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1

Isobaric vapor-liquid equilibrium of the systems cumene + benzyl alcohol and phenol + benzyl alcohol at 10 kPa  

SciTech Connect

Isobaric vapor-liquid equilibrium data are reported for the binary systems cumene + benzyl alcohol and phenol + benzyl alcohol at 10 kPa. The activity coefficient data were tested for thermodynamic consistency by the methods of Herington, Black, and Van Ness and correlated with the Wilson equation. None of the systems show an azeotrope.

Resa, J.M.; Quintana, T.; Cepeda, E. (Univ. del Paris Vasco, Vitoria (Spain). Dept. Ingenieria Quimica)

1994-01-01

2

Isobaric vapor–liquid equilibria of three aromatic hydrocarbon-tetraethylene glycol binary systems  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium data have been determined at 101.33 kPa for the binary mixtures of benzene-tetraethylene glycol (TeEG), toluene-TeEG and o-xylene-TeEG. The vapor-phase fugacity coefficients were calculated from the virial equation. The thermodynamic consistency of the data has been tested via Herington analysis. The binary parameters for four activity coefficient models (van Laar, Wilson, NRTL and UNIQUAC) have been fitted

Yang-Xin Yu; Jian-Gang Liu; Guang-Hua Gao

1999-01-01

3

A "User-Friendly" Program for Vapor-Liquid Equilibrium.  

ERIC Educational Resources Information Center

Described is a computer software package suitable for teaching and research in the area of multicomponent vapor-liquid equilibrium. This program, which has a complete database, can accomplish phase-equilibrium calculations using various models and graph the results. (KR)

Da Silva, Francisco A.; And Others

1991-01-01

4

Isobaric vapor-liquid equilibria for binary and ternary systems composed of water, 1-propanol, and 2-propanol at 100 kPa  

SciTech Connect

Isobaric vapor-liquid equilibria data were obtained for the 2-propanol + 1-propanol binary system and the water + 1-propanol + 2-propanol ternary system at 100 kPa. The data were found to be thermodynamically consistent according to the Van Ness-Byer-Gibbs method for the binary system and according to the McDermott-Ellis method for the ternary one. The binary system is well represented by assuming ideal behavior. The binary interaction parameters obtained from this and previous work are used to predict the vapor-liquid equilibrium for the ternary system using the UNIQUAC, NRTL, and Wilson models. The ternary system is well predicted from binary data.

Gabaldon, C.; Marzal, P.; Monton, J.B.; Rodrigo, M.A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-11-01

5

Vapor liquid equilibrium simulations of the SCPDP model of water  

NASA Astrophysics Data System (ADS)

Molecular simulations were carried out using the self-consistent point dipole polarizability model (SCPDP) of water in the region of vapor-liquid equilibrium. The methods of isothermal-isochoric molecular dynamics (NVT-MD) and Gibbs ensemble Monte Carlo (GEMC) were employed to calculate orthobaric densities and vapor pressures; NVT-MD also yields surface tensions and interface thickness. Agreement was found between the two methods, particularly at lower temperatures, but compared with experimental results, this model over-predicts vapor pressures and densities, and under-predicts the liquid density, surface tension, and interface thickness. The interface thickness predicted by the SCPDP model showed better agreement with experimental results than a simpler extended point charge model (SPC/E).

Rivera, J. L.; Predota, M.; Chialvo, A. A.; Cummings, P. T.

2002-05-01

6

VAPOR + LIQUID EQUILIBRIUM OF WATER, CARBON DIOXIDE, AND THE BINARY SYSTEM WATER + CARBON DIOXIDE FROM  

E-print Network

VAPOR + LIQUID EQUILIBRIUM OF WATER, CARBON DIOXIDE, AND THE BINARY SYSTEM WATER + CARBON DIOXIDE the vapor-liquid equilibrium of water (between 323 and 573 K), carbon dioxide (between 230 and 290 K) and their binary mixtures (between 348 and 393 K). The properties of supercritical carbon dioxide were determined

7

Isobaric vapor-liquid equilibria of the water + 1-propanol system at 30, 60, and 100 kPa  

SciTech Connect

Isobaric vapor-liquid equilibria for the water + 1-propanol system are reported at 30, 60, and 100 kPa. The results were found to be thermodynamically consistent according to Van Ness-Byer-Gibbs, Kojima, and Wisniak methods. The system shows a minimum boiling azeotrope, and the azeotropic composition is scarcely shifted with pressure. Results were compared with literature values. The data were correlated with Margules, Van Laar, Wilson, NRTL, and UNIQUAC liquid-phase activity coefficient models.

Gabaldon, C.; Marzal, P.; Monton, J.B.; Rodrigo, M.A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-09-01

8

Vapor-liquid equilibrium, coexistence curve, and critical locus for difluoromethane + pentafluoroethane (R-32 + R-125)  

Microsoft Academic Search

The vapor-liquid equilibrium for difluoromethane + pentafluoroethane (R-32 + R-125) was measured by the static method in the temperature range between 283 K and 313 K. The vapor-liquid coexistence curve near the critical point was measured by the observation of the meniscus disappearance. The critical temperatures and critical densities of a 30 mass % R-32 and a 60 mass %

Yukihiro Higashi; Yukihiro

1997-01-01

9

Isobaric vapor-liquid equilibria of the water + 2-propanol system at 30, 60, and 100 kPa  

SciTech Connect

Distillation is perhaps the separation process most widely used in the chemical processing industry. The correct design of distillation columns requires the availability of accurate and, if possible, thermodynamically consistent vapor-liquid equilibria (VLE) data. The present work is part of a project studying the effect of pressure on the behavior of the azeotropic point in mixtures in which at least one component is an alcohol. Isobaric vapor-liquid equilibria were obtained for the water + 2-propanol system at 30, 60, and 100 kPa. The activity coefficients were found to be thermodynamically consistent by the methods of Van Ness-Byer-Gibbs, Kojima, and Wisniak. The data were correlated with five liquid phase activity coefficient models (Margules, Van Laar, Wilson, NRTL, and UNIQUAC).

Marzal, P.; Monton, J.B.; Rodrigo, M.A. [Univ. de Valencia (Spain). Departamento de Ingenieria Quimica] [Univ. de Valencia (Spain). Departamento de Ingenieria Quimica

1996-05-01

10

Molecular dynamics simulation on evaporation molecules in a vapor-liquid equilibrium state  

NASA Astrophysics Data System (ADS)

By using molecular dynamics simulations of argon molecules, the present study investigates molecular evaporation and reflection in equilibrium at a vapor-liquid interface, which involves the kinetic boundary condition (KBC) of the Boltzmann equation. The present method allows evaporation and reflection molecules to be selected naturally at the vapor-liquid interphase. Based on the results, we confirm that the evaporation molecules in the equilibrium state behave almost similar to spontaneous-evaporation molecules (as determined by virtual-vacuum evaporation simulations). Furthermore, we find that the velocity distribution of reflection molecules in the normal direction to the boundary is lower than the Maxwell distribution at the liquid temperature.

Kobayashi, Kazumichi; Hori, Kazumasa; Yaguchi, Hisao; Watanabe, Masao

2014-12-01

11

Vapor-liquid equilibrium, coexistence curve, and critical locus for difluoromethane + pentafluoroethane (R-32 + R-125)  

SciTech Connect

The vapor-liquid equilibrium for difluoromethane + pentafluoroethane (R-32 + R-125) was measured by the static method in the temperature range between 283 K and 313 K. The vapor-liquid coexistence curve near the critical point was measured by the observation of the meniscus disappearance. The critical temperatures and critical densities of a 30 mass % R-32 and a 60 mass % R-32 mixture were determined on the basis of the saturation densities along the coexistence curve in the critical region. In addition, the critical locus for the R-32 + R-125 mixture is correlated as the function of composition.

Higashi, Yukihiro [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering] [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering

1997-11-01

12

Testing the recent charge-on-spring type polarizable water models. II. Vapor-liquid equilibrium  

NASA Astrophysics Data System (ADS)

We studied the vapor-liquid coexistence region of seven molecular models of water. All models use the charge-on-spring (COS) method to express polarization. The studied models were the COS/G2, COS/G3 [H. Yu and W. F. van Gunsteren, J. Chem. Phys. 121, 9549 (2004), 10.1063/1.1805516], the SWM4-DP [G. Lamoureux, A. D. MacKerell, Jr., and B. Roux, J. Chem. Phys. 119, 5185 (2003), 10.1063/1.1598191], the SWM4-NDP [G. Lamoureux, E. Harder, I. V. Vorobyov, B. Roux, and A. D. MacKerell, Jr., Chem. Phys. Lett. 418, 245 (2006), 10.1016/j.cplett.2005.10.135], and three versions of our model, the BKd1, BKd2, and BKd3. The BKd1 is the original Gaussian model [P. T. Kiss, M. Darvas, A. Baranyai, and P. Jedlovszky, J. Chem. Phys. 136, 114706 (2012), 10.1063/1.3692602] with constant polarization and with a simple exponential repulsion. The BKd2 applies field-dependent polarizability [A. Baranyai and P. T. Kiss, J. Chem. Phys. 135, 234110 (2011), 10.1063/1.3670962], while the BKd3 model has variable size to approximate the temperature-density (T-?) curve of water [P. T. Kiss and A. Baranyai, J. Chem. Phys. 137, 194102 (2012), 10.1063/1.4767063]. We calculated the second virial coefficient, the heat of vaporization, equilibrium vapor pressure, the vapor-liquid coexistence curve, and the surface tension in terms of the temperature. We determined and compared the critical temperatures, densities, and pressures of the models. We concluded that the high temperature slope of the (T-?) curve accurately predicts the critical temperature. We found that Gaussian charge distributions have clear advantages over the point charges describing the critical region. It is impossible to describe the vapor-liquid coexistence properties consistently with nonpolarizable models, even if their critical temperature is correct.

Kiss, Péter T.; Baranyai, András

2012-11-01

13

Vapor-Liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C3H8 Propane (EVLM1111, LB5630_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C3H8 Propane (EVLM1111, LB5630_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

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

14

Vapor-liquid equilibrium, coexistence curve, and critical locus for pentafluoroethane + 1,1,1-trifluoroethane (R125\\/R143a)  

Microsoft Academic Search

The vapor-liquid equilibrium for pentafluoroethane (R125) + 1,1,1-trifluoroethane (R143a) was measured by the static method in the temperature range between 273.15 K and 313.15 K. The vapor-liquid coexistence curve near the critical point was measured by observation of the meniscus disappearance. The critical temperatures and critical densities of the 0.4118 and 0.6208 mole fraction of R125 were determined from the

Yukihiro Higashi; Yukihiro

1999-01-01

15

ARTICLES: Vapor-Liquid Equilibrium Data of Carbon Dioxide+Methyl Propionate and Carbon Dioxide+Propyl Propionate Systems  

NASA Astrophysics Data System (ADS)

High-pressure vapor-liquid equilibrium data for the binary systems of methyl propionate+carbon dioxide and propyl propionate+carbon dioxide were measured at pressure from 1.00 MPa to 12.00 MPa and temperature in the range from 313 K to 373 K. Experimental results were correlated with the Peng-Robinson equation of state with the two-parameter van der Waals mixing rule. At the same time, the Henry's coefficient, partial molar enthalpy change and partial molar entropy change of CO2 during dissolution at different temperature were also calculated.

Xu, Wei; Xie, Chuan-xin; Li, Hong-ling; Tian, Yi-ling

2010-06-01

16

Experimental Determination of Densities and Isobaric Vapor-Liquid Equilibria of Methyl Acetate and Ethyl Acetate with Alcohols (C3 and C4) at 0.3 MPa  

NASA Astrophysics Data System (ADS)

The densities and excess volumes were determined at 298.15 K for the methyl acetate + 1-propanol, methyl acetate + 1-butanol, and ethyl acetate + 1-butanol mixtures. The vapor-liquid equilibria data at 0.3 MPa for these binary systems were obtained using a stainless steel equilibrium still. The activity coefficients were obtained from the experimental data using the Hayden and O’Connell method and the Yen and Woods equation. The binary systems in this study showed positive deviations from ideality. The experimental VLE data were verified with the point-to-point test of van Ness using the Barker routine and the Fredenslund criterion. The different versions of the UNIFAC and the ASOG group contribution models were applied.

Susial, Pedro; Estupiñan, Esteban J.; Castillo, Victor D.; Rodríguez-Henríquez, José J.; Apolinario, José C.

2013-10-01

17

New phase equilibrium analyzer for determination of the vapor-liquid equilibrium of carbon dioxide and permanent gas mixtures for carbon capture and storage  

NASA Astrophysics Data System (ADS)

A high-pressure, phase equilibrium analyzer incorporating a fiber-optic reflectometer is described. The analyzer has been designed for measuring the vapor-liquid equilibrium data of multi-component mixtures of carbon dioxide and permanent gases, providing a novel tool to acquire of a large number of phase equilibrium data for the development of the new carbon capture and storage technologies. We demonstrate that the analyzer is suitable for determining both the bubble- and dew-point lines at temperature from 253 K and pressure up to 25 MPa using pure CO2 and two binary mixtures of CO2 + N2 and CO2 + H2.

Ke, Jie; Parrott, Andrew J.; Sanchez-Vicente, Yolanda; Fields, Peter; Wilson, Richard; Drage, Trevor C.; Poliakoff, Martyn; George, Michael W.

2014-08-01

18

New phase equilibrium analyzer for determination of the vapor-liquid equilibrium of carbon dioxide and permanent gas mixtures for carbon capture and storage.  

PubMed

A high-pressure, phase equilibrium analyzer incorporating a fiber-optic reflectometer is described. The analyzer has been designed for measuring the vapor-liquid equilibrium data of multi-component mixtures of carbon dioxide and permanent gases, providing a novel tool to acquire of a large number of phase equilibrium data for the development of the new carbon capture and storage technologies. We demonstrate that the analyzer is suitable for determining both the bubble- and dew-point lines at temperature from 253 K and pressure up to 25?MPa using pure CO2 and two binary mixtures of CO2 + N2 and CO2 + H2. PMID:25173315

Ke, Jie; Parrott, Andrew J; Sanchez-Vicente, Yolanda; Fields, Peter; Wilson, Richard; Drage, Trevor C; Poliakoff, Martyn; George, Michael W

2014-08-01

19

Vapor-Liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C2H3F3 1,1,1-Trifluoroethane (EVLM1111, LB5631_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C2H3F3 1,1,1-Trifluoroethane (EVLM1111, LB5631_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

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

20

Vapor-Liquid Equilibrium in the Mixture Hex-1-ene C6H12+ C6H14Hexane (EVLM1231,LB5704_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture Hex-1-ene C6H12 + C6H14 Hexane (EVLM1231, LB5704_E)' providing data from direct measurement of temperature and mole fraction in vapor phase at variable mole fraction in liquid phase and constant pressure.

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

21

Vapor-Liquid Equilibrium in the Mixture Cyclohexene C6H10 + C6H12 Cyclohexane (EVLM1231, LB5705_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture Cyclohexene C6H10 + C6H12 Cyclohexane (EVLM1231, LB5705_E)' providing data from direct measurement of temperature and mole fraction in vapor phase at variable mole fraction in liquid phase and constant pressure.

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

22

Vapor-Liquid Equilibrium in the Mixture 2,4-Dioxapentane C3H8O2 + C6H12 Cyclohexane (EVLM1211, LB5636_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture 2,4-Dioxapentane C3H8O2 + C6H12 Cyclohexane (EVLM1211, LB5636_E)' providing data from direct measurement of temperature at variable mole fraction in liquid phase and constant pressure.

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

23

Vapor-Liquid Equilibrium in the Mixture 3-Methylthiophene C5H6S + C6H12 Hex-1-ene (EVLM1131, LB5703_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture 3-Methylthiophene C5H6S + C6H12 Hex-1-ene (EVLM1131, LB5703_E)' providing data from direct measurement of pressure and mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

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

24

Vapor-Liquid Equilibrium in the Mixture 3-Methylthiophene C5H6S + C6H12 Cyclohexane (EVLM1131, LB5702_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture 3-Methylthiophene C5H6S + C6H12 Cyclohexane (EVLM1131, LB5702_E)' providing data from direct measurement of pressure and mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

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

25

Vapor-liquid equilibrium and critical asymmetry of square well and short square well chain fluids.  

PubMed

The critical behavior of square well fluids with variable interaction ranges and of short square well chain fluids have been investigated by grand canonical ensemble Monte Carlo simulations. The critical temperatures and densities were estimated by a finite-size scaling analysis with the help of histogram reweighting technique. The vapor-liquid coexistence curve in the near-critical region was determined using hyper-parallel tempering Monte Carlo simulations. The simulation results for coexistence diameters show that the contribution of |t|(1-?) to the coexistence diameter dominates the singular behavior in all systems investigated. The contribution of |t|(2?) to the coexistence diameter is larger for the system with a smaller interaction range ?. While for short square well chain fluids, longer the chain length, larger the contribution of |t|(2?). The molecular configuration greatly influences the critical asymmetry: a short soft chain fluid shows weaker critical asymmetry than a stiff chain fluid with same chain length. PMID:25106611

Li, Liyan; Sun, Fangfang; Chen, Zhitong; Wang, Long; Cai, Jun

2014-08-01

26

Simple apparatus for vapor-liquid equilibrium measurements with data for the binary systems of carbon dioxide with n-butane and isobutane  

SciTech Connect

The authors describe the design, construction, and testing of a simple vapor-liquid equilibrium apparatus designed for measurements in the range 300-500{Kappa} at pressures to 150 bar. Data are given for measurements of P, T, x, and y for binary systems of carbon dioxide with n-butane and isobutane in the range 310-394{Kappa}.

Weber, L.A. (Center for Chemical Engineering, Thermophysics Div., National Institute of Standards and Technology, Gaithersburg, MD (US))

1989-04-01

27

Vapor-liquid equilibrium, coexistence curve, and critical locus for pentafluoroethane + 1,1,1,2-tetrafluoroethane (R125/R134a)  

SciTech Connect

The vapor-liquid equilibrium for pentafluoroethane (R125) + 1,1,1,2-tetrafluoroethane (R134a) was measured along four isotherms between 283 K and 313 K. The vapor-liquid coexistence curve at constant composition near the mixture critical point was measured by the observation of the meniscus disappearance. The critical temperatures and critical densities of the 0.2670 and 0.6648 mole fraction of R125 were determined from the saturation densities along the coexistence curve in the critical region. In addition, the critical locus for the R125/R134a mixture is correlated as a function of composition.

Higashi, Yukihiro [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering] [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering

1999-03-01

28

Vapor-liquid equilibrium, coexistence curve, and critical locus for pentafluoroethane + 1,1,1-trifluoroethane (R125/R143a)  

SciTech Connect

The vapor-liquid equilibrium for pentafluoroethane (R125) + 1,1,1-trifluoroethane (R143a) was measured by the static method in the temperature range between 273.15 K and 313.15 K. The vapor-liquid coexistence curve near the critical point was measured by observation of the meniscus disappearance. The critical temperatures and critical densities of the 0.4118 and 0.6208 mole fraction of R125 were determined from the saturation densities along the coexistence curve in the critical region. In addition, the critical locus for the R125/R143a mixture is correlated as a function of composition.

Higashi, Yukihiro [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering] [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering

1999-03-01

29

Isothermal vapor–liquid equilibrium data for the carbon dioxide (R744) + decafluorobutane (R610) system at temperatures from 263 to 353 K  

Microsoft Academic Search

Isothermal vapor–liquid equilibrium data are presented for the carbon dioxide (CO2)+decafluorobutane (C4F10) system. Measurements were performed for seven isotherms (three isotherms below and four above the critical temperature of CO2) ranging from 263.15 to 352.98K, with pressure ranging from 0.0727 to 6.8628MPa. The measurements were undertaken using a “static-analytic” type apparatus, with sampling of the equilibrium phases via pneumatic capillary

Alain Valtz; Xavier Courtial; Erik Johansson; Christophe Coquelet; Deresh Ramjugernath

2011-01-01

30

(Vapor + liquid) equilibrium data for (carbon dioxide + 1,1-difluoroethane) system at temperatures from (258 to 343) K and pressures up to about 8 MPa  

Microsoft Academic Search

Accurate thermo-physical data are of utmost interest for the development of new efficient refrigeration systems. Carbon dioxide (R744) and 1,1-difluoroethane (R152a) are addressed here. Isothermal (vapor+liquid) equilibrium data are reported herein for (R744+R152a) binary system in the (258–343) K temperature range and in the (0.14 to 7.65) MPa pressure range. A reliable “static-analytic” method taking advantage of two online ROLSI™

Hakim Madani; Alain Valtz; Christophe Coquelet; Abdeslam Hassen Meniai; Dominique Richon

2008-01-01

31

Determination of vapor-liquid equilibrium data and decontamination factors needed for the development of evaporator technology for use in volume reduction of radioactive waste streams  

SciTech Connect

A program is currently in progress at Argonne National Laboratory to evaluate and develop evaporator technology for concentrating radioactive waste streams. By concentrating radioactive waste streams, disposal costs can be significantly reduced. To effectively reduce the volume of waste, the evaporator must achieve high decontamination factors so that the distillate is sufficiently free of radioactive material. One technology that shows a great deal of potential for this application is being developed by LICON, Inc. In this program, Argonne plans to apply LICON`s evaporator designs to the processing of radioactive solutions. Concepts that need to be incorporated into the design of the evaporator include, criticality safety, remote operation and maintenance, and materials of construction. To design an effective process for concentrating waste streams, both solubility and vapor-liquid equilibrium data are needed. The key issue, however, is the high decontamination factors that have been demonstrated by this equipment. Two major contributions were made to this project. First, a literature survey was completed to obtain available solubility and vapor-liquid equilibrium data. Some vapor-liquid data necessary for the project but not available in the literature was obtained experimentally. Second, the decontamination factor for the evaporator was determined using neutron activation analysis (NAA).

Betts, S.E. [California Univ., Santa Barbara, CA (United States)

1993-10-01

32

Isothermal vapor-liquid equilibria and solubility in the system methanol + 1,3,5-trioxane  

Microsoft Academic Search

Total vapor pressure data have been measured for the binary mixture methanol + 1,3,5-trioxane at 338, 343, 348, 353, 358, 363, and 368 K. The solubility of solid trioxane in methanol was determined from 293 to 328 K. The experimental data have been correlated using the UNIQUAC equation for the activity coefficient. In addition, the isobaric vapor-liquid equilibrium calculated predictions

Stefano Brandani; Vincenzo Brandani

1994-01-01

33

Isothermal vapor-liquid equilibria and solubility in the system methanol + 1,3,5-trioxane  

SciTech Connect

Total vapor pressure data have been measured for the binary mixture methanol + 1,3,5-trioxane at 338, 343, 348, 353, 358, 363, and 368 K. The solubility of solid trioxane in methanol was determined from 293 to 328 K. The experimental data have been correlated using the UNIQUAC equation for the activity coefficient. In addition, the isobaric vapor-liquid equilibrium calculated predictions with the obtained parameters show good agreement with the experimental data available in the literature.

Brandani, S.; Brandani, V. (Univ. de L'Aquila (Italy). Dipt. di Chimica)

1994-04-01

34

Measurement of Vapor-Liquid Equilibrium for the DME + Diisopropyl Ether Binary System and Correlation for the DME + CO2 + Diisopropyl Ether Ternary System  

NASA Astrophysics Data System (ADS)

Vapor-liquid equilibrium (VLE) data have been measured with a static-type VLE apparatus for the dimethyl ether (DME)-diisopropyl ether (DIPE) binary system at five temperatures within the range from 293.04 K to 352.70 K. An isothermal correlation for the experimental data has been carried out based on the Peng-Robinson equation of state. The regressed binary interaction parameters were used to estimate VLE for the DME-CO2-DIPE ternary system at 298.15 K. From the study, it is demonstrated that DIPE is an excellent absorbent for separation in the DME synthesis process from syngas.

Wu, Xianghong; Du, Xiaojie; Zheng, Danxing

2010-02-01

35

Isothermal vapor-liquid equilibrium data for the binaries isobutane-ethanol, isobutane-1-propanol, and propane-ethanol  

SciTech Connect

The recovery of alcohols from aqueous solutions by supercritical extraction has received considerable attention during the last decade. Light hydrocarbons appeared to be the most promising near critical fluid solvents for these separations. Vapor-liquid equilibria for the isobutane-ethanol, isobutane-1-propanol, and propane-ethanol systems were measured in the temperature range of 308.6--375.1 K and at pressures up to 43.81 bar. The results show azeotrope formation for the isobutane-ethanol system.

Zabaloy, M.S.; Gros, H.P.; Bottini, S.B.; Brignole, E.A. (PLAPIQUI-UNS/CONICET, Bahia Blanca (Argentina))

1994-04-01

36

On the Re-engineered TIP4P Water Models for the Preduction of Vapor-Liquid Equilibrium  

Microsoft Academic Search

We perform extensive Gibbs Ensemble Monte Carlo simulations to study the capability of some recently re-parameterizations of the original TIP4P model intended to predict accurately the vapor-liquid coexistence envelope of water, its critical point, and its temperature dependence for the vapor pressure and second virial coefficient, and complement this analysis with the characterization of some specific crystalline faces of ice.

Ariel A Chialvo; A. Bartok; A. Baranayai

2006-01-01

37

Proposal of a minimal expression for nonlinear fuzzy approximation for the vapor liquid equilibrium VLE of the ethanol-water system at 560 mm Hg using defuzification based on Boolean Relations DBR and Singleton model  

Microsoft Academic Search

A novel methodology is presented in order to obtain a nonlinear correlation the vapor liquid equilibrium VLE of ethanol-water system at Bogota conditions, using as nonlinear approximators the defuzification based on Boolean relations DBR, based on data obtained by thermodynamical correlations and compared with polynomial and Sugeno model in order to apply to the simulation of the distillation process.

M. J. J. Soriano; Francisco Jose de Caldas

2009-01-01

38

Vapor-liquid equilibrium of the Mg(NO/sub 3/)/sub 2/-HNO/sub 3/-H/sub 2/O system  

SciTech Connect

The vapor-liquid equilibrium of the Mg(NO/sub 3/)/sub 2/-HNO/sub 3/-H/sub 2/O system in concentrations of 0 to 70 wt % Mg(NO/sub 3/)/sub 2/ and 0 to 75 wt % HNO/sub 3/ at atmospheric pressure was correlated by two approaches. One was based on a dissociation equilibrium expression in which the activities of the reacting species (HNO/sub 3/, NO/sub 3//sup -/, and H/sup +/) were approximated with mole fractions. The activity coefficients of the undissociated HNO/sub 3/ and H/sub 2/O were correlated as functions of the concentrations of magnesium nitrate and nitric acid by second-order polynomials. The average absolute difference between predicted and experimental values was 8% for the mole fraction of acid in the vapor and 8/sup 0/K for the bubble-point temperature. The second approach was to correlate the mean ionic rational activity coefficient of water with a form of the excess Gibbs energy composed of two terms. One term, a function of the ionic strength, accounts for the coulombic (ionic) interactions; the other term accounts for the non-coulombic (molecular) interactions. The average absolute difference between predicted and experimental values was 9% for the mole fraction of acid in the vapor, and 10/sup 0/K for the bubble-point temperature.

Thompson, B.E.; Derby, J.J.; Stalzer, E.H.

1983-06-01

39

Applications of the Simple Multi-Fluid Model to Correlations of the Vapor-Liquid Equilibrium of Refrigerant Mixtures Containing Carbon Dioxide  

NASA Astrophysics Data System (ADS)

This study presents a simple multi-fluid model for Helmholtz energy equations of state. The model contains only three parameters, whereas rigorous multi-fluid models developed for several industrially important mixtures usually have more than 10 parameters and coefficients. Therefore, the model can be applied to mixtures where experimental data is limited. Vapor-liquid equilibrium (VLE) of the following seven mixtures have been successfully correlated with the model: CO2 + difluoromethane (R-32), CO2 + trifluoromethane (R-23), CO2 + fluoromethane (R-41), CO2 + 1,1,1,2- tetrafluoroethane (R-134a), CO2 + pentafluoroethane (R-125), CO2 + 1,1-difluoroethane (R-152a), and CO2 + dimethyl ether (DME). The best currently available equations of state for the pure refrigerants were used for the correlations. For all mixtures, average deviations in calculated bubble-point pressures from experimental values are within 2%. The simple multi-fluid model will be helpful for design and simulations of heat pumps and refrigeration systems using the mixtures as working fluid.

Akasaka, Ryo

40

Vapor-Liquid Equilibrium in the Systems Argon-Oxygen and Ammonia-Water Measurements and Modeling for Industrial and Planetary Applications  

NASA Astrophysics Data System (ADS)

This work presents an integrated approach for characterizing binary vapor-liquid equilibrium (VLE) through a combination of experimental measurements and thermodynamic modeling for low to medium pressure binary VLE. We focus on two dissimilar mixtures: the non-polar argon-oxygen system of importance for industrial air separation processes and the polar ammonia-water system of interest for understanding the atmospheres of Jupiter, Saturn, Uranus, and Neptune. Experimental measurements of pressure, temperature, and phase composition at equilibrium were made for the argon-oxygen system at temperatures from 92K to 115K with a cryogenic VLE apparatus. A second custom-built apparatus was used to measure VLE in the ammonia-water system from 276K to 285K. Our new data, along with existing literature data, were critically evaluated and tested for thermodynamic consistency. A thermodynamic model of the argon-oxygen system from 90K to 120K was developed using an activity coefficient approach to describe nonidealities in the liquid and the virial equation of state to characterize vapor phase nonidealities. The model employs maximum likelihood parameter fitting which takes into account uncertainties in all measured quantities and maximizes the likelihood that the model describes the true behavior of the mixture. For the ammonia-water study a new extension of the thermodynamic model to polar mixtures is presented. Our model has built-in temperature dependence for reliable extrapolation to temperatures beyond the range of the available data. The model constants can be used in a simple iterative procedure to calculate the liquid and vapor compositions of the mixture at specified temperature and pressure. As a demonstration, our ammonia-water model is used to calculate altitude-composition profiles for condensing clouds of liquid ammonia-water solution on Jupiter.

Parikh, Nimmi Chandra

1997-11-01

41

Vapor-liquid equilibria of coal-derived liquids; 3: Binary systems with tetralin at 200 mmHg  

SciTech Connect

Isobaric vapor-liquid equilibrium data are reported for binary systems of tetralin with p-xylene, [gamma]-picoline, piperidine, and pyridine; all systems were measured at 26.66 kPa (200 mmHg) with a recirculation still. Liquid-phase activity coefficients were correlated using the Van Laar, Wilson, NRTL, and UNIQUAC equations. Vapor-phase nonidealities were found negligible under the experimental conditions of this work, and deviations of the liquid phase from the ideal behavior, as described by Raoult's law, were found to be slightly positive for all the systems.

Blanco, B.; Beltran, S.; Cabezas, J.L. (University Coll., Burgos (Spain). Dept. of Chemical Engineering); Coca, J. (Univ. of Oviedo (Spain). Dept. of Chemical Engineering)

1994-01-01

42

Vapor-liquid equilibrium for methanol + 1,1-dimethylpropyl methyl ether at (288.15, 308.15, and 328.15) K  

SciTech Connect

Oxygenated compounds are being used as additives to gasoline because of their antiknock effects. Vapor-liquid equilibria for methanol + 1,1-dimethylpropyl methyl ether (tert-amyl methyl ether or TAME) have been measured at (288.15, 308.15, and 328.15) K. A Gibbs-Van Ness type apparatus for total vapor pressure measurements has been used. The system shows positive deviations from Raoult`s law with an azeotrope, whose coordinates are reported at the three temperatures studied. Results have been analyzed in terms of the UNIQUAC model, several versions of the UNIFAC model, and the modified-Huron-Vidal second-order (MHV2) group contribution equation of state.

Moessner, F.; Coto, B.; Pando, C.; Rubio, R.G.; Renuncio, J.A.R. [Universidad Complutense, Madrid (Spain). Departamento de Quimica Fisica 1] [Universidad Complutense, Madrid (Spain). Departamento de Quimica Fisica 1

1996-05-01

43

Vapor-Liquid Equilibrium and Polarization Behavior of the GCP Water Model: Gaussian Charge-on-Spring versus Dipole Self-Consistent Field Approaches to Induced Polarization.  

PubMed

We developed the Gaussian charge-on-spring (GCOS) version of the original self-consistent field implementation of the Gaussian Charge Polarizable water model and test its accuracy to represent the polarization behavior of the original model involving smeared charges and induced dipole moments. For that purpose we adapted the recently proposed multiple-particle-move (MPM) within the Gibbs and isochoric-isothermal ensembles Monte Carlo methods for the efficient simulation of polarizable fluids. We assessed the accuracy of the GCOS representation by a direct comparison of the resulting vapor-liquid phase envelope, microstructure, and relevant microscopic descriptors of water polarization along the orthobaric curve against the corresponding quantities from the actual GCP water model. PMID:25803267

Chialvo, Ariel A; Moucka, Filip; Vlcek, Lukas; Nezbeda, Ivo

2015-04-16

44

Vapor-liquid contacting system  

SciTech Connect

A vapor-liquid contacting tray is described wherein a perforated portion of the tray member forms an active surface area for vapor-liquid contact in the interior of the tray member. The active surface area portion of the tray member is circumscribed by an imperforate peripheral portion of the tray member with a width of from 0.05 to 0.35 times the radius of the tray. The disclosed tray provides upwardly directed laminar jetting of liquid over the tray perforation openings for high selectivity vapor-liquid contacting and has particular utility in the absorption of hydrogen sulfide from a gas mixture containing hydrogen sulfide and carbon dioxide.

Butwell, K.F.; Sigmund, P.W.

1981-10-27

45

Densities and vapor-liquid equilibria in binary mixtures formed by propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol at 160.0 kPa  

SciTech Connect

Densities and excess volumes were determined at 298.15 K for propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol. The results of those quantities were then correlated to get the concentrations of vapor-liquid equilibrium obtained isobarically at 160 kPa for the same mixtures. Two mixtures show azeotropes: for propyl methanoate (1) + ethanol (2), x{sub 1} = 0.443 at T = 358.7 K; and for propyl methanoate (1) + propan-1-ol (2), x{sub 1} = 0.762 at T = 368.2 K. The mixtures are thermodynamically consistent, and the predictions made using several group-contribution models are satisfactory.

Falcon, J.; Ortega, J.; Gonzalez, E. [Escuela Superior de Ingenieros Industriales, Las Palmas (Spain). Laboratorio de Termodinamica y Fisicoquimica] [Escuela Superior de Ingenieros Industriales, Las Palmas (Spain). Laboratorio de Termodinamica y Fisicoquimica

1996-07-01

46

Vapor+Liquid Equilibrium Measurements and Correlation of the Binary Refrigerant Mixtures Difluoromethane (HFC32)+1,1,1,2,3,3-Hexafluoropropane (HFC236ea) and Pentafluoroethane (HFC125)+1,1,1,2,3,3-Hexafluoropropane (HFC236ea) at 288.6, 303.2, and 318.2 K  

Microsoft Academic Search

Isothermal vapor–liquid equilibria (VLE) for the binary systems of difluoromethane (HFC-32)+1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and pentafluoroethane (HFC-125)+1,1,1,2,3,3-hexafluoropropane (HFC-236ea) were measured at 288.6, 303.2, and 318.2 K using an apparatus in which the vapor phase was recirculated through the liquid. The phase composition at equilibrium was measured by gas chromatography, based on calibration using gravimetrically prepared mixtures. Both systems show a slight deviation

S. Bobbo; L. Fedele; M. Scattolini; R. Camporese

2000-01-01

47

Calculation of vapor-liquid equilibrium and PVTx properties of geological fluid system with SAFT-LJ EOS including multi-polar contribution. Part III. Extension to water-light hydrocarbons systems  

NASA Astrophysics Data System (ADS)

The SAFT-LJ EOS improved by Sun and Dubessy (2010, 2012) is extended to water-light hydrocarbon systems. Light hydrocarbons (including CH4, C2H6, C3H8 and nC4H10) are modeled as chain molecules without multi-polar moments. The contributions of the shape of molecules and main intermolecular interactions existing in water-light hydrocarbon systems (including repulsive and attractive forces between Lennard-Jones segments, the hydrogen-bonding force and the multi-polar interaction between water molecules) to the residual Helmholtz energy were accounted for by this EOS. The adjustable parameters for the interactions of H2O-CH4, H2O-C2H6, H2O-C3H8, and H2O-nC4H10 pairs were evaluated from mutual solubility data of binary water-hydrocarbon systems at vapor-liquid equilibria. Comparison with the experimental data shows this SAFT-LJ EOS can represent well vapor-liquid (and liquid-liquid) equilibria of binary water-light hydrocarbon systems over a wide P-T range. The accuracy of this EOS for mutual solubilities of methane, ethane, propane and water is within the experimental uncertainty generally. Moreover, the model is able to accurately predict the vapor-liquid equilibria and PVTx properties of multi-component systems composed of water, light hydrocarbon as well as CO2. As we know, this EOS is the first one allowing quantitative calculation of the mutual solubilities of water and light hydrocarbons over a wide P-T range among SAFT-type EOSs. This work indicates that the molecular-based EOS combined with conventional mixing rule can well describe the thermodynamic behavior of highly non-ideal systems such as water-light hydrocarbons mixtures except in the critical region for which long range density fluctuations cannot be taken into account by this analytical model.

Sun, Rui; Lai, Shaocong; Dubessy, Jean

2014-01-01

48

Vapor-Liquid Equilibria Using the Gibbs Energy and the Common Tangent Plane Criterion  

ERIC Educational Resources Information Center

Phase thermodynamics is often perceived as a difficult subject with which many students never become fully comfortable. The Gibbsian geometrical framework can help students to gain a better understanding of phase equilibria. An exercise to interpret the vapor-liquid equilibrium of a binary azeotropic mixture, using the equilibrium condition based…

Olaya, Maria del Mar; Reyes-Labarta, Juan A.; Serrano, Maria Dolores; Marcilla, Antonio

2010-01-01

49

Vapor–liquid equilibria of carbon dioxide with isopropyl acetate, diethyl carbonate and ethyl butyrate at elevated pressures  

Microsoft Academic Search

Vapor–liquid equilibria for carbon dioxide with three esters of isopropyl acetate, diethyl carbonate and ethyl butyrate were measured in this study at 308.45, 313.45 and 318.55K and at elevated pressures up to 8.9MPa. A static type phase equilibrium apparatus with visual sapphire windows was used in the experimental measurements. Equilibrium compositions in both vapor and liquid phases and the vapor–liquid

Chen-His Cheng; Yan-Ping Chen

2005-01-01

50

Semi-empirical correlation for binary interaction parameters of the Peng–Robinson equation of state with the van der Waals mixing rules for the prediction of high-pressure vapor–liquid equilibrium  

PubMed Central

Peng–Robinson equation of state is widely used with the classical van der Waals mixing rules to predict vapor liquid equilibria for systems containing hydrocarbons and related compounds. This model requires good values of the binary interaction parameter kij. In this work, we developed a semi-empirical correlation for kij partly based on the Huron–Vidal mixing rules. We obtained values for the adjustable parameters of the developed formula for over 60 binary systems and over 10 categories of components. The predictions of the new equation system were slightly better than the constant-kij model in most cases, except for 10 systems whose predictions were considerably improved with the new correlation. PMID:25685411

Fateen, Seif-Eddeen K.; Khalil, Menna M.; Elnabawy, Ahmed O.

2012-01-01

51

Prediction of vapor-liquid equilibrium and PVTx properties of geological fluid system with SAFT-LJ EOS including multi-polar contribution. Part II: Application to H2O-NaCl and CO2-H2O-NaCl System  

NASA Astrophysics Data System (ADS)

The SAFT-LJ equation of state improved by Sun and Dubessy (2010) can represent the vapor-liquid equilibrium and PVTx properties of the CO2-H2O system over a wide P-T range because it accounts for the energetic contribution of the main types of molecular interactions in terms of reliable molecular based models. Assuming that NaCl fully dissociates into individual ions (spherical Na+ and Cl-) in water and adopting the restricted primitive model of mean spherical approximation to account for the energetic contribution due to long-range electrostatic forces between ions, this study extends the improved SAFT-LJ EOS to the H2O-NaCl and the CO2-H2O-NaCl systems at temperatures below 573 K. The EOS parameters for the interactions between ion and ion and between ion and water were determined from the mean ionic activity coefficient data and the density data of the H2O-NaCl system. The parameters for the interactions between ion and CO2 were evaluated from CO2 solubility data of the CO2-H2O-NaCl system. Comparison with the experimental data shows that this model can predict the mean ionic activity coefficient, osmotic coefficient, saturation pressure, and density of aqueous NaCl solution and can predict the vapor-liquid equilibrium and PVTx properties of the CO2-H2O-NaCl system over the range from 273 to 573 K, from 0 to 1000 bar, and from 0 to 6 mol/kg NaCl with high accuracy.

Sun, Rui; Dubessy, Jean

2012-07-01

52

Vapor-Liquid Equilibria for Some Concentrated Aqueous PolymerSolutions  

SciTech Connect

Vapor-liquid-equilibrium data were obtained for binary aqueous solutions of six water-soluble linear polymers in the range 70-95 C. A classical gravimetric sorption method was used to measure the amount of solvent absorbed as a function of vapor-phase water pressure. Polymers studied were polyvinylpyrrolidone, polyethyleneoxide, polyvinylalcohol, hydroxyethylcellulose, polyethylenimine, polymethylvinylether. The experimental data were reduced with Hino's lattice model that distinguished the interactions due to London dispersion forces and those due to hydrogen bonding.

Striolo, Alberto; Prausnitz, John M.

1999-07-01

53

Calculation of Vapor-Liquid-Liquid Equilibria for the Fischer-Tropsch Reactor Effluents using Modified Peng-Robinson  

E-print Network

Calculation of Vapor-Liquid-Liquid Equilibria for the Fischer- Tropsch Reactor Effluents using of state (EOS) ]1[ has been extended to include additional groups relevant to GTL products. A key point ignored the non-ideal phase equilibrium problem of a FT reactor. The rigorous calculation method is based

Skogestad, Sigurd

54

Molecular dynamics study on the vapor-liquid interface of Ar-Ne mixtures  

NASA Astrophysics Data System (ADS)

An interface between an Ar-Ne gas mixture and its own liquid mixture in an equilibrium state has been studied by molecular dynamics simulation with 12-6 Lennard-Jones potential and Lorentz-Berthelot mixing rule. As a result, we accurately evaluate macroscopic variables, and carefully discuss the difference between the stress defined by Bearman and Kirkwood (1958) and that defined by the method of control surface. The result shows that the stress defined by Bearman and Kirkwood is not suitable for describing the detailed structure of vapor-liquid interface of Ar-Ne mixture.

Yamaguchi, Kyohei; Inaba, Masashi; Yano, Takeru

2014-12-01

55

Combination downflow-upflow vapor-liquid separator  

DOEpatents

An improved vapor-liquid separator having a vertically disposed conduit for flow of a mixture. A first, second and third plurality of curved arms penetrate and extend within the conduit. A cylindrical member is radially spaced from the conduit forming an annulus therewith and having perforations and a retaining lip at its upper end.

Kidwell, John H. (Uniontown, OH); Prueter, William P. (Alliance, OH); Eaton, Andrew M. (Alliance, OH)

1987-03-10

56

A search for the prewetting line. [in binary liquid system at vapor-liquid interface  

NASA Technical Reports Server (NTRS)

This paper describes efforts to locate the prewetting line in a binary liquid system (isopropanol-perfluoromethylcyclohexane) at the vapor-liquid interface. Tight upper bounds were placed on the temperature separation (0.2 K) between the prewetting line and the line of bulk liquid phase separation. The prewetting line in systems at equilibrium was not detected. Experimental signatures indicative of the prewetting line occurred only in nonequilibrium situations. Several theories predict that the adsorption of one of the components (the fluorocarbon, in this case) at the liquid-vapor interface should increase abruptly, at a temperature sightly above the temperature at which the mixture separates into two liquid phases. A regular solution calculation indicates that this prewetting line should have been easily detectable with the instruments used in this experiment. Significant features of the experiment are: (1) low-gradient thermostatting, (2) in situ stirring, (3) precision ellipsometry from the vapor-liquid interface, (4) high resolution differential index of refraction measurements using a novel cell design, and (5) computer control.

Schmidt, J. W.; Moldover, M. R.

1986-01-01

57

Vapor-liquid equilibria for alcohol + alcohol + sodium iodide at 298.15 K  

SciTech Connect

Estimation and correlation of phase equilibria data in chemical engineering are indispensable for the design of equilibrium separation processes. If a salt, being completely nonvolatile, is added to the solvent mixture, the relative volatility generally changes; this is known as the salting-in or -out effect on vapor-liquid equilibria. Vapor-liquid equilibria for methanol + propan-1-ol + NaI, methanol + propan-2-ol + NaI, ethanol + propan-1-ol + NaI, and ethanol + propan-2-ol + NaI systems were measured at 298.15 K using a static method. The apparatus was tested by comparing results for ethanol + water and ethanol + water + CaCl{sub 2} with literature results. Results were tested for thermodynamic consistency by Herinton`s area test and point test. NaI exerted a salting-in effect on all binary alcohol solutions and the order of the salt effect of NaI was methanol + ethanol < ethanol + propan-1-ol < ethanol + propan-2-ol < methanol + propan-1-ol < methanol + propan-2-ol. Hala`s model was applied for the correlation of four alcohol + alcohol + salt systems using observed data. Calculated {beta} values in Hala`s equation were between 2.8 and 3.9 for the four alcohol + alcohol + NaI systems.

Yamamoto, H.; Fukase, K.; Shibata, J. [Kansai Univ., Suita, Osaka (Japan)] [Kansai Univ., Suita, Osaka (Japan)

1996-09-01

58

Silicon nanowire synthesis by a vapor-liquid-solid approach  

NASA Technical Reports Server (NTRS)

Synthesis of silicon nanowires is studied by using a vapor-liquid-solid growth technique. Silicon tetrachloride reduction with hydrogen in the gas phase is used with gold serving as catalyst to facilitate growth. Only a narrow set of conditions of SiCl4 concentration and temperature yield straight nanowires. High concentrations and temperatures generally result in particulates, catalyst coverage and deactivation, and coatinglike materials.

Mao, Aaron; Ng, H. T.; Nguyen, Pho; McNeil, Melanie; Meyyappan, M.

2005-01-01

59

Vapor-liquid Coexistence Curves for Methanol and Methane using Dispersion-Corrected Density Functional Theory  

SciTech Connect

First principles Monte Carlo simulations in the Gibbs and isobaric-isothermal ensembles were performed to map the vapor-liquid coexistence curves (VLCC) of methanol and methane described by Kohn-Sham density functional theory using the Becke-Lee-Yang-Parr (BLYP) exchange and correlation functionals with the Grimme correction term for dispersive (D2) interactions. The simulations indicate that the BLYP-D2 description underpredicts the saturated vapor densities and overpredicts the saturated liquid densities and critical and boiling temperatures for both compounds. Although the deviations are quite large, these results present a significant improvement over the BLYP functional without the correction term which misses the experimental results by a larger extent in the opposite direction. With the D2 correction, an increase in the basis set does not lead to significant changes in the VLCC properties. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

McGrath, Matthew J.; Kuo, I-F W.; Ghogomu, Julius N.; Mundy, Christopher J.; Siepmann, Joern I.

2011-10-13

60

Molecular model for carbon dioxide optimized to vapor-liquid equilibria  

NASA Astrophysics Data System (ADS)

A molecular model for carbon dioxide is presented, and the parameters of the Lennard-Jones sites, the bond length, and the quadrupole moment are optimized to experimental vapor-liquid equilibrium data. The resulting molecular model shows mean unsigned deviations to the experiment over the whole temperature range from triple point to critical point of 0.4% in saturated liquid density, 1.8% in vapor pressure, and 8.1% in enthalpy of vaporization. The molecular model is assessed by comparing predicted thermophysical properties with experimental data and a reference equation of state for a large part of the fluid region. The average deviations for density and residual enthalpy are 4.5% and 1.7%, respectively. The model is also capable to predict the radial distribution function, the second virial coefficient, and transport properties, the average deviations of the latter are 12%.

Merker, Thorsten; Engin, Cemal; Vrabec, Jadran; Hasse, Hans

2010-06-01

61

Vapors-liquid phase separator. [infrared telescope heat sink  

NASA Technical Reports Server (NTRS)

The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

1980-01-01

62

Vapor–liquid equilibria for pentafluoroethane + propane and difluoromethane + propane systems over a temperature range from 253.15 to 323.15 K  

Microsoft Academic Search

This paper provides vapor–liquid equilibrium (VLE) data obtained for two binary systems of pentafluoroethane (R125)+propane (R290) and difluoromethane (R32)+R290 over a temperature range from 253.15 to 323.15K. The measurement of VLE was performed at isothermal conditions in a vapor recirculation apparatus. Both systems form azeotropes in the temperature range of this study. The experimental results were well correlated with the

Ju Hyok Kim; Min Soo Kim; Youngil Kim

2003-01-01

63

A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties  

E-print Network

A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties Jeffrey R@ipst.umd.edu #12;1 Abstract A new fixed-point charge potential model for water has been developed, targeting the accurate prediction of the vapor-liquid coexistence properties over a broad temperature range. The model

64

Effect of dimensionality on vapor-liquid phase transition  

SciTech Connect

Dimensionality play significant role on ‘phase transitions’. Fluids in macroscopic confinement (bulk or 3-Dimensional, 3D) do not show significant changes in their phase transition properties with extent of confinement, since the number of molecules away from the surrounding surfaces is astronomically higher than the number of molecules in close proximity of the confining surfaces. In microscopic confinement (quasi 3D to quasi-2D), however, the number of molecules away from the close proximity of the surface is not as high as is the case with macroscopic (3D) confinement. Hence, under the same thermodynamic conditions ‘phase transition’ properties at microscopic confinement may not remain the same as the macroscopic or 3D values. Phase transitions at extremely small scale become very sensitive to the dimensions as well as the surface characteristics of the system. In this work our investigations reveal the effect of dimensionality on the phase transition from 3D to quasi-2D to 2D behavior. We have used grand canonical transition matrix Monte Carlo simulation to understand the vapor–liquid phase transitions from 3D to quasi-2D behavior. Such studies can be helpful in understanding and controlling the fluid film behaviour confined between solid surfaces of few molecular diameters, for example, in lubrication applications.

