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1

Isobaric vapor-liquid equilibrium for ethanol + water + potassium nitrate

An increasing research interest in the determination of the salt effect in the vapor-liquid equilibrium of binary systems has developed over the last few decades due to the importance of distillation with salts in the separation of close boiling and azeotropic mixtures. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + potassium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.642 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-01-01

2

Isobaric vapor-liquid equilibrium for ethanol + water + strontium nitrate

The effect of salts on the vapor-liquid equilibrium of solvent mixtures is of considerable interest in the separation of close boiling and azeotropic mixtures. The salt effect has been studied by many researchers. Most investigations have been limited to measurements on the saturated salt solutions. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + strontium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.672, has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain)] [Univ. de Valencia (Spain)

1996-07-01

3

Isobaric vapor-liquid equilibrium for ethanol + water + sodium nitrate

The salt effect on the vapor-liquid equilibrium of mixed solvents provides a potential technique of extractive distillation, in which a dissolved salt, rather than a liquid additive, is used as the separating agent. This salt distillation process has been used in the purification of close-boiling, azeotropic, and other systems which are difficult to separate. The isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + sodium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.774 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Pena, M.P.; Vercher, E.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-09-01

4

Isobaric vapor-liquid equilibrium data for the ethanol-water-strontium bromide system

Isobaric experimental data of vapor-liquid equilibrium for the ethanol-water-strontium bromide system at different mole fractions of strontium bromide have been measured at 100.6 kPa. Data were correlated by Jaques and Furter's method. Thermodynamic consistency was checked by Herington's method with satisfactory results.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. (Univ. de Valencia (Spain). Dept. de Ingenieria Quimica)

1994-04-01

5

Isobaric vapor-liquid equilibrium for ethanol + water + copper(II) chloride

The extractive distillation in which an electrolyte is employed as the extractive agent is an important alternative to the conventional methods for separating mixtures involving azeotropes. Isobaric vapor-liquid equilibrium for ethanol (1) + water(2) + copper(II) chloride (3) at different mole fractions of copper(II) chloride has been measured at 100.0 kPa. The results in the range where the mole fraction of salt in the liquid phase was less than 0.146 times the mole fraction of water were correlated by assuming that the salt was in ionic form and it was associated only with the water. Thermodynamic consistency was checked according to Herington`s method with satisfactory results.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1995-05-01

6

Binary vapor-liquid equilibrium data without measurement of composition

1975 ABSTRACT Binary Vapor-Liquid Equilibrium Data Without Measurement of Composition (May 1975) Mohammad Sadegh Nehsat B. S. , Abadan Institute of Technology (IRAN) Chairman of Advisory Committee: Dr. P. T. Eubank Vapor-liquid. equilibrium (VLE... 1975 ABSTRACT Binary Vapor-Liquid Equilibrium Data Without Measurement of Composition (May 1975) Mohammad Sadegh Nehsat B. S. , Abadan Institute of Technology (IRAN) Chairman of Advisory Committee: Dr. P. T. Eubank Vapor-liquid. equilibrium (VLE...

Nehzat, Mohammad Sadegh

2012-06-07

7

Vapor-Liquid Equilibrium Data of Citronella Oil Systems

In the paper, the high purity citronellal, citronellal and geranial, which had been distilled from industrial crude citronella oil, were used as raw materials. The vapor-liquid equilibrium (VLE) data of citronellal, citronellal and geranial at 3.31kPa (absolute pressure) was measured by the method of single loop reactor vapor-liquid equilibrium. VLE phase diagrams of citronellal-citronellal and citronellal geranial systems were obtained.

Qiu Chen; Lili Gu

2011-01-01

8

John Arthur McLees, Jr. Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water at

Copyright by John Arthur McLees, Jr. 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water in Engineering The University of Texas at Austin May, 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water

Rochelle, Gary T.

9

Isobaric vapor-liquid equilibria in the system methyl propanoate + n-butyl alcohol

Isobaric vapor-liquid equilibria were determined at 74.66, 101.32, and 127.99 kPa for binary mixtures containing methyl propanoate + n-butyl alcohol by using a dynamic still with vapor and liquid circulation. No azeotrope was detected. The data were found to be thermodynamically consistent according to the point to point test. Application of the group-contribution models ASOG, UNIFAC, and modified UNIFAC to the activity coefficients at the three pressures studied gives average errors of less than 10%, 11%, and 3%, respectively.

Susial, P.; Ortega, J. (Univ. de Las Palmas de Gran Canaria, Canary Islands (Spain). Lab. de Termodinamica y Fisicoquimica)

1993-10-01

10

Vapor-liquid equilibrium of amine-water systems

extraction method for saline water conversion. The investigation of vapor-liquid equilibrium relationships of the solutions of amine and water is an important step towards correlating the effect of molecular structure on the thermodynamic properties... of the interesting properties of water solutions of methyldiethyl amine and other tertiary amines . The work presented here involves the construction of an experi- mental apparatus, and presentation of data determined using that appara- tus for the system of 5...

Chun, Kil Whan

2012-06-07

11

Vapor-liquid equilibrium thermodynamics of N2 + CH4 - Model and Titan applications

NASA Technical Reports Server (NTRS)

A thermodynamic model is presented for vapor-liquid equilibrium in the N2 + CH4 system, which is implicated in calculations of the Titan tropospheric clouds' vapor-liquid equilibrium thermodynamics. This model imposes constraints on the consistency of experimental equilibrium data, and embodies temperature effects by encompassing enthalpy data; it readily calculates the saturation criteria, condensate composition, and latent heat for a given pressure-temperature profile of the Titan atmosphere. The N2 content of condensate is about half of that computed from Raoult's law, and about 30 percent greater than that computed from Henry's law.

Thompson, W. R.; Zollweg, John A.; Gabis, David H.

1992-01-01

12

Isobaric vapor-liquid equilibria of the tetrahydrofuran/ethanol system at 25, 50, and 100 kPa

The vapor-liquid equilibrium of the system tetrahydrofuran (THF)/ethanol at 25, 50, and 100 kPa has been determined experimentally by using an equilibrium still of the recirculation type. Data reduction based on the Wilson, NRTL, and UNIQUAC models provides a correlation for ..gamma.. /SUB i/. The tetrahydrofuran/ethanol system forms an azeotrope above 53 kPa. At 100 and 150 kPa, the azeotropic mixtures contain respectively 0.908 and 0.844 mole fraction of tetrahydrofuran.

Brunner, E.; Scholz, A.G.R.

1984-01-01

13

A cubic equation of state for vapor-liquid equilibrium calculations of nonpolar and polar fluids

A cubic perturbed hard body (CPHB) equation of state (EOS) was developed and applied for vapor-liquid equilibrium (VLE) calculations in this study. The repulsive part of this EOS was investigated in our previous work. It is a simplified expression of hard body equation which yielded satisfactory agreement to the molecular simulation data of hard molecules from a single sphere to

Huei-Tung Wang; Jung-Chin Tsai; Yan-Ping Chen

1997-01-01

14

Isobaric vapor-liquid equilibrium measurements on binary systems of methyl propanoate with ethanol and propan-1-ol are taken at a constant pressure of 101.32 +- 0.02 kPa. These systems exhibit significant deviations from ideality and are shown to be thermodynamically consistent. The methyl propanoate-ethanol system forms an azeotrope at x = y = 0.483 and T = 345.58{Kappa}. Experimental data are fitted to a suitable equation and are likewise compared with the values predicted by the UNIFAC and ASOG models.

Susial, P.; Ortega, J. (Catedra de Termodinamica y Fisicoquimica, Escuela Superior de Ingenieros Industriales, Polytechnic University of Canarias, 35017 Las Palmas, Canary Islands (ES)); DeAlfonso, C.; Alonso, C. (Unidad de Tribologia e Ingenieria Quimica, Instituto Rocasolano, CSIC, Madrid (ES))

1989-04-01

15

This paper reports on isobaric vapor-liquid equilibrium data at 101.32 {plus minus} 0.02 kPa for methyl acetate (1) + ethane (2) or + 1-propanol (2). The results are compared with those predicted by the UNIFAC and ASOG methods. The methyl acetate (1) + ethanol (2) system forms an azeotrope at 329.8 K and a molar concentration of x{sub 1} = 0.958. Both methods predict the vapor-phase compositions equally well, with overall mean errors of less than 5%.

Ortega, J.: Susial, P.; de Alfonso, C. (Catedra de Termodinamica y Fisicoquimica, Escuela Superior de Ingeieros Industriales, 35071 Univ. of Las Palmas (ES))

1990-07-01

16

Condensation coefficient of methanol vapor near vapor-liquid equilibrium states

NASA Astrophysics Data System (ADS)

This paper is concerned with the nonequilibrium condensation from a vapor to a liquid phase on the plate endwall of a shock tube behind a reflected shock wave. The growth of a liquid film on the endwall is measured by an optical interferometer using a laser beam. The experiment is carefully conducted on the precisely designed apparatus, and thereby the condensation coefficient of methanol vapor is determined in a wide range of vapor-liquid conditions from near to far from equilibrium states. The result shows that the condensation coefficient increases with the increase of the ratio of number densities of vapor and saturated vapor at the interface.

Fujikawa, S.; Yano, T.; Ichijo, M.; Iwanami, K.

17

A new vapor-liquid equilibrium apparatus for hydrogen fluoride containing systems

A new circulating type apparatus has been constructed to obtain reliable equilibrium PTxy data for hydrogen fluoride (HF) containing system. Equilibrium cell with Pyrex windows protected by Teflon PFA sheets to prevent the corrosion was used. Isothermal vapor-liquid equilibrium data for the 1,1-difluoroethane (HFC-152a) + HF system at 288.23 and 298.35 K were obtained, and compared with PTx measurement results. Experimental data were correlated using Lencka and Anderko equation of state for HF with the Wong-Sandler mixing rule as well as the van der Waals one fluid mixing rule. The Wong-Sandler mixing rule gives better results. 5 refs., 3 figs.

Jongcheon Lee; Hwayong Kim [Seoul National Univ., Soeul (Korea, Republic of); Jong Sung Lim; Jae-Duck Kim; Youn Yong Lee [CFC Alternatives Technology Center, Seoul (Korea, Republic of)

1996-12-31

18

Vapor-Liquid Equilibrium Measurements of the Binary R32+R125 Refrigerant Mixture

NASA Astrophysics Data System (ADS)

Vapor-liquid equilibrium (VLE) data of the binary R32+R125 refrigerant mixture including R410A (50mass% R32 + 50mass% R125) were obtained by the circulation-type experimental apparatus with a liquid-bath thermostat. VLE measurements were carried out in the temperatures between 263.15 K and 318.15 K and in the pressures between 505 kPa and 2724 kPa. The experimental uncertainties of temperature, pressure, and composition measurements were estimated to be within 3 mK, 0.1 %, and 0.4 %, respectively. The present data were compared with reported experimental data against the REFPROP 6.01 as well as REFPROP 7.0 calculation results.

Higashi, Yukihiro; Miyake, Takeshi; Fujii, Ken-Ichi

19

NASA Astrophysics Data System (ADS)

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor-liquid equilibrium for acid aqueous solutions and acid mixtures. The vapor-liquid equilibrium of hydrofluoric acid + salt systems (fluorite, potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed a salting-out effect on the vapor-liquid equilibrium of the hydrofluoric acid-water system. Fluorite and potassium nitrate showed a salting-in effect on the hydrofluoric acid-water system. Separation of hydrofluoric acid from an acid mixture containing nitric acid and hydrofluoric acid was tested by the simple distillation treatment using the salt effect of cesium nitrate (45 mass%). An acid mixture of nitric acid (5.0 mol · dm-3) and hydrofluoric acid (5.0 mol · dm-3) was prepared as a sample solution for distillation tests. The concentration of nitric acid in the first distillate decreased from 5.0 mol · dm-3 to 1.13 mol · dm-3, and the concentration of hydrofluoric acid increased to 5.41 mol · dm-3. This first distillate was further distilled without the addition of salt. The concentrations of hydrofluoric acid and nitric acid in the second distillate were 7.21 mol · dm-3 and 0.46 mol · dm-3, respectively. It was thus found that the salt effect on vapor-liquid equilibrium of acid mixtures was effective for the recycling of acids from acid mixture wastes.

Yamamoto, Hideki; Sumoge, Iwao

2011-03-01

20

The experimental determinations of vapor-liquid equilibria (VLE) are indispensable for the design of separation processes such as distillation columns, extractive distillation, and selection of solvents. Isobaric vapor-liquid equilibria were obtained for the 1-butanol + N,N-dimethylformamide and 1-pentanol + N,N-dimethylformamide systems at 50.00 and 100.00 kPa. The activity coefficients were found to be thermodynamically consistent. The data were correlated with five liquid phase activity coefficient models (Margules, Van Laar, Wilson, NRTL, and UNIQUAC). Experimental vapor pressures of N,N-dimethylformamide are also included.

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

1995-05-01

21

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 Chlorodifluoromethane CHClF2 + C2ClF5 Chloropentafluoroethane (EVLM1311, LB5621_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

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

22

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 Bromotrifluoromethane CBrF3 + CHClF2 Chlorodifluoromethane (EVLM1311, LB5620_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

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

23

Water activity measurements by isopiestic method have been carried out on the aqueous solutions of alanine+potassium di-hydrogen citrate (KH(2)Cit) and alanine+tri-potassium citrate (K(3)Cit) over a range of temperatures at atmospheric pressure. From these measurements, values of the vapor pressure of solutions were determined. The effect of temperature and charge on the anion of salts on the vapor-liquid equilibrium of the investigated systems has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson and NRTL models. The agreement between the correlations and the experimental data is good. PMID:18448230

Sadeghi, Rahmat; Goodarzi, Baharak

2008-06-01

24

Solvent-refined coal (SRC) process. Vapor-liquid equilibrium measurements for the SRC-II process

This report summarizes vapor-liquid equilibrium studies conducted to support the Solvent Refined Coal project by the Pittsburg and Midway Coal Mining Company under contract with the Department of Energy. Discussed herein are experimental details and results of measurements to obtain vapor-liquid equilibrium data at conditions simulating those which occur during the gas-liquid separation steps in the SRC-II coal liquefaction process. Separation and compositional analyses of liquid and gas phases permitted calculation of the equilibrium K values for the various components of the mixture. Experimental methods and apparatus used in this work were compared to a system recently described in the literature. The measured K values agreed to within an average of +- 5% of published values and showed that the experimental system developed is satisfactory. Internal consistency of each experiment was evaluated by a material balance consistency test, and an average material balance of 99.7% was obtained over the 15 experiments. Data obtained from this work will serve as the basis for K value correlations used in process design calculations for the SRC-II Demonstration Plant.

Henry, R. M.

1980-10-01

25

Quantitative measurements of the partial vapor pressure of formaldehyde are performed above aqueous H2CO solutions of different concentrations (from 10(-5) to 0.3 molar fraction) using mass spectrometry and IR diode laser spectroscopy. Both experimental techniques allow direct probing of the gas phase concentration collected at equilibrium above the aqueous solutions. A correlation is observed between the polymerization processes occurring in the solution and the partial pressure of H2CO measured at vapor liquid equilibrium (VLE). A similar correlation is observed from total pressure measurements for which the equilibrium vapor pressure decreases as [VLE XH2CO]liq is increased. A saturation regime of the H2CO partial pressure is reached as the dissolved fraction of formaldehyde increases above approximately 0.15 mol frac. Henry's law constants are derived at 295K for the diluted solutions. PMID:19238976

Oancea, Adriana; Hanoune, Benjamin; Focsa, Cristian; Chazallon, Bertrand

2009-01-15

26

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

27

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

28

Vapor-liquid equilibrium data were obtained for systems of o-xylene with p- and m-xylenes at 6.66 and 26.66 kPa. The activity coefficients were found to be thermodynamically consistent. They were equally well correlated with the Margules, Van Laar, Wilson, NRTL, and UNIQUAC equations. The parameters of these equations are given.

Llopis, F.J.; Monton, J.B. (Univ. de Valencia (Spain). Dept. de Ingenieria Quimica)

1994-01-01

29

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 Propenenitrile C3H3N + C6H5NO2 Nitrobenzene (EVLM1211, LB5650_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.

30

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 Dimethyl sulfoxide C2H6OS + C6H5Cl Chlorobenzene (EVLM1211, LB5641_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.

31

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 N,N-Dimethylmethanamide C3H7NO + C6H5Br Bromobenzene (EVLM1211, LB5726_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.

32

Vapor-Liquid Equilibrium in the Mixture Water H2O + C6H14N2 1-Ethylpiperazine (EVLM1231, LB5656_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 Water H2O + C6H14N2 1-Ethylpiperazine (EVLM1231, LB5656_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.

33

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 N,N-Dimethylmethanamide C3H7NO + C6H7N Aniline (EVLM1211, LB5728_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.

34

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 Dimethyl sulfoxide C2H6OS + C6H5NO2 Nitrobenzene (EVLM1211, LB5643_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.

35

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 Water H2O + C6H14O2 1-Propoxypropan-2-ol (EVLM1231, LB5718_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.

36

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 Water H2O + C3H5ClO (Chloromethyl)oxirane (EVLM1231, LB5690_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.

37

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 1,2-Dichloroethane C2H4Cl2 + C3H3N Propenenitrile (EVLM1211, LB5647_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.

38

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 1,2-Dichloroethane C2H4Cl2 + C6H10O Cyclohexanone (EVLM1111, LB5653_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.

39

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

40

Measurement and modeling of vapor–liquid equilibria at high salt concentrations

Isobaric vapor–liquid equilibrium data are reported for binary and ternary aqueous mixtures containing LiCl and ZnCl2 at total salt concentrations between 10 and 50wt.%. The measurements were carried out at 5.3, 9.3, 20, 40, and 101.3kPa in a computer-controlled glass apparatus. Particular care was taken to ensure proper equilibration of the high-density, high-viscosity salt mixtures. The equilibrium data spanning temperatures

P. Kolá?; H. Nakata; A. Tsuboi; P. Wang; A. Anderko

2005-01-01

41

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

42

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 N,N-Dimethylmethanamide C3H7NO + C4H9NO N,N-Dimethylethanamide (EVLM1211, LB5727_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.

43

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 1,2-Dichloroethane C2H4Cl2 + C4H10O Diethyl ether (EVLM1311, LB5740_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

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

44

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 1,2-Dichloroethane C2H4Cl2 + C5H12O tert-Butyl methyl ether (EVLM1311, LB5739_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

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

45

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 1,2-Dichloroethane C2H4Cl2 + C6H14O Diisopropyl ether (EVLM1311, LB5741_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

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

46

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

47

Vapor-liquid contacting system

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

48

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

49

Vapor-liquid turbine expansion engines

In the last years vapor-liquid turbine expansion engines have been developed and manufactured at the Geliimash Joint Stock Company, which work on the boiling up of a stream of a cryogenic fluid in the flow-through section of the turbine expansion engine. It is characteristic for a vapor-liquid turbine expansion engine (VLT) that the line of the expansion process intersects the

I. A. Davydenkov; A. B. Davydov; G. A. Perestoronin

1995-01-01

50

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

51

We have developed a crossover scaling model for describing the thermodynamic properties of near-critical binary fluids. We have validated this model for the vapor-liquid equilibrium properties of mixtures of methane and ethane. We then apply the model to a most intriguing binary fluid, namely aqueous solutions of sodium chloride, so as to describe densities and concentrations at vapor-liquid equilibrium and

A. A. Povodyrev; M. A. Anisimov; J. V. Sengers; J. M. H. Levelt Sengers

1997-01-01

52

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

53

Simplified thermodynamic functions for vapor-liquid phase separation and fountain effect pumps

NASA Technical Reports Server (NTRS)

He-4 fluid handling devices near 2 K require novel components for non-Newtonian fluid transport in He II. Related sizing of devices has to be based on appropriate thermophysical property functions. The present paper presents simplified equilibrium state functions for porous media components which serve as vapor-liquid phase separators and fountain effect pumps.

Yuan, S. W. K.; Hepler, W. A.; Frederking, T. H. K.

1984-01-01

54

Isothermal vapor-liquid equilibria for 2-methyl-2-butanol + 2-methyl-1-butanol + 1-pentanol

Vapor-liquid equilibria (VLE) for 2-methyl-2-butanol + 2-methyl-1-butanol and 2-methyl-2-butanol + 2-methyl-1-butanol + 1-pentanol have been measured at 373.15 K. The binary VLE results have been correlated by different liquid-phase activity coefficient models. The binary interaction parameters obtained from Wilson, NRTL, and UNIQUAC models in this and a previously study are used to predict the VLE data for the ternary system. Vapor-liquid equilibrium (VLE) data are necessary for the design of distillation processes.

Aucejo, A.; Burguet, M.C.; Monton, J.B.; Munoz, R.; Sanchotello, M.; Vazquez, M.I. (Univ. of Valencia (Spain). Dept. de Ingenieria Quimica)

1994-07-01

55

Vapor-liquid equilibria for the mixtures ether + 2-butanol and + propyl acetate at 101. 3 kPa

Vapor-liquid equilibrium data at 101.3 kPa pressure for the systems 2-butanol + dibutyl ether, 2-butanol + tetrahydrofuran, propyl acetate + dibutyl ether, and propyl acetate + tetrahydrofuran are reported. The experimental data were well correlated by different thermodynamic equations. The experimental data have also been compared with those predicted by the UNIFAC group contribution method.

Benito, G.G.; Carton, A.; Uruena, M.A. (Univ. of Valladolid (Spain). Dept. of Chemical Engineering)

1994-04-01

56

Fluid density control on vapor-liquid partitioning of metals in hydrothermal systems

NASA Astrophysics Data System (ADS)

Hot aqueous fluids, both vapor and saline liquid, are primary transporting media for metals in hydrothermal-magmatic systems. Despite the growing geological evidence that the vapor phase, formed through boiling of magmatic ore-bearing fluids, can selectively concentrate and transport metals, the physical-chemical mechanisms that control the metal vapor-liquid fractionation remain poorly understood. We performed systematic experiments to investigate the metal vapor-liquid partitioning in model water-salt-gas systems H2O-NaCl-KCl-HCl at hydrothermal conditions. Measurements show that equilibrium vapor-liquid fractionation patterns of many metals are directly related to the densities of the coexisting vapor and liquid phases. Despite differences in the vapor-phase chemistry of various metals that form hydroxide, chloride, or sulfide gaseous molecules of contrasting volatile properties, water-solute interaction is a key factor that controls the metal transfer by vapor-like fluids in Earth's crust. These findings allow quantitative prediction of the vapor-liquid distribution patterns and vapor-phase metal transport in a wide range of conditions. Our density model accounts well for the vapor-brine distribution patterns of Na, Si, Fe, Zn, As, Sb, and Ag observed in fluid inclusions from magmatic-hydrothermal deposits. For Au and Cu, the partitioning in favor of the liquid phase, predicted in a sulfur-free system, contrasts with the copper and gold enrichment observed in natural vapor-like inclusions. The formation of stable complexes of Cu and Au with reduced sulfur may allow for their enhanced transport by sulfur-enriched magmatic-hydrothermal vapors.

Pokrovski, Gleb S.; Roux, Jacques; Harrichoury, Jean-Claude

2005-08-01

57

The effect of sulfur on vapor liquid fractionation of metals in hydrothermal systems

NASA Astrophysics Data System (ADS)

Despite the growing evidence that the vapor phase, formed through magma degassing and ore fluid boiling, can selectively concentrate and transport metals, the effects of major volatile components like sulfur, chlorine or carbon dioxide on the metal vapor-liquid fractionation and vapor-phase transport under magmatic-hydrothermal conditions remain poorly known. We performed systematic experiments to investigate the effect of sulfur ligands on metal vapor-liquid partitioning in model H 2O-S-NaCl-KCl-NaOH systems at temperatures from 350 to 500 °C. Results show that at acidic-to-neutral conditions, vapor-liquid equilibrium distribution coefficients, Km = mvapor / mliquid, where m is the mass concentration of the metal in corresponding phase, of metalloids (As, Sb) and base metals (Zn, Fe, Pb, Ag) are in the range 0.1-1.0 and 0.001-0.1, respectively, and are not significantly affected by the presence of geologically common sulfur concentrations, up to 1-3 wt.% S. In contrast, the partitioning of Cu, Au, and Pt into the vapor increases by a factor of 100 in comparison to the S-free water-salt system, yielding Km values of 0.5-1.0, 1-10, and 10-20, respectively, due to formation of volatile neutral complexes with H 2S and, possibly, SO 2. In neutral-to-basic systems, Zn, Pb, Fe and Ag show 10-100-fold increase of their partition coefficients, whereas Cu, Au and Pt exhibit Km values of up to several orders of magnitude lower, compared to acidic conditions at similar temperature, pressure and sulfur contents. These vapor-liquid distribution patterns result from combined effects of i) formation of volatile species with reduced sulfur ligands in the vapor phase, ii) changes in the metal speciation in the coexisting liquid phase as a function of pH, and iii) solute-solvent interactions in both phases. Our data explain the vapor-liquid fractionation trends for many metals as inferred in coexisting brine and vapor inclusions from magmatic-hydrothermal deposits, and provide a first experimental evidence for the dramatic increase of the mobility of Cu, Au and Pt in sulfur-enriched acidic magmatic-hydrothermal vapors, consistent with geological models of Au ± Cu ores formation and distribution in porphyry-epithermal settings.

Pokrovski, Gleb S.; Borisova, Anastassia Yu.; Harrichoury, Jean-Claude

2008-02-01

58

NASA Astrophysics Data System (ADS)

We have developed a crossover scaling model for describing the thermodynamic properties of near-critical binary fluids. We have validated this model for the vapor-liquid equilibrium properties of mixtures of methane and ethane. We then apply the model to a most intriguing binary fluid, namely aqueous solutions of sodium chloride, so as to describe densities and concentrations at vapor-liquid equilibrium and isochoric specific heat capacities in the one-phase region. The description shows crossover from asymptotic Ising-like critical behavior to classical (mean-field) behavior. As the salt concentration increases, the region of Ising behavior decreases, although pure classical behavior is never attained. We suggest that processes of association/dissociation may be responsible for the failure of the model to describe compositions of the vapor phase of the solutions at very low concentrations.

Povodyrev, A. A.; Anisimov, M. A.; Sengers, J. V.; Levelt Sengers, J. M. H.

1997-02-01

59

A reformulated version of the Wong-Sandler mixing rule and the Peng-Robinson equation of state are used for the correlation and prediction of the vapor-liquid equilibrium of several alkanol + alkane binary systems. The description of these mixtures provides a stringent test since cubic equations of state with conventional mixing rules usually predict false liquid-liquid splits for such systems. For all

H. Orbey; S. I. Sandier

1995-01-01

60

A field-space conformal-solution method: Binary vapor-liquid phase behavior

NASA Astrophysics Data System (ADS)

The field-space conformal solution method provides an entirely new thermodynamic framework for the description of fluid mixtures in terms of the properties of a pure reference fluid. The utility and performance of the method are examined in the special case of vapor-liquid equilibrium correlation for simple mixtures. This is one of several cases in which field-space methods have numerical or theoretical advantages over methods presently used in mixture property correlation; only properties along the vapor pressure curve of the purefluid reference system are required for a complete description of the mixture phase behavior. Vapor-liquid equilibrium data for three binary hydrocarbon mixtures, n-butane + n-pentane, n-butane + n-hexane, and n-butane + n-octane, are correlated with a simple implementation of the method having two independent mixture parameters. Two pure-fluid equations of state, a Peng-Robinson equation and a 32-constant modified Benedict-Webb-Rubin equation, are tested as reference systems. The effects of differences in the quality of the reference system and of a range of mixture component size ratios are examined.

Storvick, T. S.; Fox, J. R.

1990-01-01

61

Automatic isochoric apparatus for PVT and phase equilibrium studies of natural gas mixtures

................................................................................................................. 5 LITERATURE REVIEW................................................................................................ 7 High Pressure Vapor-Liquid Equilibrium Measurement ......................................... 7 Visual Methods... ......................................................................................................... 21 4. Ring cell cross sections. ........................................................................................ 23 5. Data acquisition and control...

Zhou, Jingjun

2009-05-15

62

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

63

Vapor-liquid equilibria for hydrogen fluoride + 1,1-difluoroethane at 288.23 and 298.35 K

Isothermal vapor-liquid equilibria for hydrogen fluoride + 1,1-difluoroethane at 288.23 and 298.35 K were measured using a circulation type apparatus equipped with an equilibrium view cell. The compositions of both vapor and liquid phases were analyzed by an on-line gas chromatographic method. They were compared with PTx equilibrium data measured by the total pressure method. The experimental data were correlated with Anderko`s equation of state using the Wong-Sandler mixing rule as well as the van der Waals one-fluid mixing rule. The Wong-Sandler mixing rule gives better results, and the relevant parameters are presented.

Lee, J.; Kim, H. [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering] [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering; Lim, J.S.; Kim, J.D.; Lee, Y.Y. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Alternatives Technology] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Alternatives Technology

1997-07-01

64

Silicon MEMS vaporizing liquid microthruster with internal microheater

This paper reports a silicon MEMS vaporizing liquid microthruster (VLM) with an internal p-diffused microheater. The device fabrication and testing have been briefly described. The VLM consisting of two micromachined, bonded silicon chips produces thrusts in the range of 5 µN to 120 µN with a heater power of 1 W to 2.4 W at a water flow rate of

D K Maurya; S Das; S K Lahiri

2005-01-01

65

Toward a Monte Carlo program for simulating vapor-liquid phase equilibria from first principles

Efficient Monte Carlo algorithms are combined with the Quickstep energy routines of CP2K to develop a program that allows for Monte Carlo simulations in the canonical, isobaric-isothermal, and Gibbs ensembles using a first principles description of the physical system. Configurational-bias Monte Carlo techniques and pre-biasing using an inexpensive approximate potential are employed to increase the sampling efficiency and to reduce the frequency of expensive ab initio energy evaluations. The new Monte Carlo program has been validated through extensive comparison with molecular dynamics simulations using the programs CPMD and CP2K. Preliminary results for the vapor-liquid coexistence properties (T = 473 K) of water using the Becke-Lee-Yang-Parr exchange and correlation energy functionals, a triple-zeta valence basis set augmented with two sets of d-type or p-type polarization functions, and Goedecker-Teter-Hutter pseudopotentials are presented. The preliminary results indicate that this description of water leads to an underestimation of the saturated liquid density and heat of vaporization and, correspondingly, an overestimation of the saturated vapor pressure.

McGrath, M; Siepmann, J I; Kuo, I W; Mundy, C J; Vandevondele, J; Sprik, M; Hutter, J; Mohamed, F; Krack, M; Parrinello, M

2004-10-20

66

High-pressure vapor-liquid equilibria for mixtures containing a supercritical fluid

Supercritical fluid extraction has been proven as an efficient separation method for some specific industrial applications. The knowledge of the phase behavior of supercritical systems plays an important role in the process design. High pressure vapor-liquid phase equilibrium compositions were measured for the binary systems of carbon dioxide + 2-methyl-1-pentanol, carbon dioxide + 1-octanol, and carbon dioxide + 1-decanol over a temperature range between 348.15 and 453.15 K. In addition to the new data, a variety of supercritical fluid systems was used to test the validity of the Peng-Robinson and Patel-Teja equations of state accompanied by several types of mixing rules. In general, the Peng-Robinson equation incorporated with the cubic mixing rule yielded the best representation.

Weng, W.L. (Ming-Hsin Engineering College, Hsinchu (Taiwan, Province of China). Dept. of Chemical Engineering); Chen, J.T.; Lee, M.J. (National Taiwan Inst. of Technology, Taipei (Taiwan, Province of China). Dept. of Chemical Engineering)

1994-08-01

67

Determination of binary mixture vapor-liquid critical densities from coexisting density data

NASA Astrophysics Data System (ADS)

Two-phase vapor-liquid equilibrium (VLE) isochores for binary mixtures are defined as the thermodynamic paths along which the overall density and composition are fixed. Data along such isochores are generated from a modified Leung-Griffiths model fit to experimental data for the binary system nitrogen-methane. The behavior of the liquid volume fraction along these isochores is found to be similar to that for pure fluids. Rectilinear diameters for varying overall densities (fixed composition) are seen to be nearly coincident. Straight-line diameters and the critical liquid volume fraction method are utilized to predict critical densities using data near and removed from the critical point. Both methods give acceptable results but the critical liquid volume fraction method is more accurate. A critical literature review of the need for binary mixture critical densities is presented and a proposed experimental procedure is given for the determination of mixture critical densities.

van Poolen, L. J.; Rainwater, J. C.

1987-11-01

68

We use in situ observations during high-temperature transmission electron microscopy to quantify the exchange of semiconductor material between Au-Ge vapor--liquid--solid seed drops and Ge nanowires (NWs). By performing simultaneous measurements under identical conditions on arrays with systematic variations in NW diameter, we establish the nanoscale size dependence of the temperature-dependent equilibrium composition of the Au-Ge binary alloy. We find a significantly enhanced Ge solubility for drops on thin NWs compared to thicker ones. The controlled modification of the surface of the NW by an ordered carbon shell leads to drastic changes in the solubility. PMID:20731466

Sutter, Eli A; Sutter, Peter W

2010-08-24

69

Isothermal-vapor-liquid equilibrium data of the rapeseed oil-carbon dioxide system were measured with a vapor-recirculation apparatus at 313.15, 333.15, 353.15, and 373.15 K at pressures between 10 and 85 MPa. The solubilities of rapeseed oil in carbon dioxide were compared with solubility data of other vegetable oils from the literature. A lattice model equation of state (EOS) is used to describe the rapeseed oil-carbon dioxide system. The lattice EOS was improved by introducing a more accurate EOS for carbon dioxide (Bender EOS) into the model. With the Kumar-Bender model and a tree-binary-parameter, composition- and density-dependent combining rule proposed by Wilczek-Vera and Vera, a quantitative description of phase equilibrium is obtained. The temperature dependence of the binary parameters has been evaluated for interpolation or extrapolation purposes.

