLATURE2 III. INTRODUCTION3 IV. MAGMATIC SYSTEMS: TIME AND LENGTH SCALES4 V. MAGMA THERMODYNAMIC

Spera, Frank J.

50

Composition and Thermodynamic Properties of Air in Chemical Equilibrium

NASA Technical Reports Server (NTRS)

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)

Moeckel, W E; Weston, Kenneth C

1958-01-01

51

Thermodynamic property determination in low gravity

NASA Technical Reports Server (NTRS)

Techniques for determining heat capacities and other properties of molten metals were investigated and critically evaluated. Precisely determining heat capacities calorimetrically in space poses several problems. The weight of a drop calorimeter block along with the necessity of obtaining a large number of data points tend to make traditional approaches appear infeasible. However, for many substances exhibiting sufficiently high thermal conductivities and with known emissivities, it appears possible to investigate their properties by observing the rate of cooling of a levitated sphere which is initially at a uniform temperature above the melting point. A special advantage of the levitation method is that considerable supercooling is expected, making the study of the heat capacities of molten metals both above and below their melting points possible.

Margrave, J. L.

1977-01-01

52

Pvt surface and thermodynamic properties of isobutane

Selected values of vapor pressure, specific volume, enthalpy, and entropy are presented for the saturated liquid and vapor states of isobutane from the normal boiling point (261.32Â°K) to the critical point (408.13Â°K). The compilation is part of a general revision of the j-Tables of real gas properties of the API Research Project 44 (30) for Câ-Câ alkanes. (35 refs.)

T. R. Das; C. O. Jr. Reed; P. T. Eubank

1973-01-01

53

Thermodynamical properties of graphene in noncommutative phase-space

We investigated the thermodynamic properties of graphene in a noncommutative phase-space in the presence of a constant magnetic field. In particular, we determined the behaviour of the main thermodynamical functions: the Helmholtz free energy, the mean energy, the entropy and the specific heat. The high temperature limit is worked out and the thermodynamic quantities, such as mean energy and specific heat, exhibit the same features as the commutative case. Possible connections with the results already established in the literature are discussed briefly.

Victor Santos; R. V. Maluf; C. A. S. Almeida

2014-07-28

54

Microcomputer Calculation of Thermodynamic Properties from Molecular Parameters of Gases.

ERIC Educational Resources Information Center

Described in this article is a problem-solving activity which integrates the application of microcomputers with the learning of physical chemistry. Students use the program with spectroscopic data to calculate the thermodynamic properties and compare them with the values from the thermochemical tables. (Author/KR)

Venugopalan, Mundiyath

1990-01-01

55

Computer program for calculating thermodynamic and transport properties of fluids

NASA Technical Reports Server (NTRS)

Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.

Hendricks, R. C.; Braon, A. K.; Peller, I. C.

1975-01-01

56

Reference Fluid Thermodynamic and Transport Properties Database (REFPROP)

National Institute of Standards and Technology Data Gateway

SRD 23 NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP) (PC database for purchase) NIST 23 contains revised data in a Windows version of the database, including 105 pure fluids and allowing mixtures of up to 20 components. The fluids include the environmentally acceptable HFCs, traditional HFCs and CFCs and 'natural' refrigerants like ammonia

57

Orientational Order, Thermodynamics and Mechanical Properties of Nematic Elastomers

A novel microscopic theory for the thermodynamics, orientational order and mechanical properties of strained polymer melts and rubber networks has been developed based on anisotropic polymer integral equation methods. The consequences of interchain excluded volume repulsions, chain connectivity and long range nematic order are simultaneously taken into account. Spontaneous distortion is predicted and correlated with the degree of nematic order.

Folusho Oyerokun; Kenneth Schweizer

2004-01-01

58

Thermodynamical properties of a rotating ideal Bose gas Sebastian Kling*

Thermodynamical properties of a rotating ideal Bose gas Sebastian Kling* Institut fÃ¼r Angewandte. The condensate was set into such a fast rotation that the centrifugal force in the corotating frame potential becomes sombrero shaped. We present an analysis for an ideal Bose gas that is confined

Pelster, Axel

59

NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species

NASA Technical Reports Server (NTRS)

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.

McBride, Bonnie J.; Zehe, Michael J.; Gordon, Sanford

2002-01-01

60

The structural, elastic and thermodynamic properties of thorium tetraboride

NASA Astrophysics Data System (ADS)

The structural, elastic and thermodynamic properties of thorium tetraboride (ThB 4) have been investigated by using first-principles plane-wave pseudopotential density functional theory with generalized gradient approximation. The behaviors of structural parameters under 0-70 GPa hydrostatic pressure are studied by means of Broyden, Fletcher, Goldfarb, and Shanno (BFGS) geometry optimization scheme. By using the stress-strain method, single crystal elastic constants are calculated to test the mechanical stability of the crystal structure and to determine mechanical properties such as bulk modulus at each pressure. However, in order to study the thermodynamic properties of ThB 4, the quasi-harmonic Debye model is used. Then, the dependencies of bulk modulus, heat capacities, thermal expansions, Grüneisen parameters and Debye temperatures on the temperature and pressure are obtained in the whole pressure range 0-70 GPa and temperature range 0-1500 K.

Aydin, Sezgin; Tatar, Aynur

2011-04-01

61

Thermodynamic properties and environmental chemistry of chromium

Values of standard entropy, standard enthalpy of formation, and standard free energy of formation for Cr and its solid and aqueous species are tabulated in this report. These values were selected or recalculated after careful evaluation of the best available current thermochemical data. The basis for selection of data centered on conformation with the recent studies of Vasil'ev et al. (1977a,b, 1978, 1980, 1981) for Cr/sup 3 +/ data and O'Hare and Boerio (1975) for CrO/sub 4//sup 2 -/ data. The thermodynamic data presented in this report will be incorporated into the data base of the geochemical computer model, MINTEQ. The distribution of Cr in the environment among its aqueous inorganic species is, according to the thermodynamic data, highly dependent upon pH and Eh and the presence of complexing ligands. The speciation of Cr in natural waters is also controlled by reduction and complexation by organic matter, adsorption and oxidation by Mn-oxide in suspended particulate matter and sediment, and reduction by H/sub 2/S released from anoxic sediments. 89 references, 8 figures, 11 tables.

Schmidt, R.L.

1984-07-01

62

Thermodynamic properties of bulk and confined water

NASA Astrophysics Data System (ADS)

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 (TL ? 225 K). The second, T* ˜ 315 ± 5 K, is a special locus of the isothermal compressibility KT(T, P) and the thermal expansion coefficient ?P(T, P) in the P-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 (TL) and the onset of the unfolding process (T*).

Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H. Eugene

2014-11-01

63

Thermodynamic properties and atomic structure of Ca-based liquid alloys

To identify the most promising positive electrodes for Ca-based liquid metal batteries, the thermodynamic properties of diverse Ca-based liquid alloys were investigated. The thermodynamic properties of Ca-Sb alloys were ...

Poizeau, Sophie (Sophie Marie Claire)

2013-01-01

64

Thermodynamic properties of bulk and confined water

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} ? 225 K). The second, T{sup *} ? 315 ± 5 K, is a special locus of the isothermal compressibility K{sub T}(T, P) and the thermal expansion coefficient ?{sub P}(T, P) in the P–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 *})

Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Mallamace, Domenico [Dipartimento di Scienze dell'Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano; Vasi, Cirino [IPCF-CNR, I-98166 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)

2014-11-14

65

Tables of thermodynamic properties of helium magnet coolant

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10{sup 8} Pa'', Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres'', Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

66

Tables of thermodynamic properties of helium magnet coolant. Revision A

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: ``Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10{sup 8} Pa``, Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: ``Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres``, Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

67

Tables of thermodynamic properties of helium magnet coolant, revision A

NASA Astrophysics Data System (ADS)

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: 'Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10(exp 8) Pa', Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923-1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: 'Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres', Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

68

Thermodynamic properties by non-calorimetric methods: Progress report

NASA Astrophysics Data System (ADS)

This project for the Office of Energy Research focuses on the noncalorimetric determination of thermodynamic properties of polynuclear aromatic molecules through the extension of existing correlation methodologies and through molecular spectroscopy with statistical mechanics. This report highlights progress during the first third of the contract period. Important advances include: derivation of group-contribution parameters for estimation of thermodynamic properties for polycyclic hydrocarbon and nitrogen-containing compounds; calculation of thermodynamic properties for eight key monocyclic compounds based on new and literature spectra were completed for the derivation of 'ring- correction' property estimation parameters; design and construction of a long pathlength, far-infrared sample cell for the collection of vapor-phase spectra of low vapor-pressure compounds; development of a method to predict the vibrational frequencies of two- and three-ring polycyclic molecules to an accuracy sufficient for identifying the fundamental vibrations in experimental spectra; and development of a method to calculate the kinetic energy expansions as a function of the coordinate for the ring-puckering, ring-twisting (in-phase), and ring-twisting (out-of-phase) vibrations of 9,10-dihydroanthracene and related molecules.

Strube, M. Michael; Chirico, R. D.; Collier, W. B.; Steele, W. V.

69

Intermolecular interactions and the thermodynamic properties of supercritical fluids.

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

Yigzawe, Tesfaye M; Sadus, Richard J

2013-05-21

70

Thermodynamic and transport properties of cryogenic propellants and related fluids

NASA Technical Reports Server (NTRS)

Significant advances have been made in recent years in the quality and range of thermophysical data for the cryogenic propellants, pressurants, and inertants. A review of recently completed and current data compilation projects for helium, hydrogen, argon, nitrogen, oxygen, fluorine, and methane is given together with recommended references for thermodynamic and transport property data tables for these fluids. Modern techniques in the plotting of thermodynamic charts from tabular data (or from functions such as the equation of state) have greatly improved their precision and value. A list of such charts is included.

Johnson, V. J.

1973-01-01

71

Thermodynamic mixing properties of olivine derived from lattice vibrations

We use a lattice vibrational technique to derive thermophysical and thermochemical properties of fayalite, Fe2SiO4. This semi-empirical technique is based on an extension of Kieffer’s model to incorporate details of the phonon spectrum.\\u000a It includes treatment of intrinsic anharmonicity and electronic effects based on crystal field theory. We extend it to predict\\u000a thermodynamic mixing properties of olivine (Mg,Fe)2SiO4\\u000a solid solutions

Michel Henricus Gerardus Jacobs; Bernard H. W. S. de Jong

2009-01-01

72

Thermodynamic properties of liquid water from a polarizable intermolecular potential

NASA Astrophysics Data System (ADS)

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.

Yigzawe, Tesfaye M.; Sadus, Richard J.

2013-01-01

73

Thermodynamic properties of metastable Ag-Cu alloys

NASA Astrophysics Data System (ADS)

The enthalpies of formation of metastable fcc Ag-Cu solid solutions, produced by ball milling of elemental powders, were determined by differential scanning calorimetry. Experimental thermodynamic data for these metastable alloys and for the equilibrium phases are compared with both calculation of phase diagrams (CALPHAD) and atomistic simulation predictions. The atomistic simulations were performed using the free-energy minimization method (FEMM). The FEMM determination of the equilibrium Ag-Cu phase diagram and the enthalpy of formation and lattice parameters of the metastable solid solutions are in good agreement with the experimental measurements. CALPHAD calculations made in the same metastable regime, however, significantly overestimate the enthalpy of formation. Thus, the FEMM is a viable alternative approach for the calculation of thermodynamic properties of equilibrium and metastable phases, provided reliable interatomic potentials are available. The FEMM is also capable of determining such properties as the lattice parameter which are not available from CALPHAD calculations.

Najafabadi, R.; Srolovitz, D. J.; Ma, E.; Atzmon, M.

1993-09-01

74

Thermodynamic properties of the Fe-Cr-P liquid solution

A Knudsen-cell mass spectrometer was used to determine thermodynamic properties of the Fe-Cr-P alloys in the temperature range of 1,403 to 1,821 K. Concentration of the components varied within the mole-fraction ranges, as follows: Fe, 0.059 to 0.801; Cr, 0.054 to 0.789; and P, 0.048 to 0.318. The isoactivity lines of phosphorous are close to the secants connecting the Fe-P and Cr-P binary sides. Iron and chromium activities decrease regularly as the configuration point moves from the Fe-Cr liquid solution toward the Fe-P and Cr-P melts. The thermodynamic properties have been described, with the associated solution model assuming that binary and ternary complexes exist in the melt.

Zaitsev, A.I.; Shelkova, N.E.; Mogutnov, B.M. [I.P. Bardin Central Research Inst. for Iron and Steel Industry, Moscow (Russian Federation)

1998-02-01

75

Thermodynamic properties of massive dilaton black holes, 2

We numerically reanalyze static and spherically symmetric black hole solutions in an Einstein-Maxwell-dilaton system with a dilaton potential $m_{d}^{2}\\phi^{2}$. We investigate thermodynamic properties for various dilaton coupling constants and find that thermodynamic properties change at a critical dilaton mass $m_{d,crit}$. For $m_{d}\\geq m_{d,crit}$, the black hole becomes an extreme solution for a nonzero horizon radius $r_{h,ex}$ as the Reissner-Nordstr\\"om black hole. However, if $m_{d}$ is nearly equal to $m_{d,crit}$, there appears a solution of smaller horizon radius than $r_{h,ex}$. For $m_{d}

Tamaki, T

2002-01-01

76

Thermodynamic properties and diffusion of water + methane binary mixtures

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.

Shvab, I.; Sadus, Richard J., E-mail: rsadus@swin.edu.au [Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218 Hawthorn, Victoria 3122 (Australia)

2014-03-14

77

Thermodynamic properties of materials derived from coal liquefaction

Few measurements of the thermodynamic properties of materials obtained from the liquefaction of coal have been reported. Because several sets of well-defined fractions of coal-derived materials existed that had been separated and characterized by the Characterization Branch of the Division of Processing and Thermodynamics of this Center, the expertise of the Thermodynamics Research Branch was utilized to measure enthalpies of combustion and heat capacities of these materials. The sets of fractions came from five sources: a synthetic crude oil derived from western Kentucky coal by the char-oil-energy development (COED) process, a synthetic crude oil derived from Utah A-seam coal by the COED process, material derived from West Virginia Pittsburgh seam coal by the Synthoil process, material derived from Illinois No. 6 coal by the H-Coal process and materials derived from subbituminous coal by the Conoco Colstrip zinc chloride hydrocracking process.

Smith, N.K.; Lee-Bechtold, S.H.; Good, W.D.

1980-01-01

78

Thermodynamic and rheological properties of hard sphere dispersions

We investigate the thermodynamic and rheological properties of hard sphere dispersions with colloidal poly-(methyl methacrylate) particles grafted with a layer of poly-(12-hydroxy stearic acid) (PMMA-PHSA). These spheres are index-matched in a mixture of tetralin and decalin and the absorption of tetralin into the PMMA core is determined with light scattering. The effective hard sphere volume fraction is set by the

See-Eng Phan

1998-01-01

79

Thermodynamic and magnetocaloric properties of geometrically frustrated Ising nanoclusters

NASA Astrophysics Data System (ADS)

Thermodynamic and magnetocaloric properties of geometrically frustrated Ising spin clusters of selected shapes and sizes are studied by exact enumeration. In the ground state the magnetization and the entropy show step-wise variations with an applied magnetic field. The number of steps, their widths and heights depend on the cluster shape and size. While the character of the magnetization plateau heights is always increasing, the entropy is not necessarily decreasing function of the field, as one would expect. For selected clusters showing some interesting ground-state properties, the calculations are extended to finite temperatures by exact enumeration of densities of states in the energy-magnetization space. In zero field the focus is laid on a peculiar behavior of some thermodynamic quantities, such as the entropy, the specific heat and the magnetic susceptibility. In finite fields various thermodynamic functions are studied in the temperature-field parameter plane and particular attention is paid to the cases showing an enhanced magnetocaloric effect. The exact results on the finite clusters are compared with the thermodynamic limit behavior obtained from Monte Carlo simulations.

Žukovi?, M.

2015-01-01

80

Coefficients for calculating thermodynamic and transport properties of individual species

NASA Technical Reports Server (NTRS)

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.

Mcbride, Bonnie J.; Gordon, Sanford; Reno, Martin A.

1993-01-01

81

Detection of DNA Hybridization Properties Using Thermodynamic Method

NASA Astrophysics Data System (ADS)

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.

Kim, Do-Kyun; Kwon, Young-Soo; Takamura, Yuzuru; Tamiya, Eiichi

2006-01-01

82

Standard Chemical Thermodynamic Properties of Alkyne Isomer Groups

The chemical thermodynamic properties of alkyne isomer groups from C/sub 2/H/sub 2/ to C/sub 5/H/sub 8/ in the ideal gas phase have been calculated from 298.15 to 1000 K from tables of Stull, Westrum, and Sinke. In the absence of literature data on all isomers of higher isomer groups, the properties of isomers of C/sub 6/H/sub 10/ to C/sub 8/H/sub 14/ have been estimated using Benson group values. Equilibrium mole fractions within isomer groups have been calculated for the ideal gas state from 298.15 to 1000 K. For isomer group properties, increments per carbon atom have been calculated to show the extent to which thermodynamic properties of higher isomer groups may be obtained by linear extrapolation. Values of C/sup circle-open//sub P/, S/sup circle-open/, ..delta../sub f/H/sup circle-open/, and ..delta../sub f/G/sup circle-open/ are given for all species from C/sub 2/H/sub 2/ to C/sub 8/H/sub 14/ in SI units for a standard state pressure of 1 bar.

Alberty, R.A.; Burmenko, E.

1986-10-01

83

Structural and thermodynamics properties of organo-modified montmorillonite clay

NASA Astrophysics Data System (ADS)

Polymer clay nanocomposites (PCNs) have been seen as the most novel materials in engineering applications since they exhibit significant improvement in mechanical and physical properties. Indeed, with few amount of organoclay, PCNs exhibit enhanced mechanical, optical, thermal and liquid or gas barrier properties compared to pure polymers and to their counterpart microcomposites. Thus, organoclays are extensively used as precursors in the preparation of PCNs. They are the best candidate in reinforcing PCNs because of the lightweight and the high availability of clay minerals in the nature. However, structure and physical phenomena arising at molecular level in organoclays, and subsequently in PCNs, are not completely or difficultly accessible with existing experimental techniques. In this work, molecular dynamics (MD) simulation was conducted using the combination of two force fields (CLAYFF and CHARMM) to evaluate the thermodynamics and structural properties of organoclay such as heat capacities, isothermal bulk modulus, density, basal spacing and chains arrangement in the interlayer spacing. Our results regarding the basal spacing and density are in fairly good agreement with available experimental data. This allows us to validate the use of the two force fields to represent interactions in organoclays. The effect of the cation exchange capacity (CEC) on the basal spacing and the thermodynamics properties is assessed. We found, through our MD simulation, that the calculated isothermal bulk modulus is in good agreement with the density value of organoclays with two different CEC.

Anoukou, K.; Zaoui, A.; Zaïri, F.; Naït-Abdelaziz, M.; Gloaguen, J. M.

2015-01-01

84

ERIC Educational Resources Information Center

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…

Piele, Philip K.

85

Thermodynamic properties of asymptotically Reissner–Nordström black holes

Motivated by possible relation between Born–Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner–Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariant metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points. -- Highlights: •We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. •We investigate thermodynamic stability and discuss about the size of stable black holes. •We obtain analytical solutions of higher dimensional theory.

Hendi, S.H., E-mail: hendi@shirazu.ac.ir

2014-07-15

86

The sources of previous thermodynamic property values are detailed for nickel and some compounds of nickel that might be expected as derived from anthropogenic introduction of nickel into the environment or are required for calculation of thermodynamic properties of nickel-containing systems. Included are descriptions of the sources of information and the methodology used to obtain the values for these compounds

Donald G. Archer

1999-01-01

87

The sources of previous thermodynamic property values are detailed for cadmium and some compounds of cadmium that might be expected as derivative from anthropogenic introduction of cadmium into the environment or are required for calculation of thermodynamic properties of cadmium-containing systems. Included are descriptions of the sources of information and methodology used to obtain the values for these compounds reported

Donald G. Archer

1998-01-01

88

Calculating thermodynamic properties from fluctuations at small scales.

We show how density and energy fluctuations of small nonperiodic systems embedded in a reservoir can be used to determine macroscopic thermodynamic properties like the enthalpy density and the thermodynamic correction factor. For mixtures, the same formalism leads to a very convenient method to obtain so-called total correlation function integrals, also often referred to as Kirkwood-Buff integrals. Using finite size scaling, the properties obtained for small systems can be extrapolated to the macroscopic system limit provided that the system is sufficiently far from the critical point. As derived in our previous work (Chem. Phys. Lett. 2011, 504, 199-201), the finite size scaling is significant and depends on 1/L, where L is the length of the small system in one dimension. By considering a reservoir with an ensemble of embedded small systems, we can use the scaling arising from surface effects to determine properties for macroscopic systems by extrapolation. We demonstrate this method for the WCA and LJ fluids, as well a for a heterogeneous system, i.e., argon adsorbed in silicalite-1 zeolite. PMID:21838274

Schnell, Sondre K; Liu, Xin; Simon, Jean-Marc; Bardow, André; Bedeaux, Dick; Vlugt, Thijs J H; Kjelstrup, Signe

2011-09-22

89

Simplified curve fits for the thermodynamic properties of equilibrium air

NASA Technical Reports Server (NTRS)

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.

Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.

1987-01-01

90

The structural, thermodynamical and elastic properties of TiO

NASA Astrophysics Data System (ADS)

In this paper, we have studied the structural, elastic, electronic and thermodynamical properties of TiO by performing ab initio calculations within the local density approximation (LDA). In particular, the lattice constant, bulk modulus, cohesive energy, phase transition pressure (Pt) from NaCl (B1) to CsCl (B2) structure, second-order elastic constants (Cij) and electronic band structures are calculated and compared with available experimental and other theoretical values. In order to gain further information, we have also predicted Young's modulus, Poisson's ratio (?), anisotropy factor (A), sound velocities, Debye temperature (?D) and their pressure-dependent behaviours in the B1 phase.

Ciftci, Yasemin O.; Ünlü, Yasemin; Colakoglu, Kemal; Deligoz, Engin

2009-08-01

91

Thermodynamic properties and electrical conductivity of strongly correlated plasma media

We study thermodynamic properties and the electrical conductivity of dense hydrogen and deuterium using three methods: classical reactive Monte Carlo (REMC), direct path integral Monte Carlo (PIMC) and a quantum dynamics method in the Wigner representation of quantum mechanics. We report the calculation of the deuterium compression quasi-isentrope in good agreement with experiments. We also solve the Wigner-Liouville equation of dense degenerate hydrogen calculating the initial equilibrium state by the PIMC method. The obtained particle trajectories determine the momentum-momentum correlation functions and the electrical conductivity and are compared with available theories and simulations.

Filinov, V S; BoÅ£an, A V; Bonitz, M; Fortov, V E

2008-01-01

92

FLUID- THERMODYNAMIC AND TRANSPORT PROPERTIES OF FLUIDS (IBM PC VERSION)

NASA Technical Reports Server (NTRS)

The accurate computation of the thermodynamic and transport properties of fluids is a necessity for many engineering calculations. The FLUID program was developed to calculate the thermodynamic and transport properties of pure fluids in both the liquid and gas phases. Fluid properties are calculated using a simple gas model, empirical corrections, and an efficient numerical interpolation scheme. FLUID produces results that are in very good agreement with measured values, while being much faster than older more complex programs developed for the same purpose. A Van der Waals equation of state model is used to obtain approximate state values. These values are corrected for real-gas effects by model correction factors obtained from tables based on experimental data. These tables also accurately compensate for the special circumstances which arise whenever phase conditions occur. Viscosity and thermal conductivity values are computed directly from tables. Interpolation within tables is based on Lagrange's three point formula. A set of tables must be generated for each fluid implemented. FLUID currently contains tables for nine fluids including dry air and steam. The user can add tables for any fluid for which adequate thermal property data is available. The FLUID routine is structured so that it may easily be incorporated into engineering programs. The IBM 360 version of FLUID was developed in 1977. It is written in FORTRAN IV and has been implemented on an IBM 360 with a central memory requirement of approximately 222K of 8 bit bytes. The IBM PC version of FLUID is written in Microsoft FORTRAN 77 and has been implemented on an IBM PC with a memory requirement of 128K of 8 bit bytes. The IBM PC version of FLUID was developed in 1986.

Fessler, T. E.

1994-01-01

93

FLUID- THERMODYNAMIC AND TRANSPORT PROPERTIES OF FLUIDS (IBM VERSION)

NASA Technical Reports Server (NTRS)

The accurate computation of the thermodynamic and transport properties of fluids is a necessity for many engineering calculations. The FLUID program was developed to calculate the thermodynamic and transport properties of pure fluids in both the liquid and gas phases. Fluid properties are calculated using a simple gas model, empirical corrections, and an efficient numerical interpolation scheme. FLUID produces results that are in very good agreement with measured values, while being much faster than older more complex programs developed for the same purpose. A Van der Waals equation of state model is used to obtain approximate state values. These values are corrected for real-gas effects by model correction factors obtained from tables based on experimental data. These tables also accurately compensate for the special circumstances which arise whenever phase conditions occur. Viscosity and thermal conductivity values are computed directly from tables. Interpolation within tables is based on Lagrange's three point formula. A set of tables must be generated for each fluid implemented. FLUID currently contains tables for nine fluids including dry air and steam. The user can add tables for any fluid for which adequate thermal property data is available. The FLUID routine is structured so that it may easily be incorporated into engineering programs. The IBM 360 version of FLUID was developed in 1977. It is written in FORTRAN IV and has been implemented on an IBM 360 with a central memory requirement of approximately 222K of 8 bit bytes. The IBM PC version of FLUID is written in Microsoft FORTRAN 77 and has been implemented on an IBM PC with a memory requirement of 128K of 8 bit bytes. The IBM PC version of FLUID was developed in 1986.

Fessler, T. E.

1994-01-01

94

ERIC Educational Resources Information Center

Chapter 7 of a book on school law, this chapter deals with 1979 cases involving disputes over property. Cases involving taxpayer attempts to prevent the construction of school buildings dominate this year's property chapter, as they did last year's. Yet, paradoxically, there is also a significant increase in cases in which taxpayers tried to…

Piele, Philip K.

95

Thermodynamic properties of the Group 1A elements

This review describes thermodynamic properties of condensed phases of the alkali metals, excluding francium for which the amount of information is too limited. The properties considered are: heat capacities from 0 to 1600 K, temperatures and enthalpies of fusion and martensitic transformation in Li and Na; discussion of the Debye temperature and electronic heat capacity coefficient at absolute zero temperature is also included. The paper is the second part of a series. Similar to previous assessment of the IIA group [93ALC/CHA], this paper considers original studies, especially with respect to factors which influence the accuracy and reliability of results. Recommendations derived from such analyses are compared with most advanced previous reviews made at the Institute for High Temperatures (Moscow) [70SHP/YAK], [82GUR] and the National Institute of Standards and Technology (Washington) [85JAN]. The properties of individual elements of the group are compared and suggestions are made for experimental studies which should improve poorly measured quantities. The review is supplemented by an IBM PC database which contains references, assessed data, brief description of studies and has facilities for fitting and plotting of data and for adding new information.

Alcock, C.B.; Itkin, V.P. [Univ. of Toronto (Canada); Chase, M.W. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1994-05-01

96

NASA Technical Reports Server (NTRS)

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.

Nguyen, Huy H.; Martin, Michael A.

2004-01-01

97

ms2: A molecular simulation tool for thermodynamic properties

NASA Astrophysics Data System (ADS)

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.

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

98

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.

Gordon, S.

1982-07-01

99

NASA Technical Reports Server (NTRS)

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.

Gordon, S.

1982-01-01

100

Thermodynamic properties of liquid Au–Bi–Sn alloys

The thermodynamic properties of the liquid ternary Au–Bi–Sn alloys were determined using an electromotive force (EMF) method with an eutectic mixture of (KCl + LiCl) as liquid electrolyte. The cell arrangement was: W, Sn ( l ) / KCl – LiCl – SnCl 2 / Au – Bi – Sn ( l ) , W. The measurements were carried out over the temperature range from 723 K to 973 K. The compositions investigated were situated on three different cross-sections with a constant ratio of Au:Bi = 2:1, 1:1, and 1:2. The partial Gibbs free energies of Sn in liquid Au–Bi–Sn alloys were determined as a function of concentration and temperature. The integral Gibbs free energy and the integral enthalpy at T = 800 K were calculated by the Gibbs–Duhem integration. The ternary interaction parameters were evaluated using the Redlich–Kister–Muggianu polynomial. PMID:25550675

Guo, Zhongnan; Yuan, Wenxia; Hindler, Michael; Mikula, Adolf

2012-01-01

101

Thermodynamic properties of Rashba spin-orbit-coupled Fermi gas

NASA Astrophysics Data System (ADS)

We investigate the thermodynamic properties of a superfluid Fermi gas subject to Rashba spin-orbit coupling and effective Zeeman field. We adopt a T -matrix scheme that takes beyond-mean-field effects, which are important for strongly interacting systems, into account. We focus on the calculation of two important quantities: the superfluid transition temperature and the isothermal compressibility. Our calculation shows very distinct influences of the out-of-plane and the in-plane Zeeman fields on the Fermi gas. We also confirm that the in-plane Zeeman field induces a Fulde-Ferrell superfluid below the critical temperature and an exotic finite-momentum pseudogap phase above the critical temperature.

Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan

2014-12-01

102

Thermodynamic Properties Characterizing the Bloch Electrons in Magnetic Fields

NASA Astrophysics Data System (ADS)

We study the thermodynamic properties characterizing the Bloch electrons described by the Harper-equation with anisotropy, such as grandcanonical potential, entropy, specific heat and energetic level occupancy number. For this purpose one resort to the density of states derivated before. At low temperatures we found oscillatory-like behaviors of the grandcanonical potential versus the applied magnetic field. In this case plateaus are present in the dependence of the level occupancy number on the chemical potential. The behavior of entropy and specific heat is similar with those found in other theoretical models. The anisotropy parameter dependence of the specific heat, at different temperatures, shows a peaked structure which is able to serve as a signature for the experimentally observed dynamically induced phase transitions, or magnetic phases.

Szakács, Z.

2010-08-01

103

Note on electrical and thermodynamic properties of isolated horizons

NASA Astrophysics Data System (ADS)

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.

Chen, Gerui; Wu, Xiaoning; Gao, Sijie

2015-03-01

104

Thermodynamic properties of asymptotically Reissner-Nordstrom black holes

Motivated by possible relation between Born-Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner--Nordstrom 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.

Seyed Hossein Hendi

2014-05-24

105

Thermodynamic properties of asymptotically Reissne-Nordström black holes

NASA Astrophysics Data System (ADS)

Motivated by possible relation between Born-Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissne-Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariant metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points.

Hendi, S. H.