Singh, Sudhir Kumar, E-mail: sksingh@thapar.edu [Department Chemical Engineering, Thapar University, Patiala-147004 Punjab (India)

2014-04-24

65

Extended vapor-liquid-solid growth of silicon carbide nanowires.  

PubMed

We developed an alloy catalytic method to explain extended vapor-liquid-solid (VLS) growth of silicon carbide nanowires (SiC NWs) by a simple thermal evaporation of silicon and activated carbon mixture using lanthanum nickel (LaNi5) alloy as catalyst in a chemical vapor deposition process. The LaNi5 alloy binary phase diagram and the phase relationships in the La-Ni-Si ternary system were play a key role to determine the growth parameters in this VLS mechanism. Different reaction temperatures (1300, 1350 and 1400 degrees C) were applied to prove the established growth process by experimentally. Scanning electron microscopy and transmission electron microscopy studies show that the crystalline quality of the SiC NWs increases with the temperature at which they have been synthesized. La-Ni alloyed catalyst particles observed on the top of the SiC NWs confirms that the growth process follows this extended VLS mechanism. The X-ray diffraction and confocal Raman spectroscopy analyses demonstrate that the crystalline structure of the SiC NWs was zinc blende 3C-SiC. Optical property of the SiC NWs was investigated by photoluminescence technique at room temperature. Such a new alloy catalytic method may be extended to synthesis other one-dimensional nanostructures. PMID:24734687

Rajesh, John Anthuvan; Pandurangan, Arumugam

2014-04-01

66

Structure/processing relationships in vapor-liquid-solid nanowire epitaxy  

E-print Network

The synthesis of Si and III-V nanowires using the vapor-liquid-solid (VLS) growth mechanism and low-cost Si substrates was investigated. The VLS mechanism allows fabrication of heterostructures which are not readily ...

Boles, Steven Tyler

2010-01-01

67

A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism  

NASA Astrophysics Data System (ADS)

We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei

2014-07-01

68

Equilibrium  

NSDL National Science Digital Library

Using a visual approach, this applet is designed to help students learn to solve equilibrium calculations and also to help them gain a deeper understanding of the topic. It can be used by the instructor in the classroom as equilibrium topics are introduced. Sample exercises for students are included. The text is available in both English and Spanish.

69

Magnetotail dynamics under isobaric constraints  

NASA Technical Reports Server (NTRS)

Using linear theory and nonlinear MHD simulations, we investigate the resistive and ideal MHD stability of two-dimensional plasma configurations under the isobaric constraint dP/dt = 0, which in ideal MHD is equivalent to conserving the pressure function P = P(A), where A denotes the magnetic flux. This constraint is satisfied for incompressible modes, such as Alfven waves, and for systems undergoing energy losses. The linear stability analysis leads to a Schroedinger equation, which can be investigated by standard quantum mechanics procedures. We present an application to a typical stretched magnetotail configuration. For a one-dimensional sheet equilibrium characteristic properties of tearing instability are rediscovered. However, the maximum growth rate scales with the 1/7 power of the resistivity, which implies much faster growth than for the standard tearing mode (assuming that the resistivity is small). The same basic eigen-mode is found also for weakly two-dimensional equilibria, even in the ideal MHD limit. In this case the growth rate scales with the 1/4 power of the normal magnetic field. The results of the linear stability analysis are confirmed qualitatively by nonlinear dynamic MHD simulations. These results suggest the interesting possibility that substorm onset, or the thinning in the late growth phase, is caused by the release of a thermodynamic constraint without the (immediate) necessity of releasing the ideal MHD constraint. In the nonlinear regime the resistive and ideal developments differ in that the ideal mode does not lead to neutral line formation without the further release of the ideal MHD constraint; instead a thin current sheet forms. The isobaric constraint is critically discussed. Under perhaps more realistic adiabatic conditions the ideal mode appears to be stable but could be driven by external perturbations and thus generate the thin current sheet in the late growth phase, before a nonideal instability sets in.

Birn, Joachim; Schindler, Karl; Janicke, Lutz; Hesse, Michael

1994-01-01

70

Characteristics of countercurrent vapor-liquid flow at a perforated plate  

E-print Network

CHARACTERISTICS OF COUNTERCURRENT VAPOR-LIQUID FLOW AT A PERFORATED PLATE A Thesis by ~mr?~ a( 64(. lt'o~ (SAM) SUTHERLAND, JR. Subm1tted to the Graduate School of the Agricultural and Mechan1cal College of Texas 1n partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE ~Zanusr19%8, MaJor subJect: Chemical Eng1neering CHARACTERISTICS OF COUNTERCURRENT VAPOR-LIQUID PLOW AT A PERFORATED PLATE A Thesis by SAN SUTHERLAND, JR. Approved as to style and content by: C a rman o...

Sutherland, Samuel Shelton

1958-01-01

71

Vapor–Liquid Equilibria of CFC Alternative Refrigerant Mixtures: Trifluoromethane (HFC23)+Difluoromethane (HFC32), Trifluoromethane (HFC23)+Pentafluoroethane (HFC125), and Pentafluoroethane (HFC125)+1,1-Difluoroethane (HFC152a)  

Microsoft Academic Search

Isothermal vapor–liquid equilibria for three binary mixtures of CFC alternative refrigerants were determined in an equilibrium apparatus in which both phases were continuously recirculated. The pressures and vapor and liquid compositions were measured for the binary systems trifluoromethane (HFC-23)+difluoromethane (HFC-32) and trifluoromethane (HFC-23)+pentafluoroethane (HFC-125) at 283.15 and 293.15 K and pentafluoroethane (HFC-125)+1,1-difluoroethane (HFC-152a) at 293.15 K. The experimental data were

J. S. Lim; J.-Y. Park; B.-G. Lee

2000-01-01

72

Detecting Isobaric VOCs  

SciTech Connect

Volatile organic compounds (VOCs) can be monitored by proton transfer reaction (PTR) MS, in which a PTR drift tube is coupled to a quadrupole mass spectrometer. In this technique, compounds undergo proton transfer reactions when they collide with H?O? ions. This soft chemical ionization method, which results in little fragmentation, allows researchers to detect trace levels of VOCs from relatively uncomplicated spectra. Sometimes, the m/z values of VOCs are similar or identical, rendering it impossible to make a positive identification. Thus, Michael Alexander and co-workers at the Pacific Northwest National Laboratory, San Francisco State University, and Innsbruck University (Austria) developed a novel instrument that couples a PTR drift tube to an ion trap mass spectrometer, which can perform MS/MS, to produce characteristic fragments of isobaric species.

Prazeller, Peter; Palmer, Peter T.; Boscaini, Elena; Jobson, B Tom; Alexander, M. Lizabeth

2003-09-01

73

Measurement of the Bending Strength of Vapor-Liquid-Solid Grown Silicon Nanowires  

Microsoft Academic Search

The fracture strength of silicon nanowires grown on a (111) silicon substrate by the vapor-liquid-solid process was measured. The nanowires, with diameters between 100 and 200 nm and a typical length of 2 Ìm, were subjected to bending tests using an atomic force microscopy setup inside a scanning electron microscope. The average strength calculated from the maximum nanowire deflection before

Samuel Hoffmann; Ivo Utke; Benedikt Moser; Johann Michler; Silke H. Christiansen; Volker Schmidt; Stephan Senz; Peter Werner; Ulrich Gösele; Christophe Ballif

2006-01-01

74

Naturally occurring vapor-liquid-solid (VLS) Whisker growth of germanium sulfide  

USGS Publications Warehouse

The first naturally occurring terrestrial example of vapor-liquid-solid (VLS) growth has been observed in condensates from gases released by burning coal in culm banks. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis indicate that the crystals consist of elongated rods (??? 100 ??m) of germanium sulfide capped by bulbs depleted in germanium. ?? 1974.

Finkelman, R.B.; Larson, R.R.; Dwornik, E.J.

1974-01-01

75

Additive and nonadditive models of vapor-liquid equilibrium in CO2 from first principles.  

PubMed

We describe quantum-chemical calculations on dimers of CO(2) and use the results to develop first-principles models for Gibbs ensemble Monte Carlo simulations of the phase coexistence curve. Isotropic pairwise potentials are insufficient to model the phase behavior and overestimate the binding in liquid CO(2) by 4 kJ mol(-1). An anisotropic treatment of the atoms in the pairwise potential reduces the strength of the binding by approximately 0.5 kJ mol(-1). We use ab initio calculations on trimers of CO(2) to assess the strength of nonadditive interactions. Including nonadditive dispersion in Gibbs ensemble simulations gives an enthalpy of vaporization within 1.5 kJ mol(-1) of the experimental value over a wide range of temperatures. PMID:19173513

Oakley, Mark T; Wheatley, Richard J

2009-01-21

76

Additive and nonadditive models of vapor-liquid equilibrium in CO2 from first principles  

NASA Astrophysics Data System (ADS)

We describe quantum-chemical calculations on dimers of CO2 and use the results to develop first-principles models for Gibbs ensemble Monte Carlo simulations of the phase coexistence curve. Isotropic pairwise potentials are insufficient to model the phase behavior and overestimate the binding in liquid CO2 by 4 kJ mol-1. An anisotropic treatment of the atoms in the pairwise potential reduces the strength of the binding by ˜0.5 kJ mol-1. We use ab initio calculations on trimers of CO2 to assess the strength of nonadditive interactions. Including nonadditive dispersion in Gibbs ensemble simulations gives an enthalpy of vaporization within 1.5 kJ mol-1 of the experimental value over a wide range of temperatures.

Oakley, Mark T.; Wheatley, Richard J.

2009-01-01

77

Effects of vapor-liquid equilibrium on wetting efficiency in hydrodesulfurization trickle-bed reactors  

E-print Network

coefficients; (8) pressure drop does not influence the conversion; (9) plug flow of the liquid phase. Bondi (1971) developed an empirical relationship between the ob- served reaction rate constant, k , in a trickle-bed to the intrinsic 0 rate constant, k...

Mills, Anna Lisa

1988-01-01

78

Vapor-liquid phase equilibrium in systems with multiple chemical reactions  

Microsoft Academic Search

We introduce a new set of composition variables for treating phase equilibria in multicomponent, multi-reaction systems with or without inert components present. These variables provide a way of reducing the dimensionality of the problem and simplifying the analysis. We find that reactive azeotropes occur at points of equal transformed composition in each phase, but not equal mole fraction. Therefore, phase

Sophie Ung; Michael F. Doherty

1995-01-01

79

Vapor liquid equilibria on the ternary lithium fluoride-sodium fluoride-beryllium fluoride system  

NASA Astrophysics Data System (ADS)

Molten mixtures of LiF, NaF, and BeF2 (FLiNaBe) have been proposed as a liquid first wall for selected fusion reactor designs. Because currently envisaged reactor technologies for igniting and/or sustaining a, fusion reaction require vacuum conditions, the volatility of these liquids is an issue for concern. Many physical properties of the ternary LiF-NaF-BeF 2 (FLiNaBe) system have already been studied as part of the molten salt reactor program, but the vapor pressure has not been measured. A study of the vapor liquid equilibrium of FLiNaBe by Thermogravimetric Analysis (TGA) and Knudsen Cell Mass Spectrometry (KCMS) is presented. The ternary system is treated as a pseudo-binary system by fixing the ratio of LiF:NaF and varying the amount of BeF2. Measurements have been performed over a composition range of 0.3--0.8 mole fraction BeF2 and from 875--975K. Experimental data, are correlated in terms of the BeF 2 activity coefficient. Measurements were also carried out on the binary systems LiF-BeF2 and NaF-BeF2. Measured values of the BeF2 activity coefficient in the binary LiF-BeF2 and NaF-BeF2 systems compare satisfactorily with previous results published in the research literature. The vapor phase of FLiNaBe was found to consist of primarily the species BeF2, LiBeF3, and NaBeF 3 over the temperature and composition range studied. Mixtures of BeF2-containing fluoride salts are highly non-ideal; the BeF2 activity coefficient exhibits both positive and negative deviations from ideality over the composition range studied. An associated solution model with 3 adjustable parameters is used to fit the BeF2 activity coefficient data of the LiF-BeF2 and NaF-BeF2 systems. The parameters obtained from fitting binary data are then used to fit the ternary system. The extension of the model to the ternary system results in a single additional parameter that can only be determined from fitting ternary data. Overall the agreement between the model and experimental data is within ˜30% and the model can be used to predict the vapor pressure over a wide composition range.

Fukuda, Grant Takeshi

80

System NaCl-HâO: relations of vapor-liquid near the critical temperature of water and of vapor-liquid-halite from 300° to 500°C  

Microsoft Academic Search

Vapor-liquid relations (P-T-x) for the system NaCl-HâO were determined experimentally at temperatures spanning the critical temperature of water (T\\/sub c\\/), the lowest temperature in the system at which critical behavior occurs. In addition, vapor-liquid-halite P-T-x (vapor) relations were determined from 300° to 500°C. Results show that at 373.0°C, immediately below T\\/sub c\\/, the vapor side of the isothermal vapor-liquid P-x

J. L. Bischoff; R. J. Rosenbauer; K PITZER

1986-01-01

81

Isobaric groundwater well  

SciTech Connect

A method is described for measuring a parameter in a well, under isobaric conditions, including such parameters as hydraulic gradient, pressure, water level, soil moisture content and/or aquifer properties. The method as presented comprises providing a casing having first and second opposite ends, and a length between the ends, the casing supporting a transducer having a reference port; placing the casing lengthwise into the well, second end first, with the reference port vented above the water table in the well; and sealing the first end. A system is presented for measuring a parameter in a well, the system comprising a casing having first and second opposite ends, and a length between the ends and being configured to be placed lengthwise into a well second end first; a transducer, the transducer having a reference port, the reference port being vented in the well above the water table, the casing being screened across and above the water table; and a sealing member sealing the first end. In one embodiment, the transducer is a tensiometer transducer and in other described embodiments, another type transducer is used in addition to a tensiometer.

Hubbell, J.M.; Sisson, J.B.

1999-10-19

82

Isobaric groundwater well  

DOEpatents

A method of measuring a parameter in a well, under isobaric conditions, including such parameters as hydraulic gradient, pressure, water level, soil moisture content and/or aquifer properties the method as presented comprising providing a casing having first and second opposite ends, and a length between the ends, the casing supporting a transducer having a reference port; placing the casing lengthwise into the well, second end first, with the reference port vented above the water table in the well; and sealing the first end. A system is presented for measuring a parameter in a well, the system comprising a casing having first and second opposite ends, and a length between the ends and being configured to be placed lengthwise into a well second end first; a transducer, the transducer having a reference port, the reference port being vented in the well above the water table, the casing being screened across and above the water table; and a sealing member sealing the first end. In one embodiment, the transducer is a tensiometer transducer and in other described embodiments, another type transducer is used in addition to a tensiometer.

Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)

1999-01-01

83

Vapor-liquid-liquid equilibria of pentafluoroethane and ionic liquid [bmim][PF6] mixtures studied with the volumetric method.  

PubMed

In this article, we investigate vapor-liquid-liquid equilibria (VLLE) of binary systems using a simple volumetric method. Being different from the usual cloud-point method for the determination of liquid-liquid separation boundaries, the present volumetric method is able to determine the direct VLLE properties, such as equilibrium compositions, as well as molar volumes of the two liquid phases, by measuring only weights and volumes of liquid samples. The theory behind this method is described, and detailed error analyses for our simple apparatus are discussed by using well-established systems in the literature: water + 2-butanol and 1-butanol + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]). Then, results for mixtures of [bmim][PF(6)] and pentafluoroethane (R-125) are provided, as well as those of the test systems above. As predicted in our earlier work, this binary system shows liquid-liquid separations in the R-125-rich side solutions with a lower critical solution temperature. In addition, we have found very large negative excess molar volumes in this system. PMID:16854153

Shiflett, Mark B; Yokozeki, A

2006-07-27

84

Subcontracted R and D final report: SRC-I phase equilibrium and enthalpy data for coal liquefaction and solvent recovery areas. Volume 2  

Microsoft Academic Search

Vapor-liquid equilibrium measurements were taken for coal liquids in contact with various pre-mixed gases consisting mostly of Hâ, Nâ, CO, HâS, and light hydrocarbons, as well as coal liquids in contact with Hâ and ethane mixtures to simulate SRC-I Demonstration Plant. Additionally, vapor-liquid equilibrium measurements were performed with hydrogen in contact with various pure components for correlation purposes. Temperatures ranged

D. C. Mehta; I. C. Chu

1984-01-01

85

Vapor-liquid equilibria for difluoromethane (R32) + and pentafluoroethane (R125) + 1,1,1,3,3,3-hexafluoropropane (R236fa) at 303.2 and 323.3 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibria (VLE) for the binary systems difluoromethane (R32) + 1,1,1,3,3,3-hexafluoropropane (R236fa) and pentafluoroethane (R125) + 1,1,1,3,3,3-hexafluoropropane (R236f) were measured at 303.2 and 323.3 K using a recirculation apparatus in which the vapor phase was forced through the liquid. The phase composition at equilibrium was measured by gas chromatography, calibrating its response using gravimetrically prepared mixtures. Both systems show

Sergio Bobbo; Roberto Camporese; Roman Stryjek

1999-01-01

86

Water-mediated ion-ion interactions are enhanced at the water vapor-liquid interface.  

PubMed

There is overwhelming evidence that ions are present near the vapor-liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion-ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor-liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. "Sticky" electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from ?-helical to a hairpin-turn-like one in response to charging of its ends. PMID:24889634

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-06-17

87

Low-temperature, vapor–liquid–solid, laterally grown silicon films using alloyed catalysts  

NASA Astrophysics Data System (ADS)

Using amorphous oxide templates known as micro-crucibles which confine a vapor–liquid–solid catalyst to a specific geometry, two-dimensional silicon thin-films of a single orientation have been grown laterally over an amorphous substrate and defects within crystals have been necked out. The vapor–liquid–solid catalysts consisted nominally of 99% gold with 1% titanium, chromium, or aluminum, and each alloy affected the processing of micro-crucibles and growth within them significantly. It was found that chromium additions inhibited the catalytic effect of the gold catalysts, titanium changed the morphology of the catalyst during processing and aluminum stabilized a potential third phase in the gold–silicon system upon cooling. Two mechanisms for growing undesired nanowires were identified both of which hindered the VLS film growth, fast silane cracking rates and poor gold etching, which left gold nanoparticles near the gold–vapor interface. To reduce the silane cracking rates, growth was done at a lower temperature while an engineered heat and deposition profile helped to reduce NWs caused by the second mechanism. Through experimenting with catalyst compositions, the fundamental mechanisms which produce concentration gradients across the gold–silicon alloy within a given micro-crucible have been proposed. Using the postulated mechanisms, micro-crucibles were designed which promote high-quality, single crystal growth of semiconductors.

LeBoeuf, Jerome L.; Brodusch, Nicolas; Gauvin, Raynald; Quitoriano, Nathaniel J.

2014-12-01

88

Water-mediated ion–ion interactions are enhanced at the water vapor–liquid interface  

PubMed Central

There is overwhelming evidence that ions are present near the vapor–liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion–ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor–liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. “Sticky” electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from ?-helical to a hairpin-turn–like one in response to charging of its ends. PMID:24889634

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-01-01

89

Nimbus 7 SMMR derived seasonal variations in the water vapor, liquid water, and surface winds over the global oceans  

NASA Technical Reports Server (NTRS)

A study based on monthly mean maps of atmospheric water vapor, liquid water, and surface wind derived from Nimbus-7 SMMR over the oceans for 13 months, is examined. A discussion of the retrieval technique used to derive the parameters is presented. The seasonal changes in the strength and position of several of the parameter features are revealed by the December 1978 and June 1979 maps. Zonal averages of the water vapor, liquid water, and surface wind for December and June are compared with information derived from conventional measurements and the results are presented in graphs.

Prabhakara, C.; Short, D. A.

1984-01-01

90

Vapor-liquid phase equilibria of water modelled by a Kim-Gordon potential  

SciTech Connect

Gibbs ensemble Monte Carlo simulations were carried out to investigate the properties of a frozen-electron-density (or Kim-Gordon, KG) model of water along the vapor-liquid coexistence curve. Because of its theoretical basis, such a KG model provides for seamless coupling to Kohn-Sham density functional theory for use in mixed quantum mechanics/molecular mechanics (QM/MM) implementations. The Gibbs ensemble simulations indicate rather limited transferability of such a simple KG model to other state points. Specifically, a KG model that was parameterized by Barker and Sprik to the properties of liquid water at 300 K, yields saturated vapor pressures and a critical temperature that are significantly under- and over-estimated, respectively.

Maerzke, K A; McGrath, M J; Kuo, I W; Tabacchi, G; Siepmann, J I; Mundy, C J

2009-03-16

91

Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism  

SciTech Connect

Indium tin oxide nanowires were grown by the reaction of In and Sn with O{sub 2} at 800?°C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In{sub 2}O{sub 3} nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO{sub 2} and suppression of In{sub 2}O{sub 3} permitting compositional and structural tuning from SnO{sub 2} to In{sub 2}O{sub 3} which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

Zervos, M., E-mail: zervos@ucy.ac.cy; Giapintzakis, J. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Mihailescu, C. N. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Luculescu, C. R. [Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Florini, N.; Komninou, Ph.; Kioseoglou, J. [Nanostructured Materials Microscopy Group (NMMG), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Othonos, A. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Research Center of Ultrafast Science, Department of Physics, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus)

2014-05-01

92

Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism  

NASA Astrophysics Data System (ADS)

Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

Zervos, M.; Mihailescu, C. N.; Giapintzakis, J.; Luculescu, C. R.; Florini, N.; Komninou, Ph.; Kioseoglou, J.; Othonos, A.

2014-05-01

93

On the existence of vapor-liquid phase transition in dusty plasmas  

SciTech Connect

The phenomenon of phase transition in a dusty-plasma system (DPS) has attracted some attention in the past. Earlier Farouki and Hamaguchi [J. Chem. Phys. 101, 9876 (1994)] have demonstrated the existence of a liquid to solid transition in DPS where the dust particles interact through a Yukawa potential. However, the question of the existence of a vapor-liquid (VL) transition in such a system remains unanswered and relatively unexplored so far. We have investigated this problem by performing extensive molecular dynamics simulations which show that the VL transition does not have a critical curve in the pressure versus volume diagram for a large range of the Yukawa screening parameter ? and the Coulomb coupling parameter ?. Thus, the VL phase transition is found to be super-critical, meaning that this transition is continuous in the dusty plasma model given by Farouki and Hamaguchi. We provide an approximate analytic explanation of this finding by means of a simple model calculation.

Kundu, M.; Sen, A.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India); Avinash, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2014-10-15

94

Vapor-liquid equilibria in fluids of two-center Lennard-Jones molecules  

SciTech Connect

Molecular dynamics simulations are performed using 500 molecules for pure fluids of two-center Lennard-Jones (12:6) molecules to obtain thermodynamic results, including the residual Helmholtz free energy, for several isotherms. Thermodynamic results obtained from these simulations are utilized to predict the vapor-liquid equilibria in these fluids. Simulation results have also been used to estimate the critical temperatures and critical densities of these fluids, and these are compared with the existing predictions from three theoretical methods. These comparisons show that the site-site Ornstein-Zernike equation, with the Percus-Yevick approximation, for these fluids overpredicts the critical temperatures, and a nonspherical reference potential based perturbation theory also shows small deviations whereas an approximate form of the zeroth-order Mayer function expansion cluster perturbation theory works well. These three methods predict well the critical densities of these fluids, within the combined uncertainties of the results.

Gupta, S.

1988-12-15

95

Effects of capillary heterogeneity on vapor-liquid counterflow in porous media  

NASA Astrophysics Data System (ADS)

Based on a continuum description, the effect of capillary heterogeneity, induced by variation in permeability, on the steady state, countercurrent, vapor-liquid flow in porous media is analyzed. It is shown that the heterogeneity acts as a body force that may enhance or diminish gravity effects on heat pipes. Selection rules that determine the steady states reached in homogeneous, gravity-driven heat pipes are also formulated. It is shown that the 'infinite' two-phase zone may terminate by a substantial change in the permeability somewhere in the medium. The two possible sequences, liquid-liquid dominated-dry, or liquid-vapor dominated-dry find applications in geothermal systems. Finally, it is shown that although weak heterogeneity affects only gravity controlled flows, stronger variations in permeability can give rise to significant capillary effects.

Stubos, A. K.; Satik, C.; Yortsos, Y. C.

1992-06-01

96

Stability and topological transformations of liquid droplets on vapor-liquid-solid nanowires  

NASA Astrophysics Data System (ADS)

The Vapor-Liquid-Solid method is one of the most popular techniques for growing semiconducting nanowires, and the stability of the liquid droplet is an important factor controlling wire morphology and, ultimately, functionality. Earlier theoretical work on axisymmetric systems indicates that the lowest-energy liquid configuration varies with surface energies, wire radius, and fluid volume. We test these predictions with a fully dynamic phase-field model that incorporates viscous fluid flow. Under conditions predicted by this earlier theoretical work, we observe the pinning of the liquid to the top face of a nanowire, a condition necessary for wire growth. To study the stability of the droplet, we apply perturbations to the liquid shape and find that the system can transition to a metastable configuration, a local minimum in the energy landscape. Furthermore, the transition pathway to this local minimum depends on the magnitude of the perturbations. Under conditions that favor a liquid on the sidewalls of the wire, we observe a spontaneous transition of the liquid from a droplet to an annular configuration through an intermediate state that is not predicted by theory. The time scales and contact-line speeds for these transitions are determined through simulation and are consistent with approximations based on simple dimensional analysis.

Schwalbach, Edwin J.; Davis, Stephen H.; Voorhees, Peter W.; Warren, James A.; Wheeler, Daniel

2012-01-01

97

Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures  

NASA Astrophysics Data System (ADS)

For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.

Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans

2009-02-01

98

Application of artificial intelligence control to the vapor-liquid-solid silicon carbide whisker process  

SciTech Connect

Silicon carbide whiskers have excellent mechanical and chemical properties, making them very desirable as a reinforcement for structural ceramic and other composite materials. Los Alamos has developed a laboratory-scale batch process for producing very high quality SiC whiskers by the vapor-liquid-solid (VLS) method which is an active candidate for technology transfer involving significant scale-up. The process, however, involves quite complex chemical/physical and parametric relationships and has not as yet lent itself successfully to modeling. An expert computer system was therefore developed to facilitate the transfer of this technology to industry. Optimum conditions were determined by relating the many process parameters to product results to establish a set of rules for running the process. These are incorporated in a two-phase expert system designed to guide inexperienced users. In Phase 1, an expert consultant program provides the user with information that enables him to set up the run. This information is incorporated into the rule base that makes up Phase 2 --- the control system. At present, the operator functions as the controller by responding to the decisions of the expert system; automation can be added later. 13 refs., 16 figs.

Shalek, P.D.; Parkinson, W.J.

1989-01-01

99

Controlled Growth of Organic Semiconductor Films Using Electrospray Vapor-Liquid-Solid Deposition  

NASA Astrophysics Data System (ADS)

Interest in low molecular weight organic semiconductors (OS) for applications such as light-emitting diodes, photovoltaics, and other technologies stems in part from their prospects for enabling significantly reduced manufacturing costs compared to traditional inorganic semiconductors. However many of the best performing prototype devices produced so far have involved expensive or time-consuming fabrication methods, such as the use of single crystals or thin films deposited under high vacuum conditions. New methods are needed capable of rapidly and inexpensively producing high quality polycrystalline films, preferably involving near-ambient conditions. This poster will present studies of one such approach based on an electrospray vapor-liquid-solid growth technique. The method produces polycrystalline OS films deposited via atmospheric-pressure sublimation from a carrier gas (argon) which is partially ionized by a corona discharge. Vapor-phase molecules are then attracted to a charged substrate coated with a thin liquid solvent layer, in which they dissolve and grow as crystals, producing films with large grain sizes. This poster will describe the electrostatic and hydrodynamic features of the deposition mechanism, and the growth kinetics of the resulting polycrystalline films.

Shaw, Daniel; Bufkin, Kevin; Johnson, Brad; Patrick, David

2010-03-01

100

Vapor-liquid equilibria for the systems difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride  

SciTech Connect

Isothermal vapor-liquid equilibria for difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. The binary system difluoromethane + hydrogen fluoride forms a homogeneous liquid phase, and the others form minimum boiling heterogeneous azeotropes at the experimental conditions.

Kang, Y.W. [KIST, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology] [KIST, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology

1998-01-01

101

Vapor-liquid coexistence curves in the critical region and the critical temperatures and densities of difluoromethane and pentafluoroethane  

Microsoft Academic Search

The vapor-liquid coexistence curves in the critical region of difluoromethane (HFC-32) and pentafluoroethane (HFC-125) were measured by a visual observation of the meniscus in an optical cell. Seventeen saturated-liquid and 13 saturated-vapor densities have been measured in a temperature range from 330 K to the critical temperature, corresponding to a density range from 218 to 790 kg\\/m[sup 3] for HFC-32.

Shigeo Kuwabara; Hirokazu Aoyama; Haruki Sato; Koichi Watanabe

2009-01-01

102

Whisker reinforced structural ceramics: Progress in the VLS growth and use of long silicon carbide whiskers. [Vapor-liquid-solid  

SciTech Connect

A VLS (vapor-liquid-solid) whisker growth process, optimized for the production of short (approx.10 mm lengths) SiC whiskers, was modified to produce greater than or equal to 25 mm long whiskers. In conjunction with this modification, a plan was developed for incorporating an artificial-intelligence system to enhance the whisker growth process. An oriented whisker ribbon was produced from the long whiskers, as a step toward the development of a staple whisker yarn.

Gac, F.D.; Shalek, P.D.; Parkinson, W.J.; Edwards, C.; Price, J.B.

1987-01-01

103

Correlation of Zeno (Z = 1) line for supercritical fluids with vapor-liquid rectilinear diameters  

SciTech Connect

For a wide range of substances, extending well beyond the regime of corresponding states behavior, the contour in the temperature-density plane along which the compressibility factor Z = P/{rho}kT is the same as for an ideal gas is nearly linear. This Z = 1 contour, termed the Zeno line, begins deep in the liquid region and ascends as the density decreases to the Boyle point of the supercritical fluid, specified by the temperature T{sub B} for which (dZ/d{rho}){sub T} = 0 as {rho} {r_arrow} 0; equivalent, at T{sub B} the second virial coefficient vanishes. The slope of the Z = 1 line is {minus}B{sub 3}/(dB{sub 2}/dT), in terms of the third virial coefficient and the derivative of the second, evaluated at T{sub B}. Previous work has examined the Zeno line as a means to extend corresponding states and to enhance other practical approximations. Here the authors call attention to another striking aspect, a strong correlation with the line of rectilinear diameters defined by the average of the subcritical vapor and liquid densities. This correlation is obeyed well by empirical data for many substances and computer simulations for a Lennard-jones potential; the ratios of the intercepts and slopes for the Zeno and rectilinear diameter liens are remarkably close to those predicted by the van der Waals equation, 8/9 and 16/9, respectively. Properties of the slightly imperfect fluid far above the critical point thus implicitly determine the diameter of the vapor-liquid coexistence curve below the critical point.

Ben-Amotz, D.; Herschbach, D.R. [Exxon Research and Engineering Co., Annandale, NJ (United States). Corporate Research Science Lab.

1996-08-01

104

Vapor-liquid equilibria for copolymer+solvent systems: Effect of intramolecular repulsion  

SciTech Connect

Role of intramolecular interactions in blend miscibility is well documented for polymer+copolymer mixtures. Some copolymer+polymer mixtures are miscible although their corresponding homopolymers are not miscible; for example, over a range of acrylonitrile content, styrene/acrylonitrile copolymers are miscible with poly(methyl methacrylate) but neither polystyrene nor polyacrylonitrile is miscible with poly(methyl methacrylate). Similarly, over a composition range, butadiene/acrylonitrile copolymers are miscible with poly(vinyl chloride) while none of the binary combinations of the homopolymers [polybutadiene, polyacrylonitrile, and poly(vinyl chloride)] are miscible. This behavior has been attributed to ``intramolecular repulsion`` between unlike copolymer segments. We have observed similar behavior in vapor-liquid equilibria (VLE) of copolymer+solvent systems. We find that acrylonitrile/butadiene copolymers have higher affinity for acetonitrile solvent than do polyacrylonitrile or polybutadiene. We attribute this non-intuitive behavior to ``intramolecular repulsion`` between unlike segments of the copolymer. This repulsive interaction is weakened when acetonitrile molecules are in the vicinity of unlike copolymer segments, favoring copolymer+solvent miscibility. We find similar behavior when acetonitrile is replaced by methyl ethyl ketone. To best knowledge, this effect has not been reported previously for VLE. We have obtained VLE data for mixtures containing a solvent and a copolymer as a function of copolymer composition. It appears that, at a given solvent partial pressure, there may be copolymer composition that yields maximum absorption of the solvent. This highly non-ideal VLE phase behavior may be useful for optimum design of a membrane for a separation process.

Gupta, R.B.; Prausnitz, J.M.

1995-03-01

105

System NaCl-H/sub 2/O: relations of vapor-liquid near the critical temperature of water and of vapor-liquid-halite from 300/sup 0/ to 500/sup 0/C  

SciTech Connect

Vapor-liquid relations (P-T-x) for the system NaCl-H/sub 2/O were determined experimentally at temperatures spanning the critical temperature of water (T/sub c/), the lowest temperature in the system at which critical behavior occurs. In addition, vapor-liquid-halite P-T-x (vapor) relations were determined from 300/sup 0/ to 500/sup 0/C. Results show that at 373.0/sup 0/C, immediately below T/sub c/, the vapor side of the isothermal vapor-liquid P-x boundary has a shape quite different from that previously conceived. The NaCl content of the vapor increases with pressure in a smooth manner from the pressure of the three-phase assemblage (135 bars, 0.0029% NaCl), to a pressure just below that of the vapor pressure of pure water (0.012% NaCl at 184 bars). Above this pressure the boundary abruptly reverses and projects asymptotically to 0% NaCl in a beak-like shape at 218 bars, the vapor pressure of pure water. At 375.5/sup 0/, slightly above T/sub c/, the asymptote disappears, and is replaced by a rounded nose. At progressively higher temperatures, the nose disappears and by 380/sup 0/C the familiar symmetrical bell-shaped curve predominates with the critical point defined by the top of the bell. The P-T curve of the three-phase assemblage determined in the present study is in agreement with previous workers. The NaCl content of the three-phase vapor, however, is much higher than some literature values at temperatures above 410/sup 0/C.

Bischoff, J.L.; Rosenbauer, R.J.

1986-07-01

106

Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system  

USGS Publications Warehouse

Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

Qin, J.; Rosenbauer, R.J.; Duan, Z.

2008-01-01

107

Engineering scale development of the Vapor-Liquid-Solid (VLS) process for the production of silicon carbide fibrils  

SciTech Connect

Vapor-liquid-solid (VLS)SiC fibrils are used as reinforcement in ceramic matrix composites (CMC). A program has been completed for determining process scaleup parameters and to produce material for evaluation in a CMC. The scaleup is necessary to lower production cost and increase material availability. Scaleup parameters were evaluated in a reactor with a vertical dimension twice that of the LANL reactor. Results indicate that the scaleup will be possible. Feasibility of recycling process gas was demonstrated and the impact of postprocessing on yields determined.

Hollar, W.E. Jr. [Carborundum Co., Niagara Falls, NY (United States). Technology Div.; Mills, W.H. [BP America, Inc., Cleveland, OH (United States)

1993-09-01

108

First principles Monte Carlo simulations of vapor--liquid equilibria: Density functionals, basis sets, and dispersion corrections  

NASA Astrophysics Data System (ADS)

Gibbs ensemble Monte Carlo simulations are used to compute the vapor--liquid equilibria for water, methanol, and methane using Kohn-Sham density functional theory. Results for BLYP and PBE functionals, BLYP with Grimme D2 and D3 dispersion corrections, and various basis sets are compared. Although none of the combinations of functional, dispersive correction, and basis set is found to yield highly accurate predictions for liquid densities, vapor pressures, and heats of vaporization for all three compounds, the results for dispersion corrected BLYP with large basis set are promising.

Siepmann, J. Ilja; McGrath, Matthew J.; Kuo, I.-F. William; Mundy, Christopher J.

2012-02-01

109

The vapor-liquid interface potential of (multi)polar fluids and its influence on ion solvation.  

PubMed

The interface between the vapor and liquid phase of quadrupolar-dipolar fluids is the seat of an electric interfacial potential whose influence on ion solvation and distribution is not yet fully understood. To obtain further microscopic insight into water specificity we first present extensive classical molecular dynamics simulations of a series of model liquids with variable molecular quadrupole moments that interpolates between SPC/E water and a purely dipolar liquid. We then pinpoint the essential role played by the competing multipolar contributions to the vapor-liquid and the solute-liquid interface potentials in determining an important ion-specific direct electrostatic contribution to the ionic solvation free energy for SPC/E water-dominated by the quadrupolar and dipolar parts-beyond the dominant polarization one. Our results show that the influence of the vapor-liquid interfacial potential on ion solvation is strongly reduced due to the strong partial cancellation brought about by the competing solute-liquid interface potential. PMID:23614431

Horváth, Lorand; Beu, Titus; Manghi, Manoel; Palmeri, John

2013-04-21

110

The vapor-liquid interface potential of (multi)polar fluids and its influence on ion solvation  

NASA Astrophysics Data System (ADS)

The interface between the vapor and liquid phase of quadrupolar-dipolar fluids is the seat of an electric interfacial potential whose influence on ion solvation and distribution is not yet fully understood. To obtain further microscopic insight into water specificity we first present extensive classical molecular dynamics simulations of a series of model liquids with variable molecular quadrupole moments that interpolates between SPC/E water and a purely dipolar liquid. We then pinpoint the essential role played by the competing multipolar contributions to the vapor-liquid and the solute-liquid interface potentials in determining an important ion-specific direct electrostatic contribution to the ionic solvation free energy for SPC/E water—dominated by the quadrupolar and dipolar parts—beyond the dominant polarization one. Our results show that the influence of the vapor-liquid interfacial potential on ion solvation is strongly reduced due to the strong partial cancellation brought about by the competing solute-liquid interface potential.

Horváth, Lorand; Beu, Titus; Manghi, Manoel; Palmeri, John

2013-04-01

111

Vapor-liquid equilibria for solvent-polymer systems from a perturbed hard-sphere-chain equation of state  

SciTech Connect

Vapor-liquid equilibria (VLE) for solvent-polymer mixtures at modest pressures are obtained from a perturbed hard-sphere-chain equation of state. This equation of state is the sum of a hard-sphere-chain term as the reference system and a van der Waals attractive term as the perturbation. The reference equation follows from the Percus-Yevick integral theory coupled with chain connectivity as described by Chiew. The effect of specific interactions, such as hydrogen bonding, is introduced through the proposal of Veytsman based on the statistical distribution of hydrogen bonds between donor and acceptor sites suggested by molecular structure. Calculated and observed vapor-liquid equilibria are presented for nonpolar, polar, and hydrogen-bonding solvent + homopolymer systems. Pure-component parameters (number of segments per molecule, segment-segment energy, and segment diameter) are obtained from pure-component properties: liquid density and vapor pressure data for normal fluids and pressure-volume-temperature data for polymers. A binary energy interaction parameter must be obtained from limited VLE data for each binary system; this parameter appears to be independent of temperature and composition over a useful range. Theoretical correlations and predictions are in good agreement with experiment.

Gupta, R.B.; Prausnitz, J.M. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering] [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering; [Lawrence Berkeley Lab., CA (United States). Chemical Sciences Div.

1996-04-01

112

Structure and dynamics of single hydrophobic/ionic heteropolymers at the vapor-liquid interface of water.  

PubMed

We focus on the conformational stability, structure, and dynamics of hydrophobic/charged homopolymers and heteropolymers at the vapor-liquid interface of water using extensive molecular dynamics simulations. Hydrophobic polymers collapse into globular structures in bulk water but unfold and sample a broad range of conformations at the vapor-liquid interface of water. We show that adding a pair of charges to a hydrophobic polymer at the interface can dramatically change its conformations, stabilizing hairpinlike structures, with molecular details depending on the location of the charged pair in the sequence. The translational dynamics of homopolymers and heteropolymers are also different, whereas the homopolymers skate on the interface with low drag, the tendency of charged groups to remain hydrated pulls the heteropolymers toward the liquid side of the interface, thus pinning them, increasing drag, and slowing the translational dynamics. The conformational dynamics of heteropolymers are also slower than that of the homopolymer and depend on the location of the charged groups in the sequence. Conformational dynamics are most restricted for the end-charged heteropolymer and speed up as the charge pair is moved toward the center of the sequence. We rationalize these trends using the fundamental understanding of the effects of the interface on primitive pair-level interactions between two hydrophobic groups and between oppositely charged ions in its vicinity. PMID:24689358

Vembanur, Srivathsan; Venkateshwaran, Vasudevan; Garde, Shekhar

2014-04-29

113

The system NaCl-H2O: Relations of vapor-liquid near the critical temperature of water and of vapor-liquid-halite from 300?? to 500??C  

USGS Publications Warehouse

Vapor-liquid relations (P-T-x) for the system NaCl-H2O were determined experimentally at temperatures spanning the critical temperature of water (Tc), the lowest temperature in the system at which critical behavior occurs. In addition, vapor-liquid-halite P-T-x(vapor) relations were determined from 300?? to 500??C. Results show that at 373.0??C, immediately below Tc, the vapor side of the isothermal vaporliquid P-x boundary has a shape quite different from that previously conceived. The NaCl content of the vapor increases with pressure in a smooth manner from the pressure of the three-phase assemblage (135 bars, 0.0029% NaCl), to a pressure just below that of the vapor pressure of pure water (0.012% NaCl at 184 bars). Above this pressure the boundary abruptly reverses and projects asymptotically to 0% NaCl in a beak-like shape at 218 bars, the vapor pressure of pure water. At 375.5??, slightly above Tc, the asymptote disappears, and is replaced by a rounded nose. At progressively higher temperatures, the nose disappears and by 380??C the familiar symmetrical bell-shaped curve predominates with the critical point defined by the top of the bell. The P-T curve of the three-phase assemblage determined in the present study is in agreement with previous workers. The NaCl content of the three-phase vapor, however, is much higher than some literature values at temperatures above 410??C. ?? 1986.

Bischoff, J.L.; Rosenbauer, R.J.; Pitzer, K.S.

1986-01-01

114

Sea-Level Pressure: Contouring Isobars  

NSDL National Science Digital Library

This interactive feature shows how an isobar (atmospheric pressure) map is drawn. Students can select an individual contour value and watch as the animation correctly places the line with respect to pressure values on the map. The animation also marks high and low pressure systems, toggles between coded (station model) and decoded pressure values, and permits the user to color the spaces between the contour lines on the map.

115

Isobar giant resonance formation in self-conjugate nuclei  

Microsoft Academic Search

The production of isobars with concomitant giant resonance excitations due to peripheral collisions of relativistic heavy ions is investigated. The interaction is described by a modified form of the central term in the one-pion-exchange potential (OPEP) where the projectile ordinary spin operator is replaced by a transition spin operator which describes the creation of an isobar from a nucleon. The

L. W. Townsend; P. A. Deutchman

1981-01-01

116

Epitaxy-enabled vapor-liquid-solid growth of tin-doped indium oxide nanowires with controlled orientations.  

PubMed

Controlling the morphology of nanowires in bottom-up synthesis and assembling them on planar substrates is of tremendous importance for device applications in electronics, photonics, sensing and energy conversion. To date, however, there remain challenges in reliably achieving these goals of orientation-controlled nanowire synthesis and assembly. Here we report that growth of planar, vertical and randomly oriented tin-doped indium oxide (ITO) nanowires can be realized on yttria-stabilized zirconia (YSZ) substrates via the epitaxy-assisted vapor-liquid-solid (VLS) mechanism, by simply regulating the growth conditions, in particular the growth temperature. This robust control on nanowire orientation is facilitated by the small lattice mismatch of 1.6% between ITO and YSZ. Further control of the orientation, symmetry and shape of the nanowires can be achieved by using YSZ substrates with (110) and (111), in addition to (100) surfaces. Based on these insights, we succeed in growing regular arrays of planar ITO nanowires from patterned catalyst nanoparticles. Overall, our discovery of unprecedented orientation control in ITO nanowires advances the general VLS synthesis, providing a robust epitaxy-based approach toward rational synthesis of nanowires. PMID:24971997

Shen, Youde; Turner, Stuart; Yang, Ping; Van Tendeloo, Gustaaf; Lebedev, Oleg I; Wu, Tom

2014-08-13

117

Ab initio potential energy surface for methane and carbon dioxide and application to vapor-liquid coexistence.  

PubMed

A six-dimensional intermolecular potential energy surface for a rigid methane (CH4) and carbon dioxide (CO2) dimer was developed from the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory. A total of 466 grid points distributed to 46 orientations were calculated from the complete basis set limit extrapolation based on up to aug-cc-pVQZ basis set. A modified site-site pair potential function was proposed for rapid representation of the high level ab initio calculations. A nonadditive three-body interaction was represented by the Axilrod-Teller-Muto expression for mixtures with the polarizability and the London dispersion constant of each molecule. Second to fourth virial coefficients of CH4 and CO2 mixtures were calculated using both the Mayer sampling Monte Carlo method and the present potential functions. The virial equation of state derived from these coefficients was used to predict the pVT values and showed good agreement with experimental data below 200 bar at 300 K. The vapor-liquid coexistence curves of pure CH4, CO2 and their mixtures were presented with the aid of Gibbs ensemble Monte Carlo simulations. The predicted tie lines agreed with the experimental data within the uncertainties up to near the critical point. PMID:25134567

Pai, Sung Jin; Bae, Young Chan

2014-08-14

118

Essential role of catalysts (Mn, Au, and Sn) in the vapor liquid solid growth kinematics of ZnS nanowires  

SciTech Connect

In this paper, we demonstrate that surface energy of the catalyst is a vital parameter for the growth rate, self doping of the self assembled nanowires synthesized by employing vapor liquid solid growth technique. The synthesis of ZnS nanowires was done by selectively using three different catalysts (Mn, Au, and Sn), where Au, is the most common catalyst, was used as a reference. The distinctive difference in the growth rate was due to the surface energy of the metal alloy droplet and the interface energies, as explained theoretically using thermodynamic approach. We have found that the activation energy of diffusion of (Zn, S) species in the catalyst droplet was low in Sn (0.41?eV for Zn and 0.13?eV for S) and high in Mn (1.79?eV for Zn and 0.61?eV for S) compared to Au (0.62?eV for Zn and 0.21?eV for S) catalyzed ZnS nanostructures. The thermodynamic calculations predicted the growth rates of Sn (7.5?nm/s) catalyzed nanowires was faster than Au (5.1?nm/s) and Mn (4.6?nm/s) catalyzed ZnS nanostructures, which were in agreement with the experimental results. Finally, the location of the catalyst as dopant in the grown nanostructure was predicted and compared with experimental observations.

Rehman, S.; Shehzad, M. A.; Hafeez, M.; Bhatti, A. S., E-mail: asbhatti@comsats.edu.pk [Center for Micro and Nano Devices (CMND), Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

2014-01-14

119

Diffusion suppression in vapor-liquid-solid Si nanowire growth by a barrier layer between the Au catalyst and substrate  

NASA Astrophysics Data System (ADS)

Nanowires have attracted significant interest because of their unique characteristics. Vapor-liquid-solid (VLS) growth is the standard method for fabricating nanowires and Au is the most commonly used catalyst. However, Au catalyst droplets diffuse over the Si substrate surface with a high migration velocity and agglomerate at relatively low temperatures. In our previous work, we reported a significant improvement in the positioning and diameter distribution of VLS-grown Si nanowires by inserting a diffusion barrier layer and concluded that the barrier layer suppressed the formation of AuSi eutectic droplets and prevented the droplets diffusing on the substrate surface during nucleation. In the present study, we analyzed the nucleation of the Au catalyst and examined its behavior during nucleation. Detailed multidirectional analysis and in situ observations confirmed that the formation and agglomeration of AuSi eutectic droplets was suppressed by the formation of a silicide layer. This because of the higher reaction temperatures between the diffusion barrier and the substrate silicon, and between the catalyst and the diffusion barrier, compared with the reaction between the Au catalyst and substrate silicon.

Koto, Makoto; Watanabe, Masatoshi; Sugawa, Etsuko; Shimizu, Tomohiro; Shingubara, Shoso

2014-10-01

120

Vapor-liquid equilibria of copolymer + solvent and homopolymer + solvent binaries: New experimental data and their correlation  

SciTech Connect

Sixty-four isothermal data sets for vapor-liquid equilibria (VLE) for polymer + solvent binaries have been obtained using a gravimetric sorption technique, in the range of 23.5--80 C. Solvents studied were acetone, acetonitrile, 1-butanol, 1,2-dichloroethane, chloroform, cyclohexane, hexane, methanol, octane, pentane, and toluene. Copolymers studied were poly(acrylonitrile-co-butadiene), poly(styrene-co-acrylonitrile), poly(styrene-co-butadiene), poly(styrene-co-butyl methacrylate), poly(vinyl acetate-co-ethylene), and poly(vinyl acetate-co-vinyl chloride). All copolymers were random copolymers. Some homopolymers were also studied: polyacrylonitrile, polybutadiene, poly(butyl methacrylate), poly(ethylene oxide), polystyrene, and poly(vinyl acetate). The composition of the copolymer may have a surprising effect on VLE. Normally, deviation from ideal behavior lies between those of the constituent homopolymers, according to the copolymer composition, as observed for cyclohexane + poly(ethylene-co-vinyl acetate) and chloroform + poly(styrene-co-butyl methacrylate). However, the strong nonideal behavior observed for systems containing hydrocarbons and poly(butadiene-co-acrylonitrile) shows that the effect of acrylonitrile is in excess of that expected form the copolymer composition. The perturbed hard-sphere chain (PHSC) equation of state was used to represent VLE of the copolymer solutions studied here.

