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1

Thermodynamics properties of ferropericlase  

NASA Astrophysics Data System (ADS)

The thermodynamics properties of ferropericlase (Mg(1-x)FexO, xFe ~ 0.19), have been investigated by first principles using a combination of newly developed techniques designed to address materials of such complexity. The strongly correlated nature of ferrous iron has been successfully addressed previously in static calculations by using a first principles LDA+U approach. However, investigation of thermodynamics properties of the solid solution presents further challenges, particularly the inclusion of vibrational effects without which results are not predictive. We have developed a vibrational virtual crystal model (VVCM) to address this issue. The acoustic velocities of the VVCM are, by construction, precisely the same as those of the real solid solution. We present here unusual anomalies on the thermodynamics properties caused by the spin crossover transition. Research supported by NSF/EAR 0635990, and NSF/ITR 0428774 (VLab). Computations were performed at the Minnesota Supercomputing Institute.

de Gironcoli, S.; Wu, Z.; Justo, J. F.; da Silva, C. S.; Wentzcovitch, R.

2008-12-01

2

Thermodynamic Properties of HCFC-124  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of HCFC-124, such as saturated densities, vapor pressures and PVT properties, were measured and the critical parameters were determined through those experimental results. The correlations for vapor pressure, saturated liquid density and PVT properties deduced from those experimental results were compared with the measured data and also with the estimates of the other correlations published in literatures. The thermodynamic functions, such as enthalpy, entropy, heat capacity, etc., can reasonably be calculated from the correlation equations in this paper.

Fukushima, Masato; Watanabe, Naohiro

3

Thermodynamic Properties of Liquid Metals.  

National Technical Information Service (NTIS)

The ability of the model potentials to yield accurate thermodynamic properties of liquid metals is tested. The pressure and bulk moduli calculated by the homogeneous deformation (HD) method depend on the electron density derivative of the self energy. The...

R. Kumaravadivel

1982-01-01

4

Thermodynamic properties of methane  

NASA Astrophysics Data System (ADS)

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.

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

5

Thermodynamic properties of uranium dioxide  

NASA Astrophysics Data System (ADS)

In order to provide reliable and consistent data on the thermophysical properties of reactor materials for rector safety studies, revision was prepared for the thermodynamic properties of the uranium dioxide portion of the fuel property section of the report Properties for Liquid Metal Fast Breeder Reactors Safety Analysis. International agreement was reached on a vapor pressure equation for the total pressure over UO2, for the calculation of enthalpy and heat capacity, and a phase change at 2670 K. An electronic term is used in place of the Frenkel defect term in the enthalpy and heat capacity equation and the phase transition is accepted.

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

1981-04-01

6

Thermodynamic properties of dichloromethane gas  

SciTech Connect

Virial coefficients, derived from an analysis of precise P-V-T data, form a basis for the determination of thermodynamic properties and the force constants of appropriate intermolecular potential models. An earlier work reports experimental P-V-T measurements for dichloromethane gas from about 350 to 510 K along with compression factors and second virial coefficients. This study presents revised values of second virial coefficients and the following other derived quantities (the figure in parentheses indicates the estimated percent uncertainty): (i) third virial coefficients (2-20); (ii) Stockmayer (12-6-3) force constants; (iii) thermodynamic properties (0.2-0.5 up to 10 atm, increasing to 5 at 30 atm and above); and (iv) fugacity coefficients.

Singh, R.P.

1986-10-01

7

Thermodynamical properties of dark energy  

SciTech Connect

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

8

Thermodynamic properties of sea air  

NASA Astrophysics Data System (ADS)

Very accurate thermodynamic potential functions are available for fluid water, ice, seawater and humid air covering wide ranges of temperature and pressure conditions. They permit the consistent computation of all equilibrium properties as, for example, required for coupled atmosphere-ocean models or the analysis of observational or experimental data. With the exception of humid air, these potential functions are already formulated as international standards released by the International Association for the Properties of Water and Steam (IAPWS), and have been adopted in 2009 for oceanography by IOC/UNESCO. In this paper, we derive a collection of formulas for important quantities expressed in terms of the thermodynamic potentials, valid for typical phase transitions and composite systems of humid air and water/ice/seawater. Particular attention is given to equilibria between seawater and humid air, referred to as "sea air" here. In a related initiative, these formulas will soon be implemented in a source-code library for easy practical use. The library is primarily aimed at oceanographic applications but will be relevant to air-sea interaction and meteorology as well. The formulas provided are valid for any consistent set of suitable thermodynamic potential functions. Here we adopt potential functions from previous publications in which they are constructed from theoretical laws and empirical data; they are briefly summarized in the appendix. The formulas make use of the full accuracy of these thermodynamic potentials, without additional approximations or empirical coefficients. They are expressed in the temperature scale ITS-90 and the 2008 Reference-Composition Salinity Scale.

Feistel, R.; Wright, D. G.; Kretzschmar, H.-J.; Hagen, E.; Herrmann, S.; Span, R.

2010-02-01

9

Thermodynamic properties of sea air  

NASA Astrophysics Data System (ADS)

Very accurate thermodynamic potential functions are available for fluid water, ice, seawater and humid air covering wide ranges of temperature and pressure conditions. They permit the consistent computation of all equilibrium properties as, for example, required for coupled atmosphere-ocean models or the analysis of observational or experimental data. With the exception of humid air, these potential functions are already formulated as international standards released by the International Association for the Properties of Water and Steam (IAPWS), and have been adopted in 2009 for oceanography by IOC/UNESCO. In this paper, we derive a collection of formulas for important quantities expressed in terms of the thermodynamic potentials, valid for typical phase transitions and composite systems of humid air and water/ice/seawater. Particular attention is given to equilibria between seawater and humid air, referred to as ''sea air'' here. In a related initiative, these formulas will soon be implemented in a source-code library for easy practical use. The library is primarily aimed at oceanographic applications but will be relevant to air-sea interaction and meteorology as well. The formulas provided are valid for any consistent set of suitable thermodynamic potential functions. Here we adopt potential functions from previous publications in which they are constructed from theoretical laws and empirical data; they are briefly summarized in the appendix. The formulas make use of the full accuracy of these thermodynamic potentials, without additional approximations or empirical coefficients. They are expressed in the temperature scale ITS-90 and the 2008 Reference-Composition Salinity Scale.

Feistel, R.; Kretzschmar, H.-J.; Span, R.; Hagen, E.; Wright, D. G.; Herrmann, S.

2009-10-01

10

Thermodynamic and Properties of Nanophases  

SciTech Connect

A large volume of today s research deals with nanophases of various types. The materials engineer, chemist, or physicist, however, when dealing with applications of nanophases is often unaware of the effect of the small size on structure and properties. The smallest nanophases reach the limit of phase definitions by approaching atomic dimensions. There, the required homogeneity of a phase is lost and undue property fluctuations destroy the usefulness of thermodynamic functions. In fact, itwas not expected that a definite nanophasewould exist belowthe size of a microphase.Aneffort ismadein this reviewto identify macrophases, microphases, and nanophases. It is shown that nanophases should contain no bulk matter as defined by macrophases and also found in microphases. The structure and properties of nanophases, thus, must be different from macrophases and microphases. These changes may include different crystal and amorphous structures, and phase transitions of higher or of lower temperature. The phase properties are changing continuously when going from one surface to the opposite one. The discussion makes use of results from structure determination, calorimetry, molecular motion evaluations, and molecular dynamics simulations.

Wunderlich, Bernhard {nmn} [ORNL

2009-01-01

11

Tables of thermodynamic properties of sodium  

SciTech Connect

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

12

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

13

Thermodynamic Properties of Organic Derivatives of the Lighter Elements and Thermodynamic Properties of Fluids.  

National Technical Information Service (NTIS)

An investigation of strained small-ring compounds in families of cyclic amines and epoxy butanes was continued. The thermodynamic properties of 1,2-epoxybutane including enthalpy of combustion and formation, low-temperature thermal properties, vapor press...

A. Osborn D. R. Douslin H. L. Finke J. F. Messerly W. D. Good

1973-01-01

14

Thermodynamic Properties of Compressed Gaseous Methane.  

National Technical Information Service (NTIS)

Real gas thermodynamic properties, H - H(0), S - S(0), and G - G(0), of methane were determined as functions of temperature and molal density over a pressure range of 0 - 400 atm. These properties are recommended as standards for the development of equati...

D. R. Douslin R. H. Harrison R. T. Moore

1973-01-01

15

Thermodynamic Properties of HCFC142b  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of HCFC142b,namely saturated densities,vapor pressures and PVT properties,were measured and the critical parameters were determined through those experimental results. The correlations for vpor pressure, saturated liquid density and PVT properties deduced from those experimental results were compared with the measured data and also with the estimates of the other correlations published in literatures. The thermodynamic functions,such as enthalpy,entropy,heat capacity and etc.,could be considered to be reasonab1y estimatedby the expression reported in this paper.

Fukushima, Masato; Watanabe, Naohiro

16

Thermodynamic properties of 13C-diamond  

Microsoft Academic Search

Changes in thermodynamic properties of diamond at isotopic substitution 12C?13C have been rigorously calculated at room and higher temperatures by using the first order of the thermodynamic perturbation theory. At 25°C, the relative changes in the lattice constant of diamond, in coefficient of thermal expansion, in isothermal bulk modulus, and in heat capacity are equal to -(1.54±0.15) × 10?4, 7.58

V. B. Polyakov; N. N. Kharlashina; A. A. Shiryaev

1997-01-01

17

Thermodynamic Properties of Ar39 Cluster  

NASA Astrophysics Data System (ADS)

The solid-liquid phase transitions of Ar39 cluster was simulated by the microcanonical Molecular Dynamics (MD) and microcanonical Parallel Tempering (PT) Monte Carlo methods using Lennard-Jones potential, and thermodynamic quantities were calculated. All thermodynamic quantities (configurational entropy, thermodynamic temperature, microcanonical heat capacity, potential energy distribution) were evaluated by using multiple histogram method. The same results were found in both simulation methods. The thermodynamic properties of microcanonical results indicate that the caloric curve has S-dent and the negative heat capacity has negative values at the solid-liquid phase transition region. At the same time by using microcanonical results melting temperature, latent heat and entropy change upon melting values were reported and compared with the values reported in the literature and the values calculated from the thermodynamic relations offered for bulk matter and, consistent values were found.

Eryurek, M.; Guven, M. H.

2007-04-01

18

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

19

Thermodynamic Properties of Aqueous Sodium Chloride Solutions  

Microsoft Academic Search

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?T?573 K,

Kenneth S. Pitzer; J. Christopher Peiper; R. H. Busey

1984-01-01

20

Dissociation constants and thermodynamic properties of alkanolamines  

Microsoft Academic Search

The dissociation constants of protonated 2-amino-2-ethyl-1,3-propanediol (AEPD), 2-amino-2-methyl-1-propanol (AMP), diethylmonoethanolamine (DEMEA), diisopropanolamine (DIPA), dimethylmonoethanolamine (DMMEA), monoethanolamine (MEA), 1-amino-2-propanol (MIPA), and methylmonoethanolamine (MMEA) have been determined by electromotive force measurements from (293 to 353) K. The experimental results and derived values of the standard state thermodynamic properties are reported.

Espen S. Hamborg; Geert F. Versteeg

2009-01-01

21

A thermodynamic property formulation for cyclohexane  

Microsoft Academic Search

A formulation for the thermodynamic properties of cyclohexane is presented. The equation is valid for single-phase and saturation states from the melting line to 700 K at pressures up to 80 MPa. It includes a fundamental equation explicit in reduced Helmholtz energy with independent variables of reduced density and temperature. The functional form and coefficients of the ancillary equations were

S. G. Penoncello; R. T. Jacobsen; A. R. H. Goodwin

1995-01-01

22

Tetrafluoromethane, Thermodynamic Properties of the Real Gas.  

National Technical Information Service (NTIS)

The thermodynamic properties, H-H(standard state), S-S(std. state), and G-G(std. state), of tetrafluoromethane were determined as functions of temperatures (0 to 350 C.) and molal density (0.75 to 11.0 gram-moles per liter) over a pressure range of 0 to 4...

R. H. Harrison D. R. Douslin

1965-01-01

23

High-temperature thermodynamic properties of forsterite  

Microsoft Academic Search

The high-temperature thermodynamic properties of forsterite were reviewed in the light of a new determination of the isobaric heat capacity (Cp), up to 1850 K, and Raman spectroscopic measurements, up to 1150 K and 10 GPa. The Cp measurements and available data on thermal expansion (alpha) and bulk modulus (K) show that the isochoric specific heat (Cnu) exceeds the harmonic

Philippe Gillet; Pascal Richet; François Guyot; Guillaume Fiquet

1991-01-01

24

HIGH TEMPERATURE THERMODYNAMIC PROPERTIES OF REACTOR MATERIALS  

Microsoft Academic Search

High-temperature thermodynamic properties of reactor materials are ; important to chemical engineers, ceramists, metallurgists, and reactor engineers ; in developing pyromnetallurgical processing procedures, fabricating fuel ; assemblies, and designing high temperature reactors. A critical evaluation and ; discussion is to be presented so that reliable free energies and phase diagrams ; if possible are available to enable one to predict

R. J. Ackermann; R. J. Thorn

1958-01-01

25

Thermodynamic properties of nitrogen at high pressures  

Microsoft Academic Search

The thermodynamic properties of nitrogen and other industrially important gases have been adequately investigated in the range of parameters from the saturation line up to temperatures of 1300~ and pressures of 1000 bar [1] and, also, at temperatures up to 3000~ and pressures up to 100 bar [2]. These data were derived from the results of a considerable number of

A. A. Antanovich; Me A. Plotnikov; G. Ya. Savel'ev

1969-01-01

26

Prediction of Thermodynamic Properties of Alternative Refrigerants  

NASA Astrophysics Data System (ADS)

The use of refrigerant mixtures for R22 alternative has recently been attracted in refrigerating and air conditioning industry. However, there has not been enough information about thermodynamic properties required to analyse the properties of mixtures. In this paper, stressing the adaptability of the modified van der Waals equation of state for refrigerant mixtures, the prediction methods of thermodynamic properties for the a1ternative refrigerant and mixture are explained. Seven generalized equations of state are chosen for the subjects of discussion. Data on R32,R125,R134a and their mixtures are applied to discuss the adaptability of these equations. Resu1ts of calculation using these equations are compared with available experimental and reference data. The optimum binary interaction parameters for those equations of state are a1so presented.

Fukushima, Masato

27

Thermodynamic Properties of Organic Derivatives of the Lighter Elements and Thermodynamic Properties of Fluids.  

National Technical Information Service (NTIS)

Strained small ring systems were investigated as possible group constituents in synthetic high energy fuels. Determination of the thermodynamic properties of trimethylene oxide (oxetane) in the ideal gas state from 0 to 1000 K by statistical mechanical me...

D. R. Douslin D. W. Scott H. L. Finke J. F. Messerly W. D. Good

1972-01-01

28

Integrated 3-Parameter Diagram for Determining Thermodynamic Properties of Fluids.  

National Technical Information Service (NTIS)

The importance of thermodynamic properties of fluids has motivated recent studies in developing methods of calculating thermodynamic properties. Among the various methods, the use of computational diagrams is a commonly used engineering method. Convention...

G. Zhao X. Deng M. Zhu

1987-01-01

29

High temperature drop calorimetry and thermodynamic properties  

SciTech Connect

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

30

Thermodynamic and transport properties of sodium liquid and vapor  

Microsoft Academic Search

Data have been reviewed to obtain thermodynamically consistent equations for thermodynamic and transport properties of saturated sodium liquid and vapor. Recently published Russian recommendations and results of equation of state calculations on thermophysical properties of sodium have been included in this critical assessment. Thermodynamic properties of sodium liquid and vapor that have been assessed include: enthalpy, heat capacity at constant

J. K. Fink; L. Leibowitz

1995-01-01

31

Thermodynamic properties for the alternative refrigerants  

Microsoft Academic Search

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

32

The thermodynamic properties of thianthrene and phenoxathiin  

SciTech Connect

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

33

The thermodynamic properties of benzothiazole and benzoxazole  

SciTech Connect

This research program, funded by the Department of Energy, Office of Fossil Energy, Advanced Extraction and Process Technology, provides accurate experimental thermochemical and thermophysical properties for key'' organic diheteroatom-containing compounds present in heavy petroleum feedstocks, and applies the experimental information to thermodynamic analyses of key hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation reaction networks. Thermodynamic analyses, based on accurate information, provide insights for the design of cost-effective methods of heteroatom removal. The results reported here, and in a companion report to be completed, will point the way to the development of new methods of heteroatom removal from heavy petroleum. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for benzothiazole and benzoxazole. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclinded-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Critical property estimates are made for both compounds. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 280 K and near 650 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathways for the removal of the heteratoms by hydrogenolysis. The results obtained in this research are compared with values present in the literature. The failure of a previous adiabatic heat capacity study to see the phase transition in benzothiazole is noted. Literature vibrational frequency assignments were used to calculate ideal gas entropies in the temperature range reported here for both compounds. Resulting large deviations show the need for a revision of those assignments. 68 refs., 6 figs., 15 tabs.

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

1991-08-01

34

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

35

Thermodynamic properties of higher lanthanum silicide  

SciTech Connect

The thermodynamic properties of lanthanum disilicide were examined for the first time in the 960-1050/sup 0/K range by measuring the electromotive force of a galvanic cell based on LaSn, the chlorides of potassium, sodium, and lanthanum, and lanthanum silicide and silicon. Reference electrodes were used to prevent lanthanum interaction with the electrolyte. The alloys were melted in an electric arc furnace in purified argon from lanthanum and silicon and followed by two-stage annealing. It was found that the resulting value of the enthalpy formation differed from the estimated value for lanthanum disilicide calculated by Miedema's model.

Polotskaya, R.I.

1988-07-01

36

Thermodynamic properties of 3-dimensional quantum antiferromagnets  

NASA Astrophysics Data System (ADS)

We present systematic calculations of thermal properties of 3-dimensional quantum antiferromagnets, in the thermodynamic limit, using series expansions. For this purpose, High Temperature Expansions (HTE) are supplemented by Numerical Linked Cluster (NLC) Expansions.footnotetextR. Applegate et al, Phys. Rev. Lett. 109, 097205 (2012); R. R. P. Singh and J. Oitmaa Phys. Rev. B 85, 144414 (2012); R. R. P. Singh and J. Oitmaa Phys. Rev. B 85, 104406 (2012). These expansions provide essentially exact calculations of thermodynamic properties of the system at (i) all fields at high temperatures and (ii) at all temperatures at high fields. In addition, we show that for classical exchange spin-ice model defined on the pyrochlore lattice, the first order NLC leads to the Pauling approximation, which gives even the zero-field ground state entropy to about one percent accuracy. Thus, these calculations are accurate over a wide parameter range. Results are presented and compared with a variety of experimental systems including pyrochlore materials Yb2Ti2O7 and Er2Ti2O7 and the Hyper Kagome material Na4Ir3O8

Singh, Rajiv R. P.; Oitmaa, Jaan; Gingras, Michel J. P.

2013-03-01

37

A thermodynamic property formulation for cyclohexane  

NASA Astrophysics Data System (ADS)

A formulation for the thermodynamic properties of cyclohexane is presented. The equation is valid for single-phase and saturation states from the melting line to 700 K at pressures up to 80 MPa. It includes a fundamental equation explicit in reduced Helmholtz energy with independent variables of reduced density and temperature. The functional form and coefficients of the ancillary equations were determined by weighted linear regression analyses of evaluated experimental data. An adaptive regression algorithm was used to determine the final equation. To ensure correct thermodynamic behavior of the Helmholtz energy surface the coefficients of the fundamental equation were determined with multiproperty fitting, Pressure-density-temperature ( P-p-T) and isobaric heat capacity ( C p - P-T) data were used to develop the fundamental equation, Saturation P-p-T values, calculated from the estimating functions, were used to ensure thermodynamic consistency at the vapor-liquid phase boundary. Separate functions were used for the vapor pressure, saturated liquid density, saturated vapor density. ideal-gas heat capacity. and pressure on the melting curve, Comparisons between experimental data and values calculated using the fundamental equation are given to verify the accuracy of the formulation. The formulation given here may be used to calculate densities within ±0.1 %, heat capacities to within ±2 %. and speed of sound to within ± 1 %, except near the critical point.

Penoncello, S. G.; Jacobsen, R. T.; Goodwin, A. R. H.

1995-03-01

38

Prediction of thermodynamic properties of coal derivatives  

SciTech Connect

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

39

Thermodynamic properties of a Kerr nonlinear blackbody.  

PubMed

Within the framework of quantum field theory, we present the superfluid state of photons in a blackbody whose interior is filled by a Kerr nonlinear crystal. The thermodynamic properties of a Kerr nonlinear blackbody are investigated. At the transition temperature, the Gibbs free energy of the two phases is continuous but the entropy density of the two phases is discontinuous. Hence, there is a jump in the entropy density and this leads to a latent heat density. The photon system undergoes a first-order phase transition from the normal to the superfluid state. The transition temperature is characteristic of a concrete crystal. The entropy density and specific heat capacity are monotonically increasing functions of the temperature but are monotonically decreasing functions of the Kerr nonlinear coefficient. PMID:23214733

Cheng, Ze

2012-11-05

40

Simple optimized Brenner potential for thermodynamic properties of diamond  

Microsoft Academic Search

We have examined the commonly used Brenner potentials in the context of the thermodynamic properties of diamond. A simple optimized Brenner potential is proposed that provides very good predictions of the thermodynamic properties of diamond. It is shown that, compared to the experimental data, the lattice wave theory of molecular dynamics (LWT) with this optimized Brenner potential can accurately predict

F. Liu; Q. H. Tang; B. S. Shang; T. C. Wang

2012-01-01

41

Simple optimized Brenner potential for thermodynamic properties of diamond  

Microsoft Academic Search

We have examined the commonly used Brenner potentials in the context of the thermodynamic properties of diamond. A simple optimized Brenner potential is proposed that provides very good predictions of the thermodynamic properties of diamond. It is shown that, compared to the experimental data, the lattice wave theory of molecular dynamics (LWT) with this optimized Brenner potential can accurately predict

F. Liu; Q. H. Tang; B. S. Shang; T. C. Wang

2011-01-01

42

Thermodynamic properties of charge-density waves  

NASA Astrophysics Data System (ADS)

Low-temperature thermodynamic properties of linear-chain compounds exhibiting charge-density waves (CDW) are examined theoretically within a mean-field theory. A result for the spin susceptibility ? is obtained which agrees with the clear-cut available data on K0.3MoO3 for T<0.9TP, where TP is the Peierls transition temperature. The influence of ordinary impurities on the order parameter ?, the half-gap ?G, and spin susceptibility ? is calculated. Numerical results are obtained for ? and ?G as a function of the impurity concentration x. Substantial difference is found between the lattice distortion parameter ? and the half-gap ?G even for relatively small impurity concentration x, which is directly accessible to experimental verification. Beyond a critical concentration x'c, the excitation spectrum of CDW condensate does not exhibit a gap. The order parameter also yields the transition temperature as a function of x, in agreement with earlier results of Patton and Sham and with recent experiments on TaS3 doped with Nb and Se impurities. Impurities are found to enhance spin susceptibility. However, the susceptibility at zero temperature remains zero for all concentrations, except in the gapless regime.

Roshen, Waseem A.

1985-06-01

43

Thermodynamic properties of inverse power fluids.  

PubMed

The local scaling behavior of the radial distribution function of the soft sphere or inverse power, r-n potential, fluid leads to a formula for the equation of state. From this formula different analytic forms for the compressibility factor, Z, have been derived. In the first, Z is expressed as a product of three functions, the hard sphere equation of state and two other functions incorporating the effects of the potential softness. In the second formula, the compressibility factor is cast in terms of the position and height of the first peak in the radial distribution function. In the final form, Z can be expressed as an exponential function which depends entirely on a combination of the virial coefficients. In each case Z is an explicit expression which has the correct low density limiting behavior and is accurate up to the freezing density for all packing fractions and circa n>or=12. Expressions are derived for the various component functions required for the different forms of Z, and relations between them are established. The compressibility factor manifests a maximum value or "ridge" when plotted as contours on the density-softness plane. It starts for the softer fluids at lower densities, increases with particle stiffness, and crosses the freezing line at n congruent with 33. From the compressibility factor other thermodynamic quantities can be obtained and the density-softness dependence of the infinite frequency limit elastic properties been determined. A self-consistent expression is derived for the effective hard sphere packing fraction (or equivalently, diameter), valid for all packing fractions and circa n>12. The effective hard-sphere diameter is compared with the formulas of Barker and Henderson, and Wheatley. PMID:17025613

Bra?ka, A C; Heyes, D M

2006-09-13

44

Thermodynamic Properties of Organic Derivatives of the Lighter Elements.  

National Technical Information Service (NTIS)

Strained small ring systems were investigated as possible group constituents in synthetic high energy fuels. Thermodynamic properties of cyclopropylamine and oxetane were determined from a comprehensive investigation of the heat capacities and heats of tr...

D. R. Douslin H. L. Finke J. F. Messerly R. H. Harrison W. D. Good

1971-01-01

45

MOISTURE SORPTION THERMODYNAMIC PROPERTIES OF CORN STOVER FRACTIONS  

Microsoft Academic Search

Efficient processing, handling, and storage of corn stover, a major crop-based biomass, require an understanding of the moisture sorption thermodynamic properties of its fractions. Moisture sorption thermodynamic properties of the major corn stover fractions such as leaf, stalk skin, and stalk pith were determined, utilizing the static gravimetric sorption isotherms data in the temperature range of 10°C to 40°C. Brunauer-Emmet-Teller

C. Igathinathane; A. R. Womac; S. Sokhansanj; L. O. Pordesimo

46

Thermodynamic and transport properties of sodium liquid and vapor  

SciTech Connect

Data have been reviewed to obtain thermodynamically consistent equations for thermodynamic and transport properties of saturated sodium liquid and vapor. Recently published Russian recommendations and results of equation of state calculations on thermophysical properties of sodium have been included in this critical assessment. Thermodynamic properties of sodium liquid and vapor that have been assessed include: enthalpy, heat capacity at constant pressure, heat capacity at constant volume, vapor pressure, boiling point, enthalpy of vaporization, density, thermal expansion, adiabatic and isothermal compressibility, speed of sound, critical parameters, and surface tension. Transport properties of liquid sodium that have been assessed include: viscosity and thermal conductivity. For each property, recommended values and their uncertainties are graphed and tabulated as functions of temperature. Detailed discussions of the analyses and determinations of the recommended equations include comparisons with recommendations given in other assessments and explanations of consistency requirements. The rationale and methods used in determining the uncertainties in the recommended values are also discussed.

Fink, J.K.; Leibowitz, L.

1995-01-01

47

Thermodynamic Property Values for Enzyme-catalyzed Reactions  

Microsoft Academic Search

This chapter deals with how one can obtain values of thermodynamic properties - specifically the apparent equilibrium constant K', the stan- dard molar transformed Gibbs energy change DrG', and the standard molar transformed enthalpy change DrH' for biochemical reactions - and, in particular, for enzyme-catalyzed reactions. In addition to direct measurement, these property values can be obtained in a variety

Robert N. Goldberg

2008-01-01

48

Dynamic and thermodynamic properties of glass-forming substances  

Microsoft Academic Search

We review the important general dynamic and thermodynamic properties of structural glass-forming substances and classify them into 12 different categories. Our understanding of glass-forming substances is incomplete until all these properties have been explained. The dynamic properties considered include those relating to the high frequency fast relaxation, the Johari–Goldstein ?-relaxation, and the slow structural ?-relaxation. Practically all the important relaxation

K. L. Ngai

2000-01-01

49

Ideal gas thermodynamic properties of methanoic and ethanoic acids  

Microsoft Academic Search

The thermodynamic properties (H0?H00, (G0?H00)\\/T, (H0?H00)\\/T, S0, Cp0, ?Hf0, ?Gf0, and log Kf] for methanoic (formic) and ethanoic (acetic) acid monomers and dimers in the ideal gaseous state over the temperature range from 0 to 1500 K and 1 atm have been calculated by the statistical thermodynamic method using the most recent and reliable molecular and spectroscopic constants. The internal

Jing Chao; Bruno J. Zwolinski

1978-01-01

50

A Theoretical Survey of DNA Oligomers Thermodynamic Properties  

NASA Astrophysics Data System (ADS)

Central to numerous techniques of molecular biology, some ubiquitous as PCR and Southern blotting, is the design of oligonucleotide probes possessing specific thermodynamic properties. Calculations of oligonucleotide thermodynamics, based on the nearest-neighbor model, have become increasingly accurate and have been extended to include not only canonical duplexes but also duplexes with mismatches. Here we use validated theoretical methods to explore the general behavior of melting temperature (Tm), free energy, and hybridization propensity in response to changes in experimental conditions and sequence. Distributions of these thermodynamic quantities are presented for DNA sequences of 5 to 50 bases sampled from the human genome. The effects of concentrations (oligonucleotide, cations), temperature, sequence composition constrains, and introduction of mismatches are considered. Thermodynamic quantities were computed using specially built softwares to facilitate our length sampling strategy. Our results provide a general survey of typical and limiting thermodynamic values that will be useful for the wide range of applications that rely on DNA probe design.

Koehler, Ryan; Peyret, Nicolas

2002-08-01

51

Structural properties of nanoclusters: Energetic, thermodynamic, and kinetic effects  

Microsoft Academic Search

The structural properties of free nanoclusters are reviewed. Special attention is paid to the interplay of energetic, thermodynamic, and kinetic factors in the explanation of cluster structures that are actually observed in experiments. The review starts with a brief summary of the experimental methods for the production of free nanoclusters and then considers theoretical and simulation issues, always discussed in

Francesca Baletto; Riccardo Ferrando

2005-01-01

52

Comparison of Thermodynamic Properties of Simulated Liquid Silica and Water  

Microsoft Academic Search

We conduct extensive molecular dynamics computer simulations of a rigid-ion model of liquid silica [L.V. Woodcock et al., J. Chem. Phys. 65, 1565 (1976)], evaluating thermodynamic and transport properties over a wide range of pressure and temperature. We find numerous similarities with behavior found in simulations of supercooled water, including a line of density maxima that passes through a maximum

Peter H. Poole; Mahin Hemmati; C. Austen Angell

1997-01-01

53

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

54

Thermodynamic Properties of the Cesium-Graphite Lamellar Compounds  

Microsoft Academic Search

The vapor pressures of the cesium—graphite lamellar compounds in the two-phase regions were measured at temperatures of 400° to 750°C. The Knudsen effusion method, in conjunction with a tracer technique employing cesium-134, was used. Thermodynamic properties were calculated from the data and are discussed in relation to the structures of the cesium—graphite lamellar compounds.

F. J. Salzano; S. Aronson

1965-01-01

55

Thermodynamic and mechanical properties of model mitochondrial membranes  

Microsoft Academic Search

Cardiolipin is a unique four-tailed, doubly negatively charged lipid found predominantly within the inner mitochondrial membrane, and is thought to be influential in determining membrane potential and permeability. To determine the role of cardiolipin in modulating the properties of membranes, this study investigates the thermodynamics of mixed cardiolipin and phosphatidylcholine monolayers and bilayers. Gibbs free energy analysis of mixed monolayers

Stephanie Nichols-Smith; Shia-Yen Teh; Tonya L. Kuhl

2004-01-01

56

The thermodynamic properties of bis-(?5-cyclopentadienylirondicarbonyl)  

NASA Astrophysics Data System (ADS)

The temperature dependence of the heat capacity of crystalline bis-(?5-cyclopentadienylirondicarbonyl) was studied over the temperature range 5-495 K in precision adiabatic vacuum and differential scanning calorimeters. The temperature dependence contained an anomaly (160-295 K) with a maximum at 250 K interpreted as a ? transition in the solid state. The fusion of the sample occurred at 435-491 K; it was accompanied by partial substance decomposition. The thermodynamic functions of crystalline bis-(?5-cyclopentadienylirondicarbonyl) were calculated from T?0 to 472.9 K. The enthalpy of combustion of the compound was determined in an isothermal calorimeter with a stationary bomb. The standard thermodynamic functions of its formation in the crystalline state at 298.15 K were calculated.

Kozlova, M. S.; Markin, A. V.; Larina, V. N.; Domracheva, L. G.; Sheiman, M. S.; Karyakin, N. V.

2008-12-01

57

Thermodynamic properties of fluids from Fluctuation Solution Theory  

SciTech Connect

Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.

O'Connell, J.P.

1990-01-01

58

Thermodynamic properties of fluids from Fluctuation Solution Theory  

SciTech Connect

Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.

O`Connell, J.P.

1990-12-31

59

Thermodynamic properties by non-calorimetric methods. Final report  

SciTech Connect

This research program provided a valuable complement to the experimental programs currently in progress at NIPER for the Advanced Research and Technology Development (AR and TD) and Advanced Exploration and Process Technology (AEPT) divisions of the Department of Energy. These experimental programs are focused on the calorimetric determination of thermodynamic properties of key polynuclear heteroatom-containing aromatic molecules. The project for the Office of Energy Research focused on the non-calorimetric determination of thermodynamic properties through the extension of existing correlation methodologies and through molecular spectroscopy with statistical mechanics. The paper discusses the following studies: Group-contribution approach for polycyclic aromatic hydrocarbons (naphthalene, phenanthrene, anthracene, pyrene, 3-methylphenanthrene, benzoquinolines, biphenyl/hydrogen system); Group-contribution approach for key monocyclic organic compounds; Molecular spectroscopy and statistical mechanics; and Thermophysical property correlations.

Steele, W.V.; Chirico, R.D.; Collier, W.B.; Strube, M.M.; Klots, T.D. [IIT Research Inst., Chicago, IL (United States)]|[National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1992-12-31

60

Thermodynamic properties of the kagome lattice in herbertsmithite  

NASA Astrophysics Data System (ADS)

Strongly correlated Fermi systems are among the most intriguing and fundamental systems in physics, whose realization in some compounds is still to be discovered. We show that ZnCu3(OH)6Cl2 can be viewed as a strongly correlated Fermi system whose low-temperature thermodynamics in magnetic fields is defined by a Fermi quantum spin liquid. Our calculations of its thermodynamic properties are in good agreement with recent experimental facts and allow us to reveal their scaling behavior which strongly resembles that observed in heavy-fermion metals and two-dimensional 3He.

Shaginyan, V. R.; Msezane, A. Z.; Popov, K. G.

2011-08-01

61

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.

62

Intermolecular interactions and the thermodynamic properties of supercritical fluids  

NASA Astrophysics Data System (ADS)

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.

Yigzawe, Tesfaye M.; Sadus, Richard J.

2013-05-01

63

Intermolecular interactions and the thermodynamic properties of supercritical fluids.  

PubMed

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

64

Thermodynamic Properties of Matrine in Ethanol  

NASA Astrophysics Data System (ADS)

In this paper, the enthalpies of dissolution of matrine in ethanol (EtOH) were measured using a RD496-2000 Calvet microcalorimeter at 309.65 K under atmospheric pressure. The differential enthalpy (?dif H m) and molar enthalpy (?sol H m) of dissolution of matrine in ethanol were determined. And the relationship between heat and the amount of solute was also established. Based on the thermodynamic and kinetic knowledge, the corresponding kinetic equation that described the dissolution process was determined to be {d?/dt=2.36× 10^{-4}(1-? )^{1.09}} . Moreover, the half-life, t 1/2 = 48.89 min, ?sol H m = -12.40 kJ · mol-1, ?sol S m = -354.7 J · mol-1 · K-1, and ? sol G m = 97.43 kJ · mol-1 of the dissolution process were also obtained. The results show that this work not only provides a simple method for the determination of the half-life for a drug but also offers a theoretical reference for the clinical application of matrine.

Li, Z. X.; Zhao, W. W.; Pu, X. H.

2011-06-01

65

Thermodynamic properties of an electron gas on a curved surface  

NASA Astrophysics Data System (ADS)

We report a study on thermodynamic properties of a two-dimensional electron gas confined in a sector of a circular cylinder immersed in a dc magnetic field perpendicular to its axis. This field configuration produces on the electrons in the curved surface, effects similar to a non-homogeneous magnetic field on a flat system. We study these effects by calculating the energy spectra for different curvature radius and symmetries of the magnetic field with respect to the surface. The analysis of the density of states, chemical potential and specific heat of these systems helps to understand the correlation between the externally controlled symmetry and their physical properties.

Batista, F. F.; Farias, G. A.; Almeida, N. S.

2013-09-01

66

Interactive calculations of thermodynamics properties of minerals in VLab  

NASA Astrophysics Data System (ADS)

We have developed a page within the VLab web site from which calculations of thermodynamics properties of minerals can be performed interactively. Previously published first principles calculations based on qhasiharmonic theory by our group have produced pressure dependent vibrational density of states (VDOSs). These calculations were costly and the essential information they produced, the VDOSs, are now stored on a database. They can be used to regenerate published results or calculate thermodynamics properties using specific user entered information (pressure and temperature range and grids, equation of state type, etc). Results are presented in numerical or graphics format (Gnuplot 4.2.2) that are interactively customized and downloadable. All codes behind the Web container are written in Java.

Kelly, N.; da Silveira, P. R.; Wentzcovitch, R. M.

2009-12-01

67

Thermodynamic properties of a rotating Bose gas in harmonic trap  

NASA Astrophysics Data System (ADS)

In this paper, the thermodynamic properties of a rotating Bose gas in harmonic trap are investigated. In particularly, the condensate fraction, critical temperature and heat capacity are analytically calculated. A simple semiclassical approximation, which is the density of state approach, is suggested. This approach is able to include the effects, such as the finite size and the chemical potential when becomes equal to the energy of the lowest energy state, that altered the rotating ideal Bose gas simultaneously. The calculated results show that the thermodynamic properties depend strongly on the rotation rate. The rapid rotation leads to a highly anisotropic confinement potential. The possibility for dimensionality cross-over to lower dimensions for this system is discussed. We compare the outcome results with the experimental measured data of Coddington et al. [Phys. Rev. A 70, 063607 (2004)].

Hassan, A. S.; El-Badry, A. M.; Soliman, S. S. M.

2011-10-01

68

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

69

Generalized thermodynamic and transport properties. I. Simple liquids.  

