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1

Condensation/evaporation of insoluble organic vapor as functions of source rate and saturation vapor pressure  

NASA Astrophysics Data System (ADS)

Condensation growth of atmospheric particles by insoluble organic vapors was studied by a monodisperse aerosol dynamics model MONO32 including atmospheric chemistry mechanism. The source rate of the vapor and its saturation vapor density at a particle surface were varied. The initial particle number size distribution was assumed to be bimodal, and aerosol was initially an internal mixture of particles consisting of soluble sulphuric acid and insoluble organic material in a ratio of 1:1. Model simulations predicted that if the ratio of the vapor source rate and the condensation sink of particles, Q/CS, exceeded 108 cm-3 and the vapor was nonvolatile or low volatile, the 10 nm nuclei grew with the growth rates of 2.5-3 nm h-1 and could act as cloud condensation nuclei in supersaturations of 1.6% or lower after 24 h simulation. Then the vapors must have saturation vapor pressures less than 7 × 106 cm-3. However, the higher the ratio of Q/CS, the higher the saturation vapor pressure could be. When the vapor was highly volatile, i.e., the saturation vapor density was high enough, in our simulations greater than 6 × 107 cm-3 the Ostwald ripening was observed. Then the nucleation mode particles were not able to grow but coagulated with larger particles without causing any significant impact on climate. An analytical expression for the saturation vapor density for the Ostwald ripening (cOst) was derived as a function of the ratio of Q/CS. Sensitivity tests for the accommodation coefficient and thermodynamic parameters as well as their effects on cOst were investigated.

Pirjola, Liisa; Korhonen, Hannele; Kulmala, Markku

2002-06-01

2

Vapor pressure measurements on low-volatility terpenoid compounds by the concatenated gas saturation method.  

PubMed

The atmospheric oxidation of monoterpenes plays a central role in the formation of secondary organic aerosols (SOAs), which have important effects on the weather and climate. However, models of SOA formation have large uncertainties. One reason for this is that SOA formation depends directly on the vapor pressures of the monoterpene oxidation products, but few vapor pressures have been reported for these compounds. As a result, models of SOA formation have had to rely on estimated values of vapor pressure. To alleviate this problem, we have developed the concatenated gas saturation method, which is a simple, reliable, high-throughput method for measuring the vapor pressures of low-volatility compounds. The concatenated gas saturation method represents a significant advance over traditional gas saturation methods. Instead of a single saturator and trap, the concatenated method uses several pairs of saturators and traps linked in series. Consequently, several measurements of vapor pressure can be made simultaneously, which greatly increases the rate of data collection. It also allows for the simultaneous measurement of a control compound, which is important for ensuring data quality. In this paper we demonstrate the use of the concatenated gas saturation method by determination of the vapor pressures of five monoterpene oxidation products and n-tetradecane (the control compound) over the temperature range 283.15-313.15 K. Over this temperature range, the vapor pressures ranged from about 0.5 Pa to about 70 Pa. The standard molar enthalpies of vaporization or sublimation were determined by use of the Clausius-Clapeyron equation. PMID:20000397

Widegren, Jason A; Bruno, Thomas J

2010-01-01

3

The Observed Properties of Liquid Helium at the Saturated Vapor Pressure  

Microsoft Academic Search

The equilibrium and transport properties of liquid 4He are deduced from experimental observations at the saturated vapor pressure. In each case, the bibliography lists all known measurements. Quantities reported here include density, thermal expansion coefficient, dielectric constant, superfluid and normal fluid densities, first, second, third, and fourth sound velocities, specific heat, enthalpy, entropy, surface tension, ion mobilities, mutual friction, viscosity

Russell J. Donnelly; Carlo F. Barenghi

1998-01-01

4

The temperature dependence of saturated vapor pressure over alkaline-earth metal pivaloyltrifluoroacetonate complexes  

NASA Astrophysics Data System (ADS)

The temperature dependences of saturated vapor pressure over M(PTA)2 · 15-crown-5, where M = Ca, Sr, or Ba and PTA is the pivaloyltrifluoroacetonate anion, were studied by the Knudsen effusion method, and the enthalpies of compound sublimation were calculated. Changes in volatility depending on the central metal atom were determined.

Efimova, Yu. A.; Abakumov, G. A.; Petrov, B. I.; Pochekutova, T. S.; Khamylov, V. K.

2008-11-01

5

Assessment of feldspar solubility constants in water in the range of 0 to 350 C at vapor saturation pressures  

SciTech Connect

The equilibrium constants for endmember feldspar hydrolysis for the following reactions: NaAlSi{sub 3}O{sub 8} + 8H{sub 2}O = Na{sup +} + Al(OH){sub 4}{sup {minus}} + 3H{sub 4}SiO{sub 4}{sup 0}; KAlSi{sub 3}O{sub 8} + 8H{sub 2}O = K{sup +} + Al(OH){sub 4}{sup {minus}} + 3H{sub 4}SiO{sub 4}{sup 0}; CaAl{sub 2}Si{sub 2}O{sub 8} + 8H{sub 2}O = Ca{sup +2} + 2Al(OH){sub 4}{sup {minus}} + 2H{sub 4}SiO{sub 4}{sup 0} are accurately described by five equations where temperature is in K. They are valid in the range 0 to 350 C, at 1 bar below 100 C and at vapor saturation pressures (P{sub sat}) at higher temperatures. The equations for low-albite and microcline are valid for Amelia albite and for microcline with the same degree of Al-Si order (Z = 0.95), respectively. The same kind of log K-temperature equations have also been retrieved for alkali-feldspar and plagioclase solid solutions. The calculated feldspar equilibrium constants of this study indicate much higher solubility under weathering conditions than generally accepted to date, the difference being more than one and a half orders of magnitude at 0 C for both high- and low-albite, but somewhat less for microcline, sanidine, and anorthite. This higher solubility is largely a consequence of new data for the thermodynamic properties of H{sub 4}SiO{sub 4}{sup 0}. The present results have a particularly important bearing on the stability of feldspars under weathering conditions and the study of interaction between water and rock/soil in this environment. They are, however, also important for the study of equilibrium/dis-equilibrium conditions in active geothermal systems.

Arnorsson, S.; Stefansson, A. [Univ. of Iceland, Reykjavik (Iceland). Science Inst.

1999-03-01

6

Heat capacity, saturation vapor pressure, and thermodynamic functions of ethyl esters of C3-C5 and C18 carboxylic acids  

NASA Astrophysics Data System (ADS)

The heat capacities of ethyl propanoate (EPr), ethyl n-pentanoate (EPen), and ethyl n-octadecanoate (ethyl stearate, ESt) were measured by vacuum adiabatic calorimetry in the temperature range of 6 to 373 K. Triple point temperatures, fusion enthalpies and entropies, and purity of the samples of the sub-stances under study were determined. The saturation vapor pressures for EPr and EPen were determined by comparative ebulliometry in an atmospheric pressure range of 4.0 to 101.7 kPa. The normal boiling points and vaporization enthalpies vs. temperature were obtained. The standard thermodynamic functions ( S, H, and G) were calculated for the condensed and ideal gas states on the basis of the experimental data. The vapor pressures of the atmospheric range were extrapolated to entire ranges of the liquid phases of EPr and EPen using the principle of corresponding states and the combined processing of pT parameters and low-temperature differences in the heat capacities of an ideal gas and liquid.

Agafonova, L. E.; Varushchenko, R. M.; Druzhinina, A. I.; Polyakova, O. V.; Kolesov, Yu. S.

2011-09-01

7

Vapor pressure of explosives  

Microsoft Academic Search

New vapor pressure data is presented for RDX, PETN, TNT, nitroglycerin, and ammonium nitrate. By comparison with the data of previous workers, it has been possible to calculate global vapor pressure expressions which are valid over a wide range of temperatures.

B. C. Dionne; D. P. Rounbehler; E. K. Achter; J. R. Hobbs; D. H. Fine

1986-01-01

8

The thermal conductivity of and convective onset in liquid {sup 3}He at saturated vapor pressure above 1.3 K  

SciTech Connect

This paper presents thermal conductivity data for liquid {sup 3}He taken at saturated vapor pressure (s.v.p.), and also the critical Rayleigh number at which convection begins. The temperature in this experiment ranged from 1.3 K to 3.2 K. We compare the thermal conductivity results with those of earlier experimenters, and find they agree well. The convective onset measurements are the first reported for {sup 3}He, and we find the critical Rayleigh number Ra{sub c} = 1500 {+-} 105, which is similar to the experimental values reported for {sup 4}He. References are provided for the thermodynamic properties necessary for calculating the Rayleigh number Ra at s.v.p.

Murphy, D.; Meyer, H. [Duke Univ., Durham, NC (United States)

1994-12-01

9

Vapor Pressure measurements for dichlorosilane  

E-print Network

trichlorosilane and silicon tetrachloride, or other chemicals which are not in the silane family. Accurate information about the vapor pressure is necessary in the production of these mixtures. Measurements reported previously for the vapor pressure of pure...

Morris, Tony Knimbula

2012-06-07

10

7, 1183911894, 2007 Vapor pressure  

E-print Network

ACPD 7, 11839­11894, 2007 Vapor pressure prediction J. F. Pankow and W. E. Asher Title Page pressures and enthalpies of vaporization of multifunctional organic compounds J. F. Pankow 1 and W. E. Asher (pankow@ebs.ogi.edu) 11839 #12;ACPD 7, 11839­11894, 2007 Vapor pressure prediction J. F. Pankow and W. E

Paris-Sud XI, Université de

11

Vapor Pressure Formulation for Ice  

Microsoft Academic Search

A new formulation is presented for the vapor pressure of ice from the triple point to —100 °C based on thermodynamic calculations. Use is made of the definitive experimental value of the vapor pressure of water at its triple point recently obtained by Guildner, Johnson, and Jones. A table is given of the vapor pressure as a function of temperature

Arnold Wexler

1977-01-01

12

The vapor pressures of explosives  

SciTech Connect

The vapor pressures of many explosive compounds are extremely low and thus determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the vapor pressures of explosives compounds at single temperatures, or as a function of temperature using vapor pressure equations. There are large variations in reported vapor pressures for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive vapor pressures and describes the methods used to determine them. We have compiled primary vapor pressure relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate vapor pressures at 25 °C.

Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.; Grate, Jay W.; Hotchkiss, Peter

2013-01-05

13

Enthalpies of Vaporization and Vapor Pressures of Some Deuterated Hydrocarbons. Liquid-Vapor Pressure Isotope Effects  

E-print Network

Enthalpies of Vaporization and Vapor Pressures of Some Deuterated Hydrocarbons. Liquid-Vapor pressures as a function of temperature and enthalpies of vaporization of a series of both liquid and solid. The applicability of this technique is first demonstrated by reproducing the vapor pressure isotope effect

Chickos, James S.

14

[High frequency jet ventilation in heated gas saturated in water vapor without a reserve of medical gas under pressure. An original method].  

PubMed

A prototype of high frequency jet ventilator is compared with a classic device: Gambro Soxijet ventilator. The advantages of the prototype are: no need of pressured medical gas; warming and saturated moisture of the gas. A powerful compressor (2 M3.H-1 flow--3 bar pressure) draws up the moistened and warmed gases and injects them into a double pneumatic capacity. The first capacity is pressure limited by a relief valve (3 bar). Exhausted gases flow back to the pump. A miniature pressure regulator, placed between the two capacities, rules the driving pressure. Gas mixture is injected through a solenoid valve controlled by an electronic twin-timer. Results of both devices are similar. However, our prototype seems to be very convenient for developing countries where medical gases under high pressure are not often available. PMID:1515955

Neidhardt, A; Péquignot, M; Combe, M; Bachour, K; Badet, J M

1992-01-01

15

Precision ozone vapor pressure measurements  

NASA Technical Reports Server (NTRS)

The vapor pressure above liquid ozone has been measured with a high accuracy over a temperature range of 85 to 95 K. At the boiling point of liquid argon (87.3 K) an ozone vapor pressure of 0.0403 Torr was obtained with an accuracy of + or - 0.7 percent. A least square fit of the data provided the Clausius-Clapeyron equation for liquid ozone; a latent heat of 82.7 cal/g was calculated. High-precision vapor pressure data are expected to aid research in atmospheric ozone measurements and in many laboratory ozone studies such as measurements of cross sections and reaction rates.

Hanson, D.; Mauersberger, K.

1985-01-01

16

VAPORIZATION THERMODYNAMICS OF KCl. COMBINING VAPOR PRESSURE AND GRAVIMETRIC DATA  

E-print Network

1 VAPORIZATION THERMODYNAMICS OF KCl. COMBINING VAPOR PRESSURE AND GRAVIMETRIC DATA Rudnyi E of thermodynamic properties of the vapor and the vaporization process, coupling pressure measurements the various studies ina general way. New values for thermodynamic properties of the monomer and dimer vapor

Rudnyi, Evgenii B.

17

Vapor pressure measured with inflatable plastic bag  

NASA Technical Reports Server (NTRS)

Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.

1965-01-01

18

Configuration and testing of a saturated vapor helium compressor  

NASA Astrophysics Data System (ADS)

A saturated vapor helium compressor was designed and tested as a component of a helium-temperature refrigeration cycle. The use of the cold compressor allows reduction of both the precooling heat exchanger area and main compressor size compared to a conventional cycle due to increased pressure of the return gas. The compressor tested was a single-piston reciprocating device which was controlled with programmable hydraulic/pneumatic logic. The compressor was mounted at the cold end of a CTI Model 1400 helium liquefier. An average compression ratio of 2.4 was obtained and an average efficiency of 82 percent was achieved. In computing compressor efficiency, external heat leaks to the compressor were neglected.

Ludwigsen, Jill L.; Smith, J. L., Jr.; Iwasa, Y.

19

Vapor Pressure Measurements in a Closed System  

ERIC Educational Resources Information Center

An alternative method that uses a simple apparatus to measure vapor pressure versus temperature in a closed system, in which the total pressure is the vapor pressure of the liquid sample, is described. The use of this apparatus gives students a more direct picture of vapor pressure than the isoteniscope method and results have generally been quite…

Iannone, Mark

2006-01-01

20

A survey and new measurements of ice vapor pressure at temperatures between 170 and 250K  

Microsoft Academic Search

Saturated vapor pressures of ice at temperatures below 200K have become more important since the discovery of ice clouds in the polar stratosphere and upper mesosphere. Direct measurements of ice vapor pressures at such low temperatures are sparse and unreliable. This paper summarizes published vapor pressure data and presents new measurements at temperatures between 170 and 250K, extending the range

James Marti; Konrad Mauersberger

1993-01-01

21

Vapor pressures of the polychlorinated naphthalenes  

Microsoft Academic Search

The vapor pressures of the supercooled liquid P{sub L} for 17 polychlorinated naphthalene congeners were determined as a function of temperature with a gas chromatographic retention time technique. The method was calibrated with vapor pressure data for polychlorinated biphenyls (PCBs) which had been measured by other techniques. These data were employed to predict temperature-dependent vapor pressures for all polychlorinated naphthalenes

Ying Duan Lei; W. Y. Shiu; F. Wania

1999-01-01

22

MHD generators based on saturated alkali-metal vapors  

Microsoft Academic Search

A scheme is considered for an MHD power station in which the MHD generator works in a closed cycle with a nonideal plasma made of the saturated vapor of cesium or potassium. Use is made of the anomalously high conductivity of such a plasma. The enthalpy transformation coefficient in the cycle is 18--25% with a maximum temperature in the cycle

L. M. Biberman; A. A. Likalter; I. T. Yakubov

1982-01-01

23

Vapor pressure above ice at temperatures below 170 K  

Microsoft Academic Search

Ice clouds in the earth's atmosphere and the presence of ices in comets and on planetary surfaces have raised the interest in the formation and existence of ice particles and of ice in bulk matter. Of special importance are the saturated vapor pressures well below 200 K. Marti and Mauersberger [1993] published a simple, experimentally derived equation that covers the

Konrad Mauersberger; Dieter Krankowsky

2003-01-01

24

Non-LTE dust nucleation in sub-saturated vapors  

E-print Network

We use the kinetic theory of nucleation to explore the properties of dust nucleation in sub-saturated vapors. Due to radiation losses, the sub-critical clusters have a smaller temperature compared to their vapor. This alters the dynamical balance between attachment and detachment of monomers, allowing for stable nucleation of grains in vapors that are sub-saturated for their temperature. We find this effect particularly important at low densities and in the absence of a strong background radiation field. We find new conditions for stable nucleation in the n-T phase diagram. The nucleation in the non-LTE regions is likely to be at much slower rate than in the super-saturated vapors. We evaluate the nucleation rate, warning the reader that it does depend on poorly substantiated properties of the macro-molecules assumed in the computation. On the other hand, the conditions for nucleation depend only on the properties of the large stable grains and are more robust. We finally point out that this mechanism may be relevant in the early universe as an initial dust pollution mechanism, since once the interstellar medium is polluted with dust, mantle growth is likely to be dominant over non-LTE nucleation in the diffuse medium.

Davide Lazzati

2007-11-09

25

Film boiling of saturated liquid flowing upward through a heated tube : high vapor quality range  

E-print Network

Film boiling of saturated liquid flowing upward through a uniformly heated tube has been studied for the case in which pure saturated liquid enters the tube and nearly saturated vapor is discharged. Since a previous study ...

Laverty, W. F.

1964-01-01

26

Vapor Pressures and Vaporization Enthalpies of a Series of Dialkyl Phthalates by Correlation Gas Chromatography  

E-print Network

Vapor Pressures and Vaporization Enthalpies of a Series of Dialkyl Phthalates by Correlation Gas in this regard include dimethyl phthalate dimethyl terephthalate, dimethyl isophthalate, diethyl phthalate, dibutyl phthalate, and bis(2-ethylhexyl) phthalate. New vaporization enthalpies and liquid vapor pressure

Chickos, James S.

27

An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines  

NASA Technical Reports Server (NTRS)

The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to generate property tables from existing property packages and a method to facilitate the accurate interpretation of fluid thermodynamic property data from those tables. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package. The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

Nguyen, Huy H.; Martin, Michael A.

2004-01-01

28

Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Heterocycles and Related Compounds  

E-print Network

Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures The vaporization enthalpies and vapor pressures of the liqiud phase from T ) 298.15 K to T ) 500 K of a series in the literature was measured on a hydrated form. Vapor pressures and normal boiling temperatures for the liquid

Chickos, James S.

29

Temperature gradient effects on vapor diffusion in partially-saturated porous media  

SciTech Connect

Vapor diffusion in porous media in the presence of its own liquid may be enhanced due to pore-scale processes, such as condensation and evaporation across isolated liquid islands. Webb and Ho (1997) developed one-and two-dimensional mechanistic pore-scale models of these processes in an ideal porous medium. For isothermal and isobaric boundary conditions with a concentration gradient, the vapor diffusion rate was significantly enhanced by these liquid island processes compared to a dry porous media. The influence of a temperature gradient on the enhanced vapor diffusion rate is considered in this paper. The two-dimensional pore network model which is used in the present study is shown. For partially-saturated conditions, a liquid island is introduced into the top center pore. Boundary conditions on the left and right sides of the model are specified to give the desired concentration and temperature gradients. Vapor condenses on one side of the liquid island and evaporates off the other side due to local vapor pressure lowering caused by the interface curvature, even without a temperature gradient. Rather than acting as an impediment to vapor diffusion, the liquid island actually enhances the vapor diffusion rate. The enhancement of the vapor diffusion rate can be significant depending on the liquid saturation. Vapor diffusion is enhanced by up to 40% for this single liquid island compared to a dry porous medium; enhancement factors of up to an order of magnitude have been calculated for other conditions by Webb and Ho (1997). The dominant effect on the enhancement factor is the concentration gradient; the influence of the temperature gradient is smaller. The significance of these results, which need to be confirmed by experiments, is that the dominant model of enhanced vapor diffusion (EVD) by Philip and deVries (1957) predicts that temperature gradients must exist for EVD to occur. If there is no temperature gradient, there is no enhancement. The present results indicate that EVD is predominantly driven by concentration gradients; temperature gradients are less important. Therefore, the EVD model of Philip and deVries may need to be modified to reflect these results.

Webb, S.W.

1999-07-01

30

Clausius-Clapeyron Equation and Saturation Vapour Pressure: Simple Theory Reconciled with Practice  

ERIC Educational Resources Information Center

While the Clausius-Clapeyron equation is very important as it determines the saturation vapour pressure, in practice it is replaced by empirical, typically Magnus-type, equations which are more accurate. It is shown that the reduced accuracy reflects an inconsistent assumption that the latent heat of vaporization is constant. Not only is this…

Koutsoyiannis, Demetris

2012-01-01

31

Vapor pressures of acetylene at low temperatures  

NASA Technical Reports Server (NTRS)

The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

1990-01-01

32

Vaporization Enthalpies and Vapor Pressures of Two Insecticide Components, Muscalure and Empenthrin, by Correlation Gas  

E-print Network

Vaporization Enthalpies and Vapor Pressures of Two Insecticide Components, Muscalure and Empenthrin: The vaporization enthalpies at T/K = 298.15 and vapor pressures from T/K = (298.15 to Tnb (normal boiling. Vaporization enthalpies of [(114.4 ± 1.0) and (114.5 ± 1.0)] kJ·mol-1 and vapor pressures, p/Pa = [(1.2 ± 0

Chickos, James S.

33

Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Hydrocarbons  

E-print Network

Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures and liquid vapor pressures from T ) 298.15 K to T ) 510 K of a series of polyaromatic hydrocarbons have been of a thermochemical cycle, and agreement is within the combined experimental uncertainties. Vapor pressures

Chickos, James S.

34

An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines  

NASA Technical Reports Server (NTRS)

The availability and proper utilization of fluid properties is of fundamental importance in the process of mathematical modeling of propulsion systems. Real fluid properties provide the bridge between the realm of pure analytiis and empirical reality. The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described, for example, in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to be used to facilitate the accurate interpretation of fluid thermodynamic property data generated by existing property packages. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package (based on fundamental equations of state approach). The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

Nguyen, Huy H.; Martin, Michael A.

2003-01-01

35

Vapor Pressure, Vapor Composition and Fractional Vaporization of High Temperature Lavas on Io  

NASA Technical Reports Server (NTRS)

Observations show that Io's atmosphere is dominated by SO2 and other sulfur and sulfur oxide species, with minor amounts of Na, K, and Cl gases. Theoretical modeling and recent observations show that NaCl, which is produced volcanically, is a constituent of the atmosphere. Recent Galileo, HST and ground-based observations show that some volcanic hot spots on Io have extremely high temperatures, in the range 1400-1900 K. At similar temperatures in laboratory experiments, molten silicates and oxides have significant vapor pressures of Na, K, SiO, Fe, Mg, and other gases. Thus vaporization of these species from high temperature lavas on Io seems likely. We therefore modeled the vaporization of silicate and oxide lavas suggested for Io. Our results for vapor chemistry are reported here. The effects of fractional vaporization on lava chemistry are given in a companion abstract by Kargel et al.

Fegley, B., Jr.; Schaefer, L.; Kargel, J. S.

2003-01-01

36

The hysteretic evapotranspiration--Vapor pressure deficit relation  

E-print Network

The hysteretic evapotranspiration--Vapor pressure deficit relation Quan Zhang1,2 , Stefano Manzoni3 evapotranspiration (ET) and vapor pressure deficit (VPD) was reported in many ecosystems, but justification for its transpiration) and vapor pressure deficit (VPD) has also been observed in many different ecosystems (Figure 1

Katul, Gabriel

37

Heating of a fully saturated darcian half-space: Pressure generation, fluid expulsion, and phase change  

USGS Publications Warehouse

Analytical solutions are developed for the pressurization, expansion, and flow of one- and two-phase liquids during heating of fully saturated and hydraulically open Darcian half-spaces subjected to a step rise in temperature at its surface. For silicate materials, advective transfer is commonly unimportant in the liquid region; this is not always the case in the vapor region. Volume change is commonly more important than heat of vaporization in determining the position of the liquid-vapor interface, assuring that the temperatures cannot be determined independently of pressures. Pressure increases reach a maximum near the leading edge of the thermal front and penetrate well into the isothermal region of the body. Mass flux is insensitive to the hydraulic properties of the half-space. ?? 1984.

Delaney, P.

1984-01-01

38

Topical and vapor toxicity of saturated fatty acids to the German cockroach (Dictyoptera: Blattellidae).  

PubMed

Topical and fumigant toxicity of saturated aliphatic fatty acids with chain lengths of C1 through C14 were determined against the German cockroach, Blattella germanica (L.). In the C1 to C11 series, topical toxicity (LD50 in milligram per adult male) ranged from 0.145 (C1) to 0.322 mg (C2). Toxicity declined dramatically with C12 and C14 acids whose LD50 values could not be calculated. The relative fumigation toxicity (LC50 in microliter per liter) of C1 through C5 acids was positively correlated with topical toxicity with values ranging from 6.159 (C3) to 12.302 microl/liter (C2). Fumigant toxicity decreased sharply with C6 (LC50 = 37.691 microl/liter) and there was no mortality of cockroaches exposed to vapors from C7 to C14 acids. The low fumigant toxicity of the C6 to C11 acids was correlated with their relatively low vapor pressure, but differences in diffusion of the vapors into the spiracles and subsequent passage to the target sites may have also been involved. PMID:24772558

Sims, Steven R; Balusu, Rammohan R; Ngumbi, Esther N; Appel, Arthur G

2014-04-01

39

Effect of capillary pressure on the approach to residual saturation  

Microsoft Academic Search

The approach to residual oil saturation during the immiscible displacement of oil as predicted by the multiphase Darcy equations is studied. It is well known that when the capillary pressure term is neglected, one arrives at the Buckley-Leverett formulation according to which the inlet face attains residual oil saturation instantaneously. This result may, however, be strongly influenced by the inclusion

T. S. Ramakrishnan; D. Wilkinson; M. M. Dias

1988-01-01

40

MODELING OF WHOLE FIELD VAPOR PRESSURE DURING REFLOW FOR FLIP CHIP BGA AND WIRE BOND PBGA PACKAGES  

Microsoft Academic Search

ABSTRACT In this paper, FEA models are built for both flip chip BGA (FCBGA) and wire bond PBGA packages to predict the moisture distribution, followed by the calculation of vapor pressure distribution in the package,using the micro- mechanics,approach,with consideration of the micro-void effect. Results show that the vapor pressure saturated much,faster than the moisture diffusion, and a near uniform vapor

Tong Yan Tee; Xue-jun Fan; Thiam Beng Lim

1999-01-01

41

Upscaling capillary pressure-saturation curves in heterogeneous porous media  

Microsoft Academic Search

Numerical models of flow in the vadose zone require capillary pressure-saturation relationships for the grid blocks discretizing the medium. However, the scale of these grid blocks is generally much larger than the sample scale at which capillary pressure-saturation relationships are measured. This study investigates the upscaling of capillary curves under static conditions of capillary-gravity equilibrium. The upscaling of capillary curves

A. J. Desbarats

1995-01-01

42

Upscaling Capillary Pressure-Saturation Curves in Heterogeneous Porous Media  

Microsoft Academic Search

Numerical models of flow in the vadose zone require capillary pressure-saturation relationships for the grid blocks discretizing the medium. However, the scale of these grid blocks is generally much larger than the sample scale at which capillary pressure-saturation relationships are measured. This study investigates the upscaling of capillary curves under static conditions of capillary-gravity equilibrium. The averaging regions are horizontal

A. J. Desbarats

1995-01-01

43

Vaporization Enthalpy and Vapor Pressure of Valproic Acid by Correlation Gas Chromatography  

E-print Network

Vaporization Enthalpy and Vapor Pressure of Valproic Acid by Correlation Gas Chromatography Joe A by correlation-gas chromatography. This resulted in a vaporization enthalpy, Hvap(298.15 K) of (74.8 ± 2.4) k at T/K = 298.15, both derived by correlation-gas chromatography. The measurement of vaporization

Chickos, James S.

44

On the propagation of a coupled saturation and pressure front  

SciTech Connect

Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

Vasco, D. W.

2010-12-01

45

High-accuracy measurements of the vapor pressure of ice referenced to the triple point  

NASA Astrophysics Data System (ADS)

vapor pressure of hexagonal (Ih) water ice was measured over the temperature range 175 K to 253.4 K and referenced to the value at the triple point of water. This experiment combined a highly accurate humidity generation system containing an ice-coated saturator (millikelvin-level temperature control) to provide humidified streams of nitrogen to a cavity-enhanced laser absorption spectrometer. The measured ice vapor pressures had relative standard uncertainties ranging from 0.4% to 0.7% over the entire temperature range. We demonstrate that these measurements validate thermodynamic correlations for ice vapor pressure based on integration of the Clapeyron equation. Moreover, they also indicate that some commonly used vapor pressure correlations are inaccurate and should be avoided.

Bielska, Katarzyna; Havey, Daniel K.; Scace, Gregory E.; Lisak, Daniel; Harvey, Allan H.; Hodges, Joseph T.

2013-12-01

46

Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier  

NASA Astrophysics Data System (ADS)

The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

2014-08-01

47

Notes on Vapor Pressure Equilibria Measurements  

NASA Astrophysics Data System (ADS)

After reading the article in this Journal (1), we would like to share our experience with a similar experiment based on an earlier article in this Journal (2). Freshman students at our institution use manometers and 24/40 ground-glass distillation apparatus (abandoned by our organic chemistry classes) to measure boiling points at reduced pressures. Distilled water and 2-methyl-1-propanol are typical liquids of interest. Students enter their collected data into an Excel template which generates graphs of P vs. T and log P vs 1/T to demonstrate the nonlinear and linear relationships that exist between vapor pressures and temperatures. The templates use the Clausius-Clapeyron equation to determine the normal boiling point and the enthalpy of vaporization of the liquid studies. The boiling point determined for water is 100 oC and for 2-methyl-1-propanol is 106 oC, within 2 o of the CRC Handbook data. We have found that the availability of state-of-the-art equipment need not limit the ability to teach and demonstrate fundamental principles. The Excel template (Macintosh) is available upon request domestically and for the cost of international postage for others. Literature Cited 1. Kidahl, N.; Berka, L. H. J. Chem. Educ. 1995, 72, 258. 2. Schaber, P. M. J. Chem. Educ. 1985, 62, 345.

Krieger, Albert G.; Henderson, John W.

1996-11-01

48

Pore scale mechanisms for enhanced vapor transport through partially saturated porous media  

NASA Astrophysics Data System (ADS)

Recent theoretical and experimental studies of vapor transport through porous media question the existence and significance of vapor transport enhancement mechanisms postulated by Philip and de Vries. Several enhancement mechanisms were proposed to rectify shortcomings of continuum models and to reconcile discrepancies between predicted and observed vapor fluxes. The absence of direct experimental and theoretical confirmation of these commonly invoked pore scale mechanisms prompted alternate explanations considering the (often neglected) role of transport via capillary connected pathways. The objective of this work was to quantify the specific roles of liquid bridges and of local thermal and capillary gradients on vapor transport at the pore scale. We considered a mechanistic pore scale model of evaporation and condensation dynamics as a building block for quantifying vapor diffusion through partially saturated porous media. Simulations of vapor diffusion in the presence of isolated liquid phase bridges reveal that the so-called enhanced vapor diffusion under isothermal conditions reflects a reduced gaseous diffusion path length. The presence of a thermal gradient may augment or hinder this effect depending on the direction of thermal relative to capillary gradients. As liquid phase saturation increases, capillary transport becomes significant and pore scale vapor enhancement is limited to low water contents as postulated by Philip and deVries. Calculations show that with assistance of a mild thermal gradient water vapor flux could be doubled relative to diffusion of an inert gas through the same system.

Shahraeeni, Ebrahim; Or, Dani

2012-05-01

49

46 CFR 154.451 - Design vapor pressure.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

2011-10-01

50

46 CFR 154.451 - Design vapor pressure.  

...2014-10-01 2014-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

2014-10-01

51

46 CFR 154.451 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

2013-10-01

52

46 CFR 154.451 - Design vapor pressure.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

2012-10-01

53

46 CFR 154.451 - Design vapor pressure.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

2010-10-01

54

Fuel Vapor Pressures and the Relation of Vapor Pressure to the Preparation of Fuel for Combustion in Fuel Injection Engines  

NASA Technical Reports Server (NTRS)

This investigation on the vapor pressure of fuels was conducted in connection with the general research on combustion in fuel injection engines. The purpose of the investigation was to study the effects of high temperatures such as exist during the first stages of injection on the vapor pressures of several fuels and certain fuel mixtures, and the relation of these vapor pressures to the preparation of the fuel for combustion in high-speed fuel injection engines.

Joachim, William F; Rothrock, A M

1930-01-01

55

Vapor pressure osmometry studies on buckminsterfullerene  

SciTech Connect

Vapor pressure osmometry has been employed in studies of solutions of buckminsterfullerene (C{sub 60}. Two aromatic solvents were selected in order to obtain solutions which would be as concentrated as possible. The number-average molecular weights M{sub n} of C{sub 60} determined by analysis of the data are 930 {+-} 5 g mol{sup {minus}1} in chlorobenzene and 700 {+-} 10 g mol{sup {minus}1} in toluene), so the M{sub n} obtained in chlorobenzene is unexpected. Both determinations were performed with the same batch of C{sub 60}, which was processed to yield material of very high purity. The amount of interstitial N{sub 2} was determined using an appropriate method. The role if interstitial molecules, solvents in the crystal lattice, solvent-fullerene complexes, C{sub 70}, and C{sub 60} dimers in these measurements will be discussed.

Honeychuck, R.V.; Cruger, T.W.; Milliken, J. [Naval Research Lab., Washington, DC (United States); [George Mason Univ., Fairfax, VA (United States)

1993-12-31

56

46 CFR 154.445 - Design vapor pressure.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST...Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type...

2011-10-01

57

46 CFR 154.438 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST...Equipment Independent Tank Type A § 154.438 Design vapor pressure. (a) If the surface of an independent tank...

2013-10-01

58

46 CFR 154.445 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST...Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type...

2013-10-01

59

46 CFR 154.445 - Design vapor pressure.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST...Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type...

2010-10-01

60

46 CFR 154.445 - Design vapor pressure.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST...Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type...

2012-10-01

61

46 CFR 154.438 - Design vapor pressure.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST...Equipment Independent Tank Type A § 154.438 Design vapor pressure. (a) If the surface of an independent tank...

2012-10-01

62

46 CFR 154.445 - Design vapor pressure.  

... 2014-10-01 2014-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST...Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type...

2014-10-01

63

On the Way to Determination of the Vapor-Pressure Curve of Pure Water  

NASA Astrophysics Data System (ADS)

The determination of the physical properties of pure water, especially the vapor-pressure curve of water, is one of the major issues identified by the Consultative Committee for Thermometry of the International Committee for Weights and Measures (CIPM) to improve the accuracy of the national references in humidity. At the present time the saturation-pressure data, corresponding to ice or liquid-vapor equilibrium, at low temperature are scarce and unreliable. This study presents new measurements of vapor and sublimation pressures of, respectively, water and ice, using a static apparatus. Prior to saturation-pressure measurements, the temperature and pressure sensors of the static apparatus were calibrated against reference gauges in use at the LNE- CETIAT laboratories. The effect of thermal transpiration has been studied. The explored temperature range lies between 250 K and 374 K, and the pressure range between 70 Pa and 105 Pa. An automatic data acquisition program was developed to monitor the pressure and temperature. The obtained results have been compared with available literature data. The preliminary uncertainty budget took into account several components: pressure measurements, temperature measurements, and environmental error sources such as thermal transpiration and hydrostatic correction.

Mokdad, S.; Georgin, E.; Mokbel, I.; Jose, J.; Hermier, Y.; Himbert, M.

2012-09-01

64

The hysteretic evapotranspiration - vapor pressure deficit relation  

NASA Astrophysics Data System (ADS)

Diurnal hysteresis between evapotranspiration (ET) and vapor pressure deficit (VPD) was reported in many ecosystems but justification for its onset and magnitude remain incomplete with biotic and abiotic factors invoked as possible explanations. To place these explanations within a mathematical framework, ';rate-dependent' hysteresis originating from a phase angle difference between periodic input and output time series is first considered. Lysimeter evaporation (E) measurements from wet bare soils and model calculations using the Penman equation demonstrate that the E-VPD hysteresis emerges without any biotic effects due to a phase angle difference (or time lag) between net radiation the main driver of E, and VPD. Modulations originating from biotic effects on the ET-VPD hysteresis were then considered. The phase angle difference representation earlier employed was mathematically transformed into a storage problem and applied to the soil-plant system. The transformed system shows that soil moisture storage within the root zone can produce an ET-VPD hysteresis prototypical of those generated by phase-angle differences. To explore the interplay between all the lags in the soil-plant-atmosphere system and phase angle differences among forcing and response variables, a detailed soil-plant-atmosphere continuum (SPAC) model was developed and applied to a grassland ecosystem. The results of the SPAC model suggest that the hysteresis magnitude depends on the radiation-VPD lag. The soil moisture dry-down simulations also suggest that modeled root water potential and leaf water potential are both better indicators of the hysteresis magnitude than soil moisture, suggesting that plant water status is the main factor regulating the hysteretic relation between ET and VPD. Hence, the genesis and magnitude of the ET-VPD hysteresis are controlled directly by both biotic factors and abiotic factors such as time lag between radiation and VPD originating from boundary layer processes. Measured eddy covariance evapotranspiration (ET) and vapor pressure deficit (VPD) time series normalized by their maximum values collected in a grassland ecosystem. The magnitude of the hysteresis is quantified as the area enveloped by the ET-VPD relation (Ahys). The arrows together with time ticks indicate the progression of the diurnal cycle from sunrise to sunset.

Zhang, Q.; Manzoni, S.; Katul, G. G.; Porporato, A. M.; Yang, D.

2013-12-01

65

Controlling the vapor pressure of a mercury lamp  

DOEpatents

The invention described herein discloses a method and apparatus for controlling the Hg vapor pressure within a lamp. This is done by establishing and controlling two temperature zones within the lamp. One zone is colder than the other zone. The first zone is called the cold spot. By controlling the temperature of the cold spot, the Hg vapor pressure within the lamp is controlled. Likewise, by controlling the Hg vapor pressure of the lamp, the intensity and linewidth of the radiation emitted from the lamp is controlled.

Grossman, Mark W. (Belmont, MA); George, William A. (Rockport, MA)

1988-01-01

66

Improved measurement of crude oil vapor pressure via PVT study methods  

SciTech Connect

A technical task force created by owner companies of the Trans-Alaska Pipeline System (TAPS) including BP Pipelines (Alaska), and Arco Transportation Alaska, Inc., and Alyeska Pipeline Service Company (APSC), the operator of TAPS, have investigated new technology for measuring the saturated liquid bubble point vapor pressure (BPVP) of crude oils. This technology is based on Pressure-Volume-Temperature (PVT) Cell study methods and consists of an on-line Vapor Pressure Analyzer (VPA) developed by Arco Oil & Gas Company and marketed by Fluid Data (TVP-1000), and a mercury-free automated PVT lab system (RUSKA 2370 Lab System) marketed by Ruska Instrument Corporation and modified to meet APSC requirements. In this methodology, the BPVP for the multicomponent fluid crude oil is defined and approximated by the intersection of the liquid compressibility and two phase lines on the isothermal pressure-volume (PV) curve for the fluid. The Task Force finds that this new technology provides saturated liquid bubble point vapor pressure values of TAPS crude oils which differ by 15 to 95 kPa from True Vapor Pressure (TVP) values obtained using API Publication 2517, Figure 18B-Equation for of Crude Oils With A Reid Vapor Pressure of 2-15 Pounds per Square Inch and corresponding RVP data from the crude oils tested. The range in difference between the BPVP and the TVP for each of five different TAPS crude oils tested was found to be due to differences in crude oil composition. 3 refs., 1 fig., 1 tab.