Gupta, R.B.; Prausnitz, J.M. [Lawrence Berkeley Lab., CA (United States)

1995-07-01

121

Grand canonical Monte Carlo simulations of vapor-liquid equilibria using a bias potential from an analytic equation of state  

NASA Astrophysics Data System (ADS)

This article introduces an efficient technique for the calculation of vapor-liquid equilibria of fluids. Umbrella Sampling Monte Carlo simulations in the grand canonical ensemble were conducted for various types of molecules. In Umbrella Sampling, a weight function is used for allowing the simulation to reach unlikely states in the phase space. In the present case this weight function, that allows the system to overcome the energetic barrier between a vapor and liquid phase, was determined by a trivialized Density Functional Theory (DFT) using the PC-SAFT equation of state. The implementation presented here makes use of a multicanonical ensemble approach to divide the space of fluctuating particle number N into various subsystems. The a priori estimate of the weight function from the analytic DFT allows the parallelization of the calculation, which significantly reduces the computation time. In addition, it is shown that the analytic equation of state can be used to substitute sampling the dense liquid phase, where the sampling of insertion and deletion moves become demanding.

Sanchez, Juan Manuel Castillo; Danner, Timo; Gross, Joachim

2013-06-01

122

Ab initio potential energy surface for methane and carbon dioxide and application to vapor-liquid coexistence  

NASA Astrophysics Data System (ADS)

A six-dimensional intermolecular potential energy surface for a rigid methane (CH4) and carbon dioxide (CO2) dimer was developed from the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory. A total of 466 grid points distributed to 46 orientations were calculated from the complete basis set limit extrapolation based on up to aug-cc-pVQZ basis set. A modified site-site pair potential function was proposed for rapid representation of the high level ab initio calculations. A nonadditive three-body interaction was represented by the Axilrod-Teller-Muto expression for mixtures with the polarizability and the London dispersion constant of each molecule. Second to fourth virial coefficients of CH4 and CO2 mixtures were calculated using both the Mayer sampling Monte Carlo method and the present potential functions. The virial equation of state derived from these coefficients was used to predict the pVT values and showed good agreement with experimental data below 200 bar at 300 K. The vapor-liquid coexistence curves of pure CH4, CO2 and their mixtures were presented with the aid of Gibbs ensemble Monte Carlo simulations. The predicted tie lines agreed with the experimental data within the uncertainties up to near the critical point.

Pai, Sung Jin; Bae, Young Chan

2014-08-01

123

Vapor-liquid equilibria for difluoromethane (R32) + and pentafluoroethane (R125) + 1,1,1,3,3,3-hexafluoropropane (R236fa) at 303.2 and 323.3 K  

SciTech Connect

Isothermal vapor-liquid equilibria (VLE) for the binary systems difluoromethane (R32) + 1,1,1,3,3,3-hexafluoropropane (R236fa) and pentafluoroethane (R125) + 1,1,1,3,3,3-hexafluoropropane (R236f) were measured at 303.2 and 323.3 K using a recirculation apparatus in which the vapor phase was forced through the liquid. The phase composition at equilibrium was measured by gas chromatography, calibrating its response using gravimetrically prepared mixtures. Both systems show a slight deviation from Raoult`s law. The data were reduced by the Carnahan-Starling-De Santis EOS. The deviations observed in vapor composition, averaging below 0.003 in mole fraction, confirm the consistency of the experimental findings and the model used for their reduction. Calculated excess Gibbs energy functions reveal values to be within {+-}40 J/mol at T = 303 K. The margins of error in pressure, temperature, and composition of vapor and liquid-phase measurements were estimated to be less than {+-}0.15%, {+-}0.005 K, and {+-}0.0015 of mole fraction, respectively.

Bobbo, S.; Camporese, R. [National Research Council, Padova (Italy). Inst. of Refrigeration] [National Research Council, Padova (Italy). Inst. of Refrigeration; Stryjek, R. [Polish Academy of Sciences, Warsaw (Poland). Inst. of Physical Chemistry] [Polish Academy of Sciences, Warsaw (Poland). Inst. of Physical Chemistry

1999-03-01

124

Phase equilibrium constraints on the viscosity of silicic magmas with implications for mafic-silicic  

E-print Network

. Isobaric crystallization paths obtained from phase equilibrium experiments show that, whereas in rhyolitic-solid behavior. Thus they cannot be used as fossil indicators of direction of magmatic flow. key words: granite/rhyolite

125

Isothermal vapor-liquid equilibria for the systems 1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride  

SciTech Connect

Isothermal vapor-liquid equilibria for the three binary systems (1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride) have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. All of the systems form minimum boiling heterogeneous azeotropes.

Kang, Y.W.; Lee, Y.Y. [KIST, Seoul (Korea, Republic of)] [KIST, Seoul (Korea, Republic of)

1997-03-01

126

Synthesis of epitaxial Si(100) nanowires on Si(100) substrate using vapor liquid solid growth in anodic aluminum oxide nanopore arrays  

NASA Astrophysics Data System (ADS)

The synthesis of epitaxial Si nanowires with growth direction parallel to Si [100] on Si(100) substrate was demonstrated using a combination of anodic aluminum oxide (AAO) template, catalytic gold film sandwiched between the template and the Si(100) substrate and vapor-liquid-solid growth using SiH4 as the Si source. After growing out from the AAO nanopores, most Si nanowires changed their diameter and growth direction into larger diameter and <111> direction.

Shimizu, T.; Senz, S.; Shingubara, S.; Gösele, U.

2007-06-01

127

A systematic study of the nitridation of SnO 2 nanowires grown by the vapor liquid solid mechanism  

NASA Astrophysics Data System (ADS)

SnO 2 nanowires (NWs) with diameters of 50 nm and lengths ?10 ?m have been grown at 800 °C on 1.0 nm Au/Si(001) via the vapor liquid solid mechanism and the low pressure chemical vapor deposition. These exhibited clear peaks in the X-ray diffraction corresponding to the tetragonal rutile crystal structure of SnO 2 and a broad-symmetric photoluminescence (PL) spectrum, centered around 560 nm due to structural-related defect states, energetically located in the upper half-band-gap of SnO 2. We find that post-growth thermal annealing of the SnO 2 NWs over a broad range of temperatures, i.e. 400-1000 °C and high flow of O 2 does not change their crystal structure or optical properties. In contrast the nitridation of SnO 2 NWs using NH 3 leads to their elimination above 500 °C. Lower temperatures did not favor the nitridation even using extended nitridation times, hydrogen, lower ramp rates or a two-step-temperature process which are effective in the case of In 2O 3 and Ga 2O 3. However the nitridation of SnO 2 NWs was promoted by HCl, supplied in-situ via the sublimation of NH 4Cl, which reacts with Sn and SnO 2 leading to the formation of the intermediate SnCl 4, which reacts in turn with NH 3 giving tin nitride at temperatures between 400 and 500 °C . We discuss the effect of the nitridation and thermal annealing on the PL spectra.

Zervos, Matthew; Othonos, Andreas

2012-02-01

128

Adapting SAFT-? perturbation theory to site-based molecular dynamics simulation. II. Confined fluids and vapor-liquid interfaces  

SciTech Connect

In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-? WCA EOS and selective applications are studied for confined fluids and vapor-liquid interfaces. The acronym WCA (Weeks-Chandler-Andersen) refers to the characterization of the reference part of the third-order thermodynamic perturbation theory applied in formulating the EOS. SAFT-? refers to the particular form of “statistical associating fluid theory” that is applied to the fused-sphere, heteronuclear, united-atom molecular models of interest. For the monomer term, the modified fundamental measure theory is extended to WCA-spheres. A new chain functional is also introduced for fused and soft heteronuclear chains. The attractive interactions are taken into account by considering the structure of the fluid, thus elevating the theory beyond the mean field approximation. The fluctuations of energy are also included via a non-local third-order perturbation theory. The theory includes resolution of the density profiles of individual groups such as CH{sub 2} and CH{sub 3} and satisfies stoichiometric constraints for the density profiles. New molecular simulations are conducted to demonstrate the accuracy of each Helmholtz free energy contribution in reproducing the microstructure of inhomogeneous systems at the united-atom level of coarse graining. At each stage, comparisons are made to assess where the present theory stands relative to the current state of the art for studying inhomogeneous fluids. Overall, it is shown that the characteristic features of real molecular fluids are captured both qualitatively and quantitatively. For example, the average pore density deviates ?2% from simulation data for attractive pentadecane in a 2-nm slit pore. Another example is the surface tension of ethane/heptane mixture, which deviates ?1% from simulation data while the theory reproduces the excess accumulation of ethane at the interface.

Ghobadi, Ahmadreza F.; Elliott, J. Richard, E-mail: elliot1@uakron.edu [Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325 (United States)

2014-07-14

129

Isobaric labeling-based relative quantification in shotgun proteomics.  

PubMed

Mass spectrometry plays a key role in relative quantitative comparisons of proteins in order to understand their functional role in biological systems upon perturbation. In this review, we review studies that examine different aspects of isobaric labeling-based relative quantification for shotgun proteomic analysis. In particular, we focus on different types of isobaric reagents and their reaction chemistry (e.g., amine-, carbonyl-, and sulfhydryl-reactive). Various factors, such as ratio compression, reporter ion dynamic range, and others, cause an underestimation of changes in relative abundance of proteins across samples, undermining the ability of the isobaric labeling approach to be truly quantitative. These factors that affect quantification and the suggested combinations of experimental design and optimal data acquisition methods to increase the precision and accuracy of the measurements will be discussed. Finally, the extended application of isobaric labeling-based approach in hyperplexing strategy, targeted quantification, and phosphopeptide analysis are also examined. PMID:25337643

Rauniyar, Navin; Yates, John R

2014-12-01

130

Isothermal vapor-liquid equilibrium of butanone + butan-1-ol at eight temperatures between 278.15 and 323.15 K  

SciTech Connect

Vapor pressures of butanone + butan-1-ol, at eight temperatures between 278.15 and 323.15 K, were measured by a static method. Activity coefficients and excess molar Gibbs free energies G{sup E} were calculated by Barker`s method. Reduction of the vapor pressure data is carried out by means of the Redlich-Kister and Wilson correlations.

Garriga, R.; Sanchez, F.; Perez, P.; Gracia, M. [Univ. de Zaragoza (Spain)] [Univ. de Zaragoza (Spain)

1996-05-01

131

Representing Vapor-Liquid Equilibrium for an Aqueous MEA-CO2 System Using the Electrolyte Nonrandom-Two-Liquid Model  

E-print Network

) It is the strongest base with the quickest reaction rate, yielding the highest purity, which make it most suitable: (a) It has a high reaction heat with CO2 that leads to higher stripping energy consumption. (b reaction as well as important interaction parameters of the electrolyte NRTL model were carefully fitted

Zhang, Luzheng

132

Vapor-liquid critical surface of ternary difluoromethane + pentafluoroethane + 1,1,1,2-tetrafluoroethane (R-32/125/134a) mixtures  

SciTech Connect

The plane of vapor-liquid criticality for ternary refrigerant mixtures of difluoromethane (R-32) + pentafluoroethane (R-125) + 1,1,1,2-tetrafluoroethane (R-134a) was determined from data on the vapor-liquid coexistence curve near the mixture critical points. The composition (mass percentage) of the mixtures studied were 23% R-32 + 25% R-125 + 52% R-134a (R-407C). 25% R-32 + 15% R-125 + 60% R-134a (R-407E), and 20% R-32 + 40% R-125 + 40% R-134a (R-407A). The critical temperature of each mixture was determined by observation of the disappearance of the meniscus. The critical density of each mixture was determined on the basis of meniscus disappearance level and the intensity of the critical opalescence. The uncertainties of the temperature, density, and composition measurements are estimated as {+-}10mK, {+-}5kg{center_dot}m{sup {minus}3}, and {+-}0.05%, respectively. In addition, predictive methods for the critical parameters of R-32/125/134a mixtures are discussed.

Higashi, Y.

1999-09-01

133

Vapor-liquid phase equilibria of potassium chloride-water mixtures: Equation-of-state representation for KCl-H2O and NaCl-H2O  

USGS Publications Warehouse

Measurements of isothermal vapor-liquid compositions for KCl-H2O as a function of pressure are reported. An equation of state, which was originally proposed by Pitzer and was improved and used by Tanger and Pitzer to fit the vapor-liquid coexistence surface for NaCl-H2O, has been used for representation of the KCl-H2O system from 300 to 410??C. Improved parameters are also reported for NaCl-H2O from 300 to 500??C. ?? 1990 American Chemical Society.

Hovey, J.K.; Pitzer, K.S.; Tanger, J.C., IV; Bischoff, J.L.; Rosenbauer, R.J.

1990-01-01

134

Vapor-liquid phase equilibria of potassium chloride-water mixtures: Equation-of-state representation for KCl-H sub 2 O and NaCl-H sub 2 O  

SciTech Connect

Measurements of isothermal vapor-liquid compositions for KCl-H{sub 2}O as a function of pressure are reported. An equation of state, which was originally proposed by Pitzer and was improved and used by Tanger and Pitzer to fit the vapor-liquid coexistence surface for NaCl-H{sub 2}O, has been used for representation of the KCl-H{sub 2}O system from 300 to 410{degree}C. Improve parameters are also reported for NaCl-H{sub 2}O from 300 to 500{degree}C.

Hovey, J.K.; Pitzer, K.S.; Tanger, J.C. IV (Lawrence Berkeley Lab., CA (USA)); Bischoff, J.L.; Rosenbauer, R.J. (Geological Survey, Menlo Park, CA (USA))

1990-02-08

135

Phase equilibrium measurements on twelve binary mixtures  

SciTech Connect

Phase equilibrium measurements have been performed on twelve binary mixtures. The PTx method was used to obtain vapor-liquid equilibrium data for the following binary systems at two temperatures each: ethanethiol + propylene; nitrobenzene + methanol; pyridine + ethyl acetate; octane + tert-amyl methyl ether; diisopropyl ether + butane; 1,3-dichloro-2-propanol + epichlorohydrin; 2,3-dichloro-1-propanol + epichlorohydrin; 2,3-epoxy-1-propanol + epichlorohydrin; 3-chloro-1,2-propanediol + epichlorohydrin; methanol + hydrogen cyanide. For these systems, equilibrium vapor and liquid phase compositions were derived from the PTx data using the Soave equation of state to represent the vapor phase and the Wilson, NRTL, or Redlich-Kister activity coefficient model to represent the liquid phase. The infinite dilution activity coefficient of methylamine in N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone-rich half of the binary. Liquid-liquid equilibrium studies were made on the triethylene glycol + 1-pentene system at two temperatures by directly analyzing samples taken from each liquid phase.

Giles, N.F. [Wiltec Research Co., Inc., Provo, UT (United States)] [Wiltec Research Co., Inc., Provo, UT (United States); Wilson, H.L.; Wilding, W.V. [Brigham Young Univ., Provo, UT (United States). Chemical Engineering Dept.] [Brigham Young Univ., Provo, UT (United States). Chemical Engineering Dept.

1996-11-01

136

A study of contacts to p- and n-type silicon nanowires synthesized via vapor-liquid-solid growth process  

NASA Astrophysics Data System (ADS)

Silicon nanowires have been the subject of intense research in recent years for their potential application in future nanoscale electronic systems and for studying physical phenomena in restricted geometries. In order for nanoscale electronic devices to realize their full potential in certain applications, ohmic contacts are required. The present study focuses on the fabrication and characterization of electrical contacts to p- and n-type Si nanowires grown by the vapor-liquid-solid method with the objective of designing ohmic contacts with a low contact resistance. The actual contacts to these nanowires could exist in two possible geometries: firstly, as an integral part of the nanowires fabricated during growth of the nanowires, also referred to as nanowire heterojunction contacts, and secondly, in the form of lithographically defined metal pads overlapping the nanowires. Cobalt silicide/Si and Au/Si heterojunction nanowires grown in anodized alumina templates with an average pore diameter of 200 nm were studied in the former geometry. An optimum amount of Au catalyst was deemed necessary for obtaining cobalt silicide/Si nanowires with good morphology. Investigations using transmission electron microscopy helped determine this amount to be approximately two-thirds of the average pore diameter of the templates in which the nanowires were grown. Subsequently, detailed scanning transmission electron microscopy revealed that even some of the nanowires with good morphology contained Au nanoparticles, more so near the interface of the Si segment with the silicide in the case of cobalt silicide/Si nanowires and with the Au in the case of Au/Si nanowires. Such Au nanoparticles were shown to cause discontinuities in some nanowires upon annealing at temperatures above the Au-Si eutectic point. Nanowires grown out the top of the membranes contained very few Au nanoparticles away from the Au/Si interface and were used for studying contacts in the metal-pad geometry. Contacts in a two-point probe configuration based on Pd, Ti/Au and Co/Al metallizations were studied for heavily doped p-type Si nanowires of average diameter 80 nm that were grown out the top of membranes, and a Ti/Au metallization was studied for heavily doped n-type Si nanowires of similar diameter. Such studies revealed that for p-type nanowires, the Co/Al contacts were the least resistive under similar fabrication and annealing conditions. Annealing from 200--300°C in a N2 ambient was shown to be optimal for obtaining ohmic contacts and avoiding thermal degradation. For n-type nanowires, the Ti/Au contacts were also shown to form ohmic contacts readily upon annealing between 250--300°C under similar conditions. Field emission scanning electron microscopy was used to study some of the defective p- and n-type Si nanowire devices including contact electrodes. A multi-contact test structure was next fabricated, which made it possible to extract various contact parameters based on a nanowire transmission line model. Contacts based on Al, Co and Co/Al metallizations were fabricated on heavily doped p-type nanowires of average diameter 80 nm that were grown out the top of membranes and from Au thin films, and an Er/Al metallization was used for heavily doped n-type nanowires of similar diameter grown by similar methods. The specific contact resistance of as-deposited Al contacts was found to be within 1 x 10-5 -- 4 x 10-4 O-cm2 when extracted at the origin of the device current-voltage (I-V) characteristics for p-type Si nanowires of resistivity 0.53 (+/-0.48) O-cm. Cobalt contacts, upon annealing in N2 within 250--300°C in the multicontact fabrication, showed lower resistance and more linear current-voltage characteristics than the Al contacts but were more difficult to lift off at the required metallization thickness. A contact based on the Co/Al metallization was later fabricated that combined the ease of lift-off of the Al multicontacts with the low resistance of the annealed Co contacts. The specific contact resistance of ohmic contacts based on such a metallizat

Dey, Soham

137

Very low specific contact resistance measurements made on a highly p-type doped 4H-SiC layer selectively grown by vapor-liquid-solid transport  

NASA Astrophysics Data System (ADS)

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10-6 ??cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10-4 ??cm2). Possible sources of this fluctuation have been also discussed in this paper.

Thierry-Jebali, N.; Vo-Ha, A.; Carole, D.; Lazar, M.; Ferro, G.; Planson, D.; Henry, A.; Brosselard, P.

2013-05-01

138

Remote sensing of atmospheric water vapor, liquid water, and wind speed at the ocean surface by passive microwave techniques from the Nimbus 5 satellite  

NASA Technical Reports Server (NTRS)

The microwave brightness temperature measurements for Nimbus 5 electrically scanned microwave radiometer (ESMR) and Nimbus-E microwave spectrometer (NEMS) are used to retrieve the atmospheric water vapor, liquid water, and wind speed by a quasi-statistical retrieval technique. It is shown that the brightness temperature can be utilized to yield these parameters under various weather conditions. Observations at 19.35, 22.235, and 31.4 GHz were input to the regression equations. The retrieved values of these parameters for portions of two Nimbus 5 orbits are presented. Then comparison between the retrieved parameters and the available observations on the total water vapor content and the surface wind speed are made.

Chang, A. T. C.; Wilheit, T. T.

1979-01-01

139

Isobaric yield ratio difference and Shannon information entropy  

NASA Astrophysics Data System (ADS)

The Shannon information entropy theory is used to explain the recently proposed isobaric yield ratio difference (IBD) probe which aims to determine the nuclear symmetry energy. Theoretically, the difference between the Shannon uncertainties carried by isobars in two different reactions (?In21), is found to be equivalent to the difference between the chemical potentials of protons and neutrons of the reactions [the IBD probe, IB- ?(??)21, with ? the reverse temperature]. From the viewpoints of Shannon information entropy, the physical meaning of the above chemical potential difference is interpreted by ?In21 as denoting the nuclear symmetry energy or density difference between neutrons and protons in reactions more concisely than from the statistical ablation-abrasion model.

Ma, Chun-Wang; Wei, Hui-Ling; Wang, Shan-Shan; Ma, Yu-Gang; Wada, Ryoichi; Zhang, Yan-Li

2015-03-01

140

Reference pressure changes and available potential energy in isobaric coordinates  

NASA Technical Reports Server (NTRS)

A formulation of the available potential energy (APE) equation in isobaric coordinates which alleviates the need for computing temporal derivatives of reference pressure and describes how work done relates to changes in the APE of a limited region is presented. The APE budget equation possesses terms analogous to those in Johnson's (1970) isentropic version. It is shown that APE changes result from either mechanical work inside the domain or an exchange of energy via boundary processes with the surrounding environment.

Robertson, F. R.

1985-01-01

141

Isotopic ratio, isotonic ratio, isobaric ratio and Shannon information uncertainty  

E-print Network

The isoscaling and the isobaric yield ratio difference (IBD) probes, which both are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to $\\beta-\\alpha$ determined by the isoscaling [$\\alpha$ ($\\beta$) is the parameter fitted from the isotopic (isotonic) yield ratio].

Chun-Wang Ma; Hui-Ling Wei

2014-09-11

142

Isotopic Ratio, Isotonic Ratio, Isobaric Ratio and Shannon Information Uncertainty  

NASA Astrophysics Data System (ADS)

The isoscaling and the isobaric yield ratio difference (IBD) probes, both of which are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to ? – ? determined by the isoscaling (? (?) is the parameter fitted from the isotopic (isotonic) yield ratio).

Ma, Chun-Wang; Wei, Hui-Ling

2014-11-01

143

Volume crossover in deeply supercooled water adiabatically freezing under isobaric conditions  

NASA Astrophysics Data System (ADS)

The irreversible return of a supercooled liquid to stable thermodynamic equilibrium often begins as a fast process which adiabatically drives the system to solid-liquid coexistence. Only at a later stage will solidification proceed with the expected exchange of thermal energy with the external bath. In this paper we discuss some aspects of the adiabatic freezing of metastable water at constant pressure. In particular, we investigated the thermal behavior of the isobaric gap between the molar volume of supercooled water and that of the warmer ice-water mixture which eventually forms at equilibrium. The available experimental data at ambient pressure, extrapolated into the metastable region within the scheme provided by the reference IAPWS-95 formulation, show that water ordinarily expands upon (partially) freezing under isenthalpic conditions. However, the same scheme also suggests that, for increasing undercoolings, the volume gap is gradually reduced and eventually vanishes at a temperature close to the currently estimated homogeneous ice nucleation temperature. This behavior is contrasted with that of substances which do not display a volumetric anomaly. The effect of increasing pressures on the alleged volume crossover from an expanded to a contracted ice-water mixture is also discussed.

Aliotta, Francesco; Giaquinta, Paolo V.; Pochylski, Mikolaj; Ponterio, Rosina C.; Prestipino, Santi; Saija, Franz; Vasi, Cirino

2013-05-01

144

All-atom force field for the prediction of vapor-liquid equilibria and interfacial properties of HFA134a.  

PubMed

A new all-atom force field capable of accurately predicting the bulk and interfacial properties of 1,1,1,2-tetrafluoroethane (HFA134a) is reported. Parameterization of several force fields with different initial charge configurations from ab initio calculations was performed using the histogram reweighting method and Monte Carlo simulations in the grand canonical ensemble. The 12-6 Lennard-Jones well depth and diameter for the different HFA134a models were determined by fitting the simulation results to pure-component vapor-equilibrium data. Initial screening of the force fields was achieved by comparing the calculated and experimental bulk properties. The surface tension of pure HFA134a served as an additional screening property to help discriminate an optimum model. The proposed model reproduces the experimental saturated liquid and vapor densities, and the vapor pressure for HFA134a within average errors of 0.7%, 4.4%, and 3.1%, respectively. Critical density, temperature, vapor pressure, normal boiling point, and heat of vaporization at 298 K are also in good agreement with experimental data with errors of 0.2%, 0.1%, 6.2%, 0%, 2.2%, respectively. The calculated surface tension is found to be within the experimental range of 7.7-8.1 mN.m(-1). The dipole moment of the different models was found to significantly affect the prediction of the vapor pressure and surface tension. The ability of the HFA134a models in predicting the interfacial tension against water is also discussed. The results presented here are relevant in the development of technologies where the more environmentally friendly HFA134a is utilized as a substitute to the ozone depleting chlorofluorocarbon propellants. PMID:19086791

Peguin, Robson P S; Kamath, Ganesh; Potoff, Jeffrey J; da Rocha, Sandro R P

2009-01-01

145

Interface pn junction arrays with high yielded grown p-Si microneedles by vapor-liquid-solid method at low temperature  

NASA Astrophysics Data System (ADS)

In this work we report the fabrication and investigation of the properties of interface pn junction arrays formed at the interface of vertically aligned p-Si microneedles and n-Si substrate. Arrays of boron doped p-Si microneedles were grown on n-Si substrate with the maximum yield of 100% by Au-catalysed vapor-liquid-solid (VLS) growth using in-situ doping with the mixed gas of Si2H6 and B2H6 at temperature less than 700 °C, which is low as compared to the temperature (1100 °C) required by diffusion process to dope Si microneedles after VLS growth. The physical dimension (diameter, length) and position of these p-Si microneedles can be controlled. The variation of growth rate, diameter, conductivity, impurity concentration and hole mobility of these p-Si microneeedles were investigated with the variation of boron doping. The pn junctions, formed with p-Si microneedles having different diameters, were found to exhibit standard diode characteristics. These pn junction embedded Si microneedle arrays might be potential candidate in sensor area applications. Again, low temperature processing would be compatible to integrate these junction arrays with other circuitry on a chip. This work provides one step forward to realize more sophisticated vertical active devices (BJT, MOSFET, etc) with Si microneedles.

Islam, Md. Shofiqul; Ishida, Makoto

2015-01-01

146

Molecular simulation of the shear viscosity and the self-diffusion coefficient of mercury along the vapor-liquid coexistence curve  

NASA Astrophysics Data System (ADS)

In earlier work [G. Raabe and R. J. Sadus, J. Chem. Phys. 119, 6691 (2003)] we reported that the combination of an accurate two-body ab initio potential with an empirically determined multibody contribution enables the prediction of the phase coexistence properties, the heats of vaporization, and the pair distribution functions of mercury with reasonable accuracy. In this work we present molecular dynamics simulation results for the shear viscosity and self-diffusion coefficient of mercury along the vapor-liquid coexistence curve using our empirical effective potential. The comparison with experiment and calculations based on a modified Enskog theory shows that our multibody contribution yields reliable predictions of the self-diffusion coefficient at all densities. Good results are also obtained for the shear viscosity of mercury at low to moderate densities. Increasing deviations between the simulation and experimental viscosity data at high densities suggest that not only a temperature-dependent but also a density-dependent multibody contribution is necessary to account for the effect of intermolecular interactions in liquid metals. An analysis of our simulation data near the critical point yields a critical exponent of ? =0.39, which is identical to the value obtained from the analysis of the experimental saturation densities.

Raabe, Gabriele; Todd, B. D.; Sadus, Richard J.

2005-07-01

147

The activity-composition relationship of oxygen and hydrogen isotopes in aqueous salt solutions: I. vapor-liquid water equilibration of single salt solutions from 50 to 100[degrees]C  

Microsoft Academic Search

The differences between oxygen and hydrogen isotope activity and composition ratios of water in single salt solutions (NaCl, KCl, MgCl[sub 2], CaCl[sub 2], Na[sub 2]SO[sub 4], and MgSO[sub 4]) were determined by means of a vapor-liquid water equilibration method over the temperature range of 50 to 100[degrees]C. A parallel equilibration technique of pure water and salt solutions with the same

J. Horita; D. J. Wesolowski; D. R. Cole

1993-01-01

148

Improvement of non-isobaric model for shock ignition  

NASA Astrophysics Data System (ADS)

In this paper, improved relations of total fuel energy, fuel gain, hot-spot radius and total areal density in a non-isobaric model of fuel assembly have been derived and compared with the numerical results of [J. Schmitt, J.W. Bates, S.P. Obenschain, S.T. Zalesak, D.E. Fyfe, Phys. Plasmas 17, 042701 (2010); S. Atzeni, A. Marocchino, A. Schiavi, G. Schurtz, New J. Phys. 15, 045004 (2013)] and several simulations performed by MULTI-1D radiation hydrodynamic code for shock ignition scenario. Our calculations indicate that the approximations made by [M.D. Rosen, J.D. Lindl, A.R. Thiessen, LLNL Laser Program Annual Report, UCRL-50021-83, pp. 3-5 (1983); J. Schmitt, J.W. Bates, S.P. Obenschain, S.T. Zalesak, D.E. Fyfe, Phys. Plasmas 17, 042701 (2010)] for the calculation of burn-up fraction are not accurate enough to give results consistent with simulations. Therefore, we have introduced more appropriate approximations for the burn-up fraction and total areal density of the fuel that are in more agreement with simulation results of shock ignition. Meanwhile, it is shown that the related formulas of the non-isobaric model for total fuel energy, fuel gain and also hot-spot radius cannot determine the model parameters independently, but improved model choose a better selection and less restrictions on determination of the parameters for the non-isobaric model. Such derivations can be used in theoretical studies of the ignition conditions and burn-up fraction of the fuel in shock ignition scenario.

Farahbod, Amir Hossein; Abolfazl Ghasemi, Seyed; Jafar Jafari, Mohammad; Rezaei, Somayeh; Sobhanian, Samad

2014-10-01

149

Encoding abrupt and uniform dopant profiles in vapor-liquid-solid nanowires by suppressing the reservoir effect of the liquid catalyst.  

PubMed

Semiconductor nanowires (NWs) are often synthesized by the vapor-liquid-solid (VLS) mechanism, a process in which a liquid droplet-supplied with precursors in the vapor phase-catalyzes the growth of a solid, crystalline NW. By changing the supply of precursors, the NW composition can be altered as it grows to create axial heterostructures, which are applicable to a range of technologies. The abruptness of the heterojunction is mediated by the liquid catalyst, which can act as a reservoir of material and impose a lower limit on the junction width. Here, we demonstrate that this "reservoir effect" is not a fundamental limitation and can be suppressed by selection of specific VLS reaction conditions. For Au-catalyzed Si NWs doped with P, we evaluate dopant profiles under a variety of synthetic conditions using a combination of elemental imaging with energy-dispersive X-ray spectroscopy and dopant-dependent wet-chemical etching. We observe a diameter-dependent reservoir effect under most conditions. However, at sufficiently slow NW growth rates (?250 nm/min) and low reactor pressures (?40 Torr), the dopant profiles are diameter independent and radially uniform with abrupt, sub-10 nm axial transitions. A kinetic model of NW doping, including the microscopic processes of (1) P incorporation into the liquid catalyst, (2) P evaporation from the catalyst, and (3) P crystallization in the Si NW, quantitatively explains the results and shows that suppression of the reservoir effect can be achieved when P evaporation is much faster than P crystallization. We expect similar reaction conditions can be developed for other NW systems and will facilitate the development of NW-based technologies that require uniform and abrupt heterostructures. PMID:25363730

Christesen, Joseph D; Pinion, Christopher W; Zhang, Xing; McBride, James R; Cahoon, James F

2014-11-25

150

The non-Newtonian heat and mass transport of He 2 in porous media used for vapor-liquid phase separation. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

This investigation of vapor-liquid phase separation (VLPS) of He 2 is related to long-term storage of cryogenic liquid. The VLPS system utilizes porous plugs in order to generate thermomechanical (thermo-osmotic) force which in turn prevents liquid from flowing out of the cryo-vessel (e.g., Infrared Astronomical Satellite). An apparatus was built and VLPS data were collected for a 2 and a 10 micrometer sintered stainless steel plug and a 5 to 15 micrometer sintered bronze plug. The VLPS data obtained at high temperature were in the nonlinear turbulent regime. At low temperature, the Stokes regime was approached. A turbulent flow model was developed, which provides a phenomenological description of the VLPS data. According to the model, most of the phase separation data are in the turbulent regime. The model is based on concepts of the Gorter-Mellink transport involving the mutual friction known from the zero net mass flow (ZNMF) studies. The latter had to be modified to obtain agreement with the present experimental VLPS evidence. In contrast to the well-known ZNMF mode, the VLPS results require a geometry dependent constant (Gorter-Mellink constant). A theoretical interpretation of the phenomenological equation for the VLPS data obtained, is based on modelling of the dynamics of quantized vortices proposed by Vinen. In extending Vinen's model to the VLPS transport of He 2 in porous media, a correlation between the K*(GM) and K(p) was obtained which permits an interpretation of the present findings. As K(p) is crucial, various methods were introduced to measure the permeability of the porous media at low temperatures. Good agreement was found between the room temperature and the low temperature K(p)-value of the plugs.

Yuan, S. W. K.

1985-01-01

151

Measurement of vapor/liquid distributions in a binary-component fuel spray using laser imaging of droplet scattering and vapor absorption  

NASA Astrophysics Data System (ADS)

Fuel volatility has a great effect on its evaporation processes and the mixture formation and thus combustion and emissions formation processes in internal combustion engines. To date, however, instead of the actual gasoline or diesel fuel, many researchers have been using single-component fuel in their studies, because the composition of the former is too complicated to understand the real physics behind the evaporation and combustion characteristics. Several research groups have reported their results on droplets evaporation in a spray of multi-component fuel, carried out both numerically and experimentally. However, there are plenty of difficulties in quantitative determination of vapor concentration and droplet distributions of each component in a multicomponent fuel spray. In this study, to determine the vapor phase concentration and droplet distributions in an evaporating binary component fuel spray, a laser diagnostics based on laser extinction by droplet scattering and vapor absorption was developed. In practice, measurements of the vapor concentration distributions of the lower (n-tridencane) and higher (n-octane) volatility components in the binary component fuel sprays have been carried out at ambient temperatures of 473K and 573K, by substituting p-xylene for noctane or ?-methylnaphthalene for n-tridecane. p-Xylene and ?-methylnaphthalene were selected as the substitutes is because they have strong absorption band near 266nm and transparent near 532nm and, their thermo-physical properties are similar to those of the original component. As a demonstration experiment, vapor/liquid distribution of the lower boiling point (LBP) and higher boiling point (HBP) components in the binary component fuel spray have been obtained.

Li, Shiyan; Zhang, Yuyin; Wu, Shenqi; Xu, Bin

2014-08-01

152

Isobaric Versus Hypobaric Spinal Bupivacaine for Total Hip Arthroplasty in the Lateral Position  

Microsoft Academic Search

Total hip arthroplasty (THA) is frequently performed under spinal anesthesia using either isobaric or hypo- baric anesthetic solution. However, these two solutions have never been compared under similar surgical con- ditions. In the present study, we compared the anes- thetic and hemodynamic effects of isobaric and hypo- baric bupivacaine in 40 ASA physical status I-II patients undergoing THA in the

Alexandre Faust; Roxane Fournier; Elisabeth Van Gessel; Anne Weber; Pierre Hoffmeyer; Zdravko Gamulin

2003-01-01

153

An isobar separation method with Q3D magnetic spectrometer for AMS  

NASA Astrophysics Data System (ADS)

Isobar interference is the main obstacle for AMS measurement, especially in the case of very strong isobaric interference, such as in the measurement of 32Si, 53Mn, 60Fe, 63Ni, etc. An isobar separation method with Q3D magnetic spectrometer was developed aiming at AMS measurements for the above-mentioned nuclides. Based on a method of (?E-Q3D) the isobaric events can be largely rejected from the region of the nuclide of interest on the focal plane of a Q3D magnetic spectrometer. As a result, the isobaric interference can be reduced by more than three orders of magnitude. Further reduction of isobaric interference can be achieved by the use of a multi-anode ionization chamber placed at the position of collecting the nuclide of interest. The performance of the ?E-Q3D system for isobar separation was tested by the above-mentioned nuclides with atomic numbers from 14 to 42. The results showed that ?E-Q3D method has strong capability for separating isobars, as detailed in this paper.

Li, Chaoli; He, Ming; Jiang, Shan; Li, Shizhuo; Gong, Jie; Liu, Jiancheng; Wang, Wei; He, GuoZhu; Wu, Shaoyong; Dong, Kejun; Wang, Xianggao; Shen, Hongtao

2010-10-01

154

Neutron Star Matter Including Delta Isobars Guang-Zhou Liu1,2  

E-print Network

Neutron Star Matter Including Delta Isobars Guang-Zhou Liu1,2 , Wei Liu1 and En-Guang Zhao2 1 a new phase structure of neutron star matter including nucleons and delta isobars is presented. Particle fractions populated and pion condensations in neutron star matter are investgated in this model

Xu, Ren-Xin

155

Stars equilibrium  

NSDL National Science Digital Library

What causes the fusion reaction in a star's core? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to processes inside a star. Students read about the equilibrium process in a star, in which outward gas pressure equals inward gravitational pressure. Then, an interactive lab activity offers students the opportunity to predict temperature, pressure, and gravity changes that occur during equilibrium. The chemical reactions of the fusion process are presented, and more specific detailed reactions are available in a pop-up box. Student practice quizzes about the equilibrium process and pressure and gravity interactions inside the star are included, as are answers. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

156

The isobaric multiplet mass equation for A?71 revisited  

SciTech Connect

Accurate mass determination of short-lived nuclides by Penning-trap spectrometers and progress in the spectroscopy of proton-rich nuclei have triggered renewed interest in the isobaric multiplet mass equation (IMME). The energy levels of the members of T=1/2,1,3/2, and 2 multiplets and the coefficients of the IMME are tabulated for A?71. The new compilation is based on the most recent mass evaluation (AME2011) and it includes the experimental results on energies of the states evaluated up to end of 2011. Taking into account the error bars, a significant deviation from the quadratic form of the IMME for the A=9,35 quartets and the A=32 quintet is observed.

Lam, Yi Hua, E-mail: lamyihua@gmail.com [CENBG (UMR 5797 — Université Bordeaux 1 — CNRS/IN2P3), Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan Cedex (France); Blank, Bertram, E-mail: blank@cenbg.in2p3.fr [CENBG (UMR 5797 — Université Bordeaux 1 — CNRS/IN2P3), Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan Cedex (France)] [CENBG (UMR 5797 — Université Bordeaux 1 — CNRS/IN2P3), Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan Cedex (France); Smirnova, Nadezda A. [CENBG (UMR 5797 — Université Bordeaux 1 — CNRS/IN2P3), Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan Cedex (France)] [CENBG (UMR 5797 — Université Bordeaux 1 — CNRS/IN2P3), Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan Cedex (France); Bueb, Jean Bernard; Antony, Maria Susai [IPHC, Université de Strasbourg, CNRS/UMR7178, 23 Rue du Loess, 67037 Strasbourg Cedex (France)] [IPHC, Université de Strasbourg, CNRS/UMR7178, 23 Rue du Loess, 67037 Strasbourg Cedex (France)

2013-11-15

157

Hard breakup of the deuteron into two {Delta} isobars  

SciTech Connect

We study high-energy photodisintegration of the deuteron into two {Delta} isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn{yields}{Delta}{Delta} scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn{yields}{Delta}{Delta} scattering. We predict that the cross section of the deuteron breakup to {Delta}{sup ++}{Delta}{sup -} is 4-5 times larger than that of the breakup to the {Delta}{sup +}{Delta}{sup 0} channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard {Delta} isobars are the result of the disintegration of the preexisting {Delta}{Delta} components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both {Delta}{sup ++}{Delta}{sup -} and {Delta}{sup +}{Delta}{sup 0} channels to be similar.

Granados, Carlos G.; Sargsian, Misak M. [Florida International University, Miami, Florida 33199 (United States)

2011-05-15

158

Rotational Equilibrium  

NSDL National Science Digital Library

In this activity, learners explore the concept of rotational equilibrium. Learners work in teams to estimate and determine the force within a mobile design. Learners solve algebraic equations, apply graphing techniques, compare results and discuss findings. Designing the mobile requires learners to solve a set of two linear algebraic equations. Learners solve the equations using three different methods: by substitution, by graphing the equations and finding the intersection, and by using determinants.

IEEE

2014-05-22

159

Rapid Analysis of Isobaric Exogenous Metabolites by Differential Mobility Spectrometry Mass Spectrometry  

SciTech Connect

The direct separation of isobaric glucuronide metabolites from propranolol dosed tissue extracts by differential mobility spectrometry mass spectrometry (DMS-MS) with the use of a polar gas-phase chemical modifier was demonstrated. The DMS gas-phase separation was able to resolve the isobaric metabolites with separation times on the order of ms instead of mins to hrs typically required when using pre-ionization chromatographic separation methods. Direct separation of isobaric metabolites from the complex tissue extract was validated using standards as well as implementing an HPLC separation prior to the DMS-MS analysis to pre-separate the species of interest. The ability to separate isobaric exogenous metabolites directly from a complex tissue extract is expected to facilitate the drug development process by increasing analytical throughput without the requirement for pre-ionization cleanup or separation strategies.

Parson, Whitney B [ORNL; Schneider, Bradley B [MDS Sciex; Kertesz, Vilmos [ORNL; Corr, Jay [AB Sciex; Covey, Thomas R. [MDS Sciex; Van Berkel, Gary J [ORNL

2011-01-01

160

Deformation effects on isospin mixing and isobar analogue resonance for 74-80Kr isotopes  

NASA Astrophysics Data System (ADS)

Pyatov's method has been applied to investigate Fermi beta transitions in deformed 74-80Kr isotopes. This self-consistent method, which was used to study the isobar analogue states in the spherical odd-odd nuclei, has to date not been applied for the isobar analogue states in deformed nuclei. The nucleon-nucleon residual interaction has been included so that the broken isospin symmetry in the mean field approximation has been restored and the strength parameter of the effective interaction has been taken out to be a free parameter. The energies and wave functions of the isobaric analogue excitations in 74-80Rb isotopes have been obtained within the framework of the pnQRPA method. The probability of the isospin mixing in the ground states and the centroid energies of the isobar analogue resonance have been presented and the deformation effects on these quantities have been quantified.

Aygör, Hasan; Ünlü, Serdar; Çakmak, Neçla; Selam, Cevat

2014-07-01

161

Rotational-Vibrational Raman Spectroscopy for Measurements of Thermochemistry in Non-isobaric Environments  

E-print Network

The present work examines line measurements of pressure, temperature, and density in high speed, non-isobaric flows emanating from an underexpanded jet nozzle. Line images of rotational and vibrational Raman spectra are collected for a 8-mm linear...

Bayeh, Alexander C.

2010-01-14

162

Al–Ga–Zn Phase Diagram. Calorimetric study of the isobaric invariants  

Microsoft Academic Search

The Al–Ga–Zn ternary phase diagram presents two isobaric invariant reactions: a eutectic at 231C and a metatectic at 1231C\\u000a [1–3]. Calorimetric measurements on the two isobaric invariant reactions have been carried out. First the Tammann method has\\u000a enabled us to determine the composition of their limits on five isopletic cross sections. Then, the compositions of the invariant\\u000a phases have been

E. Aragon; K. Jardet; P. Satre; A. Sebaoun

2000-01-01

163

Stable carbon and hydrogen isotope fractionation of dissolved organic groundwater pollutants by equilibrium sorption  

NASA Astrophysics Data System (ADS)

Linear free energy relationships (LFERs) were established which relate equilibrium vapor-liquid isotope effects to stable carbon and hydrogen isotope enrichment factors for equilibrium sorption to geosorbents. The LFERs were established for normal, cyclic or branched alkanes, monoaromatic hydrocarbons, and chloroethenes. These LFERs predict that isotopic light compounds sorb more strongly than their heavy counterparts. Defining fractionation as in classical literature by "heavy divided by light", carbon enrichment factors for equilibrium sorption were derived which ranged from - 0.13 ± 0.04‰ (benzene) to - 0.52 ± 0.19‰ (trichloroethene at 5-15 °C). Hydrogen enrichment factors for sorption of 14 different compounds were between - 2.4 and - 9.2‰. For perdeuterated hydrocarbons the predicted enrichment factors ranged from - 19 ± 5.4‰ (benzene) to - 64 ± 30‰ (cyclohexane). Equilibrium sorption experiments with a soil and activated carbon as sorbents were performed in the laboratory for perdeuterocyclohexane and perdeuterotoluene. The measured D/H enrichments agreed with the LFER prediction for both compounds and both sorbents within the uncertainty estimate of the prediction. The results of this work suggest that equilibrium sorption does create only very small isotope shifts for 13C in groundwater pollutants in aquifers. It is also suggested that deuterium shifts are expected to be higher, especially for strongly sorbing pollutants.

Höhener, Patrick; Yu, Xianjing

2012-03-01

164

4C modeling of the supercritical helium loop HELIOS in isobaric configuration  

NASA Astrophysics Data System (ADS)

Superconducting magnets for tokamak fusion reactors are subject to highly variable loads due to the intrinsically pulsed operation of the machine. The refrigerator should, on the contrary, work under conditions as stable as possible and should be sized based on the averaged loads. In this paper, the cryogenic circuit module of the 4C (Cryogenic Circuit Conductor and Coil) code is used to analyze the isobaric configuration of the HELIOS (HElium Loop for hIgh lOads Smoothing) facility at CEA Grenoble, France. The 4C model is validated against experimental data from the isobaric HELIOS configuration: the computed evolution of temperature, pressure and mass flow rate at different circuit locations shows a good agreement with the measurements for two different pulsed heat load scenarios, with and without regulation. The advantages of the (somewhat more complicated) isobaric configuration vs. the isochoric configuration in terms of heat load smoothing are highlighted. 4C simulations are used to propose a new HELIOS layout with helium charging and discharging lines located in such a way that the HELIOS performance in the isobaric configuration is optimized. The paper confirms the importance of the isobaric configuration for a tokamak cryogenic circuit, as well as the accuracy of 4C in modeling the HELIOS operation, even in the presence of complex regulation.

Guelfi, F.; Bonifetto, R.; Hoa, C.; Savoldi, L.; Zanino, R.

2014-11-01

165

Spontaneous breakdown of isospin symmetry in nuclei and isobaric analog states  

SciTech Connect

We present a self-consistent analysis of SU(2)-isospin symmetry breakdown in nuclei. We derive the energy difference of nearby nuclei ([ital Z] and [ital Z][minus]1) with the same [ital A] and splitting in the dispersion relations of protons and neutrons and show that the isobaric analog state is the massive Goldstone boson associated with the isospin polarization of the vacuum. The key relation in this analysis is the partially conserving isobaric current relation (PCIC); this is analogous to the PCAC relation with pion being the massive Goldstone boson.

Danchev, I.C.; Khanna, F.C. (TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada) Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada)); Umezawa, H. (Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada))

1994-12-01

166

MilQuant: a free, generic software tool for isobaric tagging-based quantitation.  

PubMed

Isobaric tagging techniques such as iTRAQ and TMT are widely used in quantitative proteomics and especially useful for samples that demand in vitro labeling. Due to diversity in choices of MS acquisition approaches, identification algorithms, and relative abundance deduction strategies, researchers are faced with a plethora of possibilities when it comes to data analysis. However, the lack of generic and flexible software tool often makes it cumbersome for researchers to perform the analysis entirely as desired. In this paper, we present MilQuant, mzXML-based isobaric labeling quantitator, a pipeline of freely available programs that supports native acquisition files produced by all mass spectrometer types and collection approaches currently used in isobaric tagging based MS data collection. Moreover, aside from effective normalization and abundance ratio deduction algorithms, MilQuant exports various intermediate results along each step of the pipeline, making it easy for researchers to customize the analysis. The functionality of MilQuant was demonstrated by four distinct datasets from different laboratories. The compatibility and extendibility of MilQuant makes it a generic and flexible tool that can serve as a full solution to data analysis of isobaric tagging-based quantitation. PMID:22789671

Zou, Xiao; Zhao, Minzhi; Shen, Hongyan; Zhao, Xuyang; Tong, Yuanpeng; Wang, Qingsong; Wei, Shicheng; Ji, Jianguo

2012-09-18

167

High-resolution enabled 12-plex DiLeu isobaric tags for quantitative proteomics.  

PubMed

Multiplex isobaric tags (e.g., tandem mass tags (TMT) and isobaric tags for relative and absolute quantification (iTRAQ)) are a valuable tool for high-throughput mass spectrometry based quantitative proteomics. We have developed our own multiplex isobaric tags, DiLeu, that feature quantitative performance on par with commercial offerings but can be readily synthesized in-house as a cost-effective alternative. In this work, we achieve a 3-fold increase in the multiplexing capacity of the DiLeu reagent without increasing structural complexity by exploiting mass defects that arise from selective incorporation of (13)C, (15)N, and (2)H stable isotopes in the reporter group. The inclusion of eight new reporter isotopologues that differ in mass from the existing four reporters by intervals of 6 mDa yields a 12-plex isobaric set that preserves the synthetic simplicity and quantitative performance of the original implementation. We show that the new reporter variants can be baseline-resolved in high-resolution higher-energy C-trap dissociation (HCD) spectra, and we demonstrate accurate 12-plex quantitation of a DiLeu-labeled Saccharomyces cerevisiae lysate digest via high-resolution nano liquid chromatography-tandem mass spectrometry (nanoLC-MS(2)) analysis on an Orbitrap Elite mass spectrometer. PMID:25405479

Frost, Dustin C; Greer, Tyler; Li, Lingjun

2015-02-01

168

A dynamical treatment of isobaric widths in fission : An example of frozen quantal fluctuations  

E-print Network

A dynamical treatment of isobaric widths in fission : An example of frozen quantal fluctuations H comme résultant des fluctuations dans le fondamental d'un oscillateur harmonique dépendant du temps dans distributions observed in the fission process as the result ofzero-point oscillations of a time dependent

Boyer, Edmond

169

Strategies for differentiation of isobaric flavonoids using liquid chromatography coupled to electrospray ionization mass spectrometry.  