PubMed

We propose a method by which the generalized transport properties and coefficients at all wavelengths and frequencies can be obtained by inversion of an exact kinetic equation. The necessary data are the density-density, energy-energy, and density-energy time correlation functions, which can be obtained by molecular-dynamics simulation. In addition, also the coupling between viscous stress tensor and energy flux vector can be obtained without approximation. This allows one to check the validity of the Markov assumption in a straightforward way. As a first test case, the theory is applied to liquid argon in two thermodynamic states. For this system, we calculate and discuss generalized thermodynamic (enthalpy, specific heats, and thermal expansion) and transport properties (longitudinal viscosity, thermal conductivity). PMID:21517485

Bertolini, D; Tani, A

2011-03-11

70

Calculation of thermodynamic properties of metastable phases of the elements  

Microsoft Academic Search

A chemical bonding model that provides a method of predicting thermodynamic properties of metastable structures of the solid\\u000a elements is presented. The method involves a Born-Haber-type cycle to calculate the difference in bonding energies between\\u000a the room temperature stable structures and metastable structures. To carry out the calculations, spectroscopic data are used\\u000a to determine the promotion energies from the ground

J. Kouvetakis; L. Brewer

1993-01-01

71

Improved method for predicting thermodynamic properties-KBr  

Microsoft Academic Search

A method is described for predicting the thermodynamic properties of crystals that accounts for the effect of anharmonicity on the bulk modulus and on the equilibrium condition. An iterative procedure is used that makes the predicted room-temperature values for the bulk modulus and the nearest-neighbor distance self-consistent with the experimental values. Formulas are given for determining both the temperature and

Robert J. Hardy; Sudhir Bijanki; Arnold M. Karo

1976-01-01

72

Thermodynamic and rheological properties of hard sphere dispersions  

Microsoft Academic Search

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

73

Determining thermodynamic properties of molecular interactions from single crystal studies.  

PubMed

The concept of single crystals of macromolecules as thermodynamic systems is not a common one. However, it should be possible to derive thermodynamic properties from single crystal structures, if the process of crystallization follows thermodynamic rules. We review here an example of how the stabilizing potentials of molecular interactions can be measured from studying the properties of DNA crystals. In this example, we describe an assay based on the four-stranded DNA junction to determine the stabilizing potentials of halogen bonds, a class of electrostatic interactions, analogous to hydrogen bonds, that are becoming increasing recognized as important for conferring specificity in protein-ligand complexes. The system demonstrates how crystallographic studies, when coupled with calorimetric methods, allow the geometries at the atomic level to be directly correlated with the stabilizing energies of molecular interactions. The approach can be generally applied to study the effects of DNA sequence and modifications of the thermodynamic stability of the Holliday junction and, by inference, on recombination and recombination dependent processes. PMID:23933330

Vander Zanden, Crystal M; Carter, Megan; Ho, Pui Shing

2013-08-06

74

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

75

Standard Chemical Thermodynamic Properties of Alkyne Isomer Groups  

SciTech Connect

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

76

Thermodynamic properties of the Co-W-C system  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of the Co-W-C system have been evaluated by using the CALPHAD method. The properties of the Co-C and W-C systems are taken from recent analyses, whereas the properties of the Co-W system are evaluated in the first part of the present work. In particular, the effect of W in decreasing the Curie temperature of fcc Co (Tc) is evaluated from recent solubility data, by using the Hillert-Jarl model for magnetic Gibbs energy. Our evaluation gives a less dramatic effect of W on Tc than according to early work, but strong enough to produce a magnetic miscibility gap in the fcc phase. A new phase diagram for the Co-W system, showing the immiscibility effects, is presented. The properties of the fcc, hcp, and bcc phases, two ternary carbides (M12C and M6C), and the liquid phase in the Co-W-C system are evaluated in the second part. Various isothermal and vertical sections, and a projection of the liquidus surface of the Co-W-C diagram are reported. Most of the experimental information available is satisfactorily accounted for by the present thermodynamic description.

Guillermet, Armando Fernández

1989-05-01

77

Thermodynamic properties of pure and saline (geothermal) water  

SciTech Connect

In order to evaluate the performance of proposed processes utilizing geothermal energy, it is essential to determine the thermodynamic properties of fluid streams at various points in the system. The method described ascertains the values of these properties for either pure water or salt solution, correlating temperature, pressure, enthalpy, and entropy in the liquid, two-phase, and vapor regions. The corresponding FORTRAN computer formulation is coded in one subroutine and twenty-six function subprograms, sixteen of which represent correlations of the properties of pure water. The subroutine chooses the appropriate correlations, validates input data, and embodies a large fraction of the salt solution algorithms. Including nonexecutable comment lines, the entire formulation requires less than 910 lines of code. (MHR)

Packer, M.B.; Mikic, B.B.; Meal, H.C.; Guillamon-Duch, H.

1980-01-01

78

Thermodynamic properties of aluminous pyroxenes: results of least squares refinements  

SciTech Connect

The thermodynamic properties of binary clinopyroxenes on the joins diopside-jadeite, CaTs-jadeite and diopside-CaTs are determined using phase equilibria and calorimetric data. The random model, in which the entropy is calculated as if atoms mixed randomly on each site, is used as a base along with a formulation for the excess entropy. A non-linear least squares technique is used that allows for errors in each coordinate, has the correct functional form for weighting the data and allows determination of errors in functions calculated from derived thermodynamic parameters. The derived thermodynamic properties differ significantly from those obtained using linear regression. The excess entropy relative to the random model is negatively due to short-range order, but the random model is nevertheless appropriate as a first approximation. The least squares derived mixing entropies for Di-Jd and Di-CaTs are higher than predicted by a generalized pair approximation for short-range order using scaled ordering energies from electrostatic energy calculations. This may be because the scaled ordering energies are too high or because of a positive vibrational excess entropy, but more likely because of metastable disorder in the synthetic pyroxenes or systematic errors in phase equilibria or calorimetric data.

Cohen, R.E.

1985-01-01

79

Thermodynamic Properties of Organic Derivatives of the Lighter Elements and Thermodynamic Properties of Fluids.  

National Technical Information Service (NTIS)

An investigation of strained small ring systems as possible group constituents in synthetic high energy fuels was continued. The purification of research samples of 1,2-epoxybutane, trans-2,3-epoxybutane, and cyclopentylamine is described. Thermodynamic p...

A. Osborn D. R. Douslin H. L. Finke J. F. Messerlyerly W. D. Good

1973-01-01

80

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.

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

81

Generalized thermodynamic and transport properties. II. Molecular liquids.  

PubMed

In the present paper, we extend the method described in paper I [D. Bertolini and A. Tani, preceding paper, Phys. Rev. E 83, 031201 (2011)] to molecular liquids, which allows us to solve the exact kinetic equation proposed by de Schepper et al. [Phys. Rev. A 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. PMID:21517486

Bertolini, D; Tani, A

2011-03-11

82

Thermodynamic properties of Pu3+ and Pu4+ aquo ions  

NASA Astrophysics Data System (ADS)

The purpose of this work is to evaluate thermodynamic properties of some actinide ions in aqueous solution, particularly plutonium, taking into account their real characteristics, such as their covalent character and effective charge. The aquo ions are characterized by the charge q, crystallographic radius Rc with coordination number N, radius of the water molecule Rw and number H of molecules in the second hydration sphere. For the understanding of lanthanide and actinide aquo ion properties, we have performed EXAFS experiments on different trivalent and tetravalent ions (with concentration 7.10-3 to 0.2 M) in acidic solutions (HCl 1 M) at LURE. Based on our data and different published investigations, we have defined the coordination number N and the interatomic distances d between the cation and the oxygen atoms of the primary hydration sphere for the complete series of trivalent lanthanides, for some trivalent actinides (U, Np, Pu, Am and Cf) and for the tetravalent plutonium ion. .

David, F.; Fourest, B.; Hubert, S.; Purans, J.; Vokhmin, V.; Madic, C.

2000-07-01

83

Monte Carlo Simulation of Liquid Water and an Evaluation of Thermodynamic Properties  

Microsoft Academic Search

Monte Carlo simulations were performed on liquid water using a new intermolecular potential function. For the evaluation of the thermodynamic properties of liquid water, simple expressions were proposed for the energies and the partition function, which reproduces the results of simulations reasonably. Various thermodynamic properties including heat capacities and compressibility were obtained from the partition function. The anomalous properties of

Kazuhiko Honda; Kazuo Kitaura; Kichisuke Nishimoto

1991-01-01

84

Computational studies on the infrared vibrational spectra, thermodynamic properties, detonation properties, and pyrolysis mechanism of octanitrocubane  

Microsoft Academic Search

The molecular geometries, infrared vibrational spectra, and thermodynamic properties of octanitrocubane (ONC) are calculated using the density functional theory (DFT) method at the B3LYP\\/6-31G* level. The IR frequency scaling factor 0.9501 suitable for polynitrocubanes is obtained at the B3LYP\\/6-31G* level, and the calculated IR frequencies of ONC are scaled. The accurate heat of formation 726.47 kJ\\/mol of ONC in gas

Ji Zhang; Heming Xiao

2002-01-01

85

Property.  

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.

86

Vibrational and thermodynamic properties of transition-metal nanoclusters  

NASA Astrophysics Data System (ADS)

The knowledge of the vibrational spectrum of a cluster, which is the fingerprint of its structure, is necessary for the development of thermodynamics of clusters (melting, heat capacity, solid-solid structural transitions) and for the understanding of experimental vibrational spectra. In summary, the full vibrational spectrum of NiN and CuN nanoclusters with N from 2 to 150 atoms has been determined using the analytical expression of the embedded-atom method (EAM) for the force-constant tensor for the first time. In the determination of the spectra we have employed the global-minimum structures obtained in our previous unbiased EAM studies (see e.g. Physical Review B, 2004; 2006). Furthermore, using those spectra and the superposition approximation, the thermodynamic properties of the clusters have been calculated quantum mechanically, including their heat capacity and solid-solid transition temperatures for several structural changes in the Ni and Cu clusters. Both the vibrational spectrum and the thermodynamic functions show strong cluster-size effects. We emphasized that our approach is general. It is based only on the (common) EAM form of the total energy and applicable to many other many-body potentials.

Grigoryan, Valeri G.; Springborg, Michael

2013-03-01

87

Solvation of polymers as mutual association. II. Basic thermodynamic properties.  

PubMed

The theory of equilibrium solvation of polymers B by a relatively low molar mass solvent A, developed in the simplest form in Paper I, is used to explore some essential trends in basic thermodynamic properties of solvated polymer solutions, such as the equilibrium concentrations of solvated polymers AiB and free solvent molecules A, the mass distribution ?(AiB)(i) of solvated clusters, the extent of solvation of the polymer ?(solv), the solvation transition lines T(solv)(?B(o)), the specific heat C(V), the osmotic second virial coefficient B2, phase stability boundaries, and the critical temperatures associated with closed loop phase diagrams. We discuss the differences between the basic thermodynamic properties of solvated polymers and those derived previously for hierarchical mutual association processes involving the association of two different species A and B into AB complexes and the subsequent polymerization of these AB complexes into linear polymeric structures. The properties of solvated polymer solutions are also compared to those for solutions of polymers in a self-associating solvent. Closed loop phase diagrams for solvated polymer solutions arise in the theory from the competition between the associative and van der Waals interactions, a behavior also typical for dispersed molecular and nanoparticle species that strongly associate with the host fluid. Our analysis of the temperature dependence of the second osmotic virial coefficient reveals that the theory must be generalized to describe the association of multiple solvent molecules with each chain monomer, and this complex extension of the present model will be developed in subsequent papers aimed at a quantitative rather than qualitative treatment of solvated polymer solutions. PMID:23635166

Dudowicz, Jacek; Freed, Karl F; Douglas, Jack F

2013-04-28

88

Thermodynamic properties of the Group 1A elements  

SciTech Connect

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

89

Thermodynamic Properties of Polycyclic Aromatic Oxygen-Containing Compounds: I, Chroman and Isochroman: Topical Report.  

National Technical Information Service (NTIS)

Measurements leading to the calculation of the ideal-gas thermodynamic properties for chroman and isochroman are reported. Thermomechanical and thermophysical properties were determined by adiabatic heat-capacity calorimetry, combustion calorimetry, compa...

R. D. Chirico D. G. Archer I. A. Hossenlopp A. Nguyen W. V. Steele

1988-01-01

90

Magnetic refrigeration cycle analysis using selected thermodynamic property characterizations for gadolinium gallium garnet.  

National Technical Information Service (NTIS)

Magneto-thermodynamic property characterizations were selected, adapted, and compared to material property data for gadolinium gallium garnet in the temperature range 4--40 K and magnetic field range 0--6 T. The most appropriate formulations were incorpor...

R. W. Murphy

1992-01-01

91

Property.  

ERIC Educational Resources Information Center

This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state could…

Piele, Philip K.; Johnson, Margaret M.

92

Instrumentation for Measuring Thermodynamic Properties of Rare-Earth Compounds  

NASA Astrophysics Data System (ADS)

Current models on some Rare-Earth compounds cannot fully account for their strongly correlated electron behavior, which give rise to phenomenon such as unconventional superconductivity, heavy Fermion, and quantum critical behavior. The specific heat, thermopower, and thermal conductivity measurements give important thermodynamic properties, such as effective electronic mass, stiffness of the lattice (Debye temperature), entropy, density of states of charge carriers, and phase transitions which are crucial in characterizing these materials of interest in our laboratory. A calorimeter and a thermopower-thermal conductivity probe, which are using a modified relaxation method and standard steady-state heat flow technique, respectively, are constructed for the above purpose. Detailed schematic diagram and operating principles will be discussed in the report.

Urbina, Ulises I.; Thompson, Jonathon; Ho, Pei-Chun

2010-03-01

93

Phase transition and thermodynamic properties of Sr under high pressure  

NASA Astrophysics Data System (ADS)

We have performed the first-principles and classical molecular dynamics simulations to investigate the phase diagram and thermodynamic properties of Sr under high pressure and temperature. The obtained solid phase diagram of Sr, based on the quasi-harmonic approximation (QHA), is greatly supported by the available experimental data under low pressure. From the coexistence-phase molecular dynamics simulations, we also obtained the high-pressure melting curve of Sr which shows good agreement with the experiment. While, the experimentally observed ?-Sn structure of Sr-III was found to be mechanically unstable according to our phonon dispersion calculations and evolutionary algorithm structure searches. We find that ?-U phase (space group Cmcm) is energetically favorable and is the good candidate of Sr-III.

Liu, Zhong-Li; Li, Xiao-Feng; Zhang, Xiu-Lu; Cai, Ling-Cang; Jing, Fu-Qian

2011-12-01

94

Thermodynamical Properties of a Trapped Interacting Bose Gas  

NASA Astrophysics Data System (ADS)

The thermodynamical properties of interacting Bose atoms in a harmonic potential are studied within the mean-field approximation. For weak interactions, the quantum statistics is equivalent to an ideal gas in an effective mean-field potential. The eigenvalue of the Gross-Pitaevskii equation is identified as the chemical potential of the ideal gas. The condensation temperature and density profile of atoms are calculated. It is found that the critical temperature Tc decreases as the interactions increase. Below the critical point, the condensation fraction exhibits a universal relation of N0/N = 1-(T/Tc)?, with the index ? ? 2.3 independent of the interaction strength, the chemical potential, as well as the frequency of the confining potential.

Yang, Shi-Jie; Liu, Yuechan; Feng, Shiping

95

Thermodynamic and magnetic properties in two artificial frustrated lattices  

NASA Astrophysics Data System (ADS)

With the Monte Carlo simulation, we investigate the thermodynamics and magnetic properties of the artificial frustrated square and honeycomb lattices. The results from the Ising-like dipolar model show that there occurs one magnetic order transition for the square lattice while the honeycomb lattice exhibits two magnetic order phase transitions. When the magnetic field is applied perpendicular to one of sublattices, a sharp field-independent peak in the specific heat curves appears at a very low temperature for both frustrated lattices due to the occurrence of a long-range ordered state induced by the magnetic field. For the square lattice, the coercive field slightly increases with the angle of field relative to the vertical axis. For both frustrated lattices, the magnetic reversal is achieved mostly via flipping a chain of the nearest neighbor spins.

Li, Y.; Wang, T. X.; Liu, G. D.

2013-10-01

96

Thermodynamical properties of hairy black holes in n spacetime dimensions  

SciTech Connect

The issue concerning the existence of exact black hole solutions in the presence of a nonvanishing cosmological constant and scalar fields is reconsidered. With regard to this, in investigating no-hair theorem violations, exact solutions of gravity having as a source an interacting and conformally coupled scalar field are revisited in arbitrary dimensional nonasymptotically flat space-times. New and known hairy black hole solutions are discussed. The thermodynamical properties associated with these solutions are investigated and the invariance of the black hole entropy with respect to different conformal frames is proved. The issue of the positivity of the entropy is discussed and resolved for the case of black holes immersed in de Sitter space.

Nadalini, Mario; Vanzo, Luciano; Zerbini, Sergio [Dipartimento di Fisica, Universita di Trento and Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Trento (Italy)

2008-01-15

97

Structural investigation and thermodynamical properties of alkali calcium trihydrides  

NASA Astrophysics Data System (ADS)

The ground-state structure, equilibrium structural parameters, electronic structure, and thermodynamical properties of MCaH3 (M=Li, Na, K, Rb, and Cs) phases have been investigated. From the 104 structural models used as inputs for structural optimization calculations, the ground-state crystal structures of MCaH3 phases have been predicted. At ambient condition, LiCaH3, NaCaH3, and KCaH3 crystallize in hexagonal, monoclinic, and orthorhombic structures, respectively. The remaining phases RbCaH3 and CsCaH3 crystallize in a cubic structure. The calculated phonon spectra indicate that all the predicted phases are dynamically stable. The formation energy for the MCaH3 phases have been calculated along different reaction pathways. The electronic structures reveal that all these phases are insulators with an estimated band gap varying between 2.5 and 3.3 eV.

Vajeeston, P.; Ravindran, P.; Fjellva?G, H.

2010-03-01

98

Thermodynamic and transport properties of infinite U Hubbard model  

NASA Astrophysics Data System (ADS)

The infinite U Hubbard model, which excludes double occupancy of electrons on a lattice site, can be considered as an exactly solvable non-interacting orthofermion model. We obtained several thermodynamic and transport properties like specific heat, entropy, magnetization, magnetic susceptibility and thermoelectric power for the non-interacting orthofermions. It is found that in one dimension our results coincides with that of known exact results. In case of thermoelectric power, we have also obtained the generalized Heikes formula in high temperature limits and Stafford results at low temperatures. Since the non-interacting orthofermion model is exactly solvable in any dimension, our results can be used as a guide to ascertain the accuracy of the approximations, used to solve the finite U Hubbard model, frequently employed for the study of the strongly correlated electron systems.

Kishore, R.; Mishra, A. K.

2010-01-01

99

Thermodynamic Properties of Water: Tabulation from the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use.  

National Technical Information Service (NTIS)

Tables are provided for the density, enthalpy, entropy, and volume of water and steam calculated from the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use. This formulation is the current i...

A. H. Harvey

1998-01-01

100

The thermodynamic properties of 2,3-benzothiophene  

SciTech Connect

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

101

Thermodynamic and Transport Properties of Superconducting Mg10B2  

NASA Astrophysics Data System (ADS)

Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB2 superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, Hc2, with magnetization data giving dHc2/dT = 0.44 T/K at the transition temperature of Tc = 40.2 K. Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1 T. The value of dHc/dT at Tc is estimated to be about 12 mT/K, a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter ?~26. Estimates of the critical supercurrent density, Jc, using hysteresis loops and the Bean model, give critical current densities on the order of 105 A/cm2. Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb3Sn.

Finnemore, D. K.; Ostenson, J. E.; Bud'Ko, S. L.; Lapertot, G.; Canfield, P. C.

2001-03-01

102

Predicting liquid-phase thermodynamic properties using COSMO-SAC  

NASA Astrophysics Data System (ADS)

Predicting thermodynamic properties of liquids remains a significant challenge in both academia and industry. This is because molecules in the liquid phase are relatively close together but are not arranged in an ordered structure. The COSMO-SAC model uses quantum and statistical mechanics to predict the thermodynamic properties of liquids. In this thesis, a variety of efforts have been made to improve the accuracy of this model. The most successful of these involves the inclusion of dispersion interactions in mixture calculations, which reduces the average prediction error for activity coefficients by over 30%. It has also been demonstrated that the misfit energy—the traditional interaction energy used in all known COSMO-based models—is limited in its ability to model intermolecular interactions. A variety of attempts to improve the electrostatics of the model have been made, but these have had little effect on the overall accuracy. These include use of an expanded hydrogen bonding description, use of an alternate molecular surface construction method, and incorporation of three-dimensional considerations. These results, coupled with the observed improvement obtained from including dispersion interactions, suggest that the greatest weakness in the model is the handling of electrodynamics (how molecules polarize one another), and that future efforts to improve the model should target this area. In addition, the model has been parameterized for the ADF density functional software package, thus making it available to a wider audience. Results are approximately equivalent to those obtained with DMol3, the only package for which a published parameterization was previously available. Of significance, the ADF implementation allows one of the adjustable model parameters to be eliminated. Also, a correlation was found between experimental liquid volumes and the quantum-based molecular volumes employed in COSMO-SAC. This eliminates the need to provide experimental volumes to the model. Finally, a Windows-based graphical user interface for COSMO-SAC has been developed. This expands the availability of the model to anyone with only a general familiarity with thermodynamics. Without this, use is restricted to those with an in-depth knowledge of quantum mechanics, statistical mechanics and computer programming.

Burnett, Russell I.

103

Electronic, mechanical, and thermodynamic properties of americium dioxide  

NASA Astrophysics Data System (ADS)

By performing density functional theory (DFT) +U calculations, we systematically study the electronic, mechanical, tensile, and thermodynamic properties of AmO2. It is found that the chemical bonding character in AmO2 is similar to that in PuO2, with smaller charge transfer and stronger covalent interactions between americium and oxygen atoms. The stress-strain relationship of AmO2 is examined along the three low-index directions, showing that the [1 0 0] and [1 1 1] directions are the strongest and weakest tensile directions, respectively, but the theoretical tensile strengths of AmO2 are smaller than those of PuO2. The phonon dispersion curves of AmO2 are calculated and the heat capacities as well as lattice expansion curve are subsequently determined. The lattice thermal conductivity of AmO2 is further evaluated and compared with attainable experiments. Our present work integrally reveals various physical properties of AmO2 and can be referenced for technological applications of AmO2 based materials.

Lu, Yong; Yang, Yu; Zheng, Fawei; Wang, Bao-Tian; Zhang, Ping

2013-10-01

104

Ion-specific thermodynamical properties of aqueous proteins.  

PubMed

Ion-specific interactions between two colloidal particles are calculated using a modified Poisson-Boltzmann (PB) equation and Monte Carlo (MC)simulations. PB equations present good results of ionic concentration profiles around a macroion, especially for salt solutions containing monovalent ions. These equations include not only electrostatic interactions, but also dispersion potentials originated from polarizabilities of ions and proteins. This enables us to predict ion-specific properties of colloidal systems. We compared results obtained from the modified PB equation with those from MC simulations and integral equations. Phase diagrams and osmotic second virial coefficients are also presented for different salt solutions at different pH and ionic strengths, in agreement with the experimental results observed Hofmeister effects. In order to include the water structure and hydration effect, we have used an effective interaction obtained from molecular dynamics of each ion and a hydrophobic surface combined with PB equation. The method has been proved to be efficient and suitable for describing phenomena where the water structure close to the interface plays an essential role. Important thermodynamic properties related to protein aggregation, essential in biotechnology and pharmaceutical industries, can be obtained from the method shown here. PMID:20209247

Lima, Eduardo R A; Biscaia, Evaristo C; Boström, Mathias; Tavares, Frederico W

2010-03-01

105

Thermodynamic and transport properties for polar coal mixtures. Technical progress report, July 15December 31, 1984  

Microsoft Academic Search

Progress has been made towards the goal of developing relationships for the calculation of the thermodynamic and transport properties of polar coal mixtures. The initial phase of this work has involved the extension to polar systems of procedures for the calculation of thermodynamic properties of nonpolar mixtures from parameters of the components. The mixture constants and their composition derivatives are

Stiel

1984-01-01

106

Excess Thermodynamic Properties of Concentrated Aqueous Solutions at High Temperatures  

SciTech Connect

Measurements of the vapor pressure of the solvent in wide ranges of concentration and temperature provide information on solute solvation and ion pairing--the two phenomena most often invoked for description of dilute solutions. Even in moderately concentrated solutions, as interionic distances become comparable to ionic diameters, these simple concepts gradually lose their meaning and solutions behave like molten salts. The usefulness of experimental vapor pressure results increases rapidly with their accuracy, since derived properties, such as solution enthalpies and heat capacities, can be calculated. Very accurate results can be obtained by the isopiestic method, but primary vapor pressure data for standard solutions are needed. In order to obtain vapor pressures at conditions where accurate isopiestic standards are not available and to establish more accurate standards, the ORNL isopiestic apparatus was modified for simultaneous direct vapor pressure measurements and isopiestic comparisons. There are no comprehensive solution theories derived from molecular level models and able to predict thermodynamic properties of various electrolytes as the composition changes from dilute solutions to molten salts in a wide range of temperatures. Empirical and semi-empirical models are useful for representation of experimental results, interpretation of measurements of other properties such as conductance., solubility or liquid-vapor partitioning of solutes, and for verification of theoretical predictions. Vapor pressures for aqueous CaCl{sub 2}, CaBr{sub 2}, LiCl, LiBr, LiI, NaI were measured at temperatures between 380 and 523 K in the concentration range extended to water activities below 0.2 (over 30 mol/kg for LiCl). General equations based on the modified Pitzer ion-interaction model were used to obtain enthalpy and heat capacity surfaces, which are compared with direct calorimetric measurements.

Guszkiewicz, M.S.

2001-06-07

107

Guide for Use of Computer Programs for the Calculation of Thermodynamic Properties of Oxygen and Nitrogen. (Second Edition).  

National Technical Information Service (NTIS)

This guide describes the calculation of thermodynamic properties of oxygen and nitrogen using recent formulations developed in the Center for Applied Thermodynamic Studies at the University of Idaho. The programs provide for the calculation of properties ...

R. T. Jacobsen R. B. Stewart

1976-01-01

108

Wüstite: electric, thermodynamic and optical properties of FeO  

NASA Astrophysics Data System (ADS)

We report on a systematic optical investigation of wüstite. In addition, the sample under consideration, Fe0.93O, has been characterized in detail by electrical transport, dielectric, magnetic and thermodynamic measurements. From infrared reflectivity experiments, phonon properties, Drude-like conductivity contributions and electronic transitions have been systematically investigated. The phonon modes reveal a clear splitting below the antiferromagnetic ordering temperature, similar to observations in other transition-metal monoxides and in spinel compounds which have been explained in terms of a spin-driven Jahn-Teller effect. The electronic transitions can best be described assuming a crystal-field parameter Dq = 750 cm-1 and a spin-orbit coupling constant ? = 95 cm-1. A well defined crystal field excitation at low temperatures reveals significant broadening on increasing temperature with an overall transfer of optical weight into dc conductivity contributions. This fact seems to indicate a melting of the on-site excitation into a Drude behavior of delocalized charge carriers. The optical band gap in wüstite is close to 1.0 eV at room temperature. With decreasing temperature and passing the magnetic phase transition we have detected a strong blue shift of the correlation-induced band edge, which amounts to more than 15% and has been rarely observed in antiferromagnets.

Schrettle, F.; Kant, Ch.; Lunkenheimer, P.; Mayr, F.; Deisenhofer, J.; Loidl, A.

2012-05-01

109

Thermodynamic properties of methane hydrate in quartz powder.  

PubMed

Using the experimental method of precision adiabatic calorimetry, the thermodynamic (equilibrium) properties of methane hydrate in quartz sand with a grain size of 90-100 microm have been studied in the temperature range of 260-290 K and at pressures up to 10 MPa. The equilibrium curves for the water-methane hydrate-gas and ice-methane hydrate-gas transitions, hydration number, latent heat of hydrate decomposition along the equilibrium three-phase curves, and the specific heat capacity of the hydrate have been obtained. It has been experimentally shown that the equilibrium three-phase curves of the methane hydrate in porous media are shifted to the lower temperature and high pressure with respect to the equilibrium curves of the bulk hydrate. In these experiments, we have found that the specific heat capacity of the hydrate, within the accuracy of our measurements, coincides with the heat capacity of ice. The latent heat of the hydrate dissociation for the ice-hydrate-gas transition is equal to 143 +/- 10 J/g, whereas, for the transition from hydrate to water and gas, the latent heat is 415 +/- 15 J/g. The hydration number has been evaluated in the different hydrate conditions and has been found to be equal to n = 6.16 +/- 0.06. In addition, the influence of the water saturation of the porous media and its distribution over the porous space on the measured parameters has been experimentally studied. PMID:17845024

Voronov, Vitaly P; Gorodetskii, Evgeny E; Safonov, Sergey S

2007-09-11

110

Hydrogrossular (Katoite): Vibrational, Crystal-Chemical and Thermodynamic Properties  

NASA Astrophysics Data System (ADS)

There is great current interest in understanding interactions between H2O and its components and various Earth materials. Here, questions such as the bulk water content of the mantle, and what phases can incorporate OH- and in what concentrations come immediately to mind. In this regard, the hydrogarnet substitution (i.e., O4H4?SiO4) has received special attention, because it is a verified mechanism for allowing the incorporation of OH- in garnet and possibly in other silicates as well. At relatively low temperatures there is complete solid solution between Ca3Al2Si3O12 and Ca3Al2O12H12. The latter, pure OH-containing end-member is termed katoite/hydrogrossular. Its crystal structure has been investigated by various workers using X-ray and neutron diffraction, including at high pressures. Little is known about its vibrational properties and its thermodynamic behavior is not fully understood. Thus, we studied the low temperature IR spectra and measured the heat capacity of katoite in order to investigate its vibrational, crystal-chemical and thermophysical properties. Katoite was synthesized hydrothermally in Au capsules at 250 °C and 3 kb water pressure. X-ray powder measurements show that about 98-99% katoite was obtained. Powder IR spectra were recorded between 298 K and 10 K. The spectra are considerably different in the high wavenumber region, where O-H stretching modes occur. At room temperature the IR-active O-H band located around 3662 cm-1 is broad and it narrows and shifts to higher wavenumbers and also develops structure below about 80 K. Concomitantly, additional weak intensity O-H bands located around 3600 cm-1 begin to appear and they become sharper and increase in intensity with further decreases in temperature. The spectra indicate that the vibrational behavior of individual OH groups and their collective interactions measurably affect the lattice dynamic (i.e. thermodynamic) behavior. The low temperature heat capacity behavior was investigated with a relaxation calorimeter between 5 and 300 K on a mg-sized sample. The heat capacity data are well behaved at T < 300 K and show a monotonic decrease in magnitude with decreasing temperature. A standard third-law entropy value of S° = 421.7 ± 1.6 J/mol.K was calculated. Using this new calorimetric-based S° value and published standard enthalpy of formation data for katoite, a calorimetric-based Gibbs free energy of formation at 298 K can be obtained as ?G°f = -5021.2 kJ/mol. The Cp data show no evidence for any phase transition as possibly expected by the change in OH-mode behavior with decreasing temperature. It is worth noting that the katoite, in terms of lattice dynamic or thermodynamic behavior, should be thought of having OH groups and not O4H4 clusters or polyhedral units as is often written in the literature. The single crystallographic OH group in katoite shows very weak, if any, hydrogen bonding and the H atoms have large amplitudes of vibration. Very weak H bonding or the lack of it affects the nature of low energy OH-related vibrations and this leads to katoite's large S° value.

Dachs, E.; Geiger, C. A.

2011-12-01

111

Thermodynamic Properties of Oxygen from the Triple Point to 300 K with Pressures to 80 MPa  

Microsoft Academic Search

A joint project by the authors has resulted in two new thermodynamic property formulations for oxygen. The fundamental equation explicit in Helmholtz energy by Schmidt and Wagner has been used for the calculation of the property tables presented here, and for comparisons of calculated properties to the experimental data. The formulation of Stewart and Jacobsen is used in this paper

Richard B. Stewart; Richard T Jacobsen; W. Wagner

1991-01-01

112

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

113

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

SciTech Connect

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

114

Prediction of Thermodynamic Properties of Coal Derivatives. Progress Report, September 1, 1981-August 31, 1982.  

National Technical Information Service (NTIS)

It is the purpose of this research program to develop a model to predict the thermodynamic properties of coal derivatives. Unlike natural gas and petroleum, coal and its gasification and liquefaction products are predominantly aromatic and have substantia...

M. D. Donohue

1982-01-01

115

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

116

Diagram analysis of the Hubbard model: Stationarity property of the thermodynamic potential  

SciTech Connect

The diagram approach proposed many years ago for the strongly correlated Hubbard model is developed with the aim to analyze the thermodynamic potential properties. A new exact relation between renormalized quantities such as the thermodynamic potential, the one-particle propagator, and the correlation function is established. This relation contains an additional integration of the one-particle propagator with respect to an auxiliary constant. The vacuum skeleton diagrams constructed from the irreducible Green's functions and tunneling propagator lines are determined and a special functional is introduced. The properties of this functional are investigated and its relation to the thermodynamic potential is established. The stationarity property of this functional with respect to first-order variations of the correlation function is demonstrated; as a consequence, the stationarity property of the thermodynamic potential is proved.

Moskalenko, V. A., E-mail: moskalen@theor.jinr.r [Moldova Academy of Sciences, Institute of Applied Physics (Moldova, Republic of); Dohotaru, L. A., E-mail: statphys@asm.m [Technical University (Moldova, Republic of); Cebotari, I. D. [Moldova Academy of Sciences, Institute of Applied Physics (Moldova, Republic of)

2010-07-15

117

Excess Thermodynamic Properties of Aqueous Electrolytes to High Temperatures and Pressures.  

National Technical Information Service (NTIS)

Excess thermodynamic properties have been obtained for a number of pure and mixed aqueous electrolyte solutions at high temperatures and pressures through measurements of isopiestic ratios and enthalpies of dilution. The equipment and techniques used in t...

J. M. Simonson H. F. Holmes R. E. Mesmer R. H. Busey

1987-01-01

118

Investigation of thermodynamic and transport properties of liquid transition metals using Wills-Harrison potentials.  

National Technical Information Service (NTIS)

Thermodynamic properties such as entropy, specific heat capacity at constant pressure and isothermal compressibility have been calculated for liquid 3d, 4d and 5d transition metals near melting temperature. The hard sphere diameter for all such systems is...

M. A. Khaleque G. M. Bhuiyan R. I. M. Rashid

1998-01-01

119

Group contribution method for correlating and forecasting thermodynamic properties of petroleum fluids.  

National Technical Information Service (NTIS)

A group contribution method is presented for representating and forecasting thermodynamic properties of slightly polar fluids without molecular associations. The method combines the Peng-Robinson equation of state and an excess function model based on zer...

A. Wahabou

1987-01-01

120

Prediction of Thermodynamic Properties of Coal Derivatives. Progress Report, September 1, 1983-August 31, 1984.  

National Technical Information Service (NTIS)

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 s...

M. D. Donohue

1984-01-01

121

Prediction of Thermodynamic Properties of Coal Derivatives. Progress Report, September 1, 1985-August 31, 1986.  

National Technical Information Service (NTIS)

In this report, the progress of our efforts toward understanding molecular behavior and its effect on thermodynamic properties is presented. The theory has been developed to treat fluids and fluid mixtures with various molecular interactions, including in...

M. D. Donohue

1986-01-01

122

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

Microsoft Academic Search

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 1023K. The partial free energies

Zhongnan Guo; Michael Hindler; Wenxia Yuan; Adolf Mikula

2011-01-01

123

Phase diagram and thermodynamic properties of solid magnesium in the quasiharmonic approximation  

Microsoft Academic Search

Using a family of volume-dependent interatomic pair potentials derived from first principles, we calculate phonon properties and thermodynamic functions in the quasiharmonic approximation for the hcp and bcc phases of Mg over a wide range of volume and temperature. At atmospheric pressure, the calculated hcp phonon-dispersion curves and thermodynamic properties agree well with experiment. The pressure dependence of the Raman-active

J. D. Althoff; P. B. Allen; R. M. Wentzcovitch; John Moriarty

1993-01-01

124

Magnetic properties of ultrafine ferrihydrite clusters studied by Mossbauer spectroscopy and by thermodynamical analysis  

Microsoft Academic Search

Magnetic properties of ultrafine clusters of Fe5HO8·4H2O (ferrihydrite, FH), isolated in pores of polysorb, were studied by Mossbauer spectroscopy and by thermodynamical analysis. Thermodynamical analysis allowed the conclusion that magnetic properties of ultrafine clusters cannot be interpreted in terms of a second-order magnetic phase transition or of superparamagnetic behavior alone but require the consideration of a jump-like first order magnetic

I. P. Suzdalev; V. N. Buravtsev; V. K. Imshennik; Yu. V. Maksimov; V. V. Matveev; S. V. Novichikhin; A. X. Trautwein; H. Winkler

1996-01-01

125

Calculation of the thermodynamic properties of the Ga-Sb-Tl liquid alloys  

Microsoft Academic Search

The results of the calculation of the thermodynamic properties for liquid Ga-Sb-Tl alloys at the temperature 1073 K are presented in this paper. Initially, the most appropriate thermodynamic model for the investigated system was selected. Based on a comparison of the values calculated by different geometric models (Kohler, Muggianu, Toop, Hillert, Chou) with the existing experimental based data, asymmetric models

DRAGAN MANASIJEVI; I WAO KATAYAMA

2005-01-01

126

Electrochemical Determination of Thermodynamic Properties of Manganese Sulfate and Cadmium Oxysulfate.  

National Technical Information Service (NTIS)

The Bureau of Mines investigated thermodynamic properties of MnSo4 and 2CdO: CdSO4 to obtain basic thermodynamic data applicable to the treatment of mineral concentrates during roasting and sintering processes. Standard Gibbs energies of formation were de...

