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1

Improved Magnus` form approximation of saturation vapor pressure  

SciTech Connect

Relative humidity is usually measured in aerological observations and dew point depression is usually reported in upper-air reports. These variables must frequently be converted to other moisture variables in meteorological analysis. If relative humidity is converted to vapor pressure, most humidity variables can then be determined. Elliott and Gaffen reviewed the practices and procedures of the US radiosonde system. In their paper, a comparison of the relative errors was made between the saturation vapor pressure formulations of Tetens (1930), Goff-Gratch (1946), Wexler (1976), and Buck (1981). In this paper, the authors will expand the analysis of Elliott and Gaffen by deriving several new saturation vapor pressure formulas, and reviewing the various errors in these formulations. They will show that two of the new formulations of vapor pressure over water and ice are superior to existing formulas. Upper air temperature data are found to vary from about +50 C to {minus}80 C. This large variation requires a saturation vapor pressure equation to be accurate over a large temperature range. While the errors introduced by the use of relatively inaccurate conversion equations are smaller than the errors due to the instruments, dewpoint coding errors, and dewpoint conversion algorithms (Elliott and Gaffen, 1993); they introduce additional systematic errors in humidity data. The most precise formulation of vapor pressure over a plane surface of water was given by Wexler (1976). The relative errors of Tetens` (1930) formula and one due to Buck (1981) (Buck`s equation is recommended in the Federal Meteorological Handbook No. 3, 1991) are shown. The relative errors in this table are the predicted value minus the Wexler value divided by the Wexler value.

Alduchov, O.A.; Eskridge, R.E. [National Oceanic and Atmospheric Administration, Asheville, NC (United States). National Climatic Data Center

1997-11-01

2

Saturation vapor pressures and vaporization enthalpies of esters of ethylene glycol and lower carboxylic acids  

NASA Astrophysics Data System (ADS)

Saturation vapor pressures and vaporization enthalpies of ethylene glycol and C1-C5 carboxylic acid disubstituted esters of normal and branched structures are determined by the transfer method in the temperature range of 295 to 327 K. Dependences of vaporization enthalpies versus the number of carbon atoms in a molecule and the retention indices are determined. An analysis of existing calculation schemes is given to help predict the vaporization enthalpy of the compounds under study.

Maslakova, A. S.; Krasnykh, E. L.; Levanova, S. V.

2011-10-01

3

Indoor/outdoor connections exemplified by processes that depend on an organic compound's saturation vapor pressure  

NASA Astrophysics Data System (ADS)

Outdoor and indoor environments are profitably viewed as parts of a whole connected through various physical and chemical interactions. This paper examines four phenomena that share a dependence on vapor pressure—the extent to which an organic compound in the gas phase sorbs on airborne particles, sorbs on surfaces, sorbs on particles collected on a filter or activates trigeminal nerve receptors. It also defines a new equilibrium coefficient for the partitioning of organic compounds between an airstream and particles collected by a filter in that airstream. Gas/particle partitioning has been studied extensively outdoors, but sparingly indoors. Gas/surface partitioning occurs primarily indoors while gas/filter partitioning occurs at the interface between outdoors and indoors. Activation of trigeminal nerve receptors occurs at the human interface. The logarithm of an organic compound's saturation vapor pressure correlates in a linear fashion with the logarithms of equilibrium coefficients characteristic of each of these four phenomena. Since, to a rough approximation, the log of an organic compound's vapor pressure scales with its molecular weight, molecular weight can be used to make first estimates of the above processes. For typical indoor conditions, only larger compounds with lower-saturation vapor pressures (e.g., tetracosane, pentacosane, or di-2-ethylhexyl phthalate) have airborne particle concentrations comparable to or larger than gas phase concentrations. Regardless of a compound's vapor pressure, the total mass sorbed on indoor airborne particles is quite small compared to the total sorbed on indoor surfaces, reflecting the large difference in surface areas between particles within a room and surfaces within a room. If the actual surface areas are considered, accounting for roughness and porosity, the surface concentration of organics sorbed on typical airborne particles appears to be comparable to the surface concentration of organics sorbed on indoor carpets, walls and other materials (based on data from several studies in the literature). Mirroring the importance of phase distributions outdoors, an organic compound's indoor lifetime, fate and even health impacts depend on its distribution between phases and among surfaces.

Weschler, Charles J.

4

Absorption cross sections, saturated vapor pressures, sublimation energies, and evaporation energies of some organic laser dye vapors  

SciTech Connect

A new technique of transmission measurement of overheated dye vapors is applied to determine absolute absorption cross-section spectra of three active dyes for vapor phase dye lasers. The investigated compounds are 1,4-di(2-(5-phenyloxazolyl))-benzene (POPOP), 1,4-di(2-(4-methyl-5-phenyl-oxazolyl))-benzene (dimethyl-POPOP), and 2,5-diphenylfuran (PPF). The vapor absorption spectra are compared with liquid solution spectra in order to obtain information on the dye--solvent interaction. The saturated vapor densities are determined by transmission measurements after knowing the absolute absorption cross-section spectra. The latent heats of sublimation, evaporation, and melting are derived by analyzing the dependences of the saturated vapor densities on the vapor temperature.

Schmidt, J.; Penzkofer, A.

1989-08-01

5

Determination of saturation pressure and enthalpy of vaporization of semi-volatile aerosols: the integrated volume mentod  

EPA Science Inventory

This study presents the integrated volume method for estimating saturation pressure and enthalpy of vaporization of a whole aerosol distribution. We measure the change of total volume of an aerosol distribution between a reference state and several heated states, with the heating...

6

Low-Temperature and Rapid Oxidation of GaN Surface by Saturated Water Vapor at High Pressure  

NASA Astrophysics Data System (ADS)

A gallium oxide layer was successfully formed on a GaN surface by saturated water vapor oxidation at a high pressure (350 °C, 16.5 MPa). Ga oxide thickness can be controlled in the 5-1,000 nm range by such oxidation process for 15 min. Saturated water vapor oxidation is a rapid and very low temperature oxidation process compared with the conventional thermal oxidation of GaN. This rapid oxidation potential at a low temperature is attributed to the high density of the oxidizer (H2O) under high-pressure condition. By applying post-treatment with high-pressure hot water, residual nitrogen in the oxide layer is removed and the stoichiometric composition of Ga2O3 is observed by X-ray photoelectron spectroscopy (XPS). The removal of nitrogen from the oxide by the high-pressure hot water is caused by its high solubility of inorganic compounds. Rapid and low-temperature oxidation can be applicable to the fabrication of a high-performance device without thermal stress for GaN-field effect transistors (FETs).

Futatsuki, Takashi; Oe, Taro; Aoki, Hidemitsu; Komatsu, Naoyoshi; Kimura, Chiharu; Sugino, Takashi

2009-04-01

7

Electrical conductivity measurements of aqueous boric acid at 25--350{degree}C at saturation vapor pressure. Final report  

SciTech Connect

Electrical conductance measurements of aqueous boric acid solutions (15-110 g/kg-H{sub 2}O {equivalent_to} 0.251--1.815 mol/kg-H{sub 2}O) were measured over the temperature range 25 to 75 C at saturation vapor pressures in glass cells with parallel platinum electrodes. Sixteen series of measurements were made involving three samples of boric acid from different sources. Conductance measurements were also made at 15.5 and 30.5 g/kg-H{sub 2}O over the temperature range 100 to 350 C at 50 C intervals with a metallic cell fitted with concentric platinum electrodes. The specific conductances of H{sub 3}BO{sub 3} (aq)were calculated after correction for the conductance of the solvent (water) and are tabulated in this report. At the specific conditions requested in the project description, namely a concentration of 110 g/kg-H{sub 2}O and 65 C, the specific conductance of boric acid is 293.2 {+-} 1.8 microSiemens/cm based on duplicate measurements of four independent solutions. The results from these tests will be utilized by the Tokamak Physics Experimental Project (TPX).

Ho, P.C.; Palmer, D.A.

1995-09-01

8

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

9

Vapor Pressure Data  

NSDL National Science Digital Library

Created by Professor Shuzo Ohe of the Graduate School of Chemical Engineering and the Science University or Tokyo, this site offers vapor pressure data. Available in graph form, data represent vapor pressure (mmHg) as a function of temperature (C, or F). Substances are listed alphabetically and include acetaldehyde, acetic acid, benzene, butane, carbon dioxide, and water, to name a few.

Ohe, Shuzo.

10

Configuration and testing of a saturated vapor helium compressor  

Microsoft Academic Search

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

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

1986-01-01

11

Condensation of saturated vapor on melting surfaces  

Microsoft Academic Search

Melting of vertical and horizontal surfaces as a result of condensation of saturated vapor was studied. For the vertical wall, employing similarity transformation, full boundary layer equations governing laminar films of melt and condensate were obtained. Depending on the magnitude of the Prandtl number, different scaling parameters are needed such that Pr appears in the momentum or energy equation. Numerical

Taghavi-Tafreshi

1982-01-01

12

Vapor diffusion in partially saturated packed beds  

SciTech Connect

The objective of this experimental and numerical study is to quantify the vapor diffusion enhancement factor resulting from pore-level evaporation/condensation in porous media subjected to a temperature gradient. In an earlier paper the enhancement factor {beta}, extracted from nonisothermal diffusion experiments, was shown to increase to approximately 1.0, which is equivalent to the free space diffusion coefficient, as average saturation in the packed bed increases from 0 to 0.2. The results of a drying experiment involving an initially partially saturated bed are presented in this paper. Numerical simulations of the nonisothermal diffusion and drying experiments using the TOUGH2 code were performed. The predicted vapor fluxes in both transient and quasi-steady simulations for the nonisothermal diffusion experiment are in good agreement with the experimental results when the experimentally determined enhancement factor is incorporated into the code. Simulated saturation profiles for drying are in qualitative agreement with experimental results. In both simulations the discrepancy between the predicted and observed saturation distributions may be the result of capillary hysteresis which is not included in the TOUGH2 code. Comparison between the experiments and simulations supports the existence of the enhanced vapor diffusion mechanism and indicates that the enhancement factor ranges from 0.3 to 1.0 depending on the moisture content.

Gu, L.; Ho, C.K.; Plumb, O.A.; Webb, S.W.

1999-07-01

13

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

14

Measurements on the flow of vapors near saturation through porous Vycor glass membranes  

NASA Astrophysics Data System (ADS)

We present experimental data of the flow of butane and isobutane vapors through porous Vycor glass membranes. The pressure driven flow of vapors near and far from saturation through membranes with pore diameters of 20 and 33 nm is investigated. The upstream pressures lie between the saturation pressure at the upstream temperature to approximately half that value. The pressure differences are between a few kPa to about 100 kPa. From an adiabatic description of the flow process, we expect condensation of a vapor close enough to saturation and hence, due to the action of capillary forces, an increase in mass flux with respect to the mass flux of a vapor that remains in a gaseous state. According to the adiabatic description, a vapor that flows through a porous membrane may condense for two reason: One reason is capillary condensation in the pores of the membrane, the second reason is heat conduction from the upstream to the downstream side of the membrane due to the Joule-Thomson effect. If the flux of heat in downstream direction is large enough, a vapor near saturation at the upstream side of the membrane may only release sufficient heat by condensation. Describing the flow in terms of dimensionless groups recovered from an adiabatic description of the flow process, we find that a vapor condenses and the mass flux is increased if (i) a dimensionless permeability of the membrane is larger than one and (ii) if the vapor at the upstream side is close enough to saturation such that a dimensionless group involving the upstream pressure and the pressure difference is also larger than one. Experimental data corroborates condition (i) above and indicates that condition (ii) might be valid.

Loimer, Thomas; Reznickova, Jirina; Uchytil, Petr; Setnickova, Katerina

2012-05-01

15

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.

16

Vapor pressure, heat capacity, and density along the saturation line, measurements for cyclohexanol, 2-cyclohexen-1-one, 1,2-dichloropropane, 1,4-di-tert-butylbenzene, ({+-})-2-ethylhexanoic acid, 2-(methylamino)ethanol, perfluoro-n-heptane, and sulfolane  

Microsoft Academic Search

Vapor pressures were measured to a pressure limit of 270 kPa or lower decomposition point for eight compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperatures (ambient to a maximum of 548 K). A differential scanning calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat

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

1997-01-01

17

CC Cryostat Vapor Pressure Thermometers  

SciTech Connect

Vapor pressure thermometers will be used to measure the temperature or the liquid argon in the cryostat at two different levels. One bulb will be positioned near the top of the vessel, and a second bulb will be located near the bottom of the vessel. The volume of the bulbs is dependent upon the charge temperature and pressure chosen, the temperature range of the thermometer desired, the size and length of tubing used, and the warm volume involved.