2014-07-01

106

Structural and thermodynamic properties of AlB2 compound

NASA Astrophysics Data System (ADS)

We employ a first-principles plane wave method with the relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter (HGH) scheme in the frame of DFT to calculate the equilibrium lattice parameters and the thermodynamic properties of AlB2 compound with hcp structure. The obtained lattice parameters are in good agreement with the available experimental data and those calculated by others. Through the quasi-harmonic Debye model, obtained successfully are the dependences of the normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized primitive cell volume V/V0 on pressure P, the variation of the thermal expansion ? with pressure P and temperature T, as well as the Debye temperature ?D and the heat capacity CV on pressure P and temperature T.

Zhou, Xiao-Lin; Liu, Ke; Chen, Xiang-Rong; Zhu, Jun

2006-12-01

107

A note on electrical and thermodynamic properties of Isolated Horizon

The electrical laws and Carnot cycle of Isolated Horizon (IH) are investigated in this paper. We establish the Ohm's law and Joule's law of an Isolated Horizon, and find that the conceptual picture of black holes (Membrane Paradigm) can also apply to this kind of quasi-local black holes. We also investigate the geometrical properties near a non-rotating IH, and find that under the first-order approximation of r, there exist a Killing vector and a Hamiltonian conjugate to it, so this vector is a physical observer. We calculate the energy as measured at infinity of a particle at rest outside a non-rotating IH, and use this result to construct a reversible Carnot cycle with the Isolated Horizon as a cold reservoir, which confirms the thermodynamic nature of Isolated Horizon.

Gerui Chen; Xiaoning Wu; Sijie Gao

2014-10-29

108

Electronic and thermodynamic properties of ?-Pu2O3

NASA Astrophysics Data System (ADS)

Based on density functional theory+U calculations and the quasi-annealing simulation method, we obtain the ground electronic state for ?-Pu2O3 and present its phonon dispersion curves as well as various thermodynamic properties, which have seldom been theoretically studied because of the huge unit cell. We find that the Pu-O chemical bonding is weaker in ?-Pu2O3 than in fluorite PuO2, and subsequently a frequency gap appears between oxygen and plutonium vibration density of states. Based on the calculated Helmholtz free energies at different temperatures, we further study the reaction energies for Pu oxidation, PuO2 reduction, and transformation between PuO2 and ?-Pu2O3. Our reaction energy results are in agreements with available experiment. And it is revealed that high temperature and insufficient oxygen environment are in favor of the formation of ?-Pu2O3.

Lu, Yong; Yang, Yu; Zheng, Fawei; Zhang, Ping

2014-08-01

109

Thermodynamic properties of chlorite and berthierine derived from calorimetric measurements

NASA Astrophysics Data System (ADS)

In the context of the deep waste disposal, we have investigated the respective stabilities of two iron-bearing clay minerals: berthierine ISGS from Illinois [USA; (Al0.975FeIII0.182FeII1.422Mg0.157Li0.035Mn0.002)(Si1.332Al0.668)O5(OH)4] and chlorite CCa-2 from Flagstaff Hill, California [USA; (Si2.633Al1.367)(Al1.116FeIII0.215Mg2.952FeII1.712Mn0.012Ca0.011)O10(OH)8]. For berthierine, the complete thermodynamic dataset was determined at 1 bar and from 2 to 310 K, using calorimetric methods. The standard enthalpies of formation were obtained by solution-reaction calorimetry at 298.15 K, and the heat capacities were measured by heat-pulse calorimetry. For chlorite, the standard enthalpy of formation is measured by solution-reaction calorimetry at 298.15 K. This is completing the entropy and heat capacity obtained previously by Gailhanou et al. (Geochim Cosmochim Acta 73:4738-4749, 2009) between 2 and 520 K, by using low-temperature adiabatic calorimetry and differential scanning calorimetry. For both minerals, the standard entropies and the Gibbs free energies of formation at 298.15 K were then calculated. An assessment of the measured properties could be carried out with respect to literature data. Eventually, the thermodynamic dataset allowed realizing theoretical calculations concerning the berthierine to chlorite transition. The latter showed that, from a thermodynamic viewpoint, the main factor controlling this transition is probably the composition of the berthierine and chlorite minerals and the nature of the secondary minerals rather than temperature.

Blanc, Philippe; Gailhanou, Hélène; Rogez, Jacques; Mikaelian, Georges; Kawaji, Hitoshi; Warmont, Fabienne; Gaboreau, Stéphane; Grangeon, Sylvain; Grenèche, Jean-Marc; Vieillard, Philippe; Fialips, Claire I.; Giffaut, Eric; Gaucher, Eric C.; Claret, F.

2014-09-01

110

The thermodynamic properties of 2,3-benzothiophene

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.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Steele, W.V.

1991-01-01

111

The thermodynamic properties of hydrated ?-Al2O3 nanoparticles

NASA Astrophysics Data System (ADS)

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.

Spencer, Elinor C.; Huang, Baiyu; Parker, Stewart F.; Kolesnikov, Alexander I.; Ross, Nancy L.; Woodfield, Brian F.

2013-12-01

112

The thermodynamic properties of S-lactic acid

NASA Astrophysics Data System (ADS)

The enthalpies of combustion and formation of S-lactic acid at 298.15 K, ?c H {m/o}(cr.) = -1337.9 ± 0.8 and ?f H {m/o}(cr.) = -700.1 ± 0.9 kJ/mol, were determined by calorimetry. The temperature dependence of acid vapor pressure was studied by the transpiration method, and the enthalpy of its vaporization was obtained, ?vap H o(298.15 K) = 69.1 ± 1.0 kJ/mol. The temperature and enthalpy of fusion, T m (330.4 K) and ?m H o(298.15 K) = 14.7 ± 0.2 kJ/mol, were determined by differential scanning calorimetry. The enthalpy of formation of the acid in the gas phase was obtained. Ab initio methods were used to perform a conformational analysis of the acid, calculate fundamental vibration frequencies, moments of inertia, and total and relative energies of the stablest conformers. Thermodynamic properties were calculated in the ideal gas state over the temperature range 0-1500 K. A thermodynamic analysis of mutual transformation processes (the formation of SS- and RS(meso)-lactides from S-lactic acid and the racemization of these lactides) and the formation of poly-(RS)-lactide from S-lactic acid and SS- and RS(meso)-lactides was performed.

Emel'Yanenko, V. N.; Verevkin, S. P.; Schick, C.; Stepurko, E. N.; Roganov, G. N.; Georgieva, M. K.

2010-09-01

113

Simplified curve fits for the thermodynamic properties of equilibrium air

NASA Technical Reports Server (NTRS)

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).

Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.

1986-01-01

114

Generalized thermodynamic and transport properties. II. Molecular liquids

NASA Astrophysics Data System (ADS)

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.

Bertolini, D.; Tani, A.

2011-03-01

115

ERIC Educational Resources Information Center

Reflecting widespread unhappiness with the growing tax burdens in this country, the most active area of litigation reported in the property chapter this year involves various attempts by taxpayers to prevent the construction or remodeling of public school facilities. While some taxpayers fought to keep schools from being built, others in New York…

Piele, Philip K.

116

ERIC Educational Resources Information Center

The author notes that controversies over construction bids and contracts continue to represent the largest number of property cases reported in this year's chapter. Most of these cases are routine disputes between colleges or universities and contractors over such issues as the return of bid bonds, recovery of additional costs for construction…

Piele, Philip K.

117

A COMPUTATIONAL STUDY IN THE THERMODYNAMIC AND DYNAMIC PROPERTIES OF ELECTRON TRANSFER PROTEINS

A COMPUTATIONAL STUDY IN THE THERMODYNAMIC AND DYNAMIC PROPERTIES OF ELECTRON TRANSFER PROTEINS IN THE THERMODYNAMIC AND DYNAMIC PROPERTIES OF ELECTRON TRANSFER PROTEINS by David N. LeBard has been approved December in plastocyanin. vi #12;TABLE OF CONTENTS Page CHAPTER 1 Overview of previous work

Thorpe, Michael

118

Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals

NASA Technical Reports Server (NTRS)

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.

Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.

1985-01-01

119

Thermodynamic properties of the particles interacting through smooth version of Stell-Hemmer interaction were studied using Wertheim's thermodynamic perturbation theory. The temperature dependence of molar volume, heat capacity, isothermal compressibility and thermal expansion coefficient at constant pressure for different number of bonding sites on particle were evaluated. The model showed water-like anomalies for all evaluated quantities, but thermodynamic perturbation theory does not properly predict the dependence of these properties at a fixed number of bonding points.

T. Urbic

2013-12-16

120

NASA Technical Reports Server (NTRS)

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.

Hansen, C Frederick; Heims, Steve P

1958-01-01

121

NASA Technical Reports Server (NTRS)

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.

Thompson, R. A.

1994-01-01

122

Thermodynamic properties of liquid ³3He-?4He mixtures between 0.15 K and 1.8 K

Thermodynamic property relations for liquid ³3He-?4He mixtures between temperatures of 0.15 K and 1.8 K are determined. The relations are valid over the entire concentration range. Thermodynamic properties are first ...

Chaudhry, Gunaranjan

2009-01-01

123

Thermodynamic properties of surface carbon on metals. 1. Nickel

Because of the role of surface carbon in catalytic hydrocarbon synthesis, the thermodynamic properties of surface carbon on alumina-supported nickel have been determined by measuring the equilibrium 2CO(g)in equilibriumC(a) + CO/sub 2/(g). For this reaction, the isosteric heat varies with surface coverage (theta) from -121 kJ-mol/sup -1/ at theta = 0.5 to -135 kJ-mol/sup -1/ at theta = 0.9. These values correspond to variations in the heat of formation of surface carbon relative to graphite from 52 kJ-mol/sup -1/ at low coverage to 35 kJ-mol/sup -1/ at high coverage. The surface carbon formed at temperatures below 600 K is highly reactive toward hydrogen as compared with a carbon deposit formed at higher temperatures. The experimental data indicate the presence of oxygen adatoms coadsorbed on the nickel surface. Their chemical potential is very low relative to bulk NiO. The heat of formation of O(a) exhibits little dependence on surface coverage. 9 figures, 2 tables.

Takeuchi, A.; Wise, H.

1983-12-22

124

Rhamnolipid surface thermodynamic properties and transport in agricultural soil.

Rhamnolipid is a biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension. Because of its biodegradability, rhamnolipid applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Subsequently, rhamnolipid applications have more advantages when used to improve irrigation in the agricultural soil, especially under draught conditions. In the presence of rhamnolipid, water surface tension dropped linearly with the increase of rhamnolipid concentration until the rhamnolipid critical micelle concentration (CMC) of 30 mg/L was reached. Below the CMC, rhamnolipid had linear adsorption isotherms on the soil with a partition coefficient of 0.126 L/kg. Rhamnolipid transport breakthrough curves had a broad and diffuse infiltration front, indicating retention of rhamnolipid on the soil increased with time. Rhamnolipid transport was found to be well represented by the advection-dispersion equation based on a local equilibrium assumption. When applied at concentrations above the CMC, the formed rhamnolipid micelles prevented rhamnolipid adsorption (both equilibrium adsorption and kinetic adsorption) in the soil. It was discovered in this research that rhamnolipid surface thermodynamic properties played the key role in controlling rhamnolipid transport. The attractive forces between rhamnolipid molecules contributed to micelle formation and facilitated rhamnolipid transport. PMID:24394947

Renfro, Tyler Dillard; Xie, Weijie; Yang, Guang; Chen, Gang

2014-03-01

125

Thermodynamic properties and thermometry of 1D Bose gases.

NASA Astrophysics Data System (ADS)

We investigate the thermodynamic properties of an array of independent 1D Bose gases formed by a two-dimensional optical lattice. In particular, we calculate the total entropy of the system and compare it with the respective result for the 3D Bose-Einstein condensate as a function of the temperature and the interaction strength. This allows us to analyze how the temperature of the system is altered upon an adiabatic transfer of the 3D gas into an array of 1D tubes. The calculation is based on the exact finite temperature solution for a uniform 1D Bose gas, combined with the local density approximation [1]. The results can be applied to the recent experimental measurements of the local pair correlations in 1D Bose gases [2], which potentially can include finite temperature effects and no fitting parameters. In addition, we point out that the pair correlation function can be used as a thermometer for 1D Bose gases, under conditions when the density profiles become insensitive to temperature changes. [1] K. V. Kheruntsyan, D. M. Gangardt, P. D. Drummond, G. V. Shlyapnikov, Phys. Rev. A 71, 053615 (2005). [2] T. Kinoshita, T. Wenger, D. S. Weiss, Phys. Rev. Lett. 95, 190406 (2005).

Kheruntsyan, Karen; Hu, Hui; Drummond, Peter

2006-05-01

126

Molecular Dynamics Simulation of Thermodynamic Properties in Uranium Dioxide

In the present study, we investigated the thermodynamic properties of uranium dioxide (UO2) by molecular dynamics (MD) simulations. As for solid UO2, the lattice parameter, density, and enthalpy obtained by MD simulations were in good agreement with existing experimental data and previous theoretical predictions. The calculated thermal conductivities matched the experiment results at the midtemperature range but were underestimated at very low and very high temperatures. The calculation results of mean square displacement represented the stability of uranium at all temperatures and the high mobility of oxygen toward 3000 K. By fitting the diffusivity constant of oxygen with the Vogel-Fulcher-Tamman law, we noticed a secondary phase transition near 2006.4 K, which can be identified as a ‘‘strong’’ to ‘‘fragile’’ supercooled liquid or glass phase transition in UO2. By fitting the oxygen diffusion constant with the Arrhenius equation, activation energies of 2.0 and 2.7 eV that we obtained were fairly close to the recommended values of 2.3 to 2.6 eV. Xiangyu Wang, Bin Wu, Fei Gao, Xin Li, Xin Sun, Mohammed A. Khaleel, Ademola V. Akinlalu and Li Liu

Wang, Xiangyu; Wu, Bin; Gao, Fei; Li, Xin; Sun, Xin; Khaleel, Mohammad A.; Akinlalu, Ademola V.; Liu, L.

2014-03-01

127

THERMODYNAMIC PROPERTIES OF SEA-SALTAEROSOLS A. C. Tridico and I. N. Tang

, (he hygroscopic properties of aerosolparticles generated from filtered sea-water sampleswere studiedBNL- 63377 [Abstract] THERMODYNAMIC PROPERTIES OF SEA-SALTAEROSOLS A. C. Tridico and I. N. Tang,FL Oct. 14-18, 1996 ABSTRACT The thennodynamic properties of mixed salt microdropletsrepresentativeof sea

128

NASA Technical Reports Server (NTRS)

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.

Svehla, R. A.; Mcbride, B. J.

1973-01-01

129

Thermodynamic properties of UF sub 6 measured with a ballistic piston compressor

NASA Technical Reports Server (NTRS)

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.

Sterritt, D. E.; Lalos, G. T.; Schneider, R. T.

1973-01-01

130

Thermodynamic and rheological properties of hard sphere dispersions

NASA Astrophysics Data System (ADS)

We investigate the thermodynamic and rheological properties of hard sphere dispersions with colloidal poly-(methyl methacrylate) particles grafted with a layer of poly-(12-hydroxy stearic acid) (PMMA-PHSA). These spheres are index-matched in a mixture of tetralin and decalin and the absorption of tetralin into the PMMA core is determined with light scattering. The effective hard sphere volume fraction is set by the disorder-order transition, thereby accounting for the polymer layer, any swelling due to the solvent, and polydispersity. The equation of state for the fluid phase, extracted from the equilibrium sediment with x-ray densitometry, conforms to the Carnahan-Starling equation. However, the osmotic pressure of the crystalline phase lies slightly above that calculated for a single FCC crystal. Likewise the high shear viscosity of the fluid compares well with other hard sphere dispersions, but the low shear viscosity for PMMA-PHSA hard spheres exceeds those for polystyrene and silica hard spheres. Our low shear viscosities are consistent with other PMMA-PHSA data after rescaling for both the polymer layer thickness and polydispersity. We use simple models and molecular dynamics simulations to determine that the higher osmotic pressure in the crystalline phase is a direct effect of polydispersity. Polydispersity appears to lower the crystalline close packed volume fraction. The random close packing is almost independent of polydispersity. We measure the high frequency shear modulus and dynamic viscosity for our PMMA-PHSA crystals by detecting the resonant response to oscillatory forcing with a novel dynamic light scattering scheme. The resonant response for colloidal crystals formed in normal and microgravity environments were similar, indicating that the bulk rheological properties are unaffected within experimental error by differing crystal structure and crystallite size. Our high frequency shear modulus seem reasonable, lying close to predictions for the static modulus of hard sphere crystals, whereas our high frequency dynamic viscosity seem high, exceeding measurements on the high frequency dynamic viscosity for metastable fluids. The measurements are in the linear regime for the shear modulus but may not be for the dynamic viscosity, which may explain our anomalously high dynamic viscosity.

Phan, See-Eng

1998-09-01

131

Tables of thermodynamic and transport properties of UO/sub 2/

The thermodynamic and transport properties of solid and liquid UO/sub 2/ are tabulated as a function of temperature. Properties are given for the temperature range 298.15 K to 3120 K for solid UO/sub 2/ and from 3120 to 6000 K for liquid UO/sub 2/. Thermodynamic properties tabulated include enthalpy, heat capacity, pressure, density, instantaneous thermal expansion coefficient, compressibility, thermal pressure coefficient, and speed of sound. Tabulated transport properties include thermal conductivity, thermal diffusivity, emissivity, electrical conductivity, and viscosity. Tables are given in SI units and cgs units.

Fink, J.K.

1982-06-01

132

The structural, dynamical, and thermodynamic properties of different carbon allotropes are computed using a combination of ab-initio methods: density-functional theory for total-energy calculations and density-functional ...

Mounet, Nicolas (Nicolas Frank)

2005-01-01

133

THERMODYNAMIC PROPERTIES OF MC (M = V, Nb, Ta): FIRST-PRINCIPLES CALCULATIONS

NASA Astrophysics Data System (ADS)

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.

Cao, Yong; Zhu, Jingchuan; Liu, Yong; Long, Zhishen

2013-07-01

134

AB INITIO ELASTIC AND THERMODYNAMIC PROPERTIES OF HIGH-TEMPERATURE CUBIC INTERMETALLICS AT FINITE TEMPERATURES A Thesis by MICHAEL ERIC WILLIAMS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 2008 Major Subject: Mechanical Engineering AB INITIO ELASTIC AND THERMODYNAMIC PROPERTIES OF HIGH-TEMPERATURE CUBIC INTERMETALLICS AT FINITE TEMPERATURES A Thesis by MICHAEL ERIC WILLIAMS Submitted...

Williams, Michael Eric

2009-05-15

135

WETAIR: A computer code for calculating thermodynamic and transport properties of air-water mixtures

NASA Technical Reports Server (NTRS)

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.

Fessler, T. E.

1979-01-01

136

NASA Technical Reports Server (NTRS)

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.

Nguyen, Huy H.; Martin, Michael A.

2003-01-01

137

Thermodynamic and transport property modeling in super critical water

Supercritical water oxidation (SCWO) is a thermally-based, remediation and waste-treatment process that relies on unique property changes of water when water is heated and pressurized above its critical point. Above its ...

Kutney, Michael C. (Michael Charles)

2005-01-01

138

EquilTheTA: Thermodynamic and transport properties of complex equilibrium plasmas

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.

Colonna, G.; D'Angola, A. [CNR-IMIP Bari, via Amendola 122/D - 70126 Bari (Italy); DIFA, Universita della Basilicata, via dell'Ateneo Lucano, 1085100 Potenza (Italy)

2012-11-27

139

Playing with Marbles: Structural and Thermodynamic Properties of Hard-Sphere Systems

These lecture notes present an overview of equilibrium statistical mechanics of classical fluids, with special applications to the structural and thermodynamic properties of systems made of particles interacting via the hard-sphere potential or closely related model potentials. The exact statistical-mechanical properties of one-dimensional systems, the issue of thermodynamic (in)consistency among different routes in the context of several approximate theories, and the construction of analytical or semi-analytical approximations for the structural properties are also addressed.

Andrés Santos

2013-10-21

140

Playing with Marbles: Structural and Thermodynamic Properties of Hard-Sphere Systems

These lecture notes present an overview of equilibrium statistical mechanics of classical fluids, with special applications to the structural and thermodynamic properties of systems made of particles interacting via the hard-sphere potential or closely related model potentials. The exact statistical-mechanical properties of one-dimensional systems, the issue of thermodynamic (in)consistency among different routes in the context of several approximate theories, and the construction of analytical or semi-analytical approximations for the structural properties are also addressed.

Santos, Andrés

2013-01-01

141

Gibbs: Phase equilibria and symbolic computation of thermodynamic properties

A general purpose open source, Python-based framework, Gibbs, is presented to perform multiphysical equilibrium calculations of material properties. The developed architecture allows to prototype symbolic and numerical representations of materials by starting from analytic models, tabulated experimental data, or Thermo-Calc data files. These constructions are based on the addition of arbitrary energy contributions that range from the traditional thermochemical to

Thomas Cool; Alexander Bartol; Matthew Kasenga; Kunal Modi; R. Edwin García

2010-01-01

142

Elastic and thermodynamic properties of AVO 3 (A=Sr, Pb) perovskites

NASA Astrophysics Data System (ADS)

We have investigated the elastic and thermodynamic properties for the perovskite type metavanadate SrVO 3 and the multiferroic PbVO 3, probably for the first time by the means of a Modified Rigid Ion Model (MRIM). We present the elastic constants ( C11,C12,C44) and other elastic properties like Bulk modulus ( B), Young?s modulus ( E), shear modulus ( G), Poisson?s ratio ( ?) and wave velocity ( ?l, ?s, ?m). Besides we have reported the thermodynamic properties molecular force constant ( f), Reststrahlen frequency ( ?), cohesive energy ( ?), Debye temperature ( ?D) and Gruneisen parameter ( ?). We have also computed the variation of heat capacity ( CP) and there by volume thermal expansion coefficient ( ?) in a wide temperature range. We found that the computed properties reproduce well with the available data in literature. To our knowledge some of the properties are reported for the first time.

Parveen, Atahar; Gaur, N. K.

2012-02-01

143

NASA Astrophysics Data System (ADS)

We present a system of analytical equations for computation of all thermodynamic properties of dry steam and liquid water (undesaturated, saturated and metastable supersaturated) and properties of the liquid-vapor phase interface. The form of the equations is such that it enables computation of all thermodynamic properties for independent variables directly related to the balanced quantities - total mass, liquid mass, energy, momenta. This makes it suitable for the solvers of fluid dynamics equations in the conservative form. Thermodynamic properties of dry steam and liquid water are formulated in terms of special thermodynamic potentials and all properties are obtained as analytical derivatives. For the surface tension, the IAPWS formula is used. The interfacial internal energy is derived from the surface tension and it is used in the energy balance. Unlike common models, the present one provides real (contrary to perfect gas approximation) properties of steam and water and reflects the energetic effects due to the surface tension. The equations are based on re-fitting the reference formulation IAPWS-95 and selected experimental data. The mathematical structure of the equations is optimized for fast computation.

Hrubý, Jan; Duška, Michal

2014-03-01

144

Thermodynamic properties of supercritical carbon dioxide: Widom and Frenkel lines

NASA Astrophysics Data System (ADS)

Supercritical fluids are widely used in a number of important technological applications, yet the theoretical progress in the field has been rather moderate. Fairly recently, a new understanding of the liquidlike and gaslike properties of supercritical fluids has come to the fore, particularly with the advent of the Widom and Frenkel lines that aim to demarcate different physical properties on the phase diagram. Here, we report the results of a computational study of supercritical carbon dioxide, one of the most important fluids in the chemical industry. We study the response functions of CO2 in the supercritical state and calculate the locations of their maxima (Widom lines). We also report the preliminary calculations of the Frenkel line, the line of crossover of microscopic dynamics of particles. Our insights are relevant to physical processes in the atmosphere of Venus and its evolution.

Fomin, Yu. D.; Ryzhov, V. N.; Tsiok, E. N.; Brazhkin, V. V.

2015-02-01

145

Generalizing thermodynamic properties of bulk single-walled carbon nanotubes

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

Rodriguez, Kenneth R.; Nanney, Warren A.; A. Maddux, Cassandra J.; Martínez, Hernán L.

2014-01-01

146

A Thermodynamic Property Model for Fluid-Phase Isobutane

A Helmholtz free energy equation of state for the fluid phase of isobutane (R-600a) has been developed on the basis of the ITS-90 temperature scale. This model was developed using selected measurements of the pressure–density–temperature (P, ?, T), isobaric heat capacity, speed of sound, and saturation properties. The structure of the present model consists of only 19 terms in its functional form,

H. Miyamoto; K. Watanabe

2002-01-01

147

The polycyclic aromatic hydrocarbons can be organized into an infinite number of series in each of which successive isomer groups differ by C4H2. The first series starts with benzene, and chemical thermodynamic tables are presented here for C6H6, C10H8, C14H10, C18H12, C22H14, and C26H16 in the ideal gas phase. Since chemical thermodynamic properties are known for only several polycyclic aromatic

Robert A. Alberty; Andrea K. Reif

1988-01-01

148

Thermodynamics and surface properties of liquid Ga-X (X = Sn, Zn) alloys

The mixing behaviour of Ga-Sn and Ga-Zn segregating alloy systems has been investigated by the Quasi-Chemical Approximation\\u000a (QCA) in the frame of the Quasi-Lattice Theory (QLT) combined with a statistical mechanical theory. Assuming the order energy\\u000a parameters as temperature dependent, various thermodynamic quantities are calculated at different temperatures. Thermodynamic\\u000a properties of both systems deviate positively from the Raoult’s law. The

R. Novakovic; D. Zivkovic

2005-01-01

149

NASA Astrophysics Data System (ADS)

In this paper, we show, by using the approach of effective mass, that the model of a two-dimensional Dirac oscillator can be used to describe the thermodynamic properties of graphene under a uniform magnetic field. All thermodynamic quantities of graphene, such as the free energy, the mean energy, the entropy and the specific heat, have been found by using an approach based on the zeta function.

Boumali, Abdelmalek

2015-04-01

150

Thermodynamic properties of sophocarpine and oxysophocarpine alkaloids in aqueous glucose solutions

NASA Astrophysics Data System (ADS)

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.

Li, Zongxiao; Zhao, Weiwei; Pu, Xiaohua

2012-04-01

151

NASA Technical Reports Server (NTRS)

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.

Thompson, Richard A.; Lee, Kam-Pui; Gupta, Roop N.

1990-01-01

152

Nonlinear thermodynamic quantum master equation: Properties and examples

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.

Oettinger, Hans Christian [ETH Zuerich, Department of Materials, Polymer Physics, HCI H 543, CH-8093 Zuerich (Switzerland)

2010-11-15

153

Experimental verification of the thermodynamic properties for a jet-A fuel

NASA Technical Reports Server (NTRS)

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.

Graciasalcedo, Carmen M.; Brabbs, Theodore A.; Mcbride, Bonnie J.

1988-01-01

154

NASA Astrophysics Data System (ADS)

A scaled fundamental equation for the thermodynamic properties of carbon dioxide is derived which supplements the global analytic fundamental equation of Ely et al. for CO2 by providing an accurate representation of the thermodynamic properties in the close vicinity of the critical point. Specifically, the use of a scaled equation is necessary to accomodate the experimentally observed divergent behavior of the specific heat. The equation is obtained by combining the experimental pressure data of Michels et al. (1935, 1937) with new specific heat data.

Albright, P. C.; Edwards, T. J.; Chen, Z. Y.; Sengers, J. V.

1987-08-01

155

Exploring the effect of anharmonicity of molecular vibrations on thermodynamic properties.

Thermodynamic properties of selected small and medium size molecules were calculated using harmonic and anharmonic vibrational frequencies. Harmonic vibrational frequencies were obtained by normal mode analysis, whereas anharmonic ones were calculated using the vibrational self-consistent field (VSCF) method. The calculated and available experimental thermodynamic data for zero point energy, enthalpy, entropy, and heat capacity are compared. It is found that the anharmonicity and coupling of molecular vibrations can play a significant role in predicting accurate thermodynamic quantities. Limitations of the current VSCF method for low frequency modes have been partially removed by following normal mode displacements in internal, rather than Cartesian, coordinates. PMID:17176129

Njegic, Bosiljka; Gordon, Mark S

2006-12-14

156

Exploring the effect of anharmonicity of molecular vibrations on thermodynamic properties

NASA Astrophysics Data System (ADS)

Thermodynamic properties of selected small and medium size molecules were calculated using harmonic and anharmonic vibrational frequencies. Harmonic vibrational frequencies were obtained by normal mode analysis, whereas anharmonic ones were calculated using the vibrational self-consistent field (VSCF) method. The calculated and available experimental thermodynamic data for zero point energy, enthalpy, entropy, and heat capacity are compared. It is found that the anharmonicity and coupling of molecular vibrations can play a significant role in predicting accurate thermodynamic quantities. Limitations of the current VSCF method for low frequency modes have been partially removed by following normal mode displacements in internal, rather than Cartesian, coordinates.

Njegic, Bosiljka; Gordon, Mark S.

2006-12-01

157

Thermodynamic properties of almandine-grossular garnet solid solutions

The mixing properties of Fe3Al2Si3O12-Ca3Al2Si3O12 garnet solid solutions have been studied in the temperature range 850–1100° C. The experimental method involves measuring the composition of garnet in equilibrium with an assemblage in which the activity of the Ca3Al2Si3O12 component is fixed. Experiments on the assemblage garnet solid solution, anorthite, Al2SiO5 polymorph and quartz at known pressure and temperature fix the

G. Cressey; R. Schmid; B. J. Wood

1978-01-01

158

Thermodynamic property modeling for 2,3,3,3-tetrafluoropropene (HFO1234yf)

This paper presents a timely and reliable equation of state for 2,3,3,3-tetrafluoropropene (HFO-1234yf) whose thermodynamic property information is strongly desired. The Patel–Teja (PT) equation of state and the extended corresponding state (ECS) model have been individually applied to property modeling for this new refrigerant. Comparisons of predicted values with the equation\\/model were made with the most recent experimental data. Both

Ryo Akasaka; Katsuyuki Tanaka; Yukihiro Higashi

2010-01-01

159

The thermodynamic properties ?Gho,?Hho, and ?Cp,hoassociated with the transfer of non-ionic organic compounds from gas to dilute aqueous solution and the limiting partial molar properties Cpo,2 and V22 of these compounds in water are described through a simple scheme of group contributions. A distinction is made between groups made only of carbon and hydrogen, and functional groups i.e. groups containing

Sergio Cabani; Paolo Gianni; Vincenzo Mollica; Luciano Lepori

1981-01-01

160

Properties of the largest fragment in multifragmentation: A canonical thermodynamic calculation

Many calculations for the production of light and intermediate particles resulting from heavy ion collisions at intermediate energies exist. Calculations of properties of the largest fragment resulting from multifragmentation are rare. In this paper we compute these properties and compare them with the data for the case of gold on carbon. We use the canonical thermodynamic model. The model also gives a bimodal distribution for the largest fragment in a narrow energy range.