S. C. Schaefer

1983-01-01

127

Thermodynamic properties and transport coefficients of high-temperature air plasma  

Microsoft Academic Search

New calculated thermodynamic properties and transport coefficients of high temperature air are presented. The calculations, which assume local thermodynamic equilibrium, are performed for different pressures (from 0.1 to 1000 atm) in the temperature range from 50 to 30000 K. The results have been obtained by means of the perturbative Chapman-Enskog method, after an appropriate selection of the collision integrals. The

M. Capitelli; G. Colonna

2001-01-01

128

Thermodynamic properties and transport coefficients of high-temperature air plasma  

Microsoft Academic Search

Summary form only given, as follows. This paper presents the results of a revised calculation of the thermodynamic properties and transport coefficients presented by Capitelli et al. (see Eur. Phys. J. D., vol.11, p.279-89 (2000)) for high temperature air. The calculations, which assume local thermodynamic equilibrium, are performed for different pressures (from .001 to 1000 atm) in the temperature range

M. Capitelli; G. Colonna

2001-01-01

129

Thermodynamic equilibria in xylene isomerization. 3: The thermodynamic properties of o-xylene  

SciTech Connect

Measurements leading to the calculation of the ideal-gas thermodynamic properties for o-xylene (Chemical Abstracts registry number [95-47-6]) are reported. Experimental methods included adiabatic heat-capacity calorimetry (5 K to 420 K), comparative ebulliometry (313 K to 459 K), differential-scanning calorimetry (DSC), and vibrating-tube densitometry (323 K to 523 K). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 420 K and 550 K, the critical density, and the critical pressure were derived with the vapor-pressure, density, and DSC results. Results were combined with an enthalpy of combustion reported in the literature to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra from the literature for the vapor phase. A preliminary value for the barrier to methyl-group rotation is derived. All results are compared with literature values.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Cowell, A.B.; Reynolds, J.W.; Steele, W.V. [BDM Petroleum Technologies, Bartlesville, OK (United States). Bartlesville Thermodynamics Group

1997-07-01

130

Thermodynamic equilibria in xylene isomerization. 1: The thermodynamic properties of p-xylene  

SciTech Connect

Measurements and calculations leading to the determination of thermodynamic properties for the gaseous and condensed phases of p-xylene (Chemical Abstracts registry number (supplied by the authors) [106-42-3]) are reported. All measurement results reported were obtained with a differential-scanning calorimeter (DSC). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 370 K and 550 K, the critical density and the critical pressure were derived with fitting procedures involving the new DSC results and literature vapor pressures and ensities. Results were combined with heat capacities reported in the literature obtained with adiabatic calorimetry and the enthalpy of combustion to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra. Results are compared with literature values. Literature vapor pressures, enthalpies of vaporization, virial coefficients, densities, and heat capacities for the condensed and gaseous phases are checked for consistency with the values used in this research.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Steele, W.V. [BDM-Oklahoma Inc., Bartlesville, OK (United States). National Inst. of Petroleum and Energy Research

1997-03-01

131

Thermodynamic equilibria in xylene isomerization. 2: The thermodynamic properties of m-xylene  

SciTech Connect

Measurements leading to the calculation of the ideal-gas thermodynamic properties for m-xylene are reported. Experimental methods included adiabatic heat-capacity calorimetry (5 K to 430 K), vibrating-tube densitometry (323 K to 523 K), comparative ebulliometry (309 K to 453 K), and differential-scanning calorimetry (DSC). The critical temperature was measured by DSC. Saturation heat capacities for the liquid phase between 430 K and 550 K and the critical pressure were derived with the vapor-pressure and DSC results. Results were combined with an enthalpy of combustion reported in the literature to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at selected temperatures between 250 K and 550 K. The standard state is defined as the ideal gas at the pressure p = p{degree} = 101.325 kPa. Standard entropies are compared with those calculated statistically on the basis of assigned vibrational spectra for the vapor phase. All results are compared with literature values.

Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Reynolds, J.W.; Steele, W.V. [BDM Petroleum Technologies, Bartlesville, OK (United States). Bartlesville Thermodynamics Group

1997-05-01

132

Trimethylamineborane and Triethylamineborane: Low-Temperature Thermodynamic Properties.  

National Technical Information Service (NTIS)

The low-temperature thermal properties of trimethylamineborane and triethylamineborane were determined by adiabatic calorimetry over the range 12 to 390 K and 12 to 310 K, respectively. The quantities measured include the heat capacity of the condensed ph...

H. L. Finke S. S. Todd J. F. Messerly

1969-01-01

133

Thermodynamic model for calorimetric and phase coexistence properties of coal derived fluids  

Microsoft Academic Search

The objective of this project is to develop a thermodynamic model for phase equilibria and calorimetric properties of coal derived fluids. A model for phase equilibria of coal derived liquids is already available. This model is to be extended to include calorimetric properties. The modification involves the use of the modified UNIFAC correlation with suitably regressed parameters, combined with an

Kabadi

1989-01-01

134

Thermodynamic properties of double square-well fluids: Computer simulations and theory  

Microsoft Academic Search

Computer simulations have been performed to obtain the thermodynamic properties of fluids with double square-well potentials, that is, potentials consisting of two adjacent square wells with different depths. The compressibility factor, excess energy, chemical potential, constant-volume excess heat capacity, and other derived properties have been obtained. These data have been used to test the performance of several perturbation theories for

J. R. Solana

2008-01-01

135

Computer Calculations of Metastable and Stable Fe-C-Si Phase Diagrams from Binary Thermodynamic Properties.  

National Technical Information Service (NTIS)

The metastable and stable phase diagrams of the Fe-C-Si system were to be predicted at temperatures of interest by computer calculations. The calculations were to be based on the thermodynamic properties of the constituent binary systems. These properties...

S. C. Chueh

1987-01-01

136

Thermodynamic Properties of the Internal Rotation in Methyl Alcohol Vapor from 200 to 500°K  

Microsoft Academic Search

At ordinary and lower temperatures the thermodynamic properties of the methyl alcohol internal rotation are beyond the limits of available tabulations. For any internal rotator, of a given symmetry, with a fixed moment of inertia and potential barrier, two limiting values of each property can be calculated for any chosen temperature. Available tables are restricted to those cases for which

J. O. Halford

1950-01-01

137

First-principles study of structural, elastic, electronic, vibrational and thermodynamic properties of UN  

NASA Astrophysics Data System (ADS)

The structural, elastic, electronic, phonon and thermodynamic properties of UN are studied by density functional theory (DFT) within local-density approximation (LDA) and generalized gradient approximation (GGA), and GGA + U. The GGA calculations of the ground state structural and elastic properties of UN show an overall better agreement with experimental data compared to LDA or GGA + U. The melting temperature of UN (Tm) is estimated from the calculated elastic constant, with GGA predicting Tm = 2944 ± 300 K, in excellent agreement with experimental data. The calculated phonon dispersions of UN agree well with the low temperature measurements. Furthermore, the thermodynamic properties of UN are studied using quasiharmonic approximation by including both lattice vibrational and thermal electronic contributions. The predicted thermodynamic properties, such as enthalpy, entropy, Gibbs energy, heat capacity and thermal expansion coefficient, agree well with experimental data. The derived thermodynamic functions of UN are useful to the thermodynamic modeling of phase stabilities in UN-based materials. This study shows that the thermal electronic energy and entropy due to U 5f electrons are important to describe the free energy of UN, due to the metallic character of UN. The calculated thermodynamic properties also suggest that the anharmonic effects are less important in UN even at high-temperature.

Mei, Zhi-Gang; Stan, Marius; Pichler, Benjamin

2013-09-01

138

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: First-Principle Calculations for Elastic and Thermodynamic Properties of Diamond  

Microsoft Academic Search

The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTAL03 program. The lattice parameters, the bulk modulus, the heat capacity, the Grüneisen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V\\/V0 and pressure, the elastic constants under high pressure are

Zhi-Jian Fu; Guang-Fu Ji; Xiang-Rong Chen; Qing-Quan Gou

2009-01-01

139

A Thermodynamic Property Model for Fluid Phase Hydrogen Sulfide  

Microsoft Academic Search

A Helmholtz free energy equation of state for the fluid phase of hydrogen sulfide has been developed as a function of reduced temperature and density with 23 terms on the basis of selected measurements of pressure–density–temperature (P, ?, T), isobaric heat capacity, and saturation properties. Based on a comparison with available experimental data, it is recognized that the model represents

N. Sakoda; M. Uematsu

2004-01-01

140

Ideal-gas thermodynamic properties for natural-gas applications  

Microsoft Academic Search

Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of thecp0 correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were

M. Jaeschke; P. Schley

1995-01-01

141

Thermodynamic properties of boron trioxide in the glass transition region  

Microsoft Academic Search

Knowledge of the physical properties of glasses in the transition region is of importance both from a theoreti­ cal and a practical point of view. These data are of practical importance since the structure of a glass is frozen-in at the transition temperature Tg and the prop­ erties of a glass at room temperature are to some ex­ tent determined

R. D. Corsaro; J. Jarzynski

1974-01-01

142

Vapor pressures and thermodynamic properties of UF/sub 4/  

SciTech Connect

Various thermodynamic data generated at the Oak Ridge Gaseous Diffusion Plant for uranium tetrafluoride is discussed. The data includes vapor pressure and entropy and enthalpy of fusion data. Agreement with data generated by others is also discussed. Limited data on the thermodynamic values for vaporization of uranium tetrafluoride is included in tabular form.

Leitnaker, J.M.

1983-06-01

143

Thermodynamic and Mechanical Properties of Skeletal Muscle Contraction  

Microsoft Academic Search

Thermodynamic parameters such as the change of entropy, internal energy, and enthalpy were calculated as a function of the relative skeletal muscle strain within the framework of a proposed thermodynamic model. A value for the Young’s modulus for the skeletal muscle was also estimated. The obtained theoretical values are in a good agreement with available experimental results for the frog

Yu. I. Prylutskyy; A. M. Shut; M. S. Miroshnychenko; A. D. Suprun

2005-01-01

144

The thermodynamic properties of cubic fluorite-type MgF2: first-principles prediction  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of MgF2 with a fluorite structure under high pressures and temperatures have been investigated in this work using the Debye model. This model combines with first-principles calculations within local density approximation (LDA) using pseudo-potentials and a plane-wave basis in the framework of density functional theory, and takes into account the phononic effects within the quasi-harmonic approximation. The effects of the temperatures and pressures on the thermodynamic properties such as the Debye temperature ?, the heat capacity CV, the entropy S and the Grüneisen parameter ? are all investigated at extended pressure and temperature ranges for the first time. On the basis of the first-principles study and the Debye model, all the thermodynamic properties of MgF2 with a fluorite structure have been predicted in the entire pressure range from 0 to 135 GPa and temperatures up to the melting temperature 1500 K.

Sun, X. W.; Liu, Z. J.; Song, T.; Quan, W. L.; Chen, Q. F.

2012-06-01

145

Thermoelectric and thermodynamic properties of half-Heulser alloy YPdSb from first principles calculations  

NASA Astrophysics Data System (ADS)

The structural, electronic, thermoelectric and thermodynamic properties of ternary half-Heusler compound YPdSb are investigated using the first principle calculations. It is found that YPdSb is an indirect semiconductor. The calculated band gap is 0.161 eV with spin-orbital coupling including and 0.235 eV without spin-orbital coupling including, respectively. The electronic transport properties are obtained via Boltzman transport theory. The predicted Seebeck coefficient is 240 ?V/K and the thermoelectric performance can be optimized by n-type doping at room temperature. Moreover, the lattice dynamical results regarding the phonon dispersion curves, phonon density of states and thermodynamic properties are reported. Thermodynamics (heat capacity and Debye temperature) as well as mean phonon free path and the thermal conductivity in a temperature range of 0–300 K are determined.

Kong, Fanjie; Hu, Yanfei; Hou, Haijun; Liu, Yanhua; Wang, Baolin; Wang, Lili

2012-12-01

146

Calculation of the thermodynamic properties of liquid Ag-In-Sb alloys  

Microsoft Academic Search

The results of calculations of the thermodynamic properties of liquid Ag-In-Sb alloys are presented in this paper. The Redlich-Kister-Muggianu model was used for the calculations. Based on known thermodynamic data for constitutive binary systems and available experimental data for the investigated ternary system, the ternary interac- tion parameter for the liquid phase in the temperature range 1000-1200 K was deter-

IVAN MIHAJLOVI

2006-01-01

147

Low-temperature heat capacity and thermodynamic properties of InSe  

Microsoft Academic Search

The heat capacity of InSe has been measured at temperatures from 11.14 to 325.26 K using an adiabatic calorimeter. The results\\u000a differ significantly from earlier data (by ?2.2% at 200 K). The smoothed heat capacity data have been used to evaluate temperature-dependent\\u000a thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) of indium selenide. Its thermodynamic properties\\u000a under standard conditions

A. V. Tyurin; K. S. Gavrichev; V. P. Zlomanov

2007-01-01

148

Influence of composition and particle size on spin dynamics and thermodynamic properties of magnetoresistive perovskites.  

PubMed

The thermodynamic behavior and spin dynamics of the colossal magnetoresistive (CMR) perovskites of general formula La(1-x)(A)xMn(1-y)(B)yO3 (where A is an alkaline earth, and B = Al, In) have been studied in order to evidence the effect of composition and the influence of nanocrystallinity on the thermodynamic and magnetic characteristics. By using electron paramagnetic resonance (EPR) spectroscopy, the behavior of the exchange coupling integral (J) between Mn spins and the polaron activation energy (Ea) have been investigated. The thermodynamic properties represented by the relative partial molar free energies, enthalpies and entropies of oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressures of oxygen have been obtained by using solid electrolyte electrochemical cells method. The influence of the oxygen stoichiometry change on the thermodynamic properties was examined using the data obtained by a coulometric titration technique coupled with measurements of the electromotive force (EMF). The results were correlated with the average Mn valence values as determined by redox titration. The properties of the rare-earth manganites are strongly affected by the A- and B-site substitution and by the oxygen nonstoichiometry. New features related to the modifications in properties connected with the nanocrystalline state were evidenced. The correlation existing between the magnetic and thermodynamic characteristics were discussed in relation to significant changes in the overall concentration of defects. PMID:18464427

Tanasescu, Speranta; Maxim, Florentina; Teodorescu, Florina; Giurgiu, Liviu

2008-02-01

149

Thermodynamic properties of liquid copper–indium–tin alloys determined from e.m.f. measurements  

Microsoft Academic Search

The thermodynamics properties of liquid Cu–In–Sn alloys were determined using solid oxide galvanic cells with zirconia electrolyte:(I)Re+kanthal,Cux-Iny-Sn(1-x-y),‘In2O3’\\/\\/ZrO2+(Y2O3)\\/\\/NiO,Ni,Ptin the temperature range (973 to 1223)K. Applied In2O3 can be either pure or in the solid solutions with SnO2.Thermodynamics properties of the liquid phase were described by the Redlich–Kister–Muggianu formula. Using the commercial software different phase relations in the ternary system were calculated

Dominika Jendrzejczyk-Handzlik; Wojciech Gierlotka; Krzysztof Fitzner

2009-01-01

150

Thermodynamics properties of an anisotropic Ising antiferromagnet in both external longitudinal and transverse fields  

NASA Astrophysics Data System (ADS)

We have studied the anisotropic two-dimensional nearest-neighbor Ising model with competitive interactions in both uniform longitudinal field H and transverse magnetic field ?. Using the effective-field theory (EFT) with correlation in cluster with N=1 spin we calculate the thermodynamic properties as a function of temperature with values H and ? fixed. The model consists of ferromagnetic interaction Jx in the x direction and antiferromagnetic interaction Jy in the y direction, and it is found that for H/Jy?[0,2] the system exhibits a second-order phase transition. The thermodynamic properties are obtained for the particular case of ?=Jx/Jy=1 (isotropic square lattice).

do Nascimento, Denise A.; Neto, Minos A.; de Sousa, J. Ricardo; Pacobahyba, J. T. M.

2013-11-01

151

Thermodynamic properties of correlated fermions in lattices with spin-dependent disorder  

NASA Astrophysics Data System (ADS)

Motivated by the rapidly growing possibilities for experiments with ultracold atoms in optical lattices, we investigate the thermodynamic properties of correlated lattice fermions in the presence of an external spin-dependent random potential. The corresponding model, a Hubbard model with spin-dependent local random potentials, is solved within dynamical mean-field theory. This allows us to present a comprehensive picture of the thermodynamic properties of this system. In particular, we show that for a fixed total number of fermions spin-dependent disorder induces a magnetic polarization. The magnetic response of the polarized system differs from that of a system with conventional disorder.

Makuch, K.; Skolimowski, J.; Chakraborty, P. B.; Byczuk, K.; Vollhardt, D.

2013-04-01

152

Thermodynamic properties and homogeneous nucleation of molecular clusters of nitrogen  

Microsoft Academic Search

A theoretical model for the dynamics of nitrogen microclusters, based on the assumed free rotation of Nâ molecules within a solid-like harmonic vibrating structure, is described. This approach allows the known morphology of rare-gas-type atomic clusters to be adopted to account for the statistical thermodynamics of nonpolar diatomic species with considerable simplification. As judged by the prediction of thermodynamic parameters

P. Pal; M. R. Hoare

1987-01-01

153

Phase equilibria, defect chemistry and semiconducting properties of CdTe(s) -- Thermodynamic modeling  

SciTech Connect

A thermodynamic analysis of the phase equilibria, defect chemistry, and semiconducting properties for CdTe(s) has been established on the basis of the compound energy model. Reported defect density data from a first-principles calculation have been used together with the experimentally measured phase diagram and carrier concentration data in the evaluation of thermodynamic model parameters. The excellent agreement between the various calculated and most of the experimental data indicates that a consistent thermodynamic description for the CdTe(s) phase has been obtained. This is a good illustration of how phase diagram calculations can be used in the refinement of first-principles calculations of defect formation energies.

Chen, Q.; Hillert, M.; Sundman, B. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Materials Science and Engineering; Oates, W.A. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforshung; Fries, S.G. [RWTH, Aachen (Germany). Lehrstuhl fuer Theoretische Huttenkunde; Schmid-Fetzer, R. [TU Clausthal, Clausthal-Zellerfeld (Germany). AG Elektronische Materialien

1998-08-01

154

Certain properties of an electrically insulated Coulomb plasma. Numerical simulation of microfields and thermodynamic properties. the problem of ball lightning  

Microsoft Academic Search

Many-body dynamics is used to study the (quasi-)steady state of a classical Coulomb plasma. The shortest relaxation time in such a plasma, for both the Debye screening and the thermodynamic properties, is the electron transit time over the average distance between ions. The steady-state energy of the Coulomb interaction of the particles and the steady-state potential near a fixed charge

S. A. Maiorov; A. N. Tkachev; S. I. Yakovlenko

1992-01-01

155

Thermodynamic properties and bulk viscosity near phase transition in the Z(2) and O(4) models  

SciTech Connect

We investigate the thermodynamic properties including equation of state, the trace anomaly, the sound velocity, and the specific heat, as well as transport properties like bulk viscosity in the Z(2) and O(4) models in the Hartree approximation of Cornwall-Jackiw-Tomboulis formalism. We study these properties in different cases, e.g. first-order phase transition, second-order phase transition, crossover and the case without phase transition, and discuss the correlation between the bulk viscosity and the thermodynamic properties of the system. We find that the bulk viscosity over entropy density ratio exhibits an upward cusp at the second-order phase transition, and a sharp peak at the first-order phase transition. However, this peak becomes smooth or disappears in the case of crossover. This result supports the idea that the bulk viscosity over entropy density ratio is a better quantity than the shear viscosity over entropy density ratio to locate the critical end point.

Li Baochun [Department of Physics, Shanxi University, Taiyuan, Shanxi 030006 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Huang Mei [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing 100049 (China)

2009-08-01

156

The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions  

NASA Astrophysics Data System (ADS)

In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

Shmelkov, Y.; Samujlov, E.

2013-04-01

157

First-principles determination of the structural, vibrational and thermodynamic properties of diamond, graphite, and derivatives  

Microsoft Academic Search

The structural, dynamical, and thermodynamic properties of diamond, graphite and layered derivatives (graphene, rhombohedral graphite) are computed using a combination of density-functional theory total-energy calculations and density-functional perturbation theory lattice dynamics in the generalized gradient approximation. Overall, very good agreement is found for the structural properties and phonon dispersions, with the exception of the c\\/a ratio in graphite and the

Nicolas Mounet; Nicola Marzari

2005-01-01

158

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

SciTech Connect

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

159

Thermodynamic properties of ionic fluids over wide ranges of temperature  

SciTech Connect

The principle of corresponding states is valid in reasonable approximation for ionic fluids but the quantitative behavior differs considerably from that for neutral-molecule fluids. The status of knowledge for various aqueous solutes is summarized. The critical region for an ionic system is difficult to treat theoretically and is out-of-range experimentally for simple substances such as NaCl. Current best approximations are discussed. A model, two-component ionic system with an experimentally convenient critical temperature has been found and its properties investigated. The role of long-range fluctuations on properties in the critical region is considered for ionic systems. Fused salts (without solvent) have low reduced temperatures and they follow corresponding states quite well as has been shown by Reiss and others. Fused salts have a remarkably large coefficient of expansion; its cause is discussed. At low reduced temperature an ionic-particle vapor is largely associated to neutral clusters - pairs, quarters, etc. An interesting system of considerable engineering and geological importance is NaCl in steam which has been treated in terms of successive hydration equilibria for the ion-pair.

Pitzer, K.S.

1986-07-01

160

Structure-property maps and optimal inversion in configurational thermodynamics  

SciTech Connect

Cluster expansions of first-principles density-functional databases in multicomponent systems are now used as a routine tool for the prediction of zero- and finite-temperature physical properties. The ability of producing large databases of various degrees of accuracy, i.e., high-throughput calculations, makes pertinent the analysis of error propagation during the inversion process. This is a very demanding task as both data and numerical noise have to be treated on equal footing. We have addressed this problem by using an analysis that combines the variational and evolutionary approaches to cluster expansions. Simulated databases were constructed ex professo to sample the configurational space in two different and complementary ways. These databases were in turn treated with different levels of both systematic and random numerical noise. The effects of the cross-validation level, size of the database, type of numerical imprecisions on the forecasting power of the expansions were extensively analyzed. We found that the size of the database is the most important parameter. Upon this analysis, we have determined criteria for selecting the optimal expansions, i.e., transferable expansions with constant forecasting power in the configurational space (a structure-property map). As a by-product, our study provides a detailed comparison between the variational cluster expansion and the genetic-algorithm approaches.

Arnold, Bjoern; Diaz Ortiz, Alejandro [Max Planck Institute for Metals Research, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Hart, Gus L. W. [Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602 (United States); Dosch, Helmut [DESY, Notkestrasse 85, D-22607 Hamburg (Germany)

2010-03-01

161

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

162

THERMODYNAMIC PROPERTIES OF FLUID FLOW ACROSS A MAGNETIC FIELD  

Microsoft Academic Search

The various thermodynamic quantities involved in the flow of a ; conducting fiuid in a uniform transverse magnetic field are studied. The analogs ; of Rayleigh and Fanno lines are readily derived from the basic equations. The ; internal energy and enthalpy of an electrically conducting fluid obeying perfect ; gas depends on its density and the strength of the

I. J. Singh; K. P. Chopra

1961-01-01

163

Thermodynamic Properties of Liquid Water to One Kilobar.  

National Technical Information Service (NTIS)

Recent accurate experimental P-v-t data for pure liquid water, in the range 0 to 1000 bars and 0 to 150C, are combined with other data at P = 1 atmosphere and on the saturation line, to get the thermodynamic functions for liquid water throughout this rang...

W. A. Walker

1967-01-01

164

Structural and thermodynamic properties of DNA uncover different evolutionary histories  

Microsoft Academic Search

We propose an index of DNA homogeneity (IDH) based on a binary distribution model that quantifies structural and thermodynamic aggregates present in DNA primary structures. Extensive analysis of sequence databases with the IDH uncovers significant constraints on DNA sequence other than those derived from codon usage or protein function. This index clearly distinguishes between organisms of different evolutive origins and

P. Miramontes; L. Medrano; C. Cerpa; R. Cedergren; G. Ferbeyre; G. Cocho

1995-01-01

165

Theoretical studies on the thermodynamic properties, densities, detonation properties, and pyrolysis mechanisms of trinitromethyl-substituted aminotetrazole compounds.  

PubMed

Trinitromethyl-substituted aminotetrazoles with -NH?, -NO?, -N?, and -NHC(NO?)? groups were investigated at the B3LYP/6-31G(d) level of density functional theory. Their sublimation enthalpies, thermodynamic properties, and heats of formation were calculated. The thermodynamic properties of these compounds increase with temperature as well as with the number of nitro groups attached to the tetrazole ring. In addition, the detonation velocities and detonation pressures of these compounds were successfully predicted using the Kamlet-Jacobs equations. It was found that these compounds exhibit good detonation properties, and that compound G (D = 9.2 km/s, P = 38.8 GPa) has the most powerful detonation properties, which are similar to those of the well-known explosive HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Finally, the electronic structures and bond dissociation energies of these compounds were calculated. The BDEs of their C-NO? bonds were found to range from 101.9 to 125.8 kJ/mol(-1). All of these results should provide useful fundamental information for the design of novel HEDMs. PMID:23420400

Lin, He; Chen, Peng-Yuan; Zhu, Shun-Guan; Zhang, Lin; Peng, Xin-Hua; Li, Kun; Li, Hong-Zhen

2013-02-19

166

From transport to disorder: Thermodynamic properties of finite dust clouds  

NASA Astrophysics Data System (ADS)

The quantities entropy and diffusion are measured for two- and three-dimensional (3D) dust clusters in the fluid state. Entropy and diffusion are predicted to be closely linked via unstable modes. The method of instantaneous normal modes is applied for various laser-heated clusters to determine these unstable modes and the corresponding diffusive properties. The configurational entropy is measured for 2D and 3D clusters from structural rearrangements. The entropy shows a threshold behavior at a critical temperature for the 2D clusters, allowing us to estimate a configurational melting temperature. Further, the entropic disorder increases for larger clusters. Finally, the predicted relation between entropy and unstable modes has been confirmed from our experiments for 2D systems, whereas 3D systems do not show such a clear correlation.

Schella, André; Mulsow, Matthias; Melzer, André; Schablinski, Jan; Block, Dietmar

2013-06-01

167

Thermodynamic scaling of dynamic properties of liquid crystals: Verifying the scaling parameters using a molecular model  

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

168

Using fundamental equations of state for calculating the thermodynamic properties of normal undecane  

NASA Astrophysics Data System (ADS)

The modern fundamental equations of state are analyzed together with methods of applying them for calculating the thermodynamic properties of technically important substances. Two kinds of fundamental equations of state (with 12 and 14 terms) are obtained for normal undecane ( n-undecane), which is a technically important organic working substance.

Aleksandrov, I. S.; Gerasimov, A. A.; Grigor'ev, B. A.

2011-08-01

169

Thermodynamic Properties of Hedenbergite, a Complex Silicate of Ca, Fe, Mn, and Mg.  

National Technical Information Service (NTIS)

This investigation of the thermodynamic properties of hedenbergite is one of a series being performed at the Bureau of Mines on slag-type pyroxenes, which include the pair acmite ((NaFe(+3)) (Si2O6)) and the nearly identical mineral aegirine. These pyroxe...

K. O. Bennington R. P. Beyer R. R. Brown

1984-01-01

170

Thermodynamic Properties of Ethylene from the Freezing Line to 450 K at Pressures to 260 MPa  

Microsoft Academic Search

A new fundamental equation explicit in Helmholtz energy for thermodynamic properties of ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. Independent equations for the vapor pressure for the saturated liquid and vapor densities as functions of temperature, and for the ideal gas heat capacity are also included. The fundamental equation was selected from

Majid Jahangiri; Richard T Jacobsen; Richard B. Stewart; Robert D. McCarty

1986-01-01

171

Calculations of the Thermodynamic Properties for Binary hcp Alloys with Simple Embedded Atom Method Model.  

National Technical Information Service (NTIS)

The simple embedded atom method model for hcp metals developed by Johnson has been applied to calculate the thermodynamic properties of all binary alloy systems for the eleven transition hcp metals. It has been shown that the agreement with the calculatio...

B. W. Zhang Y. Ouyang

1994-01-01

172

SIGNIGICANT STRUCTURES IN LIQUIDS. V. THERMODYNAMIC AND TRANSPORT PROPERTIES OF MOLTEN METALS  

Microsoft Academic Search

ABS>Thermodynamic properties calculated for molten metals by the method ; of significant structures of Eyring, Ree, and Hirai are presented. The ; application is discussed of the method of significant structures in predicting ; the viscosities and self-diffusion coefficients of moiten metals at various ; temperatures and pressures. Data are tabulated on sodium, mercury, copper, and ; lead. (C.H.);

C. M. Carlson; H. Eyring; T. Ree

1960-01-01

173

The relationship between thermodynamic and structural properties of low and high amylose maize starches  

Microsoft Academic Search

Maize starches with different amylose content were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It was shown that the differences in amylose content in maize starches resulted in changes in the structural and thermodynamic properties. The melting process of waxy and normal maize starches could be described by means of a “two-state” model. The melting process of

Y. I. Matveev; J. J. G van Soest; C. Nieman; L. A. Wasserman; V. A Protserov; M. Ezernitskaja; V. P. Yuryev

2001-01-01

174

Theory of nuclear spin interactions in ferromagnetic insulators. I. The thermodynamic properties  

Microsoft Academic Search

A field theoretical perturbation method is employed to investigate the low temperature thermodynamic properties of a ferromagnetic insulator in which there is a Heisenberg exchange interaction between neighbouring electronic spins and an additional hyperfine coupling between the nuclear and electronic spins. The calculations make use of the diagrammatic formalism of Vaks et al (1968), and the contributions are classified by

M. G. Cottam; M. J. Jones

1973-01-01

175

Mechanical properties of nanostructured, low temperature bainitic steel designed using a thermodynamic model  

Microsoft Academic Search

Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5GPa and high uniform elongation have been developed in the recent decade. To reduce the production cost of these steels, two chemical compositions were designed by using a thermodynamic model which was developed in Cambridge University by Bhadeshia. To attain optimum mechanical properties, the designed steels

M. N. Yoozbashi; S. Yazdani

2010-01-01

176

Molecular dynamics study of mechanical and thermodynamic properties of pentaerythritol tetranitrate  

Microsoft Academic Search

We present in this paper the results of molecular dynamics simulation based on a three-body potential, for mechanical and thermodynamic properties of pentaerythritol tetranitrate (PETN). Elastic constants and melting point obtained are in good agreement with available theoretical and experimental works. Various predictive quantities including longitudinal and transversal velocities, frequencies of the elastic wave, Debye temperature and heat capacity are

A. Zaoui; W Sekkal

2001-01-01

177

Thermodynamic properties of S=1 antiferromagnetic Heisenberg chains as Haldane systems  

Microsoft Academic Search

Thermodynamic properties of S=1 antiferromagnetic Heisenberg chains with free and periodic boundaries are investigated by a quantum Monte Carlo method. In particular, temperature dependences of the specific heat, the magnetic susceptibility, and the hidden order parameter, which are inherent to the Haldane phase, are investigated. The specific heat turns out to have a peak at a temperature Tpeak~2Delta, where Delta

Shoji Yamamoto; Seiji Miyashita

1993-01-01

178

Thermodynamic Properties of the Binary Laves Phase Compounds of Plutonium with the Group Viiia Metals.  

National Technical Information Service (NTIS)

The thermodynamic properties of PuFe sub 2 , PuRu sub 2 and PuOs sub 2 were determined using fused salt emf cells. The data indicate that there is a regular correlation between the stability of these AB sub 2 Laves type compounds and their unalloyed atomi...

G. M. Campbell

1975-01-01

179

Thermodynamic Properties of Aqueous Lithium Bromide Using a Multiproperty Free Energy Correlation  

Microsoft Academic Search

A new correlation of the thermodynamic properties of aqueous lithium bromide was constructed based on a Gibbs free energy fundamental function. The coefficients of the function were calculated using a multiproperty curve fit to vapor pressure, specific heat, and volumetric data. The specific heat data used are new experimental values obtained in our laboratory and described in a companion paper.

Zhe Yuan; Keith E. Herold

2005-01-01

180

Thermodynamic Properties of Poly(2,6-Dimethyl-1,4-Phenylene Ether).  

National Technical Information Service (NTIS)

The thermodynamic properties of crystalline and amorphous poly(2,6-dimethyl-1,4-phenylene ether) were studied calorimetrically between 80 and 570 deg./K. The calculated configurational entropy of this polymer, of similar magnitude to other glass-forming l...

F. E. Karasz H. E. Bair J. M. O'Reilly

1967-01-01

181

Thermodynamic and structural properties of a fluid with a rectangular well potential  

Microsoft Academic Search

Thermodynamic and structural properties of a system with a rectangular well potential are investigated in the supercritical region using the approximate Martynov-Sarkisov (MS) integral equation for the binary distribution function. It is shown that, in contrast to other approximations, in particular the Percus-Yevick equation (PY) and hypernetted chain approximation (HNC), the MS equation describes the limits of existence of the

G. N. Sarkisov; D. A. Tikhonov; D. Malinskii; Yu. Magarshak

1993-01-01

182

Thermodynamic properties of several soil- and sediment-derived natural organic materials  

Microsoft Academic Search

Improved understanding of the structure of soil- and sediment-derived organic matter is critical to elucidating the mechanisms that control the reactivity and transport of contaminants in the environment. This work focuses on an experimental investigation of thermodynamic properties that are a function of the macromolecular structure of natural organic matter (NOM). A suite of thermal analysis instruments were employed to

Rossane C. DeLapp; Eugene J. LeBoeuf; Katherine D. Bell

2004-01-01

183

Simulations of the structure and thermodynamic properties of water at high pressures and temperatures  

Microsoft Academic Search

Molecular dynamics simulations of water properties over a wide pressure temperature range were performed using a realistic intermolecular potential (TIP4P) and a wide range of densities. An equation of state developed for water at pressures from 10 to 300 kbar is presented together with structural and other thermodynamic results. Comparisons of the PVT predictions of TIP4P to the experimental data

John Brodholt; Bernard Wood

1993-01-01

184

The Problem of Counting the Number of Molecules and Calculating Thermodynamic Properties.  

ERIC Educational Resources Information Center

|Presents an experimental approach to illustrate that the thermodynamic properties of a system can be considered as the average of mechanical variables. Discusses the Knudsen effusion method to count the number of molecules, vapor pressure, the piezoelectric effect, the experimental setup, and sample experimental results. (JRH)|

Torres, Luis Alfonso; And Others

1995-01-01

185

Prediction of some thermodynamic properties of selected compounds of element 104  

Microsoft Academic Search

A set of parameterized equations has been published by Bratsch and Lagowski for calculating thermodynamic properties of the lanthanides, actinides, element 104, and certain related elements. Since these equations were applied to element 104, new values for the first four ionization energies and radii of the ions of charge +1, +2, +3, and +4 have been calculated for this element.

Elijah Johnson; B. Fricke

1991-01-01

186

Thermodynamic Properties of Ir2S3 and IrS2.  

National Technical Information Service (NTIS)

Thermodynamic properties of Ir2S3 have been obtained from the equilibrium pressures of S2(g) measured by the effusion technique in the range of 920 to 1110 K. The standard Gibbs energy change at these temperatures for 2 Ir(s)+1.5 S2(g) = Ir2S3(s) was foun...

E. T. Chang N. A. Gokcen

1972-01-01

187

APPROXIMATIONS FOR THE THERMODYNAMIC AND TRANSPORT PROPERTIES OF HIGH TEMPERATURE AIR  

Microsoft Academic Search

Approximations are presented for the thermodynamic and transpont ; properties of high-temperature air. Compressibility, enthalpy, entropy, specific ; heats, speed of sound, coefficients of viscosity and thermal conductivity, and ; the Prandtl number are tabulated for 500 to 15,000 deg K over a range of ; pressures from 0.0001 to 100 atm. (auth)

1959-01-01

188

Thermodynamic properties of nuclear matter with three-body forces  

SciTech Connect

We calculate thermodynamic quantities in symmetric nuclear matter within the self-consistent Green's functions method including three-body forces. The thermodynamic potential is computed directly from a diagrammatic expansion, implemented with the CD-Bonn and Nijmegen nucleon-nucleon potentials and the Urbana three-body forces. We present results for entropy and pressure up to temperatures of 20 MeV and densities of 0.32 fm{sup -3}. While the pressure is sensitive to the inclusion of three-body forces, the entropy is not. The unstable spinodal region is identified and the critical temperature associated to the liquid-gas phase transition is determined. When three-body forces are added we find a strong reduction of the critical temperature, obtaining T{sub c}{approx_equal}12 MeV.

Soma, V. [Institute of Nuclear Physics PAN, PL-31-342 Krakow (Poland); Bozek, P. [Institute of Physics, Rzeszow University, PL-35-959 Rzeszow (Poland); Institute of Nuclear Physics PAN, PL-31-342 Krakow (Poland)

2009-08-15

189

Thermodynamic properties and phase stability of wadsleyite II  

NASA Astrophysics Data System (ADS)

The thermodynamical stability of a newly observed wadsleyite II phase in the Mg2SiO4 system is studied by the density functional theory. The wadsleyite II equation of state has been derived. The phase boundaries of Mg2SiO4 polymorphs: wadsleyite, wadsleyite II and ringwoodite are studied using the quasi-harmonic approximation at high external pressures. Clapeyron slopes determined for wadsleyite II-ringwoodite and wadsleyite-wadsleyite II boundaries are 0.0047 and 0.0058 GPa/K, respectively. It is shown that the wadsleyite II phase is not thermodynamically preferred in the pure Mg2SiO4 system and will probably not occur between wadsleyite and ringwoodite phases.

Tokár, Kamil; Jochym, Pawe? T.; Piekarz, Przemys?aw; ?a?ewski, Jan; Sternik, Ma?gorzata; Parlinski, Krzysztof

2013-03-01

190

Thermodynamic critical and geometrical properties of charged BTZ black hole  

SciTech Connect

The heat capacities and the electric capacitances of charged Banados-Teitelboim-Zanelli (BTZ) black hole are first calculated. By using the equilibrium fluctuation theory of thermodynamics the second-order moments in three different ensembles are obtained, and it is found that in the microcanonical ensemble the extremal charged BTZ black hole is a critical point of the second-order phase transition. The critical exponents associated with some response coefficients satisfy the scaling law of the first kind and the effective spatial dimension is determined to be one from the scaling law of the second kind. The Ricci curvature scalar associated with the Ruppeiner thermodynamic metric is calculated, which suggests also that the effective spatial dimension of the charged BTZ black hole is one.

Wei Yihuan [Department of Physics, Bohai University, Jinzhou 121000, Liaoning (China)

2009-07-15

191

The polynomial representation of thermodynamic properties in dilute solutions  

Microsoft Academic Search

Attempts to extend the interaction parameter formalism to higher-order polynomials and to render it thermodynamically consistent\\u000a at finite solute concentrations have resulted in much confusion. The literature is reviewed with a view to clarifying the\\u000a issues. The problem is best and most simply resolved through extension of the quadratic formalism, which has a sound theoretical\\u000a foundation. A new and general

Arthur D. Pelton

1997-01-01

192

Low-Temperature Thermodynamic Properties of Vanadium. II. Mixed State  

Microsoft Academic Search

The specific heat of a single-crystal vanadium sample (resistivity ratio=140) has been measured in 12 different magnetic fields between 0.5 and 5.4°K to study the mixed state. The specific heat above approximately Hc is found to be independent of sample history, which leads to a complete thermodynamic description of the mixed state. The upper critical field Hc2(t) is found from

Ray Radebaugh; P. H. Keesom

1966-01-01

193

Thermodynamic properties of uranium in Ga–In based alloys  

NASA Astrophysics Data System (ADS)

Activity of uranium was determined in gallium, indium and gallium–indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U–Ga–In alloys, uranium forms the intermetallic compound UGa3. Activity coefficients and solubility of uranium in Ga–In eutectic were also determined in the same temperature range. Partial thermodynamic functions of ?-U in saturated alloys with gallium, indium and Ga–In eutectic were calculated.

Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Melchakov, S. Yu; Shchetinskiy, A. V.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-07-01

194

Thermodynamic properties of the itinerant-boson ferromagnet  

SciTech Connect

Thermodynamics of a spin-1 Bose gas with ferromagnetic interactions is investigated via the mean-field theory. It is apparently shown in the specific-heat curve that the system undergoes two phase transitions, the ferromagnetic transition and Bose-Einstein condensation, with the Curie point above the condensation temperature. Above the Curie point, the susceptibility fits the Curie-Weiss law perfectly. At a fixed temperature, the reciprocal susceptibility is also in a good linear relationship with the ferromagnetic interaction.

