Note: This page contains sample records for the topic isobaric vapor-liquid equilibrium from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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

Microsoft Academic Search

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

Ernesto Vercher; M. Pilar Peña; Antoni Martinez-Andreu

1996-01-01

2

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

Microsoft Academic Search

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

Ernesto Vercher; M. Pilar Peña; Antoni Martinez-Andreu

1996-01-01

3

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

Microsoft Academic Search

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

M. Pilar Peña; Ernesto Vercher; Antoni Martinez-Andreu

1996-01-01

4

Isobaric vapor–liquid equilibrium for binary systems containing benzothiophene  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) of the following systems was measured with a recirculation still: benzothiophene+dodecane at 99.6kPa, benzothiophene+1-dodecene at 100.1kPa, and benzothiophene+1-octanol at 100kPa. All systems studied exhibit positive deviation from Raoult's law. A minimum temperature azeotrope was found in the systems benzothiophene+dodecane (x1=0.491, P=99.6kPa, T=484.72K) and benzothiophene+1-dodecene (x1=0.185, P=100.1kPa, T=484.45K). No azeotropic behavior was found in benzothiophene+1-octanol system at

Erlin Sapei; Juha-Pekka Pokki; Petri Uusi-Kyyny; Kari I. Keskinen; Ville Alopaeus

2011-01-01

5

Isobaric vapor–liquid and vapor–liquid–liquid equilibrium data for the system water + ethanol + cyclohexane  

Microsoft Academic Search

Isobaric vapor–liquid (VLE) and vapor–liquid–liquid equilibria (VLLE) were measured for the ternary system water+ethanol+cyclohexane at 101.3kPa. The experimental determination was carried out in a dynamic equilibrium still with circulation of both the vapor and liquid phases, equipped with an ultrasonic homogenizer. The experimental data demonstrated the existence of a ternary heterogeneous azeotrope at 335.6K with a composition of 0.188, 0.292,

V. Gomis; R. Pedraza; M. D. Saquete

2005-01-01

6

Isobaric vapor–liquid and vapor–liquid–liquid equilibrium data for the water–ethanol–hexane system  

Microsoft Academic Search

Isobaric vapor–liquid and vapor–liquid–liquid equilibria were measured for the water–ethanol–hexane system at normal atmospheric pressure. The apparatus used for the determination of vapor–liquid–liquid equilibrium data was an all-glass dynamic recirculating still with an ultrasonic homogenizer coupled to the boiling flask.The experimental data demonstrated the existence of a ternary heterogeneous azeotrope at 329.2K with a composition of 0.105, 0.236 and 0.658mol

V. Gomis; R. Pedraza; M. D. Saquete

2007-01-01

7

Determination of valley and ridge of isobaric vapor–liquid equilibrium for ternary system  

Microsoft Academic Search

The aim of this paper is to describe a method for the determination of the valley and ridge of isobaric vapor–liquid equilibrium (VLE) for ternary systems which have a ternary azeotropic point at atmospheric and at lower pressure. The extended Redlich–Kister equation was employed as an activity coefficient for calculating the isobaric VLE, because this equation can be applied to

Kiyofumi Kurihara; Hiroyuki Matsuda; Katsumi Tochigi; Kenji Ochi; Kazuo Kojima

2007-01-01

8

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

Microsoft Academic Search

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.

Ernesto Vercher; M. Pilar Pena; Antoni Martinez-Andreu

1994-01-01

9

Isobaric vapor-liquid equilibrium for methyldichlorosilane-dimethyldichlorosilane-benzene system  

Microsoft Academic Search

The elucidation of vapor-liquid equilibrium (VLE) of the halogenated silane was necessary for the production of silicon derivatives,\\u000a especially for methylvinyldichlorosilane, due to the lack of the relevant reports. Isobaric VLE for the system methyldichlorosilane-dimethyldichlorosilane-benzene\\u000a and isobaric VLE of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325 kPa. These\\u000a binary compositions of the

Qiu Zu-min; Xie Xin-liang; Yu Shu-xian; Chen Wen-you; Xie Feng-xia; Liu Juan

2005-01-01

10

Isobaric Vapor-Liquid Equilibrium Data for Binary Mixture of 2-Methyltetrahydrofuran and  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium measurements are reported for binary mixture of 2-Methyltetrahydrofuran and Cumene at 97.3 kPa. The data were obtained using a vapor recirculating type (modified Othmer's) equilibrium still. The mixture shows slight negative deviation from ideality. The system does not form an azeotrope. The experimental data obtained in this study are thermodynamically consistent according to the Herington test. The

V. K. Rattan; Baljinder K. Gill; Seema Kapoor

2008-01-01

11

Isobaric vapor–liquid equilibrium for methyltrichlorosilane–dimethyldichlorosilane–benzene system  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) for the system methyltrichlorosilane–dimethyldichlorosilane–benzene and that of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325kPa. These binary compositions of the equilibrium vapor were calculated according to the Q function of molar excess Gibbs energy by the indirect method and the resulted VLE data agreed well with the thermodynamic consistency.

Zumin Qiu; Xinliang Xie; Yunbing He; Fengxia Xie; Qinfen Wu; Yingping Ding

2006-01-01

12

Investigation on isobaric vapor–liquid equilibrium for acetic acid + water + methyl ethyl ketone + isopropyl acetate  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+methyl ethyl ketone (MEK), MEK+isopropyl acetate, acetic acid+MEK+water and acetic acid+MEK+isopropyl acetate+water are measured at 101.33kPa using a modified Rose cell. The nonideal behavior in vapor phase of binary systems measured in this work is analyzed through calculating fugacity coefficients since mixture containing acetic acid deviates from ideal behavior seriously in

Qiang Xie; Hui Wan; MingJuan Han; GuoFeng Guan

2009-01-01

13

Isobaric low pressure vapor–liquid equilibrium data for the binary system monochloroacetic acid + dichloroacetic acid  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for the binary system monochloroacetic acid+dichloroacetic acid have been measured at 5, 7.5, and 10kPa. The VLE data measured in this work is thermodynamically consistent according to the Herington area method. The non-ideal behavior in the vapor phase was correlated using the Hayden–O’Connell model. Wilson, NRTL, and UNIQUAC were used to account for the liquid

Alex Londoño; Mark T. G. Jongmans; Boelo Schuur; André B. de Haan

14

Isobaric vapor-liquid equilibrium for methyldichlorosilane-dimethyldichlorosilane-benzene system.  

PubMed

The elucidation of vapor-liquid equilibrium (VLE) of the halogenated silane was necessary for the production of silicon derivatives, especially for methylvinyldichlorosilane, due to the lack of the relevant reports. Isobaric VLE for the system methyldichlorosilane-dimethyldichlorosilane-benzene and isobaric VLE of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325 kPa. These binary compositions of the equilibrium vapor were calculated according to the Q function of molar excess Gibbs energy by the indirect method and the resulted VLE data agreed well with the thermodynamic consistency. Moreover, the experimental data were correlated with the Wilson, NRTL, Margules and van Laar equations by means of the least-squares fit, the acquired optimal interaction parameters were fitted to experimental vapor-liquid equilibrium data for binary systems. The binary parameters of Wilson equation were also used to calculate the bubble point temperature and the vapor phase composition for the ternary mixtures without any additional adjustment. The predicted vapor-liquid equilibrium for the ternary system was in a good agreement with the experimental results. The VLE of binary and multilateral systems provided essential theory for the production of the halogenated silane. PMID:16187419

Qiu, Zu-Min; Xie, Xin-Liang; Yu, Shu-Xian; Chen, Wen-You; Xie, Feng-Xia; Liu, Juan

2005-10-01

15

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

Microsoft Academic Search

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

Jose M. Resa; Teresita Quintana; Emilio Cepeda

1994-01-01

16

Isobaric Vapor-Liquid Equilibrium of Binary Mixture of Methyl Acetate with Isopropylbenzene at 97.3 kPa  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium measurements are reported for the binary mixture of Methyl acetate and Isopropylbenzene at 97.3 kPa. The measurements have been performed using a vapor recirculating type (modified Othmer's) equilibrium still. The mixture shows positive deviation from ideality and does not form an azeotrope. The activity coefficients have been calculated taking into consideration the vapor phase nonideality. The data

Seema Kapoor; Baljinder K. Gill; V. K. Rattan

2008-01-01

17

Isobaric vapor-liquid equilibrium of binary mixtures of 1-propanol + chlorobenzene and 2-propanol + chlorobenzene  

Microsoft Academic Search

Isobaric vapor-liquid equilibria were obtained for the system 1-propanol + chlorobenzene at 20 and 100 kPa and for the system 2-propanol + chlorobenzene at 100 kPa using a dynamic still. The experimental error in temperature was ±0.1 K, in pressure ±0.01 kPa and ±0.1 kPa for the experiments carried out at 20 and 100 kPa, respectively, and in the liquid

Ana Dejoz; Vicenta González-Alfaro; Francisco J. Llopis; Pablo J. Miguel; M. Isabel Vázquez

1997-01-01

18

Effect of calcium chloride on the isobaric vapor-liquid equilibrium of 1-propanol + water  

Microsoft Academic Search

The effect of calcium chloride at salt mole fractions from 0.02 to saturation on the vapor-liquid equilibrium (VLE) of 1-propanol + water has been studied at 101.32 kPa using a modified Othmer equilibrium still. The salt exhibited a salting-out effect of the alcohol over the whole range of liquid composition, the azeotrope being eliminated at salt mole fractions greater than

Maria C. Iliuta; Fernand C. Thyrion; Ortansa M. Landauer

1996-01-01

19

Salt effect on the isobaric vapor-liquid equilibrium of the methyl acetate + methanol system  

Microsoft Academic Search

The effect of sodium thiocyanate at constant salt mole fraction from 0.01 to 0.05 and at saturation on the vapor-liquid equilibrium (VLE) of methyl acetate + methanol has been studied at 101.32 kPa using a modified Othmer equilibrium still. The salt exhibited both salting-in and salting-out effects on the methyl acetate, the azeotrope being eliminated at saturation. The results were

Maria C. Iliuta; Fernand C. Thyrion; Ortansa M. Landauer

1996-01-01

20

Isobaric vapor-liquid equilibrium for methyldichlorosilane- methyltrichlorosilane-dimethyldichlorosilane system  

Microsoft Academic Search

This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichloro- silane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected

QIU Zu-min; XIE Xin-liang; LUO Mei; XIE Feng-xia

21

Isobaric vapor-liquid equilibrium for methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system.  

PubMed

This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected by the least square method. The ternary system VLE data were predicted by the Wilson equation, with the calculated boiling points showing good agreement with the experimental data. PMID:15909344

Qiu, Zu-min; Xie, Xin-liang; Luo, Mei; Xie, Feng-xia

2005-06-01

22

Investigation on isobaric vapor liquid equilibrium for acetic acid + water + ( n-propyl acetate or iso-butyl acetate)  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+n-propyl acetate, acetic acid+iso-butyl acetate, acetic acid+water+n-propyl acetate, acetic acid+water+iso-butyl acetate are measured at 101.33kPa with a modified Rose still. The nonideal behavior in vapor phase caused by the association of acetic acid are corrected by the chemical theory and Hayden–O’Connell method, and analyzed by calculating the second virial coefficients and

Chundong Zhang; Hui Wan; Lijun Xue; Guofeng Guan

2011-01-01

23

Effect of calcium chloride on the isobaric vapor-liquid equilibrium of 1-propanol + water  

SciTech Connect

The effect of calcium chloride at salt mole fractions from 0.02 to saturation on the vapor-liquid equilibrium (VLE) of 1-propanol + water has been studied at 101.32 kPa using a modified Othmer equilibrium still. The salt exhibited a salting-out effect of the alcohol over the whole range of liquid composition, the azeotrope being eliminated at salt mole fractions greater than 0.080. A liquid phase splitting into two immiscible liquid phases on the whole range of salt concentration and over a liquid range of about 0.01--0.54 1-propanol mole fraction (salt-free basis) was observed. The results were compared with the values predicted from the extended UNIQUAC models of Sander et al. and Macedo et al. and the modified UNIFAC group-contribution model of Kikic et al.

Iliuta, M.C.; Thyrion, F.C. [Louvain Univ., Louvain-la-Neuve (Belgium). Chemical Engineering Inst.] [Louvain Univ., Louvain-la-Neuve (Belgium). Chemical Engineering Inst.; Landauer, O.M. [Univ. Politehnica Bucharest (Romania)] [Univ. Politehnica Bucharest (Romania)

1996-05-01

24

Experimental study of miscibility, density and isobaric vapor-liquid equilibrium values for mixtures of methanol in hydrocarbons (C5, C6)  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium data at 141.3 kPa for the mixtures of methanol with n-pentane and n-hexane are reported. The miscibility of methanol + n-hexane is also measured in order to get the UCSP (upper critical solubility point), then the experimental curves of vE are obtained at temperatures with total miscibility. The equilibrium data are correlated with different equations and the

Ana Maria Blanco; Juan Ortega

1996-01-01

25

Isobaric vapor-liquid equilibrium data for the system: Heptaldehyde-methyl undecenoate  

Microsoft Academic Search

Isobaric-bubble temperature data at 50 mmHg were collected for the system heptaldehyde-methyl undecenoate over the entire\\u000a composition range by the indirect method with a standard Swietoslawski-type ebulliometer. The vapor compositions were computed\\u000a by means of the nonrandom two-liquid equation. The average absolute error in temperature was 0.4K.

Y. V. L. Ravikumar; Vijay Kale

1995-01-01

26

Isobaric vapor–liquid–liquid equilibrium and vapor–liquid equilibrium for the system water–ethanol-1,4-dimethylbenzene at 101.3 kPa  

Microsoft Academic Search

An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer has been used to determine vapor–liquid (VLE) and vapor–liquid–liquid (VLLE) equilibria. Consistent data have been obtained for the ternary water+ethanol+p-xylene system at 101.3kPa for temperatures in the range of 351.16–365.40K. Experimental results have been used to check the accuracy of the UNIFAC, UNIQUAC and NRTL models in the liquid–liquid region

Vicente Gomis; Ana Pequenín; Juan Carlos Asensi

2009-01-01

27

Isobaric vapor–liquid equilibrium for the binary mixtures of nonane with cyclohexane, toluene, m-xylene, or p-xylene at 101.3 kPa  

Microsoft Academic Search

The isobaric vapor–liquid equilibrium (VLE) data were determined, by using a recirculation type apparatus, for the binary mixtures of nonane with cyclohexane, toluene, m-xylene, or p-xylene at 101.3kPa. All the data passed the thermodynamic consistency test and no azeotrope was formed in the investigated binary systems. While nonane+p-xylene were found to behave as near ideal systems, nonane+cyclohexane, nonane+toluene, and nonane+m-xylene

Bhupender S. Gupta; Ming-Jer Lee

28

Isobaric vapor-liquid equilibria of water + ethanol + hexyl acetate  

SciTech Connect

The authors determined the isobaric vapor-liquid equilibrium data for the ternary system water + ethanol + hexyl acetate at 101.325 kPa using a distillation apparatus recycling both liquid and vapor phases. The results were compared with those predicted using group contribution methods. The UNIFAC method gave the best predictions.

Arce, A.; Soto, A. [Univ. of Santiago de Compostela (Spain). Chemical Engineering Dept.; Orge, B.; Tojo, J. [Univ. of Vigo (Spain). Chemical Engineering Dept.

1995-09-01

29

Isobaric Vapor-Liquid Equilibrium of Binary System 2-Cyclohexen-1-one and 1,2-Epoxycyclohexane  

Microsoft Academic Search

Green oxidation of cyclohexene using dioxygen as oxidizing agent is highly desirable because of its environmental compatibility and economic impact. Separation of its oxidation products depends on the reliable vapor-liquid equilibrium (VLE) data of relevant components, which are still lacking. The VLE data of binary system 1,2-epoxycyclohexane and 2-cyclohexen-1-one under ambient pressure were obtained using an improved VLE equipment EC-2

Xuemeng WANG; Denggao JIANG; Zaixin GENG

2009-01-01

30

Isobaric vapor–liquid equilibrium for binary mixtures of 2-methylpentane+ethanol and +2-methyl-2-propanol  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) data for the binary systems, 2-methylpentane+ethanol and 2-methylpentane+2-methyl-2-propanol (TBA), are reported at 101.3 kPa, including pure component vapor pressures. The systems deviate remarkably from ideal behaviour presenting one positive azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by Wilson, UNIQUAC, NRTL, and Wisniak–Tamir equations.

Antonio Aucejo; Sonia Loras; Rosa Muñoz; Luis Miguel Ordoñez

1999-01-01

31

Isobaric vapor–liquid–liquid equilibria with a newly developed still  

Microsoft Academic Search

A new and simple apparatus for the measurement of isobaric vapor–liquid–liquid equilibrium (VLLE) is developed by modifying the still proposed by van Zandijcke et al. The still is used to measure the isobaric vapor–liquid equilibrium (VLE) data for the system ethanol–water, the isobaric VLE and VLLE data for the binary systems water–1-butanol and 2-butanol–water at atmospheric pressure. The obtained data

Koichi Iwakabe; Hitoshi Kosuge

2001-01-01

32

Estimation of isobaric vapor–liquid–liquid equilibria for partially miscible mixture of ternary system  

Microsoft Academic Search

The NRTL and UNIQUAC parameters for ethanol–2-butanol–water and ethanol–water–1-butanol systems are determined from the vapor–liquid equilibrium (VLE) data of the constituent binary mixtures and the vapor–liquid–liquid equilibrium (VLLE) data of the ternary mixtures. Those parameters are used to calculate the isobaric ternary VLLE, and the effect of parameters on the calculated VLLE is discussed.The isobaric ternary VLLE are calculated by

Hitoshi Kosuge; Koichi Iwakabe

2005-01-01

33

Isobaric vapor–liquid equilibrium for ternary mixtures of ethanol and methylcyclohexane with 3-methylpentane and tert-butyl alcohol at 101.3 kPa  

Microsoft Academic Search

Consistent vapor–liquid equilibrium (VLE) data for the ternary systems 3-methylpentane+ethanol+methylcyclohexane and ethanol+tert-butyl alcohol (TBA)+methylcyclohexane are reported at 101.3kPa. The VLE data have been correlated by Wilson, UNIQUAC and NRTL equations. The ternary systems do not present azeotrope and are well predicted from binary interaction parameters.

María del Carmen Sánchez-Russinyol; Antonio Aucejo; Sonia Loras

2007-01-01

34

Isobaric vapor–liquid equilibria of water–pyridine and water–pyridine–calcium chloride mixtures  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium data at 705±1mmHg for the systems water–pyridine and water–pyridine–CaCl2 were obtained using the modified Othmer circulation still. The experimental data for the water–pyridine system exhibited an azeotropic point at a water composition of 75.0mol% and a temperature of 92.60°C. The isobaric salt-free binary data were compared with predicted vapor–liquid equilibrium (VLE) data using the UNIFAC model. Good

Fahmi A Abu Al-Rub; Ravindra Datta

2001-01-01

35

Isobaric Vapor-Liquid Equilibrium in the Systems Ethyl 1,1-Dimethylethyl Ether + 2,2,4Trimethylpentane and + Octane  

Microsoft Academic Search

Consistent vapor-liquid equilibrium data for the binary systems ethyl 1,1-dimethylethyl ether (ETBE) + 2,2,4-trimethylpentane and ethyl 1,1-dimethylethyl ether + octane at 94 kPa, including pure component vapor pressures of 2,2,4-trimethylpentane and octane, have been experimentally determined. the measured systems deviate slightly from ideal behavior, can be described as symmetric regular solutions and present no azeotropes. Boiling points were correlated using

Jaime Wisniak; Graciela Galindo; Ricardo Reich; Hugo Segura

1999-01-01

36

Isobaric vapor–liquid equilibrium for binary and ternary mixtures of ethanol+2-methyl-2-propanol and 2-methylpentane+ethanol+2-methyl-2-propanol  

Microsoft Academic Search

Consistent vapor–liquid equilibrium data for the binary and ternary systems ethanol+2-methyl-2-propanol (TBA) and 2-methylpentane+ethanol+TBA are reported at 101.3 kPa. In the binary system, the results indicate a negative deviation from ideality and no azeotrope is present. The ternary system shows negative and positive deviations from ideality, does not present azeotrope, and is well predicted from binary data. The activity coefficients

Antonio Aucejo; Sonia Loras; Rosa Muñoz; Luis Miguel Ordoñez

1999-01-01

37

The Isobaric Vapor-Liquid Equilibrium of Butanone-DMF and Toluene-DMF at Reduced Pressures 1 1 Supported by the National Natural Science Foundation of China (No.20376073)  

Microsoft Academic Search

The isobaric vapor-liquid equilibrium data of butanone(1)-N, N-dimethylformamide (DMF)(2) at 100.92kPa, 93.32kPa, and 79.99kPa and of toluene(1)-DMF(2) at 100.92kPa were measured using a modified Rose-Williams still. The above data met the thermodynamic consistency test and were correlated with the Wilson, NRTL, and UNIQUAC equations. These data can be used in the analysis and design of the process that involves separating

Chang LIU; Lihua WANG; Chaohong HE; Xiangqun YE

2006-01-01

38

Isobaric vapor–liquid equilibrium for binary and ternary mixtures of 2-methyl-2-propanol+methyl 1,1-dimethylpropyl ether+2,2,4-trimethylpentane  

Microsoft Academic Search

New consistent vapor–liquid equilibrium (VLE) data for the binary system methyl 1,1-dimethylpropyl ether (TAME)+2,2,4-trimethylpentane (isooctane) and the ternary system 2-methyl-2-propanol (TBA)+methyl 1,1-dimethylpropyl ether (TAME)+2,2,4-trimethylpentane (isooctane) are reported at 101.3kPa. In the binary system, the results indicate a positive deviation from ideality and no azeotrope is present. The ternary system presents a saddle point azeotrope that can be predicted from binary

Sonia Loras; Antonio Aucejo; Rosa Muñoz; Javier de la Torre

2000-01-01

39

Isobaric vapor-liquid equilibria of methanol + 1-octanol and ethanol + 1-octanol mixtures  

SciTech Connect

Isobaric vapor-liquid equilibrium data for methanol + 1-octanol and ethanol + 1-octanol have been measured at 101.325 kPa. The results were checked for thermodynamic consistency using Fredenslund et al.`s test, correlated using Wilson, NRTL, and UNIQUAC equations for the liquid phase activity coefficients, and compared with the predictions of the ASOG, UNIFAC, and modified UNIFAC group contribution methods.

Arce, A.; Blanco, A.; Soto, A.; Tojo, J. [Univ. of Santiago de Compostela (Spain). Chemical Engineering Dept.

1995-07-01

40

Effect of nonvolatile solute on vapor–liquid equilibrium at fixed liquid composition  

Microsoft Academic Search

The influence of some nonvolatile solutes on boiling points of two azeotropic mixtures (1-propanol–water and methanol–tetrahydrofuran systems) was determined by means of isobaric vapor–liquid equilibrium experiments. A basic thermodynamic equation of nonvolatile solute effect on vapor–liquid equilibrium at fixed liquid composition was derived. Based on the theoretical analysis about the equation, two criterions of universal significance were obtained: (1) when

Ren Yi Sun; Qian Sun

2002-01-01

41

Isobaric vapor–liquid equilibrium for binary mixtures of 1-hexene + n-hexane and cyclohexane + cyclohexene at 30, 60 and 101.3 kPa  

Microsoft Academic Search

Consistent vapor–liquid equilibria (VLE) data were determined for the binary systems 1-hexene+n-hexane and cyclohexane+cyclohexene at 30, 60 and 101.3kPa, with the purpose of studying the influence of the pressure in the separation of these binary mixtures. The two systems show a small positive deviation from ideality and do not present an azeotrope. VLE data for the binary systems have been

Beatriz Marrufo; Antonio Aucejo; Margarita Sanchotello; Sonia Loras

2009-01-01

42

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

Microsoft Academic Search

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

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

2011-01-01

43

Monte Carlo simulations of vapor–liquid–liquid equilibrium of some ternary petrochemical mixtures  

Microsoft Academic Search

The aim of this study was to determine the capability and accuracy of Monte Carlo simulations to predict ternary vapor–liquid–liquid equilibrium (VLLE) for some industrial systems. Hence, Gibbs ensemble Monte Carlo simulations in the isobaric–isothermal (NpT) and isochoric–isothermal (NVT) ensembles were performed to determine vapor–liquid–liquid equilibrium state points for three ternary petrochemical mixtures: methane\\/n-heptane\\/water (1), n-butane\\/1-butene\\/water (2) and n-hexane\\/ethanol\\/water (3).

Suren Moodley; Kim Bolton; Deresh Ramjugernath

2010-01-01

44

Isobaric vapor–liquid equilibria for water + n-propanol + n-butanol ternary system at atmospheric pressure  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for water+n-propanol+n-butanol ternary system have been extensively measured at 99.2kPa using a recirculating still. The experimental data were then correlated using the extended UNIQUAC model, in which the binary interaction energy parameters between the three components were obtained through a simplex fitting method. The results showed that the calculated data by the extended UNIQUAC model

Shun’an Wei; Jianhua Zhang; Lichun Dong; Shiyu Tan; Pan Wang; Xuemei Fu; Yongli Qi

2010-01-01

45

Optimization of activity coefficient models to describe vapor-liquid equilibrium of (alcohol + water) mixtures using a particle swarm algorithm  

Microsoft Academic Search

A method to model the vapor–liquid phase based on a particle swarm algorithm is developed in this study. Two activity coefficient models (UNIQUAC and NRTL) were optimized with particle swarm optimization (PSO), and used to describe the isobaric vapor–liquid equilibrium of fifteen binary mixtures containing alcohol + water. The results were compared with the Levenberg–Marquardt algorithm, and show that the PSO algorithm

Juan A. Lazzús

2010-01-01

46

Vapor-liquid equilibrium and density measurements of tetraalklylammonium bromide + propanol + water systems  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium (VLE) measurements at atmospheric pressure were made for 1.0--3.0 m tetrapropylammonium bromide (TPAB) and 3.0 m tetrabutylammonium bromide (TBAB) in mixtures of 2-propanol and water, and 3.0 m TPAB and 3.0 m TBAB in mixtures of 1-propanol and water. In addition, VLE measurements were made on 3.0 m TBAB in 2-propanol + water mixtures at 0.080 bar.

Joseph T. Slusher; Peter T. Cummings; Yeqiong Hu; Carmen A. Vega; John P. O'Connell

1995-01-01

47

Isobaric vapor–liquid equilibria for the quaternary reactive system: Ethanol + water + ethyl lactate + lactic acid at 101.33 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data of the reactive quaternary system ethanol (1)+water (2)+ethyl lactate (3)+lactic acid (4) have been determined experimentally. Additionally, the reaction equilibrium constant was calculated for each VLE experimental data. The experimental VLE data were correlated using the UNIQUAC equation to describe the chemical and phase equilibria simultaneously. For some of the non-reactive binary systems, UNIQUAC binary

Patricia Delgado; María Teresa Sanz; Sagrario Beltrán

2007-01-01

48

Isobaric vapor-liquid equilibria for methanol + ethanol + water and the three constituent binary systems  

Microsoft Academic Search

Vapor-liquid equilibrium data for methanol + ethanol + water and its three constituent binary systems methanol + ethanol, ethanol + water, and methanol + water were measured at 101.3 kPa using a liquid-vapor ebullition-type equilibrium still. The experimental binary data were correlated by the NRTL equation. The ternary system methanol + ethanol + water was predicted by means of the

Kiyofumi Kurihara; Mikiyoshi Nakamichi; Kazuo Kojima

1993-01-01

49

Isobaric vapor–liquid equilibria for water + propylene glycol monomethyl ether (PGME), water + propyleneglycol monomethyl ether acetate (PGMEA), and PGME + PGMEA at reduced pressures  

Microsoft Academic Search

Isobaric vapor–liquid equilibria were measured for three binary systems of water+propyleneglycol monomethyl ether (PGME), water+propyleneglycol monomethyl ether acetate (PGMEA), and PGME+PGMEA at 93.3, 53.3, 26.7kPa. The equipment used was a modified Rogalski-Malanoski equilibrium still and an ebulliometer. The NRTL equation correlated the experimental binary data with good accuracy.

Katsumi Tochigi; Hideyuki Takahara; Yoshinori Shiga; Yasuto Kawase

2007-01-01

50

Isobaric vapor-liquid equilibria of octane + 1-butanol, + 2-butanol, and + 2-methyl-2-propanol at 101.3 kPa  

Microsoft Academic Search

Isobaric vapor-liquid equilibria were measured for three binary systems of 1-butanol + octane, 2-butanol + octane, and 2-methyl-2-propanol + octane at 101.3 kPa. The measurements were made in an equilibrium still with circulation of both the vapor and liquid phases. Both 1-butanol + octane and 2-butanol + octane form a minimum boiling azeotrope. 2-Methyl-2-propanol + octane is a nonazeotrope. The

Toshihiko Hiaki; Akira Taniguchi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

1996-01-01

51

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

SciTech Connect

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

52

Isobaric vapor-liquid equilibria in the binary system hexane + 2-propanol  

SciTech Connect

New vapor-liquid equilibrium data have been obtained for the binary system hexane + 2-propanol at 94.4 kPa to compare with previously reported data assumed to be thermodynamically inconsistent. The system exhibits large positive deviations from ideal behavior and an azeotrope that boils at 332.92 K and contains 73.3 mol% hexane. The activity coefficients and boiling point of the solution were correlated with its composition by the Redlich-Kister, Wilson, UNIFAC, UNIQUAC, and Wisniak-Tamir models.

Wisniak, J.; Akunis, A. [Ben-Gurion Univ. of the Negev, Beer-Sheva (Israel). Dept. of Chemical Engineering

1995-07-01

53

Vapor-liquid equilibrium of aromatic oil from coal hydrogasification  

SciTech Connect

The need for appropriate phase equilibrium data in the design of emerging coal conversion technology and particularly for the coal hydrogasification process has been the primary reason for the initiation of this project. A recirculation type vapor-liquid equilibrium (VLE) apparatus has been constructed for obtaining phase equilibrium data for complex hydrocarbon mixtures at high pressures and temperatures. A specially designed value has been used for obtaining equilibrium phase samples. The performance of the apparatus was tested for attainment of equilibrium in comparison with published data on VLE and N/sub 2/-n-decane systems. A systematic and complete VLE data for Ch/sub 4/-aromatic oil and H/sub 2/-aromatic oil systems, for pressures in the range of 20 to 110 atm and temperatures in the range of 400 to 550 K is presented. The multicomponent aromatic oil is a simulated light oil from coal hydrogasification without the presence of any highly polar components. Correlations for the estimation of hypothetical liquid phase pure component fugacities of hydrogen and methane, based on binary hydrocarbon VLE data, are presented. The correlations are to be used in conjunction with (1) the Prausnitz-Chueh modification of the Redlich-Kwong equation state for estimation of the vapor phase fugacity coefficients; (2) a slightly modified regular solution theory for estimation of activity coefficients and (3) the Lee-Edmister correlation for estimation of pure component hydrocarbon liquid phase fugacities at subcritical conditions. The methodology presented here has been tested for the computation of the VLE of a few ternary and quaternary systems at high pressures and temperatures with fair success. The technique presented here offers a viable means of estimation of high pressure and temperature VLE of complex hydrocarbon systems.

Srinivasan, R.

1981-01-01

54

Isobaric vapor–liquid equilibria for systems composed by 2-ethoxy-2-methylbutane, methanol or ethanol and water at 101.32 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for 2-ethoxy-2-methylbutane (TAEE)+methanol+water and TAEE+ethanol+water ternary systems, and for their binary subsystems alcohol+ether, have been determined experimentally at 101.32kPa. Both binary systems form an azeotrope with a minimum boiling point. The ternary system TAEE+methanol+water does not form a ternary azeotrope, however, the ternary system TAEE+ethanol+water shows a ternary azeotrope near the top of the binodal.

Alberto Arce; Eva Rodil; Ana Soto

2005-01-01

55

Isobaric vapor–liquid equilibria of 1,1-dimethylethoxy-butane + methanol or ethanol + water at 101.32 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium data (VLE) at 101.325kPa have been determined in the miscible region for 1,1-dimethylethoxy-butane (BTBE)+methanol+water and 1,1-dimethylethoxy-butane (BTBE)+ethanol+water ternary systems, and for their constituent binary systems, methanol+BTBE and ethanol+BTBE. Both binary systems show an azeotrope at the minimum boiling point. In the ternary system BTBE+methanol+water no azeotrope has been found, however, the system BTBE+ethanol+water might form a ternary

Alberto Arce; José Manuel Martínez-Ageitos; Ana Soto

2007-01-01

56

Activity Coefficient Models to Describe Vapor-Liquid Equilibrium in Ternary Hydro-Alcoholic Solutions  

Microsoft Academic Search

In this study, three semipredictive activity coefficient models: Wilson, non-random-two liquid model (NRTL), and universal quasi-chemical model (UNIQUAC), have been used for modeling vapor-liquid equilibrium properties of ternary mixtures that include substances found in alcoholic distillation processes of wine and musts. In particular, vapor-liquid equilibrium in ternary mixtures containing water + ethanol + congener has been modeled using parameters obtained

Claudio A. Faúndez; José O. Valderrama

2009-01-01

57

Isobaric vapor–liquid equilibria for water + acetic acid + ( N-methyl pyrrolidone or N-methyl acetamide)  

Microsoft Academic Search

Isobaric vapor–liquid equilibria (VLE) data for acetic acid+N-methyl pyrrolidone, acetic acid+N-methyl acetamide, water+acetic acid+N-methyl pyrrolidone, and water+acetic acid+N-methyl acetamide systems have been measured at 101.33kPa using a recirculating still. The nonideality of the vapor phase caused by the association of the acetic acid has been corrected by the chemical theory and Hayden–O’Connell method. The experimental binary data have been correlated

Weixian Chang; Hui Wan; Guofeng Guan; Huqing Yao

2006-01-01

58

Effect of magnesium chloride on the isobaric vapor–liquid equilibria of formic acid–water system  

Microsoft Academic Search

Formic acid and water form a maximum-boiling azeotrope in their mixtures. To break the azeotropic boiling in this system, inorganic salts are frequently added, because the addition of electrolytes alters significantly the equilibrium nature of the original system. In this paper we report the vapor–liquid equilibrium data for the formic acid–water–magnesium chloride system over a wide range of salt concentrations

Sei-Hun Yun; Chul Kim; Euy Soo Lee; Yeong-Cheol Kim

1998-01-01

59

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

60

Vapor-Liquid Equilibrium Measurements for Design of Coal Gasification Plants.  

National Technical Information Service (NTIS)

Results are reported on vapor-liquid equilibrium compositions of two synthetic mixtures - H sub 2 +CO+CO sub 2 +CH sub 4 +C sub 2 H sub 6 +Benzene and H sub 2 +CO+CH sub 4 +C sub 2 H sub 6 +C sub 2 H sub 4 +CO sub 2 +H sub 2 S+COS+Benzene. The equilibrium...