Klein, T.; Schulz, S. (Lehrstuhl fur Thermodynamik, Abteilung Chemietechnik, Universitat Dortmund, D-4600 Dortmund 50 (DE))

1989-07-01

70

Vapor-liquid equilibrium (VLE) data for the binary systems of benzene/toluene, diphenylmethane/toluene, m-cresol/1,2,3,4-tetrahydronaphthalene, and benzene/quinoline were measured at low to moderate pressures (0-1733 kPa) by using a static equilibrium cell. The data were isothermally correlated by using the Peng-Robinson equation of state to describe both vapor and liquid phases. The data were also correlated by using the Peng-Robinson equation of state to describe the vapor phase and the universal quasi-chemical (UNIQUAC) excess Gibbs free energy expression for the liquid phase.

Klara, S.M.; Mohamed, R.S.; Dempsey, D.M.; Holder, G.D.

1987-04-01

71

The behavior of thermodynamic response functions and the thermodynamic scalar curvature in the supercritical region have been studied for a Lennard-Jones fluid based on a revised modified Benedict-Webb-Rubin equation of state. Response function extrema are sometimes used to estimate the Widom line, which is characterized by the maxima of the correlation lengths. We calculated the Widom line for the Lennard-Jones fluid without using any response function extrema. Since the volume of the correlation length is proportional to the Riemannian thermodynamic scalar curvature, the locus of the Widom line follows the slope of maximum curvature. We show that the slope of the Widom line follows the slope of the isobaric heat capacity maximum only in the close vicinity of the critical point and that, therefore, the use of response function extrema in this context is problematic. Furthermore, we constructed the vapor-liquid coexistence line for the Lennard-Jones fluid using the fact that the correlation length, and therefore the thermodynamic scalar curvature, must be equal in the two coexisting phases. We compared the resulting phase envelope with those from simulation data where multiple histogram reweighting was used and found striking agreement between the two methods. PMID:22587083

May, Helge-Otmar; Mausbach, Peter

2012-03-01

72

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

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

73

Simulating vapor-liquid nucleation of n-alkanes

NASA Astrophysics Data System (ADS)

A combination of the aggregation-volume-bias Monte Carlo algorithm, the configurational-bias Monte Carlo algorithm, and the umbrella sampling technique was applied to investigate homogeneous vapor-liquid nucleation in ethane, n-butane, and n-heptane. The simple transferable potentials for phase equilibria-united atom (TraPPE-UA) force field was used in this investigation. It was found that for the n-heptane case, the TraPPE-UA force field predicted a nucleation rate that is about three to four orders of magnitude higher than that measured by an upward thermal diffusion cloud chamber experiment. Comparison of the simulation results to the classical nucleation theory (CNT) shows that CNT consistently overestimates the barrier heights for all chain lengths investigated. The offset on the barrier heights was found nearly independent of the supersaturation for both ethane and n-butane, similar to a Lennard-Jones system previously studied. This also directly leads to a good agreement on the cluster sizes between the simulation and the CNT calculated from the nucleation theorem. For n-heptane, however, the offset was found to depend on the supersaturation. It appears that CNT predicts a slightly weaker dependence of the nucleation rate on supersaturation, which agrees with both density functional calculations and the experiments. Structural analysis demonstrates that the orientational order near the surface differs significantly between the critical nucleus and the bulk planar liquid-vapor interface for n-heptane systems, whereas the density in the interior of the critical nucleus is in good agreement with the bulk liquid density. The different surface ordering offers a microscopic explanation for the differences observed for n-heptane between the CNT on one side and experimental observations and simulations on the other side.

Chen, Bin; Siepmann, J. Ilja; Oh, Kwang J.; Klein, Michael L.

2002-03-01

74

Design, fabrication and performance evaluation of a vaporizing liquid microthruster

NASA Astrophysics Data System (ADS)

A recent application domain of MEMS technology is in the development of microthrusters for micro-/nanosatellites. Among the various types of MEMS microthruster developed so far, the vaporizing liquid microthruster (VLM) has been widely explored for its capability to produce continuously variable thrust in the micro-Newton (µN) to mili-Newton (mN) range. This paper reports the design and experimental validation of silicon MEMS VLM consisting of a microcavity, inlet channel and converging-diverging (C-D) in-plane exit nozzle integrated in two micromachined bonded chips and sandwiched between two p-diffused microheaters, located at the top and bottom surface of the device. Structural configuration was designed using simple analytical equations to achieve maximum thrust force by controlling the inlet propellant flow and heater power of VLM in an efficient way. In addition, a 3D model using a computational fluid dynamics technique was constructed to simulate the aft section of VLM for the investigation of its aerodynamic behavior. The device fabrication and testing have been briefly described. The fabricated VLM is capable to produce 1 mN thrust using maximum heater power of 3.6 W at a water flow rate of 2.04 mg s-1 using an in-plane C-D exit nozzle of throat area 130 µm × 100 µm. A detailed thrust force measurement was carried out with the variation of input heater power for different mass flow conditions and exit to throat area ratio of the exit nozzle, and the results were interpreted with the theoretical model. The model gives considerable physical insight in the operation of the VLM. Finally, a performance comparison with other published VLM results indicates that the present design can yield comparatively more thrust force with much less input power. A performance comparison with other published VLM results indicates that the present design can achieve improved performance by integrating two heaters with appropriate chamber volume in respect of propellant flow rate and input power for obtaining a supersaturated dry stream.

Kundu, Pijus; Kanti Bhattacharyya, Tarun; Das, Soumen

2012-02-01

75

Vapor-liquid phase coexistence and transport properties of two-dimensional oligomers

NASA Astrophysics Data System (ADS)

Grand-canonical transition-matrix Monte Carlo and histogram reweighting techniques are used herein to study the vapor-liquid coexistence properties of two-dimensional (2D) flexible oligomers with varying chain lengths (m = 1-8). The phase diagrams of the various 2D oligomers follow the correspondence state (CS) principle, akin to the behavior observed for bulk oligomers. The 2D critical density is not influenced by the oligomer chain length, which contrasts with the observation for the bulk oligomers. Line tension, calculated using Binder's formalism, in the reduced plot is found to be independent of chain length in contrast to the 3D behavior. The dynamical properties of 2D fluids are evaluated using molecular dynamics simulations, and the velocity and pressure autocorrelation functions are investigated using Green-Kubo (GK) relations to yield the diffusion and viscosity. The viscosity determined from 2D non-equilibrium molecular dynamics simulation is compared with the viscosity estimated from the GK relations. The GK relations prove to be reliable and efficient for the calculation of 2D transport properties. Normal diffusive regions are identified in dense oligomeric fluid systems. The influence of molecular size on the diffusivity and viscosity is found to be diminished at specific CS points for the 2D oligomers considered herein. In contrast, the viscosity and diffusion of the 3D bulk fluid, at a reduced temperature and density, are strongly dependent on the molecular size at the same CS points. Furthermore, the viscosity increases and the diffusion decreases multifold in the 2D system relative to those in the 3D system, at the CS points.

Patra, Tarak K.; Hens, Abhiram; Singh, Jayant K.

2012-08-01

76

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

77

The phase equilibria (experimental and modeled) of eight binary mixtures each formed by a cyclic ether (1,3-dioxolane or 1,4-dioxane) and a chlorobutane isomer (1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, or 2-chloro-2-methylpropane) are presented. New experimental vapor-liquid equilibrium data at isothermal conditions (298.15, 313.15, and 328.15 K) has been obtained, and the statistical associating fluid theory for potentials of variable range (SAFT-VR) is used to model the mixtures. The results are discussed in terms of both the molecular characteristics of the pure compounds and the unlike intermolecular interactions present in the mixtures. The SAFT-VR approach is first used together with standard combining rules without adjustable parameters in order to predict the phase behavior at isothermal conditions. Good agreement between experiment and the prediction is found with such a model. Mean absolute deviations for pressures lie between 1 and 3 kPa, while for vapor phase compositions are less than 0.03 in mole fraction. However, a better agreement, can be obtained by introducing one adjustable parameter kij, which modifies the strength of the dispersion interaction between unlike components in the mixtures. This parameter is adjusted so as to model the phase equilibrium of the whole family of mixtures studied here at isothermal and isobaric conditions. We find that a unique unlike parameter kij is valid for all the studied mixtures and it is not temperature or pressure dependent. This unique transferable parameter together with the SAFT-VR approach provide a description of the vapor-liquid equilibrium of the mixtures that is in excellent agreement with the experimental data. In this case, the absolute deviations are of the order of 0.001 in mole fraction for vapor-phase compositions and less than 1 kPa for pressure. PMID:17658794

Giner, Beatriz; Gascón, Ignacio; Artigas, Héctor; Lafuente, Carlos; Galindo, Amparo

2007-08-16

78

Vapor-liquid equilibrium data were measured for binary systems of 1-butanol with 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol at 30 and 100 kPa. The experimental data obtained in this work are thermodynamically consistent according to a point-to-point consistency test, and deviation from ideal behavior is small in all cases. They can be equally well correlated with the Margules, Van Laar, Wilson, NRTL, and UNIQUAC equations.

Aucejo, A.; Burguet, M.C.; Monton, J.B.; Munoz, R.; Sanchotello, M.; Vazquez, M.I. (Univ. de Valencia (Spain). Dept. de Ingenieria Quimica)

1994-04-01

79

The associative property of artificial neural networks (ANNs) and their inherent ability to “learn” and “recognize” highly non-linear and complex relationships finds them ideally suited to a wide range of applications in chemical engineering. Dynamic Modeling and Control of Chemical Process Systems and Fault Diagnosis are the two significant applications of ANNs that have been explored so far with success.

Raj Sharma; Diwakar Singhal; Ranjana Ghosh; Ashish Dwivedi

1999-01-01

80

Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water at 35 70 C

as it was an experience I will always cherish. George Goff may very well have been the most important member of Dr after he left the group, and I am extremely appreciative of that. Mark Nelson from Air Quality with during my stay at the University of Texas. He has provided me with invaluable experience working in pilot

Rochelle, Gary T.

81

caused by poor distributor design or an unusual reactor- to-particle diameter may cause parts of a packed bed to be dry. This is described as reactor-scale incomplete contacting. Catalyst particles in a packed bed may be incompletely wetted even when... caused by poor distributor design or an unusual reactor- to-particle diameter may cause parts of a packed bed to be dry. This is described as reactor-scale incomplete contacting. Catalyst particles in a packed bed may be incompletely wetted even when...

Mills, Anna Lisa

2012-06-07

82

(for water: the SPC-, SPC/E-, and TIP4P-potential models; for carbon dioxide: the EPM2 potential model. The interactions between carbon dioxide and water were estimated from the pair potentials of the pure components of intermolecular pair potentials for various substances is documented. Especially water has been the subject

83

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

84

The effect of a polyol ester lubricant on equilibrium pressure, liquid density, and viscosity is presented for R-22, R-125, and R-134a at varying temperatures and concentrations. Preliminary vapor-liquid equilibrium (VLE) data and miscibility observations are also presented for an R-32/R-125 blend (50%/50%) with the ISO 68 polyol ester (POE). Real-gas behavior is modeled using the vapor-phase fugacity, and vapor pressure effects on liquid fugacities are taken into account with the Poynting effect. Positive, negative, and mixed deviations form the Lewis-Randall rule are observed in the activity coefficient behavior. Departures from ideality are related to molecular size differences, intermolecular forces in the mixture, and other factors. The data are discussed in the context of previous results for other refrigerants and thermodynamic modeling of refrigerant and oil mixtures.

Martz, W.L. [Ford Motor Co., Dearborn, MI (United States). Climate Control Div.; Burton, C.M.; Jacobi, A.M. [Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering

1996-11-01

85

Universal adsorption at the vapor-liquid interface near the consolute point

NASA Technical Reports Server (NTRS)

The ellipticity of the vapor-liquid interface above mixtures of methylcyclohexane (C7H14) and perfluoromethylcyclohexane (C7F14) has been measured near the consolute point T(c) = 318.6 K. The data are consistent with a model of the interface that combines a short-ranged density-vs height profile in the vapor phase with a much longer-ranged composition-versus-height profile in the liquid. The value of the free parameter produced by fitting the model to the data is consistent with results from two other simple mixtures and a mixture of a polymer and solvent. This experiment combines precision ellipsometry of the vapor-liquid interface with in situ measurements of refractive indices of the liquid phases, and it precisely locates the consolute point.

Schmidt, James W.

1990-01-01

86

An analytical model of a silicon MEMS vaporizing liquid microthruster and some experimental studies

A recent application of the MEMS technology is in the field of microthrusters for micro\\/nano satellites. A silicon MEMS vaporizing liquid microthruster (VLM) produces continuously variable thrust in the range from ?N to mN. The theoretical simulation of a VLM involves complex numerical 3D micro-fluidic, thermodynamic and electro-thermal solutions. A fast analytical method is, however, desirable in the initial phase

D. K. Maurya; S. Das; S. K. Lahiri

2005-01-01

87

Molecular simulations of the (vapor+liquid) equilibria (VLE) for benzene, cyclohexane, and (benzene+hydrogen) and (cyclohexane+hydrogen) were carried out using the Gibbs-ensemble Monte Carlo method with configurational bias. The Buckingham exponential six (exp-6) potential was used for the site–site interactions with no binary interaction parameters; benzene and cyclohexane were described with six interaction sites, and hydrogen with a single site. Simulation results,

J. Carrero-Mantilla

2008-01-01

88

On the Electronic Nature of the Surface Potential at the Vapor-Liquid Interface of Water

The surface potential at the vapor-liquid interface of water is relevant to many areas of chemical physics. Measurement of the surface potential has been experimentally attempted many times, yet there has been little agreement as to its magnitude and sign (-1.1 to +0.5 mV). We present the first computation of the surface potential of water using ab initio molecular dynamics. We find that the surface potential {chi} = -18 mV with a maximum interfacial electric field = 8.9 x 10{sup 7} V/m. A comparison is made between our quantum mechanical results and those from previous molecular simulations. We find that explicit treatment of the electronic density makes a dramatic contribution to the electric properties of the vapor-liquid interface of water. The E-field can alter interfacial reactivity and transport while the surface potential can be used to determine the 'chemical' contribution to the real and electrochemical potentials for ionic transport through the vapor-liquid interface.

Kathmann, S M; Kuo, I; Mundy, C J

2008-02-05

89

NASA Astrophysics Data System (ADS)

We present a study of indium phosphide nanowires grown by the selective area vapor liquid solid technique using metalorganic molecular beam epitaxy. Transmission electron microscopy revealed that nanowires grown at a temperature of up to 450 °C had a pure wurtzite structure, but at 480 °C a mixed wurtzite-zincblend structure was obtained. We also accurately measured the migration length of growth precursors along the side facets of the nanowires by monitoring the length of the non-tapered section of the nanowire adjacent to the gold catalyst. The migration length was found to be of the order of 0.3-0.7 ?m and to depend on the diameter of the nanowire. Up to the growth temperature of 450 °C the migration length was temperature independent, but it increased dramatically to more than 2 ?m when the nanowires were grown at 480 °C. Possible explanations for the observed effects are suggested.

Greenberg, Ya'akov; Kelrich, Alex; Calahorra, Yonatan; Cohen, Shimon; Ritter, Dan

2014-03-01

90

The influence of the liquid slab thickness on the planar vapor-liquid interfacial tension

One of the long standing challenges in molecular simulation is the description of interfaces. On the molecular length scale, finite size effects significantly influence the properties of the interface such as its interfacial tension, which can be reliably investigated by molecular dynamics simulation of planar vapor-liquid interfaces. For the Lennard-Jones fluid, finite size effects are examined here by varying the thickness of the liquid slab. It is found that the surface tension and density in the center of the liquid region decreases significantly for thin slabs. The influence of the slab thickness on both the liquid density and the surface tension is found to scale with 1/S^3 in terms of the slab thickness S, and a linear correlation between both effects is obtained. The results corroborate the analysis of Malijevsk\\'y and Jackson, J. Phys.: Cond. Mat. 24: 464121 (2012), who recently detected an analogous effect for the surface tension of liquid nanodroplets.

Werth, Stephan; Horsch, Martin; Hasse, Hans

2013-01-01

91

The influence of the liquid slab thickness on the planar vapor-liquid interfacial tension

One of the long standing challenges in molecular simulation is the description of interfaces. On the molecular length scale, finite size effects significantly influence the properties of the interface such as its interfacial tension, which can be reliably investigated by molecular dynamics simulation of planar vapor-liquid interfaces. For the Lennard-Jones fluid, finite size effects are examined here by varying the thickness of the liquid slab. It is found that the surface tension and density in the center of the liquid region decreases significantly for thin slabs. The influence of the slab thickness on both the liquid density and the surface tension is found to scale with 1/S^3 in terms of the slab thickness S, and a linear correlation between both effects is obtained. The results corroborate the analysis of Malijevsk\\'y and Jackson, J. Phys.: Cond. Mat. 24: 464121 (2012), who recently detected an analogous effect for the surface tension of liquid nanodroplets.

Stephan Werth; Sergey Lishchuk; Martin Horsch; Hans Hasse

2013-01-11

92

Rapid thermal annealing effects on tin oxide nanowires prepared by vapor-liquid-solid technique

NASA Astrophysics Data System (ADS)

Tin oxide nanowires have been grown on p-type silicon substrates using a gold-catalyst-assisted vapor-liquid-solid growth process. The nanowires were annealed in the presence of oxygen at 700 °C for different time intervals. The changes in material properties of the nanowires after annealing were investigated using various characterization techniques. Annealing improves the crystal quality of the nanowires as seen from Raman spectroscopy analysis. Photoluminescence (PL) data indicates a decrease in the oxygen vacancies and defects after annealing, affecting the luminescence from the nanowires. In addition, x-ray photoelectron spectroscopy (XPS) was used to obtain the changes in the tin and oxygen atomic concentrations before and after annealing, from which the stoichiometry was calculated.

Kar, Ayan; Yang, Jianyong; Dutta, Mitra; Stroscio, Michael A.; Kumari, Jyoti; Meyyappan, M.

2009-02-01

93

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

NASA Astrophysics Data System (ADS)

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.; Avinash, K.; Sen, A.; Ganesh, R.

2014-10-01

94

Excitation spectrum of the vapor-liquid sup 4 He interface

We analyze the elementary excitations in a vapor-liquid {sup 4}He interface with planar symmetry under saturation conditions. They are characterized by a momentum {h bar}{bold q} parallel to the interface plane and may be described by bound or continuum states. The wave functions of bound states are confined to the interface region. The continuum states may be described by their properties in the asymptotic region far apart from the interface layer. There, they are representing plane waves with momentum {h bar}{bold q}{sub {ital L}} and/or {h bar}{bold q}{sub {ital V}} vertical to the interface plane. The dispersion of these waves is determined by the energy-momentum relation in bulk liquid or vapor {sup 4}He. We may distinguish liquid, vapor, or vapor-liquid continuum states. The wave functions and energies are numerically evaluated in a generalized Feynman approximation, at various temperatures, 0{le}{ital T}{le}2 K. At nonvanishing temperatures, the wave functions of bound states represent rotons with wave number {ital q}{congruent}{ital q}{sub {ital R}}=1.8 A {sup {minus}1} trapped in the interface layer. At zero temperature, bound states appear at any wave number 0.2 A {sup {minus}1}{le}{ital q}{le}{ital q}{sub {ital R}} describing excitations of the free {sup 4}He surface. At temperatures 0{lt}{ital T}{le}1.5 K, the numerical results show that there are resonant vapor continuum states that have a very small amplitude in the asymptotic vapor region but develop an anomalously large amplitude in the interface layer. Our results on the excitation energies and on the corresponding wave functions in the interface region are displayed in a series of figures and are discussed in detail.

Gernoth, K.A.; Ristig, M.L. (Institut fuer Theoretische Physik, Universitaet zu Koeln, D-5000 Koeln 41 (Germany))

1992-02-01

95

such as proteins,3Â6 glasses,8Â10 and atomic clusters,11,12 where methods based on sampling the conventionalOrder parameter free enhanced sampling of the vapor-liquid transition using the generalized replica exchange method Qing Lu, Jaegil Kim, and John E. Straub Citation: J. Chem. Phys. 138, 104119 (2013); doi

Straub, John E.

96

calculation that indium antimonide InSb nanowires can possess improved thermoelectric properties compared the thermopower and electrical conductivity of an individual InSb nanowire grown using a vapor-liquid-solid method antimonide InSb is a small band gap semicon- ductor with high carrier mobility and small effective mass

Shi, Li

97

Survey of Evaluated Isobaric Analog States

NASA Astrophysics Data System (ADS)

Isobaric analog states (IAS) can be used to estimate the masses of members belonging to the same isospin multiplet. Experimental and estimated IAS have been used frequently within the Atomic Mass Evaluation (AME) in the past, but the associated set of evaluated masses have been published for the first time in AME2012 and NUBASE2012. In this paper the current trends of the isobaric multiplet mass equation (IMME) coefficients are shown. The T = 2 multiplet is used as a detailed illustration.

MacCormick, M.; Audi, G.

2014-06-01

98

Deconvolution of isobaric interferences in mass spectra

The concept of isobar deconvolution using the mass domain and signal intensity based domains is described. The intensity domain-based\\u000a approach employs the reconstruction of the observed isotope pattern from the isolated patterns of the isobaric species. The\\u000a quantitative information is adjusted with the use of the least squares algorithm. The mass domain-based approach employs signal\\u000a deconvolution by forming Gaussian components

Juris Meija; Joseph A. Caruso

2004-01-01

99

Platinum Assisted Vapor-Liquid-Solid Growth of Er-Si Nanowires and Their Optical Properties

We report the optical activation of erbium coated silicon nanowires (Er–SiNWs) grown with the assist of platinum (Pt) and gold (Au), respectively. The NWs were grown on Si substrates by using a chemical vapor transport process using SiCl4 and ErCl4 as precursors. Pt as well as Au worked successfully as vapor–liquid–solid (VLS) catalysts for growing SiNWs with diameters of ~100 nm and length of several micrometers, respectively. The SiNWs have core–shell structures where the Er-crystalline layer is sandwiched between silica layers. Photoluminescence spectra analyses showed the optical activity of SiNWs from both Pt and Au. A stronger Er3+ luminescence of 1,534 nm was observed from the SiNWs with Pt at room- and low-temperature (25 K) using the 488- and/or 477-nm line of an Ar laser that may be due to the uniform incorporation of more Er ions into NWs with the exclusion of the formation of catalyst-induced deep levels in the band-gap. Pt would be used as a VLS catalyst for high performance optically active Er–SiNWs. PMID:20672113

2010-01-01

100

Carbothermal synthesis of TaC whiskers via a vapor-liquid-solid growth mechanism

Tantalum carbide whiskers have been synthesized via a vapor-liquid-solid (VLS) growth mechanism in the temperature region 1200{endash}1300{degree}C in nitrogen or argon. The starting materials consisted of Ta{sub 2}O{sub 5}, C, Ni and NaCl. Carbon was added to reduce tantalum pentoxide, via a carbothermal reduction process, and Ni was used to catalyze the whisker growth. Thermodynamic calculations showed that tantalum is transported in the vapor phase as an oxochloride rather than as a chloride. An alkali metal chloride such as NaCl can be used as a source of Cl. The formation of TaC whiskers was found to be strongly dependent on the processing conditions used, on the choice of precursor materials, e.g., their particle sizes, and on the mixing procedure. So far we have obtained TaC whisker in a yield of 75{endash}90 vol{percent}. These whiskers are 0.1{endash}0.6 {mu}m in diameter and 10{endash}30 {mu}m in length, and they are straight and exhibit smooth surfaces. The main impurities are TaC particles, minor amounts of unreacted carbon, and remnants of the Ni catalyst. {copyright} {ital 1997 Materials Research Society.}

Johnsson, M.; Nygren, M. [Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

1997-09-01

101

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

102

Exciplex-based vapor/liquid visualization systems appropriate for automotive gasolines

This paper reports the development of exciplex-based vapor/liquid visualization systems based on exciplexes formed from tertiary amines and fluorine-substituted benzene and/or toluene. These systems are expected to be virtually coevaporative with solvents (fuels) boiling in the temperature range 70 to 110[degrees]C and thus are expected to track the vaporization of automotive gasoline effectively. A system consisting of 10% n-propyldiethylamine/0.5% 4-fluorotoluene/89.5% isooctane should be coevaporative with a normal boiling point of approximately 100[degrees]C. Although the coevaporation of these systems is excellent, the exciplexes revert to varying extents to excited monomer at temperatures near 100[degrees]C. Thus, there is considerable cross-talk from the liquid into the vapor spectral region. The tertiary amines generally require excitation at wavelengths below 250 nm; the fluorobenzene or 4-fluorotoluene can be excited at 266 nm. Monomer emission peaks at 290 nm; exciplex emission peaks at 350 nm. 19 refs., 5 figs., 2 tabs.

Melton, L.A. (Univ. of Texas at Dallas, Richardson (United States))

1993-06-01

103

Guiding vapor-liquid-solid nanowire growth using SiO2

NASA Astrophysics Data System (ADS)

Vapor-liquid-solid (VLS) grown nanowires (NWs) typically grow in \\langle 111\\rangle directions. In this work, using guiding structures, we effectively grow Si NWs with diameters between 20 and 100 nm in both [001] and \\langle 110\\rangle directions by guiding the Si NW growth using SiO2 surfaces. Using one structure, we demonstrate NW growth in the substrate plane, against the buried oxide layer of a standard, (001) silicon-on-insulator wafer. Using the other structure, we demonstrate NW growth perpendicular to a (001) substrate. We show that the VLS growth mechanism is the same as unconstrained NW growth, with the NWs still growing by the addition of {111} planes. We show that when the guiding surface is removed, the NW grows in its natural growth direction because the growth mechanism has not changed. We speculate that NW growth can be guided with a range of materials, the most suitable being those that are amorphous and those which are nearly immiscible both with the catalyst and with the NW material.

Quitoriano, Nathaniel J.; Wu, Wei; Kamins, Theodore I.

2009-04-01

104

Vapor-liquid-solid growth of Si nanowires: A kinetic analysis

NASA Astrophysics Data System (ADS)

A steady state kinetic model has been developed for the vapor-liquid-solid growth of Si whiskers or nanowires from liquid catalyst droplets. The steady state is defined as one in which the net injection rate of Si into the droplet is equal to the ejection rate due to wire growth. Expressions that represent specific mechanisms of injection and ejection of Si atoms from the liquid catalyst droplet have been used and their relative importance has been discussed. The analysis shows that evaporation and reverse reaction rates need to be invoked, apart from just surface cracking of the precursor, in order to make the growth rate radius dependent. When these pathways can be neglected, the growth rate become radius independent and can be used to determine the activation energies for the rate limiting step of heterogeneous precursor decomposition. The ejection rates depend on the mechanism of wire growth at the liquid-solid interface or the liquid-solid-vapor triple phase boundary. It is shown that when wire growth is by nucleation and motion of ledges, a radius dependence of growth rate does not just come from the Gibbs-Thompson effect on supersaturation in the liquid, but also from the dependence of the actual area or length available for nucleation. Growth rates have been calculated using the framework of equations developed and compared with experimental results. The agreement in trends is found to be excellent. The same framework of equations has also been used to account for the diverse pressure and temperature dependence of growth rates reported in the literature.

Shakthivel, Dhayalan; Raghavan, Srinivasan

2012-07-01

105

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

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

106

Isothermal isobaric molecular dynamics simulation of water

A series of isothermal isobaric molecular dynamics simulation are carried out on a system made up of 210 molecules at normal temperature and pressure (T=298K, P=1bar) and at high pressure (T=298K, P=2.1kbar). The physical model is based upon the tetrahedral cluster architecture composed of one central molecule (20% of the sample) and four outer molecules (80%). This theoretical approach of

M. Amrani; D. Bendeddouch; D. Bormann; A. Krallafa

2008-01-01

107

Pool boilup analysis using the TRANSIT-HYDRO code with improved vapor/liquid drag models. [LMFBR

The TRANSIT-HYDRO computer code is being developed to provide a tool for assessing the consequences of transition phase events in a hypothetical core disruptive accident in an LMFBR. The TRANSIT-HYDRO code incorporates detailed geometric modeling on a subassembly-by-subassembly basis and detailed modeling of reactor material behavior and thermal and hydrodynamic phenomena. The purpose of this summary is to demonstrate the validity of the improved vapor/liquid momentum exchange models in the TRANSIT-HYDRO code for a prototypic experiment and describe some implications for transition phase scenarios.

Wigeland, R.A.; Graff, D.L.

1984-01-01

108

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

109

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

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

110

High-pressure vapor-liquid equilibria for ethylene + 4-methyl-1-pentane and 1-butene + 1-hexene

Isothermal vapor-liquid equilibria (VLE) for the ethylene + 4-methyl-1-pentene and 1-butene + 1-hexene binary systems were measured by the static method at several temperatures for pressures in the range (0.3 to 8.5) MPa. Representations of VLE data by the Soave and Peng-Robinson cubic equations of state are compared in both modes: predictive and binary parameter adjustment. As the two binary systems behave almost ideally, there is no significant difference between their representation qualities through both equations of state.

Laugier, S. [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France)] [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France); Richon, D. [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)] [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)

1996-03-01

111

A model used for Hugoniot prediction of material at high-temperature along isobaric path

NASA Astrophysics Data System (ADS)

A model was derived in this paper to calculate the high-temperature Hugoniot of solid material along isobaric path by using an enthalpy-based equation of state (EOS) model. It provides a way and complements the Mie-Grüneisen EOS for studying high-temperature Hugoniot of materials. The Hugoniot of tungsten at 1223 K in moderate pressure range (0-10 GPa) and the Hugoniot of molybdenum at 1673 K in high pressure range (10˜300 GPa) were calculated using the presented model. The calculated results fit in with the literature data. The model can satisfactorily predict the Hugoniot of solid at high temperature over a wide pressure range. The model was also extended to predict the Hugoniot of porous materials with high initial temperature along isobaric path; and the Hugoniots of multi-component solids and porous materials at high temperature were also calculated combining with the pressure equilibrium method.

Zhou, Qiang; Chen, Pengwan; Ma, Danzhu; Dai, Kaida

2013-07-01

112

The separation of liquid mixtures through distillation is one of the most common operations in chemical industry, and the efficient design of distillation equipment requires a quantitative knowledge of vapor-liquid equilibria (VLE). Vapor-liquid equilibria were measured for binary systems of 1-pentanol + 2-methyl-1-butanol, + 2-methyl-2-butanol, and + 3-methyl-2-butanol at 373.15 K. The results are thermodynamically consistent according to the point-to-point consistency test, and deviation from ideal behavior is small in all cases.

Aucejo, A.; Burguet, M.C.; Monton, J.B.; Munoz, R.; Sanchotello, M.; Vazquez, M.I. (Univ. of Valencia (Spain). Dept. de Ingenieria Quimica)

1994-07-01

113

Indium phosphide nanowires were grown by metalorganic molecular beam epitaxy using the selective-area vapor-liquid-solid method. We show experimentally and theoretically that the size of the annular opening around the nanowire has a major impact on nanowire growth rate. In addition, we observed a considerable reduction of the growth rate in dense two-dimensional arrays, in agreement with a calculation of the shadowing of the scattered precursors. Due to the impact of these effects on growth, they should be considered during selective-area vapor-liquid-solid nanowire epitaxy. PMID:24177750

Kelrich, A; Calahorra, Y; Greenberg, Y; Gavrilov, A; Cohen, S; Ritter, D

2013-11-29

114

NASA Astrophysics Data System (ADS)

Indium phosphide nanowires were grown by metalorganic molecular beam epitaxy using the selective-area vapor-liquid-solid method. We show experimentally and theoretically that the size of the annular opening around the nanowire has a major impact on nanowire growth rate. In addition, we observed a considerable reduction of the growth rate in dense two-dimensional arrays, in agreement with a calculation of the shadowing of the scattered precursors. Due to the impact of these effects on growth, they should be considered during selective-area vapor-liquid-solid nanowire epitaxy.

Kelrich, A.; Calahorra, Y.; Greenberg, Y.; Gavrilov, A.; Cohen, S.; Ritter, D.

2013-11-01

115

VAPOR/LIQUID EQUILIBRIA OF CONSTITUENTS FROM COAL GASIFICATION IN REFRIGERATED METHANOL

The report describes a thermodynamic framework, established for the development of a model of the phase equilibria of mixtures of methanol and the major constituents found in gases produced from coal. Two approaches were used to model the equilibrium behavior: (1) an equation of ...

116

Symmetry Energy II: Isobaric Analog States

Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, from a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from a_a~10 MeV at mass A~10 to a_a~22 MeV at A~240. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme-Hartree-Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (+-2.4 MeV)...

Danielewicz, Pawel

2014-01-01

117

Vapor-liquid equilibria for binary mixtures of polar solvents with either carbon dioxide, ethane, or ethene were determined with a newly designed apparatus. Bubble-point curves were determined for three different temperatures. The densities of the liquid phases were also obtained. From these data the volume expansions of the liquid phases were calculated. The results show large differences in the volume expansions,

A. Kordikowski; A. P. Schenk; R. M. Van Nielen; C. J. Peters

1995-01-01

118

Symmetry energy II: Isobaric analog states

NASA Astrophysics Data System (ADS)

Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, representing a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from aa˜10 MeV at mass A˜10 to aa˜22 MeV at A˜240. Variation with mass can be understood in terms of dependence of nuclear symmetry energy on density and the rise in importance of low densities within nuclear surface in smaller systems. At A?30, the dependence of coefficients on mass can be well described in terms of a macroscopic volume-surface competition formula with aaV?33.2 MeV and aaS?10.7 MeV. Our further investigation shows, though, that the fitted surface symmetry coefficient likely significantly underestimates that for the limit of half-infinite matter. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme-Hartree-Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In our further analysis, we retain only those parametrizations which yield systems that are adequately stable both in the long- and short-wavelength limits. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (±2.4 MeV) constraints on the symmetry-energy values S(?) at 0.04???0.13 fm. Towards normal density the constraints significantly widen, but the normal value of energy aaV and the slope parameter L are found to be strongly correlated. To narrow the constraints, we reach for the measurements of asymmetry skins and arrive at aaV=30.2-33.7 MeV and L=35-70 MeV, with those values being again strongly positively correlated along the diagonal of their combined region. Inclusion of the skin constraints allows to narrow the constraints on S(?), at 0.04???0.13 fm, down to ±1.1 MeV. Several microscopic calculations, including variational, Bruckner-Hartree-Fock and Dirac-Bruckner-Hartree-Fock, are consistent with our constraint region on S(?).