Tao Chengjun; Wang Peilin; Qin Jihong; Gu Qiang [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China)

2008-10-01

195

Transport properties of high temperature air in local thermodynamic equilibrium  

Microsoft Academic Search

:   In the paper new calculated transport coefficients of air in the temperature range 50-100 000 K are presented. The results\\u000a have been obtained by means of the perturbative Chapman-Enskog method, assuming that the plasma is in local thermodynamic\\u000a equilibrium (LTE). The calculations include viscosity, thermal conductivity, electric conductivity and multicomponent diffusion\\u000a coefficients. For the calculation, a recent compilation of

M. Capitelli; G. Colonna; C. Gorse

2000-01-01

196

Au-Cu Ordered Intermetallic Compounds: Structure, Thermodynamics and Mechanical Properties  

NASA Astrophysics Data System (ADS)

Structure, thermodynamics and mechanical properties of ordered bimetalic Au-Cu compounds AuCu_3, AuCu(I), AuCu(II) and Au_3Cu studied at elevated temperatures. For comparison simulations are also carried for pure copper, gold and their random solid solutions at the same concentrations as the ordered compounds. The volumetric and structural properties are studied upto 700 K for ordered compounds and upto melting for pure metals and random solid solutions. But, mechanical properties (elastic constants) are only calculated at room temperature and below the disorder-order transition (600 K)

Cagin, Tahir; Kimura, Yoshitaka; Li, Hao; Goddard, William A.

1997-03-01

197

Thermodynamic properties and phase equilibria for Pt-Rh alloys  

SciTech Connect

The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1,300 K using the solid-state cell Pt-Rh, Rh + Rh{sub 2}O{sub 3}/(Y{sub 2}O{sub 3})ZrO{sub 2}/Pt{sub 1{minus}x}Rh{sub x} + Rh{sub 2}O{sub 3}, Pt-Rh. The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult`s law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, {Delta}H = X{sub Rh} (1 {minus} X{sub Rh})[{minus}10,970 + 45X{sub Rh}] J/mol, {Delta}S{sup E} = X{sub Rh} (1 {minus} X{sub Rh})[{minus}3.80 + 1.55 {times} 10{sup {minus}2} X{sub Rh}] J/mol{center_dot}K. The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.

Jacob, K.T.; Priya, S. [Indian Inst. of Science, Bangalore (India). Dept. of Metallurgy; Waseda, Yoshio [Tohoku Univ., Sendai (Japan). Inst. for Advanced Materials Processing

1998-06-01

198

A Table of Miscellaneous Thermodynamic Properties for Various Substances with Emphasis on the Critical Properties.  

National Technical Information Service (NTIS)

Properties cited include: molecular weight, triple temperature in Kelvin, normal boiling point in Kelvin, critical temperature in Kelvin, triple pressure in bars, Critical pressure in bars, critical specific volume in cm/g, Z sub C = p sub c v sub c/RT su...

D. Rathmann J. Bauer P. A. Thompson

1978-01-01

199

Computing thermodynamic and transport properties of room temperature ionic liquids and molten salts from atomistic simulations  

NASA Astrophysics Data System (ADS)

Ionic liquids and molten salts are being considered for many novel applications including for use as heat transfer fluids in thermal energy generation cycles. Thermodynamic and transport properties like melting points, heat capacities, viscosities and thermal conductvities were computed for some ionic liquids and molten salts. Melting points were computed using a novel thermodynamic integration-based procedure. Apart from computing melting points, relative thermodynamic stabilities of crystal polymorphs can be obtained using this method. The melting point and the relative stabilities of two polymorphs of the ionic liquid 1-n-butyl-3-methylimidazolium chloride were computed and were found to be comparable to experimental data. Melting points were computed for lithium, sodium and potassium nitrate salts, which are being considered as candidates for heat transfer media in solar thermal applications. Viscosities, thermal conductivities and heat capacities were also computed for these salts. The numbers were comparable to experimental data. The difference between the experimentally determined properties, and the values obtained from simulations can be attributed to the parameterization of the force field model used for these salts. In addition to pure component properties, transport properties such as self-diffusivities, viscosities and thermal conductivities were computed for ionic liquid and alkali nitrate salt mixtures. Various mixing rules were fit to these properties. The results of these studies suggest that accurate melting points are a sensitive test of force field accuracy. Also, powerful molecular simulation methods are capable of computing properties useful in the design of fluids targeting a particular application. In addition, the thermodynamic integration-based procedure is modified to compute solid phase free energies which is used to calculate solubilities of solids in liquids. Enthalpies of vaporization of ionic liquids were also computed and this data will be used to verify vaporization enthalpies measured experimentally.

Jayaraman, Saivenkataraman

200

Thermodynamic properties of zeolites: low-temperature heat capacities and thermodynamic functions for phillipsite and clinoptilolite. Estimates of the thermochemical properties of zeolitic water at low temperature  

Microsoft Academic Search

The heat capacities of phillipsite and clinoptilolite have been measured between l5 and 305 K. Smoothed values of the thermodynamic properties, heat capacity, entropy, enthalpy function and Gibbs energy function have been calculated from the measured heat capacities for the phillipsite composition (Na1 ssKsro)Alr$Sio.rzOr6'6H2O and for the clinoptilolite composition (NaosoKoe6Cal 56Mg1 zr)(Alo.zFeo.:)Si?eo?2 . 22H2O. At 298.15 K,Slsn - Sfi is

Bnuce S. HeurNcwAy; RrcHRno A. Roerr

201

Thermodynamic properties of some metal oxide-zirconia systems  

SciTech Connect

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, N.S.

1989-12-01

202

A calorimetric study of the thermodynamic properties of potassium molybdate  

NASA Astrophysics Data System (ADS)

The low-temperature heat capacity of K2MoO4 was measured by adiabatic calorimetry. The smoothed heat capacity values, entropies, reduced Gibbs energies, and enthalpies were calculated over the temperature range 0-330 K. The standard thermodynamic functions determined at 298.15 K were C {/p °} (298.15 K) = 143.1 ± 0.2 J/(mol K), S°(298.15 K) = 199.3 ± 0.4 J/(mol K), H°(298.15 K)- H°(0) = 28.41 ± 0.03 kJ/mol, and ?°(298.15 K) = 104.0 ± 0.4 J/(mol K). The thermal behavior of potassium molybdate at elevated temperatures was studied by differential scanning calorimetry. The parameters of polymorphic transitions and fusion of potassium molybdate were determined.

Gavrichev, K. S.; Ryumin, M. A.; Tyurin, A. V.; Gurevich, V. M.; Komissarova, L. N.; Khoroshilov, A. V.; Sharpataya, G. A.

2009-03-01

203

Thermodynamic properties of mesoscale convective systems observed during BAMEX  

SciTech Connect

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

204

A flower-like Ising model. Thermodynamic properties  

NASA Astrophysics Data System (ADS)

We consider a flower-like Ising model, in which there are some additional bonds (in the “flower-core”) compared to a pure Ising chain. To understand the behaviour of this system and particularly the competition between ferromagnetic (usual) bonds along the chain and antiferromagnetic (additional) bonds across the chain, we study analytically and iteratively the main thermodynamic quantities. Very interesting is, in the zero-field and zero-temperature limit, the behaviour of the magnetization and the susceptibility, closely related to the ground state configurations and their degeneracies. This degeneracy explains the existence of non-zero entropy at zero temperature, in our results. Also, this model could be useful for the experimental investigations in studying the saturation curves for the enzyme kinetics or the melting curves for DNA-denaturation in some flower-like configurations.

Mejdani, R.; Ifti, M.

1995-03-01

205

Estimation of thermodynamic properties of alloys from phase diagram and other loose boundary conditions  

NASA Astrophysics Data System (ADS)

A set of computer programs has been made, which is used to predict thermodynamic properties of an alloy system from phase diagram and other loose boundary conditions. Loose boundary conditions include fragmentary thermodynamic data and predictions based on several empirical or theoretical hypotheses. In program TOHSG, m equations with n (m greater than n) unknowns which are parameters concerning atomic interactions are assembled from the equilibria collected on experimental phase diagram, and also from the loose boundary conditions. Then, the unknowns are obtained as Chebyshev solutions. Thermodynamic properties of the alloys are also calculated. In order to test their validity, the parameters are then fed into the other two programs TOGAP and TOCOMP, which calculate the phase diagram. The set of programs can: (1) generate a working data set of a system whose thermodynamic properties are unknown, and (2) test various hypotheses against experimental data such as phase diagrams. As an example of application, U-Zr system has been analyzed. Source list of TOHSG and input/output guides are attached.

Ogawa, Toru; Iwai, Takashi

1989-05-01

206

Predicting the thermodynamic properties of gold nanoparticles using different force fields  

NASA Astrophysics Data System (ADS)

The objective of this research was to learn how to predict the thermodynamic properties of gold nanoparticles using computational tools. The lowest energy structures of gold nanoparticles of various sizes were determined and thermodynamic properties such as the free energy (F), internal energy (U), entropy (S), and specific heat (Cv) of the gold nanoparticles were investigated using a fully-atomistic Monte Carlo simulation method that utilizes a modified Wang-Landau algorithm. Eight well-known force fields for metallic systems were employed to model gold nanoparticles: the Lennard-Jones potential (LJ), the Lennard-Jones potential with Heinz's parameterization (LJH), the Gupta potential, the Sutton-Chen potential (SC), the Sutton-Chen potential with Pawluk's parameterization for small clusters (SCP), the Quantum Sutton-Chen potential (Q-SC), the Embedded Atom Method (EAM) by Cai and Ye, and the empirical potential for gold proposed by Olivier and coworkers (POT). Subsequently, we explored the accuracy of each force field in the description of the thermodynamic behavior of gold nanoparticles. The thermodynamic properties of gold nanoparticles were computed from the Density of States which was obtained as a result of the Monte Carlo simulation. Afterwards, the melting point of gold nanoparticles was determined from the behavior of the calculated thermodynamic properties and was compared with theory, experimental observations and other simulation results. The force fields employed predicted melting points of gold nanoparticles over a wide range of temperatures. A thorough comparison with the available experimental observations showed that the Quantum Sutton-Chen potential (Q-SC) correctly described the melting behavior of gold nanoparticles with sizes smaller than 1.3 nanometers.

Park, Yongjin

207

Ab initio investigation on the elastic, dynamical and thermodynamic properties of LiCl  

NASA Astrophysics Data System (ADS)

The present work reports a study of the structural, elastic, dynamical and thermodynamic properties of rock salt (RS) LiCl within density functional theory. It is found that the lattice constant and elastic constants are in very good agreement with the other calculations or experimental values. The phonon dispersion curve along several high symmetry lines at the Brillouin zone (BZ) is determined using density functional perturbation theory (DFPT), and the phonon frequencies at the ? point of the Brillouin zone are in reasonable agreement with previous calculations and experimental values. We also calculate the thermodynamic functions based on phonon density of states.

Hou, H. J.; Kong, F. J.; Yang, J. W.; Wan, S. Q.; Yang, S. X.

2013-11-01

208

Thermodynamic and catalytic properties of solid solutions of copper and zinc oxides  

SciTech Connect

The central problem in the estimation of the thermodynamic data characterizing of solid phase is associated with the consideration of the parameters of fine crystal structure, chemical and phase composition. The analysis of thermodynamic and catalytic properties of the specimens based on copper and zinc oxides was performed in relation to the CuO/ZnO ratio with the aim to determine the solid solution stability, to estimate the energy of rearranging the nearest neighbor structure and the energy conditioned by the microcrystallinity and the defectiveness of the crystal state.

Smirnov, N.N.; Shirokov, Yu.G.; Artamonov, A.V.; Il`in, A.P.

1995-10-20

209

Linearized Tensor Renormalization Group Algorithm for the Calculation of Thermodynamic Properties of Quantum Lattice Models  

NASA Astrophysics Data System (ADS)

A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic quantities of the quantum XY spin chain as well as the Heisenberg antiferromagnet on a honeycomb lattice are calculated by the linearized tensor renormalization group method, showing the pronounced precision and high efficiency.

Li, Wei; Ran, Shi-Ju; Gong, Shou-Shu; Zhao, Yang; Xi, Bin; Ye, Fei; Su, Gang

2011-03-01

210

Linearized tensor renormalization group algorithm for the calculation of thermodynamic properties of quantum lattice models.  

PubMed

A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic quantities of the quantum XY spin chain as well as the Heisenberg antiferromagnet on a honeycomb lattice are calculated by the linearized tensor renormalization group method, showing the pronounced precision and high efficiency. PMID:21517348

Li, Wei; Ran, Shi-Ju; Gong, Shou-Shu; Zhao, Yang; Xi, Bin; Ye, Fei; Su, Gang

2011-03-22

211

Calculation of the thermodynamic properties of gas and liquid solutions - Mixtures of complex substances  

NASA Astrophysics Data System (ADS)

Reference is made to a previous study (Kessel'man et al., 1986) in which a method has been proposed for calculating the thermodynamic properties of gas and liquid solutions in the one- and two-phase regions on the basis of a unified equation of state. Here, by using an effective intermolecular potential with temperature-dependent parameters, this method is extended to the calculation of the thermodynamic parameters of mixtures with complex components. Results are presented for a number of mixtures, including Ar+CO2, Ar+N2, N2+CH4, N2C2C6, CH4+CO2, and CH4+C4H10.

Kessel'Man, P. M.; Tkachenko, V. V.; Ugol'Nikov, A. P.

1987-12-01

212

Thermodynamic properties by non-calorimetric methods. Progress report, August 1, 1988--July 31, 1989  

SciTech Connect

This three year research program provides a valuable complement to the experimental programs currently in progress at NIPER for the Advanced Research and Technology Development (AR and TD) and Advanced Exploration and Process Technology (AEPT) divisions of the Department of Energy. These experimental programs are focused on the calorimetric determination of thermodynamic properties of key polynuclear heteroatom-containing aromatic molecules. This project for the Office of Energy Research focuses on the non-calorimetric determination of thermodynamic properties through the extension of existing correlation methodologies and through molecular spectroscopy with statistical mechanics. The paper discusses progress in three areas: (1) Improvement of thermochemical and thermophysical property predictions via enhancement of group-contribution methods using two approaches, namely, development and improvement of group-contribution parameters via correlations involving the expanded modern thermodynamics data base and development of group-contribution parameters via molecular spectroscopy and statistical mechanics of key monocyclic organic compounds; (2) Molecular spectroscopy and statistical mechanics: equipment development and developments in interpretation and assignment of spectra; and (3) Thermophysical property correlations.

Steele, W.V.; Chirico, R.D.; Collier, W.B.; Strube, M.M. [IIT Research Inst., Chicago, IL (United States)]|[National Inst. for Petroleum and Energy Bartlesville, OK (United States)

1989-12-31

213

Thermodynamics properties of copper-oxide superconductors described by an Ising frustrated model  

NASA Astrophysics Data System (ADS)

In this work we will study the thermodynamics properties of the quenched decorated Ising model with competitive interactions through the effective field theory (EFT) of a one-spin cluster. This model is used here to describe the thermodynamics properties of the cooper-based oxide superconductors compounds in its insulating phase (antiferromagnetic). The model consists of planes in which the nodal spins interact antiferromagnetically (JA<0) with their nearest-neighbors and ferromagnetically (JF>0) with the spins that decorated the bonds, which are quenched randomly distributed over the two-dimensional lattice. The planes interact antiferromagnetically with weak exchange interaction (i.e., JA?=?JA, ?=10-5). By using the framework of an effective-field theory, based on the differential operator technique, we discuss beyond thermodynamics properties the antiferromagnetic-phase stability limit in the temperature-decorated bond concentration space (T×p), for ?=10-5 and various values of frustration parameter (?=JA/JF), magnetic field (H) and concentration parameter (p). For certain range of the parameter ? we observe a reentrant behavior in low-temperature that it reflects in the properties behavior itself.

Padilha, Igor T.; de Sousa, J. Ricardo; Neto, Minos A.; Salmon, Octavio R.; Viana, J. R.

2013-10-01

214

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

215

Characterisation of the surface thermodynamic properties of cement components by inverse gas chromatography at infinite dilution  

SciTech Connect

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

216

Thermodynamic Properties of Asphaltenes: A Predictive Approach Based On Computer Assisted Structure Elucidation and Atomistic Simulations  

SciTech Connect

The authors describe a new methodology for predicting the thermodynamic properties of petroleum geomacromolecules (asphaltenes and resins). This methodology combines computer assisted structure elucidation (CASE) with atomistic simulations (molecular mechanics and molecular dynamics and statistical mechanics). They use quantitative and qualitative structural data as input to a CASE program (SIGNATURE) to generate a sample of ten asphaltene model structures for a Saudi crude oil (Arab Berri). MM calculations and MD simulations are used to estimate selected volumetric and thermal properties of the model structures.

Diallo, Mamadou S.; Cagin, Tahir; Faulon, Jean Loup; Goddard, William A.

2000-08-01

217

Calculation of the thermodynamic properties of gas and liquid solutions - Multicomponent mixtures  

NASA Astrophysics Data System (ADS)

A method for calculating thermodynamic properties using a unified equation of state for gases and liquids in combination with an effective intermolecular potential is extended to multicomponent systems. A comparison with experimental data indicates that, for a sufficiently large number of components, the properties of mixtures can be calculated from data on the pure components only. Results of calculations for several mixtures, including Ar-N2, Ar-CH4, N2-CH4, Ar-N2-CH4, and H2-N2-CO2-CO-CH4, are presented and compared with experimental data.

Kessel'Man, P. M.; Tkachenko, V. V.; Ugol'Nikov, A. P.

1989-08-01

218

Thermodynamic properties and static structure factor for a Yukawa fluid in the mean spherical approximation.  

PubMed

This work presents the full analytic expressions for the thermodynamic properties and the static structure factor for a hard sphere plus 1-Yukawa fluid within the mean spherical approximation. To obtain these properties of the fluid type Yukawa analytically it was necessary to solve an equation of fourth order for the scaling parameter on a large scale. The physical root of this equation was determined by imposing physical conditions. The results of this work are obtained from seminal papers of Blum and Høye. We show that is not necessary the use the series expansion to solve the equation for the scaling parameter. We applied our theoretical result to find the thermodynamic and the static structure factor for krypton. Our results are in good agreement with those obtained in an experimental form or by simulation using the Monte Carlo method. PMID:22179758

Montes-Perez, J; Cruz-Vera, A; Herrera, J N

2011-12-18

219

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

PubMed Central

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.

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

2011-01-01

220

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

PubMed

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

2011-10-20

221

Experimental study and modeling of the thermodynamic properties of Cu-Fe-Ni melts  

NASA Astrophysics Data System (ADS)

The partial mixing enthalpy of nickel in ternary liquid Cu-Fe-Ni alloys is studied at 1873 K along sections characterized by ratios x Cu: x Fe = 3, 1, and 1/3 at x Ni = 0-0.55. The investigations are undertaken using a high-temperature isoperibolic calorimeter. The temperature and composition dependence of the excess mixing Gibbs energy of liquid Cu-Fe-Ni alloys are described in terms of the Muggianu-Redlich-Kister model using the data obtained, the literature data on the activities of liquid alloy components, and the thermodynamic properties of melts of the boundary binary systems. This model is used to calculate isotherms of the thermodynamic properties of the liquid alloys over the entire composition range. The contribution of a ternary interaction to the integral mixing enthalpy of liquid Cu-Fe-Ni alloys is found to be mainly positive.

Dreval', L. A.; Abdulov, A. R.; Agraval, P. G.; Turchanin, M. A.

2010-01-01

222

Thermodynamic properties of two-component cold Fermi gases with bound states  

NASA Astrophysics Data System (ADS)

We address the thermodynamics of a two-component cold Fermi gas with short-range interaction. In the BEC region of the BCS-BEC crossover the fermionic particles form bosonic dimers as the two-particle bound states. We focus on the fermionic properties of the particles which constitute the dimers. To this end, we use the Lee-Yang quantum cluster expansion method, which enables us to expand the logarithm of the grand partition function in a power series of fugacity. By calculating the fourth-order contribution in fugacity we elucidate how the thermodynamic properties are affected by the quantum-statistical exchange effect between two fermionic particles that belong to different bosonic dimers. Furthermore, we extend the method to take into account the effect of the monomer-dimer and dimer-dimer scatterings and discuss the corresponding scattering length.

Sakumichi, Naoyuki; Kawakami, Norio; Ueda, Masahito

2010-03-01

223

Ebulliometers for measuring the thermodynamic properties of fluids and fluid mixtures  

SciTech Connect

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

224

Viscosity and thermodynamic properties of QGP in relativistic heavy-ion collisions  

Microsoft Academic Search

We study the viscosity and thermodynamic properties of QGP at RHIC by employing the recently extracted equilibrium distribution\\u000a functions from two hot QCD equations of state of O(g\\u000a 5) and O(g\\u000a 6ln?(1\\/g)), respectively. After obtaining the temperature dependence of the energy density and the entropy density, we focus our attention\\u000a on the determination of the shear viscosity for a rapidly

Vinod Chandraaand; V. Ravishankar

2009-01-01

225

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

PubMed

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

2010-11-22

226

Thermodynamical properties and Coulomb instabilities in hot nuclear systems with the Gogny interaction  

NASA Astrophysics Data System (ADS)

The thermodynamical properties and Coulomb instability in hot nuclear system with Gogny interactions are studied by using the finite-temperature real-time Green's function method. The isotherms, critical temperature, limiting temperature, saturation density, and isothermal incompressibility for various temperatures and different asymmetric parameters are calculated. To illustrate the importance of the finite-range part and density-dependence part of the interaction, we have compared our results with that given by the Skyrme interaction and Brink-Boeker interaction.

Zhang, Yi-Jun; Su, Ru-Keng; Song, Hongqiu; Lin, Fu-Min

1996-09-01

227

Thermodynamics of Polynuclear Aromatic Molecules: II. Low-Temperature Thermal Properties of Perylene, Coronene, and Naphthacene  

Microsoft Academic Search

The heat capacities of crystalline coronene and naphthacene have been determined by adiabatic calorimetry from 5 to 350 K; that of perylene was likewise measured from 5 K into the liquid phase (578 K). Values at 298.15 K of the thermodynamic properties\\/calth K mol are: The enthalpy of fusion for perylene is 7618 calth mol at the triple-point temperature, 550.9

Wen-Kuei Wong; Edgar F. westrum Jr

1980-01-01

228

Thermodynamic properties of gold–water nanolayer mixtures using molecular dynamics  

Microsoft Academic Search

The physical behavior of a fluid in contact with solid layers is still not fully understood. The present work focuses on the\\u000a study and understanding of thermodynamic and structural properties of gold–water nanolayer mixtures using molecular dynamics\\u000a simulations. Two different systems are considered, where approximately 1,700 water molecules are confined between gold nanolayers\\u000a with separations of 7.4 and 6.2 nm, respectively.

Gianluca Puliti; Samuel Paolucci; Mihir Sen

229

Grüneisen gamma and other thermodynamic properties of cesium halide crystals at zero and elevated pressures  

Microsoft Academic Search

The quasiharmonic approximation is used to calculate the Helmholtz free energy F. The interionic forces are represented by a deformation-dipole model, which is parameterized self-consistently. We give parameterized expressions for F that can be used to predict the temperature and volume dependence of the thermodynamic properties of CsCl, CsBr, and CsI. These expressions for F are tested by comparing our

Sudhir Bijanki; Robert J. Hardy

1978-01-01

230

Equations of state for the thermodynamic properties of R32 (difluoromethane) and R125 (pentafluoroethane)  

Microsoft Academic Search

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

231

Prediction of the thermodynamic properties of complex polyatomic hydrogen bonding fluids  

SciTech Connect

A new theory for intramolecular hydrogen bonding of flexible hard chain molecules in the absence of intermolecular association is presented. The theory predicts the change in thermodynamic properties due to intramolecular association and the fraction of nonbonded chains. Comparisons with molecular simulation results are presented to demonstrate the accuracy of the theory. By considering the limit of complete association, an accurate equation of state of cyclic molecules is obtained.

Ghonasgi, D.; Perez, V.; Chapman, W.G. [Rice Univ., Houston, TX (United States)

1995-05-01

232

Thermodynamical properties of La–Ni–T (T = Mg, Bi and Sb) hydrogen storage systems  

Microsoft Academic Search

The hydrogen absorption properties of LaNi4.8T0.2 (T=Mg, Bi and Sb) alloys are reported. The effects of the substitution of Ni in the LaNi5 compound with Mg, Bi and Sb are investigated. The ability of alloys to absorb hydrogen is characterized by the pressure–composition (p–c) isotherms. The p–c isotherms allow the determining thermodynamic parameters enthalpy (?Hdes) and entropy (?Sdes) of the

K. Giza; W. Iwasieczko; V. V. Pavlyuk; H. Bala; H. Drulis

2008-01-01

233

Quartz: heat capacities from 340 to 1000 K and revised values for the thermodynamic properties.  

USGS Publications Warehouse

New heat-capacity data for quartz have been measured over the T interval 340-1000 K by differential scanning calorimetry. The data were combined with recent heat-content and heat-capacity data to provide a significantly revised set of thermodynamic properties for alpha -quartz and to resolve the problem of disparate heat-content and heat-capacity data for alpha - and beta -quartz.-J.A.Z.

Hemingway, B. S.

1987-01-01

234

Standard thermodynamic properties and heat capacity equations of rare earth hydroxides  

Microsoft Academic Search

Standard thermodynamic properties at 298.15 K, 1 bar for the solid hydroxides of Y, Ce(III), Pr, Sm, Eu(III), Gd, Tb, Dy, Ho, Er, Tm and Yb were calculated from thermochemical data available in the literature. `3Rn' heat capacity equations [Fei, Y., Saxena, S.K., 1987. An equation for the heat capacity of solids. Geochim. Cosmochim. Acta 51, 251–254.] were generated for

I. I Diakonov; K. V Ragnarsdottir; B. R Tagirov

1998-01-01

235

Thermodynamic properties and stoichiometry of As (III) hydroxide complexes at hydrothermal conditions  

Microsoft Academic Search

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

236

Structural and thermodynamic properties of end-grafted polymers on curved surfaces  

Microsoft Academic Search

Conformational and thermodynamic properties of polymer chains end-grafted to cylindrical and spherical surfaces under good solvent conditions have been studied using the single-chain mean-field theory. We have considered chains of 50, 100, and 150 segments, and five different radii from R=2 up to R=100. We have found excellent quantitative agreement with all the available molecular dynamics and Monte Carlo simulations

M. A. Carignano; I. Szleifer

1995-01-01

237

Evaluation of thermodynamic properties of concrete substrates and cement slurries modified with admixtures  

Microsoft Academic Search

The study of the creation and the stability of the interface between concrete substrates and repair systems needs the knowledge\\u000a of the thermodynamic properties of materials. The measurement of the surface free energies of liquids is realised by means\\u000a of Wilhelmy plate method on reference liquid and repair products. In order to determine polar and dispersive components, it\\u000a is necessary

L. Courard

2002-01-01

238

Thermodynamic properties of two-component cold Fermi gases with bound states  

Microsoft Academic Search

We address the thermodynamics of a two-component cold Fermi gas with short-range interaction. In the BEC region of the BCS-BEC crossover the fermionic particles form bosonic dimers as the two-particle bound states. We focus on the fermionic properties of the particles which constitute the dimers. To this end, we use the Lee-Yang quantum cluster expansion method, which enables us to

Naoyuki Sakumichi; Norio Kawakami; Masahito Ueda

2010-01-01

239

Atomistic study of elastic constants and thermodynamic properties of zinc - blende CuBr  

Microsoft Academic Search

Elastic constants and thermodynamic properties of zinc blende CuBr are calculated using a molecular dynamics simulation based on Tersoff empirical interatomic potential. We find that the elastic modulus C11 is bigger than the other theoretical and experimental data, while C12 is somewhat small. The elastic modulus C44 is in good agreement with the theoretical calculations and experiment. Thermal expansion coefficient,

S. Ahmad; M. A. Wahab

2009-01-01

240

Thermodynamic and transport properties of two-temperature SF{sub 6} plasmas  

SciTech Connect

This paper deals with thermodynamic and transport properties of SF{sub 6} plasmas in a two-temperature model for both thermal equilibrium and non-equilibrium conditions. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and Guldberg-Waage equation according to deviation of van de Sanden et al. Transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated with most recent collision interaction potentials by adopting Devoto's electron and heavy particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of Chapman-Enskog method. The results are computed for various values of pressures from 0.1 atm to 10 atm and ratios of the electron temperature to the heavy particle temperature from 1 to 20 with electron temperature range from 300 to 40 000 K. In the local thermodynamic equilibrium regime, results are compared with available results of previously published studies.

Wang Weizong [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an Shaanxi 710049 (China); Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ (United Kingdom); Rong Mingzhe; Wu Yi [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an Shaanxi 710049 (China); Spencer, Joseph W.; Yan, Joseph D.; Mei, DanHua [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ (United Kingdom)

2012-08-15

241

Thermodynamic and transport properties of two-temperature SF6 plasmas  

NASA Astrophysics Data System (ADS)

This paper deals with thermodynamic and transport properties of SF6 plasmas in a two-temperature model for both thermal equilibrium and non-equilibrium conditions. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and Guldberg-Waage equation according to deviation of van de Sanden et al. Transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated with most recent collision interaction potentials by adopting Devoto's electron and heavy particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of Chapman-Enskog method. The results are computed for various values of pressures from 0.1 atm to 10 atm and ratios of the electron temperature to the heavy particle temperature from 1 to 20 with electron temperature range from 300 to 40 000 K. In the local thermodynamic equilibrium regime, results are compared with available results of previously published studies.

Wang, WeiZong; Rong, MingZhe; Wu, Yi; Spencer, Joseph W.; Yan, Joseph D.; Mei, DanHua

2012-08-01

242

Improved methods for calculating thermodynamic properties of magnetic systems using Wang-Landau density of states  

SciTech Connect

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

243

Phase transition and thermodynamic properties of CaF2 via first principles  

NASA Astrophysics Data System (ADS)

The structural stabilities, phase transitions and thermodynamic properties of CaF2 under high pressure and temperature are investigated by first-principles calculations based on the plane-wave pseudopotential density functional theory method within the generalized gradient approximation (GGA). The calculated lattice parameters of CaF2 under zero pressure and zero temperature are in good agreement with the existing experimental data and other theoretical data. Our results demonstrate that the sequence of the pressure-induced phase transition of CaF2 is the fluorite structure (Fm3m), PbCl2-type structure (Pnma) and Ni2In-type structure (P63/mmc), and the transition pressures are obtained. The temperature-dependent volume and thermodynamic properties of Fm3m phase CaF2 at 0 GPa are presented. The thermodynamic properties of CaF2 in Fm3m, Pnma and P63/mmc phases at 300 K are predicted using the corrected and uncorrected quasi-harmonic approximation model. The variations of the thermal expansion ? and heat capacity CV with pressure P and temperature T of CaF2 in the three phases are systematically obtained.

Qi, Yuan-Yuan; Cheng, Yan; Liu, Min; Chen, Xiang-Rong; Cai, Ling-Cang

2013-10-01

244

Thermodynamic Properties of Two Lithium Silicates (Li2SiO3 and Li2Si2O5).  

National Technical Information Service (NTIS)

Thermodynamic properties were determined by the Bureau of Mines for lithium metasilicate and lithium disilicate. Their enthalpies of formation were investigated by the method of hydrofluoric acid solution calorimetry. The standard enthalpy of formation va...

K. O. Bennington M. J. Ferrante J. M. Stuve

1976-01-01

245

B3LYP/6-311++G**STUDY OF CONFORMATIONAL PREFERENCES AND THERMODYNAMIC PROPERTIES OF DISACCHARIDES  

Technology Transfer Automated Retrieval System (TEKTRAN)

A conformational investigation of selected disaccharides of glucopyranose has been undertaken in an attempt to understand the effects of geometries on energies and thermodynamic properties. The disaccharides investigated exhibit a range of activities for the alternansucrase enzyme. Density function...

246

Role of electronic excitation on thermodynamic and transport properties of argon and argon-hydrogen plasmas  

SciTech Connect

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

247

Structural and Thermodynamic Properties of Amyloid-? Peptides: Impact of Fragment Size  

NASA Astrophysics Data System (ADS)

Alzheimer's disease is a progressive neurodegenerative disease whose physiological characteristics include the accumulation of amyloid-containing deposits in the brain and consequent synapse and neuron loss. Unfortunately, most widely used drugs for the treatment can palliate the outer symptoms but cannot cure the disease itself. Hence, developing a new drug that can cure it. Most recently, the ``early aggregation and monomer'' hypothesis has become popular and a few drugs have been developed based on this hypothesis. Detailed understanding of the amyloid-? peptide structure can better help us to determine more effective treatment strategies; indeed, the structure of Amyloid has been studied extensively employing experimental and theoretical tools. Nevertheless, those studies have employed different fragment sizes of Amyloid and characterized its conformational nature in different media. Thus, the structural properties might be different from each other and provide a reason for the existing debates in the literature. Here, we performed all-atom MD simulations and present the structural and thermodynamic properties of A?1-16, A?1-28, and A?1-42 in the gas phase and in aqueous solution. Our studies show that the overall structures, secondary structures, and the calculated thermodynamic properties change with increasing peptide size. In addition, we find that the structural properties of those peptides are different from each other in the gas phase and in aqueous solution.

Kitahara, T.; Wise-Scira, O.; Coskuner, O.

2010-10-01

248

Two-temperature thermodynamic and transport properties of argon-hydrogen and nitrogen-hydrogen plasmas  

NASA Astrophysics Data System (ADS)

Two-temperature thermodynamic and transport properties of argon-hydrogen and nitrogen-hydrogen plasma mixtures are presented, chemical equilibrium being achieved. The calculations of transport properties are carried out using the Chapman-Enskog method up to the third order; when electron temperature differs from that of heavy particles, calculations are performed following both a recent two-temperature theory by Rat et al that retains the coupling between electrons and heavy particles and a simplified decoupling theory proposed by Devoto. No relevant discrepancies between results obtained using these two approaches have been found, allowing the simplified method of Devoto to be still used in the computation of non-equilibrium transport properties like thermal conductivity, electrical conductivity and viscosity, with the exception of some diffusion coefficients. Results for composition, mass density, specific heat, thermal conductivity, electrical conductivity and viscosity of atmospheric pressure plasmas in the electron temperature range 300-40 000 K are reported.

Colombo, V; Ghedini, E; Sanibondi, P

2009-03-01

249

First principles study on lattice dynamics, thermodynamics and elastic properties of Na2Te under high pressure  

NASA Astrophysics Data System (ADS)

A first-principles investigation on the structural, phonon, thermodynamic and elastic properties of Na2Te has been conducted using the ABINIT code. Our results demonstrate that Na2Te in the anti-fluorite structure phase remains dynamically stable until 20 GPa. The elastic constants and thermodynamic quantities under high pressure are also calculated and discussed.

Zhang, Xudong; Ying, Caihong; Ma, He; Shi, Guimei; Li, Zhijie

2013-09-01

250

Sensitivity analysis of thermodynamic properties of liquid water: A General Approach to Improve Empirical Potentials  

SciTech Connect

A sensitivity analysis of bulk water thermodynamics is presented in an effort to understand the relation between details of molecular potentials and the properties that they predict. The analysis is incorporated in molecular dynamics simulation and investigates the sensitivity of the Helmholtz free energy, internal energy, entropy, heat capacity, pressure, thermal pressure coefficient, and static dielectric constant to details of the potential. The sensitivities of the properties are calculated with respect to the van der Waals repulsive and the attractive parts, plus short and long range Coulomb parts of three four site empirical water potentials: TIP4P, Dang-Chang and TTM2R. The polarization sensitivity is calculated for the polarizable Dang-Chang and TTM2R potentials. The analysis indicates that all investigated properties are most sensitive to the van der Waals repulsive, the short range Coulomb and the polarization components of the potentials. The sensitivity of the Helmoltz free energy, internal energy, and entropy due to polarizaion is almost 30% of total electrostatic sensitivity. In addition the similarities in the trends of the observed sensitivities for nonpolarizable and polarizable potentials lead to the conclusion that the complexity of the model is not of critical importance for the calculation of these properties for bulk water. The van der Waals attractive and the long range Coulomb sensitivities are relatively small for the entropy, heat capacity, thermal pressure coefficient and the static dielectric constant, while small changes in any of the potential contributions will significantly effect the pressure. The analysis suggests a procedure for modification of the potentials and their improved prediction of thermodynamic properties. Based on the proposed procedure the water cluster potential TTM2R was adapted for simulation of bulk water properties.

Iordanov, Tzvetelin D.; Schenter, Gregory K.; Garrett, Bruce C.

2006-01-19

251

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

252

Compatible solutes: Thermodynamic properties and biological impact of ectoines and prolines.  

PubMed

Compatible solutes like ectoine and its derivatives are deployed by halophile organisms as osmolytes to sustain the high salt concentration in the environment. This work investigates the relation of the thermodynamic properties of compatible solutes and their impact as osmolytes. The ectoines considered in this work are ectoine, hydroxyectoine, and homoectoine. Besides solution densities (15-45°C) and solubilities in water (3-80°C), component activity coefficients in the aqueous solutions were determined in the temperature range between 0 and 50°C. The latter is important for adjusting a certain water activity and therewith a respective osmotic pressure within a cell. The characteristic effect of ectoines is compared to that of prolines, as well as to that of incompatible solutes as salts and urea. The experimental results show that the influence on the activity (coefficient) of water is quite different for compatible and incompatible solutes: whereas compatible solutes cause decreasing water activity coefficients, incompatible solutes lead to an increase in water activity coefficients. Based on this quantity, the paper discusses the impact of various osmolytes on biological systems and contributes to the explanation why some osmolytes are more often and at other temperatures used than others. Moreover, it was found that the anti-stress effect of an osmolyte is weakened in the presence of a salt. Finally, it is shown that the thermodynamic properties of compatible solutes can be modeled and even predicted using the thermodynamic model PC-SAFT (Perturbed-Chain Statistical Associating Fluid Theory). PMID:20719425

Held, Christoph; Neuhaus, Thorsten; Sadowski, Gabriele

2010-08-03

253

On the magnetic and thermodynamic properties of Americium-II: A hybrid density functional theoretic study  

NASA Astrophysics Data System (ADS)

The ground states of the actinides have been matters of considerable controversies, theory often contradicting experiment specifically in regards to the magnetic nature. To resolve this discrepancy, we present here hybrid density functional theory (HYB-DFT) based studies of the structural, magnetic, electronic, and thermodynamic properties of Americium-II. Three configurations of non-magnetic (NM), anti-ferromagnetic (AFM), and ferromagnetic (FM) with and without spin-orbit coupling (SOC) have been considered to determine the ground state of Am-II. We find that the experimental NM ground state configuration is indeed obtained for Am-II at a level of 40% Hartree-Fock (HF) exchange with SOC and the computed structural properties and the electronic density of states are in good agreement with experimental observations. We also find that HBY-DFT with NSOC fails to predict the correct magnetic and electronic structures for Am-II, indicating the importance of the inclusion of SOC for studies of strongly correlated materials. The phonon related thermodynamic properties of Am-II are presented for the NM ground state configuration and the computed heat capacity and entropy are found to be in good agreement with the experimental measurements. The lattice constant, bulk modulus, heat capacity, and entropy of AM-II are predicted to be 9.44 a.u., 21.7 GPa, 24.3 JK-1mol-1, and 55.7 JK-1mol-1, respectively.