Kurita, C.H.; /Fermilab

1987-10-01

18

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

19

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus  

ERIC Educational Resources Information Center

A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

2007-01-01

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 Saturation and Magma Degassing: Integrating Petrologic and Remote Sensing Perspectives on Volcanic Volatile Budgets  

NASA Astrophysics Data System (ADS)

Over the past 25 years there has been a growing body of evidence based on petrologic, remote sensing, and volcanic gas data that andesitic, dacitic, and rhyolitic magmas in crustal reservoirs are saturated with a multicomponent C-O-H-S vapor phase before eruption. A key piece of evidence for magmatic vapor saturation is the excess S problem: the common observation that much more S is released by explosive eruptions than was originally dissolved in the erupted volume of silicate melt. If all of the excess S is derived from a magmatic vapor phase, then intermediate to silicic magmas must commonly contain several wt% exsolved vapor prior to eruption. The large amounts of volatiles implied by these estimates suggest that exsolved vapor accumulates in the apical regions of magma bodies during repose periods between eruptions. A major uncertainty in understanding volcanic SO2 emissions has been lack of information on S partitioning between silicate melt and coexisting hydrous vapor. Recently published experimental data on melt-vapor partitioning (Scaillet et al., 1998; Keppler, 1999) have shown that S partitions strongly into the vapor phase under conditions relevant for most dacitic and rhyolitic magmas. Thermodynamic modeling (Wallace, 2000) based on these results can be used to calculate the mole fractions of both SO2 and H2S in a magmatic vapor phase if temperature, pressure, oxygen fugacity, and dissolved H2O and S contents of the silicate melt are known. Using published data for well studied eruptions, the pre-eruptive magmatic vapor phase for dacitic to rhyolitic magmas typically contains 0.5 to 6 mol% total S. Andesitic, dacitic, and rhyolitic magmas in crustal reservoirs are probably vapor saturated due to recharge and underplating by vapor-saturated basaltic magma. CO2 is particularly important because it is abundant in mantle derived basalts but has low solubility in silicate melts at crustal pressures. Understanding budgets of the major volatiles requires integrating remote sensing and volcanic gas data on fluxes of CO2, SO2, and H2S from volcanoes with petrologic data on temperature, pressure, oxygen fugacity, and dissolved volatiles in both differentiated magma stored in crustal reservoirs and mafic magma recharging these systems. The importance of the latter is exemplified by mafic cinder cones surrounding Popocatepetl volcano in central Mexico. Olivine-hosted melt inclusions from these cones contain 1000-6000 ppm S (Cervantes and Wallace, 2000), indicating that mafic magma recharging into the Popo system provides an abundant source of S that may explain the very large SO2 emissions from the current eruption.

Wallace, P.

2002-05-01

22

Saturated Vapour Pressure and Refrigeration - Part I  

ERIC Educational Resources Information Center

The first part of a two-part article describes an experimental approach that can be used in teaching the concept of saturated vapour pressure. This leads to a discussion of refrigeration cycles in the second part of the article. (JR)

Bunker, C. A.

1973-01-01

23

Vapor pressure, heat capacity, and density along the saturation line, measurements for cyclohexanol, 2-cyclohexen-1-one, 1,2-dichloropropane, 1,4-di-tert-butylbenzene, ({+-})-2-ethylhexanoic acid, 2-(methylamino)ethanol, perfluoro-n-heptane, and sulfolane  

SciTech Connect

Vapor pressures were measured to a pressure limit of 270 kPa or lower decomposition point for eight compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperatures (ambient to a maximum of 548 K). A differential scanning calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point. Where possible, the critical temperature and critical density for each compound were determined experimentally. The results of the measurements were combined to derive a series of thermophysical properties including critical temperature, critical density, critical pressure, acentric factor, enthalpies of vaporization [within the temperature range ({+-}50 K) of the vapor pressures], enthalpies of fusion if solid at ambient temperature, solubility parameter, and heat capacities along the saturation line. Wagner-type vapor-pressure equations were derived for each compound. In addition, the liquid-phase densities were compared with values derived using a four-term power series in either T or [(1 {minus} T{sub r}){sup 1/3}]. All measured and derived values were compared with those obtained in a search of the literature. Recommended critical parameters are listed for each of the compounds studied. A Rule-Of-Thumb derived in the 1992 Project Year was used to estimate thermal decomposition temperatures by radical scission from a knowledge of the bond dissociation energy or vice versa.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A. [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)] [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1997-11-01

24

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

E-print Network

: Experimental vapor pressures, vaporization, fusion and sublimation enthalpies of a number of dialkyl. The compounds, the vaporization, fusion, and sublimation enthalpies and liquid and solid vapor pressures enthalpies of several liquid dialkyl benzenedicarboxylates and the fusion, sublimation, and vaporization

Chickos, James S.

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

Acoustics and precondensation phenomena in gas-vapor saturated mixtures  

NASA Astrophysics Data System (ADS)

Starting from fundamental hydrodynamics and thermodynamics equations for thermoviscous fluids, a new modeling procedure, which is suitable to describe acoustic propagation in gas mixtures, is presented. The model revises the boundary conditions which are appropriate to describe the condensation-evaporation processes taking place on a solid wall when one component of the mixture approaches saturation conditions. The general analytical solutions of these basic equations now give a unified description of acoustic propagation in an infinite, semi-infinite, or finite medium, throughout and beyond the boundary layers. The solutions account for the coupling between acoustic propagation and heat and concentration diffusion processes, including precondensation on the walls. The validity of the model and its predictive capability have been tested by a comparison with the description available in the literature of two particular systems (precondensation of propane and acoustic attenuation in a duct filled with an air-water vapor saturated mixture). The results of this comparison are discussed to clarify the relevance of the various physical phenomena that are involved in these processes. The model proposed here might be useful to develop methods for the acoustic determination of the thermodynamic and transport properties of gas mixtures as well as for practical applications involving gas and gas-vapor mixtures like thermoacoustics and acoustics in wet granular or porous media.

Guianvarc'h, C.; Bruneau, M.; Gavioso, R. M.

2014-02-01

27

Multicomponent fuel vaporization at high pressures.  

SciTech Connect

We extend our multicomponent fuel model to high pressures using a Peng-Robinson equation of state, and implement the model into KIVA-3V. Phase equilibrium is achieved by equating liquid and vapor fugacities. The latent heat of vaporization and fuel enthalpies are also corrected for at high pressures. Numerical simulations of multicomponent evaporation are performed for single droplets for a diesel fuel surrogate at different pressures.

Torres, D. J. (David J.); O'Rourke, P. J. (Peter J.)

2002-01-01

28

The vapor pressure of iron pentacarbonyl  

NASA Technical Reports Server (NTRS)

Vapor pressure measurements have been made on pure iron pentacarbonyl between +31 and -19 C. The experimental results may be expressed by the logarithm of pressure (mm Hg) to the base 10 equals -(2096.7 K/T) + 8.4959, which corresponds to a heat of vaporization for the liquid carbonyl of delta H ? (9.588 plus or minus 0.12) kcal/mole. This result confirms and extends the earlier measurements made by Trautz and Badstuebner between 0 and 140 C. The need for careful purification of commercially available iron pentacarbonyl is emphasized, particularly for establishing the correct vapor pressure below 45 C.

Gilbert, A. G.; Sulzmann, K. G. P.

1974-01-01

29

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

30

MISTING OF LOW VAPOR PRESSURE HALOCARBONS  

EPA Science Inventory

The paper gives results of a laboratory-scale study of the use of misting systems to provide total-flood fire protection with lower vapor pressure halocarbons. (NOTE: Several candidate Halon 1301 replacements with a low ozone-depletion potential have higher boiling points (usuall...

31

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, April 1--June 30, 1995  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. Both the gas saturation method and the Knudsen effusion method are being used. Results are presented for anthracene, naphthacene, pentacene, and a mixture of anthracene and perylene obtained using the effusion method.

Suuberg, E.M.

1995-10-01

32

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

33

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

34

A practical vapor pressure equation for helium-3 from 0.01 K to the critical point  

Microsoft Academic Search

A saturation vapor pressure equation, p(T), is an essential component in the 3He state equation currently under development. The state equation is valid over the range 0.01–20K with pressures from 0 to the melting pressure or 15MPa. The vapor pressure equation consequently must be valid from 0.01K to the critical temperature. This paper surveys available 3He critical temperature and pressure

Y. H. Huang; G. B. Chen

2006-01-01

35

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

36

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

PubMed

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. PMID:24992709

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

2014-08-01

37

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

38

Effects of heterogeneities on capillary pressure saturation relative permeability relationships  

NASA Astrophysics Data System (ADS)

In theories of multiphase flow through porous media, capillary pressure-saturation and relative permeability-saturation curves are assumed to be intrinsic properties of the medium. Moreover, relative permeability is assumed to be a scalar property. However, numerous theoretical and experimental works have shown that these basic assumptions may not be valid. For example, relative permeability is known to be affected by the flow velocity (or pressure gradient) at which the measurements are carried out. In this article, it is suggested that the nonuniqueness of capillary pressure-relative permeability-saturation relationships is due to the presence of microheterogeneities within a laboratory sample. In order to investigate this hypothesis, a large number of "numerical experiments" are carried out. A numerical multiphase flow model is used to simulate the procedures that are commonly used in the laboratory for the measurement of capillary pressure and relative permeability curves. The dimensions of the simulation domain are similar to those of a typical laboratory sample (a few centimeters in each direction). Various combinations of boundary conditions and soil heterogeneity are simulated and average capillary pressure, saturation, and relative permeability for the "soil sample" are obtained. It is found that the irreducible water saturation is a function of the capillary number; the smaller the capillary number, the larger the irreducible water saturation. Both drainage and imbibition capillary pressure curves are found to be strongly affected by heterogeneities and boundary conditions. Relative permeability is also found to be affected by the boundary conditions; this is especially true about the nonaqueous phase permeability. Our results reveal that there is much need for laboratory experiments aimed at investigating the interplay of boundary conditions and microheterogeneities and their effect on capillary pressure and relative permeability.

Ataie-Ashtiani, Behzad; Majid Hassanizadeh, S.; Celia, Michael A.

2002-06-01

39

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.

40

The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some ammonium salts  

Microsoft Academic Search

Vapour pressures of water over saturated solutions of ammonium bromide, ammonium dihydrogen phosphate, ammonium thiosulfate, ammonium persulfate, ammonium acetate, ammonium oxalate and ammonium tartrate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. Molar enthalpies of solution of ammonium bromide ?solHm(NH4Br, T=293.97K, m=0.1030mol·kg?1)=(17.4±0.5)kJ·mol?1; ammonium hydrogen

Alexander Apelblat; Eli Korin

2003-01-01

41

Vapor saturation of sodium: Key to unlocking the origin of Alexei V. Fedkin  

E-print Network

for too short a time to destroy all pre-existing nuclei (Hewins and Radomsky, 1990). Barred chondrules online 26 February 2013 Abstract Sodium saturation of the vapor coexisting with chondrules- ular gas, a much more reducing plume. If the conditions were such that sodium were retained

Grossman, Lawrence

42

Saturation of atomic transitions using subwavelength diameter tapered optical fibers in rubidium vapor  

NASA Astrophysics Data System (ADS)

We experimentally investigate ultralow-power saturation of the rubidium D2 transitions using a tapered optical fiber (TOF) suspended in a warm Rb vapor. A direct comparison of power-dependent absorption measurements for the TOF system with those obtained in a standard free-space vapor cell system highlights the differences in saturation behavior for the two systems. The effects of hyperfine pumping in the TOF system are found to be minimized due to the short atomic transit times through the highly confined evanescent optical mode guided by the TOF. The TOF system data is well-fit by a relatively simple empirical absorption model that indicates nanoWatt-level saturation powers.

Jones, D. E.; Franson, J. D.; Pittman, T. B.