Danielewicz, Pawel; Lee, Jenny

2014-02-01

119

Glutathione has previously been identified as a reaction target for toluene diisocyanate (TDI) in vitro and in vivo, and has been suggested to contribute to toxic and allergic reactions to exposure. In this study, the reactivity of reduced glutathione (GSH) with TDI in vitro was further investigated using a mixed phase (vapor/liquid) exposure system to model the in vivo biophysics of exposure in the lower respiratory tract. HPLC/MS/MS was used to characterize the observed reaction products. Under the conditions tested, the major reaction products between TDI vapor and GSH were S-linked bis(GSH)-TDI and to a lesser extent mono(GSH)-TDI conjugates (with one N=C=O hydrolyzed). The vapor phase generated GSH-TDI conjugates were capable of transcarbamoylating human albumin in a pH-dependent manner, resulting in changes in the self-protein’s conformation/charge, based on electrophoretic mobility under native conditions. Specific sites of human albumin-TDI conjugation, mediated by GSH-TDI, were identified (Lys73, Lys159, Lys190, Lys199, Lys212, Lys351, Lys136/137, Lys413/414, Lys524/525) and overlap with those susceptible to direct conjugation by TDI. Together, the data extend proof-of-principle for GSH to act as a “shuttle” for a reactive form of TDI, which could contribute to clinical responses to exposure. PMID:21806041

Wisnewski, Adam V; Hettick, Justin M.; Siegel, Paul D.

2012-01-01

120

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

121

3D analysis of vapor-liquid two phase flow based on compressible two fluid-one pressure model

General problems were investigated relating to the numerical methodologies in simulating a vapor-liquid two phase flow field based on the two fluid-one pressure model. Major difficulties are caused by the wide time constant range of dominant processes included in the phenomenon. This numerical stiffness problem was solved by applying the implicit method for the interfacial interaction and density wave propagation processes. Fluid state variables were derived by Newton-Raphson iteration method after solving the pressure equation. Several pressure iteration schemes were compared their performance in combination with the outer Newton-Raphson loop. Among them, it was found that the MILUCR scheme is most effective. The isolated cylinder sample calculation indicates that the void localization is mainly caused by the vapor mobility. The k-e model was applied to simulate turbulent effects, which enhanced the above-mentioned trend. The detailed BWR spacer samples indicate that the vapor acceleration and its winding motion is notable in the complex structures.

Hotta, A. [Toden Software, Inc., Minato-ku, Tokyo (Japan)

1995-12-31

122

Single crystalline metal oxide nanowires formed via a vapor-liquid-solid (VLS) route provide a platform not only for studying fundamental nanoscale properties but also for exploring novel device applications. Although the crystal phase variation of metal oxides, which exhibits a variety of physical properties, is an interesting feature compared with conventional semiconductors, it has been difficult to control the crystal phase of metal oxides during the VLS nanowire growth. Here we show that a material flux critically determines the crystal phase of indium-tin oxide nanowires grown via the VLS route, although thermodynamical parameters, such as temperature and pressure, were previously believed to determine the crystal phase. The crystal phases of indium-tin oxide nanowires varied from the rutile structures (SnO2), the metastable fluorite structures (InxSnyO3.5) and the bixbyite structures (Sn-doped In2O3) when only the material flux was varied within an order of magnitude. This trend can be interpreted in terms of the material flux dependence of crystal phases (rutile SnO2 and bixbyite In2O3) on the critical nucleation at the liquid-solid (LS) interface. Thus, precisely controlling the material flux, which has been underestimated for VLS nanowire growths, allows us to design the crystal phase and properties in the VLS nanowire growth of multicomponent metal oxides. PMID:24842296

Meng, Gang; Yanagida, Takeshi; Yoshida, Hideto; Nagashima, Kazuki; Kanai, Masaki; Zhuge, Fuwei; He, Yong; Klamchuen, Annop; Rahong, Sakon; Fang, Xiaodong; Takeda, Seiji; Kawai, Tomoji

2014-06-21

123

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. PMID:23802950

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

2013-06-21

124

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

125

Kelvin probe force microscopy (KPFM) is used to characterize the electrical characteristics of vapor-liquid-solid (VLS) Si nanowires (NWs) that are grown in-place between two predefined electrodes. KPFM measurements are performed under an applied bias. Besides contact potential differences due to differing materials, the two other primary contributions to measured variations on Si NWs between electrodes are: trapped charges at interfaces, and the parallel and serial capacitance, which are accounted for with voltage normalization and oxide normalization. These two normalization processes alongside finite-element-method simulations are necessary to characterize the bias-dependent response of Si NWs. After applying both normalization methods on open-circuit NWs, which results in a baseline of zero, we conclude that we have accounted for all the major contributions to CPDs and we can isolate effects due to applied bias such as impurity states and charged carrier flow, as well as find open connections when NWs are connected in parallel. These characterization and normalization methods can also be used to determine that the specific contact resistance of electrodes to the NWs is on the order of ?? cm². Thus, the VLS growth method between predefined electrodes overcomes the challenge of making low-resistance contacts to nanoscale systems. Thereby, the experiments and analysis presented outline a systematic method for characterizing nanowires in parallel arrays under device operation conditions. PMID:23609527

Quitoriano, Nathaniel J; Sanderson, Robert N; Bae, Sung-Soo; Ragan, Regina

2013-05-24

126

NASA Astrophysics Data System (ADS)

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.

2014-01-01

127

The global phase diagram (i.e., vapor-liquid and fluid-solid equilibrium) of two-center Lennard-Jones (2CLJ) model molecules of bond length L=sigma has been determined by computer simulation. The vapor-liquid equilibrium conditions are obtained using the Gibbs ensemble Monte Carlo method and by performing isobaric-isothermal NPT calculations at zero pressure. In the case of the solid phase, two close-packed solid structures are considered:

C. Vega; C. McBride; E. de Miguel; F. J. Blas; A. Galindo

2003-01-01

128

The global phase diagram ~i.e., vapor-liquid and fluid-solid equilibrium ! of two-center Lennard-Jones ~2CLJ! model molecules of bond length L5s has been determined by computer simulation. The vapor-liquid equilibrium conditions are obtained using the Gibbs ensemble Monte Carlo method and by performing isobaric-isothermal NPT calculations at zero pressure. In the case of the solid phase, two close-packed solid structures are

E. de Miguel; F. J. Blas

129

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 CH2 and CH3 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. PMID:25028039

Ghobadi, Ahmadreza F; Elliott, J Richard

2014-07-14

130

Analysis of the vapor-liquid-solid mechanism for nanowire growth and a model for this mechanism.

The vapor-liquid-solid (VLS) mechanism is most widely employed to grow nanowires (NWs). The mechanism uses foreign element catalytic agent (FECA) to mediate the growth. Because of this, it is believed to be very stable with the FECA-mediated droplets not consumed even when reaction conditions change. Recent experiments however differ, which suggest that even under cleanest growth conditions, VLS mechanism may not produce long, thin, uniform, single-crystal nanowires of high purity. The present investigation has addressed various issues involving fundamentals of VLS growth. While addressing these issues, it has taken into consideration the influence of the electrical, hydrodynamic, thermodynamic, and surface tension effects on NW growth. It has found that parameters such as mesoscopic effects on nanoparticle seeds, charge distribution in FECA-induced droplets, electronegativity of the droplet with respect to those of reactive nanowire vapor species, growth temperature, and chamber pressure play important role in the VLS growth. On the basis of an in-depth analysis of various issues, a simple, novel, malleable (SNM) model has been presented for the VLS mechanism. The model appears to explain the formation and observed characteristics of a wide variety of nanowires, including elemental and compound semiconductor nanowires. Also it provides an understanding of the influence of the dynamic behavior of the droplets on the NW growth. This study finds that increase in diameter with time of the droplet of tapered nanowires results primarily from gradual incorporation of oversupplied nanowire species into the FECA-mediated droplet, which is supported by experiments. It finds also that optimum compositions of the droplet constituents are crucial for VLS nanowire growth. An approximate model presented to exemplify the parametric dependency of VLS growth provides good description of NW growth rate as a function of temperature. PMID:18380484

Mohammad, S Noor

2008-05-01

131

Vaporizing liquid microthruster

MEMS technology is expanding into increasingly diverse applications. As part of a micropropulsion system, microthruster attitude controls have been micromachined in silicon. This paper presents the microthruster design, fabrication, and test results. Fluid injected into a microchamber is vaporized by resistive silicon heaters. The exiting vapor generates the thruster force as it exits a silicon micro-nozzle. The vaporization chamber, inlet

E. V Mukerjee; A. P Wallace; K. Y Yan; D. W Howard; R. L Smith; S. D Collins

2000-01-01

132

NASA Astrophysics Data System (ADS)

We have measured the glassy-state structural relaxation of aqueous suspended polystyrene (PS) nanoparticles and the corresponding silica-capped PS nanoparticles via modulated differential scanning calorimetry. Suspended and capped-PS nanoparticles undergo glass formation and subsequent physical aging under isobaric and isochoric conditions, respectively. To account for glass transition temperature (Tg) changes with confinement, physical aging measurements were performed at a constant value of Tg minus Ta, where Ta is the aging temperature. With deceasing diameter, aqueous suspended PS nanoparticles exhibited enhanced physical aging rates in comparison to bulk PS. At all values of Tg minus Ta investigated, capped-PS nanoparticles aged at reduced rates compared to the corresponding aqueous suspended PS nanoparticles. Due to differences in paths to glass formation, suspended and capped-PS nanoparticles aged to different apparent equilibrium states. We captured the physical aging behavior of all nanoparticles via the Tool, Narayanaswamy, and Moynihan (TNM) model of structural relaxation.

Guo, Yunlong; Zhang, Chuan; Priestley, Rodney

2011-03-01

133

Vapor–liquid equilibria and critical points of the systems: carbon dioxide+1-pentanol at (333.08, 343.69, 374.93, 414.23 and 426.86K) up to 18.6MPa and carbon dioxide+2-pentanol at (332.10, 343.61, 374.15, 397.56, 422.28 and 431.78K) up to 15.7MPa are reported at compositions near the critical point. An apparatus capable of measurement up to 60MPa and 523K based on the static-analytic method has been used

G Silva-Oliver; Luis A Galicia-Luna; S. I Sandler

2002-01-01

134

Isothermal and isobaric desorption of carbon dioxide by purge

Adsorption and desorption constitute the two most basic steps in all pressure swing adsorption (PSA) processes for gas separation. The desorption steps are the primary energy-consuming steps in the PSA process. They also dictate the overall separation efficiency. Isothermal and isobaric desorption of carbon dioxide was experimentally evaluated by purging adsorbent columns saturated with pure carbon dioxide with pure hydrogen,

Shivaji Sircar; Timothy C. Golden

1995-01-01

135

Two isobaric spinal anesthetic solutions (bupivacaine 0.5%/20 mg without epinephrine and tetracaine 0.5%/15 mg with 0.2 mg epinephrine) were compared in a double-blind study of 60 patients. Patients were injected while in the lateral recumbent position and were immediately turned supine and horizontal. Up to 30 min after injection, no differences were found between the groups regarding segmental level of analgesia, changes in heart rate, and onset to or maximum decrease in mean arterial pressure (MAP). No correlation was found between maximum decrease in MAP and level of analgesia. At time of maximum decrease in MAP (tetracaine group - 16.7 +/- 12.8% (mean + SEM), bupivacaine group -19.4 + 14.8%) the level of analgesia was significantly higher in the tetracaine group (T5-6) than in the bupivacaine group (T7-8). Hypotension occurred in five patients in the bupivacaine group and in six in the tetracaine group. Two patients in the tetracaine group (but none in the bupivacaine group) had bradycardia. Hypotension together with bradycardia was observed in one patient in the tetracaine group but in no patient in the bupivacaine group. Two patients in each group developed postlumbar puncture headache. The authors conclude that the choice of local anesthetic agent, by itself, is not the sole cause of hypotension seen with spinal anesthesia. PMID:3578865

Phero, J C; Bridenbaugh, P O; Edström, H H; Hagenouw, R R; Knarr, D; Mukkada, T A; Pai, U

1987-06-01

136

for processing to-be-liquefied natural gas, syn- thesis gas, and hydrogen stream, which require low CO2 leakage for the removal of CO2 from gas streams. It has several advantages over other commercial alkanolamines: (a processing the natural gas and refinery gas streams. The disadvantages of aqueous MEA include the following

Zhang, Luzheng

137

The p-n junction can be regarded as the most important electronic structure that is responsible for the ubiquity of semiconductor microelectronics today. Efforts to continually scale down the size of electronic components is guiding research to explore the use of nanomaterials synthesized from a bottom-up approach - group-IV semiconductor nanowires being one such material. However, Au-catalyzed synthesis of Si/Si1-x-Gex semiconductor nanowire heterojunctions using the commonly-used vapor-liquid-solid (VLS) growth technique results in diffuse heterojunction interfaces [1], leading to doubts of producing compositionally-sharp p-n junctions using this approach. However, we have recently reported the ability to increase Ge-Si nanowire heterojunction abruptness by VLS synthesis from a Au(1-x)Ga(x) catalyst alloy as shown by EDX analysis in an SEM [2]. In this work, we have extended the use of a AuGa catalyst alloy to produce more compositionally abrupt p-n junction interfaces compared to using pure Au as directly measured by atom probe tomography. As shown in Figure 1(a-b), individual Ge-Si heterostructured nanowires were grown vertically atop Ge(111) microposts. Direct growth on the microposts provides a facile approach to nanowire analysis which circumvents the need to use FIB-based sample preparation techniques. Both nanowires grown from pure Au and a AuGa catalyst alloy were analyzed. The corresponding 3D APT reconstruction of an individual heterostructured nanowire is shown in Figure 1(c) with the corresponding materials labeled. A 1-dimensional composition profile along the analysis direction in Figure 1(d) confirms an increase in heterojunction abruptness for nanowires grown from AuGa (~10nm) compared to nanowires grown from pure Au (~65nm). Analysis of the P distribution within the Si region (Figure 1(e)) indicates that P reaches a constant distribution over approximately 10nm when incorporated through the AuGa catalyst, whereas it continually increases over 100’s of nanometers when incorporated through pure Au. The apparent lower overall P concentration within the nanowire grown from the AuGa alloy suggests that the solubility of P in the alloy is lower compared to pure Au. The ability to controllably increase nanowire p-n junction abruptness is important for nanowire applications as solar cells and tunneling field effect transistors where an increase in device performance is expected from shaper p-n junction interfaces. [1] T.E. Clark et al., Nano Lett. 8 (2008) 1246. [2] D.E. Perea et al., Nano Lett. 11 (2011) 3117. [3] The research was supported through the user program at both the Center for Integrated Nanotechnologies at Los Alamos National Laboratory and the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory.

Perea, Daniel E.; Schreiber, Daniel K.; Devaraj, Arun; Thevuthasan, Suntharampillai; Yoo, Jinkyoung; Dayeh, Shadi A.; Picraux, Samuel T.

2012-07-30

138

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

139

NASA Technical Reports Server (NTRS)

The microwave brightness temperature measurements for Nimbus-5 electrically scanned microwave radiometer and Nimbus E microwave spectrometer 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 GHz, 22.235 GHz 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. The estimated errors for retrieval are approximately 0.15 g/sq cm for water vapor content, 6.5 mg/sq cm for liquid water content and 6.6 m/sec for surface wind speed.

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

1977-01-01

140

NASA Astrophysics Data System (ADS)

A Helmholtz free energy density functional is developed to describe the vapor-liquid interface of associating chain molecules. The functional is based on the statistical associating fluid theory with attractive potentials of variable range (SAFT-VR) for the homogenous fluid [A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, J. Chem. Phys. 106, 4168 (1997)]. A standard perturbative density functional theory (DFT) is constructed by partitioning the free energy density into a reference term (which incorporates all of the short-range interactions, and is treated locally) and an attractive perturbation (which incorporates the long-range dispersion interactions). In our previous work [F. J. Blas, E. Mart?´n del R?´o, E. de Miguel, and G. Jackson, Mol. Phys. 99, 1851 (2001); G. J. Gloor, F. J. Blas, E. Mart?´n del R?´o, E. de Miguel, and G. Jackson, Fluid Phase Equil. 194, 521 (2002)] we used a mean-field version of the theory (SAFT-HS) in which the pair correlations were neglected in the attractive term. This provides only a qualitative description of the vapor-liquid interface, due to the inadequate mean-field treatment of the vapor-liquid equilibria. Two different approaches are used to include the correlations in the attractive term: in the first, the free energy of the homogeneous fluid is partitioned such that the effect of correlations are incorporated in the local reference term; in the second, a density averaged correlation function is incorporated into the perturbative term in a similar way to that proposed by Toxvaerd [S. Toxvaerd, J. Chem. Phys. 64, 2863 (1976)]. The latter is found to provide the most accurate description of the vapor-liquid surface tension on comparison with new simulation data for a square-well fluid of variable range. The SAFT-VR DFT is used to examine the effect of molecular chain length and association on the surface tension. Different association schemes (dimerization, straight and branched chain formation, and network structures) are examined separately. The surface tension of the associating fluid is found to be bounded between the nonassociating and fully associated limits (both of which correspond to equivalent nonassociating systems). The temperature dependence of the surface tension is found to depend strongly on the balance between the strength and range of the association, and on the particular association scheme. In the case of a system with a strong but very localized association interaction, the surface tension exhibits the characteristic "s shaped" behavior with temperature observed in fluids such as water and alkanols. The various types of curves observed in real substances can be reproduced by the theory. It is very gratifying that a DFT based on SAFT-VR free energy can provide an accurate quantitative description of the surface tension of both the model and experimental systems.

Gloor, Guy J.; Jackson, George; Blas, Felipe J.; del Río, Elvira Martín; de Miguel, Enrique

2004-12-01

141

Isobaric Labeling and Data Normalization without Requiring Protein Quantitation

Isobaric multiplexed quantitative proteomics can complement high-resolution sample isolation techniques. Here, we report a simple workflow exponentially modified protein abundance index (emPAI)-MW deconvolution (EMMOL) for normalizing isobaric reporter ratios within and between experiments, where small or unknown amounts of protein are used. EMMOL deconvolutes the isobaric tags for relative and absolute quantification (iTRAQ) data to yield the quantity of each protein of each sample in the pool, a new approach that enables the comparison of many samples without including a channel of reference standard. Moreover, EMMOL allows using a sufficient quantity of control sample to facilitate the peptide fractionation (isoelectric-focusing was used in this report), and mass spectrometry MS/MS sequencing yet relies on the broad dynamic range of iTRAQ quantitation to compare relative protein abundance. We demonstrated EMMOL by comparing four pooled samples with 20-fold range differences in protein abundance and performed data normalization without using prior knowledge of the amounts of proteins in each sample, simulating an iTRAQ experiment without protein quantitation prior to labeling. We used emPAI,1 the target protein MW, and the iTRAQ reporter ratios to calculate the amount of each protein in each of the four channels. Importantly, the EMMOL-delineated proteomes from separate iTRAQ experiments can be assorted for comparison without using a reference sample. We observed no compression of expression in iTRAQ ratios over a 20-fold range for all protein abundances. To complement this ability to analyze minute samples, we report an optimized iTRAQ labeling protocol for using 5 ?g protein as the starting material. PMID:22468137

Kim, Phillip D.; Patel, Bhavinkumar B.; Yeung, Anthony T.

2012-01-01

142

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

143

Complex energy approaches for calculating isobaric analogue states

Two methods the complex energy shell model (CXSM) and the complex scaling (CS) approach were used for calculating isobaric analog resonances (IAR) in the Lane model. The IAR parameters calculated by the CXSM and the CS methods were checked against the parameters extracted from the direct numerical solution of the coupled channel Lane equations (CC). The agreement with the CC results was generally better than 1 keV for both methods and for each partial waves concerned. Similarities and differences of the CXSM and the CS methods are discussed. CXSM offers a direct way to study the configurations of the IAR wave function in contrast to the CS method.

R. Id Betan; A. T. Kruppa; T. Vertse

2008-06-30

144

Canonical ensemble molecular dynamics (MD) simulations are reported which compute both the vapor-liquid equilibrium properties (vapor pressure and liquid and vapor densities) and the interfacial properties (density profiles, interfacial tensions, entropy and enthalpy of surface formation) of four long-chained n-alkanes: n-decane (n-C(10)), n-eicosane (n-C(20)), n-hexacontane (n-C(60)), and n-decacontane (n-C(100)). Three of the most commonly employed united-atom (UA) force fields for alkanes (SKS: Smit, B.; Karaborni, S.; Siepmann, J. I. J. Chem. Phys. 1995,102, 2126-2140; J. Chem. Phys. 1998,109, 352; NERD: Nath, S. K.; Escobedo, F. A.; de Pablo, J. J. J. Chem. Phys. 1998, 108, 9905-9911; and TraPPE: Martin M. G.; Siepmann, J. I. J. Phys. Chem. B1998, 102, 2569-2577.) are critically appraised. The computed results have been compared to the available experimental data and those fitted using the square gradient theory (SGT). In the latter approach, the Lennard-Jones chain equation of state (EoS), appropriately parametrized for long hydrocarbons, is used to model the homogeneous bulk phase Helmholtz energy. The MD results for phase equilibria of n-decane and n-eicosane exhibit sensible agreement both to the experimental data and EoS correlation for all potentials tested, with the TraPPE potential showing the lowest deviations. However, as the molecular chain increases to n-hexacontane and n-decacontane, the reliability of the UA potentials decreases, showing notorious subpredictions of both saturated liquid density and vapor pressure. Based on the recommended data and EoS results for the heaviest hydrocarbons, it is possible to attest, that in this extreme, the TraPPE potential shows the lowest liquid density deviations. The low absolute values of the vapor pressure preclude the discrimination among the three UA potentials studied. On the other hand, interfacial properties are very sensitive to the type of UA potential thus allowing a differentiation of the potentials. Comparing the interfacial tension MD results to the available experimental data and SGT results, the TraPPE model exhibits the lowest deviations for all hydrocarbons. PMID:21932822

Müller, Erich A; Mejía, Andrés

2011-11-10

145

Hard breakup of the deuteron into two ? isobars

NASA Astrophysics Data System (ADS)

We study high-energy photodisintegration of the deuteron into two ? 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??? 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??? scattering. We predict that the cross section of the deuteron breakup to ?++?- is 4-5 times larger than that of the breakup to the ?+?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 ? isobars are the result of the disintegration of the preexisting ?? components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both ?++?- and ?+?0 channels to be similar.

Granados, Carlos G.; Sargsian, Misak M.

2011-05-01

146

Hard breakup of the deuteron into two ? -isobars

NASA Astrophysics Data System (ADS)

Photodisintegration of the deuteron into two ?-isobars at large center of mass angles is studied within the QCD hard rescattering model (HRM). According to the HRM, the reaction proceeds in three main steps: the photon knocks the 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 emerging at large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn->?? scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. We predict that the cross section of the deuteron breakup to &++circ;&-circ; is 4-5 times larger than that of the breakup to the &+circ;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 ?-isobars are the result of the disintegration of initial ?? components of the deuteron wave function. In this case, the angular distributions and cross sections of the breakup in both &++circ;&-circ; and &+circ;0? channels are expected to be similar.

Granados, Carlos; Sargsian, Misak

2011-04-01

147

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

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

148

The solubilities of five saccharides in water have been measured at various temperatures. This includes the monosaccharides xylose and galactose, and the disaccharides maltose monohydrate, cellobiose and trehalose dihydrate. A method that uses interaction energies and interaction parameters calculated with molecular mechanics methods has shown to give good predictions of the phase behavior of a variety of mixtures, including glycols and small saccharides in aqueous solution. The method is completely predictive, as the strength of the molecular interactions is determined with a theoretical method in the absence of any phase equilibrium data. For calculating solubilities, experimental values for the melting points and the heats of fusion of the compounds under study are, however, necessary. The solubilities of the five saccharides listed above, raffinose and meso-erythritol in water were calculated with this method. The calculated solubilities are in reasonably good agreement with experiment, and in the case of meso-erythritol, which is a polyalcohol (polyol), and galactose, the agreement between prediction and experiment is excellent. Also the vapor pressures of water over several polyols and saccharides in aqueous solution have been predicted with this method, giving results in excellent agreement with the experimental values. PMID:12350326

Jónsdóttir, Svava Osk; Cooke, Stephen A; Macedo, Eugénia A

2002-09-27

149

The isobaric multiplet mass equation for A?71 revisited

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

150

We report the growth of GaN nanowires at a low temperature of 750 °C and at atmospheric pressure in a conventional chemical vapor deposition (CVD) setup via the vapor-liquid-solid mechanism with remarkable control of directionality and growth behavior by using an in situ magnetic field. Under typical growth conditions, without any magnetic field, the nanowires are severely twisted and kinked, and exhibit a high density of planar stacking defects. With increasing in situ magnetic field strength, the microstructural defects are found to decrease progressively, and quasi-aligned nanowires are produced. At an applied magnetic field strength of 0.80 T, near-vertical aligned straight and several micrometers long nanowires of average diameter of ~40 nm with defect-free microstructure are routinely produced. Photoluminescence measurements show that the relative intensity of the defect-related peaks in the visible region with respect to the near-band-edge emission continuously decrease with increase in the applied in situ magnetic field strength, ascribable to the magnetic field-assisted significant structural improvement of the wires. It is found out that the degree of agglomerative Ni droplet on Si is critically influenced by the surface tension driven by the magnetic force, which in turn determines the eventual properties of the nanowires. PMID:24117213

Kim, Jun Sik; Mohanty, Bhaskar Chandra; Han, Chan Su; Han, Seung Jun; Ha, Gwang Heon; Lin, Liwei; Cho, Yong Soo

2014-01-01

151

NASA Astrophysics Data System (ADS)

We report the growth mechanism of metal oxide nanostructures synthesized by electron beam evaporation. The condensed electron beam can easily decompose metal oxide sources that have a high melting point, thereby creating a self-catalytic metal nanodot for the vapor-liquid-solid process. The metal oxide nanostructures can be grown at a temperature just above the melting point of the self-catalyst by dissolving oxygen. The morphology of nanostructures, such as density and uniformity, strongly depends on the surface energy and surface migration energy of the substrate. The density of the self-catalytic metal nanodots increased with decreasing surface energies of the substrate due to the perfect wetting phenomenon of the catalytic materials on the high surface energy substrate. However, the surfaces with extremely low surface energy had difficulty producing the high density of self-catalyst nanodot, due to positive line tension, which increases the contact angle to >180°. Moreover, substrates with low surface migration energy, such as single layer graphene, make nanodots agglomerate to produce a less-uniform distribution compared to those produced on multi-layer graphene with high surface migration energy.

Yu, Hak Ki; Lee, Jong-Lam

2014-10-01

152

Carbon microcoils are generally prepared by catalytic chemical vapor deposition of acetylene, using Ni as the catalyst and thiophene as the promoter. In this work, Ni3S2 was chosen as the catalyst on purpose to avoid the introducing of noxious and unpleasant thiophene during the reaction process. The products obtained in the temperature range of 1013-1033 K were pure, regular and had perfect morphology. Using transmission electron microscope, Raman spectrometer and X-ray diffractometer, the microstructure of the as-prepared carbon microcoils were characterized, furthmore, energy dispersive spectrum and selected area electron diffraction analysis reveal that the growth of carbon microcoils is always accomplished with the transformation of the catalyst from Ni3S2 to Ni3C. We first observed that the fiber constructing the carbon microcoil is composed of three sub-fibers, which strongly supports the proposition of vapor-liquid-solid-solid growth mechanism. In this mechanism, every catalyst particle is in the state of the coexistence of solid and liquid. Carbon atoms firstly permeate into the liquid portion from gas, then disperse into the solid portion, and finally deposit from the catalyst grain to form the carbon microcoil. PMID:17256329

Li, Wenjun; Guo, Yanchuan; Chen, Lijuan

2006-12-01

153

We report the growth mechanism of metal oxide nanostructures synthesized by electron beam evaporation. The condensed electron beam can easily decompose metal oxide sources that have a high melting point, thereby creating a self-catalytic metal nanodot for the vapor-liquid-solid process. The metal oxide nanostructures can be grown at a temperature just above the melting point of the self-catalyst by dissolving oxygen. The morphology of nanostructures, such as density and uniformity, strongly depends on the surface energy and surface migration energy of the substrate. The density of the self-catalytic metal nanodots increased with decreasing surface energies of the substrate due to the perfect wetting phenomenon of the catalytic materials on the high surface energy substrate. However, the surfaces with extremely low surface energy had difficulty producing the high density of self-catalyst nanodot, due to positive line tension, which increases the contact angle to >180°. Moreover, substrates with low surface migration energy, such as single layer graphene, make nanodots agglomerate to produce a less-uniform distribution compared to those produced on multi-layer graphene with high surface migration energy. PMID:25300518

Yu, Hak Ki; Lee, Jong-Lam

2014-01-01

154

Study of isobaric grape seed proanthocyanidins by MALDI-TOF MS.

Positive matrix-assisted laser desorption ionization (MALDI) spectra of grape seed raw extracts show the signals of putative proanthocyanidin (PA) oligomers, including those of several sodium and potassium adducts with the same nominal molecular weight. As a result, the MALDI time-of-flight profiles are characterized by several isobaric signals from different PAs. The presence of isobaric PA adducts was studied by sodium and potassium exchange experiments on the seed extracts of six grape varieties. This approach was effective in differentiating PAs with isobaric signals, and 15 different PAs were identified in the MALDI spectra of all samples. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25230179

De Marchi, Fabiola; Seraglia, Roberta; Molin, Laura; Traldi, Pietro; Dalla Vedova, Antonio; Gardiman, Massimo; De Rosso, Mirko; Flamini, Riccardo

2014-09-01

155

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

156

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

157

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

158

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

159

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

160

Methane's solubility in other hydrocarbons is a very important property in optimizing tertiary oil recovery processes that use miscible gas drive. A static analytical method was employed to measure high-pressure vapor-liquid equilibria up to the critical point on methane-aromatic hydrocarbon systems. The results include new data for the methane-m-xylene and methane-mesitylene systems. A comparison with data from several other sources furnishes a basis for choosing the most reliable experimental method and data origin.

Legret, D.; Richon, D.; Renon, H.

1982-04-01

161

NASA Astrophysics Data System (ADS)

Isobaric contaminants are often problematical in accelerated negative ion beams for research at certain radioactive ion beam (RIB) and accelerator mass spectrometry (AMS) facilities since their presence in low-intensity rare isotopic beams seriously compromise experimental results. This article describes a non-resonant, laser-based photo-detachment apparatus for use at these facilities, which, according to calculations efficiently removes isobaric contaminants from these beams. The advantage of the system for isobaric contaminant removal over other systems proposed to date lies in its ability to efficiently capture easily transportable energetic negative ion beams with low, intermediate or high energy spreads by a superconducting solenoid magnetic field. The ability to change the diameter of captured beams by adjusting the magnetic field strength permits optimum control of the radial overlap of the laser/negative ion beam profiles over an extended interaction region under high vacuum conditions without retarding optical affect, collision-cooling or capture losses.

Alton, G. D.; Zhang, Y.

2008-09-01

162

IQuant: An automated pipeline for quantitative proteomics based upon isobaric tags.

Quantitative proteomics technology based on isobaric tags is playing an important role in proteomic investigation. In this paper, we present an automated software, named IQuant, which integrates a postprocessing tool of protein identification and advanced statistical algorithms to process the MS/MS signals generated from the peptides labeled by isobaric tags and aims at proteomics quantification. The software of IQuant, which is freely downloaded at http://sourceforge.net/projects/iquant/, can run from a graphical user interface and a command-line interface, and can work on both Windows and Linux systems. PMID:25069810

Wen, Bo; Zhou, Ruo; Feng, Qiang; Wang, Quanhui; Wang, Jun; Liu, Siqi

2014-10-01

163

NASA Astrophysics Data System (ADS)

Due to quantum size effects (QSEs), the isobaric thermal expansion coefficient and isothermal compressibility well defined for macroscopic systems are invalid for finite-size systems. The two parameters are redefined and calculated for a finite-size ideal Fermi gas confined in a rectangular container. It is found that the isobaric thermal expansion coefficient and isothermal compressibility are generally anisotropic, i.e., they are generally different in different directions. Moreover, it is found the thermal expansion coefficient may be negative in some directions under the condition that the pressures in all directions are kept constant.

Su, Guozhen; Chen, Liwei; Chen, Jincan

2014-06-01

164

Charge-changing cross sections near the {Delta}-isobar resonance

Investigations of the charge-changing fragmentation cross sections for nuclei ranging from {sup 12}C to {sup 58}Ni and energy/nucleon from 300 to 2100 MeV on hydrogen emphasize the influence of nucleon isobar excitations. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Doll, P. [Kernforschungszentrum Karlsruhe, Institut fuer Kernphysik 1, P.O. Box 3640, D-76021 Karlsruhe (Germany); Crawford, H.J. [Space Science Laboratory, University of California, Berkeley, California 94720 (United States)

1995-02-05

165

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

166

Binding Energies of the Particle and theA=3 Isobars from a Theoretical Geometric Model.

energy from the modified Mathieu equation for the radial eigenvalue equation also establishes pro- ton for a proton-electron-proton magnetic bond lead to the Mathieu equation [6,7,8]. It is known isobar nuclides. The approximation for the resultant wave equation which lead to the deuteron binding

GonzÃ¡lez MartÃn, Gustavo R.

167

A new apparatus to measure partition coefficients Kinfinity \\/SUB s\\/ at infinite dilution up to 200 10âµ Pa and 423 K is described. Measurements of the systems: (1) methane-ethane-n-decane and methane-propane-n-decane at 294.25 K; and (2) methane-n-butane-n-decane at 344.25 K illustrate the reproducibility and good agreement with literature data. In addition, new data were obtained for the system methane-npentane-n-decane at

D. Legret; J. Desteve; H. Renon; D. Richon

1983-01-01

168

Interpretation of mean vertical velocity measured by isobaric floats during deep convective events

NASA Astrophysics Data System (ADS)

To understand isobaric float measurements of vertical velocity during oceanic deep convective events, we compare experimental results obtained in the Greenland Sea with time series from an ensemble of modeled isobaric drifters embedded in a Large Eddy Simulation (LES), carried out with realistic initial conditions and time-dependent surface forcing. Both real and simulated drifter time series show that in general the drifters observe a mean vertical velocity that may be upwards or downwards, depending on the vertical position of the float within the mixed layer. Over the course of the mixing phase, the net apparent vertical displacement of water may be on the order of several kilometers. The significant mean vertical velocity measured with these drifters is due to their tendency to preferentially sample zones of horizontal convergence. In the model, these zones are found to be associated with sinking plumes in the upper region of the mixed layer, or with rising warm return flow in the lower region.