PubMed

Flavonoids are a class of secondary plant metabolites existing in great variety in nature. Due to this variety, identification can be difficult, especially as overlapping compounds in both chromatographic separations and mass spectrometric detection are common. Methods for distinguishing isobaric flavonoids using MS(2) and MS(3) have been developed. Chromatographic separation of various plant extracts was done with RP-HPLC and detected with positive ESI-MS operated in information-dependent acquisition (IDA) mode. Two methods for the determination of flavonoid identity and substitution pattern, both featuring IDA criteria, were used together with the HPLC equipment. A third method where the collision energy was ramped utilized direct infusion. With the developed strategies, it is possible to differentiate between many isobaric flavonoids. Various classes of flavonoids were found in all of the plant extracts, in the red onion extract 45 components were detected and for 29 of them the aglycone was characterized, while the substituents were tentatively identified for 31 of them. For the strawberry extract, those numbers were 66, 30 and 60, and for the cherry extract 99, 56 and 71. The great variety of flavonoids, several of them isobaric, found in each of the extracts highlights the need for reliable methods for flavonoid characterization. Methods capable of differentiating between most of the isobars analyzed have been developed. PMID:25044850

Fridén, Mikael E; Sjöberg, Per J R

2014-07-01

170

An rf-carpet electrospray ion source to provide isobaric mass calibrants for trans-uranium elements  

E-print Network

For trans-uranium elements, stable atomic isobars do not exist. In order to provide isobaric reference ions for the mass measurement of trans-uranium elements, an electrospray ion source (ESI) was combined with an rf-carpet to collect molecular ions efficiently. The rf-carpet allows for simplification of the pumping system to transport ions from the ESI to a precision mass analyzer. Molecular ions appropriate for isobaric references of trans-uranium elements were extracted from the rf-carpet and analyzed by a multi-reflection time-of-flight mass spectrograph (MRTOF-MS) with a resolving power of $\\rm{R_m} \\gtrsim100,000$.

S. Naimi; S. Nakamura; Y. Ito; H. Mita; K. Okada; A. Ozawa; P. Schury; T. Sonoda; A. Takamine; M. Wada; H. Wollnik

2012-12-16

171

Analysis of Meson Exchange and Isobar Currents in (e,e'p) Reactions from O-16  

E-print Network

An analysis of the effects of meson exchange and isobar currents in exclusive (e,e'p) processes from O-16 under quasi-free kinematics is presented. A model that has probed its feasibility for inclusive quasi-elastic (e,e') processes is considered. Sensitivity to final state interactions between the outgoing proton and the residual nucleus is discussed by comparing the results obtained with phenomenological optical potentials and a continuum nuclear shell-model calculation. The contribution of the meson-exchange and isobar currents to the response functions is evaluated and compared to previous calculations, which differ notably from our results. These two-body contributions cannot solve the puzzle of the simultaneous description of the different responses experimentally separated. Copyright 1999 by The American Physical Society

J. E. Amaro; A. M. Lallena; J. A. Caballero

1999-04-13

172

Multiplexed Protein Quantitation in Saccharomyces cerevisiae Using Amine-reactive Isobaric Tagging Reagents  

Microsoft Academic Search

We describe here a multiplexed protein quantitation strat- egy that provides relative and absolute measurements of proteins in complex mixtures. At the core of this method- ology is a multiplexed set of isobaric reagents that yield amine-derivatized peptides. The derivatized peptides are indistinguishable in MS, but exhibit intense low-mass MS\\/MS signature ions that support quantitation. In this study, we have

Philip L. Ross; Yulin N. Huang; Jason N. Marchese; Brian Williamson; Kenneth Parker; Stephen Hattan; Nikita Khainovski; Sasi Pillai; Subhakar Dey; Scott Daniels; Subhasish Purkayastha; Peter Juhasz; Stephen Martin; Michael Bartlet-Jones; Feng He; Allan Jacobson; Darryl J. Pappin

2004-01-01

173

Quasi-two-body phase-space factors in the isobar model  

SciTech Connect

We present an integral representation of quasi-two-body phase-space factors in the isobar model, which in general enough to be used in phenomenological partial-wave scattering studies of systems such as ..pi..N, KN, NN, etc. We examine its analytic structure in detail, and furthermore cast it into an analytic form. This integral representation, with its analytic expression, is then convenient for use in analysis work.

Bhandari, R.

1982-03-01

174

Chapman Cycle Equilibrium Calculator  

NSDL National Science Digital Library

The Chapman Cycle Equilibrium Calculator solves for the equilibrium solution of the chemical reactions in the Chapman Cycle, assuming a solar flux equivalent to that at the top of the Earth's atmosphere. A Newton-Rhapson method is used to find the solution, which requires an initial guess as to the equilibrium solution.

The Shodor Education Foundation, Inc.

175

Overtaking while approaching equilibrium  

Microsoft Academic Search

A system initially far from equilibrium is expected to take more time to reach equilibrium than a system that was initially closer to equilibrium. The old puzzling observation (also called Mpemba effect) that when a sample of hot water and another sample of cold water are put in a freezer to equilibrate, the hot water sometimes overtakes as they cool,

P. Chaddah; S. Dash; Kranti Kumar; A. Banerjee

2010-01-01

176

Discrimination of large maltooligosaccharides from isobaric dextran and pullulan using ion mobility mass spectrometry  

PubMed Central

RATIONALE Ion mobility mass spectrometry (IMMS) has previously been shown to resolve small isobaric oligosaccharides, but larger alpha-oligoglucans are also abundant in biology and are of industrial importance. If conformational differences between such isomers are retained in the gas phase, IMMS could be used to address questions in biology and industry. METHODS Negative mode electrospray ionization (ESI) travelling-wave IMMS was used to resolve large isobaric ?-glucan ions on the basis of their different gas-phase conformations. ?,?-Dicarboxy-terminated polystyrene was used to calibrate the instrument allowing the collision cross-sections (CCSs) of ions to be determined. RESULTS ?-1,4-Linked maltooligosaccharides with a degree of polymerisation of up to 35 could be discriminated from ?-1,6-linked dextran and ?-1,4/1,6-linked pullulan using IMMS. Fragmentation spectra of ions separated by IMMS could also distinguish isomers. Two conformational isomers of maltohexaose were resolvable by IMMS, likely reflecting extended and V6 helical conformations. IMMS was also able to identify a product within a mixture of maltooligosaccharides treated with the potential anti-tuberculosis drug target Mycobacterium tuberculosis GlgB branching enzyme. CONCLUSIONS Biological samples of complex isobaric oligosaccharides can be analysed using IMMS in the negative mode providing facile analyses and high sensitivity without the need for either derivatisation or chromatographic separation. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd. PMID:24338967

Rashid, Abdul M; Saalbach, Gerhard; Bornemann, Stephen

2013-01-01

177

Target effects in isobaric yield ratio differences between projectile fragmentation reactions  

NASA Astrophysics Data System (ADS)

Background: The isobaric yield ratio difference (IBD) between reactions is know to be sensitive to the density difference between projectiles in heavy-ion collisions around the Fermi energy. Purpose: The target effects in the isobaric yield ratio (IYR) and the IBD results have been studied. Methods: The amount of isotopes in the 140 A MeV 48 ,40Ca +181Ta /9Be and 58 ,64Ni +181Ta /9Be reactions have been previously measured with high accuracy. The IYR and IBD results have been obtained from these reactions to study the effects of the light 9Be and heavy 181Ta targets. A ratio (r? ?) between the IBD results for the reactions with Ta and Be targets is defined to quantitatively show the target dependence of the IBD results. Results The IYRs for reactions with symmetric projectiles are more easily affected than those for reactions with neutron-rich projectiles. The IBD results are suppressed by using the 181Ta target to different degrees. Conclusions: The IYR and IBD results are influenced by the target used. The IBD for the I =1 isobaric chain is suggested as a probe to study the difference between the neutron and proton densities of the reaction systems.

Ma, Chun-Wang; Zhang, Yan-Li; Qiao, Chun-Yuan; Wang, Shan-Shan

2015-01-01

178

Overtaking while approaching equilibrium  

E-print Network

A system initially far from equilibrium is expected to take more time to reach equilibrium than a system that was initially closer to equilibrium. The old puzzling observation (also called Mpemba effect) that when a sample of hot water and another sample of cold water are put in a freezer to equilibrate, the hot water sometimes overtakes as they cool, has been highlighted recently. In the extensively studied colossal magnetoresistance manganites, cooling in a magnetic field (H) often results in an inhomogeneous mixture of transformed equilibrium phase and a kinetically arrested non-equilibrium phase which relaxes slowly towards equilibrium at fixed H and temperature (T). Here we show that the magnetization decay rate at the same H and T is larger for the state that was initially farther from equilibrium, and it continues to relax faster even after these have become equal. Our result should help propose an explanation, for Mpemba effect, that does not attribute it to any artifact.

Chaddah, P; Kumar, Kranti; Banerjee, A

2010-01-01

179

Overtaking while approaching equilibrium  

E-print Network

A system initially far from equilibrium is expected to take more time to reach equilibrium than a system that was initially closer to equilibrium. The old puzzling observation (also called Mpemba effect) that when a sample of hot water and another sample of cold water are put in a freezer to equilibrate, the hot water sometimes overtakes as they cool, has been highlighted recently. In the extensively studied colossal magnetoresistance manganites, cooling in a magnetic field (H) often results in an inhomogeneous mixture of transformed equilibrium phase and a kinetically arrested non-equilibrium phase which relaxes slowly towards equilibrium at fixed H and temperature (T). Here we show that the magnetization decay rate at the same H and T is larger for the state that was initially farther from equilibrium, and it continues to relax faster even after these have become equal. Our result should help propose an explanation, for Mpemba effect, that does not attribute it to any artifact.

P. Chaddah; S. Dash; Kranti Kumar; A. Banerjee

2010-11-16

180

Phase equilibrium of liquid mixtures: Experimental and modeled data using statistical associating fluid theory for potential of variable range approach  

NASA Astrophysics Data System (ADS)

A study of the phase equilibrium (experimental and modeled) of mixtures formed by a cyclic ether and haloalkanes has been derived. Experimental data for the isothermal vapor liquid equilibrium of mixtures formed by tetrahydrofuran and tetrahydropyran and isomeric chlorobutanes at temperatures of 298.15, 313.15, and 328.15K are presented. Experimental results have been discussed in terms of both molecular characteristics of pure compounds and potential intermolecular interaction between them using thermodynamic information of the mixtures obtained earlier. The statistical associating fluid theory for potential of variable range (SAFT-VR) approach together with standard combining rules without adjustable parameters has been used to model the phase equilibrium. Good agreement between experiment and the prediction is found with such a model. Mean absolute deviations for pressures are of the order of 1kPa, while less than 0.013mole fraction for vapor phase compositions. In order to improve the results obtained, a new modeling has been carried out by introducing a unique transferable parameter kij, which modifies the strength of the dispersion interaction between unlike components in the mixtures, and is valid for all the studied mixtures being not temperature or pressure dependent. This parameter together with the SAFT-VR approach provides a description of the vapor-liquid equilibrium of the mixtures that is in excellent agreement with the experimental data for most cases. The absolute deviations are of the order of 0.005mole fraction for vapor phase compositions and less than 0.3kPa for pressure, excepting for mixtures containing 2-chloro-2-methylpropane which deviations for pressure are larger. Results obtained in this work in the modeling of the phase equilibrium with the SAFT-VR equation of state have been compared to the ones obtained in a previous study when the approach was used to model similar mixtures with clear differences in the thermodynamic behavior. We show how the SAFT-VR approach is capable of differentiating the molecular features of a relatively wide set of different mixtures.

Giner, Beatriz; Bandrés, Isabel; Carmen López, M.; Lafuente, Carlos; Galindo, Amparo

2007-10-01

181

Electric and magnetic response to the continuum for A=7 isobars in a dicluster model  

E-print Network

Mirror isobars $^7$Li and $^7$Be are investigated in a dicluster model. The magnetic dipole moments and the magnetic dipole response to the continuum are calculated in this framework. The magnetic contribution is found to be small with respect to electric dipole and quadrupole excitations even at astrophysical energies, at a variance with the case of deuteron. Energy weighted molecular sum rules are evaluated and a formula for the molecular magnetic dipole sum rule is found which matches the numerical calculations. Cross-sections for photo-dissociation and radiative capture as well as the S-factor for reactions of astrophysical significance are calculated with good agreement with known experimental data.

A. Mason; R. Chatterjee; L. Fortunato; A. Vitturi

2008-11-11

182

Effect of isospin dependence of radius on transverse flow and fragmentation in isobaric pairs  

NASA Astrophysics Data System (ADS)

We study the role of nuclear structure effects through radius in reaction dynamics via transverse flow and multifragmentation of isobaric colliding pairs. Our study reveals that isospin-dependent radius [proposed by Royer and Rousseau [Eur. Phys. J. A10.1140/epja/i2008-10745-8 42, 541 (2009)] has significant effect towards isospin effects. The collective flow behavior and fragmentation pattern of neutron-rich system with respect to neutron-deficient system is found to get reversed with isospin-dependent radius compared to that with liquid drop radius.

Gautam, Sakshi

2013-11-01

183

Delta-isobar relativistic meson exchange currents in quasielastic electron scattering  

E-print Network

We study the role of the $\\Delta$-isobar current on the response functions for high energy inclusive quasielastic electron scattering from nuclei. We consider a general Lagrangian which is compatible with contact invariance and perform a fully relativistic calculation in first-order perturbation theory for one-particle emission. The dependence of the responses upon off-shell parametrizations is analyzed and found to be mild. A discussion of scaling behaviour and a comparison with various non-relativistic approaches are also presented.

J. E. Amaro; M. B. Barbaro; J. A. Caballero; T. W. Donnelly; A. Molinari

2003-03-24

184

Coefficients of the isobaric mass equation and their correlations with various nuclear parameters  

SciTech Connect

The coefficients of the isobaric multiplet mass equation M = a + bT{sub z} + cT{sub z}{sup 2} have been calculated for the 430 identified T = 1/2, 1, 3/2, 2 multiplets and correlations of its b, c coefficients with various nuclear parameters have been sought. For most mass numbers A there is a tendency for b to increase, and for c to decrease, with the average excitation energy of the multiplet. There seems to be no separate dependence of b or c on spin, but there could be a dependence of b on parity.

Britz, J.; Pape, A.; Antony, M.S. [Univ. Louis Pasteur, Strasbourg (France). Inst. de Recherches Subatomiques] [Univ. Louis Pasteur, Strasbourg (France). Inst. de Recherches Subatomiques

1998-05-01

185

Preprocessing Significantly Improves the Peptide/Protein Identification Sensitivity of High-resolution Isobarically Labeled Tandem Mass Spectrometry Data.  

PubMed

Isobaric labeling techniques coupled with high-resolution mass spectrometry have been widely employed in proteomic workflows requiring relative quantification. For each high-resolution tandem mass spectrum (MS/MS), isobaric labeling techniques can be used not only to quantify the peptide from different samples by reporter ions, but also to identify the peptide it is derived from. Because the ions related to isobaric labeling may act as noise in database searching, the MS/MS spectrum should be preprocessed before peptide or protein identification. In this article, we demonstrate that there are a lot of high-frequency, high-abundance isobaric related ions in the MS/MS spectrum, and removing isobaric related ions combined with deisotoping and deconvolution in MS/MS preprocessing procedures significantly improves the peptide/protein identification sensitivity. The user-friendly software package TurboRaw2MGF (v2.0) has been implemented for converting raw TIC data files to mascot generic format files and can be downloaded for free from https://github.com/shengqh/RCPA.Tools/releases as part of the software suite ProteomicsTools. The data have been deposited to the ProteomeXchange with identifier PXD000994. PMID:25435543

Sheng, Quanhu; Li, Rongxia; Dai, Jie; Li, Qingrun; Su, Zhiduan; Guo, Yan; Li, Chen; Shyr, Yu; Zeng, Rong

2015-02-01

186

Pre-vaporizing liquid fuel burner  

SciTech Connect

A burner is described which consists of: (a) a housing formed with an internal chamber; (b) eductor means mounted to the housing at a forward end of the chamber, the eductor means formed with a passageway having an inlet and an outlet, a plurality of air ducts disposed within the passageway, the air ducts arranged to direct air flowing therein into a path toward the longitudinal axis of the chamber from the forward end of the chamber to a rear end thereof; (c) first means for introducing air into the chamber through the air ducts, recirculated combustion gas being drawn into the eductor means inlet, through the passageway and out the eductor means outlet by air flowing through the ducts, the gas and air entering the chamber in interleaving streams of gas and air, the gas and air mixing in the chamber; (d) second means for introducing fuel into the rear of the chamber in the flow path of the streams of gas and air, the fuel mixing with the mixture of combustion gas and air in the rear portion of the chamber to form a mixture of combustion gas, fuel, and air; and (e) flameholder means for supporting a flame, the flame-holder means positioned at the eductor means inlet, the combustion gas being drawn from the flame on the flame-holder means into the eductor means inlet, and means for delivering the mixture of combustion gas, fuel and air to the flameholder means about the eductor means.

Harvey, A.C.

1986-08-19

187

Pre-vaporizing liquid fuel burner  

Microsoft Academic Search

A burner is described which consists of: (a) a housing formed with an internal chamber; (b) eductor means mounted to the housing at a forward end of the chamber, the eductor means formed with a passageway having an inlet and an outlet, a plurality of air ducts disposed within the passageway, the air ducts arranged to direct air flowing therein

1986-01-01

188

Vapor-liquid phase separator studies  

NASA Technical Reports Server (NTRS)

Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

Yuan, S. W. K.; Lee, J. M.; Kim, Y. I.; Hepler, W. A.; Frederking, T. H. K.

1983-01-01

189

Misconceptions of chemical equilibrium  

Microsoft Academic Search

Those propositions deemed necessary for an understanding of chemical equilibrium and Le Chatelier's Principle were defined by the investigators and validated.Thirty, Year 12 Western Australian chemistry students (17 years of age) who had studied chemical equilibrium were interviewed and students’ responses were coded into various categories of misconception that had been identified. The most significant misconceptions revealed by the study

Mark W. Hackling; Patrick J. Garnett

1985-01-01

190

Computing the Electricity Market Equilibrium: Uses of market equilibrium models  

E-print Network

1 Computing the Electricity Market Equilibrium: Uses of market equilibrium models Ross Baldick Abstract--In this paper we consider the formulation and uses of electric- ity market equilibrium models. Keywords--Electricity market, Equilibrium models I. INTRODUCTION Electricity market equilibrium modelling

Baldick, Ross

191

Equilibrium and volumetric data and model development for coal fluids. Final report, October 1, 1990--September 30, 1993  

SciTech Connect

Under continued support from DOE, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for predicting the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with the supercritical solutes hydrogen, methane, ethane, CO, and CO{sub 2}. During the course of this project, solubility data were obtained on twenty-two binary mixtures of CO, hydrogen, or nitrogen in a series of paraffinic, naphthenic and aromatic solvents (decane, eicosane, octacosane, hexatriacontane, cyclohexane, decalin, benzene, naphthalene, phenanthrene, pyrene). The measurements were conducted at temperatures from 310 to 433 K, pressures to 22 MPa, and solute mole fraction from 0.01 to 0.30. Estimated errors of the measured gas solubilities in the selected solvents are less than 0.001. Specific accomplishments of this project included (a) upgrading our experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) and phase densities; (b) measuring these properties for systematically-selected binary mixtures to provide critically needed input data for correlation development; (c) developing and testing models suitable for describing the phase behavior of coal-fluid mixtures, and the modeling results in generalized, practical formats suitable for use in process engineering calculations.

Robinson, R.L. Jr.; Gasem, K.A.M.; Park, J.; Tong, J.; Shaver, R.D.; Bader, M.S.; Twomey, D.W.

1994-03-03

192

Isobaric yield ratios in heavy-ion reactions, and symmetry energy of neutron-rich nuclei at intermediate energies  

NASA Astrophysics Data System (ADS)

The isobaric yield ratios of the fragments produced in the neutron-rich Ca48 and Ni64 projectile fragmentation are analyzed in the framework of a modified Fisher model. The correlations between the isobaric yield ratios (R) and the energy coefficients in the Weiszäcker-Beth semiclassical mass formula (the symmetry-energy term asym, the Coulomb-energy term ac, and the pairing-energy term ap) and the difference between the chemical potentials of the neutron and proton (?n-?p) are investigated. Simple correlations between (?n-?p)/T, ac/T, asym/T, and ap/T (where T is the temperature), and lnR are obtained. It is suggested that (?n-?p)/T, ac/T, asym/T, and ap/T of neutron-rich nuclei can be extracted using isobaric yield ratios for heavy-ion collisions at intermediate energies.

Ma, Chun-Wang; Wang, Fang; Ma, Yu-Gang; Jin, Chan

2011-06-01

193

Breakdown of the Isobaric Multiplet Mass Equation for the A =20 and 21 Multiplets  

NASA Astrophysics Data System (ADS)

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of Mg20,21, isotopes that are the most proton-rich members of the A =20 and A=21 isospin multiplets. These measurements were possible through the use of a unique ion-guide laser ion source, a development that suppressed isobaric contamination by 6 orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of Mg21 is in good agreement but that the mass of Mg20 deviates by 3?. These measurements reduce the uncertainties in the masses of Mg20,21 by 15 and 22 times, respectively, resulting in a significant departure from the expected behavior of the isobaric multiplet mass equation in both the A =20 and A=21 multiplets. This presents a challenge to shell model calculations using either the isospin nonconserving universal sd USDA and USDB Hamiltonians or isospin nonconserving interactions based on chiral two- and three-nucleon forces.

Gallant, A. T.; Brodeur, M.; Andreoiu, C.; Bader, A.; Chaudhuri, A.; Chowdhury, U.; Grossheim, A.; Klawitter, R.; Kwiatkowski, A. A.; Leach, K. G.; Lennarz, A.; Macdonald, T. D.; Schultz, B. E.; Lassen, J.; Heggen, H.; Raeder, S.; Teigelhöfer, A.; Brown, B. A.; Magilligan, A.; Holt, J. D.; Menéndez, J.; Simonis, J.; Schwenk, A.; Dilling, J.

2014-08-01

194

Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensis.  

PubMed

Through the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity--forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished. PMID:19785003

Montoya, Guillermo; Arango, Gabriel J; Ramírez-Pineda, José R

2009-11-01

195

Breakdown of the isobaric multiplet mass equation for the A = 20 and 21 multiplets.  

PubMed

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of (20,21)Mg, isotopes that are the most proton-rich members of the A = 20 and A = 21 isospin multiplets. These measurements were possible through the use of a unique ion-guide laser ion source, a development that suppressed isobaric contamination by 6 orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of (21)Mg is in good agreement but that the mass of (20)Mg deviates by 3 ?. These measurements reduce the uncertainties in the masses of (20,21)Mg by 15 and 22 times, respectively, resulting in a significant departure from the expected behavior of the isobaric multiplet mass equation in both the A = 20 and A = 21 multiplets. This presents a challenge to shell model calculations using either the isospin nonconserving universal sd USDA and USDB Hamiltonians or isospin nonconserving interactions based on chiral two- and three-nucleon forces. PMID:25192091

Gallant, A T; Brodeur, M; Andreoiu, C; Bader, A; Chaudhuri, A; Chowdhury, U; Grossheim, A; Klawitter, R; Kwiatkowski, A A; Leach, K G; Lennarz, A; Macdonald, T D; Schultz, B E; Lassen, J; Heggen, H; Raeder, S; Teigelhöfer, A; Brown, B A; Magilligan, A; Holt, J D; Menéndez, J; Simonis, J; Schwenk, A; Dilling, J

2014-08-22

196

An approach for triplex-isobaric peptide termini labeling (triplex-IPTL).  

PubMed

Isobaric peptide termini labeling (IPTL) is based on labeling of both peptide termini with complementary isotopic labels resulting in isobaric peptides. MS/MS analysis after IPTL derivatization produces peptide-specific fragment ions which are distributed throughout the MS/MS spectrum. Thus, several quantification points can be obtained per peptide. In this report, we present triplex-IPTL, a chemical labeling strategy for IPTL allowing the simultaneous quantification of three states within one MS run. For this purpose, dimethylation of the N-terminal amino group followed by dimethylation of lysines was used with different stable isotopes of formaldehyde and cyanoborohydride. Upon LC-MS/MS analysis, the combined samples revealed three corresponding isotopic fragment ion series reflecting quantitatively the peptide ratios. To support this multiplexing labeling strategy, we have further developed the data analysis tool IsobariQ and included multidimensional VSN normalization, statistical inference, and graphical visualization of triplex-IPTL data and clustering of protein profiling patterns. The power of the triplex-IPTL approach in combination with IsobariQ was demonstrated through temporal profiling of HeLa cells incubated with the kinesin Eg5 inhibitor S-Trityl-l-cysteine (STLC). As a result, clusters of quantified proteins were found by their ratio profiles which corresponded well to their gene ontology association in mitotic arrest and cell death, respectively. PMID:23316706

Koehler, Christian J; Arntzen, Magnus Ø; de Souza, Gustavo Antonio; Thiede, Bernd

2013-02-19

197

Modeling of phase equilibrium and vapor adsorption on carbon black based on a combination of a lattice theory and equation of state.  

PubMed

A thermodynamic approach is developed in this paper to describe the behavior of a subcritical fluid in the neighborhood of vapor-liquid interface and close to a graphite surface. The fluid is modeled as a system of parallel molecular layers. The Helmholtz free energy of the fluid is expressed as the sum of the intrinsic Helmholtz free energies of separate layers and the potential energy of their mutual interactions calculated by the 10-4 potential. This Helmholtz free energy is described by an equation of state (such as the Bender or Peng-Robinson equation), which allows us a convenient means to obtain the intrinsic Helmholtz free energy of each molecular layer as a function of its two-dimensional density. All molecular layers of the bulk fluid are in mechanical equilibrium corresponding to the minimum of the total potential energy. In the case of adsorption the external potential exerted by the graphite layers is added to the free energy. The state of the interface zone between the liquid and the vapor phases or the state of the adsorbed phase is determined by the minimum of the grand potential. In the case of phase equilibrium the approach leads to the distribution of density and pressure over the transition zone. The interrelation between the collision diameter and the potential well depth was determined by the surface tension. It was shown that the distance between neighboring molecular layers substantially changes in the vapor-liquid transition zone and in the adsorbed phase with loading. The approach is considered in this paper for the case of adsorption of argon and nitrogen on carbon black. In both cases an excellent agreement with the experimental data was achieved without additional assumptions and fitting parameters, except for the fluid-solid potential well depth. The approach has far-reaching consequences and can be readily extended to the model of adsorption in slit pores of carbonaceous materials and to the analysis of multicomponent adsorption systems. PMID:16290856

Ustinov, E A; Do, D D

2002-09-15

198

Calorimeter for measuring the isobaric specific heat capacity of fluids and fluid mixtures by the thermal relaxation method  

SciTech Connect

We present a new calorimeter for measuring the isobaric specific heat capacity for fluids and fluid mixtures based on the thermal relaxation method. The calorimeter, which is equipped with a metal bellows, works in the temperature range from 250 to 500 K at pressures up to 20 MPa and is designed to satisfy the conditions of a lumped system. The calorimeter was calibrated using water and toluene. The isobaric specific heat capacity of methanol was measured at 323.15 K and 0.1 MPa, which confirms the reliability of the calorimeter. The uncertainty is estimated to be within 2.9% at a 95% confidence level.

Tanaka, K.; Uematsu, M. [Center for Multiscale Mechanics and Mechanical Systems, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522 (Japan)

2006-03-15

199

Computing Equilibrium Chemical Compositions  

NASA Technical Reports Server (NTRS)

Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

Mcbride, Bonnie J.; Gordon, Sanford

1995-01-01

200

Isobaric yield ratio difference and neutron density difference in calcium isotopes  

NASA Astrophysics Data System (ADS)

The isobaric yield ratio difference between two reactions is found to equal ??21/T, which denotes the ratio of the difference between the neutron and proton chemical potentials to the temperature. A series of projectile fragmentation reactions induced by calcium isotopes are calculated using a modified statistical abrasion-ablation model, assuming the neutron density distribution to be the Fermi type. The ??21/T from the prefragments are found to be sensitive to the difference between the neutron density distributions of projectiles, while ??21/T from the final fragments are very similar for the reactions and insensitive to the difference between the neutron density distributions of projectiles. The ??21/T from the prefragments and final fragments verify that the deexcitation modifies the results largely.

Ma, C. W.; Yu, J.; Bai, X. M.; Zhang, Y. L.; Wei, H. L.; Wang, S. S.

2014-05-01

201

Neutron density distributions of neutron-rich nuclei studied with the isobaric yield ratio difference  

NASA Astrophysics Data System (ADS)

The isobaric yield ratio difference (IBD) between two reactions of similar experimental setups is found to be sensitive to nuclear density differences between projectiles. In this article, the IBD probe is used to study the density variation in neutron-rich 48Ca . By adjusting diffuseness in the neutron density distribution, three different neutron density distributions of 48Ca are obtained. The yields of fragments in the 80 A MeV 40, 48Ca + 12C reactions are calculated by using a modified statistical abrasion-ablation model. It is found that the IBD results obtained from the prefragments are sensitive to the density distribution of the projectile, while the IBD results from the final fragments are less sensitive to the density distribution of the projectile.

Ma, Chun-Wang; Bai, Xiao-Man; Yu, Jiao; Wei, Hui-Ling

2014-09-01

202

An ion guide laser ion source for isobar-suppressed rare isotope beams  

NASA Astrophysics Data System (ADS)

Modern experiments at isotope separator on-line (ISOL) facilities like ISAC at TRIUMF often depend critically on the purity of the delivered rare isotope beams. Therefore, highly selective ion sources are essential. This article presents the development and successful on-line operation of an ion guide laser ion source (IG-LIS) for the production of ion beams free of isobaric contamination. Thermionic ions from the hot ISOL target are suppressed by an electrostatic potential barrier, while neutral radio nuclides effusing out are resonantly ionized by laser radiation within a quadrupole ion guide behind this barrier. The IG-LIS was developed through detailed thermal and ion optics simulation studies and off-line tests with stable isotopes. In a first on-line run with a SiC target a suppression of surface-ionized Na contaminants in the ion beam of up to six orders of magnitude was demonstrated.

Raeder, Sebastian; Heggen, Henning; Lassen, Jens; Ames, Friedhelm; Bishop, Daryl; Bricault, Pierre; Kunz, Peter; Mjøs, Anders; Teigelhöfer, Andrea

2014-03-01

203

An ion guide laser ion source for isobar-suppressed rare isotope beams  

SciTech Connect

Modern experiments at isotope separator on-line (ISOL) facilities like ISAC at TRIUMF often depend critically on the purity of the delivered rare isotope beams. Therefore, highly selective ion sources are essential. This article presents the development and successful on-line operation of an ion guide laser ion source (IG-LIS) for the production of ion beams free of isobaric contamination. Thermionic ions from the hot ISOL target are suppressed by an electrostatic potential barrier, while neutral radio nuclides effusing out are resonantly ionized by laser radiation within a quadrupole ion guide behind this barrier. The IG-LIS was developed through detailed thermal and ion optics simulation studies and off-line tests with stable isotopes. In a first on-line run with a SiC target a suppression of surface-ionized Na contaminants in the ion beam of up to six orders of magnitude was demonstrated.

Raeder, Sebastian, E-mail: sebastian.raeder@fys.kuleuven.be; Ames, Friedhelm; Bishop, Daryl; Bricault, Pierre; Kunz, Peter; Mjøs, Anders [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada)] [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Heggen, Henning, E-mail: heggen@triumf.ca [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada) [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Institute of Applied Physics, TU Darmstadt, Schlossgartenstr. 7, 64289 Darmstadt (Germany); Lassen, Jens, E-mail: lassen@triumf.ca; Teigelhöfer, Andrea [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada) [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2014-03-15

204

Gamow-Teller strength studied through {Gamma}-excitation of isobaric analog states  

SciTech Connect

We consider a measurement of isobaric analog states (IAS) of 76As in 76Se as a method for measuring the Gamow-Teller (GT) strength important to constrain and possibly help normalize calculations of double beta ({beta}{beta}) decay matrix elements. We show that photo-nuclear reactions via IAS can provide valuable information about the parent and daughter states of {beta}{beta}-decay not currently available from measurements of charge exchange reactions. Several experiments have been proposed at the HI{open_square} Sfacility at the Triangle Nuclear Research Laboratory in Durham, NC, the first of which will measure the lowest 1{sup -}, 1{sup +} and 2{sup +} IAS in {sup 76}Se.

Boswell, M. S. [Physics Division, Los Alamos National Laboratory, NM (United States); Young, A. R. [Physics Department, North Carolina State University, Raleigh, NC (United States); Ejiri, H. [RCNP, Osaka University, Osaka, 567-0047 (Japan) and Nuclear Science, Czech Technical University, Brehova, Prague (Czech Republic)

2013-04-19

205

Spontaneous symmetry breaking and the energy of nuclear isobaric analog states  

NASA Astrophysics Data System (ADS)

The asymmetry between proton and neutron numbers in a nucleus is viewed as a consequence of the spontaneous symmetry breaking of the isospin symmetry. The signatures of this effect, as it was suggested by Danchev, Khanna, and Umezawa and co-workers, may have been seen already in the energetics of the nuclear isobaric analog resonance state and in the systematic of double-odd double-even mass differences. In order to account for finite size effects, not included in Umezawa's approach, we have calculated the mean field term of the Hamiltonian in a realistic nuclear single-particle basis. The nonvanishing value of the I3 current in the nonperturbative vacuum is explained in terms of ? meson exchange.

Civitarese, O.; Montani, F.; Reboiro, M.; Toki, H.

2000-06-01

206

Neutron Density Distributions of Neutron-Rich Nuclei Studied with the Isobaric Yield Ratio Difference  

E-print Network

The isobaric yield ratio difference (IBD) between two reactions of similar experimental setups is found to be sensitive to nuclear density differences between projectiles. In this article, the IBD probe is used to study the density variation in neutron-rich $^{48}$Ca. By adjusting diffuseness in the neutron density distribution, three different neutron density distributions of $^{48}$Ca are obtained. The yields of fragments in the 80$A$ MeV $^{40, 48}$Ca + $^{12}$C reactions are calculated by using a modified statistical abrasion-ablation model. It is found that the IBD results obtained from the prefragments are sensitive to the density distribution of the projectile, while the IBD results from the final fragments are less sensitive to the density distribution of the projectile.

Chun-Wang Ma; Xiao-Man Bai; Jiao Yu; Hui-Ling Wei

2014-09-09

207

A new gas lesion syndrome in man, induced by 'isobaric gas counterdiffusion'  

NASA Technical Reports Server (NTRS)

Normal men have been found to develop pruritis and gas bubble lesions in the skin, and disruption of vestibular function, when breathing nitrogen or neon with oxygen while surrounded by helium at increased ambient pressure. This phenomenon, which occurs at stable ambient pressures, at 1 or many ATA, has been designated the isobaric gas counterdiffusion syndrome. In a series of analyses and experiments in vivo and in vitro the cause of the syndrome has been established as due to gas accumulation and development of gas bubbles in tissues as a result of differences in selective diffusivities, for various respired and ambient gases, in the tissue substances between capillary blood and the surrounding atmosphere. The phenomenon described in man is an initial stage of a process shown later in animals to progress to continuous, massive, lethal, intravascular gas embolization.

Lambertsen, C. J.; Idicula, J.

1975-01-01

208

Precision test of the isobaric multiplet mass equation for the A=32, T=2 quintet  

SciTech Connect

Masses of the radionuclides {sup 32,33}Si and {sup 34}P and of the stable nuclides {sup 32}S and {sup 31}P have been measured with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. Relative mass uncertainties as low as 3x10{sup -9} have been achieved. The measured mass value of {sup 32}Si differs from the literature value by four standard deviations. The precise mass determination of {sup 32}Si and {sup 32}S have been employed to test the validity of the quadratic form of the isobaric multiplet mass equation (IMME) for the most well known A=32, T=2 isospin quintet. The new experimental results indicate a dramatic breakdown of the model.

Kwiatkowski, A. A.; Barquest, B. R.; Bollen, G.; Campbell, C. M.; Lincoln, D. L.; Morrissey, D. J.; Pang, G. K.; Prinke, A. M.; Savory, J.; Schwarz, S.; Folden, C. M. III; Melconian, D.; Sjue, S. K. L.; Block, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan (United States); Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany)

2009-11-15

209

An ion guide laser ion source for isobar-suppressed rare isotope beams.  

PubMed

Modern experiments at isotope separator on-line (ISOL) facilities like ISAC at TRIUMF often depend critically on the purity of the delivered rare isotope beams. Therefore, highly selective ion sources are essential. This article presents the development and successful on-line operation of an ion guide laser ion source (IG-LIS) for the production of ion beams free of isobaric contamination. Thermionic ions from the hot ISOL target are suppressed by an electrostatic potential barrier, while neutral radio nuclides effusing out are resonantly ionized by laser radiation within a quadrupole ion guide behind this barrier. The IG-LIS was developed through detailed thermal and ion optics simulation studies and off-line tests with stable isotopes. In a first on-line run with a SiC target a suppression of surface-ionized Na contaminants in the ion beam of up to six orders of magnitude was demonstrated. PMID:24689577

Raeder, Sebastian; Heggen, Henning; Lassen, Jens; Ames, Friedhelm; Bishop, Daryl; Bricault, Pierre; Kunz, Peter; Mjøs, Anders; Teigelhöfer, Andrea

2014-03-01

210

Distinguishing isobaric phosphated and sulfated carbohydrates by coupling of mass spectrometry with gas phase vibrational spectroscopy.  

PubMed

An original application of the coupling of mass spectrometry with vibrational spectroscopy, used for the first time to discriminate isobaric bioactive saccharides with sulfate and phosphate functional modifications, is presented. Whereas their nominal masses and fragmentation patterns are undifferentiated by sole mass spectrometry, their distinctive OH stretching modes at 3595 cm(-1) and 3666 cm(-1), respectively, provide a reliable spectroscopic diagnostic for distinguishing their sulfate or phosphate functionalization. A detailed analysis of the 6-sulfated and 6-phosphated d-glucosamine conformations is presented, together with theoretical scaled harmonic spectra and anharmonic spectra (VPT2 and DFT-based molecular dynamics simulations). Strong anharmonic effects are observed in the case of the phosphated species, resulting in a dramatic enhancement of its phosphate diagnostic mode. PMID:25211353

Schindler, Baptiste; Joshi, Janhavi; Allouche, Abdul-Rahman; Simon, Daniel; Chambert, Stéphane; Brites, Vincent; Gaigeot, Marie-Pierre; Compagnon, Isabelle

2014-10-28

211

Weather maps classification over Greek domain based on isobaric line patterns. A pattern recognition approach  

NASA Astrophysics Data System (ADS)

The paper presents a semi-supervised weather classification method based on 850-hPa isobaric level maps. A preprocessing step is employed, where isolines of geopotential height are extracted from weather map images via an image processing procedure. ? feature extraction stage follows where two techniques are applied. The first technique implements phase space reconstruction, and yields multidimensional delay distributions. The second technique is based on chain code representation of signals, from which histogram features are derived. Similarity measures are used to compare multidimensional data and the k-means algorithm is applied in the final stage. The method is applied over the area of Greece, and the resulting catalogues are compared to a subjective classification for this area. Numerical experiments with datasets derived from the European Meteorological Bulletin archives exhibit an up to 91 % accurate agreement with the subjective weather patterns.

Zagouras, Athanassios; Argiriou, Athanassios A.; Economou, George; Fotopoulos, Spiros; Flocas, Helena A.

2013-11-01

212

Ultrahigh-temperature metamorphism under isobaric heating: New evidence from the North China Craton  

NASA Astrophysics Data System (ADS)

The Khondalite Belt within Inner Mongolia Suture Zone (IMSZ) in the North China Craton (NCC) preserves evidence for extreme crustal metamorphism under ultra-high temperature (UHT) conditions at ca. 1.92 Ga, associated with the subduction-collision tectonics between the Yinshan and Ordos Blocks. Here we report a new locality in Hongsigou where cordierite- and spinel-bearing granulites record UHT metamorphism. The prograde, peak, and retrograde mineral assemblages in these pelitic granulites have been identified based on petrography and mineral chemistry as: Bt1 + Grt1 + Sil1 + Kfs1 + Pl1 + Ilm + Qtz1, Grt1 + Sil2 + Kfs2 + Pl2 + Spl + Ilm + Qtz2 + Liq, and Crd + Grt2 + Sil3 + Kfs2 + Pl2 + Ilm + Qtz2 respectively. The peak metamorphic conditions of the pelitic granulite were estimated as 930-1050 °C and 6.5-7.5 kbar based on pseudosection analysis in the system NCKFMASHTO, suggesting extreme thermal metamorphism. We report LA-ICPMS zircon U-Pb data from the granulite which show weighted mean 207Pb/206Pb age of 1881 ± 6.6 Ma, marking the timing of UHT metamorphism. Lu-Hf analyses of the zircons show ?Hf(t) values within a restricted range of -4.2 to 0.3 and together with Hf model ages, a Paleoproterozoic arc magmatic source is inferred for the detrital zircons. The estimated P-T path for the UHT granulite suggests isobaric heating followed by cooling and decompression along a clockwise trajectory, different from the anti-clockwise P-T paths defined in earlier studies for the 1.92 Ga UHT rocks from the IMSZ. The younger age and the isobaric heating trajectory suggest that the Hongsigou UHT rocks are related to heat input from underplated mafic magmas following continental collision.

Yang, Qiong-Yan; Santosh, M.; Tsunogae, Toshiaki

2014-12-01

213

Isobaric yield ratio difference in heavy-ion collisions, and comparison to isoscaling  

NASA Astrophysics Data System (ADS)

An isobaric yield ratio difference (IBD) method is proposed to study the ratio of the difference between the chemical potential of neutron and proton to temperature (??/T) in heavy-ion collisions. The ??/T determined by the IBD method (IB-??/T) is compared to the results of the isoscaling method (IS-??/T), which uses the isotopic or the isotonic yield ratio. Similar distributions of the IB- and IS-??/T are found in the measured 140A MeV 40,48Ca+9Be and the 58,64Ni+9Be reactions. The IB- and IS-??/T both have a distribution with a plateau in the small mass fragments plus an increasing part in the fragments of relatively larger mass. The IB- and IS-??/T plateaus show dependence on the n/p ratio of the projectile. It is suggested that the height of the plateau is decided by the difference between the neutron density (?n) and the proton density (?p) distributions of the projectiles, and the width shows the overlapping volume of the projectiles in which ?n and ?p change very little. The difference between the IB- and IS-??/T is explained by the isoscaling parameters being constrained by the many isotopes and isotones, while the IBD method only uses the yields of two isobars. It is suggested that the IB-??/T is more reasonable than the IS-??/T, especially when the isotopic or isotonic ratio disobeys the isoscaling. As to the question whether the ??/T depends on the density or the temperature, the density dependence is preferred since the low density can result in low temperature in the peripheral reactions.

Ma, Chun-Wang; Wang, Shan-Shan; Zhang, Yan-Li; Wei, Hui-Ling

2013-03-01

214

Equilibrium games in networks  

NASA Astrophysics Data System (ADS)

It seems a universal phenomenon of networks that the attacks on a small number of nodes by an adversary player Alice may generate a global cascading failure of the networks. It has been shown (Li et al., 2013) that classic scale-free networks (Barabási and Albert, 1999, Barabási, 2009) are insecure against attacks of as small as O(logn) many nodes. This poses a natural and fundamental question: Can we introduce a second player Bob to prevent Alice from global cascading failure of the networks? We proposed a game in networks. We say that a network has an equilibrium game if the second player Bob has a strategy to balance the cascading influence of attacks by the adversary player Alice. It was shown that networks of the preferential attachment model (Barabási and Albert, 1999) fail to have equilibrium games, that random graphs of the Erdös-Rényi model (Erdös and Rényi, 1959, Erdös and Rényi, 1960) have, for which randomness is the mechanism, and that homophyly networks (Li et al., 2013) have equilibrium games, for which homophyly and preferential attachment are the underlying mechanisms. We found that some real networks have equilibrium games, but most real networks fail to have. We anticipate that our results lead to an interesting new direction of network theory, that is, equilibrium games in networks.

Li, Angsheng; Zhang, Xiaohui; Pan, Yicheng; Peng, Pan

2014-12-01

215

Quasi-Equilibrium Nonadditivity  

NASA Astrophysics Data System (ADS)

The possibility that a short-range interacting system exhibits nonadditivity is investigated. After the discussion on the precise definition of additivity and its consequence, we show that it is possible when the system is in a quasi-equilibrium state by examining the specific model, in which the spin degrees of freedom are coupled to the motional degrees of freedom and which exhibits a type of structural phase transitions. In this model, the interactions are local but the system evolves under the global constraint, i.e., the triangular lattice structure, which effectively plays the role of long-range interactions and causes the nonadditivity. The triangular lattice structure is just a metastable structure, and hence this nonadditivity is not an equilibrium property but a property in a quasi-equilibrium state.

Mori, Takashi

2015-04-01

216

Lecture Ch. 4a Equilibrium  

E-print Network

· Chemical equilibrium Chemical Equilibrium · Two phases in equilibrium ­ Constant T, P · Phase changes1 Lecture Ch. 4a · Equilibrium · Phase changes · Enthalpy changes from phase changes ­ Latent heat with more than one chemical component, there are more than 2 independent variables; if more than one phase

Russell, Lynn

217

ELLIOTT SOBER EQUILIBRIUM EXPLANATION*  

E-print Network

and the actual selective forces don't matter; whatever the actual initial sex ratio had been, the selection. It asserts that if any force appreciably in- fluences the sex ratio it will be selection for individuals (or. R.A. Fisher (1931) formulated an equilibrium explanation of the fact that the sex ratio

Fitelson, Branden

218

Equilibrium Chemical Engines  

E-print Network

An equilibrium reversible cycle with a certain engine to transduce the energy of any chemical reaction into mechanical energy is proposed. The efficiency for chemical energy transduction is also defined so as to be compared with Carnot efficiency. Relevance to the study of protein motors is discussed. KEYWORDS: Chemical thermodynamics, Engine, Efficiency, Molecular machine.

Tatsuo Shibata; Shin-ichi Sasa

1997-10-30

219

PLASMA EQUILIBRIUM IN TOKAMAKS  

Microsoft Academic Search

This lecture treats the magnetohydrodynamic (MHD) equi- librium of axisymmetric plasmas, as given by the Grad- Shafranov equation. In a brief introduction, equilibrium pa- rameters such as the q-profile, the internal inductance, and the poloidal beta are introduced. The properties of these quantities will be illustrated in the case of the tokamak, by applying the large aspect ratio tokamak approximation.

H. J. de Blank

2006-01-01

220

Structure, thermodynamics, and liquid-vapor equilibrium of ethanol from molecular-dynamics simulations using nonadditive interactions  

NASA Astrophysics Data System (ADS)

We present a molecular-dynamics simulation study of the bulk and liquid-vapor interfacial properties of ethanol using a polarizable force field based on the fluctuating charge (FQ) formalism, as well as the nonpolarizable CHARMM22 force field. Both models are competitive with respect to the prediction of ambient liquid properties such as liquid density, enthalpy of vaporization, dielectric constant, and self-diffusion constants. The polarizable model predicts an average condensed-phase dipole moment of 2.2D associated with an induced liquid-phase dipole moment of 0.6D; though qualitatively in agreement with earlier nonadditive models as well as recent Car-Parinello calculations, the current FQ model underestimates the condensed-phase dipole moment. In terms of liquid structure, both models are in agreement with recent neutron-diffraction results of liquid ethanol structure, although the polarizable model predicts the hydroxyl-hydrogen-hydroxyl-hydrogen structure factor in closer agreement with the experimental data. In terms of interfacial properties, both models predict ambient surface tension to within 4% of the experimental value of 22.8dyn/cm, while overestimating the surface excess entropy by almost a factor of 2. Both models display the characteristic preferential orientation of interfacial molecules. The polarizable model allows for a monotonic variation of the average molecular dipole moment from the bulk value to that of the vapor phase. Consequently, there is a dramatic difference in the surface potential predicted by the polarizable and nonpolarizable models. The polarizable model estimates a surface potential of -209±3mV, while the nonpolarizable model yields a value of -944±10mV. Finally, based on the vapor-liquid equilibrium simulation data from several temperatures, we estimate the critical properties of both models. As observed with other FQ models for associating fluids (such as water and methanol), and counter to what one would anticipate by modeling more physically the electrostatic response to local environment, the current FQ model underestimates the critical temperature and overestimates the critical density of ethanol; moreover, the FQ model is, in this respect, equivalent to the underlying fixed-charge model. These results further suggest the need to revisit polarizable models in terms of quantitative vapor-liquid equilibrium prediction.

Patel, Sandeep; Brooks, Charles L.

2005-10-01

221

Capillary electrophoresis-mass spectrometry determination of morphine and its isobaric glucuronide metabolites.  