Wang, Jianguang; Ma, Li; Ray, Asok K.

2010-10-01

254

Investigation of thermodynamic properties of hyperbranched aliphatic polyesters by inverse gas chromatography.  

PubMed

Thermodynamic properties of a series of commercial hyperbranched aliphatic polyesters (Boltorn H20, H30 and H40) were examined for the first time by inverse gas chromatography (IGC) using 13 different solvents at infinite dilution as probes. Retention data of probes were utilized for an extensive characterization of polymers, which includes the determination of the Flory-Huggins interaction parameter, the weight fraction activity coefficient as well as the total and partial solubility parameters. Analysis of the results indicated that the total and partial solubility parameters decrease with increase of temperature. Furthermore, upon increase of the molecular weight, while the hydrogen bonding component decreases, no influence on the total solubility parameter is noticed within the experimental error margins. Results from the present study while providing new insight to the thermodynamic characteristics of the examined systems, they are also expected to reflect more general aspects of the behavior of hyperbranched polymers bearing similar end-groups. PMID:19913230

Dritsas, G S; Karatasos, K; Panayiotou, C

2009-10-22

255

Origin and thermodynamic properties of the instability of synthetic azo colorants in gum arabic solutions.  

PubMed

The instability of some industrially important synthetic azo colorants, including sunset yellow, azorubine, and allura red, toward gum arabic in aqueous solution has been a long-standing problem for the beverage and confectionery industries. Precipitation of these colorants causes the deterioration of product appearance and properties. This work examines the origin and nature of the problem by analysis of the precipitate and thermodynamic studies of gum arabic-colorant interactions using isothermal titration calorimetry (ITC). The presence of divalent alkaline earth metals in gum arabic samples, that is, calcium and magnesium, is shown to be responsible for the precipitation of the azo colorants. There is no direct interaction between gum arabic and the colorant molecules, and the precipitate is formed likely due to the mediation/bridging by the divalent cations. The thermodynamic knowledge gained from the ITC studies, for example, binding affinity, stoichiometry, and enthalpy, enables interpretation of many industrial observations. PMID:17910512

Fang, Yapeng; Al-Assaf, Saphwan; Sakata, Makoto; Phillips, Glyn O; Schultz, Matthias; Monnier, Vivianne

2007-10-03

256

The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use  

Microsoft Academic Search

In 1995, the International Association for the Properties of Water and Steam (IAPWS) adopted a new formulation called “The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use”, which we abbreviate to IAPWS-95 formulation or IAPWS-95 for short. This IAPWS-95 formulation replaces the previous formulation adopted in 1984. This work provides information on

W. Wagner; A. Pruß

1999-01-01

257

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

PubMed

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

258

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

259

Thermodynamic Properties of Rock-Forming Garnets: How Well Known are They?  

NASA Astrophysics Data System (ADS)

Garnet is an important rock-forming mineral whose geological occurrence is widespread. The silicate garnets (E3G2Si3O12) show extensive compositional variability and the various end-members are stable over an enormous range of rock compositions and pressure and temperature conditions. Extensive geothermometry and geobarometry studies involving garnet have been made. Thus, much research has been done to determine garnet's thermodynamic properties. There are now several internally consistent mineralogical thermodynamic databases and their use is widespread. It is common belief in some/many circles that the present databases represent "the final word" on thermodynamic properties at least in terms of most end-member silicates. The question arises - How true is this assumption in the case of garnet? We have been and are presently engaged in investigating the thermodynamic properties of garnet, where volumetric properties and heat-capacity behavior play a central role. The volumes of the various end-member garnets are now known precisely. Only secondary effects arising from extra minor components (e.g., OH-,Fe3+,Mn3+) have yet to be worked out exactly. In terms of heat capacity Cp behavior, new calorimetric data allow improved understanding. Low T calorimetric measurements on spessartine were made recently and show that previous estimates for S° were in error (Dachs et al. 2009). New unpublished calorimetric results on grossular appear to have resolved long-standing uncertainty regarding its precise S° value. S° for silica-free hydrogrossular has also been determined for the first time. Cp measurements are now focusing on almandine and here low T electronic and magnetic properties must be considered. One can conclude that Cp, S°, ?H°f, V and ?G°f for the common silicate garnet end-members are now well determined to about 1000 K. Cp behavior above roughly 1000 K is less certain for some garnets (e.g., almandine, spessartine). What about thermodynamic behavior of garnet solid solutions? Here, there is much less is known (Geiger 1999). The precise mixing behavior of most garnet binaries, for example, is not understood. An exception is the pyrope-grossular binary, which has now been investigated numerous times and some consensus on its mixing properties now exist. In a related area, crystal-chemical investigations are providing good insight on possible macroscopic thermodynamic mixing behavior. Here, for example, low temperature synchrotron measurements on line broadening of powder diffraction lines give the first quantitative lattice-strain determinations on a solid solution (Dapiaggi et al. 20005). The asymmetric nature of the mixing functions ?Hex, ?Sex, and ?Vex can be explained via strain and local Ca/Mg-O bond behavior. Another area needing further investigation is short-range order. 29Si NMR spectroscopic study of synthetic Py-Gr garnets indicates that some short-range Ca-Mg order may be present. Bosenick et al. (1999) estimate that configurational entropy effects of about 2 J/mole.K may result at T > 1000 °C. It remains to be determined, however, what the structural state is at lower temperatures of 600 to 900 °C. The degree of short-range order could be substantial in metamorphic garnet solid solutions.

Geiger, C. A.; Dachs, E.

2011-12-01

260

The thermodynamic properties of 2-aminobiphenyl (an intermediate in the carbazole/hydrogen reaction network)  

SciTech Connect

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

261

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

SciTech Connect

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

262

Predictions of thermodynamic properties of energetic materials using COSMO-RS  

Microsoft Academic Search

In this work, conductor-like screening for real solvents (COSMO-RS) calculations were carried out using COSMOtherm program in conjunction with Gaussian03 packages. The objective was to predict thermodynamic properties for two nitrogen-rich energetic materials which are less harmful for the environment than the conventional ones, namely 3,6-di(hydrazino)-1,2,4,5- tetrazine (DHT) and 3,3’-azo-bis(6-amino-1,2,4,5-tetrazine) (DAAT) for which no experimental data are available to our

Sandra Roy; Mounir Jaidann; Sophie Ringuette; Louis-Simon Lussier; Hakima Abou-Rachid

2010-01-01

263

Structural, electronic, elastic and thermodynamical properties of BaxSr1-xLiH3  

NASA Astrophysics Data System (ADS)

In this paper, we aim to study the structural, electronic, elastic and thermodynamical properties of BaxSr1-xLiH3 using ab initio calculations within the generalized gradient approximation and local density approximation. In particular, the lattice constant, bulk modulus, second-order elastic constants (Cij) and electronic band structures are calculated and compared with the available experimental and other theoretical values. In addition, we have also predicted the variation of Young's modulus (E), Poisson's ratio (v), anisotropy factor (A), sound velocities, Debye temperature (?D) and melting temperature (Tm) as a function of the Ba concentration (x).

Bahloul, B.; Bentabet, A.; Amirouche, L.; Bouhadda, Y.; Fenineche, N.

2011-12-01

264

Thermodynamic Properties of Aqueous Magnesium Chloride Solutions From 250 to 600 K and to 100 MPa  

SciTech Connect

A new general model that describes the thermodynamic properties of MgCl{sub 2}(aq) has been developed from a global fit to experimental results, including isopiestic molalities, vapor pressure measurements, freezing-point depressions, enthalpies of dilution, heat capacities, and densities, for this system. The model is based on a recent ion-interaction treatment with extended higher-order virial terms, and on experimental results from 240 to 627 K at pressures to 100 MPa and molalities to 25thinspmol{center_dot}kg{sup {minus}1}. {copyright} {ital 1998 American Institute of Physics and American Chemical Society.}

Wang, P.; Pitzer, K.S. [Department of Chemistry and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Simonson, J.M. [Oak Ridge National Laboratory, P.O. Box 2008, MS6110, Oak Ridge, Tennessee 37831 (United States)

1998-09-01

265

Thermodynamic properties of a rotating Bose-Einstein condensation in a harmonic plus quartic trap  

NASA Astrophysics Data System (ADS)

In this paper, the thermodynamic properties of a rotating Bose-Einstein condensate confined in a harmonic plus quartic potential are calculated using a modified semiclassical approximation. We determined the condensate fraction, critical temperature and heat capacity of the condensate using a method that takes into account deviations from ideal gas behavior due to the effect of finite size and the chemical potential when it is equal to the ground state energy (positive chemical potential). Predictions that can be directly compared with experiment have been found.

El-Sherbini, Tharwat M.; Hassan, Doaa; Galal, Abdelhamid A.; Hassan, Ahmed S.

2013-08-01

266

Specific heat and related thermodynamic properties of an undercooled germanium melt  

NASA Astrophysics Data System (ADS)

Embedded in a flux of dehydrated B2O3, melts of pure germanium were undercooled by repeated melting and solidification of the specimens within a differential scanning calorimeter facility. The highest undercooling obtained in this way was 190 K. The specific heat of the undercooled melt was measured by calorimetric diagnostics within the facility, and showed a linear dependence on temperature. The thermodynamic properties of germanium, such as the difference of Gibbs free energy, the difference of entropy, and the difference of enthalpy between the undercooled melt and the solid state, were derived from the measured specific heat.

Li, Q.; Zhu, Y. Y.; Liu, R. P.; Li, G.; Ma, M. Z.; Yu, J. K.; He, J. L.; Tian, Y. J.; Wang, W. K.

2004-07-01

267

Thermodynamic properties of noninteracting quantum gases with spin-orbit coupling  

SciTech Connect

In this brief report we study thermodynamic properties of noninteracting quantum gases with isotropic spin-orbit coupling. At high temperature, coefficients of virial expansion depend on both temperature T and spin-orbit coupling strength {kappa}. For strong coupling, virial expansion is applicable to the temperature region below the conventional degenerate temperature T{sub F}. At low temperature, specific heat is proportional to {radical}(T) in Bose gases and T in Fermi gases. Temperature dependence of the chemical potential of fermions shows a different behavior when the Fermi surface is above and below the Dirac point.

He Li [Jiangsu University of Science and Technology, Zhangjiagang, Jiangsu, 215600 (China); Yu Zengqiang [Institute for Advanced Study, Tsinghua University, Beijing, 100084 (China)

2011-08-15

268

Establishment of a room temperature molten salt capability to measure fundamental thermodynamic properties of actinide elements  

SciTech Connect

This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this work was to establish a capability for the measurement of fundamental thermodynamic properties of actinide elements in room temperature molten salts. This capability will be used to study in detail the actinide chloro- and oxo-coordination chemistries that dominate in the chloride-based molten salt media. Uranium will be the first actinide element under investigation.

Smith, W.H.; Costa, D.A.

1998-12-31

269

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

Microsoft Academic Search

Extensive water activity, density, and refractive index data at 25øC are reported for mixed-salt solutions, NaC1-KCI, NaC1-NaNO 3, NaCI-Na2SO 4, Na2SO4-NaNO 3, and (NH4)2SO 4- Na2SO 4. The data are obtained from hydration experiments using the single-particle levitation technique developed recently for measuring the thermodynamic and optical properties of microdroplets. These data, coveting the whole concentration range from dilute solutions

Ignatius N. Tang

1997-01-01

270

Thermodynamic properties of adsorbed water on silica gel - Exergy losses in adiabatic sorption processes  

NASA Astrophysics Data System (ADS)

In order to perform exergy analyses to optimize the transient heat and mass transfer processes involving sorption by solid adsorbents, the thermodynamic properties of adsorbed water must be determined. In this paper, the integral enthalpy and entropy are determined directly from isotherm data of water adsorbed on silica gel particles and silica gel manufactured in the form of a felt with 25 percent cotton as a support and Teflon as a binder. These results are then used to evaluate the exergy losses, due to the sorption and the convective heat and mass transfer processes, that occur in each portion of an adiabatic desiccant dehumidificaton cycle.

Worek, W. M.; Zengh, W.; San, J.-Y.

1991-09-01

271

Thermodynamic properties and equation of state of zircon ZrSiO{sub 4}  

SciTech Connect

The silicate mineral zircon is a host material for radioactive materials in the earth`s crust and is a natural candidate for usage as a nuclear waste storage material. Lattice dynamical calculations have been carried out to understand its thermodynamic properties and high pressure behavior. The calculated phonon density of states, variation of phonon frequencies with pressure and equation of state are in good agreement with the available experimental data. One of the zone center optic mode involving SiO{sub 4} rotations becomes soft at 47 GPa.

Mittal, R.; Chaplot, S.L.; Choudhury, N. [Bhabha Atomic Research Centre, Trombay (India). Solid State Physics Div.; Loong, C.K. [Argonne National Lab., IL (United States)

1998-11-01

272

Thermodynamics properties and thermal conductivity of Mg2Pb at high pressure  

NASA Astrophysics Data System (ADS)

The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by first-principles. The enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the experiments and other theoretical results. The thermal conductivity and coefficient of thermal expansion of Mg2Pb at high pressure were evaluated. The thermal conductivity presents a second-order polynomial with pressure. The calculated thermal conductivity of Mg2Pb indicates that it is suitable to be used as thermal conductor at 0 K.

Duan, YongHua; Sun, Yong

2013-10-01

273

Thermodynamic properties of chloro-complexes of silver chloride in aqueous solution  

Microsoft Academic Search

Available data on the solubility of silver chloride in aqueous solutions of HCl, NaCl, KCl, LiCl, and NH4Cl, along with potentiometric measurements of the activity of Ag+ in aqueous NaCl-NaClO4 mixtures, have been analyzed to obtain the thermodynamic properties of the (AgCl)0, AgCl2-, AgCl32-, and AgCl43- complexes. Results obtained include the stability constants of the complexes and 25°C, the virial

James J. Fritz

1985-01-01

274

Thermodynamic and structural properties of the high density Gaussian core model  

NASA Astrophysics Data System (ADS)

We numerically study thermodynamic and structural properties of the one-component Gaussian core model at very high densities. The solid-fluid phase boundary is carefully determined. We find that the density dependence of both the freezing and melting temperatures obey the asymptotic relation, log Tf, log Tm~ - ?2/3, where ? is the number density, which is consistent with Stillinger's conjecture. Thermodynamic quantities such as the energy and pressure and the structural functions such as the static structure factor are also investigated in the fluid phase for a wide range of temperature above the phase boundary. We compare the numerical results with the prediction of the liquid theory with the random phase approximation (RPA). At high temperatures, the results are in almost perfect agreement with RPA for a wide range of density, as it has already been shown in the previous studies. In the low temperature regime close to the phase boundary line, although RPA fails to describe the structure factors and the radial distribution functions at the length scales of the interparticle distance, it successfully predicts their behaviors at longer length scales. RPA also predicts thermodynamic quantities such as the energy, pressure, and the temperature at which the thermal expansion coefficient becomes negative, almost perfectly. Striking ability of RPA to predict thermodynamic quantities even at high densities and low temperatures is understood in terms of the decoupling of the length scales which dictate thermodynamic quantities from the interparticle distance which dominates the peak structures of the static structure factor due to the softness of the Gaussian core potential.

Ikeda, Atsushi; Miyazaki, Kunimasa

2011-07-01

275

Thermodynamic properties of solid oxide fuel cell anode material: La1-xSrxVO3  

NASA Astrophysics Data System (ADS)

We have computed the lattice contribution to the specific heat at constant volume for Sr doped LaVO3 with various doping concentrations (0 <= x <= 0.4) at temperature 20K <= T <= 300K. The thermodynamic properties for La1-xSrxVO3 have been studied probably for the first time by the means of a Modified Rigid Ion Model (MRIM). Also the effect of lattice distortions on the elastic and thermal properties of the present Vanadates has been studied by an atomistic approach. Our results are in a fair agreement with the available experimental data. The specific heat results can further be improved by including the spin and orbital ordering contributions to the specific heat.

Parveen, Atahar; Gaur, N. K.; Nigam, Arun K.

2013-06-01

276

A simple analysis of thermodynamic properties for classical plasmas: II. Validation  

NASA Astrophysics Data System (ADS)

The generalized hole corrected Debye-Hückel theory (Penfold et al J. Stat. Mech. (2005) P06009) is implemented. Predictions of thermodynamic functions and simple structural properties compare favourably with results from closure of the Ornstein-Zernike integral equation in the mean spherical approximation, and with Monte Carlo simulation of the charged hard sphere primitive model. A strictly nonelectroneutral system was simulated using a conventional electrolyte program and the properties subsequently corrected for the configuration independent background terms. No convergence difficulties were encountered over the concentration range studied. With the new theory, activity coefficients of good accuracy can be obtained in a simple analytical form that is suitable for use with an approximate free energy density functional describing ion-ion correlations in screening atmospheres.

Penfold, Robert; Jönsson, Bo; Robins, Margaret

2005-06-01

277

Equations of state for the thermodynamic properties of R32 (difluoromethane) and R125 (pentafluoroethane)  

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

278

SteamTablesGrid: An ActiveX control for thermodynamic properties of pure water  

NASA Astrophysics Data System (ADS)

An ActiveX control, steam tables grid ( StmTblGrd) to speed up the calculation of the thermodynamic properties of pure water is developed. First, it creates a grid (matrix) for a specified range of temperature (e.g. 400-600 K with 40 segments) and pressure (e.g. 100,000-20,000,000 Pa with 40 segments). Using the ActiveX component SteamTables, the values of selected properties of water for each element (nodal point) of the 41×41 matrix are calculated. The created grid can be saved in a file for its reuse. A linear interpolation within an individual phase, vapor or liquid is implemented to calculate the properties at a given value of temperature and pressure. A demonstration program to illustrate the functionality of StmTblGrd is written in Visual Basic 6.0. Similarly, a methodology is presented to explain the use of StmTblGrd in MS-Excel 2007. In an Excel worksheet, the enthalpy of 1000 random datasets for temperature and pressure is calculated using StmTblGrd and SteamTables. The uncertainty in the enthalpy calculated with StmTblGrd is within ±0.03%. The calculations were performed on a personal computer that has a "Pentium(R) 4 CPU 3.2 GHz, RAM 1.0 GB" processor and Windows XP. The total execution time for the calculation with StmTblGrd was 0.3 s, while it was 60.0 s for SteamTables. Thus, the ActiveX control approach is reliable, accurate and efficient for the numerical simulation of complex systems that demand the thermodynamic properties of water at several values of temperature and pressure like steam flow in a geothermal pipeline network.

Verma, Mahendra P.

2011-04-01

279

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: First-Principles Calculations for Thermodynamic Properties of Perovskite-Type Superconductor MgCNi3  

Microsoft Academic Search

The ground state properties and equation of state of the non-oxide perovskite-type superconductor MgCNi3 are investigated by first-principles calculations based on the plane-wave basis set with the local density approximation (LDA) as well as the generalized gradient approximation (GGA) for exchange and correlation, which agree well with both theoretical calculations and experiments. Some thermodynamic properties including the heat capacity, the

Wei Zhang; Zhe Li; Xiang-Rong Chen; Ling-Cang Cai; Fu-Qian Jing

2008-01-01

280

The X-ray/SZ view of the virial region. I. Thermodynamic properties  

NASA Astrophysics Data System (ADS)

Aims: We measure the thermodynamic properties of cluster outer regions to provide constraints on the processes that rule the formation of large-scale structures. Methods: We derived the thermodynamic properties of the intracluster gas (temperature, entropy) by combining the Sunyaev-Zel'dovich thermal pressure from Planck and the X-ray gas density from ROSAT. This method allowed us to reconstruct for the first time temperature and entropy profiles out to the virial radius and beyond in a large sample of objects. Results: At variance with several recent Suzaku studies, we find that the entropy rises steadily with radius, albeit at at a somewhat lower rate than predicted by self-similar expectations. We note significant differences between relaxed, cool-core systems and unrelaxed clusters in the outer regions. Relaxed systems appear to follow the self-similar expectations more closely than perturbed objects. Conclusions: Our results indicate that the well-known entropy excess observed in cluster cores extends well beyond the central regions. When correcting for the gas depletion, the observed entropy profiles agree with the prediction from gravitational collapse only, especially for cool-core clusters. Appendices are available in electronic form at http://www.aanda.org

Eckert, D.; Molendi, S.; Vazza, F.; Ettori, S.; Paltani, S.

2013-03-01

281

Thermodynamics and structural properties of a confined HP protein determined by Wang-Landau simulation  

NASA Astrophysics Data System (ADS)

Understanding protein folding confined by surfaces is important for both biological sciences and the development of nanomaterials. In this work, we study the properties of a confined HP model protein by three different types of surfaces, namely, surfaces that attract: (a) all monomers; (b) only P monomers; and (c) only H monomers. The thermodynamic and structural quantities, such as the specific heat, number of surface contacts, and number of hydrophobic pairs, are obtained by using Wang-Landau sampling. The conformational "transitions", specifically, the debridging process and hydrophobic core formation, can be identified based on an analysis of these quantities. We found that these transitions take place at different temperatures, and the ground state configurations show variations in structural properties when different surface type is used. These scenarios are confirmed by snapshots of typical states of the systems. From our study, we conclude that the thermodynamics of these transitions and the structural changes depend on the combined actions of both the composition of the H monomers and the P monomers in the HP chain and the surface types.

Pattanasiri, Busara; Li, Ying Wai; Landau, David P.; Wüst, Thomas; Triampo, Wannapong

2013-08-01

282

Thermodynamic properties of several soil- and sediment-derived natural organic materials.  

PubMed

Improved understanding of the structure of soil- and sediment-derived organic matter is critical to elucidating the mechanisms that control the reactivity and transport of contaminants in the environment. This work focuses on an experimental investigation of thermodynamic properties that are a function of the macromolecular structure of natural organic matter (NOM). A suite of thermal analysis instruments were employed to quantify glass transition temperatures (Tg), constant-pressure specific heat capacities (Cp), and thermal expansion coefficients (alpha) of several International Humic Substances Society (IHSS) soil-, sediment-, and aquatic-derived NOMs. Thermal mechanical analysis (TMA) of selected NOMs identified Tgs between 36 and 72 degrees C, and alphas ranging from 11 mum/m degrees C below the Tg to 242 mum/m degrees C above the Tg. Standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC) measurements provided additional evidence of glass transition behavior, including identification of multiple transition behavior in two aquatic samples. TMDSC also provided quantitative measures of Cp at 0 and 25 degrees C, ranging from 1.27 to 1.44 J/g degrees C. Results from TMA, DSC, and TMDSC analyses are consistent with glass transition theories for organic macromolecules, and the glass transition behavior of other NOM materials reported in previous studies. Discussion of the importance of quantifying these thermodynamic properties is presented in terms of improved physical and chemical characterization of NOM structures, and in terms of providing constraints to molecular simulation models of NOM structures. PMID:14581055

DeLapp, Rossane C; LeBoeuf, Eugene J; Bell, Katherine D

2004-01-01

283

Ab initio thermodynamic properties of point defects and O-vacancy diffusion in Mg spinels  

NASA Astrophysics Data System (ADS)

We report ab initio plane wave density functional theory studies of thermodynamic properties of isolated cation substitutions and oxygen vacancies in magnesium spinel, MgAl2O4 . The formation enthalpy of Ca, Cu, and Zn substitutions of Mg cation indicate that transition metal dopants are energetically stable in the bulk of MgAl2O4 at low oxygen chemical potential. The electronic and thermodynamic properties of isolated defects in ternary spinel show close similarities with those in binary oxides; MgO and ?-Al2O3 . The formation enthalpy of the oxygen vacancies are also similar in pure magnesium spinel and in binary oxides, but presence of impurity cations in MgAl2O4 significantly lowers formation enthalpy of the oxygen vacancy in their vicinity. Calculated energy barriers for oxygen vacancy hopping are lower in the vicinity of impurity atoms in the spinel structure. Our calculations indicate that the charge state of doped cation is modified by the accompanying oxygen vacancy and the vacancy diffusion is more facile around impurity. The present studies suggest that point defects play an important role in diffusion of oxygen vacancies in MgAl2O4 .

?odziana, Zbigniew; Piechota, Jacek

2006-11-01

284

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

SciTech Connect

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

285

The use of molecular dynamics for the thermodynamic properties of simple and transition metals  

SciTech Connect

The technique of computer simulation of the molecular dynamics in metallic systems to calculate thermodynamic properties is discussed. The nature of a metal as determined by its electronic structure is used to determine the total adiabatic potential. The effective screened ion-ion interaction can then be used in a molecular dynamics simulation. The method for the construction of a molecular dynamics ensemble, its relation to the canonical ensemble, and the definition of thermodynamic functions from the Helmholtz free energy is given. The method for the analysis of the molecular dynamics results from quasiharmonic lattice dynamics and the decomposition in terms of harmonic and anharmonic contributions is given for solids. For fluid phase metals, procedures for calculating the thermodynamics and determining the constant of entropy are presented. The solid-fluid phase boundary as a function of pressure and temperature is determined using the results of molecular dynamics. Throughout, examples and results for metallic sodium are used. The treatment of the transition metal electronic d-states in terms of an effective pair-wise interaction is also discussed and the phonon dispersion curves of Al, Ni, and Cu are calculated.

Straub, G.K.

1987-04-01

286

First-Principles Calculations of Thermodynamic Properties and Phase Diagrams of Binary Substitutional Alloys  

NASA Astrophysics Data System (ADS)

In this dissertation it is shown how quantum and statistical mechanical computational techniques can be combined in order to make possible the calculation of thermodynamic properties for solid-state binary substitutional alloy phases from first principles, i.e., from a knowledge of only basic crystallographic information and the atomic numbers of the alloy constituents. The framework which is discussed here for performing such calculations is based on the formalism of cluster expansions. Using this formalism the statistical mechanical problem of computing substitutional alloy thermodynamic properties can be reduced to that of solving a generalized Ising model. It is shown how the parameters describing atomic interactions in such an Ising model can be derived with the structure inversion method from the results of quantum mechanical calculations of zero-temperature total energies for a number of ordered stoichiometric alloy compounds sharing a common underlying parent structure. Once the parameters in the generalized Ising model have been derived, alloy thermodynamic properties can be calculated by a variety of statistical mechanical techniques. In the work presented here the quantum and statistical mechanical calculations have been performed using the linear muffin-tin orbital and cluster variation methods, respectively. These computational methods are both described in some detail. The formalism and computational techniques mentioned in the previous paragraph are applied to the study of alloy phase stability in the Ti-Al and Cd-Mg systems. For Cd -Mg an effort is made to determine the relative magnitudes of the contributions to the alloy free energy arising from configurational disorder, structural relaxations, as well as vibrational and electronic excitations. It is shown that when all of these different contributions to the free energy are included, the calculated solid-state portion of the composition-temperature phase diagram for the Cd -Mg system is in excellent agreement with experimental measurements. For the Ti-Al system, the thermodynamic stability of phases with fcc- and hcp-based crystal structures is studied. It is shown that the complexity of the Ti-Al phase diagram can be understood as being the result of a very close competition between stable and metastable ordered phases in this system.

Asta, Mark David

287

Thermodynamic and structural properties of liquids modelled by '2-Lennard-Jones centres' pair potentials  

NASA Astrophysics Data System (ADS)

Molecular dynamics calculations have been carried out for model liquid systems of N (=108 or 256) molecules interacting through two Lennard-Jones (12-6) centres coinciding with the positions of the atomic masses (the 'atom-atom' pair potential). The objectives were (a) to study the dependence of the properties on the molecular anisotropy defined by the reduced distance l*=l/? between the centres in the range 0·5-0·8; and (b) to compare the computed quantities with those of real liquids (F2, Cl2, Br2, CO2). This paper deals with thermodynamic and structural features. Time-dependent correlations will be treated in a future communication. In the liquid region not too far from the triple point the energy and pressure isochores are well represented by straight lines, the slopes of which increase with density and anisotropy. Thermodynamically consistent expressions for the energy and pressure as functions of density and temperature have been obtained for each system. With Lennard-Jones parameters adjusted so as to secure the best overall fit, the agreement between experimental and computed thermodynamic properties is very satisfactory for F2 (l*=0·505), quite good for Cl2 and Br2 (l*=0·608-0·63), but rather poor for CO2 (l*=0·793). The 'interatomic distances' are close to the experimental values. The static structural correlations are discussed in terms of the pair-correlation functions (pcf) gA(r*) for the separation between 'atoms', the first few functions gll'm(R*) which arise from the expansion of the g(R*, ?1, ?2, ?12) in spherical harmonics, and the pcf's for certain special near-neighbour configurations. The computed atom-atom structure factor is compared with the experimental data for liquid Br2. Mean square forces and torques have been evaluated and are related to some experimental results.

Singer, K.; Taylor, A.; Singer, J. V. L.

288

Investigation of surface properties of some polymers by a thermodynamic and mechanical approach: possibility of predicting mucoadhesion and biocompatibility.  

PubMed

Mucoadhesive properties of several polymers, such as sodium alginate, hydroxypropylmethyl cellulose, scleroglucan, xanthan gum, polyacrylic acid (Carbopol), and poly co-(methyl vinyl ether-maleic anhydride) (Gantrez), have been investigated by comparing a thermodynamical and a mechanical approach. Surface properties of polymers in the dry state have been studied by contact angle measurements and thermodynamical parameters derived by using different equations. This tensile adhesive strength of polymers in hydration conditions was measured by a modified DuNoy tensiometer. Comparison of the two different approaches has allowed us to conclude that thermodynamical consideration on surface energy can be used to evaluate mucoadhesive properties of materials. Data obtained with the two methods yielded a good linear correlation. Calculation of surface free energy of the considered materials also allowed a prediction of the water-polymer interface free energy: biocompatibility, defined according to the minimal interfacial free energy concept, could consequently be evaluated. PMID:8199290

Esposito, P; Colombo, I; Lovrecich, M

1994-02-01

289

Prediction of thermodynamic properties of coal derivatives. Final technical report, September 1, 1987--February 28, 1991  

SciTech Connect

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

290

Phonon densities of states and related thermodynamic properties of high temperature ceramics.  

SciTech Connect

Structural components and semiconductor devices based on silicon nitride, aluminum nitride and gallium nitride are expected to function more reliably at elevated temperatures and at higher levels of performance because of the strong atomic bonding in these materials. The degree of covalency, lattice specific heat, and thermal conductivity are important design factors for the realization of advanced applications. We have determined the phonon densities of states of these ceramics by the method of neutron scattering. The results provide a microscopic interpretation of the mechanical and thermal properties. Moreover, experimental data of the static, structures, and dynamic excitations of atoms are essential to the validation of interparticle potentials employed for molecular-dynamics simulations of high-temperature properties of multi-component ceramic systems. We present an overview of neutron-scattering investigations of the atomic organization, phonon excitations, as well as calculations of related thermodynamic properties of Si{sub 3}N{sub 4}, {beta}-sialon, AlN and GaN. The results are compared with those of the oxide analogs such as SiO{sub 2} and Al{sub 2}O{sub 3}.

Loong, C.-K.

1998-08-28

291

BON-BONs: cyclic molecules with a boron-oxygen-nitrogen backbone. Computational studies of their thermodynamic properties.  

PubMed

Although they were first reported in 1963, molecules with a boron-oxygen-nitrogen dimeric backbone do not seem to have been investigated seriously in terms of thermodynamic properties. Here we report on the calculated structures and properties, including thermodynamics, of several so-called "BON-BON" molecules. With the popularity of nitrogen-containing substituents on new high-energy materials, nitro-substituted BON-BONs were a focus of our investigation. A total of 42 BON-BON molecules were evaluated, and thermochemical analysis shows a decrease in the specific enthalpy of combustion or decomposition with increasing NO(2) content, consistent with other systems. PMID:21811776

Lawong, Aloysus K; Ball, David W

2011-08-03

292

Theoretical investigation on the structural and thermodynamic properties of FeSe at high pressure and high temperature.  

PubMed

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

2012-07-13

293

Thermodynamic and Kinetic Properties of Metal Hydrides from First-Principles Calculations  

NASA Astrophysics Data System (ADS)

In an effort to minimize the worldwide dependence on fossil fuels, much research has focused on the development of hydrogen fuel cell vehicles. Among the many challenges currently facing the transition to such an alternative energy economy is the storage of hydrogen in an economical and practical way. One class of materials that has presented itself as a possible candidate is solid metal hydrides. These materials chemically bind hydrogen and on heating, release the gas which can then be used to generate power as needed for the vehicle. In order to meet guidelines that have been set for such a storage system, hydrogen must be released rapidly in a narrow temperature range of -40 to 80°C with all reactions being reversible. This sets both thermodynamic and kinetic requirements for the design of candidate metal hydrides. First-principles calculations are well-suited for the task of exploring reactions involving metal hydrides. Here, density-functional theory is used to calculate properties of these materials at the quantum mechanical level of accuracy. In particular, three systems have been investigated: 1. Li-Mg-N-H. Reactions between all known compounds in this system are systematically investigated in order to predict thermodynamically allowed reactions that release hydrogen. The properties of these reactions are compared to the requirements set for hydrogen storage systems. Additionally, ground-state structures are predicted for Li2Mg(NH)2 and Li 4Mg(NH)3. 2. Na-Al-H. The kinetics of mass transport during the (de)hydrogenation of the well-known metal hydride NaAlH4 are investigated. A model is developed to study the flux of native defects through phases involved in these reactions. Since it is also known that titanium is an effective catalyst for both dehydrogenation and rehydrogenation, the effect of Ti substitution in bulk lattices on the kinetics of mass transport is investigated. Results are compared to experiments in order to determine if mass transport represents the rate-limiting process during de- or rehydrogenation and what the effect of Ti may be. 3. Si-H. Properties of the recently synthesized compound SiH4(H 2)2 are investigated. Under high pressures, hydrogen binding to SiH4 exhibits characteristics of both physical and chemical bonds. A ground-state structure is predicted for this phase and the vibrational and bonding properties are investigated in order to determine the origin of the unusual binding between H2 and SiH4.

Michel, Kyle Jay

294

Thermodynamic properties of non-conformal soft-sphere fluids with effective hard-sphere diameters.  

PubMed

In this work we study a set of soft-sphere systems characterised by a well-defined variation of their softness. These systems represent an extension of the repulsive Lennard-Jones potential widely used in statistical mechanics of fluids. This type of soft spheres is of interest because they represent quite accurately the effective intermolecular repulsion in fluid substances and also because they exhibit interesting properties. The thermodynamics of the soft-sphere fluids is obtained via an effective hard-sphere diameter approach that leads to a compact and accurate equation of state. The virial coefficients of soft spheres are shown to follow quite simple relationships that are incorporated into the equation of state. The approach followed exhibits the rescaling of the density that produces a unique equation for all systems and temperatures. The scaling is carried through to the level of the structure of the fluids. PMID:22158949

Rodríguez-López, Tonalli; del Río, Fernando

2011-12-09

295

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

NASA Astrophysics Data System (ADS)

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 Te = 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; Zhao, JianLing; Cheng, XinLu; Zhang, Hong

2013-07-01

296

Effect of polymer-filler interaction strengths on the thermodynamic and dynamic properties of polymer nanocomposites  

SciTech Connect

The structural and dynamical properties of polymer nanocomposites are investigated using stochastic molecular dynamics simulations. For spherical nanoparticles dispersed in a polymer matrix the results indicate that the polymer-nanoparticle interaction strength and the overall system temperature are primarily responsible for the type of dispersed state (clustering and homogeneous dispersion) achieved. A systematic study probing temperature, polymerization, polymer-nanoparticle and nanoparticle-nanoparticle interactions strengths have been performed. In this paper, however, we focus the discussion on the results for varying polymer-nanoparticle interactions strengths at different temperatures. By examining the structure and dynamics, we show there are two kinds of `clustering transitions'; one due to thermodynamic and another due to the dynamical response of the system. From these results a representative phase diagram is developed that captures the entire simulated space and allows the easy identification of the highly dispersed and the clustered states.

Sumpter, Bobby G [ORNL; Goswami, Monojoy [ORNL

2009-01-01

297

Correlating compressor and turbine costs with thermodynamic properties for CAES power plants  

SciTech Connect

Compressed air energy storage (CAES) is a technology that converts excess base load energy into stored pneumatic energy by means of a compressor for a later release through a turbine as premium peaking power. The CAES system consists of a modified gas turbine combined with an underground storage reservoir. Since 1978, such a power plant has operated successfully in Huntorf, West Germany. Others are in construction throughout the world, the largest being constructed in Donbas, Soviet Union (1050 MW). CAES is more economic with respect to other energy storage facilities due to its relatively low installation cost, short construction time, and high reliability. However, since the number of CAES plants all over the world is still small, it is essential for plant planning and optimization to evaluate normative functions for the turbine and compressor cost. The components costs are evaluated from their thermodynamic and turbo-aerodynamic properties, enabling evaluation of the optimal plant parameters.

Vadasz, P.; Weiner, D.

1987-11-01

298

Thermodynamic properties of iron and nickel chloride solutions in molten LiCl-KCl  

SciTech Connect

The thermodynamic properties of solutions of iron or nickel chlorides in mixed molten LiCl-KCl were determined by emf measurements of FeCl{sub 2} or NiCl{sub 2} formation cells. The concentration range examined was 0.015-2 mol %. The temperature dependence of the emf between 355 and 540{degree}C was used to calculate the enthalpy and entropy of formation of dissolved FeCl{sub 2} or NiCl{sub 2}. It was shown that, in the investigated concentration range, these solutions have a nearly ideal behavior. Simple empirical equations were derived to represent the emf of these formation cells with an accuracy of about {plus minus} 1.5 mV.

Lantelme, F.; Chemla, M. (Universite Pierre et Marie Curie, Paris (France)); Equey, J.F.; Mueller, S. (Paul Scherrer Institut, Villigen (Switzerland))

1991-01-24

299

Effect of polymer-filler interaction strengths on the thermodynamic and dynamic properties of polymer nanocomposites  

NASA Astrophysics Data System (ADS)

The structural and dynamical properties of polymer nanocomposites are investigated using stochastic molecular dynamics simulations. For spherical nanoparticles dispersed in a polymer matrix, the results indicate that the polymer-nanoparticle interaction strength and the overall system temperature are primarily responsible for the type of dispersed state (clustering and homogeneous dispersion) achieved. A systematic study probing temperature, polymerization, and polymer-nanoparticle and nanoparticle-nanoparticle interaction strengths has been performed. In this paper, however, we focus the discussion on the results for varying polymer-nanoparticle interaction strengths at different temperatures. By examining the structure and dynamics, we show that there are two kinds of ``clustering transitions:'' one due to thermodynamic and another due to the dynamical response of the system. From these results, a representative phase diagram is developed that captures the entire simulated space and allows the easy identification of the highly dispersed and the clustered states.