Roehner, R. [Alyeska Pipeline Service Co., Anchorage, AK (United States); Wetzel, G.; Stonestreet, W.; Lievios, J.; Reed, D.

1996-12-31

67

The Vaporization Enthalpies and Vapor Pressures of Some Primary Amines of Pharmaceutical Importance by Correlation Gas  

E-print Network

similar to amphetamine, is used medicinally as an appetite suppressant for patients who suffer from obesity.7 Tranylcypromine or trans-1-phenylcyclopropylamine, developed as an analogue of amphetamine the vaporization enthalpies and vapor pressures of a series of primary n-alkylamines including those of amphetamine

Chickos, James S.

68

Vapor Pressure of Caesium by the Positive Ion Method  

Microsoft Academic Search

The positive ion currents from pure tungsten filaments in saturated caesium vapor at bulb temperatures from -35°C to +73°C were measured for filament temperatures from 1000° to 1800°K. The results were corrected for the cooling effect of the leads and for photoelectric emission from the caesium film on the platinum deposited on the bulb which was used as an ion

John Bradshaw Taylor; Irving Langmuir

1937-01-01

69

Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid  

ERIC Educational Resources Information Center

This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

2007-01-01

70

Optimal determination of the vapor pressure critical exponent  

E-print Network

August 1977 Major Subject: Chemical Engineering OPTIMAL DETERMINATION OF THE VAPOR PRESSURE CRiTICAL EXPONENT A Thesis by CLIl FORJ) VAYNE NALTON Approved as to style and content by: (Head/o Department) ember) August 1977 ABSTRACT Optimal...

Walton, Clifford Wayne

2012-06-07

71

Development of a quasi-adiabatic calorimeter for the determination of the water vapor pressure curve.  

PubMed

Progress in the knowledge of the water saturation curve is required to improve the accuracy of the calibrations in humidity. In order to achieve this objective, the LNE-CETIAT and the LNE-CNAM have jointly built a facility dedicated to the measurement of the saturation vapor pressure and temperature of pure water. The principle is based on a static measurement of the pressure and the temperature of pure water in a closed, temperature-controlled thermostat, conceived like a quasi-adiabatic calorimeter. A copper cell containing pure water is placed inside a temperature-controlled copper shield, which is mounted in a vacuum-tight stainless steel vessel immersed in a thermostated bath. The temperature of the cell is measured with capsule-type standard platinum resistance thermometers, calibrated with uncertainties below the millikelvin. The vapor pressure is measured by calibrated pressure sensors connected to the cell through a pressure tube whose temperature is monitored at several points. The pressure gauges are installed in a thermostatic apparatus ensuring high stability of the pressure measurement and avoiding any condensation in the tubes. Thanks to the employment of several technical solutions, the thermal contribution to the overall uncertainty budget is reduced, and the remaining major part is mainly due to pressure measurements. This paper presents a full description of this facility and the preliminary results obtained for its characterization. PMID:22852731

Mokdad, S; Georgin, E; Hermier, Y; Sparasci, F; Himbert, M

2012-07-01

72

Apparatus of the Vapor-pressure Measurements for Natural Refrigerants  

NASA Astrophysics Data System (ADS)

An apparatus for measuring the vapor-pressures was newly designed and constructed in order to make the basic thermodynamic properties for environmentally acceptable refrigerants clear. The temperature of sample fluid was measured with 100? platinum resistance thermometer calibrated against ITS-90 using a 25? standard platinum resistance thermometer. With respect to the pressure measurement, two kinds of presure transducer were adopted. One is a diaphragm semi-conductor strain pressure transducer with the uncertainty of ±0.09%. This pressure transducer was calibrated against quartz crystal pressure transducer with the uncertainty of ±0.01% after every series of experiments. Another is a quartz crystal pressure transducer with the uncertainty of ±0.01%. A quartz crystal pressure transducer was calibrated against the dead weight pressure gauge and barometer. The vapor-pressures for R-32, R-134a, R-290 (propane), R-600a (iso-butane) and n-pentane were measured in the temperature range between273.15 and 323.15K. As the results of vapor-pressure measurements, the reliability of the experimental apparatus as well as the reproducibility of the experimental data were confirmed. In addition, coefficients of Antoine vapor pressure equation were determined from the experimental data. Normal boiling points for environmentally acceptable refrigerants were also determined with high accuracy.

Higuchi, Satoru; Higashi, Yukihiro

73

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Astrophysics Data System (ADS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; van Dresar, Neil T.; Lacovic, Raymond F.

74

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Technical Reports Server (NTRS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; Van Dresar, Neil T.; Lacovic, Raymond F.

1991-01-01

75

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Technical Reports Server (NTRS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet; a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency, with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurent requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; Vandresar, Neil T.; Lacovic, Raymond F.

1991-01-01

76

The Effect of Films on the Capillary Pressure - Saturation Relationship  

NASA Astrophysics Data System (ADS)

The hysteretic dependence of capillary pressure (Pc) on saturation (S) indicates that additional state variables are needed to describe multiphase flow behavior in porous media. Previous studies have shown that the observed hysteresis is a projection of a higher-dimensional surface that depends on interfacial area per volume, as an additional state variable. However, these studies have not addressed the affected of films on the Pc-S relationship. In this study, we use laser scanning confocal microscopy to image the three-dimensional (3D) fluid distributions of two immiscible fluids in a simple wedge-shaped channel. We find that entrained films of wetting phase affect the P-S relationship during both drainage and imbibition and that these extensions of the fluid-fluid interface increase the interaction among the wetting, non-wetting, and solid phases.
Smooth-walled and rough-walled wedge-shaped channels were fabricated using two different approaches: 1) two-photon polymerization by femtosecond laser and 2) broadband photolithography. Both techniques use UV-sensitive photoresist (SU-8) to construct an all-SU-8 micromodel containing a wedge-shaped channel that is 100 ?m wide at the outlet and 20 ?m wide at the inlet with a constant depth of 40 ?m. A Zeiss LSM 710 Confocal Microscope was used for image the water (wetting phase) and air (non-wetting phase) distributions within the micromodel. By labeling the wetting phase with a fluorophore (Alex Fluor-488 water solution 1%w.t.), the water-air interfaces are clearly visible in the confocal microscopy images. The samples were initially saturated with water. A series of drainage and imbibition cycles were performed by incrementing or decrementing the air pressure. At each pressure, the system was allowed to equilibrate and then a stack of scans in depth was collected to acquire the 3D fluid distribution for a given pressure. The confocal images were analyzed to extract the volume saturation of air and water, the curvature of the three-dimensional fluid-air interface, as well as the interfacial area per volume.
Hysteretic dependence of the capillary pressure (Pc) on the volume saturation (Sv) was observed even though the wedge-shaped channel has no complex geometry. The Pc - Sv hysteresis with and without films was compared. When films were present, higher capillary pressure was needed to drain the wetting phase. The film provided additional resistance during drainage and additional forces during imbibition.
Because Sv indicates the wetting phase volume variation, the energy ?E cost to move the interface was calculated from the Pc - Sv graph between pressure steps. The change in surface area ?A between pressure steps was calculated from the saturation Sv. Linear relationships were found between ?E and ?A for drainage and imbibition. The slopes of the ?E - ?A lines with film are higher than that without film, suggesting that the system expends additional energy to move fluid-fluid interfaces when films are present.
Acknowledgments: This research is supported by the National Science Foundation (0509759-EAR and 0911284-EAR).

Liu, Y.; Pyrak-Nolte, L. J.; Nolte, D. D.; Giordano, N. J.

2009-12-01

77

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2010-07-01

78

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2011-07-01

79

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2011-07-01

80

40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2014-07-01

81

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2013-07-01

82

40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2011-07-01

83

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2013-07-01

84

40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

2014-07-01

85

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2012-07-01

86

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2011-07-01

87

40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

2010-07-01

88

40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4a Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2010-07-01

89

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2014-07-01

90

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2014-07-01

91

40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2012-07-01

92

40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4a Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2013-07-01

93

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2014-07-01

94

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2013-07-01

95

40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4a Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2012-07-01

96

40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2010-07-01

97

40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4a Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2011-07-01

98

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2012-07-01

99

40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

2011-07-01

100

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2010-07-01

101

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2012-07-01

102

40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2013-07-01

103

40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

2012-07-01

104

40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

2013-07-01

105

40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.  

...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...2006 § 60.482-4a Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

2014-07-01

106

46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30...PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a...

2011-10-01

107

46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30...PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a...

2010-10-01

108

Fluid Phase Equilibria 243 (2006) 198205 Comment on "prediction of vapor pressures of solid organic  

E-print Network

of vapor pressures of solid organic compounds with a group contribution method" William E. Acree Jr gave satisfactory vapor pressure predictions for many organic compounds having vapor pressures well only for substituting into their predictive vapor pressure expression. The intent of this short

Chickos, James S.

109

46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30...PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a...

2013-10-01

110

46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30...PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a...

2012-10-01

111

46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.  

...2014-10-01 2014-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30...PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a...

2014-10-01

112

Evidence of Water Vapor in Excess of Saturation in the Atmosphere of Mars  

NASA Astrophysics Data System (ADS)

The vertical distribution of water vapor is key to the study of Mars’ hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth’s atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale.

Maltagliati, L.; Montmessin, F.; Fedorova, A.; Korablev, O.; Forget, F.; Bertaux, J.-L.

2011-09-01

113

Structural rearrangements in a lamellar diblock copolymer thin film during treatment with saturated solvent vapor  

PubMed Central

We have investigated the structural changes in thin films of lamellar poly(styrene-b-butadiene) diblock copolymers during treatment with saturated cyclohexane vapor, a solvent slightly selective for polybutadiene. Using real-time, in-situ grazing-incidence small-angle X-ray scattering (GISAXS), the swelling and the rearrangement of the lamellae were investigated with a time resolution of a few seconds, and the underlying processes on the molecular level were identified. After a few minutes in vapor, a transient state with a more well-defined and more long-range ordered lamellar orientation was encountered. Additional parallel lamellae formed which we attribute to the increased degree of coiling of the polymers in the swollen state. Eventually, the film became disordered. These changes are attributed to the increased mobility of the swollen polymers and the gradually decreasing segment-segment interaction parameter in the film as solvent is absorbed. PMID:20305742

Di, Zhenyu; Posselt, Dorthe; Smilgies, Detlef-M.; Papadakis, Christine M.

2010-01-01

114

Vapor Pressures and Vaporization, Sublimation, and Fusion Enthalpies of Some Fatty Acids  

E-print Network

.2 ± 7.1); erucic acid, (149.2 ± 7.1); and docosanoic acid (154.7 ± 7.3). A solid-solid transition, elaidic acid (C18H34O2, trans-9-octadecenoic acid), heneicosanoic acid (C21H42O2), erucic acid (C22H42O2Vapor Pressures and Vaporization, Sublimation, and Fusion Enthalpies of Some Fatty Acids Joe A

Chickos, James S.

115

Vaporizing high pressure fluids: Energy release comparisons  

SciTech Connect

This paper utilizes a method previously presented for estimating potential energy which might be released as a shock wave from sudden failure of vessels containing fluids at high pressure supercritical conditions. Data are presented for several fluids and comparisons are made illustrating the relative hazard of these fluids at a typical condition of high pressure and temperature.

Aggarwal, M.C. [Gannon Univ., Erie, PA (United States); Fryer, D.M. [High Pressure Engineering and Safety, Fairview, PA (United States)

1995-11-01

116

Evaporation rate and vapor pressure of selected polymeric lubricating oils.  

NASA Technical Reports Server (NTRS)

A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion.

Gardos, M. N.

1973-01-01

117

40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

2010-07-01

118

40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

2011-07-01

119

40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.  

... 2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

2014-07-01

120

40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

2012-07-01

121

40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

2013-07-01

122

Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment  

SciTech Connect

Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughness and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.

Kim, Jinhyun [Department of Chemistry, Kookmin University, Seoul 136-702 (Korea, Republic of)] [Department of Chemistry, Kookmin University, Seoul 136-702 (Korea, Republic of); Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr [Department of Chemistry, Kookmin University, Seoul 136-702 (Korea, Republic of)] [Department of Chemistry, Kookmin University, Seoul 136-702 (Korea, Republic of)

2012-10-15

123

Comparison of Different Techniques for Obtaining Capillary Pressure Data in the Low-Saturation Region  

Microsoft Academic Search

Capillary pressure data obtained by different methods in the low-saturation range are compared at the same values of the Leverett J function. The paper shows that in this range, saturations obtained by the mercury-injection method are significantly lower than saturations obtained by other standard methods. In this paper, further data characterizing the low-saturation region of the capillary pressure curve are

J. C. Melrose; J. R. Dixon; J. E. Mallinson

1994-01-01

124

Low-Temperature Vapor Pressures of Ethylene and Propane  

NASA Astrophysics Data System (ADS)

Mass spectra from the Galileo probe exhibit a cluster of peaks associated with two- and three-carbon hydrocarbons and two have been identified as ethylene and propane (Niemann et al. 1996). These molecules are important in the photochemical cycle of methane and are expected to be present in the atmospheres of the outer planets and Titan. To properly model related physical and chemical processes, e.g., cloud formation, it is important to have accurate thermodynamic data for these and other light hydrocarbons over the appropriate temperature and pressure range. The apparatus developed to determine the vapor pressures of gases and gas mixtures (Allen, Nelson, and Harris 1996) has been modified to provide a greater temperature range. Using this new system we have measured the vapor pressure of propane which, besides its role as a constituent in outer-planet atmospheres, is also a good calibration source since its vapor pressure is well determined over the temperature range of interest. The vapor pressure of ethylene was then determined. Little data are available for ethylene below its triple point (104 K); however we were able to extend our measurements past that point into the solid-phase region. The results of our vapor pressure measurements for these gases are presented along with comparisons with existing data sets. Allen, J.E., Jr., Nelson, R.N., Harris, B.C, Sr. 1996, B.A.A.S. underline {28}, 1157. Niemann, H.B. et al. 1996, Science 272, underline {842} and P.R. Mahaffy (private communication).

Nelson, R. N.; Allen, J. E., Jr.; Harris, B., Sr.

1997-07-01

125

Vapor pressures and gas-film coefficients for ketones  

USGS Publications Warehouse

Comparison of handbook vapor pressures for seven ketones with more recent literature data showed large differences for four of the ketones. Gas-film coefficients for the volatilization of these ketones from water determined by two different methods were in reasonable agreement. ?? 1987.

Rathbun, R.E.; Tai, D.Y.

1987-01-01

126

New class of compounds have very low vapor pressures  

NASA Technical Reports Server (NTRS)

Magnesium hexahydrate tetrachlorometallates are 50-volume-percent water, have a high melting point and possess a low vapor pressure. These new compounds are relatively noncorrosive, thermally stable, and water soluble but not hygroscopic. They may have potential applications as cooling fluids.

Angell, C. A.; Gruen, D. M.

1967-01-01

127

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

Microsoft Academic Search

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged form 500 to 950 daltons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to

G. R. Aiken; R. L. Malcolm

1987-01-01

128

46 CFR 154.426 - Design vapor pressure.  

Code of Federal Regulations, 2010 CFR

...SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3.55 psig) unless special approval...

2010-10-01

129

46 CFR 154.436 - Design vapor pressure.  

Code of Federal Regulations, 2010 CFR

...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge (3.55 psig) unless special...

2010-10-01

130

Distillation device supplies cesium vapor at constant pressure  

NASA Technical Reports Server (NTRS)

Distillation apparatus in the form of a U tube supplies small amounts of pure cesium vapor at constant pressure to a thermionic converter. The upstream leg of the U tube is connected to a vacuum pump to withdraw noncondensable impurities, the bottom portion serves as a reservoir for the liquid cesium.

Basiulis, A.; Shefsiek, P. K.

1968-01-01

131

Prediction of Vapor Pressures and Enthalpies of Vaporization Using a COSMO Solvation Shiang-Tai Lin, Jaeeon Chang, Shu Wang, William A. Goddard III, and  

E-print Network

Prediction of Vapor Pressures and Enthalpies of Vaporization Using a COSMO Solvation Model Shiang a general predictive method for vapor pressures and enthalpies of vaporization based on the calculation pressures and enthalpies of vaporization at the normal boiling temperature is found to be 76% and 4.81 k

Goddard III, William A.

132

Simultaneous Determination of Residual Saturation and Capillary Pressure Curves Utilizing the Ultracentrifuge  

Microsoft Academic Search

Residual saturation and capillary pressure curves are important for modelling reservoir and laboratory processes. Knowledge of the residual saturation curve is necessary to determine the ultimate production from a tertiary recovery process. Capillary pressure is required to interpret laboratory core floods and to describe multi-phase reservoir fluid flow. The ultracentrifuge provides a rapid means of determining capillary pressure and residual

M. J. King; A. J. Falzone; W. R. Cook; Jennings J. W; W. H. Mills

1986-01-01

133

Pressure (Or No Royal Road)  

ERIC Educational Resources Information Center

Discusses how difficult the various problems of pressure, partial pressure, gas laws, and vapor pressure are for students. Outlines the evolution of the concept of pressure, the gas equation for a perfect gas, partial pressures, saturated vapor pressure, Avogadro's hypothesis, Raoult's law, and the vapor pressure of ideal solutions. (JR)

Bradley, J.

1973-01-01

134

Vapor pressure of perfluoroalkylalkanes: the role of the dipole.  

PubMed

The vapor pressure of four liquid perfluoroalkylalkanes (CF3(CF2)n(CH2)mCH3; n = 3, m = 4,5,7; n = 5, m = 5) was measured as a function of temperature between 278 and 328 K. Molar enthalpies of vaporization were calculated from the experimental data, and the results were compared with data from the literature for the corresponding alkanes and perfluoroalkanes. The heterosegmented statistical associating fluid theory was used to interpret the results at the molecular level both with and without the explicit inclusion of the dipolar nature of the molecules. Additionally, ab initio calculations were performed for all perfluoroalkylalkanes studied to determine the dipole moment to be used in the theoretical calculations. We demonstrate that the inclusion of a dipolar term is essential for describing the vapor-liquid equilibria of perfluoroalkylalkanes. It is also shown that vapor-liquid equilibria in these compounds result from a subtle balance between dipolar interactions, which decrease the vapor pressure, and the relatively weak dispersive interactions between the hydrogenated and fluorinated segments. PMID:25526174

Morgado, Pedro; Das, Gaurav; McCabe, Clare; Filipe, Eduardo J M

2015-01-29

135

Controlling Vapor Pressure In Hanging-Drop Crystallization  

NASA Technical Reports Server (NTRS)

Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

Carter, Daniel C.; Smith, Robbie

1988-01-01

136

Low temperature measurement of the vapor pressures of planetary molecules  

NASA Technical Reports Server (NTRS)

Interpretation of planetary observations and proper modeling of planetary atmospheres are critically upon accurate laboratory data for the chemical and physical properties of the constitutes of the atmospheres. It is important that these data are taken over the appropriate range of parameters such as temperature, pressure, and composition. Availability of accurate, laboratory data for vapor pressures and equilibrium constants of condensed species at low temperatures is essential for photochemical and cloud models of the atmospheres of the outer planets. In the absence of such data, modelers have no choice but to assume values based on an educated guess. In those cases where higher temperature data are available, a standard procedure is to extrapolate these points to the lower temperatures using the Clausius-Clapeyron equation. Last summer the vapor pressures of acetylene (C2H2) hydrogen cyanide (HCN), and cyanoacetylene (HC3N) was measured using two different methods. At the higher temperatures 1 torr and 10 torr capacitance manometers were used. To measure very low pressures, a technique was used which is based on the infrared absorption of thin film (TFIR). This summer the vapor pressure of acetylene was measured the TFIR method. The vapor pressure of hydrogen sulfide (H2S) was measured using capacitance manometers. Results for H2O agree with literature data over the common range of temperature. At the lower temperatures the data lie slightly below the values predicted by extrapolation of the Clausius-Clapeyron equation. Thin film infrared (TFIR) data for acetylene lie significantly below the values predicted by extrapolation. It is hoped to bridge the gap between the low end of the CM data and the upper end of the TFIR data in the future using a new spinning rotor gauge.

Kraus, George F.

1989-01-01

137

Method and apparatus to measure vapor pressure in a flow system  

DOEpatents

The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.

Grossman, Mark W. (Belmont, MA); Biblarz, Oscar (Swampscott, MA)

1991-01-01

138

Vapor pressure measurements of bis(hydroxyethyl)piperazine and tris(hydroxyethyl)ethylenediamine  

SciTech Connect

Aqueous solutions of diethanolamine (DEA) are commonly used to remove acid gases (including hydrogen sulfide and carbon dioxide) from natural, refinery, and other industrial gas streams. Vapor pressures of bis(hydroxyethyl)piperazine (BHEP) and tris(hydroxyethyl)ethylenediamine (THEED) were measured in the temperature ranges of (412.65 to 507.15) and (372.55 to 472.35) K using the static and gas saturation techniques, respectively. The experimental data are well represented by the modified Antoine and the integrated Clausius-Clapeyron equations, and their coefficients are reported. The enthalpies of vaporization were found to be (62.76 {+-} 5.33) and (89.96 {+-} 3.91) kJ/mol for BHEP and THEED, respectively.

Abdi, M.A.; Meisen, A. [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Chemical and Bio-Resource Engineering] [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Chemical and Bio-Resource Engineering

1998-03-01

139

Solar radiation and water vapor pressure to forecast chickenpox epidemics.  

PubMed

The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure. PMID:25265908

Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

2014-09-30

140

A precise measurement method of each component gas pressures in rubidium vapor cell based on atom absorption spectra  

NASA Astrophysics Data System (ADS)

A new method and its principle are presented for measuring the each component gas pressures in Rubidium (Rb) by the analysis of absorption spectral profile. The experiment system is set up to obtain Rb absorption spectra. And then each component gas pressures in atom vapor cell is estimated. First, the relationships between transmittance of probe light, atom density and absorption cross section are introduced, and the factors which influence the absorption spectral profile and methods to measure gas pressures are given. Second, the frequency-dependence curves of transmittance and the absorption spectra are obtained through tuning the laser frequency through the Rb D1 transition. Finally, the gas pressures of Rb, N2 and He are achieved, through fitting absorption spectral profile referring to half-width and minimum transmittance value of absorption spectra. The experiment results show that gas pressures in Rb atom vapor cell can be accurately measured by absorption spectrometric methods, which will be helpful for the following study of atom vapor cell. The gas pressures of N2 and He measured by the experiments are well matched with design values. The Rb gas pressure is 30%~50% less than the saturated vapor pressure and the suppression may be due to the adsorption of the cell surfaces coated with octadecyltrichlorosilane (OTS) film.

Feng, Wei; Xiao, Guangzong; Liu, Xiaohu; Wang, Zhiguo; Yang, Kaiyong

2014-12-01

141

40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?  

Code of Federal Regulations, 2013 CFR

...do I determine the maximum HAP vapor pressure of my remediation material...do I determine the maximum HAP vapor pressure of my remediation material...must determine the maximum HAP vapor pressure of your remediation...

2013-07-01

142

40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?  

Code of Federal Regulations, 2012 CFR

...do I determine the maximum HAP vapor pressure of my remediation material...do I determine the maximum HAP vapor pressure of my remediation material...must determine the maximum HAP vapor pressure of your remediation...

2012-07-01

143

40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?  

Code of Federal Regulations, 2011 CFR

...do I determine the maximum HAP vapor pressure of my remediation material...do I determine the maximum HAP vapor pressure of my remediation material...must determine the maximum HAP vapor pressure of your remediation...

2011-07-01

144

40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?  

...I determine the maximum HAP vapor pressure of my remediation material? 63...I determine the maximum HAP vapor pressure of my remediation material? ...determine the maximum HAP vapor pressure of your remediation...

2014-07-01

145

Vapor pressure and vapor fractionation of silicate melts of tektite composition  

USGS Publications Warehouse

The total vapor pressure of Philippine tektite melts of approximately 70 per cent silica has been determined at temperatures ranging from 1500 to 2100??C. This pressure is 190 ?? 40 mm Hg at 1500??C, 450 ?? 50 mm at 1800??C and 850 ?? 70 mm at 2100?? C. Determinations were made by visually observing the temperature at which bubbles began to form at a constant low ambient pressure. By varying the ambient pressure, a boiling point curve was constructed. This curve differs from the equilibrium vapor pressure curve due to surface tension effects. This difference was evaluated by determining the equilibrium bubble size in the melt and calculating the pressure due to surface tension, assuming the latter to be 380 dyn/cm. The relative volatility from tektite melts of the oxides of Na, K, Fe, Al and Si has been determined as a function of temperature, total pressure arid roughly, of oxygen fugacity. The volatility of SiO2 is decreased and that of Na2O and K2O is increased in an oxygen-poor environment. Preliminary results indicate that volatilization at 2100??C under atmospheric pressure caused little or no change in the percentage Na2O and K2O. The ratio Fe3 Fe2 of the tektite is increased in ambient air at a pressure of 9 ?? 10-4 mm Hg (= 106.5 atm O2, partial pressure) at 2000??C. This suggests that tektites were formed either at lower oxygen pressures or that they are a product of incomplete oxidation of parent material with a still lower ferricferrous ratio. ?? 1964.

Walter, L.S.; Carron, M.K.

1964-01-01

146

A nonlinear regression analysis for estimating low-temperature vapor pressures and enthalpies of vaporization applied to refrigerants  

NASA Astrophysics Data System (ADS)

A new method is presented to extrapolate experimental vapor pressures down to the triple Point. The method involves a nonlinear regression analysis based on the Clausius Clapeyron equation and a simple relation for the enthalpy of vaporization Triple-point pressures and vapor pressures up to 0.1 0.2 MPa are estimated for R125, R32, R143a, R134a, R152a, R123, R124, and ammonia; they generally agree with available experimental data within their uncertainty, Equations for the enthalpy of vaporization which describe this property fairly well at low temperatures are obtained as a byproduct.

Tillner-Roth, R.

1996-11-01

147

Correlation Between Opacity and Surface Water Vapor Pressure Measurements at Rio Frio  

E-print Network

Correlation Between Opacity and Surface Water Vapor Pressure Measurements at Rio Frio M.A. Holdaway 1, 1996 Abstract We use the surface water vapor pressure measured by weather stations at 4060 m opacity. The surface water vapor pressure is inverted some 20% of the time at night and some 35

Groppi, Christopher

148

Measurements of the Vapor Pressure of Supercooled Water Using Infrared Spectroscopy  

E-print Network

Measurements of the Vapor Pressure of Supercooled Water Using Infrared Spectroscopy WILL CANTRELL 14 May 2007, in final form 6 December 2007) ABSTRACT Measurements are presented of the vapor pressure' data correspond to the vapor pressure of liquid water, not a mixture of liquid water and ice. Values

Kostinski, Alex

149

A HOMOGENIZATION TECHNIQUE FOR THE BOLTZMANN EQUATION FOR LOW PRESSURE CHEMICAL VAPOR DEPOSITION 1  

E-print Network

A HOMOGENIZATION TECHNIQUE FOR THE BOLTZMANN EQUATION FOR LOW PRESSURE CHEMICAL VAPOR DEPOSITION 1 the approach. The setup models low pressure chemical vapor deposition processes in the manufacturing. Low pressure chemical vapor deposition is used in the manufactur- ing of integrated circuits

Markowich, Peter A.

150

Surface structure, composition, and polarity of indium nitride grown by high-pressure chemical vapor deposition  

E-print Network

grown by high-pressure chemical vapor deposition have been studied. Atomic hydrogen cleaning produced and heterostructures--which can be accomplished by low- pressure metalorganic chemical vapor deposition MOCVD --the- rium vapor pressure of nitrogen during growth. This requires different approaches in growing structures

Dietz, Nikolaus

151

Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point  

E-print Network

Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point Allan the vapor pressure of heavy water (D2O) from its triple point to its critical point. This work takes temperatures are converted from ITS-90 to IPTS-68 before the vapor pressure is com- puted. The new formulation

Magee, Joseph W.

152

Absence of a vestigial vapor pressure paradox John F. Nagle1  

E-print Network

Absence of a vestigial vapor pressure paradox John F. Nagle1 and John Katsaras2 1 Department 26 January 1999 The enigmatic but much accepted vapor pressure paradox for oriented lipid bilayer that there is no vapor pressure paradox. The first result of this paper is to consider another degree of freedom

Nagle, John F.

153

Proximate capless annealing of GaAs using a controlled-excess As vapor pressure source  

E-print Network

Proximate capless annealing of GaAs using a controlled-excess As vapor pressure source J. M-excess arsenic vapor pressure has been studied. The excess arsenic vapor is provided by the thermal decomposition of InAs and is about 100 times larger than the arsenic pressure ofthermally decomposing Ga

Woodall, Jerry M.

154

Effect of Substrate Roughness on D Spacing Supports Theoretical Resolution of Vapor Pressure Paradox  

E-print Network

Effect of Substrate Roughness on D Spacing Supports Theoretical Resolution of Vapor Pressure with and provides experimental support for a recently proposed theoretical resolution of the vapor pressure paradox has been called the vapor pressure paradox (Rand and Parsegian, 1989). Resolving this paradox

Nagle, John F.

155

U.S. Strategic Petroleum Reserve Vapor Pressure Committee 2009 annual report  

Microsoft Academic Search

This report comprises an annual summary of activities under the U.S. Strategic Petroleum Reserve (SPR) Vapor Pressure Committee in FY2009. The committee provides guidance to senior project management on the issues of crude oil vapor pressure monitoring nd mitigation. The principal objectives of the vapor pressure program are, in the event of an SPR drawdown, to minimize the impact on

Ray Allen; Lisa Eldredge; Charles DeLuca; Patrick Mihalik; Julio Maldonado; David L. Lord; David Keith Rudeen; Gerard Berndsen

2010-01-01

156

Low vapor pressure braze alloys for thermionic energy converters  

NASA Technical Reports Server (NTRS)

Preliminary results in the use of some low-vapor-pressure braze alloys are reported; these are binary alloys of refractory metals (Th, Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, W) with vapor pressures below 0.1 nanotorr at 1500 K or 10 microtorr at 2000 K. The melting point minima or eutectics of the alloys range from 1510 K to above 3000 K. Melting points and surface wetting on a Ta base are given. Results are presented on brazing of Ir, LaB6, Nb, Re, W, and ZrO2 (with 22 wt % Zr) into a Ta base or a Nb-1% Zr base. The results are applicable in electrode screening programs for thermionic cesium diodes.

Bair, V. L.

1976-01-01

157

Vapor saturation of sodium: Key to unlocking the origin of chondrules  

NASA Astrophysics Data System (ADS)

Sodium saturation of the vapor coexisting with chondrules at their liquidus temperatures implies that vapor-condensed phase equilibrium was reached at those temperatures for all elements more refractory than sodium. In order to investigate the possibility that chondrules formed in impact-generated plumes, equilibrium calculations were applied to droplets made from two different target compositions. Combinations of dust enrichment and Ptot were found that lead to sodium saturation, and the subsequent chemical and mineralogical evolution of the droplets was explored at those conditions. If an impact on a body of CI composition caused instantaneous heating, melting and devolatilization of the target rock and ejection of a plume of gaseous, liquid and solid matter that mixed with residual nebular gas at conditions where 50% or 90% of the sodium was retained by the resulting droplets at their liquidus temperature, their mineralogical and chemical properties would strongly resemble those of Type II chondrules. If the droplets cooled and equilibrated with the mixture of residual nebular gas and their devolatilized water, sulfur and alkalis, the fayalite content of the olivine and the chemical compositions of the bulk droplets and their glasses would closely resemble those of Types IIA and IIAB chondrules at CI dust enrichments between 400× and 800×. For 50% sodium retention, the corresponding values of Ptot are 2 bars (for 400×) and 1 bar (for 800×). For 90% retention, they are 25 and 10 bars, respectively. If, instead, the target has an anhydrous, ordinary chondrite-like composition, called H', the ejected droplets are bathed in a gas mix consisting mostly of devolatilized sulfur and alkalis with residual nebular gas, a much more reducing plume. If the conditions were such that sodium were retained by the resulting droplets at their liquidus temperature, the fayalite contents of the olivine and the chemical compositions of the bulk droplets and their glasses would closely resemble those of Types IA and IAB chondrules at H' dust enrichments between 103× and 4 × 103×. For 90% sodium retention, the corresponding values of Ptot are 15 bars (for 103×) and 2 bars (for 4 × 103×). For 50% retention, they are 2 and 8 × 10-2 bars, respectively.

Fedkin, Alexei V.; Grossman, Lawrence

2013-07-01

158

Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium dioxide at high temperatures  

SciTech Connect

Thermodynamic functions of the gaseous species, thermodynamic functions of the condensed phase, and an oxygen-potential model have been combined to calculate the vapor pressures and vapor compositions in equilibrium with condensed-phase UO/sub 2-x/ for 1500 less than or equal to T less than or equal to 6000 K and 0 less than or equal to x less than or equal to 0.5. A method for extending the oxygen-potential model of Blackburn to the liquid region has been derived and evaluated. New thermodynamic functions of the UO/sub 2/ condensed phase have been derived from the best available data, including the heat capacity recommended by Fink.

Green, D.W.; Leibowitz, L.

1981-06-01

159

Stomatal responses to changes in vapor pressure deficit reflect tissue-specific differences in hydraulic conductance  

E-print Network

Stomatal responses to changes in vapor pressure deficit reflect tissue-specific differences, University of Minnesota, 1530 Cleveland Avenue North, St. Paul, MN 55108, USA ABSTRACT The vapor pressure to water vapor (gwv) in response to increasing D, limiting the ability of plants to assimilate carbon

Nippert, Jesse

160

Generation of high concentration aerosols from low vapor pressure compounds  

SciTech Connect

A generation system has been developed and used to produce exposure atmospheres containing respirable aerosols at high concentration (up to 5 mg of test compound per liter in air) from high boiling point, low vapor pressure compounds. Nine compounds were evaluated to demonstrate the effectiveness of the generation system. In each test at least 84% of the particles were in the respirable range (particle size 10 ..mu..m or less) with a mass median aerodynamic diameter of less than 3.2 ..mu..m. The system is easy to operate, reliable, versatile, provides reproducible results and is relatively inexpensive to construct.

Blank, T.L.; Velasquez, D.J.; Bechtel, C.L.; Roloff, M.V.

1987-10-01

161

Laboratory measurements of the microwave opacity and vapor pressure of sulfuric acid vapor under simulated conditions for the middle atmosphere of Venus  

NASA Technical Reports Server (NTRS)

Microwave absorption measurements at wavelengths of 13.4 and 3.6 cm were made in gaseous H2SO4 in a CO2 atmosphere under simulated conditions for the Venus middle atmosphere. The results suggest that abundances of gaseous H2SO4 on the order of 15-30 ppm could account for the absorption observed by radio occultation measurements at these wavelengths. They also imply that such abundances would correspond to saturation vapor pressure existing at or above the 46-48-km range, which correlates with the observed cloud base.

Steffes, P. G.

1985-01-01

162

Improved scaling technique for two-phase pressure—saturation relationships  

Microsoft Academic Search

Current methods of scaling imbibition and drainage pressure-saturation data scale the capillary pressure head using ratios of surface tension, constant intrinsic contact angle, fluid density difference and bubbling pressure. These methods are applicable to scaling either the main drainage or imbibition curve for different fluid pairs. However, for a given fluid pair, scaling of the drainage to the imbibition curve

D. A. Steffy; D. A. Barry; C. D. Johnston

1997-01-01

163

Effect of pressure on the electrical resistivity of water-saturated crystalline rocks  

Microsoft Academic Search

Electrical r.esistivity of eight igneous rocks and two crystalline limestones was measured at pressures to 10 kb. The rocks were saturated with tap water or salt solution, and the pore pressure was maintained near zero. The dependence of resistivity on temperature, porosity, and pore fluid salinity suggested that conduction was primarily electrolytic through- out the .entire pressure range, even though

W. F. Brace; A. S. Orange; T. R. Madden

1965-01-01

164

46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia...153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7...

2013-10-01

165

46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia...153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7...

2012-10-01

166

46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia...153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7...

2010-10-01

167

46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).  

...2014-10-01 2014-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia...153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7...

2014-10-01

168

46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia...153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7...

2011-10-01

169

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes from C78 to C92 at T ) 298.15 K by  

E-print Network

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes and vapor pressures of the n-alkanes from T ) (298.15 to 540) K for heneicosane to dononacontane. The vapor" extended corresponding states principle (CSP) which uses n-alkane input parameters based on the works

Chickos, James S.

170

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes from C40 to C76 at T ) 298.15 K by  

E-print Network

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes in combination with earlier work to evaluate the vaporization enthalpies and vapor pressures of these n-alkanes as the number of carbon atoms exceeds sixty. Introduction The n-alkanes serve as excellent standards

Chickos, James S.

171

Precision ozone calibration system based on vapor pressures of ozone  

NASA Technical Reports Server (NTRS)

A precision ozone calibration system for stratospheric research has been developed and evaluated. Vapor pressures above solid ozone are mixed with a carrier gas (N2) to produce stratospheric ozone mixing ratios at total pressures of 1 to cover 20 torr. The uncertainty in the ozone mixing ratios is approximately + or - 1.5 percent, the stability of ozone is + or - 0.3 percent. Experiments to be calibrated may sample the gas mixture over a wide range of flow rates; the maximum throughput of gas with corrections of less than 1 percent to ozone is about 200 torr 1/min. A mass spectrometer system continuously monitors the purity and stability of the N2-O3 gas mixture.

Mauersberger, K.; Hanson, D.; Morton, J.

1987-01-01

172

Selective Growth of Straight Carbon Nanotubes by Low-Pressure Thermal Chemical Vapor Deposition  

E-print Network

Selective Growth of Straight Carbon Nanotubes by Low-Pressure Thermal Chemical Vapor Deposition) were grown by low-pressure thermal chemical vapor deposition using pure ethylene. It was found preferentially bridged between Fe nanoparticles under a low pressure of 100 Pa. Moreover, utilizing this method

Hasegawa, Shuji

173

HIGH PRESSURE VAPOR TRANSPORT OF ZnGeP 2 : II. THREEDIMENSIONAL SIMULATION OF GASDYNAMICS UNDER  

E-print Network

HIGH PRESSURE VAPOR TRANSPORT OF ZnGeP 2 : II. THREE­DIMENSIONAL SIMULATION OF GASDYNAMICS UNDER pressure vapor transport (HPVT) of compound semiconductors is modeled. The modeling is for the growth of II Pascals pressure. Effects of density variations on p­polarized reflectance spectroscopy are also examined

174

40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2010-07-01

175

46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false High and low vapor pressure protection for tankships-T/ALL...Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL...collection system must be fitted with a pressure-sensing device, located as...

2013-10-01

176

40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2013-07-01

177

46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.  

...2014-10-01 false High and low vapor pressure protection for tankships-T/ALL...Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL...collection system must be fitted with a pressure-sensing device, located as...

2014-10-01

178

40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2012-07-01

179

40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.  

...2014-07-01 2014-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2014-07-01

180

40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2010-07-01

181

40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.  

...2014-07-01 2014-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2014-07-01

182

40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2013-07-01

183

40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2011-07-01

184

40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2012-07-01

185

40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

2011-07-01

186

Determination of the vapor pressures of moth sex pheromone components by a gas chromatographic method  

Microsoft Academic Search

The vapor pressures of decyl acetate, five decenyl acetate isomers, (Z)-7-dodecenyl acetate, and (Z)-9-tetradecenyl acetate have been determined at three to six temperatures in the interval 25–45 °C by a gas Chromatographic method suitable for accurate measurements of the low vapor pressures of moth sex pheromone components at biologically relevant temperatures. The vapor pressure values at 30.5 °C are 3.80

Anne-Marie Olsson; Jan Åke Jönsson; Bernt Thelin; Tommy Liljefors

1983-01-01

187

Measurement of equilibrium elemental vapor pressures using x-ray induced fluorescense.  