2014-08-01

43

Numerical Analysis of Pressure Propagation and Energy Conversion Ratio in Sodium Vapor Explosions  

SciTech Connect

A computer code PROVER-II is developed for the propagation phase of a sodium vapor explosion. A new thermal fragmentation model is proposed that includes three kinds of timescales for modeling the instant fragmentation, spontaneous nucleation fragmentation, and normal boiling fragmentation. The pressure wave propagation in a sodium vapor explosion is analyzed and compared with that in a steam explosion. The energy conversion ratio of an in-vessel sodium vapor explosion is calculated by using hydrodynamic and thermal fragmentation mechanisms, and sensitivity analyses are carried out for some parameters. The initial thermal conditions for energetic fuel-coolant interactions in a sodium system are examined. Results show that the high saturation temperature of sodium results in a much lower pressure peak in a sodium vapor explosion compared to a steam explosion, and the mechanical energy release is limited by the mass of melt participating in the explosion during the core disruptive accident in liquid-metal-cooled fast breeder reactors.

Liu Jie; Koshizuka, Seiichi; Oka, Yoshiaki [University of Tokyo (Japan)

2003-12-15

44

Coal reservoir saturation: Impact of temperature and pressure  

SciTech Connect

Methane adsorption isotherms measured for a series of coals with varying rank at a wide range of temperatures and pressures allows the prediction of the change in sorption capacity as a function of tectonic history. Changes in sorption capacity in response to declining pressure and temperature associated with uplift may increase or decrease the capacity of the coal and, if the coal is initially saturated, result in excess gas or a deficiency of gas (undersaturation). Assuming reasonable geothermal and pressure gradients, our data indicate that the sorption capacity will generally decrease with uplift and associated exhumation, suggesting that an initially gas-saturated coal will desorb gas during uplift of the reservoir. The desorbed gas would be available for migration and/or, potentially, resaturation of an undersaturated coal. Our results argue against the generally accepted theory that undersaturation of coal reservoirs results from an increase in the sorption capacity with uplift except for coals at such high pressures that the isotherms are essentially flat or for very high pressure and geothermal gradients.

Bustin, A.M.M.; Bustin, R.M. [University of British Columbia, Vancouver, BC (Canada). Dept. of Earth & Ocean Science

2008-01-15

45

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

46

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 October--31 December 1994  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, and (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to testing the equipment for measurements by the gas saturation method and the Knudsen effusion method. These techniques are beginning to yield reliable results. Some key features of the methods are summarized, and sample results presented.

Suuberg, E.M.

1995-04-01

47

LOX vaporization in high-pressure, hydrogen-rich gas  

NASA Technical Reports Server (NTRS)

LOX droplet vaporization in high-pressure hydrogen-rich gas is analyzed, with special attention to thermodynamic effects which compel the surface to heat to the critical state and to supercritical vaporization processes on heating to criticality. Subcritical vaporization is modeled using a quasi-steady diffusion-controlled gas-phase transport formulation coupled to an effective-conductivity internal-energy-transport model accounting for circulation effects. It is demonstrated how the droplet surface might heat to the critical state, for ambient pressures slightly greater than the critical pressure of oxygen, such that the bulk of propellant within the droplet remains substantially below the critical mixing temperature.

Litchford, Ron J.; Jeng, San-Mou

1990-01-01

48

The vapour pressures over saturated aqueous solutions of dl-2-aminobutyric acid, 4-aminobutyric acid, sodium- d-gluconate, sodium hippurate, and potassium magnesium- l-aspartate  

Microsoft Academic Search

Vapour pressures of water over saturated solutions of dl-2-aminobutyric acid, 4-aminobutyric acid, sodium-d-gluconate, sodium hippurate, and potassium magnesium-l-aspartate were determined over the (278 to 322)K temperature range. The determined vapour pressures were used to obtain the water activities, the molar enthalpies of vaporization, and the osmotic coefficients of sodium-d-gluconate.

Alexander Apelblat; Eli Korin

2008-01-01

49

A Simple Experiment for Determining Vapor Pressure and Enthalpy of Vaporization of Water.  

ERIC Educational Resources Information Center

Laboratory procedures, calculations, and sample results are described for a freshman chemistry experiment in which the Clausius-Clapeyron equation is introduced as a means of describing the variation of vapor pressure with temperature and for determining enthalpy of vaporization. (Author/SK)

Levinson, Gerald S.

1982-01-01

50

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

E-print Network

Vapor Pressures and Vaporization, Sublimation, and Fusion Enthalpies of Some Fatty Acids Joe A. Wilson and James S. Chickos* Department of Chemistry and Biochemistry, University of MissouriSt. Louis, St. Louis, Missouri 63121, United States *S Supporting Information ABSTRACT: Sublimation enthalpies

Chickos, James S.

51

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

52

Effects of saturation medium and pressure on strength parameters of Latrobe Valley brown coal: Carbon dioxide, water and nitrogen saturations  

Microsoft Academic Search

Adsorption of carbon dioxide (CO2) into coal matrix causes significant change in its chemical and physical structure, resulting in negligible permeability values and overall strength reduction. The main objective of this study is to investigate the effects of water, nitrogen (N2) and CO2 saturations at different saturation pressures on the strength of brown coal using uniaxial experiments. A series of

M. S. A. Perera; P. G. Ranjith; M. Peter

53

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

54

Study of capillary pressure-saturation relationships using a dynamic pore-scale network model  

Microsoft Academic Search

Current theories of multiphase flow rely on capillary pressure and saturation relationships that are commonly measured under static conditions. Recently, new multiphase flow theories have been proposed that include a new capillary pressure-saturation relationship that is valid under dynamic conditions. In this relationship, the difference between the two fluid pressures is called dynamic capillary pressure, and is assumed to be

T. Gielen; H. Nordhaug; H. Dahle; M. Celia; S. Hassanizadeh

2001-01-01

55

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

56

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

57

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

58

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

59

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

60

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

61

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

62

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

63

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

64

Pressure swing adsorption cycles for improved solvent vapor enrichment  

SciTech Connect

A pressure swing adsorption (PSA)-solvent vapor recovery (SVR) process simulator was used to investigate new PSA cycle configurations designed for higher solvent vapor enrichment. These cycles were modifications of the four-step Skarstrom cycle used commercially for PSA-SVR and include the addition of a cocurrent blowdown step, and combinations of cocurrent blowdown and continuous/batch reflux steps. The recovery of gasoline vapor from tank filling operations was simulated with n-butane, n-heptane, and nitrogen as representatives of the light and heavy components in gasoline vapor, and carrier gas, respectively. Adding a cocurrent blowdown step increased the solvent vapor enrichment, depending mainly on the step ending pressure, not the step time. Both the continuous and batch reflux steps also increased the solvent vapor enrichment, but at the expense of an increased bed capacity factor. For similar increases in the solvent vapor enrichment, batch reflux led to significantly smaller bed capacity factors compared to continuous reflux and was thus superior for PSA-SVR. Overall PSA-SVR process performance improved markedly by adding cocurrent blowdown and batch reflux steps compared to the conventional four-step cycle.

Liu, Y.; Ritter, J.A.; Kaul, B.K.

2000-03-01

65

Water-vapor pressure control in a volume  

NASA Technical Reports Server (NTRS)

The variation with time of the partial pressure of water in a volume that has openings to the outside environment and includes vapor sources was evaluated as a function of the purging flow and its vapor content. Experimental tests to estimate the diffusion of ambient humidity through openings and to validate calculated results were included. The purging flows required to produce and maintain a certain humidity in shipping containers, storage rooms, and clean rooms can be estimated with the relationship developed here. These purging flows are necessary to prevent the contamination, degradation, and other effects of water vapor on the systems inside these volumes.

Scialdone, J. J.

1978-01-01

66

Droplet Vaporization in a High-Pressure Gas  

NASA Technical Reports Server (NTRS)

Results of an experimental study of the vaporization of single R-113 and n-heptane droplets are presented. Gas temperature is found to have a strong effect on drop vaporization, while gas pressure has a weaker effect. A comparison of data from experiments in near-zero gravity with those conducted in normal gravity shows that the vaporization rate and droplet lifetime are affected depending on the liquid involved. In the case of R-113, the removal of the gravity field in free-fall experiments resulted in an increase of droplet lifetime of about 30 percent, whereas in the case of n-heptane, a much less pronounced effect was observed.

Hartfield, J. P.; Farrell, P. V.

1993-01-01

67

Subcooled and saturated water flow boiling pressure drop in small diameter helical coils at low pressure  

SciTech Connect

Experimental pressure drop results on boiling water flow through three helical coils of tube inner diameter of 4.03 mm and 4.98 mm and coil diameter to tube diameter ratio of 26.1, 64.1 and 93.3 are presented. Both subcooled and saturated flow boiling are investigated, covering operating pressures from 120 to 660 kPa, mass fluxes from 290 to 690 kg m{sup -2} s{sup -1} and heat fluxes from 50 to 440 kW m{sup -2}. Existing correlations for subcooled flow pressure drop are found not capable to fit the present subcooled database, while the measurements in saturated flow conditions are successfully reproduced by existing correlations for both straight and coiled pipe two-phase flow. The experimental database is included in tabular form. (author)

Cioncolini, Andrea; Santini, Lorenzo; Ricotti, Marco E. [Department of Nuclear Engineering, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy)

2008-05-15

68

A proposed model to include a residual NAPL saturation in a hysteretic capillary pressure–saturation relationship  

Microsoft Academic Search

A residual non-aqueous phase liquid (NAPL) present in the vadose zone can act as a contaminant source for many years as the compounds of concern partition to infiltrating groundwater and air contained in the soil voids. Current pressure–saturation–relative permeability relationships do not include a residual NAPL saturation term in their formulation. This paper presents the results of series of two-

P. J. Van Geel; S. D. Roy

2002-01-01

69

Experimental Characterization of Redox Changes During Degassing of a Vapor Saturated Magma: Redox Exchanges Between H-O-Fe Species  

NASA Astrophysics Data System (ADS)

The redox state of a magma reaching the surface is generally thought to be buffered by its iron redox ratio during ascent, reflecting therefore that of its source region. Only recently, the role of volatiles degassing on redox state of silicic magmas has been quantitatively addressed using numerical modelling. In these iron-poor magmatic systems, oxygen fugacity (fO2) is almost dominated by the chemical potential of the H2 and H2O volatile components. Because water is several orders of magnitude more soluble than molecular hydrogen in molten silicate, it was found that the ratio of their chemical potential dramatically changes during closed system degassing leading to an increase in fO2 of 2 orders of magnitude. We present here the results of an experimental test of such an oxidation event associated to the decompression of silicic melts saturated in volatiles. A peralkaline synthetic composition containing 2-4wt percent of dissolved iron oxides is used as starting material. Experiments are performed in cold seal pressure vessels pressurized with pre-mixed argon and hydrogen bottles. All experiments are equilibrated under water-saturated conditions at 800°C and variable pressures between 200 MPa and 25 MPa. Experiments were ended by rapid drop quench. Three oxygen fugacity conditions were investigated by using pure Argon (NNO+3) and two Ar-H2 mixtures buffering fO2 conditions at NNO+1.5 and NNO. Water content was determined using infrared spectroscopy and Karl-Fisher titration and the iron redox ratio was measured by wet chemistry. All run products are free of crystals. Time series experiments at fixed pressure were performed to determine the equilibrium dependence of iron redox ratios on pressure. Decompression experiments were performed from an equilibrated vapor-saturated melt at 200 MPa, lasted from few minutes to few hours, and were quenched at 100 MPa to 25 MPa. The measured iron redox ratios after decompression do not considerably differ from the ones before decompression. A slight oxidation is however noticed for some experiments, which can correspond to 0.7 log- units of fO2 increase in the most favorable cases. We conclude that a "Le Chatelier effect" most likely dominates and restricts the fO2 increase that is otherwise expected to be of ~2 log units in an iron-free melt: The increase in the fugacity ratios of H2O/H2 due to degassing upon decompression is restricted by H2 produced during oxidation of ferrous iron by water. The importance of this "Le Chatelier effect" strongly depends on the fO2 conditions prior to degassing.

Mollard, E.; Gaillard, F.; Scaillet, B.

2007-12-01

70

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...AND DISPOSAL FACILITIES Air Emission Standards for Equipment... § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each...