A. H. Hill G. L. Anderson

1984-01-01

61

Vapor–liquid equilibrium of systems containing alcohols, water, carbon dioxide and hydrocarbons using SAFT  

Microsoft Academic Search

The statistical associating fluid theory (SAFT) equation of state is employed for the correlation and prediction of vapor–liquid equilibrium (VLE) of eighteen binary mixtures. These include water with methane, ethane, propane, butane, propylene, carbon dioxide, methanol, ethanol and ethylene glycol (EG), ethanol with ethane, propane, butane and propylene, methanol with methane, ethane and carbon dioxide and finally EG with methane

Xiao-Sen Li; Peter Englezos

2004-01-01

62

Vapor–Liquid Equilibrium of Ethanol–Water System in the Presence of Molecular Sieves  

Microsoft Academic Search

Adsorptive distillation is a new process to separate liquid mixtures in a packed distillation column. It depends on using active packing material instead of inert packing material in a packed distillation column. The active packing material can affect the intermolecular forces among the system components and thus alter its vapor–liquid equilibrium (VLE). The VLE of the ethanol–water system at 1

FAHMI A. ABU AL-RUB; FAWZI A. BANAT; RAMI JUMAH

1999-01-01

63

Correlation of vapor - liquid equilibrium data for acetic acid - isopropanol - water - isopropyl acetate mixtures  

Microsoft Academic Search

A correlation procedure for the prediction of vapor - liquid equilibrium of acetic acid - isopropanol - water - isopropyl acetate mixtures has been developed. It is based on the NRTL model for predicting liquid activity coefficients, and on the Hayden-O'Connell second virial coefficients for predicting the vapor phase of systems containing association components. When compared with experimental data the

E. A. Campanella

2006-01-01

64

HIGH PRESSURE VAPOR LIQUID EQUILIBRIUM FOR CARBON DIOXIDE + ETHANOL + 2BUTANONE SYSTEM  

Microsoft Academic Search

Vapor-liquid equilibrium was measured for three binary systems, carbon dioxide + ethanol, carbon dioxide + 2-butanone, and ethanol + 2-butanone, and a ternary system, carbon dioxide + ethanol + 2-butanone, at 313.2K. A circulation type apparatus was used in case of the high pressure systems, carbon dioxide + ethanol, carbon dioxide + 2-butanone, and carbon dioxide + ethanol + 2-butanone,

Tomoya TSUJI; Masatoshi SAKAI; Toshihiko HIAKI

65

Prediction of vapor–liquid equilibrium for binary systems containing HFEs by using artificial neural network  

Microsoft Academic Search

A method using artificial neural network (ANN) was applied to estimate the vapor–liquid equilibrium (VLE) for the binary systems containing hydrofluoroethers (HFEs) and polar compounds. Our new estimation method is composed of three steps. In the first step, the sign of logarithm of activity coefficient (?) is estimated for each binary system using ANN, because it had been found that

Shingo Urata; Akira Takada; Junji Murata; Toshihiko Hiaki; Akira Sekiya

2002-01-01

66

Vapor-liquid equilibrium measurements at 101. 32 kPa for binary mixtures of methyl acetate + ethanol or 1-propanol  

SciTech Connect

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

67

Vapor-liquid equilibrium measurements for methyl propanoate-ethanol and methyl propanoate-propan-1-ol at 101. 32 kPa  

SciTech Connect

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

68

Thermodynamic modeling of the vapor–liquid equilibrium of the water\\/ethanol\\/CO 2 system  

Microsoft Academic Search

The Cubic Plus Association Equation of State (CPA EoS) developed in this laboratory is applied here in the correlation of the binary vapor–liquid equilibrium (VLE) and in the prediction of the ternary VLE of the water\\/ethanol\\/carbon dioxide system at various temperatures and pressures. Carbon dioxide is treated in three different ways: (a) as a non-associating molecule, (b) as an only

Christophoros Perakis; Epaminondas Voutsas; Kostis Magoulas; Dimitrios Tassios

2006-01-01

69

Vapor-liquid equilibrium in low pressure water+congener mixtures  

Microsoft Academic Search

Vapor-liquid equilibrium in binary water+congeners mixtures found in alcoholic distillation has been analyzed using the Peng-Robinson\\u000a equation of state and one of the most popular modern mixing rules, the Wong-Sandler model. Accurate modeling of the concentration\\u000a of congeners (substances different from ethanol and water) in the vapor phase is of special importance because these substances\\u000a give some special characteristics of

Claudio Alonso Faúndez; Felipe Andrés Urbina; José Omar Valderrama

2009-01-01

70

Vapor-liquid equilibrium for carbon dioxide + 1-butanol at high pressure  

Microsoft Academic Search

Phase equilibrium properties of mixtures at high pressures are required for practical use such as in the design and operation of separation equipment in the petroleum natural gas, and related industries. Vapor-liquid equilibria and saturated densities for carbon dioxide + 1-butanol at high pressures were measured at 313.15 K including in the vicinity of the critical region with the static-circulation

Katsuo Ishihara; Akira Tsukajima; Hiroyuki Tanaka; Masahiro Kato; Takeshi Sako; Masahito Sato; Toshikatsu Hakuta

1996-01-01

71

Vapor–liquid equilibrium data for the binary systems in the process of synthesizing diethyl carbonate  

Microsoft Academic Search

Vapor–liquid equilibrium data for the binary systems of carbon monoxide (CO)+diethyl carbonate (DEC) and carbon monoxide+ethyl acetate (EA) were measured at temperatures of 293.2K, 313.2K and 333.2K and the elevated pressures up to 12.00MPa. The measurements were carried out in a cylindrical autoclave with a moveable piston and an observation window. The experimental data were correlated using the Peng–Robisom (PR)

Rongjiao Zhu; Jianguo Zhou; Shucan Liu; Jia Ji; Yiling Tian

2010-01-01

72

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

Microsoft Academic Search

Isobaric vapor-liquid equilibria data were obtained for the 2-propanol + 1-propanol binary system and the water + 1-propanol + 2-propanol ternary system at 100 kPa. The data were found to be thermodynamically consistent according to the Van Ness-Byer-Gibbs method for the binary system and according to the McDermott-Ellis method for the ternary one. The binary system is well represented by

C. Gabaldon; P. Marzal; J. B. Monton; M. A. Rodrigo

1996-01-01

73

Isobaric vapor–liquid equilibria for the n-heptane + ethylene glycol monopropyl ether and n-octane + ethylene glycol monopropyl ether systems  

Microsoft Academic Search

Vapor–liquid equilibria (VLE) for the n-heptane+ethylene glycol monopropyl ether and n-octane+ethylene glycol monopropyl ether systems were measured. Isobaric VLE measurements of the associating fluid mixtures were conducted at several pressures (60kPa, 80kPa and 100kPa) using Fischer VLE 602 equipment. The experimental data were correlated using a two-term virial equation for vapor-phase fugacity coefficients and the three suffix Margules equation, Wilson,

Sunghyun Jang; Seonghoon Hyeong; Moon Sam Shin; Hwayong Kim

2010-01-01

74

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.

75

Vapor-liquid equilibrium in binary and ternary mixtures of nitrogen, argon, and methane  

SciTech Connect

Vapor-liquid equilibrium (VLE) values are required in technological applications and are fundamental to separation operations. In this work the authors report VLE data on the three binary mixtures and the ternary system of nitrogen, argon, and methane at 122.89 K. The experimental VLE values on the binary mixtures were correlated with the Peng-Robinson equation of state, and used to predict the VLE values for the binary system. The predicted values were than compared with the experimental results. Calculated pressure and vapor composition from the equation are compared with the ternary mixture data. The experimental results are successfully correlated with the Peng-Robinson equation of state.

Zhangli Jin; Kunyuan Liu; Wangwang Sheng (Beijing Inst. of Chemical Technology (China). Dept. of Chemical Engineering)

1993-07-01

76

Vapor-liquid equilibrium in the system methyl ethyl ketone-p-xylene  

SciTech Connect

New vapor-liquid equilibrium data have been obtained for the binary system methyl ethyl ketone-p -xylene at 760 mmHg to compare with previously reported data assumed to be thermodynamically inconsistent. The system presents slight positive deviations from ideal solution behavior. The activity coefficients are well correlated by a three-constant Redlich-Klster equation and by the Wilson equation. Boiling points are adequately described by a four-constant equation, and vapor composition is very accurately predicted by the UNIFAC method.

Wisniak, J.; Tamir, A.

1982-10-01

77

Vapor-liquid equilibrium of coal derived fluids by continuous thermodynamics  

SciTech Connect

Coal derived liquids consist of mostly aromatic compounds with definite amounts of elements like carbon, hydrogen, sulphur, nitrogen, and oxygen. A continuous thermodynamic model for vapor --liquid equilibria of these liquids has been developed. Characterization of coal fluids has been done in terms of functional groups, the composition of which may be determined from experimental elemental analysis, and spectroscopic data. The continuous thermodynamic framework has been used to represent different fractions by continuous distributions with molecular weight as the characterizing property. To perform vapor-liquid equilibrium calculations each distribution is represented by a definite number of quadrature points, and a model which incorporates Virial coefficients method for the vapor phase and the UNIFAC group contribution method for the liquid phase has been used. The main work involves a parametric study to determine if one averaged distribution can represent coal fluids with fair degree of accuracy. For this purpose, bubble point, dew point calculations are carried out for the same coal liquid represented first by a single averaged distribution and then by two and more distributions. Phase equilibrium properties have also been calculated for some available experimental data. 30 refs., 16 figs., 42 tabs.

Srinivasan, L.

1990-01-01

78

Isothermal vapor-liquid equilibrium accompanied by esterification; ethanol-formic acid system  

SciTech Connect

The equilibrium total pressures after reaction between ethanol and formic acid were measured at 30, 40 and 50/sup 0/C, and the compositions of the vapor and liquid phases were determined gas chromatographically. Since the presence of the carboxylic acid in the mixture induces dimerization and trimerization of the acid in the vapor phase, the modified fugacity coefficients were calculated from ''chemical'' theory using the Lewis fugacity rule, from which are calculated the activity coefficients and the vapor-phase mole fractions using the nonrandom, two-liquid (NRTL) equation. The parameters in the NRTL equation were obtained from vapor-liquid equilibrium data for the binary system. The calculated results agree closely with the experimental vapor-phase mole-fraction data.

Rim, J.K.; Bae, S.Y.; Lee, H.T.

1985-07-01

79

Vapor-liquid equilibrium in the ternary system hexane + 1-chlorobutane + 2-propanol and its binaries  

SciTech Connect

Vapor-liquid equilibrium at 94.4 kPa has been determined for the ternary system hexane + 1-chlorobutane + 2-propanol and the binary systems hexane + 1-chlorobutane and 1-chlorobutane + 2-propanol. The binary system hexane + 1-chlorobutane exhibits moderate deviations from ideality and an azeotrope that contains 97.5 mol % hexane and boils at 339.25 K. The binary system 1-chlorobutane + 2-propanol presents strong deviations from ideality and an azeotrope that contains 62.8 mol % 1-chlorobutane and boils at 341.60 K. The equilibrium data were correlated by the Redlich-Kister, Wilson, UNIQUAC, UNIFAC, and Wisniak-Tamir equations, and the appropriate parameters are reported. The activity coefficients of the ternary system are predicted from those of the pertinent binary systems very well by the Wilson equation and not so well by the Redlich-Kister equation. A ternary azeotrope is not present.

Wisniak, J.; Akunis, A. [Ben-Gurion Univ. of the Negev, Beer-Sheva (Israel). Dept. of Chemical Engineering

1995-09-01

80

High-pressure vapor-liquid equilibrium for R-22 + ethanol and R-22 + ethanol + water  

SciTech Connect

High-pressure vapor-liquid equilibrium (VLE) data for the systems CO{sub 2} + methanol at 313.05 K, CO{sub 2} + ethanol at 323.55, 325.15, and 333.35 K, R-22 (chlorodifluoromethane) + ethanol at 343.25, 361.45, and 382.45 K, and R-22 + ethanol + water at 351.55, 362.65, and 371.85 K are obtained using a circulation-type VLE apparatus. The apparatus is tested with measurements of the CO{sub 2} + methanol and CO{sub 2} + ethanol systems. The experimental data are correlated using the Peng-Robinson and Elliott-Suresh-Donohue equations of state.

Elbaccouch, M.M.; Raymond, M.B.; Elliott, J.R.

2000-04-01

81

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

82

Isobaric vapor-liquid equilibria for binary systems composed of octane, decane, and dodecane at 20 kPa  

SciTech Connect

The most common operation in the chemical industry is the separation of liquid mixtures through distillation. Efficient design of distillation equipment requires quantitative knowledge of vapor-liquid equilibria (VLE) in binary or multicomponent mixtures. Vapor-liquid equilibria were measured for binary systems of octane + decane, decane + dodecane, and octane + dodecane at 20.00 kPa using a recirculating still. The results are thermodynamically consistent according to the point-to-point consistency test, and deviation from ideal behavior is small for all systems.

Dejoz, A.; Gonzalez-Alfaro, V.; Miguel, P.J.; Vazquez, M.I. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-01-01

83

Distillation Separation of Hydrofluoric Acid and Nitric Acid from Acid Waste Using the Salt Effect on Vapor-Liquid Equilibrium  

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

84

Vapor-liquid equilibrium measurements for design of coal gasification plants  

SciTech Connect

Results are reported on vapor-liquid equilibrium compositions of two synthetic mixtures - H/sub 2/+CO+CO/sub 2/+CH/sub 4/+C/sub 2/H/sub 6/+Benzene and H/sub 2/+CO+CH/sub 4/+C/sub 2/H/sub 6/+C/sub 2/H/sub 4/+CO/sub 2/+H/sub 2/S+COS+Benzene. The equilibrium conditions investigated range from 323 to 479 K and 2280 to 19720 kPa. Based on this study, the Peng-Robinson correlation appears to be slightly better than the Soave-Redlich-Kwong correlation in predicting the phase equilibrium behavior of these complex mixtures. Both correlations are superior to the Grayson-Streed and Chao-Seader correlations. However, the Peng-Robinson correlation still shows some areas where improvements can be made. Specifically, for this six-component system it was observed that - actual hydrogen, methane, and carbon monoxide solubility in the liquid phase is greater than that predicted by the Peng-Robinson correlation under all conditions, and actual benzene, carbon dioxide, and ethane solubility in the gas phase is greater than that predicted under all conditions. 19 references, 7 figures, 10 tables.

Hill, A.H.; Anderson, G.L.

1984-01-01

85

Effect of dissolved inorganic salts on the isothermal vapor–liquid equilibrium of the propionic acid–water mixture  

Microsoft Academic Search

Propionic acid–water is one of the minimum boiling point azeotropic binary mixtures. Alteration of the vapor–liquid equilibrium (VLE) by addition of inorganic salts is of interest, since it allows bypassing the azeotropic point due to salt-in and salt-out effects. The effect of NaCl, NH4Cl, CaCl2, and AlCl3 at salt concentrations of 1 m and the effect of NaCl molality (0.5–3

Fawzi Banat; Sameer Al-Asheh; Jana Simandl

2002-01-01

86

Isothermal Vapor–Liquid Equilibrium of Ethanol–Water Mixtures + Acetone–Ethanol Mixtures Inside Capillary Porous Plates  

Microsoft Academic Search

Isothermal vapor–liquid equilibrium (VLE) of ethanol–water mixtures at different temperatures and the isothermal VLE of acetone–ethanol mixtures at 305.15 K were experimentally measured in three different macroporous plates:a 13.5–?m pore diameter sintered stainless steel plate, a 30–?mpore diameter porous carbon plate, and a 30–?m pore diameter porous Teflon plate. The experimental results showed that the VLE of the ethanol–water system

FAHMI A. ABU AL-RUB; RAVINDRA DATTA

2000-01-01

87

High-pressure vapor-liquid equilibrium measurement for the binary mixtures of carbon dioxide+n-butanol  

Microsoft Academic Search

High-pressure vapor-liquid equilibrium data for the binary mixtures of CO2+n-butanol were measured at various isotherms of (313.15, 323.15, 333.15 and 343.15) K, respectively. The equilibrium compositions\\u000a of vapor and liquid phases and pressures at each temperature were measured in a circulation-type equilibrium apparatus. To\\u000a facilitate easy equilibration, both vapor and liquid phases were circulated separately in the experimental apparatus and

Jong Sung Lim; Cheol Hun Yoon; Ki-Pung Yoo

2009-01-01

88

Vapor-liquid equilibrium, coexistence curve, and critical locus for binary HFC-32/HFC-134a mixture  

NASA Astrophysics Data System (ADS)

Two kinds of equilibrium measurements of binary R-32/134a mixtures were carried out. The vapor-liquid equilibria were measured by the static method in the temperature range between 283 and 313 K. On the basis of the present experimental data, the temperature dependence of the binary interaction parameter k 12 for two equations of state, namely, the Soave-Redlich-Kwong equation and Carnahan-Starling-De Santis equation, was discussed. The vapor-liquid coexistence curve near the critical point was also measured by the observation of meniscus disappearance. The critical temperatures and critical densities of 30 and 70 wt% R-32 mixtures were determined on the basis of the saturation densities along the coexistence curve in the critical region. In addition, a correlation of the critical locus for this mixture is proposed as a function of composition.

Higashi, Y.

1995-09-01

89

Measurement and theoretical prediction of the vapor–liquid equilibrium, densities and interfacial tensions of the system hexane + 2-methoxy-2-methylbutane  

Microsoft Academic Search

Experimental vapor–liquid equilibrium have been measured for the binary system hexane+2-methoxy-2-methylbutane at 50, 75 and 94kPa, and over the temperature range 321–357K using a vapor–liquid equilibrium still with circulation of both phases. In addition mixing volumes were determined at 298.15K and atmospheric pressure with a vibrating tube densimeter, while maximum differential bubble pressure tensiometry was used to measure atmospheric interfacial

Andrés Mejía; Hugo Segura; Marcela Cartes

2011-01-01

90

Vapor-Liquid Equilibrium in the Mixture Dimethyl sulfoxide C2H6OS + C7H8 Toluene (EVLM1211, LB5639_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Dimethyl sulfoxide C2H6OS + C7H8 Toluene (EVLM1211, LB5639_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.

91

Nonrandom lattice fluid group contribution parameter for vapor-liquid equilibrium of esters and their mixtures  

Microsoft Academic Search

A group contribution version of the nonrandom lattice fluid equation of state (NLF-GC EOS) has been used to predict the vapor-liquid\\u000a phase equilibria (VLE) of esters and their mixtures. The investigated esters were divided into groups according to the contribution\\u000a scheme. Two different types of parameters were regressed from experimental datasets. Size parameters were fitted to pure component\\u000a properties, and

Alexander Breitholz; Jong Sung Lim; Jeong Won Kang; Ki-Pung Yoo

2009-01-01

92

On the application of G E models to high-pressure vapor—liquid equilibrium calculations  

Microsoft Academic Search

This paper demonstrates that the two excess Gibbs free energy GE models with temperature-dependent parameters in the modified Huron—Vidal first-order (MHV1) mixing rule allow the Peng—Robinson equation of state modified by Stryjek and Vera (PRSV) to be used for calculation of vapor—liquid equilibria over wide ranges of temperature and pressure. Good results are obtained for strongly non-ideal binary and ternary

Tatsuhiko Ohta

1996-01-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

94

Cross determination of the vapor liquid equilibrium of formaldehyde aqueous solutions by quadrupole mass spectrometry and infrared diode laser spectroscopy.  

PubMed

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

95

Densities and isobaric vapor-liquid equilibria of butyl esters (methanoate to butanoate) with ethanol at 101.32 kPa  

SciTech Connect

Vapor-liquid equilibrium and densities at 101.32 kPa have been determined for the binary systems formed by four butyl esters (from methanoate to butanoate) with ethanol. The four systems exhibit positive deviations from ideal behavior, and all data (p-T-x-y) were found to be thermodynamically consistent. The activity coefficients and the dimensionless function G{sup E}/RT of the solution were correlated with its concentration by different equations. Am azeotrope was found in the mixture butyl methanoate (1) + ethanol (2) at T = 350.9 K and x{sub 1} = y{sub 1} = 0.088. The group contribution models ASOG and modified UNIFAC gave fair predictions.

Gonzalez, E.; Ortega, J. [Univ. of Las Palmas de Gran Canaria (Spain)

1995-11-01

96

Collection of VLE data for acid gas---alkanolamine systems using fourier transform infrared spectroscopy. [Vapor-liquid equilibrium  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor--liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as hindered'' amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor--liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 [times] 10[sup 14] BTU/yr.

Bullin, J.A.; Frazier, R.E.

1992-01-01

97

Vapor-liquid equilibrium and volumetric properties calculations for solutions in the supercritical carbon dioxide  

NASA Astrophysics Data System (ADS)

The calculations of gas solubilities in supercritical solvents require equations of state remaining accurate in the critical range, which are difficult to obtain with classical models. In this work, the Helmholtz energy of a mixture is considered as the sum of the Helmholtz energies of pure components taken at a constant packing fraction and of a residual term which may have the form of a RedlichKister, Van Laar, NRTL, UNIQUAC, or UNIFAC function. Thus it is possible to assign to a given component an equation of state whose form is different from that of the others. This model has been applied to binary systems containing supercritical carbon dioxide. The results are improved with respect to those obtained with the classical model for vapor-liquid equilibria and for volumetric properties.

Rauzy, E.; Peneloux, A.

1986-05-01

98

Vapor-Liquid Equilibrium in the Mixture Hexan-1-ol C6H14O + C8H16O Octan-2-one (EVLM1111, LB5658_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 Hexan-1-ol C6H14O + C8H16O Octan-2-one (EVLM1111, LB5658_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.

99

Vapor-Liquid Equilibrium in the Mixture Hex-3-yne C6H10 + C8H18O Dibutyl ether (EVLM1311, LB5678_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Hex-3-yne C6H10 + C8H18O Dibutyl ether (EVLM1311, LB5678_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.

100

Vapor-Liquid Equilibrium in the Mixture Tetradecafluorohexane C6F14 + C8H18O Dibutyl ether (EVLM1121, LB5736_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 Tetradecafluorohexane C6F14 + C8H18O Dibutyl ether (EVLM1121, LB5736_E)' providing data from direct measurement of mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

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

101

Vapor-Liquid Equilibrium in the Mixture Toluene C7H8 + C8H18O Dibutyl ether (EVLM1121, LB5677_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture Toluene C7H8 + C8H18O Dibutyl ether (EVLM1121, LB5677_E)' providing data from direct measurement of mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

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

102

Vapor-Liquid Equilibrium in the Mixture N-Methylmethanamide C2H5NO + C7H8 Toluene (EVLM1111, LB5698_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-liquid Equilibrium in the Mixture N-Methylmethanamide C2H5NO + C7H8 Toluene (EVLM1111, LB5698_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.

103

Vapor-Liquid Equilibrium in the Mixture Dimethyl carbonate C3H6O3 + C6H14O Hexan-1-ol (EVLM1111, LB5628_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Dimethyl carbonate C3H6O3 + C6H14O Hexan-1-ol (EVLM1111, LB5628_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.

104

Vapor-liquid equilibria for acetone + chloroform + methanol and constituent binary systems at 101. 3 kPa  

Microsoft Academic Search

Vapor-liquid equilibria (VLE) and azeotropic data, which are useful for the design and operation of separation processes, have been observed for many systems. Isobaric vapor-liquid equilibria for acetone + chloroform + methanol and for the constituent binary systems chloroform + methanol and chloroform + acetone were measured at 101.3 kPa using a liquid-vapor ebullition-type equilibrium still. The experimental data were

Toshihiko Hiaki; Kiyofumi Kurihara; Kazuo Kojima

1994-01-01

105

Vapor-liquid equilibria of ethanol with 2,2,4-trimethylpentane or octane at 101. 3 kPa  

Microsoft Academic Search

Vapor-liquid equilibria (VLE) are required for engineering use such as in the design and operation of separation processes. Isobaric vapor-liquid equilibria were measured for ethanol with 2,2,4-trimethylpentane or octane at 101.3 kPa in an equilibrium still with circulation of both the vapor and liquid phases. The results were correlated with the Wilson and nonrandom two-liquid (NRTL) equations.

Toshihiko Hiaki; Kenji Takahashi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

1994-01-01

106

Vapor-Liquid Equilibrium of the Mg(NO Sub 3 ) sub 2 -HNO sub 3 -H sub 2 O System.  

National Technical Information Service (NTIS)

The vapor-liquid equilibrium of the Mg(NO sub 3 ) sub 2 -HNO sub 3 -H sub 2 O system in concentrations of 0 to 70 wt % Mg(NO sub 3 ) sub 2 and 0 to 75 wt % HNO sub 3 at atmospheric pressure was correlated by two approaches. One was based on a dissociation...

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

1983-01-01

107

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

SciTech Connect

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

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

1999-03-01

108

Vapor-liquid equilibria for the binary monoethanolamine+ water and monoethanolamine+ethanol systems  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium data for monocthanolamine (MEA)+water and monoethanolamine (MEA)+ ethanol were measured\\u000a in an equilibrium cell circulating both the vapor and liquid phases. The measurements of the boiling temperatures and corresponding\\u000a equilibrium compositions for two binary mixtures were carried out at the atmospheric pressure. The results were checked for\\u000a thermodynamic consistency by the point test method. The activity coefficients

Sung-Bum Park; Huen Lee

1997-01-01

109

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

Microsoft Academic Search

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

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

2011-01-01

110

Thermodynamic modeling of the vapor–liquid equilibrium of the CO 2\\/H 2O mixture  

Microsoft Academic Search

In order to evaluate the feasibility of CO2 sequestration in geological formations detailed knowledge of the mutual solubilities of the CO2\\/H2O system is required. In this work we employ three models, which all involve the well-known Peng–Robinson equation of state, to study the CO2\\/H2O phase equilibrium, with emphasis on the solubility of CO2 in the aqueous phase and the solubility

Georgia D. Pappa; Christophoros Perakis; Ioannis N. Tsimpanogiannis; Epaminondas C. Voutsas

2009-01-01

111

A non-recycle flow still for the experimental determination of vapor–liquid equilibria in reactive systems  

Microsoft Academic Search

Experiments for the determination of vapor–liquid equilibrium (VLE) data with a Non-Recycle Flow Still (NFS) are described. Due to short residence times, the NFS is especially suited for systems with thermally unstable components and for reactive mixtures. VLE data of the latter are necessary for modeling reactive distillation processes. With the NFS isobaric data both at atmospheric and at reduced

Albert Reichl; Ulrich Daiminger; Adolf Schmidt; Michael Davies; Ulrich Hoffmann; Clemens Brinkmeier; Christoph Reder; Wolfgang Marquardt

1998-01-01

112

Vapor-liquid equilibria of 1-propanol or 2-propanol with octane at 101. 3 kPa  

Microsoft Academic Search

Isobaric vapor-liquid equilibria were measured for 1-propanol or 2-propanol with octane at 101.3 kPa in an equilibrium still with circulation of both the vapor and liquid phases. The results were correlated with the Wilson and nonrandom two-liquid (NRTL) equations.

Toshihiko Hiaki; Kenji Takahashi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

2009-01-01

113

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

Microsoft Academic Search

This work presents an integrated approach for characterizing binary vapor-liquid equilibrium (VLE) through a combination of experimental measurements and thermodynamic modeling for low to medium pressure binary VLE. We focus on two dissimilar mixtures: the non-polar argon-oxygen system of importance for industrial air separation processes and the polar ammonia-water system of interest for understanding the atmospheres of Jupiter, Saturn, Uranus,

Nimmi Chandra Parikh

1997-01-01

114

Vapor–liquid equilibrium ratios for hexane at infinite dilution in ethylene+impact polypropylene copolymer and propylene+impact polypropylene copolymer  

Microsoft Academic Search

Vapor–liquid equilibrium ratios (Kw1? values) for hexane at infinite dilution in propylene+impact polypropylene copolymer (ICP–PP) and ethylene+ICP–PP systems were measured at temperatures 323.2, 343.2 and 363.2 K and pressures up to 2.4 MPa using a chromatographic technique. The solubilities of propylene in polypropylene and those of propylene, ethylene, and hexane in ICP–PP were measured. The PVT properties of the polypropylene

Yoshiyuki Sato; Akio Tsuboi; Atsushi Sorakubo; Shigeki Takishima; Hirokatsu Masuoka; Takeshi Ishikawa

2000-01-01

115

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

Microsoft Academic Search

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

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

2008-01-01

116

Vapor-liquid equilibrium data for methanol, ethanol, methyl acetate, ethyl acetate, and o-xylene at 101.3 kPa  

SciTech Connect

Vapor-liquid equilibrium was measured for the binary systems methanol + o-xylene, ethanol + o-xylene, methyl acetate + o-xylene and ethyl acetate + o-xylene, and for the multicomponent mixtures methanol + methyl acetate + o-xylene, ethanol + ethyl acetate + o-xylene, and methanol + ethanol + methyl acetate + ethyl acetate + o-xylene at 101.3 kPa. The Wilson and Van Laar models were compared with the UNIFAC method. Results show that the correlation was satisfactory.

Costa-Lopez, J.; Garvin, A.; Espana, F.J. [Barcelona Univ. (Spain). Chemical Engineering Dept.

1995-09-01

117

Vapor–liquid equilibrium of difluoromethane +1,1,1,2-tetrafluoroethane systems over a temperature range from 258.15 to 343.15 K  

Microsoft Academic Search

Isothermal vapor–liquid equilibrium data for the binary system of difluoromethane (HFC-32) +1,1,1,2-tetrafluoroethane (HFC-134a) were measured at temperature from 258.15 to 343.15K in a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson–Stryjek–Vera equation of state using the Wong–Sandier mixing rule. The overall deviation of the pressure by the PRSV equation of state was 0.940%, and the average deviation

Xiaolong Cui; Guangming Chen; Changsheng Li; Xiaohong Han

2006-01-01

118

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

NASA Astrophysics Data System (ADS)

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

Wu, Xianghong; Du, Xiaojie; Zheng, Danxing

2010-02-01

119

Vapor–liquid equilibria determination for a hydrofluoroether with several alcohols  

Microsoft Academic Search

A small-capacity apparatus for vapor–liquid equilibrium (VLE) measurement was developed. The overall charge of the still with a provision for vapor and liquid recirculations was about 38 cm3 of the solution. The performance of the proposed apparatus was tested by determining the VLE for the methanol+benzene system at 101.3 kPa. The results obtained were satisfactory. The isobaric VLE were measured

Toshihiko Hiaki; Akiko Kawai

1999-01-01

120

Vapor-Liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C2H2F4 1,1,1,2-Tetrafluoroethane (EVLM1311, LB5632_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Pentafluoroethane C2HF5 + C2H2F4 1,1,1,2-Tetrafluoroethane (EVLM1311, LB5632_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.

121

Vapor-Liquid Equilibrium in the Mixture 1,1,1,2-Tetrafluoroethane C2H2F4 + C4H10O2 2,5-Dioxahexane (EVLM1111, LB5748_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 1,1,1,2-Tetrafluoroethane C2H2F4 + C4H10O2 2,5-Dioxahexane (EVLM1111, LB5748_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.

122

Representing vapor-liquid equilibrium for an aqueous MEA-CO{sub 2} system using the electrolyte nonrandom-two-liquid model  

SciTech Connect

Following the work of Austgen et al., the electrolyte nonrandom-two-liquid (NRTL) model was applied in a thermodynamically consistent manner to represent the vapor-liquid equilibrium (VLE) of the aqueous monoethanolamine (MEA)-CO{sub 2} system with rigorous chemical equilibrium consideration. Special attention was given to the accurate VLE description of the system at both absorbing and stripping conditions relevant to most aqueous MEA absorption/stripping processes for CO{sub 2} removal. The influence from chemical equilibrium constants, Henry`s constant, experimental data, and data regression on the representation of the VLE of the system was discussed in detail. The equilibrium constant of the carbamate reversion reaction as well as important interaction parameters of the electrolyte NRTL model were carefully fitted to experimental data. A good agreement between the calculated values and the experimental data was achieved. Moreover, the model with newly fitted parameters was successfully applied to simulate three industrial cases for CO{sub 2} removal using a rate-based approach. The results from this work were compared with those using the model by Austgen et al.

Liu, Y.; Zhang, L.; Watanasiri, S. [Aspen Technology, Inc., Cambridge, MA (United States)] [Aspen Technology, Inc., Cambridge, MA (United States)

1999-05-01

123

Vapor-liquid equilibrium and critical behavior of the square-well fluid of variable range: A theoretical study  

NASA Astrophysics Data System (ADS)

The vapor-liquid phase behavior and the critical behavior of the square-well (SW) fluid are investigated as a function of the interaction range, ?? [1.25, 3], by means of the self-consistent Ornstein-Zernike approximation (SCOZA) and analytical equations of state based on a perturbation theory [A. L. Benavides and F. del Rio, Mol. Phys. 68, 983 (1989); A. Gil-Villegas, F. del Rio, and A. L. Benavides, Fluid Phase Equilib. 119, 97 (1996)]. For this purpose the SCOZA, which has been restricted up to now to a few model systems, has been generalized to hard-core systems with arbitrary interaction potentials requiring a fully numerical solution of an integro-partial differential equation. Both approaches, in general, describe well the liquid-vapor phase diagram of the square-well fluid when compared with simulation data. SCOZA yields very precise predictions for the coexistence curves in the case of long ranged SW interaction (?>1.5), and the perturbation theory is able to predict the binodal curves and the saturated pressures, for all interaction ranges considered if one stays away from the critical region. In all cases, the SCOZA gives very good predictions for the critical temperatures and the critical pressures, while the perturbation theory approach tends to slightly overestimate these quantities. Furthermore, we propose analytical expressions for the critical temperatures and pressures as a function of the square-well range.

Schöll-Paschinger, Elisabeth; Benavides, Ana Laura; Castañeda-Priego, Ramon

2005-12-01

124

Prediction of Vapor-Liquid Equilibrium Data from C—H Band Shift of IR Spectra in Some Binary Systems * * Supported by the National Natural Science Foundation of China (No.20573093 and No.20434020)  

Microsoft Academic Search

Prediction of vapor-liquid equilibrium (VLE) is extremely necessary to separate liquid mixture in chemical production, especially when the required experimental data are difficult to measure, or the measurement is not economical. The infinite dilution activities can be used to predict VLE. However, it needs both the ends of the activities that are difficult to obtain for many systems. In the

ZHU Xiao; YAO Jia; LI Haoran; HAN Shijun

2007-01-01

125

Crude oil--natural gas system vapor--liquid equilibrium ratios (data at 250°F and system containing 20% C\\/sub 7+\\/. [Ratios for determining total oil recovery  

Microsoft Academic Search

Vapor--liquid equilibrium ratios (K values) have been determined experimentally on a Devonian crude oil--natural gas system containing 20% of the C\\/sub 7+\\/ or heavy fraction. The data were obtained at 250°F and five pressures.

C. F. Wiesepape; H. T. Kennedy; P. B. Crawford

1977-01-01

126

Vapor-liquid equilibria of 1-propanol or 2-propanol with 2,2,4-trimethylpentane at 101. 3 kPa  

Microsoft Academic Search

Isobaric vapor-liquid equilibria were measured for 1-propanol or 2-propanol with 2,2,4-trimethylpentane at 101.3 kPa in an equilibrium still with circulation of both the vapor and liquid phases. The results were best correlated with the Wilson equation. The equilibrium composition of the samples was determined using a Shimadzu gas chromatography. The accuracy of liquid, x[sub i], and vapor, y[sub i], mole

Toshihiko Hiaki; Kenji Takahashi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

1994-01-01

127

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

NASA Astrophysics Data System (ADS)

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

Akasaka, Ryo

128

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

NASA Astrophysics Data System (ADS)

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

Parikh, Nimmi Chandra

1997-11-01

129

Prediction of vapor–liquid equilibrium and PVTx properties of geological fluid system with SAFT-LJ EOS including multi-polar contribution. Part I: Application to H 2O–CO 2 system  

Microsoft Academic Search

Molecular based equations of state (EOS) are attractive because they can take into account the energetic contribution of the main types of molecular interactions. This study models vapor–liquid equilibrium (VLE) and PVTx properties of the H2O–CO2 binary system using a Lennard-Jones (LJ) referenced SAFT (Statistical Associating Fluid Theory) EOS. The improved SAFT-LJ EOS is defined in terms of the residual

Rui Sun; Jean Dubessy

2010-01-01

130

Thermodynamic modeling of vapor–liquid equilibrium of binary systems ionic liquid + supercritical {CO 2 or CHF 3} and ionic liquid + hydrocarbons using Peng–Robinson equation of state  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) data from literature for binary systems involving several ionic liquids were correlated. The Peng–Robinson equation of state, coupled with the van der Waals and Wong–Sandler mixing rules, was used as the thermodynamic model to evaluate the fugacity coefficients. The UNIQUAC and NRTL models were used to calculate the excess Gibbs free energy in the Wong–Sandler mixing rule.

Víctor H. Álvarez; Martín Aznar

2008-01-01

131

Vapor-liquid equilibria for the binary systems of 1-butanol with some halohydrocarbons at 40.0 and 101.3 kPa  

SciTech Connect

Isobaric vapor-liquid equilibrium measurements at 40.0 and 101.3 kPa are reported for 1-butanol + chlorocyclohexane, + chlorobenzene, + bromocyclohexane, + bromobenzene. Some of the studied systems show minimum temperature azeotropes. The experimental data were tested for thermodynamic consistency and satisfactorily correlated with the Margules, Van Laar, Wilson, NRTL, and UNIQUAC equations. Predictions with the UNIFAC method and ASOG method were also obtained.

Artigas, H.; Lafuente, C.; Cea, P.; Royo, F.M.; Urieta, J.S. [Univ. de Zaragoza (Spain)] [Univ. de Zaragoza (Spain)

1997-01-01

132

Vapor-liquid equilibrium data for the propane\\/-, n-butane\\/-, isobutane\\/-, and propylene\\/isopropyl fluoride systems at 30 and 50 °C  

Microsoft Academic Search

This paper presents vapor-liquid equillibrium data at 30 and 50 °C for the binary systems of isopropyl fluoride + propane, propylene, isobutane, and n-butane. The isopropyl fluoride\\/butane systems exhibit positive azeotropes. The computed, equimolar Gibbs free energy for the propylene system is roughly one-half that of the three alliphatic systems.