Chaudhuri, G.; Gupta, S. Das [Physics Department, McGill University, Montreal, H3A 2T8 (Canada)

2007-03-15

161

Precise thermodynamic properties for natural waters covering only the limnological range

Dissolved salts affect the thermodynamic properties of lake waters. Equations are given to calculate the following properties over the range of 0-0.6 salinity, 0/sup 0/-30/sup 0/C, and 0-180 bars: density, thermal expansibility, temperature of maximum density, maximum density and minimum specific volume, isothermal compressibility, specific heat at constant pressure, specific heat at constant volume, sound speed, adiabatic compressibility, freezing point, adiabatic temperature gradient, and static stability.

Chen, C.T.A.; Millero, F.J.

1986-05-01

162

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.

Duan, Yuhua

2012-11-02

163

Symmetry, Optical Properties and Thermodynamics of Neptunium(V) Complexes

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.

Rao, Linfeng; Tian, Guoxin

2009-12-21

164

Thermodynamic Properties for A Drop-in Refrigerant R-SP34E

NASA Astrophysics Data System (ADS)

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.

Kayukawa, Yohei; Hondo, Takashi; Watanabe, Koichi

165

NASA Astrophysics Data System (ADS)

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.

Satoh, Katsuhiko

2013-08-01

166

Representation of standard chemical thermodynamic properties of isomer groups by equations

Since the standard chemical thermodynamic properties of isomer groups in a homologous series are found to be linear functions of the number of carbon atoms, the number of parameters required to represent them as a function of temperature and carbon number is greatly reduced. The existing tables for C{sub p}{sup 0}(I{sub n}), S{sup 0}(I{sub n}), and the enthalpy of formation of the isomer group I{sub n} at temperature T with respect to the elements at 298.15 K for seven isomer groups of the alkylbenzenes (C{sub 6}H{sub 6} to C{sub 12}H{sub 18}) from 298.15 to 1000 K have been fitted by least squares to a set of equations containing 12 parameters. These parameters, plus five each for graphite and molecular hydrogen, can be used to calculate all of the standard chemical thermodynamic properties of these isomer groups in the ideal gas state. This makes it convenient to calculate the various thermodynamic properties for any carbon number and temperature in the range used, and also to estimate thermodynamic properties at carbon numbers higher than 12.

Alberty, R.A.; Chou, Kuochih (Massachusetts Institute of Technology, Cambridge (USA))

1990-02-22

167

The data on thermodynamic and molecular properties of the potassium, rubidium and cesium hydroxides have been collected, critically reviewed, analyzed, and evaluated. Tables of the thermodynamic properties [C{sub p}{sup {circ}}, {Phi}{degree}={minus}(G{degree}{minus}H{degree}(0)/T, S{degree}, H{degree}{minus}H{degree}(0), {Delta}{sub f}H{degree}, {Delta}{sub f}G{degree})] of these hydroxides in the condensed and gaseous states have been calculated using the results of the analysis and some estimated values. The recommendations are compared with earlier evaluations given in the JANAF Thermochemical Tables and Thermodynamic Properties of Individual Substances. The properties considered are: the temperature and enthalpy of phase transitions and fusion, heat capacities, spectroscopic data, structures, bond energies, and enthalpies of formation at 298.15 K. The thermodynamic functions in solid, liquid, and gaseous states are calculated from T=0 to 2000 K for substances in condensed phase and up to 6000 K for gases. {copyright} {ital 1997 American Institute of Physics and American Chemical Society.}

Gurvich, L.V.; Bergman, G.A.; Gorokhov, L.N.; Iorish, V.S.; Leonidov, V.Y.; Yungman, V.S. [Thermocenter of the Russian Academy of Sciences, Izhorskaya st. 13/19, IVTAN, Moscow 127412 (Russia)

1997-07-01

168

PLASMA THERMODYNAMICS. I. PROPERTIES OF HYDROGEN, HELIUM, AND LITHIUM AS PURE ELEMENTAL PLASMAS

The problem of computing the thermodynamic properties of a plasma ; composed of atoms, atomie ions, and electrons is examined from an initially ; rigorous point of view. Sufficient detail of the subsequent approximations that ; are required to develop a tractable physical model are presented to indicate the ; major problem areas and the optimum approximations that permit a

H. A. Jr. McGee; G. Heller

1962-01-01

169

NIST Standard Reference Database 23 NIST Reference Fluid Thermodynamic and Transport Properties--

#12;NIST Standard Reference Database 23 NIST Reference Fluid Thermodynamic and Transport Properties (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes

Magee, Joseph W.

170

Accuracy Based Generation of Thermodynamic Properties for Light Water in RELAP5-3D

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

Cliff B. Davis

2010-01-01

171

A simple program to determine the reaction rate and thermodynamic properties of reacting system

A simple program to determine the reaction rate and thermodynamic properties of reacting system program to determine the reaction rate by using conventional transition state theory with the Wigner in the reaction NH3 þ H ! NH2 þ H2 is used as a model to demonstrate the program usage. The rate constants have

172

The thermodynamic properties of Davydov-Scott's protein model in thermal bath

The thermodynamic properties of Davydov-Scott monomer contacting with thermal bath is investigated using Lindblad open quantum system formalism. The Lindblad equation is investigated through path integral method. It is found that the environmental effects contribute destructively to the specific heat, and large interaction between amide-I and amide-site is not preferred for a stable Davydov-Scott monomer.

Sulaiman, A; Alatas, H; Handoko, L T; 10.1142/9789814335614_0072

2011-01-01

173

Nano, Quantum, and Statistical Mechanics and Thermodynamics: Data and Property Calculation Websites

NSDL National Science Digital Library

This collection of links provides access to web sites associated with nano, quantum, and statistical mechanics and thermodynamics. The links are arranged by type: data sites, calculation/program download sites, organizations involved with data compilation and property calculation, and bibliographies.

174

Phase Diagrams and Thermodynamic Properties of Metals at High Pressures, High Temperatures

Information on phase diagrams and thermodynamic properties of metals includes results of numerous static, dynamic experiments and theoretical calculations. Multi-phase equations of state (EOS) have been used to analyze all of these data. The EOS obtained for 30 simple and transition metals account for solid, liquid, gas and plasma states as well as two-phase regions of melting and evaporating. The

I. V. Lomonosov; V. E. Fortov; K. V. Khishchenko; P. R. Levashov

2001-01-01

175

Monte Carlo calculations are carried out to give exact values of some thermodynamic properties of alloys. The calculations are performed within the framework of the surrounded atom model the main assumptions of which are: quasilattice structure of the alloy, nearest neighbour interactions, description of the configuration in terms of ''surrounded atoms''. The results are then compared wit those obtained using

C. Bichara; C. Bergman; J.-C. Mathieu

1985-01-01

176

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of State

NSDL National Science Digital Library

Cubic equations of state are widely used by chemists and chemical engineers to predict the thermodynamic properties of both pure substances and mixtures. In particular, these equations enable predictions concerning the temperature and pressure at which vapor liquid equilibrium occurs. These two educational JavaScript programs perform calculations using cubic equations of state and, equally importantly, explain how the calculations are performed.

177

Hypothetical Thermodynamic Properties: The Boiling and Critical Temperatures of Polyethylene. Louis, Missouri 63121 The normal (p ) 101.325 kPa) boiling-temperature behavior of a homologous series and approximately TB() ) 915 K for those related to polytetrafluoroethylene. Normal boiling temperatures have been

Chickos, James S.

178

Thermodynamic properties of ethylene and water in the critical region

The thermodynamic tables of ethylene and water were revised in the critical region. The new tables are consistent with the Hall-Eubank formulation and are compatible with recent experimental measurements. An isochoric equation of state (EOS) was perfected for the single-phase region neqr the critical point (CP). Starting at the vapor-liquid coexistence curve, the EOS has an initial slope consistent with

M. S. Nehzat

1978-01-01

179

Thermodynamic properties of some gallium-based binary alloys

We have studied the concentration dependence of the free energy of mixing, concentration–concentration fluctuations in the long-wavelength limit, the chemical short-range order parameter, the enthalpy and entropy of mixing of Ga–Zn, Ga–Mg and Al–Ga binary alloys at different temperatures using a quasi-chemical approximation for compound forming binary alloys and that for simple regular alloys. From the study of the thermodynamic

O. E. Awe; Y. A. Odusote; O. Akinlade; L. A. Hussain

2008-01-01

180

Cyclodextrin glycosyltransferase (CGTase) was covalently coupled to five oxidized polysaccharides differing in structure and chemical nature. The conjugates were evaluated for the retained activity, kinetic and thermodynamic stability. The conjugated CGTase with oxidized dextran (MW 47000) had the highest retained specific activity (70.05%) and the highest half-life (T1/2) at 80°C. Compared to the native enzyme, the conjugated preparation exhibited higher optimum temperature, lower activation energy (Ea), lower deactivation constant rate (kd), higher T1/2, and higher D values (decimal reduction time) within the temperature range of 60-80°C. The values of thermodynamic parameters for irreversible inactivation of native and conjugated CGTase indicated that conjugation significantly decreased entropy (?S*) and enthalpy of deactivation (?H*). The results of thermodynamic analysis for cyclodextrin production from starch indicated that The enthalpy of activation (?H*) and free energy of activation (?G*), (free energy of transition state) ?G*E-T and (free energy of substrate binding) ?G*E-S values were lower for the conjugated CGTase. Similarly, there was significant impact on improvement of kcat, kcat/Km values. Both native and conjugated enzyme produce ?-cyclodextrin from starch. PMID:25709024

Abdel-Naby, Mohamed A; Fouad, Ahmed A; El-Refai, H A

2015-05-01

181

Thermodynamic properties of an evaporation process in self-gravitating N -body systems.

By means of N -body simulations, we consider self-gravitating open systems enclosed in a spherical container with semipermeable reflecting walls, in order to investigate the thermodynamics of the evaporation process in self-gravitating N -body systems (such as the escape of stars from globular clusters). To simulate the evaporation process, when the energy of a particle exceeds a certain threshold value, the particle passes through the semipermeable reflecting wall freely. We show that the thermodynamic properties of the evaporation process, such as the dependence of the temperature on energy, agree well with those of stellar polytropes, if the system is in an approximate virial equilibrium state. However, in a lower-energy region or for a rapid evaporation process, the thermodynamic properties deviate from those for the stellar polytrope. Nevertheless, we found that a negative specific heat occurs even in the lower-energy region or for a rapid evaporation process. PMID:20866786

Komatsu, Nobuyoshi; Kiwata, Takahiro; Kimura, Shigeo

2010-08-01

182

The thermodynamic properties of 2-methylaniline and trans-(R,S)- decahydroquinoline

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.

Steele, W.V.; Chirico, R.D.; Nguyen, A.; Knipmeyer, S.E.

1990-02-01

183

Thermodynamic Properties of Spherically-Symmetric, Uniformly-Accelerated Reference Frames

We aim to study the thermodynamic properties of the spherically symmetric reference frames with uniform acceleration, including the spherically symmetric generalization of Rindler reference frame and the new kind of uniformly accelerated reference frame. We find that, unlike the general studies about the horizon thermodynamics, one cannot obtain the laws of thermodynamics for their horizons in the usual approaches, despite that one can formally define an area entropy (Bekenstein-Hawking entropy). In fact, the common horizon for a set of uniformly accelerated observers is not always exist, even though the Hawking-Unruh temperature is still well-defined. This result indicates that the Hawking-Unruh temperature is only a kinematic effect, to gain the laws of thermodynamics for the horizon, one needs the help of dynamics. Our result is in accordance with those from the various studies about the acoustic black holes.

Chao-Guang Huang; Jia-Rui Sun

2007-01-15

184

Thermodynamic and mechanical properties of TiC from ab initio calculation

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.

Dang, D. Y.; Fan, J. L.; Gong, H. R., E-mail: gonghr@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2014-07-21

185

Self-consistent calculations of the dynamic and thermodynamic properties of solid helium

NASA Astrophysics Data System (ADS)

The results of studies of physical properties of quantum crystals i.e. b.c.c. 3He and h.c.p. 4He in the reduced, all neighbors approximation of the self-consistent phonon theory (SCPT) are presented. The system of equations describing the temperature and pressure variations of the dynamic and thermodynamic quantities for these crystals has been solved for the best grounded theoretically, in the case of solid helium, the renormalized potential: the generalized version of the (exp,m) Buckingham, the (n,m) Lennard-Jones and the (exp,exp) Morse. Optimal values of the potential constants have been calculated with the help of self-consistently method using experimental data for the zero-point properties: the internal energy, volume, compressibility and the Debye'a characteristic temperature determined at low temperature. The obtained potential functions parameters were in turn used to calculate the dynamic and thermodynamic properties of solid helium.

Malinowska-Adamska, Cecylia; Sloma, Piotr

2003-10-01

186

Performance of the thermodynamic properties models in ASPEN. [Freon 12 and Freon 22

In the course of performing a number of analyses using ASPEN, the performance of the ASPEN models for computing thermodynamic properties has been observed. Pure-component properties for propane, isobutane, Freon 12 and Freon 22 and mixture properties for the propane-isobutane and the ethanol-water systems have been computed and the results compared with available data sources and with independent sources of computed properties. The built-in data regression system (DRS) of ASPEN was used to regress P-V-T and enthalpy departure data for isobutane to determine model-specific parameters. The extended Antoine vapor pressure parameters were calculated for Freon 12. The ethanol-water vapor-liquid equilibrium region was studied throughout the composition range for three isobaric data sets. Several activity coefficient models in ASPEN were fit to the data using various user-specified property routes.

Fish, L.W.; Evans, D.R.

1982-01-01

187

Metastable Solution Thermodynamic Properties and Crystal Growth Kinetics

NASA Technical Reports Server (NTRS)

The crystal growth rates of NH4H2PO4, KH2PO4, (NH4)2SO4, KAl(SO4)2 central dot 12H2O, NaCl, and glycine and the nucleation rates of KBr, KCl, NaBr central dot 2H2O, (NH4)2Cl, and (NH4)2SO4 were expressed in terms of the fundamental driving force of crystallization calculated from the activity of supersaturated solutions. The kinetic parameters were compared with those from the commonly used kinetic expression based on the concentration difference. From the viewpoint of thermodynamics, rate expressions based on the chemical potential difference provide accurate kinetic representation over a broad range of supersaturation. The rates estimated using the expression based on the concentration difference coincide with the true rates of crystallization only in the concentration range of low supersaturation and deviate from the true kinetics as the supersaturation increases.

Kim, Soojin; Myerson, Allan S.

1996-01-01

188

Thermodynamic properties of mesoscale convective systems observed during BAMEX

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.

Correia, James; Arritt, R.

2008-11-01

189

Thermodynamic properties of some metal oxide-zirconia systems

NASA Technical Reports Server (NTRS)

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.

Jacobson, Nathan S.

1989-01-01

190

Thermodynamical properties of topological Born-Infeld-dilaton black holes

We examine the $(n+1)$-dimensional $(n\\geq3)$ action in which gravity is coupled to the Born-Infeld nonlinear electrodynamic and a dilaton field. We construct a new $(n+1)$-dimensional analytic solution of this theory in the presence of Liouville-type dilaton potentials. These solutions which describe charged topological dilaton black holes with nonlinear electrodynamics, have unusual asymptotics. They are neither asymptotically flat nor (anti)-de Sitter. The event horizons of these black holes can be an $(n-1)$-dimensional positive, zero or negative constant curvature hypersurface. We also analyze thermodynamics and stability of these solutions and disclose the effect of the dilaton and Born-Infeld fields on the thermal stability in the canonical ensemble.

Ahmad Sheykhi

2008-01-27

191

Thermodynamic and fluid properties of cells, tissues and membranes

NASA Astrophysics Data System (ADS)

This dissertation studies cellular rearrangements in tissues and attempts to establish the role of physical properties of cells, tissues and membranes in several biological phenomena. Using experiments and statistical mechanical modeling, we study cell sorting, tissue engulfment, single cell motion and membrane fluctuations. When cells of two different types are mixed together, they sort out, with the less cohesive tissue surrounding the more cohesive one. This sorting out resembles the phase separation of a mixture of immiscible liquids. We have measured the rate of sorting in tissues and compared it with a cellular automaton based model of cell aggregates. We have also established that cell sorting agrees well with the theory for phase separating fluids. Engulfment is the spreading of one type of tissue over the surface of another tissue placed adjacent to it. Differences in adhesion cause an imbalance of surface tension forces which drives tissue spreading. We have quantitatively studied engulfment between different tissue types and compared the experimental rate with results from computer simulations and a liquid model. Our results suggest that simple physical principles can model tissue motion. Studying the motion of single cells in aggregates is important to understanding the overall pattern formation in tissues. We characterized cell motion in different types of adhesive aggregates to elucidate the role of adhesion in cell motion. We also observed that the cells exhibited a novel type of statistics including correlations and collective motion. Membrane deformations of cells played a negligible role in large scale cell motion. Our results indicate the importance of correlated motion for cells to move long distances in tissues. At the single cell level, tension of the cell membrane and intracellular membrane can play an important role in cell shape changes, regulation of cell motility and membrane dynamics. We used optical tweezers to measure the membrane tension of tubulo-vesicular networks obtained from Golgi and Endoplasmic Reticulum (ER) membranes within cells. As expected on the basis of some previous experiments, the ER has a higher membrane tension than the Golgi.

Upadhyaya, Arpita

2000-10-01

192

Structure-property relations and thermodynamic properties of monoclinic petalite, LiAlSi4O10

NASA Astrophysics Data System (ADS)

Structure-property relations of monoclinic petalite, LiAlSi4O10, were determined by experiment and atomistic modeling based on density functional theory. The elastic stiffness coefficients were measured between room temperature and 570 K using a combination of the plate-resonance technique and resonant ultrasound spectroscopy. The thermal expansion was studied between 100 and 740 K by means of dilatometry. The heat capacity between 2 and 398 K has been obtained by microcalorimetry using a quasi-adiabatic calorimeter. The experimentally determined elastic stiffness coefficients were employed to benchmark the results of density functional theory based model calculations. The values in the two data sets agreed to within a few GPa and the anisotropy was very well reproduced. The atomistic model was then employed to predict electric field gradients, the lattice dynamics and thermodynamic properties. The theoretical charge density was analyzed to investigate the bonding between atoms.

Haussühl, Eiken; Schreuer, Jürgen; Winkler, Björn; Haussühl, Siegfried; Bayarjargal, Lkhamsuren; Milman, Victor

2012-08-01

193

Structure-property relations and thermodynamic properties of monoclinic petalite, LiAlSi4O10.

Structure-property relations of monoclinic petalite, LiAlSi(4)O(10), were determined by experiment and atomistic modeling based on density functional theory. The elastic stiffness coefficients were measured between room temperature and 570 K using a combination of the plate-resonance technique and resonant ultrasound spectroscopy. The thermal expansion was studied between 100 and 740 K by means of dilatometry. The heat capacity between 2 and 398 K has been obtained by microcalorimetry using a quasi-adiabatic calorimeter. The experimentally determined elastic stiffness coefficients were employed to benchmark the results of density functional theory based model calculations. The values in the two data sets agreed to within a few GPa and the anisotropy was very well reproduced. The atomistic model was then employed to predict electric field gradients, the lattice dynamics and thermodynamic properties. The theoretical charge density was analyzed to investigate the bonding between atoms. PMID:22871989

Haussühl, Eiken; Schreuer, Jürgen; Winkler, Björn; Haussühl, Siegfried; Bayarjargal, Lkhamsuren; Milman, Victor

2012-08-29

194

NASA Astrophysics Data System (ADS)

This paper calculates the elastic, thermodynamic and electronic properties of pyrite (Pabar 3) RuO2 by the plane-wave pseudopotential density functional theory (DFT) method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.

Yang, Ze-Jin; Guo, Yun-Dong; Wang, Guang-Chang; Li, Jin; Dai, Wei; Liu, Jin-Chao; Cheng, Xin-Lu; Yang, Xiang-Dong

2009-11-01

195

Thermodynamical Properties of Apparent Horizon in Warped DGP Braneworld

In this paper we first obtain Friedmann equations for the $(n-1)$-dimensional brane embedded in the $(n+1)$-dimensional bulk, with intrinsic curvature term of the brane included in the action (DGP model). Then, we show that one can always rewrite the Friedmann equations in the form of the first law of thermodynamics, $dE=TdS+WdV$, at apparent horizon on the brane, regardless of whether there is the intrinsic curvature term on the brane or a cosmological constant in the bulk. Using the first law, we extract the entropy expression of the apparent horizon on the brane. We also show that in the case without the intrinsic curvature term, the entropy expressions are the same by using the apparent horizon on the brane and by using the bulk geometry. When the intrinsic curvature appears, the entropy of apparent horizon on the brane has two parts, one part follows the $n$-dimensional area formula on the brane, and the other part is the same as the entropy in the case without the intrinsic curvature term. As an interesting result, in the warped DGP model, the entropy expression in the bulk and on the brane are not the same. This is reasonable, since in this model gravity on the brane has two parts, one induced from the $(n+1)$-dimensional bulk gravity and the other due to the intrinsic curvature term on the brane.

Ahmad Sheykhi; Bin Wang; Rong-Gen Cai

2007-04-30

196

NASA Technical Reports Server (NTRS)

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.

Mccarty, R. D.

1980-01-01

197

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)

Perruchot, Christian [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Chehimi, Mohamed M. [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Vaulay, Marie-Josephe [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Benzarti, Karim [Laboratoire Central des Ponts et Chaussees (LCPC), 58 Boulevard Lefevre, 75732 Paris Cedex 15 (France)]. E-mail: benzarti@lcpc.fr

2006-02-15

198

Thermodynamic properties and atomic structure of Ca-based liquid alloys

NASA Astrophysics Data System (ADS)

To identify the most promising positive electrodes for Ca-based liquid metal batteries, the thermodynamic properties of diverse Ca-based liquid alloys were investigated. The thermodynamic properties of Ca-Sb alloys were determined by emf measurements. It was found that Sb as positive electrode would provide the highest voltage for Ca-based liquid metal batteries (1 V). The price of such a battery would be competitive for the grid-scale energy storage market. The impact of Pb, a natural impurity of Sb, was predicted successfully and confirmed via electrochemical measurements. It was shown that the impact on the open circuit voltage would be minor. Indeed, the interaction between Ca and Sb was demonstrated to be much stronger than between Ca and Pb using thermodynamic modeling, which explains why the partial thermodynamic properties of Ca would not vary much with the addition of Pb to Sb. However, the usage of the positive electrode would be reduced, which would limit the interest of a Pb-Sb positive electrode. Throughout this work, the molecular interaction volume model (MIVM) was used for the first time for alloys with thermodynamic properties showing strong negative deviation from ideality. This model showed that systems such as Ca-Sb have strong short-range order: Ca is most stable when its first nearest neighbors are Sb. This is consistent with what the more traditional thermodynamic model, the regular association model, would predict. The advantages of the MIVM are the absence of assumption regarding the composition of an associate, and the reduced number of fitting parameters (2 instead of 5). Based on the parameters derived from the thermodynamic modeling using the MIVM, a new potential of mixing for liquid alloys was defined to compare the strength of interaction in different Ca-based alloys. Comparing this trend with the strength of interaction in the solid state of these systems (assessed by the energy of formation of the intermetallics), the systems with the most stable intermetallics were found to have the strongest interaction in the liquid state. Eventually, a new criteria was formulated to select electrode materials for liquid metal batteries. Systems with the most stable intermetallics, which can be evaluated by the enthalpy of formation of these systems, will yield the highest voltage when assembled as positive and negative electrodes in a liquid metal battery. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

Poizeau, Sophie

199

Thermodynamic properties of liquid Au–Cu–Sn alloys determined from electromotive force measurements

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

Guo, Zhongnan; Hindler, Michael; Yuan, Wenxia; Mikula, Adolf

2011-01-01

200

Numerical prediction of the thermodynamic properties of ternary Al-Ni-Hf alloys

Thermodynamic properties of ternary Al-Hf-Ni system, such as {sup ex}G, ?{sub Al}, ?{sub Ni} and ?{sub Zr} at 1373K were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting {sup ex}G values was regarded as the calculation of excess Gibbs energy values inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of {sup ex}G on all legs of the triangle are known. {sup ex}G and L{sub ijk} ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism are calculated numerically using Wolfram Mathematica 9 software.

Romanowska, Jolanta; Kotowski, S?awomir; Zagula-Yavorska, Maryana [Rzeszów University of Technology (Poland)

2014-10-06

201

Elastic and thermodynamic properties of TiC from first-principles calculations

NASA Astrophysics Data System (ADS)

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.

Li, Yanhong; Wang, Wanfeng; Zhu, Bo; Xu, Ming; Zhu, Jun; Hao, Yanjun; Li, Weihu; Long, Xiaojiang

2011-12-01

202

Pressure effect on structural, elastic, and thermodynamic properties of tetragonal B4C4

NASA Astrophysics Data System (ADS)

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.

Zheng, Baobing; Zhang, Meiguang; Luo, Hong-Gang

2015-03-01

203

First-principles study on the lattice dynamics and thermodynamic properties of Cu2GeSe3

NASA Astrophysics Data System (ADS)

The lattice dynamics and thermodynamic properties of Cu2GeSe3 are investigated by first-principles calculations. The obtained phonon frequencies agree well with the measurements of Raman scattering. The thermodynamic properties are calculated within quasi-harmonic approximation, and the measured lattice thermal conductivity is well reproduced. The calculated Grüneisen parameter is found to be much smaller than previous prediction, indicating that the bonding anharmonicity is insufficient to explain the low thermal conductivity in Cu2GeSe3. Our study shows that the thermodynamic properties of Cu2GeSe3 are inherently related to its weak covalent Cu-Se bonding.

Shao, Hezhu; Tan, Xiaojian; Hu, Tianqi; Liu, Guo-Qiang; Jiang, Jun; Jiang, Haochuan

2015-02-01

204

Accuracy Based Generation of Thermodynamic Properties for Light Water in RELAP5-3D

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.

Cliff B. Davis

2010-09-01

205

NASA Astrophysics Data System (ADS)

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.

Noh, Seunghyo; Kwak, Dohyun; Lee, Juseung; Kang, Joonhee; Han, Byungchan

2014-03-01

206

The equation of state and thermodynamic properties of liquid carbon monoxide

Experimental results of p,V,T measurements on liquid carbon monoxide at temperatures from near the normal boiling point to 125 K and at pressures between the vapor pressure and 140 MPa, at regular intervals of these two variables are given. Experimental p, V, T measurements are shown in charts and graphs. Vapor pressure correlation and derived quantities are shown with detailed tables on thermodynamic properties of liquid and gaseous CO.

Barreiros, S.F.; da Ponte, M.N.; Calado, J.C.G.; Streett, W.B.

1982-01-01

207

NASA Technical Reports Server (NTRS)

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.

Younglove, B.; Mccarty, R. D.

1979-01-01

208

The stoichiometry and thermodynamic properties of As (III) hydroxide complexes were determined from both solubility and Raman spectroscopic measurements. Arsenolite, claudetite, and orpiment solubilities were measured at temperatures to 250 and 300 °C, respectively, in acid solutions (pH < 6) at the saturated vapor pressure of the system. Raman spectroscopic measurements were performed on As2O3-H2O solutions (0.02 ? As ?

Gleb Pokrovski; Robert Gout; Jacques Schott; Alexandre Zotov; Jean-Claude Harrichoury

1996-01-01

209

Ideals gas thermodynamic properties and isomerization of n-butane and isobutane

Reported Values of Structural parameters, vibrational fundamentals, and potential energy functions for internal rotation of n-butane and isobutane are reviewed. The selected values were used to calculate the thermodynamic properties (C°p, S°, (H°-H°0)\\/T) in the temperature range of O to model. Contributions of internal rotation were evaluated by the direct sum of terms containing energy levels which were calculated with

S. S. Chen; R. C. Wilhoit; B. J. Zwolinski

1975-01-01

210

Thermodynamic properties of difluoromethane (R32) and pentafluoroethane (R125) are expressed in terms of 32-term modified Benedict-Webb-Rubin (MBWR) equations of state. For each refrigerant, coefficients are reported for the MBWR equation and for ancillary equations used to fit the ideal-gas heat capacity and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined with a multiproperty fit

S. L. Outcalt; M. O. McLinden

1995-01-01

211

Ebulliometers for measuring the thermodynamic properties of fluids and fluid mixtures

The design and operation of two ebulliometers is described. One is constructed of glass and is used for measuring vapor pressures of fluids at low reduced temperatures and pressures. The other is constructed of metal. It can be used for vapor pressure measurements, and also for the study of fluid mixture thermodynamics through the determination of the activity coefficients at infinite dilution. The advantages and potential problems associated with ebulliometers are described, and typical results are given for the properties of alternative refrigerants.

Weber, L.A.; Silva, A.M.

1994-09-01

212

Thermodynamic and transport properties of nonideal systems with isotropic pair potentials.

The equations of state and the structural, thermodynamic, and transport properties of the two- and three-dimensional nonideal dissipative systems consisting of particles interacting with different isotropic pair potentials are studied in a wide range of parameters typical for laboratory dusty plasma. Simple semiempirical expression for the energy density in liquid systems is considered. Comparison of the theoretical and numerical results is presented. PMID:21230606

Vaulina, O S; Koss, X G; Khrustalyov, Yu V; Petrov, O F; Fortov, V E

2010-11-01

213

Self-consistent calculations of the dynamic and thermodynamic properties of solid helium

The results of studies of physical properties of quantum crystals i.e. b.c.c. 3He and h.c.p. 4He in the reduced, all neighbors approximation of the self-consistent phonon theory (SCPT) are presented. The system of equations describing the temperature and pressure variations of the dynamic and thermodynamic quantities for these crystals has been solved for the best grounded theoretically, in the case

Cecylia Malinowska-Adamska; Piotr Sloma

2003-01-01

214

Thermodynamics and transport properties of metal\\/inert-gas mixtures used for arc welding

The knowledge of thermodynamics and transport properties of gas mixtures at high temperature is important for many industrial applications. Spark ignition, re-entry problems of space-vehicles, gas dischargers, arc welding, and circuit breakers can be mentioned as examples. This paper focuses on metal\\/inert-gas mixtures in the temperature range from 300 to 30,000K, which are important for arc welding processes. As metals

T. Hoffmann; G. Baldea; U. Riedel

2009-01-01

215

Thermodynamic properties of mixed-spin chains in magnetic field by the transfer matrix method

Motivated by recent experimental synthesis of molecule-based ferrimagnetics, we have investigated the thermodynamic properties of one-dimensional antiferromagnetic–ferromagnetic mixed spin-12 lozenge chain in external magnetic fields at low temperature, using the transfer matrix method. The magnetization and the specific heat of the spin system have been evaluated numerically from the free energy. The magnetization as a function of the magnetic field

H. H. Fu; K. L. Yao; Z. L. Liu

2006-01-01

216

Thermodynamic properties of mixed-spin chains in magnetic field by the transfer matrix method

Motivated by recent experimental synthesis of molecule-based ferrimagnetics, we have investigated the thermodynamic properties of one-dimensional antiferromagnetic ferromagnetic mixed spin-12 lozenge chain in external magnetic fields at low temperature, using the transfer matrix method. The magnetization and the specific heat of the spin system have been evaluated numerically from the free energy. The magnetization as a function of the magnetic

H. H. Fu; K. L. Yao; Z. L. Liu

2006-01-01

217

Thermodynamic properties of ammonia–water mixtures for power-cycle applications

Ammonia–water mixtures have been used as working fluids in absorption–refrigeration cycles for several decades. Their use as multi-component working fluids for power cycles has been investigated recently. The thermodynamic properties required are known or may be calculated at elevated temperatures and pressures. We present a new method for these computations using Gibbs free energies and empirical equations for bubble and

Feng Xu; D. Yogi Goswami

1999-01-01

218

New International Skeleton Tables for the Thermodynamic Properties of Ordinary Water Substance

NASA Astrophysics Data System (ADS)

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.