SciTech Connect

X-ray induced fluorescence is demonstrated as a novel and fast method for measuring vapor pressures at high temperatures and high pressures. As such, it is an excellent complement to the effusion method, which is limited to lower pressures. High-energy synchrotron radiation was used to measure the total densities of Dy in the equilibrium vapor over condensed DyI{sub 3} and Tm in the equilibrium vapor over condensed TmI{sub 3}. Corresponding vapor pressures were determined with measured vapor cell temperatures across a range of vapor pressures of nearly three orders of magnitude, from less than 10{sup 2} Pa to more than 10{sup 4} Pa. Individual data points were obtained in time periods ranging from 10 to 30 s each.

Curry, J. J; Henins, A.; Estupinan, E. G.; Lapatovich, W. P.; Shastri, S. D. (X-Ray Science Division); (NIST); (Osram Sylvania, Inc.)

2011-04-29

188

Condensation of supersaturated vapors. X. Pressure and nonideal gas effects  

NASA Astrophysics Data System (ADS)

Calculations of temperatures and supersaturations in nucleation experiments often include the assumption that all gases are ideal and they ignore the increase in vapor pressure due to the presence of noncondensible gases. Regardless of experimental technique, such assumptions can lead to substantial errors when comparing experiment to theory, especially when included in only one or the other. To demonstrate these effects, the procedures for calculating the temperatures and supersaturations in thermal diffusion cloud chambers are examined in detail. Nonideal gas effects do alter them; however, these effects also alter the rates calculated by nucleation theory and the effect is larger on nucleation theory than on the analysis of the experimental data. Due to the presence of noncondensible gases there also is a Poynting type effect, but it very nearly cancels in thermal diffusion cloud chambers when included consistently in both theory and experiment. An additional effect which arises only in nucleation theory is the nonzero compressibility of the critical nuclei. The net result (for n-nonane), when these effects are included consistently in both experiment and theory, is to reduce the temperature dependence of the multiplicative correction to theory necessary for agreement with experiment. None of these effects account for the previously observed apparent decrease in nucleation rate with increasing total pressure. Also critically examined are the uncertainties in the transport properties used to calculate the chamber profiles. Of particular interest is the uncertainty in the thermal diffusion factor which changes systematically with composition and thus with total pressure.

Fisk, Jeffery A.; Katz, Joseph L.

1996-06-01

189

The vapor pressures of solid and liquid ozone  

NASA Technical Reports Server (NTRS)

Vapor pressures of solid and liquid ozone have been measured over a temperature range 87 to below 66 K. The experiment was performed under flow conditions, and the gas was analyzed by a precision mass spectrometer system. In the range of solid ozone two forms, supercooled and crystalline ozone, were found. A least-square fit of the data for crystalline ozone resulted in the equation log P(torr) = A + B/T, where A = 10.460 and B = -1021.6. The estimated uncertainty of the data is + or - 1.0 percent. A triple-point temperature of 79.6 + or - 0.3 K was found where supercooled and crystalline ozone data intersect.

Hanson, David; Mauersberger, Konrad

1986-01-01

190

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

USGS Publications Warehouse

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged from 500 to 950 dallons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to be relatively monodisperse from radii of gyration measurements determined by small angle x-ray scattering. THF affords greater precision and accuracy than H2O in VPO measurements, and was found to be a suitable solvent for the determination of molecular weight of aquatic fulvic acid because it obviates the dissociation problem. An inverse correlation was observed with these samples between the concentration of Ca++ and Mg++ in the river water and the radii of gyration and molecular weights of the corresponding fulvic acid samples. ?? 1987.

Aiken, G.R.; Malcolm, R.L.

1987-01-01

191

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

SciTech Connect

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged form 500 to 950 daltons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to be relatively monodisperse from radii of gyration measurements determined by small angle x-ray scattering. THF affords greater precision and accuracy than H/sub 2/O in VPO measurements, and was found to be a suitable solvent for the determination of molecular weight of aquatic fulvic acid because it obviates the dissociation problem. An inverse correlation was observed with these samples between the concentration of Ca/sup + +/ and Mg/sup + +/ in the river water and the radii of gyration and molecular weights of the corresponding fulvic acid samples.

Aiken, G.R.; Malcolm, R.L.

1987-08-01

192

Analysis of the saturation phenomena of the neutralization rate of positively charged 218Po in water vapor.  

PubMed

Generally, 88% of the freshly generated 218Po ions decayed from 222Rn are positively charged. These positive ions become neutralized by recombination with negative ions, and the main source of the negative ions is the OH- ions formed by radiolysis of water vapor. However, the neutralization rate of positively charged 218Po versus the square root of the concentration of H2O will be a constant when the concentration of H2O is sufficiently high. Since the electron affinity of the hydroxyl radical formed by water vapor is high, the authors propose that the hydroxyl radical can grab an electron to become OH-. Because the average period of collision with other positively charged ions and the average life of the OH- are much longer than those of the electron, the average concentration of negative ions will grow when the water vapor concentration increases. The authors obtained a model to describe the growth of OH- ions. From this model, it was found that the maximum value of the OH- ion concentration is limited by the square root of the radon concentration. If the radon concentration is invariant, the OH- ion concentration should be approximately a constant when the water vapor concentration is higher than a certain value. The phenomenon that the neutralization rate of positively charged 218Po versus the square root of the water vapor concentration will be saturated when the water vapor concentration is sufficiently high can be explained by this mechanism. This mechanism can be used also to explain the phenomenon that the detection efficiency of a radon monitor based on the electrostatic collection method seems to be constant when the water vapor concentration is high. PMID:25068963

Tan, Yanliang; Xiao, Detao; Shan, Jian; Zhou, Qingzhi; Qu, Jingnian

2014-09-01

193

Scaling Capillary Pressure Head - Saturation Relationships for Saprolite: Correction for Uncertainty Introduced by Pressure Cell Measurements on Tall Columns  

Microsoft Academic Search

Dense non-aqueous phase liquids (DNAPL's) are important contaminants at many hazardous waste disposal sites. Relatively little information is available on DNAPL behavior in heterogeneous porous media such as fractured saprolite. We measured air-water and FluorinertTM (a non-toxic DNAPL surrogate)-water capillary pressure head (hc)-saturation (S) relationships close to saturation on an 18-cm long by 10-cm diameter undisturbed column of fractured shale

E. Perfect; L. McKay; S. Driese; J. Dane; G. Kammerer

2002-01-01

194

Virtual Refrigerant Pressure Sensors for Use in Monitoring and Fault Diagnosis of Vapor-Compression Equipment  

Microsoft Academic Search

Refrigerant pressures are critical measurements for monitoring, control, diagnostics, and optimization of vapor compression cycle equipment. Direct refrigerant pressure measuring practices are expensive and more than often problematic. This paper describes a method, termed virtual pressure sensing, wherein refrigerant pressure values are indirectly derived from low-cost temperature sensors that can be surface-mounted. In this manner, physical pressure sensors are eliminated

Haorong Li; James E. Braun

2009-01-01

195

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

...Industry for which Construction, Reconstruction, or Modification Commenced After January 5, 1981, and on or Before November 7, 2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure...

2010-07-01

196

Vapor pressure dependence of spectral width of EIT in Lambda-level cesium molecular system  

E-print Network

We have studied electromagnetically induced transparency (EIT) in diatomic cesium molecules in a vapor cell by using tunable diode lasers. We have observed a sub-natural Lambda-resonance in an absorption molecular band at different cesium vapor pressures. The width of the EIT resonance shows a linear dependence on cesium vapor pressure. Narrow Lambda-resonances in molecules can be used as frequency references for femtosecond laser frequency combs.

Hui Chen; Hebin Li; Yuri V. Rostovtsev; Mikhail A. Gubin; Vladimir A. Sautenkov; Marlan O. Scully

2009-02-16

197

OPTIMAL DESIGN OF A HIGH PRESSURE ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION REACTOR  

E-print Network

OPTIMAL DESIGN OF A HIGH PRESSURE ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION REACTOR K.J. BACHMANN simulations as a fundamental design tool in developing a new prototype high pressure organometallic chemical vapor deposition (HPOMCVD) reactor for use in thin film crystal growth. The advantages of such a reactor

198

Method and apparatus to measure vapor pressure in a flow system  

DOEpatents

The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process. 2 figures.

Grossman, M.W.; Biblarz, O.

1991-10-15

199

Analysis of crude oil vapor pressures at the U.S. Strategic Petroleum Reserve.  

SciTech Connect

Crude oil storage caverns at the U.S. Strategic Petroleum Reserve (SPR) are solution-mined from subsurface salt domes along the U.S. Gulf Coast. While these salt domes exhibit many attractive characteristics for large-volume, long-term storage of oil such as low cost for construction, low permeability for effective fluids containment, and secure location deep underground, they also present unique technical challenges for maintaining oil quality within delivery standards. The vapor pressures of the crude oils stored at SPR tend to increase with storage time due to the combined effects of geothermal heating and gas intrusion from the surrounding salt. This presents a problem for oil delivery offsite because high vapor-pressure oil may lead to excessive atmospheric emissions of hydrocarbon gases that present explosion hazards, health hazards, and handling problems at atmospheric pressure. Recognizing this potential hazard, the U.S. Department of Energy, owner and operator of the SPR, implemented a crude oil vapor pressure monitoring program that collects vapor pressure data for all the storage caverns. From these data, DOE evaluates the rate of change in vapor pressures of its oils in the SPR. Moreover, DOE implemented a vapor pressure mitigation program in which the oils are degassed periodically and will be cooled immediately prior to delivery in order to reduce the vapor pressure to safe handling levels. The work described in this report evaluates the entire database since its origin in 1993, and determines the current levels of vapor pressure around the SPR, as well as the rate of change for purposes of optimizing both the mitigation program and meeting safe delivery standards. Generally, the rate of vapor pressure increase appears to be lower in this analysis than reported in the past and, problematic gas intrusion seems to be limited to just a few caverns. This being said, much of the current SPR inventory exceeds vapor pressure delivery guidelines and must be degassed and cooled in order to meet current delivery standards.

Rudeen, David Keith (GRAM, Inc., Albuquerque, NM); Lord, David L.

2005-08-01

200

The Observed Relationship Between Water Vapor and Ozone in the Tropical Tropopause Saturation Layer and the Influence of Meridional Transport  

NASA Technical Reports Server (NTRS)

We examine balloonsonde observations of water vapor and ozone from three Ticosonde campaigns over San Jose, Costa Rica [10 N, 84 W] during northern summer and a fourth during northern winter. The data from the summer campaigns show that the uppermost portion of the tropical tropopause layer between 360 and 380 K, which we term the tropopause saturation layer or TSL, is characterized by water vapor mixing ratios from proximately 3 to 15 ppmv and ozone from approximately 50 ppbv to 250 ppbv. In contrast, the atmospheric water vapor tape recorder at 380 K and above displays a more restricted 4-7 ppmv range in water vapor mixing ratio. From this perspective, most of the parcels in the TSL fall into two classes - those that need only additional radiative heating to rise into the tape recorder and those requiring some combination of additional dehydration and mixing with drier air. A substantial fraction of the latter class have ozone mixing ratios greater than 150 ppbv, and with water vapor greater than 7 ppmv this air may well have been transported into the tropics from the middle latitudes in conjunction with high-amplitude equatorial waves. We examine this possibility with both trajectory analysis and transport diagnostics based on HIRDLS ozone data. We apply the same approach to study the winter season. Here a very different regime obtains as the ozone-water vapor scatter diagram of the sonde data shows the stratosphere and troposphere to be clearly demarcated with little evidence of mixing in of middle latitude air parcels.

Selkirk, Henry B.; Schoeberl, M. R.; Olsen, M. A.; Douglass, A. R.

2011-01-01

201

Low Pressure Metal-Organic Vapor Phase Epitaxy  

NASA Astrophysics Data System (ADS)

A comprehensive investigation of ZnCdS grown on GaAs by the low pressure metal-organic vapor phase epitaxy (MOVPE) technique has been conducted. Optimization, growth characteristics, film properties, solid-vapor equilibrium and device applications are key issues that have been addressed. The Taguchi method or design of experiments (DOE) approach is taken to determine the effects of process parameters on the crystalline quality of epilayers. Its main advantage over the standard methodology of changing one-factor-at -a-time is the reduction of experimental runs needed to obtain the same precision of information. In addition, DOE can statistically evaluate significance of multi-parameter interactions. Thin ZnCdS films have been grown on (100) and (111) oriented GaAs substrates using diethyl zinc (DEZn), dimethyl cadmium (DMCd) and H_2S. The lowest reported full width at half maximum of peaks obtained from X-ray diffraction spectra has been obtained using this chemistry. Critical process parameters and their setpoints have also been identified that influence the desirable 2-dimensional and undesirable 3-dimensional growth. A nucleation/growth mechanism is presented to explain the preferential initiation of one growth mode over the other. Other growth characteristics including flow mechanics, film thickness uniformity, defect density, crystal structure, solid phase composition and optical purity have been studied as a function of growth parameters. The general growth characteristics highly influence the optical, physical and electrical properties of ZnCdS. The bandgap energy and complex refractive index have been measured by reflectometry and ellipsometry, respectively. Thermal expansion coefficients have been calculated from lattice constant changes at various temperatures. In-situ doping studies have also been performed to determine the maximum electron and hole concentrations. A simple model based on the regular solution approach was developed to explain the solid-vapor equilibrium distribution. For the first time, the interaction parameters for binary II -VI compounds were calculated from Stringfellow's delta lattice parameter model based solely on material properties of II-VI compounds. The results show a good fit to experimental data across a wide range of temperature values. The measured properties of ZnCdS have been used in theoretical calculations of double heterostructure lasers. The complex refractive indices are needed to evaluate the optical confinement of a symmetric three-layer slab waveguide: ZnCdS/ZnSe/ZnCdS. The relationship between the active layer thickness and optical confinement have also been investigated. Bandgap energies along with electron affinities have been used to determine the carrier confinement. Calculations based on photothreshold values confirm these results.

Cho, Joe Sung

202

A new ozone standard - The vapor pressure of ozone at liquid argon temperatures  

NASA Technical Reports Server (NTRS)

The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (-185.9 C) an ozone pressure of 0.0405 torr was obtained with an accuracy of + or - 1.5 percent. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone studies.

Mauersberger, K.; Hanson, D.; Morton, J.

1985-01-01

203

Comparison of average and point capillary pressure-saturation functions determined by steady-state centrifugation  

SciTech Connect

The capillary pressure-saturation function can be determined from centrifuge drainage experiments. In soil physics, the data resulting from such experiments are usually analyzed by the 'averaging method.' In this approach, average relative saturation, , is expressed as a function of average capillary pressure, <{psi}>, i.e., (<{psi}>). In contrast, the capillary pressure-saturation function at a physical point, i.e., S({psi}), has been extracted from similar experiments in petrophysics using the 'integral method.' The purpose of this study was to introduce the integral method applied to centrifuge experiments to a soil physics audience and to compare S({psi}) and (<{psi}>) functions, as parameterized by the Brooks-Corey and van Genuchten equations, for 18 samples drawn from a range of porous media (i.e., Berea sandstone, glass beads, and Hanford sediments). Steady-state centrifuge experiments were performed on preconsolidated samples with a URC-628 Ultra-Rock Core centrifuge. The angular velocity and outflow data sets were then analyzed using both the averaging and integral methods. The results show that the averaging method smoothes out the drainage process, yielding less steep capillary pressure-saturation functions relative to the corresponding point-based curves. Maximum deviations in saturation between the two methods ranged from 0.08 to 0.28 and generally occurred at low suctions. These discrepancies can lead to inaccurate predictions of other hydraulic properties such as the relative permeability function. Therefore, we strongly recommend use of the integral method instead of the averaging method when determining the capillary pressure-saturation function by steady-state centrifugation. This method can be successfully implemented using either the van Genuchten or Brooks-Corey functions, although the latter provides a more physically precise description of air entry at a physical point.

Cropper, Clark [University of Tennessee, Knoxville (UTK); Perfect, Edmund [ORNL; van den Berg, Dr. Elmer [University of Tennessee, Knoxville (UTK); Mayes, Melanie [ORNL

2010-01-01

204

The hysteretic evapotranspiration—Vapor pressure deficit relation  

NASA Astrophysics Data System (ADS)

hysteresis between evapotranspiration (ET) and vapor pressure deficit (VPD) was reported in many ecosystems, but justification for its onset and magnitude remains incomplete with biotic and abiotic factors invoked as possible explanations. To place these explanations within a holistic framework, the occurrence of hysteresis was theoretically assessed along a hierarchy of model systems where both abiotic and biotic components are sequentially added. Lysimeter evaporation (E) measurements and model calculations using the Penman equation were used to investigate the effect of the time lag between net radiation and VPD on the hysteresis in the absence of any biotic effects. Modulations from biotic effects on the ET-VPD hysteresis were then added using soil-plant-atmosphere models of different complexities applied to a grassland ecosystem. The results suggest that the hysteresis magnitude depends on the radiation-VPD lag, while the plant and soil water potentials are both key factors modulating the hysteretic ET-VPD relation as soil moisture declines. In particular, larger hysteresis magnitude is achieved at less negative leaf water potential, root water potential, and soil water potential. While plant hydraulic capacitance affects the leaf water potential-ET relation, it has negligible effects on the ET-VPD hysteresis. Therefore, the genesis and magnitude of the ET-VPD hysteresis are controlled directly by both abiotic factors such as soil water availability, biotic factors (leaf and root water potentials, which in turn depend on soil moisture), and the time lag between radiation and VPD.

Zhang, Quan; Manzoni, Stefano; Katul, Gabriel; Porporato, Amilcare; Yang, Dawen

2014-02-01

205

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

Microsoft Academic Search

Few measurements of H2SO4 vapor pressure have been made for sulfuric acid in the temperature and concentration ranges of atmospheric interest because of the very low pressures involved (below 10-4Pa, or 10-6torr); no such measurements appear to have been made for sulfuric acid solutions neutralized with ammonia. This work presents measurements of H2SO4 vapor pressure for aqueous sulfuric acid solutions

James J. Marti; Anne Jefferson; Xiao Ping Cai; Chad Richert; Peter H. McMurry; Fred Eisele

1997-01-01

206

Pluto's atmosphere - Models based on refraction, inversion, and vapor-pressure equilibrium  

NASA Technical Reports Server (NTRS)

Viking spacecraft radio-occultation measurements indicate that, irrespective of substantial differences, the polar ice cap regions on Mars have inversions similar to those of Pluto, and may also share vapor pressure equilibrium characteristics at the surface. This temperature-inversion phenomenon occurs in a near-surface boundary layer; surface pressure-temperature may correspond to the vapor-pressure equilibrium with CH4 ice, or the temperature may be slightly higher to match the value derived from IRAS data.

Eshleman, Von R.

1989-01-01

207

PEO/CHCl3: Crystallinity of the polymer and vapor pressure of the solvent - Equilibrium and non-equilibrium phenomena -  

E-print Network

Vapor pressures were measured for the system chloroform/polyethylene oxide (peo, weight average molar mass = 1000 kg/mol) at 25 degrees centigrade as a function of the weight fraction w of the polymer by means of a combination of head space sampling and gas chromatography. The establishment of thermodynamic equilibria was assisted by employing thin polymer films. The degrees of crystallinity alpha of the pure peo and of the solid polymer contained in the mixtures were determined via dsc. An analogous degree of polymer insolubility, beta, was calculated from the vapor pressures measured in this composition range. The experiments demonstrate that both quantities and their concentration dependence are markedly affected by the particular mode of film preparation. These non-equilibrium phenomena are discussed in terms of frozen local and temporal equilibria, where differences between alpha and beta are attributed to the occlusion of amorphous material within crystalline domains. Equilibrium information was obtained from two sources, namely from the vapor pressures in the absence of crystalline material (gas/liquid) and from the saturation concentration of peo (liquid/solid). The thermodynamic consistency of these data is demonstrated using a new approach that enables the modeling of composition dependent interaction parameters by means of two adjustable parameters only.

A. KHassanova; B. A. Wolf

2003-04-16

208

MODEL FOR HYSTERETIC CONSTITUTIVE RELATIONS GOVERNING MULTIPHASE FLOW. 1. SATURATION-PRESSURE RELATIONS  

EPA Science Inventory

In these companion papers, a general theoretical model is presented for the description of functional relationships between relative permeability k, fluid saturation S, and pressure P in two- or three-phase (e.g., air-water or air-oil-water) porous media systems subject to arbitr...

209

Pressure-Saturation Effects from AVO Attributes in CO2 Monitoring of Weyburn Reservoir, Saskatchewan, Canada  

NASA Astrophysics Data System (ADS)

In order to measure pore-pressure and saturation effects due to CO2 injection, amplitude variation with offset (AVO) could be a most valuable discriminator. The AVO technique is applied to monitoring the Weyburn reservoir, located in southeast Saskatchewan, using 3D/3C surface seismic datasets. A baseline (1999) and two monitor surveys (2001 and 2002) acquired by EnCana as part of the International Energy Agency GHG Weyburn-Midale CO2 Monitoring and Storage Project are included in this study. Two-term linear AVO attributes including the intercept (I), gradient (G), S-wave reflectivity (I-G)/2 and I+G are derived. Attribute I - G is shown to be most sensitive to pressure variations, and I + G - to CO2 saturation. In addition, several secondary attributes based on statistical distributions of (I, G) values are also examined. The time-lapse AVO attributes indicate areas of pore-pressure and potentially CO2 saturation variations between the horizontal injection wells. The results indicate that AVO technology allows estimating reservoir pressure and fluid saturation variations from time-lapse seismic data.

Gao, L.; Morozov, I. B.

2011-12-01

210

Capillary pressure-saturation relations in porous media including the effect of wettability  

Microsoft Academic Search

In this work a functional relationship between capillary pressure and wetting phase saturation has been developed. Both the imbibition and drainage of a wetting phase liquid into a porous medium consisting of clean unconsolidated silica particles have been considered. In all, two bead packings, with average particle diameters of 120 ?m and 360 ?m, and three liquids—water, ethanol, and refrigerant-113—were

William A. Moseleya; Vijay K. Dhir

1996-01-01

211

Effect of pressure and saturating fluid on thermal conductivity of compact rock  

Microsoft Academic Search

Regional differences in heat flow of about 15% are often considered to be significant. How- ever, it is shown here that the observed thermal conductivity for dry rock samples may dif- fer by more than 15% from the conductivity that the rocks had in place--saturated and under hydrostatic pressure. Error in the apparent conductivity arises because cracks, which are present

J. B. Walsh; E. R. Decker

1966-01-01

212

Pressure and fluid saturation prediction in a multicomponent reservoir, using combined seismic and electromagnetic imaging  

SciTech Connect

This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO{sub 2} gas/oil ratio in a reservoir undergoing CO{sub 2} flood. Crosswell seismic and electromagnetic data sets taken before and during CO{sub 2} flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO{sub 2} injection pilot study. A rock properties model is developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie's law, provides parameters for modeling the relations between water saturation, porosity, and the electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used along with the observed changes in shear wave velocity to predict changes in reservoir pressure. The estimation of the spatial extent and amount of CO{sub 2} relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO{sub 2}/oil ratio. Resulting images of the CO{sub 2}/oil ratio show CO{sub 2}-rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO{sub 2}. The images produced by this process are better correlated to the location and amount of injected CO{sub 2} than are any of the individual images of change in geophysical parameters.

Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

2002-06-10

213

46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false High and low vapor pressure protection for tankships-T...39.20-13 High and low vapor pressure protection for tankships—T...sensing device that senses the pressure in the main vapor collection line, which:...

2012-10-01

214

46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false High and low vapor pressure protection for tankships-T...39.20-13 High and low vapor pressure protection for tankships—T...sensing device that senses the pressure in the main vapor collection line, which:...

2011-10-01

215

Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar  

NASA Technical Reports Server (NTRS)

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

Jacobsen, Richard T.; Stewart, Richard B.

1973-01-01

216

Droplet Vaporization In High-Pressure Environments I: Near Critical Conditions  

Microsoft Academic Search

A comprehensive analysis of multicomponent droplet vaporization at near critical conditions has been carried out. The model is based on complete time-dependent conservation equations, with a full account of variable properties and vapor-liquid interfacial thermodynamics. The influences of various high-pressure phenomena (including ambient gas solubility, property variation, thermodynamic non-ideality, and transient diffusion) on the vaporization mechanism are examined systematically. As

K. C. HSIEH; J. S. SHUEN; VIGOR YANG

1991-01-01

217

New expressions to describe solution nonideal osmotic pressure, freezing point depression, and vapor pressure.  

PubMed

New empirical expressions for osmotic pressure, freezing point depression, and vapor pressure are proposed based on the concepts of volume occupancy and (or) hydration force. These expressions are in general inverse relationships in comparison to the standard ideal expressions for the same properties. The slopes of the new equations are determined by the molecular weight of the solute and known constants. The accuracy and precision of the molecular weights calculated from the slope are identical and approximately 1% for the experiments reported here. The nonideality of all three colligative expressions is described by a dimensionless constant called the solute-solvent interaction parameter I. The results on sucrose have the same I = 0.26 for all three solution properties. The nonideality parameter I increased from 0.26 on sucrose to 1.7 on hemoglobin to successfully describe the well-known nonideal response of macromolecules. PMID:1299270

Fullerton, G D; Zimmerman, R J; Cantu, C; Cameron, I L

1992-12-01

218

A vapor pressure deficit effect on crop canopy photosynthesis.  

PubMed

Canopy CO2-exchange rates (CER), air temperatures, and dew points were measured throughout ten days during the 1987 growing season for cotton (Gossypium hirsutum L.), grain sorghum [Sorghum bicolor (L) Moench], and five soybean [Glycine max (L) Merr.] cultivars, and throughout seven days in 1988, on maize (Zea maize L.). The objective was to determine if the decline in CER per unit light during the afternoon is associated with a vapor pressure deficit (VPD) increase. Some of the soybean and maize plots were kept as dry as possible. A VPD term significantly contributed (P?0.05) to a canopy CER regression model in 54 of 80 data sets in 1987. Grain sorghum was less sensitive than the well-watered soybean genotypes to an increasing VPD (P?0.05) on three of the ten measurement days and less sensitive than cotton (P?0.05) on only one day. Cotton demonstrated less VPD sensitivity than soybean (P?0.05) on one day. The moisture stressed soybean plots showed a greater CER sensitivity to VPD (P?0.05) than the well-watered soybean plots. In 1988, the frequently irrigated maize plots were less sensitive to VPD (P?0.05) than the rain-fed plots early in the season, before the rain-fed plots were excessively damaged by moisture stress. These results indicate that the afternoon declines in canopy CER found in a number of different species are associated with increases in the VPD; recent work of others suggests that this may be due to partial stomatal closure. PMID:24419762

Pettigrew, W T; Hesketh, J D; Peters, D B; Woolley, J T

1990-04-01

219

Temperature and saturation dependence in the vapor sensing of butterfly wing scales.  

PubMed

The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. PMID:24863219

Kertész, K; Piszter, G; Jakab, E; Bálint, Zs; Vértesy, Z; Biró, L P

2014-06-01

220

The influence of contact angle on capillary pressure–saturation relations in a porous medium including various liquids  

Microsoft Academic Search

Quantitative description and modeling of two-phase flow in porous media requires specification of functional relationships between capillary pressure and saturation. In the presented study, this relationship was examined for various liquids by using the dimensionless capillary pressure function, which was developed by Leverett. The measurement of liquid saturations was achieved by a gamma attenuation system. The Ottawa sand as a

Ali Ishakoglu; A. Filiz Baytas

2005-01-01

221

The Oxidation Rate of SiC in High Pressure Water Vapor Environments  

NASA Technical Reports Server (NTRS)

CVD SiC and sintered alpha-SiC samples were exposed at 1316 C in a high pressure burner rig at total pressures of 5.7, 15, and 25 atm for times up to 100h. Variations in sample emittance for the first nine hours of exposure were used to determine the thickness of the silica scale as a function of time. After accounting for volatility of silica in water vapor, the parabolic rate constants for Sic in water vapor pressures of 0.7, 1.8 and 3.1 atm were determined. The dependence of the parabolic rate constant on the water vapor pressure yielded a power law exponent of one. Silica growth on Sic is therefore limited by transport of molecular water vapor through the silica scale.

Opila, Elizabeth J.; Robinson, R. Craig

1999-01-01

222

MEASUREMENT OF PARTIAL VAPOR PRESSURE OF AMMONIA OVER ACID AMMONIUM SULFATE SOLUTIONS BY AN INTEGRAL METHOD  

EPA Science Inventory

We present a simple, integral, passive method for measuring partial vapor pressure. ntegral methods are useful tools when dealing with very low concentrations because collection over extended periods increases the analytical sensitivity. assive methods have the advantage of not i...

223

Determination of Vapor Pressure-Temperature Relationships of Current Use Pesticides and Transformation Products  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sub-cooled liquid vapor pressures of current use organochlorine and organophosphate pesticides (chlorothalonil, chlorpyrifos methyl, diazinon, fipronil) and selected transformation products (chlorpyrifos oxon, heptachlor epoxide, oxychlordane, 3,5,6-trichloro-2-pyridinol) were determined at multiple...

224

Observations of accelerated silicon carbide recession by oxidation at high water-vapor pressures  

Microsoft Academic Search

A study of the exposure of SiC at 1,200 C and high water-vapor pressures (1.5 atm) has shown SiC recession rates that exceed what is predicted based on parabolic oxidation at water-vapor pressures of less than or equal to â¼1 atm. After exposure to these conditions, distinct silica-scale structures are observed; thick, porous, nonprotective cristobalite scales form above a thin,

Karren L. More; Peter F. Tortorelli; Mattison K. Ferber; James R. Keiser

2000-01-01

225

Vapor pressure measurement for binary and ternary systems containing a phosphoric ionic liquid  

Microsoft Academic Search

Vapor pressure data were measured for nine binary systems containing water, methanol or ethanol with the ionic liquids 1-methyl-3-methylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) and 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) and one ternary system ethanol–water–[MMIM][DMP] at varying temperature and ionic liquid mass percent ranging from 10% to 70% by a quasi-static method. The vapor pressure data of the binary systems were correlated

Jin Zhao; Xiao-Chuan Jiang; Chun-Xi Li; Zi-Hao Wang

2006-01-01

226

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

Microsoft Academic Search

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements

Robert J. Stochl; Neil T. van Dresar; Raymond F. Lacovic

1991-01-01

227

Liquid-propellant droplet vaporization and combustion in high pressure environments  

NASA Technical Reports Server (NTRS)

In order to correct the deficiencies of existing models for high-pressure droplet vaporization and combustion, a fundamental investigation into this matter is essential. The objective of this research are: (1) to acquire basic understanding of physical and chemical mechanisms involved in the vaporization and combustion of isolated liquid-propellant droplets in both stagnant and forced-convective environments; (2) to establish droplet vaporization and combustion correlations for the study of liquid-propellant spray combustion and two-phase flowfields in rocket motors; and (3) to investigate the dynamic responses of multicomponent droplet vaporization and combustion to ambient flow oscillations.

Yang, Vigor

1991-01-01

228

Sound Propagation in Saturated Gas-Vapor-Droplet Suspensions Considering the Effect of Transpiration on Droplet Evaporation  

NASA Technical Reports Server (NTRS)

The Sound attenuation and dispersion in saturated gas-vapor-droplet mixtures with evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson (1975) to accommodate the effects of transpiration on the linear particle relaxation processes of mass, momentum and energy transfer. It is shown that the inclusion of transpiration in the presence of mass transfer improves the agreement between the theory and the experimental data of Cole and Dobbins (1971) for sound attenuation in air-water fogs at low droplet mass concentrations. The results suggest that transpiration has an appreciable effect on both sound absorption and dispersion for both low and high droplet mass concentrations.

Kandula, Max

2012-01-01

229

Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data  

USGS Publications Warehouse

Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on a 1.0-m-long poly(dimethylsiloxane) bonded-phase (BP-1) column to determine their vapor pressures by GC (P??GC). A plot of log P??L vs log P??GC for standard compounds was made to establish a correlation between measured and literature values, and this correlation was then used to compute P??L of test compounds from their measured P??GC. P??L of seven major components of technical chlordane, endosulfan and its metabolites, ??-hexachlorocyclohexane, mirex, and two components of technical toxaphene were determined by GC. This method provides vapor pressures within a factor of 2 of average literature values for nonpolar compounds, similar to reported interlaboratory precisions of vapor pressure determinations. GC tends to overestimate vapor pressures of moderately polar compounds. ?? 1990 American Chemical Society.

Hinckley, D.A.; Bidleman, T.F.; Foreman, W.T.; Tuschall, J.R.

1990-01-01

230

Estimation of pressure and saturation fields from time-lapse impedance data using the ensemble smoother  

NASA Astrophysics Data System (ADS)

This paper introduces the use of the ensemble smoother as a method to invert time-lapse seismic data into pressure and saturation fields. The proposed method uses engineering information described in terms of reservoir flow simulations to generate samples of the prior uncertainty space. Subsequently, these samples are corrected using the time-lapse seismic as conditioning data. The problem is formulated in terms of generating an ensemble of pressure and saturation fields sampling the posterior uncertainty space. The proposed method is very flexible and computationally easy to implement. It has very few requirements in terms of the forward model (reservoir flow simulations and petroelastic modeling). This makes the method straightforward to integrate with existing commercial tools.

Emerick, A. A.

2014-06-01

231

Scaling procedures for capillary pressure data at low wetting-phase saturations  

Microsoft Academic Search

In this paper capillary pressure data, applicable to the saturation range below 5% are reported. The method used to obtain these data involved the determination of low-temperature nitrogen adsorption\\/desorption isotherms. Three types of samples were studied: Berea sandstone, a producing-reservoir sandstone, and microporous chert extracted from the producing-reservoir sandstone. The data for Berea sandstone, when scaled according toe the usual

Melrose

1991-01-01

232

Fractional wettability effects on two-and three-fluid capillary pressure-saturation relations  

Microsoft Academic Search

Studies of the relation between capillary pressure (Pc) and fluid saturation (S) for porous media containing oil-water or air-oil-water, often assume that the medium is strongly water-wet. Natural porous media, however, are composed of a variety of mineral constituents; such media are typically composed of water- and oil-wet fractions. This study reports on two- and three-fluid Pc-S data for media

Scott A. Bradford; Feike J. Leij

1995-01-01

233

Pore evolution during high pressure atomic vapor deposition D. D. Hass Y. Y. Yang H. N. G. Wadley  

E-print Network

Pore evolution during high pressure atomic vapor deposition D. D. Hass Ã? Y. Y. Yang Ã? H. N. G distribution (IAD) for vapor atom impacts with a substrate is strongly effected by the background pressure The development of physical vapor deposition systems that employ inert gas jets to entrain and deposit atomic

Wadley, Haydn

234

Gas chromatographic vapor pressure determination of atmospherically relevant oxidation products of ?-caryophyllene and ?-pinene  

NASA Astrophysics Data System (ADS)

Vapor pressures (subcooled liquid, pliquid) of atmospherically relevant oxidation products of ?-caryophyllene (?-caryophyllene aldehyde 0.18 ± 0.03 Pa and ?-nocaryophyllene aldehyde 0.17 ± 0.03 Pa), and ?-pinene (pinonaldehyde 16.8 ± 0.20 Pa, cis-pinic acid 0.12 ± 0.06 Pa, and cis-pinonic acid 0.99 ± 0.19 Pa) at 298 K were obtained by gas chromatography with flame ionization detection (FID) and mass spectrometric (MS) detection. The effects of stationary phase polarity and column film thickness on the vapor pressure values were investigated. Increase in stationary phase polarity provided smaller values, while increase in film thickness gave slightly higher values. Values for vapor pressure were at least two orders of magnitude lower when obtained by a method utilizing vaporization enthalpy (determined by gas chromatography-mass spectrometry) than by retention index method. Finally, the results were compared with values calculated by group contribution theory. For the ?-caryophyllene oxidation products, the values measured by gas chromatography were slightly lower than those obtained by theoretical calculations. The opposite trend was observed for the ?-pinene oxidation products. The methods based on gas chromatography are concluded to be highly useful for the determination of vapor pressures of semi-volatile compounds. Except for the most polar pinic and pinonic acids, differences between vapor pressure values obtained by GC-FID and GC-MS were small. Since GC-MS provides structural information simultaneously, the use of GC-MS is recommended.

Hartonen, Kari; Parshintsev, Jevgeni; Vilja, Vesa-Pekka; Tiala, Heidi; Knuuti, Sinivuokko; Lai, Ching Kwan; Riekkola, Marja-Liisa

2013-12-01

235

Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method  

DOEpatents

An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

Smith, Michael W; Jordan, Kevin C

2014-03-25

236

The influence of surfactant sorption on capillary pressure-saturation relationships  

SciTech Connect

The capillary pressure-saturation relationship, a fundamental relationship in the description of multiphase flow, depends on the interfacial properties of the system. Sorption of a cationic surfactant such as cetyltrimethylammonium bromide (CTAB) at the various interfaces of a system changes interfacial properties such as electrophoretic mobility, interfacial tensions, and contact angle. The objective of this paper is to examine the effect of the changes in these interfacial properties on the capillary pressure-saturation relationships for the air-water-silica system. The results presented here show that as the sorption of CTAB increases, the naturally negatively-charged silica surface becomes positively charged. This change in charge is reflected in the contact angle which passes through a maximum when the electrophoretic mobility is close to zero. The spontaneous imbibition capillary pressure relationship is more sensitive to changes in interfacial properties than the drainage relationship. In the air-water-silica system studied here, no imbibition is observed at the maximum contact angle. The surface tension and contact angle can be used to predict both the drainage and imbibition relationships of the air-water-silica-CTAB systems from that of the air-water-silica system. The prediction is accomplished through scaling using the value of surface tension and the operational contact angle, which can be obtained from the intrinsic angle through the incorporation of corrections for roughness and interfacial curvature. A comparison of the measured and calculated capillary pressure relationships shows that it is possible to predict the effect of surfactant sorption on both drainage and imbibition capillary pressure-saturation relationships for the system studied.

Desai, F.N.; Demond, A.H.; Hayes, K.F.

1991-01-01

237

The influence of surfactant sorption on capillary pressure-saturation relationships  

SciTech Connect

The capillary pressure-saturation relationship, a fundamental relationship in the description of multiphase flow, depends on the interfacial properties of the system. Sorption of a cationic surfactant such as cetyltrimethylammonium bromide (CTAB) at the various interfaces of a system changes interfacial properties such as electrophoretic mobility, interfacial tensions, and contact angle. The objective of this paper is to examine the effect of the changes in these interfacial properties on the capillary pressure-saturation relationships for the air-water-silica system. The results presented here show that as the sorption of CTAB increases, the naturally negatively-charged silica surface becomes positively charged. This change in charge is reflected in the contact angle which passes through a maximum when the electrophoretic mobility is close to zero. The spontaneous imbibition capillary pressure relationship is more sensitive to changes in interfacial properties than the drainage relationship. In the air-water-silica system studied here, no imbibition is observed at the maximum contact angle. The surface tension and contact angle can be used to predict both the drainage and imbibition relationships of the air-water-silica-CTAB systems from that of the air-water-silica system. The prediction is accomplished through scaling using the value of surface tension and the operational contact angle, which can be obtained from the intrinsic angle through the incorporation of corrections for roughness and interfacial curvature. A comparison of the measured and calculated capillary pressure relationships shows that it is possible to predict the effect of surfactant sorption on both drainage and imbibition capillary pressure-saturation relationships for the system studied.