William R. Parrish; Donald M. Sitton

1982-01-01

133

Liquid–liquid equilibrium data of water with neohexane, methylcyclohexane, tert-butyl methyl ether, n-heptane and vapor–liquid–liquid equilibrium with methane  

Microsoft Academic Search

Liquid–liquid equilibrium (LLE) data for non-aqueous liquid (neohexane [NH], tert-butyl methyl ether [TBME], methylcyclohexane [MCH], or n-heptane [nC7]) and water have been measured under atmospheric pressure at 275.5, 283.15, and 298.15K. It was found that TBME is the most water soluble followed by NH, MCH, and nC7. As the temperature increased, the solubility of the non-aqueous liquids (NALs) in water

R. Susilo; J. D. Lee; P. Englezos

2005-01-01

134

Experimental measurement of vapor pressures and (vapor + liquid) equilibrium for {1,1,1,2-tetrafluoroethane (R134a) + propane (R290)} by a recirculation apparatus with view windows  

Microsoft Academic Search

The saturated vapor pressures of 1,1,1,2-tetrafluoroethane (R134a) and propane (R290), and the (vapor+liquid) equilibrium (VLE) data at (255.000, 265.000, 275.000, and 285.000)K for the (R134a+R290) system were measured by a recirculation apparatus with view windows. The uncertainty of the temperatures, pressures, and compositions are less than ±5mK, ±0.0005MPa, and ±0.005, respectively. The saturated vapor pressures data were correlated by a

Xueqiang Dong; Maoqiong Gong; Junsheng Liu; Jianfeng Wu

2011-01-01

135

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

SciTech Connect

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

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

1994-01-01

136

High pressure vapor-liquid and vapor-liquid-liquid equilibria for systems containing supercritical carbon dioxide, water and furfural  

Microsoft Academic Search

We measured vapor-liquid equilibrium for a binary system CO2?furfural at temperatures of 303 and 323 K and vapor-liquid-liquid equilibrium for a ternary system CO2?water?furfural at temperatures of 303, 323 and 343 K and pressure of 5 MPa to obtain fundamental data for concentration of furfural by using three phase separation technique. Furthermore the experimental data were compared with results calculated

Takeshi Sako; Tsutomu Sugeta; Noriaki Nakazawa; Katsuto Otake; Masahito Sato; Katsuo Ishihara; Masahiro Kato

1995-01-01

137

Vapor–liquid equilibria for water + acetic acid + ( N, N-dimethylformamide or dimethyl sulfoxide) at 13.33 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data of the systems acetic acid+N,N-dimethylformamide (DMF), acetic acid+dimethyl sulfoxide (DMSO), DMSO+water, water+acetic acid+DMF, and water+acetic acid+DMSO have been measured at 13.33kPa by using an improved Rose equilibrium still. The association of acetic acid in vapor phase has been considered, and the nonideality of vapor phase was accounted for using the Hayden–O’Connell (HOC) method. The experimental

Yong Peng; Lijuan Ping; Shengli Lu; Jianwei Mao

2009-01-01

138

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

SciTech Connect

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

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

1996-05-01

139

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

SciTech Connect

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

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

1996-07-01

140

Vapor-liquid equilibrium of water-acetone-air at ambient temperatures and pressures. An analysis of different VLE-fitting methods  

SciTech Connect

The availability of accurate equilibrium data is of high importance in chemical engineering practice both for design and research purposes. It appeared that for the gas absorption system water-acetone-air in the range of special interest for absorption and desorption operations, neither literature data nor calculations following UNIFAC gave a sufficient accuracy. An experimental program was set up to determine equilibrium data with an accuracy within 2% for low acetone concentrations (up to 7 wt % gas phase) at ambient temperature (16-30/sup 0/C) and atmospheric pressure (740-860 mmHg). From experiments the activity coefficient at infinite dilution of acetone ..gamma.. is found to be 6.79 (0.01) at 20/sup 0/C and 7.28 (0.01) at 25/sup 0/C, while the total error in ..gamma.. is 1.5%. The equilibrium constant can be calculated from ..gamma.. and shows the same error. The experimental data-fitting with procedures of Margules (two parameters) and Van Laar were successful, but NRTL, Wilson, and UNIQUAC failed, probably because of the small concentration range used.

Lichtenbelt, J.H.; Schram, B.J.

1985-04-01

141

Vapor-liquid critical curve of the system ethane + 2-methylpropane  

SciTech Connect

The vapor-liquid critical curve of the binary system ethane + 2-methylpropane was determined from the critical temperature of ethane up to the critical temperature of 2-methylpropane. The results are compared with vapor-liquid equilibrium data reported earlier on this system and with the critical curve that is predicted for this system from the Peng-Robinson equation of state.

deLoos, T.W.; vanderKool, H.J.; Ott, P.L.

1986-04-01

142

A vapor–liquid phase equilibrium model for binary CO 2–H 2O and CH 4–H 2O systems above 523 K for application to fluid inclusions  

Microsoft Academic Search

Accurate prediction of both volumetric and vapor–liquid phase equilibria of binary CO2–H2O and CH4–H2O mixtures with a single equation of state proves to be difficult. In this study we use an activity–fugacity model to predict the vapor–liquid phase equilibria above 523K and adapt a Helmoholtz model to calculate volumetric properties of these two binary systems. The average deviations of water

Shide Mao; Zhenhao Duan; Wenxuan Hu

2009-01-01

143

Vapor–liquid equilibria for binary and ternary systems composed of 2-methoxy-2-methyl propane, 2-methyl-2-propanol, and octane at 101.3 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibria for 2-methoxy-2-methyl propane (MTBE)+2-methyl-2-propanol+octane and the constituent binary system MTBE+2-methyl-2-propanol have been measured at 101.3 kPa. The measurements were made in an equilibrium still with circulation of both the vapor and liquid phases. The ternary system of MTBE+2-methyl-2-propanol+octane and the binary system of MTBE+2-methyl-2-propanol are both non-azeotropic. The constituent binary systems of 2-methyl-2-propanol+octane and MTBE+octane, which were

Toshihiko Hiaki; Kazuteru Tatsuhana; Tomoya Tsuji; Masaru Hongo

1999-01-01

144

Prediction of mixture vapor–liquid equilibrium from the combined use of Peng–Robinson equation of state and COSMO-SAC activity coefficient model through the Wong–Sandler mixing rule  

Microsoft Academic Search

In this work we examined the prediction of vapor–liquid equilibria (VLE) of mixtures from the combined use of the Peng–Robinson equation of state (PR EOS) and the COSMO-SAC liquid activity coefficient model (LM). Based on the results of quantum mechanical calculations, it has been shown that the COSMO-SAC model is capable of predicting VLE of mixtures away from the critical

Ming-Tsung Lee; Shiang-Tai Lin

2007-01-01

145

(Vapour + liquid) equilibrium of binary mixtures (1,3-dioxolane or 1,4-dioxane + 2-methyl-1-propanol or 2-methyl-2-propanol) at isobaric conditions  

Microsoft Academic Search

Isobaric (vapour+liquid) equilibrium of (1,3-dioxolane or 1,4-dioxane+2-methyl-1-propanol or 2-methyl-2-propanol) at 40.0 kPa and 101.3 kPa has been studied with a dynamic recirculating still. The experimental VLE data are thermodynamically consistent. From these data, activity coefficients were calculated and correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations. The VLE results have been compared with the predictions by the

Antonio Reyes; Carlos Lafuente; José Miñones; Udo Kragl; Félix M Royo

2004-01-01

146

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

ERIC Educational Resources Information Center

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

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

2010-01-01

147

Vapor-liquid equilibria for three aldehyde/hydrocarbon mixtures  

SciTech Connect

Isothermal vapor-liquid equilibrium (VLE) data were measured for the mixtures n-pentane/propionaldehyde, n-heptane/n-butyraldehyde, and isobutyraldehyde/n-heptane at low pressures (100-1000 mmHg) by using a dynamic still. The data reported here are thermodynamically consistent according to the point-to-point consistency test. These data are correlated with five activity coefficient models with parameters estimated from the maximum likelihood method. Also, UNIFAC parameters were estimated for the aldehyde/hydrocarbon functional-group interactions based on the new data.

Eng, R.; Sandler, S.I.

1984-04-01

148

Vapor-liquid phase separator permeability results  

NASA Technical Reports Server (NTRS)

Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

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

1981-01-01

149

Isothermal vapor–liquid equilibria of the ternary system formed by ethanol, tert-amyl methyl ether and toluene  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) data are presented for the ternary system ethanol–tert-amyl methyl ether (TAME)–toluene at 333.15 K. The experimental results were measured by using a Boublik vapor–liquid recirculation still. The results are compared with values predicted from the PRSV equation of state with the modified Huron–Vidal first order (MHV1) and Wong–Sandler (WS) mixing rules. Good agreement is obtained.

Tatsuhiko Ohta; Masanari Ishio; Toshiro Yamada

1998-01-01

150

Universality in fluid domain coarsening: The case of vapor-liquid transition  

NASA Astrophysics Data System (ADS)

Domain growth during the kinetics of phase separation is studied following vapor-liquid transition in a single component Lennard-Jones fluid. Results are analyzed after appropriately mapping the continuum snapshots obtained from extensive molecular-dynamics simulations to a simple cubic lattice. For near-critical quench interconnected domain morphology is observed. A brief period of slow diffusive growth is followed by a linear viscous hydrodynamic growth that lasts for an extended period of time. This result is in contradiction with earlier reports of late-time growth exponent 1/2 that questions the uniqueness of the non-equilibrium universality for liquid-liquid and vapor-liquid transitions.

Majumder, Suman; Das, Subir K.

2011-08-01

151

Vapor–liquid equilibria for supercritical carbon dioxide+butanol systems at 313.2 K  

Microsoft Academic Search

Isothermal vapor–liquid equilibria for CO2+1-butanol and CO2+2-butanol at 313.2K were measured using a high pressure view-cell with circulation of both vapor and liquid phases. The experimental vapor–liquid equilibrium results for the CO2+1-butanol system were compared with four sets of data from literature. The results were correlated with the Peng–Robinson equation of state and the perturbed hard-sphere equation of state.

Toshihiko Hiaki; Hideki Miyagi; Tomoya Tsuji; Masaru Hongo

1998-01-01

152

Thermodynamic properties of water + normal alcohols and vapor-liquid equilibria for binary systems of methanol or 2-propanol with water  

Microsoft Academic Search

Experiments have been carried out to determine densities and refractive indices of binary and ternary mixtures of water with normal alcohols (methanol and n-butanol) at 293.15 K. Also, vapor-liquid equilibrium data have been measured for binary systems of methanol-water and 2-propanol-water at atmospheric pressure, from which the excess Gibbs free energy was computed for both systems. The experimental vapor-liquid equilibrium

Brahim Khalfaoui; Abdessalem H. Meniai; Rafael Borja

1997-01-01

153

Design of a high-pressure ebulliometer, with vapor-liquid equilibrium results for the systems CHF2 Cl + CF3 CH3 and CF3 CH2 F + CH2F2  

NASA Astrophysics Data System (ADS)

We describe the design and operation of a new high-pressure metal ebulliometer which can operate at pressures to at least 3 MPa in the range 220 400 K. Infinite-dilution activity coefficients are presented for the system CHF2Cl + CF3-CH, at 275 K and for the system CF3-CH2F + CH2F2, at 260, 230, and 300 K. The Wilson activity coellicient model and a virial coefficient model are applied to these systems, and the phase equilibrium conditions are calculated. The results are shown to agree well with predicted and with published measured values. The excess enthalpy is calculated and compared with results from a Peng Robinson equation of state. Vapor densities on the dew curves are given.

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

1996-07-01

154

Phase diagrams for liquid–liquid equilibrium of ternary poly(ethylene glycol) + di-sodium tartrate aqueous system and vapor–liquid equilibrium of constituting binary aqueous systems at T = (298.15, 308.15, and 318.15) K  

Microsoft Academic Search

Liquid–liquid equilibria (LLE) for the aqueous polyethylene glycol 4000 (PEG4000)+di-sodium tartrate system and the vapor–liquid equilibria (VLE) of the corresponding binary aqueous systems (i.e. PEG4000+water and di-sodium tartrate+water) have been determined experimentally at T=(298.15, 308.15 and 318.15)K. The effects of temperature on the binodals and tie-lines for the investigated aqueous two-phase system (ATPS), as well as the water activities obtained

Mohammed Taghi Zafarani-Moattar; Sholeh Hamzehzadeh; Shahnaz Hosseinzadeh

2008-01-01

155

A model of vapor-liquid equilibria for acid gas-alkanolamine-water systems  

Microsoft Academic Search

A physico-chemical model was developed for representing liquid phase chemical equilibria and vapor-liquid (phase) equilibria of HâSCOâ-alkanolamine-water systems. The equilibrium composition of the liquid phase is determined by minimization of the Gibbs free energy. Activity coefficients are represented with the Electrolyte-NRTL equation treating both long-range electrostatic interactions and short-range binary interactions between liquid phase species. Vapor phase fugacity coefficients are

Austgen; D. M. Jr

1989-01-01

156

Vapor-Liquid Equilibria for Some Concentrated Aqueous PolymerSolutions  

SciTech Connect

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

Striolo, Alberto; Prausnitz, John M.

1999-07-01

157

Gas solubilities, vapor-liquid equilibria, and partial molal volumes in some hydrogen-hydrocarbon systems  

SciTech Connect

Gas solubilities were measured for hydrogen in n-pentane, 2,3-dimethylbutane, cyclohexane, n-decane, m-xylene, 1,4-diethylbenzene, and 1-methylnaphthalene. Vapor-liquid equilibrium ratios (K's) were measured for the second, third, fifth, and sixth of these systems. Partial molal volumes of hydrogen dissolved in the liquid hydrocarbons were measured for all systems except methylnaphthalene. Temperatures and pressures fell in the ranges 35-320/sup 0/C and 200-2400 psi.

Connolly, J.F.; Kandalic, G.A.

1986-10-01

158

A comparison of various cubic equation of state mixing rules for the simultaneous description of excess enthalpies and vapor-liquid equilibria  

Microsoft Academic Search

Recent new mixing and combining rules for cubic equations of state (EOS) have extended the range of such equations to the accurate description of the vapor-liquid equilibria (VLE) of highly nonideal mixtures. However, the simultaneous correlation and\\/or prediction of vapor-liquid equilibrium (VLE) and liquid mixture excess enthalpies (Hex) by either activity coefficient models or equations of state has been a

Hasan Orbey; Stanley I. Sandler

1996-01-01

159

Isothermal vapor-liquid equilibria for water + 2-aminoethanol + dimethyl sulfoxide and its constituent three binary systems  

Microsoft Academic Search

Isothermal vapor-liquid equilibria were measured for the ternary system water + 2-aminoethanol + dimethyl sulfoxide and its three constituent binary mixtures at 363.15 K. The apparatus used was a modified Rogalski-Malanoski equilibrium still. The experimental binary data were correlated by the NRTL equation. The ternary system was predicted using the binary NRTL parameters with good accuracy.

Katsumi Tochigi; Kentarou Akimoto; Kenji Ochi; Fangyhi Liu; Yasuhito Kawase

1999-01-01

160

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

SciTech Connect

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

161

An extension to the UNIFAC group assignment for prediction of vapor-liquid equilibria of mixtures containing refrigerants  

Microsoft Academic Search

All previously published vapor-liquid equilibrium data points for binary mixtures containing fluorinated hydrocarbons have been taken into account to develop an extension to the UNIFAC group assignment for common refrigerants. It is shown that ten new main groups are necessary to describe all the various forms of halogenated refrigerants. The accuracy of this extension is within the range usually obtained

Michael Kleiber

1995-01-01

162

VaporLiquid equilibrium in the methanol — Water — Methyl methoxyacetate system  

Microsoft Academic Search

Methyl methoxyacetate (HI) is the starting material in one of the syntheses of pyridoxine (vitamin t~), and is obtained by the esterification of chloroacetic acid with methanol in the presence of calcium chloride. After the separation of the aqueous solution of calcium chloride, methyl chloroacetate is methoxylated by a methanolic solution of sodium methoxide [1]. This reaction yields a mixture,

M. M. Avrutskii; M. V. Balyakina; G. E. Boksha; N. K. Nazarova; T. G. Pavlenko; V. V. Zarutskii; V. I. Gunar

1978-01-01

163

Vapor-liquid equilibria for the ternary system acetone + methanol + chlorobenzene at 101.325 kPa  

SciTech Connect

Distillation has been used as an effective method of separation in the chemical processing industry, and vapor liquid equilibrium (VLE) data are essential for development, design, and simulation of separation sequences of mixtures. Therefore, the purpose of the study of the thermodynamic equilibrium in the current mixture is the attractive possibility of the application of chlorobenzene as the solvent in the acetone + methanol extractive rectification, using a reverse volatility separation process. This paper reports vapor-liquid equilibrium results from the acetone + methanol + chlorobenzene mixture at a constant pressure of 101.325 kPa. The equilibrium data have been compared with those predicted by ASOG, UNIFAC, UNIFAC-Dortmund, UNIFAC-Lyngby group contributed methods, with lower standard deviations of the vapor molar fraction and temperature being calculated by the latter.

Orge, B.; Iglesias, M.; Dominguez, A.; Tojo, J. [Univ. de Vigo (Spain). Dept. de Ingenieria Quimica

1995-11-01

164

Vapor-liquid equilibria for solutions of dendritic polymers  

SciTech Connect

Vapor-liquid equilibrium data were obtained for dendritic polymer solutions using a classic isothermal gravimetric-sorption method; the amount of solvent absorbed by the dendrimer was measured at increasing solvent activity. The polymers were polyamidoamine (PAMAM) dendrimers of generations 1, 2, and 4 and benzyl ether dendrimers with different end groups (aromatic rings, dodecyl chains, methyl ester groups, perfluoroalkyl chains) of generations 2 to 6, and two series of benzyl ether linear polymers that are analogues of the dendrimers. Solvents were acetone, acetonitrile, chloroform, cyclohexane, methanol, n-pentane, n-propylamine, tetrahydrofuran, and toluene. The temperature range was 35 to 89 C. The amount of solvent absorbed by the dendrimers depends, sometimes strongly, on the kind of dendrimer end groups. The relation between solvent absorption and dendrimer generation number, or molecular weight, depends on the solvent-dendrimer system and on temperature. Solvent absorption in linear polymers is below that for corresponding dendrimers, all or in part owing to crystallinity in the linear polymers.

Mio, C.; Kiritsov, S.; Thio, Y.; Brafman, R.; Prausnitz, J. [Univ. of California, Berkeley, CA (United States). Chemical Engineering Dept.] [Univ. of California, Berkeley, CA (United States). Chemical Engineering Dept.; [Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.; Hawker, C.; Malmstroem, E.E. [IBM Almaden Research Center, San Jose, CA (United States). Center for Polymeric Interfaces and Macromolecular Assemblies] [IBM Almaden Research Center, San Jose, CA (United States). Center for Polymeric Interfaces and Macromolecular Assemblies

1998-07-01

165

High-pressure vapor-liquid equilibria involving mixtures of nitrogen, carbon dioxide, and eta-butane  

Microsoft Academic Search

A new high-pressure vapor-liquid equilibrium apparatus has been constructed with the capability of measuring the compositions and densities of the coexisting equilibrium phases at constant temperature and\\/or pressure. This apparatus was tested with the carbon dioxide + n-butane system with excellent agreement observed between our results and previously published data. Data are also reported for the nitrogen + n-butane system

Steven K. Shibata; Stanley I. Sandler

1989-01-01

166

Molecular dynamics simulation for vapor-liquid coexistence of water in nanocylinder  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation was conducted in order to investigate the vapor-liquid coexistence of the water molecules in nanopore. In this research, the Lennard-Jones energy parameter between a water molecule and an atom of nanopore was optimized so as to model the contact angle between a water droplet and the carbon material in the fuel cell. The TIP4P/2005 as the model of a water molecule was used; this model produces well the vapor-liquid coexistence line. All of the systems were equilibrated by Nosé-Hoover thermostat. The electrostatic interaction between water molecules was calculated through smooth particle mesh Ewald method. First, we equilibrated a water plug in the single-wall atomistic nanocylinder as a model of nanopore in the fuel cell with radius 1.3nm. Water molecules burst from an interface of the water plug in equilibration. Then, the equilibrium densities both in dense and dilute region ware sampled over 1 ns. The vapor-liquid coexistence line, density profile, free energy profile will be presented in the session.

Mima, Toshiki; Kinefuchi, Ikuya; Yoshimoto, Yuta; Miyoshi, Nobuya; Fukushima, Akinori; Tokumasu, Takashi; Takagi, Shu; Matsumoto, Yoichiro

2013-03-01

167

Prediction of vapor-liquid equilibria of associating mixtures with UNIFAC models that include association  

SciTech Connect

Two UNIFAC association models are developed using Wertheim`s theory of association rather than a chemical theory. In both models the activity coefficient is the sum of combinatorial, residual, and association contributions. The UNIFAC group-contribution model is used for the combinatorial and residual terms, and two different types of association models are considered. The UNIFAC-AG model uses functional-group-based association, while the UNIFAC-AM model considers association to occur between molecules. For associating mixtures containing acids, alcohols, or water, both activity coefficient models provide better predictions of binary vapor-liquid equilibria than the original UNIFAC model. Of those models, the UNIFAC-AM model led to the best predictions. The association term was also added to the more recent, modified UNIFAC model and briefly tested with vapor-liquid equilibrium data for the acetic acid + heptane and acetic acid + butanol mixtures. It was found that, for vapor-liquid equilibria, the modified UNIFAC + association model is only slightly better than the UNIFAC-AM model. However, the modified UNIFAC + association model has four more adjustable parameters than the UNIFAC-AM model. Therefore, use of the UNIFAC-AG or UNIFAC-AM models is recommended.

Fu, Y.H.; Orbey, H.; Sandler, S.I. [Univ. of Delaware, Newark, DE (United States)] [Univ. of Delaware, Newark, DE (United States)

1996-12-01

168

Measurement and prediction of vapor–liquid equilibria of ternary systems containing ionic liquids  

Microsoft Academic Search

For the first time vapor–liquid equilibrium (VLE) data for ternary systems containing ionic liquids are reported. The data were measured by means of a computer-operated static VLE apparatus at 353.15K with the ionic liquids 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM]+[(CF3SO2)2N]? and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM]+[(CF3SO2)2N]? and acetone, 2-propanol and water. The experimental VLE data of the binary systems were correlated using the Wilson, NRTL

Michael Döker; Jürgen Gmehling

2005-01-01

169

Vapor-liquid and liquid-liquid equilibria and critical states of water + n-decane mixtures  

SciTech Connect

Mixtures of water and hydrocarbons exhibit a rich variety of fluid phase behavior that is of technological interest because of the common occurrence of these mixtures in chemical processes, in oil reservoirs, in the environment, and other instances. The weak interaction between water and hydrocarbon molecules contrasts sharply with the strong interaction between water and water molecules in the same mixture. The extreme dissimilarity of the molecular interactions manifested as highly non-ideal solution behavior invites unusual attention. Vapor-liquid equilibrium and liquid-liquid equilibrium are observed in disjointed regions at 573.2, 593.2, and 613.2 K for mixtures of water +n-decane at pressures up to 230 bar. Vapor-liquid critical states are determined at the temperatures studied.

Wang, Qi; Chao, Kwangchu (Purdue Univ., West Lafayette, IN (United States))

1990-01-01

170

High-pressure vapor-liquid equilibria of the binary mixtures nitrogen + n-butane and argon + n-butane  

Microsoft Academic Search

High-pressure vapor-liquid equilibrium composition and density data of the binary systems nitrogen + n-butane (at 339.4 and 380.2 K) and argon + n-butane (at 340.0 and 380.1 K) are reported. The data sets sere fit with the Peng-Robinson equation of state using both generalized and fluid-specific temperature-dependent parameters. The binary interaction parameters so obtained are reported.

Martin K. F. Malewski; Stanley I. Sandler

1989-01-01

171

Vapor-liquid equilibria for the difluoromethane (HFC-32) + 1,1,1-trifluoroethane (HFC-143a) system  

SciTech Connect

Isothermal vapor-liquid equilibrium data of the binary system of difluoromethane (HFC-32) + 1,1,1-trifluoroethane (HFC-143a) were obtained in the temperature range from 263.15 K to 313.15 K. Temperature, pressure, and compositions of the liquid and vapor phases were measured with a circulation type apparatus. The experimental data were correlated with the Canahan-Starling-De Santis, Peng-Robinson, and Redlich-Kwong-Soave equations of state.

Kim, C.N.; Park, Y.M.

2000-02-01

172

Nanoporous quantum filters: inside vapor-liquid transitions of quantum fluids in nanopores.  

PubMed

We study the impact of quantum fluctuations on the phase diagram of a realistic quantum liquid, namely, neon confined in atomistic carbon nanopores at 35 K. Due to the action of attractive solid-fluid potential, both classical and quantum neon vapor condense at lower pressures in carbonaceous nanopores than bulk neon. However, we found that continuous van der Waals s-shaped isotherms, which include stable, metastable, and unstable states computed from classical simulations, are shifted to lower values of pressures in comparison to those from path integral calculations. This systematic underestimation of equilibrium vapor-liquid transition pressures as well as spinodals in classical simulations is caused by neglecting the zero-point motion of adsorbed neon at 35 K. Delocalized neon atoms excluded more volume in the adsorbed phase than the classical neon particles. Thus, adsorbed and compressed liquidlike phases of quantum neon in the studied nanopores are characterized by lower densities than their classical counterparts. Interestingly, equilibrium vapor-liquid transition pressures of confined neon at 35 K computed from classical simulations are shifted to lower values in comparison to those computed from quantum simulations by approximately 30% for different pore sizes. Simulations of classical neon at higher effective temperatures reveal that liquidlike phases of confined quantum neon at 35 K look like classical ones at higher effective temperature of 37 K. Our calculations clearly show that quantum fluctuations cannot be neglected in calculations of phase transitions of quantum fluids at cryogenic temperatures. PMID:20345103

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

2010-04-22

173

Combination downflow-upflow vapor-liquid separator  

DOEpatents

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

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

1987-03-10

174

Thermomigration of Biphase Vapor-Liquid Droplets in Solids.  

National Technical Information Service (NTIS)

The thermomigration of biphase vapor-liquid droplets was studied in KCl as a function of droplet size and the relative proportions of gas and liquid phases in the droplets. Droplets containing more than 10 vol. % of gas migrated down thermal gradients tow...

H. E. Cline T. R. Anthony

1971-01-01

175

Vapor + liquid equilibria for the ternary system methane + ethane + carbon dioxide at 230 K and its constituent binaries at temperatures from 207 to 270 K  

SciTech Connect

Vapor-liquid equilibrium data for the binary system methane + carbon dioxide were measured at 230, 250, and 270 K. The ethane + carbon dioxide system was studied at 207, 210, 213, 230, 250, and 270 K, and the methane + ethane system was studied at 210, 230, 250, and 270 K. Ternary vapor-liquid equilibria for the methane + ethane + carbon dioxide system were measured at 230 K over the pressure range from 1.15 to 6.59 MPa. The Peng-Robinson equation of state was used to model the systems, and binary interaction coefficients are reported.

Wei, M.S.W. [CER Corp., Henderson, NV (United States); Brown, T.S. [Conoco Inc., Ponca City, OK (United States); Kidnay, A.J.; Sloan, E.D. [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering

1995-07-01

176

Vapor-liquid equilibria in the carbon dioxide + 1-propanol system  

SciTech Connect

High-pressure vapor-liquid equilibrium measurements of CO{sub 2} + alkanol systems are of interest due to their importance in the supercritical extraction of thermally labile compounds, dehydration of alcohols using supercritical carbon dioxide, and extraction of natural products using near critical solvents. Vapor-liquid equilibria for CO{sub 2} + 1-propanol mixtures have been measured at 315.0, 326.5, and 337. K using a high-pressure flow apparatus. The pressure in the experiments varied from 26.38 to 89.7 MPa. Data at 315.0 K were found to be significantly different from the data reported by Suzuki et and Yao et al. However, the results at 337.2 K are in good agreement with the results of Suzuki et al and the data appear to be more consistent with the trends exhibited by other CO{sub 2} + 1-alkanol mixture The data were correlated with Patel-Teja and Peng-Robinson equations of state using classical van de Waals one-fluid mixing rules and with the Peng-Robinson-Stryjek-Vera equation of state using the Wong-Sandler mixing rules.

Vandana, V.; Teja, A.S. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical Engineering

1995-03-01

177

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

178

Silicon nanowire synthesis by a vapor-liquid-solid approach  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

179

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

SciTech Connect

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

180

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

SciTech Connect

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

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

2011-10-13

181

Vapor-liquid equilibria of cyclohexanol with carbon dioxide, ethane, or nitrogen at elevated pressures  

SciTech Connect

Vapor-liquid equilibrium (VLE) data were measured for the binary systems of cyclohexanol with carbon dioxide, ethane, or nitrogen at temperatures from 333.15 K to 453.15 K and pressures up to 190 bar. The saturated vapor compositions were correlated with the density of the light components. Henry`s constants of the gases dissolved in cyclohexanol were calculated with the aid of the Krichevsky-Ilinskaya equation. The new VLE data were also correlated by the Peng-Robinson and the Patel-Teja equations of state. In general, the Patel-Teja equation incorporating the one-fluid, two-parameter van der Waals mixing rule yielded the best representation.

Chen, J.T.; Lee, M.J. [National Taiwan Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering] [National Taiwan Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering

1996-03-01

182

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

SciTech Connect

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

183

Measurement of vapor–liquid equilibria for the binary mixture of propylene (R-1270) + propane (R-290)  

Microsoft Academic Search

Isothermal vapor–liquid equilibria data for the binary mixture of propylene (R-1270)+propane (R-290) at 273.15, 278.15, 283.15, 293.15, 303.15 and 313.15K were measured by using a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson equation of state (PR-EOS) combined with the Wong–Sandler mixing rule. It is confirmed that the data calculated by this equations of state are in

Quang Nhu Ho; Kye Sang Yoo; Byung Gwon Lee; Jong Sung Lim

2006-01-01

184

Vapor-liquid equilibria for the ternary system 2-propanol-chloroform-benzene at 50°C  

Microsoft Academic Search

Vapor-liquid equilibrium (VLE) measurements were made for the 2-propanol-chloroform and 2-propanol-chloroform-benzene systems at 50°C. VLE data for the two constituent binaries at 50 °C have been reported: 2-propanol-benzene (1); chloroform-benzene (2). The apparatus for experimental work is a Boublik vapor-recirculating still described by Ohta et al. (3). All first-grade chemicals supplied were purified for VLE measurements. 2-Propanol was distilled in

Isamu Nagata

1985-01-01

185

Vapor-liquid equilibria in the systems of toluene/aniline, aniline/naphthalene, and naphthalene/quinoline  

SciTech Connect

This paper reports on vapor-liquid equilibria for the aniline/naphthalene, toluene/aniline, and naphthalene/quinoline systems that have been determined at 0-1500 kPa and 490-623 K by using a static equilibrium cell. The data can be accurately correlated with the modified Peng-Robinson equation of state by using density-dependent mixing rules. The binary interaction parameters and correction factors for the equation of state are reported at each isotherm. The presence of coal-derived solids in these binary systems did not influence any of the binary bubble pressures.

Lee, C.H.; Mohamed, R.S.; Holder, G.D. (Chemical And Petroleum Engineering Dept., Univ. of Pittsburgh, Pittsburgh, PA (US))

1992-04-01

186

Isothermal vapor–liquid equilibria of octane with 1-butanol, 2-butanol, or 2-methyl-2-propanol  

Microsoft Academic Search

Isothermal vapor–liquid equilibria were measured for three binary systems of 1-butanol+octane at 373.15 K, 2-butanol+octane at 358.15 K, and 2-methyl-2-propanol+octane at 343.15 K. The measurements were made in a Rogalski–Malanowski type equilibrium still with circulation of both the vapor and liquid phases. Three binary isothermal systems form a maximum pressure azeotrope. The azeotropic data are x1(AZ)=0.519 mole fraction and P(AZ)=75.71

Toshihiko Hiaki; Akira Taniguchi; Tomoya Tsuji; Masaru Hongo

1998-01-01

187

Vapor-liquid equilibria for the difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a) system  

SciTech Connect

Isothermal vapor-liquid equilibrium data of the binary mixture of difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a) have been measured in the temperature range between 263 K and 323 K. The experiment was carried out with a circulation type apparatus with the measurement of temperature, pressure, and compositions of the liquid and vapor phases. The experimental data were correlated with the Peng-Robinson and Redlich-Kwong-Soave equations of state, and comparison with literature results has been made.

Chung, E.Y.; Kim, M.S. [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering] [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering

1997-11-01

188

Equilibrium  

NSDL National Science Digital Library

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

189

Effect of uniform electric field on homogeneous vapor-liquid nucleation and phase equilibria. II. Extended simple point charge model water  

Microsoft Academic Search

The effects of a uniform electric field on homogeneous vapor-liquid nucleation of the extended simple point charge (SPC\\/E) model water have been simulated. A grand canonical Monte Carlo simulation approach [I. Kusaka et al., J. Chem. Phys. 108, 3416 (1998)], which directly gives the equilibrium distribution of physical clusters, is employed to calculate the formation free energy of the SPC\\/E

G. T. Gao; K. J. Oh; X. C. Zeng

1999-01-01

190

BINARY AND MULTICOMPONENT VAPOR-LIQUID EQUILIBRIA OF SYNTHESIS GAS COMPONENTS, METHANOL AND WATER WITH TETRA ETHYLENE GLYCOL DIMETHYL ETHER (TETRAGLYME)  

Microsoft Academic Search

Binary and multicomponent vapor-liquid equilibria of synthesis gas components (H2, CO, CH4, and CO2), methanol and water with tetraethylene glycol dimethyl ether (tetraglyme) were studied experimentally at temperatures (473–513 K) and pressures (5.3–10.4 MPa) typical of the conventional vapor phase methanol synthesis. Both vapor and liquid phases were sampled directly and analyzed by gas chromatography. Solubilities were expressed in terms of equilibrium

PANKAJ KHOSLA; CHANDRASEKHAR KRISHNAN; J. RICHARD ELLIOTT Jr; J. M. BERTY

1991-01-01

191

Correlation of vapor-liquid equilibria for binary mixtures with free energy-based equation of state mixing rules: Carbon dioxide with alcohols, hydrocarbons, and several other compounds  

Microsoft Academic Search

The correlation of vapor-liquid equilibrium data for high-pressure carbon dioxide systems is of interest in a number of industrial\\u000a applications, including supercritical extraction. Here, we consider the correlation of data for 12 binary systems of carbon\\u000a dioxide separately with alcohols, with hydrocarbons, and with acetone, benzene, and water. The Wong-Sandler (W-S) and modified\\u000a Huron — Vidal first order (MHV1) free

Chul Kwak; Stanley I. Sandler; Hun-Soo Byun

2006-01-01

192

Isothermal vapor-liquid equilibria for the 2-propanol + water system containing poly(ethylene glycol) at 298.15 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibrium measurements were performed for the 2-propanol + water system containing poly(ethylene glycol) (PEG) at 298.15 K by a flow type apparatus. Three different PEGs whose molecular weights are 200, 1000, and 20,000 were employed, and their mass fractions in the liquid phase were up to 0.35. The volatility of water was reduced by the addition of PEG,

Tomoya Tsuji; Kozo Hasegawa; Toshihiko Hiaki; Masaru Hongo

1996-01-01

193

Isothermal vapor-liquid equilibria for 1,1,1,2-tetrafluoroethane + propane and propane + 1,1,1,-trifluoroethane at 283.18 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibria (VLE) for the binary systems 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) and propane + 1,1,1-trifluoroethane (R143a) were measured at 283.18 K using a recirculation apparatus in which the vapor phase was forced through the liquid. The phase composition at equilibrium was measured by gas chromatography, calibrating its response using gravimetrically prepared mixtures. The data were correlated using the

Roman Stryjek; Sergio Bobbo; Roberto Camporese

1998-01-01

194

Measurement of vapor–liquid equilibria for the binary mixture of propylene (R-1270) + 1,1,1,2-tetrafluoroethane (HFC134a)  

Microsoft Academic Search

Isothermal vapor–liquid equilibria data for the binary mixture of propylene (R-1270) + 1,1,1,2-tetrafluoroethane (HFC-134a) at five equally spaced temperatures between 273.15 and 313.15K were measured by using a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson equation of state (PR-EOS) combined with the Wong–Sandler mixing rule. It was confirmed that the data calculated by this equations of

Quang Nhu Ho; Byung Gwon Lee; Ji-Young Park; Jae-Duck Kim; Jong Sung Lim

2004-01-01

195

High pressure vapor-liquid equilibria of binary mixtures composed of HFC32, 125, 134a, 143a, 152a, 227ea and R600a (isobutane)  

Microsoft Academic Search

The vapor–liquid equilibrium data for six binary mixtures of isobutane+HFC-32, +HFC-125, +HFC-134a, +HFC-143a, +HFC-152a, and +HFC-227ea were correlated with the Peng–Robinson–Stryjek–Vera (PRSV) EOS combined with the NRTL excess free energy model and original Huron–Vidal (HVO) mixing rules. Almost all the calculated values with these models give good agreement with the experimental data. In addition, the nonideality of these binary mixtures

Ji Young Park; Jong Sung Lim; Byung Gwon Lee

2002-01-01

196

Vapor-liquid-solid growth of endotaxial semiconductor nanowires.  