2013-07-01

71

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...AND DISPOSAL FACILITIES Air Emission Standards for Equipment... § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each...

2013-07-01

72

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...AND DISPOSAL FACILITIES Air Emission Standards for Equipment... § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each...

2012-07-01

73

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...AND DISPOSAL FACILITIES Air Emission Standards for Equipment... § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each...

2012-07-01

74

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

75

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

76

Study of the effects of noisy data on the determination of the enthalpy of vaporization from a vapor pressure equation  

E-print Network

Chemical engineers use software tools everyday to aid them in solving complex problems. Software packages simulate virtually every aspect of a chemical process, including the use of source vapor pressure data to fit empirical constants of a vapor...

Casserly, Thomas Bryan

2013-02-22

77

Psychrometric and ventilation constraints for vapor pressure deficit control  

Microsoft Academic Search

Constraints on air temperature, dewpoint temperature and ventilation rate in plant growth and propagation chambers under vapor pressure deficit (VPD) control are presented. These constraints apply to any controlled environment space subjected to significant radiation in which both air temperature and humidity can be simultaneously manipulated. Defining relations and logic necessary to implement two methods of VPD control (VPDair vs.

S Zolnier; R. S Gates; J Buxton; C Mach

2000-01-01

78

CHROMIUM VAPOR PRESSURE OVER SOLID CHROMIUM-IRON ALLOYS  

Microsoft Academic Search

The chromium vapor pressure over chromium-iron alloys was measured in ; the temperature range 1100 deg to 1400 deg C to determine the thermodynamic ; functions of the solutions. The Knudsen effusion method with radiometric ; determination was used to evaluate the quantity of chromium condensed on targets. ; Electronic iron and chromium (the latter containing Cr⁵¹) were melted in

Vintaikin

1958-01-01

79

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

80

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor...

2013-07-01

81

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor...

2012-07-01

82

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor...

2012-07-01

83

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor...

2013-07-01

84

Effects of vapor pressure/velocity and concentration on condensation heat transfer for steam-ethanol vapor mixture  

NASA Astrophysics Data System (ADS)

When a steam-ethanol vapor mixture condenses on a vertical flat plate, the form of the condensate film changes and many drops are created. This non-film condensation is called pseudo-dropwise or Marangoni condensation. This paper aims to study the main influencing factors on the Marangoni condensation of steam-ethanol vapor.The factors include the ethanol concentration, vapor pressure, vapor velocity and vapor-to-surface temperature difference. The experiments show that the heat transfer coefficient has a maximum value of approximately 42 kW/m2 K when the ethanol concentration is 1%. At the low concentrations of 0.5, 1, 5.1 and 9.8%, the condensation heat transfer is greater than for pure steam. In addition, the heat transfer for all vapor mixtures increases with both the rise of vapor pressure and vapor velocity.

Yan, Junjie; Yang, Yusen; Hu, Shenhua; Zhen, Kejian; Liu, Jiping

2007-11-01

85

Vapor pressure of C{sub 70} fullerene  

SciTech Connect

The equilibrium pressures over C{sub 70} were measured in the temperature range 783-904 K by the torsion effusion and Knudsen effusion methods. The obtained data are well represented by the following selected equation: log(p/Pa) = (11.38{+-}0.15) - (9917{+-}160)/(T/K). Assuming the vapor phase constituted by only C{sub 70(g)}, the sublimation standard enthalpy of this compound, {Delta}{sub sub}H{degree}(298) = 200{+-}6 kJ mol{sub -1}, as derived by second law elaboration of the experimental data, was derived. From the vapor pressure data, an evaluation of the free energy functions for solid C{sub 70} has been made. The heat of formation of gaseous C{sub 70}, {Delta}{sub for}H{degree}(298) = 2755{+-}18 kJ/mol{sub -1}, was also derived. 21 refs., 1 fig., 6 tabs.

Piacente, V.; Gigli, G.; Scardala, P.; Giustini, A.; BArdi, G. [Universita di Roma `La Sapienza` (Italy)] [Universita di Roma `La Sapienza` (Italy)

1996-06-06

86

Low vapor pressure braze alloys for thermionic energy converters  

NASA Technical Reports Server (NTRS)

The evaluation of cesium diode electrode materials called for braze fillers with very low vapor pressures and a wide range of melting points. Binary alloys of low vapor pressure refractory metals were chosen to fill this need. These alloys of Th, Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W have reported melting point minima or eutectics from 1,510 K to above 3,000 K. Preliminary data are compiled on the use of several of these braze alloys. Melting points and surface wetting on a Ta base are given. Results of brazing Ir, LaB6, Nb, Re, W, and Zr-22 wt % ZrO2 materials into Ta and Nb-1% Zr bases are presented. Current braze usage is summarized.

Bair, V. L.

1976-01-01

87

Pore Network Modeling of Capillary Pressure -- Saturation Relations Through Retention Cells and Equilibrium Fluid Distributions in Long Columns  

Microsoft Academic Search

Standard methods for experimentally determining capillary pressure -- saturation relations of a porous medium use retention cells: a small cell filled with the porous medium is connected to two pressure reservoirs for the two given fluids. Then, the saturation is recorded as the pressure difference is changed. Conversely, one can infer capillary pressure -- saturation relations by analyzing equilibrium fluid

R. Glantz; M. Hilpert

2009-01-01

88

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

89

Vapor pressure scanning of nonstoichiometry in CdTe  

SciTech Connect

Results of vapor pressure scanning of the cadmium telluride solidus surface are reported. The deviation from stoichiometry is found to be up to (0.6-13.8) [times] 10[sup [minus]3] at.% at temperatures from 945 to 1,360 K and vapor pressures from 2.3 to 87.2 kPa on the tellurium side, while that on the cadmium side is (0.1-3.3) [times] 10[sup [minus]3] at.% in the temperature and vapor pressure ranges from 695 to 992 K and from 0.5 to 57.3 kPa, respectively. The position of the congruent sublimation curve in the P-T-X phase space is discussed and some specifics of the solidus surface are outlined. The maximum congruent sublimation temperature was found to be 1,324 K, 41 K lower than the maximum melting point of CdTe. P(Cd)-T and P(Te[sub 2])-T projections of the Cd-Te phase diagram are presented. Partial molar enthalpies and entropies of the component elements are deduced for cadmium telluride. 12 refs., 3 figs., 2 tabs.

Greenberg, J.H.; Guskov, V.N.; Lazarev, V.B.; Shebershneva, O.V. (Kurnakov Inst. of General and Inorganic Chemistry, Moscow (Russian Federation))

1993-02-01

90

Chemical Vapor Deposition at High Pressure in a Microgravity Environment  

NASA Technical Reports Server (NTRS)

In this paper we present an evaluation of critical requirements of organometallic chemical vapor deposition (OMCVD) at elevated pressure for a channel flow reactor in a microgravity environment. The objective of using high pressure is to maintain single-phase surface composition for materials that have high thermal decomposition pressure at their optimum growth temperature. Access to microgravity is needed to maintain conditions of laminar flow, which is essential for process analysis. Based on ground based observations we present an optimized reactor design for OMCVD at high pressure and reduced gravity. Also, we discuss non-intrusive real-time optical monitoring of flow dynamics coupled to homogeneous gas phase reactions, transport and surface processes. While suborbital flights may suffice for studies of initial stages of heteroepitaxy experiments in space are essential for a complete evaluation of steady-state growth.

McCall, Sonya; Bachmann, Klaus; LeSure, Stacie; Sukidi, Nkadi; Wang, Fuchao

1999-01-01

91

A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space  

E-print Network

A modeling approach to represent hysteresis in capillary pressure- saturation relationship based presents a new model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships

Zhou, Quanlin

92

Capillary pressure saturation relations supercritical CO2 and brine in sand: High-pressure Pc(Sw) controller/meter measurements and capillary scaling predictions  

E-print Network

lary pressure-saturation relationships of porous media withCapillary pressure-saturation rela- tions in porous mediapressure, salinity and in situ conditions on CO 2 injection into saline aquifers, Transp. Porous Media,

Tokunaga, T.K.

2014-01-01

93

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

94

Study of capillary pressure-saturation relationships using a dynamic pore-scale network model  

NASA Astrophysics Data System (ADS)

Current theories of multiphase flow rely on capillary pressure and saturation relationships that are commonly measured under static conditions. Recently, new multiphase flow theories have been proposed that include a new capillary pressure-saturation relationship that is valid under dynamic conditions. In this relationship, the difference between the two fluid pressures is called dynamic capillary pressure, and is assumed to be a function of the saturation and its time rate of change: Pc,dyn = Pn - Pw = Pc,stat - L dS/dt The dynamic effect is governed by the coefficient L that, in general, may be a function of saturation. In this work, we test this relationship using a pore-scale network model. Our model consists of a three-dimensional network of tubes (pore throats) connected to each other by pore bodies. Both pore bodies and pore throats are assumed to have square cross sections. We perform numerical experiments wherein both static and dynamic procedures for measurements of capillary pressure-saturation curves are simulated. We show that the dynamic correction term may indeed be important when large pressure gradient are imposed on the fluids. We determine the value of the coefficient L and investigate its dependence on soil and fluids properties.

Gielen, T.; Nordhaug, H.; Dahle, H.; Celia, M.; Hassanizadeh, S.

2001-12-01

95

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.

96

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.

97

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

98

Acidic vapors above saturated salt solutions commonly used for control of humidity  

Microsoft Academic Search

The gaseous transfer of chlorine but not sodium from a saturated NaCl solution to copper coupons has been demonstrated in a bell jar that was sealed for nine years. Thermodynamic calculations indicate that the active agent, HCl (g), is in equilibrium with H+ (aq) and Cl - (aq) in the saturated salt solution. Auger electron spectroscopy was used to analyze

C. J. Weschler; R. Schubert

1989-01-01

99

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

100

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

101

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

102

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

103

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

104

Vapor pressure of C{sub 60} buckminsterfullerene  

SciTech Connect

The equilibrium pressures over C{sub 60} were measured over a large temperature range, 730-990 K, by the torsion effusion and Knudsen effusion methods. The data obtained are well represented by the following selected linear equation: log(p/kPa) = (8.28 {+-} 0.20) - (9154 {+-} 150)/T. Considering the vapor phase constituted by only C{sub 60(g)}, the sublimation standard enthalpy of this compound, {Delta}{sub sub}H{sup 0}(298) = 181 {+-} 2 kJ mol{sup -1}, as derived by second- and third-law elaboration of the experimental data, is proposed. Considerations on free energy functions of the solid C{sub 60} are also reported. 26 refs., 3 figs., 8 tabs.

Piacente, V.; Gigli, G.; Scardala, P.; Giustini, A. [Universita di Roma `La Sapienza` (Italy)

1995-09-21

105

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

106

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

107

Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion  

NASA Astrophysics Data System (ADS)

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse oximeters showed gradual decrease of saturations during induced hypoperfusion which demonstrate the direct relation between blood volumes (PPG amplitudes), arterial vessel stenosis and blood oxygen saturation. The custom made pulse oximeter was found to be more sensitive to SpO2 changes than the commercial pulse oximeter especially at high occluding pressures.

Kyriacou, P. A.; Shafqat, K.; Pal, S. K.

2007-10-01

108

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...PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Equipment Leaks § 65.111 Standards: Pressure relief devices in...

2013-07-01

109

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...PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Equipment Leaks § 65.111 Standards: Pressure relief devices in...