Sato, H.; Uematsu, M.; Watanabe, K.; Saul, A.; Wagner, W.

1988-10-01

219

Phase Transition and Thermodynamic Properties of Magnesium Fluoride by First Principles

NASA Astrophysics Data System (ADS)

The structural stabilities, phase transitions and thermodynamic properties of MgF2 under high pressure and temperature are investigated by first-principles calculations based on plane-wave pseudopotential density functional theory method within the local density approximation. The calculated lattice parameters of MgF2 in all four phases under zero pressure and zero temperature are in good agreement with the existing experimental data and other theoretical results. Our results demonstrate that MgF2 undergoes a series of structural phase transitions from rutile (P42/mnm)?CaCl2-type (Pnnm)?modified fluorite (Pa-3)?cotunnite (Pnam) under high pressure and the obtained transition pressures are in fairly good agreement with the experimental results. The temperature-dependent volume and thermodynamic properties of MgF2 in the rutile phase at 0 GPa are presented and the thermodynamic properties of MgF2 in the rutile, CaCl2-type, modified fluorite and cotunnite phases at 300 K are also predicted using the quasi-harmonic approximation model (QHA) and the quasi-harmonic Debye model (QHD), respectively. Moreover, the partial density of states and the electronic density of the four phases under the phase transition are also investigated.

Zhang, Tian; Cheng, Yan; Lv, Zhen-Long; Ji, Guang-Fu; Gong, Min

2014-12-01

220

The Wang-Landau method [F. Wang and D. P. Landau, Phys. Rev. E 64, 056101 (2001)] is an efficient way to calculate the density of states (DOS) for magnetic systems, and the DOS can then be used to rapidly calculate the thermodynamic properties of the system. A technique is presented that uses the DOS for a simple Hamiltonian to create a stratified sample of configurations which are then used calculate a warped DOS for more realistic Hamiltonians. This technique is validated for classical models of bcc Fe with exchange interactions of increasing range, but its real value is using the DOS for a model Hamiltonian calculated on a workstation to select the stratified set of configurations whose energies can then be calculated for a density-functional Hamiltonian. The result is an efficient first-principles calculation of thermodynamic properties such as the specific heat and magnetic susceptibility. Another technique uses the sample configurations to calculate the parameters of a model exchange interaction using a least-squares approach. The thermodynamic properties can be subsequently evaluated using traditional Monte Carlo techniques for the model exchange interaction. Finally, a technique that uses the configurations to train a neural network to estimate the configuration energy is also discussed. This technique could potentially be useful in identifying the configurations most important in calculating the warped DOS. VC2011 American Institute of Physics. [doi:10.1063/1.3565413

Brown, Greg [ORNL; Rusanu, Aurelian [ORNL; Daene, Markus W [ORNL; Nicholson, Don M [ORNL; Eisenbach, Markus [ORNL; Fidler, Jane L [ORNL

2011-01-01

221

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.

Singh, Kuldip; Singh, Gurpreet; Sharma, Rohit [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

2010-07-15

222

The equilibrium compositions corresponding to the thermodynamic and transport combustion properties for a wide range of conditions for the reaction of hydrocarbons with air are presented. The compositions presented correspond to Rankine temperature schedules.

Gordon, S.

1982-07-01

223

A database of thermodynamic properties is developed, which extends a previous database of glycolysis and tricarboxylic acid cycle by adding the reactions of the pentose phosphate pathway. The raw data and documented estimations of solution properties are made electronically available. The database is determined by estimation of a set of parameters representing species-level free energies of formation. The resulting calculations provide thermodynamic and network-based estimates of thermodynamic properties for six reactions of the pentose phosphate pathway for which estimates are not available in the preexisting literature. Optimized results are made available in ThermoML format. Because calculations depend on estimated hydrogen and metal cation dissociation constants, an uncertainty and sensitivity analysis is performed, revealing 23 critical dissociation constants to which the computed thermodynamic properties are particularly sensitive. Database URL: http://www.biocoda.org/thermo PMID:21482578

Li, Xin; Wu, Fan; Qi, Feng; Beard, Daniel A.

2011-01-01

224

Free energy of formation of Mo2C and the thermodynamic properties of carbon in solid molybdenum

NASA Technical Reports Server (NTRS)

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.

Seigle, L. L.; Chang, C. L.; Sharma, T. P.

1979-01-01

225

Structural properties and thermodynamics of water clusters: A Wang-Landau study

NASA Astrophysics Data System (ADS)

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.

Yin, Junqi; Landau, D. P.

2011-02-01

226

Structural properties and thermodynamics of water clusters: a Wang-Landau study.

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. PMID:21341853

Yin, Junqi; Landau, D P

2011-02-21

227

Structural, mechanical, and thermodynamic properties of a coarse-grained DNA model

NASA Astrophysics Data System (ADS)

We explore in detail the structural, mechanical, and thermodynamic properties of a coarse-grained model of DNA similar to that recently introduced in a study of DNA nanotweezers [T. E. Ouldridge, A. A. Louis, and J. P. K. Doye, Phys. Rev. Lett. 134, 178101 (2010)]. Effective interactions are used to represent chain connectivity, excluded volume, base stacking, and hydrogen bonding, naturally reproducing a range of DNA behavior. The model incorporates the specificity of Watson-Crick base pairing, but otherwise neglects sequence dependence of interaction strengths, resulting in an "average base" description of DNA. We quantify the relation to experiment of the thermodynamics of single-stranded stacking, duplex hybridization, and hairpin formation, as well as structural properties such as the persistence length of single strands and duplexes, and the elastic torsional and stretching moduli of double helices. We also explore the model's representation of more complex motifs involving dangling ends, bulged bases and internal loops, and the effect of stacking and fraying on the thermodynamics of the duplex formation transition.

Ouldridge, Thomas E.; Louis, Ard A.; Doye, Jonathan P. K.

2011-02-01

228

Optimization of the thermodynamic properties and phase diagrams of P2O5-containing systems

NASA Astrophysics Data System (ADS)

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. Melançon, A.D. Pelton and S. Petersen. (2002) FactSage Thermochemical Software and Databases. Calphad, 26, 189-228.

Hudon, Pierre; Jung, In-Ho

2014-05-01

229

Intermolecular potentials and the accurate prediction of the thermodynamic properties of water

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.

Shvab, I.; Sadus, Richard J., E-mail: rsadus@swin.edu.au [Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122 (Australia)

2013-11-21

230

Thermodynamic properties of a geothermal working fluid; 90% isobutane-10% isopentane: Final report

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.

Gallagher, J.S.; Linsky, D.; Morrison, G.; Levelt Sengers, J.M.H.

1987-04-01

231

NASA Astrophysics Data System (ADS)

We have systematically studied the thermodynamic properties of a two-dimensional half-filled SU (2 N ) Hubbard model on a square lattice by using the determinant quantum Monte Carlo method. The entropy-temperature relation, the isoentropy curve, and the probability distribution of the on-site occupation number are calculated in both SU(4) and SU(6) cases, which exhibit prominent features of the Pomeranchuk effect. We analyze these thermodynamic behaviors based on energy scales in the density and spin channels. In the density channel, the interaction strength that marks the crossover from the weak to strong interaction regimes increases with the number of fermion components. In the spin channel, increasing the number of fermion components enhances quantum spin fluctuations, which is shown in the simulations of uniform spin susceptibilities and antiferromagnetic structure factors.

Zhou, Zhichao; Cai, Zi; Wu, Congjun; Wang, Yu

2014-12-01

232

Thermodynamic properties of antiperovskite MgCNi3 in superconducting phase

NASA Astrophysics Data System (ADS)

The aim of the present work is to explore the physical properties of the transition-metal based antiperovskite MgCNi3 in superconducting state. In particular, the critical value of the Coulomb pseudopotential and temperature dependence of the energy gap, specific heat, thermodynamic critical field and London penetration depth are theoretically analyzed within the framework of the Eliashberg formalism. Moreover, we determined the dimensionless ratios which are related to the above thermodynamic functions: 2 ? (0) /kBTC = 4.19, ?C (TC) /CN (TC) = 2.27 and TCCN (TC) /HC2 (0) = 0.141. Our calculations show that obtained results significantly diverge from the values predicted by the BCS model due to the strong-coupling corrections and retardation effect existing in investigated antiperovskite.

Szcz??niak, R.; Durajski, A. P.; Herok, ?.

2015-02-01

233

Quasi-harmonic approximation of thermodynamic properties of ice Ih, II, and III

Several thermodynamic properties of ice Ih, II, and III are studied by a quasi-harmonic approximation and compared to results of quantum path integral and classical simulations. This approximation allows to obtain thermodynamic information at a fraction of the computational cost of standard simulation methods, and at the same time permits studying quantum effects related to zero point vibrations of the atoms. Specifically we have studied the crystal volume, bulk modulus, kinetic energy, enthalpy and heat capacity of the three ice phases as a function of temperature and pressure. The flexible q-TIP4P/F model of water was employed for this study, although the results concerning the capability of the quasi-harmonic approximation are expected to be valid independently of the employed water model. The quasi-harmonic approximation reproduces with reasonable accuracy the results of quantum and classical simulations showing an improved agreement at low temperatures (T < 100 K). This agreement does not deteriorate ...

Ramirez, R; Fernandez-Serra, M -V; Herrero, C P; 10.1063/1.4737862

2012-01-01

234

A test of systematic coarse-graining of molecular dynamics simulations: thermodynamic properties.

Coarse-graining (CG) techniques have recently attracted great interest for providing descriptions at a mesoscopic level of resolution that preserve fluid thermodynamic and transport behaviors with a reduced number of degrees of freedom and hence less computational effort. One fundamental question arises: how well and to what extent can a "bottom-up" developed mesoscale model recover the physical properties of a molecular scale system? To answer this question, we explore systematically the properties of a CG model that is developed to represent an intermediate mesoscale model between the atomistic and continuum scales. This CG model aims to reduce the computational cost relative to a full atomistic simulation, and we assess to what extent it is possible to preserve both the thermodynamic and transport properties of an underlying reference all-atom Lennard-Jones (LJ) system. In this paper, only the thermodynamic properties are considered in detail. The transport properties will be examined in subsequent work. To coarse-grain, we first use the iterative Boltzmann inversion (IBI) to determine a CG potential for a (1-?)N mesoscale particle system, where ? is the degree of coarse-graining, so as to reproduce the radial distribution function (RDF) of an N atomic particle system. Even though the uniqueness theorem guarantees a one to one relationship between the RDF and an effective pairwise potential, we find that RDFs are insensitive to the long-range part of the IBI-determined potentials, which provides some significant flexibility in further matching other properties. We then propose a reformulation of IBI as a robust minimization procedure that enables simultaneous matching of the RDF and the fluid pressure. We find that this new method mainly changes the attractive tail region of the CG potentials, and it improves the isothermal compressibility relative to pure IBI. We also find that there are optimal interaction cutoff lengths for the CG system, as a function of ?, that are required to attain an adequate potential while maintaining computational speedup. To demonstrate the universality of the method, we test a range of state points for the LJ liquid as well as several LJ chain fluids. PMID:23126694

Fu, Chia-Chun; Kulkarni, Pandurang M; Shell, M Scott; Leal, L Gary

2012-10-28

235

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.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.

1990-12-01

236

Emergence of equilibrium thermodynamic properties in quantum pure states. I. Theory

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.

Fresch, Barbara; Moro, Giorgio J. [Department of Chemical Science, University of Padova, Via Marzolo 1, Padova 35131 (Italy)

2010-07-21

237

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.

Messerly, J.F.; Todd, S.S.; Finke, H.L.; Gammon, B.E.

1987-01-01

238

Thermodynamic properties of cubic ZrC under high pressure from first-principles calculations

NASA Astrophysics Data System (ADS)

The elastic and thermodynamic properties of Zirconium carbide (ZrC) are investigated by ab initio plane-wave pseudopotential density function theory method. The obtained lattice constant, elastic constant and bulk modulus B are consistent with the experimental and theoretical data. Through the quasi-harmonic Debye model, the dependences of the normalized volume V/V 0 and the bulk modulus B on pressure P, as well as the specific heat C V on the temperature T are obtained successfully. The relationships of the thermal expansion ? with temperature and pressure are also investigated, which indicate the temperature hardly has any effect on the thermal expansion ? at high pressure.

Zhu, Jun; Zhu, Bo; Qu, Jianying; Gou, Qingquan; Chen, Fang

2009-07-01

239

Elastic and thermodynamic properties of c-BN from first-principles calculations

NASA Astrophysics Data System (ADS)

The elastic constants and thermodynamic properties of c-BN are calculated using the first-principles plane wave method with the relativistic analytic pseudopotential of the Hartwigen, Goedecker and Hutter (HGH) type in the frame of local density approximation and using the quasi-harmonic Debye model, separately. Moreover, the dependences of the normalized volume V/V0 on pressure P, as well as the bulk modulus B, the thermal expansion ?, and the heat capacity CV on pressure P and temperature T are also successfully obtained.

Hao, Yan-Jun; Cheng, Yan; Wang, Yan-Ju; Chen, Xiang-Rong

2007-01-01

240

NASA Technical Reports Server (NTRS)

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.

Talcott, N. A., Jr.

1977-01-01

241

Atomic structure, mechanical quality, and thermodynamic property of TiHx phases

NASA Astrophysics Data System (ADS)

Titanium hydrides TiHx (x = 1, 1.25, 1.5, 1.75, and 2) with the cubic fluorite-type (face-centered cubic, ? phase) and face-centered-tetragonal (? phase, c/a < 1; ? 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 ? and ? 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.

Liang, C. P.; Gong, H. R.

2013-07-01

242

Thermodynamic properties of methane/water interface predicted by molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations have been performed to examine the thermodynamic properties of methane/water interface using two different water models, the TIP4P/2005 and SPC/E, and two sets of combining rules. The density profiles, interfacial tensions, surface excesses, surface pressures, and coexisting densities are calculated over a wide range of pressure conditions. The TIP4P/2005 water model was used, with an optimized combining rule between water and methane fit to the solubility, to provide good predictions of interfacial properties. The use of the infinite dilution approximation to calculate the surface excesses from the interfacial tensions is examined comparing the surface pressures obtained by different approaches. It is shown that both the change of methane solubilities in pressure and position of maximum methane density profile at the interface are independent of pressure up to about 2 MPa. We have also calculated the adsorption enthalpies and entropies to describe the temperature dependency of the adsorption.

Sakamaki, Ryuji; Sum, Amadeu K.; Narumi, Tetsu; Ohmura, Ryo; Yasuoka, Kenji

2011-04-01

243

Thermodynamic properties of methane/water interface predicted by molecular dynamics simulations.

Molecular dynamics simulations have been performed to examine the thermodynamic properties of methane/water interface using two different water models, the TIP4P/2005 and SPC/E, and two sets of combining rules. The density profiles, interfacial tensions, surface excesses, surface pressures, and coexisting densities are calculated over a wide range of pressure conditions. The TIP4P/2005 water model was used, with an optimized combining rule between water and methane fit to the solubility, to provide good predictions of interfacial properties. The use of the infinite dilution approximation to calculate the surface excesses from the interfacial tensions is examined comparing the surface pressures obtained by different approaches. It is shown that both the change of methane solubilities in pressure and position of maximum methane density profile at the interface are independent of pressure up to about 2 MPa. We have also calculated the adsorption enthalpies and entropies to describe the temperature dependency of the adsorption. PMID:21495767

Sakamaki, Ryuji; Sum, Amadeu K; Narumi, Tetsu; Ohmura, Ryo; Yasuoka, Kenji

2011-04-14

244

NASA Astrophysics Data System (ADS)

Thermodynamic properties of difluoromethane (R32) and pentafluoroethane (R125) are expressed in terms of 32-term modified Benedict-Webb-Rubin (MBWR) equations of state. For each refrigerant, coefficients are reported for the MBWR equation and for ancillary equations used to fit the ideal-gas heat capacity and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined with a multiproperty fit that used the following types of experimental data: PVT: isochoric, isobaric, and saturated-liquid heal capacities; second virial coefficients; and properties at coexistence. The respective equations of stale accurately represent experimental data from 160 to 393 K and pressures to 35 MPa for R32 and from 174 to 448 K and pressures to 68 MPa for R125 with the exception of the critical regions. Both equations give reasonable results upon extrapolation to 500 K and 60 MPa. Comparisons between predicted and experimental values are presented.

Outcalt, S. L.; McLinden, M. O.

1995-01-01

245

Physical and Thermodynamic Properties of AlnCm Clusters: Quantum-Chemical Study.

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 AlnCm 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

Loukhovitski, Boris I; Sharipov, Alexander S; Starik, Alexander M

2015-02-26

246

We study bulk structural and thermodynamic properties of methanol-water solutions via molecular dynamics simulations using novel interaction potentials based on the charge equilibration (fluctuating charge) formalism to explicitly account for molecular polarization at the atomic level. The study uses the TIP4P-FQ potential for water-water interactions, and the CHARMM-based (Chemistry at HARvard Molecular Mechanics) fluctuating charge potential for methanol-methanol and methanol-water interactions. In terms of bulk solution properties, we discuss liquid densities, enthalpies of mixing, dielectric constants, self-diffusion constants, as well as structural properties related to local hydrogen bonding structure as manifested in radial distribution functions and cluster analysis. We further explore the electronic response of water and methanol in the differing local environments established by the interaction of each species predominantly with molecules of the other species. The current force field for the alcohol-water interaction performs reasonably well for most properties, with the greatest deviation from experiment observed for the excess mixing enthalpies, which are predicted to be too favorable. This is qualitatively consistent with the overestimation of the methanol-water gas-phase interaction energy for the lowest-energy conformer (methanol as proton donor). Hydration free energies for methanol in TIP4P-FQ water are predicted to be ?5.6±0.2 kcal/mole, in respectable agreement with the experimental value of ?5.1 kcal/mole. With respect to solution micro-structure, the present cluster analysis suggests that the micro-scale environment for concentrations where select thermodynamic quantities reach extremal values is described by a bi-percolating network structure. PMID:18074339

Zhong, Yang; Warren, G. Lee; Patel, Sandeep

2014-01-01

247

Calculations and curve fits of thermodynamic and transport properties for equilibrium air to 30000 K

NASA Technical Reports Server (NTRS)

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.

Gupta, Roop N.; Lee, Kam-Pui; Thompson, Richard A.; Yos, Jerrold M.

1991-01-01

248

Thermodynamic and optical properties of mixed-salt aerosols of atmospheric importance

NASA Astrophysics Data System (ADS)

Extensive water activity, density, and refractive index data at 25°C are reported for mixed-salt solutions, NaCl-KCl, NaCl-NaNO3, NaCl-Na2SO4, Na2SO4-NaNO3, and (NH4)2SO4-Na2SO4. The data are obtained from hydration experiments using the single-particle levitation technique developed recently for measuring the thermodynamic and optical properties of microdroplets. These data, covering the whole concentration range from dilute solutions to high supersaturations, provide an opportunity to explore the light-scattering properties of both internal and external mixtures of the chloride, sulfate, and nitrate aerosols of atmospheric importance. It is shown that for sulfate and nitrate aerosols as solution droplets, the light-scattering properties do not differ appreciably among all mixture types and compositions, as long as the dry-salt aerosols have the same particle-size distribution. However, for mixed-salt aerosols containing NaCl, the light-scattering properties do depend upon the composition and particle-size distribution, although not so much on the mixture type.

Tang, Ignatius N.

1997-01-01

249

Computer-assisted analyses of the thermodynamic properties of slags in coal-combustion systems

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.

Blander, M.; Pelton, A.D.

1983-09-01

250

The thermodynamic properties to 700 K of naphthalene and 2,7-dimethylnaphthalene

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.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Steele, W.V.

1993-08-01

251

Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism

NASA Astrophysics Data System (ADS)

We present an atomistic model that accounts for a range of anomalous thermodynamic properties of the fcc ? phase of Pu-Ga alloys in terms of the Invar mechanism. Two modified embedded atom method potentials are employed to represent competing electronic states in ?-Pu, each of which has an individual configuration dependence as well as distinct interactions with gallium. Using classical Monte Carlo simulations, we compute the temperature dependence of various thermodynamic properties for different dilute gallium concentrations. The model reproduces the observed effects of excessive volume reduction along with a rapid shift in thermal expansion from negative to positive values with increasing gallium concentration. It also predicts progressive stiffening upon dilute-gallium alloying, while the calculated thermal softening is nearly independent of the gallium concentration in agreement with resonant ultrasound spectroscopy measurements in the literature. Analysis of the local structure predicted by the model indicates that the distribution of the gallium atoms is not completely random in the ? phase due to the presence of short-range order associated with the Invar mechanism. This effect is consistent with the nanoscale heterogeneity in local gallium concentration which is observed in recent extended x-ray absorption fine structure spectroscopy experiments. Implications of the Invar effect for phase stability and physical interpretations of the two states are also discussed.

Lee, Tongsik; Taylor, Christopher D.; Lawson, A. C.; Conradson, Steven D.; Chen, Shao Ping; Caro, A.; Valone, Steven M.; Baskes, Michael I.

2014-05-01

252

A new application for two-dimensional (2D) materials is emulsification, where they can serve as ultrathin platelike interfacial stabilizers in two-liquid systems. We present a first detailed thermodynamic analysis of atomically thin 2D materials at organic-aqueous liquid-liquid interfaces and derive expressions for the transfer free energies of emulsion stabilization that account for material geometry, van der Waals transparency or opacity, and variable hydrophobicity. High mass potency is shown to be an intrinsic property of the 2D geometry, which at the atomically thin limit places every atom in contact with both liquid phases, resulting in unit atom efficiency. The thermodynamic model successfully predicts that graphene oxide but not pristine graphene has a favorable hydrophobic-hydrophilic balance for oil-water emulsion stabilization. Multilayer tiling is predicted to occur by the passivation of droplet surface patches left uncovered by packing inefficiencies in the first monolayer, and complete multilayer coverage is confirmed by cryogenic scanning electron microscopy. The molecular barrier function of graphene interfacial films causes a significant suppression of dispersed-phase evaporation rates with potential applications in controlled release. Finally, these emulsions can be used as templates for creating solid graphene foams or graphene microsacks filled with lipophilic cargos. Emerging 2D materials are promising as dispersants or emulsifiers where high mass potency and multifunctional properties are desired. PMID:24625132

Creighton, Megan A; Ohata, Yuzo; Miyawaki, Jin; Bose, Arijit; Hurt, Robert H

2014-04-01

253

NASA Astrophysics Data System (ADS)

We have employed parameter-free density functional theory calculations to study the thermodynamic stability and structural parameters as well as elastic and electronic properties of Ni4N in eight selected crystallographic phases. In agreement with the experimental findings, the cubic structure with Pearson symbol cP5, space group Pm3¯m (221) is found to be the most stable and it is also the only thermodynamically stable structure at T=0 K with respect to decomposition to the elemental Ni crystal and N2 gas phase. We determine structural parameters, bulk moduli, and their pressure derivatives for all eight allotropes. The thermodynamic stability and bulk modulus is shown to be anticorrelated. Comparing ferromagnetic and nonmagnetic states, we find common features between the magnetism of elemental Ni and studied ferromagnetic Ni4N structures. For the ground-state Ni4N structure and other two Ni4N cubic allotropes, we predict a complete set of single-crystalline elastic constants (in the equilibrium and under hydrostatic pressure), the Young and area moduli, as well as homogenized polycrystalline elastic moduli obtained by different homogenization methods. We demonstrate that the elastic anisotropy of the ground-state Ni4N is qualitatively opposite to that in the elemental Ni, i.e., these materials have hard and soft crystallographic directions interchanged. Moreover, one of the studied metastable cubic phases is found auxetic, i.e., exhibiting negative Poisson ratio.

Hemzalová, P.; Friák, M.; Šob, M.; Ma, D.; Udyansky, A.; Raabe, D.; Neugebauer, J.

2013-11-01

254

The thermodynamic properties of bis(?6-ethoxybenzene)chromium fulleride from T ? 0 to 340 K

NASA Astrophysics Data System (ADS)

The temperature dependence of the heat capacity of crystalline bis-(?6-ethoxybenzene)chromium fulleride [(?6-(EtOPh))2Cr]·+[C60]·- was studied for the first time by adiabatic vacuum calorimetry over the temperature range 6-340 K with errors of ±0.2%. The temperature dependence of the EPR signal parameters of bis-(?6-ethoxybenzene)chromium fulleride was studied for the first time from 120 to 340 K. A reversible endothermic transformation was observed between 160 and 250 K during heating; it was caused by the dissociation of the [(C60)2]2- dimer and the formation of the [(?6-(EtOPh))2Cr]·+[C60]·- fulleride; its standard thermodynamic characteristics were estimated and analyzed. The experimental data were used to calculate the standard thermodynamic functions, including the heat capacity, enthalpy, entropy, and Gibbs function of the fulleride dimer from T ? 0 to 160 K and the [(?6-(EtOPh))2Cr]·+[C60]·- monomeric complex over the temperature range 250-340 K. The standard thermodynamic properties of the fulleride studied, fullerides studied earlier, and fullerite C60 were compared.

Ruchenin, V. A.; Markin, A. V.; Smirnova, N. N.; Markin, G. V.; Shevelev, Yu. A.; Kuropatov, V. A.; Lopatin, M. A.; Domrachev, G. A.

2010-06-01

255

Thermodynamic properties and entropy scaling law for diffusivity in soft spheres.

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

Pieprzyk, S; Heyes, D M; Bra?ka, A C

2014-07-01

256

Understanding the phase change behavior of biomaterials during freezing/thawing including their thermal properties at low temperatures is essential to design and improve cryobiology applications such as cryopreservation and cryosurgery. However, knowledge of phase change behavior and thermal properties of various biomaterials is still incomplete, especially at cryogenic temperatures (< or = -40 degrees C). Moreover, in these applications, chemicals are often added to improve their outcome, which can result in significant variation in the phase change behavior and thermal properties from those of the original biomaterials. These chemical additives include cryoprotective agents (CPAs), antifreeze protein (AFP), or cryosurgical adjuvants like sodium chloride (NaCl). In the present study, phase change behavior and thermal properties of saline solutions--either water-NaCl or phosphate buffered saline (PBS)--with various chemical additives were investigated. The chemical additives studied are glycerol and raffinose as CPAs, an AFP (Type III, molecular weight = 6500), and NaCl as a cryosurgical adjuvant. The phase change behavior was investigated using a differential scanning calorimeter (DSC) and a cryomicroscope. The specific and latent heat of these solutions were also measured with the DSC. The saline solutions have two distinct phase changes--water/ice and eutectic phase changes. During freezing, eutectic solidification of both water-NaCl and PBS are significantly supercooled below their thermodynamic equilibrium eutectic temperatures. However, their melting temperatures are close to thermodynamic equilibrium during thawing. These eutectic phase changes disappear when even a small amount (0.1 M glycerol) of CPA was added, but they are still observed after the addition of an AFP. The specific heats of these solutions are close to that of ice at very low temperatures (< or = -100 degrees C) regardless of the additives, but they increase between -100 degrees C and -30 degrees C with the addition of CPAs. The amount of latent heat, which is evaluated with sample weight, generally decreases with the addition of the additives, but can be normalized to approximately 300 J/g based on the weight of water which participates in the phase change. This illustrates that thermal properties, especially latent heat, of a biomaterial should be evaluated based on the understanding of its phase change behavior. The results of the present study are discussed in the context of the implications for cryobiology applications. PMID:15179849

Han, Bumsoo; Bischof, John C

2004-04-01

257

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.

Donohue, M.D.

1990-09-01

258

Mechanical, electronic, optical, thermodynamic properties and superconductivity of ScGa3

NASA Astrophysics Data System (ADS)

The rare occurrence of type-I superconductivity in binary system ScGa3 has experimentally been shown recently. In the present paper we study the electronic, optical, thermodynamic properties and some aspects of superconductivity of this compound using first-principles calculations. The mechanical properties like elastic constants, bulk modulus, shear modulus, Pugh's ductility index, Young's modulus, Poisson's ratio, elastic anisotropy factor, Peierls stress are calculated for the first time. The material is anisotropic and brittle. Electronic band structure, density of states, Fermi surfaces and bonding nature have also been studied. The optical functions are estimated and discussed for the first time. The high reflectivity is found in the ultraviolet regions up to ~13 eV and thus ScGa3 can serve as a possible shielding material for ultraviolet radiation. Thermal effects on some macroscopic properties of ScGa3 are predicted using the quasi-harmonic Debye model and phonon approximation in the temperature and hydrostatic pressure in the ranges of 0-1000 K and 0-40 GPa, respectively. The calculated electron-phonon coupling constant ?=0.52 yields Tc=2.6 K, which is in very good agreement with the experimentally observed value. The value of the coupling constant and the Ginzburg-Landau parameter (?=0.09) indicate that the compound is a weak-coupled type-I rare binary BCS superconductor.

Parvin, F.; Hossain, M. A.; Ali, M. S.; Islam, A. K. M. A.

2015-01-01

259

NASA Technical Reports Server (NTRS)

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.

Weber, L. A.

1975-01-01

260

In the present paper we performed the analysis of available data on structural, thermodynamic and mechanical properties of B6O. Although the compound is known for half a century and has been extensively studied, many properties of this boron-rich solid remain unknown or doubtful. Semi-empirical analysis of our experimental and literature data allowed us to choose the best values of main thermodynamic and mechanical characteristics among previously reported data, to predict the thermoelastic equation of state of B6O, and dependence of its hardness on non-stoichiometry and temperature.