Desai, F.N.; Demond, A.H.; Hayes, K.F.

1991-12-31

238

The Dynamics of Vapor Bubbles in Acoustic Pressure Fields  

NASA Technical Reports Server (NTRS)

In spite of a superficial similarity with gas bubbles, the intimate coupling between dynamical and thermal processes confers to oscillating vapor bubbles some unique characteristics. This paper examines numerically the validity of some asymptotic-theory predictions such as the existence of two resonant radii and a limit size for a given sound amplitude and frequency. It is found that a small vapor bubble in a sound field of sufficient amplitude grows quickly through resonance and continues to grow thereafter at a very slow rate, seemingly indefinitely. Resonance phenomena therefore play a role for a few cycles at most, and reaching a limit size-if one exists at all-is found to require far more than several tens of thousands of cycles. It is also found that some small bubbles may grow or collapse depending on the phase of the sound field. The model accounts in detail for the thermo-fluid-mechanic processes in the vapor. In the second part of the paper, an approximate formulation valid for bubbles small with respect to the thermal penetration length in the vapor is derived and its accuracy examined, The present findings have implications for acoustically enhanced boiling heat transfer and other special applications such as boiling in microgravity.

Hao, Y.; Prosperetti, A.

1999-01-01

239

Equation for compressibility factor and density of saturated n-alkanes (C1–C10) vapor, parahydrogen, and water at the boiling line  

Microsoft Academic Search

An equation is obtained for calculating the compressibility factor and saturated vapor density of n-alkanes (C1–C10), parahydrogen, and water at temperatures of the triple point up to critical point. The calculation error is close to that\\u000a for experimental data.

M. S. Rozhnov; D. N. Melnik; P. A. Chmykhalo

2010-01-01

240

Assessment of the Accuracy of Pharmacy Students’ Compounded Solutions Using Vapor Pressure Osmometry  

PubMed Central

Objective. To assess the effectiveness of using a vapor pressure osmometer to measure the accuracy of pharmacy students’ compounding skills. Design. Students calculated the theoretical osmotic pressure (mmol/kg) of a solution as a pre-laboratory exercise, compared their calculations with actual values, and then attempted to determine the cause of any errors found. Assessment. After the introduction of the vapor pressure osmometer, the first-time pass rate for solution compounding has varied from 85% to 100%. Approximately 85% of students surveyed reported that the instrument was valuable as a teaching tool because it objectively assessed their work and provided immediate formative assessment. Conclusions. This simple technique of measuring compounding accuracy using a vapor pressure osmometer allowed students to see the importance of quality control and assessment in practice for both pharmacists and technicians. PMID:23610476

McPherson, Timothy B.

2013-01-01

241

On fluid reserves and the production of superheated steam from fractured, vapor-dominated geothermal reservoirs  

Microsoft Academic Search

Vapor-dominated geothermal reservoirs produce saturated or superheated steam, and vertical pressure gradients are close to vapor static. These observations have been generally accepted as providing conclusive evidence that the liquid saturation must be rather small (<50%) in order that liquid may be nearly immobile. This conclusion ignores the crucial role of conductive heat transfer mechanisms in fractured reservoirs for vaporizing

K. Pruess; T. N. Narasimhan

1982-01-01

242

Sulfide saturation of basalt and andesite melts at high pressures and temperatures  

NASA Technical Reports Server (NTRS)

When the sulfur content of an Fe-bearing magma exceeds the saturation limit for the bulk composition, an immiscible iron sulfide melt fraction separates. For an understanding of the geochemistry of sulfur-bearing magmatic systems, more information is needed regarding the solubility of metal sulfide in silicate melt at its source and the solubility changes as a function of changing intensive and extensive variables. In the present investigation, the sulfur saturation surface is determined for the pressure range from 12.5 to 30 kbar and the temperature range from 1300 to 1460 C for three silicate melt compositions representing a range of SiO2 and FeO compositions.

Wendlandt, R. F.

1982-01-01

243

Vapor Pressure of Tektite Glass and Its Bearing on Tektite Trajectories Determined from Aerodynamic Analysis  

Microsoft Academic Search

Various experiments have been conducted to resolve a large discrepancy be- tween two measurements that have been reported for the vapor pressure of tektite glass. This discrepancy significantly affects the trajectories and mode of tektite origin as determined from calculations oœ aerodynamic ablation. Measurements in a furnace oœ vaporization rate relative to that of four different standards (SiO2, TiO_, Au,

FRANK J. CENTOLANZI; DEAN R. CHAPMAN

1966-01-01

244

Permeability–saturation–capillary pressure relations in textile fabrics from an integrated upward–horizontal–downward wicking test  

Microsoft Academic Search

A new wicking test was developed that provides intrinsic quantitative descriptors of fabrics that can be used to predict wicking behavior. These descriptors are permeability (k) and capillary pressure (Pc) as functions of saturation (S). A single fabric strip is positioned to allow sequential upward, horizontal, and downward wicking of fluid from an infinite reservoir. The upward section governs saturation,

Craig B. Simile; Haskell W. Beckham

2011-01-01

245

Permeability–saturation–capillary pressure relations in textile fabrics from an integrated upward–horizontal–downward wicking test  

Microsoft Academic Search

A new wicking test was developed that provides intrinsic quantitative descriptors of fabrics that can be used to predict wicking behavior. These descriptors are permeability (k) and capillary pressure (Pc) as functions of saturation (S). A single fabric strip is positioned to allow sequential upward, horizontal, and downward wicking of fluid from an infinite reservoir. The upward section governs saturation,

Craig B. Simile; Haskell W. Beckham

2012-01-01

246

Permeability–saturation–capillary pressure relations in textile fabrics from an integrated upward–horizontal–downward wicking test  

Microsoft Academic Search

A new wicking test was developed that provides intrinsic quantitative descriptors of fabrics that can be used to predict wicking behavior. These descriptors are permeability (k) and capillary pressure (Pc) as functions of saturation (S). A single fabric strip is positioned to allow sequential upward, horizontal and downward wicking of fluid from an infinite reservoir. The upward section governs saturation,

Craig B. Simile; Haskell W. Beckham

2011-01-01

247

Measurements of Capillary Pressure-Saturation Relationships for Silica Sands Using Light Transmission Visualization and a Rapid Pseudo Static Methods  

EPA Science Inventory

Measurement of water saturation in porous media is essential for many types of studies including subsurface water flow, subsurface colloids transport and contaminant remediation to name a few. Water saturation (S) in porous media is dependent on the capillary pressure (Pc) which,...

248

Effects of vapor pressure on thermodynamic equilibrium in multiphase flow for thermochemical hydrogen production  

NASA Astrophysics Data System (ADS)

This paper examines the effects of H2O vapor pressure on the equilibrium conditions of a CuCl2 hydrolysis reactor in the thermochemical Cu-Cl cycle of hydrogen production. A new predictive model is developed to determine the minimum steam requirement in the reactor based on the chemical equilibrium condition, reactor pressure and fraction of gaseous reactant. Experimental data, at three separate vapour pressures of steam, compared well with the new predictive formulation.

Pope, K.; Naterer, G. F.; Wang, Z. L.

2013-12-01

249

Pressure-coupled vaporization and combustion responses of liquid-fuel droplets in high-pressure environments  

NASA Technical Reports Server (NTRS)

The dynamic responses of liquid-fuel droplet vaporization and combustion to ambient pressure oscillations are examined. The analysis is based on the complete sets of conservation equations for both gas and liquid phases, and accommodates detailed treatments of finite-rate chemical kinetics and variable properties. With a full account of thermodynamic phase equilibrium at the droplet surface, the model enables a systematic examination of the effects of ambient flow conditions on the droplet behavior. The responses of hydrocarbon fuel droplets in both sub- and super-critical environments are investigated. Results indicate that the droplet gasification and burning mechanisms depend greatly on the ambient pressure. In particular, a rapid enlargement of the vaporization and combustion responses occurs when the droplet surface reaches its critical point, mainly due to the strong variations of latent heat of vaporization and thermophysical properties at the critical state.

Yang, Vigor; Shuen, J. S.; Hsiao, C. C.

1991-01-01

250

Modeling atomization processes in high-pressure vaporizing sprays  

NASA Astrophysics Data System (ADS)

The theoretical basis and numerical implementation of KIVA, a multidimensional computer code for the simulation of atomization and vaporization processes in the injection of a liquid through a round hole into a compressed gas, are described. KIVA is based on the blob-injection model of Reitz and Diwakar (1987), taking into account the effects of liquid inertia, surface tension, and the aerodynamic forces on the jet, as well as drop collision and coalescence and the effect of drops on turbulence in the gas. The predictions of KIVA for different injection regimes are compared with published experimental data in extensive graphs, and good agreement is demonstrated.

Reitz, Rolf D.

251

A simple grand canonical approach to compute the vapor pressure of bulk and finite size systems  

NASA Astrophysics Data System (ADS)

In this article we introduce a simple grand canonical screening (GCS) approach to accurately compute vapor pressures from molecular dynamics or Monte Carlo simulations. This procedure entails a screening of chemical potentials using a conventional grand canonical scheme, and therefore it is straightforward to implement for any kind of interface. The scheme is validated against data obtained from Gibbs ensemble simulations for water and argon. Then, it is applied to obtain the vapor pressure of the coarse-grained mW water model, and it is shown that the computed value is in excellent accord with the one formally deduced using statistical thermodynamics arguments. Finally, this methodology is used to calculate the vapor pressure of a water nanodroplet of 94 molecules. Interestingly, the result is in perfect agreement with the one predicted by the Kelvin equation for a homogeneous droplet of that size.

Factorovich, Matías H.; Molinero, Valeria; Scherlis, Damián A.

2014-02-01

252

A simple grand canonical approach to compute the vapor pressure of bulk and finite size systems.  

PubMed

In this article we introduce a simple grand canonical screening (GCS) approach to accurately compute vapor pressures from molecular dynamics or Monte Carlo simulations. This procedure entails a screening of chemical potentials using a conventional grand canonical scheme, and therefore it is straightforward to implement for any kind of interface. The scheme is validated against data obtained from Gibbs ensemble simulations for water and argon. Then, it is applied to obtain the vapor pressure of the coarse-grained mW water model, and it is shown that the computed value is in excellent accord with the one formally deduced using statistical thermodynamics arguments. Finally, this methodology is used to calculate the vapor pressure of a water nanodroplet of 94 molecules. Interestingly, the result is in perfect agreement with the one predicted by the Kelvin equation for a homogeneous droplet of that size. PMID:24527904

Factorovich, Matías H; Molinero, Valeria; Scherlis, Damián A

2014-02-14

253

A simple grand canonical approach to compute the vapor pressure of bulk and finite size systems  

SciTech Connect

In this article we introduce a simple grand canonical screening (GCS) approach to accurately compute vapor pressures from molecular dynamics or Monte Carlo simulations. This procedure entails a screening of chemical potentials using a conventional grand canonical scheme, and therefore it is straightforward to implement for any kind of interface. The scheme is validated against data obtained from Gibbs ensemble simulations for water and argon. Then, it is applied to obtain the vapor pressure of the coarse-grained mW water model, and it is shown that the computed value is in excellent accord with the one formally deduced using statistical thermodynamics arguments. Finally, this methodology is used to calculate the vapor pressure of a water nanodroplet of 94 molecules. Interestingly, the result is in perfect agreement with the one predicted by the Kelvin equation for a homogeneous droplet of that size.

Factorovich, Matías H.; Scherlis, Damián A. [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA (Argentina)] [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA (Argentina); Molinero, Valeria [Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850 (United States)] [Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850 (United States)

2014-02-14

254

Quantitative structure-property relationships for prediction of boiling point, vapor pressure, and melting point.  

PubMed

Boiling point, vapor pressure, and melting point are important physicochemical properties in the modeling of the distribution and fate of chemicals in the environment. However, such data often are not available, and therefore must be estimated. Over the years, many attempts have been made to calculate boiling points, vapor pressures, and melting points by using quantitative structure-property relationships, and this review examines and discusses the work published in this area, and concentrates particularly on recent studies. A number of software programs are commercially available for the calculation of boiling point, vapor pressure, and melting point, and these have been tested for their predictive ability with a test set of 100 organic chemicals. PMID:12924571

Dearden, John C

2003-08-01

255

Preconcentrator with high volume chiller for high vapor pressure particle detection  

DOEpatents

Apparatus and method for collecting particles of both high and low vapor pressure target materials entrained in a large volume sample gas stream. Large volume active cooling provides a cold air supply which is mixed with the sample gas stream to reduce the vapor pressure of the particles. In embodiments, a chiller cools air from ambient conditions to 0-15.degree. C. with the volumetric flow rate of the cold air supply being at least equal to the volumetric flow rate of the sample gas stream. In further embodiments an adsorption media is heated in at least two stages, a first of which is below a threshold temperature at which decomposition products of the high vapor pressure particle are generated.

Linker, Kevin L

2013-10-22

256

Pore pressure diffusion and the hydrologic response of nearly saturated, thin landslide deposits of rainfall  

SciTech Connect

Previous workers have correlated slope failures during rainstorms with rainfall intensity, rainfall duration, and seasonal antecedent rainfall. This note shows how such relationships can be interpreted using a periodic steady-state solution to the well-known linear pressure diffusion equation. Normalization of the governing equation yields a characteristic response time that is a function of soil thickness, saturated hydraulic conductivity, and pre-storm effective porosity, and which is analogous to the travel time of a piston wetting front. The effects of storm frequency and magnitude are also successfully quantified using dimensionless attenuation factors and lag times.

Haneberg, W.C. (New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, Socorro, NM (United States))

1991-11-01

257

Microfluidic vapor-diffusion barrier for pressure reduction in fully closed PCR modules.  

PubMed

Microfluidic systems for polymerase chain reaction (PCR) should be fully closed to avoid vapor loss and to exclude the risk of contaminating the laboratory environment. In closed systems however, the high temperatures of up to 95 °C associated with PCR cause high overpressures up to 100 kPa, dominated by the increase of vapor partial pressure upon evaporation. Such high overpressures pose challenges to the mechanical stability of microfluidic chips as well as to the liquid handling in integrated sample-to-answer systems. In this work, we drastically reduce the pressure increase in fully closed PCR systems by integrating a microchannel that serves as a vapor-diffusion barrier (VDB), separating the liquid-filled PCR chamber from an auxiliary air chamber. In such configurations, propagation of vapor from the PCR chamber into the auxiliary air chamber and as a consequence the increase of pressure is limited by the slow diffusion process of vapor through the VDB. At temperature increase from 23 °C to 95 °C, we demonstrate the reduction of overpressure from more than 80 kPa without the VDB to only 35 kPa with the VDB. We further demonstrate proper function of VDB and its easy integration with downstream processes for PCR based nucleic acid amplification within centrifugal microfluidics. Without integration of the VDB, malfunction due to pressure-induced delamination of the microfluidic chip occurred. PMID:25524461

Czilwik, G; Schwarz, I; Keller, M; Wadle, S; Zehnle, S; von Stetten, F; Mark, D; Zengerle, R; Paust, N

2015-02-01

258

VAPOR PRESSURE ISOTOPE EFFECTS IN THE MEASUREMENT OF ENVIRONMENTAL TRITIUM SAMPLES.  

SciTech Connect

Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The magnitude of the vapor pressure isotope effect is characterized as functions of the amount of water distilled from the sample aliquot and the heat settings for the distillation process. The tritium concentration in the distillate is higher than the tritium concentration in the sample early in the distillation process, it then sharply decreases due to the vapor pressure isotope effect and becomes lower than the tritium concentration in the sample, until the high tritium concentration retained in the boiling flask is evaporated at the end of the process. At that time, the tritium concentration in the distillate again overestimates the sample tritium concentration. The vapor pressure isotope effect is more pronounced the slower the evaporation and distillation process is conducted; a lower heat setting during the evaporation of the sample results in a larger bias in the tritium measurement. The experimental setup used and the fact that the current study allowed for an investigation of the relative change in vapor pressure isotope effect in the course of the distillation process distinguish it from and extend previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.034 {+-} 0.033, 1.052 {+-} 0.025, and 1.066 {+-} 0.037, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples, this implies that the tritium concentration could be underestimated by 3 - 6%.

Kuhne, W.

2012-12-03

259

Use of temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration.  

PubMed

To quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern Wyoming, USA. The forest stand was located along a soil water gradient from a stream side to near the top of a ridge. The stand was dominated by Pinus contorta Dougl. ex Loud. with Picea engelmannii Parry ex Engelm and Abies lasiocarpa (Hook.) Nutt. present near the stream and scattered individuals of Populus tremuloides Michx. throughout the stand. We used a cyclic sampling design that maximized spatial information with a minimum number of samples for semivariogram analyses. All species exhibited previously established responses to environmental variables in which the dominant driver was a saturating response to vapor pressure deficit (D). This response to D is predictable from tree hydraulic theory in which stomatal conductance declines as D increases to prevent excessive cavitation. The degree to which stomatal conductance declines with D is dependent on both species and individual tree physiology and increases the variability in transpiration as D increases. We quantified this variability spatially by calculating the spatial autocorrelation within 0.2-kPa D bins. Across 11 bins of D, spatial autocorrelation in individual tree transpiration was inversely correlated to D and dropped from 45 to 20 m. Spatial autocorrelation was much less for transpiration per unit leaf area and not significant for transpiration per unit sapwood area suggesting that spatial autocorrelation within a particular D bin could be explained by tree size. Future research should focus on the mechanisms underlying tree size spatial variability, and the potentially broad applicability of the inverse relationship between D and spatial autocorrelation in tree transpiration. PMID:18244950

Adelman, Jonathan D; Ewers, Brent E; Mackay, D Scott

2008-04-01

260

Saturation meter  

DOEpatents

A saturation meter for use in a pressurized water reactor plant comprising a differential pressure transducer having a first and second pressure sensing means and an alarm. The alarm is connected to the transducer and is preset to activate at a level of saturation prior to the formation of a steam void in the reactor vessel.

Gregurech, S.

1984-08-01

261

Thermal Conductivity of Liquid and Vapor Hydrocarbon Systems: Pentanes and Heavier at Low Pressures  

SciTech Connect

A simplified equation has been developed for the prediction of thermal conductivity of liquid and vapor hydrocarbon systems as a function of temperature with the normal boiling point and the specific gravity as input parameters. The equation is in the form of k = aT /SUB b/ /SUP b/ S /SUP c/ where a, b, and c are functions of temperature only. The equation is applicable for liquids over the boiling range of 100-650/sup 0/F and the temperature ranging from the normal freezing point to the normal boiling point and pressures of less than 30 atm. For vapors the equation is applicable over the boiling range of 150-550/sup 0/F and temperature range of 400-700/sup 0/F for pressures less than 3 atm. Calculated values produce an average deviation of 4.4% from experimental values for 190 liquid points. For vapors, average deviation was about 3% for 126 data points.

Riazi, M.R.; Faghri, A.

1985-04-01

262

Vapor pressure and normal boiling point predictions for pure methyl esters and biodiesel fuels  

Microsoft Academic Search

Temperature dependent vapor pressures of the methyl esters of fourteen fatty acids that are commonly present in biodiesel fuels were predicted by the Antoine equation and a group contribution method. The predicted boiling points of these esters up to a pressure of 100mmHg were within ±1.0% of reported data for these two methods. Normal boiling points were determined from both

W. Yuan; A. C. Hansen; Q. Zhang

2005-01-01

263

Effect of additives on the antiknock properties and Reid vapor pressure of gasoline  

Microsoft Academic Search

An evaluation was made of the effect produced by the addition of oxygenates such as ethanol, ETBE and MTBE and nonoxygenates such as isooctane and toluene on the Reid vapor pressure (RVP) and octane number of two types of gasoline with different chemical compositions. Locally produced gasoline was blended with five different percentages (v\\/v) of the additives, i.e. 5, 10,

Rosângela da Silva; Renato Cataluña; Eliana Weber de. Menezes; Dimitrios Samios; Clarisse M. Sartori Piatnicki

2005-01-01

264

Quasi-static vapor pressure measurements on reactive systems in inert atmosphere box  

NASA Technical Reports Server (NTRS)

Apparatus makes vapor pressure measurements on air-sensitive systems in an inert atmosphere glove box. Once the apparatus is loaded with the sample and all connections made, all measuring operations may be performed outside the box. The apparatus is a single-tube adaptation of the double-tube quasi-static technique.

Fischer, A. K.

1968-01-01

265

RELATIONSHIP BETWEEN TRANSPIRATION AND NITROGEN UPTAKE BY PEPPER (CAPSICUM ANNUUM) AS MEDIATED BY VAPOR PRESSURE DEFICIT  

E-print Network

was to study the possible relationship between transpiration and nitrogen uptake. Bell peppers (Capsicum annuumRELATIONSHIP BETWEEN TRANSPIRATION AND NITROGEN UPTAKE BY PEPPER (CAPSICUM ANNUUM) AS MEDIATED and growth even under low nutrient conditions. INDEX WORDS: nitrogen, pepper, transpiration, vapor pressure

Teskey, Robert O.

266

Vapor Pressures and Thermodynamics of Oxygen-Containing Polycyclic Aromatic Hydrocarbons Measured Using Knudsen Effusion  

PubMed Central

Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) are ubiquitous environmental pollutants resulting from the incomplete combustion of coal and fossil fuels. Their vapor pressures are key thermodynamic data essential for modeling fate and transport within the environment. The present study involved nine PAHs containing oxygen heteroatoms, including aldehyde, carboxyl and nitro groups, specifically: 2-nitrofluorene; 9-fluorenecarboxylic acid; 2-fluorenecarboxaldehyde; 2-anthracenecarboxylic acid; 9-anthracenecarboxylic acid; 9-anthraldehyde; 1-nitropyrene; 1-pyrenecarboxaldehyde and 1-bromo-2-naphthoic acid. The vapor pressures of these compounds, with molecular weights ranging from 194 to 251 grams per mole, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, non-oxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of –CHO,–COOH, and –NO2 groups onto these PAHs increases the enthalpy of sublimation and decreases the vapor pressure as compared to the parent PAH; the position of substitution also plays a significant role in determining the vapor pressure of these OPAHs. PMID:18220445

Goldfarb, Jillian L.

2013-01-01

267

Computationally efficient modeling of wafer temperatures in a low-pressure chemical vapor deposition furnace  

Microsoft Academic Search

A new thermal model is developed to predict wafer temperatures within a hot-wall low pressure chemical vapor deposition furnace based on the furnace wall temperatures as measured by thermocouples. Based on an energy balance of the furnace system, this model is a transformed linear model which captures the nonlinear relationship between the furnace wall temperature distribution and the wafer temperature

Qinghua He; S. Joe Qin; Anthony J. Toprac

2003-01-01

268

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

269

The viscosity of the refrigerant 1,1-difluoroethane along the saturation line  

NASA Astrophysics Data System (ADS)

The viscosity coefficient of the refrigerant R152a (1,1-difluoroethane) has been measured along the saturation line both in the saturated liquid and in the saturated vapor. The data have been obtained every 10 K from 243 up to 393 K by means of a vibrating-wire viscometer using the free damped oscillation method. The density along the saturation line was calculated from the equation of state given by Tamatsu et al. with application of the saturated vapor-pressure correlation given by Higashi et al. An interesting result is that in the neighborhood of the critical point, the kinematic viscosity of the saturated liquid seems to coincide with that of the saturated vapor. The results for the saturated liquid are in satisfying agreement with those of Kumagai and Takahashi and of Phillips and Murphy. A comparison of the saturatedvaport data with the unsaturated-vapor data of Takahashi et al. shows some discrepancies.

van der Gulik, P. S.

1993-07-01

270

Spectral properties of molecular iodine in absorption cells filled to specified saturation pressure.  

PubMed

We present the results of measurement and evaluation of spectral properties of iodine absorption cells filled at certain saturation pressure. A set of cells made of borosilicate glass instead of common fused silica was tested for their spectral properties in greater detail with special care for the long-term development of the absorption media purity. The results were compared with standard fused silica cells and the high quality of iodine was verified. A measurement method based on an approach relying on measurement of linewidth of the hyperfine transitions is proposed as a novel technique for iodine cell absorption media purity evaluation. A potential application in laser metrology of length is also discussed. PMID:25402909

Hrabina, Jan; Šarbort, Martin; Acef, Ouali; Burck, Frédéric Du; Chiodo, Nicola; Holá, Miroslava; ?íp, Ond?ej; Lazar, Josef

2014-11-01

271

Deviations from Ideal Sublimation Vapor Pressure Behavior in Mixtures of Polycyclic Aromatic Compounds with Interacting Heteroatoms  

PubMed Central

Despite the relatively small atomic fraction of a given heteroatom in a binary mixture of polycyclic aromatic compounds (PAC), the inclusion of heteroatomic substituted compounds can significantly impact mixture vapor pressure behavior over a wide range of temperatures. The vapor pressures of several binary PAC mixtures containing various heteroatoms show varying behavior, from practically ideal behavior following Raoult’s law to significant deviations from ideality depending on the heteroatom(s) present in the mixture. Mixtures were synthesized using the quench-cool technique with equimolar amounts of two PAC, both containing heteroatoms such as aldehyde, carboxyl, nitrogen, and sulfur substituent groups. For some mixtures, deviation from ideality is inversely related to temperature, though in other cases we see deviations from ideality increasing with temperature, whereas some appear independent of temperature. Most commonly we see lower vapor pressures than predicted by Raoult’s law, which indicates that the interacting heteroatoms prefer the solid mixture phase as opposed to the vapor phase. Although negative deviations predominate from Raoult’s Law, the varying mixtures investigated show both higher and lower enthalpies and entropies of sublimation than predicted. In each mixture, a higher enthalpy of sublimation leads to higher entropy of sublimation than predicted, and vice versa. PMID:23807818

Goldfarb, Jillian L.; Suuberg, Eric M.

2013-01-01

272

The vapor pressures of supercooled NHO3/H2O solutions. [in polar stratospheric clouds  

NASA Technical Reports Server (NTRS)

A procedure utilizing the Gibbs-Duhem relation is used to extrapolate vapor pressures of supercooled HNO3 mixtures to 190 K. Values of A and B from the equation logP = A - B/T are presented for solutions between 0.20 and 0.25 mole fraction HNO3. In the stratosphere, if sufficient HNO3 vapor is present because it has not come into equilibrium with the nitric acid trihydrate, supercooled nitric acid solutions could condense at temperatures up to 1.5 + or - 0.8 K above the ice point.

Hanson, David R.

1990-01-01

273

On optimum interstage pressure for two-stage and mechanical-subcooling vapor-compression refrigeration cycles  

Microsoft Academic Search

The objective of the present study is to demonstrate that the optimum interstage pressure for a two-stage refrigeration system can be approximated by the saturation pressure corresponding to the arithmetic mean of the condensing and evaporating temperatures. It is also shown that the optimum performance of a refrigeration system with mechanical sub-cooling occurred when the subcooler compressor (saturation suction) temperature

S. M. Zubair; S. H. Khan

1995-01-01

274

Development of a Model for High Precursor Conversion Efficiency Pulsed-Pressure Chemical Vapor Deposition (PP-CVD) Processing  

E-print Network

1 Development of a Model for High Precursor Conversion Efficiency Pulsed- Pressure Chemical Vapor. ___________________________________________________________________________ Abstract A model of the movement of precursor particles in the unsteady Pulsed-Pressure Chemical Vapour and moderate reactor peak pressure. Keywords: Pulsed pressure chemical vapour deposition (PP-CVD), Precursor

Hickman, Mark

275

Ex 6.1(a) The vapor pressure of dichloromethane at 24.1C is 400 Torr and its enthalpy of vaporization is 28.7 kJ mol-1  

E-print Network

Ex 6.1(a) The vapor pressure of dichloromethane at 24.1°C is 400 Torr and its enthalpy of vaporization is 28.7 kJ mol-1 . Estimate the temperature at which its vapor pressure is 500 Torr. Ex 6.3(a) The vapor pressure of a liquid in the temperature range 200 K to 260 K was found to fit the expression ln

Findley, Gary L.

276

High-pressure homogenization lowers water vapor permeability of soybean protein isolate-beeswax films.  

PubMed

Soybean-protein isolate (SPI) has excellent film-forming capacity. However, the water vapor permeability of SPI film is high, which will cause the moisture lose of packaged products. The effect of high-pressure homogenization (HPH) on the water vapor permeability of SPI-beeswax films was evaluated. The HPH was effective at lowering the water vapor permeability of SPI-beeswax films to about 50% of the control. The HPH reduced the particle size of films and made their matrix more compact. The HPH improved the hydrophobicity of SPI-beeswax films. For the first time, we proved that the HPH improved the bound-beeswax content in SPI-beeswax films. The bound beeswax was effective at lowering the water vapor permeability of films rather than the free beeswax in the film matrix. In summary, the HPH lowered water vapor permeability of SPI-beeswax films by reducing their particle size and raising their hydrophobicity and bound-beeswax content. PMID:22324505

Zhang, Chao; Ma, Yue; Guo, Kuan; Zhao, Xiaoyan

2012-03-01

277

Low pressure MOCVD (metalorganic chemical vapor deposition) growth of InSb  

SciTech Connect

Low pressure (200 Torr) metalorganic chemical vapor deposition (MOCVD) of InSb has been examined through variation of the Column III (TMIn) and Column V (TMSb or TESb) precursor partial pressures. The use of lower growth pressure significantly enhanced the range of allowable Column III Column V partial pressures in which specular morphology InSb could be obtained without the formation of In droplets or Sb crystals. In addition, a 70% improvement in the average hole mobility was obtained, compared to InSb grown in the same reactor at atmospheric pressure. SIMS analysis revealed that Si at the substrate/epitaxial layer interface is an important impurity that may contribute to degradation of the mobility. Substitution of TESb for TMSb did not result in any improvement in the purity of the InSb. 6 refs.

Cunningham, B.T.; Schneider, R.P. Jr.; Biefeld, R.M.

1990-01-01

278

Observations on vapor pressure in SPR caverns : sources.  

SciTech Connect

The oil of the Strategic Petroleum Reserve (SPR) represents a national response to any potential emergency or intentional restriction of crude oil supply to this country, and conforms to International Agreements to maintain such a reserve. As assurance this reserve oil will be available in a timely manner should a restriction in supply occur, the oil of the reserve must meet certain transportation criteria. The transportation criteria require that the oil does not evolve dangerous gas, either explosive or toxic, while in the process of transport to, or storage at, the destination facility. This requirement can be a challenge because the stored oil can acquire dissolved gases while in the SPR. There have been a series of reports analyzing in exceptional detail the reasons for the increases, or regains, in gas content; however, there remains some uncertainty in these explanations and an inability to predict why the regains occur. Where the regains are prohibitive and exceed the criteria, the oil must undergo degasification, where excess portions of the volatile gas are removed. There are only two known sources of gas regain, one is the salt dome formation itself which may contain gas inclusions from which gas can be released during oil processing or storage, and the second is increases of the gases release by the volatile components of the crude oil itself during storage, especially if the stored oil undergoes heating or is subject to biological generation processes. In this work, the earlier analyses are reexamined and significant alterations in conclusions are proposed. The alterations are based on how the fluid exchanges of brine and oil uptake gas released from domal salt during solutioning, and thereafter, during further exchanges of fluids. Transparency of the brine/oil interface and the transfer of gas across this interface remains an important unanswered question. The contribution from creep induced damage releasing gas from the salt surrounding the cavern is considered through computations using the Multimechanism Deformation Coupled Fracture (MDCF) model, suggesting a relative minor, but potentially significant, contribution to the regain process. Apparently, gains in gas content can be generated from the oil itself during storage because the salt dome has been heated by the geothermal gradient of the earth. The heated domal salt transfers heat to the oil stored in the caverns and thereby increases the gas released by the volatile components and raises the boiling point pressure of the oil. The process is essentially a variation on the fractionation of oil, where each of the discrete components of the oil have a discrete temperature range over which that component can be volatized and removed from the remaining components. The most volatile components are methane and ethane, the shortest chain hydrocarbons. Since this fractionation is a fundamental aspect of oil behavior, the volatile component can be removed by degassing, potentially prohibiting the evolution of gas at or below the temperature of the degas process. While this process is well understood, the ability to describe the results of degassing and subsequent regain is not. Trends are not well defined for original gas content, regain, and prescribed effects of degassing. As a result, prediction of cavern response is difficult. As a consequence of this current analysis, it is suggested that solutioning brine of the final fluid exchange of a just completed cavern, immediately prior to the first oil filling, should be analyzed for gas content using existing analysis techniques. This would add important information and clarification to the regain process. It is also proposed that the quantity of volatile components, such as methane, be determined before and after any degasification operation.

Munson, Darrell Eugene

2010-05-01

279

Calculations of Freezing Point Depression, Boiling Point Elevation, Vapor Pressure and Enthalpies of Vaporization of Electrolyte Solutions by a Modified Three-Characteristic Parameter Correlation Model  

Microsoft Academic Search

A method was proposed for calculating the thermodynamic properties, freezing point depression, boiling point elevation, vapor\\u000a pressure and enthalpy of vaporization for single solute electrolyte solutions, including aqueous and nonaqueous solutions,\\u000a based on a modified three-characteristic-parameter correlation model. When compared with the corresponding literature values,\\u000a the calculated results show that this method gives a very good approximation, especially for 1-1

Xinlei Ge; Xidong Wang

2009-01-01

280

Thermo-optical determination of vapor pressures of TNT and RDX nanofilms.  

PubMed

Accurate thermodynamic parameters of thin films of explosives are important for understanding their behavior in the nanometer scale as well as in standoff detection. Using UV-absorbance spectroscopy technique, accurate thermodynamic parameters such as activation energies of sublimation, sublimation rates, and vapor pressures of the explosives cyclotrimethylenetrinitramine (RDX) and 2,4,6-trinitrotoluene (TNT) were determined. The values of these parameters are in excellent agreement with those reported using traditional experiments based on gravimetry. In terms of the Clapeyron equation, the dependence of RDX and TNT vapor pressures on temperature can be described by the relations LnP (Pa)=39.6-15459/T (K) and LnP (Pa)=34.9-12058/T (K), respectively. Heats of sublimation of RDX and TNT were also determined to be 128kJ/mol and 100.2kJ/mol, respectively. PMID:22099681

Hikal, Walid M; Paden, Jeffrey T; Weeks, Brandon L

2011-12-15

281

Water-vapor pressure in nests of the San Miguel Island Song Sparrow  

USGS Publications Warehouse

The water-vapor pressure (PN) in nests of the San Miguel Island race of Song Sparrows (Melospiza melodia micronyx) averaged 16 torr, but varied considerable between nests and within individual nests during successive days of incubation. Large daily fluctuations occurred throughout the incubation period and did not parallel concurrent changes in ambien vapor pressure (P1). Daily rates of water loss from nest eggs (MH2O) averaged 28 mg day-1, but also varied considerable within and between nests and did not correlate with changes in P1. MH2O increased 6-33% after the third day of incubation. PN was significantly higher and MH2O significantly lower in nests located in sheltered gullies than in nests from a windswept slope. These data suggest that Song Sparrows do not regulate PN to achieve hatching success.

Kern, Michael D.; Sogge, Mark K.; van Riper, Charles, III

1990-01-01

282

Modeling high-pressure vapor–liquid equilibrium of limonene, linalool and carbon dioxide systems  

Microsoft Academic Search

The research reported in this study is focused on modeling high-pressure phase behavior for CO2–limonene and CO2–linalool. A modified Peng–Robinson equation of state was applied to calculate vapor–liquid equilibrium using five different mixing rules obtained by incorporating activity coefficient models. The methodologies proposed by Heidemann–Kokal, Wong–Sandler and LCVM were used coupled with NRTL, UNIQUAC and UNIFAC models. A comparative analysis

S. A. B Vieira de Melo; G. M. N Costa; A. M. C Uller; F. L. P Pessoa

1999-01-01

283

Surface Passivation of Crystalline Silicon Solar Cells by Atmospheric Pressure Chemical Vapor Deposition  

Microsoft Academic Search

SiO2 films prepared by atmospheric pressure chemical vapor deposition (APCVD) were investigated for surface passivation of crystalline Si solar cells. The passivation effects of APCVD SiO2 for p-type Si substrates were evaluated by measuring excess minority carrier lifetimes. Effective surface recombination velocities S eff were decreased by successive annealing in N2 atmosphere at 300-700 degC without the degradation of the

Ryusuke Imai; Tsukasa Ishiwata; Hitoshi Sai; Naoya Yamamoto; Koji Arafune; Yoshio Ohshita; Masafumi Yamaguchi

2006-01-01

284

A solute vapor pressure study of complexes between benzene and caffeine in aqueous solutions  

Microsoft Academic Search

Highly precise vapor pressure-solubility measurements have been obtained for aqueous solutions of caffeine at temperatures\\u000a in the range 15 to 45C. Values of the fugacity of benzene at known total concentrations of benzene and caffeine have been\\u000a calculated and used to derive equilibrium constants for the interaction of benzene molecules with monomers and aggregates\\u000a of caffeine. Data are quite precisely

Edwin E. Tucker; Sherril D. Christian

1993-01-01

285

Vapor pressure of uranyl. beta. -diketonates. II. Adducts with dimethyl sulfoxide and hexamethyl phosphorotriamide  

Microsoft Academic Search

Adducts of uranyl pivaloylacetonate(I), dipivaloylmethanate(II), trifluoroacetylacetonate(III), and pivaloyltrifluoroacetonate(IV) with dimethyl sulfoxide (DMSO) and hexamethyl phosphorotriamide (HMPTA) were synthesized, and their behavior was studied under sublimation conditions. The vapor pressure of adducts of III and IV with DMSO and HMPTA, which practically do not dissociate on sublimation, was measured by the flow method. The results of the measurements are given below.

G. V. Sidorenko; D. N. Suglobov

2009-01-01

286

Characterization of the TIP4P-Ew water model: Vapor pressure and boiling point  

NASA Astrophysics Data System (ADS)

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3±1.9K, about 7K higher than the boiling point of TIP4P water (363.7±5.1K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

Horn, Hans W.; Swope, William C.; Pitera, Jed W.

2005-11-01

287

Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.  

PubMed

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. PMID:16321097

Horn, Hans W; Swope, William C; Pitera, Jed W

2005-11-15

288

Low pressure chemical vapor deposition of silicon carbide thin films from hexamethyldisilane  

Microsoft Academic Search

Silicon carbide thin films were grown by low pressure chemical vapor deposition using hexamethyldisilane Me3SiSiMe3 as the single-source precursor. Deposition of uniform thin films on Si(1 1 1) substrates was carried out at temperatures 1123-1323 K in a hot-wall reactor. The growth rates were 0.9-55 nm\\/min depending on the conditions employed. Estimated energy of activation is 110 kJ\\/mol. Bulk elemental

Hsin-Tien Chiu; Jen-Shiou Hsu

1994-01-01

289

Some possible filler alloys with low vapor pressures for refractory-metal brazing  

NASA Technical Reports Server (NTRS)

A compilation of eutectics and melting-point minima for binary combinations of metals having vapor pressures below 10 to the minus 10th power torr at 1500 degrees K and .00005 torr at 2000 degree K is presented. These compositions and others near them on their phase diagrams are potential special brazing fillers for refractory metals. Some possible problems and advantages for fusion bonds of such mixtures are indicated. Evaluations of brazing fillers containing refractory metals are reported.

Morris, J. F.