2012-07-01

110

Capillary Pressure-Saturation Relations for Saprolite: Scaling With and Without Correction for Column Height  

Microsoft Academic Search

Dense nonaqueous phase liquids (DNAPLs) are important subsur- the capillary pressure-saturation relationship, hereafter face contaminants. Information is lacking on DNAPL behavior in heterogeneous porous media such as weathered rock (saprolite). We denoted by w(hc), where w is the volumetric content of measured air-water and Fluorinert (a nontoxic DNAPL surrogate; the wetting fluid and hc is the capillary pressure head. 3M,

E. Perfect; L. D. McKay; S. C. Cropper; S. G. Driese; G. Kammerer; J. H. Dane

2004-01-01

111

Measurement and prediction of saturation-pressure relationships in three-phase porous media systems  

Microsoft Academic Search

Scaled multiphase versions of the Brooks-Corey and van Genuchten retention functions were used to describe saturation-capillary pressure curves measured in air-water, air-organic liquid and organic liquid-water systems in a sandy porous medium for four organic liquids during monotonic wetting phase drainage. Scaling was achieved by a linear transformation of capillary pressures using scaling coefficients which are shown to be closely

R. J. Lenhard; J. C. Parker

1987-01-01

112

Dynamic Effect in the Capillary PressureSaturation Relationship and its Impacts on Unsaturated Flow  

E-print Network

Dynamic Effect in the Capillary Pressure­Saturation Relationship and its Impacts on Unsaturated should be generalized to include dynamic ef- All of these effects are essentially lumped into the Pc ­S depicted in Fig. 1 are obtained experi-includes dynamic effects. A review of these experiments shows

Hassanizadeh, S. Majid

113

NEW COREFLOOD SIMULATOR BASED ON INDEPENDENT TREATMENT OF IN-SITU SATURATION AND PRESSURE DATA  

Microsoft Academic Search

When capillary pressure is important water\\/oil and gas\\/oil displacement tests need to be interpreted carefully to establish the underlying relative permeability, since the JBN method will under estimate oil recovery and artificially suppress relative permeabilities. Previous work used a recasting of the Darcy flow equations to develop a method for interpreting displacement tests by direct processing of saturation data. These

David J Element; Stephen G Goodyear

114

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

115

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor...

2013-07-01

116

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...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor...

2012-07-01

117

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

118

Total sulfur dioxide emissions and pre-eruption vapor-saturated magma at Mount St. Helens, 1980-88  

SciTech Connect

SO{sub 2} from explosive volcanism can cause significant climatic and atmospheric impacts, but the source of the sulfur is controversial. TOMS, COSPEC, and ash leachate data for Mount St. Helens from the time of the climactic eruption on 18 May 1980 to the final stages of non-explosive degassing in 1988 give a total SO{sub 2} emission of 2 Mt. COSPEC data show a sharp drop in emission rate that was apparently controlled by a decreasing rate of magma supply. A total SO{sub 2} emission of only 0.08 Mt is estimated from melt inclusion data and the conventional assumption that the main sulfur source was pre-eruption melt; commonly invoked sources of {open_quotes}excess sulfur{close_quotes} (anhydrite decomposition, basaltic magma, and degassing of non-erupted magma) are unlikely in this case. Thus melt inclusions may significantly underestimate SO{sub 2} emissions and impacts of explosive volcanism on climate and the atmosphere. Measured CO{sub 2} emissions, together with the H{sub 2}O content of melt inclusions and experimental solubility data, indicate the Mount St. Helens dacite was vapor-saturated at depth prior to ascent and suggest that a vapor phase was the main source of sulfur for the 2-Mt of SO{sub 2}. A vapor source is consistent with experimental studies on the Mount St. Helens dacite and removes the need for a much debated shallow magma body. 23 refs., 3 figs.

Gerlach, T.M.; McGee, K.A. [Geological Survey, Vancouver, WA (United States)] [Geological Survey, Vancouver, WA (United States)

1994-12-15

119

Reducing deuterium-tritium ice roughness by electrical heating of the saturated vapor  

SciTech Connect

High gain targets for inertial confinement fusion (ICF) contain a layer of deuterium-tritium (DT) ice which surrounds a volume of DT gas in thermal equilibrium with the solid. The roughness of the cryogenic fuel layer inside of ICF targets is one of the sources of imperfections which cause implosions to deviate from perfect one dimensional performance. Experiments at Lawrence Livermore National Laboratory have shown that applying a heat flux across the inner surface of a hydrogen layer such as that inside an ICF target reduces the intrinsic roughness of the surface. We have developed a technique to generate this heat flux by applying and electric field to the DT vapor in the center of these shells. This vapor has a small but significant conductivity due to ionization caused by beta decay of tritium in the vapor and the solid. We describe here experiments using a 1.15 GHz cavity to apply an electric field to frozen DT inside of a sapphire test cell. The cell and cavity geometry allows visual observation of the frozen layers.

Mapoles, E.R. [Lawrence Livermore National Lab., CA (United States); Sater, J.D.; Monsler, E. [Schafer (W.J.) Associates, Inc., Livermore, CA (United States); Pipes, J. [Allied-Signal Inc., Livermore, CA (United States)

1996-06-14

120

Comparison of height-averaged and point-measured capillary pressure–saturation relations for sands using a modified Tempe cell  

Microsoft Academic Search

Tempe cells and similar devices are often used for measurements of capillary pressure versus saturation relationships (retention curves) of soils. Average water saturation within the sample is often used as the representative saturation. For cases where the saturation distribution along the cell height is nonuniform, use of the height-averaged water saturation artificially smoothes the retention curve when the capillary pressure

Toshihiro Sakaki; Tissa H. Illangasekare

2007-01-01

121

Comparison of height-averaged and point-measured capillary pressure-saturation relations for sands using a modified Tempe cell  

Microsoft Academic Search

Tempe cells and similar devices are often used for measurements of capillary pressure versus saturation relationships (retention curves) of soils. Average water saturation within the sample is often used as the representative saturation. For cases where the saturation distribution along the cell height is nonuniform, use of the height-averaged water saturation artificially smoothes the retention curve when the capillary pressure

Toshihiro Sakaki; Tissa H. Illangasekare

2007-01-01

122

Vapor pressure of ethyl (5-cyano-3,4-diphenyl-6-oxo-1,6-dihydropyridazin-1-yl)acetate by the effusion method  

SciTech Connect

The effusion method was used to determine the vapor pressure of ethyl (5-cyano-3,4-diphenyl-6-oxo-1,6-dihydropyridazin-1-yl)acetate (I) at 13 temperatures, in the range 123-141 /sup 0/C, with a minimum of two results at each temperature. Measured vapor pressures were in the range 10/sup -4/-6 X 10/sup -4/ torr and were expressed by the following equation: log p = 13.40 - (689 1/T), where p is the vapor pressure in torr and T is the absolute temperature. The 95% confidence limits for the constants of the equation are respectively + or - 1.19 and + or - 486. Experimental conditions studied included effusion hole diameter and effusion time. This compound undergoes no phase change below the melting point (about 143 /sup 0/C). All the results are for the crystalline phase below 143 /sup 0/C. Some results by the gas saturation procedure are also included.

DePablo, R.S.

1982-10-01

123

Relation of blood pressure to reported intake of salt, saturated fats, and alcohol in healthy middle-aged population  

Microsoft Academic Search

The association of blood pressure with reported intake of salt, saturated fats, and alcohol was studied in a sample of 8479 subjects based on a cross sectional survey in a population aged 30 to 64 years. A consistent association was found between the mean arterial pressure and the intake of alcohol (p less than 0.001) and saturated fats (p less

J T Salonen; J Tuomilehto; A Tanskanen

1983-01-01

124

PHOTOLYSIS OF ARYL KETONES WITH VARYING VAPOR PRESSURE ON SOIL  

EPA Science Inventory

The photolysis of a series of aryl ketones on air-dried soil surfaces was examined to establish whether vapor transport has an effect on the rate and extent of photolysis. f vapor transport were significant on light-exposed soils, then differences in the observed photolysis rate ...

125

Experimental studies on the enhanced flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in vertical porous coated tube  

NASA Astrophysics Data System (ADS)

The characteristics of flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.

Yang, Dong; Shen, Zhi; Chen, Tingkuan; Zhou, Chenn Q.

2013-07-01

126

Studies of the Afterglow in Mercury Vapor. I. Intensity Pressure Relations  

Microsoft Academic Search

The intensities of the stronger lines in the subordinate series of the afterglow spectrum of mercury were measured by photographic methods as a function of vapor pressure from 0.1 mm to 2.0 mm Hg in a stream of vapor distilled from a mercury arc into a side tube. Measurements made with the ion concentration held constant at the point of

Robert C. Garth; George E. Moore

1941-01-01

127

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

128

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

129

Vapor pressures and thermodynamic properties of strontium silicides  

Microsoft Academic Search

The high temperature vaporization processes of strontium silicides were studied by means of the Knudsen Effusion Mass Spectrometry and Knudsen Effusion Weight Loss techniques in the temperature range 665–1300K, with reference to the recent reinvestigation of the Sr–Si phase diagram [Palenzona A, Pani M. J Alloys Compd 2004;373:214.]. The only species detected in the vapor phase equilibrated with two-phase solid

G. Balducci; S. Brutti; A. Ciccioli; G. Gigli; G. Trionfetti; A. Palenzona; M. Pani

2006-01-01

130

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, January 1, 1994--March 31, 1994  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. Sophisticated general correlative approaches are slowly being developed, based upon group contribution methods, or based upon some key functional features of the molecules. These are as yet difficult to apply to coal tars. The detailed group contribution methods, in which fairly precise structural information is needed, do not lend themselves well for application to very complex, poorly characterized coal tars. The methods based upon more global types of characterizations have not yet dealt much with the question of oxygenated functional groups. In short, only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion.

Suuberg, E.M.

1994-06-01

131

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

132

Bilayer graphene growth by low pressure chemical vapor deposition on copper foil  

E-print Network

Successfully integrating graphene in standard processes for applications in electronics relies on the synthesis of high-quality films. In this work we study Low Pressure Chemical Vapor Deposition (LPCVD) growth of bilayer ...

Fang, Wenjing, S.M. Massachusetts Institute of Technology

2012-01-01

133

Single- and few-layer graphene by ambient pressure chemical vapor deposition on nickel  

E-print Network

An ambient pressure chemical vapor deposition (APCVD) process is used to fabricate graphene based films consisting of one to several graphene layers across their area. Polycrystalline Ni thin films are used and the graphene ...

Reina Ceeco, Alfonso

2010-01-01

134

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

: FAMEs; Vapor pressure; Vaporization enthalpy; Correlation gas chromatography19 20 1. Introduction21 for chlorinated23 hydrocarbons in industrial processes [1], for diesel fuel [2] and24 lubricants. The larger- 36 cessful in providing vaporization enthalpies of both liquids and 37 solids, particularly

Chickos, James S.

135

Modeling of Moisture Diffusion and Whole-Field Vapor Pressure in Plastic Packages of IC Devices  

Microsoft Academic Search

\\u000a Moisture diffusion and vapor pressure development analyses are the key to understand the moisture-induced failure mechanisms\\u000a in electronic packages. In this chapter, theories and applications of moisture diffusion modeling and vapor pressure analysis\\u000a are reviewed. The unique characteristics of moisture diffusion in multi-material system are described. The commonly used normalization\\u000a methods to remove interfacial discontinuity are presented, and the details

X. J. Fan; T. Y. Tee; X. Q. Shi; B. Xie

136

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

137

Fractional-calculus model for temperature and pressure waves in fluid-saturated porous rocks.  

PubMed

We study a fractional time derivative generalization of a previous Natale-Salusti model about nonlinear temperature and pressure waves, propagating in fluid-saturated porous rocks. Their analytic solutions, i.e., solitary shock waves characterized by a sharp front, are here generalized, introducing a formalism that allows memory mechanisms. In realistic wave propagation in porous media we must take into account spatial or temporal variability of permeability, diffusivity, and other coefficients due to the system "history." Such a rock fracturing or fine particulate migration could affect the rock and its pores. We therefore take into account these phenomena by introducing a fractional time derivative to simulate a memory-conserving formalism. We also discuss this generalized model in relation to the theory of dynamic permeability and tortuosity in fluid-saturated porous media. In such a realistic model we obtain exact solutions of Burgers' equation with time fractional derivatives in the inviscid case. PMID:22060520

Garra, Roberto

2011-09-01

138

Temperature and water vapor pressure effects on the friction coefficient of hydrogenated diamondlike carbon films.  

SciTech Connect

Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior that does not reoccur even after extended periods of exposure to low partial pressures of H{sub 2}O and O{sub 2}. Experiments varying both water vapor pressure and sample temperature show trends of a decreasing friction coefficient as a function of both the decreasing water vapor pressure and the increasing substrate temperature. Theses trends are examined with regard to first order gas-surface interactions. Model fits give activation energies on the order of 40 kJ/mol, which is consistent with water vapor desorption.