PubMed

Free-standing and in-plane lateral nanowires (NWs) grown by the vapor-liquid-solid (VLS) process have been widely reported. Herein, we demonstrate that the VLS method can be extended to the synthesis of horizontally aligned semiconductor NWs embedded in substrates. Endotaxial SiGe NWs were grown in silicon substrates by tuning the directional movement of the catalyst in the substrates. The location of the SiGe NWs can be controlled by the SiO(2) pattern on the silicon surface. By varying the growth conditions, the proportion of Ge in the obtained NWs can also be tuned. This approach opens up an opportunity for the spatial control of the NW growth in substrates and can potentially broaden the applications of NWs in new advanced fields. PMID:23066984

Li, Shaozhou; Huang, Xiao; Liu, Qing; Cao, Xiehong; Huo, Fengwei; Zhang, Hua; Gan, Chee Lip

2012-11-14

197

APPLICATION OF THE SCLC MODEL TO THE SALT EFFECT IN VAPOR-LIQUID EQUILIBRIA  

Microsoft Academic Search

The ability of the rationalized SCLC model to correlate data on the salt effect in vapor-liquid equilibria is examined in this work. For a system consisting of two miscible solvents the effect of salt in altering the relative volatility is represented by the model with four adjustable binary interaction parameters. The model is shown to correlate vapor-liquid equilibria of several

K. V. NARAYANAN; M. S. ANANTH

1995-01-01

198

Application of UNIFAC models for prediction of vapor–liquid and liquid–liquid equilibria relevant to separation and purification processes of crude biodiesel fuel  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) of the methanol–biodiesel (BDF)\\/glycerin binary system and liquid–liquid equilibrium (LLE) of the water–BDF binary system and the methanol–BDF–glycerin and methanol–water–BDF ternary systems were predicted using several UNIFAC models: the latest original UNIFAC model, Kikic’s model, Fornari’s model, Dortmund-UNIFAC model, and LLE-UNIFAC model. The former VLE and latter LLE are used to design methanol recovery processes and separation

Hidetoshi Kuramochi; Kouji Maeda; Satoru Kato; Masahiro Osako; Kazuo Nakamura; Shin-ichi Sakai

2009-01-01

199

Vapor-liquid equilibria for the binary systems of benzene/toluene, diphenylmethane/toluene, m-cresol/1,2,3,4-tetrahydronaphthalene, and quinoline/benzene  

SciTech Connect

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

200

Vapor-liquid equilibria in the systems of n-decane/tetralin, n-hexadecane/tetralin, n-decan/1-methylnaphthalene, and 1-methylnaphthalene/tetralin  

SciTech Connect

Vapor-liquid equilibrium data for the binary systems of n-decane/tetralin, n-hexadecane/tetralin, n-decane/1-methyinaphthalene, and 1-methyinaphthalene/tetralin were measured at a low to moderate pressure (0 - 1123 kPa) by using a static equilibrium cell. The binary P-x data were isothermally correlated using the modified Peng-Robinson equation of state to describe both vapor and liquid phases at 473.15, 533.15, and 573.15 K. In this paper interaction parameters for density-dependent mixing rules are reported at each isotherm.

Lee, C.H.; Dempsey, D.M.; Mohamed, R.S.; Holder, G.D. (Chemical and Petroleum Engineering Dept., Univ. of Pittsburgh, Pittsburgh, PA (US))

1992-04-01

201

Measurement of vapor–liquid equilibria for the binary systems of propane + 1,1,1,2-tetrafluoroethane and 1,1,1-trifluoroethane + propane at various temperatures  

Microsoft Academic Search

Isothermal vapor–liquid equilibrium data for the binary systems of propane+1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1-trifluoroethane (HFC-143a)+propane (HC-290) were measured at 273.15, 283.15, 293.15, 303.15, 313.15 and 323.15K, and 268.15, 278.15, 298.15, 308.15, and 318.15K, respectively. The experiments were carried out using a circulation-type equilibrium apparatus with the measurement of temperature, pressure, and the compositions of the liquid and vapor phases. The experimental

Jong Sung Lim; Ji-Young Park; Jeong Won Kang; Byung-Gwon Lee

2006-01-01

202

Group-contribution equation of state for the prediction of vapor-liquid equilibria of mixtures containing hydrofluorocarbons and alkanes  

SciTech Connect

This work is aimed to present and validate a thermodynamic model that enables the prediction of vapor-liquid equilibria of refrigerant mixtures of alkanes and hydrofluorocarbons, in the temperature and pressure ranges of interest for refrigeration cycles and heat pump applications. A modified Redlich-Kwong-Soave equation of state is used with Huron-Vidal mixing rules and a modified UNIFAC group-contribution approach for calculating the component infinite-pressure activity coefficients. A new classification of functional groups is suggested, and the values of interaction parameters between groups are provided. These parameters are regressed from selected binary vapor-liquid equilibrium data. A good regression is obtained for all group pairs, with a maximum root-mean-square deviation on relative pressure residuals of 1.86%. The proposed method is totally predictive since only the structure, critical constants, and vapor pressure of pure components are needed in order to calculate4 thermodynamic properties of refrigerant mixtures. Results for a number of binary and ternary mixtures are reported and compared to available experimental data.

Elvassore, N.; Barolo, M.; Bertucco, A. [Univ. di Padova (Italy). Ist. di Impianti Chimici] [Univ. di Padova (Italy). Ist. di Impianti Chimici

1998-08-01

203

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

PubMed

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

Rajesh, John Anthuvan; Pandurangan, Arumugam

2014-04-01

204

Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase  

USGS Publications Warehouse

A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

Moench, A. F.; Atkinson, P. G.

1978-01-01

205

Magnetotail dynamics under isobaric constraints  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

206

Riemannian geometry study of vapor-liquid phase equilibria and supercritical behavior of the Lennard-Jones fluid.  

PubMed

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

207

Riemannian geometry study of vapor-liquid phase equilibria and supercritical behavior of the Lennard-Jones fluid  

NASA Astrophysics Data System (ADS)

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.

May, Helge-Otmar; Mausbach, Peter

2012-03-01

208

Steady-state, vapor-liquid concurrent flow: Relative permeabilities and end effects.  

National Technical Information Service (NTIS)

Steady-state methods are commonly used for the determination of the relative permeabilities of single component vapor-liquid systems, such as steam-water. Even though such experiments are performed under adiabatic conditions, the interpretation of results...

M. Parlar M. Zeybek Y. C. Yortsos

1990-01-01

209

Design of a high-pressure ebulliometer, with vapor-liquid equilibrium results for the systems CHF{sub 2}Cl + CF{sub 3}-CH{sub 3} and CF{sub 3}-CH{sub 2} F+CH{sub 2}F{sub 2}  

SciTech Connect

The authors describe the design and operation of a new high-pressure metal ebulliometer which can operate at pressures to at least 3 MPa in the range 220-400 K. Infinite-dilution activity coefficients are presented for the system CHF{sub 2}Cl + CF{sub 3}-CH{sub 3} at 275 K and for the system CF{sub 3}-CH{sub 2}F + CH{sub 2}F{sub 2} at 260, 280, and 300 K. The Wilson activity coefficient model and a virial coefficient model are applied to these systems, and the phase equilibrium conditions are calculated. The results are shown to agree well with predicted and with published measured values. The excess enthalpy is calculated and compared with results from a Peng-Robinson equation of state. Vapor densities on the dew curves are given.

Weber, L.A.; Silva, A.M. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1996-07-01

210

Improvement of predictive accuracy of the UNIFAC model for vapor-liquid equilibria of polymer solutions  

Microsoft Academic Search

The UNIFAC model is extended to the prediction of vapor-liquid equilibria of polymer solutions using a proposed relation between the volume parameter r(n) for an n-mer polymer and that r(1) for the monomer. The modified UNIFAC model does not require a free-volume term as does the UNIFAC-FV model. As a result, no additional information is needed for the vapor-liquid equilibria

Chongli Zhong; Yoshiyuki Sato; Hirokatsu Masuoka; Xiaoning Chen

1996-01-01

211

A model of vapor-liquid equilibria for acid gas-alkanolamine-water systems  

SciTech Connect

A physico-chemical model was developed for representing liquid phase chemical equilibria and vapor-liquid (phase) equilibria of H{sub 2}SCO{sub 2}-alkanolamine-water systems. The equilibrium composition of the liquid phase is determined by minimization of the Gibbs free energy. Activity coefficients are represented with the Electrolyte-NRTL equation treating both long-range electrostatic interactions and short-range binary interactions between liquid phase species. Vapor phase fugacity coefficients are calculated using the Redlich-Kwong-Soave Equation of State. Adjustable parameters of the model, binary interaction parameters and carbamate stability constants, were fitted on published binary system alkanolamine-water and ternary system (H{sub 2}S-alkanolamine-water, CO{sub 2}-alkanolamine-water) VLE data. The Data Regression System of ASPEN PLUS, based upon the Maximum Likelihood Principle, was used to estimate adjustable parameters. Ternary system measurements used in parameter estimation ranged in temperature from 25 to 120{degree}C in alkanolamine concentration from 1 to 5 M, in acid gas loading from 0 to 1.5 moles per mole alkanolamine, and in acid gas partial pressure from 0.1 to 1,000 kPa. Maximum likelihood estimates of ternary system H{sub 2} or CO{sub 2} equilibrium partial pressures and liquid phase concentrations were found to be in good agreement with measurements for aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), diglycolamine (DGA), and methyldiethanolamine (MDEA) indicating that the model successfully represents ternary system data. The model was extended to represent CO{sub 2} solubility in aqueous mixtures of MDEA with MEA or DEA. The solubility was measured at 40 and 80{degree}C over a wide range of CO{sub 2} partial pressures. These measurements were used to estimate additional binary parameters of the mixed solvent systems.

Austgen, D.M. Jr.

1989-01-01

212

Some effects of vapor-liquid flow ratio on performance of a trickle-bed reactor  

SciTech Connect

In the correlation of data from trickle-bed reactors results are frequently presented in terms of liquid hourly space velocities (LHSV) based on liquid feed to the reactor regardless of the extent to which the various components of the liquid may be vaporized within the reactor. This especially the case in petroleum and fuels processing where feed compositions are so complex chemically that a rudimentary kinetic expression frequently suffices. However in fact reactants and reaction intermediates of significant volatility will distribute themselves between the liquid and vapor phases. This distribution is affected not only by pressure and temperature, but also by the ratio of the flow rates of liquid and vapor and by liquid holdup in the reactor. This ratio and liquid holdup can thus affect reactant liquid concentrations in contact with the catalyst and hence conversion and selectivity. For a specified liquid hourly space velocity in a trickle bed reactor the degree of conversion of any reactant of appreciable volatility will usually descrease with increasing gas/liquid ratio. No effect will be observed with a true zero order reaction and the magnitude of the effect will be greater, the higher the order of reaction. For a reaction in equilibrium, here quinoline and PyTHQ, the equilibrium ratio can be affected by their relative volatilities which in turn can affect the rate of subsequent reactions. However the overall hydrodenitrogenation reaction of quinoline and N-containing organic intermediates is only marginally greater than zero order under the conditions studied and hence the percent HDN converison is little affected by gas-liquid ratio or vapor phase versus vapor-liquid reaction. 10 refs., 5 figs.

Smith, C.M.; Satterfield, C.N.

1985-01-01

213

High-pressure vapor-liquid equilibria in the propane-1-propanol system  

SciTech Connect

High-pressure isothermal vapor liquid equilibrium data were measured for the propane-1-propanol system at 81.6, 105.2, and 120.1 C in a static equilibrium cell with liquid-phase sampling by a piston-driven sampling rod and homogenizing the sample with a static jet mixer. The vapor phase was sampled by releasing it into an evacuated manifold, and the gas chromatograph was calibrated with a new variable volumetric device. Satisfactory modeling was achieved with the combined method using the UNIQUAC equation with equations of sate: the group contribution EOS, Peng-Robinson EOS, or the two-parameter Virial EOS. Differences between the measured and calculated vapor-phase mole fractions, however, were significant for the lower pressure regions of the 81.6 and 120.1 C isotherms. UNIQUAC parameters, hitherto unavailable, with fairly strong temperature dependence in the 81.6 to 120.1 C range are proposed for the system. The covariance matrix indicated a significant correlation among the parameters. The classical mixing rule interaction parameters required for the original Peng-Robinson EOS in the combined method were obtained using the direct method and were temperature-independent for the isotherms for which the propane was supercritical. The possibility of propane/1-propanol immiscibility was theoretically examined according to the criteria of Baker et al. The plots of Gibbs energy of mixing vs. phase mole fractions did not indicate liquid-phase splitting, but the inferences are EOS-dependent and must await visual confirmation. The authors earlier vapor-phase thermodynamic consistency test indicated the data for all three data sets not to be inconsistent.

Muehlbauer, A.L.; Raal, J.D. (Univ. of Natal, Durban (South Africa))

1993-04-01

214

Vapor-liquid equilibrium data on water-substitute gas components: N/sub 2/-H/sub 2/O, H/sub 2/-H/sub 2/O, CO-H/sub 2/O, H/sub 2/-CO-H/sub 2/O, and H/sub 2/S-H/sub 2/O  

SciTech Connect

Project 758, initiated in 1976, comprises an experimental program to generate phase equilibrium data on gaseous components with water. Prior to formulating the project, a literature survey reported in RR-36 was conducted to determine the extent and quality of existing data in the area. One conclusion resulting from the survey is limited data exist for water-hydrocarbon systems and their quality varies from average to poor. Therefore, an extensive data development program is envisioned. Initial efforts to develop an experimental method to acquire accurate data rapidly have proved unsuccessful to date, thus delaying data generation. Consequently, the data summarized in the ensuing RR-41 were obtained by established, classical techniques for measuring phase equilibria. With the exception of hydrogen sulfide, the four gaseous components studied in this investigation are related primarily to substitute gas production. However, investigations currently in progress or planned will include natural gas and associated components as well as substitute gas constituents with water. The ultimate goal of the project is to provide adequate data from which existing correlations capable of predicting water-phase equilibria may be improved significantly, or if desirable, new models may be developed. 3 references, 11 figures, 6 tables.

Gillespie, P.C.; Wilson, G.M.

1980-04-01

215

Vapor-liquid equilibria of binary mixtures of alkanols with alkanes from atmospheric pressure to the critical point  

SciTech Connect

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 systems, the model parameters used were fit to data on the lowest-temperature isotherm and then higher-temperature isotherms were successfully predicted with those parameters. False phase splitting was avoided by using a constrained parameter fit. For highly asymmetric (in size) alkanol + alkane binaries four parameters were necessary for an accurate representation of the data, while for less asymmetric alkanol + alkane binaries only two parameters were used.

Orbey, H. [Middle East Technical Univ., Ankara (Turkey); Sandler, S.I. [Univ. of Delaware, Newark, DE (United States)

1995-05-01

216

Vapor-liquid equilibria of binary mixtures of alkanols with alkanes from atmospheric pressure to the critical point  

NASA Astrophysics Data System (ADS)

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 systems, the model parameters used were fit to data on the lowest-temperature isotherm and then higher-temperature isotherms were successfully predicted with those parameters. False phase splitting was avoided by using a constrained parameter fit. For highly asymmetric (in size) alkanol+alkane binaries four parameters were necessary for an accurate representation of the data, while for less asymmetric alkanol + alkane binaries only two parameters were used.

Orbey, H.; Sandier, S. I.

1995-05-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

218

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

219

Status Report on the Measurement of Vapor--Liquid Equilibria.  

National Technical Information Service (NTIS)

Hydrogen-rich binary and multicomponent systems are being studied by two different approaches: (1) A perturbation chromatographic approach developed at Rice University over the years, and; (2) An equilibrium cell which can be operated in either the flow o...

R. Kobayashi

1976-01-01

220

Coal Gasification Pilot Plant Support Studies. Subtask 3-2. Phase Equilibrium Studies as Applied to Treatment of Raw Bases from Coal Gasification.  

National Technical Information Service (NTIS)

Several methods to predict the phase equilibrium behavior of gas mixtures at different temperatures and pressures appear in the literature. In this study, four of these correlations have been evaluated using experimentally derived vapor-liquid equilibrium...

1980-01-01

221

Measurements of the vapor-liquid coexistence curve and the critical parameters for 1,1,1,2-tetrafluoroethane  

Microsoft Academic Search

Measurements of the vapor-liquid coexistence curve in the critical region for 1,1,1,2-tetrafluoroethane (R134a; CH2FCF3), which is currently considered as a prospective substitute for conventional refrigerant R12, have been performed by visual observation of the disappearance of the meniscus at the vapor-liquid interface within an optical cell. Twenty-seven saturated densities along the vapor-liquid coexistence curve between 208 and 999 kg·m?3 have

Y. Kabata; S. Tanikawa; M. Uematsu; K. Watanabe

1989-01-01

222

Vapor-liquid equilibrium of carbon dioxide in aqueous mixtures of monoethanolamine and methyldiethanolamine  

SciTech Connect

Aqueous solutions of alkanolamines are used to separate carbon dioxide and hydrogen sulfide from gas streams. Data for the distribution of carbon dioxide between the vapor and aqueous solutions of four mixtures of monoethanolamine (MEA) and methyldiethanolamine (MDEA) have been obtained at 25, 40, 80 and 120 C over a range of pressures from 100 kPa to 20 MPa. Partial pressures of CO[sub 2] ranged from 0.001 to 19,930 kPa. Enthalpies of reaction of CO[sub 2] in the solutions have been calculated from the solubility data.

Jou, F.Y.; Otto, F.D.; Mather, A.E. (Univ. of Alberta, Edmonton (Canada). Dept. of Chemical Engineering)

1994-08-01

223

Choice of basis mixtures for the prediction of vapor-liquid equilibria using the UNIFAC model  

SciTech Connect

A link was established between the accurate prediction of vapor-liquid equilibria and azeotropes using the UNIFAC group model and the choice of the basis information. The component activity coefficients are plotted as functions of composition for all the sets of data in each binary system. The activity coefficients at infinite dilution are determined as graphical extrapolations of these plots. The plot for the butanol-hydrocarbon system is shown. It is shown that azeotrope parameters can be used as the basis information to predict vapor-liquid equilibria for several sets of systems.

Kushner, T.M.; Fainburg, G.D.; Vitman, T.A.; Serafimov, L.A.

1988-07-01

224

Further Validation of a Set of Quadrupolar Potential Models for Ethylene and Propylene from the Prediction of some Binary Mixture Vapor-Liquid Equilibria by Gibbs-ensemble Molecular Simulation  

Microsoft Academic Search

A set of two-center Lennard-Jones plus point quadrupole (2CLJQ) effective pair potential models for ethylene and propylene, that have already been shown to be capable of fitting the saturated densities, the vapor pressures, and the enthalpies of vaporization of the pure liquids, is tested for vapor-liquid equilibrium (VLE) of mixtures in this work. Monte Carlo simulations in the Gibbs ensemble

Javier Carrero-Mantilla; Mario Llano-Restrepo

2003-01-01

225

Extended UNIQUAC model for correlation and prediction of vapor–liquid–liquid–solid equilibria in aqueous salt systems containing non-electrolytes. Part B. Alcohol (ethanol, propanols, butanols)–water–salt systems  

Microsoft Academic Search

The Extended UNIQUAC model for electrolyte solutions is an excess Gibbs energy function consisting of a Debye–Hückel term and a term corresponding to the UNIQUAC equation. For vapor–liquid equilibrium calculations, the fugacities of gas-phase components are calculated with the Soave–Redlich–Kwong equation of state. The model only requires binary, temperature-dependent interaction parameters. It has previously been used to describe the excess

Kaj Thomsen; Maria C. Iliuta; Peter Rasmussen

2004-01-01

226

Isobaric groundwater well  

DOEpatents

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

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

1999-01-01

227

Prediction of vapor-liquid equilibria at high pressures using activity coefficient parameters obtained from low-pressure data: A comparison of two equation of state mixing rules  

SciTech Connect

Two recent equation of state mixing rules, one by Dahl and Michelsen (MHV2) and another by Wong and Sandler (W-S), are claimed to be useful for making vapor-liquid equilibrium predictions for nonideal mixtures at high temperatures and pressures using data obtained at low pressures. Here the authors compare the performance of these two mixing rules in predicting the high-pressure phase behavior of nine binary systems using published activity coefficient parameters. They also compare the predictions for two ternary systems using mixing rule parameters obtained from low-pressure binary mixture data. They find that both mixing rules can be used to make reasonable high-pressure vapor-liquid equilibrium predictions from low-pressure data. However, the errors in the predicted pressure with the W-S mixing rule when used with either the Peng-Robinson or Soave-Redlich-Kwong equation of state are, on the average, about half or less those obtained when using the MHV2 mixing rule. Also, the predictions of the MHV2 mixing rule deteriorate significantly as the temperature and pressure range increase, which is not the case with the W-S mixing rule.

Huang, Hai; Sandler, S.I. (Univ. of Delaware, Newark (United States). Dept. of Chemical Engineering)

1993-07-01

228

High-pressure vapor-liquid equilibria involving mixtures of nitrogen, carbon dioxide, and eta-butane  

SciTech Connect

A new high-pressure vapor-liquid equilibrium apparatus has been constructed with the capability of measuring the compositions and densities of the coexisting equilibrium phases at constant temperature and/or pressure. This apparatus was tested with the carbon dioxide + n-butane system with excellent agreement observed between our results and previously published data. Data are also reported for the nitrogen + n-butane system and the previously unmeasured nitrogen + carbon dioxide + n-butane system. These data were modeled with the Peng-Robinson equation of state. Excellent fits were obtained for the compositions in the carbon dioxide + n-butane system, but a poor fit was obtained for the nitrogen + n-butane data. The ability of the Peng-Robinson equation of state to accurately predict the phase behavior of the ternary mixture is dependent on the fits of the binary data, and therefore the ternary data are also not fit well. In all cases the liquid densities are poorly predicted with the Peng-Robinson equation of state.

Shibata, S.K. (Du Pont de Nemours (E.I.) and Co., Wilmington, DE (USA). Technical Div.); Sandler, S.I. (Delaware Univ., Newark, DE (USA). Dept. of Chemical Engineering)

1989-07-01

229

A Modification of ? in SRK Equation of State and Vapor-Liquid Equilibria Prediction  

Microsoft Academic Search

Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor ? in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing

LUO Mingjian; MA Peisheng; XIA Shuqian

2007-01-01

230

Isothermal vapor-liquid equilibria for methanol + ethanol + water, methanol + water, and ethanol + water  

Microsoft Academic Search

Isothermal vapor-liquid equilibria were measured for the ternary system methanol + ethanol + water and its constituent binary systems of methanol + water and ethanol + water at 323.15, 328.15, and 333.15 K. The apparatus that was used made it possible to control the measured temperature and total pressure by computer. The experimental binary data were correlated by the NRTL

Kiyofumi Kurihara; Kouichi Takeda; Kazuo Kojima; Tsuyoshi Minoura

1995-01-01

231

Correlation of vapor-liquid equilibria for the system ammonia-carbon dioxide-water  

Microsoft Academic Search

New parameters are given for a previously published correlation for calculating vapor-liquid equilibria in aqueous systems containing volatile weak electrolytes. Particular attention is given to ternary aqueous mixtures containing ammonia and carbon dioxide. When the new parameters are used, good agreement is obtained with recent experimental data.

Kenichi Kawazuishi; John M. Prausnitz

1987-01-01

232

Vapor/Liquid Interaction and Entrainment in Shell-and-Tube Evaporators.  

National Technical Information Service (NTIS)

The problem of vapor/liquid interaction and entrainment in shell-and-tube evaporators is analyzed. Attention is focused primarily on the horizontal tube falling film evaporators, which have been proposed for use in Ocean Thermal Energy Conversion (OTEC) p...

D. Yung J. J. Lorenz E. N. Ganic

1978-01-01

233

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

USGS Publications Warehouse

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

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

1974-01-01

234

Steady-state, vapor-liquid concurrent flow: Relative permeabilities and end effects  

SciTech Connect

Steady-state methods are commonly used for the determination of the relative permeabilities of single component vapor-liquid systems, such as steam-water. Even though such experiments are performed under adiabatic conditions, the interpretation of results has proved to be a difficult task in many cases. Reasons involve phase change, heat transfer, capillarity and rate considerations. This paper presents a systematic study of the saturation and temperature distributions in steady-state, vapor-liquid flows and examines the sensitivity to parameters such as injection rate, permeability and core length. Two sets are analyzed, one pertaining to the simultaneous injection of a two-phase mixture (Sanchez and Schechter, 1987) and another involving phase change (liquid to vapor) within the core (Miller, 1951). End effects and, in general, effects associated with capillary heterogeneity are analyzed in detail. 16 refs., 15 figs., 3 tabs.

Parlar, M.; Zeybek, M.; Yortsos, Y.C.

1990-06-01

235

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

236

Light scattering from a binary mixture near the vapor-liquid critical line  

Microsoft Academic Search

Light scattering measurements are reported near the vapor-liquid critical line for a low-concentration mixture of propylene in CO2. Along the critical isochore the small-angle scattering cross section diverges as strongly as in pure fluids (gamma = 1.212 +\\/- 0.015). The critical contribution to the diffusivity is estimated from linewidth measurements, and found to coincide with that for CO2.

M. Giglio; A. Vendramini

1973-01-01

237

Vapor liquid equilibria for the quaternary system of formaldehyde(1)-methanol(2)-methylal(3)-water(4)  

Microsoft Academic Search

The vapor-liquid equilibria in the quaternary system of formaldehyde(1)-methanol(2)-methylal(3)-water(4) were measured experimentally at a pressure of 101.33 ± 0.02 kPa, and at temperatures from about 318 to 367 K. The concentration ranges of the liquid phase were, formaldehyde < 15% (in mass), methanol < 42%, and methylal and water from 0 to 100%. Brandani's physico-chemical model was extended to correlate

Zhengjun Shan; Yanru Wang; Shouchang Qiu; Chongyu Zheng; Jun Shi

1995-01-01

238

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

Microsoft Academic Search

For the design and optimization of CO2 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 N2+O2+CO2. Pure substance parameters of the Peng–Robinson EOS are taken from the literature, whereas the

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

2009-01-01

239

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

Microsoft Academic Search

TiC whiskers were synthesized via a vapor-liquid-solid (VLS) growth mechanism in the temperature region 1,200--1,600 C in a protecting argon atmosphere. The starting materials consisted of TiOâ, carbon, nickel, and an alkali-metal chloride, such as NaCl, used as a precursor for chlorine. The overall chemical reaction was based on a straightforward carbothermal reduction process, but the reactions that actually took

Niklas Ahlen; Mats Johnsson; Mats Nygren

1996-01-01

240

Vapor–liquid phase behavior of binary systems of hydrogen chloride and certain n-alkanes  

Microsoft Academic Search

This contribution reports on experimental data of the vapor–liquid phase behavior of the binary system hydrogen chloride+ethane. It was confirmed that the system hydrogen chloride+ethane has type-I fluid phase behavior in the classification of Van Konynenburg and Scott with maximum pressure azeotropy. As an additional feature, it turned out that no reaction between hydrogen chloride and the mercury present in

L. J Florusse; C. J Peters

2002-01-01

241

Vapor–liquid equilibria for the system 1-propanol+ n-hexane near the critical region  

Microsoft Academic Search

Vapor–liquid equilibria and critical point data for the system 1-propanol+n-hexane at 483.15, 493.15, 503.15 and 513.15K are reported. The critical pressures determined from the critical opalescence of the mixture were compared with published data for the system 2-propanol+n-hexane. Phase behavior measurements were made in a modified circulating type apparatus with a view cell. These mixtures are highly nonideal because of

Byung Chul Oh; Youngdae Kim; Hun Yong Shin; Hwayong Kim

2004-01-01

242

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

SciTech Connect

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

243

Controlled vapor-liquid-solid growth of indium, gallium, and tinoxide nanowires via chemical vapor transport  

SciTech Connect

We utilized a vapor-liquid-solid growth technique tosynthesize indium oxide, gallium oxide, and tin oxide nanowires usingchemical vapor transport with gold nanoparticles as the catalyst. Usingidentical growth parameters, we were able to synthesize single crystalnanowires typically 40-100 nm diameter and more than 10-100 m long. Theproducts were characterized by means of X-ray diffraction (XRD), scanningelectron microscopy (SEM), and high-resolution transmission electronmicroscopy (HRTEM). All the wires were grown under the same growthconditions with growth rates inversely proportional to the source metalvapor pressure. Initial experiments show that different transparent oxidenanowires can be grown simultaneously on a single substrate withpotential application for multicomponent gas sensors.

Johnson, M.C.; Aloni, S.; McCready, D.E.; Bourret-Courchesne, E.D.

2006-03-31

244

Vapor-liquid equilibria of binary mixtures with ethyl tert-butyl ether  

SciTech Connect

In this work P-T-x-y vapor-liquid equilibria were obtained for ethyl tert-butyl ether (ETBE) + toluene at temperatures of 273.15, 311.15, and 333.15 K and for 2-methylbutane (isopentane) + ETBE at temperatures of 293.15 and 303.15 K. These mixtures are found to be almost ideal, and the reported data are well described using a Peng-Robinson equation of state, modified by Stryjek and Vera with the van der Waals one-fluid mixing rule.

Steinhagen, V. (Technische Univ., Berlin (Germany). Inst. fuer Thermodynamik und Reaktionstechnik); Sandler, S.I. (Univ. of Delaware, Newark, DE (United States). Dept. of Chemical Engineering)

1994-07-01

245

Vapor-liquid equilibria of hydrocarbons and tert-amyl methyl ether  

SciTech Connect

The P-T-x-y data for tert-amyl methyl ether (TAME) separately with 2,2,4-trimethylpentane (TMP), methylcyclohexane (MCHX), and toluene were obtained at three temperatures, 293, 311, and 333 K. The vapor-liquid equilibria of a five-components mixture (TAME + TMP + 1-heptene + MCHX + toluene) at the same temperature were measured as well. The data reported have been successfully described using a Peng-Robinson equation of state with van der Waals one-fluid mixing rules.

Antosik, M. (Polish Academy of Sciences, Warszawa (Poland). Inst. of Physical Chemistry); Sandler, S.I. (Univ. of Delaware, Newark, DE (United States). Dept. of Chemical Engineering)

1994-07-01

246

VLS /vapor-liquid-solid/ - Newly discovered growth mechanism on the lunar surface.  

NASA Technical Reports Server (NTRS)

A probable vapor-liquid-solid (VLS) type of growth has been discovered for the first time in nature on the surface of lunar rock 15015. Scanning electron microprobe and energy dispersive x-ray data indicate that the growth occurs as metallic iron stalks from about 0.015 to 0.15 micrometer in diameter, with bulbous tips consisting of a mixture of iron and sulfur and measuring from about 0.03 to 0.2 micrometer in diameter. The stalk length is two to ten times the bulb diameter.

Carter, J. L.

1973-01-01

247

Vapor-liquid interfacial properties of rigid-linear Lennard-Jones chains.  

PubMed

We have obtained the interfacial properties of short rigid-linear chains formed from tangentially bonded Lennard-Jones monomeric units from direct simulation of the vapour-liquid interface. The full long-range tails of the potential are accounted for by means of an improved version of the inhomogeneous long-range corrections of Janec?ek [J. Phys. Chem. B 110, 6264-6269 (2006)] proposed recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] valid for spherical as well as for rigid and flexible molecular systems. Three different model systems comprising of 3, 4, and 5 monomers per molecule are considered. The simulations are performed in the canonical ensemble, and the vapor-liquid interfacial tension is evaluated using the test-area method. In addition to the surface tension, we also obtain density profiles, coexistence densities, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the chain length and rigidity on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapor-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. The surface tension has been scaled by critical properties and represented as a function of the difference between coexistence densities relative to the critical density. PMID:22938258

Blas, F J; Moreno-Ventas Bravo, A Ignacio; Míguez, J M; Piñeiro, M M; MacDowell, L G

2012-08-28

248

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

PubMed

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

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-06-17

249

A Topologically Based Procedure to Identify Invariant Reactions for Isobaric Multicomponent Phase Diagrams  

NASA Astrophysics Data System (ADS)

Invariant reactions are a common occurrence in multicomponent phase diagrams, and their underlying topological basis can be correlated with the numbers of reactant and product phases involved. Understanding and manipulating invariant reactions demand in-depth knowledge in phase diagram topologies. Based on simple equilibrium calculations, a topologically based procedure is proposed to establish invariant reactions for isobaric multicomponent phase diagrams.

Liu, Yajun; Kang, Zhitao

2014-06-01

250

A Topologically Based Procedure to Identify Invariant Reactions for Isobaric Multicomponent Phase Diagrams  

NASA Astrophysics Data System (ADS)

Invariant reactions are a common occurrence in multicomponent phase diagrams, and their underlying topological basis can be correlated with the numbers of reactant and product phases involved. Understanding and manipulating invariant reactions demand in-depth knowledge in phase diagram topologies. Based on simple equilibrium calculations, a topologically based procedure is proposed to establish invariant reactions for isobaric multicomponent phase diagrams.

Liu, Yajun; Kang, Zhitao

2013-11-01

251

Verification of Onsager's reciprocal relations for evaporation and condensation using non-equilibrium molecular dynamics  

Microsoft Academic Search

Non-equilibrium molecular dynamic (NEMD) simulations have been used to study heat and mass transfer across a vapor–liquid interface for a one-component system using a Lennard-Jones spline potential. It was confirmed that the relation between the surface tension and the surface temperature in the non-equilibrium system was the same as in equilibrium (local equilibrium) [A. Røsjorde, D.W. Fossmo, S. Kjelstrup, D.

J. Xu; S. Kjelstrup; D. Bedeaux; A. Røsjorde; L. Rekvig

2006-01-01

252

Tapering and crystal structure of indium phosphide nanowires grown by selective area vapor liquid solid epitaxy  

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

253

Cooperative effect in nucleation: Nanosized seed particles jointly nucleate vapor-liquid transitions  

NASA Astrophysics Data System (ADS)

Using the constrained lattice density functional theory, in this work we show that when the size of critical nucleus for vapor-liquid transition is comparable to the distance between seed particles (or active sites on solid surfaces), a cooperative effect in nucleation processes is found. More specifically, neighboring seed particles are found to nucleate jointly the phase transition with a lower nucleation barrier and a different morphology of critical nucleus compared to those from an isolated seed particle. In addition, the cooperative effect, including the decrease of nucleation barrier and the morphology change of critical nucleus, is found to depend on the distance between seed particles, the fluid-solid interaction, and the particle size.

Guo, Qiumin; Liu, Yawei; Jiang, Guangfeng; Zhang, Xianren

2013-06-01

254

Vapor-liquid-solid grown silica nanowire based electrochemical glucose biosensor.  

PubMed

Vapor-liquid-solid (VLS) grown silica nanowires (SiO(2)NWs) have been deposited electrophoretically on a gold electrode and utilized for covalent immobilization of glucose oxidase (GOx). Covalent binding has been achieved via 3-aminopropyltriethoxysilane (APTES) modification and N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. Scanning electron microscopy, transmission electron microscopy and cyclic voltammetry techniques have been used to characterize SiO(2)NW and GOx/APTES/SiO(2)NW/Au bioelectrode. Electrochemical studies reveal that SiO(2)NW increases the effective electro-active surface area thus resulting in higher loading of enzyme. Response characteristics show linearity in the range of interest 25-300 mg dl(-1), with a detection limit of 11 mg dl(-1), sensitivity: 0.463 µA (mg dl(-1))(-1) and regression coefficient of 0.992. PMID:21369619

Murphy-Pérez, Eduardo; Arya, Sunil K; Bhansali, Shekhar

2011-04-21

255

Conditions for subeutectic growth of Ge nanowires by the vapor-liquid-solid mechanism  

NASA Astrophysics Data System (ADS)

The requirement of the presence of a liquid for the widely accepted vapor-liquid-solid (VLS) mechanism suggests that nanowire growth should be carried out at temperatures above the catalyst-nanowire eutectic melting point. In this paper, we examine the nanowire growth at the deep subeutectic temperatures often employed for germanium nanowire growth with Au catalyst nanoparticles. The effects of germane partial pressure on the low temperature limit for Au-catalyzed Ge nanowire growth by chemical vapor deposition from GeH4(g) were studied thoroughly, both with and without initial heating above the bulk eutectic temperature. A model to explain the temperature and pressure limits of subeutectic VLS nanowire growth was developed. The interdependence of the pressure and temperature required for good quality germanium nanowire growth may also apply in other cases of nanowire growth, beyond the Au-Ge system.

Adhikari, Hemant; McIntyre, Paul C.; Marshall, Ann F.; Chidsey, Christopher E. D.

2007-11-01

256

Growth mechanisms of vapor-liquid-solid grown nanowires: A detailed analysis of irregular nanowire formation  

NASA Astrophysics Data System (ADS)

Although vapor-liquid-solid (VLS) growth has become a standard method for producing nanowires, the underlying growth mechanisms have not been fully elucidated because VLS growth is affected by thermodynamic and geometrical factors that, to date, have mainly been considered separately. Based on the assumption that the irregular nanowire growth reflects the conditions of the eutectic droplet during nanowire growth, we aimed to elucidate the thermodynamic and geometrical aspects of the growth mechanisms by the measurement and analysis of irregular kinked and curved Si nanowires grown by Au-catalyzed VLS. The results suggest that kinked nanowires may be caused by higher supersaturation, whereas curved nanowires may be caused by lower supersaturation within the eutectic Au-Si droplet. The results of measuring and analyzing irregular nanowires confirmed that both thermodynamic and geometrical effects complexly influence nanowire growth kinetics, particularly the supersaturation of eutectic droplets, and the effects are more pronounced in larger diameter nanowires.

Koto, Makoto

2014-04-01

257

Oscillatory Mass Transport in Vapor-Liquid-Solid Growth of Sapphire Nanowires  

SciTech Connect

In vapor-liquid-solid (VLS) growth, the liquid phase plays a pivotal role in mediating mass transport from the vapor source to the growth front of a nanowire. Such transport often takes place through the liquid phase. However, we observed by in situ transmission electron microscopy a different behavior for self-catalytic VLS growth of sapphire nanowires. The growth occurs in a layer-by-layer fashion and is accomplished by interfacial diffusion of oxygen through the ordered liquid aluminum atoms. Oscillatory growth and dissolution reactions at the top rim of the nanowires occur and supply the oxygen required to grow a new (0006) sapphire layer. A periodic modulation of the VLS triple-junction configuration accompanies these oscillatory reactions.