1973-01-01

290

AVO studies in Ketzin to discriminate fluid saturation and pore pressure related changes in 3D time-lapse data  

NASA Astrophysics Data System (ADS)

3D time-lapse seismic data were acquired at the Ketzin pilot CO2 storage site (a baseline (2005) and two repeat surveys (2009, 2012)). The CO2 injection started in 2008. Over 60 ktons of CO2 have been injected into a heterogeneous sandstones reservoir (saline aquifer) at a 650 m depth. Surface seismic can monitor CO2 at the Ketzin site. The time-lapse seismic signature has been interpreted as an anomaly caused by fluid saturation- related changes only. But CO2 injection must always decrease effective or differential reservoir pressure, because CO2 is injected at higher pressure than the original formation pore fluid pressure. We used AVO methods of Juhling&Young (1993) and Landro (2001) to discriminate between CO2-saturation- and pore-pressure- related effects in 3D time-lapse seismic data from Ketzin.

Ivanova, Alexandra; Bergmann, Peter; Yang, Can; Lüth, Stefan; Juhlin, Christopher

2013-04-01

291

Predictive models for estimating the vapor pressure of poly- and perfluorinated compounds at different temperatures  

NASA Astrophysics Data System (ADS)

Poly- and perfluorinated compounds (PFCs) are a class of global environmental pollutants that are of concern regarding their environmental fate and adverse effects. However, data on the basic physicochemical property of PFCs are still limited. To fill part of the data gaps, temperature-dependent predictive models for vapor pressure of PFCs were developed based on previously reported experimental data. The applicability domain of the models was analyzed using the Williams plot and the influential points and the response outliers were identified. The statistical performance of the models was significantly improved by removing these influential points and response outliers. This procedure confirmed the importance of properly defining the applicability domain of the predictive models. It is shown that the main factors governing the vapor pressure of PFCs, are intermolecular dispersive interactions, hydrogen bonding, temperature, intermolecular dipole-induced dipole interactions and dipole-dipole interactions. Although the model obtained could be used to reliably predict the vapor pressures of certain PFCs at different temperatures, it is essential that the prediction must fall within the applicability domain of the model and the temperature range for reliable predictions.

Ding, Guanghui; Shao, Mihua; Zhang, Jing; Tang, Junyi; Peijnenburg, Willie J. G. M.

2013-08-01

292

Methods of Measuring Vapor Pressures of Lubricants With Their Additives Using TGA and/or Microbalances  

NASA Technical Reports Server (NTRS)

The life of a space system may be critically dependent on the lubrication of some of its moving parts. The vapor pressure, the quantity of the available lubricant, the temperature and the exhaust venting conductance passage are important considerations in the selection and application of a lubricant. In addition, the oil additives employed to provide certain properties of low friction, surface tension, antioxidant and load bearing characteristics, are also very important and need to be known with regard to their amounts and vapor pressures. This paper reports on the measurements and analyses carried out to obtain those parameters for two often employed lubricants, the Apiezon(TM)-C and the Krytox(TM) AB. The measurements were made employing an electronic microbalance and a thermogravimetric analyzer (TGA) modified to operate in a vacuum. The results have been compared to other data on these oils when available. The identification of the mass fractions of the additives in the oil and their vapor pressures as a function of the temperature were carried out. These may be used to estimate the lubricant life given its quantity and the system vent exhaust conductance. It was found that the Apiezon(TM)-C has three main components with different rates of evaporation while the Krytox(TM) did not indicate any measurable additive.

Scialdone, John J.; Miller, Michael K.; Montoya, Alex F.

1996-01-01

293

In-reactor oxidation of zircaloy-4 under low water vapor pressures  

SciTech Connect

Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr- 4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

Walter G. Luscher; David J. Senor; Keven K. Clayton; Glen R. Longhurst

2015-01-01

294

In-reactor oxidation of zircaloy-4 under low water vapor pressures  

NASA Astrophysics Data System (ADS)

Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 °C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr-4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

2015-01-01

295

Vapor Pressure  

NSDL National Science Digital Library

This page is divided into several short sections, each focused on a specific topic such as evaporation or boiling point and each is accompanied by schematic illustrations of the process at the molecular level or a graph of the related variables.. Links to related topics are along the right hand side.

Nave, Carl R.

2010-01-01

296

Status of the CNRS-LCSR program on high pressure droplet vaporization and burning  

NASA Technical Reports Server (NTRS)

Depending on the surrounding flow and thermodynamic conditions, a single droplet may experience several gasification regimes, ranging from the envelope flame regime to pure vaporization. In practical situations, such as rocket propulsion or diesel combustion, the size distribution of droplets is, at best, bimodal, so that the possibility exists for the simultaneous presence of various regimes. For example, very small droplets are transported by the gas phase with zero relative velocity. This picture validates then the spherical symmetry hypothesis applied to the droplet and to the diffusion flame enveloping it. On the other hand, for larger droplets, a relative velocity exists due to drag forces. The most important influence of forced convection on droplet burning is the possibility to extinguish globally the envelope flame, or to establish a flame stabilized in the wake region. The burning rates of these regimes differ strongly. The characteristic time of droplet gasification is also influenced by the surrounding pressure and temperature. A parametric investigation of single droplet burning regimes is then helpful in providing the necessary physical ideas for sub-grid models used in spray combustion numerical prediction codes. The CNRS-LCSR experimental program on droplet vaporization and burning deals with these various regimes: stagnant and convective monocomponent droplet burning convective mono and bicomponent droplet vaporization; high temperature convective mono and biocomponent droplet vaporization; burning regimes of hydrazine and hydroxyl-ammonium-nitrate based monopropellant droplets and the vaporization regimes of liquid oxygen droplets. Studies on interacting droplets and on liquid aluminum droplets will start in the near future. The influence of high pressure is a common feature of all these studies. This paper summarizes the status of the CNRS-LCSR program on the effects of high pressure on monocomponent single droplet burning and vaporization, and some recent results obtained under normal and reduced gravity conditions with suspended droplets are presented. In the work described here, parabolic flights of an aircraft is used to create a reduced gravity environment of the order of 10(exp -2) g.

Chauveau, Christian; Goekalp, Iskender

1993-01-01

297

Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of three 4-substituted acetanilide derivatives  

Microsoft Academic Search

The vapor pressures of three 4-substituted acetanilide derivatives (namely, 4-ethoxyacetanilide, 4-hydroxyacetanilide and 4-bromoacetanilide) were measured above their liquids using the mass loss rates determined by thermogravimetry under both isothermal and nonisothermal diffusion-controlled conditions. The coefficient used to convert mass loss rates in vapor pressures showed a slight increase with increasing temperature. Therefore, the small deviations observed from the mean value

Stefano Vecchio; Mauro Tomassetti

2009-01-01

298

A rocking multianvil: elimination of chemical segregation in fluid-saturated high-pressure experiments  

NASA Astrophysics Data System (ADS)

Fluid saturated high-pressure experiments often result in strongly zoned experimental charges, this hinders experimentation in chemically homogeneous systems which in turn has serious consequences on equilibration, reaction progress, and (apparent) phase stabilities. In order to overcome these problems, a 600-ton press accommodating either a multianvil or end-loaded piston cylinder module has been mounted in such a way that it can be turned by 180°, thus inverting its position in the gravity field. During turning, hydraulic pressure, heating power, and cooling water remain connected allowing fully controlled pressures and temperatures during experiments. A series of experiments at 13 GPa, 950°C, on a serpentine bulk composition in the MgO-SiO 2-H 2O system demonstrates that continuous turning at a rate of 2 turns/min results in a nearly homogeneous charge composed of phase E + enstatite. The same experiment at static conditions resulted in four mineral zones: quench phase E, enstatite, enstatite + phase E, and phase E + phase A. Phase A disappears in experiments at a turning rate ?1 turn/min. A static 15-min experiment shows that zonation already forms within this short time span. Placing two short capsules within a single static experiment reveals that the fluid migrates to the hot spot in each capsule and is not gravitationally driven toward the top. The zonation pattern follows isotherms within the capsule, and the degree of zonation increases with temperature gradient (measured as 10 °C within a capsule) and run time. Our preferred interpretation is that Soret diffusion causes a density-stratified fluid within the capsule that does not convect in a static experiment and results in temperature dependant chemical zonation. The aggravation of zonation and appearance of additional phases with run time can be explained with a dissolution-reprecipitation process where the cold spot of the capsule is relatively MgO enriched and the hot spot relatively SiO 2 and H 2O enriched (at 13 GPa and 950°C). Rocking and tilting of a stratified fluid induces Rayleigh-Taylor instabilities, causing chemical rehomogenization. If turning is faster than the time required to build significant chemical potential gradients in the fluid, chemical zonation in the distribution of the solids is suppressed.

Schmidt, Max W.; Ulmer, Peter

2004-04-01

299

A comparison of strategies for imputing saturated pressure array data with application to the wheelchair-seating interface.  

PubMed

Abstract Purpose: The common responses to pressure sensor saturation are extreme: either discarding of data, or wholesale alteration of experimental protocol. Here, we test four simplistic strategies for restoring missing data due to sensor saturation, avoiding such drastic measures. Methods: We tested these algorithms on 62 pressure maps collected from 42 individuals (20 M/22 F, 54.1?±?26.2 years, 1.7?±?0.1?m, 71.9?±?17.8?kg) under a variety of seating conditions. These strategies were tested via a cross-validation design, censoring the maximum pressure value in the datasets and measuring prediction error. Results: The four strategies showed various prediction error rates: ??=?0.43?±?0.14 (simple substitution), ??=?0.16?±?0.21 (scaled substitution), ??=?0.19?±?0.21 (feature extraction), and ??=?0.24?±?0.32 (extrapolation by non-linear modeling). Conclusion: For single-sensor saturation, it may be possible to restore missing data using simple techniques. Implications for Rehabilitation We present a method for imputing missing data from pressure sensor arrays. The implications for rehabilitation are as follows. Improved flexibility in design of protocols concerning interfacial pressure measurement. Restoration of missing data from existing datasets. Reduction in recruitment burden for future studies. Reduction in exposure risk to study participants. PMID:25203501

Wininger, Michael; Crane, Barbara

2014-09-01

300

Influence of change in physical state on elastic nonlinear response in rock: Significance of effective pressure and water saturation  

NASA Astrophysics Data System (ADS)

We describe Young's mode resonant bar results obtained under effective pressure at two saturation states: dry and water saturated. We monitor primary manifestations of nonlinear response in these experiments: the harmonic content, the source extinction intensity, and fundamental resonant frequency shift. In addition, we describe the hysteretic behavior of the static pressure response, the linear modulus, and Q. Because we currently lack a complete theoretical description of nonlinear behavior under resonance at pressure, we provide relative measures of nonlinear response rather than absolute values. The rocks include Fontainebleau and Meule sandstones and Lavoux limestone. Dynamic strain levels range from 10-8 to 10-5 and frequencies range from 1 to 10 kHz. The elastic nonlinear response of each of the rocks is markedly different over the range of physical property states explored. The different responses are related to differences in mechanical response resulting from rock type, grain cement type, etc. In all of the samples studied, the change in resonant frequency as a function of excitation intensity is not measurable above approximately 10 MPa; however, harmonics are observed at larger effective pressure levels. Hysteresis in velocity and Q versus pressure vary considerably between the rocks. The effect of Q on the experiments is marked. When Q is low (<10) as for some saturated samples, relative excitations must be large in order to induce equivalent dry sample strains.

Zinszner, Bernard; Johnson, Paul A.; Rasolofosaon, Patrick N. J.

1997-04-01

301

Pressure intelligent control strategy of Waste heat recovery system of converter vapors  

NASA Astrophysics Data System (ADS)

The converter gas evaporative cooling system is mainly used for absorbing heat in the high temperature exhaust gas which produced by the oxygen blowing reaction. Vaporization cooling steam pressure control system of converter is a nonlinear, time-varying, lagging behind, close coupling of multivariable control object. This article based on the analysis of converter operation characteristics of evaporation cooling system, of vaporization in a production run of pipe pressure variation and disturbance factors.For the dynamic characteristics of the controlled objects,we have improved the conventional PID control scheme.In Oxygen blowing process, we make intelligent control by using fuzzy-PID cascade control method and adjusting the Lance,that it can realize the optimization of the boiler steam pressure control.By design simulation, results show that the design has a good control not only ensures drum steam pressure in the context of security, enabling efficient conversion of waste heat.And the converter of 1800 flue gas through pipes and cool and dust removal also can be cooled to about 800. Therefore the converter haze evaporative cooling system has achieved to the converter haze temperature decrease effect and enhanced to the coal gas returns-ratio.

Feng, Xugang; Wu, Zhiwei; Zhang, Jiayan; Qian, Hong

2013-01-01

302

Thermochemical and Vapor Pressure Behavior of Anthracene and Brominated Anthracene Mixtures  

PubMed Central

The present work concerns the thermochemical and vapor pressure behavior of the anthracene (1) + 2-bromoanthracene (2) and anthracene (1) + 9-bromoanthracene (3) systems. Solid-liquid equilibrium temperature and differential scanning calorimetry studies indicate the existence of a minimum melting solid state near an equilibrium temperature of 477.65 K at x1 = 0.74 for the (1) + (2) system. Additionally, solid-vapor equilibrium studies for the (1) + (2) system show that the vapor pressure of the mixtures depends on composition, but does not follow ideal Raoult’s law behaviour. The (1) + (3) system behaves differently from the (1) + (2) system. The (1) + (3) system has a solid solution like phase diagram. The system consists of two phases, an anthracene like phase and a 9-bromoanthracene like phase, while (1) + (2) mixtures only form a single phase. Moreover, experimental studies of the two systems suggest that the (1) + (2) system is in a thermodynamically lower energy state than the (1) + (3) system. PMID:24319314

Suuberg, Eric M.

2013-01-01

303

Low-Temperature Vapor Pressures of Selected C_1, C_2, and C_3 Hydrocarbons  

NASA Astrophysics Data System (ADS)

Light hydrocarbons play important roles in the development of atmospheres, clouds, and hazes in the outer planets and some of their satellites. The first-order equilibrium and photochemical models developed to describe these systems require accurate laboratory data as inputs. It is important that these data are acquired over the appropriate range of atmospheric parameters, e.g., temperature, and in this regard there is a particular need for vapor pressures of molecular constituents at low temperatures. We have developed an apparatus capable of providing this extremely limited information and have undertaken a program to systematically determine the thermodynamic properties of molecules and mixtures of importance to the planetary atmospheres community. Previously we reported results for ethylene and propane (Nelson, Allen, and Harris 1997) and methane and monodeuterated methane (Allen and Nelson 1998). In our continuing efforts to supply these needed data, we update our list of low-temperature vapor pressures for light hydrocarbons by reporting here the experimentally determined vapor pressure of acetylene from 0.3 to 8x10(-6) torr, corresponding to temperatures from 124 to 84 K, respectively. This extends the available measured data for this molecule by over two orders of magnitude in pressure. Nelson, R. N., Allen, J. E., Jr., and Harris, B. C., Sr. 1997, B.A.A.S. {bf 29}, 1009. Allen, J. E., Jr. and Nelson, R. N. 1998, to appear in Proc. of the NASA Laboratory Space Science Workshop (Cambridge: Harvard-Smithsonian). RNN is a summer faculty researcher from the Department of Chemistry, Georgia Southern University.

Allen, J. E., Jr.; Nelson, R. N.

1998-09-01

304

Partial Pressures of In-Se from Optical Absorbance of the Vapor  

NASA Technical Reports Server (NTRS)

The optical absorbance of the vapor phase over various In-Se compositions between 33.3 and 61 atomic percent and 673 and 1418K has been measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gage measurements for compositions between 50 and 61 atomic percent but significantly higher than those from Knudsen cell and simultaneous Torsion-Knudsen cell measurements. The sequiselenide is found to sublime incongruently. Congruent vaporization occurs for the liquid above 1000 K between 50.08 and 56 at. percent Se. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000 and 1300K is essentially independent of temperature and falls between -36 and -38 kJ per gram atomic weight for 50 and 56 percent Se at 1200 and 1300K.

Brebrick, R. F.; Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

2001-01-01

305

Vapor pressure isotope fractionation effects in planetary atmospheres: application to deuterium  

E-print Network

The impact of the vapor pressure difference between deuterated and nondeuterated condensing molecules in planetary atmospheres is quantitatively assessed. This difference results in a loss of deuterium in the vapor phase above the condensation level. In Titan, Uranus and Neptune, the effect on CH3D is too subtle to alter current D/H ratio determinations. In Mars, the effect can induce a large depletion of HDO, starting about one scale height above the condensation level. Although the current infrared measurements of the D/H ratio appear to be almost unaffected, the intensity of disk-averaged millimetric HDO lines can be modified by about 10%. The effect is much stronger in limb sounding, and can be easily detected from orbiter observations.

Thierry Fouchet; Emmanuel Lellouch

1999-11-15

306

Highly ionized physical vapor deposition plasma source working at very low pressure  

NASA Astrophysics Data System (ADS)

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti+ and Ti++ peaks are observed in the mass scan spectra). This corresponds well with high plasma density ne ˜ 1018 m-3, measured during the HiPIMS pulse.

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Cada, M.; Hubicka, Z.; Tichy, M.; Hippler, R.

2012-04-01

307

Highly ionized physical vapor deposition plasma source working at very low pressure  

SciTech Connect

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti{sup +} and Ti{sup ++} peaks are observed in the mass scan spectra). This corresponds well with high plasma density n{sub e} {approx} 10{sup 18} m{sup -3}, measured during the HiPIMS pulse.

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Hippler, R. [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Cada, M.; Hubicka, Z. [Institute of Physics v. v. i., Academy of Science of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Tichy, M. [Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, 180 00 Prague (Czech Republic)

2012-04-02

308

UNCORRECTEDPROOF Please cite this article in press as: D. Lipkind et al., The vaporization enthalpies and vapor pressures of a series of unsaturated fatty acids methyl  

E-print Network

enthalpies and vapor pressures of a series of unsaturated fatty acids methyl esters by correlation gas fatty acids methyl esters by correlation gas chromatography 3 4 Dmitry Lipkind1, Yaroslav Kapustin1,8,11,14-eicosatetraeneoate), methyl Z,Z,Z,Z,Z 5,8,11,14,17-eicosapentaeneoate, methyl erucate (methyl Z 13-docosaneoate

Chickos, James S.

309

Surface roughening in low-pressure chemical vapor deposition Jason T. Drotar, Y.-P. Zhao, T.-M. Lu, and G.-C. Wang  

E-print Network

Surface roughening in low-pressure chemical vapor deposition Jason T. Drotar, Y.-P. Zhao, T.-M. Lu etching, the pressure is usually low enough so that the mean free path of the vapor particles is much of a reemission model for chemical vapor deposition. We find that, for pure first-order reemission, the interface

Wang, Gwo-Ching

310

Effect of temperature and iron-oxide nano-particle inclusions on the ultrasound vaporization pressure of perfluorocarbon droplets for disease detection and therapy  

E-print Network

Iron-Oxide Nano-particle inclusions on the Ultrasound Vaporization Pressure of Perfluorocarbon Droplets for Disease DetectionIron-Oxide Nano-particle inclusions on the Ultrasound Vaporization Pressure of Perfluorocarbon Droplets for Disease Detectioniron oxide nanoparticle loaded emulsions36. 2.3.2 Acoustic droplet vaporization and microbubble detection.

Amirriazi, Seyed Saleh

2009-01-01

311

On optimum interstage pressure for two-stage and mechanical-subcooling vapor-compression refrigeration cycles  

SciTech Connect

The objective of the present study is to demonstrate that the optimum interstage pressure for a two-stage refrigeration system can be approximated by the saturation pressure corresponding to the arithmetic mean of the condensing and evaporating temperatures. It is also shown that the optimum performance of a refrigeration system with mechanical sub-cooling occurred when the subcooler compressor (saturation suction) temperature corresponds to the arithmetic mean of the condensing and evaporating temperatures.

Zubair, S.M.; Khan, S.H. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Mechanical Engineering

1995-02-01

312

Solubility parameter and activity coefficient of HDEHP dimer in select organic diluents by vapor pressure osmometry  

SciTech Connect

A thorough understanding of the non-ideal behavior of the chemical components utilized in solvent extraction contributes to the success of any large-scale spent nuclear fuel treatment. To address this, our current work uses vapor pressure osmometry to characterize the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), a common extractant in proposed separation schemes. Solubility parameters were fit to data on HDEHP at four temperatures using models based on Scatchard Hildebrand regular solution theory with Flory Huggins entropic corrections. The results are comparable but not identical to the activity coefficients from prior slope analysis in the literature. (authors)

Gray, M.; Nilsson, M. [University of California Irvine, 916 Engineering Tower, UC Irvine, Irvine, CA 92697-2575 (United States); Zalupski, P. [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)

2013-07-01

313

Synthesis of crystalline boron nanoribbons and calcium hexaboride nanowires by low pressure chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Low pressure chemical vapor deposition was used to synthesize crystalline boron nanoribbons of 16 nm thickness by both uncatalyzed and nickel-catalyzed pyrolysis of diborane at relatively low temperatures. The nanoribbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and Raman spectroscopy. Similar procedures were used to synthesize and characterize calcium hexaboride nanowires. The nanostructures reported here are compared with recent literature results for boron nanoribbons and CaB6 nanowires grown by the same method.

Jash, Panchatapa; Trenary, Michael

2009-06-01

314

Oxalate Ion Decomposition under UV Light from Low Pressure Mercury Vapor Lamps  

Microsoft Academic Search

Kinetics of oxalate ion decomposition under UV light from low pressure mercury vapor lamps (LPMVL) was studied in a batch reactor. The effects of UV light intensity (1.38×10 to 5.27×10 ELs, where E: Einstein or 1 mole of photons), temperature (15?35°C), initial oxalate concentration ((2.05?21.1)?×?10 M), initial pH (5.45?8.94) and alkalinity (0–50 mg L as CaCO3) on the photodecomposition kinetics

Gonca F. Talu; Vasil Diyamandoglu; Urs Jans

2007-01-01

315

A vapor-pressure study of the systems formed by polonium with palladium and iridium  

SciTech Connect

Direct thermal vacuum synthesis shows that polonium vapor does not react with iridium when they are heated together to 1000/sup 0/C. Polonium vapor begins to be absorbed appreciably by palladium at 340-350/sup 0/C. The radiotensimetric method has been used in examining the thermal stabilities of polonium-palladium comounds, which has shown that there are three intermetallides PdPo, Pd/sub 2/Po, and Pd/sub 3/Po, which dissociate to release elemental polonium. The dissociation temperature increases as the polonium content of the compound decreases and is in the range 390-700/sup 0/C. The temperature dependence of the polonium vapor pressure in the dissociation is described by the following: PdPo log P /SUB Pa/ = (7.31 + or - 0.08) -- (4520 + or -40)/T, and at 460580/sup 0/C, ..delta..H = 86.3 + or - 0.7 kJ/mol; Pd/sub 2/Po log P /SUB Pa/ = (7.42 + or - 0.01) -- (6080 + or 10)/T at 725900/sup 0/C, ..delta..H = 116 + or - 0.2 kJ/mol; Pd/sub 3/Po log P /SUB Pa/ = (9.18 + or - 0.01) -- (8620 + or 1000/sup 0/C, ..delta..H = 164 + or - 1 kJ/mol. The properties of these compounds are compared with those of the corresponding tellurides and of the polonium-nickel and poloniumplatinum systems.

Abakumou, A.S.; Khokhlou, A.D.; Malysheu, M.L.; Reznikova, N.F.

1985-11-01

316

Continuum reaction field calculation of dielectric constant and vapor pressures for water and carbon disulfide.  

PubMed Central

Continuum reaction field theory is applied to calculations of dielectric constant, contribution of intermolecular interactions to the free energy of a liquid, and heat of vaporization. Introduction of repulsive interactions and the use of one adjustable parameter, the free volume, enables prediction of vapor pressures. The calculations are illustrated for a simple nonpolar liquid, carbon disulfide, and for liquid water. It is shown that when Onsager's equation is rearranged to a quadratic equation, and a recently found value of the polarizability is employed, its solutions for liquid water yield good agreement with experimental values throughout the whole temperature range. The decrease of the dielectric constant with temperature is essentially linear with the inverse of absolute temperature, but there is additional significant decrease due to the decrease of density with temperature. The relatively high value of the heat of vaporization of liquid water is expressed in terms of large dipolar interaction of a water molecule with the environment, which is due to polarization effects. PMID:1244889

Nir, S

1976-01-01

317

Vapors and Droplets Mixture Deposition of Metallic Coatings by Very Low Pressure Plasma Spraying  

NASA Astrophysics Data System (ADS)

In recent years, the very low pressure plasma-spraying (VLPPS) process has been intensely developed and implemented to manufacture thin, dense and finely structured ceramic coatings for various applications, such as Y2O3 for diffusion barriers, among other examples. This paper aims at presenting developments carried out on metallic coatings. Aluminum was chosen as a demonstrative material due to its "moderate" vaporization enthalpy (i.e., 38.23 KJ cm-3) compared to the one of copper (i.e., 55.33 KJ cm-3), cobalt (i.e., 75.03 KJ cm-3), or even tantalum (i.e., 87.18 KJ cm-3). The objective of this work is primarily to better understand the behavior of a solid precursor injected into the plasma jet leading to the formation of vapors and to better control the factors affecting the coating structure. Nearly dense aluminum coatings were successfully deposited by VLPPS at 100 Pa with an intermediate power plasma torch (i.e., Sulzer Metco F4 type gun with maximum power of 45 kW). Optical emission spectroscopy (OES) was implemented to study and analyze the vapor behavior into the plasma jet. Simplified CFD modeling allowed better understanding of some of the thermo-physical mechanisms. The effect of powder-size distribution, substrate temperature and spray distance were studied. The phase composition and microstructural features of the coatings were characterized by XRD and SEM. Moreover, Vickers microhardness measurements were implemented.

Vautherin, B.; Planche, M.-P.; Bolot, R.; Quet, A.; Bianchi, L.; Montavon, G.

2014-04-01

318

Phase evolution in low-pressure Se vapor selenization of evaporated Cu/In bilayer precursors  

NASA Astrophysics Data System (ADS)

Evolution of elemental binaries and single-phase copper indium diselenide, CuInSe2 (CIS) during Se vapor selenization of evaporated Cu/In bilayer metal precursors at pressures of 0.3-10 mbar and temperatures in the range of 260-400 °C has been investigated. At low pressures, the relative kinetics of selenization of Cu and In are changed resulting in the formation of single-phase CIS even at very low temperatures (260 °C). Optical, Auger, and x-ray photoelectron spectroscopy investigations are employed to characterize the chalcopyrite absorber layer. At higher pressures (?7-10 mbar), simultaneous formation of the equilibrium binaries, CuSe and In2Se3 at low temperatures leads to the formation of CIS through a diffusion limited reaction of the binaries at higher temperatures. The availability of Se reacting species varies significantly in the pressure regime. At low reactor pressures and Se availability, the reaction CuSe+In(l)+Se?CIS, proceeds to completion even at low temperatures. The detailed study of the phase evolution is made by x-ray diffraction and scanning electron microscopy investigations and correlated with the Se availability in the reactor.

Lakshmikumar, S. T.; Rastogi, A. C.

1996-04-01

319

Pressure drop in fully developed, turbulent, liquid-vapor annular flows in zero gravity  

NASA Technical Reports Server (NTRS)

The prediction of frictional pressure drop in fully developed, turbulent, annular liquid-vapor flows in zero gravity using simulation experiments conducted on earth is described. The scheme extends the authors' earlier work on dispersed flows. The simulation experiments used two immiscible liquids of identical density, namely, water and n-butyl benzoate. Because of the lack of rigorous analytical models for turbulent, annular flows, the proposed scheme resorts to existing semiempirical correlations. Results based on two different correlations are presented and compared. Others may be used. It was shown that, for both dispersed and annular flow regimes, the predicted frictional pressure gradients in 0-g are lower than those in 1-g under otherwise identical conditions. The physical basis for this finding is given.

Sridhar, K. R.; Chao, B. T.; Soo, S. L.

1992-01-01

320

Effect of Hydrogen in Size-Limited Growth of Graphene by Atmospheric Pressure Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Analysis of graphene domain synthesis explains the main graphene growth process. Size-limited graphene growth caused by hydrogen is studied to achieve efficient graphene synthesis. Graphene synthesis on Cu foils via the chemical vapor deposition method using methane as carbon source is limited by high hydrogen concentration. Results indicate that hydrogen affects graphene nucleation, the growth rate, and the final domain size. Considering the role of hydrogen as both activator and etching reagent, we build a model to explain the cause of this low graphene growth rate for high hydrogen partial pressure. A two-step method is proposed to control the graphene nucleation and growth rate separately. Half the time is required to obtain similar domain size compared with single-step synthesis, indicating improved graphene synthesis efficiency. The change of the partial pressure and transmission time between the two steps is a factor that cannot be ignored to control the graphene growth.

Zhang, Haoran; Zhang, Yanhui; Wang, Bin; Chen, Zhiying; Sui, Yanping; Zhang, Yaqian; Tang, Chunmiao; Zhu, Bo; Xie, Xiaoming; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

2015-01-01

321

Fungicide volatilization measurements: inverse modeling, role of vapor pressure, and state of foliar residue.  

PubMed

Few data sets of pesticide volatilization from plants at the field scale are available. In this work, we report measurements of fenpropidin and chlorothalonil volatilization on a wheat field using the aerodynamic gradient (AG) method and an inverse dispersion modeling approach (using the FIDES model). Other data necessary to run volatilization models are also reported: measured application dose, crop interception, plant foliage residue, upwind concentrations, and meteorological conditions. The comparison of the AG and inverse modeling methods proved the latter to be reliable and hence suitable for estimating volatilization rates with minimized costs. Different diurnal/nocturnal volatilization patterns were observed: fenpropidin volatilization peaked on the application day and then decreased dramatically, while chlorothalonil volatilization remained fairly stable over a week-long period. Cumulated emissions after 31 h reached 3.5 g ha(-1) and 5 g ha(-1), respectively (0.8% and 0.6% of the theoretical application dose). A larger difference in volatilization rates was expected given differences in vapor pressure, and for fenpropidin, volatilization should have continued given that 80% of the initial amount remained on plant foliage for 6 days. We thus ask if vapor pressure alone can accurately estimate volatilization just after application and then question the state of foliar residue. We identified adsorption, formulation, and extraction techniques as relevant explanations. PMID:20199019

Bedos, Carole; Rousseau-Djabri, Marie-France; Loubet, Benjamin; Durand, Brigitte; Flura, Dominique; Briand, Olivier; Barriuso, Enrique

2010-04-01

322

Trends in odor intensity for human and electronic noses: relative roles of odorant vapor pressure vs. molecularly specific odorant binding.  

PubMed

Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electronic nose detectors were essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant's vapor pressure. A similar trend is observed in human odor detection threshold values for these same homologous series of odorants. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorant's vapor pressure. Similarly, the data are consistent with the hypothesis that the odor detection thresholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant concentrations sorbed into the olfactory epithelium at a constant fraction of the odorant's vapor pressure. PMID:9576901

Doleman, B J; Severin, E J; Lewis, N S

1998-05-12

323

Trends in odor intensity for human and electronic noses: Relative roles of odorant vapor pressure vs. molecularly specific odorant binding  

PubMed Central

Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electronic nose detectors were essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant’s vapor pressure. A similar trend is observed in human odor detection threshold values for these same homologous series of odorants. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorant’s vapor pressure. Similarly, the data are consistent with the hypothesis that the odor detection thresholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant concentrations sorbed into the olfactory epithelium at a constant fraction of the odorant’s vapor pressure. PMID:9576901

Doleman, Brett J.; Severin, Erik J.; Lewis, Nathan S.

1998-01-01

324

A unified equation for calculating methane vapor pressures in the CH4-H2O system with measured Raman shifts  

USGS Publications Warehouse

A unified equation has been derived by using all available data for calculating methane vapor pressures with measured Raman shifts of C-H symmetric stretching band (??1) in the vapor phase of sample fluids near room temperature. This equation eliminates discrepancies among the existing data sets and can be applied at any Raman laboratory. Raman shifts of C-H symmetric stretching band of methane in the vapor phase of CH4-H2O mixtures prepared in a high-pressure optical cell were also measured at temperatures between room temperature and 200 ??C, and pressures up to 37 MPa. The results show that the CH4 ??1 band position shifts to higher wavenumber as temperature increases. We also demonstrated that this Raman band shift is a simple function of methane vapor density, and, therefore, when combined with equation of state of methane, methane vapor pressures in the sample fluids at elevated temperatures can be calculated from measured Raman peak positions. This method can be applied to determine the pressure of CH4-bearing systems, such as methane-rich fluid inclusions from sedimentary basins or experimental fluids in hydrothermal diamond-anvil cell or other types of optical cell. ?? 2007 Elsevier Ltd. All rights reserved.

Lu, W.; Chou, I.-M.; Burruss, R.C.; Song, Y.

2007-01-01

325

Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers  

NASA Astrophysics Data System (ADS)

Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

2015-01-01

326

What is the significance of pore pressure in a saturated shale layer?  

Microsoft Academic Search

Electrostatic interactions, associated with negatively charged surfaces of clay minerals, produce a so-called “disjoining pressure” when diffuse layers overlap, i.e., at low porosity. Disjoining pressure is the pressure difference between the water in the clay pore space and that in a bulk solution at the same depth. Another widely used concept in clay-rocks is the “swelling pressure.” It corresponds in

J. Gonçalvès; P. Rousseau-Gueutin; G. de Marsily; P. Cosenza; S. Violette

2010-01-01

327

AA Parametric Model for Predicting Relative Permeability-Saturation-Capillary Pressure Relationships of Oil?Water Systems in Porous Media with Mixed Wettability  

SciTech Connect

A parametric two-phase, oil-water relative permeability/capillary pressure model for petroleum engineering and environmental applications is developed for porous media in which the smaller pores are strongly water-wet and the larger pores tend to be intermediate- or oil-wet. A saturation index, which can vary from 0 to 1, is used to distinguish those pores that are strongly water-wet from those that have intermediate- or oil-wet characteristics. The capillary pressure submodel is capable of describing main-drainage and hysteretic saturation-path saturations for positive and negative oil-water capillary pressures. At high oil-water capillary pressures, an asymptote is approached as the water saturation approaches the residual water saturation. At low oil-water capillary pressures (i.e., negative), another asymptote is approached as the oil saturation approaches the residual oil saturation. Hysteresis in capillary pressure relations, including water entrapment, is modeled. Relative permeabilities are predicted using parameters that describe main drainage capillary pressure relations and accounting for how water and oil are distributed throughout the pore spaces of a porous medium with mixed wettability. The capillary pressure submodel is tested against published experimental data, and an example of how to use the relative permeability/capillary pressure model for a hypothetical saturation-path scenario involving several imbibition and drainage paths is given. Features of the model are also explained. Results suggest that the proposed model is capable of predicting relative permeability/capillary pressure characteristics of porous media mixed wettability.

Lenhard, Robert J.(INEEL) [INEEL; Oostrom, Mart (BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

1998-01-01

328

Vapor pressures and heats of sublimation of crystalline ?-cellobiose from classical molecular dynamics simulations with quantum mechanical corrections.  

PubMed

In this paper, we report the calculation of the enthalpy of sublimation, ?(sub)H, as a function of temperature of crystalline ?-cellobiose from molecular dynamics (MD) simulations, using two popular carbohydrate force fields. Together with the entropy difference between the solid and the vapor, ?S, evaluated at atmospheric pressure, ?(sub)H gives the vapor pressure of cellobiose over the solid phase as a function of T. It is found that when quantum mechanical corrections to the enthalpy calculated from the distribution of normal modes is applied both force fields give ?(sub)H close to experiments. The entropy change, ?S, which is calculated within a harmonic approximation becomes too small, leading to vapor pressures that are too low. These findings are relevant to MD simulations of crystalline carbohydrates in general, e.g., native cellulose. PMID:24784815

Wohlert, Jakob

2014-05-22

329

The separation and characterization of a hydrogen getter product mixture: Part 2, measurement of product vapor pressures  

SciTech Connect

HCPB is the acronym of an organic hydrogen getter compound used in weapon systems. When this material scavenges hydrogen by reacting with it, a number of compounds are formed, each of which is more volatile than HCPB. It is desirable to know the vapor pressure of these products in order to assess their migration potential within the weapon. In this study, individual compounds from a reacted HCPB mixture were isolated and their vapor pressures were measured. Three of the four fractions examined with a modified capacitance manometer were found to have vapor pressures under 1 mtorr; the fourth was measured at 92 +- 15 mtorr. An attempt was made to obtain boiling point data on the two liquid components of the getter mixture, but they decomposed before reaching their boiling points.

Fircish, D.W.; Shell, T.R.

1987-06-04

330

Detection and measurement of sulfur mustard (HD) offgassing from the weanling pig following exposure to saturated HD vapor. Technical report, September-October 1994  

SciTech Connect

Sulfur mustard (HD) is a chemical warfare agent for which there is neither antidote nor adequate therapeutic protection. Animal models are employed to investigate mechanisms of injury and to evaluate protective measures against HD exposure. Researchers whose experiments involve cutaneous application of HD vapor to animals benefit from the detection and quantitation of HD at the exposed site. The ability to detect and quantify HD enables the researcher to follow safe procedures in handling skin samples. We have designed an experimental procedure to measure HD offgassing from animal models. A Minicams(R), which is a portable gas chromatograph (GC) equipped with a flame photometric detector (FPD) and with online sorbent collection and desorption, was used to monitor the HD concentration. Confirming measurements were made using a two-step process that trapped HD on a Tenax sorbent offline and then transferred the sample by means of an ACEM 900 to a OC equipped with either FPD or a mass spectrometer (MS). We collected data from six experiments in which weanling pigs were exposed to saturated HD vapor via vapor caps containing 10 micro of HD. HD concentration was measured in time-weighted-average (TWA) units at a specific HD application site. The currently recommended exposure value for HD is 3 ng/l, 1 TWA unit. In five of the six experiments, Minicams HD concentration values were less than 0.5 TWA, 2 hours postexposure, and in one of the experiments, TWA Minicams concentration was less than 0.5 TWA, 5 hours post-exposure. OCIMS detection was used in three of the experiments to confirm Minicams data and to provide greater sensitivity and selectivity at 0.1 TWA. GC/MS data confirmed that HD concentrations fell below 0.1 TWA in less than S hours for a specific site.

Logan, T.P.; Graham, J.S.; Martin, J.L.; Zallnick, J.E.; Jakubowski, E.M.

1997-11-01

331

Evaluation of the electrode method for measuring H/sub 2/S vapor pressure over alkanolamine solutions  

SciTech Connect

A new electrode method for measuring the equilibrium vapor pressure of H/sub 2/S over any sulfide solution was tested. The method relates the electropotential difference produced between pH and silver/sulfide ion specific electrodes to the H/sub 2/S equilibrium vapor pressure of solution. The experimental technique is simple and time efficient. In this work, H/sub 2/S equilibrium vapor pressures were measured from 10/sup -4/ kPa to 10 kPa at 25/sup 0/C in aqueous solutions of monoethanolamine-MEA (2.5 N), diethanolamine-DEA (2.0N), and methyldiethanolamine-MDEA (1.0 N and 4.28 N). The H/sub 2/S vapor-liquid equilibria (VLE) of 4.28 N MDEA was also examined at 40/sup 0/C. The results indicate that the addition of MEA to a MDEA solution reduces the H/sub 2/S vapor pressure only at low H/sub 2/S loadings.

Austgen, D.M.; Rochelle, G.T.

1987-01-01

332

On the analyses of mixture vapor pressure data: the hydrogen peroxide/water system and its excess thermodynamic functions.  