Dickrell, P. L.; Sawyer, W. G.; Eryilmaz, O. L.; Erdemir, A.; Energy Technology; Univ. of Florida

2009-07-01

139

Establishing a quantitative functional relationship between capillary pressure saturation and interfacial area. 1998 annual progress report  

SciTech Connect

'Through an integrated and focused research program that is comprised of theoretical, computational and experimental efforts this research effort is directed at: (1) improving on newly developed laboratory techniques to quantify and directly measure the functional relationship between phase interfacial area (a), saturation (S) and capillary pressure (Pc), (2) developing new computational algorithms in conjunction with laboratory measurements to predict Pc, S and a, (3) testing existing theory and developing new theory to describe the relationship between Pc, S and a at the large scale, and (4) synthesizing the results of the experimental, computational and theoretical investigative efforts to develop a generic model based upon an intrinsic soil metric to describe the functional dependence of Pc, S and a. The results of this research could be used to generate a site specific soil moisture characteristic surface. Ultimately the results of this research could serve as the foundation upon which the true health and safety risk of a site could be evaluated, the applicability of various remediation technologies examined, and the performance of implemented treatment strategies controlled. This report summarizes work after 18 months of a 3-year project. The authors are working to integrate the theory, experiments, and numerical simulations into a coherent approach to study the role of interfacial areas in porous media flow physics. The recent efforts have focused on quantifying the relationship between capillary pressure, saturation, and interfacial areas. The theory developed by Gray et al. (1998) indicates clearly that the traditional relationship between capillary pressure and saturation is incomplete, and interfacial area per unit volume must be added to the functional dependence. The theory does not, however, provide the form of that functional dependence; determination of this relationship must be done experimentally. To this end, both the network modelling and the PVI approach are being pursued.'

Montemagno, C.D. [Cornell Univ., Ithaca, NY (US); Celia, M. [Princeton Univ., NJ (US); Gray, W.G. [Univ. of Notre Dame, IN (US)

1998-06-01

140

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

Code of Federal Regulations, 2011 CFR

...false High and low vapor pressure protection for tankships-T/ALL. 39.20-13 Section 39.20-13 Shipping COAST...20-13 High and low vapor pressure protection for tankships—T/ALL. Each tankship vapor collection system must be...

2011-10-01

141

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

142

Vapor Pressure and Mean Adsorption Time of Pyromellitic Dianhydride and 4,4?-Oxidianiline  

NASA Astrophysics Data System (ADS)

Thermogravimetry (TG) measurements taken at pressures ranging from 10-1 to 10-3 Pa are used to calculate the vapor pressure of pyromellitic dianhydride (PMDA) and 4,4?-oxidianiline (ODA). The vapor pressure calculated for PMDA is closely agrees with to those reported by Pethe et al.., Elshazly and Salem. For ODA, the calculated vapor pressure fits exactly on the curve obtained by Salem. The enthalpy is also calculated. The activation energy of desorption is found to be nearly equal to the enthalpy. The adsorption and desorption rates for both PMDA and ODA at various substrate temperatures are also observed. The mean adsorption time, ? calculated for ODA is several orders of magnitude larger than that for PMDA. 1:1 doses of ODA and PMDA therefore produce imine bonds which lead to the formation of thermally unstable films.

Dutt, Radhika; Takahashi, Yoshikazu; Iijima, Masayuki

1999-06-01

143

Vapor pressures of substituted polycarboxylic acids are much lower than previously reported  

NASA Astrophysics Data System (ADS)

The partitioning of compounds between the aerosol and gas phase is a primary focus in the study of the formation and fate of secondary organic aerosol. We present measurements of the vapor pressure of 2-methylmalonic (isosuccinic) acid, 2-hydroxymalonic (tartronic) acid, 2-methylglutaric acid, 3-hydroxy-3-carboxy-glutaric (citric) acid and DL-2,3-dihydroxysuccinic (DL-tartaric) acid, which were obtained from the evaporation rate of supersaturated liquid particles levitated in an electrodynamic balance. Our measurements indicate that the pure component liquid vapor pressures at 298.15 K for tartronic, citric and tartaric acids are much lower than the same quantity that was derived from solid state measurements in the only other room temperature measurement of these materials (made by Booth et al., 2010). This strongly suggests that empirical correction terms in a recent vapor pressure estimation model to account for the inexplicably high vapor pressures of these and similar compounds should be revisited, and that due caution should be used when the estimated vapor pressures of these and similar compounds are used as inputs for other studies.

Huisman, A. J.; Krieger, U. K.; Zuend, A.; Marcolli, C.; Peter, T.

2013-07-01

144

Vitrification of polymer solutions as a function of solvent quality, analyzed via vapor pressures.  

PubMed

Vapor pressures (headspace sampling in combination with gas chromatography) and glass transition temperatures [differential scanning calorimetry (DSC)] have been measured for solutions of polystyrene (PS) in either toluene (TL) (10-70 degrees C) or cyclohexane (CH) (32-60 degrees C) from moderately concentrated solutions up to the pure polymer. As long as the mixtures are liquid, the vapor pressure of TL (good solvent) is considerably lower than that of CH (theta solvent) under other identical conditions. These differences vanish upon the vitrification of the solutions. For TL the isothermal liquid-solid transition induced by an increase of polymer concentration takes place within a finite composition interval at constant vapor pressure; with CH this phenomenon is either absent or too insignificant to be detected. For PS solutions in TL the DSC traces look as usual, whereas these curves may become bimodal for solutions in CH. The implications of the vitrification of the polymer solutions for the determination of Flory-Huggins interaction parameters from vapor pressure data are discussed. A comparison of the results for TL/PS with recently published data on the same system demonstrates that the experimental method employed for the determination of vapor pressures plays an important role at high polymer concentrations and low temperatures. PMID:16689599

Bercea, Maria; Wolf, Bernhard A

2006-05-01

145

Vitrification of polymer solutions as a function of solvent quality, analyzed via vapor pressures  

NASA Astrophysics Data System (ADS)

Vapor pressures (headspace sampling in combination with gas chromatography) and glass transition temperatures [differential scanning calorimetry (DSC)] have been measured for solutions of polystyrene (PS) in either toluene (TL) (10-70 °C) or cyclohexane (CH) (32-60 °C) from moderately concentrated solutions up to the pure polymer. As long as the mixtures are liquid, the vapor pressure of TL (good solvent) is considerably lower than that of CH (theta solvent) under other identical conditions. These differences vanish upon the vitrification of the solutions. For TL the isothermal liquid-solid transition induced by an increase of polymer concentration takes place within a finite composition interval at constant vapor pressure; with CH this phenomenon is either absent or too insignificant to be detected. For PS solutions in TL the DSC traces look as usual, whereas these curves may become bimodal for solutions in CH. The implications of the vitrification of the polymer solutions for the determination of Flory-Huggins interaction parameters from vapor pressure data are discussed. A comparison of the results for TL/PS with recently published data on the same system demonstrates that the experimental method employed for the determination of vapor pressures plays an important role at high polymer concentrations and low temperatures.

Bercea, Maria; Wolf, Bernhard A.

2006-05-01

146

Inner pressure control method in optical fiber preform fabrication by vapor-phase axial deposition  

Microsoft Academic Search

A method to control inner pressure variation in a vapor-phase axial-deposition (VAD) apparatus is developed. It uses a flame-detection technology to explain temperature fluctuations. Primary causes of the inner pressure fluctuations are analyzed, and suppression techniques are described. They include the adoption of a large buffer-tank and bias gas addition. An inner pressure-feedback control mechanism operates by adjusting the bias

Katsuyuki Imoto; Masao Sumi

1988-01-01

147

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

148

Pore water pressure increment model for saturated Nanjing fine sand subject to cyclic loading  

NASA Astrophysics Data System (ADS)

Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure (EPWP) ratio variation with the ratio of the number of cycles are provided. The concept of the EPWP increment ratio is introduced and two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined. It is found that the development of the EPWP increment ratio can be divided into three stages: descending, stable and ascending. Furthermore, at the stable and ascending stages, a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and natural logarithm of the effective dynamic shear stress ratio. Accordingly, the EPWP increment ratio at the number of cycles N has been deduced that is proportional to the log decrement of effective stress at the cycle number N-1, but is independent of the cyclic stress amplitude. Based on the analysis, a new EPWP increment model for saturated Nanjing fine sand is developed from tested data fitting, which provides a better prediction of the curves of EPWP generation, the number of cycles required for initial liquefaction and the liquefaction resistance.

Wang, Binghui; Chen, Guoxing; Jin, Dandan

2010-12-01

149

The design, construction and three dimensional modeling of a high pressure organometallic chemical vapor deposition reactor  

NASA Astrophysics Data System (ADS)

Two high pressure reactors have been designed, built and tested, in order to extend Organometallic Chemical Vapor Deposition (OMCVD) to materials that exhibit large thermal decomposition pressures at their optimum growth temperature. The Differentially Pressure Controlled (DPC) Reactor System was designed and built for use at pressures ?10 atm. A second generation reactor, the Compact Hard Shell (CHS) Reactor was built in order to extend pressures ?100 atm. A physico-chemical model of the High Pressure Organometallic Chemical Vapor Deposition (HPOMCVD) process that describes three dimensional transport phenomena as well as gas-phase and surface reactions underlying the growth of compound semiconductors is presented. A reduced-order model of the Organometallic Chemical Vapor Deposition of InN from trimethylindium and ammonia at elevated pressures has been developed and tested. The model describes the flow dynamics coupled to chemical reactions and transport in the flow channel of the Compact Hard Shell Reactor, as a function of substrate temperature, total pressure and centerline flow velocity.

McCall, Sonya Denise

150

Non-invasive Positive Pressure Ventilation during Sleep at 3800m: relationship to Acute Mountain Sickness and sleeping oxyhemoglobin saturation  

PubMed Central

Background and objectives Ascent to high altitude results in hypobaric hypoxia and some individuals will develop Acute Mountain Sickness, which has been shown to be associated with low oxyhemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake, results in a reduction in AMS symptoms and higher oxyhemoglobin saturation. We aimed to test whether pressure ventilation during sleep would prevent AMS by keeping oxyhaemoglobin higher during sleep. Methods We compared sleeping oxyhemoglobin saturation and the incidence and severity of Acute Mountain Sickness in seven subjects sleeping for two consecutive nights at 3800m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of Acute Mountain Sickness was assessed by administration of the Lake Louise questionnaire. Results We found significant increases in the mean and minimum sleeping oxyhemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusion The use of positive pressure ventilation during sleep at 3800m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation. PMID:20051046

Johnson, PL; Popa, DA; Prisk, GK; Sullivan, CE; Edwards, N

2014-01-01

151

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, April 1, 1996--June 30, 1996  

SciTech Connect

As the world continues to deplete its petroleum reserves, then heavy crude oil, coal liquids, and other heavy fossil fuels may be required to meet the world energy needs. Heavy fossil fuels contain molecules that are large and more aromatic and that contain more heteroatoms than those found in liquid crude oil. There is also significant current interest in general area of coal pyrolysis, particularly with respect to comprehensive models of this complicated phenomenon. This interest derives from central role of pyrolysis in all thermally driven coal conversion processes - gasification, combustion, liquefaction, mild gasification, or thermal beneficiation. There remain several key data needs in these application areas. Among them is a need for a more reliable correlation for prediction of the vapor pressures of heavy, primary coal tars. Such information is important in design of all coal conversion processes, in which the volatility of tarry products is of major concern. This paper presents work on the vapor pressures of coal tars using the continuous knudsen effusion technique.

Suuberg, E.M.; Oja, V.; Lilly, W.D.

1997-12-31

152

VAPOR PRESSURE AND MELTING BEHAVIOR OF SULFURIC ACID-WATER SYSTEMS  

EPA Science Inventory

An experimental apparatus was designed and constructed to use high vacuum and mass spectrometric techniques to determine total and partial vapor pressures above bulk liquid samples in the temperature range between -65C and 25C. Observations on the sulfuric acid-water system revea...