Kurakevych, Oleksandr O

2011-01-01

261

A theoretical investigation on structural and thermodynamic properties of 11-type iron-based superconductor FeSe at high pressure and high temperature was performed by employing the first-principles method based on the density functional theory. Some structural parameters of FeSe in both tetragonal and hexagonal phases are reported. According to the fourth-order Birch-Murnaghan equation of states, the transition pressure P(t) of FeSe from the PbO-type phase to the NiAs-type phase was determined. The calculated results are found to be in good agreement with the available experimental data. Based on the quasi-harmonic Debye model, the pressure and temperature dependence of the thermodynamic properties for hexagonal phase FeSe were investigated. Our theoretical calculations suggest that the pressure and temperature have significant effects on the heat capacity, vibrational internal energy, vibrational entropy, vibrational Helmholtz free energy, thermal expansion coefficient and Debye temperature. Even though few theoretical reports on the structural properties of FeSe are found in the current literature, to our knowledge, this is a novel theoretical investigation on the structural and thermodynamic properties of FeSe at high temperature. We hope that the theoretical results reported here can give more insight into the structural and thermodynamic properties of other iron-based superconductors at high temperature. PMID:22790848

Lu, Cheng; Yang, Xing-Qiang; Zhu, Chun-Ye; Kuang, Xiao-Yu

2012-08-28

262

Elastic, Electronic and Thermodynamic Properties of Rh3X(X = Zr, Nb and Ta) Intermetallic Compounds

NASA Astrophysics Data System (ADS)

Structural, electronic, elastic and thermodynamic properties of Rh3X(X = Zr, Nb, Ta) intermetallic compounds are investigated in the framework of density functional theory (DFT). The exchange-correlation (XC) potential is treated with the generalized gradient approximation (GGA) and local density approximation (LDA). The computed ground state properties agree well with the available theoretical and experimental values. The elastic constants are obtained by calculating the total energy versus volume conserving strains using Mehl model. The electronic and bonding properties are discussed from the calculations of band structures (BSs), densities of states and electron charge densities. The volume and bulk modulus at high pressure and temperature are investigated. Additionally, thermodynamic properties such as the heat capacity, thermal expansion and Debye temperature at high pressures and temperatures are also analyzed.

Ould Kada, M.; Seddik, T.; Sayede, A.; Khenata, R.; Bouhemadou, A.; Deligoz, E.; Alahmed, Z. A.; Bin Omran, S.; Rached, D.

2014-11-01

263

NASA Technical Reports Server (NTRS)

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.

Simmonds, A. L.; Miller, C. G., III; Nealy, J. E.

1976-01-01

264

Isentropic expansion and related thermodynamic properties of non-ionic amphiphile-water mixtures.

A concise thermodynamic formalism is developed for the molar isentropic thermal expansion, ES,m = ( partial differential Vm/ partial differential T)(Sm,x), and the ideal and excess quantities for the molar, apparent molar and partial molar isentropic expansions of binary liquid mixtures. Ultrasound speeds were determined by means of the pulse-echo-overlap method in aqueous mixtures of 2-methylpropan-2-ol at 298.15 K over the entire composition range. These data complement selected extensive literature data on density, isobaric heat capacity and ultrasound speed for 9 amphiphile (methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-2-ol, ethane-1,2-diol, 2-methoxyethanol, 2-ethoxyethanol or 2-butoxyethanol)-water binary systems, which form the basis of tables listing molar and excess molar isobaric expansions and heat capacities, and molar and excess molar isentropic compressions and expansions at 298.15 K and at 65 fixed mole fractions spanning the entire composition range and fine-grained in the water-rich region. The dependence on composition of these 9 systems is graphically depicted for the excess molar isobaric and isentropic expansions and for the excess partial molar isobaric and isentropic expansions of the amphiphile. The analysis shows that isentropic thermal expansion properties give a much stronger response to amphiphile-water molecular interactions than do their isobaric counterparts. Depending on the pair property-system, the maximum excess molar isentropic value is generally twenty- to a hundred-fold greater than the corresponding maximum isobaric value, and occurs at a lower mole fraction of the amphiphile. Values at infinite dilution of the 9 amphiphiles in water are given for the excess partial molar isobaric heat capacity, isentropic compression, isobaric expansion and isentropic expansion. These values are interpreted in terms of the changes occurring when amphiphile molecules cluster into an oligomeric form. Present results are discussed from theoretical and experimental thermodynamic viewpoints. It is concluded that isentropic thermal expansion properties constitute a new distinct resource for revealing particular features and trends in complex mixing processes, and that analyses using these new properties compare favourably with conventional approaches. PMID:18183317

Reis, João Carlos R; Douhéret, Gérard; Davis, Michael I; Fjellanger, Inger Johanne; Høiland, Harald

2008-01-28

265

NASA Technical Reports Server (NTRS)

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.

Klich, G. F.

1976-01-01

266

Thermodynamic properties of Lu/sub 2/In/sub 5/ and LuIn

The measurement of the electromotive forces (emf) of the prepared alloys of lutetium with indium were made over a temperature range of 370 to 537/sup 0/C with concentrations of 5 to 49% lutetium. The results indicate the existence of two heterogeneous regions in this concentration region. The phase which is richest in indium has the composition 28.61% Lu (LuIn/sub 2/ /sub 5/) instead of 25% Lu. The 1:1 phase should apparently be considered as stoichiometric with 1%, since the emf of the alloy with 51.2% Lu has values at 200 mV, while the alloys with 29.6 to 39.3% Lu have an emf of 255 mV. X-ray analysis confirmed these results. The thermodynamic property values were calculated by least square fit methods, and were compared with literature parameters. 4 tables.

Khue, V.D.; Vasil'ev, V.P.; Gerasimov, Ya.I.

1982-01-01

267

Magnetic, transport, and thermodynamic properties of CaMn2O4 single crystals

NASA Astrophysics Data System (ADS)

Physical properties including magnetic susceptibility, room-temperature electrical resistivity, thermal conductivity, heat capacity, and thermal expansion are reported for high quality single-crystal samples of marokite CaMn2O4 . We determined that CaMn2O4 is highly electrically insulating and exhibits long-range antiferromagnetic order below TN=217.5±0.6K with easy axis along a . Anisotropic thermal expansion, similar to that of crystallographically layered materials, is observed, suggesting that the crystal structure of CaMn2O4 is also assembled from previously undescribed layers. An extensive thermodynamic study of the antiferromagnetic transition was undertaken resulting in a heat-capacity critical exponent ?=0.082±0.007 and calculated pressure derivative dTN/dP=5.154±0.174K/GPa .

White, B. D.; Souza, J. A.; Chiorescu, C.; Neumeier, J. J.; Cohn, J. L.

2009-03-01

268

NASA Astrophysics Data System (ADS)

We report electrical, magnetic, elastic, and thermodynamic properties of CoSi. A low resistivity residual ratio and tendency of the resistivity to saturate near room temperature identify CoSi as a disordered metal, which nevertheless reveals the clear presence of T2 contribution of nonmagnetic nature below ˜30 K. The Sommerfeld constant of CoSi, following from heat capacity measurements, does not show any enhancement over values typical of simple metals. The magnetic susceptibility of CoSi changes from diamagnetic at high temperature to paramagnetic at temperatures below ˜25 K, indicating the existence of local magnetic moments. The elastic moduli of CoSi show an anomalous decrease on cooling. An explanation of these phenomena is based on the concept of electron localization with formation of local magnetic moments. These phenomena probably arise as a result of a self-doping effect due to the polyvalent character of Co and the nonstoichiometric nature of CoSi.

Stishov, Sergei M.; Petrova, Alla E.; Sidorov, Vladimir A.; Krasnorussky, Vladimir N.; Menzel, Dirk

2012-08-01

269

Molecular-dynamic modeling of thermodynamic properties of the lunar Fe-S core

NASA Astrophysics Data System (ADS)

The physical properties (density, modules of compression, heat capacity, and velocity of the P-waves) of the lunar Fe-S core are modeled with molecular dynamics and the Embedded Atom Model potential at 0-18 at % S content, temperatures up to 2500 K, and pressures up to 5 GPa. The thermodynamic calculations of the velocity of P-waves in the liquid lunar core are consistent with the interpreted results of seismic processing of the Apollo observations. According to calculations, the density of the liquid core may vary from 7.4 (pure liquid iron) to 6.75 (10 at % S at 1950 ± 50 K) g/cm3. This approach provides more reliable restrictions for the inner structure of the Moon.

Belashchenko, D. K.; Kuskov, O. L.

2015-01-01

270

Thermodynamic and optical properties of gases in a wide range of parameters.

NASA Astrophysics Data System (ADS)

This work describes calculational methods and the results of systematic calculations of the thermodynamic properties, composition, spectral and mean absorption coefficients for air, water, silicon dioxide and the atmosphere of Mars (0.965 CO2+0.035 N2). The range of the considered temperatures from 0.1 to 103eV includes the molecular state of the substances, dissociative gas, low temperature plasma and multicharge plasma. The selected density range ? = 10-9 - 10-2 g cm-3 includes the most interesting states for applications. The main mechanisms which determine the absorption coefficients of gases and plasma (inverse bremsstrahlung; photoionization from the ground and excited states of particles; photodissociation of molecules; photoionization from internal particle shells; electronic-vibrational transitions in molecules; line absorption by atoms and ions) were taken into account. Absorption coefficients were determined for photon energies ? = 3×10-2 - 104eV.

Romanov, G. S.; Stankevich, Yu. A.; Stanchits, I. K.; Stepanov, K. L.

1995-02-01

271

Acoustic and Thermodynamic Properties of the Binary Liquid Mixture n-Octane + n-Dodecane

NASA Astrophysics Data System (ADS)

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.

Khasanshin, T. S.; Golubeva, N. V.; Samuilov, V. S.; Shchemelev, A. P.

2014-01-01

272

Fast interpolation algorithm for the calculation of thermodynamic property maps of microstructures

NASA Astrophysics Data System (ADS)

A fast method for the calculation of thermodynamic property mappings of alloy microstructures is presented. It uses surrogate interpolation models instead of the direct CALPHAD calculation of each data point. With the best algorithm, a speed-up of nearly 30 can be achieved compared to the direct method. If repeated calculations of similar microstructures are required, a speed-up of around 300 can even be realized. Different surrogate models have been evaluated. The universal kriging method gives the most accurate results, while polynomial surface response models turn out to generate larger interpolation errors. In order to minimize the number of calculation points of the surrogate interpolation model, the microstructure is classified into similar regions, in which the design points are chosen randomly. The algorithm is applicable independent of alloy composition. Within the paper, we present the application of the algorithm for two single-crystalline nickel-based superalloys.

Rettig, Ralf; Singer, Robert F.

2014-12-01

273

Thermodynamic properties of aqueous solutions of sodium ibuprofen at 293.15-318.15 K

NASA Astrophysics Data System (ADS)

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.

Manin, N. G.; Perlovich, G. L.

2015-04-01

274

Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation

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.

Feng, ShiQuan; Cheng, XinLu [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China) [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu, 610064 (China); Zhao, JianLing [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)] [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Zhang, Hong [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China)] [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China)

2013-07-28

275

NASA Astrophysics Data System (ADS)

Supersymmetric Discrete Light Cone Quantization is utilized to derive the full mass spectrum of two dimensional supersymmetric theories. The thermal properties of such models are studied by constructing the density of states. We consider pure super Yang-Mills theory without and with fundamentals in large-Nc approximation. For the latter we include a Chern-Simons term to give mass to the adjoint partons. In both of the theories we find that the density of states grows exponentially and the theories have a Hagedorn temperature TH. For the pure SYM we find that TH at infinite resolution is slightly less than one in units of g2Ncp . In this temperature range, we find that the thermodynamics is dominated by the massless states. For the system with fundamental matter we consider the thermal properties of the mesonic part of the spectrum. We find that the meson-like sector dominates the thermodynamics. We show that in this case TH grows with the gauge coupling. The temperature and coupling dependence of the free energy for temperatures below TH are calculated. As expected, the free energy for weak coupling and low temperature grows quadratically with the temperature. The ratio of free energies at strong coupling compared to weak coupling, rs-w, for low temperatures grows quadratically with T. Our data indicate that rs-w tends to zero in the continuum at low temperatures. Finally a super-QCD model realized from weakly coupled D3-D7 branes is proposed as a future project in SDLCQ.

Proestos, Yiannis

2007-12-01

276

NASA Technical Reports Server (NTRS)

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.

Miller, C. G., III; Wilder, S. E.

1976-01-01

277

In the present paper we performed the analysis of available data on structural, thermodynamic and mechanical properties of B6O. Although the compound is known for half a century and has been extensively studied, many properties of this boron-rich solid remain unknown or doubtful. Semi-empirical analysis of our experimental and literature data allowed us to choose the best values of main

Oleksandr O. Kurakevych; Vladimir L. Solozhenko

2011-01-01

278

NASA Technical Reports Server (NTRS)

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

Fessler, T. E.

1977-01-01

279

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 l?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 ?-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

Mittal, Shruti; Singh, Laishram Rajendrakumar

2013-01-01

280

Experimental access to elastic and thermodynamic properties of RbMnFe(CN)6

NASA Astrophysics Data System (ADS)

We use spectroscopic ellipsometry to study the elastic and thermodynamic properties of the structural first-order transition of the cooperative Jahn-Teller solid, RbMn[Fe(CN)6]. While the analysis of the thermal dependence of the dielectric constant revealed a remarkable energy shift in the metal-to-ligand charge transfer band, that of the refractive index allowed to evaluate the volumetric thermal expansion coefficient in the two phases through the Gladstone-Dale relation. The access to the elastic properties of the solid is obtained with the reflectivity under pressure measurements, from which we estimated the bulk modulus values in the low- and high-temperature phases as BLT=30(±3) GPa and BHT=23(±2) GPa, respectively. Assuming the system is isotropic, the corresponding Debye temperature values have been found to be ?DLT(SE)?360(±25) K and ?DHT(SE)?290(±20) K, in good agreement with those derived from independent Mössbauer spectrometry investigations which led to ?DLT(Moss)?332(±7) K and ?DHT(Moss)?280(±11) K. Moreover, we have been able to extract from the SE data, the entropy change at the transition, ?S ?64 J K-1 mol-1, which has been also found in good agreement with the value, ?S ?60±5 J K-1 mol-1, derived from calorimetric experiments performed in this work.

Boukheddaden, K.; Loutete-Dangui, E. D.; Codjovi, E.; Castro, M.; Rodriguéz-Velamazán, J. A.; Ohkoshi, S.; Tokoro, H.; Koubaa, M.; Abid, Y.; Varret, F.

2011-01-01

281

NASA Astrophysics Data System (ADS)

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.

Kocak, B.; Ciftci, Y. O.; Colakoglu, K.; Deligoz, E.

2010-10-01

282

First principle study of elastic and thermodynamic properties of FeB4 under high pressure

NASA Astrophysics Data System (ADS)

The elastic properties, elastic anisotropy, and thermodynamic properties of the lately synthesized orthorhombic FeB4 at high pressures are investigated using first-principles density functional calculations. The calculated equilibrium parameters are in good agreement with the available experimental and theoretical data. The obtained normalized volume dependence of high pressure is consistent with the previous experimental data investigated using high-pressure synchrotron x-ray diffraction. The complete elastic tensors and crystal anisotropies of the FeB4 are also determined in the pressure range of 0-100 GPa. By the elastic stability criteria and vibrational frequencies, it is predicted that the orthorhombic FeB4 is stable up to 100 GPa. In addition, the calculated B/G ratio reveals that FeB4 possesses brittle nature in the range of pressure from 0 to 100 GPa. The calculated elastic anisotropic factors suggest that FeB4 is elastically anisotropic. By using quasi-harmonic Debye model, the compressibility, bulk modulus, the coefficient of thermal expansion, the heat capacity, and the Grüneisen parameter of FeB4 are successfully obtained in the present work.

Zhang, Xinyu; Qin, Jiaqian; Ning, Jinliang; Sun, Xiaowei; Li, Xinting; Ma, Mingzhen; Liu, Riping

2013-11-01

283

Structural and thermodynamic properties of Fe{sub 1.12}Te with multiple phase transitions

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}

Cherian, Dona, E-mail: donacherian@physics.iisc.ernet.in; Elizabeth, Suja [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Rößler, S.; Koz, C.; Schwarz, U.; Wirth, S. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Tsirlin, A. A. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia)

2014-03-28

284

Ab initio studies of thermodynamic and electronic properties of phosphorene nanoribbons

NASA Astrophysics Data System (ADS)

We present a density functional theory study of the thermodynamic and electronic properties of phosphorene nanoribbons. We consider a variety of terminations and reconstructions of ribbon edges, both with and without hydrogen passivation, and calculate an ab intio phase diagram that identifies energetically preferred edges as a function of temperature and hydrogen partial pressure. These studies are also accompanied by detailed electronic structure calculations from which we find that ribbons with hydrogenated edges are typically direct gap semiconductors with fundamental gaps that are in excess of phosphorene, the gaps varying inversely with ribbon width. In contrast, ribbons with bare or partially passivated edges either have metallic edges or are semiconducting with band gaps that are smaller than those of their hydrogenated counterparts due to the appearance of midgap edge states. Overall, our studies provide a basis for tailoring the electronic properties of phosphorene nanoribbons by controlling the edge termination via processing conditions (temperature and hydrogen partial pressure) as well as by confinement of carriers via control over ribbon width.

Ramasubramaniam, Ashwin; Muniz, Andre R.

2014-08-01

285

NASA Astrophysics Data System (ADS)

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 ?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-Grüneisen-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.

Antoshechkina, P. M.; Wolf, A. S.; Hamecher, E. A.; Asimow, P. D.; Ghiorso, M. S.

2013-12-01

286

The Beattle-Bridgeman equation of state was used to calculate several of ; the thermodynamic properties and fiow process correction factors for air. The ; increase in the specific heats due to the vibration of diatomic molecules was ; included by assuming the molecules to be perfect harmonic oscillators. This ; report contains the equations used and the tabulated results of

1957-01-01

287

Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy Available online 25 November 2011 Keywords: Clusters Interaction potentials Range of interactions Topography for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures

Berry, R. Stephen

288

Using an integral-equation approach based upon an approximation for the tail function, the equilibrium properties of a system of hard spheres are studied with special concern for the behavior in the region of close packing. The closure adopted is such that full, internal consistency is ensured in the thermodynamics of the model with respect to both the two zero-separation theorems

P. V. Giaquinta; G. Giunta; G. Malescio

1991-01-01

289

Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re - phase Mauro, 144502 (2014); doi: 10.1063/1.4869800 View online: http://dx.doi.org/10.1063/1.4869800 View Table Publishing Articles you may be interested in Elastic, superconducting, and thermodynamic properties

AlfÃ¨, Dario

290

Ab initio calculation of lattice dynamics and thermodynamic properties of beryllium Fen Luo, Ling: 10.1063/1.3688344 View online: http://dx.doi.org/10.1063/1.3688344 View Table of Contents: http (2011) Note: Extraction of hydrogen bond thermodynamic properties of water from dielectric constant

AlfÃ¨, Dario

291

Molecular simulation of thermodynamic and transport properties for the H2O+NaCl system.

Molecular dynamics and Monte Carlo simulations have been carried out to obtain thermodynamic and transport properties of the binary mixture H2O+NaCl at temperatures from T = 298 to 473 K. In particular, vapor pressures, liquid densities, viscosities, and vapor-liquid interfacial tensions have been obtained as functions of pressure and salt concentration. Several previously proposed fixed-point-charge models that include either Lennard-Jones (LJ) 12-6 or exponential-6 (Exp6) functional forms to describe non-Coulombic interactions were studied. In particular, for water we used the SPC and SPC/E (LJ) models in their rigid forms, a semiflexible version of the SPC/E (LJ) model, and the Errington-Panagiotopoulos Exp6 model; for NaCl, we used the Smith-Dang and Joung-Cheatham (LJ) parameterizations as well as the Tosi-Fumi (Exp6) model. While none of the model combinations are able to reproduce simultaneously all target properties, vapor pressures are well represented using the SPC plus Joung-Cheathem model combination, and all LJ models do well for the liquid density, with the semiflexible SPC/E plus Joung-Cheatham combination being the most accurate. For viscosities, the combination of rigid SPC/E plus Smith-Dang is the best alternative. For interfacial tensions, the combination of the semiflexible SPC/E plus Smith-Dang or Joung-Cheatham gives the best results. Inclusion of water flexibility improves the mixture densities and interfacial tensions, at the cost of larger deviations for the vapor pressures and viscosities. The Exp6 water plus Tosi-Fumi salt model combination was found to perform poorly for most of the properties of interest, in particular being unable to describe the experimental trend for the vapor pressure as a function of salt concentration. PMID:25527948

Orozco, Gustavo A; Moultos, Othonas A; Jiang, Hao; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

2014-12-21

292

Molecular simulation of thermodynamic and transport properties for the H2O+NaCl system

NASA Astrophysics Data System (ADS)

Molecular dynamics and Monte Carlo simulations have been carried out to obtain thermodynamic and transport properties of the binary mixture H2O+NaCl at temperatures from T = 298 to 473 K. In particular, vapor pressures, liquid densities, viscosities, and vapor-liquid interfacial tensions have been obtained as functions of pressure and salt concentration. Several previously proposed fixed-point-charge models that include either Lennard-Jones (LJ) 12-6 or exponential-6 (Exp6) functional forms to describe non-Coulombic interactions were studied. In particular, for water we used the SPC and SPC/E (LJ) models in their rigid forms, a semiflexible version of the SPC/E (LJ) model, and the Errington-Panagiotopoulos Exp6 model; for NaCl, we used the Smith-Dang and Joung-Cheatham (LJ) parameterizations as well as the Tosi-Fumi (Exp6) model. While none of the model combinations are able to reproduce simultaneously all target properties, vapor pressures are well represented using the SPC plus Joung-Cheathem model combination, and all LJ models do well for the liquid density, with the semiflexible SPC/E plus Joung-Cheatham combination being the most accurate. For viscosities, the combination of rigid SPC/E plus Smith-Dang is the best alternative. For interfacial tensions, the combination of the semiflexible SPC/E plus Smith-Dang or Joung-Cheatham gives the best results. Inclusion of water flexibility improves the mixture densities and interfacial tensions, at the cost of larger deviations for the vapor pressures and viscosities. The Exp6 water plus Tosi-Fumi salt model combination was found to perform poorly for most of the properties of interest, in particular being unable to describe the experimental trend for the vapor pressure as a function of salt concentration.

Orozco, Gustavo A.; Moultos, Othonas A.; Jiang, Hao; Economou, Ioannis G.; Panagiotopoulos, Athanassios Z.

2014-12-01

293

ThermoML is an Extensible Markup Language (XML)-based new\\u000d\\u000aIUPAC standard for storage and exchange of experimental, predicted, and critically\\u000d\\u000aevaluated thermophysical and thermochemical property data. The basic principles,\\u000d\\u000ascope, and description of all structural elements of ThermoML are discussed.\\u000d\\u000aThermoML covers essentially all thermodynamic and transport property\\u000d\\u000adata (more than 120 properties) for pure compounds, multicomponent mixtures,\\u000d\\u000aand chemical reactions

MICHAEL FRENKEL; ROBERT D. CHIRICO; VLADIMIR DIKY; QIAN DONG; KENNETH N. MARSH; JOHN H. DYMOND; WILLIAM A. WAKEHAM; STEPHEN E. STEIN; ERICH KÖNIGSBERGER; ANTHONY R. H. GOODWIN

2006-01-01

294

NASA Astrophysics Data System (ADS)

First-principle calculations based on density functional theory are adopted to investigate the structural, electronic and thermodynamic properties of BiF3-type Mg3Gd compound. Our results for the equilibrium structural parameters are consistent with experimental values and other theoretical results. The single-crystal elastic constants, polycrystalline elastic moduli, Poisson's ratio and anisotropy factor are determined using the Voigt-Reuss-Hill approximation. Estimated Cauchy pressure and the G/B relationship indicate that Mg3Gd is mechanically stable and brittle. In addition, the electronic structure is studied within the generalized gradient approximation (GGA) and local spin density approximation (LSDA) along with Hubbard energy. The calculations associated with phonon properties confirm the dynamical stability of BiF3-type structure. Finally, the dependences of normalized volume, bulk modulus and thermodynamic properties of Mg3Gd are obtained via the quasi-harmonic Debye model.

Liu, Yong; Hu, Wen-Cheng; Li, De-Jiang; Zeng, Xiao-Qin; Xu, Chun-Shui; Yang, Xiang-Jie

2014-01-01

295

In this study, we use solubility and oxide melt solution calorimetry measurements to determine the thermodynamic properties of the uranyl phosphate phases autunite (abbreviated: CaUP), uranyl hydrogen phosphate (HUP), and uranyl orthophosphate (UP). Solubility measurements from both supersaturated and undersaturated conditions, as well as under different pH conditions, rigorously demonstrate attainment of equilibrium and yield well-constrained solubility product values of -48.36 (-0.03 /+ 0.03), -13.17 (-0.11 / +0.07), and -49.36 (-0.04 / +0.02) for CaUP, HUP, and UP, respectively. We use the solubility data to calculate standard state Gibbs free energies of formation for all phases (-7630.61 ± 9.69, -3072.27 ± 4.76, and -6138.95 ± 12.24 kJ mol-1 for CaUP, HUP, and UP, respectively), and calorimetry data to calculate standard state enthalpies of formation of -3223.22 ± 4.00 and -7001.01 ± 15.10 kJ mol-1 for HUP and UP, respectively. Combining these results allows us also to calculate the standard state entropies of formation of -506.54 ± 10.48 and -2893.12 ± 19.44 kJ mol-1 K-1 for HUP and UP phases, respectively. The results from this study are part of a combined effort to develop reliable and internally consistent thermodynamic data for environmentally relevant uranyl minerals. Data such as these are required in order to optimize and quantitatively assess the effect of phosphate amendment remediation technologies for uranium contaminated systems.

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

296

Free-standing silicene obtained by cooling from 2D liquid Si: structure and thermodynamic properties

NASA Astrophysics Data System (ADS)

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.

Van Hoang, Vo; Thi Cam Mi, Huynh

2014-12-01

297

Experimental Study of the Thermodynamic Properties of Diethyl Ether (DEE) at Saturation

NASA Astrophysics Data System (ADS)

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.

Polikhronidi, N. G.; Abdulagatov, I. M.; Batyrova, R. G.; Stepanov, G. V.; Ustuzhanin, E. E.; Wu, J. T.

2011-03-01

298

canonical ensemble. Mechanical properties are used to help characterize and identify the Na+-MMT structure. Several elastic properties such as compliance and stiffness matrices, Young's, shear, and bulk modulus, volume compressibility, Poisson's ratios, Lamé...

Atilhan, Selma

2009-05-15

299

A technique for preparing thermodynamic property tables using incomplete data sets

Extended corresponding states (ECS) algorithms provide versatile predictions for the thermophysical properties of mixtures. The NIST14 computer database implements an ECS model and the resultant property calculations are remarkably accurate for a wide variety of mixtures. This model emphasizes single phase calculations for many systems and properties, and it has the usual difficulties with the phase envelope and the critical

H Duarte-Garza; J. C Holste; K. R Hall; G. A Iglesias-Silva

1998-01-01

300

High-temperature thermodynamic properties of the thorium-oxygen system

The thermodynamic properties of the thorium-oxygen system at high temperatures have been investigated by means of mass effusion, mass spectrometric, and transpiration techniques over compositions ranging from the congruently vaporizing composition to the lower phase boundary composition. A very sharp decrease in oxygen potential occurs when stoichiometric thoria is reduced but slightly from the stoichiometric composition. The small extent of reduction over a wide range of oxygen potentials measured in the temperature range 2400 to 2655/sup 0/K is a clear illustration of the higher stability of the ThO/sub 2-x/ phase compared with actinide-oxides such as UO/sub 2-x/, PuO/sub 2-x/, as well as other metal oxide systems. Estimates of ..delta.. anti H/sub O/sub 2//, ..delta.. anti S/sub O/sub 2//, and the standard free energy of formation of bivariant ThO/sub 2-x/ compositions have been made. A substantial increase in the total pressure of thorium-bearing species occurs when stoichiometric thoria is reduced toward the lower phase boundary. The increase in pressure can be attributed primarily to the increasing contribution of the ThO gaseous species. Total pressures of thorium-bearing species above ThO/sub 2-x/ compositions calculated by means of experimental oxygen potentials and the known or estimated free energy of formation values of the gaseous species and condensed phase are in reasonable agreement with experimental values. 8 figures, 3 tables.

Ackermann, R.J.; Tetenbaum, M.

1980-01-01

301

This report discusses theoretical and experimental work aimed at elucidating the effects of molecular structure and intermolecular forces on macroscopic thermodynamic properties. Theoretically, we have learned how to treat various molecular interactions so that quantitative predictions can be made for a variety of complex molecules and mixtures. These include Lennard-Jones interactions for non-polar molecules, anisotropic interactions for dipolar and quadrupolar molecules, and association effects (such as hydrogen bonding). In addition, a simplified version of the theory was developed which can be compared easily with other commonly used equations (namely, Peng-Robinson, Redlich-Kwong or van der Waals). The experimental portion of this program involves precise measurements of phase behavior for binary and ternary mixtures involving quadrupolar molecules. Experiments were conducted to determine the enhancement of solubility for 1-methyl naphthalene in super-critical carbon dioxide when toluene is added in small amounts. A new experimental apparatus is being built to study the vapor-liquid equilibria up to 4000 psia. 32 references, 13 figures, 5 tables.

Donohue, M.D.

1984-05-01

302

Thermodynamic Properties of He Gas in the Temperature Range 4.2-10 K

NASA Astrophysics Data System (ADS)

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.

Mosameh, S. M.; Sandouqa, A. S.; Ghassib, H. B.; Joudeh, B. R.

2014-05-01

303

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of State

NASA Astrophysics Data System (ADS)

Cubic equations of state are widely used by chemists and chemical engineers to predict the thermodynamic properties of both pure substances and mixtures. In particular, they enable predictions concerning the temperature and pressure at which vapor liquid equilibrium occurs. In this article, two JavaScript programs are described. The first program gives students the choice of five different cubic equations of state and performs calculations for pure substances. The second program predicts vapor liquid equilibrium for binary mixtures using a choice of three modern equations of state and the van der Waals mixing rules. There are three advantages to using JavaScript and a Web interface for these programs. Firstly, the program contains online theory so that, rather than just calculating the parameter, the program explains how the calculation is being performed. Secondly, virtually all students are familiar with how forms work when they are used on Web pages and so they find the program straightforward to use. Thirdly, the Web interface means that it is easy for a student to vary a parameter and observe its influence on the answer or to repeat a calculation using a different equation of state.

Barrie, Patrick J.

2005-06-01

304

The thermodynamic and ground state properties of the TIP4P water octamer.