Goswami, Monojoy; Sumpter, Bobby G.

2009-04-01

300

Estimation of the Thermodynamic Limit of Overheating for Bulk Water from Interfacial Properties  

NASA Astrophysics Data System (ADS)

The limit of overheating or expanding is an important property of liquids, which is relevant for the design and safety assessment of processes involving pressurized liquids. In this work, the thermodynamic stability limit—the so-called spinodal—of water is calculated by molecular dynamics computer simulation, using the molecular potential model of Baranyai and Kiss. The spinodal pressure is obtained from the maximal tangential pressure within a liquid-vapor interface layer. The results are compared to predictions of various equations of state. Based on these comparisons, a set of equations of state is identified which gives reliable results in the metastable (overheated or expanded) liquid region of water down to -55 MPa.

Imre, A. R.; Baranyai, A.; Deiters, U. K.; Kiss, P. T.; Kraska, T.; Quiñones Cisneros, S. E.

2013-09-01

301

Structural and thermodynamic properties of starches extracted from GBSS and GWD suppressed potato lines.  

PubMed

A combined DSC-SAXS approach was employed to study the effects of amylose and phosphate esters on the assembly structures of amylopectin in B-type polymorphic potato tuber starches. Amylose and phosphate levels in the starches were specifically engineered by antisense suppression of the granule bound starch synthase (GBSS) and the glucan water dikinase (GWD), respectively. Joint analysis of the SAXS and DSC data for the engineered starches revealed that the sizes of amylopectin clusters, thickness of crystalline lamellae and the polymorphous structure type remained unchanged. However, differences were found in the structural organization of amylopectin clusters reflected in localization of amylose within these supramolecular structures. Additionally, data for annealed starches shows that investigated potato starches possess different types of amylopectin defects. The relationship between structure of investigated potato starches and their thermodynamic properties was recognized. PMID:17188347

Kozlov, Sergey S; Blennow, Andreas; Krivandin, Alexei V; Yuryev, Vladimir P

2006-11-15

302

Thermodynamic properties, nonstoichiometry and phase transformation parameters of oxides in the Eu-O system  

NASA Astrophysics Data System (ADS)

The influence of nonstoichiometry on the partial thermodynamic properties of oxygen and the {C to B} transformation parameters of europium sesquioxide within a temperature range from 1200 K to 1400 K using e.m.f., DTA and DSC methods, has been determined. A tentative phase diagram in the {Cto B} transformation region is proposed. L'influence de la nonstoechiométrie sur les propriétés thermodynamiques partielles de l'oxygène et sur les paramètres de la transition {C to B} de Eu2O3 dans l'intervalle de températures de 1200 K à 1400 K a été étudiée par les méthodes EMF, DTA, DSC. Une variante de diagramme de phases dans la région de la transition {Cto B} est présentée.

Sukhushina, I.; Vasiljeva, I.; Balabajeva, R.

1998-01-01

303

Trapping Effect of Periodic Structures on the Thermodynamic Properties of a Fermi Gas  

NASA Astrophysics Data System (ADS)

We report the thermodynamic properties of an ideal Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes simulated by one (planes) or two perpendicular (tubes) external Dirac comb potentials, while the particles are allowed to move freely in the remaining directions. In contrast to what happens to the bosonic chemical potential, which is a constant for T

Salas, P.; Solís, M. A.

2013-10-01

304

Thermodynamical Properties and Quasi-Localized Energy of the Stringy Dyonic Black Hole Solution  

NASA Astrophysics Data System (ADS)

In this paper, we calculate the heat flux passing through the horizon TS|rh and the difference of energy between the Einstein and Møller prescription within the region {M}, in which is the region between outer horizon {H}+ and inner horizon {H}-, for the modified GHS solution, KLOPP solution and CLH solution. The formula E Einstein | M = E Møller | M-? {? {M}}TS is obeyed for the mGHS solution and the KLOPP solution, but not for the CLH solution. Also, we suggest a RN-like stringy dyonic black hole solution, which comes from the KLOPP solution under a dual transformation, and its thermodynamical properties are the same as the KLOPP solution.

Yang, I.-Ching; Chen, Bai-An; Tsai, Chung-Chin

2012-09-01

305

Phase Transition, Elastic and Thermodynamic Properties of Beryllium via First Principles  

NASA Astrophysics Data System (ADS)

The phase transition, elastic and thermodynamic properties of beryllium (Be) have been studied at high pressures by plane-wave ultrasoft pseudopotential density functional theory (DFT) within the generalized gradient approximation (GGA). It is found that the hcp ? bcc phase transition of Be occurs at 506 GPa (T = 0 K) and occurs at 1200 K (P = 0 GPa). The coefficients of linear thermal expansion of the hexagmal close-packed (hcp), bcc and orthorhombic Be have been calculated. The hcp ? orthorhombic ? bcc phase transitions do not occur in all range of pressures, that is to say, the orthorhombic Be is not an intermediate phase between the hcp and bcc Be. The obtained bulk modulus (B0) are 113.2 GPa (for hcp Be), 113.1 GPa (for bcc Be) and 70.5 GPa (for orthorhombic Be), respectively.

Cheng, Yan; Chen, Hai-Hua; Xue, Fan-Xiang; Ji, Guang-Fu; Gong, Min

2013-09-01

306

A novel equation of state for the prediction of thermodynamic properties of fluids.  

PubMed

This work proposes a new equation of state (EOS) based on molecular theory for the prediction of thermodynamic properties of real fluids. The new EOS uses a novel repulsive term, which gives the correct hard sphere close packed limit and yields accurate values for hard sphere and hard chain virial coefficients. The pressure obtained from this repulsive term is corrected by a combination of van der Waals and Dieterici potentials. No empirical temperature functionality of the parameters has been introduced at this stage. The novel EOS predicts the experimental volumetric data of different compounds and their mixtures better than the successful EOS of Peng and Robinson. The prediction of vapor pressures is only slightly less accurate than the results obtained with the Peng-Robinson equation that is designed for these purposes. The theoretically based parameters of the new EOS make its predictions more reliable than those obtained from purely empirical forms. PMID:16851652

Polishuk, Ilya; Vera, Juan H

2005-03-31

307

Theoretical and experimental investigations of fluctuation thermodynamic properties of liquid solutions  

NASA Astrophysics Data System (ADS)

Work has proceeded in the three areas of theory, correlation and experiment. The theoretical analyses have focussed on the statistical mechanical basis for the successful method for correlating liquid-phase activity coefficients of complex mixtures called solution of groups where the system is viewed as a mixture of groups rather than molecules and binary parameters are catalogued for the relatively small number of groups that make up the many molecules of petrochemical processing interest. From a correlation point of view, we have established a unique and simple form for the partial molar volume at infinite dilution of strong salts (e.g., NaCl) in water for all pressures and temperatures up to 350 C. In experiment, we have performed an analysis of the use of Rayleigh light scattering as a technique for obtaining thermodynamic properties of liquid mixtures.

Oconnell, J. P.

1987-02-01

308

Prediction of thermodynamic, transport and vapor–liquid equilibrium properties of binary mixtures of ethylene glycol and water  

Microsoft Academic Search

Equilibrium and non-equilibrium molecular dynamics and Monte Carlo simulation techniques were applied to predict various thermodynamic, transport and vapor–liquid equilibrium properties of binary mixtures of ethylene glycol and water (EG–W) based on OPLS-AA and SPC\\/E force fields. The properties predicted include density, vaporization enthalpy, enthalpy of mixing, heat capacities, diffusion coefficients, shear viscosities, thermal conductivities, vapor–liquid coexistence isotherms and isobaric

Jianxing Dai; Ling Wang; Yingxin Sun; Lin Wang; Huai Sun

2011-01-01

309

Thermodynamic properties of CF 3?CHF?CHF 2, 1,1,1,2,3,3-hexafluoropropane  

Microsoft Academic Search

We report the thermodynamic properties of 1,1,1,2,3,3-hexafluoropropane (known in the refrigeration industry as R236ea or HFC-236ea) in the temperature and pressure region commonly encountered in thermal machinery. The properties are based on measurements of the vapor pressure, the density of the compressed liquid (PVT), the refractive index of the saturated liquid and vapor, the critical temperature, and the speed of

D. R Defibaugh; K. A Gillis; M. R Moldover; J. W Schmidt; L. A Weber

1996-01-01

310

Thermodynamic and rheological properties of solid-liquid systems in coal processing. Final technical report  

SciTech Connect

The work on this project was initiated on September 1, 1991. The project consisted of two different tasks: (1) Development of a model to compute viscosities of coal derived liquids, and (2) Investigate new models for estimation of thermodynamic properties of solid and liquid compounds of the type that exist in coal, or are encountered during coal processing. As for task 1, a model for viscosity computation of coal model compound liquids and coal derived liquids has been developed. The detailed model is presented in this report. Two papers, the first describing the pure liquid model and the second one discussing the application to coal derived liquids, are expected to be published in Energy & Fuels shortly. Marginal progress is reported on task 2. Literature review for this work included compilation of a number of data sets, critical investigation of data measurement techniques available in the literature, investigation of models for liquid and solid phase thermodynamic computations. During the preliminary stages it was discovered that for development of a liquid or solid state equation of state, accurate predictive models for a number of saturation properties, such as, liquid and solid vapor pressures, saturated liquid and solid volumes, heat capacities of liquids and solids at saturation, etc. Most the remaining time on this task was spent in developing predictive correlations for vapor pressures and saturated liquid volumes of organic liquids in general and coal model liquids in particular. All these developments are discussed in this report. Some recommendations for future direction of research in this area are also listed.

Kabadi, V.N.

1995-06-30

311

Thermodynamic model for calorimetric and phase coexistence properties of coal derived fluids. Final technical report  

SciTech Connect

The work on this project was initiated on September 1, 1989. The project consisted of three different tasks. 1. A thermodynamic model to predict VLE and calorimetric properties of coal liquids. 2. VLE measurements at high temperature and high pressure for coal model compounds and 3. Chromatographic characterization of coal liquids for distribution of heteroatoms. The thermodynamic model developed is an extension of the previous model developed for VLE of coal derived fluids (DOE Grant no. FG22-86PC90541). The model uses the modified UNIFAC correlation for the liquid phase. Some unavailable UNIFAC interactions parameters have been regressed from experimental VLE and excess enthalpy data. The model is successful in predicting binary VLE and excess enthalpy data. Further refinements of the model are suggested. An apparatus for the high pressure high temperature VLE data measurements has been built and tested. Tetralin-Quinoline is the first binary system selected for data measurements. The equipment was tested by measuring 325{degree}C isotherm for this system and comparing it with literature data. Additional isotherms at 350{degree}C and 370{degree}C have been measured. The framework for a characterization procedure for coal derived liquids has been developed. A coal liquid is defined by a true molecular weight distribution and distribution of heteroatoms as a function of molecular weights. Size exclusions liquid chromatography, elemental analysis and FTIR spectroscopy methods are used to obtain the molecular weight and hetroatom distributions. Further work in this area should include refinements of the characterization procedure, high temperature high pressure VLE data measurements for selective model compound binary systems, and improvement of the thermodynamic model using the new measured data and consistent with the developments in the characterization procedure.

Kabadi, V.N.

1992-10-01

312

Thermodynamic and mechanical properties of crystalline CoSb3: A molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations have been performed to study the fundamental thermodynamic and mechanical properties of single-crystalline skutterudite CoSb3 in the nanometric scale. The several interesting thermodynamic predictions, including linear thermal expansion coefficient, specific heat capacity, thermal conductivity, and temperature dependence of elastic constants, show excellent agreement with data available in the literature. The classic mechanical tests of uniaxial tension and compression are performed respectively at constant temperatures. The CoSb3 single-crystal exhibits nonlinear elastic response during the deformation process and the sustainable stress is very high, demonstrating its outstanding stability. An interesting phenomenon occurs at compression that the stress-strain curve undergoes a transition. The cause of the transition is an atomic reconstruction, which is observed and interpreted on the basis of interatomic interactions. Both of the failure patterns under tension and compression reveal brittleness of the material. The increasing of temperature would result in a linear degradation of the effective Young's modulus and ultimate strength, but its effect on Poisson's ratio is negligible. The results provide the groundwork for future studies of service behavior of the skutterudites-based thermoelectric devices.

Yang, Xu-Qiu; Zhai, Peng-Cheng; Liu, Li-Sheng; Zhang, Qing-Jie

2011-06-01

313

Towards predictor based design of thermodynamic and kinetic properties of complex materials for hydrogen storage  

NASA Astrophysics Data System (ADS)

A calculational approach for the design of new complex materials for hydrogen storage with favorable thermodynamic stability and enhanced diffusion kinetics is presented. By combining density functional theory (DFT) calculations on stable crystal structures and local coordination models with database methods, we perform large-scale screening studies to determine a number of potential alloys/mixtures with favorable thermodynamic stabilities and identify simple descriptors for subsequent materials prediction. Predictors for the kinetic properties of the materials are derived from combining materials screening with path techniques and harmonic transition state theory (TST) to indentify materials parameters, e.g. the hydrogen binding energy, which correlate with the macroscopic diffusion rates. These predictors are then used to design new alloy/mixture compositions and ratios to favor structures with optimal diffusion kinetics. We present results from binary and ternary alkali-transition metal borohydrides and Perovskite based hydrogen permeable membranes, as well as results from studies of binary and mixed metal ammines. Results from the modeling of pathways and rates of dynamical processes involved in the ab-/desorption mechanisms will also be presented and compared to quasi elastic neutron scattering data.

Hummelshoej, Jens

2011-03-01

314

Atmospheric amines - Part II. Thermodynamic properties and gas/particle partitioning  

NASA Astrophysics Data System (ADS)

Amines enter the atmosphere from a wide range of sources, but relatively little is known about their atmospheric behavior, especially their role in gas/particle partitioning. In Part I of this work ( Ge et al., 2011) a total of 154 amines, 32 amino acids and urea were identified as occurring in the atmosphere, based upon a survey of the literature. In this work we compile data for the thermodynamic properties of the amines which control gas/particle partitioning (Henry's Law constant, liquid vapor pressure, acid dissociation constant, activity coefficient and solubility in water), and also estimate the solid/gas dissociation constants of their nitrate and chloride salts. Prediction methods for boiling point, liquid vapor pressure, acid dissociation constant and the solubility of the amines in water are evaluated, and used to estimate values of the equilibrium constants where experimental data are lacking. Partitioning of amines into aqueous aerosols is strongly dependent upon pH and is greatest for acidic aerosols. For several common amines the tendency to partition to the particle phase is similar to or greater than that of ammonia. Our results are presented as tables of values of thermodynamic equilibrium constants, which are also incorporated into the Extended Aerosol Inorganics Model ( E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) to enable gas/aerosol partitioning and other calculations to be carried out.

Ge, Xinlei; Wexler, Anthony S.; Clegg, Simon L.

2011-01-01

315

First-principles calculations of phase transition, elasticity, and thermodynamic properties for TiZr alloy  

NASA Astrophysics Data System (ADS)

Structural transformation, pressure dependent elasticity behaviors, phonon, and thermodynamic properties of the equiatomic TiZr alloy are investigated by using first-principles density-functional theory. Our calculated lattice parameters and equation of state for ? and ? phases as well as the phase transition sequence of ? ? ? ? ? are consistent well with experiments. Elastic constants of ? and ? phases indicate that they are mechanically stable. For cubic ? phase, however, it is mechanically unstable at zero pressure and the critical pressure for its mechanical stability is predicted to equal to 2.19 GPa. We find that the moduli, elastic sound velocities, and Debye temperature all increase with pressure for three phases of TiZr alloy. The relatively large B/G values illustrate that the TiZr alloy is rather ductile and its ductility is more predominant than that of element Zr, especially in ? phase. Elastic wave velocities and Debye temperature have abrupt increase behaviors upon the ? ? ? transition at around 10 GPa and exhibit abrupt decrease feature upon the ? ? ? transition at higher pressure. Through Mulliken population analysis, we illustrate that the increase of the d-band occupancy will stabilize the cubic ? phase. Phonon dispersions for three phases of TiZr alloy are firstly presented and the ? phase phonons clearly indicate its dynamically unstable nature under ambient condition. Thermodynamics of Gibbs free energy, entropy, and heat capacity are obtained by quasiharmonic approximation and Debye model.

Wang, Bao-Tian; Li, Wei-Dong; Zhang, Ping

2012-01-01

316

The High Pressure Superconductivity of CaLi2 Compound: The Thermodynamic Properties  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of the superconducting state in CaLi2 at 60 GPa have been described in the paper. The numerical analysis has been carried out in the framework of the Eliashberg formalism. It has been shown that: (i) the critical value of the Coulomb pseudopotential is equal to 0.20, which corresponds to the value of 1795 meV for the Coulomb potential; (ii) the critical temperature ( T C ) cannot be correctly calculated by using the Allen-Dynes (AD) formula; (iii) the dimensionless ratios: TCCN (TC )/H2C (0 ), ( C S ( T C )- C N ( T C ))/ C N ( T C ) and 2?(0)/ k B T C take the non-BCS values: 0.157, 1.78 and 3.85, respectively. The symbol C N represents the specific heat in the normal state, C S denotes the specific heat in the superconducting state, H C (0) is the thermodynamic critical field near the temperature of zero Kelvin, and ?(0) is the order parameter; (iv) the ratio of the electron effective mass (m^{star}e) to the electron band mass ( m e ) assumes a high value, in the whole range of the temperature, where the superconducting state exists. The maximum of m^{star}e/me is equal to 2.15 for T= T C .

Szcz??niak, R.; Durajski, A. P.; Pach, P. W.

2013-06-01

317

Thermodynamic and Transport Properties of Superconducting Mg{sup 10}B{sub 2}  

SciTech Connect

Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB{sub 2} superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, H{sub c2} , with magnetization data giving dH{sub c2}/dT=0.44 T/ K at the transition temperature of T{sub c}=40.2 K . Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1T. The value of dH{sub c}/dT at T{sub c} is estimated to be about 12 mT/K , a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter {kappa}{approx}26 . Estimates of the critical supercurrent density, J{sub c} , using hysteresis loops and the Bean model, give critical current densities on the order of 10{sup 5} A/cm {sup 2} . Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb{sub 3}Sn .

Finnemore, D. K.; Ostenson, J. E.; Bud'ko, S. L.; Lapertot, G.; Canfield, P. C.

2001-03-12

318

Thermodynamic properties of 9-methylcarbazole and 1,2,3,4-tetrahydro-9-methylcarbazole  

SciTech Connect

Removal of carbazole and its derivatives from heavy petroleum has proved to be particularly difficult using present technology. Studies have shown carbazole and its alkyl-homologs are the dominant nitrogen-containing components in clarified slurry oils, thereby indicating their low reactivity and/or formation during cat-cracking processes. The results reported here will point the way to the development of new methods of nitrogen removal from carbazole and its derivatives. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for 9-methylcarbazole and 1,2,3,4-tetrahydro-9-methylcarbazole. For studies on 1,2,3,4-tetrahydro-9-methylcarbazole experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, vibrating-tube densitometry, comparative ebulliometry, inclined-piston gauge manometry, and differential-scanning calorimetry (d.s.c.). Adiabatic heat-capacity and combustion calorimetric studies were reported previously for 9-methylcarbazole. Vapor pressures by comparative ebulliometry and inclined-piston gauge manometry, and heat-capacities for the liquid phase by d.s.c. are reported here. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 298.15 K and near 700 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathway of the initial hydrogenation step in the carbazole/H{sub 2} hydrodenitrogenation network. 52 refs., 9 figs., 15 tabs.

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

1991-04-01

319

Seismic properties of the Kohistan oceanic arc root: Insights from laboratory measurements and thermodynamic modeling  

NASA Astrophysics Data System (ADS)

P-wave velocities (Vp) have been measured in the laboratory and calculated using thermodynamic modeling for seven representative rock samples from the lower crust to mantle section of the Kohistan paleo-island arc. Lower crustal rocks comprise plagioclase-rich gabbro, garnet-bearing gabbro, and hornblendite; mantle rocks comprise garnetite, pyroxenite, websterite, and dunite. Measurements were performed at confining pressures up to 0.5 GPa and temperatures up to 1200°C. Vp were also calculated using rock major element chemistry with the Perple_X software package. Calculated Vp match closely the laboratory measurements. At depths representative for the arc root, Vp of upper mantle rocks vary from 7.7-8.1 km/s, whereas the lower crustal rocks have velocities between 6.9-7.5 km/s. P-wave anisotropy is small, with exceptions of sheared gabbros. Measured and calculated seismic properties are consistent with, and complement a growing database of published seismic properties from the Kohistan arc. In the light of such data, we discuss seismic imaging of present-day island arcs. Intermediate Vp (7.4-7.7 km/s) in arc roots can be explained by pyroxenites and garnet-bearing mafic rocks. Strong seismic reflectors may be related to garnetites (8.0-8.2 km/s).

Almqvist, B. S. G.; Burg, J.-P.; Berger, J.; Burlini, L.

2013-06-01

320

First-principles calculations on the elastic and thermodynamic properties of NbN  

NASA Astrophysics Data System (ADS)

The elastic and thermodynamic properties of NbN at high pressures and high temperatures are investigated by the plane-wave pseudopotential density functional theory (DFT). The generalized gradient approximation (GGA) with the Perdew—Burke—Ernzerhof (PBE) method is used to describe the exchange—correlation energy in the present work. The calculated equilibrium lattice constant a0, bulk modulus B0, and the pressure derivative of bulk modulus B'0 of NbN with rocksalt structure are in good agreement with numerous experimental and theoretical data. The elastic properties over a range of pressures from 0 to 80.4 GPa are obtained. Isotropic wave velocities and anisotropic elasticity of NbN are studied in detail. It is indicated that NbN is highly anisotropic in both longitudinal and shear-wave velocities. According to the quasi-harmonic Debye model, in which the phononic effect is considered, the relations of (V - V0)/V0 to the temperature and the pressure, and the relations of the heat capacity Cv and the thermal expansion coefficient ? to temperature are discussed in a pressure range from 0 to 80.4 GPa and a temperature range from 0 to 2500 K. At low temperature, Cv is proportional to T3 and tends to the Dulong—Petit limit at higher temperature. We predict that the thermal expansion coefficient ? of NbN is about 4.20 × 10-6/K at 300 K and 0 GPa.

Ren, Da-Hua; Cheng, Xin-Lu

2012-12-01

321

Biomolecules in hydrothermal systems: Calculation of the standard molal thermodynamic properties of nucleic-acid bases, nucleosides, and nucleotides at elevated temperatures and pressures  

Microsoft Academic Search

Calculation of the thermodynamic properties of biomolecules at high temperatures and pressures is fundamental to understanding the biogeochemistry of hydrothermal systems. Ample evidence indicates that hyperthermophilic microbes interact chemically with their mineralogical environment in these systems. Nevertheless, little is known about the thermodynamic properties of the biomolecules involved in such processes. Recent advances in theoretical biogeochemistry make it possible to

Douglas E. Larowe; Harold C. Helgeson

2006-01-01

322

A thermodynamic property formulation for ethylene from the freezing line to 450 K at pressures to 260 MPa  

Microsoft Academic Search

A new thermodynamic property formulation based upon a fundamental equation explicit in Helmholtz energy of the form A=A(?, T) for ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. A vapor pressure equation, equations for the saturated liquid and vapor densities as functions of temperature, and an equation for the ideal-gas heat capacity are

M. Jahangiri; R. T. Jacobsen; R. B. Stewart; R. D. McCarty; H. J. M. Hauley; A. Cezairliyan

1986-01-01

323

A thermodynamic property formulation for ethylene from the freezing line to 450 K at pressures to 260 MPa  

Microsoft Academic Search

A new thermodynamic property formulation based upon a fundamental equation explicit in Helmholtz energy of the form A= A( rho, T) for ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. A vapor pressure equation, equations for the saturated liquid and vapor densities as functions of temperature, and an equation for the ideal-gas heat

M. Jahangiri; R. T. Jacobsen; R. B. Stewart; R. D. McCarty

1986-01-01

324

Gas transport and thermodynamic properties of PMMA\\/PVME blends containing PS-b-PMMA as a compatibilizer  

Microsoft Academic Search

Gas transport and thermodynamic properties of polymethylmethacrylate (PMMA) blended with polyvinylmethylether (PVME) containing diblock copolymer of styrene and methylmethacrylate (PS-b-PMMA) as a compatibilizer were studied. Phase separation temperatures of PVME blends with styrenic random copolymer containing various amounts of methyl methacrylate (MMA) were determined to calculate the interaction energies of the binary pairs involved in this system using lattice fluid

E. J. Moon; J. E. Yoo; H. W. Choi; C. K. Kim

2002-01-01

325

Mass Spectrometric Study of the Thermodynamic Properties of Melts in the Rb 2 O–B 2 O 3 System  

Microsoft Academic Search

The vaporization and thermodynamic properties (activities of the components and Gibbs energies) of melts in the Rb2O–B2O3 system at a B2O3 content varying from 66.7 to 92.0 mol % are investigated by high-temperature differential mass spectrometry upon evaporation from molybdenum cells in the temperature range 950–1350 K.

V. L. Stolyarova; S. I. Lopatin

2004-01-01

326

Calculation of the Standard Molal Thermodynamic Properties of Crystalline, Liquid, and Gas Organic Molecules at High Temperatures and Pressures  

Microsoft Academic Search

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

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

1998-01-01

327

Thermodynamic properties of R32 + R134a and R125 + R32 mixtures in and beyond the critical region  

Microsoft Academic Search

A parametric crossover equation of state for pure fluids is adapted to binary mixtures. This equation incorporates scaling laws asymptotically close to the critical point and is transformed into a regular classical expansion far away from the critical point. An isomorphic generalization of the law of corresponding states is applied to the prediction of thermodynamic properties and the phase behavior

S. B Kiselev; M. L Huber

1998-01-01

328

Theoretical insight of physical adsorption for a single-component adsorbent+adsorbate system: I. Thermodynamic property surfaces.  

PubMed

Thermodynamic property surfaces for a single-component adsorbent+adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl2-in-silica gel+water system for cooling applications, and (ii) activated carbon (Maxsorb III)+methane system for gas storage. PMID:19140706

Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

2009-02-17

329

Thermodynamic properties of aqueous gadolinium perrhenate and gadolinium chloride from high dilution calorimetry at extreme temperatures and pressures.  

PubMed

The heat of solution of solid cubic gadolinium oxide has been measured in noncomplexing perrhenic acid solutions at very high dilutions (10(-4) m) up to 596.30 K, from which the standard state thermodynamic properties of aqueous gadolinium perrhenate were determined up to 623.15 K. From the measured differences between similar properties of aqueous sodium chloride and perrhenate, thermodynamic properties for aqueous gadolinium chloride were obtained by ionic additivity. Data for the hydrolysis of Gd3+(aq) were obtained by separate determinations. The enthalpy of solution of gadolinium chloride at 623.15 K obtained from this research (-2.7 MJ mol(-1)) is apparently larger than any other recorded for a chemical reaction involving aqueous systems. Standard state partial molal heat capacities for ThCl4(aq) were predicted up to 623.15 K. PMID:19191504

Djamali, Essmaiil; Cobble, James W

2009-02-26

330

Ab initio calculations of structure and thermodynamic properties of tetragonal-TiH2 under high temperatures and pressures  

NASA Astrophysics Data System (ADS)

The structural and thermodynamic properties of tetragonal-TiH2 under high temperatures and pressures are investigated by Ab initio calculations based on pseudo-potential plane-wave density functional theory method within using the generalized gradient approximation (GGA) and quasi-harmonic Debye model. Some ground state properties such as lattice constants, bulk modulus and elastic constants are good agreement with the available experimental results and other theoretical data. Through the quasiharmonic Debye model, in which the phononic effects are considered, the thermodynamic properties of tetragonal-TiH2 such as thermal expansion coefficient, Debye temperature, heat capacity and Grüneisen parameters dependence of temperature and pressure in the range of 0-1000 K and 0-10 GPa are also presented, respectively.

Liu, X. K.; Tang, B.; Zhang, Y.

2013-10-01

331

Thermodynamic properties of autunite, uranyl hydrogen phosphate, and uranyl orthophosphate from solubility and calorimetric measurements  

SciTech Connect

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

332

Thermodynamic properties of carbides in 2.25Cr-1Mo steel at 985 K  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of carbides present in 2.25Cr-lMo steel were determined at 985 K by a gas flowing method with fixed CH4/H2 gas mixtures and by a silica capsule method with reference alloys. The carbon activity range was from 0.06 to 0.5. Total carbon content, carbide species, and Cr and Mo partitionings between the matrix and carbides were measured as a function of the carbon activity. Both M6C and M23C6 carbides were present after 1000 to 3000 hours at the test temperature and in the carbon activity range studied. The amount of M6C was greater in the low carbon activity range, while M23C6 carbide became the major carbide with increasing carbon activity. The M6C carbide contained Mo as a major element and Cr and Si as minor elements; approximately 13 pct of the metal constituent was (Cr + Si). The stability of M6C carbide in this steel is significantly higher than M6C formed in the Fe-Mo-C system. The M23C6 carbide contained Cr as a major metal component and Mo as a minor. The M23C6 carbide is more stable in an extended range of the carbon activity in 2.25Cr-lMo steel than in the Fe-Cr-C system. The presence of Si is apparently low in M23C6. Thermodynamic parameters were computed for M6C and M23C6 carbides using a regular solution model of component carbides, FeCx, CrCx, and MoCx.

Wada, Harue

1986-09-01

333

Thermodynamic properties of Pt nanoparticles: Size, shape, support, and adsorbate effects  

NASA Astrophysics Data System (ADS)

This study presents a systematic investigation of the thermodynamic properties of free and ?-Al2O3-supported size-controlled Pt nanoparticles (NPs) and their evolution with decreasing NP size. A combination of in situ extended x-ray absorption fine-structure spectroscopy (EXAFS), ex situ transmission electron microscopy (TEM) measurements, and NP shape modeling revealed (i) a cross over from positive to negative thermal expansion with decreasing particle size, (ii) size- and shape-dependent changes in the mean square bond-projected bond-length fluctuations, and (iii) enhanced Debye temperatures (?D, relative to bulk Pt) with a bimodal size-dependence for NPs in the size range of ˜0.8-5.4 nm. For large NP sizes (diameter d >1.5 nm) ?D was found to decrease toward ?D of bulk Pt with increasing NP size. For NPs ? 1 nm, a monotonic decrease of ?D was observed with decreasing NP size and increasing number of low-coordinated surface atoms. Our density functional theory calculations confirm the size- and shape-dependence of the vibrational properties of our smallest NPs and show how their behavior may be tuned by H desorption from the NPs. The experimental results can be partly attributed to thermally induced changes in the coverage of the adsorbate (H2) used during the EXAFS measurements, bearing in mind that the interaction of the Pt NPs with the stiff, high-melting temperature ?-Al2O3 support may also play a role. The calculations also provide good qualitative agreement with the trends in the mean square bond-projected bond-length fluctuations measured via EXAFS. Furthermore, they revealed that part of the ?D enhancement observed experimentally for the smallest NPs (d ? 1 nm) might be assigned to the specific sensitivity of EXAFS, which is intrinsically limited to bond-projected bond-length fluctuations.

Roldan Cuenya, B.; Alcántara Ortigoza, M.; Ono, L. K.; Behafarid, F.; Mostafa, S.; Croy, J. R.; Paredis, K.; Shafai, G.; Rahman, T. S.; Li, L.; Zhang, Z.; Yang, J. C.

2011-12-01

334

First-principles study on thermodynamic properties and phase transitions in TiS(2).  

PubMed

Structural and vibrational properties of TiS(2) with the CdI(2) structure have been studied to high pressures from density functional calculations with the local density approximation (LDA). The calculated axial compressibility of the CdI(2)-type phase agrees well with experimental data and is typical of layered transition-metal dichalcogenides. The obtained phonon dispersions show a good correspondence with available experiments. A phonon anomaly is revealed at 0 GPa, but is much reduced at 20 GPa. The thermodynamic properties of this phase were also calculated at high pressures and high temperatures using the quasi-harmonic approximation. Our LDA study on the pressure-induced phase transition sequence predicts that the CdI(2)-type TiS(2), the phase stable at ambient conditions, should transform to the cotunnite phase at 15.1 GPa, then to a tetragonal phase (I4/mmm) at 45.0 GPa. The tetragonal phase remains stable to at least 500 GPa. The existence of the tetragonal phase at high pressures is consistent with our previous findings in NiS(2) (Yu and Ross 2010 J. Phys.: Condens. Matter 22 235401). The cotunnite phase, although only stable in a narrow pressure range between 15.1 and 45.0 GPa, displays the formation of a compact S network between 100 and 200 GPa, which is evidenced by a kink in the variation of unit cell lengths with pressure. The electron density analysis in cotunnite shows that valence electrons are delocalized from Ti atoms and concentrated near the S network. PMID:21406908

Yu, Yonggang G; Ross, Nancy L

2011-01-19

335

Magnetic and thermodynamical properties of the simple-cubic Hubbard model  

NASA Astrophysics Data System (ADS)

Magnetic and thermodynamical properties of the half-filled Hubbard model on the simple-cubic lattice have been investigated by using the two analytical theories for band magnetism: the single-site spin fluctuation (SSF) theory proposed independently by Hubbard and Hasegawa and the Gutzwiller-type variational approach (VA) developed by Kakehashi and Fulde. We have calculated, as a function of the temperature T and the electron-electron interaction U, the sublattice magnetization, amplitude of local moments, susceptibilities, energy, and entropy, from which the U-T phase diagram is obtained. Our ground-state results, particularly of the VA, are in good agreement with those obtained in the variational Monte Carlo calculations performed by Yokoyama and Shiba. Our finite-temperature calculations are compared with those in the recent Monte Carlo (MC) simulations made by Hirsch. It is shown that, as far as local quantities such as the amplitude of local moments and the Curie constants are concerned, our results are consistent with the MC results. It is realized, however, that the antiferromagnetic correlation is much overestimated in a small 4×4×4 cluster in Hirsch's MC simulation, yielding Néel temperatures, TN, about 70% higher than those in the mean-field-type theories of the SSF and VA approaches.

Kakehashi, Yoshiro; Hasegawa, Hideo

1988-05-01

336

Determination of thermodynamic properties of ternary Al-Cu-Zn alloys by electromotive force method  

SciTech Connect

The thermodynamic properties of ternary Al-Cu-Zn alloys containing 25 to 62 at % Al have been determined by electromotive force (EMF) measurements between 420 and 920 C by an aluminum concentration cell of the type Al[AlCl[sub 3]-LiCl-KC1] alloy. This concentration cell was evaluated via comparison with known partial free energy for Al measured in liquid Al-Cu alloys by Wilder, and several liquidus temperatures of Al-Cu phase diagram have been determined. From EMF values, activities of Al with respect to mole fraction of Al in ternary Al-Cu-Zn alloys for three quasi-binary sections (x[sub cu]/x[sub zn] = 7/3, 1, and 3/7) at 850 C were determined. The negative deviation from Raoultian behavior observed was more pronounced at high x[sub cu]/x[sub zn] ratios in agreement with binary Al-Zn and Al-Cu phase diagrams.

Van, T.D.; Winand, R. (Univ. Libre de Bruxelles, Brussels (Belgium). Dept. of Metallurgy-Electrochemistry)

1994-04-01

337

Structural and Thermodynamic Properties of TiAl intermetallics under High Pressure  

NASA Astrophysics Data System (ADS)

The structural and thermodynamic properties of TiAl intermetallics under high pressure have been investigated by ab initio plane-wave pseudopotential density functional theory method. It is found that the ratio of lattice parameter c to a keeps almost constant with a value of 1.02 under the pressure from 0 to 20 GPa, which agrees well with the experimental results. With the pressure increasing from 20 to 45 GPa the values of c/a decrease almost linearly from 1.02 to 0.99. These calculated results indicate under low pressure the variation rate for a-axis is almost the same to that for c-axis, but under higher pressure the variation for a-axis is smaller than along c-axis. Through the quasi-harmonic Debye model, the equation of state (EOS) of TiAl intermetallics, as well as the thermal expansion and heat capacity at various pressures and temperatures are also studied.

Li, Xu-Sheng; Wang, Hai-Yan; Li, Chang-Yun; Mi, Guo-Fa; Hu, Qian-Ku

2012-01-01

338

Phase diagram of oxygen adsorbed on Ni(111) and thermodynamic properties from first-principles  

NASA Astrophysics Data System (ADS)

The thermodynamic properties and the surface phase diagram of O/Ni(111) have been calculated from Metropolis and Wang-Landau Monte Carlo simulations based on lateral interactions derived from density-functional theory (DFT) calculations. The DFT energies were mapped onto an Ising-like Hamiltonian according to the cluster expansion technique formalism. Both fcc and hcp adsorption sites were included in the Hamiltonian. Different criteria were used to evaluate competing parameter sets: cross-validation score CV, Mallow’s Cp statistics, and adjusted R2 statistics. The parameter space was searched using genetic algorithms in order to find optimum parameter sets. The different parameter sets obtained from different criteria lead essentially to the same transition temperatures. Excellent agreement is found when comparing the shape and the stability regions of the theoretical and the experimental (from the literature) phase diagrams. We investigate the nature of the p(2×2) and (3×3)R30° phase transitions at ?=1/4 and 1/3 ML, respectively. Differences arise when comparing the values of the calculated and the experimental transition temperatures owing to imprecision in present-day DFT calculations.

Lazo, C.; Keil, F. J.

2009-06-01

339

Influence of Alloying Elements on the Thermodynamic Properties of Titanium in Molten Steel  

NASA Astrophysics Data System (ADS)

The influences of alloying elements of chromium, nickel, manganese, molybdenum, copper, and oxygen on the thermodynamic property of titanium in molten iron were investigated at 1873 K to improve control of the formation of titanium compounds in the steelmaking processes. At a certain titanium potential controlled by the coexistence of Ti3O5 and Ti2O3 with steel, the interaction parameters between alloying elements and titanium in molten iron were determined as follows. \\varepsilon ^{{{text{Mn}}}}_{{{text{Ti}}}} = - 27.4( ± 0.66),quad \\varepsilon ^{{{text{Cr}}}}_{{{text{Ti}}}} = 5.33( ± 0.84),quad \\varepsilon ^{{{text{Ni}}}}_{{{text{Ti}}}} = - 3.93( ± 0.51),quad \\varepsilon ^{{{text{Mo}}}}_{{{text{Ti}}}} = 5.76( ± 0.69),quad \\varepsilon ^{{{text{Cu}}}}_{{{text{Ti}}}} = 3.44( ± 0.69) Through the investigation of titanium deoxidation equilibria in molten iron, the activity coefficient of titanium and the first-order interaction parameter between oxygen and titanium were determined as follows: ? _{{{text{Ti}}}}^{ circ} = 0.0215(±0.00062),quad \\varepsilon ^{{{text{Ti}}}}_{{text{O}}} = - 160(±10) Also, titanium deoxidation of molten 304 stainless steel was measured and compared with the calculated results using the determined interaction parameters.