Lherminier, Pascale; Harcourt, Ramsey R.; Garwood, Roland W.; Gascard, Jean-Claude

2001-05-01

169

NASA Astrophysics Data System (ADS)

An ionization depressor, 1% H3PO4 was used to eliminate the isobaric interference that has been of a great concern during the procedure of boron isotopic ratio analysis by thermal ionization mass spectrometer (TIMS). Our experiments have shown that it appears to be an effective method to completely restrain the formation of isobaric ions of CNO- and Cs2CNO+ in the ionization source of mass spectrometer. We have also discussed the optimum proportion of depressor to nitrite for precise analysis of boron isotopes in natural samples based on a conditional experiment. In this case, the pretreatment of boron extraction from natural samples is greatly simplified since it is not necessary to remove nitrite and organic matter completely. In virtue of the method, we determined boron isotope in different types of natural samples, and our results are consistent with previous reports.

Wei, Haizhen; Xiao, Yingkai; Sun, Aide; Zhang, Chonggeng; Li, Shizhen

2004-07-01

170

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

171

Delta-Isobar Production in the Hard Photodisintegration of a Deuteron

NASA Astrophysics Data System (ADS)

Hard photodisintegration of the deuteron in delta-isobar production channels is proposed as a useful process in identifying the quark structure of hadrons and of hadronic interactions at large momentum and energy transfer. The reactions are modeled using the hard re scattering model, HRM, following previous works on hard breakup of a nucleon nucleon (NN) system in light nuclei. Here,quantitative predictions through the HRM require the numerical input of fits of experimental NN hard elastic scattering cross sections. Because of the lack of data in hard NN scattering into ?-isobar channels, the cross section of the corresponding photodisintegration processes cannot be predicted in the same way. Instead, the corresponding NN scattering process is modeled through the quark interchange mechanism, QIM, leaving an unknown normalization parameter. The observables of interest are ratios of differential cross sections of ?-isobar production channels to NN breakup in deuteron photodisintegration. Both entries in these ratios are derived through the HRM and QIM so that normalization parameters cancel out and numerical predictions can be obtained. )

Granados, Carlos; Sargsian, Misak

2010-02-01

172

Introduction. The aim of the study was to compare the sensory, motor, and neuroophthalmological effects of isobaric levobupivacaine and bupivacaine when intrathecally administered. Materials and Methods. A prospective, double-blind, randomized study with 60 ASA grade I-II patients aged 18–65 years awaiting knee arthroscopy under spinal anesthesia. Patients received 12.5?mg of isobaric bupivacaine or levobupivacaine. Several features were recorded. Results. No significant intergroup differences were observed for ASA classification, time to micturate, demographic data, surgery duration, and patient/surgeon satisfaction. Similar hemodynamic parameters and sensory/motor blockade duration were found for both groups. There were no neuroophthalmological effects in either group. Sensory (P = 0.018) and motor blockade onset (P = 0.003) was faster in the bupivacaine group. T6 (T2–T12) and T3 (T2–T12) were the highest sensory block levels for the levobupivacaine and bupivacaine groups, respectively (P = 0.008). It took less time to regain maximum motor blockade in the bupivacaine group (P = 0.014), and the levobupivacaine group required use of analgesia earlier (P = 0.025). Conclusions. Isobaric bupivacaine and levobupivacaine are analogous and well-tolerated anesthetics for knee arthroscopy. However, for bupivacaine, sensory and motor blockade onset was faster, and greater sensory blockade with a longer postoperative painless period was achieved. PMID:24701571

del-Rio-Vellosillo, Monica; Garcia-Medina, Jose Javier; Abengochea-Cotaina, Antonio; Barbera-Alacreu, Manuel

2014-01-01

173

Overtaking while approaching equilibrium

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

174

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

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

2008-06-25

175

Isobaric analog states as a tool for spectroscopy of exotic nuclei

NASA Astrophysics Data System (ADS)

Spectroscopy of neutron rich exotic isotopes via their isobaric analog states (IAS) in less exotic nuclei is discussed. Several different experimental techniques, which can be applied to search for IAS of exotic isotopes, are described. Successful application of these techniques to the studies of heavy helium isotopes 7He and 9He led to the observation of unknown IAS in 7Li and 9Li. Spectroscopic information for these states were obtained, and implication of these findings to the structure of 7,9He is considered.

Rogachev, G. V.; Aprahamian, A. A.; Becchetti, F. D.; Boutachkov, P.; Chen, Y.; Chubarian, G.; DeYoung, P. A.; Fomichev, A.; Goldberg, V. Z.; Golovkov, M. S.; Kolata, J. J.; Oganessian, Yu. Ts.; Peaslee, G. F.; Quinn, M.; Rodin, A.; Skorodumov, B. B.; Slepnev, R. S.; Ter-Akopian, G.; Trzaska, W. H.; Wohr, A.; Wolski, R.

2005-12-01

176

upon Q-switch and flash lamps of the laser, respectively. Preliminary experiments con- ducted with the spectroscopy system were conducted in the non-isobaric flow field in the wake of an underexpanded jet nozzle with an approximate exit Mach number of 2...). Pretriggering of the EMCCD detector and synchro- nization with the laser timing, as well as the the laser energy measurement system, were accomplished by using the TTL signal generated by the laser flash lamps and conditioning it through a variable delay pulse...

Bayeh, Alexander C.

2010-01-14

177

The isobaric thermal expansivity and the isothermal compressibility have been measured at 298.15 K for several nonsaturated hydro bons: 1-hexene, 1-hexyne, 1-heptene, 1-heptyne, 1-octene, 1-octyne, o-xylene, m-xylene, p-xylene, and mesitylene (1,3,5-trimethylbenzene). The results, together with previous data from their laboratory, are discussed in terms of the chain length of the hydrocarbons, the degree of unsaturation (-ane, -ene, -yne), the degree of methylation, and the position of the methyl groups on the aromatic ring.

Aicart, E.; Junquera, E. [Univ. Complutense, Madrid (Spain). Dept. de Quimica Fisica I; Letcher, T.M. [Univ. of Natal, Durban (South Africa)

1995-11-01

178

Is there a "$?$-isobar puzzle" in the physics of neutron stars?

We discuss the formation of $\\Delta$ isobars in neutron star matter. We show that their threshold density strictly correlates with the density derivative of the symmetry energy of nuclear matter, the $L$ parameter. By restricting $L$ to the range of values indicated by recent experimental and theoretical analysis, i.e. $40$ MeV $\\lesssim L \\lesssim 62$ MeV, we find that $\\Delta$ isobars appear at a density of the order of 2$\\div$3 times nuclear matter saturation density, i.e. the same range for the appearance of hyperons. The range of values of the couplings of the $\\Delta$s with the mesons is restricted by the analysis of the data obtained from photoabsorption, electron and pion scattering on nuclei. If the potential of the $\\Delta$ in nuclear matter is close to the one indicated by the experimental data then the equation of state becomes soft enough that a "$\\Delta$ puzzle" exists, similar to the "hyperon puzzle" widely discussed in the literature.

Alessandro Drago; Andrea Lavagno; Giuseppe Pagliara; Daniele Pigato

2014-07-10

179

Is there a "$\\Delta$-isobar puzzle" in the physics of neutron stars?

We discuss the formation of $\\Delta$ isobars in neutron star matter. We show that their threshold density strictly correlates with the density derivative of the symmetry energy of nuclear matter, the $L$ parameter. By restricting $L$ to the range of values indicated by recent experimental and theoretical analysis, i.e. $40$ MeV $\\lesssim L \\lesssim 62$ MeV, we find that $\\Delta$ isobars appear at a density of the order of 2$\\div$3 times nuclear matter saturation density, i.e. the same range for the appearance of hyperons. The range of values of the couplings of the $\\Delta$s with the mesons is restricted by the analysis of the data obtained from photoabsorption, electron and pion scattering on nuclei. If the potential of the $\\Delta$ in nuclear matter is close to the one indicated by the experimental data then the equation of state becomes soft enough that a "$\\Delta$ puzzle" exists, similar to the "hyperon puzzle" widely discussed in the literature.

Drago, Alessandro; Pagliara, Giuseppe; Pigato, Daniele

2014-01-01

180

A series of first principles Monte Carlo simulations in the isobaric-isothermal ensemble were carried out for liquid water at ambient conditions (T = 298 K and p = 1 atm). The Becke-Lee-Yang-Parr (BLYP) exchange and correlation energy functionals and norm-conserving Goedecker-Teter-Hutter (GTH) pseudopotentials were employed with the CP2K simulation package to examine systems consisting of 64 water molecules. The fluctuations in the system volume encountered in simulations in the isobaric-isothermal ensemble requires a reconsideration of the suitability of the typical charge density cutoff and the regular grid generation method previously used for the computation of the electrostatic energy in first principles simulations in the microcanonical or canonical ensembles. In particular, it is noted that a much higher cutoff is needed and that the most computationally efficient method of creating grids can result in poor simulations. Analysis of the simulation trajectories using a very large charge density cutoff at 1200 Ry and four different grid generation methods point to a substantially underestimated liquid density of about 0.85 g/cm{sup 3} resulting in a somewhat understructured liquid (with a value of about 2.7 for the height of the first peak in the oxygen/oxygen radial distribution function) for BLYP-GTH water at ambient conditions.

McGrath, M; Siepmann, J I; Kuo, I W; Mundy, C J; VandeVondele, J; Hutter, J; Mohamed, F; Krack, M

2004-12-02

181

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

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of 20,21Mg, 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 six orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of 21Mg is in good agreement but that the mass of 20Mg deviates by 3{\\sigma}. These measurements reduce the uncertainties in the masses of 20,21Mg 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 non-conserving USDA/B Hamiltonians or isospin non-conserving interactions based on chiral two- and three-nucleon forces.

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

2014-09-04

182

Isobaric yield ratios and the symmetry energy in heavy-ion reactions near the Fermi energy

The relative isobaric yields of fragments produced in a series of heavy-ion-induced multifragmentation reactions have been analyzed in the framework of a modified Fisher model, primarily to determine the ratio of the symmetry energy coefficient to the temperature, a{sub sym}/T, as a function of fragment mass A. The extracted values increase from 5 to approx16 as A increases from 9 to 37. These values have been compared to the results of calculations using the antisymmetrized molecular dynamics (AMD) model together with the statistical decay code gemini. The calculated ratios are in good agreement with those extracted from the experiment. In contrast, the values extracted from the ratios of the primary isobars from the AMD model calculation are approx4 to 5 and show little variation with A. This observation indicates that the value of the symmetry energy coefficient derived from final fragment observables may be significantly different than the actual value at the time of fragment formation. The experimentally observed pairing effect is also studied within the same simulations. The Coulomb coefficient is also discussed.

Huang, M. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Z. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Kowalski, S. [Institute of Physics, Silesia University, Katowice (Poland); Ma, Y. G. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Wada, R.; Hagel, K.; Barbui, M.; Bottosso, C.; Materna, T.; Natowitz, J. B.; Qin, L.; Rodrigues, M. R. D.; Sahu, P. K. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States); Keutgen, T. [FNRS and IPN, Universite Catholique de Louvain, B-1348 Louvain-Neuve (Belgium); Bonasera, A. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States); Laboratori Nazionali del Sud, INFN, via Santa Sofia, 62, 95123 Catania (Italy); Wang, J. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

2010-04-15

183

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

184

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

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

185

Polymorphs of 1,1-diamino-2,2-dinitroethene (FOX-7): Isothermal compression versus isobaric heating

NASA Astrophysics Data System (ADS)

Raman spectroscopy was used to examine polymorphic changes in 1,1-diamino-2,2-dinitroethene (FOX-7) single crystals under: isothermal compression to 15 GPa and isobaric heating to 500 K. Changes in the Raman spectra were observed at ˜2.0 and ˜4.5 GPa, and at ˜390 K and ˜450 K. These onsets are in general accord with previously reported onsets from IR measurements under isothermal compression and from X-ray diffraction measurements under isobaric heating, respectively. In contrast to recent suggestions, we show that the high pressure polymorphs have different vibrational structures, and likely different crystal structures, than the high temperature polymorphs.

Dreger, Z. A.; Tao, Y.; Gupta, Y. M.

2013-10-01

186

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

187

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

188

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

189

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

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

190

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

2014-08-24

191

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

192

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

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

193

The laser ion source trap for highest isobaric selectivity in online exotic isotope production.

The improvement in the performance of a conventional laser ion source in the laser ion source and trap (LIST) project is presented, which envisages installation of a repeller electrode and a linear Paul trap/ion guide structure. This approach promises highest isobaric purity and optimum temporal and spatial control of the radioactive ion beam produced at an online isotope separator facility. The functionality of the LIST was explored at the offline test separators of University of Mainz (UMz) and ISOLDE/CERN, using the UMz solid state laser system. Ionization efficiency and selectivity as well as time structure and transversal emittance of the produced ion beam was determined. Next step after complete characterization is the construction and installation of the radiation-hard final trap structure and its first online application. PMID:20192370

Schwellnus, F; Blaum, K; Catherall, R; Crepieux, B; Fedosseev, V; Gottwald, T; Kluge, H-J; Marsh, B; Mattolat, C; Rothe, S; Stora, T; Wendt, K

2010-02-01

194

We report the measurements of the densities of linear alkylbenzene at three temperatures over 4 to 23 Celsius degree with pressures up to 10 MPa. The measurements have been analysed to yield the isobaric thermal expansion coefficients and, so far for the first time, isothermal compressibilities of linear alkylbenzene.

Zhou, Xiang; Liu, Qian; Zhang, Zhenyu; Ding, Yayun; Zhou, Li; Cao, Jun

2014-01-01

195

We report the measurements of the densities of linear alkylbenzene at three temperatures over 4 to 23 Celsius degree with pressures up to 10 MPa. The measurements have been analysed to yield the isobaric thermal expansion coefficients and, so far for the first time, isothermal compressibilities of linear alkylbenzene.

Xiang Zhou; Qingmin Zhang; Qian Liu; Zhenyu Zhang; Yayun Ding; Li Zhou; Jun Cao

2014-08-05

196

Unambiguous determination of isobaric histone modifications by reversed-phase retention time adapted methodology that exploits difference in the relative retention time of acetylated and methylated 2009 Keywords: Retention High-mass accuracy Acetylation Methylation Trimethylation a b s t r a c

Tsai, Ming-Daw

197

Herein we describe the development and application of a set of novel N, N-dimethyl leucine (DiLeu) 4-plex isobaric tandem mass (MS2) tagging reagents with high quantitation efficacy and greatly reduced cost for neuropeptide and protein analysis. DiLeu reagents serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency. DiLeu reagent resembles the general structure of a tandem mass tag in that it contains an amine reactive group (triazine ester) targeting the N-terminus and ?-amino group of the lysine side-chain of a peptide, a balance group, and a reporter group. A mass shift of m/z 145.1 is observed for each incorporated label. Intense a1 reporter ions at m/z 115.1, 116.1, 117.1, and 118.1 are observed for all pooled samples upon MS2. All labeling reagents are readily synthesized from commercially available chemicals with greatly reduced cost. Labels 117 and 118 can be synthesized in one step and labels 115 and 116 can be synthesized in two steps. Both DiLeu and iTRAQ reagents show comparable protein sequence coverage (~43%) and quantitation accuracy (<15%) for tryptically digested protein samples. Furthermore, enhanced fragmentation of DiLeu labeling reagents offers greater confidence in protein identification and neuropeptide sequencing from complex neuroendocrine tissue extracts from a marine model organism, Callinectes sapidus. PMID:20218596

Xiang, Feng; Ye, Hui; Chen, Ruibing; Fu, Qiang; Li, Lingjun

2010-01-01

198

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

199

Astrocytes are essential components of neurogenic niches that affect neurogenesis through membrane association and/or the release of soluble factors. To identify factors released from astrocytes that could regulate neural stem cell differentiation and proliferation, we used mild oxygen-glucose deprivation (OGD) to inhibit the secretory capacity of astrocytes. Using the Transwell co-culture system, we found that OGD-treated astrocytes could not promote neural stem cell differentiation and proliferation. Next, isobaric tagging for the relative and absolute quantitation (iTRAQ) proteomics techniques was performed to identify the proteins in the supernatants of astrocytes (with or without OGD). Through a multi-step analysis and gene ontology classification, 130 extracellular proteins were identified, most of which were involved in neuronal development, the inflammatory response, extracellular matrix composition and supportive functions. Of these proteins, 44 had never been reported to be produced by astrocytes. Using ProteinPilot software analysis, we found that 60 extracellular proteins were significantly altered (27 upregulated and 33 downregulated) in the supernatant of OGD-treated astrocytes. Among these proteins, 7 have been reported to be able to regulate neurogenesis, while others may have the potential to regulate neurogenesis. This study profiles the major proteins released by astrocytes, which play important roles in the modulation of neurogenesis.

Yan, Hu; Zhou, Wenhao [Children's Hospital of Fudan University, 399 Wanyuan Road, Shanghai 201102 (China)] [Children's Hospital of Fudan University, 399 Wanyuan Road, Shanghai 201102 (China); Wei, Liming; Zhong, Fan [Institutes of Biomedical Sciences, Fudan University, 138 Yixueyuan Roda, Shanghai 200032 (China)] [Institutes of Biomedical Sciences, Fudan University, 138 Yixueyuan Roda, Shanghai 200032 (China); Yang, Yi, E-mail: yyang@shmu.edu.cn [Children's Hospital of Fudan University, 399 Wanyuan Road, Shanghai 201102 (China)] [Children's Hospital of Fudan University, 399 Wanyuan Road, Shanghai 201102 (China)

2010-01-08

200

Mass defect-based pseudo-isobaric dimethyl labeling for proteome quantification.

Discovering differentially expressed proteins in various biological samples requires proteome quantification methods with accuracy, precision, and wide dynamic range. This study describes a mass defect-based pseudo-isobaric dimethyl labeling (pIDL) method based on the subtle mass defect differences between (12)C/(13)C and (1)H/(2)H. Lys-C protein digests were labeled with CD2O/(13)CD2O and reduced with NaCNBD3/NaCNBH3 as heavy and light isotopologues, respectively. The fragment ion pairs with mass differences of 5.84 mDa were resolved by high-resolution tandem mass spectrometry (MS/MS) and used for quantification. The pIDL method described here resulted in highly accurate and precise quantification results with approximately 100-fold dynamic range. Furthermore, the pIDL method was extended to 4-plex proteome quantification and applied to the quantitative analysis of proteomes from Hca-P and Hca-F, two mouse hepatocarcinoma ascites syngeneic cell lines with low and high lymph node metastasis rates. PMID:24180428

Zhou, Yuan; Shan, Yichu; Wu, Qi; Zhang, Shen; Zhang, Lihua; Zhang, Yukui

2013-11-19

201

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

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

2014-03-26

202

Isobaric analog resonances of Mg31 and the border of the island of inversion

NASA Astrophysics Data System (ADS)

The evolution of the nuclear shell structure in the region of the neutron-rich shell-breaking nucleus Mg32 has been the subject of considerable interest. We present here the first determination of the overlap of the ground and two first excited states in Mg31 with a neutron coupled to the ground state in Mg30 based on studies of its isobaric analog resonances in Al31. The excitation function for proton resonant elastic scattering on Mg30 was measured close to 0? in the laboratory frame by bombarding a thick polyethylene target with a Mg30 beam at an energy of 2.92 MeV/nucleon at the REX-ISOLDE facility at CERN. Three resonances were successfully resolved, and angular momenta and total and proton resonance widths were determined by using R-matrix analysis. The deduced spectroscopic factor for the ground state in Mg31 is consistent with the shell-model calculation, whereas those for the first and second excited states could not be reproduced. These results show that a drastic change in structure occurs between Mg30 and Mg31 and that the onset of structural change in this region therefore occurs between these two isotopes.

Imai, N.; Mukai, M.; Cederkäll, J.; Aghai, H.; Golubev, P.; Johansson, H. T.; Kahl, D.; Kurcewics, J.; Teranishi, T.; Watanabe, Y. X.

2014-07-01

203

Fast analysis of isobaric grape anthocyanins by Chip-liquid chromatography/mass spectrometry.

In a previous work, direct-infusion electrospray ionization ion trap tandem mass spectrometry (ESI-IT-MS/MS) was applied to the study of anthocyanins in extracts from the skins of Clinton grapes, a non-Vitis vinifera red grape variety qualitatively and quantitatively rich in anthocyanins. A good characterization of anthocyaninins was obtained, but it was impossible to differentiate some compounds with the same nominal mass but with different elemental composition. In this work, the capabilities of quadrupole time-of-flight mass spectrometry (QTOF-MS) coupled with Chip-liquid chromatography (LC-Chip) were applied to the study of Clinton anthocyanins and this method provided the complete sample anthocyanin fingerprint in less than 5 min. Multi-stage mass spectrometry (MS(n); n >2) was not necessary to identify isobaric compounds, nor were deuterium-exchange experiments necessary to distinguish between compounds containing the same aglycone. The fast separation bypasses the problem of petunidin-3-O-(6-O-acetyl)monoglucoside and delphinidin-3,5-O-diglucoside quantification, present in the direct-infusion ESI-ITMS approach, due to overlapping with matrix interferences. PMID:19670341

Flamini, Riccardo; De Rosso, Mirko; Smaniotto, Anna; Panighel, Annarita; Vedova, Antonio Dalla; Seraglia, Roberta; Traldi, Pietro

2009-09-01

204

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

205

Beyond Equilibrium Thermodynamics

NASA Astrophysics Data System (ADS)

Beyond Equilibrium Thermodynamics fills a niche in the market by providing a comprehensive introduction to a new, emerging topic in the field. The importance of non-equilibrium thermodynamics is addressed in order to fully understand how a system works, whether it is in a biological system like the brain or a system that develops plastic. In order to fully grasp the subject, the book clearly explains the physical concepts and mathematics involved, as well as presenting problems and solutions; over 200 exercises and answers are included. Engineers, scientists, and applied mathematicians can all use the book to address their problems in modelling, calculating, and understanding dynamic responses of materials.

Öttinger, Hans Christian

2005-01-01

206

A variety of quantitative proteomics methods have been developed, including label-free, metabolic labeling, and isobaric chemical labeling using iTRAQ or TMT. Here, these methods were compared in terms of the depth of proteome coverage, quantification accuracy, precision, and reproducibility using a high-performance hybrid mass spectrometer, LTQ Orbitrap Velos. Our results show that (1) the spectral counting method provides the deepest proteome coverage for identification, but its quantification performance is worse than labeling-based approaches, especially the quantification reproducibility; (2) metabolic labeling and isobaric chemical labeling are capable of accurate, precise, and reproducible quantification and provide deep proteome coverage for quantification. Isobaric chemical labeling surpasses metabolic labeling in terms of quantification precision and reproducibility; (3) iTRAQ and TMT perform similarly in all aspects compared in the current study using a CID-HCD dual scan configuration. Based on the unique advantages of each method, we provide guidance for selection of the appropriate method for a quantitative proteomics study.

Li, Zhou [ORNL; Adams, Rachel M [ORNL; Chourey, Karuna [ORNL; Hurst, Gregory {Greg} B [ORNL; Hettich, Robert {Bob} L [ORNL; Pan, Chongle [ORNL

2012-01-01

207

A steady-state non-equilibrium molecular dynamics approach for the study of evaporation processes.

Two non-equilibrium methods (called bubble method and splitting method, respectively) have been developed and tested to study the steady state evaporation of a droplet surrounded by its vapor, where the evaporation continuously occurs at the vapor-liquid interface while the droplet size remains constant. In the bubble method, gas molecules are continuously reinserted into a free volume (represented by a bubble) located at the centre of mass of the droplet to keep the droplet size constant. In the splitting method, a molecule close to the centre of mass of the droplet is split into two: In this way, the droplet size is also maintained during the evaporation. By additional local thermostats confined to the area of insertion, the effect of frequent insertions on properties such as density and temperature can be limited to the immediate insertion area. Perturbations are not observed in other parts of the droplet. In the end, both the bubble method and the splitting method achieve steady-state droplet evaporation. Although these methods have been developed using an isolated droplet, we anticipate that they will find a wide range of applications in the study of the evaporation of isolated films and droplets or thin films on heated substrates or under confinement. They can in principle also be used to study the steady-state of other physical processes, such as the diffusion or permeation of gas molecules or ions in a pressure gradient or a concentration gradient. PMID:24116576

Zhang, Jianguo; Müller-Plathe, Florian; Yahia-Ouahmed, Méziane; Leroy, Frédéric

2013-10-01

208

Objectives Using magnetic resonance imaging (MRI), we analyzed the efficacy of the posterior approach lumbar ISOBAR TTL internal fixation system for the dynamic fixation of intervertebral discs, with particular emphasis on its effects on degenerative intervertebral disc disease. Methods We retrospectively compared the MRIs of 54 patients who had previously undergone either rigid internal fixation of the lumbar spine or ISOBAR TTL dynamic fixation for the treatment of lumbar spondylolisthesis. All patients had received preoperative and 6-, 12-, and 24-month postoperative MRI scans of the lumbar spine with acquisition of both routine and diffusion-weighted images (DWI). The upper-segment discs of the fusion were subjected to Pfirrmann grading, and the lumbar intervertebral discs in the DWI sagittal plane were manually drawn; the apparent diffusion coefficient (ADC) value was measured. Results ADC values in the ISOBAR TTL dynamic fixation group measured at the 6-, 12-, and 24-month postoperative MRI studies were increased compared to the preoperative ADC values. The ADC values in the ISOBAR TTL dynamic fixation group at 24 months postoperatively were significantly different from the preoperative values (P?ISOBAR TTL dynamic fixation group (P?ISOBAR TTL internal fixation system can prevent or delay the degeneration of intervertebral discs. PMID:24898377

2014-01-01

209

Applied General Equilibrium Analysis

This book presents a collection of articles on applied general equilibrium analysis by major contributors to this field. This rapidly expanding method of analysis involves the use of computers to study entire economies and the interrelationships among firms, households and governments in these economies. There are also articles on the particular computational techniques involved in the numerical estimation of these

Herbert E. Scarf; John B. Shoven

1986-01-01

210

Deviation from secular equilibrium

Laser exposure of gold nanoparticles in aqueous solutions of Uranium salt leads to accelerated decay of U238 nuclei and significant deviation from secular equilibrium. The samples demonstrate the enhanced gamma emission in the range of 54 keV during laser exposure.

A. V. Simakin; G. A. Shafeev

2010-01-20

211

An Updated Equilibrium Machine

ERIC Educational Resources Information Center

A device that can demonstrate equilibrium, kinetic, and thermodynamic concepts is described. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when the leaf blower is turned on and various air pressures are…

Schultz, Emeric

2008-01-01

212

A mixed strategy is a probability distribution one uses to randomly choose among available actions in order to avoid being predictable. In a mixed strategy equilibrium each player in a game is using a mixed strategy, one that is best for him against the strategies the other players are using. In laboratory experiments the behavior of inexperienced subjects has generally

Mark Walker; John Wooders

213

NASA Astrophysics Data System (ADS)

Dynamical regimes in the California Undercurrent and ocean interior off Central California are controlled by rich mesoscale activity, including eddies, filaments and turbulent jets. A unique dataset of 56 isobaric RAFOS floats was used to analyze relative dispersion in the region. The floats were launched in pairs and triads at 150- -600 m between 1993 and 2003 (http://www.oc.nps.navy.mil/npsRAFOS/). The launch design allowed us to identify about forty float pairs in several classes of initial separation distance. Taking into consideration the anisotropic nature of the California Undercurrent, alongshore and cross-shore separations were calculated for the identified pairs of float trajectories. We applied different techniques, both asymptotic and non-asymptotic, to estimate relative dispersion of the RAFOS floats. In addition to the probability distribution function of the mean square separation and its second- order moments, higher order moments were also considered to understand how much intermittency influence float dispersion. In addition to averaging distances at fixed times, two alternative approaches based on averaging times at fixed distance were tried, the finite size Lyapunov exponent and the parametrical exit time statistics. The latter was estimated both theoretically and using float sampling through the probability weighted moments. Statistical significance of the results as well as possible biases of the estimates due to horizontal and vertical shears were investigated. Different techniques give, in general, different dispersion regimes with power exponents varying between 0.5 and 2. Most differences occurred for the kurtosis and skewness at the initial stage for float pairs with small separation. The focus here was on finite sample size effects and an empirical criterion for evaluating the impact of sample size.

Margolina, T.; Collins, C. A.; Ivanov, L. M.; Hsieh, C.

2006-12-01

214

Spinal Anesthesia with Isobaric Tetracaine in Patients with Previous Lumbar Spinal Surgery

Purpose Previous lumbar spinal surgery (PLSS) is not currently considered as a contraindication for regional anesthesia. However, there are still problems that make spinal anesthesia more difficult with a possibility of worsening the patient's back pain. Spinal anesthesia using combined spinal-epidural anesthesia (CSEA) in elderly patients with or without PLSS was investigated and the anesthetic characteristics, success rates, and possible complications were evaluated. Materials and Methods Fifty patients without PLSS (Control group) and 45 patients with PLSS (PLSS group) who were scheduled for total knee arthroplasty were studied prospectively. A CSEA was performed with patients in the left lateral position, and 10 mg of 0.5% isobaric tetracaine was injected through a 27 G spinal needle. An epidural catheter was then inserted for patient controlled analgesia. Successful spinal anesthesia was defined as adequate sensory block level more than T12. The number of skin punctures and the onset time were recorded, and maximal sensory block level (MSBL), time to 2-segment regression, success rate and complications were observed. Results The success rate of CSEA in Control group and PLSS group was 98.0%, and 93.3%, respectively. The median MSBL in PLSS group was higher than Control group [T4 (T2-L1) vs. T6 (T3-T12)] (p < 0.001). There was a significant difference in the number of patients who required ephedrine for the treatment of hypotension in PLSS group (p = 0.028). Conclusion The success rate of CSEA in patients with PLSS was 93.3%, and patients experienced no significant neurological complications. The MSBL can be higher in PLSS group than Control group. PMID:19430559

Kim, Soo Hwan; Jeon, Dong-Hyuk; Chang, Chul Ho; Lee, Sung-Jin

2009-01-01

215

Plasma Equilibrium in Tokamaks

The task of the theory of tokamak equilibrium is to determine the global magnetic confinement topology and physical characteristics of the underlying basic equilibrium state, which is assumed to be static (both [partial derivative]/[partial derivative]t = 0 and background velocity v{sub 0} = 0). This could be considered to be the most boring case of plasma behavior, viz. total absence of dynamics: a corresponding fluid dynamics problem hardly exists. The reason for our interest in this plasma state is the prospect of obtaining clean, abundant, and cheap energy from controlled thermonuclear fusion reactions. Of course, criticism and doubt immediately enter the mind after a statement like this. Nevertheless, let us study this plasma state, leaving questions like 'is there such a state at all?' and 'is it actually so desirable?' for later (Sec. 5)

Goedbloed, J.P. [FOM- Institute for Plasma Physics 'Rijnhuizen' (Netherlands)

2004-03-15

216

A new fast, spectrally selective imaging method called fluctuating equilibrium magnetic resonance is presented. With all gradients refocused over a repetition interval, certain phase schedules of radiofrequency excitation pulses produce an equilibrium magnetization that fluctuates from excitation to excitation, thus permitting simultaneous acquisition of several images with different contrast features. For example, lipid and water images can be rapidly acquired. The effective echo time can be adjusted using the flip angle, thus providing control over the T(2) contribution to the contrast. Several applications of the technique are presented, including fast musculoskeletal, abdominal, breast, and brain imaging, in addition to MR angiography. A technique for combining lipid and water images generated with this sequence for angiography is described and other potential applications are suggested. Magn Reson Med 42:876-883, 1999. PMID:10542345

Vasanawala, S S; Pauly, J M; Nishimura, D G

1999-11-01

217

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

218

Covariant Equilibrium Statistical Mechanics

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

219

Gravity, Dimension, Equilibrium, & Thermodynamics

Is it actually possible to interpret gravitation as space's property in a pure classical way. Then, we note that extended self-gravitating system equilibrium depends directly on the number of dimension of the space in which it evolves. Given those precisions, we review the principal thermodynamical knowledge in the context of classical gravity with arbitrary dimension of space. Stability analyses for bounded 3D systems, namely the Antonov instability paradigm, are then rapproched to some amazing properties of globular clusters and galaxies.

Jerome Perez

2006-03-30

220

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.

Stapleton, Michael

221

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

222

Hardy-Weinberg Equilibrium Diagnostics

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

223

Non-equilibrium phase transitions

These lecture notes give a basic introduction to the physics of phase transitions under non-equilibrium conditions. The notes start with a general introduction to non-equilibrium statistical mechanics followed by four parts. The first one discusses the universality class of directed percolation, which plays a similar role as the Ising model in equilibrium statistical physics. The second one gives an overview

Haye Hinrichsen

2006-01-01

224

STOCHASTICS AND THERMODYNAMICS EQUILIBRIUM MEASURES

periodic irreducible algebraic varieties contained in the critical set of f, we have that f = log d (pressure gap), then admits a unique equilibrium state Âµ on J. In this paper we prove that the dynamical that has a pressure gap), then admits a unique equilibrium state Âµ on J. This equilibrium state

Urbanski, Mariusz

225

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

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

226

Energy Flows in a Quasi-Isobaric Fusion-Fission Hybrid Reactor

NASA Astrophysics Data System (ADS)

We have examined the dominant mechanisms of energy flow in a fusion-fission hybrid reactor, which is based on a magnetically confined thermonuclear D-T plasma. D -T fusion provides a source of high-energy neutrons which are absorbed in a blanket outside the reactor. The blanket combines the functions of energy multiplication by fission of U^{238}, Pu ^{239} and U^{233 }, and tritium breeding. The fusion "driver" produces 100 MW of neutron power while the blanket provides energy multiplication of about 50. The hybrid can produce about 2000 MW of electrical power. The plasma is contained in the space between two concentric cylinders. There is uniformity in the direction parallel to the curved surfaces of the cylinders, and the confining field is purely toroidal. The plasma has a rectangular cross-section bounded by a planar electrode at one end and a thermionic emitter at the other, and cylindrical walls inside and outside. There is a modest pressure gradient, i.e., nT ~ constant. The temperature is high in the core of the plasma, where fusion occurs, but falls to low values near the walls and end-plates. It is hoped that the quasi-isobaric character will eliminate serious instabilities, and that plasma behaviour will be near-classical. The high-n, low-T periphery should reduce damage to the walls from energetic plasma particles. We have found a class of sustainable MHD equilibria with Q ~ 0.3. The inner and outer radii and height of the reactor are 31, 38 and 7 metres respectively. A high magnetic field is required, in the range 200-400 kG. T rises from 200 eV at the walls to 2.7 keV in the fusion zone, where n_ {rm e}~ 1.5 times 10^{14} cm^{-3}. There is a small vertical flow velocity to provide fueling. We have studied alpha-particle slowing down, electron-cyclotron radiation transport, inelastic reactions, bremsstrahlung, conduction, convection, and heat exchange between electrons and ions in the reactor. RF heating in the lower hybrid range can balance the differential energy equations for electrons and ions throughout the reactor.