Oh, Sang Ho [ORNL; Chisholm, Matthew F [ORNL; Kauffmann, Yaron [Technion-Israel Institute of Technology, Haifa, Israel; Kaplan, Prof. Wayne D. [Technion, Israel Institute of Technology; Luo, Weidong [ORNL; Ruhle, M. [Max-Planch-Institut fur Metallforschang, Germany; Scheu, Christina [Ludwig-Maximilian University

2010-01-01

258

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

SciTech Connect

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

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

1992-06-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

260

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

SciTech Connect

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

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

2009-03-16

261

Vapor-liquid and liquid-liquid equilibria of water, 2-methoxyethanol and cyclohexanone: Experiment and correlation  

Microsoft Academic Search

Vapor-liquid equilibria and liquid-liquid equilibria of a ternary mixture consisting of water, 2-methoxyethanol and cyclohexanone and in addition of all binary subsystems were studied experimentally at several temperatures. A ternary corrective term in the expression for the Gibbs free energy based on the NRTL model improves simultaneous representation of binary and ternary phase equilibria.

T. Hauschild; H. Knapp

1994-01-01

262

High-pressure vapor-liquid equilibria for propane + 2-butanol, propylene + 2-butanol, and propane + 2-butanol + 2-propanol  

Microsoft Academic Search

The use of dual effect solvents (near critical extractant and high-pressure water entrainer), for the recovery and dehydration of alcohols from dilute aqueous solutions, has been proposed by Brignole et al. (1987). The present work is part of an experimental program undertaken to confirm the applicability of light hydrocarbons for this separation problem. Vapor-liquid equilibria have been measured for propane

Hernán P. Gros; Marcelo S. Zabaloy; Esteban A. Brignole

1996-01-01

263

Temporal and spatial relationships between topography, atmospheric water vapor, liquid water and vegetation endmember fractions determined using AVIRIS  

Microsoft Academic Search

Temporal and spatial changes in water vapor, liquid water and endmember fractions were investigated using AVIRIS data collected in the vicinity of Jasper Ridge, CA, on three dates in 1992. Water vapor and liquid water were mapped using a Modtran-II based atmospheric model that accounts for spatially varying atmospheric properties. Spectral mixture analysis (SMA) was used to model vegetation as

D. A. Roberts; R. O. Green; J. B. Adams; J. S. Cothern; D. E. Sabol; M. O. Smith

1994-01-01

264

Vapor-liquid equilibria of ethanol + octane at 343. 15 K and 1-propanol + octane at 358. 15 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibria were measured for ethanol + octane at 343.15 K and 1-propanol + octane at 358.15 K. The measurements were made in a still with the aid of a computer for control of the temperature and measurements of the total pressure. The results were best correlated with the Wilson equation for the system of ethanol + octane and

Toshihiko Hiaki; Kenji Takahashi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

2009-01-01

265

Measurements of the vapor-liquid coexistence curve and the critical parameters for 1,1,1,2-tetrafluoroethane  

SciTech Connect

Measurements of the vapor-liquid coexistence curve in the critical region for 1,1,1,2-tetrafluoroethane (R134a; CH{sub 2}FCF{sub 3}), which is currently considered as a prospective substitute for conventional refrigerant R12, have been performed by visual observation of the disappearance of the meniscus at the vapor-liquid interface within an optical cell. Twenty-seven saturated densities along the vapor-liquid coexistence curve between 208 and 999 kg {times} m{sup {minus}3} have been obtained in the temperature range 343 K to the critical temperature. The experimental uncertainties in temperature and density measurements have been estimated to be within {plus minus} 10 mK and {plus minus} 0.55%, respectively. On the basis of these measurements near the critical point, the critical temperature and the critical density for 1,1,1,2-tetrafluoroethane were determined in consideration of the meniscus disappearing level as well as the intensity of the critical opalescence. In addition, the critical exponent {beta} along the vapor-liquid coexistence curve has been determined in accord with the difference between the density of the saturated liquid and that of the saturated vapor.

Kabata, Y.; Tanikawa, S.; Uematsu, M.; Watanabe, K. (Keio Univ., Yokohama (Japan))

1989-05-01

266

Measurements of the Vapor-Liquid Coexistence Curves and the Critical Parameters of HCFC123 and HFC134a  

NASA Astrophysics Data System (ADS)

The critical parameters and vapor-liquid coexistence curves in the critical region of two environmentally acceptable hydrogen-containing halocarbons (HCFC123 and HFC134a) were determined experimentally. The measurements of vapor-liquid coexistence curves were made through visual observation of the disappearance of meniscus at the vapor-liquid interface within the optical cell. Thirty eight saturated densities in the range of 209 to 1176 kg/m3 were obtained between the temperature of 392 K and the critical temperature for HCFC123. And seventeen saturated densities in the range of 322 to 746 kg/m3 were obtained between the temperature of 370 K and the critical temperature for HFC134a. On the basis of these results, the critical temperature and critical density of HCFC123 were determined to be 456.94 K and 553 kg/m3, respectively. And these parameters of HFC134a were determined to be 374.18 K and 507 kg/m3. In addition, the critical exponents were determined and the correlation of vapor-liquid coexistence curves were developed.

Fukushima, Masato; Watanabe, Naohiro; Kamimura, Toru

267

Isobars and the Efficient Market Hypothesis  

Microsoft Academic Search

Isobar surfaces, a method for describing the overall shape of multidimensional data, are estimated by nonparametric regression and used to evaluate the efficiency of selected markets based on returns of their stock market indices.

Kristýna Ivanková

2010-01-01

268

Isobaric Analog States for Neutron Spectroscopic Factors.  

National Technical Information Service (NTIS)

A survey of the modified R-matrix method for extraction of neutron spectroscopic factors from isobaric analog resonances in proton elastic scattering polarization and cross section excitation functions is presented for several parent analog states in Zirc...

W. J. Thompson J. L. Ellis

1969-01-01

269

Correlation and prediction of binary vapor-liquid equilibrium in systems containing gases, hydrocarbons, alcohols, and water  

Microsoft Academic Search

Optimal binary interaction coefficients have been determined for a generalized equation of state for associating mixtures using a large data base of 170 binary systems compiles from the literature. The data base covers gases (Hâ, Nâ, CO, COâ, and HâS), hydrocarbons, alcohols, and water. Results show substantial improvements in accuracy for the equation of state presented here relative to the

Aaron S. Puhala; J. Richard Elliott

1993-01-01

270

Measurement and estimation of vapor–liquid equilibrium for industrial sugar juice using the Peng–Robinson equation of state  

Microsoft Academic Search

The Peng–Robinson equation of state is adapted to calculate phase equilibria for industrial sugar juices using the pseudocomponent approach. These juices were characterized by sugar, amino acid, carboxylic acid and ash pseudocomponents in aqueous solution. New correlating equations are developed for calculating the pseudocomponents equation of state constants using the molecular structure. Pseudo-binary interaction parameters of Peng–Robinson equation of state

S. Abderafi; T. Bounahmidi

1999-01-01

271

Application of a volume-translated Peng-Robinson equation of state on vapor-liquid equilibrium calculations  

Microsoft Academic Search

A volume-translated Peng-Robinson (VTPR) equation of state (EOS) is developed in this study. Besides the two parameters in the original Peng-Robinson equation of state, a volume correction term is employed in the VTPR EOS. In this equation, the temperature dependence of the EOS energy parameter was regressed by an improved expression which yields better correlation of pure-fluid vapor pressures. The

Jung-Chin Tsai; Yan-Ping Chen

1998-01-01

272

Modeling of high-pressure vapor–liquid equilibrium in ionic liquids + gas systems using the PRSV equation of state  

Microsoft Academic Search

Ionic liquids are environmentally friendly solvents composed of large organic cations and relatively small inorganic anions, whose melting point is below T=373.15K. This is an arbitrary limit defined in order to organize the dramatically increasing number of possible applications in chemical processes. These compounds are regarded as potentially environmentally benign solvents due to their almost negligible vapor pressure, which essentially

Pedro F. Arce; P. Adrián Robles; Teófilo A. Graber; Martín Aznar

2010-01-01

273

Directed synthesis of germanium oxide nanowires by vapor-liquid-solid oxidation.  

PubMed

We report on the directed synthesis of germanium oxide (GeO(x)) nanowires (NWs) by locally catalyzed thermal oxidation of aligned arrays of gold catalyst-tipped germanium NWs. During oxygen anneals conducted above the Au-Ge binary eutectic temperature (T > 361 °C), one-dimensional oxidation of as-grown Ge NWs occurs by diffusion of Ge through the Au-Ge catalyst droplet, in the presence of an oxygen containing ambient. Elongated GeO(x) wires grow from the liquid catalyst tip, consuming the adjoining Ge NWs as they grow. The oxide NWs' diameter is dictated by the catalyst diameter and their alignment generally parallels that of the growth direction of the initial Ge NWs. Growth rate comparisons reveal a substantial oxidation rate enhancement in the presence of the Au catalyst. Statistical analysis of GeO(x) nanowire growth by ex situ transmission electron microscopy and scanning electron microscopy suggests a transition from an initial, diameter-dependent kinetic regime, to diameter-independent wire growth. This behavior suggests the existence of an incubation time for GeO(x) NW nucleation at the start of vapor-liquid-solid oxidation. PMID:22947505

Gunji, M; Thombare, S V; Hu, S; McIntyre, P C

2012-09-28

274

Identifying Crystallization- and Incorporation-Limited Regimes during Vapor-Liquid-Solid Growth of Si Nanowires.  

PubMed

The vapor-liquid-solid (VLS) mechanism is widely used for the synthesis of semiconductor nanowires (NWs), yet several aspects of the mechanism are not fully understood. Here, we present comprehensive experimental measurements on the growth rate of Au-catalyzed Si NWs over a range of temperatures (365-480 °C), diameters (30-200 nm), and pressures (0.1-1.6 Torr SiH4). We develop a kinetic model of VLS growth that includes (1) Si incorporation into the liquid Au-Si catalyst, (2) Si evaporation from the catalyst surface, and (3) Si crystallization at the catalyst-NW interface. This simple model quantitatively explains growth rate data collected over more than 65 distinct synthetic conditions. Surprisingly, upon increasing the temperature and/or pressure, the analysis reveals an abrupt transition from a diameter-independent growth rate that is limited by incorporation to a diameter-dependent growth rate that is limited by crystallization. The identification of two distinct growth regimes provides insight into the synthetic conditions needed for specific NW-based technologies, and our kinetic model provides a straightforward framework for understanding VLS growth with a range of metal catalysts and semiconductor materials. PMID:24815744

Pinion, Christopher W; Nenon, David P; Christesen, Joseph D; Cahoon, James F

2014-06-24

275

Organic-vapor-liquid-solid deposition with an impinging gas jet  

NASA Astrophysics Data System (ADS)

A method for rapid, mass-efficient deposition of highly crystalline organic films under near ambient conditions of pressure and temperature is reported based on delivery of an organic precursor via an impinging gas jet to a substrate coated by a thin liquid solvent layer. Films of the organic semiconductor tetracene were deposited by sublimation into a flow of argon carrier gas directed at an indium-tin-oxide/glass substrate coated by a thin layer of bis(2-ethylhexyl)sebecate, and growth was followed in situ with optical microscopy. A fluid dynamics model is applied to account for the gas phase transport and aggregation, and the results compared to experiment. The combination of gas jet delivery with an organic-vapor-liquid-solid growth mechanism leads to larger crystals and lower nucleation densities than on bare surfaces, with markedly different nucleation and growth kinetics. An explanation based on enhanced solution-phase diffusivity and a larger critical nucleus size in the liquid layer is proposed to account for the differences.

Shaw, Daniel W.; Bufkin, Kevin; Baronov, Alexandr A.; Johnson, Brad L.; Patrick, David L.

2012-04-01

276

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

SciTech Connect

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

277

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

SciTech Connect

TiC whiskers were synthesized via a vapor-liquid-solid (VLS) growth mechanism in the temperature region 1,200--1,600 C in a protecting argon atmosphere. The starting materials consisted of TiO{sub 2}, carbon, nickel, and an alkali-metal chloride, such as NaCl, used as a precursor for chlorine. The overall chemical reaction was based on a straightforward carbothermal reduction process, but the reactions that actually took place were more complex and involved formation of gaseous TiCl{sub x} species, which were transported to the nickel catalyst. The formation of TiC whiskers depended on the processing conditions used, mixing procedure of the precursor materials applied, and properties of precursor materials chosen, e.g., their particle sizes. A route for synthesizing TiC whiskers at a yield of 80--90 vol% was established. The whiskers were {approximately}1 {micro}m in diameter and 10--30 {micro}m in length; they were straight and had smooth surfaces. The main impurities were TiC particles, minor amounts of unreacted carbon, and remnants of the nickel catalyst.

Ahlen, N.; Johnsson, M.; Nygren, M. [Stockholm Univ. (Sweden)

1996-11-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

279

Identification of an intrinsic source of doping inhomogeneity in vapor-liquid-solid-grown nanowires.  

PubMed

The vapor-liquid-solid (VLS) process of semiconductor nanowire growth is an attractive approach to low-dimensional materials and heterostructures because it provides a mechanism to modulate, in situ, nanowire composition and doping, but the ultimate limits on doping control are ultimately dictated by the growth process itself. Under widely used conditions for the chemical vapor deposition growth of Si and Ge nanowires from a Au catalyst droplet, we find that dopants incorporated from the liquid are not uniformly distributed. Specifically, atom probe tomographic analysis revealed up to 100-fold enhancements in dopant concentration near the VLS trijunction in both B-doped Si and P-doped Ge nanowires. We hypothesize that radial and azimuthal inhomogeneities arise from a faceted liquid-solid interface present during nanowire growth, and we present a simple model to account for the distribution. As the same segregation behavior was observed in two distinct semiconductors with different dopants, the observed inhomogeneity is likely to be present in other VLS grown nanowires. PMID:23237496

Connell, Justin G; Yoon, KunHo; Perea, Daniel E; Schwalbach, Edwin J; Voorhees, Peter W; Lauhon, Lincoln J

2013-01-01

280

n-Type Doping of Vapor-Liquid-Solid Grown GaAs Nanowires  

NASA Astrophysics Data System (ADS)

In this letter, n-type doping of GaAs nanowires grown by metal-organic vapor phase epitaxy in the vapor-liquid-solid growth mode on (111)B GaAs substrates is reported. A low growth temperature of 400°C is adjusted in order to exclude shell growth. The impact of doping precursors on the morphology of GaAs nanowires was investigated. Tetraethyl tin as doping precursor enables heavily n-type doped GaAs nanowires in a relatively small process window while no doping effect could be found for ditertiarybutylsilane. Electrical measurements carried out on single nanowires reveal an axially non-uniform doping profile. Within a number of wires from the same run, the donor concentrations N D of GaAs nanowires are found to vary from 7 × 1017 cm-3 to 2 × 1018 cm-3. The n-type conductivity is proven by the transfer characteristics of fabricated nanowire metal-insulator-semiconductor field-effect transistor devices.

Gutsche, Christoph; Lysov, Andrey; Regolin, Ingo; Blekker, Kai; Prost, Werner; Tegude, Franz-Josef

2011-12-01

281

Directed synthesis of germanium oxide nanowires by vapor-liquid-solid oxidation  

NASA Astrophysics Data System (ADS)

We report on the directed synthesis of germanium oxide (GeOx) nanowires (NWs) by locally catalyzed thermal oxidation of aligned arrays of gold catalyst-tipped germanium NWs. During oxygen anneals conducted above the Au-Ge binary eutectic temperature (T > 361?°C), one-dimensional oxidation of as-grown Ge NWs occurs by diffusion of Ge through the Au-Ge catalyst droplet, in the presence of an oxygen containing ambient. Elongated GeOx wires grow from the liquid catalyst tip, consuming the adjoining Ge NWs as they grow. The oxide NWs’ diameter is dictated by the catalyst diameter and their alignment generally parallels that of the growth direction of the initial Ge NWs. Growth rate comparisons reveal a substantial oxidation rate enhancement in the presence of the Au catalyst. Statistical analysis of GeOx nanowire growth by ex situ transmission electron microscopy and scanning electron microscopy suggests a transition from an initial, diameter-dependent kinetic regime, to diameter-independent wire growth. This behavior suggests the existence of an incubation time for GeOx NW nucleation at the start of vapor-liquid-solid oxidation.

Gunji, M.; Thombare, S. V.; Hu, S.; McIntyre, P. C.

2012-09-01

282

Isothermal vapor-liquid equilibria for 1,1,1,2-tetrafluoroethane + propane and propane + 1,1,1,-trifluoroethane at 283.18 K  

SciTech Connect

Isothermal vapor-liquid equilibria (VLE) for the binary systems 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) and propane + 1,1,1-trifluoroethane (R143a) were measured at 283.18 K using a recirculation apparatus in which the vapor phase was forced through the liquid. The phase composition at equilibrium was measured by gas chromatography, calibrating its response using gravimetrically prepared mixtures. The data were correlated using the Carnahan-Starling-De Santis and Peng-Robinson equations of state. The authors found positive homoazeotropes for R134a (1) + R290 (2) at a pressure P = 1,000.5 kPa and a composition x{sub 1} = 0.386, and for R290 (1) + R143a (2) at P = 796 kPa and x{sub 1} = 0.363. For the R134a + R290 there was a valid consistency with the values reported in the literature.

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

1998-03-01

283

Isothermal vapor–liquid equilibria and excess molar volumes for 2-methyl pyrazine (2MP) containing binary mixtures  

Microsoft Academic Search

2-Methyl pyrazine (2MP) has led to significant interest for its industrial and pharmaceutical uses. The new vapor–liquid equilibria (VLE) at 353.15K and excess molar volumes (VE) at 298.15K over the whole mole fraction range for seven binaries (water, n-hexane, cyclohexane, n-heptane, methylcyclopentane (MCP), methylcyclohexane (MCH) and ethyl acetate (EA) with 2MP) have been measured. VLE were measured by using headspace

So-Jin Park; Hyun-Hee Kim; Kyu-Jin Han; Dong-Bok Won; Sang Bong Lee; Myoung-Jae Choi

2001-01-01

284

Liquid–liquid equilibria and vapor–liquid equilibria for the binary system of epichlorohydrin and water  

Microsoft Academic Search

The liquid–liquid equilibria (LLE) data and vapor–liquid equilibria (VLE) data for the binary system of epichlorohydrin (EPCH)+water were studied at 101.3kPa. An azeotropic behavior has been found in the EPCH+water. Both the experimental LLE and VLE data were compared with the correlated values obtained by means of the NRTL and UNIQUAC equations. Both models satisfactorily correlated the experimental data. Thermodynamic

Qun Yue; Jia-wen Zhu; Yan-yang Wu; Xiang-qian Yuan; Liang Ma

2009-01-01

285

Vapor–liquid equilibria at elevated pressures of binary mixtures of carbon dioxide with methyl salicylate, eugenol, and diethyl phthalate  

Microsoft Academic Search

A semi-flow type apparatus was used to measure the vapor–liquid equilibria (VLE) of CO2 with methyl salicylate, eugenol, and diethyl phthalate binary mixtures at 308.15, 318.15, and 328.15 K over the pressure range from 1.4 to 13 MPa. New VLE data for these binary mixtures are presented and the Henry's constants were determined from these results. The Soave–Redlich–Kwong and the

Kong-Wei Cheng; Shin-Jien Kuo; Muoi Tang; Yan-Ping Chen

2000-01-01

286

Prediction of vapor-liquid equilibria of binary systems using PRSV equation of state and Wong-Sandier mixing rules  

Microsoft Academic Search

The Peng-Robinson equation of state modified by Stryjek and Vera (1986) has been used with Wong-Sandier mixing rules (1992) to predict vapor-liquid equilibria of forty-three binary mixtures involving organic alcohols, esters, ketones, amines, etc. The Wong-Sandier mixing rules are theoretically correct in the sense that they reproduce quadratic composition dependence of the second virial coefficient. However, recent studies indicate that

Pallab Ghosh; Tanmay Taraphdar

1998-01-01

287

ON THE SIMULTANEOUS REPRESENTATION OF VAPOR-LIQUID EQUILIBRIA AND EXCESS ENTHALPIES OF 1ALKANOL + n-ALKANE MIXTURES  

Microsoft Academic Search

Simultaneous representation of vapor-liquid equilibria and excess enthalpies for l-alkanol + n-alkane mixtures has been investigated by means or the PRSV equation of state together with the Wong-Sandier mixing rule. Special attention has been paid on the mixtures of methanol and n-hexane. The results are influenced not only by the selection of a suitable excess Gibbs energy model incorporated in

SHUBAO SHEN; BENJAMIN C.-Y. LU

1997-01-01

288

A new mixing rule for cubic equations of state and its application to vapor-liquid equilibria of polymer solutions  

Microsoft Academic Search

A new mixing rule for van der Waals-type two-parameter cubic equations of state (EOSs) has been proposed in this work, which is particularly suitable for highly asymmetric systems. The new mixing rule has been applied to the PRSV and SRK EOSs to calculate vapor-liquid equilibria (VLE) of polymer solutions. Compared to the other two mixing rules which have been used

Chongli Zhong; Hirokatsu Masuoka

1996-01-01

289

Vapor–liquid equilibria predictions of hydrogen–hydrocarbon mixtures with the Huron–Vidal mixing rule  

Microsoft Academic Search

An excess Gibbs-equation of state (GE-EoS) framework based on the Huron–Vidal mixing rule, has been applied to study vapor–liquid equilibria (VLE) of hydrogen–hydrocarbon mixtures. The mixing rule couples the Peng–Robinson–Stryjek–Vera (PRSV) EoS with a local composition solution model. The solution model is based on one-fluid theory treatment and assigns a single energy parameter to each binary pair. This energy parameter

Socrates Ioannidis; Dana E. Knox

1999-01-01

290

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

SciTech Connect

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

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

1996-08-01

291

Vapor-liquid equilibria of the binary systems nitrogen + bromotrifluoromethane, + bromochlorodifluoromethane, + 1,1,1,2,3,3,3-heptafluoropropane, and + trifluoroiodomethane from 293.2 to 313.2 K and 30 to 100 bar  

SciTech Connect

Bromotrifluoromethane (halon-1301) and bromochlorodifluoromethane (halon-1211) have been used as clean, nontoxic, and effective fire extinguishing agents for a long time. But these compounds are being phased out because of their ozone-depletion potential. Isothermal vapor-liquid equilibria were measured in the binary systems nitrogen + bromotrifluoromethane, nitrogen + bromochlorodifluoromethane, nitrogen + 1,1,1,2,3,3,3-heptafluoropropane, and nitrogen + trifluoroiodomethane in a circulation-type equilibrium apparatus. The temperature range was (293.2 to 313.2) K and the pressure range was (30 to 100) bar. The experimental data were well correlated with the Peng-Robinson equation of state using the Wong and Sandler mixing rule, and the relevant parameters are presented.

Lim, J.S.; Kim, J.D. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology

1997-01-01

292

Isobaric Analog States in CL35.  

National Technical Information Service (NTIS)

The gamma-ray yield from the S34(p, gamma)Cl35 reaction shows strong resonances at proton energies of 1214 and 1512 keV. These resonance states occur at the correct energies to be isobaric analogs of the 1.99- and 2.35-MeV states in S35, respectively. Ang...

D. D. Watson J. C. Manthuruthil F. D. Lee

1968-01-01

293

Neutron Spectroscopic Factors from Isobaric Analog States.  

National Technical Information Service (NTIS)

The spectroscopic factors S sub n of bound neutron states are usually found from (d,p) stripping reactions. An alternative method of finding S sub n for medium-to-heavy nuclei is to analyze isobaric analog resonances observed in (p,p) scattering from thes...

W. J. Thompson J. L. Adams D. Robson

1968-01-01

294

Isobaric 1 exp + -States of Spherical Nuclei.  

National Technical Information Service (NTIS)

Isobaric 1 exp + states of spheric nuclei are studied in the framework of the final Fermi-system theory. Characteristics of these states (the Gamow-Teller resonance (GTR) and for collective configuration states (CCS))are considered numerically and analyti...

Y. V. Gaponov Y. S. Lyutostanskii

1974-01-01

295

Fine Structure of Isobaric Analog States.  

National Technical Information Service (NTIS)

The split isobaric analog states arising in medium-heavy nuclei were analized in (p, gamma ) reactions using differential excitation functions. The spin and parity of the states on the gsub(9/2) shell model orbit were determined from angular distributions...

I. Fodor

1980-01-01

296

Synthesis and characterization of group IV semiconductor nanowires by vapor-liquid-solid growth  

NASA Astrophysics Data System (ADS)

There is currently intense interest in one-dimensional nanostructures, such as nanotubes and nanowires, due to their potential to test fundamental concepts of dimensionality and to serve as building blocks for nanoscale devices. Vapor-liquid-solid (VLS) growth, which is one of the most common fabrication methods, has been used to produce single crystal semiconductor nanowires such as silicon (Si), germanium (Ge), and gallium arsenide (GaAs). In the VLS growth of Group IV semiconductor nanowires, a metal, such as gold (Au) is used as a catalyst agent to nucleate whisker growth from a Si-containing (silane (SIH4)) or Ge-containing vapor (germane (GeH 4)). Au and Si/Ge form a liquid alloy that has a eutectic temperature of around 360°C, which, upon supersaturation, nucleates the growth of a Si or Ge wire. The goal of this work is to develop a more fundamental understanding of VLS growth kinetics and intentional doping of Group IV semiconductor nanowires in order to better control the properties of the nanowires. The fabrication of p-type and n-type Si nanowires will be studied via the addition of dopant gases such as diborane (B2H 6), trimethylboron (TMB), and phosphine (PH3) during growth. The use of gaseous dopant sources provides more flexibility in growth, particularly for the fabrication of p-n junctions and structures with axial dopant variations (e.g. p+-p- p+). The study is then extended to fabricate SiGe alloy nanowires by mixing SiH4 and GeH4. Bandgap engineering in Si/SiGe heterostructures can lead to novel devices with improved performance compared to those made entirely of Si. The scientific findings will lead to a better understanding of the fabrication of Si/SiGe axial and radial heterostructure nanowires for functional nanowire device structures, such as heterojunction bipolar transistors (HBTs) and high electron mobility transistors (HEMTs). Eventually, the central theme of this research is to provide a scientific knowledge base and foundation for the design of Si, Ge, and SiGe nanostructures that will be of importance in nanoscale device applications.

Lew, Kok-Keong

297

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

USGS Publications Warehouse

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

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

2008-01-01

298

Effects of vapor-liquid equilibria on coke deposition in trickle-bed reactors during heavy oil processing. 2: Modeling  

SciTech Connect

A model which describes the amount of coke deposited onto the catalyst during heavy oil conversion in a trickle-bed reactor is presented. The model comprises on one hand the cracking reactions (multicomponent kinetics) and coke formation kinetics (thermal and catalytic coke) and on the other hand the vapor--liquid equilibria of the reaction mixture. The latter aspect provides crucial to describing the distinct maxima of the amount of coke formed as a function of both the hydrogen-to-oil ratio and the temperature in processing heavy vacuum gas oil. The quantitative predictive power of the model is demonstrated.

Jong, K.P. de (Shell Research B. V., Amsterdam (Netherlands). Koninklijke/Shell-Laboratorium)

1994-12-01

299

Vertically Aligned InP Nanowires Grown via the Self-Assisted Vapor--Liquid--Solid Mode  

NASA Astrophysics Data System (ADS)

We have demonstrated the growth of vertical InP nanowires via the self-assisted vapor--liquid--solid mode on an InP(111) substrate. Single nanowires exhibit a highly uniform diameter along the axial direction despite their 15 ?m length. We show direct evidence of the self-assisted growth mode by performing a compositional analysis of the NW tip. We demonstrated that the In particle at the NW tip could be removed by modifying the V/III source material ratio during growth. Single InP nanowires exhibit a distinct TO phonon peak and show the luminescence of the excitonic emission at 4 K.

Zhang, Guoqiang; Tateno, Kouta; Gotoh, Hideki; Sogawa, Tetsuomi

2012-05-01

300

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

SciTech Connect

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

301

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

SciTech Connect

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

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

1993-09-01

302

Top-gated field effect transistors fabricated using thermally-oxidized silicon nanowires synthesized by vapor-liquid solid growth  

Microsoft Academic Search

This paper discusses the oxidation of p- and n-type silicon nanowires (SiNWs) grown by the vapor-liquid-solid (VLS) method and their integration into top-gated FETs. The oxidization of the as-grown SiNWs was carried out at 900degC in dry oxygen following standard cleaning process (SCI & SC2). The resulting Si\\/SiO2 core-shell NWs were integrated into top-gated FETs where the SiO2 shell served

Tsung-ta Ho; Bangzhi Liu; S. Eichfeld; Kok-Keong Lew; S. Mohney; J. Redwing; T. Mayer

2007-01-01

303

An automated apparatus for equilibrium phase compositions, densities, and interfacial tensions: data for carbon dioxide + decane  

Microsoft Academic Search

An existing vapor–liquid equilibrium facility has been automated to measure simultaneously liquid and vapor equilibrium phase compositions, phase densities, and interfacial tensions. Experimental measurements have been made for CO2+decane at 344.3K. The newly acquired data were compared with those of five other sources. Excellent agreement was observed for the phase densities of this work and those of Nagarajan et al.

R. D Shaver; R. L Robinson; K. A. M Gasem

2001-01-01

304

Phase Equilibrium and Volumetric Properties of Coal-Derived Fluids. Quarterly Report, June 15--September 15, 1977.  

National Technical Information Service (NTIS)

A contract has been awarded for the investigation of (a) the volumetric properties of gases typical of those produced in coal gasification operations and (b) the vapor-liquid equilibrium behavior of mixtures typical of those occurring in the processing of...

R. L. Robinson

1977-01-01

305

Phase Equilibrium and Volumetric Properties of Coal-Derived Fluids. Quarterly Report, June 16--September 15, 1978.  

National Technical Information Service (NTIS)

Research was continued on (a) the volumetric properties of gases typical of those produced in coal gasification operations and (b) the vapor-liquid equilibrium behavior of mixtures typical of those occurring in the processing of coal-derived fluids. Data ...

R. L. Robinson

1978-01-01

306

Phase Equilibrium and Volumetric Properties of Coal-Derived Fluids. Quarterly Report, March 16, 1978--June 15, 1978.  

National Technical Information Service (NTIS)

A contract has been awarded for investigation of (a) the volumetric properties of gases typical of those produced in coal gasification operations and (b) the vapor-liquid equilibrium behavior of mixtures typical of those occurring in the processing of coa...

R. L. Robinson

1978-01-01

307

Nearly Complete Isobar Suppression by Photodetachment  

SciTech Connect

The efficiency of selective suppression of negative ions by photodetachment in a gas-filled radio frequency quadrupole ion cooler was investigated with a new detection method. A neodymium doped yttrium aluminum garnet laser beam at 1064 nm was used to remove Co ions in the radio frequency quadrupole cooler and the remaining ions were then probed by photodetachment and neutral particle detection. More than 99.99% suppression of the Co ions was observed. Under identical conditions, only 20% of a Ni beam was suppressed. The results demonstrate that this isobar suppression technique can lead to nearly complete elimination of certain isobaric contaminants in negative ion beams, opening up new experimental possibilities in nuclear and atomic research and accelerator mass spectrometry.

Andersson, P. [University of Gothenburg, Sweden; Lindahl, A. O. [University of Gothenburg, Sweden; Hanstorp, D. [University of Gothenburg, Sweden; Havener, Charles C [ORNL; Liu, Yun [ORNL; Liu, Yuan [ORNL

2010-01-01

308

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

PubMed

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

Vembanur, Srivathsan; Venkateshwaran, Vasudevan; Garde, Shekhar

2014-04-29

309

Isospin purity in the A=42 isobars  

SciTech Connect

The lifetime of the first 2{sub T=1}{sup +} state in 42Sc has been measured as 74(16) fs. This result gives a value for the isoscalar matrix element of M0=6.63(76). From the mirror nuclei, 42Ca and 42Ti, the isoscalar matrix element is given as 7.15(48) W.u., confirming isospin purity in the A=42 isobars.

Orce, J.N.; McKay, C.J.; Choudry, S.N.; Lesher, S.L.; Mynk, M.; Bandyopadhyay, D.; Yates, S.W.; McEllistrem, M.T. [University of Kentucky, Lexington, Ky 40506-0055 (United States); Petkov, P. [Institute for Nuclear Research and Nuclear Energy, Sofia 11784 (Bulgaria); Institut fuer Kernphysik der Universitaet zu Koeln, 50937 Cologne (Germany)

2004-09-13

310

Sea-Level Pressure: Contouring Isobars  

NSDL National Science Digital Library

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

311

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

312

Shadowing and mask opening effects during selective-area vapor-liquid-solid growth of InP nanowires by metalorganic molecular beam epitaxy  

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

313

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

USGS Publications Warehouse

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

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

1986-01-01

314

High-pressure vapor-liquid equilibria of two binary systems: Carbon dioxide + cyclohexanol and carbon dioxide + cyclohexanone  

SciTech Connect

Vapor-liquid equilibria for carbon dioxide + cyclohexanol and carbon dioxide + cyclohexanone were measured using an apparatus based on a static-analytic method with in situ samplings. P, T, x, y measurements were made at pressures up to 22 MPa. The carbon dioxide + cyclohexanol system was studied at 433 and 473 K, and carbon dioxide + cyclohexanone, at 433 and 473 K. The results are correlated by the Redlich-Kwong-Soave and Peng and Robinson equations and several mixing rules. The best fittings are obtained with the Peng-Robinson equation of state and a two-parameter mixing rule, i.e., within 1.1% for both pressures and vapor mole fractions on the carbon dioxide + cyclohexanone system and within 1.9% for pressures and 2.9% for vapor mole fractions on the carbon dioxide + cyclohexanol system. More recent equations by Patel and Teja and Salim and Trebble show no significant advantages.

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)

1997-01-01

315

Constructing a superhydrophobic surface on polydimethylsiloxane via spin coating and vapor-liquid sol-gel process.  

PubMed

In this study, a superhydrophobic surface on polydimethylsiloxane (PDMS) substrate was constructed via the proposed vapor-liquid sol-gel process in conjunction with spin coating of dodecyltrichlorosilane (DTS). Unlike the conventional sol-gel process where the reaction takes place in the liquid phase, layers of silica (SiO(2)) particles were formed through the reaction between the reactant spin-coated on the PDMS surface and vapor of the acid solution. This led to the SiO(2) particles inlaid on the PDMS surface. Followed by subsequent spin coating of DTS solution, the wrinkle-like structure was formed, and the static contact angle of the water droplet on the surface could reach 162 degrees with 2 degrees sliding angle and less than 5 degrees contact angle hysteresis. The effect of layers of SiO(2) particles, concentrations of DTS solution and surface topography on superhydrophobicity of the surface is discussed. PMID:20020726

Peng, Yu-Ting; Lo, Kuo-Feng; Juang, Yi-Je

2010-04-01

316

Testing the Isobaric Multiplet Mass Equation  

NASA Astrophysics Data System (ADS)

We will present data on an experiment to determine the mass of the lowest T = 2 state in ^32S with an accuracy of ? M/M ? 10-9. An implanted ^31P target was prepared. The state is populated via ^31P+p and the decaying gammas with energies ? 3923 ˜ and ˜ 8126 keV are observed with Ge detectors. newline newline The motivation for the measurement is to improve the precision of a test of the isobaric mass multiplet equation.

Triambak, Smarajit; Garcia, Alejandro; Hodges, Gregory; Sallaska, Anne; West, Chris

2003-10-01

317

Effect of trivalent, bivalent, and univalent cation inorganic salts on the isothermal vapor–liquid equilibria of propionic acid–water system  

Microsoft Academic Search

The effect of five dissolved inorganic salts, namely; aluminum chloride, calcium chloride, potassium chloride, potassium nitrate, and potassium bromide, on the vapor liquid equilibria (VLE) of the binary system propionic acid–water was investigated at 60°C using the headspace gas chromatography technique (HSGC). For various salt concentrations, the influence of the salting out of propionic acid was noted. For a concentration

Fawzi Banat; Sameer Al-Asheh; Jana Simandl

2003-01-01

318

Comparison of high-pressure vapor-liquid equilibria of mixtures of CO{sub 2} or propane with nonane and C{sub 9} alkylbenzenes  

SciTech Connect

Vapor-liquid equilibria were measured for (1) binary mixtures of carbon dioxide with nonane, cumene, propylbenzene, or mesitylene, (2) binary mixtures of propane with nonane, cumene, or mesitylene, and (3) ternary mixtures of carbon dioxide, nonane, and cumene. For the carbon dioxide mixtures, vapor-liquid equilibria were measured at 70 C and at pressures ranging from 3.7 MPa to 12.1 MPa. For the propane mixtures, vapor-liquid equilibria were measured at 104 C and at pressures ranging from 0.9 MPa to 3.7 MPa. It was found that differences in the phase equilibria of the mixtures could be explained primarily by the self-association of the C{sub 9} components. The composition of the C{sub 9} components in the vapor phase compositions were found to be directly related to the volatility (self-association) of the C{sub 9} component. Liquid phase compositions were found to be enriched in carbon dioxide or propane content in the mixtures containing C{sub 9} compounds having the weakest self-association. Also presented in this paper are comparisons of measurements of vapor-liquid equilibria of carbon dioxide + decane and propane + decane with literature data as validation of the two experimental methods used. These measurements were made at 71 C for the carbon dioxide + decane mixtures and at temperatures ranging from 38 C to 120 C for the propane + decane mixtures.