Yoshikawa, Takeshi; Morita, Kazuki

2007-08-01

340

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

341

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

342

Physical Properties Models for Simulation of Processes to Treat INEEL Tank Farm Waste: Thermodynamic Equilibrium  

SciTech Connect

A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.

Nichols, T.T.; Taylor, D.D.

2002-07-18

343

A simple analysis of thermodynamic properties for classical plasmas: I. Theory  

NASA Astrophysics Data System (ADS)

By eliminating the short range negative divergence of the Debye-Hückel pair distribution function, but retaining the exponential charge screening known to operate at large interparticle separation, the thermodynamic properties of one-component plasmas of point ions or charged hard spheres can be well represented even in the strong coupling regime. Predicted electrostatic free energies agree within 5% of simulation data for typical Coulomb interactions up to a factor of 10 times the average kinetic energy. Here, this idea is extended to the general case of a uniform ionic mixture, comprising an arbitrary number of components, embedded in a rigid neutralizing background. The new theory is implemented in two ways: (i) by an unambiguous iterative algorithm that requires numerical methods and breaks the symmetry of cross correlation functions; and (ii) by invoking generalized matrix inverses that maintain symmetry and yield completely analytic solutions, but which are not uniquely determined. The extreme computational simplicity of the theory is attractive when considering applications to complex inhomogeneous fluids of charged particles.

Penfold, Robert; Nordholm, Sture; Nichols, Nancy

2005-06-01

344

The thermodynamic and hydrodynamic properties of macromolecules that influence the hydrodynamics of porous systems.  

PubMed

The water flow across porous, semipermeable membranes associated with osmosis and filtration under a variety of conditions is analysed and compared to macromolecular diffusion across free-liquid boundaries, diffusion and sedimentation in the ultracentrifuge, and tracer diffusion of water. This study establishes that osmosis can be explained in terms of the irreversible thermodynamics of diffusion. For macromolecular osmotically active solutes in the semidilute concentration regime the water flows across semipermeable porous membranes are interpreted in terms of a rate-limiting solute-solvent exchange layer that exists on the solution side of the membrane adjacent to the membrane pore; both osmosis and filtration will be governed by these exchange layers. These exchange layers also yield unique properties of their constituent molecules in systems where there is osmotic equilibration between solutions of different solutes. This study also establishes the need to consider the internal osmotic pressure of membranes in the pressure balance associated with the flow across the membrane. The complex situation of partially permeable membranes is analysed for the simple case where there are no mechanical gradients and there is only one osmotically active solution that creates a rate-limiting exchange layer. This treatment predicts that the flow will be governed primarily by the osmotic pressure difference associated with the partitioning of the solute at the membrane-solution interface. PMID:8072300

Comper, W D

1994-06-21

345

Phonon spectrum, thermodynamic properties, and pressure-temperature phase diagram of uranium dioxide  

NASA Astrophysics Data System (ADS)

We present a study of the structural phase transition and the mechanical and thermodynamic properties of UO2 by means of the local density approximation (LDA)+U approach. A phase transition pressure of 40 GPa is obtained from theory at 0 K, and agrees well with the experimental value of 42 GPa. The pressure-induced enhancements of elastic constants, elastic moduli, elastic wave velocities, and Debye temperature of the ground-state fluorite phase are predicted. The phonon spectra of both the ground state fluorite structure and high-pressure cotunnite structure calculated by the supercell approach show that the cotunnite structure is dynamically unstable under ambient pressure. Based on the imaginary mode along the ?-X direction and soft phonon mode along the ?-Z direction, a transition path from cotunnite to fluorite has been identified. We calculate the lattice vibrational energy in the quasiharmonic approximation using both first-principles phonon density of state and the Debye model. The calculated temperature dependence of lattice parameter, entropy, and specific heat agrees well with experimental observations in the low temperature domain. The difference of the Gibbs free energy between the two phases of UO2 has predicted a boundary in the pressure-temperature phase diagram. The solid-liquid boundary is approximated by an empirical equation using our calculated elastic constants.

Wang, Bao-Tian; Zhang, Ping; Lizárraga, Raquel; Di Marco, Igor; Eriksson, Olle

2013-09-01

346

Thermodynamic properties and equations of state for Ag, Al, Au, Cu and MgO using a lattice vibrational method  

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

347

An equation of state for the thermodynamic properties of R143a (1,1,1-trifluoroethane)  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of 1,1,1-trifluoroethane (R143a) are expresed in terms of a 32-term modified Benedict-Webb-Rubin (MBWR) equation of state. Coefficients are reported for the MBWR equation and for ancillary equations used to lit the ideal-gas heat capacity, and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined from a multiproperty fit that used the following types of experimental data: PVT: isochoric, isobaric, and saturated-liquid heat capacities: second virial coefficients: speed of sound and properties at coexistence. The equation of state was optimized to the experimental data from 162 to 346 K and pressures to 35 MPa with the exception of the critical region. Upon extrapolation to 500 K and 60 MPa, the equation gives thermodynamically reasonable results. Comparisons between calculated and experimental values are presented.

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

1997-11-01

348

Thermodynamic properties of the one-dimensional extended quantum compass model in the presence of a transverse field  

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

349

First-principles study of the elastic and thermodynamic properties of CaSiO(3) perovskite.  

PubMed

The thermodynamic and elastic properties of CaSiO(3) perovskite are investigated at high pressures and temperatures using the plane wave pseudopotential method within the local density approximation. The athermal elastic moduli of CaSiO(3) perovskite are calculated as a function of pressure up to 200 GPa. The calculated results are in excellent agreement with available experimental data at high pressure, and compare favourably with other pseudopotential predictions over the pressure regime studied. It is also found that the elastic anisotropy drops rapidly with the increase of pressure initially, and then decreases more slowly at higher pressures. The thermodynamic properties of CaSiO(3) perovskite are predicted using the quasi-harmonic Debye model for the first time; the heat capacity and the thermal expansion coefficient agree with the observed values at ambient conditions and the other calculations at high pressures and temperatures. PMID:21694039

Liu, Z J; Sun, X W; Chen, Q F; Cai, L C; Wu, H Y; Ge, S H

2007-05-09

350

Thermodynamics with density and temperature dependent particle masses and properties of bulk strange quark matter and strangelets  

SciTech Connect

Thermodynamic formulas for investigating systems with density- and/or temperature-dependent particle masses are generally derived from the fundamental derivation equality of thermodynamics. Various problems in the previous treatments are discussed and modified. Properties of strange quark matter in bulk and strangelets at both zero and finite temperature are then calculated based on the new thermodynamic formulas with a new quark mass scaling, which indicates that low-mass strangelets near {beta} equilibrium are multiquark states with an antistrange quark, such as the pentaquark (u{sup 2}d{sup 2}s) for baryon number 1 and the octaquark (u{sup 4}d{sup 3}s) for dibaryon, etc.

Wen, X.J. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Zhong, X.H. [Department of Physics, Nankai University, Tianjin 300071 (China); Peng, G.X. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Shen, P.N. [China Center of Advanced Science and Technology (World Lab.), Beijing 100080 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Ning, P.Z. [China Center of Advanced Science and Technology (World Lab.), Beijing 100080 (China); Department of Physics, Nankai University, Tianjin 300071 (China)

2005-07-01

351

An equation of state for the thermodynamic properties of R143a (1,1,1-trifluoroethane)  

Microsoft Academic Search

Thermodynamic properties of 1,1,1-trifluoroethane (R143a) are expresed in terms of a 32-term modified Benedict-Webb-Rubin\\u000a (MBWR) equation of state. Coefficients are reported for the MBWR equation and for ancillary equations used to lit the ideal-gas\\u000a heat capacity, and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined\\u000a from a multiproperty fit that used the following types

S. L. Outcalt; M. O. McLinden

1997-01-01

352

An equation of state for the thermodynamic properties of R143a (1,1,1-trifluoroethane)  

Microsoft Academic Search

Thermodynamic properties of 1,1,1-trifluoroethane (R143a) are expresed in terms of a 32-term modified Benedict-Webb-Rubin (MBWR) equation of state. Coefficients are reported for the MBWR equation and for ancillary equations used to lit the ideal-gas heat capacity, and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined from a multiproperty fit that used the following types

S. L. Outcalt; M. O. McLinden

1997-01-01

353

Second-order thermodynamic derivative properties of selected mixtures by the soft-SAFT equation of state  

Microsoft Academic Search

We have discussed the capability of the soft-SAFT equation of state (EoS) to predict second order thermodynamic derivative properties of pure fluids in a recent paper [F. Llovell, L.F. Vega, J. Phys. Chem. B 110 (2006) 11427–11437]. The goal of this work is to extend these calculations to selected binary mixtures. The equation was applied in a semi-predictive manner: the

F. Llovell; C. J. Peters; L. F. Vega

2006-01-01

354

Thermodynamic Properties of the Mixtures R23\\/R744 and R41\\/R744 and their Efficiency as Refrigerants  

Microsoft Academic Search

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

355

Thermodynamic properties of Sr-doped LaMnOâ perovskite in the La-Sr-Mn-O system  

Microsoft Academic Search

Thermodynamic properties of Sr-doped perovskite-type lanthanum manganites (LSM) were generated by measuring the electromotive force (EMF) of test materials, using the solid galvanic cell technique. The cell consisted of an anode (SrO\\/SrFâ), an electrolyte (CaFâ or SrFâ) and a cathode (LSM\\/SrFâ). Two types of cells were tested in which type 1 used a CaFâ electrolyte and type 2 used a

Feng Zheng; L. R. Pederson

1999-01-01

356

Derivation of empirical equations for thermodynamic properties of a ozone safe refrigerant (R404a) using artificial neural network  

Microsoft Academic Search

This study, deals with the potential application of the artificial neural networks (ANNs) to represent PVTx (pressure-specific volume–temperature–vapor quality) data in the range of temperature of 173–498K and pressure of 10–3600kPa. Generally, numerical equations of thermodynamic properties are used in the computer simulation analysis instead of analytical differential equations. And also analytical computer codes usually require a large amount of

Adnan Sözen; Erol Arcaklioglu; Tayfun Menlik

2010-01-01

357

Thermodynamic and transport combustion properties of hydrocarbons with air. Part 2: Compositions corresponding to Kelvin temperature schedules in part 1  

SciTech Connect

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

358

An investigation of high temperature thermodynamic properties in the Pt-Zr and Pt-Hf systems  

Microsoft Academic Search

High-temperature thermodynamic properties of Pt?Zr alloys containing 2 to 25 at. pct Zr and Pt?Hf alloys containing 20 to\\u000a 25 at. pct Hf have been measured over the temperature range 1100 to 1400 K by a galvanic cell technique using a thoria-based\\u000a electrolyte. Activities of Zr and Hf show large negative deviations from Raoult's Law; at 1300 K and 23

P. J. Meschter; W. L. Worrell

1977-01-01

359

An investigation of high temperature thermodynamic properties in the Pt-Zr and Pt-Hf systems  

Microsoft Academic Search

High-temperature thermodynamic properties of Pt-Zr alloys containing 2 to 25 at. pct Zr and Pt-Hf alloys containing 20 to 25 at. pct Hf have been measured over the temperature range 1100 to 1400 K by a galvanic cell technique using a thoria-based electrolyte. Activities of Zr and Hf show large negative deviations from Raoult's Law; at 1300 K and 23

P. J. Meschter; W. L. Worrell

1977-01-01

360

The influence of locked nucleic acid residues on the thermodynamic properties of 20-O-methyl RNA\\/RNA heteroduplexes  

Microsoft Academic Search

The influence of locked nucleic acid (LNA) residues on the thermodynamic properties of 20-O-methyl RNA\\/RNA heteroduplexes is reported. Optical melting studies indicate that LNA incorporated into an other- wise 20-O-methyl RNA oligonucleotide usually, but not always, enhances the stabilities of complemen- tary duplexes formed with RNA. Several trends are apparent, including: (i) a 30 terminal U LNA and 50 terminal

Elzbieta Kierzek; Anna Ciesielska; Karol Pasternak; David H. Mathews; Douglas H. Turner; Ryszard Kierzek

361

Site-specifically located 8-amino-2'-deoxyguanosine: thermodynamic stability and mutagenic properties in Escherichia coli.  

PubMed

2-Nitropropane (2-NP), an important industrial solvent and a component of cigarette smoke, is mutagenic in bacteria and carcinogenic in rats. 8-Amino-2'-deoxyguanosine (8-amino-dG) is one of the types of DNA damage found in liver, the target organ in 2-NP-treated rats. To investigate the thermodynamic properties of 8-amino-dG opposite each of the four DNA bases, we have synthesized an 11mer, d(CCATCG*CTACC), in which G* represents the modified base. By annealing a complementary DNA strand to this modified 11mer, four sets of duplexes were generated each containing one of the four DNA bases opposite the lesion. Circular dichroism studies indicated that 8-amino-dG did not alter the global helical properties of natural right-handed B-DNA. The thermal stability of each duplex was examined by UV melting measurements and compared with its unmodified counterpart. For the unmodified 11mer, the relative stability of the complementary DNA bases opposite G was in the order C > T > G > A, as determined from their -DeltaG degrees values. The free energy change of each modified duplex was lower than its unmodified counterpart, except for the G*:G pair that exhibited a higher melting transition and a larger -DeltaG degrees than the G:G duplex. Nevertheless, the stability of the modified 11mer duplex also followed the order C > T > G > A when placed opposite 8-amino-dG. To explore if 8-amino-dG opposite another 8-amino-dG has any advantage in base pairing, a G*:G* duplex was evaluated, which showed that the stability of this duplex was similar to the G*:G duplex. Mutagenesis of 8-amino-dG in this sequence context was studied in Escherichia coli, which showed that the lesion is weakly mutagenic (mutation frequency approximately 10(-3)) but still can induce a variety of targeted and semi-targeted mutations. PMID:11266546

Venkatarangan, L; Sivaprasad, A; Johnson, F; Basu, A K

2001-04-01

362

EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL  

SciTech Connect

This final technical report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period September 24, 1996 to September 23, 1999 which covers the entire performance period of the project. During this period, modification, alignment, and calibration of the measurement system, measurement of devolatilization time-scales for single coal particles subjected to a range of heating rates and temperature data at these time-scales, and analysis of the temperature data to understand the effect of heating rates on coal thermal properties were carried out. A new thermodynamic model was developed to predict the heat transfer behavior for single coal particles using one approach based on the analogy for thermal property of polymers. Results of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 5} K/s. At these heating rates during the early stages of heating, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatilization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are a few data available in the coal literature for low heating rate experiments (10{sup 2}-10{sup 3} K/s) conducted by UTRC, our industrial partner, in this project. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time of the single particle experiments discussed above. The polymer analogy model was modified to include longer heating time on the order of several seconds to test these data. However, the model failed to predict these low heating rate data. It should be noted that UTRC's work showed reasonably good agreement with Merrick model heat capacity predictions at these low heating rates, but at higher heating rates UTRC observed that coal thermal response was heat flux dependent. It is concluded that at combustion level heating rates (10{sup 4}-10{sup 5} K/s) coal structural changes are delayed and attendant increases in heat capacity and thermal conductivity are pushed to higher temperatures or require significant hold times to become manifest.

Ramanathan Sampath

2000-01-01

363

An IR and Calorimetric Investigation of the Structural, Crystal-Chemical and Thermodynamic Properties of Hydrogrossular  

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

364

Relating Convective and Microphysical Properties to Large-scale Dynamical and Thermodynamical processes within Tropical Cyclones  

NASA Astrophysics Data System (ADS)

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 of Tropical Convection (YOTC) program. In this study, a combination of cloud resolving model (CRM) simulations, TRMM Microwave Imager (TMI) measurements, NOAA Optimum Interpolation sea surface temperatures (SST), and Global Forecasting System (GFS) analysis are used to address this issue. The University of Wisconsin Nonhydrostatic Modeling System (UWNMS), a CRM, is used to simulate hurricanes Dennis (9-10 July 2005), Katrina (29-30 2005), and Gustav (30-31 August 2008) at 2-km resolution, nested within 1ºx1º GFS analyses. The UWNMS-generated thermodynamic and hydrometeor profiles are used in a radiative transfer model to calculate brightness temperatures (Tbs) at TMI frequencies. The UWNMS-based Tbs and TRMM-based Tbs are compared to validate overall consistency of the CRM simulations. The cloud-scale profiles of hydrometeors, vertical wind, temperature, and wind shear from UWNMS are analyzed to study their characteristics as functions of SST and GFS-based large-scale regimes represented by parameters including horizontal moisture divergence, vertical moisture flux at 500 hPa, potential vorticity, large-scale wind shear, and Convective Available Potential Energy among others, throughout mature stage of these major hurricanes. Results of this study show how cloud-scale processes are related to large-scale processes within these tropical cyclones.

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

2008-12-01

365

Thermodynamic properties for rare earths and americium in pyropartitioning process solvents  

SciTech Connect

The design of a molten metal-molten salt based chemical and electrochemical process for separation of actinides from plutonium-uranium extraction waste requires a consistent set of thermodynamic properties for the actinides and rare earths present in nuclear waste. Standard potential data for Y, La, Ce, Pr, and Gd in molten LiCl-KCl were obtained. Americium data obtained were standard potentials in molten LiCl-KCl and activity coefficients for Cd and Bi. Data were obtained between 400 and 500 C. Results for the rare earth chlorides using an improved experimental technique were consistent with theory, with standard free energy of formation values somewhat more negative than those found in the literature. Special attention was given to Am in the LiCl-KCl/Cd system because it can exist as the +2 and/or +3 ion in this system. Americium ions existed only as the +3 ion in LiCl-KCl/Bi. Standard electrochemical potentials for Am/Am{sup +2} in LiCl-KCl eutectic at 400, 450, and 500 C were {minus}2.893, {minus}2.853, and {minus}2.838 V, respectively, relative to Cl{sup 2}/Cl{sup {minus}}. Standard electrochemical potentials vs. Cl{sub 2}/Cl{sup {minus}} for Am/Am{sup +3} in LiCl-KCl eutectic were {minus}2.83 V at 450 C and {minus}2.78 V at 500 C. Activity coefficients for Am in molten Cd were 1 {times} 10{sup {minus}5} and 8 {times} 10{sup {minus}5} at 450 and 500 C.

Fusselman, S.P.; Roy, J.J.; Grimmett, D.L. [Boeing Co., Canoga Park, CA (United States). Rocketdyne Propulsion and Power] [and others

1999-07-01

366

Varying the charge of small cations in liquid water: structural, transport, and thermodynamical properties.  

PubMed

In this work, we show how increasing the charge of small cations affects the structural, thermodynamical, and dynamical properties of these ions in liquid water. We have studied the case of lanthanoid and actinoid ions, for which we have recently developed accurate polarizable force fields, and the ionic radius is in the 0.995-1.250 Å range, and explored the valency range from 0 to 4+. We found that the ion charge strongly structures the neighboring water molecules and that, in this range of charges, the hydration enthalpies exhibit a quadratic dependence with respect to the charge, in line with the Born model. The diffusion process follows two main regimes: a hydrodynamical regime for neutral or low charges, and a dielectric friction regime for high charges in which the contraction of the ionic radius along the series of elements causes a decrease of the diffusion coefficient. This latter behavior can be qualitatively described by theoretical models, such as the Zwanzig and the solvated ion models. However, these models need be modified in order to obtain agreement with the observed behavior in the full charge range. We have thus modified the solvated ion model by introducing a dependence of the bare ion radius as a function of the ionic charge. Besides agreement between theory and simulation this modification allows one to obtain an empirical unified model. Thus, by analyzing the contributions to the drag coefficient from the viscous and the dielectric terms, we are able to explain the transition from a regime in which the effect of viscosity dominates to one in which dielectric friction governs the motion of ions with radii of ca. 1 Å. PMID:23126724

Martelli, Fausto; Vuilleumier, Rodolphe; Simonin, Jean-Pierre; Spezia, Riccardo

2012-10-28

367

A molecular dynamics study of the thermodynamic properties of calcium apatites. 1. Hexagonal phases.  

PubMed

Structural and thermodynamic properties of crystal hexagonal calcium apatites, Ca10(PO4)6(X)2 (X = OH, F, Cl, Br), were investigated using an all-atom Born-Huggins-Mayer potential by a molecular dynamics technique. The accuracy of the model at room temperature and atmospheric pressure was checked against crystal structural data, with maximum deviations of ca. 4% for the haloapatites and 8% for hydroxyapatite. The standard molar lattice enthalpy, delta(lat)H298(o), of the apatites was calculated and compared with previously published experimental results, the agreement being better than 2%. The molar heat capacity at constant pressure, C(p,m), in the range 298-1298 K, was estimated from the plot of the molar enthalpy of the crystal as a function of temperature, H(m) = (H(m,298) - 298C(p,m)) + C(p,m)T, yielding C(p,m) = 694 +/- 68 J x mol(-1) x K(-1), C(p,m) = 646 +/- 26 J x mol(-1) x K(-1), C(p,m) = 530 +/- 34 J x mol(-1) x K(-1), and C(p,m) = 811 +/- 42 J x mol(-1) x K(-1) for hydroxy-, fluor-, chlor-, and bromapatite, respectively. High-pressure simulation runs, in the range 0.5-75 kbar, were performed in order to estimate the isothermal compressibility coefficient, kappaT, of those compounds. The deformation of the compressed solids is always elastically anisotropic, with BrAp exhibiting a markedly different behavior from those displayed by HOAp and ClAp. High-pressure p-V data were fitted to the Parsafar-Mason equation of state with an accuracy better than 1%. PMID:16375450

Cruz, Fernando J A L; Lopes, José N Canongia; Calado, Jorge C G; Minas da Piedade, Manuel E

2005-12-29

368

Salt Effects on the structural and thermodynamic properties of a group 3 LEA protein model peptide.  

PubMed

To sequestrate or scavenge ionic species in desiccated cells is one of the putative functions of group 3 late embryogenesis abundant (G3LEA) proteins. We still lack direct physicochemical information on how G3LEA proteins and their characteristic primary amino acid sequences, i.e., 11-mer motif repeats, behave in the presence of salts under water-deficit conditions. In the current study, we investigated salt effects as a function of water content on the structural and thermodynamic properties of the 22-mer peptide (PvLEA-22), consisting of two tandem repeats of the consensus 11-mer motif of G3LEA proteins from the larvae of P. vanderplanki. The results of circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopic measurements indicate four main points as follows: (1) PvLEA-22 is in random coils in the aqueous solutions with or without a salt. (2) Dried PvLEA-22, whether salt-free or mixed with NaCl or KCl, is largely folded as ?-helix. (3) When dried with MgCl(2) or CaCl(2), PvLEA-22 adopts ?-sheet structure as well as random coil. (4) PvLEA-22 faithfully reproduces the conformational changes of the native LEA protein in response to added salts. Furthermore, through temperature-modulated differential scanning calorimetry (TMDSC) measurements, dried PvLEA-22 is found to be in the glassy state at ambient temperatures, independent of which salt is present. On the basis of these results, we discuss the intrinsic nature and putative functional roles of G3LEA proteins under salt-rich conditions. PMID:21770412

Furuki, Takao; Shimizu, Tempei; Kikawada, Takahiro; Okuda, Takashi; Sakurai, Minoru

2011-07-25

369

Structural and thermodynamic properties of freely-jointed hard-sphere rings and chains  

SciTech Connect

In this paper, we employ the product-reactant Ornstein-Zernike approach (PROZA) developed by the authors to investigate the structural and thermodynamic properties of freely-jointed hard-sphere ring fluids. Using an Mxm component sticky two-point (S2P) model and specifying an appropriate association rule between various species, the associating monomers will form M rings with each ring composed of m beads in the complete-association limit. Applying the PROZA to such a Hamiltonian and considering the limit of complete association, we are able to derive analytical expressions for the average monomer-monomer radial distribution function (RDF) as well as its intermolecular and intramolecular contributions and a closed form of the compressibility pressure. To test the theory, we also perform Monte Carlo simulations for the freely-jointed hard-sphere ring model over a wide range of densities and ring sizes. Compared to the simulation results, we find that the predictions of the PROZA for the compressibility factor of flexible ring melts are quantitatively accurate and the average monomer-monomer RDF g(r) is in excellent agreement with the simulation data over a wide range of densities that includes the polymer-melt regime. Based upon such a comparison as well as theoretical considerations, we conclude that ring-size independence of g(r) is a quantitatively accurate approximation and also that the g(r) of rings will be a good approximation for melts of long chains. Finally, we find that we must go beyond our PROZA framework in order to accurately obtain the separate intramolecular and intermolecular parts of g(r), for which we give a quantitatively satisfactory recipe. (c) 2000 American Institute of Physics.

Lin, C.-T [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400 (United States); Stell, G. [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400 (United States); Kalyuzhnyi, Yu. V. [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400 (United States); Institute for Condensed Matter Physics, Svientsitskoho 1, 290011 Lviv, (Ukraine)

2000-02-08

370

Thermodynamic properties Ar films on the surface of a bundle of carbon nanotubes  

Microsoft Academic Search

We employ canonical Monte Carlo simulations to explore the properties of an Argon film adsorbed on the external surface of a bundle of carbon nanotubes. The study is concerned primarily with three properties: specific heat, differential heat of adsorption, and Ar-Ar correlation functions. These measurable functions exhibit information about the dependence of film structure on coverage and temperature. Our results

Milton Cole; Silvina Gatica

2005-01-01

371

Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet.  

National Technical Information Service (NTIS)

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 ...

R. W. Murphy

1994-01-01

372

A New Equation of State and Tables of Thermodynamic Properties for Methane Covering the Range from the Melting Line to 625 K at Pressures up to 100 MPa  

Microsoft Academic Search

This work reviews the data on thermodynamic properties of methane which were available up to the middle of 1991 and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. A new strategy for optimizing the structure of empirical thermodynamic correlation equations was used to determine the functional form of the

U. Setzmann; W. Wagner

1991-01-01

373

Thermodynamic properties of supercritical n-m Lennard-Jones fluids and isochoric and isobaric heat capacity maxima and minima  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima/minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties.

Mairhofer, Jonas; Sadus, Richard J.

2013-10-01

374

Thermodynamic properties of supercritical n-m Lennard-Jones fluids and isochoric and isobaric heat capacity maxima and minima.  

PubMed

Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima?minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties. PMID:24160523

Mairhofer, Jonas; Sadus, Richard J

2013-10-21

375

Review of the Thermodynamic Properties of Hydrogen Based on Existing Equations of State  

NASA Astrophysics Data System (ADS)

Currently available equations of state (EOSs) for hydrogen are reviewed, and the data for the critical point, normal boiling point, and triple point are summarized. Through comparisons of PVT, saturated properties, heat capacity, and speed of sound among the latest EOSs for hydrogen, their features are discussed. The proper use of the EOSs, including a consideration of the nuclear isomers (ortho- and parahydrogen), is of great importance, especially for saturated properties, heat capacity, and speed of sound because these properties are different between the nuclear isomers. The present review concludes with recommendations for use of the EOSs for hydrogen.

Sakoda, N.; Shindo, K.; Shinzato, K.; Kohno, M.; Takata, Y.; Fujii, M.

2010-02-01

376

Thermodynamic Properties of Actinide-Zirconium Dioxide Solid-Solutions Relevant for Advanced Nuclear Fuels  

SciTech Connect

Currently, spent nuclear fuel (SNF) from commercial reactors is composed of 95-99% UO{sub 2} and 1-5% fission products and transuranium elements. Thus, the primary waste form is the UO{sub 2} matrix, which over time will corrode to a variety of U(VI)-secondary phases. Alternative nuclear fuels, such as inert-matrix fuels and mixed-oxide fuels, have been studied for their in-reactor performance; however little research has been conducted to understand the behavior of these fuels as a wasteform. We use density functional theory and Monte-Carlo methods to understand the solid solution behavior of (Ac, Zr)O{sub 2} (Ac = Th, U, Np, Pu) phases. The end members of interest include ZrO{sub 2}, ThO{sub 2}, UO{sub 2}, NpO{sub 2}, and PuO{sub 2}, and all share the cubic-fluorite structure. The excess enthalpy of mixing ({delta}H{sub excess}), excess Gibbs free energy of mixing ({delta}G{sub excess}), and excess configurational entropy ({delta}S{sub excess}) are calculated for the above solid solution series, and from {delta}G{sub excess}, miscibility gaps are identified. In conclusion: Density functional theory and Monte Carlo simulations were used in this study to determine the thermodynamic properties of binary oxide solid solutions that are useful for advanced nuclear fuel applications. The DFT results for each solid solution series is of the single cubic unit cell; therefore, only one interaction parameter was calculated. Based on the Monte-Carlo results, on the order of 25% Zr can be incorporated into the AcO{sub 2} structures (Ac = Th, U, Np, or Pu). However, only trace amounts of the actinides can be incorporated into ZrO{sub 2}. Considering larger systems in the DFT calculations will improve results, because more cation-cation interaction parameters can be calculated. Configurational ordering can also be considered with larger systems. Molecular dynamic simulations will be used to determine the temperature dependence of the different solid solutions that is more specific to their respective lattice dynamics. (authors)

Shuller, L.C.; Ewing, R.C. [Materials Science and Engineering Department, University of Michigan (United States); Pavenayotin, N.; Ewing, R.C. [University of Michigan, Nuclear Engineering (United States); Skomurski, F.N. [Geological Sciences Department, University of Michigan (United States); Ewing, R.C.; Becker, U. [EMSL, Pacific Northwest National Laboratory (United States)

2008-07-01

377

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

378

Rheological and Thermodynamic Properties of Volatile-bearing Magmas from Pantelleria, Etna and Phlegrean Fields Magmas  

NASA Astrophysics Data System (ADS)

The rheological and thermodynamic properties of silicate melts control fluid-dynamics of transport, eruption style and rates of physico-chemical processes (degassing and crystallization) in natural magmas. In this study we investigated the effect of H2O and CO2 on the liquid viscosity and heat capacity on several multicomponent systems. Measurements were conducted on four series of melts, obtained by remelting and homogenization of natural pantelleritic (Khaggiar dome, Pantelleria), trachytic (Agnano Monte Spina eruption, Phlegrean Fields), latitic (Fondo Riccio eruption, Phlegrean Fields) and trachybasaltic (Etna 1992 eruption) magmas. CO2 or H2O synthesis experiments were conducted in piston cylinder apparatus. The volatile -bearing samples were measured with a differential scanning calorimeter (DSC) and a vertical dilatometer (micropenetration technique). Water and CO2 content were measured by Karl Fisher Titration and FTIR spectroscopy. Compositions were analyzed over a range of water contents up to 5.3 wt% and CO2 content up to 4000 ppm. Viscosity ranged from 108 to 1013 Pa s with decreasing temperature from 630 to 1100 K. Viscosity is strongly affected by H2O and CO2. The effect of CO2 on viscosity appears to be a function of speciation and chemical composition. The heat capacity of glasses and liquids and the glass transition interval were also investigated. Base chemical composition have a strong influences on Tg: high alkali contents can lower Tg of low NBO/T liquids. This behavior is demonstrated by Pantellerite samples. Glass transition temperatures are also strongly affected by H2O and CO2. The CO2 effect, such as water, is to decrease Tg and it appears to be a function of chemical composition. We present data for partial molar CpH2Omol and CpOH- and derive a simple expression to evaluate the relative contributions of different H-bearing species to the total heat capacity of hydrous melts. Experimental viscosity and calorimetric data were fitted according to the Adam and Gibbs theory in which configurational entropy (Sconf) is the main factor controlling the viscosity of melts. From calorimetric measurements, and assuming that the vibrational contribution to the liquid Cp remains constant above Tg, we determined the configurational contribution to Cpliq and thus calculated the variation of the Sconf as a function of T, H2O and CO2 content in the liquid state. Combining viscosity measurements with the configurational entropies for our liquids, we parameterized the variation of viscosity as a function of temperature and volatiles content within the framework of the Adam and Gibbs theory of structural relaxation.

Di Genova, D.; Romano, C.; Alletti, M.; Behrens, H.; Scaillet, B.

2011-12-01

379

Rational design of ion force fields based on thermodynamic solvation properties.  

PubMed

Most aqueous biological and technological systems contain solvated ions. Atomistic explicit-water simulations of ionic solutions rely crucially on accurate ionic force fields, which contain most commonly two adjustable parameters: the Lennard-Jones diameter and the interaction strength. Assuming these parameters to be properly optimized, the plethora of parameters one finds in the literature for one and the same ion is surprising. In principle, the two parameters should be uniquely determined by matching two ionic properties obtained for a particular water model and within a given simulation protocol with the corresponding experimental observables. Traditionally, ion parameters were chosen in a somewhat unsystematic way to reproduce the solvation free energy and to give the correct ion size when compared with scattering results. Which experimental observable one chooses to reproduce should in principle depend on the context within which the ionic force field is going to be used. In the present work we suggest to use the solvation free energy in conjunction with the solvation entropy to construct thermodynamically sound force fields for the alkali and halide ions for the simulation of ion-specific effects in aqueous environment. To that end we determine the solvation free energy and entropy of both cations and anions in the entire relevant parameter space. As an independent check on the quality of the resulting force fields we also determine the effective ionic radius from the first peak of the radial ion-water distribution function. Several difficulties during parameter optimization are discussed in detail. (i) Single-ion solvation depends decisively on water-air surface properties, which experimentally becomes relevant when introducing extrathermodynamic assumptions on the hydronium (H(3)O(+)) solvation energy. Fitting ion pairs circumvents this problem but leaves the parameters of one reference ion (here we choose chloride) undetermined. (ii) For the halides the problem is almost underdetermined, i.e., there is a whole set of degenerate parameters that equally well describe, e.g., chloride and bromide ions. (iii) For the heavy cations the problem is overdetermined, i.e., no combination of Lennard-Jones parameters is able to reproduce simultaneously energy and entropy of solvation. We discuss various possibilities to deal with these problems and finally present an optimized force field for the halide anions that reproduces the free energy and the entropy of solvation. For the alkali metal cations there is no unambiguous choice of parameters. Therefore, we give three different parameter sets for every ion with a small, intermediate, or large Lennard-Jones interaction strength, where the Lennard-Jones diameters are optimized to reproduce the solvation free energy. The ionic radius is reproduced with acceptable accuracy by this optimization strategy, meaning that the proposed force fields are reliable beyond the target observables (i.e., free energy and entropy of solvation). PMID:19334851

Horinek, Dominik; Mamatkulov, Shavkat I; Netz, Roland R

2009-03-28

380

Amylose Phase Composition As Analyzed By FTIR In A Temperature Ramp: Influence Of Short Range Order On The Thermodynamic Properties  

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

381

Thermodynamic properties of pulverized coal during rapid heating devolatilization processes. Quarterly progress report, April--June 1993  

SciTech Connect

Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is essential to the fundamental determination of kinetic parameters of coal devolatilization. These same properties are also needed to refine existing devolatilization sub-models utilized in large-scale modeling of coal combustion systems. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. The coal ranks to be investigated will include a high volatile A bituminous (PSOC 1451 D) and a low volatile bituminous (PSOC 1516D). An anthracite (PSOC 1468) will be used as a non-volatile coal reference. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars.

Proscia, W.M.; Freihaut, J.D.

1993-08-01

382

Theoretical predictions of the structural and thermodynamic properties of MgZn2 Laves phase under high pressure  

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

2013-07-01

383

Thermodynamic phase retrieval of convective clouds: impact of sensor viewing geometry and vertical distribution of cloud properties  

NASA Astrophysics Data System (ADS)

The sensitivity of passive remote sensing measurements to retrieve microphysical parameters of convective clouds, in particular their thermodynamic phase, is investigated by three-dimensional (3-D) radiative transfer simulations. The effects of different viewing geometries and vertical distributions of the cloud microphysical properties are investigated. Measurement examples of spectral solar radiance reflected by cloud sides (passive) in the near-infrared (NIR) spectral range are performed together with collocated lidar observations (active). The retrieval method to distinguish the cloud thermodynamic phase (liquid water or ice) exploits different slopes of cloud side reflectivity spectra of water and ice clouds in the NIR. The concurrent depolarization backscattering lidar provides geometry information about the cloud distance and height as well as the depolarization.

Jäkel, E.; Walter, J.; Wendisch, M.

2013-03-01

384

The influence of 3d-metal alloy additions on the elastic and thermodynamic properties of CuPd3  

NASA Astrophysics Data System (ADS)

Embedded-atom method (EAM) potentials are used to investigate the effects of alloying (e.g. 3d-metals) on the trends of elastic and thermodynamic properties for CuPd3 alloy. Our calculated lattice parameter, cohesive energy, and elastic constants of CuPd3 are consistent with the available experimental and theoretical data. The results of elastic constants indicate that all these alloys are mechanically stable. Further mechanical behavior analysis shows that the additions of Cr, Fe, Co, and Ni could improve the hardness of CuPd3 while V could well increase its ductility. Moreover, in order to evaluate the thermodynamic contribution of 3d-metals, the Debye temperature, phonon density of states, and vibrational entropy for CuMPd6 alloy are also investigated.

Huang, Shuo; Zhang, Chuan-Hui; Sun, Jing; Shen, Jiang

2013-08-01

385

Statistical theory of the thermodynamic and structural properties of nematic liquid crystals with intermolecular correlations taken into account  

SciTech Connect

Correlation effects in liquid crystals are studied with the help of the statistical method of angular distributions. The approach is used to develop a statistical theory of the thermodynamic and structural properties of nematic liquid crystals. The molecular interaction characteristics of the crystals are expressed in terms of mean force potentials which satisfy a nonlinear integral equation. This equation is solved numerically and results are given for nematic polyacrylamide. The method can be used to calculate a wide spectrum of macroscopic characteristics, such as the dielectric constant, and correlation functions of different orders, including correlations between the angular and spatial variables.

Bruk-Levinson, E.T.; Zakharov, A.V.

1988-08-01

386

Structural and Thermodynamic Properties of Multiferroic Y0.5Dy0.5MnO3  

NASA Astrophysics Data System (ADS)

The structural and thermodynamic properties of polycrystalline samples of Y0.5Dy0.5MnO3 were investigated in order to investigate the effect of higher magnetic moment ion over Y ion. The structural transition from hexagonal to orthorhombic is observed at very high doping of Dy ion. Heat capacity measurements were performed at 2-300K in the application of different high magnetic field and the transition indicates the spin alignment of Mn3+(TNMn3+). By using heat capacity data also calculated Debye temperature of the series.

Kumar Swamy, N.; Gupta, Manish; Das, B. K.; Pavan Kumar, N.

387

On the studies of thermodynamics properties of fast neutron irradiated (LixK1-x)2SO4 crystals  

NASA Astrophysics Data System (ADS)

The effect of fast neutron irradiation on the thermodynamic properties of (LixK1-x)2SO4, (x = 0.1, 0.2,????????0.5) has been studied. The measurements were carried out in the vicinity of phase transition. The study reveals that as the lithium content decreases the first high temperature phase Tc = 705 K disappears, while the second one is shifted to lower temperature. It is observed also that the specific heat, Cp, decreases sharply with neutron integrated fluence ? and increases once more. Both entropy and enthalpy changes increase with the increase of neutron integrated fluence.