Chaturvedi, Shashank

227

NSDL National Science Digital Library

The EJS Coin Flip Equilibrium model simulates a a simple system of N coins arranged in ordered rows. The coins all begin heads up. At each step of the simulation one or more coins are chosen at random and flipped over. Separate windows show the set of coins, a plot of the number of heads/tails after each step, the entropy of the system after each step, and a histogram of the occurrences of a given number of heads. The user can change the number of coins and the number of coins flipped at each step of the simulation. A user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Coin Flip Equilibrium model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_CoinFlip.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-06-18

228

Multiple equilibrium laboratory devices

NASA Astrophysics Data System (ADS)

Devices{* } will be demonstrated and videotapes played of a number of laboratory studies that exhibit multiple equilibrium. All devices have two competing effects driving the flow. In two of them, temperature and salinity oppose each other. In another, air and water compete. In a fourth, wave propagation is opposed by inertia. Connection with hypothesized ocean behavior will be made. {* } Whitehead, J. A. 2000 Stratified Convection with Multiple States. Ocean Modelling, 2, 109-121. Whitehead, J. A. W. Gregory Lawson and John Salzig. 2001 Multistate flow devices for geophysical fluid dynamics and climate. American Journal of Physics, 69 546-553. Whitehead, J. A. and P. G. Baines. 2000. Hydraulic Jump Location as a Multiple Equilibrium feature. 2000 Ocean Sciences Meeting, American Geophysical Union, San Antonio Texas, January 25, 2000. Abstract: EOS 80 #46 (Supplement), OS125. Whitehead, J. A. , M. L. E. Timmermans, W. Gregory Lawson, S. N. Bulgakov, A. M. Zatarian, J. F. A. Medina, and John Salzig, Laboratory studies of thermally and/or Salinity-driven flows with partial mixing: Part 1 Stommel transitions and multiple flow states. In preparation

Whitehead, J. A.

2001-12-01

229

NASA Astrophysics Data System (ADS)

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

Mairhofer, Jonas; Sadus, Richard J.

2013-10-01

230

Equilibrium of nematic vesicles

NASA Astrophysics Data System (ADS)

A variational scheme is proposed which allows the derivation of a concise and elegant formulation of the equilibrium equations for closed fluid membranes, endowed with a nematic microstructure. The nematic order is described by an in-plane nematic director and a degree of orientation, as customary in the theory of uniaxial nematics. The only constitutive ingredient in this scheme is a free-energy density which depends on the vesicle geometry and order parameters. The stress and the couple stress tensors related to this free-energy density are provided. As an application of the proposed scheme, a certain number of special theories are deduced: soap bubbles, lipid vesicles, chiral and achiral nematic membranes, and nematics on curved substrates.

Napoli, Gaetano; Vergori, Luigi

2010-11-01

231

Statistical physics ""Beyond equilibrium

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

232

The Nash equilibrium: A perspective

In 1950, John Nash contributed a remarkable one-page PNAS article that defined and characterized a notion of equilibrium for n- person games. This notion, now called the “Nash equilibrium,” has been widely applied and adapted in economics and other behavioral sciences. Indeed, game theory, with the Nash equilibrium as its centerpiece, is becoming the most prominent unifying theory of social science. In this perspective, we summarize the historical context and subsequent impact of Nash's contribution. PMID:15024100

Holt, Charles A.; Roth, Alvin E.

2004-01-01

233

Partial-Equilibrium Welfare Analysis

The use of partial equilibrium models is common, and, typically, efficiency is characterized by maximizing consumer plus producer surplus (or, sometimes, gross consumer surplus). The analysis appeals-implicitly or explicitly-to the concept of efficiency derived from general equilibrium models. Using the tax-reform methodology, it is shown in a simple general equilibrium model that, if the second-best outcome is not the first-best

Charles Blackorby

1999-01-01

234

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.

Blecha, Betty

235

Phase equilibrium data for development of correlations for coal fluids

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

236

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

237

Kinetic equilibrium and relativistic thermodynamics

Relativistic thermodynamics is treated from the point of view of kinetic theory. It is shown that the generalized J\\"uttner distribution suggested in [1] is compatible with kinetic equilibrium. The requirement of compatibility of kinetic and thermodynamic equilibrium reveals several generalizations of the Gibbs relation where the velocity field is an independent thermodynamic variable.

P. Ván

2011-02-01

238

STP Approach To Equilibrium Program

NSDL National Science Digital Library

The ApproachToEquilibrium program displays the number of particles on one half of a box as a function of time after a small hole is made in the partition dividing the box in half. The purpose of this simulation is to gain insight into the tendency of macroscopic systems to approach a well defined equilibrium macrostate and the improtance of fluctuations in equilibrium. ApproachToEquilibrium is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready- to-run (compiled) Java archive. Double-clicking the stp ApproachToEquilibrium.jar file will run the program if Java is installed on your computer. Additional Open Source Physics programs for Statistical and Thermal Physics can be found by searching ComPADRE for Open Source Physics, STP or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

239

Measurement of Isobaric Heat Capacity of Gaseous Trans-1,3,3,3-tetrafluoropropene (HFO 1234ze (E) )

NASA Astrophysics Data System (ADS)

The specific isobaric heat capacity (cp) was measured for HFO-1234ze(E) (trans-1,3,3,3-tetrafluoropropene) in the gas phase. HFO-1234ze(E) has a lower GWP value of 6 and is one of new environment-friendly refrigerants. Nineteen measurements for HFO-1234ze(E) were obtained at temperatures from 303 K to 363 K and at pressures from 0.35 MPa to 1.3 MPa. The expanded uncertainty (k=2) of the temperature measurements is estimated to be less 22 mK, and that of the pressure measurements is less 4.4 kPa. The expanded uncertainty for cp is estimated to range from 14 to 21 J.kg-1.K-1.

Kagawa, Noboru; Matsuguchi, Atsushi; Watanabe, Koichi

240

AMG 900 is an orally available small molecule that is a highly potent and selective pan-aurora kinase inhibitor currently in development for the treatment of advanced human cancers. A co-eluting, isobaric interference was discovered in preliminary LC-MS/MS analyses of rodent in vivo pharmacokinetic samples during preclinical evaluation of AMG 900. The interference was identified as a major circulating N-oxide metabolite which partially converted to an [M+H-O](+) ion under the conditions of atmospheric pressure chemical ionization. A selective liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of AMG 900 and its N-oxide metabolite in plasma was developed and successfully applied for the bioanalysis of discovery stage preclinical rodent pharmacokinetic studies. PMID:23245248

Be, Xuhai; Moore, Earl S; Zhao, Zhiyang; Wells, Mary C

2013-02-23

241

Transient and secular radioactive equilibrium revisited

The two definitions of radioactive equilibrium are revisited in this paper. The terms activity equilibrium and effective life equilibrium are proposed to take the place of currently used terms transient equilibrium and secular equilibrium. The proposed new definitions have the advantage of providing a clearer physics meaning. Besides the well known instant activity equilibrium, another class of exact effective life-time equilibrium is also discussed in this letter.

Zhang, Qinghui; Amols, Howard

2014-01-01

242

Nash Equilibrium and Dynamics Sergiu Hart

Nash Equilibrium and Dynamics Sergiu Hart June 2008 Conference in Honor of John Nash's 80th equilibrium John Nash, Ph.D. Dissertation, Princeton 1950 SERGIU HART c 2008 Â p. #12;Nash equilibrium EQUILIBRIUM POINT: John Nash, Ph.D. Dissertation, Princeton 1950 SERGIU HART c 2008 Â p. #12;Nash equilibrium

Hart, Sergiu

243

Molecular dynamics simulation of confined fluids in isosurface-isothermal-isobaric ensemble

NASA Astrophysics Data System (ADS)

A method for the simulation of fluids confined between surfaces is developed. The molecular dynamics, with coupling to an external bath, simulation method of Berendsen et al. [J. Chem. Phys. 81, 3684 (1984)] is extended for this purpose. We keep the temperature and the parallel component of pressure fixed and change the box length in the perpendicular direction with respect to the confining surfaces to archive equilibrium. The simulation is easy to perform, especially in the case of solvation force computation. Employing this method, the simulation results on the confined Lennard-Jones and water are presented and are compared to previous grand canonical ensemble Monte Carlo and molecular dynamics simulation results. While consistent with other methods, our results show that spherical Lennard-Jones particles and water form layered structures parallel to the confining surfaces with enhanced layering with increasing pressure. Also we studied the oscillatory behaviors of solvation force and number density of confined particles as well as the stepwise variation of particle numbers as a function of separation between confining surfaces.

Eslami, Hossein; Mozaffari, Farkhondeh; Moghadasi, Jalil; Müller-Plathe, Florian

2008-11-01

244

Molecular dynamics simulation of confined fluids in isosurface-isothermal-isobaric ensemble.

A method for the simulation of fluids confined between surfaces is developed. The molecular dynamics, with coupling to an external bath, simulation method of Berendsen et al. [J. Chem. Phys. 81, 3684 (1984)] is extended for this purpose. We keep the temperature and the parallel component of pressure fixed and change the box length in the perpendicular direction with respect to the confining surfaces to archive equilibrium. The simulation is easy to perform, especially in the case of solvation force computation. Employing this method, the simulation results on the confined Lennard-Jones and water are presented and are compared to previous grand canonical ensemble Monte Carlo and molecular dynamics simulation results. While consistent with other methods, our results show that spherical Lennard-Jones particles and water form layered structures parallel to the confining surfaces with enhanced layering with increasing pressure. Also we studied the oscillatory behaviors of solvation force and number density of confined particles as well as the stepwise variation of particle numbers as a function of separation between confining surfaces. PMID:19026076

Eslami, Hossein; Mozaffari, Farkhondeh; Moghadasi, Jalil; Müller-Plathe, Florian

2008-11-21

245

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

246

Equilibrium Electro-osmotic Instability

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 s...

Rubinstein, Isaak

2014-01-01

247

Essays in dynamic general equilibrium

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

248

Edge equilibrium code for tokamaks

NASA Astrophysics Data System (ADS)

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, Xujing; Zakharov, Leonid E.; Drozdov, Vladimir V.

2014-01-01

249

A search for equilibrium states

NASA Technical Reports Server (NTRS)

An efficient search algorithm is described for the location of equilibrium states in a search set of states which differ from one another only by the choice of pure phases. The algorithm has three important characteristics: (1) it ignores states which have little prospect for being an improved approximation to the true equilibrium state; (2) it avoids states which lead to singular iteration equations; (3) it furnishes a search history which can provide clues to alternative search paths.

Zeleznik, F. J.

1982-01-01

250

Wieser, Hayek and Equilibrium Theory

The paper challenges Joseph Salernoâ€™s recent revisionist account in â€œThe Place of Human Action in the Development of Economic Thoughtâ€ of the relationship between Friedrich von Wieser and F.A. Hayek and of their views on equilibrium theory. The paper argues, contra Salerno, that Wieser was not a proponent of general equilibrium theory, so could not have influenced Hayek in the

Bruce J. Caldwell

2002-01-01

251

Equilibrium Electro-osmotic Instability

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

252

Relevance of equilibrium in multifragmentation

The relevance of equilibrium in a multifragmentation reaction of very central $^{40}Ca+^{40}Ca$ collisions at 35 MeV/nucleon is investigated by using simulations of Antisymmetrized Molecular Dynamics (AMD). Two types of ensembles are compared. One is the reaction ensemble of the states at each reaction time $t$ in collision events simulated by AMD, and the other is the equilibrium ensemble prepared by solving the AMD equation of motion for a many-nucleon system confined in a container for a long time. The comparison of the ensembles is performed for the fragment charge distribution and the excitation energies. Our calculations show that there exists an equilibrium ensemble which well reproduces the reaction ensemble at each reaction time $t$ for the investigated period $80\\leq t\\leq300$ fm/$c$. However, there are some other observables which show discrepancies between the reaction and equilibrium ensembles. These may be interpreted as dynamical effects in the reaction. The usual static equilibrium at each instant is not realized since any equilibrium ensemble with the same volume as that of the reaction system cannot reproduce the fragment observables.

Takuya Furuta; Akira Ono

2008-11-04

253

Relevance of equilibrium in multifragmentation

The relevance of equilibrium in a multifragmentation reaction of very central {sup 40}Ca + {sup 40}Ca collisions at 35 MeV/nucleon is investigated by using simulations of antisymmetrized molecular dynamics (AMD). Two types of ensembles are compared. One is the reaction ensemble of the states at each reaction time t in collision events simulated by AMD, and the other is the equilibrium ensemble prepared by solving the AMD equation of motion for a many-nucleon system confined in a container for a long time. The comparison of the ensembles is performed for the fragment charge distribution and the excitation energies. Our calculations show that there exists an equilibrium ensemble that well reproduces the reaction ensemble at each reaction time t for the investigated period 80{<=}t{<=}300 fm/c. However, there are some other observables that show discrepancies between the reaction and equilibrium ensembles. These may be interpreted as dynamical effects in the reaction. The usual static equilibrium at each instant is not realized since any equilibrium ensemble with the same volume as that of the reaction system cannot reproduce the fragment observables.

Furuta, Takuya [GANIL (DSM-CEA/IN2P3-CNRS), Boite Postal 55027, F-14076 Caen (France); Ono, Akira [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

2009-01-15

254

Quantum Statistical Mechanics. III. Equilibrium Probability

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

255

Shape characteristics of equilibrium and non-equilibrium fractal clusters.

It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other between the viscosity and hydrodynamic radii, as potential measures of shape anisotropy. We also find a strong correlation between anisotropy and effective fractal dimension. These observations should provide new practical methods for quantifying the nature of particle clustering in diverse contexts. PMID:23902013

Mansfield, Marc L; Douglas, Jack F

2013-07-28

256

Shape characteristics of equilibrium and non-equilibrium fractal clusters

NASA Astrophysics Data System (ADS)

It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other between the viscosity and hydrodynamic radii, as potential measures of shape anisotropy. We also find a strong correlation between anisotropy and effective fractal dimension. These observations should provide new practical methods for quantifying the nature of particle clustering in diverse contexts.

Mansfield, Marc L.; Douglas, Jack F.

2013-07-01

257

by the perturbation, are sufficiently small to allow equation linearization as assumed in the theoretical development. The other assumptions of the theory are also reflected in the experimental conditions. A mechanical vibrator was used to help pack the column... on the basis of random molecular mixing, do not predict well the thermodynamic properties of the IPA/APP system when considering orientation effects arising from the IPA molecular polarity. The hydrogen bonds existing between IPA molecules tend to cause...

Joffrion, Lamar Lane

2012-06-07

258

The Coulomb effect hypothesis, formerly used to interpret fluctuations in the curve of maximal total kinetic energy as a function of light fragment mass in reactions 233U(nth,f), 235U(nth,f) and 239Pu(nth,f), is confirmed in high kinetic energy as well as in low excitation energy windows, respectively. Data from reactions 233U(nth,f), 235U(nth,f), 239Pu(nth,f) and 252Cf(sf) show that, between two isobaric fragmentations with similar Q-values, the more asymmetric charge split reaches the higher value of total kinetic energy. Moreover, in isobaric charge splits with different Q-values, similar preference for asymmetrical fragmentations is observed in low excitation energy windows.

Montoya, Modesto

2014-01-01

259

The Coulomb effect hypothesis, formerly used to interpret fluctuations in the curve of maximal total kinetic energy as a function of light fragment mass in reactions 233U(nth,f), 235U(nth,f) and 239Pu(nth,f), is confirmed in high kinetic energy as well as in low excitation energy windows, respectively. Data from reactions 233U(nth,f), 235U(nth,f), 239Pu(nth,f) and 252Cf(sf) show that, between two isobaric fragmentations with similar Q-values, the more asymmetric charge split reaches the higher value of total kinetic energy. Moreover, in isobaric charge splits with different Q-values, similar preference for asymmetrical fragmentations is observed in low excitation energy windows.

Modesto Montoya

2014-03-15

260

S-Nitrosylation is a redox-based protein post-translational modification in response to nitric oxide signaling and is involved in a wide range of biological processes. Detection and quantification of protein S-nitrosylation have been challenging tasks due to instability and low abundance of the modification. Many studies have used mass spectrometry (MS)-based methods with different thiol-reactive reagents to label and identify proteins with S-nitrosylated cysteine (SNO-Cys). In this study, we developed a novel iodoTMT switch assay (ISA) using an isobaric set of thiol-reactive iodoTMTsixplex reagents to specifically detect and quantify protein S-nitrosylation. Irreversible labeling of SNO-Cys with the iodoTMTsixplex reagents enables immune-affinity detection of S-nitrosylated proteins, enrichment of iodoTMT-labeled peptides by anti-TMT resin, and importantly, unambiguous modification site-mapping and multiplex quantification by liquid chromatography-tandem MS. Additionally, we significantly improved anti-TMT peptide enrichment efficiency by competitive elution. Using ISA, we identified a set of SNO-Cys sites responding to lipopolysaccharide (LPS) stimulation in murine BV-2 microglial cells and revealed effects of S-allyl cysteine from garlic on LPS-induced protein S-nitrosylation in antioxidative signaling and mitochondrial metabolic pathways. ISA proved to be an effective proteomic approach for quantitative analysis of S-nitrosylation in complex samples and will facilitate the elucidation of molecular mechanisms of nitrosative stress in disease. PMID:24926564

Qu, Zhe; Meng, Fanjun; Bomgarden, Ryan D; Viner, Rosa I; Li, Jilong; Rogers, John C; Cheng, Jianlin; Greenlief, C Michael; Cui, Jiankun; Lubahn, Dennis B; Sun, Grace Y; Gu, Zezong

2014-07-01

261

The charge-exchange (3He,t) scattering to the isobaric analog state (IAS) of the target can be considered as "elastic" scattering of 3He 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 is related directly to the same density difference, it can be well probed in the analysis of the charge- exchange (3He,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 (3He,t) scattering to the IAS of 90Zr and 208Pb 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.

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

2014-02-16

262

Malignant tumors are relatively resistant to treatment due to their heterogeneous nature, drug resistance, and tendency for metastasis. Recent studies suggest that a subpopulation of cancer cells is responsible for the malignant outcomes. These cells are considered as cancer stem cells (CSC). Although a number of molecules have been identified in different cancer cells as markers for cancer stem cells, no promising markers are currently available for hepatocellular carcinoma cells. In this study, two clones of Hep3B cell lines were functionally characterized as control or CSC-like cells, based on properties including spheroid formation, drug resistance, and tumor initiation. Furthermore, their protein expression profiles were investigated by isobaric tags for relative and absolute quantitation (iTRAQ), and a total of 1,127 proteins were identified and quantified from the combined fractions; 50 proteins exhibited at least 2-fold differences between these two clones. These 50 proteins were analyzed by GeneGo and were found to be associated with liver neoplasms, hepatocellular carcinoma (HCC), and liver diseases. They were also components of metabolic pathways, immune responses, and cytoskeleton remodeling. Among these proteins, the expressions of S100P, S100A14, and vimentin were verified in several HCC cell lines, and their expressions were correlated with tumorigenicity in HCC cell lines. The functional significance of vimentin and S100A14 were also investigated and verified. PMID:23782096

Ko, Ching-Huai; Cheng, Chieh-Fang; Lai, Chin-Pen; Tzu, Te-Hui; Chiu, Chih-Wei; Lin, Mei-Wei; Wu, Si-Yuan; Sun, Chung-Yuan; Tseng, Hsiang-Wen; Wang, Chun-Chung; Kuo, Zong-Keng; Wang, Ling-Mei; Chen, Sung-Fang

2013-08-01

263

Tuning universality far from equilibrium

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. PMID:23928853

Karl, Markus; Nowak, Boris; Gasenzer, Thomas

2013-01-01

264

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

265

Degenerate equilibrium states of collisionless stellar systems

We study spherically symmetrical equilibrium states of collisionless stellar systems confined to a spherical box. These equilibrium states correspond to the statistics introduced by Lynden-Bell in his theory of `violent relaxation', and are described by a Fermi-Dirac distribution function. We compute the corresponding equilibrium diagram and show that a global entropy maximum exists for any accessible control parameter. This equilibrium

P.-H. Chavanis; J. Sommeria

1998-01-01

266

Equilibrium in a Production Economy

Consider a closed production-consumption economy with multiple agents and multiple resources. The resources are used to produce the consumption good. The agents derive utility from holding resources as well as consuming the good produced. They aim to maximize their utility while the manager of the production facility aims to maximize profits. With the aid of a representative agent (who has a multivariable utility function) it is shown that an Arrow-Debreu equilibrium exists. In so doing we establish technical results that will be used to solve the stochastic dynamic problem (a case with infinite dimensional commodity space so the General Equilibrium Theory does not apply) elsewhere.

Chiarolla, Maria B., E-mail: maria.chiarolla@uniroma1.it [Universita di Roma 'La Sapienza', Dipartimento di Metodi e Modelli per l'Economia, il Territorio e la Finanza, Facolta di Economia (Italy); Haussmann, Ulrich G., E-mail: uhaus@math.ubc.ca [University of British Columbia, Department of Mathematics (Canada)

2011-06-15

267

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

268

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

269

Magnetospheric equilibrium with anisotropic pressure

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

270

Financial Constraints and Unemployment Equilibrium

This paper aims to show (1) that the IS\\/LM model will be a coherent solution to Keynes's analysis of unemployment, if the relaxation of the general equilibrium framework is based solely on exogenous price and quantity constraints; (2) that the consequent determination of unemployment equilibria is analytically fragile and does not support Keynes' attempt to reduce the standard approach to

CESARONI GIOVANNI; MESSORI MARCELLO

2003-01-01

271

Equilibrium Statistical Mechanics Giovanni Gallavotti

1 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 properties, proved or assumed, of few particles systems

Roma "La Sapienza", UniversitÃ di

272

Equilibrium Statistical Mechanics Giovanni Gallavotti

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", UniversitÃ di

273

Equilibrium Statistical Mechanics Giovanni Gallavotti

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 properÂ ties, proved or assumed, of few particles

Roma "La Sapienza", UniversitÃ di

274

Equilibrium Wage and Dismissal Processes

I develop and estimate an equilibrium model of the labor market in which inefficient employees are systematically eliminated from the sector of the market characterized by asymmetric information and moral hazard. Systematic selection on the distribution of productivity characteristics produces wage sequences that are increasing in tenure for employees never previously terminated even in the absence of long-term contracting between

Christopher J. Flinn

1997-01-01

275

Equilibrium Thermodynamics of Lattice QCD

Lattice QCD allows us to simulate QCD at non-zero temperature and/or densities. Such equilibrium thermodynamics calculations are relevant to the physics of relativistic heavy-ion collisions. I give a brief review of the field with emphasis on our work.

D. K. Sinclair

2007-01-14

276

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

277

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. PMID:24254578

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

2014-02-01

278

NASA Astrophysics Data System (ADS)

Isothermal-isobaric molecular-dynamics simulations have been performed to investigate the glassy and liquid structures of two alkali chloride systems [mixture (LiCl)0.50(KCl)0.40(CsCl)0.10 and pure LiCl]. With the use of an ionic interaction model, the basic thermodynamic properties of the crystalline, liquid, and glassy states are successfully reproduced in the simulations. At normal pressure (101.3 MPa), it is found that the predominant short-range order in both systems is the LiCl4 tetrahedral units, each pair of which is mutually connected by sharing not only the vertices but also the edges of the tetrahedra. In the glassy and liquid states of LiCl-KCl-CsCl, the network structure is formed by polytetrahedral medium-range order (LiLi4) consisting of five connected LiCl4 tetrahedra. Some portions of this network are truncated by the K+ and Cs+ ions adjacent to the vertex Cl- ions. On the other hand, liquid and glassy LiCl has a disordered structure approximately analogous to zinc-blende structure, also including the wurtzitelike ionic arrangement. For LiCl in the amorphous and crystalline states, we performed isothermal-compression simulations up to 30 GPa. As in the experimental findings, no structural transformation occurs for the rocksalt LiCl crystal. The compression causes the crystallization of amorphous LiCl into rocksalt structure at more than 3-10 GPa with continuous structural change. This structural transformation is analogous to the pressure-induced polymorphic transition (zinc blende-->rocksalt) that occurs in the crystals of more covalent compounds such as CdS.

Kinugawa, Kenichi

1993-10-01

279

NASA Astrophysics Data System (ADS)

In the Higher Himalaya of the region from Cho Oyu to the Arun valley northeast of Makalu, the Miocene leucogranites are not hosted only in the upper High Himalayan Crystallines (HHC); a network of dykes also cuts the lower HHC and the Lesser Himalayan Crystallines (LHC). The plutons and dykes are mainly composed of two-mica (muscovite+biotite±tourmaline±cordierite±andalusite±sillimanite) leucogranite, with tourmaline?2.6% and biotite>1.5% modal, and tourmaline (muscovite+tourmaline±biotite±sillimanite ±garnet±kyanite±andalusite±spinel±corundum) leucogranite, with tourmaline>2.2% and biotite<1.5% modal. Both leucogranite types were produced by partial melting in the andalusite-sillimanite facies series, under LP/HT conditions constrained by the occurrence of peritectic andalusite and cordierite. The geochemical features of the leucogranites suggest that tourmaline leucogranite was produced by muscovite dehydration melting in muscovite-rich metapelites at P˜350 MPa and T?640°C, whereas two-mica leucogranite was produced by biotite dehydration melting in biotite-rich metapelites at P˜300 MPa and T?660-710 °C. Melting in fertile muscovite-rich metapelites of the top of both the HHC and LHC produced magmas which were emplaced at the same structural level in which they had been generated. Melting in the biotite-rich gneiss of both the HHC and LHC produced hotter magmas which were transported upwards by dyking and eventually coalesced in the plutons of the upper HHC. A similar process also produced a network of two-mica granite at the top of the LHC in the Ama Drime-Nyönno Ri Range northeast of Makalu. The prograde character of leucogranite melt-producing reactions in the Everest-Makalu area suggests that, here, the generation of Miocene leucogranites took place in a regime of nearly isobaric heating following nearly adiabatic decompression.

Visonà, Dario; Lombardo, Bruno

2002-06-01

280

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. PMID:24845350

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

2014-07-01

281

The selection of efficient separating agents for the extractive fractionation of aliphatic-aromatic hydrocarbon systems has fundamental importance in technology of preparing pure aromatic hydrocarbons. It has been shown previously that N-methylpyrrolidone (NMP) can be used as an efficient separating agent for paraffin-aromatic hydrocarbon, naphthene-aromatic hydrocarbon, or olefin-aromatic hydrocarbon systems. It was previously shown that the presence of water in the NMP increases its selectivity in the heptane-benzene system. However, the limited number of systems studied which contain heptane does not allow one to make a judgment about the relative volatility of paraffins, naphthenes, olefins, and benzene in mixtures with NMP containing water. Moreover, the complexity of the indicated systems causes definite difficulties in the experimental study of the isobaric liquid-vapor equilbrium for determining the relative volatility ..cap alpha../sub i-j/ of nonaromatic hydrocarbons, i, and benzene, j, as a function of the concentration of an extractant containing water, X/sub r/. The author has previously made studies of methods of calculating liquid-vapor equilibrium in the analogous systems with anhydrous NMP from a limited amount of information about liquid-vapor equilibrium. Therefore the objective of this work was to perform analytical calculations and an experimental check of liquid-vapor equilibrium in systems which included paraffins, naphthenes, olefins, benzene, NMP, and water.

Miroshnichenko, A.A.

1983-07-20

282

Punctuated equilibrium comes of age

NASA Astrophysics Data System (ADS)

The intense controversies that surrounded the youth of punctuated equilibrium have helped it mature to a useful extension of evolutionary theory. As a complement to phyletic gradualism, its most important implications remain the recognition of stasis as a meaningful and predominant pattern within the history of species, and in the recasting of macroevolution as the differential success of certain species (and their descendants) within clades.

Gould, Stephan Jay; Eldredge, Niles

1993-11-01

283

Stochastic Nash Equilibrium Problems: Sample Average ...

the problem and the first order equilibrium conditions are characterized in terms of .... of convergence is usually obtained by applying classical uniform strong law of ...... V. Piccialli, Generalized Nash equilibrium problems and Newton methods,.

2010-01-22

284

On static equilibrium and balance puzzler

The principles of static equilibrium are of special interest to civil engineers. For a rigid body to be in static equilibrium the condition is that net force and net torque acting on the body should be zero. That clearly signifies that if equal weights are placed on either sides of a balance, the balance should be in equilibrium, even if its beam is not horizontal (we have considered the beam to be straight and have no thickness, an ideal case). Thus, although the weights are equal, they will appear different which is puzzling. This also shows that the concept of equilibrium is confusing, especially neutral equilibrium is confused to be stable equilibrium. The study not only throws more light on the concept of static equilibrium, but also clarifies that a structure need not be firm and steady even if it is in static equilibrium.

Samrat Dey; Ashish Paul; Dipankar Saikia; Deepjyoti Kalita; Anamika Debbarma; Shaheen Akhtar Wahab; Saurabh Sarma

2012-12-12

285

Torque equilibrium attitude control for Skylab reentry

NASA Technical Reports Server (NTRS)

All the available torque equilibrium attitudes (most were useless from the standpoint of lack of electrical power) and the equilibrium seeking method are presented, as well as the actual successful application during the 3 weeks prior to Skylab reentry.

Glaese, J. R.; Kennel, H. F.

1979-01-01

286

Equilibrium and kinetics in metamorphism

NASA Astrophysics Data System (ADS)

The equilibrium model for metamorphism is founded on the metamorphic facies principle, the repeated association of the same mineral assemblages in rocks of different bulk composition that have been metamorphosed together. Yet, for any metamorphic process to occur, there must be some degree of reaction overstepping (disequilibrium) to initiate reaction. The magnitude and variability of overstepping, and the degree to which it is either a relatively minor wrinkle or a more substantive challenge to the interpretation of metamorphic rocks using the equilibrium model, is an active area of current research. Kinetic barriers to reaction generally diminish with rising temperature due to the Arrhenius relation. In contrast, the rate of build-up of the macroscopic energetic driving force needed to overcome kinetic barriers to reaction, reaction affinity, does not vary uniformly with temperature, instead varying from reaction to reaction. High-entropy reactions that release large quantities of H2O build up reaction affinity more rapidly than low-entropy reactions that release little or no H2O, such that the former are expected to be overstepped less than the latter. Some consequences include: (1) metamorphic reaction intervals may be discrete rather than continuous, initiating at the point that sufficient reaction affinity has built up to overcome kinetic barriers; (2) metamorphic reaction intervals may not correspond in a simple way to reaction boundaries in an equilibrium phase diagram; (3) metamorphic reactions may involve metastable reactions; (4) metamorphic 'cascades' are possible, in which stable and metastable reactions involving the same reactant phases may proceed simultaneously; and (5) fluid generation, and possibly fluid presence in general, may be episodic rather than continuous, corresponding to discrete intervals of reaction. These considerations bear on the interpretation of P-T-t paths from metamorphic mineral assemblages and textures. The success of the metamorphic facies principle suggests that these effects are second-order features that operate within a broadly equilibrium approach to metamorphism. However, it may be that the close approach to equilibrium occurs primarily at the boundaries between the metamorphic facies, corresponding to relatively discrete intervals of reaction involving consumption of hydrous phases.

Pattison, D. R.

2012-12-01

287

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

288

Comparative Statics of General Equilibrium Asset Prices

Abstract This is a study on the comparative statics of general equilibrium asset prices in a representative-agent model where securities are specified by their dividend processes - vector geometric Brownian motions with fixed factor loadings. As usual, equilibrium asset prices are conditional expectations of future dividends valued at the marginal utility of equilibrium consumption. I examine the comparative statics of

Theodoros M. Diasakos

289

The MHD equilibrium problem in nonaxisymmetric toroidal

order to have a static (3D) equilibrium, p'() must be zero in thThe MHD equilibrium problem in nonaxisymmetric toroidal plasma confinement systems (as a novel KAM. Introduction: 3D MHD toroidal equilibrium problem, coordinates & field-line Hamiltonian 2. Problems (chaos

Hudson, Stuart

290

The complexity of computing a Nash equilibrium

How long does it take until economic agents converge to an equilibrium? By studying the complexity of the problem of computing a mixed Nash equilibrium in a game, we provide evidence that there are games in which convergence to such an equilibrium takes prohibitively long. Traditionally, com- putational problems fall into two classes: those that have a polynomial-time algorithm, and

Konstantinos Daskalakis; Paul W. Goldberg; Christos H. Papadimitriou

2005-01-01

291

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

292

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

293

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

294

Vaporizing Liquid Microthruster Concept: Preliminary Results of Initial Feasibility Studies

Introduction Chip Design and Fabrication Heater Characterization Description of Experiment Results Propellant Vaporization: Initial Studies Description of Experiment Preliminary Results Preliminary Conclusions and Future Work References

Juergen Mueller; Indrani Chakraborty; David Bame; William Tang

2000-01-01

295

Vaporizing Liquid Microthruster Concept: Preliminary Results of Initial Feasibility Studies

NASA Astrophysics Data System (ADS)

Introduction Chip Design and Fabrication Heater Characterization Description of Experiment Results Propellant Vaporization: Initial Studies Description of Experiment Preliminary Results Preliminary Conclusions and Future Work References

Mueller, Juergen; Chakraborty, Indrani; Bame, David; Tang, William

296

Equilibrium and non-equilibrium metal-ceramic interfaces

Metal-ceramic interfaces in thermodynamic equilibrium (Au/ZrO{sub 2}) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO{sub 2} system, ZrO{sub 2} precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO{sub 2} phase. It appears that formation of the cubic ZrO{sub 2} is facilitated by alignment with the Au matrix. Most of the ZrO{sub 2} precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed (111) Au/ZrO{sub 2} interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent of semi-coherent. This indicates that there may be relatively strong bond between MgO and Au.