PubMed

The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug monitoring and forensic identification of drug use. In particular, capillary electrophoresis with mass spectrometry (CE-MS) represents an attractive tool for opioid analysis. Whereas volatile background electrolytes in CE often improve electrospray ionization for coupled MS detection, such electrolytes may reduce CE separation efficiency and resolution. To better understand the effects of background electrolyte (BGE) composition on separation efficiency and detection sensitivity, this work compares and contrasts method development for both volatile (ammonium formate and acetate) and nonvolatile (ammonium phosphate and borate) buffers. Peak efficiencies and migration times for morphine and morphine metabolites were optimal with a 25mM ammonium borate buffer (pH=9.5) although greater sensitivities were achieved in the ammonium formate buffer. Optimized CE methods allowed for the resolution of the isobaric morphine metabolites prior to high mass accuracy, electrospray ionization quadrupole time-of-flight (ESI-QTOF) MS detection applicable to the analysis of urine samples in under seven minutes. Urine sample preparation required only a 10-fold dilution with BGE prior to analysis. Limits of detection (LOD) in normal human urine were found to be 1.0?g/mL for morphine and 2.5?g/mL for each of M3G and M6G by CE-ESI-QTOF-MS. These LODs were comparable to those for CE-UV analysis of opioid standards in buffer, whereas CE-ESI-QTOF-MS analysis of opioid standards in buffer yielded LODs an order of magnitude lower. Patient urine samples (N=12) were analyzed by this new CE-ESI-QTOF-MS method and no significant difference in total morphine content relative to prior liquid chromatography-mass spectrometry (LC-MS) results was found as per a paired-t test at the 99% confidence level. Whereas the LC-MS method applied to these samples determined only total morphine content, this new CE-ESI-QTOF-MS method allowed for species differentiation in addition to total morphine determination. By this method, it was found that M3G and M6G metabolites were present in a 5:1 concentration ratio, on average, in patient samples. Therefore, the CE-ESI-QTOF-MS method not only allows for total morphine concentration determination comparable to established LC-MS methods, but also allows for differentiation between morphine and its trace glucuronides, yielding additional biochemical information about drug metabolism. PMID:25589256

Isbell, Theresa A; Strickland, Erin C; Hitchcock, Jennifer; McIntire, Gregory; Colyer, Christa L

2015-02-01

222

Isobar suppression for measurement of silicon-32 by accelerator mass spectrometry at low energy  

NASA Astrophysics Data System (ADS)

Development of a method to suppress the isobaric interference, 32S, for the purpose of measuring 32Si by Accelerator Mass Spectrometry (AMS) at low energy was undertaken. The differential energy loss of the ions when transmitted through a thin carbon foil was the basis of the isobaric suppression. A new silica reduction technique was developed for the purpose of increasing ion source output for silicon samples. The energy loss and energy straggle of the transmitted ions, the charge state distributions, and beamline transmission were measured for the stable isotopes of silicon and 32S for the development of the method. The data are compared to the predictions that were made for the ion beam energy loss and energy straggle using the Monte Carlo simulation program TRIM. The charge state distribution data are compared to predictions made using empirical formulas developed by Chaki and Elmore in 1980. The negative silicon ion beam source output for chemically prepared Mg 2Si samples was increased from approximately 10 nA to approximately 15 ?A. This was an increase of a factor of approximately 103 over naturally occurring SiO2 samples. The observed energy loss profiles of the silicon and sulfur ions through carbon foils of 50-?g/cm2, 75-?g/cm2, and 100-?g/cm2 are in good agreement with the predicted values, with absolute percent error results ranging from 0.1% to 2.5%. The measured energy straggling for the silicon and sulfur ions in the thin carbon foils ranged from approximately 150 keV to 450 keV. This is much larger than the values of 21 keV to 30 keV that were predicted using simulations from the TRIM code. The measured charge state distributions were in very good agreement with the predicted distributions for silicon and sulfur. The overall system ion beam transmission efficiency was 0.2% for the transmission to the spectrograph, and 0.02% to the silicon surface barrier detector in the spectrograph. The results indicate that enacting the differential energy loss for the silicon- sulfur pair suppressed the sulfur interference by a factor of 106 relative to the silicon count rate.

Treacy, Donald John, Jr.

2000-10-01

223

Temperature lapse rates at restricted thermodynamic equilibrium in the Earth system  

NASA Astrophysics Data System (ADS)

Equilibrium temperature profiles obtained by maximizing the entropy of a column of fluid with a given height and volume under the influence of gravity are discussed by using numerical experiments. Calculations are made both for the case of an ideal gas and for a liquid with constant isobaric heat capacity, constant compressibility and constant thermal expansion coefficient representing idealized conditions corresponding to atmosphere and ocean. Calculations confirm the classical equilibrium condition by Gibbs that an isothermal temperature profile gives a maximum in entropy constrained by a constant mass and a constant sum of internal and potential energy. However, it was also found that an isentropic profile gives a maximum in entropy constrained by a constant mass and a constant internal energy of the fluid column. On the basis of this result a hypothesis is suggested that the adiabatic lapse rate represents a restricted or transitory and metastable equilibrium state, which has a maximum in entropy with lower value than the maximum in the state with an isothermal lapse rate. This transitory equilibrium state is maintained by passive forces, preventing or slowing down the transition of the system to the final or ultimate equilibrium state.

Björnbom, Pehr

2015-03-01

224

Confinement of Equilibrium Polymers  

NASA Astrophysics Data System (ADS)

We consider supramolecular polymer systems in which reversible intermolecular bonding affects the thermodynamics of the system. While we have formulated models for a number of such systems, this presentation focuses on equilibrium polymers in which monomers can reversibly link together to form linear polymers. This serves as a model for giant micelles of surfactant molecules that can break and recombine at any point along the cylindrical micelle. While equilibrium polymers in bulk environments have been studied, we investigate their behavior in confined environments such as between two parallel plates. Our model features a continuous distribution of polymer lengths and assumes a favorable energy decrease when two monomers form a bond. We are interested in how confinement affects the density profile and the polymer length distribution, and we calculate these properties analytically using the ground state dominance approximation and computationally employing self-consistent field theory.

Feng, Edward

2005-03-01

225

Covariant Equilibrium Statistical Mechanics  

E-print Network

A manifest covariant equilibrium statistical mechanics is constructed starting with a 8N dimensional extended phase space which is reduced to the 6N physical degrees of freedom using the Poincare-invariant constrained Hamiltonian dynamics describing the micro-dynamics of the system. The reduction of the extended phase space is initiated forcing the particles on energy shell and fixing their individual time coordinates with help of invariant time constraints. The Liouville equation and the equilibrium condition are formulated in respect to the scalar global evolution parameter which is introduced by the time fixation conditions. The applicability of the developed approach is shown for both, the perfect gas as well as the real gas. As a simple application the canonical partition integral of the monatomic perfect gas is calculated and compared with other approaches. Furthermore, thermodynamical quantities are derived. All considerations are shrinked on the classical Boltzmann gas composed of massive particles and hence quantum effects are discarded.

E. Lehmann

2006-02-25

226

Absolute Equilibrium Entropy  

NASA Technical Reports Server (NTRS)

The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

Shebalin, John V.

1997-01-01

227

Equilibrium electroconvective instability.  

PubMed

Since its prediction 15 years ago, hydrodynamic instability in concentration polarization at a charge-selective interface has been attributed to nonequilibrium electro-osmosis related to the extended space charge which develops at the limiting current. This attribution had a double basis. On the one hand, it has been recognized that neither equilibrium electro-osmosis nor bulk electroconvection can yield instability for a perfectly charge-selective solid. On the other hand, it has been shown that nonequilibrium electro-osmosis can. The first theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge selectivity for the sake of simplicity and so did the subsequent studies of various time-dependent and nonlinear features of electro-osmotic instability. In this Letter, we show that relaxing the assumption of perfect charge selectivity (tantamount to fixing the electrochemical potential of counterions in the solid) allows for the equilibrium electroconvective instability. In addition, we suggest a simple experimental test for determining the true, either equilibrium or nonequilibrium, origin of instability in concentration polarization. PMID:25839276

Rubinstein, I; Zaltzman, B

2015-03-20

228

Equilibrium Structure of Piperidine  

NASA Astrophysics Data System (ADS)

In order to determine an accurate equilibrium structure for the equatorial form of piperidine, C_ 5H11N, microwave transitions and ground state rotational constants are reported for the 13C and 15N isotopologues measured in natural abundance. These rotational constants along with those of the parent and ND species were used together with vibration-rotation constants obtained from a cubic force fields calculated at the B3LYP/cc-pVTZ and MP2/cc-pVTZ levels of theory to derive a semiexperimental (SE) equilibrium structure. However, the rotational constants of the CD deuterated species are not available, and there are many small Cartesian coordinates. Furthermore, piperidine is an oblate top. Quite generally, there is a large rotation of the principal axis system upon isotopic substitution in oblate tops that may considerably reduce the accuracy of the SE structure. For these reasons, the mixed estimation method was used. In this method, internal coordinates from good-quality quantum chemical calculations (with appropriate uncertainties) are fitted simultaneously with moments of inertia of the full set of isotopologues. In order to have predicates as accurate as possible, the geometry was optimized at the MP2 and CCSD(T) levels of theory using Dunning basis sets up to quadruple-zeta quality. This combination of experimental rotational constants and high-level ab initio calculations allowed us to determine an accurate equilibrium structure.

Demaison, Jean; Rudolph, Heinz Dieter; Craig, Norman C.; Ecija, Patricia; Cocinero, Emilio J.; Lesarri, Alberto

2014-06-01

229

Equilibrium Electroconvective Instability  

NASA Astrophysics Data System (ADS)

Since its prediction 15 years ago, hydrodynamic instability in concentration polarization at a charge-selective interface has been attributed to nonequilibrium electro-osmosis related to the extended space charge which develops at the limiting current. This attribution had a double basis. On the one hand, it has been recognized that neither equilibrium electro-osmosis nor bulk electroconvection can yield instability for a perfectly charge-selective solid. On the other hand, it has been shown that nonequilibrium electro-osmosis can. The first theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge selectivity for the sake of simplicity and so did the subsequent studies of various time-dependent and nonlinear features of electro-osmotic instability. In this Letter, we show that relaxing the assumption of perfect charge selectivity (tantamount to fixing the electrochemical potential of counterions in the solid) allows for the equilibrium electroconvective instability. In addition, we suggest a simple experimental test for determining the true, either equilibrium or nonequilibrium, origin of instability in concentration polarization.

Rubinstein, I.; Zaltzman, B.

2015-03-01

230

Introduction to Carbonate Equilibrium  

NSDL National Science Digital Library

The activity asks students to make observations about what occurs when two effervescent antacid tablets are placed into a beaker of water. The Students work together in groups. There are three parts to the activity. In the first part, the tablets are dropped into tap water and student groups (2-4 students) must complete a series of question sheets (one per group) that guide them through thinking about the event. In the second part, a presentation on chemical equilibrium for the carbonate system is given. The starting point is the answers received in the first part. Basic chemical reactions for the carbonate system are presented including equilibrium expressions for each reaction and discussion about open and closed systems. At the end of class, a handout is given to the students. In the third part, three beakers (acidic, neutral and basic solutions, but not indicated) are placed together and two tablets are placed into each beaker. Students are split into two groups (8-12 students) and are asked to describe why the reactions are different. Discussion follows collection of student responses in each part. Once the chemical reactions and equilibrium expressions are presented, they are involved and referenced in all discussions.

michael stapleton

231

Gas-phase ion-molecule reactions for resolution of atomic isobars: AMS and ICP-MS perspectives  

NASA Astrophysics Data System (ADS)

Ion-molecule reactions that can be used for resolution of spectral overlaps of long-lived or stable (T1/2 > 100 years) atomic isobars on the long-lived radio-isotopes (100 < T1/2 < 1012 years) in mass spectrometry are considered. Results for the separations of isobaric overlaps via cation reactions with NO, N2O, O2, CO2, C2H2, CH3F studied with the Inductively Coupled Plasma Dynamic Reaction Cell(TM) Mass Spectrometer (ICP-DRC(TM)-MS) with use of stable isotopes are presented. Overview of potential and reported reactions for separation of 35 isobars is given. Potential for the following isobaric pairs separation is shown (reaction gas and the extent of separation achieved to date in parenthesis): 32Si+/32S+(NO, 5 x 104), 40K+/40Ar+(N2O, 1.9 x 103), 40K+/40Ca+(N2O, 50), 59Ni+/59Co+(N2O, 6), 79Se+/79Br+(O2, 7.2 x 103), 81Kr+/81Br+(C2H2, 1.5 x 104), 93Mo+/93Nb+(N2O, 100), 93Mo+/93Zr+(N2O, 150), 135Cs+/135Ba+(N2O, 8 x 104), 137,138La+/137,138Ba+(O2, 40), 146Sm+/146Nd+(CO2, 1.5 x 105), 176Lu+/176Hf+(NO, 2.8 x 103), 187Re+/187Os+(N2O, 2.8 x 104). Effect of instrumental parameters on reactivity is discussed. The relevance of this work to accelerator mass spectrometry is discussed briefly.

Bandura, Dmitry R.; Baranov, Vladimir I.; Litherland, A. E.; Tanner, Scott D.

2006-09-01

232

Extraction of the symmetry energy coefficients from the masses differences of isobaric nuclei  

E-print Network

The nuclear symmetry energy coefficients of finite nuclei are extracted by using the differences between the masses of isobaric nuclei. Based on the masses of more than 2400 nuclei with $A=9-270$, we investigate the model dependence in the extraction of symmetry energy coefficient. We find that the extraction of the symmetry energy coefficients is strongly correlated with the forms of the Coulomb energy and the mass dependence of the symmetry energy coefficient adopted. The values of the extracted symmetry energy coefficients increase by about 2 MeV for heavy nuclei when the Coulomb correction term is involved. We obtain the bulk symmetry energy coefficient $S_0=28.26\\pm1.3$ MeV and the surface-to-volume ratio $\\kappa=1.26\\pm 0.25 $ MeV if assuming the mass dependence of symmetry energy coefficient $a_{\\rm sym}(A)=S_0(1-\\kappa/A^{1/3})$, and $S_0=32.80\\pm1.7$ MeV, $\\kappa=2.82\\pm0.57$ MeV when $a_{\\rm sym}(A)=S_0 (1+\\kappa/A^{1/3})^{-1}$ is adopted.

Junlong Tian; Haitao Cui; Kuankuan Zheng; Ning Wang

2014-03-28

233

Combining Amine Metabolomics and Quantitative Proteomics of Cancer Cells Using Derivatization with Isobaric Tags  

PubMed Central

Quantitative metabolomics and proteomics technologies are powerful approaches to explore cellular metabolic regulation. Unfortunately, combining the two technologies typically requires different LC-MS setups for sensitive measurement of metabolites and peptides. One approach to enhance the analysis of certain classes of metabolites is by derivatization with various types of tags to increase ionization and chromatographic efficiency. We demonstrate here that derivatization of amine metabolites with tandem mass tags (TMT), typically used in multiplexed peptide quantitation, facilitates amino acid analysis by standard nanoflow reversed-phase LC-MS setups used for proteomics. We demonstrate that this approach offers the potential to perform experiments at the MS1-level using duplex tags or at the MS2-level using novel 10-plex reporter ion-containing isobaric tags for multiplexed amine metabolite analysis. We also demonstrate absolute quantitative measurements of amino acids conducted in parallel with multiplexed quantitative proteomics, using similar LC-MS setups to explore cellular amino acid regulation. We further show that the approach can also be used to determine intracellular metabolic labeling of amino acids from glucose carbons. PMID:24611633

2015-01-01

234

Differentiating Isobaric Steroid Hormone Metabolites Using Multi-Stage Tandem Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Steroid hormones and their metabolites are currently undergoing clinical trials as potential therapeutics for traumatic brain injury (TBI). To support this work, it is necessary to develop improved procedures for differentiating isobaric species in this compound class. Equilin sulfate (E-S), estrone sulfate (E1-S), 17?-dihydroequilin sulfate (ADHE-S), and 17?-dihydroequilin sulfate (BDHE-S) are primary constituents in hormone replacement therapies, such as Premarin, which are among pharmaceuticals being investigated for TBI treatment. The latter three compounds are isomers and can be difficult to differentiate in trace analytical determinations. In this work, a systematic study of the fragmentation of ADHE-S, BDHE-S, E1-S, and E-S under different stages of higher order tandem mass spectrometry (MSn) and variation of collision energy, allowed optimization of conditions for distinguishing the isomeric structures. For epimeric variants (e.g., ADHE-S versus BDHE-S; ?- versus ?-stereoisomerization in the C-17 position), differentiation was achieved at MS4 and fragmentation was demonstrated through MS5. Computational analysis was performed to further explore differences in the fragmentation pathways due to changes in stereochemistry.

Tedmon, Lauren; Barnes, Jeremy S.; Nguyen, Hien P.; Schug, Kevin A.

2013-03-01

235

Facilitation of gastric compliance and cardiovascular reaction by repeated isobaric distension of the rat stomach  

PubMed Central

Gastric distension causes cardiovascular reactions and enhances gastric compliance. Here we investigated how these responses are related to each other, whether they change upon repeated distension and which neural mechanisms are involved. Mean arterial blood pressure (MAP) in phenobarbital-anaesthetized rats was recorded from a carotid artery and gastric compliance determined with an electronic barostat. Runs of intermittent gastric distension were generated by stepwise increments (5 mm Hg) of intragastric pressure. While gastric compliance peaked at intragastric pressures of 20 mm Hg, the change in MAP (predominantly hypotension) was largest at intragastric pressures beyond 30 mm Hg. Repeated distension enhanced the MAP response to intragastric pressures beyond 35 mm Hg, whereas gastric compliance was facilitated primarily at intragastric pressures below 20 mm Hg. This facilitation of gastric compliance depended on the magnitude of the preceding distension. The MAP response to distension was enhanced by nitric oxide synthase inhibition, inhibited by subdiaphragmatic vagotomy but hardly affected by coeliac ganglionectomy. The facilitation of gastric compliance was changed by vagotomy in a complex manner but left unaltered by the other interventions. These findings show that isobaric gastric distension elicits both MAP and gastric compliance responses whose characteristics, mechanisms and sensitization properties differ profoundly. PMID:15916627

Römer, Markus; Painsipp, Evelin; Schwetz, Ines; Holzer, Peter

2015-01-01

236

ChemTeacher: Equilibrium Constant  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Equilibrium Constant page includes resources for teaching students about defining and using equilibrium constants.

2012-07-24

237

The isochoric, isobaric and saturation-heat capacities of the Lennard-Jones fluid from equations of state and Monte Carlo simulations  

Microsoft Academic Search

Isochoric-, isobaric- and saturation-heat capacities are calculated from the modified Benedict-Webb-Rubin type equation of state (EOS) of Johnson et al. (1993) and from the van der Waals theory based EOS given by Mecke et al. (1995) for the Lennard-Jones fluid. The isochoric- and isobaric-heat capacities are also determined from NVT and NpT ensemble Monte Carlo simulations. A method is proposed

Dezsö Boda; Tamás Lukács; János Liszi; István Szalai

1996-01-01

238

Structural design using equilibrium programming  

NASA Technical Reports Server (NTRS)

Multiple nonlinear programming methods are combined in the method of equilibrium programming. Equilibrium programming theory has been appied to problems in operations research, and in the present study it is investigated as a framework to solve structural design problems. Several existing formal methods for structural optimization are shown to actually be equilibrium programming methods. Additionally, the equilibrium programming framework is utilized to develop a new structural design method. Selected computational results are presented to demonstrate the methods.

Scotti, Stephen J.

1992-01-01

239

Hardy-Weinberg Equilibrium Diagnostics  

Microsoft Academic Search

We propose two diagnostics for the statistical assessment of Hardy–Weinberg equilibrium. One diagnostic is the posterior probability of the complement of the smallest highest posterior density credible region that includes points in the parameter space consistent with the hypothesis of equilibrium. The null hypothesis of equilibrium is to be rejected if this probability is less than a pre-selected critical level.

André Rogatko; Michael J. Slifker; James S. Babb

2002-01-01

240

NON-EQUILIBRIUM THERMODYNAMIC PROCESSES: SPACE PLASMAS AND THE INNER HELIOSHEATH  

SciTech Connect

Recently, empirical kappa distribution, commonly used to describe non-equilibrium systems like space plasmas, has been connected with non-extensive statistical mechanics. Here we show how a consistent definition of the temperature and pressure is developed for stationary states out of thermal equilibrium, so that the familiar ideal gas state equation still holds. In addition to the classical triplet of temperature, pressure, and density, this generalization requires the kappa index as a fourth independent thermodynamic variable that characterizes the non-equilibrium stationary states. All four of these thermodynamic variables have key roles in describing the governing thermodynamical processes and transitions in space plasmas. We introduce a novel characterization of isothermal and isobaric processes that describe a system's transition into different stationary states by varying the kappa index. In addition, we show how the variation of temperature or/and pressure can occur through an 'iso-q' process, in which the system remains in a fixed stationary state (fixed kappa index). These processes have been detected in the proton plasma in the inner heliosheath via specialized data analysis of energetic neutral atom (ENA) observations from Interstellar Boundary Explorer. In particular, we find that the temperature is highly correlated with (1) kappa, asymptotically related to isothermal ({approx}1,000,000 K) and iso-q ({kappa} {approx} 1.7) processes; and (2) density, related to an isobaric process, which separates the 'Ribbon', P Almost-Equal-To 3.2 pdyn cm{sup -2}, from the globally distributed ENA flux, P Almost-Equal-To 2 pdyn cm{sup -2}.

Livadiotis, G.; McComas, D. J., E-mail: glivadiotis@swri.edu [Southwest Research Institute, San Antonio, TX (United States)

2012-04-10

241

Spreading widths of isobaric analog states and the isovector giant monopole resonance  

NASA Astrophysics Data System (ADS)

A global analysis of the experimental spreading widths ? ? of 65 isobaric analog states (IAS) in the range A = 110 to 238 has been performed assuming isospin mixing via the Coulomb force with T< = T0-1 doorway states mediated by coupling to the ( T0-1)-component of the giant isovector monopole resonance (IVM). Excellent agreement has been achieved over the entire range, thus establishing general smooth trends for the parameters describing the resonance. The excitation energy of the resonance, E( IVM)?V 0/A {1}/{3}-(T 0+1)V 1/A was found to reproduce the IAS data with V0 in the range 155 to 170 MeV and V1?55 MeV. These values are taken from recent theoretical estimates of Auerbach and the extreme hydrodynamical estimate of Bohr, Damgaard and Mottelson. The charge-dependent matrix elements were found factors of two to three stronger than hydrodynamic or microscopic estimates, but in almost perfect agreement with an expression based on sum rules derived by Lane and Mekjian. A strength-function approach developed by MacDonald and Birse for the damping widths of isovector monopole resonances was successfully employed. However, it became necessary to introduce an explicit dependence on nuclear deformation to describe a splitting of the IVM strength due to coupling to the ?-vibration component of the isovector quadrupole resonance (IVQ). The postulated ?-dependence describes the strong increase with neutron excess of the spreading widths for several rare-earth nuclei, and an essentially one-parameter fit to all experimental spreading widths gives ? 2/? ? 1.2 . It is further concluded that the density of doorway states which are responsible for the isospin mixing is much lower than the density of all underlying states of lower isospin with the same spin and parity as the IAS, and the ratio decreases exponentially with increasing excitation energy.

Jänecke, J.; Harakeh, M. N.; van der Werf, S. Y.

1987-02-01

242

Statistical physics ""Beyond equilibrium  

SciTech Connect

The scientific challenges of the 21st century will increasingly involve competing interactions, geometric frustration, spatial and temporal intrinsic inhomogeneity, nanoscale structures, and interactions spanning many scales. We will focus on a broad class of emerging problems that will require new tools in non-equilibrium statistical physics and that will find application in new material functionality, in predicting complex spatial dynamics, and in understanding novel states of matter. Our work will encompass materials under extreme conditions involving elastic/plastic deformation, competing interactions, intrinsic inhomogeneity, frustration in condensed matter systems, scaling phenomena in disordered materials from glasses to granular matter, quantum chemistry applied to nano-scale materials, soft-matter materials, and spatio-temporal properties of both ordinary and complex fluids.

Ecke, Robert E [Los Alamos National Laboratory

2009-01-01

243

Phase equilibrium data for development of correlations for coal fluids  

SciTech Connect

The overall objective of the authors' work is to develop accurate predictive methods for representations of vapor-liquid equilibria in systems encountered in coal-conversion processes. The objectives pursued in the present project include: (1) Measurements of binary vapor-liquid phase behavior data for selected solute gases (e.g., C{sub 2}H{sub 6}, CH{sub 4}) in a series of paraffinic, naphthenic, and aromatic hydrocarbon solvents to permit evaluations of interaction parameters in models for phase behavior. Solubilities of the gases in the liquid phase have been determined. (2) Evaluation of existing equations of state and other models for representations of phase behavior in systems of the type studied experimentally; development of new correlation frameworks as needed. (3) Generalization of the interaction parameters for the solutes studied to a wide spectrum of heavy solvents; presentation of final results in formats useful in the design/optimization of coal liquefaction processes.

Robinson, R.L. Jr.; Gasem, K.A.M.; Darwish, N.A.; Raff, A.M.

1991-02-01

244

General Equilibrium Simulation for Microeconomics  

NSDL National Science Digital Library

Teaching general equilibrium analysis to students is challenging. General equilibrium models are typically accessible to only a small handful of mathematically well prepared students. Yet the growing significance of general equilibrium models in economics challenges instructors to find ways to make these models accessible to undergraduate students. The simulation gives microeconomics instructors an alternative to the traditional Edgeworth box graphical presentation. The simulation, with sample parameter files, is implemented with a Java applet available at General Equilibrium Simulations. The developers of the simulation are Walter Nicholson and Frank Westhoff at Amherst College.

Betty Blecha

245

Reply to ``Comment on `Correlations between isobaric and isochoric fragilities and thermodynamical scaling exponent for glass-forming liquids' ''  

NASA Astrophysics Data System (ADS)

Our recent paper [A. Grzybowski, K. Grzybowska, J. Zio?o, and M. Paluch, Phys. Rev. E 74, 041503 (2006)] tested the correlations between isobaric and isochoric fragilities, mP and mV , as well as the scaling exponent ? under elevated pressure conditions. The preceding paper [R. Casalini and C. M. Roland, Phys. Rev. E 76, 013501 (2007)] is a Comment by the authors of the correlations originally determined for atmospheric pressure. In this Reply we present our point of view on criticisms contained in the Comment. We clarify and maintain our previously drawn conclusions.

Grzybowski, A.; Grzybowska, K.; Zio?o, J.; Paluch, M.

2007-07-01

246

The Isospin Admixture of The Ground State and The Properties of The Isobar Analog Resonances In Deformed Nuclei  

SciTech Connect

Within quasiparticle random phase approximation (QRPA), Pyatov-Salamov method for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state are investigated by including the pairing correlations between nucleons for {sup 72-80}Kr isotopes. Our results are compared with the spherical case and with other theoretical results.

Aygor, H. Ali; Maras, Ismail [Celal Bayar University, Department of Physics, Manisa (Turkey); Cakmak, Necla; Selam, Cevad [Anadolu University, Department of Physics, Eskisehir (Turkey)

2008-11-11

247

Misleading measures in Vitamin D analysis: A novel LC-MS/MS assay to account for epimers and isobars  

PubMed Central

Background Recently, the accuracies of many commercially available immunoassays for Vitamin D have been questioned. Liquid chromatography tandem mass spectrometry (LC- MS/MS) has been shown to facilitate accurate separation and quantification of the major circulating metabolite 25-hydroxyvitamin-D3 (25OHD3) and 25-hydroxyvitamin-D2 (25OHD2) collectively termed as 25OHD. However, among other interferents, this method may be compromised by overlapping peaks and identical masses of epimers and isobars, resulting in inaccuracies in circulating 25OHD measurements. The aim of this study was to develop a novel LC-MS/MS method that can accurately identify and quantitate 25OHD3 and 25OHD2 through chromatographic separation of 25OHD from its epimers and isobars. Methods A positive ion electrospray ionisation (ESI) LC-MS/MS method was used in the Multiple Reaction Monitoring (MRM) mode for quantification. It involved i) liquid-liquid extraction, ii) tandem columns (a high resolution ZORBAX C18 coupled to an ULTRON chiral, with guard column and inlet filter), iii) Stanozolol-D3 as internal standard, and iv) identification via ESI and monitoring of three fragmentation transitions. To demonstrate the practical usefulness of our method, blood samples were collected from 5 healthy male Caucasian volunteers; age range 22 to 37 years and 25OHD2, 25OHD3 along with co-eluting epimers and analogues were quantified. Results The new method allowed chromatographic separation and quantification of 25OHD2, 25OHD3, along with 25OHD3 epimer 3-epi-25OHD3 and isobars 1-?-hydroxyvitamin-D3 (1?OHD3), and 7-?-hydroxy-4-cholesten-3-one (7?C4). The new assay was capable of detecting 0.25 ng/mL of all analytes in serum. Conclusions To our knowledge, this is the first specific, reliable, reproducible and robust LC-MS/MS method developed for the accurate detection of 25OHD (Vitamin D). The method is capable of detecting low levels of 25OHD3 and 25OHD2 together with chromatographic separation from the co-eluting epimers and isobars and circumvents other instrumental/analytical interferences. This analytical method does not require time-consuming derivatisation and complex extraction techniques and could prove very useful in clinical studies. PMID:21569549

2011-01-01

248

Realization of In-Source Collision-Induced Dissociation in Single-Photon Ionization Time-of-Flight Mass Spectrometry and Its Application for Differentiation of Isobaric Compounds.  

PubMed

Single-photon ionization mass spectrometry (SPI-MS) is a versatile and powerful analytical technique for online and real-time analysis of organic species; however, it is confronted with an intrinsic drawback of lacking structural information on the investigated molecules, let alone differentiation of isobaric compounds. In this work, we describe a first attempt to integrate in-source collision-induced dissociation (CID) to the SPI ion source in a SPI-MS instrument. The in-source CID was accomplished by elevating the pressure in the ion source to medium vacuum pressure (MVP) and raising the extraction voltage. With the aid of in-source CID, both the SPI-induced molecular ion and CID-generated fragment ion mass spectra can be obtained to endue each analyte with its unique spectrometric "fingerprint". The capability for differentiation of isobaric compounds is demonstrated by analyzing two groups of isobaric compounds with molecular weights of 72 and 106 Da, respectively, and quantitative analysis of p-xylene and ethylbenzene in gas mixture. As a result, isobaric compounds with different characteristic fragment ions or appearance energies can be successfully distinguished. The work presents a feasible method for practical applications of SPI-MS to differentiate isobaric compounds conveniently and rapidly without MS/MS technique or coupling additional separation technologies. PMID:25594827

Hua, Lei; Hou, Keyong; Chen, Ping; Xie, Yuanyuan; Jiang, Jichun; Wang, Yan; Wang, Weiguo; Li, Haiyang

2015-02-17

249

The Greenhouse Effect Temperature Equilibrium  

E-print Network

The Greenhouse Effect #12;Temperature Equilibrium The Earth is in equilibrium with the Sun temperature is about 14C, or 287K. The 40K difference is due to the greenhouse effect. Essentially all (Wein's Law). Our atmosphere is not completely transparent at these wavelengths, because the greenhouse

Walter, Frederick M.

250

Rapid-Equilibrium Enzyme Kinetics  

ERIC Educational Resources Information Center

Rapid-equilibrium rate equations for enzyme-catalyzed reactions are especially useful because if experimental data can be fit by these simpler rate equations, the Michaelis constants can be interpreted as equilibrium constants. However, for some reactions it is necessary to use the more complicated steady-state rate equations. Thermodynamics is…

Alberty, Robert A.

2008-01-01

251

Equilibrium Versus the Invisible Hand  

Microsoft Academic Search

Twentieth century equilibrium modeling depicts an end state toward which an economy tends, whereas the invisible hand, as Adam Smith depicted it, suggests an economy continually progressing as an increased division of labor is produced by growing markets. Thus, there is an inherent tension between the concepts of an equilibrium outcome versus the invisible hand process. The paper discusses different

Randall G. Holcombe

1999-01-01

252

Equilibrium versus the Invisible Hand  

Microsoft Academic Search

Twentieth century equilibrium modeling depicts an end state toward which an economy tends, whereas the invisible hand, as Adam Smith depicted it, suggests an economy continually progressing as an increased division of labor is produced by growing markets. Thus, there is an inherent tension between the concepts of an equilibrium outcome versus the invisible hand process. The paper discusses different

RANDALL G. HOLCOMBE

1999-01-01

253

Genetic algorithm for mobiles equilibrium  

Microsoft Academic Search

An adaptive algorithm is proposed for controlling mobile users transmitter power and information bit rate cooperatively in CDMA networks. The active component of this scheme is called genetic algorithm for mobiles equilibrium (GAME). Based on an evolutionary computational model, the base station tries to achieve an adequate equilibrium between its users. Thereof, each mobile call send its traffic with a

Mohamed Moustafa; M. Naghshineh

2000-01-01

254

Equilibrium structures in vertical oligopoly  

Microsoft Academic Search

The central purpose of this paper is to examine vertical integration as an equilibrium phenomenon. We model it as integration between Cournot oligopolists in both the upstream and the downstream stages. We consider the issue of private profitability versus collective profitability and show that under several situations the equilibrium outcomes may result in a Prisoner's dilemma. The analysis is extended

Masahiro Abiru; Babu Nahata; Subhashis Raychaudhuri; Michael Waterson

1998-01-01

255

Phosphopeptide quantitation using amine-reactive isobaric tagging reagents and tandem mass spectrometry: application to proteins isolated by gel electrophoresis.  

PubMed

Polyacrylamide gel electrophoresis is widely used for protein separation and it is frequently the final step in protein purification in biochemistry and proteomics. Using a commercially available amine-reactive isobaric tagging reagent (iTRAQ) and mass spectrometry we obtained reproducible, quantitative data from peptides derived by tryptic in-gel digestion of proteins and phosphoproteins. The protocol combines optimized reaction conditions, miniaturized peptide handling techniques and tandem mass spectrometry to quantify low- to sub-picomole amounts of (phospho)proteins that were isolated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immobilized metal affinity chromatography (FeIII-IMAC) was efficient for removal of excess reagents and for enrichment of derivatized phosphopeptides prior to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. Phosphopeptide abundance was determined by liquid chromatography/tandem mass (LC/MS/MS) using either MALDI time-of-flight/time-of-flight (TOF/TOF) MS/MS or electrospray ionization quadrupole time-of-flight (ESI-QTOF) MS/MS instruments. Chemically labeled isobaric phosphopeptides, differing only by the position of the phosphate group, were distinguished and characterized by LC/MS/MS based on their LC elution profile and distinct MS/MS spectra. We expect this quantitative mass spectrometry method to be suitable for systematic, comparative analysis of molecular variants of proteins isolated by gel electrophoresis. PMID:16521170

Sachon, E; Mohammed, S; Bache, N; Jensen, O N

2006-01-01

256

Is Soret equilibrium a non-equilibrium effect?  

NASA Astrophysics Data System (ADS)

Recent thermophoretic experiments on colloidal suspensions revived an old debate, namely whether the Soret effect is properly described by thermostatics, or necessarily requires non-equilibrium thermodynamics. Based on colloidal transport theory and the entropy production of the related viscous flow, our analysis leads to the conclusion that the equilibrium approach may work for small ions, yet fails for colloidal particles and polymers. Regarding binary molecular mixtures, our results shed some doubt on the validity of thermostatic approaches that derive the Soret coefficient from equilibrium potentials.

Würger, Alois

2013-04-01

257

Is Soret equilibrium a non-equilibrium effect?  

E-print Network

Recent thermophoretic experiments on colloidal suspensions revived an old debate, namely whether the Soret effect is properly described by thermostatics, or necessarily requires non-equilibrium thermodynamics. Based on colloidal transport theory and the entropy production of the related viscous flow, our analysis leads to the conclusion that the equilibrium approach may work for small ions, yet fails for colloidal particles and polymers. Regarding binary molecular mixtures, our results shed some doubt on the validity of thermostatic approaches that derive the Soret coefficient from equilibrium potentials.

Alois Würger

2014-01-29

258

Near-equilibrium heliosphere - Far-equilibrium heliosheath  

NASA Astrophysics Data System (ADS)

Space plasmas are systems in stationary states out of thermal equilibrium, and thus, their phase space distributions cannot be analyzed in the framework of classical Statistical Mechanics. Recent advances in theoretical space physics have shown that non-extensive Statistical Mechanics offers a solid statistical foundation for these distributions. The kappa index that governs these distributions is significant for its role in identifying the nonequilibrium stationary states and measuring their "thermodynamic distance" from thermal equilibrium. While inner heliosphere plasmas reside in near equilibrium states with large kappa indices, generally >2.5, analysis of the IBEX ENA-spectra showed that inner heliosheath resides in states far from equilibrium with small kappa indices <2.5.

Livadiotis, G.; McComas, D. J.

2013-06-01

259

Equilibrium relationships for non-equilibrium chemical dependencies  

E-print Network

In contrast to common opinion, it is shown that equilibrium constants determine the time-dependent behavior of particular ratios of concentrations for any system of reversible first-order reactions. Indeed, some special ratios actually coincide with the equilibrium constant at any moment in time. This is established for batch reactors, and similar relations hold for steady-state plug-flow reactors, replacing astronomic time by residence time. Such relationships can be termed time invariants of chemical kinetics.

Gregory S. Yablonsky; Denis Constales; Guy B. Marin

2010-07-27

260

Colloidal Gels: Equilibrium and Non-Equilibrium Routes  

E-print Network

We attempt a classification of different colloidal gels based on colloid-colloid interactions. We discriminate primarily between non-equilibrium and equilibrium routes to gelation, the former case being slaved to thermodynamic phase separation while the latter is individuated in the framework of competing interactions and of patchy colloids. Emphasis is put on recent numerical simulations of colloidal gelation and their connection to experiments. Finally we underline typical signatures of different gel types, to be looked in more details in experiments.

Emanuela Zaccarelli

2007-06-12

261

Interregional equilibrium with heterogeneous labor.  

PubMed

"The impact of labor migration on interregional equilibrium is studied when workers are heterogeneous in productivity and regional mobility. The skilled respond to market disequilibrium by moving into the most attractive region. The unskilled are immobile in the short-run and move with the skilled in the long-run. Both regions have a neoclassical production function affected by an externality depending on the number of skilled. Workers move according to the utility differential when regional amenities vary with population or according to the wage differential. The equilibrium pattern depends on the unskilled's mobility and on migration incentives. Typically, regional imbalance characterizes the equilibrium which is often suboptimal." PMID:12291408

Michel, P; Perrot, A; Thisse J-f

1996-02-01

262

Understanding thermal equilibrium through activities  

NASA Astrophysics Data System (ADS)

Thermal equilibrium is a basic concept in thermodynamics. In India, this concept is generally introduced at the first year of undergraduate education in physics and chemistry. In our earlier studies (Pathare and Pradhan 2011 Proc. episteme-4 Int. Conf. to Review Research on Science Technology and Mathematics Education pp 169–72) we found that students in India have a rather unsatisfactory understanding of thermal equilibrium. We have designed and developed a module of five activities, which are presented in succession to the students. These activities address the students’ alternative conceptions that underlie their lack of understanding of thermal equilibrium and aim at enhancing their understanding of the concept.

Pathare, Shirish; Huli, Saurabhee; Nachane, Madhura; Ladage, Savita; Pradhan, Hemachandra

2015-03-01

263

Helical axis stellarator equilibrium model  

SciTech Connect

An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift.

Koniges, A.E.; Johnson, J.L.

1985-02-01

264

Non-equilibrium chemistry and cooling in the diffuse interstellar medium - I. Optically thin regime  

NASA Astrophysics Data System (ADS)

An accurate treatment of the multiphase interstellar medium (ISM) in hydrodynamic galaxy simulations requires that we follow not only the thermal evolution of the gas, but also the evolution of its chemical state, including its molecular chemistry, without assuming chemical (including ionization) equilibrium. We present a reaction network that can be used to solve for this thermo-chemical evolution. Our model follows the evolution of all ionization states of the 11 elements that dominate the cooling rate, along with important molecules such as H2 and CO, and the intermediate molecular species that are involved in their formation (20 molecules in total). We include chemical reactions on dust grains, thermal processes involving dust, cosmic ray ionization and heating and photochemical reactions. We focus on conditions typical for the diffuse ISM, with densities of 10-2 cm-3? nH?104 cm-3 and temperatures of 102 K ? T ? 104 K, and we consider a range of radiation fields, including no UV radiation. In this paper, we consider only gas that is optically thin, while paper II considers gas that becomes shielded from the radiation field. We verify the accuracy of our model by comparing chemical abundances and cooling functions in chemical equilibrium with the photoionization code CLOUDY. We identify the major coolants in diffuse interstellar gas to be C II, Si II and Fe II, along with O I and H2 at densities nH ? 102 cm-3. Finally, we investigate the impact of non-equilibrium chemistry on the cooling functions of isochorically or isobarically cooling gas. We find that, at T < 104 K, recombination lags increase the electron abundance above its equilibrium value at a given temperature, which can enhance the cooling rate by up to two orders of magnitude. The cooling gas also shows lower H2 abundances than in equilibrium, by up to an order of magnitude.

Richings, A. J.; Schaye, J.; Oppenheimer, B. D.

2014-06-01

265

Determination of vapor liquid equilibrium for the ternary iso-propanol/atactic-polypropylene/n-heptane mixture at 105C and 140C, and the binary iso-propanol/atactic-polypropylene mixture at 85C using perturbation gas chromatography / cby Lamar Lane Joffrion  

E-print Network

to Bondi's recommendation (1964). Using Bondi's work s;/sf is 1. 13 for the IPA/APP mixture and 1. 06 for the n-heptane/APP mixture. In Figure 6, composition isotherms are shown for the IPA/APP mixture using interpolation and integration results...

Joffrion, Lamar Lane

1984-01-01

266

Equilibrium and Orientation in Cephalopods.  

ERIC Educational Resources Information Center

Describes the structure of the equilibrium receptor system in cephalopods, comparing it to the vertebrate counterpart--the vestibular system. Relates the evolution of this complex system to the competition of cephalopods with fishes. (CS)

Budelmann, Bernd-Ulrich

1980-01-01

267

Essays in dynamic general equilibrium  

E-print Network

This thesis consists of three chapters studying dynamic economies in general equilibrium. The first chapter considers an economy in business cycles with potentially imperfect financial markets. The second chapter investigates ...

Cao, Dân (Dân Vu?)

2010-01-01

268

Equilibrium Constants You Can Smell.  

ERIC Educational Resources Information Center

Presents a simple experiment involving the sense of smell that students can accomplish during a lecture. Illustrates the important concepts of equilibrium along with the acid/base properties of various ions. (JRH)

Anderson, Michael; Buckley, Amy

1996-01-01

269

Equilibrium Electro-osmotic Instability  

E-print Network

Since its prediction fifteen years ago, electro-osmotic instability has been attributed to non-equilibrium electro-osmosis related to the extended space charge which develops at the limiting current in the course of concentration polarization at a charge-selective interface. This attribution had a double basis. Firstly, it has been recognized that equilibrium electro-osmosis cannot yield instability for a perfectly charge-selective solid. Secondly, it has been shown that non-equilibrium electro-osmosis can. First theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge-selectivity for the sake of simplicity and so did the subsequent numerical studies of various time-dependent and nonlinear features of electro-osmotic instability. In this letter, we show that relaxing the assumption of perfect charge-selectivity (tantamount to fixing the electrochemical potential in the solid) allows for equilibrium electro-osmotic instability. Moreover, we suggest a simple experimental test for determining the true, either equilibrium or non-equilibrium, origin of electro-osmotic instability.

Isaak Rubinstein; Boris Zaltzman

2014-03-18

270

Look into liquid phase of metal from the equation of state: Is there an agreement between shock-wave and isobaric-expansion data?  

Microsoft Academic Search

A wide-range multi-phase equation of state was used to analyze thermodynamic properties of metals at high pressure and temperature. The comparison has been done for static data, principal, reflected and porous Hugoniots, release isentropes, isobaric expansion data, density measurements in liquid metal, evaluations of the critical point. Discussed are results obtained for about 15 simple and transition metals.

I. V. Lomonosov; V. E. Fortov

1996-01-01

271

Quantum Statistical Mechanics. III. Equilibrium Probability  

E-print Network

Given are a first principles derivation and formulation of the probabilistic concepts that underly equilibrium quantum statistical mechanics. The transition to non-equilibrium probability is traversed briefly.

Phil Attard

2014-04-10

272

Polarized deuteron charge-exchange reaction $dp->{pp}_sN\\pi$ in the Delta-isobar region  

E-print Network

Mechanisms of the charge exchange reaction $dp\\to \\{pp\\}_{\\!s} N\\pi$, where $\\{pp\\}_{\\!s}$ is a two-proton system at low excitation energy, are studied at beam energies 1 -- 2 GeV and for invariant masses $M_X$ of the final $N\\pi $ system that correspond to the formation of the $\\Delta(1232)$ isobar. The direct mechanism, where the initial proton is excited into the $\\Delta(1232)$, dominates and explains the existing data on the unpolarized differential cross section and spherical tensor analyzing power $T_{22}$ for $M_X> 1.2$ GeV/$c^2$. However, this model fails to describe $T_{20}.

Uzikov, Yu N; Wilkin, C

2015-01-01

273

Spectroscopy of the neutron-deficient isobars {sup 163}Re and {sup 163}W using tagging techniques  

SciTech Connect

Selective tagging techniques have been used to establish new band structures in the transitional isobars {sup 163}Re and {sup 163}W. These nuclei were produced in the {sup 106}Cd({sup 60}Ni, xp yn {gamma}) reaction at a bombarding energy of 270 MeV. Prompt {gamma} rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated by the RITU separator and implanted into the GREAT spectrometer. At low spin, the yrast band of {sup 163}Re is shown to be a strongly coupled collective band based on a proton h{sub 11/2} configuration. In {sup 163}W, the decay path of the 13/2{sup +} isomeric state to the ground state has been identified and negative parity structures based on the ground state established.

Joss, D. T.; Thomson, J.; Page, R. D.; Bianco, L.; Darby, I. G.; Grahn, T.; Pakarinen, J.; Paul, E. S. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, L69 7ZE (United Kingdom); Scholey, C.; Eeckhaudt, S.; Greenlees, P. T.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Leppaennen, A.-P.; Nyman, M.; Rahkila, P.; Sorri, J. [Department of Physics, University of jyvaeskylae, FIN-40014, jyvaeskylae (Finland)] (and others)

2008-11-11

274

Proteomic identification and quantification of S-glutathionylation in mouse macrophages using resin-assisted enrichment and isobaric labeling.  

PubMed

S-Glutathionylation (SSG) is an important regulatory posttranslational modification on protein cysteine (Cys) thiols, yet the role of specific cysteine residues as targets of modification is poorly understood. We report a novel quantitative mass spectrometry (MS)-based proteomic method for site-specific identification and quantification of S-glutathionylation across different conditions. Briefly, this approach consists of initial blocking of free thiols by alkylation, selective reduction of glutathionylated thiols, and covalent capture of reduced thiols using thiol affinity resins, followed by on-resin tryptic digestion and isobaric labeling with iTRAQ (isobaric tags for relative and absolute quantitation) for MS-based identification and quantification. The overall approach was initially validated by application to RAW 264.7 mouse macrophages treated with different doses of diamide to induce glutathionylation. A total of 1071 Cys sites from 690 proteins were identified in response to diamide treatment, with ~90% of the sites displaying >2-fold increases in SSG modification compared to controls. This approach was extended to identify potential SSG-modified Cys sites in response to H2O2, an endogenous oxidant produced by activated macrophages and many pathophysiological stimuli. The results revealed 364 Cys sites from 265 proteins that were sensitive to S-glutathionylation in response to H2O2 treatment, thus providing a database of proteins and Cys sites susceptible to this modification under oxidative stress. Functional analysis revealed that the most significantly enriched molecular function categories for proteins sensitive to SSG modifications were free radical scavenging and cell death/survival. Overall the results demonstrate that our approach is effective for site-specific identification and quantification of SSG-modified proteins. The analytical strategy also provides a unique approach to determining the major pathways and cellular processes most susceptible to S-glutathionylation under stress conditions. PMID:24333276

Su, Dian; Gaffrey, Matthew J; Guo, Jia; Hatchell, Kayla E; Chu, Rosalie K; Clauss, Therese R W; Aldrich, Joshua T; Wu, Si; Purvine, Sam; Camp, David G; Smith, Richard D; Thrall, Brian D; Qian, Wei-Jun

2014-02-01

275

Proteomic Identification and Quantification of S-glutathionylation in Mouse Macrophages Using Resin-Assisted Enrichment and Isobaric Labeling  

SciTech Connect

Protein S-glutathionylation (SSG) is an important regulatory posttranslational modification of protein cysteine (Cys) thiol redox switches, yet the role of specific cysteine residues as targets of modification is poorly understood. We report a novel quantitative mass spectrometry (MS)-based proteomic method for site-specific identification and quantification of S-glutathionylation across different conditions. Briefly, this approach consists of initial blocking of free thiols by alkylation, selective reduction of glutathionylated thiols and enrichment using thiol affinity resins, followed by on-resin tryptic digestion and isobaric labeling with iTRAQ (isobaric tags for relative and absolute quantitation) for MS-based identification and quantification. The overall approach was validated by application to RAW 264.7 mouse macrophages treated with different doses of diamide to induce glutathionylation. A total of 1071 Cys-sites from 690 proteins were identified in response to diamide treatment, with ~90% of the sites displaying >2-fold increases in SSG-modification compared to controls.. This approach was extended to identify potential SSG modified Cys-sites in response to H2O2, an endogenous oxidant produced by activated macrophages and many pathophysiological stimuli. The results revealed 364 Cys-sites from 265 proteins that were sensitive to S-glutathionylation in response to H2O2 treatment. These proteins covered a range of molecular types and molecular functions with free radical scavenging, and cell death and survival included as the most significantly enriched functional categories. Overall the results demonstrate that our approach is effective for site-specific identification and quantification of S-glutathionylated proteins. The analytical strategy also provides a unique approach to determining the major pathways and cell processes most susceptible to glutathionylation at a proteome-wide scale.