PubMed

Reported here are some aspects of the analysis of mixture vapor pressure data using the model-free Redlich-Kister approach that have heretofore not been recognized. These are that the pure vapor pressure of one or more components and the average temperature of the complex apparatuses used in such studies can be obtained from the mixture vapor pressures. The findings reported here raise questions regarding current and past approaches for analyses of mixture vapor pressure data. As a test case for this analysis approach the H2O2-H2O mixture vapor pressure measurements reported by Scatchard, Kavanagh, and Tickner (G. Scatchard, G. M. Kavanagh, L. B. Ticknor, J. Am. Chem. Soc. 1952, 74, 3715-3720; G. M. Kavanagh, PhD. Thesis, Massachusetts Institute of Technology (USA), 1949) have been used; there is significant recent interest in this system. It was found that the original data is fit far better with a four-parameter Redlich-Kister excess energy expansion with inclusion of the pure hydrogen peroxide vapor pressure and the temperature as parameters. Comparisons of the present results with the previous analyses of this suite of data exhibit significant deviations. A precedent for consideration of iteration of temperature exists from the little-known work of Uchida, Ogawa, and Yamaguchi (S. Uchida, S. Ogawa, M. Yamaguchi, Japan Sci. Eng. Sci. 1950, 1, 41-49) who observed significant variations of temperature from place to place within a carefully insulated apparatus of the type traditionally used in mixture vapor pressure measurements. For hydrogen peroxide, new critical constants and vapor pressure-temperature equations needed in the analysis approach described above have been derived. Also temperature functions for the four Redlich-Kister parameters were derived, that allowed calculations of the excess Gibbs energy, excess entropy, and excess enthalpy whose values at various temperatures indicate the complexity of H2O2-H2O mixtures not evident in the original analyses of this suite of experimental results. PMID:15551324

Manatt, Stanley L; Manatt, Margaret R R

2004-12-01

333

Germanium determination by flame atomic absorption spectrometry: an increased vapor pressure-chloride generation system.  

PubMed

A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl(4)). In order to do so, a novel joint vapor production and gas-liquid separation unit equipped with a home-made oven was incorporated to an ordinary nitrous oxide-acetylene flame atomic absorption spectrometer. Several variables such as reaction time, temperature and acid concentration have been investigated. The linear range for germanium determination was 0.1-10 ng mL(-1) for 1 mL sampling volume with a detection limit (3s) of 0.01 ng mL(-1). The relative standard deviation (RSD) was 2.4% for nine replicates of a 1 ng mL(-1) germanium solution. The method was validated by the analysis of one non-certified and two certified geochemical reference materials, respectively, CRM GSJ-JR-2 (Rhyolite), and GSJ-JR-1 (Rhyolite), and GBW 07107 (Chinese Rock). Selectivity of the method was investigated for Cd(2+), Co(2+), Cu(2+), Fe(3+), Ga(3+), Hg(2+), Ni(2+), Pb(2+), Sn(2+), and Zn(2+) ions and ionic species of As(III), Sb(III), Te(IV), and Se(IV). PMID:21315908

Kaya, Murat; Volkan, Mürvet

2011-03-15

334

The Vapor Pressure of Palladium at Temperatures up to 1973K  

NASA Technical Reports Server (NTRS)

Understanding high-temperature processes is imperative for modeling the formation of the solar system. It is unfortunate that since the 1950 s little has been done in the area of thermodynamics to continue gaining information on metals such as iron (Fe), nickel (Ni), cobalt (Co), palladium (Pd) and many others. Although the vapor pressures of these metals can be extrapolated to higher temperatures, the data is often limited to temperature ranges too low to be applicable to processes that occur during the formation of the solar system (T approx. 2000K). Experimental techniques inhibited the data in the past by restricting the testing of metals to temperatures below their melting point. Today, higher temperature testing is possible by using a Thermo- Cahn Thermogravimetric system that is able to reach temperatures up to 1973K in vacuo and measure a 10 gram change in a sample with mass of up to 100 grams.

Gardner, K. G.; Feguson, F. T.; Nuth, J. A.

2005-01-01

335

The Action of Pressure-Radiation Forces on Pulsating Vapor Bubbles  

NASA Technical Reports Server (NTRS)

The action of pressure-radiation (or Bjerknes) forces on gas bubbles is well understood. This paper studies the analogous phenomenon for vapor bubbles, about which much less is known. A possible practical application is the removal of boiling bubbles from the neighborhood of a heated surface in the case of a downward facing surface or in the absence of gravity. For this reason, the case of a bubble near a plane rigid surface is considered in detail. It is shown that, when the acoustic wave fronts are parallel to the surface, the bubble remains trapped due to secondary Bjerknes force caused by an "image bubble." When the wave fronts are perpendicular to the surface, on the other hand, the bubble can be made to slide laterally.

Hao, Y.; Oguz, N.; Prosperetti, A.

2001-01-01

336

Vapor Pressure of Three Brominated Flame Retardants Determined via Knudsen Effusion Method  

PubMed Central

Brominated flame retardants (BFRs) have been used in a variety of consumer products in the past four decades. The vapor pressures for three widely used BFRs, that is, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and octabromodiphenyl ethers (octaBDEs) mixtures, were determined using the Knudsen effusion method and compared to those of decabromodiphenyl ether (BDE209). The values measured extrapolated to 298.15 K are 8.47 × 10?9, 7.47 × 10?10, and 2.33 × 10?9 Pa, respectively. The enthalpies of sublimation for these BFRs were estimated using the Clausius-Clapeyron equation and are 143.6 ± 0.4, 153.7 ± 3.1, and 150.8 ± 3.2 kJ/mole, respectively. In addition, the enthalpies of fusion and melting temperatures for these BFRs were also measured in the present study. PMID:22213441

Fu, Jinxia; Suuberg, Eric M.

2012-01-01

337

Manufacture Of Optical Interference Coatings By Low Pressure Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Low Pressure Chemical Vapor Deposition (LPCVD) has found wide use as a manufacturing process in semiconductor fabrication, but has not been previously used successfully for the manufacture of optical coatings. Recent work at Deposition Sciences has made it possible to manufacture on a routine basis optical interference coatings using LPCVD. LPCVD has replaced evaporation as the preferred method for deposition of the optical coating on domes for Stinger missiles; over 10,000 Stinger missile domes have been coated by Deposition Sciences using our LPCVD manufacturing process. LPCVD processes have inherent technical and cost advantages over evaporation for a wide variety of optical coating applications. LPCVD is the process of choice for optical coating of very non-planar substrates, or for optical coatings that must withstand rigorous environments. This paper describes the properties of the LPCVD process as applied to optical coatings, some performance advantages of optical films deposited by LPCVD, and the capabilities of Deposition Sciences' current LPCVD manufacturing system.

Rogers, Donald Z.

1989-12-01

338

Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor  

NASA Technical Reports Server (NTRS)

The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

Brebrick, R. F.; Su, Ching-Hua

2001-01-01

339

A search for chemical laser action in low pressure metal vapor flames. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Optical emissions were studied from low pressure (approximately 1 torr) dilute diffusion flames of Ca and Mg vapor with O2, N2O and mixtures of CCl4 and O2. The Ca flames with O2 and N2O revealed high vibrational excitation of the product CaO molecule (up to v=30). The flames with CCl4 revealed extreme nonequilibrium metal atom electronic excitation, up to the metal atom ionization limit (6.1 eV for Ca, 7.6 eV for Mg). The metal atom excited electronic state populations did not follow a Boltzmann distribution, but the excitation rates ('pumping rate') were found to obey an Arrhenius-type expression, with the electronic excitation energy playing the role of activation energy and a temperature of about 5000 K for triplet excited states and 2500 K for singlets (vs. approximately 500 K translational temperature).

Zwillenberg, M. L.

1975-01-01

340

Reid vapor-pressure regulation of gasoline, 1987-1990. Master's thesis  

SciTech Connect

Although it is generally only a summertime problem, smog, as represented by its criteria pollutant, ozone, is currently the number one air pollution problem in the United States. Major contributors to smog formation are the various Volatile Organic Compounds (VOC's) which react with other chemicals in the atmosphere to form the ozone and other harmful chemicals known as smog. Gasoline is a major source of VOC's, not only as it is burned in car engines, but as it evaporates. Gasoline evaporates in storage tanks, as it is transferred during loading and refueling operations, and in automobiles, both while they are running and while parked in the driveway. In 1987, the United States Environmental Protection Agency began an almost unprecedented effort to reduce the evaporative quality of commercial gasolines by mandating reductions in its Reid Vapor Pressure (RVP).

Butters, R.A.

1990-09-30

341

Velocities of elastic waves and v P \\/ v S ratios in dry and water-saturated rock samples at high pressure  

Microsoft Academic Search

Elastic wave velocities and the ratiovP\\/vS were studied for dry and initially saturated samples of carbonate and crystalline rocks at pressures to 2 kbar. In initially saturated samplesvP increases in crystalline rock, whereas in sedimentary rock it may either increase or decrease with increasing pressure. Under the same conditionsvS remains approximately constant in crystalline rocks and decreases in sedimentary samples.

M. P. Volarovich; V. A. Budnikov

1978-01-01

342

Oxidizer partial pressure window for YBa2Cu3O(7-x) thin film formation by metalorganic chemical vapor deposition  

Microsoft Academic Search

We conducted a systematic study of oxidizer partial pressure effects on both the superconducting transport properties and structural properties of YBa2Cu3O(7-x) (YBCO) films grown by conventional metalorganic chemical vapor deposition (MOCVD). Superconducting YBCO thin films were grown in partial N2O pressures ranging from 0.4 to 45 Torr and at substrate temperatures of 500 and 700 C. We observed a window

C. S. Chern; J. Zhao; P. E. Norris; S. M. Garrison; K. Yau; Y. Q. Li; B. M. Gallois; B. H. Kear

1992-01-01

343

Determination of octane numbers and Reid vapor pressure in commercial gasoline using dispersive fiber-optic Raman spectroscopy  

Microsoft Academic Search

Dispersive fiber-optic Raman spectroscopy utilizing CCD detection and near-IR DBR diode laser excitation is used to remotely analyze 205 petroleum fuels of varying composition for pump octane number, motor octane number (MON), research octane number (RON), and Reid vapor pressure (RVP). Partial least squares regression analysis in tandem with several preprocessing techniques was used to model pump octane, MON, RON,

Philip E. Flecher; William T. Welch; Sacharia Albin; John B. Cooper

1997-01-01

344

Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures  

NASA Technical Reports Server (NTRS)

The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

1985-01-01

345

DETERMINATION OF THE VAPOR PRESSURES OF SELECT POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS AT 75–275°C  

EPA Science Inventory

Vapor pressures were determined for several polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at 75–275°C, extending the available literature data to more relevant temperature regions and providing the first experimental data for 2,3,7...

346

An Integrated Approach to Introducing Biofuels, Flash Point, and Vapor Pressure Concepts into an Introductory College Chemistry Lab  

ERIC Educational Resources Information Center

Students explore the fundamental chemical concepts of vapor pressure and flash point in a real-world technical context, while gaining insight into the contemporary societal issue of biofuels. Lab activities were developed using a closed-cup instrument to measure the flash point of various biodiesel samples. Pre- and post-tests revealed that the…

Hoffman, Adam R.; Britton, Stephanie L.; Cadwell, Katie D.; Walz, Kenneth A.

2011-01-01

347

VAPOR PRESSURES AND EVAPORATION COEFFICIENTS OF FE, NA AND K OVER CHONDRULE COMPOSITION MELTS. A. V. Fedkin1  

E-print Network

VAPOR PRESSURES AND EVAPORATION COEFFICIENTS OF FE, NA AND K OVER CHONDRULE COMPOSITION MELTS. A. V and isotopic evidence of significant evaporative losses from chondrules is rare. The free evaporation flux and evaporation coefficient of species x, resp., R is the gas constant and T is the temperature. Thus, computation

Grossman, Lawrence

348

Growth analysis of novel ZnO nanotetrapods with tubular legs from aspect of reagent's vapor pressure and growth temperature  

NASA Astrophysics Data System (ADS)

In this article, novel ZnO nanotetrapods with tubular legs was successfully synthesized using mixed powder of Zn, ZnO, and carbon as source. The growth process was analyzed at large, and a two-step growth model, viz. initial deficient-oxidation and latter second-volatilization, was proposed to explain the formation of tubular leg of ZnO nanotetrapod. In the growth model, the high Zn vapor pressure and high growth temperature were considered as two crucial factors determining the growth behavior. Zn-rich ZnO nanotetrapod formed under high Zn vapor pressure at the initial stage. These redundant Zn clusters coexisted in ZnO lattice as interstitial Zn. The following second-volatilization of interstitial Zn under high growth temperature led to formation of tubular leg. Four other experiments were designed to analyze the growth behavior under high and low Zn vapor pressure and growth temperature, respectively, and these experimental results further confirmed the validity of our growth model. Our experiment proposed a feasible synthesis route to prepare hollow nanostructures controlled by the vapor pressure and growth temperature. Furthermore, these novel ZnO nanotetrapods might have potential application as building blocks for functional nanodevices.

Yan, Youguo; Zhou, Lixia; Zhang, Jun; Hu, Songqing; Sun, Shuangqing; Zhen, Yuhua

2012-11-01

349

CO(2) partial pressure and calcite saturation in springs - useful data for identifying infiltration areas in mountainous environments.  

PubMed

Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High PCO2 combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low PCO2 near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High PCO2 in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low PCO2 and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO2-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies. PMID:23429574

Hilberg, Sylke; Brandstätter, Jennifer; Glück, Daniel

2013-04-01

350

Atmospheric-Pressure Chemical Vapor Deposition of Iron Pyrite Thin Films  

SciTech Connect

Iron pyrite (cubic FeS{sub 2}) is a promising candidate absorber material for earth-abundant thin-film solar cells. In this report, single-phase, large-grain, and uniform polycrystalline pyrite thin films are fabricated on glass and molybdenum-coated glass substrates by atmospheric-pressure chemical vapor deposition (AP-CVD) using the reaction of iron(III) acetylacetonate and tert-butyl disulfide in argon at 300 C, followed by sulfur annealing at 500--550 C to convert marcasite impurities to pyrite. The pyrite-marcasite phase composition depends strongly on the concentration of sodium in the growth substrate and the sulfur partial pressure during annealing. Phase and elemental composition of the films are characterized by X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. The in-plane electrical properties are surprisingly insensitive to phase and elemental impurities, with all films showing p-type, thermally activated transport with a small activation energy ({approx}30 meV), a room- temperature resistivity of {approx}1 {Omega} cm, and low mobility. These ubiquitous electrical properties may result from robust surface effects. These CVD pyrite thin films are well suited to fundamental electrical studies and the fabrication of pyrite photovoltaic device stacks.

Berry, Nicholas; Cheng, Ming; Perkins, Craig L.; Limpinsel, Moritz; Hemminger, John C.; Law, Matt (NREL); (UCI)

2012-10-23

351

Highly stable silicon dioxide films deposited by means of rapid thermal -low-pressure chemical vapor deposition onto InP  

E-print Network

grown by rapid thermal, low-pressure chemical vapor deposition (RT-LPCVD), using pure oxygen (0,) and 2Highly stable silicon dioxide films deposited by means of rapid thermal - low-pressure chemical vapor deposition onto InP A. Katz, A. Feingold, U. K. Chakrabarti, and S. J. Peat-ton AT&T Bell

Florida, University of

352

The influence of substrate polarity on the structural quality of InN layers grown by high-pressure chemical vapor deposition  

E-print Network

the growth temperatures to below 650 °C for low-pressure metal organic chemical vapor depo- sition MOCVDThe influence of substrate polarity on the structural quality of InN layers grown by high-pressure chemical vapor deposition N. Dietz,1,a M. Alevli,1 R. Atalay,1 G. Durkaya,1 R. Collazo,2 J. Tweedie,2 S

Dietz, Nikolaus

353

THE EFFECT OF SODIUM VAPOR FORMATION ON THE OPERATION OF THE ENRICO FERMI REACTOR--AN ESTIMATE  

Microsoft Academic Search

The results of calculations concerning two-phase sodium flow in the ; Fermi Fast Breeder Reactor are presented. The large specific volume of sodium ; vapor coupled with the resistance of the top axial blanket section resulted in ; large pressure drops far small values of net vapor. Once the coolant reached the ; saturation temperature, the pressure drop resulting from

H. R. Kroeger; J. W. Stephenson

1957-01-01

354

Organic Dye Effects on DNAPL Entry Pressure in Water Saturated Porous Media  

SciTech Connect

One of three diazo dyes with the same fundamental structure have been used in most studies of DNAPL behavior in porous media to stain the NAPL: Sudan III, Sudan IV, or Oil-Red-O. The dyes are generally implicitly assumed to not influence DNAPL behavior. That assumption was tested using simple entry pressure experiments.

Iversen, G.M.

2001-10-02

355

Mercury vapor pressure of flue gas desulfurization scrubber suspensions: effects of pH level, gypsum, and iron.  

PubMed

Calcium-based scrubbers designed to absorb HCl and SO(2) from flue gases can also remove oxidized mercury. Dissolved mercury halides may have an appreciable partial vapor pressure. Chemical reduction of the dissolved mercury may increase the Hg emission, thereby limiting the coremoval of mercury in the wet scrubbing process. In this paper we evaluate the effects of the pH level, different gypsum qualities, and iron in flue gas desulfurization (FGD) scrubber suspensions. The impact of these parameters on mercury vapor pressure was studied under controlled laboratory conditions in model scrubber suspensions. A major influence is exerted by pH values above 7, considerably amplifying the mercury concentration in the vapor phase above the FGD scrubber suspension. Gypsum also increases the mercury re-emission. Fe(III) decreases and Fe(II) increases the vapor pressure significantly. The consequences of the findings for a reliable coremoval of mercury in FGD scrubbers are discussed. It is shown that there is an increased risk of poor mercury capture in lime-based FGD scrubbers in comparison to limestone FGD scrubbers. PMID:22324514

Schuetze, Jan; Kunth, Daniel; Weissbach, Sven; Koeser, Heinz

2012-03-01

356

Methods for calculation of engineering parameters for gas separation. [vapor pressure and solubility of gases in organic liquids  

NASA Technical Reports Server (NTRS)

A group additivity method is generated which allows estimation, from the structural formulas alone, of the energy of vaporization and the molar volume at 25 C of many nonpolar organic liquids. Using these two parameters and appropriate thermodynamic relations, the vapor pressure of the liquid phase and the solubility of various gases in nonpolar organic liquids are predicted. It is also possible to use the data to evaluate organic and some inorganic liquids for use in gas separation stages or liquids as heat exchange fluids in prospective thermochemical cycles for hydrogen production.

Lawson, D. D.

1979-01-01

357

Synthetic fluid inclusions XIX. Experimental determination of the vapor-saturated liquidus of the system H2O-NaCl-FeCl2  

NASA Astrophysics Data System (ADS)

Magmatic-hydrothermal fluids associated with felsic to intermediate composition magmas are generally dominated by (Na ± K)Cl, but often the fluids also contain significant concentrations of FeCl2. Previously, fluid inclusions containing such fluids were interpreted using the properties of H2O-NaCl because the effect of FeCl2 on the phase equilibrium and volumetric (PVTx) properties of aqueous fluids was essentially unknown. In this study, synthetic fluid inclusion experiments have been conducted to determine the vapor-saturated liquidus phase relations of the system H2O-NaCl-FeCl2. Microthermometric and microanalytical measurements on synthetic fluid inclusions have been combined with the limited existing data, as well as with predictions based on Pitzer's formalism, to determine the ternary cotectic and peritectic phase boundaries and liquidus fields. The liquidus is qualitatively similar to those of other ternary systems of H2O-NaCl plus divalent-cation chlorides (MgCl2 and CaCl2) and has been characterized through empirical equations that represent the liquid salinity on the ice- and halite-liquidus surfaces. The ice and halite liquidi intersect at a metastable cotectic curve, which can be used to determine fluid compositions in this system if metastable behavior is observed. Furthermore, based on the experimentally determined liquidus, bulk salinities of natural fluid inclusions can be determined from the last dissolution temperatures of ice and/or halite using the new empirical equations.

Lecumberri-Sanchez, Pilar; Steele-MacInnis, Matthew; Bodnar, Robert J.

2015-01-01

358

An improved method for simultaneous determination of frictional pressure drop and vapor volume fraction in vertical flow boiling  

NASA Technical Reports Server (NTRS)

The two-phase frictional pressure drop and vapor volume fraction in the vertical boiling and adiabatic flow of the refrigerant, R11, have been simultaneously measured by a liquid balancing column and differential magnetic reluctance pressure transducers. An account is given of the experimental apparatus and procedure, data acquisition and analysis, and error estimation employed. All values of two-phase multipliers evaluated on the basis of the measured frictional pressure drop data in vertical upflow fall in the range bounded by the predictions of the Chisholm correlation and the homogeneous model.

Klausner, J. F.; Chao, B. T.; Soo, S. L.

1990-01-01

359

Exchange of Na+ and K+ between water vapor and feldspar phases at high temperature and low vapor pressure  

USGS Publications Warehouse

In order to determine whether gas (steam) containing a small amount of dissolved alkali chloride is effective in promoting base exchange of Na+ and K+ among alkali feldspars and coexisting brine or brine plus solid salt, experiments were carried out at 400-700??C and steam densities ranging down to less than 0.05. For bulk compositions rich in potassium, the low pressure results are close to previous high-pressure results in composition of the fluid and coexisting solid phase. However, when the bulk composition is more sodic, alkali feldspars are relatively richer in potassium at low pressure than at high pressure. This behaviour corresponds to enrichment of potassium in the gas phase relative to coexisting brine and precipitation of solid NaCl when the brine plus gas composition becomes moderately sodic. The gas phase is very effective in promoting base exchange between coexisting alkali feldspars at high temperature and low water pressure. This suggests that those igneous rocks which contain coexisting alkali feldspars out of chemical equilibrium either remained very dry during the high-temperature part of their cooling history or that the pore fluid was a gas containing very little potassium relative to sodium. ?? 1976.

Fournier, R.O.

1976-01-01

360

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)  

NASA Technical Reports Server (NTRS)

The optical absorption spectra of the vapor phase over HgI2(s,l) were measured for wavelengths between 200 and 600 nm. The spectra show that the sample sublimed congruently into HgI2 with no Hg or I2 absorption spectrum observed. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were determined. From these constants the vapor pressure of H912, P, was established as a function of temperatures for the liquid and the solid Beta-phases. The expressions correspond to the enthalpies of vaporization and sublimation of 15.30 and 20.17 Kcal/mole, respectively, for the liquid and the Beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 Kcal/mole and the intersection of the two expressions gives a melting point of 537 K.

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

361

Long-term evaluation of the controlled pressure method for assessment of the vapor intrusion pathway.  

PubMed

Vapor intrusion (VI) investigations often require sampling of indoor air for evaluating occupant risks, but can be confounded by temporal variability and the presence of indoor sources. Controlled pressure methods (CPM) have been proposed as an alternative, but temporal variability of CPM results and whether they are indicative of impacts under natural conditions have not been rigorously investigated. This study is the first involving a long-term CPM test at a house having a multiyear high temporal resolution indoor air data set under natural conditions. Key observations include (a) CPM results exhibited low temporal variability, (b) false-negative results were not obtained, (c) the indoor air concentrations were similar to the maximum concentrations under natural conditions, and (d) results exceeded long-term average concentrations and emission rates under natural conditions by 1-2 orders of magnitude. Thus, the CPM results were a reliable indicator of VI occurrence and worst-case exposure regardless of day or time of year of the CPM test. PMID:25604884

Holton, Chase; Guo, Yuanming; Luo, Hong; Dahlen, Paul; Gorder, Kyle; Dettenmaier, Erik; Johnson, Paul C

2015-02-17

362

Effect of Chemical Composition on Enthalpy of Evaporation and Equilibrium Vapor Pressure  

E-print Network

Proceeding from the Clausius-Clapeyron equation, the relation is derived that establishes a correlation between the partial enthalpy of evaporation from binary solutions, concentrations of components, and equilibrium vapor pressures. The difference between enthalpies of evaporation of components from solutions and those from the pure liquids, D(DH), depends on the chemical nature and concentrations, X, of solutions. The effect of concentrations on D(DH) makes different appearances in ideal and non-ideal solutions, although, as a whole, D(DH) increases with the growth of concentration of the second component. A model is introduced, which considers D(DH) as the sum of energetic changes of three sequential stages: passage of molecules from the bulk liquid into the surface layer, exit of the molecules on the outer side of the interface, and the following desorption into the gas phase. In the framework of the model, the main contribution to enthalpy of evaporation comes from the processes in the surface layer. It is suggested that adsorption from solutions, which changes the chemical composition of the surface layer with respect to that of the bulk solution, determines, to great extent, the difference in the forms of the curves D(DH)=f(X) for ideal and non-ideal solutions.

Vladimir Kh. Dobruskin

2010-04-20

363

Characterization of thin silicon oxynitride films prepared by low pressure rapid thermal chemical vapor deposition  

SciTech Connect

Thin silicon oxynitride (Si-N-O) films have been deposited using low pressure rapid thermal chemical vapor deposition (RTCVD), with silane (SiH[sub 4]), nitrous oxide (N[sub 2]O), and ammonia (NH[sub 3]) as the reactive gases. Structural and kinetic studies indicate that an increase in the NH[sub 3]/N[sub 2]O flow rate ratio leads to an increase N/O atomic ratio and a decreased Si-N-O deposition rate for constant SiH[sub 4] and N[sub 2]O flow rates. Experimental results show that RTCVD Si-N-O films with high throughput at low thermal budget, uniform composition, and atomically flat interface can be achieved using a SiH[sub 4]/NH[sub 3]/N[sub 2]O gas mixture. Electrical characterization of poly Si/Si-N-O/Si capacitors demonstrates that for NH[sub 3]/N[sub 2]O flow rate ratios ranging from 20 to 100%, the mid-gap interface trap densities of the deposited Si-N-O films are [<=]2 [times] 10[sup 10] eV[sup [minus]1] cm[sup [minus]2] and Fowler-Nordheim electron-tunneling rather than Frenkel-Poole thermal-emission is the dominant conduction mechanism in the thin RTCVD Si-N-O films.

Xu, X.L.; McLarty, P.K.; Brush, H.; Misra, V.; Wortman, J.J. (North Carolina State Univ., Raleigh, NC (United States). Dept. of Electrical and Computer Engineering); Harris, G.S. (North Carolina State Univ., Raleigh, NC (United States). Dept. of Material Science and Engineering)

1993-10-01

364

Threefold atmospheric-pressure annealing for suppressing graphene nucleation on copper in chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) is a promising method of producing a large single-crystal graphene on a catalyst, especially on copper (Cu), and a further increase in domain size is desirable for electro/optic applications. Here, we report on threefold atmospheric-pressure (ATM) annealing for suppressing graphene nucleation in atmospheric CVD. Threefold ATM annealing formed a step and terrace surface of the underlying Cu, in contrast to ATM annealing. Atomic force microscopy and Auger electron mapping revealed that Si-containing particles existed on threefold-ATM- and ATM-annealed surfaces; particles on Cu had a lower density after threefold ATM annealing than after ATM annealing. The formation of a step and terrace surface and the lower density of particles following the threefold ATM annealing would play a role in reducing graphene nucleation. By combining threefold ATM annealing and electropolishing of Cu, the nucleation of graphene was effectively suppressed, and a submillimeter-sized hexagonal single-crystal graphene was successfully obtained.

Suzuki, Seiya; Nagamori, Takashi; Matsuoka, Yuki; Yoshimura, Masamichi

2014-09-01

365

Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure  

NASA Astrophysics Data System (ADS)

We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis due to its high heat and mass transfer efficiency and well-controlled flow parameters. Experimental studies of CVD microreactor technology are slow and expensive. Analytical solution of the governing equations is impossible due to the complexity of intertwined non-linear physical and chemical processes. Computer simulation is the most effective tool for design and optimization of microreactors. Our computational fluid dynamics model employs mass, momentum and energy balance equations for a laminar transient flow of a chemically reacting gas mixture at low Reynolds number. Simulation results show the influence of microreactor configuration and process parameters on SiO2 deposition rate and uniformity. We simulated three microreactors with the central channel diameter of 5, 10, 20 micrometers, varying gas flow rate in the range of 5-100 microliters per hour and temperature in the range of 300-800 °C. For each microchannel diameter we found an optimal set of process parameters providing the best quality of deposited material. The model will be used for optimization of the microreactor configuration and technological parameters to facilitate the experimental stage of this research.

Konakov, S. A.; Krzhizhanovskaya, V. V.

2015-01-01

366

Organic component vapor pressures and hygroscopicities of aqueous aerosol measured by optical tweezers.  

PubMed

Measurements of the hygroscopic response of aerosol and the particle-to-gas partitioning of semivolatile organic compounds are crucial for providing more accurate descriptions of the compositional and size distributions of atmospheric aerosol. Concurrent measurements of particle size and composition (inferred from refractive index) are reported here using optical tweezers to isolate and probe individual aerosol droplets over extended timeframes. The measurements are shown to allow accurate retrievals of component vapor pressures and hygroscopic response through examining correlated variations in size and composition for binary droplets containing water and a single organic component. Measurements are reported for a homologous series of dicarboxylic acids, maleic acid, citric acid, glycerol, or 1,2,6-hexanetriol. An assessment of the inherent uncertainties in such measurements when measuring only particle size is provided to confirm the value of such a correlational approach. We also show that the method of molar refraction provides an accurate characterization of the compositional dependence of the refractive index of the solutions. In this method, the density of the pure liquid solute is the largest uncertainty and must be either known or inferred from subsaturated measurements with an error of <±2.5% to discriminate between different thermodynamic treatments. PMID:25522920

Cai, Chen; Stewart, David J; Reid, Jonathan P; Zhang, Yun-Hong; Ohm, Peter; Dutcher, Cari S; Clegg, Simon L

2015-01-29

367

Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications  

NASA Technical Reports Server (NTRS)

Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

2002-01-01

368

Avoiding compositional segregation in fluid-saturated high-pressure experiments: a rocking multi-anvil  

NASA Astrophysics Data System (ADS)

High pressure equilibria involving hydrous phases and fluid suffer from intrinsically high solubilities of solid components which, in conjunction with gravitationally driven fluid migration, cause chemical segregation within experimental systems. Additional complications arise as fluid migration and dissolution are time- and fluid/rock ratio dependent. Consequently, strong zoning in solid phase assemblages is frequently observed (e.g. Stalder+Ulmer 2001, CMP) which render interpretations of phase relations and equilibrium difficult. In fact, experimental determinations of high-pressure dehydration reactions from different groups are often inconsistent (at least in MSH and in K-rich systems), a major part of these inconsistencies might be attributed to time dependent chemical segregation. In order to overcome these problems a rocking multi-anvil was developed. A 600 tons press has been mounted such that it can be turned by 180^o while pressure and temperature are applied. The fully automated system needs 30 sec for a 180^o turn, the interval between two turns is programmable. The rocking press accommodates a piston cylinder or multi-anvil system and allows to invert the gravitational field acting on the sample at pressures from 1-25 GPa. Experiments of several days at 1 turn/15 min or for 4 h with continuous turning have been successfully completed. A turning frequency series (at 4 h run time) and a static time series have been conducted on serpentine composition at 13 GPa, 950 ^oC. Without rocking, 4 horizontal zones (fluid-quench, enstatite, phase E+en, E+phase A) are observed. Rocking with 1 turn/15 min decreases the zoning but phase A is still present. Only continuous turning leads to an (almost) perfectly homogeneous capsule of E+en with equilibrium texture. A short static experiment of 15 min results into axis-symmetrical zones that follow hour-glass shaped isotherms. With increasing run time zones become horizontal and asymmetric (top-bottom). The observed textures are consistent with an initially temperature dependent crystallization where zoning is caused by Soret-diffusion. With time, a stable Soret-gradient in the fluid together with fluid segregation causes development of a horizontal zonation through a dissolution-reprecipitation process that auto-amplifies the Soret-gradient. Continuous turning prevents the establishment of a chemical gradient in the fluid stable in space and time. Through turning-induced "stirring" of the system we obtain an almost homogeneous fluid and thus an almost homogeneous solid phase distribution. Finally, our experiments are in equilibrium over the entire capsule, the number of phases does not exceed those permitted by the phase rule (which is typically the case in static experiments), and we can reliably determine phase relations of hydrous phases at high pressure without depending on interpretations of strongly zoned capsules.

Schmidt, M. W.; Ulmer, P.

2003-04-01

369

Control of Photosynthesis and Stomatal Conductance in Ricinus communis L. (Castor Bean) by Leaf to Air Vapor Pressure Deficit.  

PubMed

Castor bean (Ricinus communis L.) has a high photosynthetic capacity under high humidity and a pronounced sensitivity of photosynthesis to high water vapor pressure deficit (VPD). The sensitivity of photosynthesis to varying VPD was analyzed by measuring CO(2) assimilation, stomatal conductance (g(s)), quantum yield of photosystem II (phi(II)), and nonphotochemical quenching of chlorophyll fluorescence (q(N)) under different VPD. Under both medium (1000) and high (1800 micromoles quanta per square meter per second) light intensities, CO(2) assimilation decreased as the VPD between the leaf and the air around the leaf increased. The g(s) initially dropped rapidly with increasing VPD and then showed a slower decrease above a VPD of 10 to 20 millibars. Over a temperature range from 20 to 40 degrees C, CO(2) assimilation and g(s) were inhibited by high VPD (20 millibars). However, the rate of transpiration increased with increasing temperature at either low or high VPD due to an increase in g(s). The relative inhibition of photosynthesis under photorespiring (atmospheric levels of CO(2) and O(2)) versus nonphotorespiring (700 microbars CO(2) and 2% O(2)) conditions was greater under high VPD (30 millibars) than under low VPD (3 millibars). Also, with increasing light intensity the relative inhibition of photosynthesis by O(2) increased under high VPD, but decreased under low VPD. The effect of high VPD on photosynthesis under various conditions could not be totally accounted for by the decrease in the intercellular CO(2) in the leaf (C(i)) where C(i) was estimated from gas exchange measurements. However, estimates of C(i) from measurements of phi(II) and q(N) suggest that the decrease in photosynthesis and increase in photorespiration under high VPD can be totally accounted for by stomatal closure and a decrease in C(i). The results also suggest that nonuniform closure of stomata may occur in well-watered plants under high VPD, causing overestimates in the calculation of C(i) from gas exchange measurements. Under low VPD, 30 degrees C, high light, and saturating CO(2), castor bean (C(3) tropical shrub) has a rate of photosynthesis (61 micromoles CO(2) per square meter per second) that is about 50% higher than that of tobacco (C(3)) or maize (C(4)) under the same conditions. The chlorophyll content, total soluble protein, and ribulose-1,5-bisphosphate carboxylase/oxygenase level on a leaf area basis were much higher in castor bean than in maize or tobacco, which accounts for its high rates of photosynthesis under low VPD. PMID:16669054

Dai, Z; Edwards, G E; Ku, M S

1992-08-01

370

Control of Photosynthesis and Stomatal Conductance in Ricinus communis L. (Castor Bean) by Leaf to Air Vapor Pressure Deficit 1  

PubMed Central

Castor bean (Ricinus communis L.) has a high photosynthetic capacity under high humidity and a pronounced sensitivity of photosynthesis to high water vapor pressure deficit (VPD). The sensitivity of photosynthesis to varying VPD was analyzed by measuring CO2 assimilation, stomatal conductance (gs), quantum yield of photosystem II (?II), and nonphotochemical quenching of chlorophyll fluorescence (qN) under different VPD. Under both medium (1000) and high (1800 micromoles quanta per square meter per second) light intensities, CO2 assimilation decreased as the VPD between the leaf and the air around the leaf increased. The gs initially dropped rapidly with increasing VPD and then showed a slower decrease above a VPD of 10 to 20 millibars. Over a temperature range from 20 to 40°C, CO2 assimilation and gs were inhibited by high VPD (20 millibars). However, the rate of transpiration increased with increasing temperature at either low or high VPD due to an increase in gs. The relative inhibition of photosynthesis under photorespiring (atmospheric levels of CO2 and O2) versus nonphotorespiring (700 microbars CO2 and 2% O2) conditions was greater under high VPD (30 millibars) than under low VPD (3 millibars). Also, with increasing light intensity the relative inhibition of photosynthesis by O2 increased under high VPD, but decreased under low VPD. The effect of high VPD on photosynthesis under various conditions could not be totally accounted for by the decrease in the intercellular CO2 in the leaf (Ci) where Ci was estimated from gas exchange measurements. However, estimates of Ci from measurements of ?II and qN suggest that the decrease in photosynthesis and increase in photorespiration under high VPD can be totally accounted for by stomatal closure and a decrease in Ci. The results also suggest that nonuniform closure of stomata may occur in well-watered plants under high VPD, causing overestimates in the calculation of Ci from gas exchange measurements. Under low VPD, 30°C, high light, and saturating CO2, castor bean (C3 tropical shrub) has a rate of photosynthesis (61 micromoles CO2 per square meter per second) that is about 50% higher than that of tobacco (C3) or maize (C4) under the same conditions. The chlorophyll content, total soluble protein, and ribulose-1,5-bisphosphate carboxylase/oxygenase level on a leaf area basis were much higher in castor bean than in maize or tobacco, which accounts for its high rates of photosynthesis under low VPD. PMID:16669054

Dai, Ziyu; Edwards, Gerald E.; Ku, Maurice S. B.

1992-01-01

371

Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium  

USGS Publications Warehouse

Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

Iverson, R.M.

1993-01-01

372

Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes  

USGS Publications Warehouse

Measurements and estimates of aqueous solubilities, 1-octanol-water partition coefficients (Kow), and vapor pressures were made for 29 linear alkylbenzenes having alkyl chain lengths of 9-14 carbons. The ranges of values observed were vapor pressures from 0.002 to 0.418 Pa, log Kow, from 6.83 to 9.95, and aqueous solubilities from 4 to 38 nmol??L-1. Measured values exhibited a relationship to both the alkyl chain length and the position of phenyl substitution on the alkyl chain. Measurement of the aqueous concentrations resulting from equilibration of a mixture of alkylbenzenes yielded higher than expected values, indicating cosolute or other interactive effects caused enhanced aqueous concentrations of these compounds. ?? 1992 American Chemical Society.

Sherblom, P.M.; Gschwend, P.M.; Eganhouse, R.P.

1992-01-01

373

Simultaneous Treatment of Vapor Pressures and Related Thermal Data Between the Triple and Normal Boiling Temperatures for n-Alkanes C5-C20  

NASA Astrophysics Data System (ADS)

Experimental vapor pressures, calorimetric enthalpies of vaporization and differences between the heat capacities of the ideal gas and the liquid for n-alkanes C5 to C20 between the triple and normal boiling temperatures have been treated simultaneously. Attention was focused particularly on the region of low pressures where vapor pressure data are scarce and subject to important systematic errors. The reliability and consistency of data fro different sources was evaluated and the three parameter Cox equation was used to correlate simultaneously as a function of temperature the selected values of different properties. The recommended vapor pressures and thermal data resulting from this procedure are mutually consistent over the homologous series and present a considerable refinement particularly at lower pressures.