Gao, Y.; Merkle, K.L.

1991-01-01

297

Equilibrium and non-equilibrium metal-ceramic interfaces

Metal-ceramic interfaces in thermodynamic equilibrium (Au/ZrO{sub 2}) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO{sub 2} system, ZrO{sub 2} precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO{sub 2} phase. It appears that formation of the cubic ZrO{sub 2} is facilitated by alignment with the Au matrix. Most of the ZrO{sub 2} precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed [111] Au/ZrO{sub 2} interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent of semi-coherent. This indicates that there may be relatively strong bond between MgO and Au.

Gao, Y.; Merkle, K.L.

1991-12-31

298

Princeton spectral equilibrium code: PSEC

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

299

Non-equilibrium phase transitions

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

300

The charge-exchange break-up of polarised deuterons pol{d}p -> {pp}n, where the final {pp} diproton system has a very low excitation energy and hence is mainly in the 1S0 state, is a powerful tool to probe the spin-flip terms in the proton-neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the Delta(1232) isobar in the pol{d}p -> {pp}X reaction. Values of the differential cross section and two deuteron tensor analysing powers, A_{xx} and A_{yy}, have been extracted in terms of the momentum transfer to the diproton or the invariant mass Mx of the unobserved system X. The unpolarised cross section in the high Mx region is well described in a model that includes only direct excitation of the Delta isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low Mx, even when Delta excitation in the projectile deuteron is included in the calculation. Furthermore, direct Delta production through one pion exchange only reproduces the angular dependence of the difference between the two tensor analysing powers.

D. Mchedlishvili; S. Barsov; J. Carbonell; D. Chiladze; S. Dymov; A. Dzyuba; R. Engels; R. Gebel; V. Glagolev; K. Grigoryev; P. Goslawski; M. Hartmann; O. Imambekov; A. Kacharava; V. Kamerdzhiev; I. Keshelashvili; A. Khoukaz; V. Komarov; P. Kulessa; A. Kulikov; A. Lehrach; N. Lomidze; B. Lorentz; G. Macharashvili; R. Maier; S. Merzliakov; M. Mielke; M. Mikirtychyants; S. Mikirtychyants; M. Nioradze; H. Ohm; M. Papenbrock; D. Prasuhn; F. Rathmann; V. Serdyuk; H. Seyfarth; H. J. Stein; E. Steffens; H. Stockhorst; H. Ströher; M. Tabidze; S. Trusov; Yu. Uzikov; Yu. Valdau; C. Wilkin

2013-05-23

301

The charge-exchange break-up of polarised deuterons pol{d}p -> {pp}n, where the final {pp} diproton system has a very low excitation energy and hence is mainly in the 1S0 state, is a powerful tool to probe the spin-flip terms in the proton-neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the Delta(1232) isobar in the pol{d}p -> {pp}X reaction. Values of the differential cross section and two deuteron tensor analysing powers, A_{xx} and A_{yy}, have been extracted in terms of the momentum transfer to the diproton or the invariant mass Mx of the unobserved system X. The unpolarised cross section in the high Mx region is well described in a model that includes only direct excitation of the Delta isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low Mx, even w...

Mchedlishvili, D; Carbonell, J; Chiladze, D; Dymov, S; Dzyuba, A; Engels, R; Gebel, R; Glagolev, V; Grigoryev, K; Goslawski, P; Hartmann, M; Imambekov, O; Kacharava, A; Kamerdzhiev, V; Keshelashvili, I; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Lehrach, A; Lomidze, N; Lorentz, B; Macharashvili, G; Maier, R; Merzliakov, S; Mielke, M; Mikirtychyants, M; Mikirtychyants, S; Nioradze, M; Ohm, H; Papenbrock, M; Prasuhn, D; Rathmann, F; Serdyuk, V; Seyfarth, H; Stein, H J; Steffens, E; Stockhorst, H; Ströher, H; Tabidze, M; Trusov, S; Uzikov, Yu; Valdau, Yu; Wilkin, C

2013-01-01

302

Excitation of the ?(1232) isobar in deuteron charge exchange on hydrogen at 1.6, 1.8, and 2.3 GeV

NASA Astrophysics Data System (ADS)

The charge-exchange break-up of polarised deuterons d?p?{pp}sn, where the final {pp}s diproton system has a very low excitation energy and hence is mainly in the S01 state, is a powerful tool to probe the spin-flip terms in the proton-neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the ?(1232) isobar in the d?p?{pp}sX reaction. Values of the differential cross section and two deuteron tensor analysing powers, Axx and Ayy, have been extracted as functions of the momentum transfer to the diproton or the invariant mass MX of the unobserved system X. The unpolarised cross section in the high MX region is well described in a model that includes only direct excitation of the ? isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low MX, even when ? excitation in the projectile deuteron is included in the calculation. Furthermore, direct ? production through one pion exchange only reproduces the angular dependence of the difference between the two tensor analysing powers.

Mchedlishvili, D.; Barsov, S.; Carbonell, J.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Engels, R.; Gebel, R.; Glagolev, V.; Grigoryev, K.; Goslawski, P.; Hartmann, M.; Imambekov, O.; Kacharava, A.; Kamerdzhiev, V.; Keshelashvili, I.; Khoukaz, A.; Komarov, V.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Maier, R.; Merzliakov, S.; Mielke, M.; Mikirtychyants, M.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H. J.; Steffens, E.; Stockhorst, H.; Ströher, H.; Tabidze, M.; Trusov, S.; Uzikov, Yu.; Valdau, Yu.; Wilkin, C.

2013-10-01

303

String fluid in local equilibrium

NASA Astrophysics Data System (ADS)

We study the solutions of string fluid equations under the assumption of a local equilibrium which was previously obtained in the context of the kinetic theory. We show that the fluid can be foliated into noninteracting submanifolds whose equations of motion are exactly that of the wiggly strings considered previously by Vilenkin and Carter. In a special case of negligible statistical variance in either the left- or the right-moving directions of microscopic strings, the submanifolds are described by the action of a null-current-carrying chiral string. When both variances vanish the submanifolds are described by the Nambu-Goto action and the string fluid reduces to the string dust introduced by Stachel.

Schubring, Daniel; Vanchurin, Vitaly

2014-10-01

304

Neoclassical equilibrium in gyrokinetic simulations

This paper presents a set of model collision operators, which reproduce the neoclassical equilibrium and comply with the constraints of a full-f global gyrokinetic code. The assessment of these operators is based on an entropy variational principle, which allows one to perform a fast calculation of the neoclassical diffusivity and poloidal velocity. It is shown that the force balance equation is recovered at lowest order in the expansion parameter, the normalized gyroradius, hence allowing one to calculate correctly the radial electric field. Also, the conventional neoclassical transport and the poloidal velocity are reproduced in the plateau and banana regimes. The advantages and drawbacks of the various model operators are discussed in view of the requirements for neoclassical and turbulent transport.

Garbet, X.; Dif-Pradalier, G.; Nguyen, C.; Sarazin, Y.; Grandgirard, V.; Ghendrih, Ph. [CEA, IRFM, F-13108 St. Paul-lez-Durance Cedex (France)

2009-06-15

305

A small amplitude oscillatory shear flows with the classic characteristic of a phase shift when using non-equilibrium molecular dynamics simulations for n-hexadecane fluids. In a suitable range of strain amplitude, the fluid possesses significant linear viscoelastic behavior. Non-linear viscoelastic behavior of strain thinning, which means the dynamic modulus monotonously decreased with increasing strain amplitudes, was found at extreme strain amplitudes. Under isobaric conditions, different temperatures strongly affected the range of linear viscoelasticity and the slope of strain thinning. The fluid's phase states, containing solid-, liquid-, and gel-like states, can be distinguished through a criterion of the viscoelastic spectrum. As a result, a particular condition for the viscoelastic behavior of n-hexadecane molecules approaching that of the Rouse chain was obtained. Besides, more importantly, evidence of thermorheologically simple materials was presented in which the relaxation modulus obeys the time-temperature superposition principle. Therefore, using shift factors from the time-temperature superposition principle, the estimated Arrhenius flow activation energy was in good agreement with related experimental values. Furthermore, one relaxation modulus master curve well exhibited both transition and terminal zones. Especially regarding non-equilibrium thermodynamic states, variations in the density, with respect to frequencies, were revealed. PMID:20379496

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

2010-04-28

306

1-D EQUILIBRIUM DISCRETE DIFFUSION MONTE CARLO

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

307

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

308

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

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

309

Hubbard nanoclusters far from equilibrium

NASA Astrophysics Data System (ADS)

The Hubbard model is a prototype for strongly correlated many-particle systems, including electrons in condensed matter and molecules, as well as for fermions or bosons in optical lattices. While the equilibrium properties of these systems have been studied in detail, the nonequilibrium dynamics following a strong nonperturbative excitation only recently came into the focus of experiments and theory. It is of particular interest how the dynamics depend on the coupling strength and on the particle number and whether there exist universal features in the time evolution. Here, we present results for the dynamics of finite Hubbard clusters based on a self-consistent nonequilibrium Green functions (NEGF) approach invoking the generalized Kadanoff-Baym ansatz (GKBA). We discuss the conserving properties of the GKBA with Hartree-Fock propagators in detail and present a generalized form of the energy conservation criterion of Baym and Kadanoff for NEGF. Furthermore, we demonstrate that the HF-GKBA cures some artifacts of prior two-time NEGF simulations. Besides, this approach substantially speeds up the numerical calculations and thus presents the capability to study comparatively large systems and to extend the analysis to long times allowing for an accurate computation of the excitation spectrum via time propagation. Our data obtained within the second Born approximation compare favorably with exact diagonalization results (available for up to 13 particles) and are expected to have predictive capability for substantially larger systems in the weak-coupling limit.

Hermanns, Sebastian; Schlünzen, Niclas; Bonitz, Michael

2014-09-01

310

The Equilibrium Manifold: Postmodern Developments in the Theory of General Economic Equilibrium

In The Equilibrium Manifold, noted economic scholar and major contributor to the theory of general equilibrium Yves Balasko argues that, contrary to what many textbooks want readers to believe, the study of the general equilibrium model did not end with the existence and welfare theorems of the 1950s. These developments, which characterize the modern phase of the theory of general

Yves Balasko

311

A general equilibrium analysis of partial-equilibrium welfare measures: The case of climate change

This paper uses computable general equilibrium models to demonstrate that partial-equilibrium welfare measures can offer reasonable approximations of the true welfare changes for large exogenous changes. With consistency in the size and direction of the indirect price effects associated with large shocks, single sector partial-equilibrium measures will exhibit small errors. Otherwise the errors can be substantial and difficult to sign.

Kokoski, M.F.; Smith, V.K. (Bureau of Labor Statistics, Washington, DC (USA))

1987-06-01

312

Equilibrium The theory of equilibrium attempts to predict what happens in a game

2 Equilibrium The theory of equilibrium attempts to predict what happens in a game when players over games to find games with good equilibria. Here, we review the most fundamental notions of equilibrium. They will all be static notions in that players are assumed to understand the game and will play

Fiat, Amos

313

Equilibrium 2 H fractionations in organic molecules

the biochemical basis for biosynthetic fractionations (Sessions et al., 1999; Chikaraishi et al., 2004a,b; ZhangEquilibrium 2 H/1 H fractionations in organic molecules: I. Experimental calibration of ab initio.e., the equilibrium isotopic fractionation factor (aeq). To date, relevant data have been lacking for molecules larger

Sessions, Alex L.

314

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.)

315

Parametric tests for static and dynamic equilibrium

Econometric estimates of the characteristics of production are highly sensitive to the choice of dynamic specification. In this paper we propose a new approach for testing whether inputs are in static equilibrium. The procedure, which is based on the use of a generalized cost function, tests for divergences between the actual and static equilibrium quantities of all inputs simultaneously and

Scott E. Atkinson; Robert Halvorsen

1998-01-01

316

Pretirage INLN..... Non equilibrium statistical mechanics

1 PrÂ´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, UniversitÃ© de

317

Mixed variational inequalities and economic equilibrium problems

We consider rather broad classes of general economic equilibrium problems and oligopolistic equilibrium problems which can be formulated as mixed variational inequality problems. Such problems involve a continuous mapping and a convex, but not necessarily differentiable function. We present existence and\\u000auniqueness results of solutions under weakened $P$ -type assumptions on the cost mapping. They enable us to establish new

I. V. Konnov; E. O. Volotskaya

2002-01-01

318

Sensitivity theory for the equilibrium burnup cycle

The design and analysis of advanced reactor concepts are based on the performance of the equilibrium cycle (sometimes also referred to as they cyclic mode of the reactor), rather than some arbitrary sequence of start-up cycles. While sensitivity theory has been developed for a sequence of nonequilibrium (or initial value) depletion problems, the equilibrium problem has not been previously considered.

W. S. Yang; T. J. Downar

1989-01-01

319

NASA Astrophysics Data System (ADS)

The main focus of the present paper is on studying the nematic-smectic- A phase boundary of an ideally oriented Gay-Berne system. The phase diagram is determined by means of an isothermal-isobaric Monte Carlo simulation. The results are compared with predictions of the local density functional expanded up to second and third order in the one-particle distribution function. It is shown that generally the second-order expansion does not give satisfactory predictions for smectics. Going beyond the leading order yields good quantitative agreement at moderate densities. With increasing density the relative error of the local density functional calculations increases, but usually does not exceed 10% in densities. We conclude that the density functional approach could be competitive to time-consuming simulations in determining phase diagrams of spatially and orientationally ordered liquid crystalline structures.

Józefowicz, W.; Cholewiak, G.; Longa, L.

2005-03-01

320

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

321

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

322

Disturbances in equilibrium function after major earthquake

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

323

Large sets of biological samples are commonly encountered in biomedical research, and a rigorous, reliable top-down quantification method for proteins from multiple samples is required. With differential in-gel electrophoresis (DIGE), Cy3 and Cy5 dyes are used to fluorescently label two different protein samples prior to running them on the same 2D gel. Often, Cy2 dye is used as an internal standard as well. This approach permits analysis of two to three samples under identical conditions, eliminating the need to register and match the images as in traditional 2D gels. Though conceptually seductive, problems plague DIGE, especially when attempting to perform complex quantitative proteomics studies. Since the DIGE images are generated with two to three different dyes of differing molar extinction coefficients, quantum yields, and physicochemical properties, absolute quantification of small intensity differences is challenging. Also, DIGE is overly simplistic in its basic assumption that all information required in an experiment can be obtained from a single 2D gel using an easy control-vs.-perturbed state experimental design. Multi-point time-course experiments and drug dose-response experiments require many more than the two to three sample capacity of DIGE. An isobaric mass tagging strategy is presented wherein seven different samples are simultaneously fractionated on a single 2D gel and protein abundances subsequently quantified by mass spectrometry. Workflows that replace or alternatively augment DIGE are described. Reproducibility of conventional DIGE vs. the isobaric mass tagging strategy demonstrates higher accuracy quantification obtained with the latter approach.

Xie, B.; Hekking, B.; Lisoukov, H.; Wang, Y.; Parman, C.; Patton, W. F.

2007-01-01

324

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. PMID:21952753

Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

2014-01-01

325

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

326

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

327

STP Lennard-Jones Thermal Equilibrium Program

NSDL National Science Digital Library

The STP LJ Thermal Equilibrium program simulates the interaction between two systems of Lennard-Jones particles brought into thermal contact. The purpose of this simulation is to explore the nature of thermal equilibrium and the relation, if any, between the kinetic and potential energies of two systems in thermal contact. The two initially isolated systems have 81 (red) and 64(green) particles by default. STP LJThermalEquilibrium is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_LJThermalEquilibrium.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-13

328

On the equilibrium of rotating filaments

The physical properties of the so-called Ostriker isothermal, non-rotating filament have been classically used as benchmark to interpret the stability of the filaments observed in nearby clouds. However, such static picture seems to contrast with the more dynamical state observed in different filaments. In order to explore the physical conditions of filaments under realistic conditions, in this work we theoretically investigate how the equilibrium structure of a filament changes in a rotating configuration. To do so, we solve the hydrostatic equilibrium equation assuming both uniform and differential rotations independently. We obtain a new set of equilibrium solutions for rotating and pressure truncated filaments. These new equilibrium solutions are found to present both radial and projected column density profiles shallower than their Ostriker-like counterparts. Moreover, and for rotational periods similar to those found in the observations, the centrifugal forces present in these filaments are also able to...

Recchi, S; Palestini, A

2014-01-01

329

Sound speeds in suspensions in thermodynamic equilibrium

NASA Astrophysics Data System (ADS)

This work considers sound propagation in suspensions of particles of constant mass in fluids, in both relaxed and frozen thermodynamic equilibrium. Treating suspensions as relaxing media, thermodynamic arguments are used to obtain their sound speeds in equilibrium conditions. The results for relaxed equilibrium, which is applicable in the limit of low frequencies, agree with existing theories for aerosols, but disagree with Wood's equation. It is shown that the latter is thermodynamically correct only in the exceptional case when the specific heat ratios of the fluid and of the particles are equal to unity. In all other cases discrepancies occur. These may be significant when one of the two phases in the suspension is a gas, as is the case in aerosols and in bubbly liquids. The paper also includes a brief discussion of the sound speed in frozen equilibrium.

Temkin, S.

1992-11-01

330

Adaptive radiation: convergence and non-equilibrium.

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

331

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

332

Inventories and capacity utilization in general equilibrium

The primary goal of this dissertation is to gain a better understanding, in thecontext of a dynamic stochastic general equilibrium framework, of the role of inventories and capacity utilization (of both capital and labor) and, in particular...

Trupkin, Danilo Rogelio

2009-05-15

333

Equilibrium Reconstruction on the Large Helical Device

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

334

Master thesis Non-equilibrium Solidification

Metallurgy Graduate Institute of Ferrous Technology Pohang University of Science and Technology 2011 #12-equilibrium solidification of -TRIP steel Computational Metallurgy 2011 Advisor: Prof. Suh, Dong-Woo Text in English Abstract

Cambridge, University of

335

Equilibrium shape of crystals H. J. Schulz

are qualitatively different. For example, the equilibrium shape of 4He crystals is completely rounded above about 1257 Equilibrium shape of crystals H. J. Schulz Institut Laue-Langevin, 156X, 38042 Grenoble Cedex, acceptÃ© le 9 octobre 1984 ) RÃ©sumÃ©. 2014 Nous dÃ©crivons les mÃ©canismes physiques qui contrÃ´lent la forme d

Paris-Sud XI, UniversitÃ© de

336

Vapor Equilibrium Relationships of Dry Milk1

apor equilibrium data have been used to predict and explain water-binding properties of spray-dried milk. Equilibrium moisture contents for nonfat products with low, medium, and high preheat treatment and low-heat product with 1, 13, and 26% of milk fat were obtained at storage temperatures of 35, 60, 86, and 100 F. Based on proposed water sorption mechanisms for proteins, a

D. R. Heldman; C. W. Hall; T. I. Hedrick

1965-01-01

337

Thermal equilibrium in argon induction discharges

The equilibrium state of induction discharge plasmas in argon has been examined for a wide range of pressures (7·6 to 760 Torr) and with electron densities ranging from 3×1014 to 8×1015 cm?3. Grossly non-thermal conditions are obtained when the electron density falls below 1015 cm?3. For higher densities the approach to LTE (local thermal equilibrium) depends on the strength of

A D Stokes

1971-01-01

338

Equilibrium fluctuation energy of gyrokinetic plasma

The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed, and found to be smaller than the well-known result

Krommes, J.A.; Lee, W.W.; Oberman, C.

1985-11-01

339

Theory for non-equilibrium statistical mechanics.

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

340

Equilibrium ab initio (AI) and classical constant pressure-constant temperature molecular dynamics (MD) simulations have been performed to investigate the dynamical properties in (type I) hydrogen sulphide hydrate at 150 and 300 K and 1 bar, and also lower temperatures, with particular scrutiny of guest motion. The rattling motions of the guests in the large and small cavities were around 45 and 75-80 cm(-1), respectively, from AIMD, with the corresponding classical MD modes being 10-12 cm(-1) less at 150 K and around 5 cm(-1) lower at 300 K. The rattling motion in the small cavity overlapped somewhat with the translational motion of the host lattice (with modes at circa 85 and 110 cm(-1)), due in part to a smaller cage radius and more frequent occurrences of guest-host hydrogen bonding leading to greater coupling in the motion. The experimentally determined H-S stretch and H-S-H bending frequencies, in the vicinity of 2550-2620 and 1175 cm(-1) [H.R. Richardson et al., J. Chem. Phys.1985, 83, 4387] were reproduced successfully in the AIMD simulations. Consideration of Kubic harmonics for the guest molecules from AIMD revealed that a preferred orientation of the dipole-vector (or C(2)-axis) exists at 150 K vis--vis the [100] cube axis in both the small and large cavities, but is markedly more significant for the small cavity, while there is no preferred orientation at 300 K. In comparison, classical MD did not reveal any preferred orientation at either temperature, or at 75 K (closer to the AIMD simulation at 150 K vis-à-vis that approach's estimated melting point). Probing rotational dynamics of the guests reinforced this temperature effect, revealing more rapid rotational time scales at 300 K with faster decay times of dipole-vector (C(2)) and H-H-vector (C(2)(y)) being similar for each cage, at around 0.25 and 0.2 ps, respectively, versus approximately 0.45 and 0.5 ps (large) and 0.8 ps (small) at 150 K. It was found that the origin of the observed preferred orientations, especially in the small cages, at 150 K via AIMD was attributable to optimization of the dipolar interaction between the guest and outward-pointing water dipoles in the cavity, with guests "flitting" rotationally between various such configurations, forming occasionally hydrogen bonds with the host molecules. PMID:21391544

English, Niall J; Tse, John S

2011-06-16

341

Planetary cratering 2: Studies of saturation equilibrium

NASA Astrophysics Data System (ADS)

A realistic computer model has been developed to display images of imaginary cratered surfaces, taking into account empirically measured input size distributions of primary and secondary craters, ejecta blanket morphology including feathering with distance, obliteration due to ejecta from outside the imaged area, lighting effects, etc. The model allows us to track surface evolution of morphology as new craters are added. Using the model as well as lunar photos, we have studied the approach to saturation equilibrium (defined as a condition when no further proportionate increase in crater density occurs as input cratering increases). We find that an identifiable saturation equilibrium occurs close to a level previously identified for this state (Hartmann 1984), typically fluctuating around a crater density from about 0.4 to 2 times that level. This result is fairly robust vis-a-vis the range of model parameters we have chosen. Flooding, basin ejecta blankets, and other obliterative effects can introduce structure and oscillations within this range, even after saturation equilibrium is achieved. These findings may constrain or revise certain earlier interpretations of satellite and planet surface evolution and impactor populations which were predicated on the assumed absence of saturation equilibrium. In our fourth experimental run, we found that suppression of "sandblasting" by sub-resolution impacts allows the smallest secondaries to rise above the saturation equilibrium line, a result that might be relevant to a similar situation on Gaspra and perhaps some other asteroids.

Hartmann, William K.; Gaskell, Robert W.

1997-01-01

342

We present herein, a comprehensive density functional theory study towards 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-isotherma ensemble. Our results indicate that both PBE and BLYP functionals underpredict the density and overstructure 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. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program, and was performed in part using the Molecular Science Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility located at the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE.

Schmidt, Jochen; VandeVondele, Joost; Kuo, I-F W.; Sebastiani, Daniel; Siepmann, Joern L.; hutter, juerg; Mundy, Christopher J.

2009-09-03

343

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

344

Collisional cooling employed in an orthogonal time-of-flight mass spectrometer (o-TOF MS) stabilizes fragment ions that are generated by matrix-assisted laser desorption ionization in-source decay (MALDI ISD). By variation of the buffer gas pressure, ISD and "post-source decay" (PSD) dissociation channels can be switched on and off to some extent. Under high-pressure conditions, ISD type fragments of post-translationally modified (PTM) peptides are generated that contain even labile bound side groups; the examples of a phosphorylated and an O-glycosylated peptide are shown. At elevated laser fluences, d- and w-type fragment ions of peptides are detected as a result of high-energy side chain cleavage. This allows for differentiation of the isobaric amino acid residues leucine and isoleucine. Reduction of the cooling efficiency by lowering the buffer gas pressure results in the loss of the d-/w-type species, presumably in secondary metastable dissociation processes. This also enhances cleavage of the side groups from the PTM peptides and can be used to corroborate identification of the modification site. Furthermore, these measuring conditions generate small amounts of fragments containing sequence information about the cyclic part of a disulfide peptide by inducing symmetric and asymmetric cleavage of the intramolecular S-S bond. PMID:20524643

Soltwisch, Jens; Dreisewerd, Klaus

2010-07-01

345

Non--Equilibrium Blunt Body Flow 1 Analysis of NonEquilibrium, Hypersonic Blunt

Non--Equilibrium Blunt Body Flow 1 Analysis of NonÂEquilibrium, Hypersonic Blunt Body Flow streamline quantities and the stagnation point heat transfer in hypersonic flows about spheres or cylinders, as two-- dimensional hypersonic flows about spheres or cylinders exhibit an approximate local similarity

346

NASA Astrophysics Data System (ADS)

A century ago, the foundations of equilibrium statistical mechanics were laid. For a system in equilibrium with a thermal bath, much is understood through the Boltzmann factor, e- H[ C]/kT , for the probability of finding the system in any microscopic configuration C. In contrast, apart from some special cases, little is known about the corresponding probabilities, if the same system is in contact with more than one reservoir of energy, so that, even in stationary states, there is a constant energy flux through our system. These non-equilibrium steady states display many surprising properties. In particular, even the simplest generalization of the Ising model offers a wealth of unexpected phenomena. Mostly discovered through Monte Carlo simulations, some of the novel properties are understood while many remain unexplained. A brief review and some recent results will be presented, highlighting the sharp contrasts between the equilibrium Ising system and this non-equilibrium counterpart.

Zia, R. K. P.; Shaw, L. B.; Schmittmann, B.; Astalos, R. J.

2000-05-01

347

Equilibrium exchange rate theories under flexible exchange rate regimes

Economic theory refers to several notions of the exchange rate equilibrium value in a flexible exchange rate regime. It has been defined as that consistent with : a) the equilibrium of trade balance; b)the equilibrium of current account; c) the overall equilibrium of the balance of payments; d) the absence of speculative attacks on foreign exchange markets; e) the absence

Rosaria Rita Canale

2002-01-01

348

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

349

Equilibrium stellar systems with genetic algorithms

NASA Astrophysics Data System (ADS)

In 1979, M Schwarzschild showed that it is possible to build an equilibrium triaxial stellar system. However, the linear programmation used to that goal was not able to determine the uniqueness of the solution, nor even if that solution was the optimum one. Genetic algorithms are ideal tools to find a solution to this problem. In this work, we use a genetic algorithm to reproduce an equilibrium spherical stellar system from a suitable set of predefined orbits, obtaining the best solution attainable with the provided set. FULL TEXT IN SPANISH

Gularte, E.; Carpintero, D. D.

350

Amazon Basin: A System in Equilibrium

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

351

DECOMPOSITION AND SAMPLING METHODS STOCHASTIC EQUILIBRIUM PROBLEMS

DECOMPOSITION AND SAMPLING METHODS FOR STOCHASTIC EQUILIBRIUM PROBLEMS a dissertation submitted of the resulting algorithm is proved. We also present a cut-sampling method that uses a sample of the cuts by as much as 40%. The sampling method results in solutions that are within 3% of the optimal solution when

Stanford University

352

Non-equilibrium spatial dynamics of ecosystems.

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

353

Lumpy investment in sticky information general equilibrium

This paper introduces lumpy micro-level investment into a sticky information general equilibrium model. Lumpy investment arises because of inattentiveness in capital investment decisions instead of the more popular assumption of non-convex adjustment costs. Sticky information is the only source of rigidity in the model and it is pervasive to all markets and decisions. The model yields aggregate dynamics that are

Fabio Verona

2011-01-01

354

Equilibrium swelling properties of polyampholytic hydrogels

The role of counter ions and ion dissociation in establishing the equilibrium swelling of balanced and unbalanced polyampholytic hydrogels has been investigated experimentally and theoretically. The swelling dependence on both the net charge offset and the external bath salt concentration has been examined using an acrylamide based polyampholytic hydrogels. By careful consideration of the swelling kinetics, we illustrate the effects

Anthony E. English; Salvador Mafé; José A. Manzanares; Xiahong Yu; Alexander Yu. Grosberg; Toyoichi Tanaka

1996-01-01

355

Equilibrium Theory of Concentrated Colloidal Suspensions

This thesis examines three related problems in the theory of concentrated colloidal suspensions which arise from the effort to understand how electrostatic interactions between charged, dispersed particles affect their aggregate equilibrium behavior. It treats formally the questions: (1) is it possible to create an approach to evaluating double-layer interactions that unifies the microscopic modelling of ionic distributions near charged interfaces,

Eric Stephen Reiner

1994-01-01

356

Assessing Students' Conceptual Understanding of Solubility Equilibrium.

ERIC Educational Resources Information Center

Presents a problem on solubility equilibrium which involves macroscopic, microscopic, and symbolic levels of representation as a resource for the evaluation of students, and allows for assessment as to whether students have acquired an adequate conceptual understanding of the phenomenon. Also diagnoses difficulties with regard to previous…

Raviolo, Andres

2001-01-01

357

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.)

358

Problems on Non-Equilibrium Statistical Physics

Four problems in non-equilibrium statistical physics are investigated: 1. The thermodynamics of single-photon gas; 2. Energy of the ground state in Multi-electron atoms; 3. Energy state of the H2 molecule; and 4. The Condensation behavior in N...

Kim, Moochan

2011-08-08

359

An iterative substructuring algorithm for equilibrium equations

Summary The topic of iterative substructuring methods, and more generally domain decomposition methods, has been extensively studied over the past few years, and the topic is well advanced with respect to first and second order elliptic problems. However, relatively little work has been done on more general constrained least squares problems (or equivalent formulations) involving equilibrium equations such as those

Douglas James; Robert J. Plemmons

1990-01-01

360

Equilibrium free energies from nonequilibrium processes

A recent result, relating the (irreversible) work performed on a system during a non quasistatic process, to the Helmholtz free energy difference between two equilibrium states of the system, is discussed. A proof of this result is given for the special case when the evolution of the system in question is modeled by a Langevin equation in configuration space.

Jarzynski, C.

1997-10-29

361

Sorptional equilibrium and drying characteristics of garlic

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

362

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

363

The thermal equilibrium of molecular clouds

Some heating and cooling mechanisms which determine the thermal equilbrium of molecular clouds are introduced, such as radiative cooling (or heating) by molecules or atoms, heating through dust-gas collisions and gravitational collapse, and so on. Some discussions about how to determine the thermal equilibrium temperature of different kinds of molecular clouds are also given.

Y. Tang; D. Xiang

1987-01-01

364

Role of the Laboratory: Static Equilibrium

NSDL National Science Digital Library

This activity from the PTRA Manual "The Role of the Laboratory in Teaching Introductory Physics" is a variation of the typical static laboratory activity, and includes a method of measuring buoyant force. See article "Static Equilibrium", by Jim Nelson in the December, 1985 issue of The Science Teacher.

Nelson, Jim; Nelson, Jane

2006-06-18

365

Testing Static Equilibrium for Legged Robots

Consider a legged robot at fixed foot placements. Where can the robot move its center of mass (CM) while remaining in static equilibrium? If the terrain is flat, the CM must lie above the convex hull of the robot's feet. If the terrain is not flat, this often-used approximation can be arbitrarily bad. Instead, the CM must lie above the

Timothy Bretl; Sanjay Lall

2008-01-01

366

Children's conceptual understanding of forces and equilibrium

NSDL National Science Digital Library

Children in years three, four, and five of physics study were tested to determine their intuitive preconceptions about forces and equilibrium in the static case, as well as any changes in their conceptual framework that might have taken place as a result of maturity and instruction.

Jones, George; Hurford, Will; Terry, Colin

2005-11-28

367

On magnetostatic equilibrium in a stratified atmosphere

This is a study of the relationship between a magnetic field and its embedding plasma in static equilibrium in a uniform gravity. The ideal gas law is assumed. A system invariant in a given direction is treated first. We show that an exact integral of the equation for force balance across field lines can be derived in a closed form.

B. C. Low

1980-01-01

368

Recency, consistent learning, and Nash equilibrium.

We examine the long-term implication of two models of learning with recency bias: recursive weights and limited memory. We show that both models generate similar beliefs and that both have a weighted universal consistency property. Using the limited-memory model we produce learning procedures that both are weighted universally consistent and converge with probability one to strict Nash equilibrium. PMID:25024197

Fudenberg, Drew; Levine, David K

2014-07-22

369

Effective equilibrium theory of nonequilibrium quantum transport

NASA Astrophysics Data System (ADS)

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.

Dutt, Prasenjit; Koch, Jens; Han, Jong; Le Hur, Karyn

2011-12-01

370

On the equilibrium of rotating filaments

NASA Astrophysics Data System (ADS)

The physical properties of the so-called Ostriker isothermal, non-rotating filament have been classically used as benchmark to interpret the stability of the filaments observed in nearby clouds. However, such static picture seems to contrast with the more dynamical state observed in different filaments. In order to explore the physical conditions of filaments under realistic conditions, in this work we theoretically investigate how the equilibrium structure of a filament changes in a rotating configuration. To do so, we solve the hydrostatic equilibrium equation assuming both uniform and differential rotations independently. We obtain a new set of equilibrium solutions for rotating and pressure truncated filaments. These new equilibrium solutions are found to present both radial and projected column density profiles shallower than their Ostriker-like counterparts. Moreover, and for rotational periods similar to those found in the observations, the centrifugal forces present in these filaments are also able to sustain large amounts of mass (larger than the mass attained by the Ostriker filament) without being necessary unstable. Our results indicate that further analysis on the physical state of star-forming filaments should take into account rotational effects as stabilizing agents against gravity.

Recchi, S.; Hacar, A.; Palestini, A.