Several stochastic simulations of the TIP4P [W. L. Jorgensen, J. Chandrasekhar, J. D. Madura, R. W. Impey, and M. L. Klein, J. Chem. Phys. 79, 926 (1983)] water octamer are performed. Use is made of the stereographic projection path integral and the Green's function stereographic projection diffusion Monte Carlo techniques, recently developed in one of our groups. The importance sampling for the diffusion Monte Carlo algorithm is obtained by optimizing a simple wave function using variational Monte Carlo enhanced with parallel tempering to overcome quasiergodicity problems. The quantum heat capacity of the TIP4P octamer contains a pronounced melting peak at 160 K, about 50 K lower than the classical melting peak. The zero point energy of the TIP4P water octamer is 0.0348+/-0.0002 hartree. By characterizing several large samples of configurations visited by both guided and unguided diffusion walks, we determine that both the TIP4P and the SPC [H. J. C. Berendsen, J. P. Postma, W. F. von Gunsteren, and J. Hermans, (Intermolecular Forces, Reidel, 1981). p. 331] octamer have a ground state wave functions predominantly contained within the D(2d) basin of attraction. This result contrasts with the structure of the global minimum for the TIP4P potential, which is an S(4) cube. Comparisons of the thermodynamic and ground-state properties are made with the SPC octamer as well. PMID:19916613

Asare, E; Musah, A-R; Curotto, E; Freeman, David L; Doll, J D

2009-11-14

305

NASA Astrophysics Data System (ADS)

We consider the thermodynamic and kinetic properties of Nickel as an example of transition metal in two-temperature state (Te?Ti,) produced by femtosecond laser heating. Our physical model includes essential processes induced in metals by ultrafast laser energy absorption. Specifically, the electron-ion collision frequency was obtained from recent high-temperature measurements of electrical conductivity and electron-electron screened Coulomb scattering was calculated by taking into account s-s and s-d collisions. In addition, chemical potential, energy, heat capacity, and pressure were obtained from first-principles density functional theory calculations. This model was implemented in two-temperature hydrodynamic code (2T-HD) and combined with molecular dynamics (MD) to determine strength of molten Ni at high strain rates ˜108-109s-1 under conditions of femtosecond laser ablation experiments. The simulated ablation threshold, which depends on material strength, was found to be in good agreement with our experimental measurements reported here. The combined 2T-HD/MD modeling explains the surprisingly high experimental energy density necessary to initiate ablation in Ni (the experimental crater depth in Ni is several times smaller than in Al and Au, while ablation threshold energies are similar).

Inogamov, N. A.; Petrov, Yu. V.; Zhakhovsky, V. V.; Khokhlov, V. A.; Demaske, B. J.; Ashitkov, S. I.; Khishchenko, K. V.; Migdal, K. P.; Agranat, M. B.; Anisimov, S. I.; Fortov, V. E.; Oleynik, I. I.

2012-07-01

306

Energetic stability, structural transition, and thermodynamic properties of ZnSnO3

NASA Astrophysics Data System (ADS)

First principles calculations were performed on ZnSnO3 polymorphs to understand their energetic stability and structural transition under high pressure environments. The experimentally-identified ilmenite (IL)-type and LiNbO3 (LN)-type ZnSnO3 may coexist at zero pressure considering the effect of zero point energy. IL-type ZnSnO3 becomes unstable under high pressure due to the appearance of imaginary frequency in phonon spectra. Enthalpy differences suggest that the phase stability follows the sequence: ZnO+SnO2 below 5.9 GPa, Zn2SnO4+SnO2 up to 7.1 GPa, and LN-type phase above 7.1 GPa. Pressurization at 34.5 GPa causes a phase transformation from the LN-type to the orthorhombic CdSnO3-type. Thermodynamic properties including Helmholtz free energy, specific heat at constant volume and Debye temperature were also calculated.

Gou, Huiyang; Zhang, Jingwu; Li, Zhiping; Wang, Gongkai; Gao, Faming; Ewing, Rodney C.; Lian, Jie

2011-02-01

307

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

Kaya, Ismet; Pala, Cigdem Yigit

2014-07-01

308

Measurement and modelling of high temperature thermodynamic properties of URh3 alloy

NASA Astrophysics Data System (ADS)

The high temperature phase stability of arc-melted cubic URh3 intermetallic compound has been investigated using high temperature inverse drop calorimetry in the temperature range of 300-1273 K. URh3 exists as a line compound with negligible solubility range. Room temperature XRD profile and elemental X-ray mapping experiments on 1273 K/3 h homogenized samples have confirmed the homogeneity and L12 (cF8; pm3m) crystal structure of URh3. The drop measurements yielded accurate values for the enthalpy increment ?HT0 as a function of temperature, from which the specific heat CP has been estimated. The enthalpy data obtained in this study have been compared and combined with the reported data on low temperature CP and also with the ?HT0 in the temperature range, 0-840 K, for a comprehensive theoretical analysis using quasiharmonic Debye-Grüneisen formalism. It is found that this model with due allowance for thermal expansion effects can successfully account for the experimentally measured thermal property data in the entire temperature region spanning 0-1273 K. Invoking a combination of measurement and modelling, a comprehensive set of thermodynamic quantities have been obtained for URh3.

Rai, Arun Kumar; Tripathy, Haraprasanna; Jeya Ganesh, B.; Raju, S.

2012-08-01

309

Perturbation theory for the thermodynamic properties of liquid nitrogen using model potentials

NASA Astrophysics Data System (ADS)

A statistical mechanical perturbation theory due to Fischer has been used to calculate thermodynamic properties of liquid nitrogen for model intermolecular potentials due to Cheung and Powles (CP), Raich and Gillis (RG), and Berns and van der Avoird (BV). Refinements in the numerical implementation of the Fischer theory are described. Results for the CP potential agree well with both simulation and experimental data except at high density and high temperature. Differences between theory and experiment are usually comparable to the differences between two sets of experimental data for the CP potential but are generally larger for the other two potentials. For both BV and RG potentials the excess Helmholtz energies and excess internal energies are up to 15 and 10 per cent higher, respectively, than experimental values whereas the predicted pressures are low by 100-200 bar for RG and 50-100 bar for BV. The BV potential is slightly more satisfactory than the RG potential overall. Results for spherical harmonic components of the radial correlation function for the CP potential calculated using zeroth and first order approximations in the Fischer theory and also in the RAM theory are also compared with results from molecular dynamics simulations.

Watanabe, K.; Allnatt, A. R.; Meath, W. J.

310

Magnetic and thermodynamic properties of face-centered cubic Fe-Ni alloys.

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

Lavrentiev, M Yu; Wróbel, J S; Nguyen-Manh, D; Dudarev, S L

2014-08-14

311

Structural and Thermodynamic Properties of Selective Ion Binding in a K+ Channel

Thermodynamic measurements of ion binding to the Streptomyces lividans K+ channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K+, Rb+, Cs+, and Ba2+) bound and not with smaller ions (Na+, Mg2+, and Ca2+). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 Angstroms from the ions. We conclude that ion selectivity in a K+ channel is a property of size-matched ion binding sites created by the protein structure.

Lockless,S.; Zhou, M.; MacKinnon, R.

2007-01-01

312

NASA Astrophysics Data System (ADS)

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.

Jacobs, M.; Schmid-Fetzer, R.

2012-04-01

313

NASA Astrophysics Data System (ADS)

The presence of a quantum critical point can significantly affect the thermodynamic properties of a material at finite temperatures. This is reflected, e.g., in the entropy landscape S(T, c) in the vicinity of a quantum critical point, yielding particularly strong variations for varying the tuning parameter c such as magnetic field. In this work we have studied the thermodynamic properties of the quantum compass model in the presence of a transverse field. The specific heat, entropy and cooling rate under an adiabatic demagnetization process have been calculated. During an adiabatic (de)magnetization process temperature drops in the vicinity of a field-induced zero-temperature quantum phase transitions. However close to field-induced quantum phase transitions we observe a large magnetocaloric effect.

Jafari, R.

2012-05-01

314

NASA Technical Reports Server (NTRS)

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.

Colon, G.

1981-01-01

315

NASA Astrophysics Data System (ADS)

We investigate the structural and thermodynamic properties of cerium in ? phase by using the first-principles plane wave method with a relativistic analytic pseudopotential of Hartwigsen, Goedcker and Hutter (HGH) scheme in the frame of local density approximation (LDA). The obtained lattice constant and bulk modulus are consistent with the available experimental data. Moreover, dependences of the normalized primitive volume V/V0 on pressure and the thermodynamic quantities (including the Grüneisen constant ? and thermal expansion ?) on temperature and pressure are obtained. The obtained linear thermal expansion parameter ? (9.857 × 10-6 K-1 at 293.15K and 0GPa) is slightly larger than the experimental value (6.3 × 10-6 K-1). All the results indicate that we provide an effective method to deal with the ground properties of the strongly interacting d- and/or f-electron systems.

Sun, Li-Li; Ji, Guang-Fu; Chen, Xiang-Rong; Gou, Qing-Quan

2009-01-01

316

We analyze thermodynamics of water samples confined in nanopores and prove that although the freezing temperature can be dramatically lower, the suppression of the ice nucleation leading to the freezing temperature depression is a truly macroscopic effect rather than a consequence of microscopic interactions. The freezing transition itself is a truly collective phenomenon described by a macroscopic order parameter (the nearly homogeneous density of the liquid within the pore away from the pores wall) exactly in the same way as in the bulk liquid. The thermodynamics properties of the confined and the bulk liquid can be described by macroscopic thermodynamics and be readily related to each other simply by proper inclusion of the additional Laplace pressure exerted by the solid-liquid boundary.

P. O. Fedichev; L. I. Menshikov

2012-06-15

317

NASA Technical Reports Server (NTRS)

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.

Gordon, S.

1982-01-01

318

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.

Gordon, S.

1982-07-01

319

NASA Astrophysics Data System (ADS)

By using the new approximation type, the Dirac equation is solved with the combination of Generalized Pöschl-Teller and Hyperbolical potentials within the framework of supersymmetric approach. The energy levels are obtained for both pseudospin and spin symmetries and the nonrelativistic limit is obtained with the corresponding wave functions in terms of hypergeometric functions. Some thermodynamic properties are equally obtained with the energy equation of the nonrelativistic limit.

Onate, C. A.; Ojonubah, J. O.

2015-03-01

320

Mixtures of refrigerants are widely used as working substances for refrigerating plants. Among them, mixtures of ozone-safe and natural refrigerants, in particular R23\\/R744 and R41\\/R744, are important. For calculating their thermodynamic properties, we compiled equations of state on the basis of the method in (1). According to this reference, the equation of state for a mixture is presented as a

Aleksandr Vasserman C; Valentine Malchevsky S

321

Thermodynamic Properties of CaNdAlO 4 -SrNdAlO 4 Solid Solutions

The structural and thermodynamic properties of CaNdAlO4-SrNdAlO4 solid solutions are studied at 1673 K by x-ray diffraction and high-temperature calorimetry. The lattice parameters and unit-cell volume of the solid solutions are shown to vary linearly with composition. The measured heats of solid solution are used to evaluate the enthalpies of formation from the constituent oxides and constituent elements and the

L. N. Komissarova; M. A. Ryumin; G. Ya. Pushkina; G. V. Zimina; A. V. Novoselov; A. Pajaczkowska; M. A. Borik; A. L. Il’inskii

2005-01-01

322

NASA Astrophysics Data System (ADS)

First-principles calculations have been performed to obtain the thermodynamic properties of hbox {ScAlO}3 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 hbox {ScAlO}3 compounds with reasonable accuracy.

Abdollahi, Arash; Gholzan, Seyed Maghsoud

2015-03-01

323

NASA Astrophysics Data System (ADS)

The garnet class of phases is extremely broad in terms of composition and structural properties. Garnet is found in nature and various synthetic garnet phases have a number of important technical applications. There exist the rock-forming silicate garnets that are so widespread geologically. An additional class is given by the so-called "hydrogarnets" in which the tetrahedral site (Wyckoff position 24d) is empty. At relatively low temperatures there is complete solid solution between Ca3Al2Si3O12 and Ca3Al2H12O12, for example. The substitution mechanism can be written as O4H4 \\lrarr SiO4. The latter, pure OH-containing end-member, which has not been found in nature, is termed katoite/hydrogrossular. Its structure has been investigated by various workers by X-ray and neutron diffraction and by proton NMR, IR and Raman spectroscopic methods. At ambient conditions the structure has the "standard" garnet cubic symmetry of Ia-3d. At high pressures, and possibly at low temperatures, a different structure may occur. We measured the low temperature IR spectra and heat capacity of katoite in order to understand its structural, crystal-chemical and thermophysical properties. A sample of Ca3Al2H12O12 was synthesized hydrothermally in Au capsules at 250 °C and 3 kb water pressure. X-ray powder measurements show that about 98-99% katoite was obtained. Powder IR spectra were recorded between 298 K and 10 K. The measured spectra are considerably different in the high wavenumber region, where O-H stretching modes occur, between 298 K and 10 K. At room temperature the IR-active O-H band located around 3662 cm-1 is broad and it narrows and shifts to higher wavenumbers and also develops structure below about 80 K. Concomitantly, additional weak intensity O-H bands located around 3600 cm-1 begin to appear and they become sharper and increase in intensity with further decreases in temperature down to 10 K. The spectra indicate that the vibrational behavior of individual OH groups and their collective interactions measurably affect the lattice dynamic (i.e. thermodynamic) behavior. The low temperature heat capacity behavior was investigated with a commercially designed relaxation calorimeter between 5 and 300 K on a mg-sized sample. The heat capacity data are well behaved at T < 300 K and show a monotonic decrease in magnitude with decreasing temperature. A standard third-law entropy value of So = 421.7 ± 1.6 J/mol·K was calculated. Using this new calorimetric-based So value and published standard enthalpy of formation data for katoite, a calorimetric-based Gibbs free energy of formation at 298 K can be obtained as ?G°f = -5021.2 kJ/mol. The Cp data show no evidence for any phase transition as possibly expected by the change in OH-mode behavior with decreasing temperature. We have no explanation for the appearance of the additional modes. It is worth noting that the katoite crystal structure in terms of lattice dynamic or thermodynamic behavior should be thought of having OH groups and not O4H4 clusters or polyhedral units as is often written in the literature. The single crystallographic OH group in katoite shows very weak, if any, hydrogen bonding and the H atoms have large amplitudes of vibration. The weak H bonding controls the nature of low energy OH-related vibrations and this leads to its large So value.

Geiger, C. A.; Dachs, E.

2012-04-01

324

National Institute of Standards and Technology Data Gateway

SRD 10 NIST/ASME Steam Properties Database (PC database for purchase) Based upon the International Association for the Properties of Water and Steam (IAPWS) 1995 formulation for the thermodynamic properties of water and the most recent IAPWS formulations for transport and other properties, this updated version provides water properties over a wide range of conditions according to the accepted international standards.

325

Thermodynamic and mechanical properties of copper precipitates in ?-iron from atomistic simulations

NASA Astrophysics Data System (ADS)

Precipitate hardening is commonly used in materials science to control strength by acting on the number density, size distribution, and shape of solute precipitates in the hardened matrix. The Fe-Cu system has attracted much attention over the last several decades due to its technological importance as a model alloy for Cu steels. In spite of these efforts several aspects of its phase diagram remain unexplained. Here we use atomistic simulations to characterize the polymorphic phase diagram of Cu precipitates in body-centered cubic (BCC) Fe and establish a consistent link between their thermodynamic and mechanical properties in terms of thermal stability, shape, and strength. The size at which Cu precipitates transform from BCC to a close-packed 9R structure is found to be strongly temperature dependent, ranging from approximately 4 nm in diameter (˜2700atoms) at 200 K to about 8 nm (˜22800atoms) at 700 K. These numbers are in very good agreement with the interpretation of experimental data given Monzen [Philos. Mag. APMAADG0141-861010.1080/01418610008212077 80, 711 (2000)]. The strong temperature dependence originates from the entropic stabilization of BCC Cu, which is mechanically unstable as a bulk phase. While at high temperatures the transition exhibits first-order characteristics, the hysteresis, and thus the nucleation barrier, vanish at temperatures below approximately 300 K. This behavior is explained in terms of the mutual cancellation of the energy differences between core and shell (wetting layer) regions of BCC and 9R nanoprecipitates, respectively. The proposed mechanism is not specific for the Fe-Cu system but could generally be observed in immiscible systems, whenever the minority component is unstable in the lattice structure of the host matrix. Finally, we also study the interaction of precipitates with screw dislocations as a function of both structure and orientation. The results provide a coherent picture of precipitate strength that unifies previous calculations and experimental observations.

Erhart, Paul; Marian, Jaime; Sadigh, Babak

2013-07-01

326

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

2014-01-01

327

A complete thermodynamic and kinetic solution study on lanthanide(iii) complexes with monoacetamide (DOTAMA, ) and monopropionamide (DOTAMAP, ) derivatives of DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was undertaken with the aim to elucidate their stability and inertness in aqueous media. The stability constants of Gd and Gd are comparable, whereas a more marked difference is found in the kinetic inertness of the two complexes. The formation of the Eu(iii) and Ce(iii) complexes takes place via the formation of the protonated intermediates which can deprotonate and transform into the final complex through a OH(-) assisted pathway. Gd shows faster rates of acid catalysed decomplexation with respect to Gd, which has a kinetic inertness comparable to GdDOTA. Nevertheless, Gd is one order of magnitude more inert than GdDO3A. A novel DOTAMAP-based bifunctional chelating ligand and its deoxycholic acid derivative () were also synthesized. Since the coordinated water molecule in Gd is characterized by an exchange rate ca. two orders of magnitude greater than in Gd, the relaxivity of the macromolecular derivatives of Gd should not be limited by the slow water exchange process. The relaxometric properties of the supramolecular adduct of Gd with human serum albumin (HSA) were investigated in aqueous solution by measuring the magnetic field dependence of the (1)H relaxivity which, at 20 MHz and 298 K, shows a 430% increase over that of the unbound Gd chelate. Thus, Gd(iii) complexes with DOTAMAP macrocyclic ligands can represent good candidates for the development of stable and highly effective bioconjugate systems for molecular imaging applications. PMID:25695351

Tei, Lorenzo; Baranyai, Zsolt; Gaino, Luca; Forgács, Attila; Vágner, Adrienn; Botta, Mauro

2015-03-10

328

Thermodynamic properties of alloys of the Al-Co and Al-Co-Sc systems

NASA Astrophysics Data System (ADS)

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).

Shevchenko, M. A.; Berezutskii, V. V.; Ivanov, M. I.; Kudin, V. G.; Sudavtsova, V. S.

2014-05-01

329

NASA Astrophysics Data System (ADS)

The dependences of the structural, electronic, mechanical, and thermodynamic properties of AlSc2 compound on pressure were investigated for the first time by means of the first-principles method based on the density functional theory with generalized gradient approximation and local density approximation. It was found that the pressure has significant effects on the equilibrium volume, mechanical properties, electronic properties and the heat capacity. Our calculated structural data are in good agreement with the previous experimental and theoretical data results. The calculated elastic constants indicate that the AlSc2 compound is mechanically stable in the pressure range of 0-50 GPa. The Zener ratio A and linear compressibility coefficients kc/ka are used to estimate anisotropic elasticity. The isotropic bulk modulus B, shear modulus G, Young's modulus E, and Poisson's ratio ? of polycrystalline AlSc2 compound were determined using the Voigt-Reuss-Hill averaging scheme. The B/G, Poisson's ratio and microhardness parameter are calculated. The band structure and density of states are also discussed. The Debye temperature can be obtained from the elastic constants and the sound velocities and the pressure has little influence. The temperature-dependent behavior of thermodynamical properties (internal energy, entropy, free energy, and heat capacity) at 0, 20, and 40 GPa have been obtained from phonon density of states.

Pang, Mingjun; Zhan, Yongzhong; Wang, Haizhou; Jiang, Wenping; Du, Yong

2011-08-01

330

NASA Astrophysics Data System (ADS)

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.

Seddik, T.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Bin-Omran, S.; Rached, D.

2012-03-01

331

Unified approach to electronic, thermodynamical, and transport properties of Fe3Si and Fe3Al alloys

NASA Astrophysics Data System (ADS)

The electronic, thermodynamical, and transport properties of ordered Fe3X (X =Al,Si) alloys are studied from first principles. We present here a unified approach to the phase stability, the estimate of the Curie temperature, the temperature dependence of sublattice magnetizations, magnon spectra, the spin-stiffnesses, and residual resistivities. An important feature of the present study is that all calculated physical properties are determined in the framework of the same first-principles electronic structure model combined with the effective Ising and Heisenberg Hamiltonians used for study of the thermodynamical properties of alloys. Curie temperatures, spin-stiffnesses, and magnon spectra are determined using the same calculated exchange integrals. Finally, the transport properties are calculated using the linear-response theory. Our theoretical estimates compare well with available experimental data. In particular, calculations predict (in agreement with experiment) the ordered D03 phase as the ground-state alloy structure, demonstrate that a correct relation of Curie temperatures of Fe3Al/Fe3Si alloys can be obtained only by going beyond a simple mean-field approximation, provide reasonable estimates of spin-stiffnesses, and give resistivities compatible with structural disorder observed in the experiment. Although the calculated temperature dependences of the Fe magnetization on different sublattices are similar, they nevertheless deviate more than in the experiment, and we discuss a possible origin.

Kudrnovský, J.; Drchal, V.; Bergqvist, L.; Rusz, J.; Turek, I.; Újfalussy, B.; Vincze, I.

2014-10-01

332

NSDL National Science Digital Library

For engineering graduates entering the job market, experience with appropriate computational tools and techniques is increasingly necessary. Therefore, the University of Alabama's Mechanical Engineering Department is introducing students to computational problem solving earlier in their college careers by developing Microsoft Excel-based modules to be used as teaching tools in the sophomore and junior-level thermodynamics and heat transfer courses. The MS Excel package was chosen as a software platform for this purpose because of its ubiquitous nature and its ability to utilize Visual Basic for Applications (VBA) macros in a spreadsheet format. In the sophomore-level thermodynamics course, much of the class material focuses on the properties of steam and ideal gases. Therefore, a suite of Microsoft Excel functions to compute steam and ideal gas properties and assist in analyzing properties of states and processes has been developed. A number of Excel packages that pertained to the computation of steam properties were already available in the public domain. In a companion paper1, these packages were compared and Magnus Holmgrens Xsteam functions were chosen as a starting point for the current project.

Huguet, Jesse

333

The objectives of this research project are to: develop a thermodynamic properties correlation framework for pure coal fluids; extend the framework to prediction of thermodynamic properties of defined binary mixtures; develop correlations for the correlation characterization parameters in terms of routinely measured variables; and develop methods for applying the thermodynamic and characterization correlations to undefined coal systems in ways which make the results useful for design. This report is organized into 5 sections. The mean potential model equation of state developed in this research is presented in section I. Application of the correlation to predict the thermodynamic properties of nonpolar, polar, and associating pure compounds is presented in section II. In section III, property predictions for defined mixtures are discussed. Methods for applying the correlation to undefined mixtures are presented in section IV. In section V, the results of enthalpy, volatility, bubble point, and K-value calculations for several actual coal-fluid systems are presented. 144 references, 5 figures, 25 tables.

Starling, K.E.; Lee, L.L.; Watanasiri, S.; Kumar, K.H.; Brule, M.R.; Chung, T.H.; Luong, T.H.; Owens, V.H.; Khalil, M.A.; Khan, M.A.

1983-01-01

334

The thermodynamic properties of 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene

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.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K.; Steele, W.V.

1992-12-01

335

Thermodynamic properties of isobutane-isopentane mixtures from -40 to +600(0)F and up to 1000 psia

NASA Astrophysics Data System (ADS)

The Helmboltz function for pure isobutane from a recent correlation was converted to a dimensionless form and a pressure enthalpy chart based on this function was generated by computer. A Helmholtz function for mixtures of isobutane and isopentane was formed based upon the dimensionless corresponding states principle. Scarce literature data for saturation properties of isopentane, and new data for its vapor pressure and for the critical line of the mixture, were used. The accuracy of the surface was checked by comparing with literature enthalpy data and with new VLE data for the mixture. Tables of thermodynamic properties were generated from this Helmholtz function for the 0.1 mole fraction isopentane-in-isobutane mixture in the single phase region and on the dew and bubble point curves, together with properties of the coexisting phase. A pressure enthalpy chart for this mixture was also generated.

Gallagher, J. S.; Sengers, J. M. H. L.; Morrison, G.; Sengers, J. V.

1984-07-01

336

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 < ? < 2?. It enables a unified approach to both wedges and edges. PMID:25554179

Urrutia, Ignacio

2014-12-28

337

Thermodynamic properties and cloud droplet activation of a series of oxo-acids

NASA Astrophysics Data System (ADS)

Submicron sized aerosol particles in the Earth's atmosphere influence visibility, human health, and global climate (IPCC, 2007). The organic mass fraction of the atmospheric aerosol has been estimated at 20-90% of the total aerosol mass mass (Kanakidou et al., 2005). Many of the organic species found in the particle phase in the atmosphere are produced via the oxidation of biogenic hydrocarbon emissions such as terpenes and sesquiterpenes (Hallquist et al. 2009). We have investigated the thermodynamic properties of four aliphatic oxo-dicarboyxlic acids identified or thought to be present in atmospheric particulate matter: oxosuccinic acid, 2-oxoglutaric acid, 3-oxoglutaric acid, and 4-oxopimelic acid. The compounds were characterized in terms of their cloud condensation nuclei (CCN) activity, vapor pressure, density, and tendency to decarboxylate in aqueous solution. We deployed a variety of experimental techniques and instruments: a CCN counter, a Tandem Differential Mobililty Analyzer (TDMA) coupled with a laminar flow tube (Bilde, 2003), and liquid chromatography/mass spectrometry (LC/MS). Generally, the presence of the oxo functional group causes the vapor pressure of the compounds to diminish by an order of magnitude with respect to the parent dicarboxylic acid, and it tends to increase the CCN activity. Dicarboxylic acids with an oxo-group in the ?-position were found to decarboxylate in aqueous solution. IPCC: Climate Change (2007): The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK. Kanakidou, M., Seinfeld, J. H., Pandis, S. N., Barnes, I., Dentener, F. J., Facchini, M. C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C. J., Swietlicki, E., Putaud, J. P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G. K., Winterhalter, R., Myhre, C. E. L., Tsigaridis, K., Vignati, E., Stephanou, E. G., and Wilson, J (2005). Atmos. Chem. Phys., 5, 1053-1123, 2005. Hallquist, M., Wenger, JC, Baltensperger, U., Rudich, Y., Simpson, D., Claeys, M., Dommen, J.,Donahue, NM, George, C., Goldstein, AH, et al. (2009). Atmos Chem. Phys. Discuss, 9, 3555-3762. Bilde, M., Svenningsson, B., Mønster, J., and Rosenørn, T. (2003). Environ. Sci. Technol., 37, 1371-1378.

Frosch, Mia; Platt, Stephen; Zardini, Alessandro; Bilde, Merete

2010-05-01

338

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

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

339

Simulation technologies are applied extensively in casting industries to understand the heat transfer and fluid transport\\u000a phenomena and their relationships to the microstructure and the formation of defects. It is critical to have accurate thermo-physical\\u000a properties as input for reliable simulations of the complex solidification and solid phase transformation processes. The thermo-physical\\u000a properties can be calculated with the help of

J. Guo; M. T. Samonds

2007-01-01

340

In this work we present the generalization of some thermodynamic properties of the black body radiation (BBR) towards an $n-$dimensional Euclidean space. For this case the Planck function and the Stefan-Boltzmann law have already been given by Landsberg and de Vos and some adjustments by Menon and Agrawal. However, since then no much more has been done on this subject and we believe there are some relevant aspects yet to explore. In addition to the results previously found we calculate the thermodynamic potentials, the efficiency of the Carnot engine, the law for adiabatic processes and the heat capacity at constant volume. There is a region at which an interesting behavior of the thermodynamic potentials arise, maxima and minima appear for the $n-d$ BBR system at very high temperatures and low dimensionality, suggesting a possible application to cosmology. Finally we propose that an optimality criterion in a thermodynamic framework could have to do with the $3-d$ nature of the universe.

Gonzalez-Ayala, Julian; Cordero, Rubén; Angulo-Brown, F

2015-01-01

341

NASA Astrophysics Data System (ADS)

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.

Gering, Kevin Leslie

342

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.

Nagashima, H., E-mail: nagashima@nanoint.ifs.tohoku.ac.jp [School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsuda, S. [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan)] [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan); Tsuboi, N. [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan)] [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Koshi, M. [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan)] [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan); Hayashi, K. A. [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan)] [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan); Tokumasu, T. [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)] [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)

2014-04-07

343

NASA Astrophysics Data System (ADS)

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.

Bernazzani, Paul; Delmas, Genevieve

1998-03-01

344

NASA Astrophysics Data System (ADS)

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.

Dri, Fernando L.; Shang, ShunLi; Hector, Louis G., Jr.; Saxe, Paul; Liu, Zi-Kui; Moon, Robert J.; Zavattieri, Pablo D.

2014-12-01

345

NASA Astrophysics Data System (ADS)

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.

Liu, Yong; Hu, Wen-Cheng; Li, De-Jiang; Zeng, Xiao-Qin; Xu, Chun-Shui

2014-04-01

346

NASA Astrophysics Data System (ADS)

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 ? 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 ?D, thermal expansion coefficient ?, heat capacity Cp and Grüneisen parameter ? 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.

Wei, Ning; Zhang, Xiaoli; Zhang, Chuanguo; Hou, Songjun; Zeng, Z.

2015-10-01

347

A multiparameter corresponding-states correlation has been developed to accurately predict thermodynamic properties of nonpolar, polar, and associating compounds. The correlation parameters include critical temperature, critical density, structure factor, dipole moment, and three polar/associative parameters. The correlation was applied to predict vapor pressure, and density of a wide variety of polar and associating compounds including water, ammonia, alcohols, ethers, ketones, amines, mercaptans, cresols, xylenols, and indanols. The average absolute deviations for vapor pressure and density are 2.3% and 2.8%, respectively. 4 tables.

Watanasiri, S.; Kumar, K.H.; Starling, K.E.

1982-01-01

348

NASA Technical Reports Server (NTRS)

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.

Weber, L. A.

1977-01-01

349

NASA Technical Reports Server (NTRS)

A previous calculation of the thermodynamic properties of interstitial solid solutions based on the technique of Kirkwood expansions has been extended to include the effects of second nearest neighbor solute atom mutual interactions. The error inherent in the first order (or quasi-chemical) counting of the degeneracy of the solution crystal is avoided. It is shown that, at high temperatures, even strong second nearest neighbor solute mutual interactions have a negligible effect on the entropy of the solution and a small, temperature-dependent effect on the solute partial enthalpy.