Su, Dian; Gaffrey, Matthew J.; Guo, Jia; Hatchell, Kayla E.; Chu, Rosalie K.; Clauss, Therese RW; Aldrich, Joshua T.; Wu, Si; Purvine, Samuel O.; Camp, David G.; Smith, Richard D.; Thrall, Brian D.; Qian, Weijun

2014-02-11

276

Molecular dynamics in the isothermal-isobaric ensemble: The requirement of a ``shell'' molecule. III. Discontinuous potentials  

NASA Astrophysics Data System (ADS)

Based on the approach of Gruhn and Monson [Phys. Rev. E 63, 061106 (2001)], we present a new method for deriving the collisions dynamics for particles that interact via discontinuous potentials. By invoking the conservation of the extended Hamiltonian, we generate molecular dynamics (MD) algorithms for simulating the hard-sphere and square-well fluids within the isothermal-isobaric (NpT) ensemble. Consistent with the recent rigorous reformulation of the NpT ensemble partition function, the equations of motion impose a constant external pressure via the introduction of a shell particle of known mass [M. J. Uline and D. S. Corti, J. Chem. Phys. 123, 164101 (2005); 123, 164102 (2005)], which serves to define uniquely the volume of the system. The particles are also connected to a temperature reservoir through the use of a chain of Nosé-Hoover thermostats, the properties of which are not affected by a hard-sphere or square-well collision. By using the Liouville operator formalism and the Trotter expansion theorem to integrate the equations of motion, the update of the thermostat variables can be decoupled from the update of the positions of the particles and the momentum changes upon a collision. Hence, once the appropriate collision dynamics for the isobaric-isenthalpic (NpH ) equations of motion is known, the adaptation of the algorithm to the NpT ensemble is straightforward. Results of MD simulations for the pure component square-well fluid are presented and serve to validate our algorithm. Finally, since the mass of the shell particle is known, the system itself, and not a piston of arbitrary mass, controls the time scales for internal pressure and volume fluctuations. We therefore consider the influence of the shell particle algorithm on the dynamics of the square-well fluid.

Uline, Mark J.; Corti, David S.

2008-07-01

277

Fluid-solid equilibrium of carbon dioxide as obtained from computer simulations of several popular potential models: The role of the quadrupole  

NASA Astrophysics Data System (ADS)

In this work the solid-fluid equilibrium for carbon dioxide (CO2) has been evaluated using Monte Carlo simulations. In particular the melting curve of the solid phase denoted as I, or dry ice, was computed for pressures up to 1000 MPa. Four different models, widely used in computer simulations of CO2 were considered in the calculations. All of them are rigid non-polarizable models consisting of three Lennard-Jones interaction sites located on the positions of the atoms of the molecule, plus three partial charges. It will be shown that although these models predict similar vapor-liquid equilibria their predictions for the fluid-solid equilibria are quite different. Thus the prediction of the entire phase diagram is a severe test for any potential model. It has been found that the Transferable Potentials for Phase Equilibria (TraPPE) model yields the best description of the triple point properties and melting curve of carbon dioxide. It is shown that the ability of a certain model to predict the melting curve of carbon dioxide is related to the value of the quadrupole moment of the model. Models with low quadrupole moment tend to yield melting temperatures too low, whereas the model with the highest quadrupole moment yields the best predictions. That reinforces the idea that not only is the quadrupole needed to provide a reasonable description of the properties in the fluid phase, but also it is absolutely necessary to describe the properties of the solid phase.

Pérez-Sánchez, G.; González-Salgado, D.; Piñeiro, M. M.; Vega, C.

2013-02-01

278

Fluid-solid equilibrium of carbon dioxide as obtained from computer simulations of several popular potential models: the role of the quadrupole.  

PubMed

In this work the solid-fluid equilibrium for carbon dioxide (CO2) has been evaluated using Monte Carlo simulations. In particular the melting curve of the solid phase denoted as I, or dry ice, was computed for pressures up to 1000 MPa. Four different models, widely used in computer simulations of CO2 were considered in the calculations. All of them are rigid non-polarizable models consisting of three Lennard-Jones interaction sites located on the positions of the atoms of the molecule, plus three partial charges. It will be shown that although these models predict similar vapor-liquid equilibria their predictions for the fluid-solid equilibria are quite different. Thus the prediction of the entire phase diagram is a severe test for any potential model. It has been found that the Transferable Potentials for Phase Equilibria (TraPPE) model yields the best description of the triple point properties and melting curve of carbon dioxide. It is shown that the ability of a certain model to predict the melting curve of carbon dioxide is related to the value of the quadrupole moment of the model. Models with low quadrupole moment tend to yield melting temperatures too low, whereas the model with the highest quadrupole moment yields the best predictions. That reinforces the idea that not only is the quadrupole needed to provide a reasonable description of the properties in the fluid phase, but also it is absolutely necessary to describe the properties of the solid phase. PMID:23464159

Pérez-Sánchez, G; González-Salgado, D; Piñeiro, M M; Vega, C

2013-02-28

279

Tuning universality far from equilibrium  

NASA Astrophysics Data System (ADS)

Possible universal dynamics of a many-body system far from thermal equilibrium are explored. A focus is set on meta-stable non-thermal states exhibiting critical properties such as self-similarity and independence of the details of how the respective state has been reached. It is proposed that universal dynamics far from equilibrium can be tuned to exhibit a dynamical transition where these critical properties change qualitatively. This is demonstrated for the case of a superfluid two-component Bose gas exhibiting different types of long-lived but non-thermal critical order. Scaling exponents controlled by the ratio of experimentally tuneable coupling parameters offer themselves as natural smoking guns. The results shed light on the wealth of universal phenomena expected to exist in the far-from-equilibrium realm.

Karl, Markus; Nowak, Boris; Gasenzer, Thomas

2013-08-01

280

Detecting temperature fluctuations at equilibrium  

E-print Network

Gibbs and Boltzmann definitions of temperature agree only in the macroscopic limit. The ambiguity in identifying the equilibrium temperature of a finite sized `small' system exchanging energy with a bath is usually understood as a limitation of conventional statistical mechanics. We interpret this ambiguity as resulting from a stochastically fluctuating temperature coupled with the phase space variables giving rise to a broad temperature distribution. With this ansatz, we develop the equilibrium statistics and dynamics of small systems. Numerical evidence using an analytically tractable model shows that the effects of temperature fluctuations can be detected in equilibrium and dynamical properties of the phase space of the small system. Our theory generalizes statistical mechanics to small systems relevant to biophysics and nanotechnology.

Dixit, Purushottam D

2015-01-01

281

Tokamak equilibrium solver by neural network algorithm  

Microsoft Academic Search

Tokamak equilibrium analyses have been routinely carried out by solving the Grad-Shafranov equation with various conventional numerical techniques. As a new approach for the equilibrium analysis a neural network equilibrium solver has been proposed from the functional approximation capabilities of the artificial neural network. The neural network equilibrium solver does not have to perform finite differences and coordinate transformations, so

Young-Mu Jeon; Y. S. Park; Y. S. Hwang

2003-01-01

282

EQUILIBRIUM MIGRATION WITH INVESTED REMITTANCES  

Microsoft Academic Search

This paper analyzes international migrations when migrants invest part of their income in their origin country. We show that a non-total migratory equilibrium can exist if the foreign wage is not too high, and\\/or migratory and transfer costs are not too low. Exogenous shocks, such as an increase in the foreign wage, lead to an increase in optimal remittances per

Claire Naiditchand Radu Vranceanuy

283

DYNAMIC EQUILIBRIUM IN THERAPEUTIC SITUATIONS.  

ERIC Educational Resources Information Center

THE CONCEPT OF DYNAMIC EQUILIBRIUM IS USED TO EXAMINE THE OCCURRENCE OF CHANGE IN A THERAPEUTIC INTERVIEW AND TO PROPOSE A THEORY OF THERAPY. BY ANALYZING THE WORKINGS OF THE PSYCHOSOCIAL SYSTEM THROUGH THE GENERAL SYSTEMS THEORY, IT IS POSSIBLE TO SEE HOW CHANGE OCCURS IN AN INDIVIDUAL FAMILY OR COMMUNITY. APPLIED TO A FAMILY INTERVIEW, THE MODEL…

CARROLL, EDWARD J.

284

Quantifying mixing using equilibrium reactions  

SciTech Connect

A method of quantifying equilibrium reactions in a microchannel using a fluorometric reaction of Fluo-4 and Ca{sup 2+} ions is presented. Under the proper conditions, equilibrium reactions can be used to quantify fluid mixing without the challenges associated with constituent mixing measures such as limited imaging spatial resolution and viewing angle coupled with three-dimensional structure. Quantitative measurements of CaCl and calcium-indicating fluorescent dye Fluo-4 mixing are measured in Y-shaped microchannels. Reactant and product concentration distributions are modeled using Green's function solutions and a numerical solution to the advection-diffusion equation. Equilibrium reactions provide for an unambiguous, quantitative measure of mixing when the reactant concentrations are greater than 100 times their dissociation constant and the diffusivities are equal. At lower concentrations and for dissimilar diffusivities, the area averaged fluorescence signal reaches a maximum before the species have interdiffused, suggesting that reactant concentrations and diffusivities must be carefully selected to provide unambiguous, quantitative mixing measures. Fluorometric equilibrium reactions work over a wide range of pH and background concentrations such that they can be used for a wide variety of fluid mixing measures including industrial or microscale flows.

Wheat, Philip M. [Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, Arizona 85287-6106 (United States); Posner, Jonathan D. [Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, Arizona 85287-6106 (United States); Department of Chemical Engineering, Arizona State University, Tempe, Arizona 85287-6106 (United States)

2009-03-15

285

Equilibrium Statistical Mechanics Giovanni Gallavotti  

E-print Network

Equilibrium Statistical Mechanics Giovanni Gallavotti I.N.F.N. Roma 1, Fisica Roma1 1. Foundations: atoms and molecules Classical Statistical Mechanics studies properties of macroscopic aggregates the foundations of statistical mechanics have been laid on proper­ ties, proved or assumed, of few particles

Roma "La Sapienza", Università di

286

Equilibrium Statistical Mechanics Giovanni Gallavotti  

E-print Network

Equilibrium Statistical Mechanics Giovanni Gallavotti I.N.F.N. Roma 1, Fisica Roma1 1. Foundations: atoms and molecules Classical Statistical Mechanics studies properties of macroscopic aggregates the foundations of statistical mechanics have been laid on proper- ties, proved or assumed, of few particles

Roma "La Sapienza", Università di

287

Equilibrium Distribution Functions: Another Look.  

ERIC Educational Resources Information Center

Discusses equilibrium distribution functions and provides an alternative "derivation" that allows the student, with the help of a computer, to gain intuitive insight as to the nature of distributions in general and the precise nature of the dominance of the Boltzmann distribution. (JN)

Waite, Boyd A.

1986-01-01

288

Organizational equilibrium and organizational change  

Microsoft Academic Search

This article contrasts traditional models of MNE organizational design against newer models, represented by transnationalism and heterarchy. The important characteristics are fundamentally different. Traditional models tend to be models of equilibrium, while the newer models are largely models of change. With the intent of reconciling the two theories, it is argued that the new change-oriented models are most applicable at

William G Egelhoff

1999-01-01

289

Magnetospheric equilibrium with anisotropic pressure  

SciTech Connect

Self-consistent magnetospheric equilibrium with anisotropic pressure is obtained by employing an iterative metric method for solving the inverse equilibrium equation in an optimal flux coordinate system. A method of determining plasma parallel and perpendicular pressures from either analytic particle distribution or particle distribution measured along the satellite's path is presented. The numerical results of axisymmetric magnetospheric equilibrium including the effects of finite beta, pressure anisotropy, and boundary conditions are presented for a bi-Maxwellian particle distribution. For the isotropic pressure cases, the finite beta effect produces an outward expansion of the constant magnetic flux surfaces in relation to the dipole field lines, and along the magnetic field the toroidal ring current is maximum at the magnetic equator. The effect of pressure anisotropy is found to further expand the flux surfaces outward. Along the magnetic field lines the westward ring current can be peak away from the equator due to an eastward current contribution resulting from pressure anisotropy. As pressure anisotropy increases, the peak westward current can become more singular. The outer boundary flux surface has significant effect on the magnetospheric equilibrium. For the outer flux boundary resembling dayside compressed flux surface due to solar wind pressure, the deformation of the magnetic field can be quite different from that for the outer flux boundary resembling the tail-like surface. 23 refs., 17 figs.

Cheng, C.Z.

1991-07-01

290

Numerical models of CTX equilibrium  

SciTech Connect

The open mesh flux conserver (MFC) of the Los Alamos spheromak (CTX) is equipped with Rogowski loops that measure the current in many of its individual segments. The distribution of induced current in the toroidal hoops of the MFC can be used to construct numerical models of the CTX equilibrium.

Marklin, G.

1984-01-01

291

Chapter 9. Chemical Equilibrium 9.1 The Nature of Chemical Equilibrium  

E-print Network

Chapter 9. Chemical Equilibrium #12;9.1 The Nature of Chemical Equilibrium -Approach to Equilibrium equilibrium expressions for the following gas- phase chemical equilibria. (a) 2 NOCl(g) 2 NO(g) + Cl2(g) (b chemical equilibrium are not answered by these procedures. Why should the law of mass action exist

Ihee, Hyotcherl

292

Neutron-skin effects in isobaric yield ratios for mirror nuclei in a statistical abrasion-ablation model  

NASA Astrophysics Data System (ADS)

Background: The isobaric yield ratio for mirror nuclei [IYR(m)] in heavy-ion collisions, which is assumed to depend linearly on x=2(Z-1)/A1/3 of a fragment, is applied to study some coefficients of the energy terms in the binding energy, as well as the difference between the chemical potentials of a neutron and proton. It is found that the IYR(m) has a systematic dependence on the reaction, which has been explained as the volume and/or the isospin effects in previous studies. However, neither the volume nor the isospin effects can fully interpret the data.Purpose: We suppose that the IYR(m) depends on the neutron-skin thickness (?np) of the projectile, and check the idea of whether the neutron-skin thickness effects can fully explain the systematic dependence of the IYR(m).Methods: A modified statistical abrasion-ablation model is used to calculate the reactions induced by projectiles of three series: (1) the calcium isotopes from 36Ca to 56Ca as projectiles with different limitations on the impact parameters (bmax) to show the volume effects according to bmax; (2) the A=45 isobars as the projectiles having different isospins and ?np; and (3) projectiles having similar ?np to show whether the IYR(m) depends on the volume or the isospin of the projectile.Results: The IYR(m) shows a distribution of a linear part in the small-x fragments, and a nonlinear part in the large-x fragments. The linear part of IYR(m) is fitted. (1) In the calcium isotopic reactions, the IYR(m) depends on the isospin or the volume of the projectile, but ?np greatly influences the nonlinear part of the IYR(m). The IYR(m) does not depend on the colliding source in reactions of small bmax for the nonneutron-rich projectiles, and does not depend on the collision sources in reactions by the neutron-rich projectiles. (2) In reactions of the A=45 isobars, though IYR(m) depends on the isospin of projectile, IYR(m) shows small dependence on isospin if ?np>0. (3) In the reactions of projectiles having similar ?np, the IYR(m) in the small mass fragments show no dependence on the volume and the isospin of the projectile when the mass of the projectile is relatively large. Specifically, the dependence of IYR(m) on the mass of the isospin of the projectile vanishes when ?np˜0.02fm.Conclusions: The linear and nonlinear parts of the IYR(m) are governed by the core and the surface (skin) of the projectile, respectively. The neutron-skin effects can well explain the systematic dependence of the IYR(m).

Ma, Chun-Wang; Wei, Hui-Ling; Ma, Yu-Gang

2013-10-01

293

Non-Equilibrium Properties from Equilibrium Free Energy Calculations  

NASA Technical Reports Server (NTRS)

Calculating free energy in computer simulations is of central importance in statistical mechanics of condensed media and its applications to chemistry and biology not only because it is the most comprehensive and informative quantity that characterizes the eqUilibrium state, but also because it often provides an efficient route to access dynamic and kinetic properties of a system. Most of applications of equilibrium free energy calculations to non-equilibrium processes rely on a description in which a molecule or an ion diffuses in the potential of mean force. In general case this description is a simplification, but it might be satisfactorily accurate in many instances of practical interest. This hypothesis has been tested in the example of the electrodiffusion equation . Conductance of model ion channels has been calculated directly through counting the number of ion crossing events observed during long molecular dynamics simulations and has been compared with the conductance obtained from solving the generalized Nernst-Plank equation. It has been shown that under relatively modest conditions the agreement between these two approaches is excellent, thus demonstrating the assumptions underlying the diffusion equation are fulfilled. Under these conditions the electrodiffusion equation provides an efficient approach to calculating the full voltage-current dependence routinely measured in electrophysiological experiments.

Pohorille, Andrew; Wilson, Michael A.

2012-01-01

294

A Network Equilibrium FrameworkA Network Equilibrium Framework for Internet Advertising:for Internet Advertising  

E-print Network

A Network Equilibrium FrameworkA Network Equilibrium Framework for Internet Advertising:for Internet Advertising: Models, Quantitative Analysis, andModels, Quantitative Analysis, and Algorithms Internet marketing strategiescompetitive Internet marketing strategies as a network equilibrium problem

Nagurney, Anna

295

High-sensitivity isobar-free AMS measurements and reference materials for 55Fe, 68Ge and 202gPb  

NASA Astrophysics Data System (ADS)

Isobaric interference represents one of the major limitations in mass spectrometry. For a few cases in AMS with tandem accelerators, isobaric interference is completely excluded like the well-known major isotopes 14C, 26Al, 129I. Additional isotopes are 55Fe (t1/2 = 2.74 years), 68Ge (t1/2 = 270.9 days) and 202Pb (t1/2 = 52.5 kyr), with 68Ge and 202Pb never been used in AMS so far. Their respective stable isobars, 55Mn, 68Zn and 202Hg do not form stable negative ions. The exceptional sensitivity of AMS for 55Fe, 68Ge and 202gPb offers important insights into such different fields like nuclear astrophysics, fundamental nuclear physics and technological applications. VERA, a dedicated AMS facility is well suited for developing procedures for new and non-standard isotopes. AMS measurements at the VERA facility established low backgrounds for these radionuclides in natural samples. Limits for isotope ratios of <10-15, <10-16 and ?2 × 10-14 were measured for 55Fe/56Fe, 68Ge/70Ge and 202Pb/Pb, respectively. In order to generate accurate isotope ratios of sample materials, AMS relies on the parallel measurement of reference materials with well-known ratios. A new and highly accurate reference material for 55Fe measurements with an uncertainty of ±1.6% was produced from a certified reference solution. In case of 68Ge dedicated neutron activations produced a sufficiently large number of 68Ge atoms that allowed quantifying them through the activity of its decay product 68Ga. Finally, for 202Pb, the short-lived isobar 202Tl was produced via neutron activation and served as a proxy for 202Pb AMS measurements.

Wallner, A.; Bichler, M.; Buczak, K.; Fink, D.; Forstner, O.; Golser, R.; Hotchkis, M. A. C.; Klix, A.; Krasa, A.; Kutschera, W.; Lederer, C.; Plompen, A.; Priller, A.; Schumann, D.; Semkova, V.; Steier, P.

2013-01-01

296

Dose-dependent effect of intrathecal dexmedetomidine on isobaric ropivacaine in spinal anesthesia for abdominal hysterectomy: Effect on block characteristics and hemodynamics  

PubMed Central

Background and Aims: Effect of intrathecal dexmedetomidine as an adjuvant to isobaric ropivacaine in spinal anesthesia for abdominal hysterectomy is not much investigated. The objective was to assess the dose dependent effect of dexmedetomidine (3 mcg vs 5 mcg) as an adjunct to isobaric ropivacaine in spinal anesthesia. Materials and Methods: Forty selected female patients were randomized to receive intrathecal 0.5% isobaric ropivacaine (15 mg) with dexmedetomidine 3 mcg (Group D3) or 5 mcg (Group D5) in spinal anesthesia for abdominal hysterectomy. Block characteristics, hemodynamic changes, postoperative analgesia, and adverse effects were compared. Results: Both groups were comparable regarding sensory-motor block characteristics and postoperative analgesia (P > 0.05). Four (10%) patients of Group D5 and 5 (12.5%) of Group D3 could not achieve desired T6 sensory level and Bromage score of 3(complete motor block) hence were converted to general anesthesia at the outset. Nine (22.5%) patients each in both groups required ketamine supplementation (0.5 mg/kg) for intraoperative pain at the time of uterine manipulation. Incidence of hypotension was comparable (55.56% in Group D5 and 37.14% in Group D3, P = 0.11), but this occurred significantly earlier in Group D5, P < 0.001. Sedation was also significantly more in Group D5 as compared with Group D3, P < 0.01. Conclusion: We conclude that spinal anesthesia with isobaric ropivacaine (15 mg) with dexmedetomidine (3 mcg or 5 mcg) did not show much promise for abdominal hysterectomy as one third cases required analgesic supplementation. Both doses of dexmedetomidine produced a similar effect on block characteristic and postoperative analgesia; however, a dose of 5 mcg dose was associated with more hypotension and sedation. PMID:25788777

Naithani, Udita; Meena, Mahendra Singh; Gupta, Sunanda; Meena, Khemraj; Swain, Lalatendu; Pradeep, D. S.

2015-01-01

297

Fully self-consistent charge-exchange quasiparticle random-phase approximation and its application to isobaric analog resonances  

NASA Astrophysics Data System (ADS)

A microscopic model aimed at the description of charge-exchange nuclear excitations along isotopic chains which include open-shell systems is developed. It consists of the quasiparticle random phase approximation (QRPA) made on top of Hartree-Fock-Bardeen-Cooper-Schrieffer (HF-BCS). The calculations are performed by using the Skyrme interaction in the particle-hole channel and a zero-range, density-dependent pairing force in the particle-particle channel. At variance with the (many) versions of QRPA which are available in the literature, in our work special emphasis is put on the full self-consistency. Its importance, as well as the role played by the charge-breaking terms of the nuclear Hamiltonian, like the Coulomb interaction, the charge symmetry and charge independence breaking (CSB-CIB) forces and the electromagnetic spin-orbit, are elucidated by means of numerical calculations of the isobaric analog resonances (IAR). The theoretical energies of these states along the chain of the Sn isotopes agree well with the experimental data in the stable isotopes. Predictions for unstable systems are presented.

Fracasso, S.; Colò, G.

2005-12-01

298

Charge-exchange scattering to the isobaric analog state at medium energies as a probe of the neutron skin  

NASA Astrophysics Data System (ADS)

The charge-exchange (He3,t) scattering to the isobaric analog state (IAS) of the target can be considered as "elastic" scattering of He3 by the isovector term of the optical potential (OP) that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross section for the IAS can be a good probe of the isospin dependence of the OP, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. Given the neutron skin of the target related directly to the same density difference, it can be well probed in the analysis of the charge-exchange (He3,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation. For this purpose, the data of the (He3,t) scattering to the IAS of Zr90 and Pb208 targets at Elab=420 MeV have been analyzed in the distorted wave Born approximation using the double-folded charge-exchange form factor. The neutron skin deduced for these two nuclei turned out to be in a good agreement with the existing database.

Loc, Bui Minh; Khoa, Dao T.; Zegers, R. G. T.

2014-02-01

299

Folding model study of the isobaric analog excitation: Isovector density dependence, Lane potential, and nuclear symmetry energy  

NASA Astrophysics Data System (ADS)

A consistent folding model analysis of the (?S=0,?T=1) charge exchange (p,n) reaction measured with Ca48, Zr90, Sn120, and Pb208 targets at the proton energies of 35 and 45 MeV is done within a two-channel coupling formalism. The nuclear ground state densities given by the Hartree-Fock-Bogoliubov formalism and the density-dependent CDM3Y6 interaction were used as inputs for the folding calculation of the nucleon optical potential and (p,n) form factor. To have an accurate isospin dependence of the interaction, a complex isovector density dependence of the CDM3Y6 interaction has been carefully calibrated against the microscopic Brueckner-Hartree-Fock calculation by Jeukenne, Lejeune, and Mahaux before being used as folding input. Since the isovector coupling was used to explicitly link the isovector part of the nucleon optical potential to the cross section of the (p,n) reaction exciting the 0+ isobaric analog states in Sc48, Nb90, Sb120, and Bi208, the newly parametrized isovector density dependence could be well tested in the folding model analysis of the (p,n) reaction. The isospin- and density-dependent CDM3Y6 interaction was further used in the Hartree-Fock calculation of asymmetric nuclear matter, and a realistic estimation of the nuclear symmetry energy was made.

Khoa, Dao T.; Than, Hoang Sy; Cuong, Do Cong

2007-07-01

300

Charge exchange (p,n) reactions to the isobaric analog states of high Z nuclei: 73<=Z<=92  

NASA Astrophysics Data System (ADS)

Differential cross sections have been measured for the (p,n) reaction to the isobaric analog states of 181Ta, 197Au, 209Bi, 232Th, and 238U at an incident energy of 27 MeV. Because of the importance of collective effects in this mass region, coupled-channel calculations have been carried out in the analysis of the data. Optical potentials obtained from the Lane model for the charge exchange reaction have been used in the simultaneous analysis of coupled proton and neutron channels. The sensitivity of the calculations to the different couplings between the levels and to the magnitude of the isovector potentials, V1 and W1, is discussed. The good agreement obtained between the measured and calculated (p,n) angular distributions to the analog state confirms the validity of the Lane formalism for high-Z nuclei (Z>=50). Elastic neutron differential cross sections inferred from the coupled-channel analysis are compared with measurements available in the literature in the energy range 7-8 MeV. The results of these calculations agree with the measured values as well as the results of calculations made using global neutron optical potential parameters optimized to fit neutron data. NUCLEAR REACTIONS 181Ta, 197Au, 209Bi, 232Th, 238U(p,n)IAS; E=27 MeV; Measured ?(?) for ground-state analog transition; deduced (n,n)?(?), E=7-8 MeV; coupled-channel analysis.

Hansen, L. F.; Grimes, S. M.; Poppe, C. H.; Wong, C.

1983-11-01

301

Equilibrium cluster formation and gelation  

E-print Network

We study the formation and growth of equilibrium clusters in a suspension of weakly-charged colloidal particles and small non-adsorbing polymers. The effective potential is characterised by a short-range attraction and a long-range repulsion. The size, shape and local structure of the clusters are studied using three-dimensional particle microscopy. We observe a rapid growth in the mean cluster size and the average number of nearest neighbours approaching the gel boundary.

Rodrigo Sanchez; Paul Bartlett

2005-06-22

302

Chemical Equilibrium and Isotope Temperatures  

E-print Network

The measurement and interpretation of isotopic yield ratios in heavy ion reactions at intermediate and high energies are discussed and the usefulness of these observables for establishing equilibrium properties and for determining thermodynamic parameters is illustrated. The examples are mainly taken from work performed with lighter projectiles at intermediate and high energies and from studies of spectator reactions at relativistic energies. As an application, the caloric curve of nuclei, as derived for Au on Au collisions, is introduced and discussed.

J. Pochodzalla; W. Trautmann

2000-09-20

303

Development of a Vaporizing Liquid Bismuth Anode for Hall Thrusters  

Microsoft Academic Search

Bismuth metal vapor Hall thrusters may have superior performance and economic characteristics when compared to xenon. From increased efficiency to reduced propellant and testing costs, bismuth seems to have a bright future. Of paramount importance when developing a practical bismuth device is the mechanism by which the propellant flow is controlled. This paper reports on an effort to use waste

Dean Massey; Alexander Kieckhafer; Jason Sommerville; Lyon B. King

304

Two-Step Vapor/Liquid/Solid Purification  

NASA Technical Reports Server (NTRS)

Vertical distillation system combines in single operation advantages of multiple zone refining with those of distillation. Developed specifically to load Bridgman-Stockbarger (vertical-solidification) growth ampoules with ultrapure tellurium and cadmium, system, with suitable modifications, serves as material refiner. In first phase of purification process, ampoule heated to drive off absorbed volatiles. Second phase, evaporator heated to drive off volatiles in charge. Third phase, slowly descending heater causes distillation from evaporator to growing crystal in ampoule.

Holland, L. R.

1986-01-01

305

Morphodynamic equilibrium of alluvial estuaries  

NASA Astrophysics Data System (ADS)

The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final equilibrium state is reached through an erosional wave, which leads to bed degradation of the upstream 'fluvial reach'. For a given river discharge, the length of the tidal reach increases quite rapidly with tidal amplitude, up to some threshold value of the tidal amplitude above which the length of the estuary becomes comparable with the length of the tidal wave. When the channel plan-form is convergent, deposition of sediments of fluvial origin in the funnel-shaped region drastically changes the equilibrium configuration. The effect of an increasing channel convergence is thus to induce bed aggradation close to the inlet. Nevertheless, tidal forcing only slightly changes the non-tidal profile. The effect of increasing tidal oscillations again leads to an increase of the bed slope at the inlet and to a general bed degradation upstream. The effects of varying sediment supply, flow discharge and river width in the upstream reach have also been investigated and play an important role. Further geomorphological implications of these results will be discussed at the meeting. References Dalrymple, R. W., and K. Choi (2007), Morphologic and facies trends through the fluvialmarine transition in tide-dominated depositional systems: A schematic framework for environmental and sequence-stratigraphic interpretation, Earth-Science Reviews, 81(3-4), 135-174, doi:10.1016/j.earscirev.2006.10.002. Seminara, G., M. Bolla Pittaluga, and N. Tambroni (2012), Morphodynamic equilibrium of tidal channels, Environmental Fluid Mechanics: Memorial Volume in Honour of Prof. Gerhard H. Jirka, 153-174

Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni

2014-05-01

306

Two Suggestions for Improving Chemical Equilibrium Instruction  

E-print Network

Two Suggestions for Improving Chemical Equilibrium Instruction Journal: Journal of Chemical to the Journal of Chemical Education #12;ed-20XX-XXXXXX Two Suggestions for Improving Chemical Equilibrium Chemical Equilibrium Instruction David Yaron*1, Jodi L. Davenport2, James Greeno3, Michael Karabinos1

Yaron, David

307

Princeton spectral equilibrium code: PSEC  

SciTech Connect

A fast computer code has been developed to calculate free-boundary solutions to the plasma equilibrium equation that are consistent with the currents in external coils and conductors. The free-boundary formulation is based on the minimization of a mean-square error epsilon while the fixed-boundary solution is based on a variational principle and spectral representation of the coordinates x(psi,theta) and z(psi,theta). Specific calculations using the Columbia University Torus II, the Poloidal Divertor Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR) geometries are performed.

Ling, K.M.; Jardin, S.C.

1984-03-01

308

A Quantitative Tool to Distinguish Isobaric Leucine and Isoleucine Residues for Mass Spectrometry-Based De Novo Monoclonal Antibody Sequencing  

NASA Astrophysics Data System (ADS)

De novo sequencing by mass spectrometry (MS) allows for the determination of the complete amino acid (AA) sequence of a given protein based on the mass difference of detected ions from MS/MS fragmentation spectra. The technique relies on obtaining specific masses that can be attributed to characteristic theoretical masses of AAs. A major limitation of de novo sequencing by MS is the inability to distinguish between the isobaric residues leucine (Leu) and isoleucine (Ile). Incorrect identification of Ile as Leu or vice versa often results in loss of activity in recombinant antibodies. This functional ambiguity is commonly resolved with costly and time-consuming AA mutation and peptide sequencing experiments. Here, we describe a set of orthogonal biochemical protocols, which experimentally determine the identity of Ile or Leu residues in monoclonal antibodies (mAb) based on the selectivity that leucine aminopeptidase shows for n-terminal Leu residues and the cleavage preference for Leu by chymotrypsin. The resulting observations are combined with germline frequencies and incorporated into a logistic regression model, called Predictor for Xle Sites (PXleS) to provide a statistical likelihood for the identity of Leu at an ambiguous site. We demonstrate that PXleS can generate a probability for an Xle site in mAbs with 96% accuracy. The implementation of PXleS precludes the expression of several possible sequences and, therefore, reduces the overall time and resources required to go from spectra generation to a biologically active sequence for a mAb when an Ile or Leu residue is in question.

Poston, Chloe N.; Higgs, Richard E.; You, Jinsam; Gelfanova, Valentina; Hale, John E.; Knierman, Michael D.; Siegel, Robert; Gutierrez, Jesus A.

2014-07-01

309

X-ray continuum as a measure of pressure and fuel-shell mix in compressed isobaric hydrogen implosion cores  

NASA Astrophysics Data System (ADS)

Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus'kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion's central hot spot, the hot-spot "fuel-shell" mix mass can be inferred.

Epstein, R.; Goncharov, V. N.; Marshall, F. J.; Betti, R.; Nora, R.; Christopherson, A. R.; Golovkin, I. E.; MacFarlane, J. J.

2015-02-01

310

High-Field Asymmetric-Waveform Ion Mobility Spectrometry and Electron Detachment Dissociation of Isobaric Mixtures of Glycosaminoglycans  

PubMed Central

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is shown to be capable of resolving isomeric and isobaric glycosaminoglycan negative ions, and to have great utility for the analysis of this class of molecules when combined with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tandem mass spectrometry. Electron detachment dissociation (EDD) and other ion activation methods for tandem mass spectrometry can be used to determine the sites of labile sulfate modifications and for assigning the stereochemistry of hexuronic acid residues of GAGs. However, mixtures with overlapping mass-to-charge values present a challenge, as their precursor species cannot be resolved by a mass analyzer prior to ion activation. FAIMS is shown to resolve two types of mass-to-charge overlaps. A mixture of chondroitin sulfate A (CSA) oligomers with 4–10 saccharides units produces ions of a single mass-to-charge by electrospray ionization, as the charge state increases in direct proportion to the degree of polymerization for these sulfated carbohydrates. FAIMS is shown to resolve the overlapping charge. A more challenging type of mass-to-charge overlap occurs for mixtures of diastereomers. FAIMS is shown to separate two sets of epimeric GAG tetramers. For the epimer pairs, the complexity of the separation is reduced when the reducing end is alkylated, suggesting that anomers are also resolved by FAIMS. The resolved components were activated by EDD and the fragment ions were analyzed by FTICR-MS. The resulting tandem mass spectra were able to distinguish the two epimers from each other. PMID:24254578

Kailemia, Muchena J.; Park, Melvin; Kaplan, Desmond A.; Venot, Andre; Boons, Geert-Jan; Li, Lingyun; Linhardt, Robert J.; Amster, I. Jonathan

2014-01-01

311

High-Field Asymmetric-Waveform Ion Mobility Spectrometry and Electron Detachment Dissociation of Isobaric Mixtures of Glycosaminoglycans  

NASA Astrophysics Data System (ADS)

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is shown to be capable of resolving isomeric and isobaric glycosaminoglycan negative ions and to have great utility for the analysis of this class of molecules when combined with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tandem mass spectrometry. Electron detachment dissociation (EDD) and other ion activation methods for tandem mass spectrometry can be used to determine the sites of labile sulfate modifications and for assigning the stereochemistry of hexuronic acid residues of glycosaminoglycans (GAGs). However, mixtures with overlapping mass-to-charge values present a challenge, as their precursor species cannot be resolved by a mass analyzer prior to ion activation. FAIMS is shown to resolve two types of mass-to-charge overlaps. A mixture of chondroitin sulfate A (CSA) oligomers with 4-10 saccharides units produces ions of a single mass-to-charge by electrospray ionization, as the charge state increases in direct proportion to the degree of polymerization for these sulfated carbohydrates. FAIMS is shown to resolve the overlapping charge. A more challenging type of mass-to-charge overlap occurs for mixtures of diastereomers. FAIMS is shown to separate two sets of epimeric GAG tetramers. For the epimer pairs, the complexity of the separation is reduced when the reducing end is alkylated, suggesting that anomers are also resolved by FAIMS. The resolved components were activated by EDD and the fragment ions were analyzed by FTICR-MS. The resulting tandem mass spectra were able to distinguish the two epimers from each other.

Kailemia, Muchena J.; Park, Melvin; Kaplan, Desmond A.; Venot, Andre; Boons, Geert-Jan; Li, Lingyun; Linhardt, Robert J.; Amster, I. Jonathan

2013-11-01

312

Non-equilibrium phase transitions  

SciTech Connect

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken.

Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.

1998-12-31

313

Thermodynamic equilibrium at heterogeneous pressure  

NASA Astrophysics Data System (ADS)

Recent advances in metamorphic petrology point out the importance of grain-scale pressure variations in high-temperature metamorphic rocks. Pressures derived from chemical zonation using unconventional geobarometry based on equal chemical potentials fit mechanically feasible pressure variations. Here a thermodynamic equilibrium method is presented that predicts chemical zoning as a result of pressure variations by Gibbs energy minimization. Equilibrium thermodynamic prediction of the chemical zoning in the case of pressure heterogeneity is done by constraint Gibbs minimization using linear programming techniques. Compositions of phases considered in the calculation are discretized into 'pseudo-compounds' spanning the entire compositional space. Gibbs energies of these discrete compounds are generated for a given range and resolution of pressures for example derived by barometry or from mechanical model predictions. Gibbs energy minimization is subsequently performed considering all compounds of different composition and pressure. In addition to constraining the system composition a certain proportion of the system is constraint at a specified pressure. Input pressure variations need to be discretized and each discrete pressure defines an additional constraint for the minimization. The proportion of the system at each different pressure is equally distributed over the number of input pressures. For example if two input pressures P1 and P2 are specified, two constraints are added: 50 percent of the system is constraint at P1 while the remaining 50 percent is constraint at P2. The method has been tested for a set of 10 input pressures obtained by Taj?manová et al. (2014) using their unconventional geobarometry method in a plagioclase rim around kyanite. Each input pressure is added as constraint to the minimization (1/10 percent of the system for each discrete pressure). Constraining the system composition to the average composition of the plagioclase rim successfully predicts the observed chemical zoning. In conclusion, Gibbs minimization provides identical results to the geobarometry approach based on chemical potentials thus validating the inferred pressure gradient. The thermodynamic consistency of the calculation is supported by the similar result obtained from two different approaches. Reference: Taj?manová, L., Podladchikov, Y., Powell, R., Moulas, E., Vrijmoed, J. C. & Connolly, J. A. D. (2014). Grain scale pressure variations and chemical equilibrium in high-grade metamorphic rocks. Journal of Metamorphic Geology, (in press).

Vrijmoed, Johannes C.; Podladchikov, Yuri Y.

2014-05-01

314

Simultaneous quantification of protein phosphorylation sites using liquid chromatography-tandem mass spectrometry-based targeted proteomics: a linear algebra approach for isobaric phosphopeptides.  

PubMed

As one of the most studied post-translational modifications (PTM), protein phosphorylation plays an essential role in almost all cellular processes. Current methods are able to predict and determine thousands of phosphorylation sites, whereas stoichiometric quantification of these sites is still challenging. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)-based targeted proteomics is emerging as a promising technique for site-specific quantification of protein phosphorylation using proteolytic peptides as surrogates of proteins. However, several issues may limit its application, one of which relates to the phosphopeptides with different phosphorylation sites and the same mass (i.e., isobaric phosphopeptides). While employment of site-specific product ions allows for these isobaric phosphopeptides to be distinguished and quantified, site-specific product ions are often absent or weak in tandem mass spectra. In this study, linear algebra algorithms were employed as an add-on to targeted proteomics to retrieve information on individual phosphopeptides from their common spectra. To achieve this simultaneous quantification, a LC-MS/MS-based targeted proteomics assay was first developed and validated for each phosphopeptide. Given the slope and intercept of calibration curves of phosphopeptides in each transition, linear algebraic equations were developed. Using a series of mock mixtures prepared with varying concentrations of each phosphopeptide, the reliability of the approach to quantify isobaric phosphopeptides containing multiple phosphorylation sites (? 2) was discussed. Finally, we applied this approach to determine the phosphorylation stoichiometry of heat shock protein 27 (HSP27) at Ser78 and Ser82 in breast cancer cells and tissue samples. PMID:25403019

Xu, Feifei; Yang, Ting; Sheng, Yuan; Zhong, Ting; Yang, Mi; Chen, Yun

2014-12-01

315

Measurement and isobar-model analysis of the doubly differential cross section for the. pi. /sup +/ produced in. pi. /sup -/p. -->. pi. /sup +/. pi. /sup -/n  

SciTech Connect

The doubly differential cross section d/sup 2/sigma/d..cap omega..dT for ..pi../sup +/ mesons produced in the reaction ..pi../sup -/p ..-->.. ..pi../sup +/..pi../sup -/n was measured at 203, 230, 256, and 358 MeV with a single-arm magnetic spectrometer. A set of five previous measurements at 254, 280, 292, 331, and 356 MeV was reanalyzed with the new measurements. Integrated cross sections were calculated for the combined data set with unprecedented accuracy for this energy range. The chiral-symmetry-breaking parameter was determined to be epsilon = -0.03 +- 0.26 by extrapolating the mean square modulus of the matrix element to threshold and comparing the threshold matrix element with the prediction of soft-pion theory. This value of epsilon is consistent with zero as required by the Weinberg Lagrangian. Measurements at the three highest energies were compared with the results of an isobar-model analysis of bubble-chamber events by an LBL-SLAC collaboration. After allowing for an overall normalization difference, the measurements at 331 and 358 MeV were in excellent agreement with the results of their analysis. The measurement at 292 MeV required variation of the PS11(epsilonN) amplitude, as well as the overall normalization, which could be due to the limited number of bubble-chamber events available for the LBL-SLAC analysis at this energy. A partial-wave analysis of the measurements was also carried out with the VPI isobar model. Within this model, the matrix element contains a background term calculated from a phenomenological ..pi..N Lagrangian that is consistent with the hypotheses of current algebra and PCAC. The reaction was found to be dominated by the initial P11 wave. Production of the ..delta.. isobar from initial D waves was found to be significant at the two highest energies.

Manley, D.M.

1981-11-01

316

A comparison of thoracic spinal anesthesia with low-dose isobaric and low-dose hyperbaric bupivacaine for orthopedic surgery: A randomized controlled trial  

PubMed Central

Background: The thoracic spinal anesthesia was first described in 1909 and recently revised for various surgical procedures. This is a prospective study aims to evaluate the parameters of the thoracic spinal anesthesia (latency, motor block and paresthesia), the incidence of cardiovascular changes and complications comparing low doses of isobaric and hyperbaric bupivacaine. Materials and Methods: A total of 200 orthopedic patients operated under spinal anesthesia were included in this study. Spinal anesthesia was between T9-T10, with a 27G cutting point or pencil tip in lateral or sitting. Spinal anesthesia was performed with 0.5% bupivacaine isobaric or hyperbaric. Patients remained in cephalad or head down position 10-20° for 10 minutes. We evaluated the demographics, analgesia, and degree of motor block, incidence of paresthesia, bradycardia, hypotension, anesthesia success and neurological complications. Results: All patients developed spinal and there was no failure. The solution did not affect the onset of the blockade. The duration of motor block was greater than the sensitive with isobaric. The duration of sensory block was greater than the motor block with hyperbaric solution. The incidence of paresthesia was 4%, with no difference between the needles. The incidence of hypotension was 12.5% with no difference between the solutions. There was no neurological damage in all patients. Conclusion: The beginning of the block is fast regardless of the solution used. By providing a sensory block of longer duration than the motor block hyperbaric bupivacaine is reflected in a better indication. Thoracic spinal anesthesia provides excellent anesthesia for lower limb orthopedic surgery

Imbelloni, Luiz Eduardo; Gouveia, Marildo A.

2014-01-01

317

Local non-equilibrium thermodynamics.  

PubMed

Local Shannon entropy lies at the heart of modern thermodynamics, with much discussion of trajectory-dependent entropy production. When taken at both boundaries of a process in phase space, it reproduces the second law of thermodynamics over a finite time interval for small scale systems. However, given that entropy is an ensemble property, it has never been clear how one can assign such a quantity locally. Given such a fundamental omission in our knowledge, we construct a new ensemble composed of trajectories reaching an individual microstate, and show that locally defined entropy, information, and free energy are properties of the ensemble, or trajectory-independent true thermodynamic potentials. We find that the Boltzmann-Gibbs distribution and Landauer's principle can be generalized naturally as properties of the ensemble, and that trajectory-free state functions of the ensemble govern the exact mechanism of non-equilibrium relaxation. PMID:25592077

Jinwoo, Lee; Tanaka, Hajime

2015-01-01

318

Local non-equilibrium thermodynamics  

PubMed Central

Local Shannon entropy lies at the heart of modern thermodynamics, with much discussion of trajectory-dependent entropy production. When taken at both boundaries of a process in phase space, it reproduces the second law of thermodynamics over a finite time interval for small scale systems. However, given that entropy is an ensemble property, it has never been clear how one can assign such a quantity locally. Given such a fundamental omission in our knowledge, we construct a new ensemble composed of trajectories reaching an individual microstate, and show that locally defined entropy, information, and free energy are properties of the ensemble, or trajectory-independent true thermodynamic potentials. We find that the Boltzmann-Gibbs distribution and Landauer's principle can be generalized naturally as properties of the ensemble, and that trajectory-free state functions of the ensemble govern the exact mechanism of non-equilibrium relaxation. PMID:25592077

Jinwoo, Lee; Tanaka, Hajime

2015-01-01

319

Local non-equilibrium thermodynamics  

NASA Astrophysics Data System (ADS)

Local Shannon entropy lies at the heart of modern thermodynamics, with much discussion of trajectory-dependent entropy production. When taken at both boundaries of a process in phase space, it reproduces the second law of thermodynamics over a finite time interval for small scale systems. However, given that entropy is an ensemble property, it has never been clear how one can assign such a quantity locally. Given such a fundamental omission in our knowledge, we construct a new ensemble composed of trajectories reaching an individual microstate, and show that locally defined entropy, information, and free energy are properties of the ensemble, or trajectory-independent true thermodynamic potentials. We find that the Boltzmann-Gibbs distribution and Landauer's principle can be generalized naturally as properties of the ensemble, and that trajectory-free state functions of the ensemble govern the exact mechanism of non-equilibrium relaxation.

Jinwoo, Lee; Tanaka, Hajime

2015-01-01

320

Bose condensation far from equilibrium  

E-print Network

The formation of Bose condensates far from equilibrium can play an important role in our understanding of collision experiments of heavy nuclei or for the evolution of the early universe. In the relativistic quantum world particle number changing processes can counteract Bose condensation, and there is a considerable debate about the relevance of this phenomenon in this context. We show that the involved question of Bose condensation from initial over-population can be answered for the example of scalar field theories. Condensate formation occurs as a consequence of an inverse particle cascade with a universal power-law spectrum. This particle transport towards low momenta is part of a dual cascade, in which energy is also transfered by weak wave turbulence towards higher momenta. To highlight the importance of number changing processes for the subsequent decay of the condensate, we also compare to non-relativistic theories with exact number conservation. We discuss the relevance of these results for nonabelian gauge theories.

J. Berges; D. Sexty

2012-03-09

321

Equilibrium calculations of firework mixtures  

SciTech Connect

Thermochemical equilibrium calculations have been used to calculate detonation conditions for typical firework components including three report charges, two display charges, and black powder which is used as a fuse or launch charge. Calculations were performed with a modified version of the TIGER code which allows calculations with 900 gaseous and 600 condensed product species at high pressure. The detonation calculations presented in this paper are thought to be the first report on the theoretical study of firework detonation. Measured velocities for two report charges are available and compare favorably to predicted detonation velocities. However, the measured velocities may not be true detonation velocities. Fast deflagration rather than an ideal detonation occurs when reactants contain significant amounts of slow reacting constituents such as aluminum or titanium. Despite such uncertainties in reacting pyrotechnics, the detonation calculations do show the complex nature of condensed phase formation at elevated pressures and give an upper bound for measured velocities.

Hobbs, M.L. [Sandia National Labs., Albuquerque, NM (United States); Tanaka, Katsumi; Iida, Mitsuaki; Matsunaga, Takehiro [National Inst. of Materials and Chemical Research, Tsukuba, Ibaraki (Japan)

1994-12-31

322

Kinetic equilibrium reconstruction on EAST tokamak  

NASA Astrophysics Data System (ADS)

Plasma equilibrium is an important basis for tokamak plasma research. The equilibrium reconstructed from experimental diagnostics is a key element for experiments analysis and for theory study. The kinetic equilibrium has the profiles information (current or safety factor profile, kinetic pressure profile), which are key issues for some studies of physics. With the constraints of magnetic measurements, pressure profile and edge current profile, we achieved the first reconstructed kinetic equilibrium on EAST tokamak. The pressure and edge current profiles are based on the diagnostics and theoretical bootstrap current model. The kinetic equilibrium has the pedestal structure for H-mode plasma, which the magnetic reconstruction missed. This improved equilibrium is an important basis for some experimental analysis and theory studies on EAST.

Li, G. Q.; Ren, Q. L.; Qian, J. P.; Lao, L. L.; Ding, S. Y.; Chen, Y. J.; Liu, Z. X.; Lu, B.; Zang, Q.

2013-12-01

323

Structural properties of methanol-water binary mixtures within the quantum cluster equilibrium model.  

PubMed

Density functional theory (B3LYP-D3, M06-2X) has been used to calculate the structures, interaction energies and vibrational frequencies of a set of 93 methanol-water clusters of different type (cubic, ring, spiro, lasso, bicyclic), size and composition. These interaction energies have been used within the framework of the Quantum Cluster Equilibrium Theory (QCE) to calculate cluster populations as well as thermodynamic properties of binary methanol-water mixtures spanning the whole range from pure water to pure methanol. The necessary parameters amf and bxv of the QCE model were obtained by fitting to experimental isobars of MeOH-H2O mixtures with different MeOH content. The cubic and spiro motifs dominate the distribution of methanol-water clusters in the mixtures with a maximum of mixed clusters at x(MeOH) = 0.365. Reasonable agreement with experimental data as well as earlier molecular dynamics simulations was found for excess enthalpies H(E), entropies S(E) as well as Gibbs free energies of mixing G(E). In contrast, heat capacities Cp and C showed only poor agreement with experimental data. PMID:25660666

Matisz, G; Kelterer, A-M; Fabian, W M F; Kunsági-Máté, S

2015-04-01

324

Parametric study and characterization of the isobaric thermomechanical transformation fatigue of nickel-rich NiTi SMA actuators  

NASA Astrophysics Data System (ADS)

The recent development of various aerospace applications utilizing Ni-rich NiTi Shape memory Alloys (SMAs) as actuators motivated the need to characterize the cyclic response and the transformation fatigue behavior of such alloys. The fatigue life validation and certification of new designs is required in order to be implemented and used in future applications. For that purpose, a custom built fatigue test frame was designed to perform isobaric thermally induced transformation cycles on small dogbones SMA actuators (test gauge cross-section up to: 1.270 x 0.508 mm2). A parametric study on the cyclic response and transformation fatigue behavior of Ni-rich NiTi SMAs led to the optimization of several material/process and test parameters, namely: the applied stress range, the heat treatment, the heat treatment environment and the specimen thickness. However, fatigue testing was performed in a chilled waterless glycol environment maintained at a temperature of 5°C that showed evidence of corrosion-assisted transformation fatigue failure. Therefore, it was necessary to build a fatigue test frame that would employ a dry and inert cooling methodology to get away from any detrimental interactions between the specimens and the cooling medium (corrosion). The selected cooling method was gaseous nitrogen, sprayed into a thermally insulated chamber, maintaining a temperature of -20°C. The design of the gaseous nitrogen cooling was done in such a way that the actuation frequency is similar to the one obtained using the original design (~ 0.1 Hz). For both cooling methods, Joule resistive heating was used to heat the specimens. In addition and motivated by the difference in surface quality resulting from different material processing such as EDM wire cutting and heat treatments, EDM recast layer and oxide layer were removed. The removal was followed by an ultra-fine polish (0.05 ?m) that was performed on a subset of the fatigue specimens. Experimental results are presented for full actuation of the SMA actuators and are given in terms of applied stress, accumulated plastic strain and number of cycles to failure. In addition, the assessment of the influence of the surface quality is supported by fatigue tests results and post-failure microstructure analysis.