2014-10-01

371

The 'Schwarzschild-Kerr' Equilibrium Configurations

We discuss the possibility of equilibrium between a Schwarzschild black hole possessing zero intrinsic angular momentum and a hyperextreme Kerr source. The balance occurs due to frame-dragging exerted by the latter source on the black-hole constituent, thus giving rise to a non-zero horizon's angular velocity parallel to the angular momentum of the Kerr object.

Manko, V. S. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico); Ruiz, E. [Instituto Universitario de Fisica Fundamental y Matematicas, Universidad de Salamanca, 37008 Salamanca (Spain)

2010-12-07

372

Integration Versus Outsourcing In Industry Equilibrium

We develop an equilibrium model of industrial structure in which the organization of firms is endogenous. Differentiated consumer products can be produced either by vertically integrated firms or by pairs of specialized companies. Production of each variety of consumer good requires a specialized component. Vertically integrated firms can manufacture the components they need, but they face a relatively high cost

Gene M. Grossman; Elhanan Helpman

2002-01-01

373

Equilibrium Concept for Overlapping Generations Organizations.

National Technical Information Service (NTIS)

A necessary feature for equilibrium is that beliefs about the behavior of other agents are rational. We argue that in stationary OLG environments this implies that any future generation in the same situation as the initial generation must do as well as th...

E. C. Prescott, J. V. Rios-Rull

2000-01-01

374

Equilibrium analysis, banking, contagion and financial fragility

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

375

Equilibrium analysis, banking and financial instability

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

376

Reliable Computation of Equilibrium States and Bifurcations

food chain in a chemostat (Canale's model), and a modification of thereof. This modification aids of ecological systems is the location of equilibrium states and bifurcations. Interval-Newton techniques in elucidating the nonlinear effects of introducing a hypothetical contaminant into a food chain. Keywords

Stadtherr, Mark A.

377

Generalized Equilibrium Problem with Mixed Relaxed Monotonicity

We extend the concept of relaxed ?-monotonicity to mixed relaxed ?-?-monotonicity. The concept of mixed relaxed ?-?-monotonicity is more general than many existing concepts of monotonicities. Finally, we apply this concept and well known KKM-theory to obtain the solution of generalized equilibrium problem. PMID:25121137

Rizvi, Haider Abbas; K?l?cman, Adem

2014-01-01

378

In a previous paper (Llovell et al. J. Phys. Chem. B, submitted for publication), the free-volume theory (FVT) was coupled with the soft-SAFT equation of state for the first time to extend the capabilities of the equation to the calculation of transport properties. The equation was tested with molecular simulations and applied to the family of n-alkanes. The capability of the soft-SAFT + FVT treatment is extended here to other chemical families and mixtures. The compositional rules of Wilke (Wilke, C. R. J. Chem. Phys. 1950, 18, 517-519) are used for the diluted term of the viscosity, while the dense term is evaluated using very simple mixing rules to calculate the viscosity parameters. The theory is then used to predict the vapor-liquid equilibrium and the viscosity of mixtures of nonassociating and associating compounds. The approach is applied to determine the viscosity of a selected group of hydrofluorocarbons, in a similar manner as previously done for n-alkanes. The soft-SAFT molecular parameters are taken from a previous work, fitted to vapor-liquid equilibria experimental data. The application of FVT requires three additional parameters related to the viscosity of the pure fluid. Using a transferable approach, the ? parameter is taken from the equivalent n-alkane, while the remaining two parameters B and Lv are fitted to viscosity data of the pure fluid at several isobars. The effect of these parameters is then investigated and compared to those obtained for n-alkanes, in order to better understand their effect on the calculations. Once the pure fluids are well characterized, the vapor-liquid equilibrium and the viscosity of nonassociating and associating mixtures, including n-alkane + n-alkane, hydrofluorocarbon + hydrofluorocarbon, and n-alkane + hydrofluorocarbon mixtures, are calculated. One or two binary parameters are used to account for deviations in the vapor-liquid equilibrium diagram for nonideal mixtures; these parameters are used in a transferable manner to predict the viscosity of the mixtures. Very good agreement with available experimental data is found in all cases, with an average absolute deviation ranging between 1.0% and 5.5%, even when the system presents azeotropy, reinforcing the robustness of the approach. PMID:23566079

Llovell, F; Marcos, R M; Vega, L F

2013-05-01

379

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

380

Bifurcations of equilibrium sets in mechanical systems with dry friction

NASA Astrophysics Data System (ADS)

The presence of dry friction in mechanical systems induces the existence of an equilibrium set, consisting of infinitely many equilibrium points. The local dynamics of the trajectories near an equilibrium set is investigated for systems with one frictional interface. In this case, the equilibrium set will be an interval of a curve in phase space. It is shown in this paper that local bifurcations of equilibrium sets occur near the endpoints of this curve. Based on this result, sufficient conditions for structural stability of equilibrium sets in planar systems are given, and two new bifurcations are identified. The results are illustrated by application to a controlled mechanical system with friction.

Biemond, J. J. Benjamin; van de Wouw, Nathan; Nijmeijer, Henk

2012-11-01

381

General equilibrium incidence of energy taxation

The pervasiveness of energy in the economy and the numerous ways in which energy taxation can distort resource allocations implies the necessity of a general equilibrium approach to the question of energy tax incidence. The author presents a general equilibrium model that accounts for domestic energy production and energy imports, direct energy consumption and use of energy as an intermediate good, and production of energy intensive and nonenergy intensive goods. He examines the incidence of three broadly-based energy taxation policies: a tax on all energy consumption, a subsidy to domestic energy production, and a tariff on energy imports. The subsidy, although not a revenue raising measure, is included because, like the other policies, it acts to reduce energy imports. Such a measure may be of interest by reducing reliance on unstable foreign sources of supply. 12 references, 3 tables.

Solow, J.L.

1984-04-01

382

Fluctuation theorem for constrained equilibrium systems.

We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as isokinetic and Nosé-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless, finite-time averages of the phase-space contraction rate have nontrivial fluctuations which we show satisfy a simple version of the Gallavotti-Cohen fluctuation theorem, complementary to the usual fluctuation theorem for nonequilibrium stationary states and appropriate to constrained equilibrium states. Moreover, we show that these fluctuations are distributed according to a Gaussian curve for long enough times. Three different systems are considered here: namely, (i) a fluid composed of particles interacting with Lennard-Jones potentials, (ii) a harmonic oscillator with Nosé-Hoover thermostatting, and (iii) a simple hyperbolic two-dimensional map. PMID:16605412

Gilbert, Thomas; Dorfman, J Robert

2006-02-01

383

Uncertainty Principle Consequences at Thermal Equilibrium

Contrary to the conventional wisdom that deviations from standard thermodynamics originate from the strong coupling to the bath, it is shown that these deviations are intimately linked to the power spectrum of the thermal bath. Specifically, it is shown that the lower bound of the dispersion of the total energy of the system, imposed by the uncertainty principle, is dominated by the bath power spectrum and therefore, quantum mechanics inhibits the system thermal-equilibrium-state from being described by the canonical Boltzmann's distribution. This is in sharp contrast to the classical case, for which the thermal equilibrium distribution of a system interacting via central forces with pairwise-self-interacting environment, irrespective of the interaction strength, is shown to be \\emph{exactly} characterized by the canonical Boltzmann distribution. As a consequence of this analysis, we define an \\emph{effective coupling} to the environment that depends on all energy scales in the system and reservoir interactio...

Pachon, Leonardo A; Zueco, David; Brumer, Paul

2014-01-01

384

Equilibrium statistical mechanics for incomplete nonextensive statistics

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

385

The Physics Classroom: Equilibrium and Statics

NSDL National Science Digital Library

This website, by Tom Henderson of Glenbrook South High School, offers a lesson explaining statics and equilibrium. It is the third in a unit on Forces in Two Dimensions and the previous lessons can be found on the left hand side of the page. Graphs, figures, and images are dispersed throughout the lesson to facilitate comprehension along with a quiz at the end to assess student understanding.

Henderson, Tom

2008-06-10

386

Well-posedness for vector equilibrium problems

We introduce and study two notions of well-posedness for vector equilibrium problems in topological vector spaces; they arise\\u000a from the well-posedness concepts previously introduced by the same authors in the scalar case, and provide an extension of\\u000a similar definitions for vector optimization problems. The first notion is linked to the behaviour of suitable maximizing sequences,\\u000a while the second one is

M. Bianchi; G. Kassay; R. Pini

2009-01-01

387

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

388

Noncircular, finite aspect ratio, local equilibrium model

A tokamak equilibrium model, local to a flux surface, is introduced which is completely described in terms of nine parameters including aspect ratio, elongation, triangularity, and safety factor. By allowing controlled variation of each of these nine parameters, the model is particularly suitable for localized stability studies such as those carried out using the ballooning mode representation of the gyrokinetic equations. {copyright} {ital 1998 American Institute of Physics.}

Miller, R.L.; Chu, M.S.; Greene, J.M.; Lin-Liu, Y.R.; Waltz, R.E. [General Atomics, San Diego, California92186-5608 (United States)] [General Atomics, San Diego, California92186-5608 (United States)

1998-04-01

389

Non-equilibrium current via geometric scatterers

NASA Astrophysics Data System (ADS)

We investigate non-equilibrium particle transport in a system consisting of a geometric scatterer and two leads coupled to heat baths with different chemical potentials. We derive an expression for the corresponding current, the carriers of which are fermions, and analyze numerically its dependence on the model parameters in examples where the scatterer has a rectangular or triangular shape. Dedicated to the memory of Markus Büttiker (1950-2013).

Exner, Pavel; Neidhardt, Hagen; Tater, Miloš; Zagrebnov, Valentin A.

2014-10-01

390

Analysis on the forward market equilibrium model

We establish the existence results for the Allaz–Vila [B. Allaz, J.-L. Vila, Cournot competition, forward markets and efficiency, J. Econ. Theory 59 (1993) 1–16] forward market equilibrium model when the M producers have different linear cost functions. We also consider an example with three asymmetric producers. The computational results supplement the conclusion in that the forward trading would increase market

Che-lin Su

2007-01-01

391

Reflective equilibrium and the 'moral conservatism' objection

about particular moral conclusions than we are about why they arc correct. " However, casuistry has its limits. Because it is a bottom-up ?ts approach, it seems to be rooted in cultural bias and popular opinion. (It will become apparent that, because... of this problem, casuistry, like reflective equilibrium, also suffers from the moral conservatism objection. ) In the linc-drawing exercise above, the paradigm case of permissible or impermissible is taken from what is culturally acceptable. More fundamentally...

Chandler, James Robert

2012-06-07

392

Equilibrium of Twisted Horizontal Magnetic Flux Tubes

The equilibrium of non-force-free twisted horizontal magnetic flux tubes is studied including gravity and an arbitrary pressure perturbation on the tube boundary. To solve this free-boundary problem, we use general nonorthogonal flux coordinates and consider the two-dimensional case in which there is no variation of the physical quantities along the tube axis. For the applications in the convection zone and

T. Emonet; F. Moreno-Insertis

1996-01-01

393

Equilibrium Measures for Maps with Inducing Schemes

We introduce a class of continuous maps f of a compact metric space I admitting inducing schemes and describe the tower constructions associated with them. We then establish a thermodynamical formalism, i.e., describe a class of real-valued potential functions \\\\phi on I which admit unique equilibrium measures \\\\mu_\\\\phi minimizing the free energy for a certain class of measures. We also

Yakov Pesin; Samuel Senti

2006-01-01

394

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

395

Statistical approach to partial equilibrium analysis

NASA Astrophysics Data System (ADS)

A statistical approach to market equilibrium and efficiency analysis is proposed in this paper. One factor that governs the exchange decisions of traders in a market, named willingness price, is highlighted and constitutes the whole theory. The supply and demand functions are formulated as the distributions of corresponding willing exchange over the willingness price. The laws of supply and demand can be derived directly from these distributions. The characteristics of excess demand function are analyzed and the necessary conditions for the existence and uniqueness of equilibrium point of the market are specified. The rationing rates of buyers and sellers are introduced to describe the ratio of realized exchange to willing exchange, and their dependence on the market price is studied in the cases of shortage and surplus. The realized market surplus, which is the criterion of market efficiency, can be written as a function of the distributions of willing exchange and the rationing rates. With this approach we can strictly prove that a market is efficient in the state of equilibrium.

Wang, Yougui; Stanley, H. E.

2009-04-01

396

Equilibrium Gold Nanoclusters Quenched with Biodegradable Polymers

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

397

Binary Neutron Stars in Quasi-equilibrium

Quasi-equilibrium sequences of binary neutron stars are constructed for a variety of equations of state in general relativity. Einstein's constraint equations in the Isenberg-Wilson-Mathews approximation are solved together with the relativistic equations of hydrostationary equilibrium under the assumption of irrotational flow. We focus on unequal-mass sequences as well as equal-mass sequences, and compare those results. We investigate the behavior of the binding energy and total angular momentum along a quasi-equilibrium sequence, the endpoint of sequences, and the orbital angular velocity as a function of time, changing the mass ratio, the total mass of the binary system, and the equation of state of a neutron star. It is found that the orbital angular velocity at the mass-shedding limit can be determined by an empirical formula derived from an analytic estimation. We also provide tables for 160 sequences which will be useful as a guideline of numerical simulations for the inspiral and merger performed in the near future.

Keisuke Taniguchi; Masaru Shibata

2010-05-06

398

Out-of-equilibrium electromagnetic radiation

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

2003-10-03

399

Scaling studies of spheromak formation and equilibrium

Formation and equilibrium studies have been performed on the Swarthmore Spheromak Experiment (SSX). Spheromaks are formed with a magnetized coaxial plasma gun and equilibrium is established in both small (d{sub small}=0.16 m) and large (d{sub large}=3d{sub small}=0.50 m) copper flux conservers. Using magnetic probe arrays it has been verified that spheromak formation is governed solely by gun physics (in particular the ratio of gun current to flux, {mu}{sub 0}I{sub gun}/{Phi}{sub gun}) and is independent of the flux conserver dimensions. It has also been verified that equilibrium is well described by the force free condition {nabla}{times}{bold B}={lambda}{bold B} ({lambda}=constant), particularly early in decay. Departures from the force-free state are due to current profile effects described by a quadratic function {lambda}={lambda}({psi}). Force-free SSX spheromaks will be merged to study magnetic reconnection in simple magnetofluid structures. {copyright} {ital 1998 American Institute of Physics.}

Geddes, C.G.; Kornack, T.W.; Brown, M.R. [Department of Physics and Astronomy, Swarthmore College, Swarthmore, Pennsylvania19081-1397 (United States)] [Department of Physics and Astronomy, Swarthmore College, Swarthmore, Pennsylvania19081-1397 (United States)

1998-04-01

400

401

Transport and equilibrium in molecular plasmas: the sulfur lamp

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

402

On Intersectoral Asymmetries in Factors Substitutability, Equilibrium Production Possibility Centre National de la Recherche Scientifique #12; Abstract The existence of asymmetries in factors to equilibrium factors costs and outputs prices. The generality of the current approach and the genericity

Paris-Sud XI, UniversitÃ© de

403

Quantum Hypothesis Testing Non-Equilibrium Statistical Mechanics

Quantum Hypothesis Testing and Non-Equilibrium Statistical Mechanics V. JaksiÂ´c1 , Y. Ogata2 , C with recent developments in non-equilibrium quantum statistical mechanics. In particular, we relate the large

Boyer, Edmond

404

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

405

Multiplicity in General Financial Equilibrium with Portfolio Constraints

This paper explores the role of portfolio constraints in generating multiplicity of equilibrium. We present a simple financial market economy with two goods and two households, households who face constraints on their ability to take unbounded positions in risky stocks. Absent such constraints, equilibrium allocation is unique and is Pareto efficient. With one portfolio constraint in place, the efficient equilibrium

Suleyman Basak; David Cass; Juan Manuel Licari; Anna Pavlova

2006-01-01

406

Multiplicity in General Financial Equilibrium with Portfolio Constraints, Second Version

This paper explores the role of portfolio constraints in generating multiplicity of equilibrium. We present a simple financial market economy with two goods and two households, households who face constraints on their ability to take unbounded positions in risky stocks. Absent such constraints, equilibrium allocation is unique and is Pareto efficient. With one portfolio constraint in place, the efficient equilibrium

Suleyman Basak; David Cass; Juan Manuel Licari; Anna Pavlova

2006-01-01

407

Multiplicity in general financial equilibrium with portfolio constraints

This paper explores the role of portfolio constraints in generating multiplicity of equilibrium. We present a simple financial market economy with two goods and two households, households who face constraints on their ability to take unbounded positions in risky stocks. Absent such constraints, equilibrium allocation is unique and is Pareto efficient. With one portfolio constraint in place, the efficient equilibrium

Suleyman Basak; David Cass; Juan Manuel Licari; Anna Pavlova

2008-01-01

408

SORPTION EQUILIBRIUM MOISTURE CHARACTERISTICS OF SELECTED CORN STOVER COMPONENTS

Corn stover equilibrium moisture isotherms were developed to aide biomass engineering of consistent, uniform-quality feedstock supplies for renewable bioenergy and bioproducts. Equilibrium moisture content (EMC) and equilibrium relative humidity (ERH) sorption data of corn leaf, stalk skin, and stalk pith were experimentally determined using the static gravimetric method at six temperatures ranging from 10°C to 40°C and at ten ERH

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

409

Equilibrium-independent passivity: a new definition and implications

We extend the traditional notion of passivity to a forced system whose equilibrium is nontrivially dependent on the control input by defining equilibrium-independent passivity, a system property characterized by a dissipation inequality centered at an arbitrary equilibrium point. We also provide input\\/output tests to certify this property which can be performed analytically or empirically. An example from network stability analysis

George H. Hines; Murat Arcak; Andrew K. Packard

2010-01-01

410

Equilibrium-independent passivity: A new definition and numerical certification

We extend the traditional notion of passivity to a forced system whose equilibrium is dependent on the control input by defining equilibrium-independent passivity, a system property characterized by a dissipation inequality centered at an arbitrary equilibrium point. We provide a necessary input\\/output condition which can be tested for systems of arbitrary dimension and sufficient conditions to certify this property for

George H. Hines; Murat Arcak; Andrew K. Packard

2011-01-01

411

Lorenz equilibrium: equitability in non-cooperative games

The most popular solution concept in game theory, Nash equilibrium, has some limitations when applied to real life problems. Nash equilibrium rarely assures maximal payoff. A possibility is to consider Pareto equilibrium, inspired from the standard solution concept in multi-criteria optimization, but the obtained equilibria often consists of a large set of solutions that is too hard to process. Our

Réka Nagy; Mihai Alexandru Suciu; D. Dumitrescu

2012-01-01

412

(Quantum) chaos theory and statistical physics far from equilibrium

(Quantum) chaos theory and statistical physics far from equilibrium: Introducing the group for Non-equilibrium quantum and statistical physics Tomaz Prosen Department of physics, Faculty of mathematics and physics, University of Ljubljana July, 2011 Tomaz Prosen Non-equilibrium quantum and statistical physics group #12

Â?umer, Slobodan

413

Equilibrium motion of unbalanced dual-spin spacecraft

The force free motion of a dual-spin spacecraft, with mass unbalance and internal energy dissipation in the main body, is studied. The exact equations of motion are solved for the steady state motion, often referred to as equilibrium motion or equilibrium point, reached asymptotically when the internal energy dissipation ceases. The solution indicates that at equilibrium the cone angle and

A. Sitchin; J. M. Vance

1975-01-01

414

EQUILIBRIUM PATHS OF MECHANICAL SYSTEMS WITH UNILATERAL CONSTRAINTS

in structural mechanics is the determination of the static equilibrium path of a structure for varying valuesEQUILIBRIUM PATHS OF MECHANICAL SYSTEMS WITH UNILATERAL CONSTRAINTS PART I: THEORY M. Schulz and S theoretical formulation is required for simulating their behaviour. After showing that the equilibrium

Pellegrino, Sergio

415

Eulerian and Lagrangian pictures of non-equilibrium diffusions

We show that a non-equilibrium diffusive dynamics in a finite-dimensional space takes in the Lagrangian frame of its mean local velocity an equilibrium form with the detailed balance property. This explains the equilibrium nature of the fluctuation-dissipation relations in that frame observed previously. The general considerations are illustrated on few examples of stochastic particle dynamics.

Raphael Chetrite; Krzysztof Gawedzki

2009-05-28

416

Modeling Equilibrium Moisture Content of ?-Ray Irradiated Rough Rice

Experimental studies show that gamma irradiation dose affects the values of equilibrium moisture content of grain at the same relative humidity and temperature of ambient. Values of the equilibrium moisture content decreased with increasing dose of ?-ray irradiation during both adsorption and desorption. Factor of irradiation dose was included in three widely used models for equilibrium moisture content; the parameters

Y. Yu; J. Wang

2006-01-01

417

Trapped nonneutral plasmas, liquids, and crystals (the thermal equilibrium states)

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

418

Equilibrium time correlation functions and the dynamics of fluctuations

NASA Astrophysics Data System (ADS)

Equilibrium time correlation functions are of great importance because they probe the equilibrium dynamical response to external perturbations. We discuss the properties of time correlation functions for several systems that are simple enough to illustrate the calculational steps involved. The discussion underscores the need for avoiding language which misleadingly suggests that thermal equilibrium is associated with a quiescent or moribund state of the system.

Luban, Marshall; Luscombe, James H.

1999-12-01

419

Towards breaking temperature equilibrium in multi-component Eulerian schemes

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

420

Hanging an Airplane: A Case Study in Static Equilibrium

ERIC Educational Resources Information Center

Our classrooms are filled with engineering majors who take a semester-long course in static equilibrium. Many students find this class too challenging and drop their engineering major. In our introductory physics class, we often breeze through static equilibrium; to physicists equilibrium is just a special case of Newton's second law. While it is…

Katz, Debora M.

2009-01-01

421

Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium

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

422

Substantial evidence has accumulated in recent empirical works on the limited ability of the Nash equilibrium to rationalize observed behavior in many classes of games played by experimental subjects. This realization has led to several attempts aimed at finding tractable equilibrium concepts which perform better empirically; one such example is the impulse balance equilibrium (Selten, Chmura, 2008), which introduces a

Alessandro Tavoni

2009-01-01

423

Multicomponent Equilibrium Models for Testing Geothermometry Approaches

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

424

Process for operating equilibrium controlled reactions

A cyclic process for operating an equilibrium controlled reaction in a plurality of reactors containing an admixture of an adsorbent and a reaction catalyst suitable for performing the desired reaction which is operated in a predetermined timed sequence wherein the heating and cooling requirements in a moving reaction mass transfer zone within each reactor are provided by indirect heat exchange with a fluid capable of phase change at temperatures maintained in each reactor during sorpreaction, depressurization, purging and pressurization steps during each process cycle.

Nataraj, Shankar (Allentown, PA); Carvill, Brian Thomas (Orefield, PA); Hufton, Jeffrey Raymond (Fogelsville, PA); Mayorga, Steven Gerard (Allentown, PA); Gaffney, Thomas Richard (Allentown, PA); Brzozowski, Jeffrey Richard (Bethlehem, PA)

2001-01-01

425

The canonical equilibrium of constrained molecular models

NASA Astrophysics Data System (ADS)

In order to increase the efficiency of the computer simulation of biological molecules, it is very common to impose holonomic constraints on the fastest degrees of freedom; normally bond lengths, but also possibly bond angles. Since the maximum time step required for the stability of the dynamics is proportional to the shortest period associated with the motions of the system, constraining the fastest vibrations allows to increase it and, assuming that the added numerical cost is not too high, also increase the overall efficiency of the simulation. However, as any other element that affects the physical model, the imposition of constraints must be assessed from the point of view of accuracy: both the dynamics and the equilibrium statistical mechanics are model-dependent, and they will be changed if constraints are used. In this review, we investigate the accuracy of constrained models at the level of the equilibrium statistical mechanics distributions produced by the different dynamics. We carefully derive the canonical equilibrium distributions of both the constrained and unconstrained dynamics, comparing the two of them by means of a "stiff" approximation to the latter. We do so both in the case of flexible and hard constraints, i.e., when the value of the constrained coordinates depends on the conformation and when it is a constant number. We obtain the different correcting terms associated with the kinetic energy mass-metric tensor determinants, but also with the details of the potential energy in the vicinity of the constrained subspace (encoded in its first and second derivatives). This allows us to directly compare, at the conformational level, how the imposition of constraints changes the thermal equilibrium of molecular systems with respect to the unconstrained case. We also provide an extensive review of the relevant literature, and we show that all models previously reported can be considered special cases of the most general treatments presented in this work. Finally, we numerically analyze a simple methanol molecule in order to illustrate the theoretical concepts in a practical case.

Echenique, P.; Cavasotto, C. N.; García-Risueño, P.

2011-11-01

426

A non-equilibrium quantum Landauer principle

Using the operational framework of completely positive, trace preserving operations and thermodynamic fluctuation relations, we derive a lower bound for the heat exchange in a Landauer erasure process on a quantum system. Our bound comes from a non-phenomenological derivation of the Landauer principle which holds for generic non-equilibrium dynamics. Furthermore the bound depends on the non-unitality of dynamics, giving it a physical significance. We apply our framework to the model of a spin-1/2 system coupled to an interacting spin chain at finite temperature.

John Goold; Mauro Paternostro; Kavan Modi

2014-02-18

427

Modeling Equilibrium Clusters in Lysozyme Solutions

We present a combined experimental and numerical study of the equilibrium cluster formation in globular protein solutions under no-added salt conditions. We show that a cluster phase emerges as a result of a competition between a long-range screened Coulomb repulsion and a short-range attraction. A simple effective potential, in which only depth and width of the attractive part of the potential are optimized, accounts in a remarkable way for the wavevector dependence of the X-ray scattering structure factor.

Frédéric Cardinaux; Anna Stradner; Peter Schurtenberger; Francesco Sciortino; Emanuela Zaccarelli

2006-07-11

428

Non-equilibrium Dynamics of DNA Nanotubes

NASA Astrophysics Data System (ADS)

Can the fundamental processes that underlie molecular biology be understood and simulated by DNA nanotechnology? The early development of DNA nanotechnology by Ned Seeman was driven by the desire to find a solution to the protein crystallization problem. Much of the later development of the field was also driven by envisioned applications in computing and nanofabrication. While the DNA nanotechnology community has assembled a versatile tool kit with which DNA nanostructures of considerable complexity can be assembled, the application of this tool kit to other areas of science and technology is still in its infancy. This dissertation reports on the construction of non-equilibrium DNA nanotube dynamic to probe molecular processes in the areas of hydrodynamics and cytoskeletal behavior. As the first example, we used DNA nanotubes as a molecular probe for elongational flow measurement in different micro-scale flow settings. The hydrodynamic flow in the vicinity of simple geometrical objects, such as a rigid DNA nanotube, is amenable to rigorous theoretical investigation. We measured the distribution of elongational flows produced in progressively more complex settings, ranging from the vicinity of an orifice in a microfluidic chamber to within a bursting bubble of Pacific ocean water. This information can be used to constrain theories on the origin of life in which replication involves a hydrodynamically driven fission process, such as the coacervate fission proposed by Oparin. A second theme of this dissertation is the bottom-up construction of a de novo artificial cytoskeleton with DNA nanotubes. The work reported here encompasses structural, locomotion, and control aspects of non-equilibrium cytoskeletal behavior. We first measured the kinetic parameters of DNA nanotube assembly and tested the accuracy of the existing polymerization models in the literature. Toward recapitulation of non-equilibrium cytoskeletal dynamics, we coupled the polymerization of DNA nanotubes with an irreversible energy consumption reaction, analogous to nucleotide hydrolysis in actin and microtubule polymerization. Finally, we integrated the DNA strand displacement circuits with DNA nanotube polymerization to achieve programmable kinetic control of behavior within artificial cytoskeleton. Our synthetic approach may provide insights into natural cytoskeleton dynamics, such as minimal architectural or reaction mechanism requirements for non-equilibrium behaviors including treadmilling and dynamic instability. The outgrowth of DNA nanotechnology beyond its own boundaries, serving as a general model system for biomolecular dynamics, can lead to an understanding of molecular processes that advances both basic and applied sciences.

Hariadi, Rizal Fajar

429

NASA Astrophysics Data System (ADS)

Spatial coherence of thermal fields in far- and near-field zones generated by heated half-space into vacuum is studied at essentially different thermodynamical conditions. It is shown that correlation lengths of fields in any field zone are different in equilibrium and out of equilibrium systems. In wide range of distances from sample surface correlation functions are should be calculated using a total sum of evanescent and propagating contributions due to their mutual compensation at some conditions because of anticorrelations. It is demonstrated that correlation lengths as calculated with a proposed formula are in agreement with a behavior of correlation functions of thermal fields in spectral range of surface excitations

Dorofeyev, Illarion

2014-11-01

430

Hydrologic controls on equilibrium soil depths

NASA Astrophysics Data System (ADS)

This paper deals with modeling the mutual feedbacks between runoff production and geomorphological processes and attributes that lead to patterns of equilibrium soil depth. Our primary goal is an attempt to describe spatial patterns of soil depth resulting from long-term interactions between hydrologic forcings and soil production, erosion, and sediment transport processes under the framework of landscape dynamic equilibrium. Another goal is to set the premises for exploiting the role of soil depths in shaping the hydrologic response of a catchment. The relevance of the study stems from the massive improvement in hydrologic predictions for ungauged basins that would be achieved by using directly soil depths derived from geomorphic features remotely measured and objectively manipulated. Hydrological processes are here described by explicitly accounting for local soil depths and detailed catchment topography. Geomorphological processes are described by means of well-studied geomorphic transport laws. The modeling approach is applied to the semiarid Dry Creek Experimental Watershed, located near Boise, Idaho. Modeled soil depths are compared with field data obtained from an extensive survey of the catchment. Our results show the ability of the model to describe properly the mean soil depth and the broad features of the distribution of measured data. However, local comparisons show significant scatter whose origins are discussed.

Nicótina, L.; Tarboton, D. G.; Tesfa, T. K.; Rinaldo, A.

2011-04-01

431

Globally convergent computation of chemical equilibrium composition.

We report the Newton-Raphson based globally convergent computational method for determination of chemical equilibrium composition. In the computation of chemical equilibrium composition, an appearance of nonpositive value of number of moles of any component leads to discrepancy. The process of conditional backtracking and adaptive set of refining factors for Newton-Raphson steps are employed to resolve the problem. The mathematical formulation proposed by Heuze et al. (J Chem Phys 1985, 83, 4734) has been solved using proposed computational method, instead of empirical iterative formulation, as proposed by them. Results for the same numerical example, used by Heuze et al. (J Chem Phys 1985, 83, 4734) and White et al. (J Chem Phys 1958, 28, 751) are presented in addition to decomposition of Cyclotrimethylenetrinitramine for fixed temperature and pressure. It is observed that the proposed method is efficient and globally convergent. An even noteworthy finding is that the set of refining factors can be chosen from the range 0.1 to eta, where eta may be greater than one depending on how smoothly system of nonlinear equations is dependant on corresponding variable. Related analysis and results are discussed. PMID:18161685

Patil, Sunil; Aiyer, R C; Sharma, K C

2008-05-01

432

Structural design using equilibrium programming formulations

NASA Technical Reports Server (NTRS)

Solutions to increasingly larger structural optimization problems are desired. However, computational resources are strained to meet this need. New methods will be required to solve increasingly larger problems. The present approaches to solving large-scale problems involve approximations for the constraints of structural optimization problems and/or decomposition of the problem into multiple subproblems that can be solved in parallel. An area of game theory, equilibrium programming (also known as noncooperative game theory), can be used to unify these existing approaches from a theoretical point of view (considering the existence and optimality of solutions), and be used as a framework for the development of new methods for solving large-scale optimization problems. Equilibrium programming theory is described, and existing design techniques such as fully stressed design and constraint approximations are shown to fit within its framework. Two new structural design formulations are also derived. The first new formulation is another approximation technique which is a general updating scheme for the sensitivity derivatives of design constraints. The second new formulation uses a substructure-based decomposition of the structure for analysis and sensitivity calculations. Significant computational benefits of the new formulations compared with a conventional method are demonstrated.

Scotti, Stephen J.

1995-01-01

433

Equilibrium dynamics of spin-glass systems

We present a critical analysis of the Sompolinsky theory of equilibrium dynamics. By using the spherical 2+p spin-glass model we test the asymptotic static limit of the Sompolinsky solution showing that it fails to yield a thermodynamically stable solution. We then present an alternative formulation, based on the Crisanti, Hoerner, and Sommers [Z. Phys. B: Condens. Matter 92, 257 (1993)] dynamical solution of the spherical p-spin spin-glass model, reproducing a stable static limit that coincides, in the case of a one step replica symmetry breaking ansatz, with the solution at the dynamic free energy threshold at which the relaxing system gets stuck off equilibrium. We formally extend our analysis to any number of replica symmetry breakings R. In the limit R{yields}{infinity}, both formulations lead to the Parisi antiparabolic differential equation. This is the special case, though, where no dynamic blocking threshold occurs. The formulation does not contain the additional order parameter {delta} of the Sompolinsky theory.

Crisanti, A.; Leuzzi, L. [Dipartimento di Fisica, Universita di Roma 'La Sapienza', Istituto Nazionale Fisica della Materia, Unita di Roma, Rome (Italy); SMC, P.le Aldo Moro 2, I-00185 Rome (Italy); Istituto Studi della Complessita (ISC), CNR, Via dei Taurini 19, I-00185 Rome (Italy)

2007-04-01

434

Theory of charged dust clouds: Equilibrium

Gravitational equilibria of low density dust clouds imbedded in plasma background are studied. These are a new class of astrophysical objects, in which the electric field in quasineutral plasma balances the self-gravity of the dust. Heuristic arguments based on the total potential energy of a uniform dust ball are given for the existence of stable equilibrium and the mass limit for the maximum dust mass M{sub AS}, which can be supported against its self-gravity. The gravitational collapse is initiated by the destabilization of the fundamental radial mode as the mass of the dust cloud M{sub D}{yields}M{sub AS}. The physics of the mass limit is similar to the Chandrasekhar's mass limit for compact objects. One parameter family of spherically symmetric, static solutions of radius R ({approx_equal}0.1 AU) and the total mass of the dust cloud M{sub D} ({approx_equal}10{sup 19} g), for given central dust density, are constructed. A finite flux of photoelectrons is shown to decrease R and M{sub D}. Two-dimensional rotating dust disk equilibrium, characterized by a sharp and diffuse boundary, is also constructed. These dust equilibria (spherical clouds, rotating disks), which are predicted to be within the interstellar clouds, could be relevant for planet formation, as they provide locations where a significant quantity of dust can be stably trapped. The accretion and coagulation interaction between these trapped dust grains may lead to planet formation.