Alex, K.; Mclellan, R. B.

1971-01-01

350

A Monte Carlo simulation is carried out to study thermodynamic properties of Cu-Au alloys using a face-centered-cubic (fcc) lattice-gas model. To obtain quantitatively accurate results, a Finnis-Sinclair-type potential, which has been widely used for molecular dynamics (MD) simulations, is employed. To overcome some shortcomings of lattice-gas models such as neglecting vibrational entropy, the potential is mapped onto the fcc lattice using the renormalization technique. The renormalized potential gives an improved Cu-Au phase diagram compared to the original MD potential applied directly on the lattice. PMID:15267866

Sahara, Ryoji; Ichikawa, Hiroshi; Mizuseki, Hiroshi; Ohno, Kaoru; Kubo, Hiroshi; Kawazoe, Yoshiyuki

2004-05-15

351

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

Scalettar, Richard T.; Pickett, Warren E.

2004-07-01

352

Based on a sticky-electrolyte model, the Ornstein{endash}Zernike integral equation is solved for nonsymmetric electrolytes with stickiness between ions at various distances equal to or less than the collision diameter. The hypernetted chain or Percus{endash}Yevick approximation is used for the closure inside the hard core, while the mean-spherical approximation for electrostatic interactions is used for the closure outside the hard core. Expressions for correlation functions and thermodynamic properties in term of the sticky parameters are derived. Numerical results are presented for various cases. {copyright} {ital 1997 American Institute of Physics.}

Hu, Y.; Jiang, J.; Liu, H. [Thermodynamics Research Laboratory, East China University of Science and Technology, Shanghai 200237 (China)] [Thermodynamics Research Laboratory, East China University of Science and Technology, Shanghai 200237 (China); Prausnitz, J.M. [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States); [Chemical Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)

1997-02-01

353

On thermodynamic and dielectric properties of PbHPO4 and PbHAsO4 crystals

NASA Astrophysics Data System (ADS)

Thermodynamic and dielectric properties of PbHPO4 and PbHAsO4 crystals are studied using the pseudo-spin model for proton subsystem within a two-particle cluster approximation neglecting the proton tunneling on hydrogen bonds. Temperature dependence of spontaneous polarization, heat capacity, static dielectric permittivity and dielectric dispersion in wide frequency range is calculated for both compounds in two structural phases. At a proper set of model parameters, a good quantitative description of the corresponding experimental data is obtained.

Zachek, I. R.; Shchur, Ya.; Levitskii, R. R.; Bilenka, O. B.

2014-11-01

354

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

Decremps, F; Gauthier, M; Ayrinhac, S; Bove, L; Belliard, L; Perrin, B; Morand, M; Le Marchand, G; Bergame, F; Philippe, J

2015-02-01

355

Thermodynamic properties of perovskite ARuO{sub 3} (A=Ca, Sr, and Ba) single crystals

Magnetic susceptibility, transport properties (including magnetoresistivity and the Hall effect), and specific heat of perovskite ARuO{sub 3} (A=Ca, Sr, and Ba) single crystals were measured. These compounds, particularly CaRuO{sub 3} (paramagnetic conductor) and SrRuO{sub 3} (ferromagnetic conductor) are believed to have a narrow {pi}{sup {asterisk}} band and their thermodynamic properties depend in an extremely sensitive way on the degree of the band filling and band width. This study reveals that the {pi}{sup {asterisk}} bandwidth of these compounds is largely determined by the ionic radii of the alkaline-earth A cations, i.e., the interaction between A s and O 2p orbitals and the electron correlation becomes progressively stronger in the series BaRuO{sub 3}, SrRuO{sub 3}, and CaRuO{sub 3}. {copyright} {ital 1997 American Institute of Physics.}

Shepard, M.; McCall, S.; Cao, G.; Crow, J.E. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306 (United States)] [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306 (United States)

1997-04-01

356

NASA Astrophysics Data System (ADS)

The thermodynamic and thermo-elastic properties of ductility intermetallic compounds DyCu with B2 structure are investigated with molecular dynamics. The calculated structural properties are in reasonable agreement with the available experimental and previously calculated data. At 300 K, the heat capacity of DyCu is 23.93 J mol-1 K-1. At the whole range 0-900 K, the elastic constants decrease with increasing temperature, and satisfy the stability criterions for DyCu compound. The value of B/G ratio for DyCu is greater than 1.75 implying the DyCu intermetallics are ductile, and increases with elevating temperature. Our results mean that the ductility of DyCu can be improved by increasing temperature.

Wu, Yurong; Xu, Longshan; Hu, Wangyu

2015-02-01

357

Standard thermodynamic properties of H3PO4(aq) over a wide range of temperatures and pressures.

The densities and heat capacities of solutions of phosphoric acid, 0.05 to 1 mol kg-1, were measured using flow vibrating tube densitometry and differential Picker-type calorimetry at temperatures up to 623 K and at pressures up to 28 MPa. The standard molar volumes and heat capacities of molecular H3PO4(aq) were obtained, via the apparent molar properties corrected for partial dissociation, by extrapolation to infinite dilution. The data on standard derivative properties were correlated simultaneously with the dissociation constants of phosphoric acid from the literature using the theoretically founded SOCW model. This made it possible to describe the standard thermodynamic properties, particularly the standard chemical potential, of both molecular and ionized phosphoric acid at temperatures up to at least 623 K and at pressures up to 200 MPa. This representation allows one to easily calculate the first-degree dissociation constant of H3PO4(aq). The performance of the SOCW model was compared with the other approaches for calculating the high-temperature dissociation constant of the phosphoric acid. Using the standard derivative properties, sensitively reflecting the interactions between the solute and the solvent, the high-temperature behavior of H3PO4(aq) is compared with that of other weak acids. PMID:17201442

Ballerat-Busserolles, Karine; Sedlbauer, Josef; Majer, Vladimir

2007-01-11

358

Eleven equations of state are employed to predict the vapor pressures, liquid and vapor densities, liquid and vapor heat capacities, and vaporization enthalpies and entropies of normal hydrogen along the coexistence curve. The volumetric and thermal properties of gaseous hydrogen together with the speeds of sound, Joule–Thomson coefficients and inversion curves for wide ranges of temperature and pressure are predicted

Khashayar Nasrifar

2010-01-01

359

Lead-free solder alloys: Thermodynamic properties of the (Au + Sb + Sn) and the (Au + Sb) system

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

Hindler, Michael; Guo, Zhongnan; Mikula, Adolf

2012-01-01

360

NASA Astrophysics Data System (ADS)

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 ?-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 s? 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 ?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.

Wei, Yong-Kai; Ge, Ni-Na; Ji, Guang-Fu; Chen, Xiang-Rong; Cai, Ling-Cang; Zhou, Su-Qin; Wei, Dong-Qing

2013-09-01

361

NASA Astrophysics Data System (ADS)

This paper overviews Helmholtz energy equations of state for pure HFC and natural refrigerants. The equations of state consist of the ideal-gas part and the residual part. The ideal-gas part can be calculated from the ideal-gas isobaric heat capacity according to the ideal-gas law, and the residual part is determined empirically by fitting to experimental thermodynamic property data. Polynomial and exponential terms are used to represent the residual part. Some equations have more complex terms for accurate descriptions of critical behavior. Mixture models for applications of the pure-fluid equations of state to refrigerant mixtures are summarized. Until now, two mixture models have been developed for HFC refrigerant mixtures. This paper also discusses calculation methods for the pvT relation, vapor-liquid equilibrium, and critical point using Helmholtz energy equations of state. Few literature discusses the methods in detail, although such information is very precious to make a computer program for calculating thermodynamic properties.

Akasaka, Ryo

362

NASA Astrophysics Data System (ADS)

Using first-principles calculations, the elastic constants, thermodynamic properties and structural phase transition of NbN under high pressure are investigated by means of the pseudopotential plane-waves method, in addition to the effect of metallic bonding on its hardness. Three candidate structures are chosen to investigate NbN, namely, rocksalt (NaCl), NiAs and WC types. On the basis of the third-order Birch-Murnaghan equation of states, the transition pressure Pt (Pt=200.64 GPa) between the WC phase and the NaCl phase of NbN is predicted for the first time. Elastic constants, formation enthalpies, shear modulus, Young's modulus, and Poisson's ratio of NbN are derived. The calculated results are found to be in good agreement with the available experimental data and theoretical values. According to the quasi-harmonic Debye model, the Debye temperature under high pressure is derived from the average sound velocity. Moreover, the effect of metallic bonding on the hardness of NbN is investigated and the hardness shows a gradual decrease rather than increase under compression. This is a quantitative investigation on the structural and thermodynamic properties of NbN, and it still awaits experimental confirmation.

Wang, Zhen-Hua; Kuang, Xiao-Yu; Huang, Xiao-Fen; Lu, Peng; Mao, Ai-Jie

2010-12-01

363

NASA Astrophysics Data System (ADS)

We review the treatment of electrostatic interactions in computer simulations under periodic boundary conditions, with emphasis on Ewald summation. Connections between Ewald summation and reaction field approaches will be made within a unifying picture of electrostatic potentials in Wigner lattices. The calculation of thermodynamic pressures in simulations of polar and ionic media will be discussed. Effects of finite system size on charging free energies will be analyzed. In addition, we will briefly review the problem of defining proper thermodynamic limits for single-ion properties. We find that cluster (or droplet) calculations of ionic solvation enthalpies or free energies (e.g., based on quantum mechanical methods) contain a contribution stemming from the charge ordering in the cluster-vacuum interface. This interfacial potential can lead to deviations of calculated single-ion enthalpies and free energies from the values in a properly defined thermodynamic limit at infinite ionic dilution. Finally, we will study the validity of linear response approximations for Coulomb systems. The origin of non-linearities in charging free energies will be traced to variations in the microscopic structure. We will conclude with a discussion of accurate integration methods for non-linear free energy expressions.

Hummer, Gerhard; Pratt, Lawrence R.; García, Angel E.; Neumann, Martin

1999-11-01

364

NASA Technical Reports Server (NTRS)

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.

Langhoff, Stephen; Bauschlicher, Charles; Jaffe, Richard

1992-01-01

365

Cements are being considered for sealing boreholes, shafts, and tunnels in nuclear waste repositories. The phases which will be stable in the long run are those which have the lowest free energies under repository conditions. In order to identify these phases, the relevant thermodynamic literature has been reviewed and evaluated, and some calculations of thermodynamic properties have been made for plausible repository conditions. Best values of heats, entropies, and free energies of formation are presented for calcium silicates, aluminates, and ferrites. Data for C-S-H gel are presented, considering the gel to have a composition of Ca/sub 3/Si/sub 2/O/sub 7/.3H/sub 2/O, and compared to the data for comparable crystalline phases. Equations and thermodynamic properties, including temperature dependence, are given for the hydration of cement components. Calculations for specific reactions show that hydration of tricalcium silicate should produce hillebrandite, 2CaO.SiO/sub 2/.1.17H/sub 2/O; the presence of excess silica should make higher-silica phases such as hillebrandite, tobermorite, or others more stable. The equilibrium between tobermorite, 5CaO.6SiO/sub 2/.5.5H/sub 2/O, and xonotlite, 6CaO.6SiO/sub 2/.H/sub 2/O, was calculated. Calculations of free energy of reaction of aqueous ions with tricalcium aluminate to form salts show that under normal atmospheric pressure and temperature Friedel's salt, the tricalcium aluminate monochloride hydrate, is stable both in typical brines and in a basalt groundwater. Similarly, in a brine from Los Medanos in the Delaware Basin of New Mexico, the tricalcium aluminate trisulfate-hydrate ettringite is stable with respect to tricalcium aluminate and to tricalcium aluminate monosulfate hydrate, but not with respect to hydrogarnet (tricalcium aluminate hexahydrate). 3 figures, 23 tables.

Sarkar, A.K.; Barnes, M.W.; Roy, D.M.

1982-09-01

366

NASA Astrophysics Data System (ADS)

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.

Chelli, S.; Meradji, H.; Amara Korba, S.; Ghemid, S.; El Haj Hassan, F.

2014-12-01

367

THE ELASTIC AND THERMODYNAMIC PROPERTIES OF Lu DOPED ScVO3

NASA Astrophysics Data System (ADS)

We have investigated the elastic, cohesive and thermal properties of (Lu, Sc) VO3 and Sc1-xLuxVO3(0.6 ? x ? 0.9) perovskites by means of a modified rigid ion model (MRIM). The variation of specific heat is determined following the temperature driven structural phase transitions. Also, the effect of lattice distortions on the elastic and thermal properties of the present pure and doped vanadates has been studied by an atomistic approach. The calculated bulk modulus (BT), reststrahlen frequency (?0), cohesive energy (?), Debye temperature (?D) and Gruneisen parameter (?) reproduce well with the corresponding experimental data. The specific heat results can further be improved by including the magnetic ordering contributions to the specific heat.

Parveen, Atahar; Gaur, N. K.

2012-12-01

368

Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

Murphy, R.W.

1994-12-01

369

Although most components contribute to structural and physical properties of food, the two main construction materials are\\u000a proteins and polysaccharides in their molecular and colloidal dispersions. Native biopolymers in biological system interact\\u000a specifically, whereas they are mainly denatured and interact non-specifically in formulated food. Most food components have\\u000a limited miscibility on a molecular level and form multicomponent, heterophase and non-equilibrium

V. Tolstoguzov

2000-01-01

370

We present exact analytical results for the thermodyanmic properties of a two-dimensional (2D), harmonically trapped charged quantum gas in a magnetic field. While our results are applicable to both Fermi and Bose gases, we focus our attention on trapped fermions owing to their relevant application in the density-functional theory of inhomogeneous Fermi systems. In particular, we test the Thomas-Fermi (or

Patrick Shea; Brandon P. van Zyl

2008-01-01

371

It is well known that precipitating convection within tropical cyclones result from a complex interactions among large-scale, storm-scale, cloud-scale, and micro-scale processes. For improved representation of these processes within tropical cyclone models, it is crucial to first understand how micro-scale and cloud- scale properties within tropical cyclones are related to large-scale processes, one of the key objectives of the Year

A. V. Mehta; E. A. Smith; G. J. Tripoli

2008-01-01

372

Amorphous Si - the role of MeV implantation in elucidating defect and thermodynamic properties

The role of MeV implantation in producing thick amorphous Si layers has been central in elucidating several of its properties. The recent use of MeV Si beams to produce very pure layers will be reviewed. The kinetics of solid-phase epitaxy have been measured for amorphous Si layers up to 5 mum thick and the activation energy found to be 2.70

J. M. Poate; S. Coffa; D. C. Jacobson; A. Polman; J. A. Roth; G. L. Olson; S. Roorda; W. Sinke; J. S. Custer; M. O. Thompson; F. Spaepen; E. Donovan

1991-01-01

373

An 18-coefficient modified Benedict–Webb–Rubin equation of state for HFC-125 (pentafluoroethane) has been developed. Correlations of vapor pressure and saturated liquid density are also presented. This equation of state has been developed using experimental data for the relationship of pressure-volume-temperature of fluid, saturation properties, isochoric heat capacity data, and speed of sound data. The equation of state is valid in the

Chun-Cheng Piao; Masahiro Noguchi

1998-01-01

374

An associated solution model is applied to describe the thermodynamic behavior of Fe-S liquid. This model assumes the existence\\u000a of ‘FeS’ species in addition to Fe and S in the liquid. With two solution parameters for each of the binaries Fe-‘FeS’ and\\u000a ‘FeS’-S, this model accounts for the compositional dependence of the thermodynamic properties of Fe-S liquid from pure Fe

R. C. Sharma; Y. A. Chang

1979-01-01

375

Structural, thermodynamic, mechanical, and magnetic properties of FeW system

The Fe-W system is systematically investigated through a combined use of first-principles calculation, cluster expansion, special quasirandom structures, and experiments. It is revealed that the ferromagnetic state of BCC Fe-W solid solution has lower heat of formation than its nonmagnetic state within the entire composition range, and intermetallic ?-Fe{sub 2}W and ?-Fe{sub 7}W{sub 6} phases are energetically favorable with negative heats of formation. Calculations also show that the Fe-W solid solution has much lower coefficient of thermal expansion than its mechanical mixture, and that the descending sequence of temperature-dependent elastic moduli of each Fe-W solid solution is E?>?G?>?B. Moreover, magnetic state should have an important effect on mechanical properties of Fe-W phases, and electronic structures can provide a deeper understanding of various properties of Fe-W. The derived results agree well with experimental observations, and can clarify two experimental controversies regarding structural stability and magnetic property of Fe-W phases in the literature.

Ren, Q. Q.; Fan, J. L.; Han, Y.; Gong, H. R., E-mail: gonghr@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2014-09-07

376

The Helmholtz function for pure isobutane from a recent correlation has been converted to a dimensionless form and a pressure-enthalpy chart based on this function has been generated by computer. A Helmholtz function for mixtures of isobutane and isopentane has been formed based upon the dimensionless isobutane Helmholtz function as the reference fluid by means of an extended corresponding-states principle. Scarce literature data for saturation properties of isopentane, and new data for its vapor pressure and for the critical line of the mixture were used. The accuracy of the surface was checked by comparing with literature enthalpy data and with new VLE data for the mixture. Tables of thermodynamic properties have been generated from this Helmholtz function for the 0.1 mole fraction isopentane-in-isobutane mixture in the single-phase region and on the dew- and bubble-point curves, together with properties of the coexisting phase. A pressure-enthalpy chart for this mixture has also been generated.

Gallagher, J.S.; Levelt Sengers, J.M.H.; Morrison, G.; Sengers, J.V.

1984-07-01

377

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}.

Dong, Bing; Zhou, Xiao-Lin, E-mail: Zhouxl-wuli@163.com, E-mail: lkworld@126.com; Chang, Jing [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101 (China); Liu, Ke, E-mail: Zhouxl-wuli@163.com, E-mail: lkworld@126.com [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101 (China); Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)

2014-08-07

378

Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000 K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), velocity of sound, the isotherm derivative (?P\\/?&rgr;)?, and the isochor derivative (?P\\/?T)&rgr;. The thermodynamic

Richard T. Jacobsen; Richard B. Stewart

1973-01-01

379

We investigate the thermodynamics of spherically symmetric black hole solutions in a four-dimensional Einstein--Yang-Mills-SU(2) theory with a negative cosmological constant. Special attention is paid to configurations with a unit magnetic charge. We find that a set of Reissner-Nordstr\\"om--Anti-de Sitter black holes can become unstable to forming non-Abelian hair. However, the hairy black holes are never thermodynamically favoured over the full set of abelian monopole solutions. The thermodynamics of the generic configurations possessing a noninteger magnetic charge is also discussed.

Kichakova, Olga; Radu, Eugen; Shnir, Yasha

2015-01-01

380

Calculation of the thermodynamic properties of fuel-vapor species from spectroscopic data

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.

Green, D.W.

1980-09-01

381

We study the applicability of the semiclassical Feynman and Hibbs (FH) (second-order or fourth-order) effective potentials to the description of the thermodynamic properties of quantum fluids at finite temperatures. First, we use path integral Monte Carlo (PIMC) simulations to estimate the thermodynamic/static properties of our model quantum fluid, i.e. low-density 4He at 10 K. With PIMC we obtain the experimental equation of state, the single-particle mean kinetic energy, the single-particle density matrix and the single-particle momentum distribution of this system at low densities. We show that our PIMC results are in full agreement with experimental data obtained with deep inelastic neutron scattering at high momentum transfers (D. Colognesi, C. Andreani, R. Senesi, Europhys. Lett., 2000, 50, 202). As expected, in this region of the 4He phase diagram, quantum effects modify the width of the single-particle momentum distribution but do not alter its Gaussian shape. Knowing the exact values of density, pressure and single-particle mean kinetic energy for our model quantum fluid, we investigate the limitations of the semiclassical FH effective potentials. We show that commonly used 'short-time' approximations to the high-temperature density matrix due to Feynman and Hibbs can only be applied in a very limited range of the 4He phase diagram. We found that FH effective potentials reproduce the experimental densities of 4He at 10 K for Lambda/a < 0.45 (Lambda = 2.73 A denotes the thermal de Broglie wavelength, a = rho(-1/3) is the mean nearest-neighbor distance in the fluid and rho denotes fluid density). Moreover, semiclassical FH effective potentials are able to correctly predict the single-particle mean kinetic energy of 4He at 10 K in a very limited range of fluid densities, i.e.Lambda/a < 0.17. We show that the ad hoc application of the semiclassical FH effective potentials for the calculation of the thermodynamic properties of dense liquid-like para-hydrogen (para-H2) adsorbed in nanoporous materials below 72 K is questionable. PMID:19812839

Kowalczyk, Piotr; Brualla, Lorenzo; Gauden, Piotr A; Terzyk, Artur P

2009-10-28

382

First principle study of elastic and thermodynamic properties of ZrZn2 and HfZn2 under high pressure

NASA Astrophysics Data System (ADS)

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.

Sun, Na; Zhang, Xinyu; Qin, Jiaqian; Ning, Jinliang; Zhang, Suhong; Liang, Shunxing; Ma, Mingzhen; Liu, Riping

2014-02-01

383

A set of partially covalent interatomic potentials has been developed with the aim of reproducing the experimentally known\\u000a crystal structures and predicting the unknown crystal structures and the thermodynamic and elastic properties of bromellite\\u000a BeO, chrysoberyl BeAl2O4, and its isostructural analogs BeCr2O4 and BeFe2O4. The calculated structural, elastic, and thermodynamic properties of these minerals are in good agreement with the

N. N. Eremin; N. A. Gromalova; V. S. Urusov

2009-01-01

384

Structural and thermodynamic properties of MgB 2 from first-principles calculations

NASA Astrophysics Data System (ADS)

A first-principles plane wave method with the relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter (HGH) scheme in the frame of local density approximation is performed to calculate the lattice parameters and the equation of states (EOS) of superconducting MgB 2. Our calculations show that the ratio c/ a of about 1.134 is the most stable structure for MgB 2, as is consistent with experiment and other theoretical results. Also, the isothermal and isobaric properties are discussed from energy-volume curves using a quasi-harmonic Debey model.

Guo, Hua-Zhong; Chen, Xiang-Rong; Cai, Ling-Cang; Zhu, Jun; Gao, Jie

2005-06-01

385

NASA Astrophysics Data System (ADS)

This report presents the assessed thermochemical measurements on rubidium compounds upon which the property values, ?f H0, ?f G0, S0, C0p, and H0(T)-H0(0) at 298.15 K and ?f H0(0 K) recommended in the ``NBS Tables of Chemical Thermodynamic Properties'' are based. Included in this set of thermochemical measurements, or thermochemical reaction catalog, is a comparison of the observed values for the processes in question with those predicted (calculated) from the recommended property values in the forementioned tables. The evaluator's initially assigned uncertainties on the experimental measurements and final estimated reliabilities on the recommended process values are given. This paper illustrates the evaluation procedure used in preparing the full set of recommended data in the ``NBS Tables of Chemical Thermodynamic Properties''.

Parker, V. B.; Evans, W. H.; Nuttall, R. L.

1987-01-01

386

Dynamic and thermodynamic properties of the generalized diamond chain model for azurite.

The natural mineral azurite Cu(3)(CO(3))(2)(OH)(2) is an interesting spin-1/2 quantum antiferromagnet. Recently, a generalized diamond chain model has been established as a good description of the magnetic properties of azurite with parameters placing it in a highly frustrated parameter regime. Here we explore further properties of this model for azurite. First, we determine the inelastic neutron scattering spectrum in the absence of a magnetic field and find good agreement with experiments, thus lending further support to the model. Furthermore, we present numerical data for the magnetocaloric effect and predict that strong cooling should be observed during adiabatic (de)magnetization of azurite in magnetic fields slightly above 30 T. Finally, the presence of a dominant dimer interaction in azurite suggests the use of effective Hamiltonians for an effective low-energy description and we propose that such an approach may be useful for fully accounting for the three-dimensional coupling geometry. PMID:21471625

Honecker, Andreas; Hu, Shijie; Peters, Robert; Richter, Johannes

2011-04-27

387

It is generally accepted that current technologies for capturing CO{sub 2} are still too energy intensive. Hence, there is a critical need for development of new materials that can capture CO{sub 2} reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO{sub 2} capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO{sub 2} sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO{sub 2} adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO{sub 2} capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. These CO{sub 2} sorbent candidates were further considered for experimental validations. In this presentation, we first introduce our screening methodology with validating by solid dataset of alkali and alkaline metal oxides, hydroxides and bicarbonates which thermodynamic properties are available. Then, by studying a series of lithium silicates, we found that by increasing the Li{sub 2}O/SiO{sub 2} ratio in the lithium silicates their corresponding turnover temperatures for CO{sub 2} capture reactions can be increased. Compared to anhydrous K{sub 2}CO{sub 3}, the dehydrated K{sub 2}CO{sub 3}?1.5H{sub 2}O can only be applied for post-combustion CO{sub 2} capture technology at temperatures lower than its phase transition (to anhydrous phase) temperature, which depends on the CO{sub 2} pressure and the steam pressure with the best range being PH{sub 2}O?1.0 bar. Above the phase-transition temperature, the sorbent will be regenerated into anhydrous K{sub 2}CO{sub 3}. Our theoretical investigations on Na-promoted MgO sorbents revealed that the sorption process takes place through formation of the Na{sub 2}Mg(CO{sub 3}){sub 2} double carbonate with better reaction kinetics over porous MgO, that of pure MgO sorbent. The experimental sorption tests also indicated that the Na-promoted MgO sorbent has high reactivity and capacity towards CO{sub 2} sorption and can be easily regenerated either through pressure or temperature swing processes.

Duan, Yuhua; Luebke, David; Pennline, Henry; Li, Liyu; King, David; Zhang; Keling; Zhao; Lifeng; Xiao, Yunhan

2012-01-01

388

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

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

389

This landmark book presents a formulation for the properties of steam over a previously unavailable range of temperatures and pressures. The thermodynamically consistent data encompasses numerous thermophysical properties, including specific volume, density, internal energy, enthalpy, and entropy. Steam tables extends the useful temperature range from the melting line to over 2500 K, and permits you to apply the formulation from zero pressure of the ideal gas to more than 20 kilobars - 20 times the range of previous formulations.

Haar, L.; Gallagher, J.S.; Kell, G.S.

1984-01-01

390

NASA Technical Reports Server (NTRS)

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.

Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.

1989-01-01

391

NASA Technical Reports Server (NTRS)

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.

Hendricks, R. C.

1994-01-01

392

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

Vítek, Aleš; Arismendi-Arrieta, D J; Rodríguez-Cantano, R; Prosmiti, R; Villarreal, P; Kalus, R; Delgado-Barrio, G

2015-04-14

393

Properties of hadronic systems according to the non-extensive self-consistent thermodynamics

NASA Astrophysics Data System (ADS)

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 To = 192 MeV results in a divergent behaviour in respect with the lattice calculation.

Deppman, A.

2014-11-01

394

Thermodynamic bounds and general properties of optimal efficiency and power in linear responses

NASA Astrophysics Data System (ADS)

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.

Jiang, Jian-Hua

2014-10-01

395

Thermodynamic and kinetic properties of the Li-graphite system from first-principles calculations

We present an ab initio study of the thermodynamics and kinetics of LixC6 , relevant for anode Li intercalation in rechargeable Li batteries. In graphite, the interlayer interactions are dominated by Van der Waals forces, which are not captured with standard density-functional theory (DFT). By calculating the voltage profile for Li intercalation into graphite and comparing it to experimental results,

Kristin Persson; Yoyo Hinuma; Ying Shirley Meng; Anton van der Ven; Gerbrand Ceder

2010-01-01

396

Thermodynamic bounds and general properties of optimal efficiency and power in linear responses.

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

Jiang, Jian-Hua

2014-10-01

397

The solid phase FT-IR and FT-Raman spectra of 1-methyl-2-phenyl benzimidazole (MPBZ) have been recorded in the condensed state. In this work, experimental and theoretical study on the molecular structure, quantum chemical calculations of energies and vibrational wavenumbers of MPBZ is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311+G(d,p) and 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 4000-400 cm(-1) and with Fourier transform Raman spectrum in the region of 4000-100 cm(-1). Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential (MEP) surfaces, polarizability, Mulliken charges and thermodynamic properties of the title compound. PMID:24785089

Karnan, M; Balachandran, V; Murugan, M; Murali, M K

2014-09-15

398

NASA Technical Reports Server (NTRS)

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.

Lovell, Conrad S.; Wise, Kristopher E.; Kim, Jae-Woo; Lillehei, Peter T.; Harrison, Joycelyn S.; Park, Cheol

2009-01-01

399

Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re ?-phase.

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(m)). Finally, we show that the vibrational contribution has significant consequences on the disordering of the ?-phase at high temperature. PMID:24735300

Palumbo, Mauro; Fries, Suzana G; Pasturel, Alain; Alfè, Dario

2014-04-14

400

Correlation corrections to the thermodynamic properties of spin-asymmetric QGP matter

NASA Astrophysics Data System (ADS)

We calculate the free energy, entropy and pressure of the Quark Gluon Plasma (QGP) at finite temperature and density with a given fraction of spin-up and spin-down quarks using a MIT bag model with corrections up to . The expressions for the specific heat and the spin susceptibility are derived in terms of Fermi momentum and temperature. The effects of the interaction between the quarks on the properties of the QGP phase are also investigated. Within our phenomenological model, we estimate the transition temperature T c by constructing the phase boundary between the hadronic phase and the QGP phase. Finally, we compute the equation of state of the QGP and its dependence on the temperature and the density.

Pal, Kausik

2015-02-01

401

Elasticity and thermodynamic properties of RuB 2 under pressure

NASA Astrophysics Data System (ADS)

First-principles calculations of the crystal structure and the elastic properties of RuB 2 have been carried out with the plane-wave pseudopotential density functional theory method. The calculated values are in very good agreement with experimental data as well as with some of the existing model calculations. The elastic constants c ij, the aggregate elastic moduli ( B, G, E), Poisson's ratio, and the elastic anisotropy with pressure have been investigated. Through the quasi-harmonic Debye model considering the phonon effects, the isothermal bulk modulus, the thermal expansions, Grüneisen parameters, and Debye temperatures depending on the temperature and pressure are obtained in the whole pressure range from 0 to 60 GPa and temperature range from 0 to 1100 K as well as compared to available data.

Peng, Feng; Peng, Weimin; Fu, Hongzhi; Yang, Xiangdong

2009-11-01

402

Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re ?-phase

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.