El-Khatib, A. M.; Kassem, M. E.; Gomaa, N. G.; Mahmoud, S. A.

388

Thermodynamic properties of the ?-quartz-type and rutile-type GeO2 from first-principles calculations.  

PubMed

Phonon density-of-states and related thermodynamic properties of the ?-quartz-type and rutile-type germanium dioxide (GeO2) are investigated from density functional perturbation theory. The significant density-of-states at the low frequencies in the ?-quartz-type GeO2 are at the origin of (i) its lower internal energy below 250 K, (ii) its smaller free energy, (iii) its higher entropy, (iv) its lower Debye temperature and (v) its larger positive linear thermal expansion, with respect to the rutile-type GeO2. PMID:23955725

Hermet, P; Lignie, A; Fraysse, G; Armand, P; Papet, Ph

2013-08-16

389

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets  

SciTech Connect

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

Richard T. Scalettar; Warren E. Pickett

2005-08-02

390

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets  

SciTech Connect

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

391

Predictions of the structural, electronic and thermodynamic properties of the anti-fluorite-type Mg2Sn under pressure from first principles  

NASA Astrophysics Data System (ADS)

Using first-principles calculations based on density functional theory, the structural, electronic and thermodynamic properties of Mg2Sn in anti-fluorite structure under hydrostatic pressure are investigated. Our results for the equilibrium structural parameters are consistent with the previous experimental and theoretical data. The dependences of elastic constants, polycrystalline elastic moduli, Poisson's ratio and the anisotropy factor on pressure have been investigated. It is found that pressure has a significant effect on elastic properties due to variations in interatomic distances. In addition, the variations in density of states with applied pressure are determined to reveal the bonding characteristics. Finally, the dependences of bulk modulus and thermodynamic properties of Mg2Sn on pressure and temperature are investigated with the quasi-harmonic Debye model, and the results of thermodynamic properties are consistent with the experimental report.

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

2013-10-01

392

The effects of thermodynamic stability on wind properties in different low-mass black hole binary states  

NASA Astrophysics Data System (ADS)

We present a systematic theory-motivated study of the thermodynamic stability condition as an explanation for the observed accretion disc wind signatures in different states of low-mass black hole binaries (BHB). The variability in observed ions is conventionally explained either by variations in the driving mechanisms or by the changes in the ionizing flux or due to density effects, whilst thermodynamic stability considerations have been largely ignored. It would appear that the observability of particular ions in different BHB states can be accounted for through simple thermodynamic considerations in the static limit. Our calculations predict that in the disc-dominated soft thermal and intermediate states, the wind should be thermodynamically stable and hence observable. On the other hand, in the power-law-dominated spectrally hard state the wind is found to be thermodynamically unstable for a certain range of 3.55 ? log ? ? 4.20. In the spectrally hard state, a large number of the He-like and H-like ions (including e.g. Fe XXV, Ar XVIII and S XV) have peak ion fractions in the unstable ionization parameter (?) range, making these ions undetectable. Our theoretical predictions have clear corroboration in the literature reporting differences in wind ion observability as the BHBs transition through the accretion states While this effect may not be the only one responsible for the observed gradient in the wind properties as a function of the accretion state in BHBs, it is clear that its inclusion in the calculations is crucial for understanding the link between the environment of the compact object and its accretion processes.

Chakravorty, Susmita; Lee, Julia C.; Neilsen, Joseph

2013-09-01

393

The effects of thermodynamic stability on wind properties in different low-mass black hole binary states  

NASA Astrophysics Data System (ADS)

We present a systematic theory-motivated study of the thermodynamic stability condition as an explanation for the observed accretion disc wind signatures in different states of low-mass black hole binaries (BHB). The variability in observed ions is conventionally explained either by variations in the driving mechanisms or by the changes in the ionizing flux or due to density effects, whilst thermodynamic stability considerations have been largely ignored. It would appear that the observability of particular ions in different BHB states can be accounted for through simple thermodynamic considerations in the static limit. Our calculations predict that in the disc-dominated soft thermal and intermediate states, the wind should be thermodynamically stable and hence observable. On the other hand, in the power-law-dominated spectrally hard state the wind is found to be thermodynamically unstable for a certain range of 3.55 ? log ? ? 4.20. In the spectrally hard state, a large number of the He-like and H-like ions (including e.g. Fe XXV, Ar XVIII and S XV) have peak ion fractions in the unstable ionization parameter (?) range, making these ions undetectable. Our theoretical predictions have clear corroboration in the literature reporting differences in wind ion observability as the BHBs transition through the accretion states While this effect may not be the only one responsible for the observed gradient in the wind properties as a function of the accretion state in BHBs, it is clear that its inclusion in the calculations is crucial for understanding the link between the environment of the compact object and its accretion processes.

Chakravorty, Susmita; Lee, Julia C.; Neilsen, Joseph

2013-11-01

394

An application of the extended corresponding states model to thermodynamic property calculations for trans-1,3,3,3-tetrafluoropropene (HFO1234ze(E))  

Microsoft Academic Search

A new thermodynamic property model is presented for trans-1,3,3,3-tetrafluoropropene (trans-CHFCHCF3, HFO-1234ze(E)) based upon available experimental data. This model is an application of the extended corresponding states principle, which is one approach in property modeling for fluids with limited experimental databases. The model is capable of calculating with reasonable accuracies various properties of HFO-1234ze(E), including the PVT relation, energies, heat capacities,

Ryo Akasaka

2010-01-01

395

Electronic Structure and Thermodynamic Properties of the Cubic Antiperovskite Compound InNCe3 via First-Principles Calculations  

NASA Astrophysics Data System (ADS)

Elastic, thermodynamic, electronic, and magnetic properties in the cubic antiperovskite InNCe3 compound are derived from the full-potential linear muffin-tin orbital method. From the computed elastic constants, theoretical values of Young's modulus, the shear modulus, Poisson's ratio, Lamé's coefficients, sound velocities, and the Debye temperature are evaluated. Analysis of the ratio between the bulk modulus and the shear modulus shows that InNCe3 is brittle in nature. The variations of elastic constants with pressure indicate that this compound possesses higher mechanical stability in the pressure range from 0 to 40 GPa. The electronic and magnetic properties of this compound are calculated by adding the Coulomb interaction U to improve the results.

Bettahar, N.; Nasri, D.; Benalia, S.; Merabet, M.; Abidri, B.; Benkhettou, N.; Khenata, R.; Rached, D.; Rabah, M.

2013-03-01

396

Thermodynamic properties of La1-xAxCoO3 (A=K, Cd, Pr and Nd)  

NASA Astrophysics Data System (ADS)

We have calculated the thermal and allied properties of La1-xAxCoO3 (A=K, Cd, Pr, Nd and 0?x?1) as a function of temperature 1 K?T?300 K for the first time using Modified Rigid Ion Model (MRIM). The calculated bulk modulus, specific heat, thermal expansion and other thermodynamic properties obtained from MRIM have presented proper interpretation of the experimental data, for monovalent (K+), divalent (Cd2+) and trivalent (Pr3+ and Nd3+) ion-doped LaCoO3. In addition, the results on the cohesive energy (?), molecular force constant (f), Reststrahlen frequency (?), Debye temperature (?D) and Gruneisen parameter (?) are also discussed.

Thakur, Rasna; Gaur, N. K.

2013-05-01

397

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

SciTech Connect

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)

1997-04-01

398

Thermodynamic Properties of o-Xylene, m-Xylene, p-Xylene, and Ethylbenzene  

NASA Astrophysics Data System (ADS)

Equations of state for the xylene isomers (o-xylene, m-xylene, and p-xylene) and ethylbenzene have been developed with the use of the Helmholtz energy as the fundamental property with independent variables of density and temperature. The general uncertainties of the equations of state are 0.5% in vapor pressure above the normal boiling point, and increase as the temperature decreases due to a lack of experimental data. The uncertainties in density range from 0.1% in the liquid region to 1.0% elsewhere (the critical and vapor-phase regions). The uncertainties in properties related to energy (such as heat capacity and sound speed) are estimated to be 1.0%. In the critical region, the uncertainties are higher for all properties. The behavior of the equations of state is reasonable within the region of validity and at higher and lower temperatures and pressures. Detailed analyses between the equations and experimental data are reported.

Zhou, Yong; Wu, Jiangtao; Lemmon, Eric W.

2012-06-01

399

Minimum-free-energy distribution of RNA secondary structures: Entropic and thermodynamic properties of rare events  

NASA Astrophysics Data System (ADS)

We study the distribution of the minimum free energy (MFE) for the Turner model of pseudoknot free RNA secondary structures over ensembles of random RNA sequences. In particular, we are interested in those rare and intermediate events of unexpected low MFEs. Generalized ensemble Markov-chain Monte Carlo methods allow us to explore the rare-event tail of the MFE distribution down to probabilities such as 10-70 and to study the relationship between the sequence entropy and structural properties for sequence ensembles with fixed MFEs. Entropic and structural properties of those ensembles are compared with natural RNA of the same reduced MFE ( z score).

Wolfsheimer, S.; Hartmann, A. K.

2010-08-01

400

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

PubMed

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

401

First-principles study of lattice dynamics and thermodynamic properties of LaCl3 and LaBr3  

NASA Astrophysics Data System (ADS)

We perform first-principles calculations of the lattice dynamics and the thermodynamic properties of LaCl3 and LaBr3 . Using density-functional perturbation theory, we obtain the Born effective charge tensors, the dielectric permittivity tensors, the phonon frequencies at the Brillouin zone center, and the phonon dispersion curves, as well as corresponding density of states. The Born effective charge and the dielectric permittivity tensors exhibit anisotropy, which are analyzed in detail. The calculated phonon frequencies at the ? point of the Brillouin zone show good agreement with the experimental values for most vibrational modes. The light yields of LaCl3:Ce and LaBr3:Ce are theoretically estimated to be 62 400 and 71400photons/MeV , respectively, on the basis of the calculated values of the dielectric constants and the highest longitudinal optical infrared phonon frequencies. The thermodynamics properties including the phonon contribution to the Helmholtz free energy ?F , the phonon contribution to the internal energy ?E , the entropy S , and the constant-volume specific heat Cv are determined within the harmonic approximation based on the calculated phonon dispersion relations.

Liu, Bo; Gu, Mu; Qi, Zeming; Liu, Xiaolin; Huang, Shiming; Ni, Chen

2007-08-01

402

The thermodynamic properties of weakly interacting quark-gluon plasma via the one-gluon exchange interaction  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of the quark-gluon plasma (QGP), as well as its phase diagram, are calculated as a function of baryon density (chemical potential) and temperature. The QGP is assumed to be composed of the light quarks only, i.e., the up and down quarks, which interact weakly, and the gluons which are treated as they are free. The interaction between quarks is considered in the framework of the one gluon exchange model which is obtained from the Fermi liquid picture. The bag model is used, with fixed bag pressure ( B)for the nonperturbative part, and the quantum chromodynamics (QCD) coupling is assumed to be constant, i.e., with no dependence on the temperature or the baryon density. The effect of weakly interacting quarks on the QGP phase diagram are shown and discussed. It is demonstrated that the one-gluon exchange interaction for the massless quarks has considerable effect on the QGP phase diagram and it causes the system to reach to the confined phase at the smaller baryon densities and temperatures. The pressure of excluded volume hadron gas model is also used to find the transition phase diagram. Our results depend on the values of bag pressure and the QCD coupling constant. The latter does not have a dramatic effect on our calculations. Finally, we compare our results with the thermodynamic properties of strange quark matter and the lattice QCD prediction for the QGP transition critical temperature.

Modarres, M.; Mohamadnejad, A.

2013-03-01

403

Effect of molecular structure on thermodynamic properties of carbohydrates. A calorimetric study of aqueous di- and oligosaccharides at subzero temperatures.  

PubMed

For aqueous solutions of di- and oligosaccharides thermodynamic properties have been investigated at subzero temperatures using differential scanning calorimetry. The amount of unfrozen water observed is found to increase linearly with the glass transition temperatures of anhydrous carbohydrates. Furthermore, the amount of unfrozen water shows a linear relationship with known solution properties of aqueous carbohydrates, such as partial molar compressibility and heat of solution. The different effectiveness among various di- and oligosaccharides to avoid ice formation is associated with the combination of constitutive monosaccharides and attendant molecular structure features including the position and type of the glycosidic linkage between the constituent units. More unfrozen water is induced in the presence of a carbohydrate having a poorer compatibility with the three-dimensional hydrogen-bond network of water. A series of these results obtained imply that there is a common key of carbohydrate stereochemistry governing several different thermodynamic amounts of a given system involving carbohydrates. In this context, a modified stereospecific-hydration model can be used to interpret the present results in terms of stereochemical effects of carbohydrates. PMID:11861018

Furuki, Takao

2002-03-01

404

Thermodynamic Effects on Phase Stabilities and Structural Properties of TiO2 from the First-principles  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) is one of the most representative photocatalytic materials and much attention is focused on understanding and improvement of its photocatalytic activity. At the same time, TiO2 is known to be a highly polymorphic material and as many as eleven crystal phases have been identified so far. It is expected that TiO2 show various photocatalytic properties depending on crystal phases. However, relative stabilities of these identified phases are still controversial. In order to clarify the thermodynamic phase stabilities of TiO2, we obtain the free energies of its several representative phases, rutile, anatase, brookite, and TiO2-II within the framework of the density-functional theory using the pseudopotential method. We calculate both the static energy and the contribution of phonons to the free energy through the quasiharmonic approximation for each phase. It is found that treatment of semicore electrons in constructing the pseudopotential of the Ti atom significantly affects the relative phase stabilities. From the phase diagram obtained, we find that the anatase phase is the most stable at lower temperature and pressure. We also discuss the thermodynamic effects on structural properties such as thermal expansion.

Aoki, Yuta; Saito, Susumu

2013-03-01

405

Thermodynamic properties and atomistic structure of the dry amorphous silica surface from a reactive force field model  

NASA Astrophysics Data System (ADS)

A force field model of the Keating type supplemented by rules to break, form, and interchange bonds is applied to investigate thermodynamic and structural properties of the amorphous SiO2 surface. A simulated quench from the liquid phase has been carried out for a silica sample made of 3888 silicon and 7776 oxygen atoms arranged on a slab ˜40Å thick, periodically repeated along two directions. The quench results into an amorphous sample, exposing two parallel square surfaces of ˜42nm2 area each. Thermal averages computed during the quench allow us to determine the surface thermodynamic properties as a function of temperature. The surface tension turns out to be ?=310±20erg/cm2 at room temperature and ?=270±30 at T=2000K , in fair agreement with available experimental estimates. The entropy contribution Tss to the surface tension is relatively low at all temperatures, representing at most ˜20% of the surface energy. Almost without exceptions, Si atoms are fourfold coordinated and oxygen atoms are twofold coordinated. Twofold and threefold rings appear only at low concentration and are preferentially found in proximity of the surface. Above the glass temperature Tg=1660±50K , the mobility of surface atoms is, as expected, slightly higher than that of bulk atoms. The computation of the height-height correlation function shows that the silica surface is rough in the equilibrium and undercooled liquid phase, becoming smooth below the glass temperature Tg .

Cabriolu, Raffaela; Ballone, Pietro

2010-04-01

406

Catalytic and thermodynamic properties of a tannase produced by Aspergillus niger GH1 grown on polyurethane foam.  

PubMed

Tannase is an inducible enzyme with important applications in the food and pharmaceutical industries. This enzyme was produced by the fungus Aspergillus niger GH1 under solid-state fermentation using polyurethane foam as solid support and tannic acid as sole carbon source and tannase inducer. Physicochemical properties of A. niger tannase were characterized, and the kinetic and thermodynamics parameters on methyl gallate hydrolysis were evaluated. The enzyme was stable in a pH range of 2-8 and a functional temperature range of 25-65 °C. The highest k(cat) value was 2,611.10 s(-1) at 65 °C. Tannase had more affinity for methyl gallate at 45 °C with a K(M) value of 1.82 mM and an efficiency of hydrolysis (k(cat)/K(M)) of 330.01 s(-1) mM(-1). The lowest E(a) value was found to be 21.38 kJ/mol at 4.4 mM of methyl gallate. The lowest free energy of Gibbs (?G) and enthalpy (?H) were found to be 64.86 and 18.56 kJ/mol, respectively. Entropy (?S) was -0.22 kJ/mol K. Results suggest that the A. niger GH1 tannase is an attractive enzyme for industrial applications due its catalytic and thermodynamical properties. PMID:21837378

Ramos, Erika L; Mata-Gómez, Marco A; Rodríguez-Durán, Luis V; Belmares, Ruth E; Rodríguez-Herrera, Raúl; Aguilar, Cristóbal Noe

2011-08-12

407

Helmholtz Energy Equations of State for HFC and Natural Refrigerants and Their Applications to Calculations of Thermodynamic Properties  

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

408

Standard state thermodynamic properties of completely dissociated hydrochloric acid and aqueous sodium hydroxide at extreme temperatures and pressures.  

PubMed

Standard state thermodynamic properties for completely dissociated hydrochloric acid were fixed by ionic additivity, using the data from other strong electrolytes perrhenic acid, sodium perrhenate, and sodium chloride from 298.15 to 598.15 K and at p(sat). The standard electrode potential for the important silver-silver chloride electrode system and the equilibrium constants for the volatility of HCl from aqueous solutions were then calculated and compared with literature data. Using the experimental data from this study and auxiliary data from literature, the logarithm of the molal association constant of HCl at the critical temperature of water and at 673.15 K up to 1000 MPa was predicted from the unified theory of electrolytes (UTE). The standard state thermodynamic properties for completely dissociated aqueous sodium hydroxide were also calculated by ionic additivity over the same temperature range from aqueous sodium chloride, hydrochloric acid, and the dissociation constant of water. The results were compared with literature data. PMID:19606908

Djamali, Essmaiil; Cobble, James W

2009-08-01

409

Elastic, superconducting, and thermodynamic properties of the cubic metallic phase of AlH3 via first-principles calculations  

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

410

A thermodynamic property formulation for ethylene from the freezing line to 450 K at pressures to 260 MPa  

NASA Astrophysics Data System (ADS)

A new thermodynamic property formulation based upon a fundamental equation explicit in Helmholtz energy of the form A= A( ?, T) for ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. A vapor pressure equation, equations for the saturated liquid and vapor densities as functions of temperature, and an equation for the ideal-gas heat capacity are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least-squares fit to selected P-?-T data, saturated liquid and saturated vapor density data to define the phase equilibrium criteria for coexistence, C v data, velocity of sound data, and second virial coefficients. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity ( C v), isobaric heat capacity ( C p), and velocity of sound are included. The fundamental equation reported here may be used to calculate pressures and densities with an uncertainty of ±0.1%, heat capacities within ±3 %, and velocity of sound values within ±1 %, except in the region near the critical point. The fundamental equation is not intended for use near the critical point. This formulation is proposed as part of a new international standard for thermodynamic properties of ethylene.

Jahangiri, M.; Jacobsen, R. T.; Stewart, R. B.; McCarty, R. D.

1986-05-01

411

Thermodynamic properties of chromium oxides in slags from carbon-ferrochrome production  

Microsoft Academic Search

In the smelting of carbon ferrochrome, it is impor? tant to determine the optimal slag composition, which should have certain physical and physicochemical properties for most complete reduction of the chro? mium and impurity removal. The selection of the slag composition depends on the composition of the initial chrome ore and the fluxes employed. The fluxes most commonly used in

A. V. Pavlov; D. Ya. Ostrovskii; Yu. V. Glavatskikh

2011-01-01

412

Thermodynamic properties and structure of the liquid-vapor interface: A neoclassical Redlich-Kwong model  

NASA Astrophysics Data System (ADS)

It is well known that the classical mean field theory of van der Waals for liquid-vapor interfacial region properties deviates from real fluid behavior in several important ways. In particular, the variations of the surface tension and interfacial region thickness with temperature near the critical point are not consistent with those for real fluids. This paper presents a modified version of the classical mean field model that incorporates Redlich-Kwong fluid properties. It is shown here that this neoclassical Redlich-Kwong fluid model predicts property variations with temperature that agree better with measured data for real fluids. Predictions of the critical exponents associated with the temperature variation of surface tension and interfacial region thickness are developed from the Redlich-Kwong model. This new model predicts that surface tension varies about proportional to (1-T/Tc)1.33 and that the interfacial region thickness varies about proportional to (1-T/Tc)-0.67, with T and Tc being the system temperature and critical temperature, respectively. Compared to the critical exponents predicted by classical van der Waals theory, the Redlich-Kwong model predictions are found to be in better agreement with values inferred from experimental measurements. Predictions of the Redlich-Kwong model regarding interfacial region structure and property fluctuations are also examined.

Carey, V. P.

2003-03-01

413

Ursell Operators in Statistical Physics III: thermodynamic properties of degenerate gases  

Microsoft Academic Search

We study in more detail the properties of the generalized Beth Uhlen- beck formula obtained in a preceding article. This formula leads to a sim- ple integral expression of the grand potential of any dilute system, where the interaction potential appears only through the matrix elements of the second order Ursell operator U2. Our results remain valid for significant degree

P. Gruter; F. Laloe; A. E. Meyerovich; W. Mullin

414

Ursell Operators in Statistical Physics III: thermodynamic properties of degenerate gases  

Microsoft Academic Search

We study in more detail the properties of the generalized Beth Uhlenbeck formula obtained in a preceding article. This formula leads to a simple integral expression of the grand potential of the system, where the interaction potential appears only through the matrix elements of the second order Ursell operator $U_{2}$. Our results remain valid for significant degree of degeneracy of

P. Grüter; F. Laloë; A. E. Meyerovich; W. Mullin

1996-01-01

415

Thermophysical Properties of Liquid Air and Its Components (Teplofizicheskie Svoistva Zhidkogo Vozdukha I Ego Komponentov).  

National Technical Information Service (NTIS)

Contents: Form of the equation of state for liquids; Thermodynamic properties of liquid nitrogen; Thermodynamic properties of liquid oxygen; Thermodynamic properties of liquid argon; Thermodynamic properties of liquid air; Viscosity of liquid air and its ...

A. A. Vasserman V. A. Rabinovich

1970-01-01

416

On the calculation of equilibrium thermodynamic properties and the establishment of statistical-thermodynamically-consistent finite bound-state partition functions in nonideal multicomponent plasma mixtures within the chemical model  

SciTech Connect

The problem of the calculation of equilibrium thermodynamic properties and the establishment of statistical-thermodynamically consistent finite bound-state partition functions in nonideal multicomponent plasma systems is revised within the chemical picture. The present exploration accompanied by the introduction of a generalized consistent formulation, in terms of the solution of the inverse problem, clears ambiguities and gives a better understanding of the problem on top of pointing out weaknesses and inaccuracies/inconsistencies buried in widely used models in literature.

Zaghloul, Mofreh R. [Department of Physics, College of Sciences, United Arab Emirates University, Al-Ain, 177551 (United Arab Emirates)

2010-12-15

417

Thermodynamic properties of bridging clusters in thin films of water between hydrophobic surfaces assessed from surface force isotherms.  

PubMed

In the course of a long-term effort to cope with surface force data for thin films of water between hydrophobic surfaces, we have applied the bridging-cluster model (Eriksson, J. C.; Henriksson, U. Bridging-cluster model for hydrophobic attraction . Langmuir 2007, 23, 10026 - 10033) to the recently published surface force isotherms for water films between hexadecylthiolated gold surfaces in the thickness range of 20-100 nm and temperature range of 10-40 °C (Wang, J.; Yoon, R.-H.; Eriksson, J. C. Excess thermodynamic properties of thin water films confined between hydrophobized gold surfaces. J. Colloid Interface Sci. 2011, 364, 257 - 263). We show that these isotherms can be faithfully reproduced on the basis of the bridging-cluster model. The thermodynamic excess properties (?Gc?, ?Hc?, and T?Sc) of linear clusters that are assumed to bridge the core of the films were calculated from the experimental surface force isotherms. A crucial step taken was to infer two-dimensional ideal mixing of the clusters with the surrounding film water. We find that ?Hc and T?Sc are both negative quantities, with the latter being larger than the former, which implies a positive excess Gibbs energy of a cluster, ?Gc = ?Hc - T?Sc. Typically, for temperatures between 10 and 40 °C, these cluster properties are of the order of some kBT units, corresponding to 10(-4)-10(-3)kBT per water molecule entailed. Our analysis yields support of the notion that elongated aggregates can arise in thin films of water between hydrophobic surfaces driven by entropy of mixing. PMID:23521404

Eriksson, Jan Christer; Henriksson, Ulf

2013-04-03

418

ON THE SELF-CONSISTENT STATISTICAL THEORY OF STRUCTURAL, DYNAMICAL, AND THERMODYNAMIC SURFACE PROPERTIES OF ANHARMONIC CRYSTALS II:. The Properties of Arbitrary Oriented Surfaces of the Two-Dimensional Model with Square Lattice  

NASA Astrophysics Data System (ADS)

The correlative unsymmetrized self-consistent field method is used to study surface properties of the two-dimensional model of an anharmonic crystal with square lattice having various Miller indices. The lattice relaxation, the amplitudes of atomic vibrations and the thermodynamic surface functions are calculated. The typical nonsingular and vicinal surfaces are considered. The dependence of thermodynamic surface functions on the surface orientation is obtained.

Zubov, V. I.; Banyeretse, F.

419

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

420

Electronic absorption, vibrational spectra, nonlinear optical properties, NBO analysis and thermodynamic properties of N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule by ab initio HF and density functional methods  

NASA Astrophysics Data System (ADS)

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-100 cm-1 and 4000-400 cm-1, respectively, for N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule. Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method using 6-31G(d,p) and 6-311G(d,p) basis sets. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The frontier orbital energy gap and dipole moment illustrates the high reactivity of the title molecule. The first order hyperpolarizability (?0) and related properties (?, ? and ??) of the molecule were also calculated. Stability of the molecule arising from hyperconjugative interactions and charge delocalization were analyzed using natural bond orbital (NBO) analysis. The results show that electron density (ED) in the ?* and ?* anti-bonding orbitals and second order delocalization energies (E2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded in the region 200-500 nm in ethanol and electronic properties such as excitation energies, oscillator strength and wavelength were calculated by TD-DFT/B3LYP, CIS and TD-HF methods using 6-31G(d,p) basis set. Molecular electrostatic potential (MEP) and HOMO-LUMO energy levels are also constructed. The thermodynamic properties of the title compound were calculated at different temperatures and the results reveals the heat capacity (C), and entropy (S) increases with rise in temperature.

Rajamani, T.; Muthu, S.; Karabacak, M.

2013-05-01

421

Electronic absorption, vibrational spectra, nonlinear optical properties, NBO analysis and thermodynamic properties of N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule by ab initio HF and density functional methods.  

PubMed

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-100 cm(-1) and 4000-400 cm(-1), respectively, for N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule. Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method using 6-31G(d,p) and 6-311G(d,p) basis sets. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The frontier orbital energy gap and dipole moment illustrates the high reactivity of the title molecule. The first order hyperpolarizability (?0) and related properties (?, ? and ??) of the molecule were also calculated. Stability of the molecule arising from hyperconjugative interactions and charge delocalization were analyzed using natural bond orbital (NBO) analysis. The results show that electron density (ED) in the ?(*) and ?(*) anti-bonding orbitals and second order delocalization energies (E2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded in the region 200-500 nm in ethanol and electronic properties such as excitation energies, oscillator strength and wavelength were calculated by TD-DFT/B3LYP, CIS and TD-HF methods using 6-31G(d,p) basis set. Molecular electrostatic potential (MEP) and HOMO-LUMO energy levels are also constructed. The thermodynamic properties of the title compound were calculated at different temperatures and the results reveals the heat capacity (C), and entropy (S) increases with rise in temperature. PMID:23474478

Rajamani, T; Muthu, S; Karabacak, M

2013-02-15

422

Review of the Thermodynamic Properties of Hydrogen Based on Existing Equations of State  

Microsoft Academic Search

Currently available equations of state (EOSs) for hydrogen are reviewed, and the data for the critical point, normal boiling\\u000a point, and triple point are summarized. Through comparisons of PVT, saturated properties, heat capacity, and speed of sound\\u000a among the latest EOSs for hydrogen, their features are discussed. The proper use of the EOSs, including a consideration of\\u000a the nuclear isomers

N. Sakoda; K. Shindo; K. Shinzato; M. Kohno; Y. Takata; M. Fujii

2010-01-01

423

Equilibrium and thermodynamic properties of the PuO 2+ x solid solution  

Microsoft Academic Search

Free energies for forming a fluorite-related PuO2+x solid solution via the oxide–water reaction at 300–800 K are obtained using estimated partial molar free energy isotherms based on bounding conditions and property data. Derived ?G° values indicate that the PuO2+H2O reaction spontaneously forms oxide compositions up to PuO2.5 at 300 K and are consistent with diffraction data for fluorite-related solids formed

John M. Haschke; Thomas H. Allen

2002-01-01

424

Formulation based on artificial neural network of thermodynamic properties of ozone friendly refrigerant\\/absorbent couples  

Microsoft Academic Search

This paper presents a new approach based on artificial neural networks (ANNs) to determine the properties of liquid and two phase boiling and condensing of two alternative refrigerant\\/absorbent couples (methanol\\/LiBr and methanol\\/LiCl). These couples do not cause ozone depletion and use in the absorption thermal systems (ATSs). ANNs are able to learn the key information patterns within multidimensional information domain.

Adnan Sözen; Mehmet Özalp

2005-01-01

425

Mechanical and thermodynamic properties of infrared transparent low melting chalcogenide glass  

Microsoft Academic Search

The properties of infrared (IR) transparent chalcogenide glass Se57I20As18Te3Sb2 have been studied for the first time by dynamic mechanical analysis (DMA). This glass demonstrates both high transparency in a broad IR band (1–12 ?m) and a particularly low softening point (near 50 °C). It is known as one of the best adhesives intended for the binding of IR optics elements.

Edward Bormashenko; Roman Pogreb; Semion Sutovsky; Victor Lusternik; Alexander Voronel

2002-01-01

426

Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar  

Microsoft Academic Search

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

427

Thermodynamic properties of the LiCl–H 2O system at vapor–liquid equilibrium from 273 K to 400 K  

Microsoft Academic Search

A formulation of the thermodynamic properties of the LiCl–H2O system at vapor–liquid equilibrium is presented in the form of separate Gibbs energy equations for the vapor and solution phases. Explicit thermodynamically consistent equations for density, isobaric heat capacity, enthalpy, entropy, enthalpy of dilution and osmotic coefficient are given. The pressure at vapor–liquid equilibrium is calculated from the condition of phase

J. Pátek; J. Klomfar

2008-01-01

428

Investigation of thermodynamic properties of poly(methyl methacrylate-co- n-butylacrylate-co-cyclopentyl styryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography  

Microsoft Academic Search

The thermodynamic properties of poly(methyl methacrylate-co-butyl acrylate-co-cyclo -pentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were investigated by means of inverse gas chromatography (IGC) using 20 different kinds of solvents as the probes. Some thermodynamic parameters, such as molar heats of sorption, weight fraction activity coefficient, Flory–Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions

Qi-Chao Zou; Shi-Ling Zhang; Shi-Min Wang; Li-Min Wu

2006-01-01

429

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

SciTech Connect

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

430

Static and thermodynamic properties of low-density supercritical 4He-breakdown of the Feynman-Hibbs approximation.  

PubMed

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

2009-08-14

431

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

NASA Astrophysics Data System (ADS)

Measured spectroscopic data, estimated molecular parameters, and a density-of-states model for electronic structure were used to calculate thermodynamic functions for gaseous ThO, ThO2, UO, UO2, UO3, PuO, and PuO2. Various methods for estimating parameters were considered and numerically evaluated. The sensitivity of the calculated thermodynamic functions to molecular parameters was examined quantitatively. Values of the standard enthalpies of formation at 298.15(0)K were derived from the best available (DELTA)G(0)/sub f/ equations and the calculated thermodynamic functions. Estimates of the uncertainties were made for measured and estimated data as well as for various mathematical and physical approximations. Tables of the thermodynamic functions to 6000(0)K are recommended for gaseous thorium, uranium, and plutonium oxides.

Green, D. W.

1980-09-01

432

Unconventional Magnetic and Thermodynamic Properties of S=1/2 Spin Ladder with Ferromagnetic Legs  

NASA Astrophysics Data System (ADS)

We have succeeded in synthesizing single crystals of a new organic radical 3-Cl-4-F-V [3-(3-chloro-4-fluorophenyl)-1,5-diphenylverdazyl]. Through the ab initio molecular orbital calculation and the analysis of the magnetic properties, this compound was confirmed to be the first experimental realization of an S=1/2 spin-ladder system with ferromagnetic leg interactions. The field-temperature phase diagram indicated that the ground state is situated very close to the quantum critical point. Furthermore, we found an unexpected field-induced successive phase transition, which possibly originates from the interplay of low dimensionality and frustration.

Yamaguchi, H.; Iwase, K.; Ono, T.; Shimokawa, T.; Nakano, H.; Shimura, Y.; Kase, N.; Kittaka, S.; Sakakibara, T.; Kawakami, T.; Hosokoshi, Y.

2013-04-01

433

Thermodynamic Properties of CO{sub 2} Capture Reaction by Solid Sorbents: Theoretical Predictions and Experimental Validations  

SciTech Connect

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

434

Structural, thermodynamic, and kinetic properties of Gramicidin analogue GS6 studied by molecular dynamics simulations and statistical mechanics.  

PubMed

Gramicidin S (GS) analogues belong to an important class of cyclic peptides, characterized by an antiparallel double-stranded beta-sheet structure with Type II' beta-turns. Such compounds can be used as model systems to understand the folding/unfolding process of beta-hairpins and more in general of beta-structures. In the present study, we specifically investigate the folding/unfolding behavior of the hexameric Gramicidin S analogue GS6 by using all-atoms molecular dynamics (MD) simulations at different temperatures, coupled to a statistical mechanical model based on the Quasi Gaussian Entropy theory. Such an approach permits to describe the structural, thermodynamic, and kinetic properties of the peptide and to quantitatively characterize its folding/unfolding transitions. PMID:19396809

Zanetti-Polzi, Laura; Anselmi, Massimiliano; D'Alessandro, Maira; Amadei, Andrea; Di Nola, Alfredo

2009-12-01

435

Absence of the structural phase transition in ammonia borane dispersed in mesoporous silica: evidence of novel thermodynamic properties  

SciTech Connect

The occurrence of the structural phase transition of NH3BH3 dispersed in mesoporous silica was studied by anelastic spectroscopy and differential scanning calorimetry. Both measurements indicate that the structural phase transition is suppressed in the sample in which ammonia borane covers only the internal surface of the scaffold. Such a drastic change in the main features of this compound indicates that novel thermodynamic properties can be obtained by means of the fine dispersion of NH3BH3 at a monolayer level. This work was produced with the support of the US Department of Energy Office of Basic Energy Sciences, Chemical Sciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Paolone, Annalisa; Palumbo, Oriele; Rispoli, Pasquale; Cantelli, Rosario; Autrey, Thomas; Karkamkar, Abhijeet J.

2009-06-18

436

An extended corresponding-states model for predicting thermodynamic properties of N 2 -Ar-O 2 mixtures including vapor-liquid equilibrium  

Microsoft Academic Search

A formulation developed previously for the prediction of the thermodynamic properties of single-phase states of binary and ternary mixtures in the nitrogen-argon-oxygen system has been revised to include the calculation of vapor-liquid equilibrium (VLE) properties. The model is based on the theory of extended corresponding states with van der Waals mixing rules. Binary interaction parameters have been determined with single-phaseP-p-T

W. P. Clarke; R. T. Jacobsen; E. W. Lemmon; S. G. Penoncello; S. W. Beyerlein

1994-01-01

437

Effect of combined external uniaxial stress and dc bias on the dielectric property of BaTiO3-based dielectrics in multilayer ceramic capacitor: thermodynamics and experiments  

Microsoft Academic Search

The dielectric properties of (Nb, Y)-doped BaTiO3 in a multilayer ceramic capacitor (MLCC) under combined external uniaxial compressive stress and dc bias field were investigated at room temperature by using a modified Ginsburg-Landau-Devonshire thermodynamic theory and the dielectric measurement. It is found that although dc bias decreases the dielectric properties dominantly, the influence of the external uniaixial compressive stress should

Gang Yang; Zhenxing Yue; Tieyu Sun; Huanlin Gou; Longtu Li

2008-01-01

438

Thermodynamic properties of HFC338mccq, CFâCFâCFâCHâF, 1,1,1,2,2,3,3,4-octafluorobutane  

Microsoft Academic Search

The authors report the thermodynamic properties of 1,1,1,2,2,3,3,4-octafluorobutane, which has been designated as HFC-338mccq by the refrigeration industry. The measurements span the temperature and pressure ranges encountered in thermal machinery. The properties measured include the vapor pressure, the density of the compressed liquid, the refractive index of both the saturated liquid and the saturated vapor, the critical temperature, the capillary

D. R. Defibaugh; E. Carrillo-Nava; J. J. Hurly; M. R. Moldover; J. W. Schmidt; L. A. Weber

1997-01-01

439

Thermodynamic and structural properties of the path-integral quantum hard-sphere fluid  

NASA Astrophysics Data System (ADS)

An extensive study of the path-integral quantum hard-sphere fluid far from exchange is presented. The results cover the calculation of mechanical, thermal, r-space and k-space pair properties. Path-integral Monte Carlo simulations involving the Cao-Berne's propagator provide the internal energies and pair radial distribution functions (instantaneous, linear response, and necklace center of mass). For the sake of comparison, Barker's and Jaccuci-Omerti's image propagators are also applied at several state points. To obtain k-space properties use of the Gaussian Feynman-Hibbs picture for representing quantum systems is made. This picture is known to yield two Ornstein-Zernike equations; one for true quantum particles (linear response) and the other for the centers of mass of quantum particles. Direct correlation functions and static structure factors are obtained via Baxter's partition complemented with Dixon-Hutchinson's variational procedure. Wherever possible, the present results are compared with semiclassical (Yoon-Scheraga's) and path-integral (Runge-Chester's) data available in the literature. The limits of validity of the Gaussian Feynman-Hibbs picture in this context are also established.

Sesé, Luis M.

1998-06-01

440

Analysis of elevated temperature data for thermodynamic properties of selected radionuclides  

SciTech Connect

This report is a review of chemical thermodynamic data for Ni, Zr, Tc, U, Np, Pu and Am in aqueous solutions at elevated temperatures. Thermodynamic data for aqueous reactions over the temperature range 20-150{degrees}C are needed for geochemical modeling studies of the Yucca Mountain Project. The present review is focused on the aqueous complexes relevant to expected conditions in the Yucca Mountain region: primarily the hydroxide, carbonate, sulfate and fluoride complexes with the metal ions. Existing thermodynamic data are evaluated, and means of extrapolating 25{degrees}C data to the temperatures of interest are discussed. There will be a separate review of solubility data for relevant Ni, Zr, Tc, Np, Pu and Am compounds.

Wruck, D.A.; Palmer, C.E.A.

1997-08-01