Jennings, D.W.; Schucker, R.C. [Exxon Research and Development Labs., Baton Rouge, LA (United States)] [Exxon Research and Development Labs., Baton Rouge, LA (United States)

1996-07-01

319

Infrared spectroscopic studies of the conformation in ethyl ?-haloacetates in the vapor, liquid and solid phases  

NASA Astrophysics Data System (ADS)

Infrared spectra of ethyl ?-fluoroacetate, ethyl ?-chloroacetate, ethyl ?-bromoacetate and ethyl ?-iodoacetate have been measured in the solid, liquid and vapor phases in the region 4000-200 cm -1. Vibrational frequency assignment of the observed bands to the appropriate modes of vibration was made. Calculations at DFT B3LYP/6-311+G** level, Job: conformer distribution, using Spartan program '08, release 132 was made to determine which conformers exist in which molecule. The results indicated that the first compound exists as an equilibrium mixture of cis and trans conformers and the other three compounds exist as equilibrium mixtures of cis and gauche conformers. Enthalpy differences between the conformers have been determined experimentally for each compound and for every phase. The values indicated that the trans of the first compound is more stable in the vapor phase, while the cis is the more stable in both the liquid and solid phases. In the other three compounds the gauche is more stable in the vapor and liquid phases, while the cis conformer is the more stable in the solid phase for each of the second and third compound, except for ethyl ?-iodoacetate, the gauche conformer is the more stable over the three phases. Molar energy of activation Ea and the pseudo-thermodynamic parameters of activation ? H‡, ? S‡ and ? G‡ were determined in the solid phase by applying Arrhenius equation; using bands arising from single conformers. The respective Ea values of these compounds are 5.1 ± 0.4, 6.7 ± 0.1, 7.5 ± 1.3 and 12.0 ± 0.6 kJ mol -1. Potential energy surface calculations were made at two levels; for ethyl ?-fluoroacetate and ethyl ?-chloroacetate; the calculations were established at DFT B3LYP/6-311+G** level and for ethyl ?-bromoacetate and ethyl ?-iodoacetate at DFT B3LYP/6-311G* level. The results showed no potential energy minimum exists for the gauche conformer in ethyl ?-fluoroacetate.

Jassem, Naserallah A.; El-Bermani, Muhsin F.

2010-07-01

320

Coulomb energy differences in isobaric multiplets  

SciTech Connect

By comparing the excitation energies of analogue states in isobaric multiplets, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. In particular, the mirror nuclei 35Ar and 35Cl show large differences between the excitation energies of analogue negative-parity states at high spin, confirming the important contribution of the relativistic electromagnetic spin-orbit interaction to the Coulomb energy. The single-particle character of the configuration of these states is reproduced with very good accuracy by shell model calculations in the sd and pf shells valence space. In addition, evidence of isospin mixing is deduced from the El transitions linking positive and negative parity states.

Lenzi, S. M.; Farnea, E.; Bazzacco, D.; Brandolini, F.; Lunardi, S.; Mason, P.; Menegazzo, R.; Nespolo, M.; Ur, C. A. [Dipartimento di Fisica dell' Universita, Padova (Italy); INFN, Padova (Italy); Della Vedova, F.; Marginean, N.; Napoli, D. R.; De Angelis, G.; Axiotis, M.; Gadea, A. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Ionescu-Bujor, M.; Bucurescu, D.; Iordachescu, A. [National Institute for Physics and Nuclear Engineering, Bucharest (Romania); Bizzeti-Sona, A. M.; Bizzeti, P. G. [Dipartimento di Fisica dell' Universita, Florence (Italy); INFN, Florence (Italy)] (and others)

2007-02-12

321

Theoretical study of vapor-liquid homogeneous nucleation using stability analysis of a macroscopic phase.  

PubMed

Stability analysis is generally used to verify that the solution to phase equilibrium calculations corresponds to a stable state (minimum of the free energy). In this work, tangent plane distance analysis for stability of macroscopic mixtures is also used for analyzing the nucleation process, reconciling thus this analysis with classical nucleation theories. In the context of the revised nucleation theory, the driving force and the nucleation work are expressed as a function of the Lagrange multiplier corresponding to the mole fraction constraint from the minimization problem of stability analysis. Using a van der Waals fluid applied to a ternary mixture, Lagrange multiplier properties are illustrated. In particular, it is shown how the Lagrange multiplier value is equal to one on the binodal and spinodal curves at the same time as the driving force of nucleation vanishes on these curves. Finally, it is shown that, on the spinodal curve, the nucleation work from the revised and generalized nucleation theories are characterized by two different local minima from stability analysis, irrespective of any interfacial tension models. PMID:23061836

Carreón-Calderón, Bernardo

2012-10-14

322

Vapor-liquid activity coefficients for methanol and ethanol from heat of solution data: application to steam-methane reforming.  

PubMed

This paper presents equations and curves to calculate vapor-liquid phase equilibria for methanol and ethanol in dilute aqueous solution as a function of temperature, using activity coefficients at infinite dilution. These thermodynamic functions were originally derived to assess the distribution of by-product contaminants in the process condensate and the steam-system deaerator of a hydrogen plant [Paper ENV-00-171 presented at the NPRA 2000 Environmental Conference, San Antonio, TX, 10-12 September 2000], but have general applicability to other systems as well. The functions and calculation method described here are a necessary piece of an overall prediction technique to estimate atmospheric emissions from the deaerator-vent when the process condensate is recycled as boiler feed water (BFW) make-up. Having such an estimation technique is of particular significance at this time because deaerator-vent emissions are already coming under regulatory scrutiny in California [Emissions from Hydrogen Plant Process Vents, Adopted 21 January 2000] followed closely elsewhere in the US, and eventually worldwide. The overall technique will enable a permit applicant to estimate environmental emissions to comply with upcoming regulations, and a regulatory agency to evaluate those estimates. It may also be useful to process engineers as a tool to estimate contaminant concentrations and flow rates in internal process streams such as the steam-generating system. Metallurgists and corrosion engineers might be able to use the results for materials selection. PMID:11606240

Kunz, R G; Baade, W F

2001-11-16

323

Nucleation and hysteresis of vapor-liquid phase transitions in confined spaces: Effects of fluid-wall interaction  

NASA Astrophysics Data System (ADS)

In this work, we propose a method to stabilize a nucleus in the framework of lattice density-functional theory (LDFT) by imposing a suitable constraint. Using this method, the shape of critical nucleus and height of the nucleation barrier can be determined without using a predefined nucleus as input. As an application of this method, we study the nucleation behavior of vapor-liquid transition in nanosquare pores with infinite length and relate the observed hysteresis loop on an adsorption isotherm to the nucleation mechanism. According to the dependence of hysteresis and the nucleation mechanism on the fluid-wall interaction, w , in this work, we have classified w into three regions ( w>0.9 , 0.1?w?0.9 , and w<0.1 ), which are denoted as strongly, moderately, and weakly attractive fluid-wall interaction, respectively. The dependence of hysteresis on the fluid-wall interaction is interpreted by the different nucleation mechanisms. Our constrained LDFT calculations also show that the different transition paths may induce different nucleation behaviors. The transition path dependence should be considered if morphological transition of nuclei exists during a nucleation process.

Men, Yumei; Yan, Qingzhao; Jiang, Guangfeng; Zhang, Xianren; Wang, Wenchuan

2009-05-01

324

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

SciTech Connect

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

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

1995-07-01

325

A flux induced crystal phase transition in the vapor-liquid-solid growth of indium-tin oxide nanowires.  

PubMed

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

2014-05-29

326

Toluene Diisocyanate Reactivity with Glutathione Across a Vapor/Liquid Interface and Subsequent Transcarbamoylation of Human Albumin  

PubMed Central

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.

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

2012-01-01

327

Vapor-liquid equilibria in the nitrogen + carbon dioxide + propane system from 240 to 330 K at pressures to 15 MPa  

SciTech Connect

The design and development of separation processes in the natural gas industry requires accurate knowledge of the vapor-liquid equilibria of multicomponent systems consisting of the alkane hydrocarbons with carbon dioxide and nitrogen. Vapor-liquid equilibria were measured for the nitrogen, carbon dioxide, and propane ternary system and its constituent binaries over the temperature range 240 K to 330 K. The binary systems were measured at 240, 270, and 330 K, and the ternary system was studied at 240 K for 2.0 and 13.0 MPa, 270 K for 2.0, 6,0, and 13.0 MPa, and 330 K and 5 MPa. The Peng-Robinson equation of state was used to model the system.

Yucelen, B.; Kidnay, A.J. [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering and Petroleum-Refining] [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering and Petroleum-Refining

1999-09-01

328

Prediction of vapor–liquid equilibria in non-polymer and polymer solutions using an ASOG-based equation of state (PRASOG)  

Microsoft Academic Search

An ASOG-based equation of state called PRASOG (Peng–Robinson ASOG) has been developed to predict vapor–liquid equilibria in non-polymer and polymer solutions. It makes use of the zero-pressure GE mixing rule consistent with the second virial coefficient condition for calculating the mixture parameters in Peng–Robinson EOS and predicts the GE using ASOG method. The first object of this paper is to

Katsumi Tochigi

1998-01-01

329

Representation of vapor-liquid and liquid-liquid equilibria for binary systems containing polymers: Applicability of an extended Flory-Huggins equation  

Microsoft Academic Search

For some binary systems, an extended Flory-Huggins equation is applicable to both vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) using the same adjustable parameters. New LLE and VLE data are reported for polystyrene (PS) (MW = 100,000)\\/ cyclohexane and for poly(ethylene glycol) (PEG) (MW = 8,000)\\/water. Experimental results for the PS\\/cyclohexane system agree well with the semiempirical model, whereas those

Y. C. Bae; J. J. Shim; D. S. Soane; J. M. Prausnitz

1993-01-01

330

An investigation on void fraction of vapor–liquid two-phase flow for smooth and microfin tubes with R134a at adiabatic condition  

Microsoft Academic Search

The present paper deals with experiments and a prediction method for the void fraction of R134a vapor–liquid two-phase flow in horizontal smooth and microfin tubes in adiabatic condition. The void fraction is measured by the quick closing valve method. The smooth tube tested is 1024 mm in length and 7.52 mm in inside diameter. The microfin tube tested is 1015

Shigeru Koyama; Joodong Lee; Ryuuichirou Yonemoto

2004-01-01

331

Isothermal vapor-liquid equilibria for 2-propanol + octane and 2-propanol + 2,2,4-trimethylpentane at 348.15 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibria were measured for 2-propanol + octane and 2-propanol + 2,2,4-trimethylpentane at 348.15 K. The measurements were made in a Rogalski-Malanowski-type still with circulation of both vapor and liquid phases. Both binary isothermal systems form a maximum pressure azeotrope. The azeotropic data are x1(AZ) = 0.882 mole fraction and P(AZ) = 78.20 kPa for 2-propanol (1) + octane

Toshihiko Hiaki; Tomoya Tsuji; Masaru Hongo

1996-01-01

332

Vapor-liquid equilibria of ethanol + 2,2,4-trimethylpentane at 333. 15 K and 1-propanol + 2,2,4-trimethylpentane at 343. 15 K  

Microsoft Academic Search

Isothermal vapor-liquid equilibria were measured for ethanol + 2,2,4-trimethylpentane at 333.15 K and 1-propanol + 2,2,4-trimethylpentane at 343.15 K. The measurements were made in a still with the aid of a computer for control of the temperature and measurement of the total pressure. The experimental results were best correlated with the Wilson equation.

Toshihiko Hiaki; Kenji Takahashi; Tomoya Tsuji; Masaru Hongo; Kazuo Kojima

1994-01-01

333

Vapor-liquid equilibria in toluene + m-Xylene, toluene + n-decane, and n-deane + m-xylene mixtures  

SciTech Connect

Isothermal vapor-liquid equilibria at three temperatures between 373.5 and 394.3 K were measured for the binary systems toluene + m-xylene, toluene + n-decane, and n-decane + m-xylene by using a recirculating still. The data reported were found to be thermodynamically consistent and were correlated with four well-known activity coefficient models. The maximum likelihood method was used to estimate the parameters of the models.

Willman, B.; Teja, A.S.

1985-01-01

334

Escape- and Spreading Width of the Isobaric Analog State.  

National Technical Information Service (NTIS)

Data and systematics on the natural line width, the escape width, and the spreading width of ground state isobaric analog states are presented. The relation between isospin impurity and spreading width, and between escape width and neutron spectroscopic f...

S. Y. Vanderwerf

1991-01-01

335

A flux induced crystal phase transition in the vapor-liquid-solid growth of indium-tin oxide nanowires  

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available: STEM mapping of In and Sn in an ISO nanowire (Fig. S1) and homogeneity of a fluorite ISO phase at the full length of a nanowire (Fig. S2). See DOI: 10.1039/c4nr01016g

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

2014-05-01

336

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

PubMed

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

337

Application of the SAFT-VR equation of state to vapor–liquid equilibrium calculations for pure components and binary mixtures using the Sutherland potential  

Microsoft Academic Search

An equation of state based on the statistical associating fluid theory for potentials of variable range (SAFT-VR) has been applied to model 35 pure associating and non-associating fluids and 15 binary mixtures. The pure components consist of alkanes, alcohols, water, aromatics and polar or multi-polar compounds like ammonia and H2S. In contrast to other attempts which have used the SAFT-VR

F. Paragand; F. Feyzi; B. Behzadi

2010-01-01

338

Phase equilibrium modeling of mixtures of long-chain and short-chain alkanes using Peng–Robinson and SAFT  

Microsoft Academic Search

Peng–Robinson and selected implementations of the Statistical Associating Fluid Theory (SAFT) equation of state (EoS) were evaluated for their ability to correlate and predict vapor–liquid equilibrium for highly asymmetric mixtures of n-alkanes. Peng–Robinson is surprisingly accurate for fitting such mixtures, but only if the pure component parameters are regressed with vapor pressure and liquid density data, as is normally done

P. David Ting; Patrick C. Joyce; Prasanna K. Jog; Walter G. Chapman; Mark C. Thies

2003-01-01

339

Effects of vapor-liquid equilibria on coke deposition in trickle-bed reactors during heavy oil processing; 1: Experimental results  

SciTech Connect

The deposition of coke onto catalysts during the conversion of heavy vacuum gas oil has been investigated in a trickle-bed reactor at elevated temperatures (ca. 450 C) and moderate hydrogen pressures (30 bar). It is argued that coke is formed via two parallel routes, viz., (i) thermal condensation reactions of aromatic moieties and (ii) catalytic dehydrogenation reactions. The amount of coke deposited onto the catalyst shows a distinct maximum as a function of both temperature and hydrogen/oil ratio. These maxima are induced by the vapor-liquid equilibria in the reactor. A qualitative description involving the concentration of heavy coke precursors present in the oil phase is given.

Jong, K.P. de (Koninklijke/Shell Lab., Amsterdam (Netherlands))

1994-04-01

340

Critical temperature of LaBa 2Cu 3O y thin films by vapor-liquid-solid growth technique improved by the composition ratio in liquid phase  

NASA Astrophysics Data System (ADS)

In order to improve a critical temperature ( Tc) of LaBa 2Cu 3O y (LaBCO) thin films for achieving a high irreversibility field, we investigated the vapor-liquid-solid (VLS) technique with various composition ratios of Ba/Cu in a liquid layer as growth solvent. As a result, we achieved the VLS-LaBCO thin films with excellent crystallinity and observed a spiral growth consisted of the wide terrace with a width of about 300 nm. Moreover, the orthorhombicity and the Tc onset of VLS-LaBCO thin films increased with increasing Ba/Cu ratio in the liquid layer.

Funaki, S.; Ichino, Y.; Yoshida, Y.; Inoue, K.; Takai, Y.; Matsumoto, K.; Mukaida, M.; Ichinose, A.; Horii, S.

2008-09-01

341

Trends in the Isobaric Multiplet Mass Equation Coefficients  

NASA Astrophysics Data System (ADS)

Isobaric analogue states (IAS) can be used to study the charge independence of the nuclear force via first order perturbation theory. In this case the IAS multiplet masses are expected to follow a quadratic form as described by the Isobaric Multiplet Mass Equation (IMME) with coefficients accessible through experimental measurements. Higher order effects are expected to appear through cubic, or higher, polynomial terms. The current IMME coefficient trends, as based on the IAS states included in the 2012 Atomic Mass Evaluation and NUBASE2012 are shown.

MacCormick, Marion; Audi, Georges

2014-03-01

342

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

SciTech Connect

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

Higashi, Y.

1999-09-01

343

Measurements of the vapor-liquid coexistence curve in the critical region and the critical parameters of 1,1,2,2,-tetrafluoroethane  

SciTech Connect

The vapor-liquid coexistence curve in the critical region of 1,1,2,2-tetrafluoroethane (HFC-134) was measured by a visual observation of the meniscus in an optical cell. Eighteen saturated liquid densities and 10 saturated vapor densities have been obtained in a temperature range from 364 K to the critical temperature, corresponding to a density range from 243 to 1001 kg/m[sup 3]. The experimental uncertainties of temperature and density measurements are estimated to be within [plus minus]10 mK and between [plus minus]0.11% and [plus minus]0.44%, respectively. Not only the level where the meniscus disappeared but also the intensity of the critical opalescence was considered in the determination of the critical temperature and density being 391.74 [plus minus] 0.02 K (ITS-90) and 536 [plus minus] 2 kg/m[sup 3], respectively. The critical exponent of the power law, [beta], was also determined as 0.347 [plus minus] 0.002. A saturated vapor-liquid density correlation has been developed on the basis of the present measurements.

Tatoh, Jun; Kuwabara, Shigeo; Sata, Haruki; Watanabe, Koichi (Keio Univ., Yokohama (Japan). Dept. of Mechanical Engineering)

1993-01-01

344

K-shell ionization across isobaric analog resonances  

NASA Astrophysics Data System (ADS)

K-shell ionization probabilities PK near isobaric analog resonances are calculated including contributions from compound-nucleus scattering. For projectile scattering angles less than 90°, compound-nucleus scattering has a negligible effect on PK, but at large angles PK is affected considerably if compound-nucleus scattering is included. Present address: Department of Physics, TU-Munich, D-8046 Garching, West Germany.

Anholt, R.; Chemin, J. F.; Amundsen, P. A.

1982-12-01

345

Shift of the velocity of low-frequency pressure perturbations in the vapor-liquid mixture under nonadiabatic conditions  

NASA Astrophysics Data System (ADS)

A theoretical study of the equilibrium velocity of sound in the liquid-vapor mixture containing the close-packed layer of spherical particles has been carried out. Thermodynamic relations include a description of a non-stationary heat transfer between the mixture and particles in compression half-wave. The theoretical model allows explaining the experimentally observed significant reduction in the equilibrium velocity from its adiabatic value at the increase in vapor content of the mixture. The calculated results agree with experimental data obtained in the vertical channel at filtering the liquid-vapor mixture in a close-packed layer of spherical particles of borosilicate glass and steel.

Tairov, E. A.

2013-09-01

346

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

USGS Publications Warehouse

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

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

1990-01-01

347

Monte Carlo simulation of homogeneous binary vapor–liquid nucleation: Mutual enhancement of nucleation in a partially miscible system  

Microsoft Academic Search

By means of a constrained canonical-ensemble Monte Carlo technique the equilibrium physical cluster distribution {nij} in a supersaturated vapor mixture is computed. From this the intensive Gibbs free energy of ij-cluster formation ?Gij is obtained via the relation nij=Ne??Gij\\/kBT, where N is the number of molecules in the system, T is temperature, and kB is the Boltzmann constant. The saddle

S. Yoo; K. J. Oh; X. C. Zeng

2001-01-01

348

Monte Carlo simulation of homogeneous binary vapor-liquid nucleation: Mutual enhancement of nucleation in a partially miscible system  

Microsoft Academic Search

By means of a constrained canonical-ensemble Monte Carlo technique the equilibrium physical cluster distribution {nij} in a supersaturated vapor mixture is computed. From this the intensive Gibbs free energy of ij-cluster formation DeltaGij is obtained via the relation nij=Ne-DeltaGij\\/kBT, where N is the number of molecules in the system, T is temperature, and kB is the Boltzmann constant. The saddle

S. Yoo; K. J. Oh; X. C. Zeng

2001-01-01

349

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range  

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. Martín del Río, E. de Miguel, and G. Jackson, Mol. Phys. 99, 1851 (2001); G. J. Gloor, F. J. Blas, E. Martín del Río, 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

350

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

NASA Technical Reports Server (NTRS)

The microwave brightness temperature measurements for Nimbus-5 electrically scanned microwave radiometer 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

351

Heat pipes for spacecraft temperature control: An assessment of the state-of-the-art. [gas, vapor, liquid, and voltage control  

NASA Technical Reports Server (NTRS)

Spacecraft applications that require the efficient cooling of high-powered components, the precise temperature control of sensitive electronic and optical components, and the protection of cooled components from temporary, adverse environmental conditions are increasing. Heat pipes using gas, vapor, liquid, or voltage control to provide variable conductance or diode thermal behavior have been and are continuing to be developed to meet increasingly difficult requirements. The various control techniques are critically evaluated using characteristic features and properties, including heat transport capability, volume and mass requirements, complexity and ease of fabrication, reliability, and control characteristics. As a result, advantages and disadvantages of specific approaches are derived and discussed. Using four development levels, the state-of-the-art of the various heat pipe temperature control techniques is assessed.

Groll, M.; Kirkpatrick, J. P.

1976-01-01

352

Thermodynamic modeling of vapor-liquid equilibria and excess properties of the binary systems containing diethers and n-alkanes by cubic equation of state  

Microsoft Academic Search

A comparison of the performances of two different approaches of cubic equations of state models, based on a classical van\\u000a der Waals and mixing rules incorporating theG\\u000a \\u000a E\\u000a equation, was carried out for correlation of Vapor-Liquid Equilibria (VLE), HE and C\\u000a P\\u000a E\\u000a data alone, and simultaneous correlation of VLE+HE, VLE+C\\u000a P\\u000a E\\u000a , HE +C\\u000a P\\u000a E\\u000a and VLE+HE

Slobodan P. šerbanovi?; Ivona R. Grguri?; Mirjana Lj. Kijev?anin; Aleksandar Z. Tasi?; Bojan D. Djordjevi?

2004-01-01

353

Isobaric analog resonances of the N=21 nucleus 35Si  

NASA Astrophysics Data System (ADS)

Neutron single-particle states in the neutron-rich nucleus 35Si, which is located beside the N=20 shell breaking nucleus 32Mg, were investigated through their isobaric analog resonances. The excitation function for 34Si+p elastic scattering was measured around 0? in the laboratory frame by the thick target inverse kinematics method with a 34Si beam around 5 MeV/nucleon and a thick polyethylene target. Eight resonances were successfully observed. Angular momenta and proton and total widths of the resonances were assigned using R-matrix analysis. With the help of information of the ? decay study, six isobaric analog resonances were identified. Spectroscopic factors and spin-parities of the corresponding parent states in 35Si are presented.

Imai, N.; Hirayama, Y.; Watanabe, Y. X.; Teranishi, T.; Hashimoto, T.; Hayakawa, S.; Ichikawa, Y.; Ishiyama, H.; Jeong, S. C.; Kahl, D.; Kubono, S.; Miyatake, H.; Ueno, H.; Yamaguchi, H.; Yoneda, K.; Yoshimi, A.

2012-03-01

354

Isobaric Analogue States Studied in Mirrored Fragmentation and Knockout Reactions  

SciTech Connect

A Gamma-ray spectroscopic study of excited states of isobaric multiplets has been performed in recent years, with a view to gaining a quantitative understanding of energy differences between excited states in terms of a range of Coulomb and other isospin breaking phenomena. Recently, the experimental programme has been augmented by a study of isobaric analogue states of mirror nuclei populated in mirrored fragmentation reactions. In this presentation, recent results on the T = 3/2 analogue states in the T{sub z} = {+-} 3/2 mirror pair {sup 53}Ni/{sup 53}Mn will be summarised. In this work, further strong evidence is found for the need to include an anomalous isospin-breaking two-body matrix element for angular-momentum couplings of J = 2, in addition the expected Coulomb contribution, in order to account for the experimental data.

Bentley, M.A.; Pritychenko, B.; Paterson,I.; Brown,J.R.; Taylor,M.J.; Digen,C.Aa.; Adrich,P.; Bazin,D.; Cook.J.M.; Gade,A.; Glasmacher,T.; McDaniel,S.; Ratkiewicz,A.; Siwek,K.; D.Weisshaar,D.; Pritychenko,B.; Lenzi,S.M.

2010-05-21

355

The ground state of nuclear matter with virtual ?-isobar excitations  

NASA Astrophysics Data System (ADS)

The equation of state of nuclear matter is studied in the framework of the Bethe-Brueckner-Goldstone theory using the local Argonne v28 potential which explicitly includes ?-isobar degrees of freedom. The self-consistent two-body reaction matrix is obtained with all possible allowed couplings to the N? and ?? states. Saturation occurs around kF=1.2 fm -1 with a binding energy per particle {B}/{A}=-10.31 MeV, confirming the effect of the isobar in pushing the saturation point to the upper side of the Coester band. The present results are very close to the ones obtained in full coupled-channel relativistic calculations.

Baldo, M.; Ferreira, L. S.

1991-11-01

356

Reference pressure changes and available potential energy in isobaric coordinates  

NASA Technical Reports Server (NTRS)

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

Robertson, F. R.

1985-01-01

357

Shotgun proteomics using the iTRAQ isobaric tags  

Microsoft Academic Search

Shotgun proteomic methods involving isobaric tagging of peptides enable high-throughput proteomic analysis. iTRAQ reagents allow simultaneous identification and quantitation of proteins in four different samples using tandem mass spectrometry (MS). In this article, we provide a brief description of proteome analysis using iTRAQ reagents and review the current applications of these reagents in proteomic studies. We also compare different aspects

Kunal Aggarwal; Leila H. Choe; Kelvin H. Lee

2006-01-01

358

Isobaric-Spin Mixing in BE8 States.  

National Technical Information Service (NTIS)

The Li7(He3,d)Be8 reaction was studied using a magnetic spectrometer in order to obtain precise values for the widths of the isobaric-spin-mixed states at 16.6 and 16.9 MeV in Be8. The results are Gamma(16.6) = 113 +3 or -3 keV and Gamma(16.9) = 77 +3 or ...

J. B. Marion P. H. Nettles C. L. Cocke C. J. Stephenson

1966-01-01

359

Inertial confinement fusion: Ignition of isobarically compressed DT targets  

Microsoft Academic Search

Summary  Ignition of initially isobaric D-T plasmas, triggered by a hot spot, surrounded by denser, cold fuel, is studied both analytically\\u000a and numerically. It the conditions for self-heating of the not spot are met, then a burn wave propagates, at first through\\u000a deflagration driven by ?-particles, and eventually through detonation. After an initial transient phase and the self-heating\\u000a stage, burn in

S. Atzeni; A. Caruso

1984-01-01

360

Shear viscosity and thermal conductivity of dipolar real fluids from equilibrium molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

Equilibrium molecular dynamics and the Green-Kubo formalism were used to simultaneously calculate shear viscosity and thermal conductivity for 10 refrigerants: R11, R12, R22, R23, R41, R123, R134a, R142b, R143a, and R152a. The fluids were modelled in previous work of Stoll et al. [J Chem Phys 2003;119:11396-407] using the two-center Lennard-Jones plus point dipole (2CLJD) pair potential, with parameters adjusted to vapor-liquid equilibria only. The predicted shear viscosities and thermal conductivities show an overall average deviation of about 15% and 10%, respectively, from correlations of experimental data.

Fernández, Gimmy A.; Vrabec, Jadran; Hasse, Hans

2006-10-01

361

Calculation of NARM's equilibrium with Peng-Robinson equation of state  

NASA Astrophysics Data System (ADS)

The liquid molar volumes of nonazeotropic refrigerant mixtures (NARM), calculated with Peng Robinson (PR) equation, were compared with vapor -liquid equilibrium experimental data in this paper. Provided with co-reaction coefficient k ij , the discrepancies of liquid molar volume data for R22+R114 and R22+R142b using PR equation are 7.7% and 8.1%, respectively. When HBT (Hankinson-Brobst-Thomson) equation was joined with PR equation, the deviations are reduced to less than 1.5% for both R22+R114 and R22+R142b.

Li, Tingxun; Guo, Kaihua; Wang, Ruzhu; Fan, Shuanshi

2001-04-01

362

Infrared spectroscopic studies of the conformation in ethyl alpha-haloacetates in the vapor, liquid and solid phases.  

PubMed

Infrared spectra of ethyl alpha-fluoroacetate, ethyl alpha-chloroacetate, ethyl alpha-bromoacetate and ethyl alpha-iodoacetate have been measured in the solid, liquid and vapor phases in the region 4000-200 cm(-1). Vibrational frequency assignment of the observed bands to the appropriate modes of vibration was made. Calculations at DFT B3LYP/6-311+G** level, Job: conformer distribution, using Spartan program '08, release 132 was made to determine which conformers exist in which molecule. The results indicated that the first compound exists as an equilibrium mixture of cis and trans conformers and the other three compounds exist as equilibrium mixtures of cis and gauche conformers. Enthalpy differences between the conformers have been determined experimentally for each compound and for every phase. The values indicated that the trans of the first compound is more stable in the vapor phase, while the cis is the more stable in both the liquid and solid phases. In the other three compounds the gauche is more stable in the vapor and liquid phases, while the cis conformer is the more stable in the solid phase for each of the second and third compound, except for ethyl alpha-iodoacetate, the gauche conformer is the more stable over the three phases. Molar energy of activation Ea and the pseudo-thermodynamic parameters of activation DeltaH(double dagger), DeltaS(double dagger) and DeltaG(double dagger) were determined in the solid phase by applying Arrhenius equation; using bands arising from single conformers. The respective E(a) values of these compounds are 5.1+/-0.4, 6.7+/-0.1, 7.5+/-1.3 and 12.0+/-0.6 kJ mol(-1). Potential energy surface calculations were made at two levels; for ethyl alpha-fluoroacetate and ethyl alpha-chloroacetate; the calculations were established at DFT B3LYP/6-311+G** level and for ethyl alpha-bromoacetate and ethyl alpha-iodoacetate at DFT B3LYP/6-311G* level. The results showed no potential energy minimum exists for the gauche conformer in ethyl alpha-fluoroacetate. PMID:20382068

Jassem, Naserallah A; El-Bermani, Muhsin F

2010-07-01

363

Rotational Equilibrium  

NSDL National Science Digital Library

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

Ieee

2013-07-08

364

Gamma decays of isobaric analog states relevant to neutrino detection  

NASA Astrophysics Data System (ADS)

Measurements have been made of the gamma ray branching ratios for the decay of the lowest isobaric analog states of 71Ge and 81Kr. These states could be populated by high-energy neutrinos in gallium- and bromine-based detectors. Although these states are unbound to particle decay, all channels with significant penetrabilities are isospin forbidden, so that gamma decay is a possibility. Our results indicate that these states decay mainly by neutron emission and therefore contribute very little to detection sensitivities for 71Ga and 81Br.

Champagne, A. E.; Dodge, G. E.; Kouzes, R. T.; Lowry, M. M.; McDonald, A. B.; Roberson, M. W.

1988-08-01

365

Isothermal--isobaric molecular dynamics simulation of liquid water  

SciTech Connect

Results of the first isothermal--isobaric molecular dynamics simulation of water are reported. Water molecules are assumed to be flexible and to interact via a sum of pairwise interatomic potentials. Extensive runs for 256 molecules at 298 and 373 K and 1 bar give satisfactory agreement with observed properties of liquid water as diverse as density, internal energy, heat capacity, compressibility, pair correlation functions, diffusion coefficient, vibrational spectrum, relative permittivity, and dielectric relaxation spectra. The nonlinear dependence of the relative permittivity on the electric field is also computed by means of fluctuation--dissipation relations.

Ruff, I.; Diestler, D.J. (Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (USA))

1990-08-01

366

An extension of the Peng–Robinson equation of state for the correlation and prediction of high-pressure phase equilibrium in systems containing supercritical carbon dioxide and a salt  

Microsoft Academic Search

The development of an extended Peng–Robinson equation of state is described, which allows for the consideration of salts in calculations for the high-pressure vapor + liquid phase equilibrium. The extension employs two terms: a Debye–Hückel and a Margules term. The new equation is applied to systems with carbon dioxide, water, methanol, acetic acid, sodium chloride, and sodium acetate. For the

Georg Sieder; Gerd Maurer

2004-01-01

367

Subcontracted R and D final report: SRC-I phase equilibrium and enthalpy data for coal liquefaction and solvent recovery areas. Volume 1. [Mostly gases and light hydocarbons with aromatics and coal liquid fractions  

Microsoft Academic Search

International Coal Refining Company instituted a 2-year program to develop new data on SRC-I coal liquids and related model compounds. Specifically, the overall program obtectives were to develop vapor\\/liquid equilibrium (VLE) and enthalpy data to modify the existing petroleum-based correlations and verify the designs of several pieces of process equipment in the SRC-I Demonstration Plant. The analytical characterization of coal

D. C. Mehta; I. C. Chu

1984-01-01

368

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

PubMed

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

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

2009-01-01

369

High Resolution Isobar Separator for Study of Exotic Decays  

NASA Astrophysics Data System (ADS)

A Multi-pass Time-Of-Flight mass spectrometer and separator (MTOF) was designed and built by the UNIRIB Consortium. The MTOF spectrometer consists of two coaxial electrostatic mirrors and auxiliary focusing, injection, and extraction elements. Ions of different mass are reflected multiple times between the mirrors and separated longitudinally. Using a test ion source, a mass resolving power of 29,000 (FWHM) has been achieved. The agreement between simulated and measured properties of the MTOF spectrometer is very good. MTOF will be converted into a mass separator by adding a fast electrostatic switch of the Bradbury-Nielson type. It will be initially coupled to the online isotope separator, UNISOR, at HRIBF to provide isobaric pure samples of exotic species in the ^100Sn region or neutron-rich nuclei for decay studies. Our ion optic calculations indicate a mass resolving power >= 15,000 and efficiencies of 30-50%. Ion optic design principles and hardware specifications from numerical simulations will be presented. The proposed RIB injection with beam cooling and bunching from the UNISOR separator into this new, compact isobar separator will be described.

Shchepunov, V.; Piechaczek, A.; Carter, H. K.; Zganjar, E. F.; Batchelder, J.; Liddick, S. N.; Wollnik, H.; Hu, Y.

2007-04-01

370

An objective isobaric/isentropic technique for upper air analysis  

NASA Technical Reports Server (NTRS)

An objective meteorological analysis technique is presented whereby both horizontal and vertical upper air analyses are performed. The process used to interpolate grid-point values from the upper-air station data is the same as for grid points on both an isobaric surface and a vertical cross-sectional plane. The nearby data surrounding each grid point are used in the interpolation by means of an anisotropic weighting scheme, which is described. The interpolation for a grid-point potential temperature is performed isobarically; whereas wind, mixing-ratio, and pressure height values are interpolated from data that lie on the isentropic surface that passes through the grid point. Two versions (A and B) of the technique are evaluated by qualitatively comparing computer analyses with subjective handdrawn analyses. The objective products of version A generally have fair correspondence with the subjective analyses and with the station data, and depicted the structure of the upper fronts, tropopauses, and jet streams fairly well. The version B objective products correspond more closely to the subjective analyses, and show the same strong gradients across the upper front with only minor smoothing.

Mancuso, R. L.; Endlich, R. M.; Ehernberger, L. J.

1981-01-01

371

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

372

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

373

Effect of precursor flux on compositional evolution in InP 1- x Sb x nanowires grown via self-catalyzed vapor-liquid-solid process  

NASA Astrophysics Data System (ADS)

We investigated the effect of high flow rates (> 10 -5 mol/min) of metalorganic precursors on compositional evolution in indium phosphide antimonide (InP 1- xSb x) nanowires grown via chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates maintained at ˜360 °C. The as-grown nanowire morphology, composition, and crystallinity are determined using scanning and transmission electron microscopies, selected-area electron diffraction, and x-ray energy dispersive spectroscopy. For all of the precursor flow rates, we obtain zinc blende structured InP 1- xSb x wires that are tapered with wider tops, narrower bases, and In-rich In-Sb alloy tips—characteristic of the vapor-liquid-solid process. The Sb content within the InP 1- xSb x wires is found to increase non-linearly with increasing Sb precursor flow rate. At the interfaces between the In-Sb alloy tips and the InP 1- xSb x nanowires, we observe single-crystalline wurtzite-structured InSb segments whose volumes depend on the Sb precursor flow rate. We attribute this phenomenon to the rapid crystallization of InSb during cooling of the Sb-rich In-Sb alloy droplets.

Ngo, Chilan; Zhou, Hailong; Mecklenburg, Matthew; Pozuelo, Marta; Regan, B. C.; Xiao, Q. F.; Shenoy, V. B.; Hicks, R. F.; Kodambaka, S.