Růži?ka, Kv?toslav; Majer, Vladimír

1994-01-01

374

Epitaxial growth of ZnO thin films exhibiting room-temperature ultraviolet emission by atmospheric pressure chemical vapor deposition  

Microsoft Academic Search

ZnO films have been grown on sapphire(0001) substrates by means of the atmospheric pressure halide vapor phase epitaxy technique using ZnI2 and O2 as starting materials. The ZnO films showed a full width at half maximum of the (0002) X-ray peak of 20.2 min and a reflection high-energy electron diffraction pattern similar to that of a single crystal. A band-edge

Kazuhiko Kaiya; Kouji Omichi; Naoyuki Takahashi; Takato Nakamura; Shinji Okamoto; Hajime Yamamoto

2002-01-01

375

Estimation of vapor pressures, solubilities and Henry's law constants of selected persistent organic pollutants as functions of temperature  

Microsoft Academic Search

An internally consistent set of temperature dependent physical-chemical property data was derived for 73 persistent organic pollutants, including polychlorinated biphenyls, diphenylethers, dibenzo-p-dioxins, and dibenzofurans, organochlorinated pesticides and polycyclic aromatic hydrocarbons. Measured data reported in the literature were expanded by different estimation and regression methods. Temperature dependent vapor pressures were estimated from relative gas chromatographic retention times and by a modified

Jaakko Paasivirta; Seija Sinkkonen; Pirjo Mikkelson; Tiina Rantio; Frank Wania

1999-01-01

376

Estimating the vapor pressures of multi-functional oxygen-containing organic compounds using group contribution methods  

Microsoft Academic Search

A UNIFAC-based method for estimating the vapor pressure (pLo) values of oxygen-containing compounds of intermediate-to-low volatility has been developed as an aid in modeling the formation and behavior of organic aerosols. This UNIFAC-pLo method was constructed using a set of 76 compounds with experimentally determined pLo values. The compounds chosen are of intermediate-to-low volatility and contain multiple oxygen-containing functionalities. For

William E Asher; James F Pankow; Garnet B Erdakos; John H Seinfeld

2002-01-01

377

Integrated vapor pressure, hygroswelling, and thermo-mechanical stress modeling of QFN package during reflow with interfacial fracture mechanics analysis  

Microsoft Academic Search

In this paper, a comprehensive and integrated package stress model is established for quad flat non-lead package with detailed considerations of effects of moisture diffusion, heat transfer, thermo-mechanical stress, hygro-mechanical stress and vapor pressure induced during reflow. The critical plastic materials, i.e., moldcompound and die attach are characterized for hygroswelling and moisture properties, which are not easily available from material

Tong Yan Tee; Zhaowei Zhong

2004-01-01

378

Measurement and modeling of osmotic coefficients of aqueous solution of ionic liquids using vapor pressure osmometry method  

Microsoft Academic Search

Osmotic coefficients of binary mixtures containing an ionic liquid, (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIm]BF4, 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIm]ES, and 1-butyl-3-methylimidazolium methyl sulfate, [BMIm]MS) with water were measured until about 3 molal concentrations using vapor pressure osmometry method (VPO) at temperature ranges 298.15–328.15K and modeled using different electrolyte excess Gibbs free energy models including electrolyte non-random two liquids (NRTL), modified NRTL (MNRTL), mean

Hemayat Shekaari; Sedighehnaz S. Mousavi

2009-01-01

379

Generation of Charged Nanoparticles during the Synthesis of GaN Nanostructures by Atmospheric-Pressure Chemical Vapor Deposition  

Microsoft Academic Search

The possibility that GaN charged nanoparticles might be generated during the synthesis of GaN nanostructures was examined in an atmospheric-pressure chemical vapor deposition (CVD) process using a differential mobility analyzer combined with a Faraday cup electrometer. Both positively and negatively charged nanoparticles in the size range of 10–100 nm were generated in the reactor of the CVD process using Ga2O3 precursor

Sung-Soo Lee; Chan-Soo Kim; Nong-Moon Hwang

2012-01-01

380

Atmospheric pressure chemical vapor deposition of transparent conducting films of fluorine doped zinc oxide and their application to amorphous silicon solar cells  

Microsoft Academic Search

Transparent conducting ZnO:F was deposited as thin films on soda lime glass substrates by atmospheric pressure chemical vapor\\u000a deposition (CVD) deposition at substrate temperatures of 480–500 °C. The precursors diethylzinc, tetramethylethylenediamine\\u000a and benzoyl fluoride were dissolved in xylene. The solution was nebulized ultrasonically and then flash vaporized by a carrier\\u000a gas of nitrogen preheated to 150 °C. Ethanol was vaporized separately, and

Haifan Liang; Roy G. Gordon

2007-01-01

381

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

SciTech Connect

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

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

1995-12-31

382

Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments  

NASA Astrophysics Data System (ADS)

We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors.

Dugrain, Vincent; Rosenbusch, Peter; Reichel, Jakob

2014-08-01

383

Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments.  

PubMed

We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors. PMID:25173251

Dugrain, Vincent; Rosenbusch, Peter; Reichel, Jakob

2014-08-01

384

Vapor pressure deficit controls on fire ignition and fire spread in boreal forest ecosystems  

NASA Astrophysics Data System (ADS)

Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different fire processes, including ignition, daily fire spread rates, and cumulative annual burned area. Here we combined MODIS active fires (MCD14ML), MODIS imagery (MOD13A1) and ancillary historic fire perimeter information to produce a dataset of daily fire spread maps of Alaska for the period 2002-2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed together with daily vapor pressure deficit (VPD) observations from the North American Regional Reanalysis (NARR) and lightning strikes from the Alaska Lightning Detection Network (ALDN). We found a significant relationship between daily VPD and probability that a lightning strike would develop into a fire ignition. In the first 5 days after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread rates, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979-2011; R2 = 0.45). Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our spatiotemporal analysis provide new information about temporal and spatial dynamics of wildfires and have implications for modeling the terrestrial carbon cycle.

Sedano, F.; Randerson, J. T.

2014-01-01

385

Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films  

SciTech Connect

Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

Hoffman, D.M. [Houston Univ., TX (United States); Atagi, L.M. [Houston Univ., TX (United States)]|[Los Alamos National Lab., NM (United States); Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang [Houston Univ., TX (United States); Rubiano, R.R. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Springer, R.W.; Smith, D.C. [Los Alamos National Lab., NM (United States)

1994-06-01

386

On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.  

SciTech Connect

Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are reached concerning the factors affecting the growth rate in on-line APCVD reactors. In addition, a substantial body of data was generated that can be used to model many different industrial tin oxide coating processes. These data include the most extensive compilation of thermochemistry for gas-phase tin-containing species as well as kinetic expressions describing tin oxide growth rates over a wide range of temperatures, pressures, and reactant concentrations.

Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

2006-11-01

387

Fabrication of Ferrite Thin Film using Low Pressure Metalorganic Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

This thesis is based on the research work on the multiferroic material fabrications using low pressure metalorganic chemical vapor deposition (MOCVD). Multiferroic material refers to the ones who have two or more ferroic properties, like ferroelectricity, ferromagnetism, ferroelasticity and ferrotoroidicity. Extensive research findings focused on pure nano scale thin films and composites those were related to presenting both ferroelectricity and ferromagnetism coupling within the material. BiFeO3 (BFO) was known to be the only single phase multiferroic material which exhibited magnetoelectric (ME) coupling effect at room temperature. This coupling effect provided an extra degree of freedom for designs of whole new devices and applications never thought to be possible before. Recently, large ME effect was found in its thin epitaxial-strained films. However, very few papers reported the CVD techniques for depositing BFO thin films so far. Most of these reports used direct liquid injection method to deliver the organometallic reactants during the CVD process (ie. DLICVD). Here, we introduced a novel liquid iron precursor, n-butylferrocene, delivered into the reactor by heating the precursor canisters at certain temperatures for growing BFO thin films. Other crucial MOCVD conditions (reactor's pressure, reactor's temperature, substrates...) were also discussed and optimized. Characterizations for the film composition, crystallinity, ferroelectricity, ferromagnetism and the magneto-dielectric coupling effect were analyzed in detail. The results confirmed that BFO film had multiferroic properties and could be potentially used in future tunable high-frequency devices. Although single-phase BFO exhibited ME effect, this suffered from problems such as current leakages, weak ME coupling and low ordering temperatures. Doping or ion substitution was a limited way to enhance the ME property since the compounds had definite compositions. Therefore, heterostructures such as bilayered/multilayered thin films, nanoparticles/nanopillars embedded in different materials and nanowires became more promising for the future on-chip integration applications because the coupling in such structures was many orders of magnitude stronger. Another research scientists interested in was the heterostructural magnetostrictive NiFe2O4 (NFO) with piezoelectric materials. NFO was a promising magnetic phase for ME heterostructures due to its low anisotropy, high permeability with high resistivity, low eddy current losses and smaller coercive field. In this study, the nickel ferrite thin films had been deposited using computer controlled MOCVD setup in both co-deposition mode and cyclic-deposition mode. Conditions for CVD process were discussed and optimized for growing NFO thin film. The thin films showed NFO composition, uniformity in chemical states and thickness, trevorite crystalline form, free from carbon contamination and similar magnetic property as other literature reported.

Yang, Yi

388

The Gaseous Enthalpy of Formation of the Ionic Liquid 1Butyl3-methylimidazolium Dicyanamide from Combustion Calorimetry, Vapor Pressure Measurements, and Ab Initio Calculations  

Microsoft Academic Search

Ionic liquids are attracting growing interest as alternatives to conventional molecular solvents. Experimental values of vapor pressure, enthalpy of vaporization, and enthalpy of formation of ionic liquids are the key thermodynamic quantities, which are required for the validation and development of the molecular modeling and ab initio methods toward this new class of solvents. In this work, the molar enthalpy

Vladimir N. Emel'yanenko; Sergey P. Verevkin; Andreas Heintz

2007-01-01

389

Ex 8.1(a) At 90C, the vapor pressure of methylbenzene is 400 Torr and that of 1,2-dimethylbenzene is 150 Torr. What is the composition of a liquid mixture that boils at 90C  

E-print Network

Ex 8.1(a) At 90°C, the vapor pressure of methylbenzene is 400 Torr and that of 1,2- dimethylbenzene? What is the composition of the vapor produced? Ex 8.2(a) The vapor pressure of pure liquid A at 300 K is 0.350. Calculate the total pressure of the vapor and the composition of the liquid mixture. Prob 8

Findley, Gary L.

390

Pressure and power generation during explosive vaporization on a thin-film microheater  

Microsoft Academic Search

When a liquid is superheated above its boiling point to temperatures near or at the homogeneous nucleation limit, the energy released could create a so-called explosive vaporization, if a significant fraction of this energy is manifested in the form of vapor expansion. In this study, a thin-film microheater (100 ?m×110 ?m) was placed on the underside of a water layer. The surface

Z. Zhao; S. Glod; D. Poulikakos

2000-01-01

391

Modeling Relations Among Relative Permeabilities, Fluid Saturations, and Capillary Pressures in Mixed-Wet Porous Media: Model Testing and Application to Oil-Water Systems  

SciTech Connect

A critical component of all multiphase flow codes is how relationships among relative permeabilities, fluid saturations, and capillary pressures (i.e., k-S-P relations) are described. Models that are able to mimic fundamental fluid-flow processes to predict k S-P relations are preferable than extrapolating measured data points to estimate k-S-P relations because they may have greater utility and may be more consistent. Furthermore, different saturation-path histories may be simulated with a computer code than those measured in the k-S-P experiments. Because the geometry of the pore spaces in natural porous media is very complex and will likely never be precisely known to predict k-S-P behavior from fundamental relationships, k-S-P models are largely empirical. In this paper, an empirical model based on theoretical considerations is developed to predict hysteretic k-S-P relations in porous media in which the smaller pores are water-wet and the larger pores are oil-wet, i.e., mixed-w et. At high oil-water capillary pressures, the water saturation is modeled to approach the residual water saturation. At low oil-water capillary pressures (i.e., negative), the oil saturation is modeled to approach the residual oil saturation. Relative permeabilities are predicted using parameters that describe main-drainage S-P relations and accounting for the distribution of water and oil in the pore spaces of mixed-wet porous media. The proposed algebraic expressions are easy to implement in multiphase flow codes and can be used to predict k-S-P relations for any saturation-path history. In addition, the model is relatively easy to calibrate to porous media.

Oostrom, Mart (BATTELLE (PACIFIC NW LAB)); Lenhard, Robert J. (INEEL); Delshad, M; Robertson, S D. (Spirit 76, Midland, TX); M.Th. van Genuchten, F.J. Leij and L. Wu

1998-01-01

392

Effect of pressure, temperature, and oil-saturation on the thermal conductivity of sandstone up to 250 MPa and 520 K  

Microsoft Academic Search

Effective thermal conductivity (ETC) of oil-saturated sandstone (porosity 13%) have been measured over a temperature range from (288 to 520)K and at pressures up to 250MPa with a steady-state parallel-plate apparatus. The expanded uncertainty of thermal conductivity, pressure, and temperature measurements at the 95% confidence level with a coverage factor of k=2 were estimated to be 2%, 0.05%, and 30mK,

Zumrud Z. Abdulagatova; Ilmutdin M. Abdulagatov; Subkhanverdi N. Emirov

2010-01-01

393

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces  

SciTech Connect

We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.

Starr, David E.; Wong, Ed K.; Worsnop, Douglas R.; Wilson, Kevin R.; Bluhm, Hendrik

2008-05-01

394

Capillary pressure and saturation relations for supercritical CO2 and brine in sand: High-pressure Pc(Sw) controller/meter measurements and capillary scaling predictions  

NASA Astrophysics Data System (ADS)

In geologic carbon sequestration, reliable predictions of CO2 storage require understanding the capillary behavior of supercritical (sc) CO2. Given the limited availability of measurements of the capillary pressure (Pc) dependence on water saturation (Sw) with scCO2 as the displacing fluid, simulations of CO2 sequestration commonly rely on modifying more familiar air/H2O and oil/H2O Pc(Sw) relations, adjusted to account for differences in interfacial tensions. In order to test such capillary scaling-based predictions, we developed a high-pressure Pc(Sw) controller/meter, allowing accurate Pc and Sw measurements. Drainage and imbibition processes were measured on quartz sand with scCO2-brine at pressures of 8.5 and 12.0 MPa (45°C), and air-brine at 21°C and 0.1 MPa. Drainage and rewetting at intermediate Sw levels shifted to Pc values that were from 30% to 90% lower than predicted based on interfacial tension changes. Augmenting interfacial tension-based predictions with differences in independently measured contact angles from different sources led to more similar scaled Pc(Sw) relations but still did not converge onto universal drainage and imbibition curves. Equilibrium capillary trapping of the nonwetting phases was determined for Pc = 0 during rewetting. The capillary-trapped volumes for scCO2 were significantly greater than for air. Given that the experiments were all conducted on a system with well-defined pore geometry (homogeneous sand), and that scCO2-brine interfacial tensions are fairly well constrained, we conclude that the observed deviations from scaling predictions resulted from scCO2-induced decreased wettability. Wettability alteration by scCO2 makes predicting hydraulic behavior more challenging than for less reactive fluids.

Tokunaga, Tetsu K.; Wan, Jiamin; Jung, Jong-Won; Kim, Tae Wook; Kim, Yongman; Dong, Wenming

2013-08-01

395

Response of effluent-irrigated Eucalyptus grandis and Pinus radiata to salinity and vapor pressure deficits.  

PubMed

Effects of high vapor pressure deficit (VPD) and soil salinity on growth and physiology of Pinus radiata D. Don and Eucalyptus grandis Hill ex Maiden were studied in a five-year-old plantation irrigated with salt-enhanced effluent (2.2 dS m(-1)) or freshwater (0.2 dS m(-1)) for 14 weeks during spring and summer. Salt was then rapidly leached by over-irrigation with low-salinity effluent. Soil water and salinity, tree water stress, sap flux, substrate carbon conversion efficiency, foliage and stem growth, and foliar cations and chloride were monitored throughout the study. An average of 9 and 1 Mg ha(-1) of salt with an average hydraulic load of 660 and 780 mm was applied to the salt and control plots, respectively. Maximum soil salinity in the root zone was 5.8 and 6.8 dS m(-1) in the eucalypt and pine plots, respectively. Predawn water potential was more than twice as sensitive to increasing salinity in E. grandis as in P. radiata. The salt treatment reduced rates of leaf and stem growth of the eucalypts by 60 to 70% but had no effect on leaf and stem growth of the pines. In the eucalypts, salinity decreased mean leaf area by 26% and increased specific leaf area by 12% compared with control values, indicating less biomass per unit leaf area in the salt treatment. Salinity had no effects on these two parameters in pine. The salt treatment significantly increased mean foliar concentrations of Na and Cl in both species, and of K in the pines. Foliar Na concentration was 6-10 times higher in the eucalypts than in the pines. Lowered water potential and increased Na concentration in the eucalypts in response to salinity resulted in about a 50% reduction in the efficiency of conversion of carbon into biomass; however, three weeks after leaching the salt, there was no significant difference in efficiency of conversion of carbon into biomass between the treatments. Salinity had no effect on water use by eucalypts, but caused a nonsignificant decrease (7%) in water use by pines. As evaporative demand increased, crop factor (transpiration divided by pan evaporation) declined by up to 50 and 60% in the pines and eucalypts, respectively. We conclude that stomatal response to high VPD, not soil salinity, accounts for most of the reduction in summertime water use. PMID:12651343

Myers, B. J.; Benyon, R. G.; Theiveyanathan, S.; Criddle, R. S.; Smith, C. J.; Falkiner, R. A.

1998-01-01

396

Does Spatial Variation in Soil Characteristics Affect Tree Transpiration Responses to Vapor Pressure Deficit?  

NASA Astrophysics Data System (ADS)

Forest canopy transpiration (Ec) both depends on and influences the local and regional atmospheric conditions. Because soil is the source of water for Ec, the soil's chemical and physical properties are also likely to be drivers of transpiration. The objective of this study is to spatially quantify the relationship between the soil's chemical and physical characteristics and Ec across environmental gradients. The two study sites are in northern Wisconsin, in mixed hardwood forest. In one site, the environmental gradient runs from a dry upland dominated by aspen (Populus tremuloides) to a wetland dominated by alders (Alnus rugosa). The second site has little elevational variation, is well-drained, and is dominated by sugar maple (Acer saccharum) bisected by a swath of red pine (Pinus resinosa). Ec data have been collected over three summers on the same set of trees using Granier sensors, while the soil samples were collected in 2006 from the same plots as the measured trees. Both of the approximately 120 m x 120 m plots have been sampled in 10 m x 10 m subplots based on a 3/7 cyclic sampling scheme to maximize spatially explicit information with a minimum number of sampled points. Roughly 150 trees were measured in each plot. We have previously shown an inverse relationship between the spatial autocorrelation of Ec and vapor pressure deficit (D). We thus hypothesize that a significant amount of this relationship can be explained by soil properties. Preliminary analysis of soil data from a representative transect in the aspen site show that soil texture, carbon (C) content, and nitrogen (N) content change along the gradient. From the upland through the wetland, Ec declined significantly, and, while all the soils were a sandy loam, the sand content showed a decreasing trend, while the silt content increased nearly two-fold. Across the same (upland to wetland) gradient, the C:N ratio showed a slightly increasing trend, but the total percentage values of the two elements increased nearly 25 fold: from C of 0.884 and N of 0.060 to C of 22.34 and N of 1.283. We hypothesize that the maple site will show less variability in Ec because of its more uniform soil characteristics. Ongoing work of soil moisture release curves, bulk density, and root biomass will provide additional explanations of the spatial relationships between Ec and D. Our analytical approach, then, provides a first step in explaining the processes behind spatial patterns in transpiration.

Traver, E.; Ewers, B. E.; Loranty, M.; Mackay, D. S.

2006-12-01

397

The dissolution of calcite in CO2-saturated solutions at 25??C and 1 atmosphere total pressure  

USGS Publications Warehouse

The dissolution of Iceland spar in CO2-saturated solutions at 25??C and 1 atm total pressure has been followed by measurement of pH as a function of time. Surface concentrations of reactant and product species have been calculated from bulk fluid data using mass transport theory and a model that accounts for homogeneous reactions in the bulk fluid. The surface concentrations are found to be close to bulk solution values. This indicates that calcite dissolution under the experimental conditions is controlled by the kinetics of surface reaction. The rate of calcite dissolution follows an empirical second order relation with respect to calcium and hydrogen ion from near the initial condition (pH 3.91) to approximately pH 5.9. Beyond pH 5.9 the rate of surface reaction is greatly reduced and higher reaction orders are observed. Calculations show that the rate of calcite dissolution in natural environments may be influenced by both transport and surface-reaction processes. In the absence of inhibition, relatively short times should be sufficient to establish equilibrium. ?? 1976.

Plummer, L.N.; Wigley, T.M.L.

1976-01-01

398

Are fern stomatal responses to different stimuli coordinated? Testing responses to light, vapor pressure deficit, and CO2 for diverse species grown under contrasting irradiances.  

PubMed

The stomatal behavior of ferns provides an excellent system for disentangling responses to different environmental signals, which balance carbon gain against water loss. Here, we measured responses of stomatal conductance (gs ) to irradiance, CO2 , and vapor pressure deficit (VPD) for 13 phylogenetically diverse species native to open and shaded habitats, grown under high- and low-irradiance treatments. We tested two main hypotheses: that plants adapted and grown in high-irradiance environments would have greater responsiveness to all stimuli given higher flux rates; and that species' responsiveness to different factors would be correlated because of the relative simplicity of fern stomatal control. We found that species with higher light-saturated gs had larger responses, and that plants grown under high irradiance were more responsive to all stimuli. Open habitat species showed greater responsiveness to irradiance and CO2 , but lower responsiveness to VPD; a case of plasticity and adaptation tending in different directions. Responses of gs to irradiance and VPD were positively correlated across species, but CO2 responses were independent and highly variable. The novel finding of correlations among stomatal responses to different stimuli suggests coordination of hydraulic and photosynthetic signaling networks modulating fern stomatal responses, which show distinct optimization at growth and evolutionary time-scales. PMID:25077933

Creese, Chris; Oberbauer, Steve; Rundel, Phil; Sack, Lawren

2014-10-01

399

Arsenic incorporation into InGaAsP grown by low-pressure metalorganic vapor phase epitaxy using tertiarybutylarsine and tertiarybutylphosphine in N2 ambient  

NASA Astrophysics Data System (ADS)

InxGa1-xAsyP1-y epilayers have been grown by low-pressure metalorganic vapor phase epitaxy (LPMOVPE) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) as group V precursors and nitrogen as the carrier gas. Arsenic incorporation into InxGa1-xAsyP1-y films grown by LPMOVPE as a function of the gas phase composition ratio and V/III ratio has been systematically studied. With optimized growth conditions, the arsenic composition of the epilayers does not change linearly with the TBA source flow. It is observed that the arsenic incorporation becomes saturated when the gas phase composition TBA/(TBA+TBP) increases to 0.4. The incorporation kinetics in MOVPE growth of InxGa1-xAsyP1-y alloy has been analyzed by using an adsorption-trapping model. The As composition (y) of the InxGa1-xAsyP1-y films varies with the TBA gas phase composition ?=TBA/(TBA+TBP) according to the expression y=2Ns*/aN0(1-e-???). It is demonstrated that with the optimized growth conditions, TBA has a higher incorporation efficiency than TBP in MOVPE growth of InxGa1-xAsyP1-y films.

Huang, G. S.; Tang, X. H.; Zhang, B. L.; Tjin, Swee Chuan

2003-10-01

400

Change in form of palladium plate during one-sided saturation with hydrogen: I. Effect of rate of increase in gaseous-hydrogen pressure  

NASA Astrophysics Data System (ADS)

The effect of the rate of gaseous-hydrogen pressure rise on changes in the form of a palladium plate has been studied during its one-sided saturation with hydrogen in the ? region of the Pd-H system under isothermal conditions at temperatures of 170-320°C. The dependences of the principal characteristics of hydrogen-induced changes in the form of a plate on the rate of gaseous hydrogen pressure rise were determined. The decrease in the rate of increase in hydrogen pressure was found to lead to a decrease in the maximum bend of the plate.

Gol'tsova, M. V.; Lyubimenko, E. N.

2012-11-01

401

Isobaric vapor–liquid equilibria for ethanol–water system containing different ionic liquids at atmospheric pressure  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for ethanol–water systems containing ionic liquids (ILs) 1-methyl-3-methylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), 1-butyl-3-methylimidazolium bromide ([BMIM][Br]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) at atmospheric pressure (101.32kPa) were measured with a circulation still. The results showed that the VLE of ethanol–water systems in the presence of different ILs was obviously different from that of the

Jin Zhao; Cong-Cong Dong; Chun-Xi Li; Hong Meng; Zi-Hao Wang

2006-01-01

402

Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method  

NASA Astrophysics Data System (ADS)

A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

2009-12-01

403

Liquid phase epitaxy of GaP by a temperature difference method under controlled vapor pressure  

Microsoft Academic Search

A series of experiments have been done in which the properties of GaP grown by liquid phase epitaxy (LPE) have been varied by providing an additional source of phosphorus via the vapor phase. The quality of the crystals, as judged from gross defect features observed in etched cross sections, is a function of the amount of phosphorus added to the

J. Nishizawa; Y. Okuno

1975-01-01

404

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)  

NASA Technical Reports Server (NTRS)

Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

2002-01-01

405

Pressure generation and measurement in the rapid vaporization of water on a pulsed-laser-heated surface  

SciTech Connect

The transient pressure generated by the interaction of short-pulsed laser light with the liquid{endash}solid interface is studied quantitatively. A KrF excimer laser beam of tens of nanoseconds pulse duration irradiates water on a solid surface and induces rapid thermal expansion and explosive vaporization. The pressure pulses launched into water by such processes are detected experimentally by the photoacoustic probe beam deflection method and a broadband piezoelectric transducer. The peak intensities of the traveling pressure wave measured by these two methods are compared with the theoretical thermoelastic predictions. The measurements show that a compressional pressure wave packet is radiated from the water-solid interface with the peak intensity of the order of 1 MPa at laser fluences up to about 100 mJ/cm{sup 2}. Simultaneous monitoring of the bubble growth kinetics by the optical specular reflectance probe has been performed. It is observed that the pressure generation is enhanced by the bubble expansion in the superheated water for laser fluences exceeding the bubble nucleation thresholds. {copyright} {ital 1996 American Institute of Physics.}

Park, H.K.; Kim, D.; Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Tam, A.C. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099 (United States)] [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099 (United States)

1996-10-01

406

Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in the mid-infrared at atmospheric pressure  

SciTech Connect

We report quantitative broadband infrared spectra of vapor-phase hydrogen peroxide (H2O2) with all spectra pressure broadened to atmospheric pressure. The spectra were generated by flowing a concentrated solution (83 weight%) of H2O2 into a gently heated disseminator and diluting with a flow of pure nitrogen carrier gas. The water vapor lines were subtracted from the resulting spectra to yield the spectrum of pure H2O2. Comparison with previous results for the ?6 band strength (including hot bands) compares favorably with the results of Klee et al. [(1999) J. Mol. Spectr. 195, 154] as well as HITRAN. The present results are 433 and 467 cm-2 atm-1 (±8% and ±3% at 298 and 323 K, respectively) for the band strength, matching well the Klee value (S = 467 cm-2 atm-1 at 296 K) for the integrated band. Other bands in the 520-7500 cm-1 interval and their potential for atmospheric monitoring are discussed.

Johnson, Timothy J.; Sams, Robert L.; Burton, Sarah D.; Blake, Thomas A.

2009-09-01

407

Ionic liquids by proton transfer: vapor pressure, conductivity, and the relevance of DeltapKa from aqueous solutions.  

PubMed

We describe the behavior of the conductivity, viscosity, and vapor pressure of various binary liquid systems in which proton transfer occurs between neat Brönsted acids and bases to form salts with melting points below ambient. Such liquids form an important subgroup of the ionic liquid (IL) class of reaction media and electrolytes on which so much attention is currently being focused. Such "protic ionic liquids" exhibit a wide range of thermal stabilities. We find a simple relation between the limit set by boiling, when the total vapor pressure reaches one atm, and the difference in pK(a) value for the acid and base determined in dilute aqueous solutions. For DeltapK(a) values above 10, the boiling point elevation becomes so high (>300 degrees C) that preemptive decomposition prevents its measurement. The completeness of proton transfer in such cases is suggested by the molten salt-like values of the Walden product, which is used to distinguish good from poor ionic liquids. For the good ionic liquids, the hydrogen bonding of acid molecules to the proton-transfer anion is strong enough that boiling points, but not melting points, may maximize at the hydrogen-bonded dianion composition. High boiling liquids of this type constitute an interesting class of high-temperature protonic acid that may have high-temperature fuel cell applications. PMID:14664586

Yoshizawa, Masahiro; Xu, Wu; Angell, C Austen

2003-12-17

408

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

409

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274–400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

410

Vapor–liquid equilibria for binary mixtures of carbon dioxide with 1,2-dimethoxybenzene, 2-methoxyphenol, or p-cresol at elevated pressures  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) phase compositions were measured for three binary systems of carbon dioxide with 1,2-dimethoxybenzene, 2-methoxyphenol, or p-cresol at temperatures from 323.15 to 423.15 K and pressures up to 20 MPa. The solubilities of these close-boiling heavy components in the vapor phase were compared over the experimental conditions. Henry's constants were calculated from the isothermal equilibrium data. The temperature

Ming-Jer Lee; Chi-Fu Kou; Jung-Wen Cheng; Ho-mu Lin

1999-01-01

411

Real-time explosives/narcotics vapor enhancement and collection systems for use with the atmospheric pressure ionization time-of-flight mass spectrometer  

NASA Astrophysics Data System (ADS)

This paper is a companion document to the Atmospheric Pressure Ionization Time-of-Flight Mass Spectrometer (API TOFMS) presentation (Lee, et al., 1992). Two significant technique challenges related to design and implementation of vapor collection systems are addressed. They are as follows: (1) freeing deposited or trapped explosive material particles or vapor; and (2) transportation of sample specimen from the pickup point to the detector. Addressed in this dissertation will be both hand-held collection and air shower booth accumulation.

Hintze, M. Marx; Hansen, Byron L.; Heath, Russell L.

1992-05-01

412

Bridgman-type apparatus for the study of growth-property relationships - Arsenic vapor pressure-GaAs property relationship  

NASA Technical Reports Server (NTRS)

A precision Bridgman-type apparatus is described which was designed and constructed for the investigation of relationships between crystal growth parameters and the properties of GaAs crystals. Several key features of the system are highlighted, such as the use of a heat pipe for precise arsenic vapor pressure control and seeding without the presence of a viewing window. Pertinent growth parameters, such as arsenic source temperature, thermal gradients in the growing crystal and in the melt, and the macroscopic growth velocity can be independently controlled. During operation, thermal stability better than + or - 0.02 C is realized; thermal gradients can be varied up to 30 C/cm in the crystal region, and up to 20 C/cm in the melt region; the macroscopic growth velocity can be varied from 50 microns/hr to 6.0 cm/hr. It was found that the density of dislocations depends critically on As partial pressure; and essentially dislocation-free, undoped, crystals were grown under As pressure precisely controlled by an As source maintained at 617 C. The free carrier concentration varied with As pressure variations. This variation in free carrier concentration was found to be associated with variations in the compensation ratio rather than with standard segregation phenomena.

Parsey, J. M.; Nanishi, Y.; Lagowski, J.; Gatos, H. C.

1982-01-01

413

Growth of non-polar ZnO thin films with different working pressures by plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Non-polar coexisting m-plane (10\\bar{1}0) and a-plane (11\\bar{2}0) zinc oxide (ZnO) thin films have been synthesized onto commercial silicon (100) substrates by using plasma enhanced chemical vapor deposition (PECVD) system at different working pressures. The effects of the working pressure on crystal orientation, microstructure, surface morphology, and optical properties of the ZnO thin films were investigated. From the X-ray diffraction patterns, the non-polar ZnO thin films were successfully synthesized at the working pressures of 6 and 9 Torr, respectively. The non-polar ZnO thin films showed stripes-like surface morphology and with smooth surface roughness (?3.53 nm) was performed by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM), respectively. All the ZnO films show a remarkable near-band-edge (NBE) emission peak located at ultraviolet (UV) band accompanying a negligible deep-level (DL) emission at visible region detected by photoluminescence (PL) spectra at room temperature. From the above systematic measurement analysis, indicating the better crystallinity and optical character of ZnO thin film was improved with reducing the working pressure. The wettability of non-polar ZnO thin films was also explored in this presented article.

Chao, Chung-Hua; Wei, Da-Hua

2014-11-01

414

Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report  

SciTech Connect

Rock types that are likely candidates for drilling were tested. Reported herein are the short-time ultimate strengths and ductilities determined at temperatures of 25/sup 0/ to 1050/sup 0/C and a strain rate of 10/sup -4/s/sup -1/ of (a) room-dry Mt. Hood Andesite, Cuerbio Basalt, and Charcoal (St. Cloud Gray) Granodiorite at confining pressures of 0, 50, and 100 MPa, (b) water-saturated specimens of the same three rocks at zero effective pressure (both pore and confining pressures of 50 MPa), and (c) room-dry Newberry Rhyolite Obsidian at 0 and 50 MPa. These strengths are then compared with the stresses developed at the wall of a borehole in an elastic medium at the appropriate temperatures and mean pressures to assess the problem of borehole stability. (MHR)

Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

1980-11-01

415

Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPA and temperatures to partial melting  

SciTech Connect

The short-term failure strengths and strains at failure of room-dry and water-saturated, cylindrical specimens (2 by 4 cm) of Charcoal Granodiorite (CG), Mt. Hood Andesite (MHA), and Cuerbio Basalt (CB) at a strain rate of 10/sup -4/s/sup -1/, at effective confining pressures of 0, 50, and 100 MPa and at temperatures to partial melting were investigated. Data from water-saturated specimens of the granodiorite and andesite, compared to room-dry counterparts, indicate (1) the pore pressures are essentially communicated throughout each test specimen so that they are fully effective; (2) at P/sub e/ = 0 and 50 MPa the granodiorite does not water-weaken; (3) at these same effective pressures the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (4) at P/sub e/ = 0 and 870 to 900/sup 0/C the andesite's strength averages 20 MPa while the strength of dry specimens at the same P and T exhibit a strength of 100 MPa; (5) at P/sub e/ = 50 MPa compared to 160 MPa dry; (6) the basalt at P/sub e/ = 0, appears to be water-weakened at 800/sup 0/C; (7) water saturated specimens deformed at temperatures less than that of melting exhibit ultimate strengths at less than 2% shortening and then work-soften along faults; (8) again as do the dry counterparts, the wet specimens deform primarily by microscopic fracturing that coalesces into one or more macroscopic faults; and (9) the temperature for incipient melting of the andesite is decreased >150/sup 0/C in the water-saturated tests.

Bauer, S.J.; Friedman, M.; Handin, J.

1981-01-01

416

Application of precise line shape measurements to determine the vapor pressure of ice in the temperature range from 0 to -70 deg. C  

SciTech Connect

We performed spectroscopic measurement of the vapor pressure of ice. We describe an experimental method that enables such a measurement over a wide temperature range that covers the change of the vapor pressure of ice by a few orders of magnitude. Our preliminary results have relative uncertainties at the sub-percent level and are compared to correlations given by Wexler [A. Wexler, J. Res. NBS 81A, 5 (1977)] and Marti and Mauersberger [J. Marti and K. Mauersberger, Geophys. Res. Lett. 20,363 (1993)].

Bielska, K.; Lisak, D. [Instytut Fizyki, Uniwersytet Mikolaja Kopernika, ul. Grudziadzka 5, 87-100 Torun (Poland); Havey, D. K.; Scace, G. E.; Hodges, J. T. [National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899 (United States)

2010-10-29

417

Electrical and optical properties of doped tin and zinc oxide thin films by atmospheric pressure chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Zinc oxide and tin oxide films have been deposited by atmospheric pressure chemical vapor deposition. Zinc oxide films doped with fluorine have higher mobility and higher visible transmission than those doped with the Group III elements (B, Al, Ga). A ZnO:F film with a sheet resistance of 5 ?/square has an average visible absorption of about 3%. Various doped zinc oxide films were compared with each other and with SnO2:F films through their Figure of Merit, which is defined as the ratio of the conductivity over the visible absorption coefficient. Zinc oxide films doped with fluorine have the highest Figure of Merit and are very promising as transparent electrodes for solar cells with high cell efficiency.

Hu, Jianhua; Gordon, Roy G.

1992-12-01

418

Tree ring wood analysis after hydrogen peroxide pressure decomposition with inductively coupled plasma atomic emission spectrometry and electrothermal vaporization  

SciTech Connect

A method utilizing pressure decomposition to minimize sample pretreatment is described for the inductively coupled plasma atomic emission spectrometric analysis of red spruce and sugar maple. Cores collected from trees growing on Camels Hump Mountain, Vermont, were divided into decade increments in order to monitor the temporal changes in concentrations of 21 elements. Dried wood samples were decomposed in a bomb made of Teflon with 50% hydrogen peroxide heated in an oven at 125/sup 0/C for 4 h. The digestion permitted use of aqueous standards and minimized any potential matrix effects. The element concentrations were obtained sequentially by electrothermal vaporization ICP-AES using 5 ..mu..L sample aliquots. The method precision varied between 3 and 12%. Elements forming oxyanions (Al, As, Fe, Ge, Mn, Si, V) were found at elevated concentrations during the most recent three decades, while other metal (e.g., Mg, Zn) concentrations were unchanged or decreased. 45 references, 6 tables, 1 figure.

Matusiewicz, H.; Barnes, R.M.

1985-02-01

419

Vapor-pressure osmometric study of the molecular weight and aggregation tendency of a reference-soil fulvic acid  

USGS Publications Warehouse

The molecular weight and aggregation tendency of a reference-soil fulvic acid in Armadale horizon Bh were determined by vapor-pressure osmometry using tetrahydrofuran and water as solvents. With tetrahydrofuran, number-average molecular weight values of 767 ?? 34 and 699 ?? 8 daltons were obtained from two separate sets of measurements. Two sets of measurements with water also yielded values within this range (754 ?? 70 daltons) provided that the fulvic acid concentration in water did not exceed 7 mg ml-1; at higher concentrations (9.1-13.7 mg ml-1) a number-average molecular weight of 956 ?? 25 daltons was resolved, providing evidence of molecular aggregation. Extension of these studies to 80% neutralized fulvic acid showed that a sizeable fraction of the sodium counter ion is not osmotically active.

Marinsky, J.A.; Reddy, M.M.

1990-01-01

420

High-Pressure Water-Vapor Annealing for Enhancement of a-Si:H Film Passivation of Silicon Surface  

NASA Astrophysics Data System (ADS)

We investigate the effect of amorphous hydrogenated silicon (a-Si:H) films passivated on silicon surfaces based on high-pressure water-vapor annealing (HWA). The effective carrier lifetime of samples reaches the maximum value after 210°C, 90min HWA. Capacitance-voltage measurement reveals that the HWA not only greatly reduces the density of interface states (Dit), but also decreases the fixed charges (Qfixed) mainly caused by bulk defects. The change of hydrogen and oxygen in the film is measured by a spectroscopic ellipsometer and a Fourier-transform infrared (FTIR) spectrometer. All these results show that HWA is a useful method to improve the passivation effect of a-Si:H films deposited on silicon surfaces.

Guo, Chun-Lin; Wang, Lei; Zhang, Yan-Rong; Zhou, Hai-Feng; Liang, Feng; Yang, Zhen-Hui; Yang, De-Ren

2014-10-01

421

Surface Passivation of HgCdTe Using Low-Pressure Chemical Vapor Deposition of CdTe  

NASA Astrophysics Data System (ADS)

CdTe passivation films have been deposited on Hg1- x Cd x Te ( x = 0.35) samples used for infrared detectors by low-pressure chemical vapor deposition (LPCVD) and atomic layer deposition (ALD) at temperatures as low as 135°C to 170°C. ALD has been used to deposit an initially uniform starting surface before continuing the deposition using LPCVD. Favorable conformal coverage has been demonstrated on high-aspect-ratio HgCdTe structures. LPCVD deposition rates of 40 nm/h to 70 nm/h were obtained by varying the sample temperature from 135°C to 170°C. Lifetime measurements carried out at 300 K exhibited a significant improvement in minority-carrier lifetime from 0.9 ?s (sample without passivation) to 4.28 ?s for samples passivated at 135°C.