Bertacchini, Olivier W.; Schick, Justin; Lagoudas, Dimitris C.

2009-03-01

325

Industry equilibrium, uncertainty, and futures markets  

Microsoft Academic Search

This paper studies competitive long-run industry equilibrium with uncertainty and futures trading. We also provide a long-run analysis of futures trading instead of the conventional short-run analysis. It is shown without using a general equilibrium model that, given uncertain demand and risk aversion, a bias (backwardation or contango) arises in long-run industry equilibrium. Given risk neutrality such a bias, however,

Shoji Haruna

1996-01-01

326

Vadose zone isobaric well  

DOEpatents

A deep tensiometer is configured with an outer guide tube having a vented interval along a perforate section at its lower end, which is isolated from atmospheric pressure at or above grade. A transducer having a monitoring port and a reference port is located within a coaxial inner guide tube. The reference port of the transducer is open to the vented interval of the outer guide tube, which has the same gas pressure as in the sediment surrounding the tensiometer. The reference side of the pressure transducer is thus isolated from the effects of atmospheric pressure changes and relative to pressure changes in the material surrounding the tensiometer measurement location and so it is automatically compensated for such pressure changes.

Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)

2001-01-01

327

Passive equilibrium studies on ZT-P  

SciTech Connect

The poloidal field system of ZT-P was modified by the addition of a transformer, which coupled the magnetizing and equilibrium circuits. ZT-P is a small, air core, Reversed Field Pinch, operated at the Los Alamos National Laboratory. It is used as test bed for the much larger ZT-H, RFP experiment, now under construction at LANL. Planned experiments include size scaling measurements and determining the effect of low time constant measurements and determining the effect of low time constant shell operation. ZT-P has had an entirely passive equilibrium system, which did not provide a well centered equilibrium, although a tolerable equilibrium was realized by removing half of the equilibrium coil set. The transformer was added to the poloidal field system to adjust the equilibrium current for a centered plasma, while using the entire coil set. It also had the effect of reducing the dependence of the equilibrium on the plasma resistance. Stable, well centered discharges were achieved over a broad range of plasma currents. The improved equilibrium also lowered the loop voltage and extended the discharge lifetime. These experiments also investigated the unique problems of equilibrium systems on air core RFP devices. 26 refs., 6 figs.

Pickrell, M.M.; Reass, W.A.

1987-12-01

328

Determining Equilibrium Position For Acoustical Levitation  

NASA Technical Reports Server (NTRS)

Equilibrium position and orientation of acoustically-levitated weightless object determined by calibration technique on Earth. From calibration data, possible to calculate equilibrium position and orientation in presence of Earth gravitation. Sample not levitated acoustically during calibration. Technique relies on Boltzmann-Ehrenfest adiabatic-invariance principle. One converts resonant-frequency-shift data into data on normalized acoustical potential energy. Minimum of energy occurs at equilibrium point. From gradients of acoustical potential energy, one calculates acoustical restoring force or torque on objects as function of deviation from equilibrium position or orientation.

Barmatz, M. B.; Aveni, G.; Putterman, S.; Rudnick, J.

1989-01-01

329

1-D EQUILIBRIUM DISCRETE DIFFUSION MONTE CARLO  

SciTech Connect

We present a new hybrid Monte Carlo method for 1-D equilibrium diffusion problems in which the radiation field coexists with matter in local thermodynamic equilibrium. This method, the Equilibrium Discrete Diffusion Monte Carlo (EqDDMC) method, combines Monte Carlo particles with spatially discrete diffusion solutions. We verify the EqDDMC method with computational results from three slab problems. The EqDDMC method represents an incremental step toward applying this hybrid methodology to non-equilibrium diffusion, where it could be simultaneously coupled to Monte Carlo transport.

T. EVANS; ET AL

2000-08-01

330

Equilibrium coexistence of three amphiboles  

USGS Publications Warehouse

Electron probe and wet chemical analyses of amphibole pairs from the sillimanite zone of central Massachusetts and adjacent New Hampshire indicated that for a particular metamorphic grade there should be a restricted composition range in which three amphiboles can coexist stably. An unequivocal example of such an equilibrium three amphibole rock has been found in the sillimanite-orthoclase zone. It contains a colorless primitive clinoamphibole, space group P21/m, optically and chemically like cummingtonite with blue-green hornblende exsolution lamellae on (100) and (-101) of the host; blue-green hornblende, space group C2/m, with primitive cummingtonite exsolution lamellae on (100) and (-101) of the host; and pale pinkish tan anthophyllite, space group Pnma, that is free of visible exsolution lamellae but is a submicroscopic intergrowth of two orthorhombic amphiboles. Mutual contacts and coarse, oriented intergrowths of two and three host amphiboles indicate the three grew as an equilibrium assemblage prior to exsolution. Electron probe analyses at mutual three-amphibole contacts showed little variation in the composition of each amphibole. Analyses believed to represent most closely the primary amphibole compositions gave atomic proportions on the basis of 23 oxygens per formula unit as follows: for primitive cummingtonite (Na0.02Ca0.21- Mn0.06Fe2+2.28Mg4.12Al0.28) (Al0.17Si7.83), for hornblende (Na0.35Ca1.56Mn0.02Fe1.71Mg2.85Al0.92) (Al1.37Si6.63), and for anthophyllite (Na0.10Ca0.06Mn0.06Fe2.25Mg4.11Al0.47) (Al0.47Si7.53). The reflections violating C-symmetry, on X-ray single crystal photographs of the primitive cummingtonite, are weak and diffuse, and suggest a partial inversion from a C-centered to a primitive clinoamphibole. Single crystal photographs of the anthophyllite show split reflections indicating it is an intergrowth of about 80% anthophyllite and about 20% gedrite which differ in their b crystallographic dimensions. Split reflections are characteristic of all analyzed orthorhombic amphiboles so far examined from Massachusetts and New Hampshire except the most aluminous gedrites, and the relative intensity of the gedrite reflections is roughly proportional to the degree of Na and Al substitution. Thin sections of a few of these anthophyllite specimens show lamellae parallel to (010) that are just resolved with a high power objective. ?? 1969 Springer-Verlag.

Robinson, P.; Jaffe, H.W.; Klein, C., Jr.; Ross, M.

1969-01-01

331

EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE  

NASA Technical Reports Server (NTRS)

New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow-field information for the various shock-wave interference patterns and their associated maximum surface pressure and heat flux predictions. EASI is written in FORTRAN 77 for a DEC VAX 8500 series computer using the VAX/VMS operating system, and requires 75K of memory. The program is available on a 9-track 1600 BPI magnetic tape in DEC VAX BACKUP format. EASI was developed in 1989. DEC, VAX, and VMS are registered trademarks of the Digital Equipment Corporation.

Glass, C. E.

1994-01-01

332

The Rate-Controlled Constrained-Equilibrium Approach to Far-From-Local-Equilibrium Thermodynamics  

E-print Network

The Rate-Controlled Constrained-Equilibrium (RCCE) method for the description of the time-dependent behavior of dynamical systems in non-equilibrium states is a general, effective, physically based method for model order ...

Beretta, Gian Paolo

333

1 stepped pressure equilibrium code : hdfint 1 stepped pressure equilibrium code : hdfint 1  

E-print Network

1 stepped pressure equilibrium code : hdfint Contents 1 stepped pressure equilibrium code : hdfint enclosed by each interface; · pressure(1:Nvol); real; pressure in each volume; · iota(1:Nvol); real

Hudson, Stuart

334

Algorithmica manuscript Gaming Prediction Markets: Equilibrium Strategies  

E-print Network

Algorithmica manuscript Gaming Prediction Markets: Equilibrium Strategies with a Market Maker as it becomes available to anyone. A prediction market is a financial market specifically designed to take ad the equilibrium behavior of informed traders interacting with market scoring rule (MSR) market makers. One

Fortnow, Lance

335

The Stability of the NonEquilibrium  

E-print Network

non­equilibrium steady state (NESS) far from equilibrium has at­ tracted considerable interests. The NESS is introduced as a state asymptotically realized from an inhomogeneous initial state [11]­[12]. A question rises naturally here; is the NESS macroscopically stable? As an analogy of return to equilib­ rium

336

Pretirage INLN..... Non equilibrium statistical mechanics  

E-print Network

1 Pr´etirage INLN..... Non equilibrium statistical mechanics Michel Le Bellac Institut Non Lin In part I of these lecture notes, I introduce the basic tools of non equilibrium statistical mechanics statistical mechanics, all thermodynamics properties are derived from the partition func- tion: once

Paris-Sud XI, Université de

337

Zeroth Law, Entropy, Equilibrium, and All That  

ERIC Educational Resources Information Center

The place of the zeroth law in the teaching of thermodynamics is examined in the context of the recent discussion by Gislason and Craig of some problems involving the establishment of thermal equilibrium. The concept of thermal equilibrium is introduced through the zeroth law. The relation between the zeroth law and the second law in the…

Canagaratna, Sebastian G.

2008-01-01

338

Diphasic equilibrium and chemical engineering Francois JAMES  

E-print Network

Diphasic equilibrium and chemical engineering Fran¸cois JAMES Mathematical topics in fluid ). (2) This equality is nothing but the well-known equality of chemical potentials at equilibrium. We. Tech., Harlow, 1992, 246-250 1 Introduction Many processes in Chemical Engineering involve matter

d'Orléans, Université

339

Equilibrium : ConcFromKsp (8 Variations)  

NSDL National Science Digital Library

The K sp of BaF 2 is 1.7 x 10 -6 mol/L in water at 25 o C. What is the concentration of barium ions in equilibrium with solid barium fluoride? (Assume that the only relevant reaction is the solubility-product equilibrium.)

340

Wetting under chemical equilibrium and nonequilibrium conditions  

Microsoft Academic Search

The thermodynamics of a solid-liquid-vapor system both under chemical equilibrium and nonequilibrium conditions, based on the model of Gibbs, is discussed. Under chemical equilibrium conditions, the degree of wetting or nonwetting of a flat and nondeformable solid by the liquid is defined by Young's equation in terms of the static interfacial tensions. Under chemical nonequilibrium conditions, mass transfer across an

I. A. Aksay; Carl E. Hoge; Joseph A. Pask

1974-01-01

341

Chemical equilibrium systems as numerical test problems  

Microsoft Academic Search

A system of nonlinear equations has been used as a test case by at least two authors. This system is purported to describe the equilibrium of the products of hydrocarbon combustion. The given system does not describe the stated physical problem, a fact which invalidates it as a test of solution methods for chemical equilibrium systems. In this note, the

Keith Meintjes; Alexander P. Morgan

1990-01-01

342

Equilibrium Times for the Multicanonical Method  

Microsoft Academic Search

This work measures the time to equilibrium for the multicanonical method on the 2D-Ising system by using a new criterion, proposed here, to find the time to equilibrium, teq, of any sampling procedure based on a Markov process. Our new procedure gives the same results that the usual one, based on the magnetization, for the canonical Metropolis sampling on a

M. L. Guerra; J. D. Muñoz

2004-01-01

343

Disturbances in equilibrium function after major earthquake  

NASA Astrophysics Data System (ADS)

Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events.

Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi

2012-10-01

344

Disturbances in equilibrium function after major earthquake  

PubMed Central

Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events. PMID:23087814

Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi

2012-01-01

345

Local Nash Equilibrium in Social Networks  

NASA Astrophysics Data System (ADS)

Nash equilibrium is widely present in various social disputes. As of now, in structured static populations, such as social networks, regular, and random graphs, the discussions on Nash equilibrium are quite limited. In a relatively stable static gaming network, a rational individual has to comprehensively consider all his/her opponents' strategies before they adopt a unified strategy. In this scenario, a new strategy equilibrium emerges in the system. We define this equilibrium as a local Nash equilibrium. In this paper, we present an explicit definition of the local Nash equilibrium for the two-strategy games in structured populations. Based on the definition, we investigate the condition that a system reaches the evolutionary stable state when the individuals play the Prisoner's dilemma and snow-drift game. The local Nash equilibrium provides a way to judge whether a gaming structured population reaches the evolutionary stable state on one hand. On the other hand, it can be used to predict whether cooperators can survive in a system long before the system reaches its evolutionary stable state for the Prisoner's dilemma game. Our work therefore provides a theoretical framework for understanding the evolutionary stable state in the gaming populations with static structures.

Zhang, Yichao; Aziz-Alaoui, M. A.; Bertelle, Cyrille; Guan, Jihong

2014-08-01

346

Local Nash Equilibrium in Social Networks  

PubMed Central

Nash equilibrium is widely present in various social disputes. As of now, in structured static populations, such as social networks, regular, and random graphs, the discussions on Nash equilibrium are quite limited. In a relatively stable static gaming network, a rational individual has to comprehensively consider all his/her opponents' strategies before they adopt a unified strategy. In this scenario, a new strategy equilibrium emerges in the system. We define this equilibrium as a local Nash equilibrium. In this paper, we present an explicit definition of the local Nash equilibrium for the two-strategy games in structured populations. Based on the definition, we investigate the condition that a system reaches the evolutionary stable state when the individuals play the Prisoner's dilemma and snow-drift game. The local Nash equilibrium provides a way to judge whether a gaming structured population reaches the evolutionary stable state on one hand. On the other hand, it can be used to predict whether cooperators can survive in a system long before the system reaches its evolutionary stable state for the Prisoner's dilemma game. Our work therefore provides a theoretical framework for understanding the evolutionary stable state in the gaming populations with static structures. PMID:25169150

Zhang, Yichao; Aziz-Alaoui, M. A.; Bertelle, Cyrille; Guan, Jihong

2014-01-01

347

Local Nash equilibrium in social networks.  

PubMed

Nash equilibrium is widely present in various social disputes. As of now, in structured static populations, such as social networks, regular, and random graphs, the discussions on Nash equilibrium are quite limited. In a relatively stable static gaming network, a rational individual has to comprehensively consider all his/her opponents' strategies before they adopt a unified strategy. In this scenario, a new strategy equilibrium emerges in the system. We define this equilibrium as a local Nash equilibrium. In this paper, we present an explicit definition of the local Nash equilibrium for the two-strategy games in structured populations. Based on the definition, we investigate the condition that a system reaches the evolutionary stable state when the individuals play the Prisoner's dilemma and snow-drift game. The local Nash equilibrium provides a way to judge whether a gaming structured population reaches the evolutionary stable state on one hand. On the other hand, it can be used to predict whether cooperators can survive in a system long before the system reaches its evolutionary stable state for the Prisoner's dilemma game. Our work therefore provides a theoretical framework for understanding the evolutionary stable state in the gaming populations with static structures. PMID:25169150

Zhang, Yichao; Aziz-Alaoui, M A; Bertelle, Cyrille; Guan, Jihong

2014-01-01

348

The Conceptual Change Approach to Teaching Chemical Equilibrium  

ERIC Educational Resources Information Center

This study investigates the effect of a conceptual change approach over traditional instruction on students' understanding of chemical equilibrium concepts (e.g. dynamic nature of equilibrium, definition of equilibrium constant, heterogeneous equilibrium, qualitative interpreting of equilibrium constant, changing the reaction conditions). This…

Canpolat, Nurtac; Pinarbasi, Tacettin; Bayrakceken, Samih; Geban, Omer

2006-01-01

349

On the concept chemical equilibrium: The associative framework  

Microsoft Academic Search

Word associations were used to map the conception of high school students concerning the concepts chemical equilibrium and equilibrium. It was found that the preconception of the two concepts was differentiated on noncritical dimensions; equilibrium being associated with everyday life experiences and chemical equilibrium with general chemical concepts. After studying the subject of chemical equilibrium at school the two concepts

Esther Gussarsky; Malka Gorodetsky

1990-01-01

350

Teaching Chemical Equilibrium with the Jigsaw Technique  

NASA Astrophysics Data System (ADS)

This study investigates the effect of cooperative learning (jigsaw) versus individual learning methods on students’ understanding of chemical equilibrium in a first-year general chemistry course. This study was carried out in two different classes in the department of primary science education during the 2005-2006 academic year. One of the classes was randomly assigned as the non-jigsaw group (control) and other as the jigsaw group (cooperative). Students participating in the jigsaw group were divided into four “home groups” since the topic chemical equilibrium is divided into four subtopics (Modules A, B, C and D). Each of these home groups contained four students. The groups were as follows: (1) Home Group A (HGA), representin g the equilibrium state and quantitative aspects of equilibrium (Module A), (2) Home Group B (HGB), representing the equilibrium constant and relationships involving equilibrium constants (Module B), (3) Home Group C (HGC), representing Altering Equilibrium Conditions: Le Chatelier’s principle (Module C), and (4) Home Group D (HGD), representing calculations with equilibrium constants (Module D). The home groups then broke apart, like pieces of a jigsaw puzzle, and the students moved into jigsaw groups consisting of members from the other home groups who were assigned the same portion of the material. The jigsaw groups were then in charge of teaching their specific subtopic to the rest of the students in their learning group. The main data collection tool was a Chemical Equilibrium Achievement Test (CEAT), which was applied to both the jigsaw and non-jigsaw groups The results indicated that the jigsaw group was more successful than the non-jigsaw group (individual learning method).

Doymus, Kemal

2008-03-01

351

Chlorodifluoromethane equilibrium on 13X molecular sieve  

NASA Astrophysics Data System (ADS)

Adsorption phase equilibrium data are required for evaluating any adsorption-based gas separation process. The U.S. Army Edgewood Research, Development and Engineering Center is currently measuring adsorption phase equilibrium data for a variety of chemical warfare agents and their surrogates on adsorbent materials to correlate physical properties to filtration/separation efficiencies of each vapor on each adsorbent. This report details the adsorption phase equilibrium data measured for chlorodifluoromethane (R-22) on 13X Molecular Sieve. The 13X Molecular Sieve is a candidate adsorbent for future military air purification systems employing the pressure-swing adsorption separation process.

Carlile, Donna L.; Mahle, John J.; Buettner, Leonard C.; Tevault, David E.; Friday, David K.

1994-08-01

352

Energy Spectrum of equilibrium Black Holes  

E-print Network

Taking cue from the knowledge of the quantum theory of gravity at our disposal in the form of loop quantum gravity, a model Hamiltonian operator for the quantum theory of equilibrium black hole horizons, modeled as isolated horizons, is proposed. Using equilibrium statistical mechanical methods we derive the first law of isolated horizon mechanics. Seeking that the result should be compatible with the one derived from the classical theory, the unknown coefficients and parameters of the Hamiltonian operator are fixed, yielding the energy spectrum of equilibrium black holes.

Abhishek Majhi

2014-09-20

353

Equilibrium Kawasaki dynamics of continuous particle systems  

E-print Network

We construct a new equilibrium dynamics of infinite particle systems in a Riemannian manifold $X$. This dynamics is an analog of the Kawasaki dynamics of lattice spin systems. The Kawasaki dynamics now is a process where interacting particles randomly hop over $X$. We establish conditions on the {\\it a priori} explicitly given symmetrizing measure and the generator of this dynamics, under which a corresponding conservative Markov processes exists. We also outline two types of scaling limit of the equilibrium Kawasaki dynamics: one leading to an equilibrium Glauber dynamics in continuum (a birth-and-death process), and the other leading to a diffusion dynamics of interacting particles (in particular, the gradient stochastic dynamics).

Yu. G. Kondratiev; E. Lytvynov; M. Röckner

2007-02-08

354

Default and Punishment in General Equilibrium1  

Microsoft Academic Search

Abstract We extend,the standard,model,of general equilibrium,with incomplete,mar- kets to allow for default and punishment.,The equilibrating variables include expected delivery rates, along with the usual prices of assets and commodities.

Pradeep Dubey; John Geanakoplos; Martin Shubik

2005-01-01

355

An Equilibrium Model of Rare Event Premia  

E-print Network

In this paper, we study the asset pricing implication of imprecise knowledge about rare events. Modeling rare events as jumps in the aggregate endowment, we explicitly solve the equilibrium asset prices in a pure-exchange ...

Liu, Jun

2002-08-12

356

Adaptive radiation: convergence and non-equilibrium.  

PubMed

The spectacular adaptive radiation of cichlid fish in Lake Tanganyika encompasses extensive morphological convergence and co-occurrence of ecologically similar species, forcing a reevaluation of non-equilibrium dynamics in community assembly. PMID:23347943

Gillespie, Rosemary G

2013-01-21

357

An Elementary Discussion of Chemical Equilibrium.  

ERIC Educational Resources Information Center

This discussion uses a more difficult reaction as the prototype to derive the standard equation for chemical equilibrium. It can be used by students who can understand and use partial derivatives. (CW)

David, Carl W.

1988-01-01

358

Spreadsheet Templates for Chemical Equilibrium Calculations.  

ERIC Educational Resources Information Center

Describes two general spreadsheet templates to carry out all types of one-equation chemical equilibrium calculations encountered by students in undergraduate chemistry courses. Algorithms, templates, macros, and representative examples are presented to illustrate the approach. (PR)

Joshi, Bhairav D.

1993-01-01

359

Equilibrium Reconstruction on the Large Helical Device  

SciTech Connect

Equilibrium reconstruction is commonly applied to axisymmetric toroidal devices. Recent advances in computational power and equilibrium codes have allowed for reconstructions of three-dimensional fields in stellarators and heliotrons. We present the first reconstructions of finite beta discharges in the Large Helical Device (LHD). The plasma boundary and magnetic axis are constrained by the pressure profile from Thomson scattering. This results in a calculation of plasma beta without a-priori assumptions of the equipartition of energy between species. Saddle loop arrays place additional constraints on the equilibrium. These reconstruction utilize STELLOPT, which calls VMEC. The VMEC equilibrium code assumes good nested flux surfaces. Reconstructed magnetic fields are fed into the PIES code which relaxes this constraint allowing for the examination of the effect of islands and stochastic regions on the magnetic measurements.

Samuel A. Lazerson, D. Gates, D. Monticello, H. Neilson, N. Pomphrey, A. Reiman S. Sakakibara, and Y. Suzuki

2012-07-27

360

14 CFR 67.205 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2011 CFR

... 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.205...Second-Class Airman Medical Certificate § 67.205 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2011-01-01

361

14 CFR 67.305 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2013 CFR

... 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.305...Third-Class Airman Medical Certificate § 67.305 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2013-01-01

362

14 CFR 67.205 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2012 CFR

... 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.205...Second-Class Airman Medical Certificate § 67.205 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2012-01-01

363

14 CFR 67.205 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2010 CFR

... 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.205...Second-Class Airman Medical Certificate § 67.205 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2010-01-01

364

14 CFR 67.105 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2012 CFR

... 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.105...First-Class Airman Medical Certificate § 67.105 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2012-01-01

365

14 CFR 67.205 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2013 CFR

... 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.205...Second-Class Airman Medical Certificate § 67.205 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2013-01-01

366

14 CFR 67.305 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2012 CFR

... 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.305...Third-Class Airman Medical Certificate § 67.305 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2012-01-01

367

14 CFR 67.305 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2010 CFR

... 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.305...Third-Class Airman Medical Certificate § 67.305 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2010-01-01

368

14 CFR 67.105 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2014 CFR

... 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.105...First-Class Airman Medical Certificate § 67.105 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2014-01-01

369

14 CFR 67.305 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2014 CFR

... 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.305...Third-Class Airman Medical Certificate § 67.305 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2014-01-01

370

14 CFR 67.105 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2013 CFR

... 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.105...First-Class Airman Medical Certificate § 67.105 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2013-01-01

371

14 CFR 67.305 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2011 CFR

... 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.305...Third-Class Airman Medical Certificate § 67.305 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2011-01-01

372

14 CFR 67.105 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2011 CFR

... 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.105...First-Class Airman Medical Certificate § 67.105 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2011-01-01

373

14 CFR 67.105 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2010 CFR

... 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.105...First-Class Airman Medical Certificate § 67.105 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2010-01-01

374

14 CFR 67.205 - Ear, nose, throat, and equilibrium.  

Code of Federal Regulations, 2014 CFR

... 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.205...Second-Class Airman Medical Certificate § 67.205 Ear, nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards...

2014-01-01

375

Edge Equilibrium Code (EEC) For Tokamaks  

SciTech Connect

The edge equilibrium code (EEC) described in this paper is developed for simulations of the near edge plasma using the finite element method. It solves the Grad-Shafranov equation in toroidal coordinate and uses adaptive grids aligned with magnetic field lines. Hermite finite elements are chosen for the numerical scheme. A fast Newton scheme which is the same as implemented in the equilibrium and stability code (ESC) is applied here to adjust the grids

Li, Xujling

2014-02-24

376

Formation of garnet + corundum during isobaric cooling at UHT conditions: an example from pelitic granulites of the Highland Complex, Sri Lanka  

NASA Astrophysics Data System (ADS)

Coexisting garnet and corundum have been reported from different rock types such as UHP rocks, aluminous eclogites, kimberlites and numerous granulites worldwide which experienced UHT conditions of 900-1050 °C at relatively high but not eclogitic pressures of 10-12 kbar. In pelitic granulites the assemblage garnet + corundum is usually interpreted to form at peak P during prograde heating along a clock-wise metamorphic path and subsequently breaks down during decompression to form sapphirine, cordierite-sapphirine-spinel or spinel-sillimanite bearing assemblages, depending on the PT-trajectory and bulk rock composition. In any cases, coexisting garnet + corundum are rarely preserved. Even less usual is the occurrence of garnet + corundum in pyroxene-free rocks. In this study, we report the occurrence of coexisting garnet + corundum within spinel- and corundum-bearing, orthopyroxene-free garnet-sillimanite-biotite-graphite gneisses from the Highland Complex (HC), Sri Lanka. In the investigated pelitic granulites, quartz-saturated domains and quartz-deficient domains are distinguishable. Quartz-saturated domains consist of quartz, plagioclase, alkali-feldspar, garnet-porphyroblasts and biotite flakes around garnet. Quartz-deficient domains are constituted of sillimanite, plagioclase, alkali-feldspar, corundum, spinel, biotite and two generations of garnet. Grt1 is coarse- to medium-grained (0.5-3 cm in diameter) and encloses rare Ti-rich biotite and numerous rutile needles and apatite rods. Grt2 is medium- to fine-grained (0.25-1 cm in diameter), contains rare sillimanite and/or spinel inclusions and is always associated with corundum. Corundum occurs in mutual contact with Grt2, partially embedded within rim area of Grt2 or as inclusions in Grt2. Rarely, tiny spinel inclusions can be observed in corundum. The chemistry of minerals preserved as inclusion in Grt1 indicates that pelitic granulites attained maximal P of 10.5-11 kbar at T around 850°C during their prograde history. Further heating induced a series of biotite-melting reactions which progressively consumed biotite and quartz from the rock matrix and produced garnet-porphyroblasts and spinel. Textural observations coupled with both pseudosections calculated in the CNKFMASHTMnO system and Ti-in-garnet geothermobarometry suggest that peak metamorphic temperature occurred at UHT conditions of 950-975 0C and pressures of 9-9.5 kbar. Peak T was followed by a period of isobaric cooling responsible for the formation of corundum and Grt2 via the reaction Spl + Sil = Grt2 + Crn at around 930 °C, as well as exsolution of rutile needles and apatite rods from Grt1. Modelling of the mode of spinel, sillimanite, corundum and garnet confirms that along an isobaric cooling path at about 920-930 °C and 9-9.5 kbar corundum appears and spinel contemporaneously disappears. At the same PT conditions, our model predicts a decrease of sillimanite and an increase of garnet content. Further isobaric cooling produced a second generation of biotite at the rim of large Grt1-porphyroblasts at ca. 800 °C. Therefore, the investigated granulites provide a rare but meaningful example where garnet + corundum formed along a retrograde metamorphic trajectory under UHT conditions, forcing to consider isobaric cooling at the base of the crust as an alternative process to explain the formation of coexisting garnet + corundum, especially if the studied rock lacks of cordierite or orthopyroxene.

Laksthitha Dharmapriya, Prasanna; Galli, Andrea; Prabath Malaviarachchi, Sanjeeva; Su, Ben-Xun

2014-05-01

377

Isobaric-Isothermal Molecular Dynamics Utilizing Density Functional Theory: An Assessment of the Structure and Density of Water at Near-Ambient Conditions  

SciTech Connect

We present herein a comprehensive density functional theory study toward assessing the accuracy of two popular gradient-corrected exchange correlation functionals on the structure and density of liquid water at near ambient conditions in the isobaric-isothermal ensemble. Our results indicate that both PBE and BLYP functionals under predict the density and over structure the liquid. Adding the dispersion correction due to Grimme(1, 2) improves the predicted densities for both BLYP and PBE in a significant manner. Moreover, the addition of the dispersion correction for BLYP yields an oxygen-oxygen radial distribution function in excellent agreement with experiment. Thus, we conclude that one can obtain a very satisfactory model for water using BLYP and a correction for dispersion.

Schmidt, J; VandeVondele, J; Kuo, I W; Sebastiani, D; Siepmann, J I; Hutter, J; Mundy, C J

2009-03-06

378

Theory for non-equilibrium statistical mechanics.  

PubMed

This paper reviews a new theory for non-equilibrium statistical mechanics. This gives the non-equilibrium analogue of the Boltzmann probability distribution, and the generalization of entropy to dynamic states. It is shown that this so-called second entropy is maximized in the steady state, in contrast to the rate of production of the conventional entropy, which is not an extremum. The relationships of the new theory to Onsager's regression hypothesis, Prigogine's minimal entropy production theorem, the Langevin equation, the formula of Green and Kubo, the Kawasaki distribution, and the non-equilibrium fluctuation and work theorems, are discussed. The theory is worked through in full detail for the case of steady heat flow down an imposed temperature gradient. A Monte Carlo algorithm based upon the steady state probability density is summarized, and results for the thermal conductivity of a Lennard-Jones fluid are shown to be in agreement with known values. Also discussed is the generalization to non-equilibrium mechanical work, and to non-equilibrium quantum statistical mechanics. As examples of the new theory two general applications are briefly explored: a non-equilibrium version of the second law of thermodynamics, and the origin and evolution of life. PMID:16883388

Attard, Phil

2006-08-21

379

Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization  

NASA Astrophysics Data System (ADS)

An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded `fixed charge' sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptides with S, S'-dimethylthiobutanoylhydroxysuccinimide ester iodide (DMBNHS), followed by analysis using capillary HPLC-ESI-MS, yielded an average 2.5-fold increase in ionization efficiencies and a significant increase in the presence and/or abundance of higher charge state precursor ions compared to the non-derivatized phosphopeptides. Notably, 44% of the phosphopeptides (22 of 50) in their underivatized states yielded precursor ions whose maximum charge states corresponded to +2, while only 8% (4 of 50) remained at this maximum charge state following DMBNHS derivatization. Quantitative analysis was achieved by measuring the abundances of the diagnostic product ions corresponding to the neutral losses of `light' (S(CH3)2) and `heavy' (S(CD3)2) dimethylsulfide exclusively formed upon CID-MS/MS of isobaric stable isotope labeled forms of the DMBNHS derivatized phosphopeptides. Under these conditions, the phosphate group stayed intact. Access for a greater number of peptides to provide enhanced phosphopeptide sequence identification and phosphorylation site characterization was achieved via automated data-dependent CID-MS3 or ETD-MS/MS analysis due to the formation of the higher charge state precursor ions. Importantly, improved sequence coverage was observed using ETD-MS/MS following introduction of the sulfonium ion fixed charge, but with no detrimental effects on ETD fragmentation efficiency.

Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

2012-04-01

380

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

SciTech Connect

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

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

1982-01-01

381

On the equilibrium profile of river beds  

NASA Astrophysics Data System (ADS)

Despite the wide spectrum of perturbations of flow and sediment transport experienced by rivers as a result of hydrologic variations, the paradigm of morphodynamic equilibrium has long been present in the geomorphological literature where it is traditionally associated with the semiempirical notion of formative discharge, whereby the unsteady forcing is taken as morphologically equivalent to some effective steady forcing. Here we investigate the mechanisms responsible for maintaining a quasi-equilibrium bed profile of a river reach sufficiently short to have no significant tributary inputs. More importantly, we assume the channel banks to be fixed, hence, the case we have in mind is that of rivers protected by levees which cannot respond to hydrologic forcing by changing their width like natural rivers. Employing a 1-D model of river morphodynamics, we first determine the equilibrium profile of the river reach for given steady forcing conditions and discuss the capability of this approach for interpreting bed profiles observed in the field by applying it to the terminal reach of the Magra River, Italy. Field observations turn out to be reasonably well fitted by the equilibrium profile associated with a steady effective discharge, which however differs from the typical formative discharge (mean annual flood) for natural channels with erodible banks. Finally, we clarify how fluctuations of the hydrodynamic forcing associated with the recorded historical sequence of hydrologic events of variable intensities have acted to maintain the river equilibrium.

Bolla Pittaluga, M.; Luchi, R.; Seminara, G.

2014-02-01

382

Development of a thermal equilibrium prediction algorithm.  

SciTech Connect

A thermal equilibrium prediction algorithm is developed and tested using a heat conduction model and data sets from calorimetric measurements. The physical model used in this study is the exact solution of a system of two partial differential equations that govern the heat conduction in the calorimeter. A multi-parameter estimation technique is developed and implemented to estimate the effective volumetric heat generation and thermal diffusivity in the calorimeter measurement chamber, and the effective thermal diffusivity of the heat flux sensor. These effective properties and the exact solution are used to predict the heat flux sensor voltage readings at thermal equilibrium. Thermal equilibrium predictions are carried out considering only 20% of the total measurement time required for thermal equilibrium. A comparison of the predicted and experimental thermal equilibrium voltages shows that the average percentage error from 330 data sets is only 0.1% . The data sets used in this study come from calorimeters of different sizes that use different kinds of heat flux sensors. Furthermore, different nuclear material matrices were assayed in the process of generating these data sets. This study shows that the integration of this algorithm into the calorimeter data acquisition software will result in an 80% reduction of measurement time. This reduction results in a significant cutback in operational costs for the calorimetric assay of nuclear materials.

Aviles-Ramos, C. (Cuauhtemoc)

2001-01-01

383

Quasi-equilibrium and non-equilibrium adsorption in heterogeneous photocatalysis  

Microsoft Academic Search

Heterogeneous photocatalysis is a promising alternative for the removal of organic and inorganic pollutants in water. Some chemical species display a strong and slow surface adsorption kinetics reacting under non-equilibrium while others adsorb quickly and moderately with adsorption taking place under quasi-equilibrium. In the specific case of a given pollutant once the intrinsic kinetic constants are evaluated, one can establish

Benito Serrano; Miguel Salaices; Aaron Ortiz; Hugo I. de Lasa

2007-01-01

384

Computational Market Equilibrium Yinyu Ye, WINE2008 1 Computational Economy Equilibrium and its Application  

E-print Network

: Market "Fairness" or "Cruelty" For every good i, j xij good i is a "free" good by trader j Then, xij, pi, i, j = 1, . . . , n, is a market equilibrium if and only if it meets following-Debreu competitive market equilibrium · Each of a population of n agents has an initial endowment of divisible goods

Ye, Yinyu

385

Non--Equilibrium Blunt Body Flow 1 Analysis of NonEquilibrium, Hypersonic Blunt  

E-print Network

and Navier--Stokes calculations and experiments are presented, which include perfect gas flows and nonNon--Equilibrium Blunt Body Flow 1 Analysis of Non­Equilibrium, Hypersonic Blunt Body Flow Aachen Templergraben 64, 52056 Aachen, Germany Abstract: A method for the calculation of the stagnation

386

A Coupled Model for Radiative Transfer: Doppler Effects, Equilibrium and Non-Equilibrium Diffusion Asymptotics  

E-print Network

A Coupled Model for Radiative Transfer: Doppler Effects, Equilibrium and Non-Equilibrium Diffusion. The interaction terms take into account both scattering and absorption/emission phenomena, as well as Doppler-diffusion equations. Key words. Hydrodynamic limits. Diffusion approximation. Radiative transfer. Doppler correction

Goudon, Thierry

387

Equilibrium dialysis using chromophoric sugar derivatives.  

PubMed

Equilibrium dialysis has been used to examine the binding affinity of ligands to proteins. It is a simple and reliable method, which requires only inexpensive equipment. For analysis of lectin-sugar interactions, the lectin and sugar are placed in the individual chambers separated by the membrane to allow the sugar to diffuse into the lectin chamber. After equilibrium has been reached, the concentrations of the sugar in both chambers are determined to evaluate the sugar-binding affinity of lectin. In this chapter, an example of the equilibrium dialysis experiment using the chromophoric derivatives of galactose and N-acetylgalactosamine is demonstrated, which reveals the difference in the affinity as well as specificities of two different carbohydrate-binding sites present in the B-chains of the plant lectin ricin. PMID:25117234

Hatakeyama, Tomomitsu

2014-01-01

388

Analytic prediction of airplane equilibrium spin characteristics  

NASA Technical Reports Server (NTRS)

The nonlinear equations of motion are solved algebraically for conditions for which an airplane is in an equilibrium spin. Constrained minimization techniques are employed in obtaining the solution. Linear characteristics of the airplane about the equilibrium points are also presented and their significance in identifying the stability characteristics of the equilibrium points is discussed. Computer time requirements are small making the method appear potentially applicable in airplane design. Results are obtained for several configurations and are compared with other analytic-numerical methods employed in spin prediction. Correlation with experimental results is discussed for one configuration for which a rather extensive data base was available. A need is indicated for higher Reynolds number data taken under conditions which more accurately simulate a spin.

Adams, W. M., Jr.

1972-01-01

389

Equilibrium analysis of zirconium carbide CVD growth  

NASA Astrophysics Data System (ADS)

A chemical equilibrium study was performed to investigate the effect of growth parameters on the constitution in ZrC films grown by chemical vapor deposition (CVD). The equilibrium analysis of the Zr-C-H system demonstrated that ZrC (fcc) deposition is favorable and that a certain minimum amount of hydrogen should prevent co-deposition of elemental carbon over a wide range of temperature, pressure, and inlet C/Zr atom ratio. The results of the equilibrium analysis were compared to the phase constitution of films grown by low-pressure metalorganic CVD (<10 -4 Torr). Only carbon-rich ZrC films were grown and demonstrated the possibility of an aerosol-assisted CVD approach to stoichiometric ZrC film growth.

Won, Yong Sun; Varanasi, Venu G.; Kryliouk, Olga; Anderson, Timothy J.; McElwee-White, Lisa; Perez, Rosa J.

2007-09-01

390

Misconceptions of students and teachers in chemical equilibrium  

Microsoft Academic Search

A written test was developed and administered to diagnose misconceptions in different areas of chemical equilibrium among 162 undergraduate chemistry students and 69 school?teachers of chemistry. Analysis of the responses reveal widespread misconceptions among both students and teachers in areas related to the prediction of equilibrium conditions, rate and equilibrium, applying equilibrium principles to daily life, and to acid?base and

Anil C. Banerjee

1991-01-01

391

Isodynamic axisymmetric equilibrium near the magnetic axis  

SciTech Connect

Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo’s configuration)

Arsenin, V. V., E-mail: arsenin@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)

2013-08-15

392

Algorithm For Hypersonic Flow In Chemical Equilibrium  

NASA Technical Reports Server (NTRS)

Implicit, finite-difference, shock-capturing algorithm calculates inviscid, hypersonic flows in chemical equilibrium. Implicit formulation chosen because overcomes limitation on mathematical stability encountered in explicit formulations. For dynamical portion of problem, Euler equations written in conservation-law form in Cartesian coordinate system for two-dimensional or axisymmetric flow. For chemical portion of problem, equilibrium state of gas at each point in computational grid determined by minimizing local Gibbs free energy, subject to local conservation of molecules, atoms, ions, and total enthalpy. Major advantage: resulting algorithm naturally stable and captures strong shocks without help of artificial-dissipation terms to damp out spurious numerical oscillations.

Palmer, Grant

1989-01-01

393

Computing Properties Of Chemical Mixtures At Equilibrium  

NASA Technical Reports Server (NTRS)

Scientists and engineers need data on chemical equilibrium compositions to calculate theoretical thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93 is general program that calculates chemical equilibrium compositions and properties of mixtures for any chemical system for which thermodynamic data are available. Includes thermodynamic data for more than 1,300 gaseous and condensed species and thermal-transport data for 151 gases. Written in FORTRAN 77.

Mcbride, B. J.; Gordon, S.

1995-01-01

394

Problems on Non-Equilibrium Statistical Physics  

E-print Network

PROBLEMS ON NON-EQUILIBRIUM STATISTICAL PHYSICS A Dissertation by MOOCHAN KIM Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2010 Major... Subject: Physics PROBLEMS ON NON-EQUILIBRIUM STATISTICAL PHYSICS A Dissertation by MOOCHAN KIM Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of DOCTOR OF PHILOSOPHY...

Kim, Moochan

2011-08-08

395

A randomized clinical study comparing spinal anesthesia with isobaric levobupivacaine with fentanyl and hyperbaric bupivacaine with fentanyl in elective cesarean sections  

PubMed Central

Background: To date, racemic bupivacaine is the most popular local anesthetic for spinal anesthesia in parturients undergoing elective cesarean delivery. With the introduction of levobupivacaine as pure S (–) enantiomer of bupivacaine which offers advantages of lower cardiotoxicity and neurotoxicity and shorter motor block duration, its use has widely increased in India. However, very few studies have been conducted about its efficacy in obstetric anesthesia. Thus, this study was undertaken to compare the sensorial, motor block levels, and side-effects of equal doses of hyperbaric bupivacaine and levobupivacaine with intrathecal fentanyl addition in elective cesarean cases. Materials and Methods: After approval of College Ethical Committee, 30 parturient with American Society of Anesthesiologists I-II undergoing elective cesarean section were enrolled for study with their informed consent. They were randomly divided equally to either Group BF receiving 10 mg (2 ml) hyperbaric bupivacaine and 25 mcg (0.5 ml) fentanyl, or Group LF receiving 10 mg (2 ml) isobaric levobupivacaine and 25 mcg (0.5 ml) fentanyl. Sensory and motor block characteristics of the groups were assessed with pinprick, cold swab, and Bromage scale; observed hemodynamic changes and side-effects were recorded. Effects on the neonate were observed by APGAR score at 1 and 5 min and umbilical cord blood gas analysis. Results: Hemodynamic parameters like mean arterial pressure of Group BF were found to be lower. Group BF exhibited maximum motor block level whereas in Group LF, max sensorial block level and postoperative visual analog scale scores were higher. Umbilical blood gas pCO2 was slightly higher, and pO2 was marginally lower in Group BF. Onset of motor block time, time to max motor block, time to T10 sensorial block, reversal of two dermatome, the first analgesic need were similar in both groups. Conclusion: Intrathecal isobaric levobupivacaine-fentanyl combination is a good alternative to hyperbaric bupivacaine-fentanyl combination in cesarean surgery as it is less effective in motor block, it maintains hemodynamic stability at higher sensorial block levels.

Goyal, Ayesha; Shankaranarayan, P.; Ganapathi, P.

2015-01-01

396

Equilibrium states of Runge Kutta schemes  

Microsoft Academic Search

Understanding the behavior of Runge-Kutta codes when stability considerations restrict the stepsize provides useful information for stiffness detection and other implementation details. Analysis of equilibrium states on test problems is presented which provides predictions and insights into this behavior. The implications for global error are also discussed.

George Hall

1985-01-01

397

FAST plasma scenarios and equilibrium configurations  

Microsoft Academic Search

In this paper we present the fusion advanced studies torus (FAST) plasma scenarios and equilibrium configurations, designed to reproduce the ITER ones (with scaled plasma current) and suitable to fulfil plasma conditions for integrated studies of plasma-wall interaction, burning plasma physics, ITER relevant operation problems and steady state scenarios. The attention is focused on FAST flexibility in terms of both

G. Calabrò; F. Crisanti; G. Ramogida; R. Albanese; A. Cardinali; A. Cucchiaro; G. Granucci; G. Maddaluno; M. Marinucci; S. Nowak; A. Pizzuto; V. Pericoli Ridolfini; A. Pironti; A. A. Tuccillo; F. Zonca

2009-01-01

398

Network Equilibrium of Heterogeneous Congestion Control Protocols  

E-print Network

Abstract-- When heterogeneous congestion control protocols that react to different pricing signals share sources and links that use a large class of algorithms to adapt their rates and congestion prices. Often1 Network Equilibrium of Heterogeneous Congestion Control Protocols Ao Tang Jiantao Wang Steven H

Low, Steven H.

399

Muslims in France: Identifying a discriminatory equilibrium.  

E-print Network

Muslims in France: Identifying a discriminatory equilibrium. Claire L. Adida David D. Laitin Marie-Anne Valfort§ July 3, 2013 Abstract We analyze the assimilation patterns of Muslim immigrants in Western suggest that Muslims and rooted French are locked in a sub-optimal equilib- rium whereby (i) rooted French

Boyer, Edmond

400

Amazon Basin: A System in Equilibrium  

Microsoft Academic Search

Despite the very active deforestation of the last decade, the Amazon Basin is still primarily covered with trees and is a system in equilibrium. The Andes form a barrier at the western end of the basin and, coupled with the prevailing easterly winds, ensure an almost unique precipitation and water-recycling regime. On average 50 percent of the precipitation is recycled,

Eneas Salati; Peter B. Vose

1984-01-01

401

Macroeconomic Theory: A Dynamic General Equilibrium Approach  

E-print Network

Macroeconomic Theory: A Dynamic General Equilibrium Approach Mike Wickens University of York.e. without first taking deviations about trend growth. (a) Derive the Euler equation (b) Discuss the steady-state and labor augmenting technical progress. (a) Show that the model has constant steady-state growth when

Landweber, Laura

402

Payload specialists Patrick Baudry conducts equilibrium experiments  

NASA Technical Reports Server (NTRS)

Payload specialists Patrick Baudry participates in an experiment involving equilibrium and vertigo. He is anchored to the orbiter floor by foot restraints and is wearing a device over his eyes to measure angular head movement and up and down eye movement.

1985-01-01

403

Survival, Uncertainty, and Equilibrium Theory: An Exposition  

Microsoft Academic Search

The last twenty years have witnessed a significant growth of the literature on the “survival problem”, primarily in the context of the causes and remedies of famines. Once a subject essentially of empirical development economics, economic survival became an issue of analytical economics and, most recently, of general equilibrium theory. We review several issues of the survival problem in the

Mukul Majumdar; Nigar Hashimzade

2004-01-01

404

Multifrequency jump-diffusions: An equilibrium approach  

Microsoft Academic Search

This paper proposes that equilibrium valuation is a powerful method to generate endogenous jumps in asset prices. We specify an economy with continuous consumption and dividend paths, in which endogenous price jumps originate from the market impact of regime-switches in the drifts and volatilities of fundamentals. We parsimoniously incorporate regimes of heterogeneous durations and verify that the persistence of a

Laurent E. Calvet; Adlai J. Fisher

2008-01-01

405

Equilibrium Analysis in Cake Cutting Simina Brnzei  

E-print Network

Equilibrium Analysis in Cake Cutting Simina Brânzei Department of Computer Science Aarhus@cs.au.dk ABSTRACT Cake cutting is a fundamental model in fair division; it repre- sents the problem of fairly. In this paper, we initiate the study of equilibria of classical cake cutting protocols. We consider one

Miltersen, Peter Bro

406

Non-equilibrium Dynamics of DNA Nanotubes  

E-print Network

Non-equilibrium Dynamics of DNA Nanotubes Thesis by Rizal Fajar Hariadi In Partial Fulfillment the interesting structural features of DNA nanotubes during my candidacy. Within the DNA and Natural Algorithms nanotubes. Jongmin Kim pursued a project exploring in vitro tran- scription of the RNA tiles with me. Even

Winfree, Erik

407

Equilibrium resource management with altruistic overlapping generations  

E-print Network

Equilibrium resource management with altruistic overlapping generations Ivar Ekeland Larry Karp follows a Most Rapid Approach Path to a steady state, into an overlapping generations setting. The current generation discounts future generations' utility flows at a rate pos- sibly different from the pure rate

Kammen, Daniel M.

408

Non-equilibrium spatial dynamics of ecosystems.  

PubMed

Ecological systems show tremendous variability across temporal and spatial scales. It is this variability that ecologists try to predict and that managers attempt to harness in order to mitigate risk. However, the foundations of ecological science and its mainstream agenda focus on equilibrium dynamics to describe the balance of nature. Despite a rich body of literature on non-equilibrium ecological dynamics, we lack a well-developed set of predictions that can relate the spatiotemporal heterogeneity of natural systems to their underlying ecological processes. We argue that ecology needs to expand its current toolbox for the study of non-equilibrium ecosystems in order to both understand and manage their spatiotemporal variability. We review current approaches and outstanding questions related to the study of spatial dynamics and its application to natural ecosystems, including the design of reserves networks. We close by emphasizing the importance of ecosystem function as a key component of a non-equilibrium ecological theory, and of spatial synchrony as a central phenomenon for its inference in natural systems. PMID:24984261

Guichard, Frederic; Gouhier, Tarik C

2014-09-01

409

Equilibrium analysis, banking, contagion and financial fragility  

Microsoft Academic Search

In this paper a general equilibrium model of an economy with incomplete markets (GEI) with money and default is examined. The model is a simplified version of the real world consisting of a non-bank private sector, banks, a central bank, a government and a regulator. It is used to analyse actions by policy-makers and to identify policy relevant empirical work.