153

Emissivity correcting pyrometer for temperature measurement in low pressure chemical vapor deposition  

Microsoft Academic Search

Rapid thermal processing (RTP) low pressure chemical vapor deposition (LPCVD) requires accurate wafer temperature measurement to control film deposition during processing. The temperature sensor discussed detects a portion of the target radiance as a DC signal. The remainder of the target radiance is chopped, reflected back onto the target, and recollected by the sensor as an AC signal. Two versions

M. J. Fordham; R. F. Gansman; F. Y. Sorrell

1993-01-01

154

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

155

REVIEW: Kinetics of the active media of high-pressure metal-vapor lasers  

Microsoft Academic Search

This paper reviews theoretical and experimental investigations of the active media of high-pressure lasers with active media consisting of mixtures of inert gases and the vapor of group-II metals. The active media are pumped by hard ionizing agents: electron or ion beams or charged products of nuclear reactions (nuclear pumping). The physical origins of limitations on the laser power and

A. V. Karelin; Sergei I. Yakovlenko

1993-01-01

156

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

E-print Network

H. Harveya... and Eric W. Lemmon Physical and Chemical Properties Division, National Institute for the Properties of Water and Steam IAPWS . The new formulation fits the available data within their scatter across Institute of Physics. Key words: D2O; heavy water; ITS-90; vapor pressure. Contents 1. Introduction

Magee, Joseph W.

157

Vapor pressures of some C/sub 4/ hydrocarbons and their mixtures  

SciTech Connect

A significant amount of new vapor pressure data has been determined on systems containing 1.3-butadiene, n-butane, trans-2-butene, and cls-2-butene. Integration of the binary Gibbs-Duhem equation gave relative volatilities with a probable error of no more than + or - 0.010 unit.

Flebbe, J.L.; Barclay, D.A.; Manley, D.B.

1982-10-01

158

Vapor pressures and thermodynamics of oxygen-containing polycyclic aromatic hydrocarbons measured using Knudsen effusion  

SciTech Connect

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 g/mol, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421 K. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, nonoxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of -CHO, -COOH, and -NO{sub 2} 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.

Goldfarb, J.L.; Suuberg, E.M. [Brown University, Providence, RI (United States). Division of Engineering

2008-06-15

159

Vapor pressures and evaporation coefficients for melts of ferromagnesian chondrule-like compositions  

E-print Network

Vapor pressures and evaporation coefficients for melts of ferromagnesian chondrule in revised form 17 August 2005 Abstract To determine evaporation coefficients for the major gaseous species that evaporate from silicate melts, the Hertz­Knudsen equation was used to model the compositions of residues

Grossman, Lawrence

160

Effect of reactor pressure on the electrical and structural properties of InN epilayers grown by high-pressure chemical vapor deposition  

E-print Network

to stoichiometric instabilities4,5 and a potential immiscibility for ternary InGaN alloys.6 In 1970, McChesney et al InGaN heterostructures, we explore in this study the growth of InN by high-pressure chemical vapor-pressure metalorganic chemical vapor deposition (MOCVD, also denoted as OMCVD, OMVPE or MOVPE) conditions

Perera, A. G. Unil

161

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

Code of Federal Regulations, 2010 CFR

...determine the maximum HAP vapor pressure of my remediation material...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...Standards for Hazardous Air Pollutants: Site Remediation...the maximum HAP vapor pressure of my remediation...

2010-07-01

162

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

Code of Federal Regulations, 2012 CFR

...determine the maximum HAP vapor pressure of my remediation material...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...Standards for Hazardous Air Pollutants: Site Remediation...the maximum HAP vapor pressure of my remediation...

2012-07-01

163

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

Code of Federal Regulations, 2011 CFR

...determine the maximum HAP vapor pressure of my remediation material...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...Standards for Hazardous Air Pollutants: Site Remediation...the maximum HAP vapor pressure of my remediation...

2011-07-01

164

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

Code of Federal Regulations, 2013 CFR

...determine the maximum HAP vapor pressure of my remediation material...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...Standards for Hazardous Air Pollutants: Site Remediation...the maximum HAP vapor pressure of my remediation...

2013-07-01

165

Surface tension, coexistence curve, and vapor pressure of binary liquid-gas mixtures  

NASA Astrophysics Data System (ADS)

The objective of this paper is to present measurements of the vapor pressure, capillary coefficient, and refractive index of four binary mixtures, CO2-SF6, R14-SF6, SF6-R13B1, and SF6-R22, at liquid-vapor equilibrium at different average concentrations. The measuring temperature range covered the entire liquid-vapor region from the triple line up to the critical point. The capillary coefficient was determined by means of the capillary rise method; the refractive index, by measuring the angle of refraction of a light beam passing through a prism and the sample. In order to obtain the liquid-vapor densities of pure substances the Lorentz-Lorenz relation can be used. However, in applying this relation to calculate the liquid-vapor densities of a mixture, one may need the concentrations of both the liquid and the vapor phase, which are, for the most part, quite different from the average concentration of the mixture. Calculating the concentrations of both fluid phases with the aid of an equation of state and comparing with measurements, we could show that the molar refraction coefficient of the mixtures can be simply determined from the average concentration and the molar refraction coefficients of their pure components. The surface tension of the mixtures could then be calculated from the measured capillary coefficient and the refractive index with the aid of the Lorentz-Lorenz relation.

Do, V. T.; Straub, J.

1986-01-01

166

Network model investigation of interfacial area, capillary pressure and saturation relationships in granular porous media  

NASA Astrophysics Data System (ADS)

We have developed a new approach for generating pore throat cross sections of various shapes based on distributions of shape factors and radii of inscribed circles. These distributions are obtained from analysis of grains packing. General formulas for calculating geometrical properties and entry capillary pressure for given shape factor and inscribed circle radius are developed. These relationships are employed in a pore network, which has a number of special features. In particular, it is highly flexible in terms of location of pore bodies, variable coordination number, as well as variable cross-sectional shapes. The pore network model is employed for simulating the equilibrium distribution of two fluids in a granular porous medium, under both drainage and imbibition conditions. The pore network model is verified by comparing simulation results with experimental data of quasi-static drainage and imbibition experiments in a glass bead medium. The pore-level topology and geometrical description of pore bodies and pore throats, essential for building the network, are rigorously extracted from experimental data using image analysis (3DMA-Rock software). Calculated capillary pressure-saturation (Pc - Sw) and specific interfacial area-saturation (anw - Sw) curves show very good agreement with measured ones, for both drainage and imbibition. We show that the shape factor can significantly influence the form of macroscopic Pc - Sw and anw - Sw curves, if the length and volumes associated to the pore throats are considerable. Furthermore, using continuous generation of shape factor distribution, the model can be validated against the grain size distribution. After validating the model against experiments, in addition to primary and main curves, we simulate many scanning curves to generate Pc - Sw - anw surfaces for drainage and imbibition, separately. Results show that these two surfaces lie very close to each other, and the average normalized difference is small, in the range of simulations uncertainty. Our results illustrate that Pc - Sw - anw surfaces show very little hysteresis and, therefore, specific interfacial area can be considered as an essential variable for reducing or eliminating the hysteresis observed in Pc - Sw curves.

Joekar-Niasar, V.; Prodanovi?, M.; Wildenschild, D.; Hassanizadeh, S. M.

2010-06-01

167

Advanced Computational Modeling of Vapor Deposition in a High-pressure Reactor  

NASA Technical Reports Server (NTRS)

In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

2004-01-01

168

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

169

Sildenafil Increases Systemic Saturation and Reduces Pulmonary Artery Pressure in Patients with Failing Fontan Physiology  

PubMed Central

Objective The purpose of this study was to investigate the effect of sildenafil in patients with failing Fontan physiology. Design A retrospective chart review was performed to compare history and available data in patients with Fontan circulations before and after starting sildenafil. The paired and unpaired Student’s t-tests were used for statistical analyses. Patients Six patients at our institution with Fontan physiology, persistent symptoms of cyanosis or effusion, and poor hemodynamics as measured in the catheterization laboratory were placed on sildenafil. One patient was not included in the analysis because of insufficient length of treatment. All patients had symptoms of failing Fontan hemodynamics with either persistent cyanosis or effusions. In this group, the mean pulmonary artery pressure was greater than 15 mm Hg (17.4 ± 1.5 mm Hg) with mean estimated pulmonary vascular resistance of 3.5 ± 1.0 Wood units × m2 prior to starting sildenafil. Results Sildenafil significantly increased the systemic arterial oxyhemoglobin saturation in this group (82.8 ± 7.3% pre-treatment vs. 91.0 ± 5.5% post-treatment, P = .017). In the four out of five patients who have had follow-up catheterizations, there was a significant decrease in pulmonary artery pressure (17.4 ± 1.5 mm Hg pre-treatment vs. 13.8 ± 2.1 mm Hg post-treatment, P = .018) and in estimated pulmonary vascular resistance pre- and post-sildenafil treatment (3.5 ± 1.0 Wood units × m2 pre-treatment vs. 2.0 ± 0.4 Wood units × m2 post-treatment, P = .031). Conclusions Sildenafil may be a useful adjunct to therapy in patients with failing Fontan physiology likely through its function as a pulmonary vasodilator. PMID:21866231

Morchi, Gira S.; Ivy, D. Dunbar; Duster, Mark C.; Claussen, Lori; Chan, Kak-Chen; Kay, Joseph

2011-01-01

170

Parameters of saturated absorption resonances of the /sup 192/OsO/sub 4/ molecule in the 28. 46 THz range at low pressures  

SciTech Connect

A high-pressure waveguide CO/sub 2/ laser was used to measure the impact broadening ..delta nu../sub r/0, saturation intensity I/sub sat/, and contrast of /sup 192/OsO/sub 4/ saturated absorption resonances in the 28.46 THz range. Values of these parameters in the pressure range p = 0.5--10 mTorr are given for both a traditional resonance due to a transition from an excited vibrational--rotational state and also for a higher-intensity resonance corresponding to the A/sup 2//sub 2/P(46) transition from the ground state. The parameters ..delta nu../sub r/0 and I/sub sat/ for both resonances are approximately the same in the pressure range under study and for p<1 mTorr they are ..delta nu../sub r/0 (p) = (30 +- 5)p kHz and I/sub sat/ (p) = (15 +- 3)p/sup m/ ..mu..W/cm/sup 2/, where 1vapor pressures in an external cell.

Bazarov, E.N.; Gerasimov, G.A.; Gubin, V.P.; Starostin, N.I.; Fomin, V.V.

1984-02-01

171

Spectral properties of molecular iodine absorption cells filled to saturation pressure  

NASA Astrophysics Data System (ADS)

The absorption cells - optical frequencies references - represent the crucial part of setups for practical realization of the meter unit - highly stable laser standards, where varied laser sources are frequency locked to the selected absorption transitions. Furthermore, not only in the most precise laboratory instruments, but also in less demanding interferometric measuring setups the frequency stabilization of the lasers throught the absorption in suitable media ensure the direct traceability to the fundamental standard of length. We present the results of measurement and evaluation of spectral properties of molecular iodine absorption cells filled to saturation pressure of absorption media. A set of cells filled with different amounts of molecular iodine was prepared and an agreement between expected and resulting spectral properties of these cells was observed and evaluated. The cells made of borosilicate glass instead of common fused silica were tested for their spectral properties in greater detail with special care for the absorption media purity - the measured hyperfine transitions linewidths were compared to cells traditionally made of fused silica glass with well known iodine purity. The usage of borosilicate glass material represents easier manufacturing process and also significant costs reduction but a great care must be taken to control/avoid the risk of absorption media contamination. An approach relying on measurement of linewidth of the hyperfine transitions is proposed and discussed.

Hrabina, Jan; Sarbort, Martin; Cip, Ondrej; Lazar, Josef

2014-05-01

172

A Functional Relationship Between Capillary Pressure, Saturation, and Interfacial Area as Revealed by a Pore-Scale Network Model  

Microsoft Academic Search

The constitutive relationships required for the parameterization of multiphase flow and transport problems are of critical importance to hydrologic modeling. Recently, a hypothesis has been developed that predicts a functional relationship between capillary pressure, saturation, and interfacial area. A network model was developed to test this hypothesis. Microscale physical processes were simulated and volume averaging was used to derive the

Paul C. Reeves; Michael A. Celia

1996-01-01

173

A functional relationship between capillary pressure, saturation, and interfacial area as revealed by a pore-scale network model  

Microsoft Academic Search

The constitutive relationships required for the parameterization of multiphase flow and transport problems are of critical importance to hydrologic modeling. Recently, a hypothesis has been developed that predicts a functional relationship between capillary pressure, saturation, and interfacial area. A network model was developed to test this hypothesis. Microscale physical processes were simulated and volume averaging was used to derive the

Paul C. Reeves; Michael A. Celia

1996-01-01

174

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false High and low vapor pressure protection for tankships-T...controlled; and (b) Has a high pressure and a low pressure alarm that...controlled; (2) Alarms at a high pressure of not more than 90...