Avinash, K. [Department of Physics and Astrophysics, University of Delhi, Delhi - 7 (India)

2007-01-15

435

Uncertainty Principle Consequences at Thermal Equilibrium

Contrary to the conventional wisdom that deviations from standard thermodynamics originate from the strong coupling to the bath, it is shown that these deviations are intimately linked to the power spectrum of the thermal bath. Specifically, it is shown that the lower bound of the dispersion of the total energy of the system, imposed by the uncertainty principle, is dominated by the bath power spectrum and therefore, quantum mechanics inhibits the system thermal-equilibrium-state from being described by the canonical Boltzmann's distribution. This is in sharp contrast to the classical case, for which the thermal equilibrium distribution of a system interacting via central forces with pairwise-self-interacting environment, irrespective of the interaction strength, is shown to be \\emph{exactly} characterized by the canonical Boltzmann distribution. As a consequence of this analysis, we define an \\emph{effective coupling} to the environment that depends on all energy scales in the system and reservoir interaction. Sample computations in regimes predicted by this effective coupling are demonstrated. For example, for the case of strong effective coupling, deviations from standard thermodynamics are present and, for the case of weak effective coupling, quantum features such as stationary entanglement are possible at high temperatures.

Leonardo A. Pachon; Johan F. Triana; David Zueco; Paul Brumer

2014-01-07

436

Symmetries in fluctuations far from equilibrium.

Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager's reciprocity relations and Green-Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields. PMID:21493865

Hurtado, Pablo I; Pérez-Espigares, Carlos; del Pozo, Jesús J; Garrido, Pedro L

2011-05-10

437

Equilibrium stellar systems with spindle singularities

NASA Technical Reports Server (NTRS)

Equilibrium sequences of axisymmetric Newtonian clusters that tend toward singular states are constructed. The distribution functions are chosen to be of the form f = f(E, Jz). The numerical method then determines the density and gravitational potential self-consistently to satisfy Poisson's equation. For the prolate models, spindle singularities arise from the depletion of angular momentum near the symmetry axis. While the resulting density enhancement is confined to the region near the axis, the influence of the spindle extends much further out through its tidal gravitational field. Centrally condensed prolate clusters may contain strong-field regions even though the spindle mass is small and the mean cluster eccentricity is not extreme. While the calculations performed here are entirely Newtonian, the issue of singularities is an important topic in general relativity. Equilibrium solutions for relativistic star clusters can provide a testing ground for exploring this issue. The methods used in this paper for building nonspherical clusters can be extended to relativistic systems.

Shapiro, Stuart L.; Teukolsky, Saul A.

1992-01-01

438

Form factors in equilibrium and non-equilibrium mixed states of the Ising model

NASA Astrophysics Data System (ADS)

Using the ‘Liouville space’ (the space of operators) of the massive Ising model of quantum field theory, there is a natural definition of form factors in any mixed state. These generalize the usual form factors, and are building blocks for mixed-state correlation functions. We study the cases of mixed states that are diagonal in the asymptotic particle basis, and obtain exact expressions for all mixed-state form factors of order and disorder fields. We use novel techniques based on deriving and solving a system of non-linear functional differential equations. We then write down the full form factor expansion for mixed-state correlation functions of these fields. Under weak analytic conditions on the eigenvalues of the density matrix, this is an exact large-distance expansion. The form factors agree with the known finite-temperature form factors when the mixed state is specialized to a thermal Gibbs ensemble. Our results can be used to analyze correlation functions in generalized Gibbs ensembles (which occur after quantum quenches). Applying this to the density matrix for non-equilibrium steady states with energy flows, we observe that non-equilibrium form factors have branch cuts in rapidity space. We verify that this is in agreement with a non-equilibrium generalization of the KMS relations, and we conjecture that the leading large-distance behavior of order and disorder non-equilibrium correlation functions contains oscillations in the log of the distance between the fields.

Chen, Yixiong; Doyon, Benjamin

2014-09-01

439

Radiative equilibrium model of Titan's atmosphere

NASA Technical Reports Server (NTRS)

The present global radiative equilibrium model for the Saturn satellite Titan is restricted to the two-stream approximation, is vertically homogeneous in its scattering properties, and is spectrally divided into one thermal and two solar channels. Between 13 and 33% of the total incident solar radiation is absorbed at the planetary surface, and the 30-60 ratio of violet to thermal IR absorption cross sections in the stratosphere leads to the large temperature inversion observed there. The spectrally integrated mass absorption coefficient at thermal wavelengths is approximately constant throughout the stratosphere, and approximately linear with pressure in the troposphere, implying the presence of a uniformly mixed aerosol in the stratosphere. There also appear to be two regions of enhanced opacity near 30 and 500 mbar.

Samuelson, R. E.

1983-01-01

440

Hall MHD Equilibrium of Accelerated Compact Toroids

NASA Astrophysics Data System (ADS)

We examine the structure and dynamics of the compact toroid's magnetic field. The compact toroid is dramatically accelerated by a large rail-gun Lorentz force density equal to j xB. We use magnetic data from the Compact Toroid Injection Experiment to answer the question of exactly where in the system j xB has nonzero values, and to what extent we can apply the standard model of force-free equilibrium. In particular we present a method of analysis of the magnetic field probe signals that allows direct comparison to the predictions of the Woltjer-Taylor force-free model and Turner's generalization of magnetic relaxation in the presence of a non-zero Hall term and fluid vorticity.

Howard, S. J.; Hwang, D. Q.; Horton, R. D.; Evans, R. W.; Brockington, S. J.

2007-11-01

441

Dynamical evolution of quantum oscillators towards equilibrium

A pure quantum state of large number N of oscillators, interacting via harmonic coupling, evolves such that any small subsystem n<

A R Usha Devi; A K Rajagopal

2009-01-11

442

Punctuated equilibrium dynamics in human communications

A minimal model based on individual interactions is proposed to study the non-Poisson statistical properties of human behavior: individuals in the system interact with their neighbors, the probability of an individual acting correlates to its activity, and all individuals involved in action will change their activities randomly. The model creates rich non-Poisson spatial-temporal properties in the activities of individuals, in agreement with the patterns of human communication behaviors. Our findings provide insight into various human activities, embracing a range of realistic social interacting systems, particularly, intriguing bimodal phenomenons. This model bridges priority queues and punctuated equilibrium, and our modeling and analysis is likely to shed light on non-Poisson phenomena in many complex systems.

Peng, Dan; Wei, Zong-Wen; Wang, Bing-Hong

2014-01-01

443

Equilibrium Clusters in Concentrated Lysozyme Protein Solutions

We have studied the structure of salt-free lysozyme at 293 K and pH 7.8 using molecular simulations and experimental SAXS effective potentials between proteins at three volume fractions, 0.012, 0.033, and 0.12. We found that the structure of lysozyme near physiological conditions strongly depends on the volume fraction of proteins. The studied lysozyme solutions are dominated by monomers only for <0.012; for the strong dilution 70% of proteins are in a form of monomers. For 0.033 only 20% of proteins do not belong to a cluster. The clusters are mainly elongated. For 0.12 almost no individual particles exits, and branched, irregular clusters of large extent appear. Our simulation study provides new insight into the formation of equilibrium clusters in charged protein solutions near physiological conditions.

Kowalczyk, P; Gauden, P A; Terzyk, A P

2011-01-01

444

Equilibrium Clusters in Concentrated Lysozyme Protein Solutions

We have studied the structure of salt-free lysozyme at 293 K and pH 7.8 using molecular simulations and experimental SAXS effective potentials between proteins at three volume fractions, 0.012, 0.033, and 0.12. We found that the structure of lysozyme near physiological conditions strongly depends on the volume fraction of proteins. The studied lysozyme solutions are dominated by monomers only for <0.012; for the strong dilution 70% of proteins are in a form of monomers. For 0.033 only 20% of proteins do not belong to a cluster. The clusters are mainly elongated. For 0.12 almost no individual particles exits, and branched, irregular clusters of large extent appear. Our simulation study provides new insight into the formation of equilibrium clusters in charged protein solutions near physiological conditions.

P. Kowalczyk; A. Ciach; P. A. Gauden; A. P. Terzyk

2011-06-03

445

Renyi statistics in equilibrium statistical mechanics

The Renyi statistics in the canonical and microcanonical ensembles is examined in the general case and in particular for the ideal gas. In the microcanonical ensemble the Renyi statistics is equivalent with the Boltzmann-Gibbs statistics. By the exact analytical results for the ideal gas, it is shown that in the canonical ensemble in the thermodynamic limit the Renyi statistics is also equivalent with the Boltzmann-Gibbs statistics. Furthermore it satisfies the requirements of the equilibrium thermodynamics, i.e. the thermodynamical potential of the statistical ensemble is a homogeneous function of degree 1 of its extensive variables of state. We conclude that the Renyi statistics duplicates the thermodynamical relations stemming from the Boltzmann-Gibbs statistics in the thermodynamical limit.

A. S. Parvan; T. S. Biro

2009-10-16

446

Thermal equilibrium of two quantum Brownian particles

The influence of the environment in the thermal equilibrium properties of a bipartite continuous variable quantum system is studied. The problem is treated within a system-plus-reservoir approach. The considered model reproduces the Brownian motion when the two particles are isolated and induces an effective interaction between them, depending on the choice of the spectral function of the bath. The coupling between the system and the environment guarantees the translational invariance of the system in the absence of an external potential. The entanglement between the particles is measured by the logarithmic negativity, which is shown to monotonically decrease with the increase of the temperature. A range of finite temperatures is found in which entanglement is still induced by the reservoir.

Valente, D. M.; Caldeira, A. O. [Departamento de Fisica da Materia Condensada, Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, CEP 13083-970, Campinas-SP (Brazil)

2010-01-15

447

Anisotropic pressure tokamak equilibrium and stability considerations

Investigation of the effect of pressure anisotropy on tokamak equilibrium and stability is made with an MHD model. Realistic perpendicular and parallel pressure distributions, P/sub perpendicular/(psi,B) and P/sub parallel/(psi,B), are obtained by solving a one-dimensional Fokker-Planck equation for neutral beam injection to find a distribution function f(E, v/sub parallel//v) at the position of minimum field on each magnetic surface and then using invariance of the magnetic moment to determine its value at each point on the surface. The shift of the surfaces of constant perpendicular and parallel pressure from the flux surfaces depends strongly on the angle of injection. This shift explains the observed increase or decrease in the stability conditions. Estimates of the stabilizing effect of hot trapped ions indicates that a large fraction must be nonresonant and thus decoupled from the bad curvature before it becomes important.

Salberta, E.R.; Grimm, R.C.; Johnson, J.L.; Manickam, J.; Tang, W.M.

1987-02-01

448

Radiation temperature of non-equilibrium plasmas

In fusion devices measurements of the radiation temperature T{sub r} ({omega}, k) near the electron cyclotron frequency {omega}{sub C} and the second harmonic 2{omega}{sub C} in directions nearly perpendicular to the confining magnetic field B (i.e., k {approx} k {perpendicular}) serve to map out the electron temperature profiles T{sub e}(r,t). For optically thick plasma at thermodynamic equilibrium T{sub r} = T{sub e}. However, there is increasing experimental evidence for the presence of non-equilibrium electron distributions (such as a drifting Maxwellian with appreciable values of the streaming parameter {omicron} = v{sub d}/v{sub t}, a bi- Maxwellian, and anisotropic Maxwellian with T {perpendicular} {ne} T {parallel}, etc.,) in tokamak plasmas, especially in the presence of radio-frequency heating. Here, we examine (both non-relativistically and relativistically) the dependence of T{sub r} on {omicron}, T{perpendicular}/T{parallel}, T{sub h}/T{sub b}, n{sub h}/n{sub b}etc., where n{sub b}, n{sub h}, T{sub b}, T{sub h} are the densities and temperatures, respectively, of the bulk and the hot components of the bi-Maxwellian plasma. Our bi-Maxwellian results predict that the ratio T{sub r}/T{sub e} is a very sensitive function of the ratios n{sub h}/n{sub b} and T{sub h}/T{sub b}. Further, these relativistic and non-relativistic results satisfy the well-known limit c {yields} {infinity} correspondence principle'', showing that the intensity of the emission and absorption line is independent of the line broadening mechanism. 44 refs., 2 figs.

Arunasalam, V.

1991-07-01

449

Out-of-Equilibrium Transport near a Quantum Phase Transition

Non-equilibrium properties are expected to be particularly rich at a second order quantum phase transition, given that statics and (imaginary time) dynamics are already mixed at the equilibrium level. The issue has so far received only limited study, partly because equilbrium methods are not readily generalizable to non-equilibrium situations. Here we consider the quantum critical point of a Bose-Fermi Kondo

Stefan Kirchner; Lijun Zhu; Qimiao Si

2005-01-01

450

Equilibrium time correlation functions and the dynamics of fluctuations

Equilibrium time correlation functions are of great importance because they probe the equilibrium dynamical response to external perturbations. We discuss the properties of time correlation functions for several systems that are simple enough to illustrate the calculational steps involved. The discussion underscores the need for avoiding language which misleadingly suggests that thermal equilibrium is associated with a quiescent or moribund state of the system. (c) 1999 American Association of Physics Teachers.

Luban, Marshall [Ames Laboratory and the Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory and the Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Luscombe, James H. [Department of Physics, Naval Postgraduate School, Monterey, California 93943 (United States)] [Department of Physics, Naval Postgraduate School, Monterey, California 93943 (United States)

1999-12-01

451

Recovery factor for non-equilibrium sedimentation processes

Non-equilibrium sediment transport has a significant role on the simulation of reservoir sedimentation as a non-equilibrium process. Two case studies of reservoir sedimentation processes are made in this research using a Bureau of Reclamation computer model. The model is a semi-2D mathematical model for hydraulic simulation and a semi-3D model for morphologic simulation of sedimentation processes. Non-equilibrium sediment transport formula

Chih Ted Yang; Reza Marsooli

2010-01-01

452

Local temperature of out-of-equilibrium quantum electron systems

NASA Astrophysics Data System (ADS)

We show how the local temperature of out-of-equilibrium, quantum electron systems can be consistently defined with the help of an external voltage and temperature probe. We determine sufficient conditions under which the temperature measured by the probe (i) is independent of details of the system-probe coupling, (ii) is equal to the temperature obtained from an independent current-noise measurement, (iii) satisfies the transitivity condition expressed by the zeroth law of thermodynamics, and (iv) is consistent with Carnot's theorem. This local temperature therefore characterizes the system in the common sense of equilibrium thermodynamics, but remains well defined even in out-of-equilibrium situations with no local equilibrium.

Meair, J.; Bergfield, J. P.; Stafford, C. A.; Jacquod, Ph.

2014-07-01

453

Confined colloidal crystals in and out of equilibrium

NASA Astrophysics Data System (ADS)

Recent studies on confined crystals of charged colloidal particles are reviewed, both in equilibrium and out of equilibrium. We focus in particular on direct comparisons of experiments (light scattering and microscopy) with lattice sum calculations and computer simulations. In equilibrium we address buckling and crystalline multilayering of charged systems in hard and soft slit confinement. We discuss also recent crystalline structures obtained for charged mixtures. Moreover we put forward possibilities to apply external perturbations, in order to drive the system out of equilibrium. These include electrolyte gradients as well as the application of shear and electric fields.

Reinmüller, A.; O?uz, E. C.; Messina, R.; Löwen, H.; Schöpe, H. J.; Palberg, T.

2013-11-01

454

Calculation of dehydration absorbers based on improved phase equilibrium data

Dehydration using triethylene glycol (TEG) as an absorbent, is a standard process for natural gas treating. New and more accurate TEG/water equilibrium data have been measured between 1980 and 1990. However, this has not influenced much on the design methods of dehydration absorbers. Inaccurate equilibrium data have been extensively used in design calculations. When using data from a common source like Worley, an overall bubble cap tray efficiency between 25--40% has normally been recommended. This has resulted in a quite satisfactory and consistent design method. It is obvious that newer equilibrium data (Herskowitz, Parrish, Bestani) are more accurate. However, to achieve an improved design method, column efficiencies consistent with the new equilibrium data must be recommended. New equilibrium data have been correlated to an activity coefficient model for the liquid phase and combined with an equation of state for the gas phase. Performance data from the North Sea offshore platform Gullfaks C (drying 4--5 MMscmd) have been measured. The bubble cap column has been simulated, and the tray efficiency has been adjusted to fit the performance data. Tray efficiencies calculated with new equilibrium data are higher than 50%. Calculated tray efficiency values are dependent on the equilibrium data used. There are still uncertainties in equilibrium data for the TEC/water/natural gas system. When using accurate equilibrium data, an overall bubble cap tray efficiency of 40--50% and a Murphree efficiency of 55--70% can be expected at normal absorption conditions.

Oi, L.E.

1999-07-01

455

A representation of the static MHD equilibrium system in coordinates connected with magnetic surfaces is suggested. It is used for producing families of non-trivial 3D exact solutions of isotropic and anisotropic plasma equilibria in different geometries, with and without dynamics, and often without geometrical symmetries. The ways of finding coordinates in which exact equilibria can be constructed are discussed; examples and their applications as physical models are presented.

Alexei F. Cheviakov

2004-10-19

456

Modeling rocky coastline evolution and equilibrium

NASA Astrophysics Data System (ADS)

Many of the world’s rocky coastlines exhibit planform roughness in the form of alternating headlands and embayments. Along cliffed coasts, it is often assumed that headlands consist of rock that is more resistant to wave attack than in neighboring bays, because of either structural or lithologic variations. Bays would then retreat landward faster than headlands, creating the undulating planform profiles characteristic of a rocky coastal landscape. While the interplay between alongshore rock strength and nearshore wave energy is, in some circumstances, a fundamental control on coastline shape, beach sediment is also important. Laboratory experiments and field observations have shown that beach sediment, in small volumes, can act as an abrasive tool to encourage sea cliff retreat. In large volumes, though, sediment discourages wave attack on the cliff face, acting as a protective barrier. This nonlinearity suggests a means for headland persistence, even without alongshore variations in rock strength: bare-rock headlands could retreat more slowly than, or at the same rate as, neighboring sediment-filled embayments because of alongshore variations in the availability of beach sediment. Accordingly, nearshore sediment dynamics (i.e. sediment production from sea cliff retreat and alongshore sediment transport) could promote the development of autogenic planform geometry. To explore these ideas, we present numerical and analytical modeling of large-scale (> one kilometer) and long-term (millennial-scale) planform rocky coastline evolution, in which sediment is supplied by both sea cliff erosion and coastal rivers and is distributed by alongshore sediment transport. We also compare model predictions with real landscapes. Previously, our modeling exercises focused on a basic rocky coastline configuration where lithologically-homogeneous sea cliffs supplied all beach sediment and maintained a constant alongshore height. Results showed that 1) an equilibrium alongshore headland and sediment-filled bay sequence could persist in the absence of heterogeneous lithology, 2) headland spacing was not autogenic and was a function of the initial coastline shape, and 3) that the proportion of the equilibrium coastline that consisted of headlands (and bays) was analytically predictable and depended on sea cliff height and composition as well as rates of beach erosion and bare-rock sea cliff retreat. In the present contribution we include fluvial sediment sources, alongshore and cross-shore variations in sea cliff height (which, in turn, vary cliff sediment supply in time and space), lithologic heterogeneities, and submarine canyons that extend into the nearshore zone and intercept alongshore sediment transport (similar to the California coastline). These modifications alter the style of rocky coastline evolution and the final equilibrium coastline configuration. We compare numerical and analytical model results to real landscapes, focusing on the California coastline. Overall, we seek to establish simple relationships between physical parameters (sea cliff characteristics, sediment sources and sinks, and wave climate) that can be used to explain why some coastlines exhibit rocky headlands, and how extensive the headlands are (relative to beach-covered stretches).

Limber, P. W.; Murray, A. B.

2010-12-01

457

Calculation of individual isotope equilibrium constants for geochemical reactions

Theory is derived from the work of Urey (Urey H. C. [1947] The thermodynamic properties of isotopic substances. J. Chem. Soc. 562-581) to calculate equilibrium constants commonly used in geochemical equilibrium and reaction-transport models for reactions of individual isotopic species. Urey showed that equilibrium constants of isotope exchange reactions for molecules that contain two or more atoms of the same element in equivalent positions are related to isotope fractionation factors by ?? = (Kex)1/n, where n is the number of atoms exchanged. This relation is extended to include species containing multiple isotopes, for example 13C16O18O and 1H2H18O. The equilibrium constants of the isotope exchange reactions can be expressed as ratios of individual isotope equilibrium constants for geochemical reactions. Knowledge of the equilibrium constant for the dominant isotopic species can then be used to calculate the individual isotope equilibrium constants. Individual isotope equilibrium constants are calculated for the reaction CO2g = CO2aq for all species that can be formed from 12C, 13C, 16O, and 18O; for the reaction between 12C18 O2aq and 1H218Ol; and among the various 1H, 2H, 16O, and 18O species of H2O. This is a subset of a larger number of equilibrium constants calculated elsewhere (Thorstenson D. C. and Parkhurst D. L. [2002] Calculation of individual isotope equilibrium constants for implementation in geochemical models. Water-Resources Investigation Report 02-4172. U.S. Geological Survey). Activity coefficients, activity-concentration conventions for the isotopic variants of H2O in the solvent 1H216Ol, and salt effects on isotope fractionation have been included in the derivations. The effects of nonideality are small because of the chemical similarity of different isotopic species of the same molecule or ion. The temperature dependence of the individual isotope equilibrium constants can be calculated from the temperature dependence of the fractionation factors. The derivations can be extended to calculation of individual isotope equilibrium constants for ion pairs and equilibrium constants for isotopic species of other chemical elements. The individual isotope approach calculates the same phase isotopic compositions as existing methods, but also provides concentrations of individual species, which are needed in calculations of mass-dependent effects in transport processes. The equilibrium constants derived in this paper are used to calculate the example of gas-water equilibrium for CO2 in an acidic aqueous solution. ?? 2004 Elsevier Ltd.

Thorstenson, D.C.; Parkhurst, D.L.

2004-01-01

458

We report the mass measurement of the short-lived {sup 12}Be nuclide (T{sub 1/2}=21.5 ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of 25 078.0(2.1) keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin T=2 states in {sup 12}C and {sup 12}O, we reevaluate the isobaric mass multiplet equation for the lowest lying T=2 multiplet in the A=12 system and use the extracted parameters to extrapolate from the known excited 2{sup +} and 0{sup +} states in {sup 12}Be. Though this analysis favors the second known T=2 state in {sup 12}C to be 2{sup +}, 0{sup +} cannot be excluded.

Ettenauer, S.; Brodeur, M.; Gallant, A. T.; Dilling, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia (Canada); Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia (Canada); Brunner, T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia (Canada); Physik Department E12, Technische Universitaet Muenchen, Garching (Germany); Lapierre, A.; Ringle, R.; Pearson, M. R.; Delheij, P.; Lassen, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia (Canada); Lunney, D. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia (Canada); CSNSM-IN2P3-CNRS, Universite Paris 11, F-91405 Orsay (France)

2010-02-15

459

NASA Astrophysics Data System (ADS)

Isochronous mass spectrometry has been applied to neutron-deficient Ni58 projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived Tz=-3/2 nuclides including Ti41, Cr45, Fe49, and Ni53 have been measured with a precision of 20-40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the A=53, T=3/2 quartet. We perform full space shell model calculations and compare them with the new experimental results.

Zhang, Y. H.; Xu, H. S.; Litvinov, Yu. A.; Tu, X. L.; Yan, X. L.; Typel, S.; Blaum, K.; Wang, M.; Zhou, X. H.; Sun, Y.; Brown, B. A.; Yuan, Y. J.; Xia, J. W.; Yang, J. C.; Audi, G.; Chen, X. C.; Jia, G. B.; Hu, Z. G.; Ma, X. W.; Mao, R. S.; Mei, B.; Shuai, P.; Sun, Z. Y.; Wang, S. T.; Xiao, G. Q.; Xu, X.; Yamaguchi, T.; Yamaguchi, Y.; Zang, Y. D.; Zhao, H. W.; Zhao, T. C.; Zhang, W.; Zhan, W. L.

2012-09-01

460

General-equilibrium incidence of energy taxation

Taxes on energy consumption, energy-import tariffs, and subsidization of domestic energy production have recently been offered as policies intended to reduce dependency on uncertain sources of foreign energy supply. This dissertation addresses the distributional consequences of such broadly-based energy-taxation policies. Particular attention is focused on the incidence of such policies on payments to factors, and on relative prices of consumption goods. These aspects of energy policy incidence are first considered separately. An expression for the impact of an energy tax on the rental/wage ratio is derived from a two-sector general equilibrium model with intermediate goods. The incidence is a function of factor intensities and substitution possibilities, and of demand elasticities, where both factor intensities and substitution possibilities are measured so as to include both direct inputs and indirect inputs via intermediate goods. Reasonable parameter values imply that the tax is borne disproportionately by capital, and is thus progressive. The effect of an energy tax on output depends on variations in total energy intensities, where total includes both direct input and indirect input via intermediate goods. Intensities for a 36-sector breakdown of goods are calculated. Even with little disaggregation, relative price effects will be of the same order of magnitude as factor price impacts.

Solow, J.L.

1983-01-01

461

Amazon basin: a system in equilibrium

Despite very active deforestation in 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% of the precipitation is recycled, and in some areas even more. The soils are poor. Most of the nitrogen and phosphorus is found in the soil, and the remaining nutrient elements are found in the standing biomass. There is some nutrient recycling and little loss from the intact ecosystem, and the small input of nutrients from precipitation maintains a small positive nutrient balance. Continued large-scale deforestation is likely to lead to increased erosion and water runoff with initial flooding in the lower Amazon, together with reduced evapotranspiration and ultimately reduced precipitation. Reduced precipitation in the Amazon could increase the tendency toward continentality and adversely affect climate and the present agriculture in south-central Brazil. 83 references, 1 figure, 5 tables.

Salati, E.; Vose, P.B.

1984-07-13

462

Scale covariant gravity and equilibrium cosmologies

Causal structure, inertial path structure and compatibility with quantum mechanics demand no full Lorentz metric, but only an integrable Weyl geometry for space time (Ehlers/Pirani/Schild 1972, Audretsch e.a. 1984). A proposal of (Tann 1998,,Drechsler/Tann 1999) for a minimal coupling of the Hilbert-Einstein action to a scale covariant scalar vacuum field $\\phi$ (weight -1) plus (among others) a Klein-Gordon action term opens the access to a scale covariant formulation of gravity. The ensuing scale covariant K-G equation specifies a natural scale gauge vacuum gauge). Adding other natural assumptions for gauge conditions (in particular Newton gauge, with unchanging Newton constant) the chosen Ansatz leads to a class of Weyl geometric Robertson-Walker solutions of the Einstein equation, satisfying $a''a+a'^2= const$, analogous to the Friedmann-Lemaitre equation but with completely different dynamical properties ($a$ the warp function in Riemann gauge). The class has an asymptotically attracting 1-parameter subfamily of extremely simple space-time geometries with an isotropic Robertson-Walker fluid as source of the Einstein equation, discussed as Weyl universes elsewhere (Scholz 2005). Under the assumption of a heuristic gravitational self energy binding Ansatz for the fluid, equilibrium solutions arise, in stark contrast to classical (semi-Riemannian) cosmology. Weyl universes agree very well with a variety of empirical data from observational cosmology, in particular supernovae luminosities and quasar data.

Erhard Scholz

2007-03-20

463

Guidewire path simulation using equilibrium of forces

NASA Astrophysics Data System (ADS)

Vascular diseases are among the major causes of death in developed countries and the treatment of those pathologies may require endovascular interventions, in which the physician utilizes guidewires and catheters through the vascular system to reach the injured vessel region. Several computational studies related to endovascular procedures are in constant development. So, predicting the guidewire path may be of great value for both physicians and researchers. We propose a method to simulate and predict the guidewire and catheter path inside a blood vessel based on equilibrium of forces, which leads, iteratively, to the minimum energy configuration. This technique was validated with physical models using a Ø0.33mm stainless steel guidewire. This method presented RMS error, in average, less than 1 mm. Moreover, the algorithm presented low variation (in average, ?=0.03mm) due to the variation of the input parameters. Therefore, even for a wide range of different parameters configuration, similar results are presented, which makes this technique easier to work with. Since this method is based on basic physics, it is simple, intuitive, easy to learn and easy to adapt.

Cardoso, Fernando M.; Furuie, Sergio S.

2014-03-01

464

A theoretical analysis of vertical flow equilibrium

The assumption of Vertical Flow Equilibrium (VFE) and of parallel flow conditions, in general, is often applied to the modeling of flow and displacement in natural porous media. However, the methodology for the development of the various models is rather intuitive, and no rigorous method is currently available. In this paper, we develop an asymptotic theory using as parameter the variable R{sub L} = (L/H){radical}(k{sub V})/(k{sub H}). It is rigorously shown that present models represent the leading order term of an asymptotic expansion with respect to 1/R{sub L}{sup 2}. Although this was numerically suspected, it is the first time that is is theoretically proved. Based on the general formulation, a series of models are subsequently obtained. In the absence of strong gravity effects, they generalize previous works by Zapata and Lake (1981), Yokoyama and Lake (1981) and Lake and Hirasaki (1981), on immiscible and miscible displacements. In the limit of gravity-segregated flow, we prove conditions for the fluids to be segregated and derive the Dupuit and Dietz (1953) approximations. Finally, we also discuss effects of capillarity and transverse dispersion.

Yortsos, Y.C.

1992-01-01

465

The Quark-Gluon Plasma in Equilibrium

Our current knowledge of the quark-gluon plasma in thermodynamical equilibrium is reviewed. The phase diagram of strongly interacting matter is discussed, with emphasis on the quark-hadron phase transition and the color-superconducting phases of quark matter. Lattice QCD results on the order of the phase transition, the thermodynamical functions, the heavy quark free energy, mesonic spectral functions, and recent results for nonzero quark chemical potential are presented. Analytic attempts to compute the thermodynamical properties of strongly interacting matter, such as perturbation theory, quasiparticle models, ``hard-thermal-loop''(HTL)-resummed perturbation theory, the Polyakov-loop model, as well as linear sigma models are discussed. Finally, color-superconducting quark matter is considered in the limit of weak coupling. The gap equation and the excitation spectrum are derived. The solution of the gap equation, gap parameters in various color-superconducting phases, and critical temperatures for the transition to normal-conducting quark matter are presented. A summary of gluon and photon properties in color superconductors is given.

Dirk H. Rischke

2003-05-12

466

Amazon basin: a system in equilibrium.

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, and in some areas even more. The soils are poor. Most of the nitrogen and phosphorus is found in the soil, and the remaining nutrient elements are found in the standing biomass. There is some nutrient recycling and little loss from the intact ecosystem, and the small input of nutrients from precipitation maintains a small positive nutrient balance. Continued large-scale deforestation is likely to lead to increased erosion and water runoff with initial flooding in the lower Amazon, together with reduced evapotranspiration and ultimately reduced precipitation. Reduced precipitation in the Amazon could increase the tendency toward continentality and adversely affect climate and the present agriculture in south-central Brazil. PMID:17837908

Salati, E; Vose, P B

1984-07-13

467

Equilibrium Pure States and Nonequilibrium Chaos

We consider nonequilibrium systems such as the Edwards-Anderson Ising spin glass at a temperature where, in equilibrium, there are presumed to be (two or many) broken symmetry pure states. Following a deep quench, we argue that as time goes to infinity, although the system is usually in some pure state locally, either it never settles permanently on a fixed lengthscale into a single pure state, or it does but then the pure state depends on both the initial spin configuration and the realization of the stochastic dynamics. But this latter case can occur only if there exists an uncountable number of pure states (for each coupling realization) with almost every pair having zero overlap. In both cases, almost no initial spin configuration is in the basin of attraction of a single pure state; that is, the configuration space (resulting from a deep quench) is all boundary (except for a set of measure zero). We prove that the former case holds for deeply quenched two-dimensional ferromagnets. Our results raise the possibility that even if more than one pure state exists for an infinite system, time averages don't necessarily disagree with Boltzmann averages.

C. M. Newman; D. L. Stein

1998-09-28

468

Pre-equilibrium studies in monoisotopic praseodymium

Measurement and analysis of excitation functions in {alpha}-induced reactions has become an important tool for studying the pre-equilibrium (PE) phenomenon. As part of the programme of precise measurement and analysis of excitation functions in reactions for a large number of nuclei, the authors report the measurement of excitation functions for the reactions {sup 141}Pr({alpha},n){sup 144}Pm and {sup 141}Pr({alpha},2n){sup 143}Pm in the energy range from threshold to {approx}40 MeV. To the best of their knowledge, these excitation functions have been measured for the first time. Measurements have been performed using stacked foil activation technique. The irradiation has been carried out at the Variable Energy Cyclotron Centre (VECC), Calcutta, India using the {alpha}-beam of {approx} 40 MeV. The post irradiation analysis has been done using the HPGe detector coupled to the ORTEC`s PC based multichannel analyser. The analysis of the excitation functions has been carried out using the semi-classical computer codes ACT and ALICE-82. These codes use Hauser-Feshbach/ Welsskopf-Ewing formalism for compound nucleus calculations and exciton/hybrid model for simulating PE contributions. The quantum mechanical statistical multistep code EXIFON has also been used for the analysis of these excitation functions. The comparison of results with different codes will be presented.

Singh, B.P.; Mustafa, M.M.; Sankarcharyulu, M.G.V. [Aligarh Muslim Univ. (India)] [and others

1994-12-31

469

UK Tax Policy and Applied General Equilibrium Analysis

At the time of this volume's publication in 1985, general equilibrium modelling had become a significant area of applied economic research. Its focus was to develop techniques to facilitate economy-wide quantitative assessment of allocative and distributional impacts on policy changes. UK Tax Policy and Applied General Equilibrium Analysis was the first book-length treatment of the development and application of an

John Piggott; John Whalley

1985-01-01