2011-12-01

374

Effects of transport gradients in a chemical vapor deposition reactor employing vapor-liquid-solid growth of ternary chalcogenide phase-change materials.  

PubMed

Chemical vapor deposition (CVD) with vapor-liquid-solid (VLS) growth is employed to synthesize individual Ge(2)Sb(2)Te(5) nanowires with the ultimate goal of synthesizing a large scale nanowire array for universal memory storage. A consistent challenge encountered during the synthesis is a lack of control over the composition and morphology across the growth substrate. To better understand the challenges associated with the CVD synthesis of the ternary chalcogenide, computational fluid dynamics simulations are performed to quantify 3D thermal and momentum transients in the growth conditions. While these gradients are qualitatively known to exist, they have not been adequately quantified in both the axial and radial directions when under pressure and flow conditions indicative of VLS growth. These data are not easily acquired by conventional means for the axial direction under vacuum and are a considerable challenge to accurately measure radially. The simulation data shown here provide 3D insights into the gradients which ultimately dictate the region of controllable stoichiometry and morphology. These results help explain the observed inhomogeneity of the characterized ternary chalcogenide growth products at various growth substrate locations. PMID:20351405

Johnson, Derek C; Morris, Wesley D; Prieto, Amy L

2010-04-23

375

Representation of vapor-liquid and liquid-liquid equilibria for binary systems containing polymers: Applicability of an extended Flory-Huggins equation  

SciTech Connect

For some binary systems, an extended Flory-Huggins equation is applicable to both vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) using the same adjustable parameters. New LLE and VLE data are reported for polystyrene (PS) (MW = 100,000)/ cyclohexane and for poly(ethylene glycol) (PEG) (MW = 8,000)/water. Experimental results for the PS/cyclohexane system agree well with the semiempirical model, whereas those for PEG/water do not, probably because, for PEG/water, the temperature range of the VLE data is about 55 C lower than that of the LLE data. Excellent fits were obtained for their previously published experimental results for PS/cyclohexane (upper critical solution temperature, UCST), PS/ethyl acetate (lower critical solution temperature, LCST), PS/ tert-butyl acetate and PS/methyl acetate (both UCST and LCST), and PEG/water (closed- loop). The semiempirical model also fits well with new data obtained for the polymer blend PS /poly (vinyl methyl ether).

Bae, Y.C.; Shim, J.J.; Soane, D.S.; Prausnitz, J.M. (Univ. of California, Berkeley (United States))

1993-02-15

376

The generation of HCl in the system CaCl2-H2O: Vapor-liquid relations from 380-500??C  

USGS Publications Warehouse

We determined vapor-liquid relations (P-T-x) and derived critical parameters for the system CaCl2-H2O from 380-500??C. Results show that the two-phase region of this system is extremely large and occupies a significant portion of the P-T space to which circulation of fluids in the Earth's crust is constrained. Results also show the system generates significant amounts of HCl (as much as 0.1 mol/kg) in the vapor phase buffered by the liquid at surprisingly high pressures (???230 bars at 380??C, <580 bars at 500??C), presumably by hydrolysis of CaCl2: CaCl2 + 2H2O = Ca(OH)2 + 2HCl. We interpret the abundance of HCl in the vapor as due to its preference for the vapor phase, and by the preference of Ca(OH)2 for either the liquid phase or solid. The recent recognition of the abundance of CaCl2 in deep brines of the Earth's crust and their hydrothermal mobilization makes the hydrolysis of CaCl2 geologically important. The boiling of Ca-rich brines produces abundant HCl buffered by the presence of the liquid at moderate pressures. The resultant Ca(OH)2 generated by this process reacts with silicates to form a variety of alteration products, such as epidote, whereas the vapor produces acid-alteration of rocks through which it ascends.

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

1996-01-01

377

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

Microsoft Academic Search

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

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

2003-01-01

378

Vapor-liquid equilibria for difluoromethane + dichloromethane at 303.2 and 313.2 K and 1,1-difluoroethane + vinyl chloride at 303.2 and 323.2 K  

SciTech Connect

Isothermal vapor-liquid equilibria for difluoromethane (HFC-32) + dichloromethane at 303.2 K and 313.2 K and 1,1-difluoroethane (HFC-152a) + vinyl chloride at 303.2 K and 323.2 K were measured in a circulation-type apparatus. The experimental data were correlated with the Peng-Robinson equation of state using the Wong and Sandler mixing rule, and the relevant parameters are presented.

Lim, J.S.; Lee, Y.W.; Lee, Y.Y. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology

1997-05-01

379

Vapor-liquid equilibria for 1,1-difluoroethane + acetylene and 1,1-difluoroethane + 1,1-dichloroethane at 303.2 K and 323.2 K  

SciTech Connect

Isothermal vapor-liquid equilibria for 1,1-difluoroethane (HFC-152a) + acetylene and 1,1-difluoroethane + 1,1-dichloroethane (HCC-150a) were measured in a circulation type apparatus at 303.2 K and 323.2 K. The experimental data were correlated with the Peng-Robinson equation of state using the Wong and Sandler mixing rule, and the relevant parameters are presented.

Lim, J.S.; Lee, Y.W.; Kim, J.D.; Lee, Y.Y. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Environmental and CFC Technology; Lee, J. [LG Chemical LTD/Research Park, Taejon (Korea, Republic of)] [LG Chemical LTD/Research Park, Taejon (Korea, Republic of)

1996-09-01

380

Nucleon-nucleon scattering with isobar degrees of freedom  

NASA Astrophysics Data System (ADS)

A nonrelativistic nucleon-nucleon interaction potential model containing explicit coupling to N?(1232 MeV) and /or NN*(1440 MeV) channels is developed and used to describe empirical elastic scattering phase shifts from 0-1000 MeV. The theoretical Feshbach-Lomon meson exchange potential provides the starting point for describing the interaction between the two nucleons. NN? and NNNN¯ intermediate states are implicitly included through the two-pion exchange portion of the Feshbach-Lomon interaction. Short range phenomenological NN-NN potentials are used along with empirical short range and one pion exchange coupling potentials between the nucleon-nucleon and nucleon-isobar channels. Quantitative fits to the Arndt phase shifts and inelasticity parameters from 0-1000 MeV for J<=6 are obtained. The resulting potentials are obtained in a local, coordinate space representation, convenient for use in many-body calculations at intermediate energies.

Ray, L.

1987-03-01

381

Complex energy approaches for calculating isobaric analogue states  

NASA Astrophysics Data System (ADS)

Parameters of isobaric analog resonance (IAR) are calculated in the framework of the Lane model using different methods. In the standard method, the direct numerical solution of the coupled channel (CC) Lane equations served as a reference for checking two complex energy methods, namely the complex energy shell model (CXSM) and the complex scaling (CS) approaches. The IAR parameters calculated by the CXSM and the CS methods agree with that of the CC results within 1 keV for all partial waves considered. Although the CXSM and the CS methods have similarities, an important difference is that only the CXSM method offers a direct way for studying the configurations of the IAR wave function.

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

2008-10-01

382

Complex energy approaches for calculating isobaric analogue states  

SciTech Connect

Parameters of isobaric analog resonance (IAR) are calculated in the framework of the Lane model using different methods. In the standard method, the direct numerical solution of the coupled channel (CC) Lane equations served as a reference for checking two complex energy methods, namely the complex energy shell model (CXSM) and the complex scaling (CS) approaches. The IAR parameters calculated by the CXSM and the CS methods agree with that of the CC results within 1 keV for all partial waves considered. Although the CXSM and the CS methods have similarities, an important difference is that only the CXSM method offers a direct way for studying the configurations of the IAR wave function.

Betan, R. Id; Kruppa, A. T.; Vertse, T. [Departamento de Quimica y Fisica, FCEIA(UNR)-Instituto de Fisica Rosario (CONICET), Avenida Pellegrini 250, 2000 Rosario (Argentina); Institute of Nuclear Research of the Hungarian Academy of Sciences, Post Office Box 51, H-4001 Debrecen (Hungary); Institute of Nuclear Research of the Hungarian Academy of Sciences, Post Office Box 51, H-4001 Debrecen, Hungary and University of Debrecen, Faculty of Informatics, Post Office Box 12, H-4010 Debrecen (Hungary)

2008-10-15

383

The isobaric multiplet mass equation for A?71 revisited  

NASA Astrophysics Data System (ADS)

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; Blank, Bertram; Smirnova, Nadezda A.; Bueb, Jean Bernard; Antony, Maria Susai

2013-11-01

384

The isobaric multiplet mass equation for A?71 revisited  

SciTech Connect

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

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

2013-11-15

385

Hard breakup of the deuteron into two {Delta} isobars  

SciTech Connect

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

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

2011-05-15

386

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

NASA Technical Reports Server (NTRS)

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

Yuan, S. W. K.

1985-01-01

387

Equilibrium solubilities of CO/sub 2/ and H/sub 2/S in diethanolamine (DEA) and methyldiethanolamine (MDEA) solutions  

SciTech Connect

The ability to predict equilibrium phase behavior in systems containing CO/sub 2/ and/or H/sub 2/S in alkanolamine solutions such as diethanolamine (DEA) and methyldiethanolamine (MDEA) is of vital importance for proper design and operation of acid gases treating systems. Literature data for the solubilities of CO/sub 2/ and/or H/sub 2/S in DEA and MDEA systems have been compiled and evaluated. Experimental measurements have also been made to confirm literature data and to expand the data base. A vapor-liquid equilibrium (VLE) model similar to the one developed by Kent and Eisenberg has been developed to correlate the data. The model gives the most accurate predictions when compared to other VLE models available for predicting equilibrium acid gas partial pressures over DEA and MDEA solutions.

Ho, A.S.; Equren, P.R. (Amoco Production Co., Tulsa, OK (US))

1988-01-01

388

Nuclear Structure Information from 208Pb(p, p') via Isobaric Analog Resonances in 209Bi  

NASA Astrophysics Data System (ADS)

We studied the inelastic proton scattering on the doubly magic nucleus 208Pb via isobaric analog resonances (IAR) in 209Bi. In the proton decay of the intruder resonance j15/2 several states with positive parity are identified...

Heusler, A.; von Brentano, P.; Faestermann, T.; Graw, G.; Hertenberger, R.; Jolie, J.; Krücken, R.; Maier, K. H.; Mücher, D.; Pietralla, N.; Riess, F.; Werner, V.; Wirth, H.-F.

2008-04-01

389

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

SciTech Connect

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

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

2011-01-01

390

Three-nucleon hadronic and electromagnetic reactions with {delta}-isobar excitation  

SciTech Connect

Three-nucleon hadronic and electromagnetic reactions are described. The description uses the purely nucleonic charge-dependent CD-Bonn potential and its coupled-channel extension CD-Bonn + {delta}. Exact solutions of three-particle equations are employed for the initial and final states of the reactions. The {delta}-isobar excitation yields an effective three-nucleon force and effective two- and three-nucleon currents beside other {delta}-isobar effects; they are mutually consistent.

Deltuva, A. [University of Hannover, (Germany); University of Lisboa (Portugal); Adam, J. Jr. [Academy of Sciences of Czech Republic (Czech Republic); Fonseca, A.C. [University of Lisboa (Portugal); Sauer, P.U. [University of Hannover (Germany)

2005-05-06

391

Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration  

SciTech Connect

Chemical vapor infiltration (CVI) is a method of ceramic or carbon matrix composite fabrication in which chemical vapor deposition reactions are employed to deposit the matrix material (ceramic or carbon) on the internal surface of a porous preform. This study addresses the possibility of identifying optimal pressure and temperature pairs that can be used to give the least processing time during isobaric isothermal CVI within a window of operating conditions. Optimal pressure-temperature pairs are determined as the solution of an optimization problem that seeks to minimize the processing time predicted by a CVI model under the constraint that the maximum density difference in the preform at the end of the densification does not exceed a preset limit. Results are presented on the dependence of the optimum processing time on the type of structure of the preform, the specifications that the final product has to conform to, and the kinetics of the chemical reaction. The results show that operation at low pressure affects adversely the processing time and that a dramatic reduction in the processing time can be achieved by operating in the vicinity of the optimal pressure.

Ofori, J.Y.; Sotirchos, S.V. [Univ. of Rochester, NY (United States). Dept. of Chemical Engineering] [Univ. of Rochester, NY (United States). Dept. of Chemical Engineering

1996-10-01

392

J/??pp¯? decay in the isobar resonance model  

NASA Astrophysics Data System (ADS)

Based on the effective Lagrangian approach, the J/??pp¯? decay is studied in an isobar resonance model with the assumption that the ?-meson is produced from intermediate nucleon resonances. The contributions from the N1/2-*(1535), N3/2+*(1900), N1/2-*(2090) and N1/2+*(2100) states are considered. In terms of the coupling constants g?NN*2 and g?NN*2 extracted from the reaction cross section of the ?-p?n? process, and the partial decay widths of the J/??pp¯? and J/??pn¯?- processes, respectively, the invariant mass spectrum and the Dalitz plot for J/??pp¯? decay are predicted. It is shown that there are two types of results. In the type I case, a large peak structure around 2.09 GeV implies that a considerable amount of N? or qqqss¯ component may exist in the narrow-width N1/2-*(2090) state, but a tiny qqqss¯ component in the broad-width N1/2+*(2100) state. In the type II case, a small peak around 2.11 GeV may only indicate the existence of a certain amount of p? or qqqss¯ component in the narrow-width N1/2+*(2100) state, but no information for the broad-width N1/2-*(2090) state. Further BESIII data with high statistics would help us to distinguish the strange structures of these N*s.

Dai, Jian-Ping; Shen, Peng-Nian; Xie, Ju-Jun; Zou, Bing-Song

2012-01-01

393

Glycan analysis by isobaric aldehyde reactive tags and mass spectrometry.  

PubMed

Glycans play significant roles in physiological and pathological processes. Therefore, quantitative analysis of glycans from normal and disease specimens can provide insight into disease onset and progression. Relative glycan quantification usually requires modification of the glycans with either chromogenic or fluorogenic tags for optical measurement or isotopic tags for mass spectrometric analysis. Because of rapid advances in mass spectrometry (MS) instruments in resolution, sensitivity, and speed, MS-based methods have become increasingly popular for glycan analysis in the past decade. However, current isotopic tags for glycan labeling are mostly mass-shift tags generating mass differences in precursor ions for quantification, which can complicate mass spectra. In this study, we report the synthesis and characterization of isobaric aldehyde reactive tags (iARTs) for glycan quantification using tandem MS. We applied iARTs to the relative identification and quantification of glycans of gp120, a glycoprotein from human immunodeficiency virus. The results show that iARTs provide strong signals for glycan identification. Although we only show the synthesis and characterization of two iARTs reagents, iARTs can be readily expanded to six-plex tags for quantitative analysis of six samples concurrently. PMID:23895018

Yang, Shuang; Yuan, Wei; Yang, Weiming; Zhou, Jianying; Harlan, Robert; Edwards, James; Li, Shuwei; Zhang, Hui

2013-09-01

394

Glycan Analysis by Isobaric Aldehyde Reactive Tags and Mass Spectrometry  

PubMed Central

Glycans play significant roles in physiological and pathological processes. Therefore, quantitative analysis of glycans from normal and disease specimens can provide insight into disease onset and progression. Relative glycan quantification usually requires modification of the glycans with either chromogenic or fluorogenic tags for optical measurement or isotopic tags for mass spectrometric analysis. Due to rapid advances in mass spectrometry (MS) instruments in resolution, sensitivity and speed, MS-based methods have become increasingly popular for glycan analysis in the past decade. However, current isotopic tags for glycan labeling are mostly mass-shift tags generating mass differences in precursor ions for quantification, which can complicate mass spectra. In this study, we report the synthesis and characterization of isobaric aldehyde reactive tags (iARTs) for glycan quantification using tandem MS. We applied iARTs to the relative identification and quantification of glycans of gp120, a glycoprotein from human immunodeficiency virus. The results show that iARTs provide strong signals for glycan identification. Although we only show the synthesis and characterization of two iARTs reagents, iARTs can be readily expanded to six-plex tags for quantitative analysis of six samples concurrently.

Yang, Shuang; Yuan, Wei; Yang, Weiming; Zhou, Jianying; Harlan, Robert; Edwards, James; Li, Shuwei; Zhang, Hui

2013-01-01

395

Measurement of vapor–liquid equilibria (VLE) and excess enthalpies ( H E) of binary systems with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and prediction of these properties and ? ? using modified UNIFAC (Dortmund)  

Microsoft Academic Search

Vapor–liquid equilibria (VLE) and excess enthalpies (HE) were measured for a variety of alkanes, alkenes, aromatics, alcohols, ketones and water in several ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM]+[BTI]?, 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM]+[BTI]?, 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [HMIM]+[BTI]? and 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [OMIM]+[BTI]?, covering the temperature range from 323.15 to 413.15K. The new data were used together with the already available experimental data for imidazolium compounds

Silke Nebig; Rainer Bölts; Jürgen Gmehling

2007-01-01

396

Vapor-liquid equilibria for hydrogen fluoride + difluoromethane, + 1,1,1,2-tetrafluoroethane, and + 1-chloro-1,2,2,2-tetrafluoromethane at 283.3 and 298.2 K  

SciTech Connect

The production of refrigerants involves the separation of multicomponent mixtures containing hydrogen fluoride, hydrogen chloride, and various chlorinated and fluorinated hydrocarbons. Therefore, it is essential to known the phase behavior of these mixtures. Isothermal vapor-liquid equilibria for hydrogen fluoride (HF) + difluoromethane (HFC-32), HF + 1,1,1,2-tetrafluoroethane (HFC-134a), and HF + 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) were measured by the P-T-x method at 283.3 and 298.2 K. Vapor compositions were calculated from these results. Among these systems, the HF + HFC-134a and HF + HCFC-124 systems exhibit minimum boiling azeotropes at both temperatures.

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. [KIST, Seoul (Korea, Republic of). CFC Alternatives Technology Center] [KIST, Seoul (Korea, Republic of). CFC Alternatives Technology Center

1996-01-01

397

Vapor-liquid equilibria for 1,1,1,2-tetrafluoroethane + 1-chloro-1,2,2,2-tetrafluoroethane and 1-chloro-1,2,2,2-tetrafluoroethane + 1-chloro-1,1-difluoroethane systems  

SciTech Connect

Isothermal vapor-liquid equilibria were determined for two binary mixtures of refrigerants with a circulation type apparatus. The 1,1,1,2-tetrafluoroethane (HFC-134a) + 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) system was studied at 296.45, 302.25, and 307.25 K. The 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) + 1-chloro-1,1-difluoroethane (HCFC-142b) system was studied at 298.15 and 312.15 K. At each temperature, the pressure and vapor and liquid compositions were measured. Results were correlated with the Peng-Robinson equation of state.

Lee, J.; Lee, J.; Kim, H. [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering] [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering

1996-07-01

398

Phase equilibrium data for development of correlations for coal fluids: Report for the period August 15, 1987 to December 31, 1987  

SciTech Connect

During the present report period, data have been obtained on the solubilities of carbon dioxide in benzene at 310.2 K, and of ethane in n-hexatriacontane at 373.2 K and in n-tetratetracontane at 373.2 K and 423.2 K. These data are well described by the Soave and Peng-Robinson equations of state. Also, during this report period a low pressure recirculating vapor-liquid equilibrium still has been designed and constructed. Preliminary tests on selected systems confirm excellent operation of the new apparatus. 17 refs., 7 figs., 10 tabs.

Robinson, R.L. Jr.; Gasem, K.A.M.; Raff, A.M.; Qin, Yanlong

1988-01-19

399

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

PubMed

Linear free energy relationships (LFERs) were established which relate equilibrium vapor-liquid isotope effects to stable carbon and hydrogen isotope enrichment factors for equilibrium sorption to geosorbents. The LFERs were established for normal, cyclic or branched alkanes, monoaromatic hydrocarbons, and chloroethenes. These LFERs predict that isotopic light compounds sorb more strongly than their heavy counterparts. Defining fractionation as in classical literature by "heavy divided by light", carbon enrichment factors for equilibrium sorption were derived which ranged from -0.13±0.04‰ (benzene) to -0.52±0.19‰ (trichloroethene at 5-15 °C). Hydrogen enrichment factors for sorption of 14 different compounds were between -2.4 and -9.2‰. For perdeuterated hydrocarbons the predicted enrichment factors ranged from -19±5.4‰ (benzene) to -64±30‰ (cyclohexane). Equilibrium sorption experiments with a soil and activated carbon as sorbents were performed in the laboratory for perdeuterocyclohexane and perdeuterotoluene. The measured D/H enrichments agreed with the LFER prediction for both compounds and both sorbents within the uncertainty estimate of the prediction. The results of this work suggest that equilibrium sorption does create only very small isotope shifts for (13)C in groundwater pollutants in aquifers. It is also suggested that deuterium shifts are expected to be higher, especially for strongly sorbing pollutants. PMID:22055158

Höhener, Patrick; Yu, Xianjing

2012-03-15

400

The effects of hyperbaric or isobaric bupivacaine on bispectral index in spinal anesthesia for cesarean section  

PubMed Central

Background: Hyperbaric and isobaric bupivacaine has been shown to reduce bispectral index (BIS) during spinal anesthesia. The aim of this study was to compare the effect of isobaric bupivacaine and hyperbaric bupivacaine on the BIS during cesarean section with spinal anesthesia. Materials and Methods: In this double-blind randomized controlled clinical trial, 84 pregnant women with ASA (American Society of Anesthesiologists) class I or II were randomly assigned to receive isobaric or hyperbaric bupivacaine. BIS was measured using electro encephalography (EEG) and recorded at the baseline and 5th, 10th, 15th, 30th, 45th, 60th, 90th and 120th minutes after spinal injection. The heart rate (HR), mean arterial pressure (MAP), signal quality index (SQI), electromyography (EMG) and the temperature were also recorded during surgery. Results: From recruited subjects, 41 completed the study in each group and their data were analyzed. The BIS score began to reduce until 30th minute for isobaric bupivacaine and 45th minute for hyperbaric bupivacaine after spinal injection. The recorded BIS was not significantly different between two groups at all the time points. Difference of BIS from baseline was not significant between two groups at most time points except for the 45th minute after injection that it was 5.9 ± 9 vs. 2.7 ± 4.6 for hyperbaric and isobaric bupivacaine, respectively (p = 0.047). The changing trend was not significantly different between groups with hyperbaric and isobaric bupivacaine. Conclusion: According to the present study, the BIS score during surgery began to decrease when the patients were injected spinally by both of these drugs. The greatest decrease from baseline BIS values occurred at 30 and 45 minutes after induction of spinal anesthesia. However, hyperbaric or isobaric bupivacaine did not have different effects on the BIS during spinal anesthesia.

Jabalameli, Mitra; Hazegh, Nina; Gholami, Saeed

2012-01-01

401

Liquid-vapor equilibrium in the systems hexane-benzene-petroleum sulfoxides and hexane-benzene-petroleum sulfones  

SciTech Connect

Vapor-liquid equilibrium in the hexane-benzene system in presence of petroleum sulfoxides and petroleum sulfones, which are new selective solvents for aromatic and unsaturated hydrocarbons was studied. Liquid-vapor equilibrium were studied in the Bushmakin apparatus under atmospheric pressure. Gas-liquid chromatography with the aid of a UKh-2 chromatograph with a katharometer detector was used for monitoring the purity of hexane and benzene and for analyzing the phases. The stationary liquid phase was 15% Carbowax 20M on Chezasorb (50-70 mesh). A stainless-steel spiral chromatographic column 4 m long and 4 mm inside diameter was used, the temperature was 95/sup 0/C, and nitrogen was used as the carrier gas. Reagents of cp grade were used in the experiments.

Vakhitova, N.G.; Kolosnitsyn, V.S.; Baikova, A.Ya.; Nikitin, Yu.E.; Murinov, Yu.I.

1982-03-10

402

Linear dependency of full scattering profile isobaric point on tissue diameter.  

PubMed

Most methods for measuring light-tissue interaction focus on volume reflectance, while very few measure light transmission. In a previous work, we suggested investigating the influence of blood vessel diameter on photons exiting the tissue at all exit angles to receive the full scattering profile. By this method, we have shown that there is a central angle, i.e., the isobaric point, independent of blood vessel diameter. The vessel diameter changes the effective reduced scattering coefficient. However, both the scattering profile and the value of the isobaric point strongly depend on optical properties and the exact geometry of the tissue. In this study, we investigate the dependency of the isobaric point on tissue diameter and scattering coefficient in both two-dimensional and three-dimensional simulations. We show that the value of this point linearly depends on tissue diameter. The findings of this work solve the dilemma of whether to measure transmission or reflection since the isobaric point reduces by half the total amount of exiting photons. Furthermore, the full scattering profile is sensitive to changes in the scattering properties, but a single isobaric point to these changes is expected. If this point is not found, it is a diagnostic indication of an unexpected change in the tissue. PMID:24522807

Duadi, Hamootal; Feder, Idit; Fixler, Dror

2014-02-01

403

Non-equilibrium configurational Prigogine-Defay ratio  

NASA Astrophysics Data System (ADS)

Classically, the Prigogine-Defay (PD) ratio involves differences in isobaric heat capacity, isothermal compressibility, and isobaric thermal expansion coefficient between a super-cooled liquid and the corresponding glass at the glass transition. However, determining such differences by extrapolation of coefficients that have been measured for super-cooled liquid and glassy state, respectively, poses the problem that it does not exactly take into account the non-equilibrium character of the glass transition. In this paper, we assess this question by taking into account the time dependence of configurational contributions to the three thermodynamic coefficients in the glass transition range upon varying temperature and/or pressure. Macroscopic non-equilibrium thermodynamics is applied to obtain a generalised form of the PD ratio. The classical PD ratio can then be taken as a particular case of this generalisation. Under some assumptions, the configurational PD ratio (CPD ratio) can be expressed in terms of fictive temperature and fictive pressure which, hence, provides another possibility to experimentally verify this formalism.

Garden, Jean-Luc; Guillou, Hervé; Richard, Jacques; Wondraczek, Lothar

2012-06-01

404

Non-Equilibrium Stability Theory.  

National Technical Information Service (NTIS)

Contents: Introduction; Local equilibrium; Classical stability theory of thermodynamic equilibrium; Equilibrium stability theory and entropy balance equation; Explicit form of the equilibrium stability conditions; Stability of non-equilibrium states; The ...

P. Glansdorff I. Prigogine

1969-01-01

405

Prediction of vapor–liquid equilibrium in polymer solutions using a Peng–Robinson group contribution model 1 Paper presented at the International Conference on Applied Physical Chemistry, Warsaw, 13–15 November 1996. 1  

Microsoft Academic Search

The objective of this study is to extend the applicability of a Peng–Robinson group contribution method (PRASOG), which combines a zero pressure gE mixing rule for Peng–Robinson EOS with ASOG group contribution model, to polymer solutions. The solvent activities in polymer solutions have been predicted by PRASOG-FV which evaluates the gE from ASOG-FV proposed previously in order to predict the

K Tochigi; H Futakuchi; K Kojima

1998-01-01

406

Vapor-liquid equilibrium constants at infinite dilution determined by a gas stripping method: ethane, propane, n-butane, n-pentane in the methane-n-decane system  

SciTech Connect

A new apparatus to measure partition coefficients Kinfinity /SUB s/ at infinite dilution up to 200 10/sup 5/ 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 344.25 K up to 101 10/sup 5/ Pa.

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

1983-01-01

407

PVT Measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K  

NASA Astrophysics Data System (ADS)

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archimedes' principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2×10-4 and 7×10-4, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5 MPa, an isochoric apparatus was used. The relative measurement uncertainty of pv/(RT) is less than 1×10-3. In addition to the investigation of the ( p, v, T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements are compared with a fundamental equation for R134a, which is based on the measurements of other research groups.

Blanke, W.; Klingenberg, G.; Weiss, R.

1995-09-01

408

PVT measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K  

SciTech Connect

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archmiedes` principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2 X 10 {sup -4} and 7 X 10{sup -4}, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5MPa, an isochoric apparatus was used. The relative measurement uncertainty of pv/(RT) is less than 1X10{sup -3}. In addition to the investigation of the (p,v,T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements of other research groups.

Blanke, W.; Klingenberg, G.; Weiss, R. [Physikalisch-Technische Bundesantalt, Braunschweig (Germany)

1995-09-01

409

An experimental apparatus proposed for efficient removal of isobaric contaminants in negative ion beams  

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

410

The role of iterative isobar processes in nuclear matter and the effective nucleon-nucleon interaction  

NASA Astrophysics Data System (ADS)

A calculation is performed using lowest order Brueckner theory in momentum space, with explicit isobar configurations included through the coupled channel mathod. The effective interaction for the1 S 0-5 D 0 channel is extracted from this calculation. Two different transition potentials are used — one due to Green and Niskanen (1976), the other, due to Green and co-workers (1978). The nucleon-nucleon (NN) interaction used is the Reid soft core potential, compensated for the inclusion of the explicit isobar channel. The effective interaction shows marked momentum dependence in the intermediate range. The loss of attraction depends on the transition potential one chooses. The correlation function involving the nucleon-isobar intermediate state is anti-correlated to the NN part.

Dey, J.; Samanta, B. C.; Dey, M.

1980-09-01

411

Coal gasification pilot plant support studies. Subtask 3-2. Phase equilibrium studies as applied to treatment of raw bases from coal gasification. [122 to 403/sup 0/F and 590 to 2800 psia  

SciTech Connect

Several methods to predict the phase equilibrium behavior of gas mixtures at different temperatures and pressures appear in the literature. In this study, four of these correlations have been evaluated using experimentally derived vapor-liquid equilibrium compositions and phase densities. The experiments were conducted with simulated coal gasification product gas-benzene mixtures over a temperature range of 122/sup 0/ to 403/sup 0/F and pressure range of 590 to 2800 psia. The four correlations evaluated were the Peng-Robinson, the Soave Redlich-Kwong, the Redlich-Kwong Chao-Seader, and the Redlich-Kwong Grayson-Streed. Interaction coefficients for several of the components of interest for use in the Peng-Robinson equation of state were also determined from available binary vapor-liquid equilibrium data. Of the four available vapor-equilibrium correlations evaluated, the Peng-Robinson correlation provided the closest approximation to the experimental results. The next closest correlations were the Soave Redlich-Kwong, the Redlich-Kwong Chao-Seader, and the Redlich-Kwong Grayson-Streed.

Not Available

1980-10-01

412

The Chemical Equilibrium Problem.  

National Technical Information Service (NTIS)

It has long been known that the problem of determining the equilibrium composition of a solution of chemically reacting species could be formulated as a constrained minimum problem. Previous methods for solving the chemical equilibrium problem in this for...

J. H. Bigelow

1968-01-01

413

High Resolution Study of the g9\\/2 Isobaric Analogue State in 61Cu  

Microsoft Academic Search

The g9\\/2 isobaric analogue state (IAS) in 61Cu has been investigated by the 60Ni(p, p)60Ni and (p, gamma)61Cu reaction using high energy-resolution (overall \\\\varDelta E~=350 eV) proton beams. Resonances at Ep(lab.)=3723, 3732, 3737 and 3743 keV are identified as fragments of the IAS of the g9\\/2 state in 61Ni. Proton widths and radiative widths of these isobaric analogue resonances (IAR's)

Minoru Adachi; Toshiyuki Hattori; Eiichi Arai; Masao Ogawa; Haruo Satoh

1974-01-01

414

Communication: Resolving the vibrational and configurational contributions to thermal expansion in isobaric glass-forming systems  

NASA Astrophysics Data System (ADS)

A fundamental understanding of isobaric thermal expansion behavior is critical in all areas of glass science and technology. Current models of glass transition and relaxation behavior implicitly assume that the thermal expansion coefficient of glass-forming systems can be expressed as a sum of vibrational and configurational contributions. However, this assumption is made without rigorous theoretical or experimental justification. Here we present a detailed statistical mechanical analysis resolving the vibrational and configurational contributions to isobaric thermal expansion and show experimental proof of the separability of thermal expansion into vibrational and configurational components for Corning Jade® glass.

Potuzak, Marcel; Mauro, John C.; Kiczenski, T. J.; Ellison, Adam J.; Allan, Douglas C.

2010-09-01

415

Isobaric analog states in the f7/2 and g9/2 shells  

NASA Astrophysics Data System (ADS)

Calculations are performed for energies of isobaric analog states with isospins T=2 and T=3 in regions where they have been found experimentally, e.g., the pf shell, and regions where they have not yet been found, e.g., g9/2 near Z=50, N=50. We consider two approaches: one using binding energy formulas and Coulomb energies contained therein, and the other using shell-model calculations. It is noted that some (but not all) calculations yield very low excitation energies for the J=0+, T=2 isobaric analog state in 96Ag.

Zamick, L.; Escuderos, A.; Robinson, S. J. Q.; Sharon, Y. Y.; Kirson, M. W.

2013-06-01

416

Chapman Cycle Equilibrium Calculator  

NSDL National Science Digital Library

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

The Shodor Education Foundation, Inc.

417

Vapor-liquid equilibria for the systems composed of 1-chloro-1,1-difluoroethane, 1,1-dichloro-1-fluoroethane, and 1,1,1-trichloroethane at 50.1 C  

SciTech Connect

Isothermal vapor-liquid equilibria for the three binary systems 1-chloro-1,1-difluoroethane + 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane + 1,1,1-trichloroethane, and 1,1-dichloro-1-fluoroethane + 1,1,1-trichloroethane and the ternary system 1-chloro-1,1-difluoromethane + 1,1-dichloro-1-fluoroethane + 1,1,1-trichloroethane have been measured at 50.1 C. The experimental data for the binary systems are correlated with the Peng-Robinson equation of state, and the relevant parameters are presented. The predicted results for the ternary system were found to be in good agreement with the experimental data.

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

1996-03-01

418

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

PubMed

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

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

2012-09-18

419

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

Microsoft Academic Search

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.

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

2010-01-01

420

Comparative study of intrathecal hyperbaric versus isobaric ropivacaine: A randomized control trial  

PubMed Central

Background: Hyperbaric ropivacaine produce more reliable sensory and motor block, with faster onset, better quality of muscles relaxation than isobaric ropivacaine. So, this study was designed to compare the efficacy of hyperbaric ropivacaine with isobaric ropivacaine in patients undergoing lower abdominal surgery. Methods: A randomized controlled double blind study in two groups of patients. group A (n=35) received 3 ml of isobaric ropivacaine 6 mg/ml (18 mg). Group B (n=35) received 3 ml of hyperbaric ropivacaine 6 mg/ml (18 mg). The onset and duration of sensory block at dermatome level T10, maximum upper and lower spread of sensory block, intensity, and duration of motor block were recorded. Statistical Analysis: Block characteristics were compared using the two-tailed Mann – Whitney U-test. The proportion of side effects was compared using the Chi-square test. Results: The median time of onset of sensory block at the T10 dermatome was 4.4±1.3 min in group B and 6.0±1.03 min in group A. The median time to maximum block height was 16.7±3.7 min in group A and 12.03±1.96 min in group B. The median duration of complete motor recovery (B0) was significantly shorter in the heavy ropivacaine group (166.5±11.7 min) compared with the isobaric ropivacaine group (192.9±9.6 min). Conclusions: Intrathecal hyperbaric ropivacaine provides more rapid, adequate, and good quality of sensory and motor block with rapid post-operative recovery as compare to isobaric ropivacaine.

Gupta, Rajni; Bogra, Jaishri; Singh, Prithvi Kumar; Saxena, Sulekha; Chandra, Girish; Kushwaha, Jitendra Kumar

2013-01-01

421

Misconceptions of chemical equilibrium  

Microsoft Academic Search

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

Mark W. Hackling; Patrick J. Garnett

1985-01-01

422

Equilibrium Product Bundling  

Microsoft Academic Search

This article offers an equilibrium theory of product bundling by rival firms. In several models where a primary good is produced in a duopoly market and one or more other goods is produced under perfectly competitive conditions, bundling is shown to emerge as an equilibrium strategy of one or both of the duopolists for its role as a product-differentiation device.

Yongmin Chen

1997-01-01

423

Transverse electron scattering response function of He3 with ?-isobar degrees of freedom  

NASA Astrophysics Data System (ADS)

A calculation of the He3 transverse (e,e') inclusive response function, RT, which includes ? degrees of freedom, is performed using the Lorentz integral transform method. The resulting coupled equations are treated in impulse approximation, where the NNN and NN? channels are solved separately. As NN and NNN potentials, we use the Argonne V18 and Urbana IX models, respectively. Electromagnetic currents include the ?-isobar currents, one-body N currents with relativistic corrections, and two-body currents consistent with the Argonne V18 potential. RT is calculated for the breakup threshold region at momentum transfers near 900 MeV/c. Our results are similar to those of Deltuva in that large ?-isobar current contributions are found. However, we find that these are largely canceled by the relativistic contribution from the one-body N currents. Finally, a comparison is made between theoretical results and experimental data.

Yuan, Luping; Efros, Victor D.; Leidemann, Winfried; Tomusiak, Edward L.