Palumbo, Mauro, E-mail: mauro.palumbo@rub.de; Fries, Suzana G. [ICAMS, Ruhr University Bochum, Universität Str. 150, D-44801 Bochum (Germany)] [ICAMS, Ruhr University Bochum, Universität Str. 150, D-44801 Bochum (Germany); Pasturel, Alain [SIMAP, UMR CNRS-INPG-UJF 5266, BP 75, F-38402 Saint Martin d’Hères (France)] [SIMAP, UMR CNRS-INPG-UJF 5266, BP 75, F-38402 Saint Martin d’Hères (France); Alfè, Dario [Department of Earth Sciences, Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre-UCL, University College London, Gower Street, London WC1E 6BT (United Kingdom)] [Department of Earth Sciences, Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre-UCL, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2014-04-14

403

NASA Astrophysics Data System (ADS)

An 18-coefficient modified Benedict-Webb-Rubin equation of state for HFC-125 (pentafluoroethane) has been developed. Correlations of vapor pressure and saturated liquid density are also presented. This equation of state has been developed using experimental data for the relationship of pressure-volume-temperature of fluid, saturation properties, isochoric heat capacity data, and speed of sound data. The equation of state is valid in the superheated gaseous phase and the compressed liquid phase at pressures up to 68 MPa, densities to 1700 kg/m3, and temperatures from the triple point (172.52 K) to 475 K. This equation of state has been selected as an international standard formulation for HFC-125 based on an evaluation of the available equations of state by Annex 18 of the International Energy Agency.

Piao, Chun-Cheng; Noguchi, Masahiro

1998-07-01

404

FP-LAPW investigation of the structural, electronic and thermodynamic properties of Al3Ta compound

NASA Astrophysics Data System (ADS)

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.

Boulechfar, R.; Meradji, H.; Chouahda, Z.; Ghemid, S.; Drablia, S.; Khenata, R.

2015-09-01

405

Conformational and thermodynamic properties of peptide binding to the human S100P protein

S100P is a member of the S100 subfamily of calcium-binding proteins that are believed to be associated with various diseases, and in particular deregulation of S100P expression has been documented for prostate and breast cancer. Previously, we characterized the effects of metal binding on the conformational properties of S100P and proposed that S100P could function as a Ca2+ conformational switch. In this study we used fluorescence and CD spectroscopies and isothermal titration calorimetry to characterize the target-recognition properties of S100P using a model peptide, melittin. Based on these experimental data we show that S100P and melittin can interact in a Ca2+-dependent and -independent manner. Ca2+-independent binding occurs with low affinity (Kd ? 0.2 mM), has a stoichiometry of four melittin molecules per S100P dimer and is presumably driven by favorable electrostatic interactions between the acidic protein and the basic peptide. In contrast, Ca2+-dependent binding of melittin to S100P occurs with high affinity (Kd ? 5 ?M) has a stoichiometry of two molecules of melittin per S100P dimer, appears to have positive cooperativity, and is driven by hydrophobic interactions. Furthermore, Ca2+-dependent S100P-melittin complex formation is accompanied by significant conformational changes: Melittin, otherwise unstructured in solution, adopts a helical conformation upon interaction with Ca2+-S100P. These results support a model for the Ca2+-dependent conformational switch in S100P for functional target recognition. PMID:12021435

Gribenko, Alexey V.; Guzmán-Casado, Mercedes; Lopez, Maria M.; Makhatadze, George I.

2002-01-01

406

NASA Astrophysics Data System (ADS)

The structural, thermodynamic and dynamic properties of surfaces and thin films of polymethylene and polytetrafluoroethylene melts are studied by molecular dynamics simulations using explicit and united atom models. N-tridecane (C_13H_28) and n-C_44H_90 melt films with a thickness of about 30 A have been investigated by NVT-MD simulation method at the temperatures from 300 K to 450 K and at zero pressure. We obtain reliable results for the surface properties such as surface tension, density profile, order parameter, and diffusivity. Simulations give good agreement for the density and surface tension when compared with experimental data. It is observed that for n-tridecane the density of methyl chain-end group is enhanced in the free surface, while it is depleted in the region below the surface. For longer chains of C_44H_90 the segregation of chain ends to the surface is clearly seen as a peak. A slight preference for chain segments to orient along the direction parallel to the surface is observed, whereas the orientations of endmost bond vectors are nearly random. Moreover, the molecular diffusivity in the surface region is significantly greater than in the bulk region, especially along the film plane direction. These results for polymethylene melts are compared with those for C_12F_26 chains which exhibit significantly reduced chain flexibility.

Chang, J.; Yoon, D. Y.; Yang, L.; Han, J.; Jaffe, R. L.

2000-03-01

407

NASA Technical Reports Server (NTRS)

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.

Venkateswaran, S.; Hunt, L. Roane; Prabhu, Ramadas K.

1992-01-01

408

Considerable difficulties persist in modelling the thermodynamics of multicomponent aqueous electrolyte solutions, especially at high concentrations. The widely adopted Pitzer formalism suffers from severe disadvantages, particularly with the combinatorial increase in mixing parameters required in multicomponent systems. As an alternative, the simple mixing rules of Young, of Harned and of Zdanovskii have been employed to predict the properties of mixtures using only the properties of the binary constituents with few or no additional parameters. Among these, Zdanovskii's rule is particularly promising because it constitutes a fundamental criterion for ideal mixing, i.e. when solutions having the same solvent activity are mixed in any proportion, the solvent activity remains unchanged. Many mixtures of strong electrolyte solutions are known from experiment to obey Zdanovskii's rule. This is important because application to aqueous electrolyte systems of practical interest has been hindered due to the process-intensive determination of water activities using the Gibbs-Duhem relation. This paper describes an alternative method which efficiently calculates the water activity of a multicomponent solution obeying Zdanovskii's rule. Some specific examples of the method are presented and various applications considered. In some systems, where deviations from Zdanovskii's rule occur, a single empirical parameter can be obtained and can be easily incorporated into the calculations. PMID:20188901

Rowland, Darren; May, Peter M

2010-04-15

409

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, R(g)(2) and ?, respectively. In addition, a specific orientational order S(x) 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 R(g)(2), while their shape and order barely vary with an infinite value of ? and S(x). 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. PMID:21280752

Tseng, Huan-Chang; Chang, Rong-Yeu; Wu, Jiann-Shing

2011-01-28

410

A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple

R. C. Hendricks; A. K. Baron; I. C. Peller

1975-01-01

411

The rare earth element complexes have never been analyzed in the gaseous state due to experimental concerns. The thermodynamic properties of rare earth element complexes are important for various applications, from high-intensity discharge lamps to recovery of rare earth metals. 46 refs., 4 figs., 1 tab.

Zhi-Chang Wang; Lin-Shan Wang [Northeastern Univ., Liaoning (China)

1997-04-09

412

Using the Voter and Chen (VC) version of the embedded atom model, we performed molecular dynamics simulations to compute the static structure factors and some thermodynamic properties of Ni, Pd, Pt, Cu, Ag and Au in the liquid phase. The computations were carried out using both the full embedded atom model and a pair-potential approximation; both afforded quite similar results

M. M. G. Alemany; M. Calleja; C. Rey; L. J. Gallego; J. Casas; L. E. González

1999-01-01

413

Standard partial molal thermodynamic properties including association constants for 246 inorganic aqueous rare earth element (REE) complexes with chloride, fluoride, hydroxide, carbonate, sulfate, bicarbonate, nitrate, and orthophosphate can be calculated at pressures from 1 to 5000 bars and temperatures from 0 to 1000°C, using experimental data from the literature and correlation algorithms. Predicted association constants for REE complexes are used

Johnson R. Haas; Everett L. Shock; David C. Sassani

1995-01-01

414

The tables in our first two papers on polycyclic aromatic hydrocarbons [J. Phys. Chem. Ref. Data 17, 241 (1988) and J. Phys. Chem. Ref. Data (18, 77 (1989)], have been extended by calculating thermodynamic properties for the first two isomer groups in the naphthocoronene series, the first two isomer groups in the ovalene series, and first members of some higher

Robert A. Alberty; Michael B. Chung; Andrea K. Reif

1990-01-01

415

Thermodynamic properties of boron suboxide in the temperature range 11.44-781.8 K

NASA Astrophysics Data System (ADS)

Heat capacity of boron suboxide (B6O) have been determined in the vacuum adiabatic calorimeter with pulse heat supply in the temperature range 11.44-311.84 K. The values of its low-temperature heat capacity (Cp), entropy (S), enthalpy (Ht-Ho) and reduced thermodynamic potential (-(G-Ho)/T) were tabulated. The values of the enthalpy (Ht-H298.15), average (Cp) and true heat capacities of B6O have been determined by mixing isothermal massive calorimetry. Experimental results were treated by least-squares method. Equations of temperature dependence of thermodynamic characteristics of boron suboxide were obtained. The curve of temperature dependence of its Debye characteristic temperature was plotted.

Tsagareishvili, G. V.; Tsagareishvili, D. Sh.; Tushishvili, M. Ch.; Omiadze, I. S.; Naumov, V. N.; Tagaev, A. B.

1991-07-01

416

Thermodynamic properties and thermal stability of the synthetic zinc formate dihydrate

Zinc formate dihydrate has been synthesized and characterized by powder X-ray diffraction, elemental analysis, FTIR spectra\\u000a and thermal analysis. The molar heat capacity of the coordination compound was measured by a temperature modulated differential\\u000a scanning calorimetry (TMDSC) over the temperature range from 200 to 330 K for the first time. The thermodynamic parameters\\u000a such as entropy and enthalpy vs. 298.15

J. Zhang; Y. Y. Liu; J. L. Zeng; F. Xu; L. X. Sun; W. S. You; Y. Sawada

2008-01-01

417

Thermodynamic Properties of Dioxygen Difluoride (O2F2) and Dioxygen Fluoride (O2F)

Recent spectroscopic and chemical kinetic studies have provided sufficient data for construction of reliable thermodynamic tables for both dioxygen difluoride (O2F2; Chemical Abstracts Registry Number, 7783-44-0) and dioxygen fluoride (O2F; Chemical Abstracts Registry Number, 15499-23-7). This paper contains those tables for these species in both SI units (0.1 MPa standard state) and cal K mol units (1.0 atm standard state).

John L. Lyman

1989-01-01

418

NASA Astrophysics Data System (ADS)

Motivated by experiments showing decreasing tensile modulus of nylons with increasing plasticizer content, a model involving the disruption of nylon hydrogen bonding by addition of plasticizer is proposed. This leads to proposed further experiments and suggests a complementary phenomenological analysis that involves the bulk modulus. The surface energy as a function of plasticizer concentration is then incorporated into the phenomenology. The importance of varying the temperature in the proposed thermodynamic measurements is stressed.

Zhang, M. L.; March, N. H.; Peeters, A.; Van Alsenoy, C.; Van Doren, V. E.

2001-04-01

419

Thermodynamic properties of boron suboxide in the temperature range 11.44–781.8 K

Heat capacity of boron suboxide (B6O) have been determined in the vacuum adiabatic calorimeter with pulse heat supply in the temperature range 11.44–311.84 K. The values of its low-temperature heat capacity (Cp), entropy (S), enthalpy (Ht?Ho) and reduced thermodynamic potential (?(G?Ho)\\/T) were tabulated.The values of the enthalpy (Ht?H298.15), average (Cp) and true heat capacities of B6O have been determined by

G. V. Tsagareishvili; D. Sh. Tsagareishvili; M. Ch. Tushishvili; I. S. Omiadze; V. N. Naumov; A. B. Tagaev

1991-01-01

420

Thermodynamic properties of boron suboxide in the temperature range 11.44-781.8 K

Heat capacity of boron suboxide (B6O) have been determined in the vacuum adiabatic calorimeter with pulse heat supply in the temperature range 11.44-311.84 K. The values of its low-temperature heat capacity (Cp), entropy (S), enthalpy (Ht-Ho) and reduced thermodynamic potential (-(G-Ho)\\/T) were tabulated. The values of the enthalpy (Ht-H298.15), average (Cp) and true heat capacities of B6O have been determined

G. V. Tsagareishvili; D. Sh. Tsagareishvili; M. Ch. Tushishvili; I. S. Omiadze; V. N. Naumov; A. B. Tagaev

1991-01-01

421

Because hydrate formation in pipelines, processing operations, and reservoirs is generally undesirable, studies of gas-hydrate thermodynamics, particularly examinations of conditions where a second hydrate phase or a hydrocarbon-rich phase exists in addition to the water, hydrate, and gas phases, are important to the natural gas industry. In this study, analysts used experimental methane-krypton and methane-argon hydrate data to generate chemical-potential,

G. D. Holder; G. Corbin; K. D. Papadopoulos

1980-01-01

422

An analytical investigation for thermodynamic properties of the Fe-Cr-Ni-Mg-O system

NASA Astrophysics Data System (ADS)

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.

Arslan, H.; Dogan, A.

2015-02-01

423

F-actin gels of increasing concentrations (25–300?M) display in vitro a progressive onset of birefringence due to orientational ordering of actin filaments. At F-actin concentrations <100?M, this birefringence can be erased and restored at will by sonication and gentle flow, respectively. Hence, the orientational ordering does not result from a thermodynamic transition to a nematic phase but instead is due to

Emmanuèle Helfer; Pierre Panine; Marie-France Carlier; Patrick Davidsonz

2005-01-01

424

Landscape Excitation Profiles and Excess Thermodynamic Properties of Disaccharide Aqueous Solutions

We will consider the use of the bond model in characterizing, by the direct calculation route, the full excitation profile. The present work sets the temperature behaviour of the excessive value of some thermodynamic quantities, such as configurational entropy and heat capacity of two homologous disaccharide aqueous solutions. The findings represent important data for understanding the better lyoprotectant effectiveness of trehalose in comparison with sucrose. PMID:19669457

Mondelli, C.; Romeo, G.

2006-01-01

425

The thermodynamic activity of water in a binary KOH HâO system has been measured using an electrochemical cell, Cell A (Hâ(Pt)\\/KOH in HâO\\/Hg, HgO(Pt)), in the concentration range between 1 and 8 molal and the temperature range of 0 to 80Â°C. From the equilibrium voltage of cell (A), the activity of water can be directly calculated without making assumptions about

W. B. Johnson; G. R. St. Pierre; D. D. Macdonald; M. K. Malhotra

1985-01-01

426

The prevalence of Mg(2+) ions in biology and their essential role in nucleic acid structure and function has motivated the development of various Mg(2+) ion models for use in molecular simulations. Currently, the most widely used models in biomolecular simulations represent a nonbonded metal ion as an ion-centered point charge surrounded by a nonelectrostatic pairwise potential that takes into account dispersion interactions and exchange effects that give rise to the ion's excluded volume. One strategy toward developing improved models for biomolecular simulations is to first identify a Mg(2+) model that is consistent with the simulation force fields that closely reproduces a range of properties in aqueous solution, and then, in a second step, balance the ion-water and ion-solute interactions by tuning parameters in a pairwise fashion where necessary. The present work addresses the first step in which we compare 17 different nonbonded single-site Mg(2+) ion models with respect to their ability to simultaneously reproduce structural, thermodynamic, kinetic and mass transport properties in aqueous solution. None of the models based on a 12-6 nonelectrostatic nonbonded potential was able to reproduce the experimental radial distribution function, solvation free energy, exchange barrier and diffusion constant. The models based on a 12-6-4 potential offered improvement, and one model in particular, in conjunction with the SPC/E water model, performed exceptionally well for all properties. The results reported here establish useful benchmark calculations for Mg(2+) ion models that provide insight into the origin of the behavior in aqueous solution, and may aid in the development of next-generation models that target specific binding sites in biomolecules. © 2015 Wiley Periodicals, Inc. PMID:25736394

Panteva, Maria T; Giamba?u, George M; York, Darrin M

2015-05-15

427

Based on the quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for calculation of thermodynamic properties and -- closely related to the latter -- a Wigner dynamics method for calculation of transport properties of the QGP are formulated. The QGP partition function is presented in the form of a color path integral with a new relativistic measure instead of the Gaussian one traditionally used in the Feynman-Wiener path integral. It is shown that the PIMC method is able to reproduce the lattice QCD equation of state at zero baryon chemical potential at realistic model parameters (i.e. quasiparticle masses and coupling constant) and also yields valuable insight into the internal structure of the QGP. Our results indicate that the QGP reveals quantum liquid-like (rather than gas-like) properties up to the highest considered temperature of 525 MeV. The pair distribution functions clearly reflect the existence of gluon-gluon bound states, i.e. glueballs, at temperatures just above the phase transition, while meson-like $q\\bar{q}$ bound states are not found. The calculated self-diffusion coefficient agrees well with some estimates of the heavy-quark diffusion constant available from recent lattice data and also with an analysis of heavy-quark quenching in experiments on ultrarelativistic heavy ion collisions, however, appreciably exceeds other estimates. The lattice and heavy-quark-quenching results on the heavy-quark diffusion are still rather diverse. The obtained results for the shear viscosity are in the range of those deduced from an analysis of the experimental elliptic flow in ultrarelativistic heavy ions collisions, i.e. in terms the viscosity-to-entropy ratio, $1/4\\pi < \\eta/S < 2.5/4\\pi$, in the temperature range from 170 to 440 MeV.

V. S. Filinov; Yu. B. Ivanov; M. Bonitz; V. E. Fortov; P. R. Levashov

2013-01-29

428

Thermodynamic Functions and Properties of MgO at High Compression and High Temperature

The complete thermodynamic functions for MgO are presented for the temperature range 300--2000 K and the pressure range 0--150 GPa, both as tables and as graphs. Careful attention is given to the temperature and pressure dependence of the coefficient of thermal expansion {alpha} and the isothermal bulk modulus {ital K}{sub {ital T}}, which are the major corrections to the thermodynamic functions in extreme conditions. Our equations efficiently use the fact that the product {alpha}{ital K}{sub {ital T}} varies only slightly with either temperature or with volume, although scrupulous care is taken to account for the actual numbers. The corrections are now possible due to recent measurements of the bulk modulus up to 1800 K. The Birch--Murnaghan equation of state is used to account for certain terms in the expressions for internal energy and enthalpy. The parameters used in the Birch--Murnaghan equation of state are given as functions of temperature. The parameters which presently limit the calculations of thermodynamic functions to even higher temperatures and pressures and limit the applications of this method to other minerals are: (1) the uncertainty of the thermal expansivity at temperatures above 1500 K, and (2) the uncertainty of the temperature dependence of ({partial derivative}{ital K}{sub {ital T}}/{partial derivative}{ital T}){sub {ital P}} at temperatures above 800 K.

Anderson, O.L.; Zou, K. (Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences, University of California, Los Angeles, California 90024 (US))

1990-01-01

429

Measuring Thermodynamic Properties of Metals and Alloys With Knudsen Effusion Mass Spectrometry

NASA Technical Reports Server (NTRS)

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.

Copland, Evan H.; Jacobson, Nathan S.

2010-01-01

430

Quasicontinuous P?T data of CO(2), ethane, propane, and the [CO(2) + ethane] mixture have been determined along subcritical, critical, and supercritical regions. These data have been used to develop the optimal experimental method and to determine the precision of the results obtained when using an Anton Paar DMA HPM vibrating-tube densimeter. A comparison with data from reference EoS and other authors confirm the quality of our experimental setup, its calibration, and testing. For pure compounds, the value of the mean relative deviation is MRD(?) = 0.05% for the liquid phase and for the extended critical and supercritical region. For binary mixtures the mean relative deviation is MRD(?) = 0.70% in the range up to 20 MPa and MRD(?) = 0.20% in the range up to 70 MPa. The number of experimental points measured and their just quality have enable us to determine some derivated properties with satisfactory precision; isothermal compressibilities, ?(T), have been calculated for CO(2) and ethane (MRD(?(T)) = 1.5%), isobaric expasion coefficients, ?(P), and internal pressures, ?(i), for CO(2) (MRD(?(P)) = 5% and MRD(?(i)) = 7%) and ethane (MRD(?(P)) = 7.5% and MRD(?(i)) = 8%). An in-depth discussion is presented on the behavior of the properties obtained along subcritical, critical, and supercritical regions. In addition, PuT values have been determined for water and compressed ethane from 273.19 to 463.26 K up to pressures of 190.0 MPa, using a device based on a 5 MHz pulsed ultrasonic system (MRD(u) = 0.1%). With these data we have calibrated the apparatus and have verified the adequacy of the operation with normal liquids as well as with some compressed gases. From density and speed of sound data of ethane, isentropic compressibilities, ?(s), have been obtained, and from these and our values for ?(T) and ?(P), isobaric heat capacities, C(p), have been calculated with MRD(C(p)) = 3%, wich is within that of the EoS. PMID:21639086

Velasco, Inmaculada; Rivas, Clara; Martínez-López, José F; Blanco, Sofía T; Otín, Santos; Artal, Manuela

2011-06-30

431

It has been noted that for present and anticipated modes of operation the Hanford N-Reactor primary coolant may bear thermohydraulically significant amounts of dissolved hydrogen, nitrogen, and ammonia. To investigate this possibility, calculations were made of the specific volume and specific enthalpy of aqueous primary coolant from available data and reasonable approximations over the necessary ranges of temperature and pressure. A computer program which produces a steam table of these properties, as well as compositions, has been coded to provide tables of the bubble line, dew line, superheated-vapor - compressed liquid, and two phase-to-20% void regimes from 32/sup 0/F to 630/sup 0/F and from 14 psia to 2100 psia. This program will provide the tables for any inputted coolant composition of water with 0.01 to 200 ppM NH/sub 3/, 0.01 to 50 ppM H/sub 2/, and 0.01 to 150 ppM N/sub 2/, or so long as the mole fraction of water remains above 0.999. Alteration for other water chemistries is not difficult.

Bechtold, D.B.

1982-06-23

432

Pairing Mechanism for the High-TC Superconductivity: Symmetries and Thermodynamic Properties

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

Szcz??niak, Rados?aw

2012-01-01

433

NASA Technical Reports Server (NTRS)

Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity, isobaric heat capacity velocity of sound, the isotherm derivative, and the isochor derivative. The thermodynamic property tables are based on an equation of state, P=P (p,T), which accurately represents liquid and gaseous nitrogen for the range of pressures and temperatures covered by the tables. Comparisons of property values calculated from the equation of state with measured values for P-p-T, heat capacity, enthalpy, latent heat, and velocity of sound are included to illustrate the agreement between the experimental data and the tables of properties presented here. The coefficients of the equation of state were determined by a weighted least squares fit to selected P-p-T data and, simultaneously, to isochoric heat capacity data determined by corresponding states analysis from oxygen data, and to data which define the phase equilibrium criteria for the saturated liquid and the saturated vapor. The vapor pressure equation, melting curve equation, and an equation to represent the ideal gas heat capacity are also presented. Estimates of the accuracy of the equation of state, the vapor pressure equation, and the ideal gas heat capacity equation are given. The equation of state, derivatives of the equation, and the integral functions for calculating derived thermodynamic properties are included.

Jacobsen, Richard T.; Stewart, Richard B.

1973-01-01

434

NASA Astrophysics Data System (ADS)

Calculation of the thermodynamic properties of organic solids, liquids, and gases at high temperatures and pressures is a requisite for characterizing hydrothermal metastable equilibrium states involving these species and quantifying the chemical affinities of irreversible reactions of organic molecules in natural gas, crude oil, kerogen, and coal with minerals and organic, inorganic, and biomolecular aqueous species in interstitial waters in sedimentary basins. To facilitate calculations of this kind, coefficients for the Parameters From Group Contributions (PFGC) equation of state have been compiled for a variety of groups in organic liquids and gases. In addition, molecular weights, critical temperatures and pressures, densities at 25°C and 1 bar, transition, melting, and boiling temperatures ( Tt,Pr, Tm,Pr, and Tv,Pr, respectively) and standard molal enthalpies of transition (? H° t,Pr), melting (? H° m,Pr), and vaporization (? H° v,Pr) of organic species at 1 bar ( Pr) have been tabulated, together with an internally consistent and comprehensive set of standard molal Gibbs free energies and enthalpies of formation from the elements in their stable state at 298.15 K ( Tr) and Pr (? G° f and ? H° f, respectively). The critical compilation also includes standard molal entropies ( S°) and volumes ( V°) at Tr and Pr, and standard molal heat capacity power function coefficients to compute the standard molal thermodynamic properties of organic solids, liquids, and gases as a function of temperature at 1 bar. These properties and coefficients have been tabulated for more than 500 crystalline solids, liquids, and gases, and those for many more can be computed from the equations of state group additivity algorithms. The crystalline species correspond to normal alkanes (C nH 2( n+1) ) with carbon numbers ( n, which is equal to the number of moles of carbon atoms in one mole of the species) ranging from 5 to 100, and 23 amino acids including glycine (C 2H 5NO 2), alanine (C 3H 7NO 2), valine (C 5H 11NO 2), leucine (C 6H 13NO 2), isoleucine (C 6H 13NO 2), aspartic acid (C 4H 7NO 4), glutamic acid (C 5H 9NO 4), asparagine (C 4H 8N 2O 3), glutamine (C 5H 10N 2O 3), proline (C 5H 9NO 2), phenylalanine (C 9H 11NO 2), tryptophan (C 11H 12N 2O 2), methionine (C 5H 11SNO 2), serine (C 3H 7NO 3), threonine (C 4H 9NO 3), cysteine (C 3H 7SNO 2), tyrosine (C 9H 11NO 3), lysine (C 6H 14N 2O 2), lysine:HCl (C 6H 15N 2O 2Cl), arginine (C 6H 14N 4O 2), arginine:HCl (C 6H 15N 4O 2Cl), histidine (C 6H 9N 3O 2), and histidine:HCl (C 6H 10N 3O 2Cl). The data for the latter compounds permit calculation of the standard molal thermodynamic properties of protein unfolding in biogeochemical processes (Helgeson et al 1998). The liquids and gases considered in the present study include normal alkanes (C nH 2( n+1) ) for carbon numbers ranging from 1 to 100, 2- and 3-methylalkanes (C nH 2( n+1) ) for 4 ? n ? 20 and 6 ? n ? 20, respectively, 2,3-dimethylpentane (C 7H 16), 4-methylheptane (C 8H 18), cycloalkanes (C nH 2 n) for 3 ? n ? 8, methylated benzenes (C nH 2( n-3) ) for 7 ? n ? 12, normal alkylbenzenes (C nH 2( n-3) ) for 6 ? n ? 20, normal 1-alcohols (C nH 2( n+1) O) for 1 ? n ? 20, ethylene glycol (C 2H 6O 2), glycerol (C 3H 8O 3), normal 1-alkanethiols (C nH 2( n+1) S) for 1 ? n ? 20, normal carboxylic acids (C nH 2 nO 2) for 2 ? n ? 20, and the following miscellaneous species: 2-thiabutane (C 3H 8S), thiophene (C 4H 4S), thiophenol (C 6H 6S), acetone (C 3H 6O), 2-butanone (C 4H 8O), ethyl acetate (C 4H 8O 2), pyridine (C 5H 5N), 3-methylpyridine (C 6H 7N), and quinoline (C 9H 7N). One additional liquid (2-methylthiacyclopentane (C 5H 10S)) was also considered along with crystalline and gaseous carbazole (C 12H 9N). The thermodynamic data and equations summarized below can be used together with the standard molal thermodynamic properties of high molecular weight organic compounds ( Richard and Helgeson 1995, Richard and Helgeson 1998a, Richard and Helgeson 1998b) and minerals, inorganic gases, and aqueo

Helgeson, Harold C.; Owens, Christine E.; Knox, Annette M.; Richard, Laurent

1998-03-01

435

Thermodynamic properties and heat capacities of Co (BTC) 1\\/3 (DMF) (HCOO)

A novel metal organic framework [Co (BTC)1\\/3 (DMF) (HCOO)]\\u000a n\\u000a (CoMOF, BTC = 1,3,5-benzene tricarboxylate, DMF = N,N-dimethylformamide) has been synthesized solvothermally and characterized by single crystal X-ray diffraction, X-ray powder\\u000a diffraction, and FT-IR spectra. The molar heat capacity of the compound was measured by modulated differential scanning calorimetry\\u000a (MDSC) over the temperature range from 198 to 418 K for the first time. The thermodynamic

Chun-Hong Jiang; Li-Fang Song; Jian Zhang; Li-Xian Sun; Fen Xu; Fen Li; Qing-Zhu Jiao; Zhen-Gang Sun; Yong-Heng Xing; Yong Du; Ju-Lan Zeng; Zhong Cao

2010-01-01

436

Thermodynamic properties of caesium zirconate Cs 2ZrO 3

The low-temperature heat capacity of Cs2ZrO3was measured fromT=5 K toT=393 K. For the standard molar entropy atT=298.15 K, a value of (199.2±0.8) J·K?1·mol?1was found. The enthalpy increment of Cs2ZrO3was measured fromT=542 K toT=703 K using drop calorimetry. Using these results, a thermodynamic table of caesium zirconate was generated.

R. P. C Schram; V. M Smit-Groen; E. H. P Cordfunke

1999-01-01

437

A quantum-chemical study of the thermodynamic properties of the CNOH3 isomers

NASA Astrophysics Data System (ADS)

The B3LYP/6-311++G(3 df,3 pd) DFT method was used to determine the geometry and vibrational frequencies for the formamide, formaldoxime, nitrosomethane, oxaziridine, and formimide. The potential energy functions of the hindered internal rotations were calculated. The conformers of formaldoxime and formimide were determined. For all the molecules, including the conformers, the thermodynamic characteristics ?f H° (298 K), S°(298 K), C p(298 K), and ?f G° (298 K) were determined. The temperature dependences C p( T) within 298-1500 K were represented in the form of cubic polynomials.

Turovtsev, V. V.; Stepnikov, I. V.; Kizin, A. N.; Orlov, Yu. D.

2007-02-01

438

NASA Astrophysics Data System (ADS)

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.

Szcz&?acute; niak, Rados?aw; Durajski, Artur P.

2013-11-01

439

Thermodynamic properties of diosgenin determined by oxygen-bomb calorimetry and DSC

NASA Astrophysics Data System (ADS)

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.

Zhao, Ming-Rui; Wang, Hong-Jie; Wang, Shu-Yu; Yue, Xiao-Xin

2014-12-01

440

NASA Astrophysics Data System (ADS)

The structural, vibrational, phonon and thermodynamic properties of TiC, ZrC and HfC have been investigated by first-principles calculations using the plane-wave pseudopotential method. The NaCl-type FCC structures are optimized and confirmed to be dynamically stable for these compounds. The vibrational modes at the ? point are analyzed using group theory for the studied carbides. The lattice dynamical results regarding the phonon dispersion curves, phonon density of states and thermodynamic properties are reported within the framework of density functional perturbation theory. It is shown that these compounds exhibit similar but slightly different behaviors for the phonon related properties, which is expected because the transition metal atoms are in the same IV group. The present calculation results compare satisfactorily to experimental and existing literature results.

Li, Hui; Zhang, Litong; Zeng, Qingfeng; Ren, Haitao; Guan, Kang; Liu, Qiaomu; Cheng, Laifei

2011-01-01

441

During the first half year of this research program the following elements of research have been performed: (1) the development of an improved pure component data bank, including collection and processing of data which is 70% complete as to substance, (2) calculation of distillable coal fluid th