Banerjee, Sneha; Su, Peng-Yu; Dahal, Rajendra; Bhat, Ishwara B.; Bergeson, Jeremy D.; Blissett, Caleb; Aqariden, Fikri; Hanyaloglu, Bengi

2014-08-01

422

Compact electron-beam source for formation of neutral beams of very low vapor pressure materials  

NASA Technical Reports Server (NTRS)

In order to form metal vapors for neutral beam studies, an electron-beam heater and a power supply have been designed. The source, which measures about 30 x 50 x 70 mm, consists of a filament, accelerating plate (defined by pole pieces), and a supported target. The electrons from the filament are focused by the field penetration through a 2 mm slit in the high-voltage cage. They are then accelerated to about 5 kV to a ground plate. The electrons then follow a path in the magnetic field and strike the sample to be heated on its front surface. The assembly is attached to a water-cooled base plate. The electron beam source has produced beams of Ta and C particles with densities of about 10 to the 8th power/cu cm.

Rutherford, J. A.; Vroom, D. A.

1978-01-01

423

Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds  

NASA Technical Reports Server (NTRS)

Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

1993-01-01

424

saturated liquid. The region above the vapor line is superheated vapor; that below the lower line is subcooled liquid. The region enclosed by the pair represents a mixture of liquid and  

E-print Network

for refrigeration at two different temperature levels--for the freezer compartment and for the refrigerator from the freezer compartment to the refrigerator compartment, and (2) p, the refrigerant will be a mixture of liquid and vapor, as usually occurs in a single-refrigerant system. One

Oak Ridge National Laboratory

425

Computing boiling temperatures and vapor pressures in homologous series of perfluorinated oligomers  

NASA Astrophysics Data System (ADS)

Correlation relationships are proposed for computing boiling temperatures of T b oligomers with the general formula R1(CF2) n R2 at normal pressure, where R1 and R2 are arbitrary end groups and the increment of the CF2 fragment is 20.4 K. The dependences of coefficients A and B in the Clausius-Clapeyron equation (ln P = A - B/ T) on the length of the oligomer chain are determined by computing critical temperatures and pressures using an additive scheme.

Kim, I. P.

2013-07-01

426

Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas  

NASA Technical Reports Server (NTRS)

A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.

Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.

1996-01-01

427

Disjoining pressure and capillarity in the constrained vapor bubble heat transfer system  

Microsoft Academic Search

Using the disjoining pressure concept in a seminal paper, Derjaguin, Nerpin and Churaev demonstrated that isothermal liquid flow in a very thin film on the walls of a capillary tube enhances the rate of evaporation of moisture by several times. The objective of this review is to present the evolution of the use of Churaev's seminal research in the development

Arya Chatterjee; Joel L. Plawsky; Peter C. Wayner

2011-01-01

428

The Effects of Massage with Coconut and Sunflower Oils on Oxygen Saturation of Premature Infants with Respiratory Distress Syndrome Treated With Nasal Continuous Positive Airway Pressure  

PubMed Central

Introduction: Nowadays particular emphasis is placed on the developmental aspects of premature infants care. Massage therapy is one of the best-known methods of caring. Due to the minimal touch policy in neonatal intensive care units (NICUs), massaging is not usually performed on premature infants. However, there is not sufficient evidence to support the claim that newborn infants with complex medical conditions should not be massaged. This study aimed to determine the effects of massage with coconut and sunflower oils on oxygen saturation of infants with respiratory distress syndrome (RDS) treated with nasal continuous positive airway pressure (NCPAP). Methods: This was a randomized controlled trial on 90 newborns who were admitted to Alzahra Hospital (Tabriz, Iran). The infants were divided into control and massage therapy groups (massage with coconut and sunflower oils). Data was collected using a hospital documentation form. A 15-minute daily massage was performed for 3 days. Respiratory rate (RR), fraction of inspired oxygen (FiO2) and oxygen saturation were measured 5 minutes before the massage, 3 times during the massage, and 5 minutes after the massage. The collected data was analyzed using a mixed model. Results: In comparison to coconut oil and control groups, mean oxygen saturation of sunflower oil group was improved. In addition, the coconut massage group showed lower oxygen saturation than the control group but was all values were within the normal range. Although massage decreased oxygen saturation, there was no need to increase FiO2. Conclusion: Massage therapy can provide developmental care for infants treated with NCPAP. PMID:25276695

Valizadeh, Sousan; Hosseini, Mohammad Bagher; Asghari Jafarabadi, Mohammad; Ajoodanian, Najmeh

2012-01-01

429

Sensitivity of mean canopy stomatal conductance to vapor pressure deficit in a flooded Taxodium distichum L. forest: hydraulic and non-hydraulic effects  

Microsoft Academic Search

We measured the xylem sap flux in 64-year- old Taxodium distichum (L.) Richard trees growing in a flooded forest using Granier-type sensors to estimate mean canopy stomatal conductance of the stand (GS). Temporal variations in GS were investigated in relation to variation in vapor pressure deficit ( D), photosynthetic photon flux density (Qo), and the transpiration rate per unit of

R. Oren; J. S. Sperry; B. E. Ewers; D. E. Pataki; N. Phillips; J. P. Megonigal

2001-01-01

430

Measurements of viscosity of refrigerants in the vapor phase  

SciTech Connect

Measurements of the viscosity of refrigerants R124, R125, R134a, and R152a in the vapor phase are presented. The measurements, performed in a new vibrating-wire instrument, cover a temperature range from 273 to 333 K from about atmospheric pressure up to below the saturation pressure. The uncertainty of the reported values is estimated to be better than {+-}1%. Comparison with measurements of other investigators reveals a lack of reliable data in the vapor region for these compounds.

Assael, M.J.; Polimatidou, S.K. [Aristotle Univ., Thessaloniki (Greece). Faculty of Chemical Engineering

1997-03-01

431

Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries  

NASA Astrophysics Data System (ADS)

The ?-? interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance.

Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

2014-12-01

432

Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries  

PubMed Central

The ?-? interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance. PMID:25490893

Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

2014-01-01

433

Smectics and smectic-like phases: Equation of state, finite size effects and vapor pressure paradox  

Microsoft Academic Search

In this dissertation, I pursue the constant pressure ensemble approach to elucidate the statistical mechanics of smectic phases of semi-flexible manifolds. I use this approach to consider in detail sterically stabilized phases of semi-flexible polymers in two-dimensional smectic systems. For the first time, the universal constants characterizing the entropic repulsion between semi-flexible polymers are obtained. The thermodynamic limit is quickly

Lianghui Gao

2004-01-01

434

Dynamics of a Spherical Vapor\\/Gas Bubble in Varying Pressure Fields  

Microsoft Academic Search

A mathematical model is developed to simulate the radial motion of cavitation bubbles. The heat and mass transports including phase change are formulated precisely. In order to reduce the computational cost without loss of the important thermo-fluid phenomena, two simplifications are employed: time-dependent bubble radius is described using the Rayleigh-Plesset equation; the pressure in the bubble is assumed to be

Hisanobu Kawashima; Masaharu Kameda

2008-01-01

435

Low-Temperature Growth of Epitaxial Si Films by Atmospheric Pressure Plasma Chemical Vapor Deposition Using Porous Carbon Electrode  

NASA Astrophysics Data System (ADS)

The low-temperature growth of epitaxial Si films by atmospheric pressure plasma chemical vapor deposition (AP-PCVD) was investigated. A 150 MHz very high frequency (VHF) power supply was used to generate an atmospheric pressure plasma of gas mixtures containing He, H2, and SiH4. Two types of electrode (i.e., cylindrical rotary and porous carbon electrodes) were used in plasma generation. When a cylindrical rotary electrode was used, polycrystalline Si growth was inevitable at the film edge on the upstream side. This is due to the variation in deposition rate along the gas flow direction, which is extremely high at the plasma/atmosphere interface on the upstream side. To solve this problem, we developed a novel porous carbon electrode where process gas molecules are directly supplied into the plasma region through a porous carbon plate a distance (0.8 mm) away from the substrate surface. Using such a porous carbon electrode, we successfully grew a defect-free epitaxial Si film on the entire surface of a 4 in. Si wafer at 600 °C. The average growth rate was 0.25-0.3 ?m/min, which is as high as that obtained by thermal CVD at 900 °C. The epitaxial Si films grown at 600 °C were characterized by various methods, including transmission electron microscopy, atomic force microscopy, secondary ion mass spectrometry, and selective etching. The influence of adsorbed impurities in the porous carbon material on the quality of epitaxial Si films was also investigated.

Ohmi, Hiromasa; Kakiuchi, Hiroaki; Tawara, Naotaka; Wakamiya, Takuya; Shimura, Takayoshi; Watanabe, Heiji; Yasutake, Kiyoshi

2006-10-01

436

Subatmospheric vapor pressures for fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a) evaluated from internal-energy measurements  

SciTech Connect

Vapor pressures were evaluated from measured internal-energy changes {Delta}U{sup (2)} in the vapor + liquid two-phase region. The method employed a thermodynamic relationship between the derivative quantity ({partial_derivative}U{sup (2)}/{partial_derivative}V){sub T}, the vapor pressure p{sub {sigma}}, and its temperature derivative ({partial_derivative}p/{partial_derivative}T){sub {sigma}}. This method was applied at temperatures between the triple point and the normal boiling point of three substances: fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a). In the case of R41, vapor pressures up to 1 MPa were calculated to validate the technique at higher pressures. For R152a, the calculated vapor pressure at the triple-point temperature differed from a direct experimental measurement by less than the claimed uncertainty (5 Pa) of the measurement. The calculated vapor pressures for R41 helped to resolve discrepancies in several published vapor pressure sources. Agreement with experimentally measured vapor pressures for R152a and for R143a near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately 0.04 kPa (0.04%) for the published measurements.

Duarte-Garza, H.A.; Magee, J.W.

1999-09-01

437

Correlation Between Jugular Bulb Oxygen Saturation and Partial Pressure of Brain Tissue Oxygen During CO 2 and O 2 Reactivity Tests in Severely Head-Injured Patients  

Microsoft Academic Search

Summary  ?Purpose. To correlate the jugular bulb oxygen saturation (SjvO2) and brain tissue oxygen pressure (PbtO2) during carbon dioxide (CO2) and oxygen (O2) reactivity tests in severely head-injured patients.\\u000a \\u000a ?Methods and Results. In nine patients (7 men, 2 women, age: 26?6.5 years, GCS of 6.5?2.9), a polarographic microcatheter (Clark-type) was inserted\\u000a into nonlesioned white matter (frontal lobe). PbtO2 and SjvO2 were

J. Fandino; R. Stocker; S. Prokop; H.-G. Imhof

1999-01-01

438

Long Term Measurement of the Vapor Pressure of Gold in the Au-C System  

NASA Technical Reports Server (NTRS)

Incorporating the {Au(s,l) + graphite} reference in component activity measurements made with the multiple effusion-cell vapor source mass spectrometry (multicell KEMS) technique provides a fixed temperature defining ITS-90 (T(sub mp)(Au) = 1337.33K) and a systematic method to check accuracy. Over a 2 year period delta H sub(298)Au was determined by the 2nd and 3rd law methods in 25 separate experiments and were in the ranges 362.2 plus or minus 3.3 kJmol(sup -1) and 367.8 plus or minus 1.1 kJmol(sup -1), respectively. This 5 kJmol-1 discrepancy is transferred directly to the measured activities. This is unacceptable and the source of this discrepancy needs to be understood and corrected. Accepting the 2nd law value increases p(Au) by about 50 percent, brings the 2nd and 3rd law values into agreement and removes the T dependence in the 3rd law values. While compelling, there is no way to independently determine instrument sensitivities, S(sub Au), with T in a single experiment with KEMS. This lack of capability is stopping a deeper understanding of this problem. In addition, the Au-C phase diagram suggests a eutectic invariant reaction: L-Au(4.7at%C) = FCC-Au(0.08at%C) + C(graphite) at T(sub e) approximately 1323K. This high C concentration in Au(l) must reduce p(Au) in equilibrium with {Au(s,l) + graphite} and raises some critical questions about the Gibbs free energy functions of Au(s,l) and the Au fixed point (T(sub mp)(Au) = 1337.33K) which is always measured in graphite.

Copland, Evan H.

2009-01-01

439

Calibrated vapor generator source  

SciTech Connect

A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

1995-09-26

440

Boiling liquid expanding vapor explosion: experimental research in the evolution of the two-phase flow and over-pressure.  

PubMed

In a boiling liquid expanding vapor explosion (BLEVE), the superheating and boiling of the liquefied gas inside the vessel as it fails is important information necessary to understand the mechanism of this type of disaster. In this paper, a small-scale experiment was developed to investigate the possible processes that could lead to a BLEVE. Water was used as the test fluid. High-speed video was utilized to observe the two-phase flow swelling which occurred immediately following the partial loss of containment through a simulated crack. The velocity of the two-phase swelling was measured along with pressure and temperature. It was observed that initially a mist-like two-phase layer was rapidly formed on the liquid surface (~3-4 ms) after the vessel opened. The superheated liquid rapidly boiled and this accelerated upwards the two-phase layer, the whole liquid boiled after about 17 ms form opening. It was supposed that the swelling of the two-phase layer was the possible reason for the first over-pressure measured at the top and bottom of the vessel. From 38 ms to 168 ms, the boiling of the superheated liquid weakened. And from 170 ms, the original drop/mist-like two-phase flow turned into a churn-turbulent bubbly two-phase flow, rose quickly in the field of the camera and eventually impacted the vessel top wall. The force of its impact and "cavitation" and "choke" following with the two-phase ejection were maybe main reasons for the second obvious pressure increasing. PMID:18261848

Chen, Sining; Sun, Jinhua; Wan, Wei

2008-08-15

441

Line mixing in some water vapor transitions perturbed by N2, Ar and He pressure  

NASA Astrophysics Data System (ADS)

Line mixing effect has been studied for five pairs of H2O lines perturbed by N2, Ar and He. Two pairs of lines (in terms of the rotational quantum numbers J, Ka, and Kc) [1 0 1] ? [2 1 2], [2 1 2] ? [3 0 3] and [3 0 3] ? [2 1 2], [2 1 2] ? [1 0 1] belong to the ?2 band, two pairs of lines [3 1 2] ? [4 1 3], [3 2 1] ? [4 2 2] and [4 3 1] ? [3 3 0], [4 2 2] ? [3 2 1], belong to the ?1 + ?2 + ?3 band and fifth pair of the lines [5 4 1] ? [6 5 2], [5 4 1] ? [6 3 4] belong to the 3?1 + ?2 and 8?2 band, respectively. Pressure broadening coefficients of H2O (half-widths, pressure shifts and off-diagonal relaxation matrix elements) have been calculated for all lines and for two pair of lines from the ?1 + ?2 + ?3 band perturbed by N2 and Ar they have been obtained experimentally.

Petrova, T. M.; Solodov, A. M.; Solodov, A. A.; Starikov, V. I.

2015-01-01

442

Meteorological Tables for Determination of Precipitable Water, Temperatures and Pressures Aloft for a Saturated Pseudoadiabatic Atmosphere -- in the Metric System  

E-print Network

of snowmelt over mountainous basins where the temperatures range considerably with elevation. Additionally, information on atmospheric pressure in millibars for selected heights was obtained. Thermodynamic considerations in the computational scheme...

Eihle, W. O.; Powers, R. J.; Clark, R.A.

443

Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure  

NASA Technical Reports Server (NTRS)

A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

Ouazzani, Jalil; Rosenberger, Franz

1990-01-01

444

Vapor Pressures and Vaporization Enthalpies of the n-Alkanes from C21 to C30 at T ) 298.15 K by Correlation Gas Chromatography  

E-print Network

by Correlation Gas Chromatography James S. Chickos* and William Hanshaw Department of Chemistry and Biochemistry of transfer from solution to the gas phase as measured by gas chromatography.3 A plot of the vaporization interest in using the larger n-alkanes as stan- dards for correlation gas chromatography measurements (c

Chickos, James S.

445

Some properties of low-vapor-pressure braze alloys for thermionic converters  

NASA Technical Reports Server (NTRS)

Density, dc electrical resistivity, thermal conductivity, and linear thermal expansion are measured for arc-melted rod-shaped samples of binary eutectics of Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W selected as very-low-pressure braze fillers for thermionic converters. The first two properties are measured at 296 K for Zr-21.7 at% Ru, Zr-13 wt% W, Zr-19 wt% W, Zr-22.3 at% Nb, Nb-66.9 at% Ru, Hf-25.3 wt% Re, Zr-25.7 at% Ta, Hf-22.5 at% W, and Nb-35 wt% Mo. The last property is measured from 293 K to 2/3 melting point for specified alloys of different compositions. Resistivities of 0.000055 to 0.000181 ohm-cm are observed with the alloys having resistivities about ten times that of the less resistive constituent metal and about three times that of the more resistive constituent metal, except for Zr-19 wt% W and Nb-35 wt% Mo (greater resistivities). Thermal expansion coefficients vary from 0.000006 to 0.0000105/K. All brazes exhibit linear thermal expansion near that of their constituent metals.

Bair, V. L.

1978-01-01

446

Step-coverage simulation for tetraethoxysilane and ozone atmospheric pressure chemical vapor deposition  

SciTech Connect

A simulation model for atmospheric pressure (AP) CVD has bee developed using one-dimensional diffusion and mass conservation equations. The model was applied to trench step-coverage of the tetraethoxysilane (TEOS) and O[sub 3] CVD, in which it was not necessary to consider lateral diffusion because of narrow (and deep) trenches. For nondoped silicate glass (NSG), the step-coverage of a 4.5 aspect ratio trench showed a good fit if a sticking probability of 0.0039 was assumed for the 0.6% ozone (in oxygen) deposition and of 0.0026 for the 6% ozone deposition (both 400 C). The reaction rate constant was compared with the diffusion mass-transfer coefficient, and the reaction proved to be limited by diffusion of the reactant, TEOS, which directly participated in the CVD reaction. For the 2 m/o phosphosilicate glass (PSG) step-coverage, which had a slight overhang, the model matched the obtained results well only when an active growth species with a high sticking probability of 1.0 was added to the growth species of nondoped oxide. This analytical simulation method satisfactorily explains the experimental data.

Fujino, K. (Semiconductor Process Lab., Toyko (Japan)); Egashira, Y.; Shimogaki, Y.; Komiyama, H. (Univ. of Tokyo, (Japan). Dept. of Chemical Engineering)

1993-08-01

447

High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

448

Pre-conditioning the epigenetic response to high vapor pressure deficit increases the drought tolerance of Arabidopsis thaliana.  

PubMed

Epigenetic modification of the genome via cytosine methylation is a dynamic process that responds to changes in the growing environment. This modification can also be heritable. The combination of both properties means that there is the potential for the life experiences of the parental generation to modify the methylation profiles of their offspring and so potentially to "pre-condition" them to better accommodate abiotic conditions encountered by their parents. We recently identified high vapor pressure deficit (vpd)-induced DNA methylation at 2 gene loci in the stomatal development pathway and an associated reduction in leaf stomatal frequency. (1) Here, we test whether this epigenetic modification pre-conditioned parents and their offspring to the more severe water stress of periodic drought. We found that 3 generations of high vpd-grown plants were better able to withstand periodic drought stress over 2 generations. This resistance was not directly associated with de novo methylation of the target stomata genes, but was associated with the cmt3 mutant's inability to maintain asymmetric sequence context methylation. If our finding applies widely, it could have significant implications for evolutionary biology and breeding for stressful environments. PMID:24270688

Tricker, Penny; Rodríguez López, Carlos; Hadley, Paul; Wagstaff, Carol; Wilkinson, Mike

2013-10-01

449

Electrical properties of low pressure chemical vapor deposited silicon nitride thin films for temperatures up to 650 °C  

NASA Astrophysics Data System (ADS)

The results of a study on electrical conduction in low pressure chemical vapor deposited silicon nitride thin films for temperatures up to 650 °C are described. Current density versus electrical field characteristics are measured as a function of temperature for 100 and 200 nm thick stoichiometric (Si3N4) and low stress silicon-rich (SiRN) films. For high E-fields and temperatures up to 500 °C conduction through Si3N4 can be described well by Frenkel-Poole transport with a barrier height of ˜1.10 eV, whereas for SiRN films Frenkel-Poole conduction prevails up to 350 °C with a barrier height of ˜0.92 eV. For higher temperatures, dielectric breakdown of the Si3N4 and SiRN films occurred before the E-field was reached above which Frenkel-Poole conduction dominates. A design graph is given that describes the maximum E-field that can be applied over silicon nitride films at high temperatures before electrical breakdown occurs.

Tiggelaar, R. M.; Groenland, A. W.; Sanders, R. G. P.; Gardeniers, J. G. E.

2009-02-01

450

Activity coefficients and free energies of nonionic mixed surfactant solutions from vapor-pressure and freezing-point osmometry.  

PubMed

The thermodynamic properties of mixed surfactant solutions are widely investigated, prompted by numerous practical applications of these systems and by interest in molecular association and self-organization. General techniques for measuring thermodynamic activities, such as isopiestic equilibration, are well-established for multicomponent solutions. Surprisingly, these techniques have not yet been applied to mixed surfactant solutions, despite the importance of the free energy for micelle stability. In this study, equations are developed for the osmotic coefficients of solutions of nonionic surfactant A + nonionic surfactant B. A mass-action model is used, with virial equations for the activity coefficients of the micelles and free surfactant monomer species. The equations are fitted to osmotic coefficients of aqueous decylsulfobetaine + dodecylsulfobetaine solutions measured by vapor-pressure and freezing-point osmometry. Equilibrium constants for mixed-micelle formation are calculated from the free monomer concentrations at the critical micelle concentrations. The derived activity coefficients of the micelles and free monomers indicate large departures from ideal solution behavior, even for dilute solutions of the surfactants. Stoichiometric activity coefficients of the total surfactant components are evaluated by Gibbs-Duhem integration of the osmotic coefficients. Relatively simple colligative property measurements hold considerable promise for free energy studies of multicomponent surfactant solutions. PMID:21504169

MacNeil, Jennifer A; Ray, Gargi Basu; Leaist, Derek G

2011-05-19

451

In Situ Measurement, Characterization, and Modeling of Two-Phase Pressure Drop Incorporating Local Water Saturation in PEMFC Gas Channels  

NASA Astrophysics Data System (ADS)

Proton Exchange Membrane Fuel Cells (PEMFCs) have been an area of focus as an alternative for internal combustion engines in the transportation sector. Water and thermal management techniques remain as one of the key roadblocks in PEMFC development. The ability to model two-phase flow and pressure drop in PEMFCs is of significant importance to the performance and optimization of PEMFCs. This work provides a perspective on the numerous factors that affect the two-phase flow in the gas channels and presents a comprehensive pressure drop model through an extensive in situ fuel cell investigation. The study focused on low current density and low temperature operation of the cell, as these conditions present the most challenging scenario for water transport in the PEMFC reactant channels. Tests were conducted using two PEMFCs that were representative of the actual full scale commercial automotive geometry. The design of the flow fields allowed visual access to both cathode and anode sides for correlating the visual observations to the two-phase flow patterns and pressure drop. A total of 198 tests were conducted varying gas diffusion layer (GDL), inlet humidity, current density, and stoichiometry; this generated over 1500 average pressure drop measurements to develop and validate two-phase models. A two-phase 1+1 D modeling scheme is proposed that incorporates an elemental approach and control volume analysis to provide a comprehensive methodology and correlation for predicting two-phase pressure drop in PEMFC conditions. Key considerations, such as condensation within the channel, consumption of reactant gases, water transport across the membrane, and thermal gradients within the fuel cell, are reviewed and their relative importance illustrated. The modeling scheme is shown to predict channel pressure drop with a mean error of 10% over the full range of conditions and with a mean error of 5% for the primary conditions of interest. The model provides a unique and comprehensive basis for developing a fundamental adiabatic two-phase flow pressure drop predictive scheme for PEMFC reactant channels.

See, Evan J.

452

The effects of wettability and trapping on relationships between interfacial area, capillary pressure and saturation in porous media: A pore-scale network modeling approach  

NASA Astrophysics Data System (ADS)

SummaryWe use a three-dimensional mixed-wet random pore-scale network model to investigate the impact of wettability and trapping on the relationship between interfacial area, capillary pressure and saturation in two-phase drainage and imbibition processes. The model is a three-dimensional network of interconnected pores and throats of various geometrical shapes. It allows multiple phases to be present in each capillary element in wetting and spreading layers, as well as occupying the center of the pore space. Two different random networks that represent the pore space in Berea and a Saudi Arabia reservoir sandstone are used in this study. We allow the wettability of the rock surfaces contacted by oil to alter after primary drainage. The model takes into account both contact angle and trapping hystereses. We model primary oil drainage and water flooding for mixed-wet conditions, and secondary oil injection for a water-wet system. The total interfacial area for pores and throats are calculated when the system is at capillary equilibrium. They include contributions from the arc menisci (AMs) between the bulk and corner fluids, and from the main terminal menisci (MTMs) between different bulk fluids. We investigate hysteresis in these relationships by performing water injection into systems of varying wettability and initial water saturation. We show that trapping and contact angle hystereses significantly affect the interfacial area. In a strongly water-wet system, a sharp increase is observed at the beginning of water flood, which shifts the area to a higher level than primary drainage. As we change the wettability of the system from strongly water-wet to strongly oil-wet, the trapped oil saturation decreases significantly. Starting water flood from intermediate water saturations, greater than the irreducible water saturation, can also affect the non-wetting phase entrapment, resulting in different interfacial area behaviors. This can increase the interfacial area significantly in oil-wet systems. A qualitative comparison of our results with the experimental data available in literature for glass beads shows, with some expected differences, an encouraging agreement. Also, our results agree well with those generated by the previously developed models.

Raeesi, Behrooz; Piri, Mohammad

2009-10-01

453

Vapor Pressures in the Al(I)+Al2O3(s) System: Reconsidering Al2O3(s) Condensation  

NASA Technical Reports Server (NTRS)

The vaporization behavior of the A1-O system has been studied on numerous occasions but significant uncertainties remain. The origin of this uncertainty must be understood before A1-O vaporization behavior can be accurately determined. The condensation of A12O3 and clogging of the effusion orifice is a difficult problem for the Knudsen effusion technique that influences the measured vaporization behavior but has only received limited attention. This study reconsiders this behavior in detail. A new theory for A12O3 condensation is proposed together with procedures that will improve the measured thermodynamic properties of A1-O vaporization.

Copland, Evan

2005-01-01

454

Assessment of a five-layer laminate technique to measure the saturation solubility of drug in pressure-sensitive adhesive film.  

PubMed

A five-layer laminate technique is used to determine the saturation solubility of a drug in a thin polymer film, c(p)(s), of pressure-sensitive adhesive (PSA) used to prepare transdermal patches. A drug-loaded donor polymer film is attached via a separating membrane to an initially drug-free acceptor polymer film. Diffusion of drug occurs into the acceptor up to saturation solubility equilibrium. This systematic study of the technique using the drug tamsulosin and the PSA Duro Tak 87-4098 was a kinetic analysis of the diffusion process. It was found that the technique gives an equilibrium value for c(p)(s) in a PSA polymer film in the presence of crystalline phase of the drug in the donor. A highly permeable Perthese-separating membrane caused overshoot in the acceptor, most likely induced by initial supersaturation of the donor. Change to a less-permeable ethylene-vinyl-acetate-separating membrane avoided overshoot, but gave a prolonged time, >300 days, to equilibrium. Preloading the acceptor accelerated the equilibration process to approximately 50 days with the Perthese. Suitable experimental conditions are identified that, if performed correctly, allow the technique to give an equilibrium value for c(p)(s). PMID:22529028

Reismann, Simone; Lee, Geoffrey

2012-07-01

455

Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms  

Microsoft Academic Search

1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and

Gerhard Laus; Max Andre; Gino Bentivoglio; Herwig Schottenberger

2009-01-01

456

Vapor pressure determinations of 8-2 fluorortelomer alcohol and 1-H perfluorooctane by capillary gas chromatography Relative retention time versus headspace methods.  

PubMed

Two distinctly different capillary gas chromatographic methods were used to determine the vapor pressure of 8-2 fluorotelomer alcohol (8-2 FTOH) and 1-H perfluoroheptane at several temperatures. For measurements employing the relative retention-time method, a short polymethylsiloxane column was used from 25 to 65 degrees C. For the 8-2 FTOH, hydrocarbon alcohols and perfluoroalcohols were used as reference standards. For 1-H perfluoroheptane, hydrocarbons were used as reference standards. Vapor pressure estimates could differ by as much as an order of magnitude compared to published results determined by other (nonchromatographic) methods. This variance may be a function of solvent-solute interactions within the gas chromatographic column and the infinite dilution assumption, both used in the relative retention method. For comparison, data were also gathered using headspace gas chromatography (GC) with atomic emission detection (AED). The results from this novel GC/AED method were consistent with prior nonchromatographic results. A discussion of why headspace is the preferred technique for the determination of vapor pressure for fluorinated compounds is presented. PMID:16443234

Cobranchi, Daryl P; Botelho, Miguel; Buxton, L William; Buck, Robert C; Kaiser, Mary A

2006-03-10

457

Multi-scale influence of vapor pressure deficit on fire ignition and spread in boreal forest ecosystems  

NASA Astrophysics Data System (ADS)

Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different aspects of fire dynamics, including ignition, daily fire spread, and cumulative annual burned area. Here we combined Moderate-Resolution Imaging Spectroradiometer (MODIS) active fires (MCD14ML), MODIS imagery (MOD13A1) and ancillary historic fire perimeter information to produce a data set of daily fire spread maps for Alaska during 2002-2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed with daily vapor pressure deficit (VPD) observations from the North American Regional Reanalysis (NARR) and lightning strikes from the Alaska Lightning Detection Network (ALDN). We found a significant relationship between daily VPD and likelihood that a lightning strike would develop into a fire ignition. In the first week after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979-2011; R2 = 0.45). Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our spatiotemporal analysis provide new information about temporal and spatial dynamics of wildfires and have implications for modeling the terrestrial carbon cycle.

Sedano, F.; Randerson, J. T.

2014-07-01

458

Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition  

PubMed Central

The neutral, distorted octahedral complex [TiCl4(SenBu2)2] (1), prepared from the reaction of TiCl4 with the neutral SenBu2 in a 1:2 ratio and characterized by IR and multinuclear (1H, 13C{1H}, 77Se{1H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3?m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10–3 ?·cm with a carrier density of 1 × 1022 cm–3. Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 ?m diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ?20 ?m hole size, whereas their lengths/widths continue to increase. PMID:24489437

2013-01-01

459

Use of vapor pressure deficit to predict humidity and temperature effects on the mortality of mold mites, Tyrophagus putrescentiae.  

PubMed

The mold mite, Tyrophagus putrescentiae (Shrank), frequently infests a variety of stored food products in ideal, but rather limited conditions. Major factors limiting survival of this mite are the temperature and humidity imposed on T. putrescentiae as it develops within and disperses among sites. However, since relative humidity is dependent upon air temperature, determining survivability in a habitat can be difficult in the presence of structural temperature variations. Vapor pressure deficit (VPD) provides a method of combining both relative humidity and temperature into a single number that can be used to determine conditions detrimental to mite survival. This study utilized a bioassay format to measure mortality of T. putrescentiae when exposed to a range of seven temperatures (5-35 degrees C), 10 relative humidities (0-100% RH), 17 exposure times (0.5-240 h), with and without food. With these combinations of temperature and RH, mortality curves (mortality versus time) that displayed a sigmoidal relationship were used to calculate LT(50) and LT(90) estimates. These mortality estimates were then regressed on their associated VPD and the resulting regressions (LT(50) and LT(90)) were significant at P < 0.0001, and provided acceptable R(2) values >or=0.83, regardless of whether food was present or not. At room temperature, threshold of VPD for T. putrescentiae development was below 8.2 mbar, this estimate being initially calculated from published values. For mites exposed to drier conditions, above 8.2 mbar, survival time was curtailed dependant on the magnitude of VPD. As the VPD exceeded 12 mbar, mites experienced substantial (>90%) mortality within 58 (33, 101) h; and further increasing VPD decreased the time of exposure to achieve mortality. This study demonstrates that making subtle changes in humidity or temperature to reach a target VPD may provide control of mite outbreaks and reduce areas inhabitable for T. putrescentiae. PMID:18979171

Eaton, Marc; Kells, Stephen A

2009-03-01

460

Variability in Proline-Accumulating Ability of Barley (Hordeum vulgare L.) Cultivars Induced by Vapor Pressure Deficit 1  

PubMed Central

This work was undertaken in an effort to reconcile the conflicting proline-accumulating responses of the barley (Hordeum vulgare L.) cultivars, Excelsior and Proctor, reported by Singh et al. (1972) and Hanson et al. (1976). It deals with the effects of different vapor pressure deficits (VPD) during growth and subsequent drought stress on several barley cultivars. A higher VPD (1.2 kilopascals) during Clipper seedling growth resulted in higher solute-accumulating ability, seemingly independently of leaf water potential, than a lower VPD (0.12 kilopascals). The higher VPD during stress also resulted in higher solute contents, and this response may be more closely related to leaf water potential. When the responses of Excelsior and Proctor were examined in detail, it was found that the relative proline-accumulating ability of the two cultivars was dependent upon the VPD under which they were grown. At low VPD, Proctor accumulated significantly more proline than did Excelsior; whereas at higher VPD, Excelsior accumulated more proline than did Proctor. The crossover occurred at a VPD of about 0.72 kilopascals. This reversal of cultivar response was enhanced by multiplying seed under the two VPD extremes. Glycinebetaine accumulation did not demonstrate the crossover effect, although the concentration of this compound in all cultivars also depended on the VPD prevailing during growth and/or stress. Solute levels, in general, were more closely related to the decrease in relative water content than to a decrease in leaf water potential. It is concluded that the conflicting proline-accumulating responses of Excelsior and Proctor could be explained by these findings. PMID:16668700

Naidu, Bodapati P.; Aspinall, Donald; Paleg, Leslie G.

1992-01-01

461

An experimental study of the effect of boron on a water saturated haplogranite at 1 Kbar vapour pressure  

NASA Astrophysics Data System (ADS)

An experimental study of the effect of boron in the water saturated Q-Or-Ab-B2O3-H2O system has been performed at P=1 Kbar to provide experimental data and explain the role of boron in some late magmatic and early hydrothermal events. Experiments were conducted between 500° C and 800° starting from a gel, or a previously crystallized gel, and variable amounts of boron (0 to 18% B2O3) added to water. The phases obtained were: quartz, sanidine, albite, silicate liquid quenched to glass, and aqueous vapour phase. Boric acids, borates and isotropic low index materials were found in the quenched vapour phase. An aluminium silicate-like mineral, not yet fully identified, is also present. The solidus temperature of the Q-Or-Ab composition is lowered by 60° C when 5 wt. % B2O3 is added and by more than 130° C when 17wt. % B2O3 is added. Compositions of equilibrated silicate melts and vapours were obtained between 780° C and 750° C for various B2O3 concentrations. The vapour phase is B and Si rich. It is also enriched in Na with respect to K, and in alkalis with respect to Al. Its silicate solute content is higher than in experiments with pure water. The solubility of water is increased by the addition of boron in Q-Or-Ab melts. Microprobe data show that the melts equilibrated with vapour phases become hyperaluminous and more potassic than sodic. The partition coefficient of boron is in favour of the vapour ( k D=B2O3% in melt/B2O3% in vapour=0.33±0.02). The effect of the interaction between the silicate phases and the vapour is discussed. Comparison is made between the behaviour of boron and that of chlorine and fluorine. Geological applications are also provided, which concern the influence of boron on minimum melting, on muscovite stability and on the hypersolvus-subsolvus transition.

Pichavant, Michel

1981-07-01

462

Investigation of vapor film motion regularities at boiling liquids  

NASA Astrophysics Data System (ADS)

The experimental investigation of the saturated Freon-113 and distilled water film boiling on spheres with different diameters at atmospheric pressure under conditions of free convection is executed. With high-speed video average thickness and cumulative distribution function of vapor film as a function of the angle was measured. It was found that with increasing the angle the average thickness of vapor film can change by different laws depending on diameter of the sphere and the temperature difference. It was found also that the increase in the average vapor film thickness with increasing angle is more connected with the increase of large components of cumulative distribution function. It also noted the presence of quasi-periodic pulsations of the vapor film thickness in the lower part, which eventually largely determine the behavior of the interface at large angles.

Agaltsov, A.; Zeigarnik, Y. U.

2013-04-01

463

Tested Demonstrations. Gasoline Vapor: An Invisible Pollutant  

ERIC Educational Resources Information Center

Describes a demonstration concerning the air pollution aspects of gasoline vapor which provides an estimation of the vapor pressure of test fuel, the molecular weight of the vapor, and illustrates a method of controlling the pollution. (SL)

Stephens, Edgar R.

1977-01-01

464

49 CFR 179.15 - Pressure relief devices.  

...padding pressure and the lading vapor pressure at the following reference temperatures...burst pressure. (3) The vapor tight pressure of a reclosing pressure relief...transportation. (3) The vapor tight pressure and the...

2014-10-01

465

Saturated Fat  

MedlinePLUS

... Ice cream and ice cream products Palm and coconut oils It's important to note that lower-fat ... are another source of saturated fats: palm oils, coconut oils, and cocoa butter. You may think you ...

466

MESOSCOPIC SCALE MODELING FOR CHEMICAL VAPOR DEPOSITION  

E-print Network

. GOBBERT \\Lambda AND CHRISTIAN RINGHOFER y Abstract. Low pressure chemical vapor deposition is a process is typically run at very low pressure. A typical value for the total pressure in low pressure chemical vaporMESOSCOPIC SCALE MODELING FOR CHEMICAL VAPOR DEPOSITION IN SEMICONDUCTOR MANUFACTURING MATTHIAS K

Ringhofer, Christian

467

Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPa and temperatures to partial melting  

SciTech Connect

Instantaneous-failure strengths and ductilities of water-saturated cylindrical specimens of Charcoal Granodiorite, Mount Hood Andesite, and Cuerbio Basalt are determined at a strain rate of 10{sup -4}s{sup -1} and at effective confining pressures (Pe) of 0 and 50 MPa and at temperatures to partial melting. The data indicate: (1) at Pe = 0 and 50 MPa (Pc and Pp of 50 MPa and of 100 and 50 MPa, respectively) the granodiorite does not water-weaken; (2) at these same Pe the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (3) at Pe = 0 and 870-900{sup 0}C the andesite's wet strength averages 20 MPa compared to 100 MPa, dry; (4) at Pe = 50 MPa and 920{sup 0}C its wet strength is 45 MPa compared to 160 MPa dry; (5) at Pe = 0, the basalt appears to be water-weakened above 800{sup 0}C; (6) water-saturated specimens deformed at temperatures less than T{sub m} exhibit ultimate strengths at less than 2 percent shortening and then work-soften along faults; and (7) both dry and wet specimens deform primarily by brittle fracture. Extrapolations indicate: (1) crystalline rocks should be drillable because they remain brittle until partial melting occurs, and penetration rates should increase with temperature because there is a corresponding decrease in brittle fracture strength; (2) boreholes in ''water-filled'' holes will be stable to >10 km at temperatures 10 km; and (4) open boreholes in the andesite are apt to be much less stable, and at similar temperatures would fail at 2 to 5-km depth.

Bauer, S.J.; Friedman, M.; Handin, J.

1981-01-01

468

Subatmospheric Vapor Pressures for Fluoromethane (R41), 1,1-Difluoroethane (R152a), and 1,1,1-Trifluoroethane (R143a) Evaluated from Internal-Energy Measurements  

Microsoft Academic Search

Vapor pressures were evaluated from measured internal-energy changes ?U(2) in the vapor+liquid two-phase region. The method employed a thermodynamic relationship between the derivative quantity (?U(2)\\/?V)T, the vapor pressure ps, and its temperature derivative (?p\\/?T)s. This method was applied at temperatures between the triple point and the normal boiling point of t