2010-11-01

424

Isobar model analysis of {pi}{sup 0{eta}} photoproduction on protons  

SciTech Connect

Photoproduction of {pi}{sup 0{eta}} on protons in the energy range from threshold to 1.4 GeV is discussed. The data for representative angular distributions recently obtained at MAMI C are analyzed using an isobar model. The isobars considered are {Delta}(1232) and S{sub 11}(1535) for {pi}{sup 0}p and {eta}p states, respectively. In accordance with the results of earlier works, the main features of the reaction are explained through the dominance of the D{sub 33} wave with a relatively small admixture of positive parity resonances. Comparison with recent experimental results for the photon beam asymmetry is carried out.

Fix, A.; Lee, A. [Tomsk Polytechnic University, Lenina 30, 634050 Tomsk (Russian Federation); Kashevarov, V. L. [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz, J.J. Becher Weg 45, 55099 Mainz (Germany); Lebedev Physical Institute, Leninskiy prospekt 53, 119991 Moscow (Russian Federation); Ostrick, M. [Lebedev Physical Institute, Leninskiy prospekt 53, 119991 Moscow (Russian Federation)

2010-09-15

425

Conductivity of multiple shock compressed hydrogen along 135 and 180 GPa isobars  

NASA Astrophysics Data System (ADS)

The results of temperature and conductivity measurements of hydrogen, multiple shock compressed to the pressures 135 and 180 GPa are presented. Explosively driven steel plate with velocity up to 8 km/s was used for shock wave generation. Hydrogen with different initial pressures and temperatures was multiple shock compressed between steel bottom and sapphire window. Brightness temperature of hydrogen was measured by fast optical pyrometer. Electrical resistance of shocked hydrogen was measured simultaneously with optical pyrometer records. The conductivity of hydrogen decreased from 424 1/Om/cm at 2700 K down to 20 1/Om/cm at 6000 K along 135 GPa isobar. The conductivity of hydrogen decreased from 800 1/Om/cm at 5000 K down to 100 1/Om/cm at 6700 K along 180 GPa isobar. Experimental results are compared with different theoretical predictions.

Ternovoi, Vladimir; Pyalling, Alexei; Nikolaev, Dmitry; Kvitov, Sergey

2009-06-01

426

Conductivity of Multiple Shock Compressed Hydrogen Along 135 and 180 Gpa Isobars  

NASA Astrophysics Data System (ADS)

The results of temperature and conductivity measurements of hydrogen, multiple shock compressed to the pressures 135 and 180 GPa are presented. Explosively driven steel plate with velocity up to 8 km/s was used for shock wave generation. Hydrogen with various initial pressures and temperatures was multiple shock compressed between steel bottom and sapphire window. Brightness temperature of hydrogen was measured by fast optical pyrometer. Electrical resistance of shocked hydrogen was measured simultaneously with optical pyrometer records. The conductivity of hydrogen decreased from 424 1/Om/cm at 2700 K down to 20 1/Om/cm at 6000 K along 135 GPa isobar. The conductivity of hydrogen decreased from 800 1/Om/cm at 5000 K down to 100 1/Om/cm at 6700 K along 180 GPa isobar. Experimental results are compared with various theoretical predictions.

Ya. Ternovoi, V.; Pyalling, A. A.; Nikolaev, D. N.; Kvitov, S. V.

2009-12-01

427

'Coulomb' description of basic relaxation parameters of isobar analog and charge-exchange giant monopole resonances  

SciTech Connect

Within a semimicroscopic approach, basic relaxation parameters of the isobaric analog resonance and of the charge-exchange giant monopole resonance, which is an overtone of the isobaric analog resonance, are interpreted in terms of the mean Coulomb field of a nucleus. The continuum version of the random-phase approximation, allowance for an approximate isospin conservation in nuclei in an explicit form, and a phenomenological description of the fragmentation effect are basic ingredients of the approach used. The aforementioned parameters were calculated for a number of magic and near-magic nuclei by using a partly self-consistent phenomenological nuclear mean field and the isovector part of the Landau-Migdal interaction in the particle-hole channel. The results of the calculations are compared with corresponding experimental data.

Gorelik, M. L.; Rykovanov, V. S.; Urin, M. G., E-mail: urin@theor.mephi.r [National Research Nuclear University MEPhI (Russian Federation)

2010-12-15

428

Molecular dynamics in the isothermal-isobaric ensemble: The requirement of a ``shell'' molecule. II. Simulation results  

NASA Astrophysics Data System (ADS)

The results of a series of constant pressure and temperature molecular-dynamics (MD) simulation studies based on the rigorous shell particle formulation of the isothermal-isobaric (NpT) ensemble are presented. These MD simulations validate the newly proposed constant pressure equations of motion in which a ``shell'' particle is used to define uniquely the volume of the system [M. J. Uline and D. S. Corti, J. Chem. Phys. (to be published), preceding paper]. Ensemble averages obtained with the new MD NpT algorithm match the ensemble averages obtained using the previously derived shell particle Monte Carlo NpT method [D. S. Corti, Mol. Phys. 100, 1887 (2002)]. In addition, we also verify that the Hoover NpT MD algorithm [W. G. Hoover, Phys. Rev. A 31, 1695 (1985); 34, 2499 (1986)] generates the correct ensemble averages, though only when periodic boundary conditions are employed. The extension of the shell particle MD algorithm to multicomponent systems is also discussed, in which we show for equilibrium properties that the identity of the shell particle is completely arbitrary when periodic boundary conditions are applied. Self-diffusion coefficients determined with the shell particle equations of motion are also identical to those obtained in other ensembles. Finally, since the mass of the shell particle is known, the system itself, and not a piston of arbitrary mass, controls the time scales for internal pressure and volume fluctuations. We therefore consider the effects of the shell particle on the dynamics of the system. Overall, the shell particle MD algorithm is an effective simulation method for studying systems exposed to a constant external pressure and may provide an advantage over other existing constant pressure approaches when developing nonequilibrium MD methods.

Uline, Mark J.; Corti, David S.

2005-10-01

429

Modeling of isobaric–isothermal chemical vapor infiltration: effects of reactor control parameters on a densification  

Microsoft Academic Search

This work deals with the integration of off-preform and in-preform physico-chemical phenomena involved in isothermal isobaric CVI for processing of ceramic-matrix composites (CMC). A global modeling approach featuring coupled reactor fluid mechanics and porous medium gas transport has been developed. The coupling between transport and reaction phenomena inside and outside the preform is rather strong, both physically and numerically. In

Nicolas Reuge; Gerard L. Vignoles

2005-01-01

430

The Defect Diffusion Model and Isochoric Energy and Isobaric Enthalpy for Glass Formers  

Microsoft Academic Search

The defect diffusion model produces stretched exponential relaxation, in supercooled liquids, through the sub-diffusive motion of defects. The aggregation of the defects produces a Vogel-Fulcher type law for the divergence of the time scale at a critical temperature. The model is employed to calculate the ratio of the apparent isochoric activation energy to the isobaric activation enthalpy, EV*\\/H* or EV\\/EP,.

Michael Shlesinger; John Bendler; John Fontanella; Mary Wintersgill

2009-01-01

431

Coupled-channel Treatment of Isobaric Analog Resonances in (p,p?) Capture Processes  

NASA Astrophysics Data System (ADS)

With the advent of nuclear reactions on unstable isotopes, there has been a renewed interest in using isobaric analogue resonances (IAR) as a tool for probing the nuclear structure. The position and width of isobaric analogue resonances in nucleon-nucleus scattering are accurate and detailed indicators of the positions of resonances and bound states with good single-particle characters. We report on implementation within our coupled-channels code FRESCO of the charge-exchange interaction term that transforms an incident proton into a neutron. Isobaric analog resonances are seen as peaks in ?-ray spectrum when the proton is transformed into a neutron at an energy near a neutron bound state. The Lane coupled-channels formalism was extended to follow the non-orthogonality of this neutron channel with that configuration of an inelastic outgoing proton, and the target being left in a particle-hole excited state. This is tested for 208Pb, for which good (p,p'?) coincidence data exists.

Thompson, I. J.; Arbanas, G.

2014-04-01

432

Coupled-channel treatment of Isobaric Analog Resonances in (p,p') Capture Processes  

SciTech Connect

With the advent of nuclear reactions on unstable isotopes, there has been a renewed interest in using isobaric analogue resonances (IAR) as a tool for probing the nuclear structure. The position and width of isobaric analogue resonances in nucleon-nucleus scattering are accurate and detailed indicators of the positions of resonances and bound states with good single-particle characters. We report on implementation within our coupled-channels code FRESCO of the charge-exchange interaction term that transforms an incident proton into a neutron. Isobaric analog resonances are seen as peaks in gamma-ray spectrum when the proton is transformed into a neutron at an energy near a neutron bound state. The Lane coupled-channels formalism was extended to follow the nonorthogonality of this neutron channel with that configuration of an inelastic outgoing proton, and the target being left in a particle-hole excited state. This is tested for 208Pb, for which good (p,p g)

Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Arbanas, Goran [ORNL

2013-01-01

433

Escape and spreading widths of the isobaric analog states of Sn and Te isotopes  

NASA Astrophysics Data System (ADS)

The escape widths for direct proton decay from isobaric analog states in Sb and I nuclei have been obtained by combining calculated single-particle widths with experimental spectroscopic information for neutron pickup reactions on the respective Sn and Te target nuclei. They display a pronounced odd- A/even- A staggering effect with very small widths for the even- A isotopes due to the lower proton decay energies. Only data for odd- A nuclei are available, and there is good agreement. Combining the calculated escape widths with the known experimental total widths yields values for the spreading widths. As expected, and in agreement with theoretical predictions, the spreading widths are essentially constant and dependent only weakly on neutron excess. Interestingly, the spreading widths are independent of whether statistical isospin-violating neutron decay is energetically possible or not, as is the case for the isobaric analog states of the light Sn isotopes with A < 116. The branching ratios for the isospin-forbidden neutron decays from the isobaric analog states average about 95% for the heavier even- A Sb isotopes, and about 60% for the odd- A isotopes. Gamma-ray deexcitation and direct and statistical proton decay compete in the decays of the IAS of the light Sn isotopes, and a branching ratio of about 90% for gamma-ray deexcitation is expected for the IAS in 112Sb.

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

1993-02-01

434

Spinal Anesthesia for Knee Arthroscopy Using Isobaric Bupivacaine and Levobupivacaine: Anesthetic and Neuroophthalmological Assessment  

PubMed Central

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.

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

2014-01-01

435

Computing Equilibrium Chemical Compositions  

NASA Technical Reports Server (NTRS)

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

Mcbride, Bonnie J.; Gordon, Sanford

1995-01-01

436

The activity-composition relationship of oxygen and hydrogen isotopes in aqueous salt solutions: II. Vapor-liquid water equilibration of mixed salt solutions from 50 to 100[degrees]C and geochemical implications  

SciTech Connect

The difference between oxygen and hydrogen isotope activity and composition ratios of water in mixed salt solutions in the system Na-K-Mg-Ca-Cl-SO[sub 4]-H[sub 2]O was determined by means of a vapor-liquid water equilibration method over the temperature range of 50 to 100[degrees]C. The observed isotope salt effects in complex mixed salt solutions to very high ionic strengths agree quantitatively with calculations based on the assumption of a simple additive property of the isotope salt effects of the individual salts in the solutions. Sofer and Gat (1972, 1975) and Horita and Gat (1989) also observed that this simple mixing rule applies to synthetic and natural chloride-mixed salt solutions at room temperature. Equations to convert between the isotope activity and composition scales for brines and fractionation factors between brines and other substances are presented. For most geochemical interactions between brines and other phases (vapor, gases, minerals), such as evaporation/boiling, mineral precipitation, and mineral/rock alteration, the isotope activity scale should be used. The isotope composition scale, on the other hand, is most useful for studies of mixing of different brines and formation of brines by mineral dissolution. Misusage of the two isotopic scales of brines will, and probably in the literature has, lead to incorrect conclusions in many isotopic studies of brine-dominated systems (origin of brines, temperature of mineral formation, isotope ratios of fossil fluids).

Horita, J.; Cole, D.R.; Wesolowski, D.J. (Oak Ridge National Lab., TN (United States))

1993-10-01

437

Continuum random phase approximation self-consistent approaches to the theory of isobaric analog resonances  

SciTech Connect

Two approaches (exact and approximate) to the isobaric analog resonance (IAR) theory within the random phase approximation in the continuum are considered. Both of them are based on the partial self-consistency condition which is the result of the isospin symmetry of the nuclear Hamiltonian. The evaluations of the IAR partial proton widths for near magic nuclei over a wide atomic mass region are performed. The results obtained within the framework of these approaches are compared with each other and with the experimental data. The method of the calculation of the Coulomb correction to the IAR transition density is also given.

Rumyantsev, O.A.; Urin, M.H. (Moscow Engineering Physics Institute, 115409, Moscow (Russian Federation))

1994-01-01

438

Analysis of temperature and isobaric volume expansion dependence of elastic moduli of solids  

NASA Astrophysics Data System (ADS)

Thermo-elastic properties of solids at high temperature can be understood adequately by knowing the temperature dependences of their elastic moduli. It has been found that there exists a precise relationship showing exponential dependence of their elastic moduli on isobaric volume expansion for some typical solids such as NaCl, KCL, MgO, and CaO at high temperatures. We have calculated the values of elastic moduli C, C, C,K, and KT at different temperatures for the solids under study. The calculated values of elastic moduli are found to show fairly good agreement with available experimental data.

Xing, Ling-Ling; Peng, Xue-Cheng; Fang, Zheng-Hua

2007-04-01

439

Applied General Equilibrium Analysis  

Microsoft Academic Search

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

440

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

441

Relativistic Figures of Equilibrium  

Microsoft Academic Search

Compact fluid bodies in equilibrium under its own gravitational field are abundant in the Universe and a proper treatment of them can only be carried out using the full theory of General Relativity. The problem is of enormous complexity as it involves two very different regimes, namely the interior and the exterior of the fluid, coupled through the surface of

M Mars

2009-01-01

442

An Equilibrium Model of \\  

Microsoft Academic Search

The sustained rise in US current account deficits, the stubborn decline in long-run real rates, and the rise in US assets in global portfolios appear as anomalies from the perspective of conventional models. This paper rationalizes these facts as an equilibrium outcome when different regions of the world differ in their capacity to generate financial assets from real investments. Extensions

Ricardo J. Caballero; Emmanuel Farhi; Pierre-Olivier Gourinchas

2008-01-01

443

Equilibrium phase compositions, phase densities, and interfacial tensions for CO sub 2 + hydrocarbon systems; CO sub 2 + n-butane + n-decane  

SciTech Connect

This paper presents experimental vapor-liquid equilibrium phase compositions, phase densities, and interfacial tensions for the ternary system CO{sub 2} + n-butane + n-decane at 160{degrees} F. Measurements were made on a mixture of constant overall molar composition of 90.2% CO{sub 2}, 5.9% n-C{sub 4}, 3.9% n-C{sub 10} at pressures from 1310 psia to a near-critical dew point state at 1675 psia. Additional data were obtained at a constant pressure of 1600 psia. The measured phase compositions are in agreement with the data of Metcalfe and Yarborough. The phase densities and interfacial tensions represent data not previously available in the literature.

Nagarajan, N. (Mobil Research and Development Corp., Dallas, TX (US)); Gasem, K.A.M.; Robinson, R.L. Jr. (School of Chemical Engineering, Oklahoma State Univ., Stillwater, OK (US))

1990-07-01

444

? Isobar Degrees of Freedom in the 3He Transverse Electron Scattering Response Function  

NASA Astrophysics Data System (ADS)

The importance of ?(1232) isobar degrees of freedom is investigated for the transverse ( e, e') response of 3He in the quasi-elastic peak region and beyond (considered momentum transfer range: 500 ? q ? 1,000 MeV/c). Besides ? isobar currents ( ?-IC) meson exchange currents and relativistic corrections to the nucleonic one-body current are included. The calculation is carried out by using the Lorentz integral transform (LIT) method. Results for the transverse response function R T are presented up to q = 700 MeV/c, whereas for higher q only some preliminary results for the LIT of R T are discussed. In the quasi-elastic peak region ?-IC enhance R T by about 5% and tend to cancel three-nucleon force effects. One observes an excellent agreement with experimental R T results. Particularly strong ?-IC contributions are found for transitions into the final state with isospin T = 3/2, which is only reachable in three-body break-up reactions.

Leidemann, Winfried; Yuan, Luping; Efros, Victor D.; Orlandini, Giuseppina; Tomusiak, Edward L.

2013-08-01

445

Isobaric-isothermal Monte Carlo simulations from first principles: Application to liquid water at ambient conditions  

SciTech Connect

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

446

?33-isobar contribution to the soft nucleon-nucleon potentials. I. 2?-exchange potentials  

NASA Astrophysics Data System (ADS)

Two-pion-exchange (TPE) nucleon-nucleon potentials are derived for one or two ? isobars in the intermediate states. Strong dynamical pair suppression is assumed. At the NN? and the N?? vertices Gaussian form factors are incorporated into the relativistic two-body framework by using a dispersion representation for the one-pion-exchange amplitudes. The Fourier transformations are performed using factorization techniques for the energy denominators, taking into account the mass difference between the nucleon and the ? isobar. Analytic expressions for the TPE potentials are obtained, which contain at most one-dimensional integrals. The TPE potentials are first calculated up to orders (fNN? fN??)2 and f4N??. These come from the adiabatic contributions of all planar and crossed three-dimensional momentum-space TPE diagrams. We also give the contributions of the OPE iteration, which can be subtracted or not, depending on whether one performs a coupled-channel calculation for, e.g., the NN, N? system, or a single NN-channel calculation. Next, we calculate the (m?/M) corrections. These are due to the 1/M terms in the pion-nucleon vertices, and the 1/M terms in the nonadiabatic expansion of the nucleon energies in the intermediate states.

Rijken, Th. A.; Stoks, V. G. J.

1992-07-01

447

iFASP: combining isobaric mass tagging with filter-aided sample preparation.  

PubMed

Careful, clean and controlled preparation of samples for mass spectrometry proteomics is crucial to obtain reproducible and reliable data. This is especially important when carrying out quantitative proteomics by chemical isobaric labeling (aka tandem mass tagging), since the differentially labeled samples are combined quite late during the sample processing. Addressing this need for robust and reliable sample processing for quantitative proteomics, we describe here iFASP, a simple protocol for combining isobaric mass tagging with the recently introduced filter-aided sample preparation (FASP) method. iFASP provides a quick, simple and effective method for obtaining clean samples, ensuring efficient digestion and providing excellent labeling yields for quantitative proteomics experiments. We have carried out our iFASP protocol using several highly complex Xenopus laevis egg and embryo lysates and compared the labeling yields and number of high-confidence peptide identifications to a standard in-solution digestion and labeling protocol. Although the labeling efficiency with both techniques is in the 99+% range, the number of peptides identified with a 1% false discovery rate and the corresponding number of quantified peptide spectral matches are as much as doubled with iFASP compared to the corresponding non-FASP-based method. PMID:23692318

McDowell, Gary S; Gaun, Aleksandr; Steen, Hanno

2013-08-01

448

An Updated Equilibrium Machine  

NASA Astrophysics Data System (ADS)

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 applied. Equilibrium can be approached from different distributions of balls in the container under different conditions. The Le Châtelier principle can be demonstrated. Kinetic concepts can be demonstrated by changing the nature of the barrier, either changing the height or by having various sized holes in the barrier. Thermodynamic concepts can be demonstrated by taping over some or all of the openings and restricting air flow into container on either side of the barrier.

Schultz, Emeric

2008-08-01

449

Absolute Equilibrium Entropy  

NASA Technical Reports Server (NTRS)

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

Shebalin, John V.

1997-01-01

450

The Donnan Equilibrium  

PubMed Central

We investigate the conditions under which nonideality in solution influences the Donnan equilibrium. Of the various parameters that characterize this equilibrium, the osmotic pressure established across the Donnan membrane is found to be particularly sensitive to intermolecular interactions between the diffusible and nondiffusible ionic species. Under physiologically appropriate conditions, we find that it is almost never valid to use Debye-Hückel theory to calculate ionic activities: it is important to take proper account of ion size. When the diffusible species is a 1-1 electrolyte, this can be done using the mean spherical approximation (MSA) for a mixture of ions of different diameters. For 2-2, or higher-valent, electrolytes one should also include the effects of the second ionic virial coefficient, which the MSA omits.

Stell, G.; Joslin, C. G.

1986-01-01

451

Vapor-liquid phase separator studies  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

452

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

453

Comparative study of fentanyl and morphine in addition to hyperbaric or isobaric bupivacaine in combined spinal anaesthesia for caesarean section  

PubMed Central

Introduction The aim of our study was to compare the effects of isobaric and hyperbaric bupivacaine combined with morphine or fentanyl in patients undergoing caesarean section. We assessed quality and spread of analgesia and anaesthesia, postoperative analgesic requirement and side effects. Material and methods Hundred patients with American Society of Anesthesiologists physical status (ASA) I-II, age 18 to 40 years, were randomized to 4 groups. The intrathecal solutions were isobaric bupivacaine + morphine (group A), isobaric bupivacaine + fentanyl (group B), heavy bupivacaine + + morphine (group C) and heavy bupivacaine + fentanyl (group D). Mean arterial pressure, heart rate, oxygen saturation, ephedrine consumption, analgesic requirement time and additional analgesic needs were recorded. Results The 1st min value of mean arterial pressure was the lowest one in all groups. Heart rate decreased significantly in group A at the 10th min but not in the other groups. The decrease of visual analogue scale (VAS) pain scores began in the groups after the 4th postoperative h (p < 0.05) and the VAS value of group B at the 8th h was significantly higher than the other groups. The first analgesic requirement time in the postoperative period was longer in patients who had intrathecal morphine than those who had fentanyl. The duration of analgesia with isobaric bupivacaine and morphine was the longest one. Conclusions We concluded that intrathecal morphine provides a long duration of postoperative analgesia but the duration gets longer when it is combined with plain bupivacaine instead of heavy bupivacaine.

Saracoglu, Ayten; Saracoglu, Kemal T.; Eti, Zeynep

2011-01-01

454

Analysis of isobaric pesticides in pepper with high-resolution liquid chromatography and mass spectrometry: complementary or redundant?  

PubMed

Five isobaric pesticides are analyzed in red pepper (Capsicum annuum) by high-resolution chromatography (100,000 theoretical plates/meter) and high-resolution mass spectrometry (resolving power > 25000) to test whether these methods are redundant or complementary when using MS/MS analysis. The five compounds are hexaconazole, isazophos, isoxathion, kresoxim-methyl, and triazophos, with an isobaric mass of m/z 314 and 336. Red pepper was chosen as a complex vegetable matrix with more than 4000 adducted ions (MH(+) and MNa(+)). High-resolution chromatography was found to be a valuable tool to separate the isobaric pesticides from one another, whereas the high resolution of the mass spectrometer separated the matrix ions of red pepper easily from the pesticides due to differences in their mass defect. The combination of techniques is especially valuable in MS/MS analysis because of interfering precursor and fragment ions of the isobaric pesticides rather than the complex pepper matrix--a nonintuitive result. PMID:23305249

Thurman, E Michael; Ferrer, Imma; Zavitsanos, Paul; Zweigenbaum, Jerry A

2013-03-13

455

Phase equilibrium predicted by the Soave-Redlich-Kwong equation at low temperatures  

NASA Astrophysics Data System (ADS)

This study developed vapor-liquid equilibrium relationships for vapor pressure and liquid density predicted by the Soave-Redlich-Kwong cubic equation of state (SRK) in the low temperature limit. Dimensionless variables were defined to simplify calculations. One, reduced density, was defined by dividing the actual density by density in the zero temperature limit. During this process, a useful form of the SRK equation was developed. Vapor pressures and phase densities were calculated numerically using a regula-falsi procedure. The method gave efficient calculations for reduced temperatures from approximately 0.0002 to approximately 0.9999. By manipulating the numerical data for reduced pressure and reduced temperature, functional relationships were suggested and verified analytically. Results of the predictive equations for reduced pressure were compared to the numerical results and differed at worst within one order of magnitude over the temperature range from zero to the critical point. Further modeling of the difference between the predictive equations and the actual SRK results is suggested.

Wadelton, Kimberly; Misovich, Michael

2005-03-01

456

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

457

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

PubMed

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

458

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

NASA Astrophysics Data System (ADS)

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.

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

459

The search for nuclear molecules in isobaric analog states of ^10B  

NASA Astrophysics Data System (ADS)

The highly deformed rotational band in ^10Be with molecular like ?:2n:? structure was suggested by [1]. In the work presented here, a search for similar structures in T=1 isobaric analog states in ^10B was performed. The excitation energy range of 8.5 -12.1 MeV was probed using the ^9Be(p,?)^6Li(T=1, 3.56 MeV, 0^+) reaction. An R-matrix analysis was performed which allowed spin-parities and partial widths of the observed states to be determined. The cluster properties of the observed states are discussed. [4pt] [1] M. Freer et al, Phys. Rev. Lett. 96, 042501 (2006).

Kuchera, Anthony; Rogachev, Grigory; Goldberg, Vladilen; Johnson, Eric; Miller, Laniece; Cherubini, Silvio; Gulino, Marisa; Hardy, John; La Cognata, Marco; Lattuada, Marcello; Gianluca Pizzone, Rosario; Romano, Stefano; Spitaleri, Claudio; Tribble, Robert; Trzaska, Wladek; Tumino, Aurora

2011-10-01

460

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

461

Development of a high resolution isobar separator for study of exotic decays  

NASA Astrophysics Data System (ADS)

A compact isobar spectrometer and separator, based on the multi-pass-time-of-flight (MTOF) principle, is being developed by the University radioactive ion beam (UNIRIB) Consortium. It consists of two coaxial, grid-free electrostatic mirrors with auxiliary injection, focusing and extraction elements. Ions of different mass are reflected multiple times between the mirrors and separated longitudinally. Using an electron beam impact ion source and N 2 as a sample gas, a mass resolving power of 110,000 (FWHM) has been achieved. In the near future, MTOF will be coupled to the on-line isotope separator UNISOR (University Isotope Separator - Oak Ridge) at Holifield radioactive ion beam facility using electrostatic beam deceleration, a radiofrequency beam cooler and a fast buncher. It will serve as a high resolution mass separator with a Bradbury-Nielsen gate, providing isotopically pure samples of exotic species in the 100Sn region and later, of neutron rich nuclei, for use in decay studies.

Piechaczek, A.; Shchepunov, V.; Carter, H. K.; Batchelder, J. C.; Zganjar, E. F.; Liddick, S. N.; Wollnik, H.; Hu, Y.; Griffith, B. O.

2008-10-01

462

Discrimination of Isobaric Leu/Ile Residues by MALDI In-Source Decay Mass Spectrometry  

NASA Astrophysics Data System (ADS)

MALDI in-source decay (ISD) has been used for top-down sequencing of proteins. The use of the matrix 1,5-diaminonapthalene (1,5-DAN) gave abundant w ions, which are formed from the unimolecular dissociation of z• radical fragments via ? cleavage reaction and thus help identify which of the isobaric amino acids, Leu or Ile, is present. The high abundance of w ions in MALDI-ISD with 1,5-DAN results from the low collision rate in the MALDI plume. MALDI-ISD with 1,5-DAN appears to be an useful method for the top-down sequencing of proteins, including discrimination of Leu and Ile near the C-terminal end.

Asakawa, Daiki; Smargiasso, Nicolas; De Pauw, Edwin

2013-02-01

463

Calculation of the Isobaric Analogue Resonance Using Shell Model in the Complex Energy Plane  

NASA Astrophysics Data System (ADS)

A convenient tool for studying nuclei being far away from the beta stability line is the complex energy shell model (CXSM) in which the Berggren representation (Nucl. Phys. A 109:265, 1968) (BR) is used. The BR is formed from bound, resonant sates, and complex-energy scattering states. The parameters of isobaric analog resonance (IAR) are calculated in the framework of the Lane-model (Nucl. Phys. A 35:676, 1962) using CXSM. The novel feature of the present CXSM calculation is that the optical potentials used are complex. Results of the CXSM calculation are checked against those of the standard solution of the coupled channel Lane-equations (CC). The IAR parameters calculated by the CXSM agree well with that of the CC results for absorptive and emittive optical potentials. This agreement confirms the applicability of the CXSM calculation for complex potential.

Id Betan, R.; Rácz, A.; Vertse, T.

2011-07-01

464

Calculation The Isobaric Analogue Resonance Using Shell Model in The Complex Energy Plane  

SciTech Connect

A convenient tool for studying nuclei being far away from the beta stability line is the complex energy shell model (CXSM) in which the Berggren representation (Nucl. Phys. A 109:265, 1968) (BR) is used. The BR is formed from bound, resonant sates, and complex-energy scattering states. The parameters of isobaric analog resonance (IAR) are calculated in the framework of the Lane-model (Nucl. Phys. A 35:676, 1962) using CXSM. The novel feature of the present CXSM calculation is that the optical potentials used are complex. Results of the CXSM calculation are checked against those of the standard solution of the coupled channel Lane-equations (CC). The IAR parameters calculated by the CXSM agree well with that of the CC results for absorptive and emittive optical potentials. This agreement confirms the applicability of the CXSM calculation for complex potential.

Racz, A. [University of Debrecen, Hungary; Vertse, T. [Institute of Nuclear Research of the Hungarian Academy of Sciences; Id Betan, Rodolfo M [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

2011-01-01

465

The Defect Diffusion Model and Isochoric Energy and Isobaric Enthalpy for Glass Formers  

NASA Astrophysics Data System (ADS)

The defect diffusion model produces stretched exponential relaxation, in supercooled liquids, through the sub-diffusive motion of defects. The aggregation of the defects produces a Vogel-Fulcher type law for the divergence of the time scale at a critical temperature. The model is employed to calculate the ratio of the apparent isochoric activation energy to the isobaric activation enthalpy, EV*/H* or EV/EP,. This ratio measures the relative sensitivity of kinetic processes to changes in volume and temperature respectively. This ratio equation is tested using dielectric relaxation data for poly(vinyl acetate), viscosity data for glycerol and ionic conductivity data for poly(propylene glycol) containing LiCF3SO3. Good agreement between theory and experiment is found using model parameters previously published.

Shlesinger, Michael; Bendler, John; Fontanella, John; Wintersgill, Mary

2009-03-01

466

Split isobaric analog state in 55Ni: case of strong isospin mixing.  

PubMed

Study of ?+ decay of the exotic Tz=-3/2 nucleus 55Cu, via delayed ? rays, has revealed a strongly isospin mixed doublet (4599-4579 keV) in 55Ni, which represents the fragmented and previously unknown isobaric analog of the ground state of 55Cu. The observed small log?ft values to both states in the doublet confirm the superallowed Fermi ? decay. The near degeneracy of a pair of 3/2- levels in 55Ni results in the strong isospin mixing. The isospin mixing matrix element between the T=3/2 and T=1/2 levels is inferred from the experiment to be 9(1) keV, which agrees well with the matrix element of the charge symmetry breaking shell model Hamiltonian of Ormand and Brown. A precise value of the half-life of 55Cu at 57(3) ms was also obtained. PMID:24483792

Tripathi, Vandana; Tabor, S L; Volya, A; Liddick, S N; Bender, P C; Larson, N; Prokop, C; Suchyta, S; Tai, P-L; Vonmoss, J M

2013-12-27

467

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

468

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

PubMed

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

469

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

470

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

NASA Astrophysics Data System (ADS)

Selective tagging techniques have been used to establish new band structures in the transitional isobars 163Re and 163W. These nuclei were produced in the 106Cd(60Ni, xp yn ?) reaction at a bombarding energy of 270 MeV. Prompt ? rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated by the RITU separator and implanted into the GREAT spectrometer. At low spin, the yrast band of 163Re is shown to be a strongly coupled collective band based on a proton h11/2 configuration. In 163W, the decay path of the 13/2+ isomeric state to the ground state has been identified and negative parity structures based on the ground state established.

Joss, D. T.; Thomson, J.; Scholey, C.; Ertürk, S.; Simpson, J.; Page, R. D.; Bianco, L.; Cederwall, B.; Darby, I. G.; Eeckhaudt, S.; Gomez-Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Lagergren, K.; Leino, M.; Leppännen, A.-P.; Nyman, M.; O'Donnell, D.; Pakarinen, J.; Paul, E. S.; Rahkila, P.; Sandzelius, M.; Sorri, J.; Sarén, J.; Uusitalo, J.; Venhart, M.

2008-11-01

471

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

472

Equilibrium Molecular Dynamics Simulations  

NASA Astrophysics Data System (ADS)

Molecular dynamics (MD) is a widely used atomistic simulation method due to the detailed information it can provide, often with a relatively small computational investment. The most distinguishing attribute of MD among molecular simulation methods is that it provides a means to monitor the time evolution of a system of particles (usually atoms) in phase space, thus allowing for an atomic-level view of the dynamics of a material in a given equilibrium or nonequilibrium thermodynamic state. This is particularly appealing for those in the energetic materials (EM) community since such a detailed description could reveal the fundamental mechanisms controlling the initiation of an energetic material to detonation, a phenomenon for which direct experimental measurement is in short Superscriptply due to the small time and spatial scales involved and the accompanying large rates of chemical energy release. MD is not affected by any of these factors; rather, its main limitations are the description of interatomic interactions (potential energy functions) used in the simulations and the viability of using classical mechanics to study molecular-scale phenomena. MD is receiving increased use in condensed-phase EM research as interaction potentials emerge that "realistically" describe the chemistry associated with initiation of an EM. However, MD is not limited to studying nonequilibrium dynamic events only; it has proven to be extremely useful for predicting thermodynamic equilibrium properties in the condensed phase.

Rice, Betsy M.; Sewell, Thomas D.

473

Coin Flip Equilibrium  

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

474

High-pressure vapor-liquid equilibria for CO[sub 2] + benzonitrile, CO[sub 2] + benzyl alcohol, CO[sub 2] + 2-tert-butylphenol, CO[sub 2] + methoxybenzene, and CO[sub 2] + 1,2,3,4-Tetrahydronaphthalene at temperatures between 313 and 393 K and pressures up to 20 MPa  

SciTech Connect

High-pressure vapor-liquid equilibria are reported for CO[sub 2] + benzonitrile, CO[sub 2] + benzyl alcohol, CO[sub 2] + 1-tert-butylphenol, CO[sub 2] + methoxybenzene, and CO[sub 2] + 1,2,3,4-tetrahydronaphthalene at three temperatures from 313 to 393 K and pressures up to 20 MPa. The investigations were made by using a flow-type apparatus. The results for CO[sub 2] + methoxybenzene are compared to literature values. On the other systems no literature values are available.

Walther, D.; Maurer, G. (Univ. Kaiserslautern (Germany))

1993-04-01

475

Vapor-liquid coexistence curves in the critical region and the critical temperatures and densities of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea)  

Microsoft Academic Search

The vapor-liquid coexistence curves in the critical region of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea) were measured by a visual observation of the meniscus disappearance in an optical cell. Seventeen saturated-vapor and -liquid densities have been measured for R-134a. Thirty-five saturated-vapor and -liquid densities have been measured for R-143a. Twenty-seven saturated-vapor and -liquid densities have been measured for R-236ea.

Hirokazu Aoyama; Go Kishizawa; Haruki Sato; Koichi Watanabe

1996-01-01

476

Applications of the Soave-Redlich-Kwong Equations of State Using Mathematic  

NASA Astrophysics Data System (ADS)

The application of the Peng-Robinson equations of state (PR EOS) using Matlab and Mathematic has already been demonstrated. In this paper, using Mathematic to solve Soave-Redlich-Kwong (SRK) EOS, as well as the estimation of pure component properties, plotting of vapor-liquid equilibrium (VLE) diagram and calculation of chemical equilibrium, is presented. First the SRK EOS is used to predict several pure-component properties, such as liquid and gas molar volumes for isobutane. The vapor-liquid isobaric diagram is then plotted for a binary mixture composed of n-pentane and n-hexane under the pressures of 2*10^5 and 8*10^5 Pa respectively.

Sun, Lanyi; Zhai, Cheng; Zhang, Hui

477

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

478

Weak Acid Equilibrium  

NSDL National Science Digital Library

Students are asked to calculate the pH of a weak acid aqueous solution. The problems involve a series of generic acids with assigned equilibrium constants (Ka) and total concentrations (Ct). Initially, students are required to hand calculate all problems by algebraic manipulation of the mathematical relationships of the system. The solution is a cubic equation. Through a series of assumptions, the solution is simplified. The assumptions are based on the chemistry of the system given the Ka and Ct for the problem. The problems are then graphically solved. Ultimately, the students develop an Excel worksheet to solve the problems and a Bjerrum plot to display the speciation as a function of pH.

Stapleton, Michael

479

Statistical physics ""Beyond equilibrium  

SciTech Connect

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

Ecke, Robert E [Los Alamos National Laboratory

2009-01-01

480

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

SciTech Connect

Recently, empirical kappa distribution, commonly used to describe non-equilibrium systems like space plasmas, has been connected with non-extensive statistical mechanics. Here we show how a consistent definition of the temperature and pressure is developed for stationary states out of thermal equilibrium, so that the familiar ideal gas state equation still holds. In addition to the classical triplet of temperature, pressure, and density, this generalization requires the kappa index as a fourth independent thermodynamic variable that characterizes the non-equilibrium stationary states. All four of these thermodynamic variables have key roles in describing the governing thermodynamical processes and transitions in space plasmas. We introduce a novel characterization of isothermal and isobaric processes that describe a system's transition into different stationary states by varying the kappa index. In addi