Dimitrios P. Tsomocos

2003-01-01

410

Equilibrium analysis, banking and financial instability  

Microsoft Academic Search

This paper first extends the canonical General Equilibrium with Incomplete Markets (GEI) model with money and default to allow for competitive banking and financial instability. Second, it introduces capital requirements for the banking sector to assess the short and medium term macroeconomic consequences of the proposed New Basel Accord. Monetary Equilibria with Commercial Banks and Default (MECBD) exist and financial

Dimitrios P. Tsomocos

2003-01-01

411

Non-equilibrium current via geometric scatterers  

E-print Network

We investigate non-equilibrium particle transport in the system consisting of a geometric scatterer and two leads coupled to heat baths with different chemical potentials. We derive expression for the corresponding current the carriers of which are fermions and analyze numerically its dependence of the model parameters in examples, where the scatterer has a rectangular or triangular shape.

Pavel Exner; Hagen Neidhardt; Milos Tater; Valentin A. Zagrebnov

2014-05-17

412

Equilibrium : CommonIonEffect (9 Variations)  

NSDL National Science Digital Library

The molar solubility of lead(II) fluoride (PbF 2 ) is 2.1 x 10 -3 mol/L in pure water at 25 o C. What is the molar solubility of lead(II) fluoride in 0.10 M NaF at 25 o C? (Assume that the only relevant reaction is the solubility-product equilibrium.)

413

Calculating Shocks In Flows At Chemical Equilibrium  

NASA Technical Reports Server (NTRS)

Boundary conditions prove critical. Conference paper describes algorithm for calculation of shocks in hypersonic flows of gases at chemical equilibrium. Although algorithm represents intermediate stage in development of reliable, accurate computer code for two-dimensional flow, research leading up to it contributes to understanding of what is needed to complete task.

Eberhardt, Scott; Palmer, Grant

1988-01-01

414

Equilibrium : KspSaturation (12 Variations)  

NSDL National Science Digital Library

Zn(OH) 2 has a K sp of 4.5 x 10 -17 . If you have a solution of Zn(OH) 2 that has a hydroxide ion concentration equal to 4.6 x 10 -6 mol/L, the solution is ... (Assume that the only relevant reaction is the solubility-product equilibrium.)

415

Sorptional equilibrium and drying characteristics of garlic  

Microsoft Academic Search

Drying characteristics of garlic including moisture sorption equilibrium, drying kinetics and pungency losses were investigated. Adsorption and desorption isotherms at 25, 45 and 65 °C were determined and correlated with a four parameter equation. The influence of temperature on adsorption was negligible and some hysteresis effect was observed. Air drying experiments and a diffusive model taking into account the internal

A. Pezzutti; G. H. Crapiste

1997-01-01

416

Local thermodynamics of inhomogeneous fluids at equilibrium  

SciTech Connect

Extensive thermodynamic parameters of inhomogeneous fluids in thermal equilibrium are expressed as integrals of corresponding locally defined quantities. In particular, the distinction between the grand canonical potential and the integrated mechanical pressure is discussed in terms of scale invariance, and a similar analysis is made of the Helmholtz free energy.

Percus, J.K. (Courant Institute of Mathematical Sciences and Physics Department, New York University, New York, New York 10012 (United States)); Pozhar, L.A. (Institute for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov 310164 (Ukraine)); Gubbins, K.E. (School of Chemical Engineering, Cornell University, Ithaca, New York 14853 (United States))

1995-01-01

417

Spheromak Equilibrium Studies on SSX Cameron Geddes  

E-print Network

, conducted on the Swarthmore Spheromak Experiment (SSX) at Swarthmore College, is a study of the formation be moved after formation, which is useful for these experiments. Magnetic reconnection is a turbulentSpheromak Equilibrium Studies on SSX Cameron Geddes Swarthmore College Department of Physics 10

Geddes, Cameron Guy Robinson

418

Equilibrium rotation in field-reversed configurations  

NASA Astrophysics Data System (ADS)

The turbulence that drives anomalous transport in field-reversed configurations (FRCs) is believed to break the otherwise closed magnetic surfaces inside the separatrix. This places electrons in the core of the plasma in electrical contact with those in the periphery. This effect was proposed and investigated in the context of spheromaks [D. D. Ryutov, Phys. Plasmas 14, 022506 (2007)]. The opening up of internal magnetic field lines serves to regulate the electrostatic potential in the interior of the plasma, and in turn drives ion rotation. In effect, "end-shorting," a well-known phenomenon in the FRC scrape-off layer, also extends into the plasma interior. For conditions relevant to experiments, the ion rotation can be expressed in terms of equilibrium properties (density and temperature gradients) and as such is the "equilibrium" rotation. This theory is incomplete in that it neglects evolving, transport-related effects that modify the equilibrium and, indirectly, the rotation rate. Consequently, the equilibrium rotation theory is only partially successful in predicting experimental results: although it predicts the average rotation well, the estimated degree of rotational shear seems unlikely, especially at late times in the plasma lifetime.

Steinhauer, Loren

2008-01-01

419

General Equilibrium Models: Improving the Microeconomics Classroom  

ERIC Educational Resources Information Center

General equilibrium models now play important roles in many fields of economics including tax policy, environmental regulation, international trade, and economic development. The intermediate microeconomics classroom has not kept pace with these trends, however. Microeconomics textbooks primarily focus on the insights that can be drawn from the…

Nicholson, Walter; Westhoff, Frank

2009-01-01

420

Wet Bulb Equilibrium in a Finite Process  

Microsoft Academic Search

WET bulb equilibrium between a liquid layer and a stream of air is established, in the absence of radiation, when the enthalpy of evaporation is entirely provided by heat transfer from the air stream. It is therefore possible to define an adiabatic surface, called here the l-surface, close to the interface and on the liquid side of it. For a

W. B. Gosney

1969-01-01

421

An Equilibrium Relation for Gas Adsorption Applications  

Microsoft Academic Search

A new multicomponent equilibrium relation is proposed for engineering applications. This relation is based on a lattice model for mixtures of unequally sized molecules. An approximation is introduced for loading-dependent enthalies of adsorption that simplifies the energy balance in fixed-bed models and allows efficient solution of the equation set in process simulations. Comparisons are made with nonideal binary data in

Bradley P. Russell

1999-01-01

422

Equilibrium Models of Strongly Magnetized Neutron Stars  

NASA Astrophysics Data System (ADS)

We consider equilibrium configurations of strongly magnetized neutron stars. Within full general relativity and assuming axisymmetry, we construct rotating stars with both poloidal and toroidal fields. Using a self-consistent field approach, we investigate the relative contributions from both magnetic components.

Hirschmann, Eric W.

2015-01-01

423

Teaching Chemical Equilibrium with the Jigsaw Technique  

ERIC Educational Resources Information Center

This study investigates the effect of cooperative learning (jigsaw) versus individual learning methods on students' understanding of chemical equilibrium in a first-year general chemistry course. This study was carried out in two different classes in the department of primary science education during the 2005-2006 academic year. One of the classes…

Doymus, Kemal

2008-01-01

424

AUCTION EQUILIBRIUM WITH COSTLY INFORMATION ACQUISITION  

E-print Network

AUCTION EQUILIBRIUM WITH COSTLY INFORMATION ACQUISITION Rolando M. Guzman and Charles D. Kolstad of whether or not to acquire information depends on a private cost of information acquisition and on her on the cost of information acquisition and on his or her conjectures regarding the behavior of other bidders

Kolstad, Charles

425

A Progression of Static Equilibrium Laboratory Exercises  

ERIC Educational Resources Information Center

Although simple architectural structures like bridges, catwalks, cantilevers, and Stonehenge have been integral in human societies for millennia, as have levers and other simple tools, modern students of introductory physics continue to grapple with Newton's conditions for static equilibrium. As formulated in typical introductory physics…

Kutzner, Mickey; Kutzner, Andrew

2013-01-01

426

Equilibrium Information Disclosure: Grade Inflation and Unraveling  

Microsoft Academic Search

This paper explores information disclosure in matching markets, e. g. the informativeness of transcripts given out by universities. We show that the same amount of information is disclosed in all equilibria. We then demonstrate that if universities disclose the equilibrium amount of information, students and employers will not find it profitable to contract early; if they disclose more, unraveling will

Michael Ostrovsky; Michael A. Schwarz

2003-01-01

427

Sensitivity analysis for abstract equilibrium problems  

Microsoft Academic Search

We develop the general framework of sensitivity analysis for equilibrium problems in the setting of vector topological normed space. Our approach does not make any recourse to geometrical properties and the obtained result can be viewed as an extension and generalization of the well-known results (on variational inequalities) in the literature. Even though we have worked under arbitrary constraints K?

Mohamed Ait Mansour; Hassan Riahi

2005-01-01

428

Spontaneity and Equilibrium II: Multireaction Systems  

ERIC Educational Resources Information Center

The thermodynamic criteria for spontaneity and equilibrium in multireaction systems are developed and discussed. When N reactions are occurring simultaneously, it is shown that G and A will depend upon N independent reaction coordinates, ?a (a = 1,2, ..., N), in addition to T and p for G or T and V for A. The general criteria for spontaneity and…

Raff, Lionel M.

2014-01-01

429

Equilibrium Polymerization as a Critical Phenomenon  

NASA Astrophysics Data System (ADS)

Equilibrium polymerization can be described by the n-->0 limit of the n-vector model of magnetism in a small magnetic field. Nonclassical critical effects are predicted. The earlier theory of Tobolsky and Eisenberg is a mean-field approximation to the present theory. An application is made to the polymerization in sulfur.

Wheeler, John C.; Kennedy, Stephen J.; Pfeuty, Pierre

1980-12-01

430

Equilibrium gas flow computations. I - Accurate and efficient calculation of equilibrium gas properties  

NASA Technical Reports Server (NTRS)

This paper treats the accurate and efficient calculation of thermodynamic properties of arbitrary gas mixtures for equilibrium flow computations. New improvements in the Stupochenko-Jaffe model for the calculation of thermodynamic properties of diatomic molecules are presented. A unified formulation of equilibrium calculations for gas mixtures in terms of irreversible entropy is given. Using a highly accurate thermo-chemical data base, a new, efficient and vectorizable search algorithm is used to construct piecewise interpolation procedures with generate accurate thermodynamic variable and their derivatives required by modern computational algorithms. Results are presented for equilibrium air, and compared with those given by the Srinivasan program.

Liu, Yen; Vinokur, Marcel

1989-01-01

431

Equilibrium and out-of-equilibrium thermodynamics in supercooled liquids and glasses  

NASA Astrophysics Data System (ADS)

We review the inherent structure thermodynamical formalism and the formulation of an equation of state (EOS) for liquids in equilibrium based on the (volume) derivatives of the statistical properties of the potential energy surface. We also show that, under the hypothesis that during ageing the system explores states associated with equilibrium configurations, it is possible to generalize the proposed EOS to out-of-equilibrium (OOE) conditions. The proposed formulation is based on the introduction of one additional parameter which, in the chosen thermodynamic formalism, can be chosen as the local minimum where the slowly relaxing OOE liquid is trapped.

Mossa, S.; La Nave, E.; Tartaglia, P.; Sciortino, F.

2003-01-01

432

Computing stationary distributions in equilibrium and non-equilibrium systems with Forward Flux Sampling  

E-print Network

We present a method for computing stationary distributions for activated processes in equilibrium and non-equilibrium systems using Forward Flux Sampling (FFS). In this method, the stationary distributions are obtained directly from the rate constant calculations for the forward and backward reactions; there is no need to perform separate calculations for the stationary distribution and the rate constant. We apply the method to the non-equilibrium rare event problem proposed by Maier and Stein, to nucleation in a 2-dimensional Ising system, and to the flipping of a genetic switch.

Chantal Valeriani; Rosalind J. Allen; Marco J. Morelli; Daan Frenkel; Pieter Rein ten Wolde

2009-07-03

433

Effective equilibrium theory of nonequilibrium quantum transport  

SciTech Connect

The theoretical description of strongly correlated quantum systems out of equilibrium presents several challenges and a number of open questions persist. Here, we focus on nonlinear electronic transport through an interacting quantum dot maintained at finite bias using a concept introduced by Hershfield [S. Hershfield, Phys. Rev. Lett. 70 2134 (1993)] whereby one can express such nonequilibrium quantum impurity models in terms of the system's Lippmann-Schwinger operators. These scattering operators allow one to reformulate the nonequilibrium problem as an effective equilibrium problem associated with a modified Hamiltonian. In this paper, we provide a pedagogical analysis of the core concepts of the effective equilibrium theory. First, we demonstrate the equivalence between observables computed using the Schwinger-Keldysh framework and the effective equilibrium approach, and relate Green's functions in the two theoretical frameworks. Second, we expound some applications of this method in the context of interacting quantum impurity models. We introduce a novel framework to treat effects of interactions perturbatively while capturing the entire dependence on the bias voltage. For the sake of concreteness, we employ the Anderson model as a prototype for this scheme. Working at the particle-hole symmetric point, we investigate the fate of the Abrikosov-Suhl resonance as a function of bias voltage and magnetic field. - Highlights: > Reformulation of steady-state nonequilibrium quantum transport, following Hershfield. > Derivation of effective equilibrium density operator using the 'open-system' approach. > Equivalence with the Keldysh description and formulas relating the two approaches. > Novel framework to treat interactions perturbatively. > Application to nonequilibrium Anderson model and fate of Abrikosov-Suhl resonance.

Dutt, Prasenjit [Department of Physics, Yale University, New Haven, CT 06520 (United States); Koch, Jens [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Han, Jong [Department of Physics, State University of New York at Buffalo, Buffalo, NY 14260 (United States); Le Hur, Karyn, E-mail: karyn.lehur@yale.edu [Department of Physics, Yale University, New Haven, CT 06520 (United States)

2011-12-15

434

Quantitative Proteomic Analysis of Serum from Pregnant Women Carrying a Fetus with Conotruncal Heart Defect Using Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) Labeling  

PubMed Central

Objective To identify differentially expressed proteins from serum of pregnant women carrying a conotruncal heart defects (CTD) fetus, using proteomic analysis. Methods The study was conducted using a nested case-control design. The 5473 maternal serum samples were collected at 14–18 weeks of gestation. The serum from 9 pregnant women carrying a CTD fetus, 10 with another CHD (ACHD) fetus, and 11 with a normal fetus were selected from the above samples, and analyzed by using isobaric tags for relative and absolute quantitation (iTRAQ) coupled with two-dimensional liquid chromatography-tandem mass spectrometry(2D LC-MS/MS). The differentially expressed proteins identified by iTRAQ were further validated with Western blot. Results A total of 105 unique proteins present in the three groups were identified, and relative expression data were obtained for 92 of them with high confidence by employing the iTRAQ-based experiments. The downregulation of gelsolin in maternal serum of fetus with CTD was further verified by Western blot. Conclusions The identification of differentially expressed protein gelsolin in the serum of the pregnant women carrying a CTD fetus by using proteomic technology may be able to serve as a foundation to further explore the biomarker for detection of CTD fetus from the maternal serum. PMID:25393621

Zhang, Ying; Kang, Yuan; Zhou, Qiongjie; Zhou, Jizi; Wang, Huijun; Jin, Hong; Liu, Xiaohui; Ma, Duan; Li, Xiaotian

2014-01-01

435

Inclusive production of slow protons and. delta. /sup 2 +/ (1236) isobars in. pi. /sup +/p interactions at 32 GeV/c  

SciTech Connect

Inclusive production of slow protons and ..delta../sup 2 +/ = (1236) isobars in ..pi../sup +/p interactions at 32 GeV/c is investigated in limited kinematic regions with Vertical Bart/sub p/pVertical Bar< 1.1 (GeV/c)/sup 2/ and Vertical Bart/sub p/..delta..Vertical Bar< 0.6 (GeV/c)/sup 2/, where the total inclusive cross sections are sigma(p) = 6.27 +- 0.2 mb and sigma(..delta../sup 2 +/) = 1.02 +- 0.2 mb. The energy dependence and the factorization properties of the total inclusive cross sections and inclusive spectra are discussed. In the dependence of the average associated multiplicity of charged particles in reactions in a proton target on the square of the missing mass of the system X, a systematic difference is observed between ..pi../sup +/p and K/sup + -/p reactions at 32 GeV/c in the region M/sup 2//sub X/ < 6 GeV/sup 2/.

Azhinenko, I.V.; Belokopytov, Y.A.; Vorob'ev, A.P.; Gerdyukov, L.N.; Gorunov, P.A.; Knyazev, V.V.; Kurnosenko, A.I.; Petrovykh, L.P.; Ryadovikov, V.N.; Rybin, A.M.; Uvarov, V.A.; Khromova, G.N.; Chikilev, O.G.; Chunikhin, V.F.; Shlyapnikov, P.V.

1980-04-01

436

Nuclear structure beyond the neutron drip line: the lowest energy states in $^9$He via their T=5/2 isobaric analogs in $^9$Li  

E-print Network

The level structure of the very neutron rich and unbound $^9$He nucleus has been the subject of significant experimental and theoretical study. Many recent works have claimed that the two lowest energy $^9$He states exist with spins $J^\\pi=1/2^+$ and $J^\\pi=1/2^-$ and widths on the order of hundreds of keV. These findings cannot be reconciled with our contemporary understanding of nuclear structure. The present work is the first high-resolution study with low statistical uncertainty of the relevant excitation energy range in the $^8$He$+n$ system, performed via a search for the T=5/2 isobaric analog states in $^9$Li populated through $^8$He+p elastic scattering. The present data show no indication of any narrow structures. Instead, we find evidence for a broad $J^{\\pi}=1/2^+$ state in $^9$He located approximately 3 MeV above the neutron decay threshold.

Uberseder, E; Goldberg, V Z; Koshchiy, E; Roeder, B T; Alcorta, M; Chubarian, G; Davids, B; Fu, C; Hooker, J; Jayatissa, H; Melconian, D; Tribble, R E

2015-01-01

437

Ambient isobaric heat capacities, C(p,m), for ionic solids and liquids: an application of volume-based thermodynamics (VBT).  

PubMed

Thermodynamic properties, such as standard entropy, among others, have been shown to correlate well with formula volume, V(m), thus permitting prediction of these properties on the basis of chemical formula and density alone, with no structural detail required. We have termed these procedures "volume-based thermodynamics" (VBT). We here extend these studies to ambient isobaric heat capacities, C(p,m), of a wide range of materials. We show that heat capacity is strongly linearly correlated with formula volume for large sets of minerals, for ionic solids in general, and for ionic liquids and that the results demonstrate that the Neumann-Kopp rule (additivity of heat capacity contributions per atom) is widely valid for ionic materials, but the smaller heat capacity contribution per unit volume for ionic liquids is noted and discussed. Using these correlations, it is possible to predict values of ambient (298 K) heat capacities quite simply. We also show that the heat capacity contribution of water molecules of crystallization is remarkably constant, at 41.3 ± 4.7 J K(-1) (mol of water)(-1), so that the heat capacities of various hydrates may be reliably estimated from the values of their chemical formula neighbors. This result complements similar observations that we have reported for other thermodynamic differences of hydrates. PMID:21812409

Glasser, Leslie; Jenkins, H Donald Brooke

2011-09-01

438

Non-Equilibrium Heavy Flavored Hadron Yields from Chemical Equilibrium Strangeness-Rich QGP  

E-print Network

The yields of heavy flavored hadrons emitted from strangeness-rich QGP are evaluated within chemical non-equilibrium statistical hadronization model, conserving strangeness, charm, and entropy yields at hadronization.

Inga Kuznetsova; Johann Rafelski

2008-01-05

439

Coupled phase and aqueous species equilibrium of the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite  

NASA Astrophysics Data System (ADS)

A model is developed for the calculation of coupled phase and aqueous species equilibrium in the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite. The vapor-liquid-solid (calcite, halite) equilibrium together with the chemical equilibrium of H +, Na +, Ca 2+, CaHCO3+, Ca(OH) +, OH -, Cl -, HCO3-, CO32-, CO 2(aq) and CaCO 3(aq) in the aqueous liquid phase as a function of temperature, pressure, NaCl concentrations, CO 2(aq) concentrations can be calculated, with accuracy close to those of experiments in the stated T- P- m range, hence calcite solubility, CO 2 gas solubility, alkalinity and pH values can be accurately calculated. The merit and advantage of this model is its predictability, the model was generally not constructed by fitting experimental data. One of the focuses of this study is to predict calcite solubility, with accuracy consistent with the works in previous experimental studies. The resulted model reproduces the following: (1) as temperature increases, the calcite solubility decreases. For example, when temperature increases from 273 to 373 K, calcite solubility decreases by about 50%; (2) with the increase of pressure, calcite solubility increases. For example, at 373 K changing pressure from 10 to 500 bar may increase calcite solubility by as much as 30%; (3) dissolved CO 2 can increase calcite solubility substantially; (4) increasing concentration of NaCl up to 2 m will increase calcite solubility, but further increasing NaCl solubility beyond 2 m will decrease its solubility. The functionality of pH value, alkalinity, CO 2 gas solubility, and the concentrations of many aqueous species with temperature, pressure and NaCl (aq) concentrations can be found from the application of this model. Online calculation is made available on www.geochem-model.org/models/h2o_co2_nacl_caco3/calc.php.

Duan, Zhenhao; Li, Dedong

2008-10-01

440

Phase Equilibrium Investigations of Planetary Materials  

NASA Technical Reports Server (NTRS)

This grant provided funds to carry out phase equilibrium studies on the processes of chemical differentiation of the moon and the meteorite parent bodies, during their early evolutionary history. Several experimental studies examined processes that led to the formation of lunar ultramafic glasses. Phase equilibrium studies were carried out on selected low-Ti and high-Ti lunar ultramafic glass compositions to provide constraints on the depth range, temperature and processes of melt generation and/or assimilation. A second set of experiments examined the role of sulfide melts in core formation processes in the earth and terrestrial planets. The major results of each paper are discussed, and copies of the papers are attached as Appendix I.

Grove, T. L.

2005-01-01

441

An equilibrium approach to modelling social interaction  

E-print Network

The aim of this work is to put forward a statistical mechanics theory of social interaction, generalizing econometric discrete choice models. After showing the formal equivalence linking econometric multinomial logit models to equilibrium statical mechanics, a multi-population generalization of the Curie-Weiss model for ferromagnets is considered as a starting point in developing a model capable of describing sudden shifts in aggregate human behaviour. Existence of the thermodynamic limit for the model is shown by an asymptotic sub-additivity method and factorization of correlation functions is proved almost everywhere. The exact solution of the model is provided in the thermodynamical limit by finding converging upper and lower bounds for the system's pressure, and the solution is used to prove an analytic result regarding the number of possible equilibrium states of a two-population system. The work stresses the importance of linking regimes predicted by the model to real phenomena, and to this end it propo...

Gallo, Ignacio

2009-01-01

442

Equilibrium bed-concentration of nonuniform sediment.  

PubMed

Knowledge of the equilibrium bed-concentration is vital to mathematical modeling of the river-bed deformation associated with suspended load but previous investigations only dealt with the reference concentration of uniform sediment because of difficulties in observation of the bed-concentration. This work is a first attempt to develop a theoretical formula for the equilibrium bed-concentration of any fraction of nonuniform sediment defined at the bed-surface. The formula is based on a stochastic-mechanistic model for the exchange of nonuniform sediment near the bed, and described as a function of incipient motion probability, non-ceasing probability, pick-up probability, and the ratio of the average single-step continuous motion time to static time. Comparison of bed-concentration calculated from the proposed formula with the measured data showed satisfactory agreement, indicating the present formula can be used for solving the differential equation governing the motion of suspended load. PMID:12659233

Sun, Zhi-Lin; Sun, Zhi-Feng; Donahue, John

2003-01-01

443

Equilibrium statistical mechanics for incomplete nonextensive statistics  

E-print Network

The incomplete nonextensive statistics in the canonical and microcanonical ensembles is explored in the general case and in a particular case for the ideal gas. By exact analytical results for the ideal gas it is shown that taking the thermodynamic limit, with $z=q/(1-q)$ being an extensive variable of state, the incomplete nonextensive statistics satisfies the requirements of equilibrium thermodynamics. The thermodynamical potential of the statistical ensemble is a homogeneous function of the first degree of the extensive variables of state. In this case, the incomplete nonextensive statistics is equivalent to the usual Tsallis statistics. If $z$ is an intensive variable of state, i.e. the entropic index $q$ is a universal constant, the requirements of the equilibrium thermodynamics are violated.

A. S. Parvan; T. S. Biro

2010-03-29

444

An extended absorption theory for hydrate equilibrium  

SciTech Connect

A hybrid type of theory for calculating hydrate equilibrium was recently proposed. The theory has been extended to cover the region of equilibrium between ice and hydrate as well as liquid water hydrate. In this work, the authors present some results for the changes of chemical potential due to guest inclusion using either the harmonic oscillator approach or the original theory. Simple spherical Lennard-Jones models have been used for the guest molecules. Gas phase chemical potentials are calculated from the same sets of parameters using the virial-equation. Water is represented by the TIP4P potential. They have correlated these results into a convenient interpolation-equation. The authors have used this equation to estimate some results for mixtures. The results are promising and with an extension of the simulations to cover a broader range of components this might be a convenient alternative to the present single cavity integrations that require empirical corrections for large components.

Kvamme, B. [Telemark Inst. of Technology, Porsgrunn (Norway)

1995-12-31

445

Stationary equilibrium singularity distributions in the plane  

NASA Astrophysics Data System (ADS)

We characterize all stationary equilibrium point singularity distributions in the plane of logarithmic type, allowing for real, imaginary or complex singularity strengths. The dynamical system follows from the assumption that each of the N singularities moves according to the flow field generated by all the others at that point. For strength vector \\vec{\\Gamma} \\in {\\Bbb R}^N , the dynamical system is the classical point vortex system obtained from a singular discrete representation of the vorticity field from ideal, incompressible fluid flow. When \\vec{\\Gamma} \\in \\Im , it corresponds to a system of sources and sinks, whereas when \\vec{\\Gamma} \\in {\\Bbb C}^N the system consists of spiral sources and sinks discussed in Kochin et al (1964 Theoretical Hydromechanics 1 (London: Interscience)). We formulate the equilibrium problem as one in linear algebra, A \\vec{\\Gamma} = 0 , A \\in {\\Bbb C}^{N \\times N} , \\vec{\\Gamma} \\in {\\Bbb C}^N , where A is a N × N complex skew-symmetric configuration matrix which encodes the geometry of the system of interacting singularities. For an equilibrium to exist, A must have a kernel and \\vec{\\Gamma} must be an element of the nullspace of A. We prove that when N is odd, A always has a kernel, hence there is a choice of \\vec{\\Gamma} for which the system is a stationary equilibrium. When N is even, there may or may not be a non-trivial nullspace of A, depending on the relative position of the points in the plane. We provide examples of evenly and randomly distributed points on curves such as circles, figure eights, flower-petal configurations and spirals. We then show how to classify the stationary equilibria in terms of the singular spectrum of A.

Newton, P. K.; Ostrovskyi, V.

2012-02-01

446

Introduction to Equilibrium Thermodynamics: Salt Dissolution  

NSDL National Science Digital Library

In this lab I simply have students dissolve halite and sylvite in water at various temperatures. I use this experiment to introduce students to the principles of equilibrium thermodynamics, as well as basic lab skills, data analysis, and lab report writing. Students use basic laboratory skills to conduct their experiments then analyze their data using a spreadsheet program such as Excel. They then write up their results and discussion in a formal lab report.

Andrew Knudsen

447

A Chemical Equilibrium Model for Natural Waters  

Microsoft Academic Search

This paper reviews the present status of the Pitzer chemical equilibrium model, which can be used to characterize the one-atmosphere activity coefficients of ionic and non-ionic solutes in natural waters as a function of temperature and ionic strength. The model considers the ionic interactions of the major seasalt ions (H, Na, K, Mg, Ca, Sr, Cl, Br, OH, HCO3, B(OH)4,

Frank J. Millero; Denis Pierrot

1998-01-01

448

Equilibrium Correlations of Asset Price and Return  

Microsoft Academic Search

Two empirical questions concerning the equity and housing have been studied extensively: (1) Are the price and return serially\\u000a correlated, and (2) What is the optimal weight of housing in the portfolio? The answer to the second question crucially depends\\u000a on the cross-correlation of assets. This paper complements the literature by building a simple dynamic general equilibrium\\u000a with fully rational

Charles Ka Yui Leung; Yui Leung

2007-01-01

449

The boundary value problem of magnetotail equilibrium  

NASA Technical Reports Server (NTRS)

The earth magnetotail equilibrium problem is examined by expressing it as a 2D boundary value problem for a prescribed tail boundary, which may be considered as an idealized magnetopause. A general solution of this problem is derived for the 2D case, where the dependence on the y coordinate and the presence of By are neglected. These solutions are further generalized by including the y dependence and an open magnetosphere. Then, a general solution of a 3D boundary problem is derived.

Birn, Joachim

1991-01-01

450

The equilibrium boundary between grahite and diamond  

Microsoft Academic Search

The equilibrium boundary between diamond and graphite has been determined over the temperature interval 1100°C-1625°C. A piston-cylinder apparatus and a ''zero-friction'' cell were used. Pressures were computed by force\\/area measurements and are independent of any calibration points. Visual observations of diamond dissolution or diamond growth were used in fixing the position of the boundary. Our newly determined boundary has the

C. Scott Kennedy; George C. Kennedy

1976-01-01

451

Molecular equilibrium with condensation. [In astrophysics  

SciTech Connect

Minimization of the Gibbs energy of formation for species of chemical elements and compounds in their gas and condensed phases determines their relative abundances in a mixture in chemical equilibrium. The procedure is more general and more powerful than previous abundance determinations in multiphase astrophysical mixtures. Some results for astrophysical equations of state are presented, and the effects of condensation on opacity are briefly indicated. 18 refs.

Sharp, C.M.; Huebner, W.F. (Los Alamos National Laboratory, NM (USA) Southwest Research Institute, San Antonio, TX (USA))

1990-02-01

452

Molecular equilibrium with condensation. [in astrophysics  

NASA Technical Reports Server (NTRS)

Minimization of the Gibbs energy of formation for species of chemical elements and compounds in their gas and condensed phases determines their relative abundances in a mixture in chemical equilibrium. The procedure is more general and more powerful than previous abundance determinations in multiphase astrophysical mixtures. Some results for astrophysical equations of state are presented, and the effects of condensation on opacity are briefly indicated.

Sharp, C. M.; Huebner, W. F.

1990-01-01

453

Multi-period equilibrium/near-equilibrium in electricity markets based on locational marginal prices  

NASA Astrophysics Data System (ADS)

In this dissertation we propose an equilibrium procedure that coordinates the point of view of every market agent resulting in an equilibrium that simultaneously maximizes the independent objective of every market agent and satisfies network constraints. Therefore, the activities of the generating companies, consumers and an independent system operator are modeled: (1) The generating companies seek to maximize profits by specifying hourly step functions of productions and minimum selling prices, and bounds on productions. (2) The goals of the consumers are to maximize their economic utilities by specifying hourly step functions of demands and maximum buying prices, and bounds on demands. (3) The independent system operator then clears the market taking into account consistency conditions as well as capacity and line losses so as to achieve maximum social welfare. Then, we approach this equilibrium problem using complementarity theory in order to have the capability of imposing constraints on dual variables, i.e., on prices, such as minimum profit conditions for the generating units or maximum cost conditions for the consumers. In this way, given the form of the individual optimization problems, the Karush-Kuhn-Tucker conditions for the generating companies, the consumers and the independent system operator are both necessary and sufficient. The simultaneous solution to all these conditions constitutes a mixed linear complementarity problem. We include minimum profit constraints imposed by the units in the market equilibrium model. These constraints are added as additional constraints to the equivalent quadratic programming problem of the mixed linear complementarity problem previously described. For the sake of clarity, the proposed equilibrium or near-equilibrium is first developed for the particular case considering only one time period. Afterwards, we consider an equilibrium or near-equilibrium applied to a multi-period framework. This model embodies binary decisions, i.e., on/off status for the units, and therefore optimality conditions cannot be directly applied. To avoid limitations provoked by binary variables, while retaining the advantages of using optimality conditions, we define the multi-period market equilibrium using Benders decomposition, which allows computing binary variables through the master problem and continuous variables through the subproblem. Finally, we illustrate these market equilibrium concepts through several case studies.

Garcia Bertrand, Raquel

454

Analytical ultracentrifugation: sedimentation velocity and sedimentation equilibrium.  

PubMed

Analytical ultracentrifugation (AUC) is a versatile and powerful method for the quantitative analysis of macromolecules in solution. AUC has broad applications for the study of biomacromolecules in a wide range of solvents and over a wide range of solute concentrations. Three optical systems are available for the analytical ultracentrifuge (absorbance, interference, and fluorescence) that permit precise and selective observation of sedimentation in real time. In particular, the fluorescence system provides a new way to extend the scope of AUC to probe the behavior of biological molecules in complex mixtures and at high solute concentrations. In sedimentation velocity (SV), the movement of solutes in high centrifugal fields is interpreted using hydrodynamic theory to define the size, shape, and interactions of macromolecules. Sedimentation equilibrium (SE) is a thermodynamic method where equilibrium concentration gradients at lower centrifugal fields are analyzed to define molecule mass, assembly stoichiometry, association constants, and solution nonideality. Using specialized sample cells and modern analysis software, researchers can use SV to determine the homogeneity of a sample and define whether it undergoes concentration-dependent association reactions. Subsequently, more thorough model-dependent analysis of velocity and equilibrium experiments can provide a detailed picture of the nature of the species present in solution and their interactions. PMID:17964931

Cole, James L; Lary, Jeffrey W; P Moody, Thomas; Laue, Thomas M

2008-01-01

455

Recovery of postural equilibrium control following spaceflight  

NASA Technical Reports Server (NTRS)

Decreased postural stability is observed in most astronauts immediately following spaceflight. Because ataxia may present postflight operational hazards, it is important to determine the incidence of postural instability immediately following landing and the dynamics of recovery of normal postural equilibrium control. It is postulated that postflight postural instability results from in-flight adaptive changes in central nervous system (CNS) processing of sensory information from the visual, vestibular, and proprioceptive systems. The purpose of the present investigation was to determine the magnitude and time course of postflight recovery of postural equilibrium control and, hence, readaptation of CNS processing of sensory information. Thirteen crew members from six spaceflight missions were studied pre- and postflight using a modified commercial posturography system. Postural equilibrium control was found to be seriously disrupted immediately following spaceflight in all subjects. Readaptation to the terrestrial environment began immediately upon landing, proceeded rapidly for the first 10-12 hours, and then proceeded much more slowly for the subsequent 2-4 days until preflight stability levels were reachieved. It is concluded that the overall postflight recovery of postural stability follows a predictable time course.

Paloski, W. H.; Reschke, M. F.; Black, F. O.; Doxey, D. D.; Harm, D. L.

1992-01-01

456

Out-of-equilibrium electromagnetic radiation  

E-print Network

We derive general formulas for photon and dilepton production rates from an arbitrary non-equilibrated medium from first principles in quantum field theory. At lowest order in the electromagnetic coupling constant, these relate the rates to the unequal-time in-medium photon polarization tensor and generalize the corresponding expressions for a system in thermodynamic equilibrium. We formulate the question of electromagnetic radiation in real time as an initial value problem and consistently describe the virtual electromagnetic dressing of the initial state. In the limit of slowly evolving systems, we recover known expressions for the emission rates and work out the first correction to the static formulas in a systematic gradient expansion. Finally, we discuss the possible application of recently developed techniques in non-equilibrium quantum field theory to the problem of electromagnetic radiation. We argue, in particular, that the two-particle-irreducible (2PI) effective action formalism provides a powerful resummation scheme for the description of multiple scattering effects, such as the Landau-Pomeranchuk-Migdal suppression recently discussed in the context of equilibrium QCD.

Julien Serreau

2004-06-22

457

Bifurcated helical core equilibrium states in tokamaks  

NASA Astrophysics Data System (ADS)

Tokamaks with weak to moderate reversed central shear in which the minimum inverse rotational transform (safety factor) qmin is in the neighbourhood of unity can trigger bifurcated magnetohydrodynamic equilibrium states, one of which is similar to a saturated ideal internal kink mode. Peaked prescribed pressure profiles reproduce the ‘snake’ structures observed in many tokamaks which has led to a novel explanation of the snake as a bifurcated equilibrium state. Snake equilibrium structures are computed in simulations of the tokamak à configuration variable (TCV), DIII-D and mega amp spherical torus (MAST) tokamaks. The internal helical deformations only weakly modulate the plasma-vacuum interface which is more sensitive to ripple and resonant magnetic perturbations. On the other hand, the external perturbations do not alter the helical core deformation in a significant manner. The confinement of fast particles in MAST simulations deteriorate with the amplitude of the helical core distortion. These three-dimensional bifurcated solutions constitute a paradigm shift that motivates the applications of tools developed for stellarator research in tokamak physics investigations.

Cooper, W. A.; Chapman, I. T.; Schmitz, O.; Turnbull, A. D.; Tobias, B. J.; Lazarus, E. A.; Turco, F.; Lanctot, M. J.; Evans, T. E.; Graves, J. P.; Brunetti, D.; Pfefferlé, D.; Reimerdes, H.; Sauter, O.; Halpern, F. D.; Tran, T. M.; Coda, S.; Duval, B. P.; Labit, B.; Pochelon, A.; Turnyanskiy, M. R.; Lao, L.; Luce, T. C.; Buttery, R.; Ferron, J. R.; Hollmann, E. M.; Petty, C. C.; van Zeeland, M.; Fenstermacher, M. E.; Hanson, J. M.; Lütjens, H.

2013-07-01

458

Equilibrium Gold Nanoclusters Quenched with Biodegradable Polymers  

PubMed Central

Although sub-100 nm nanoclusters of metal nanoparticles are of interest in many fields including biomedical imaging, sensors and catalysis, it has been challenging to control their morphologies and chemical properties. Herein, a new concept is presented to assemble equilibrium Au nanoclusters of controlled size by tuning the colloidal interactions with a polymeric stabilizer, PLA(1k)-b-PEG(10k)-b-PLA(1k). The nanoclusters form upon mixing a dispersion of ~5 nm Au nanospheres with a polymer solution followed by partial solvent evaporation. A weakly adsorbed polymer quenches the equilibrium nanocluster size and provides steric stabilization. Nanocluster size is tuned from ~20 nm to ~40 nm by experimentally varying the final Au nanoparticle concentration and the polymer/Au ratio, along with the charge on the initial Au nanoparticle surface. Upon biodegradation of the quencher, the nanoclusters reversibly and fully dissociate to individual ~5 nm primary particles. Equilibrium cluster size is predicted semi-quantitatively with a free energy model that balances short-ranged depletion and van der Waals attractions with longer-ranged electrostatic repulsion, as a function of the Au and polymer concentrations. The close spacings of the Au nanoparticles in the clusters produce strong NIR extinction over a broad range of wavelengths from 650 to 900 nm, which is of practical interest in biomedical imaging. PMID:23230905

Murthy, Avinash K.; Stover, Robert J.; Borwankar, Ameya U.; Nie, Golay D.; Gourisankar, Sai; Truskett, Thomas M.; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

459

Thermodynamics and Kinetics of Chemical Equilibrium in Solution.  

ERIC Educational Resources Information Center

Discusses theory of thermodynamics of the equilibrium in solution and dissociation-dimerization kinetics. Describes experimental procedure including determination of molar absorptivity and equilibrium constant, reaction enthalpy, and kinetics of the dissociation-dimerization reaction. (JM)

Leenson, I. A.

1986-01-01

460

On the Concept "Chemical Equilibrium": The Associative Framework.  

ERIC Educational Resources Information Center

Word associations were used to map high school students' concepts of "chemical equilibrium" and "equilibrium." It was found that the preconception of the two concepts was differentiated on noncritical dimensions. (Author/CW)

Gussarsky, Esther; Gorodetsky, Malka

1990-01-01

461

Fluctuation-induced phenomena in non-equilibrium systems  

E-print Network

In this thesis, we investigate the implications of fluctuations in systems away, possibly even far, from equilibrium due to their motion either in or out of thermal equilibrium. This subject encompasses several topics in ...

Faghfoor M., Mohammad (Faghfoor Maghrebi)

2013-01-01

462

Transport and equilibrium in molecular plasmas: the sulfur lamp  

E-print Network

Transport and equilibrium in molecular plasmas: the sulfur lamp PROEFSCHRIFT ter verkrijging van de William Transport and equilibrium in molecular plasmas: the sulfur lamp / by Colin William Johnston. : plasma / zwavel lamp / moleculen / transporteigenschappen Subject headings : plasma / sulfur lamp

Eindhoven, Technische Universiteit

463

Fractal Geometry of Equilibrium Payoffs in Discounted Supergames  

NASA Astrophysics Data System (ADS)

This paper examines the pure-strategy subgame-perfect equilibrium payoffs in discounted supergames with perfect monitoring. It is shown that the equilibrium payoffs can be identified as sub-self-affine sets or graph-directed iterated function systems. We propose a method to estimate the Hausdorff dimension of the equilibrium payoffs and relate it to the equilibrium paths and their graph presentation.

Berg, Kimmo; Kitti, Mitri

2014-08-01

464

Equilibrium and stability of charged and uncharged helium film surfaces  

Microsoft Academic Search

We have studied the equilibrium shape and stability of charged and uncharged surfaces on thin films of liquid helium. We assume that the average distance between electrodes is much greater than the film thickness. We used a variational method to obtain the necessary and sufficient conditions for the equilibrium and stability of the equilibrium state of a charged surface. The

Zhakin

1985-01-01

465

GLOBAL OPTIMIZATION FOR THE PHASE AND CHEMICAL EQUILIBRIUM PROBLEM  

E-print Network

GLOBAL OPTIMIZATION FOR THE PHASE AND CHEMICAL EQUILIBRIUM PROBLEM: APPLICATION TO THE NRTL of solutions to the phase and chemical equilibrium problem when the problem is posed as the minimization the equilibrium condition. For many chemical engineering applications this function will be the Gibbs free energy

Neumaier, Arnold

466

Trapped nonneutral plasmas, liquids, and crystals (the thermal equilibrium states)  

E-print Network

Trapped nonneutral plasmas, liquids, and crystals (the thermal equilibrium states) Daniel H. E confined for hours and even days, and thermal equilibrium states are observed. These plasmas can be cooled. Experimental observation of thermal-equilibrium states 96 1. Electron plasmas 96 2. Ion plasmas 97 C. Self

California at San Diego, University of

467

Towards breaking temperature equilibrium in multi-component Eulerian schemes  

SciTech Connect

We investigate the effects ofthermal equilibrium on hydrodynamic flows and describe models for breaking the assumption ofa single temperature for a mixture of components in a cell. A computational study comparing pressure-temperature equilibrium simulations of two dimensional implosions with explicit front tracking is described as well as implementation and J-D calculations for non-equilibrium temperature methods.

Grove, John W [Los Alamos National Laboratory; Masser, Thomas [Los Alamos National Laboratory

2009-01-01

468

The director and molecular dynamics of the field-induced alignment of a Gay-Berne nematic phase: An isothermal-isobaric nonequilibrium molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

Isothermal-isobaric molecular dynamics simulations have been performed for the generic Gay-Berne (GB) mesogen, GB(4.4, 20.0, 1, 1), to investigate director and molecular rotational motion during the field-induced alignment of a nematic. The alignment process for the director is discussed within the context of a hydrodynamic analysis based on the Ericksen-Leslie theory and this is found to predict the simulated behavior well. The dependence of the relaxation time for the alignment on the field strength is also in good accord with the theory. The rotational viscosity coefficient estimated from the simulation is smaller than that typically observed for real nematics and the possible reasons for this are discussed. However, the simulation results are found to follow not only the theory but also the experiments, at least qualitatively. No significant variation in the local and long-range structure of the nematic phase is found during the field-induced alignment process. In addition, we have explored the molecular dynamics in the nematic phase in the presence of the field using the first- and second-rank time autocorrelation functions. More importantly we are able to show that the director relaxation time is longer than that for molecular rotation. It is also possible to use the two orientational correlation times to explore the relationship between the rotational viscosity coefficient and the rotational diffusion constant. The diffusion constants determined from the orientational correlation times, based on the short-time expansion of the autocorrelation functions, are found to be significantly different. In consequence it is not possible to test, unambiguously, the relationship between the rotational viscosity coefficient and the rotational diffusion constant. However, it would seem that the second-rank rotational correlation time provides the most reliable route to the rotational viscosity coefficient.

Luckhurst, Geoffrey R.; Satoh, Katsuhiko

2010-05-01

469

Equation of state of a dense plasma by orbital-free and quantum molecular dynamics: Examination of two isothermal-isobaric mixing rules  

NASA Astrophysics Data System (ADS)

We test two isothermal-isobaric mixing rules, respectively based on excess-pressure and total-pressure equilibration, applied to the equation of state of a dense plasma. While the equation of state is generally known for pure species, that of arbitrary mixtures is not available so that the validation of accurate mixing rules, that implies resorting to first-principles simulations, is very useful. Here we consider the case of a plastic with composition C2H3 and we implement two complementary ab initio approaches adapted to the dense plasma domain: quantum molecular dynamics, limited to low temperature by its computational cost, and orbital-free molecular dynamics, that can be implemented at high temperature. The temperature and density range considered is 1-10 eV and 0.6-10 g/cm 3 for quantum molecular dynamics, and 5-1000 eV and 1-10 g/cm 3 for orbital-free molecular dynamics. Simulations for the full C2H3 mixture are the benchmark against which to assess the mixing rules, and both pressure and internal energy are compared. We find that the mixing rule based on excess-pressure equilibration is overall more accurate than that based on total-pressure equilibration; except for quantum molecular dynamics and a thermodynamic domain characterized by very low or negative excess pressures, it gives pressures which are generally within statistical error or within 1% of the exact ones. Besides, its superiority is amplified in the calculation of a principal Hugoniot.

Danel, J.-F.; Kazandjian, L.

2015-01-01

470

Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium  

SciTech Connect

We examine both processes of ionization by electron and heavy-particle impact in spatially uniform plasmas at rest in the absence of external forces. A singular perturbation analysis is used to study the following physical scenario, in which thermal relaxation becomes much slower than chemical reactions. First, electron-impact ionization is investigated. The dynamics of the system rapidly becomes close to a slow dynamics manifold that allows for defining a unique chemical quasi-equilibrium for two-temperature plasmas and proving that the second law of thermodynamics is satisfied. Then, all ionization reactions are taken into account simultaneously, leading to a surprising conclusion: the inner layer for short time scale (or time boundary layer) directly leads to thermal equilibrium. Global thermo-chemical equilibrium is reached within a short time scale, involving only chemical reactions, even if thermal relaxation through elastic collisions is assumed to be slow.

Massot, Marc [Laboratoire EM2C, UPR 288 CNRS - Ecole Centrale Paris (France); Graille, Benjamin [Laboratoire de Mathematiques d'Orsay, UMR 8628 CNRS - Universite Paris-Sud (France); Magin, Thierry E. [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics (Belgium)

2011-05-20

471

Equilibrium and shot noise in mesoscopic systems  

SciTech Connect

Within the last decade, there has been a resurgence of interest in the study of noise in Mesoscopic devices, both experimentally and theoretically. Noise in solid state devices can have different origins: there is 1/f noise, which is believed to arise from fluctuations in the resistance of the sample due to the motion of impurities. On top of this contribution is a frequency independent component associated with the stochastic nature of electron transport, which will be the focus of this paper. If the sample considered is small enough that dephasing and inelastic effects can be neglected, equilibrium (thermal) and excess noise can be completely described in terms of the elastic scattering properties of the sample. As mentioned above, noise arises as a consequence of random processes governing the transport of electrons. Here, there are two sources of randomness: first, electrons incident on the sample occupy a given energy state with a probability given by the Fermi-Dirac distribution function. Secondly, electrons can be transmitted across the sample or reflected in the same reservoir where they came from with a probability given by the quantum mechanical transmission/reflection coefficients. Equilibrium noise refers to the case where no bias voltage is applied between the leads connected to the sample, where thermal agitation alone allows the electrons close to the Fermi level to tunnel through the sample. In general, equilibrium noise is related to the conductance of the sample via the Johnson-Nyquist formula. In the presence of a bias, in the classical regime, one expects to recover the full shot noise < {Delta}{sup 2}I >= 2I{Delta}{mu} as was observed a long time ago in vacuum diodes. In the Mesoscopic regime, however, excess noise is reduced below the shot noise level. The author introduces a more intuitive picture, where the current passing through the device is a superposition of pulses, or electron wave packets, which can be transmitted or reflected.

Martin, T.

1994-10-01

472

Multicomponent Equilibrium Models for Testing Geothermometry Approaches  

SciTech Connect

Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.

Cooper, D. Craig; Carl D. Palmer; Robert W. Smith; Travis L. McLing

2013-02-01

473

Adaptive Implicit Non-Equilibrium Radiation Diffusion  

SciTech Connect

We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

Philip, Bobby [ORNL; Wang, Zhen [ORNL; Berrill, Mark A [ORNL; Rodriguez Rodriguez, Manuel [ORNL; Pernice, Michael [Idaho National Laboratory (INL)

2013-01-01

474

Equilibrium coverage of halides on metal electrodes  

NASA Astrophysics Data System (ADS)

The adsorption of halides on Cu(111) and Pt(111) has been studied using periodic density functional theory calculations. The equilibrium coverage of the halides as a function of the electrode potential was determined using a thermodynamic approach in which the electrochemical environment is not explicitly taken into account. For all considered systems, halide coverages between 1/3 and 3/8 should be stable over a wide potential range. Although some quantitative discrepancies with experiment are obtained, the qualitative trends derived from the calculations are consistent with experimental observations. The reasons for the remaining discrepancies with the experiment are discussed.

Gossenberger, Florian; Roman, Tanglaw; Groß, Axel

2015-01-01