2010-10-01

175

Vaporization of Uranium Mononitride and Heat of Sublimation of Uranium  

Microsoft Academic Search

The vaporization of uranium mononitride UN has been investigated by the Knudsen effusion technique in combination with a mass spectrometer. The vaporization occurs incongruently by preferential loss of nitrogen forming the two-phase system nitrogen-saturated liquid uranium–uranium-saturated nonstoichiometric uranium mononitride. The vapor pressures of U and N2 have been obtained by silver calibration over the two-phase system UN0.4&sngbnd;UN0.9 in the temperature

Karl A. Gingerich

1969-01-01

176

Investigations of analyte-specific response saturation and dynamic range limitations in atmospheric pressure ionization mass spectrometry.  

PubMed

With this study, we investigated why some small molecules demonstrate narrow dynamic ranges in electrospray ionization-mass spectrometry (ESI-MS) and sought to establish conditions under which the dynamic range could be extended. Working curves were compared for eight flavonoids and two alkaloids using ESI, atmospheric pressure chemical ionization (APCI), and heated electrospray ionization (HESI) sources. Relative to reserpine, the flavonoids exhibited narrower linear dynamic ranges with ESI-MS, primarily due to saturation in response at relatively low concentrations. Saturation was overcome by switching from ESI to APCI, and our experiments utilizing a combination HESI/APCI source suggest that this is due in part to the ability of APCI to protonate neutral quercetin molecules in the gas phase. Thermodynamic equilibrium calculations indicate that quercetin should be fully protonated in solution, and thus, it appears that some factor inherent in the ESI process favors the formation of neutral quercetin at high concentration. The flavonoid saturation concentration was increased with HESI as compared to ESI, suggesting that inefficient transfer of ions to the gas phase can also contribute to saturation in ESI-MS response. In support of this conclusion, increasing auxiliary gas pressure or switching to a more volatile spray solvent also increased the ESI dynamic range. Among the sources investigated herein, the HESI source achieved the best analytical performance (widest linear dynamic range, lowest LOD), but the APCI source was less subject to saturation in response at high concentration. PMID:25268329

Alfaro, Clint M; Uwakweh, Agbo-Oma; Todd, Daniel A; Ehrmann, Brandie M; Cech, Nadja B

2014-11-01

177

Outflow methods for evaluating the soil hydraulic functional relationships between NAPL pressure and saturation in porous media  

SciTech Connect

Remediation and cleanup of petroleum product contaminated ground water often require modeling of fluid transport processes when immiscible liquid phases are present. Modeling of such multiphase transport systems requires knowledge of the functional relationships between fluid pressures, saturations, and permeabilities. The authors evaluated the applicability of the multistep outflow method used in soil science to determine these functions for two porous media (loam and sand) using Soltrol 130 and water as wetting fluids. The analytical retention and permeability functions of van Genuchten and Mualem were used, with an inverse method that has been shown to be reliable in estimating water retention and unsaturated hydraulic conductivity in soils, to estimate soil hydraulic function parameters for Soltrol 130 and water. The water and Soltrol 130 cumulative drainage as a function of time and the equilibrium saturations were used as input to a numerical model (MLSTPM) to optimize, through an inverse solution of the Richards equation, the parameters needed for the hydraulic functions. Optimizations were carried out for saturation paths corresponding to monotonically decreasing wetting phase saturations only. The functional relationships between oil pressures, saturations, and permeabilities in Oso-Flaco fine sand were accurately predicted from the optimized water retention curve parameters based on scaling by the ratio of interfacial tensions. However, this scaling procedure was inadequate to predict oil hydraulic function parameters from those of water in Yolo loam.

Bali, K.M. [Univ. of California Desert Research and Extension Center, Holtville, CA (United States); Grismer, M.E.; Hopmans, J.W. [Univ. of California, Davis, CA (United States). Dept. of Land, Air, and Water Resources

1996-12-31

178

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

179

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

SciTech Connect

We describe Young{close_quote}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{sup {minus}8} to 10{sup {minus}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 ({lt}10) as for some saturated samples, relative excitations must be large in order to induce equivalent dry sample strains.{copyright} 1997 American Geophysical Union

Zinszner, B. [Institut Francais du Petrole, Rueil Malmaison (France)] [Institut Francais du Petrole, Rueil Malmaison (France); Johnson, P.A. [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico (United States)] [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); [Laboratoire dAcoustique Physique, Universite Pierre et Marie Curie, Paris; Rasolofosaon, P.N. [Institut Francais du Petrole, Rueil Malmaison (France)] [Institut Francais du Petrole, Rueil Malmaison (France)

1997-04-01

180

Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water  

NASA Astrophysics Data System (ADS)

report measurements of the vapor pressure of water over the supercooled temperature range 248 to 273 K derived from evaporation kinetics measurements of single water droplets. Accurate measurements of the relative humidity of the surrounding gas phase are derived from comparative and sequential measurements of the evaporation kinetics of droplets containing sodium chloride. The temperature dependence of the vapor pressure of supercooled water is shown to conform closely to the parameterization provided by Murphy and Koop (2005) once the uncertainties in experimental and thermophysical parameters are accounted for by ensuring an accurate representation of evaporation rates at temperatures above 273 K. Further, from a sensitivity analysis of all of the data over the full temperature range from 248 to 293 K, we can conclude that the evaporation coefficient of water, and thus the mass accommodation coefficient, is greater than, or equal to, 0.5.

Davies, James F.; Miles, Rachael E. H.; Haddrell, Allen E.; Reid, Jonathan P.

2014-09-01

181

Effect of H 2 ambient annealing on silicon nanowires prepared by atmospheric pressure chemical vapor deposition  

Microsoft Academic Search

We report the effect of H2 ambient annealing on the microstructure and vibrational properties of silicon nanowires (SiNWs) grown by atmospheric pressure chemical vapor depositions. The SiNWs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field-Emission Scanning Electron Microscopy (FESEM) and High-Resolution Transmission Electron Microscopy (HRTEM). The HRTEM study revealed that the thickness of oxide sheath surrounded by core silicon

Bhabani S. Swain; Sung S. Lee; Sang H. Lee; Bibhu P. Swain; Nong M. Hwang

2010-01-01

182

Generalization of vapor pressure lowering effects in an existing geothermal simulator  

Microsoft Academic Search

Thermodynamic properties of pore water are shown to be different from those of bulk water because of interfacial forces between the aqueous and solid phases. This {open_quotes}vapor-pressure lowering{close_quotes} (VPL) effect is described through Kelvin`s equation, which relates VPL to properties of the liquid phase. An algorithm that accounts for VPL had previously been implented in the geothermal simulator TETRAD. This

Shook

1993-01-01

183

Characterization of CuInS 2 films prepared by atmospheric pressure spray chemical vapor deposition  

Microsoft Academic Search

Copper indium disulfide films were deposited by atmospheric pressure spray chemical vapor deposition (CVD). Films were deposited at 390°C using [(PPh3)2CuIn(SEt)4] as a single source precursor in an argon atmosphere. The films range in thickness from 0.75 to 1.0 ?m and exhibit a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a

Jerry D. Harris; Kulbinder K. Banger; David A. Scheiman; Mark A. Smith; Michael H.-C. Jin; Aloysius F. Hepp

2003-01-01

184

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

185

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

186

Vapor pressures and enthalpies of sublimation of D-glucose, D-xylose, cellobiose, and levoglucosan  

SciTech Connect

The vapor pressures of {alpha}-D-glucose (or dextrose), D-xylose, D-cellobiose (or 4-{beta}-D-glucopyranosyl-D-glucopyranose), and levoglucosan (or 1,6-anhydro-{beta}-D-glucopyranose) have been measured using the Knudsen effusion technique, in the range of temperatures from 344 to 488 K. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Claperon equation. The vapor pressures may be correlated by ln(P/Pa) = A {minus} B/(T/K), where A = 53.16, B = 23.382 ({+-}600) for D-glucose (395--406 K), A = 46.29 and B = 19,006 ({+-} 375) for D-xylose (370--395 K), and A = 70.30 and B = 36,264 ({+-} 5,220) for cellobiose (474--488 K). Levoglucosan displayed a solid phase transition at approximately 386 K, and its vapor pressure was affected accordingly. For this material, A = 38.96 and B = 15,049 ({+-} 123) in the temperature range 344--386 K and A = 31.19 and B = 12,066 ({+-} 709) in the temperature range 386--405 K.

Oja, V.; Suuberg, E.M. [Brown Univ., Providence, RI (United States). Div. of Engineering] [Brown Univ., Providence, RI (United States). Div. of Engineering

1999-01-01

187

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 April 1994--30 June 1994  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars and (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to preparing the temperature measurement system for measurements of vapor pressure by the Knudsen effusion method. In the meantime, work has begun on preparing the system for producing the well-defined coal tar fractions that will ultimately be the subject of this study. The liquid chromatographic systems will be appropriate for this task. Anthracene and nonadecane were used to check the operation of the effusion apparatus. Fitting of the preliminary experimental data to the Clausius-Clapeyron equation was performed using the method of least squares. From these fits, the latent heats of evaporation or sublimation ({Delta}H{sub v}) could be approximately calculated. This report discusses results from the Knudsen method and tars production, collection, and molecular weight distribution.

Suuberg, E.M.; Oja, V.; Lilly, W.D.

1994-10-01

188

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 January 1996--31 March 1996  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude. Sophisticated general correlative approaches are slowly being developed, based upon group contribution methods, or based upon some key functional features of the molecules. These are as yet difficult to apply to coal tars. The detailed group contribution methods, in which fairly precise structural information is needed, do not lend themselves well for application to very complex, poorly characterized coal tars. The methods based upon more global types of characterizations have not yet dealt much with the question of oxygenated functional groups. In short, only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well- established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to developing techniques for measurements of vapor pressures of coal tar related compounds, and mixtures, in a ``continuous`` mode, using the effusion technique.

Suuberg, E.M.

1996-09-01

189

Measurements and Correlations of cis-1,3,3,3-Tetrafluoroprop-1-ene (R1234ze(Z)) Saturation Pressure  

NASA Astrophysics Data System (ADS)

cis-1,3,3,3-Tetrafluoroprop-1-ene (R1234ze(Z)) is being investigated as a working fluid possessing a low global warming potential (GWP) for high-temperature heat pumping applications, organic Rankine cycles, and air-conditioning and refrigeration applications, and as a potential solvent, propellant, and foam blowing agent. Its GWP is less than one. The open literature contains a total of 79 vapor-pressure data from three sources and the critical state properties from a single source. The current paper provides 64 vapor-pressure data from two different laboratories over the temperature range from 238.13 K to 372.61 K. These data are regressed using Wagner and extended Antoine vapor-pressure correlations and then compared to the existing open literature data and correlations. The normal-boiling-point temperature and acentric factor for R1234ze(Z) are estimated to be 282.73 K and 0.3257, respectively.

Fedele, Laura; Di Nicola, Giovanni; Brown, J. Steven; Bobbo, Sergio; Zilio, Claudio

2014-01-01

190

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

191

Insights into the Relationships Among Capillary Pressure, Saturation, Interfacial Area and Relative Permeability Using Pore-Network Modeling  

Microsoft Academic Search

To gain insight in relationships among capillary pressure, interfacial area, saturation, and relative permeability in two-phase\\u000a flow in porous media, we have developed two types of pore-network models. The first one, called tube model, has only one element\\u000a type, namely pore throats. The second one is a sphere-and-tube model with both pore bodies and pore throats. We have shown\\u000a that

V. Joekar-Niasar; S. M. Hassanizadeh; A. Leijnse

2008-01-01

192

Dynamic Oil-Water and Air-Water Capillary Pressure-Saturation Curves: Experiments and Lattice-Boltzmann Simulations  

NASA Astrophysics Data System (ADS)

Capillary pressure plays a significant role in multiphase flow and transport in porous media. Although capillary forces occur at the pore-scale, many mathematical models require a macro-scale relationship between capillary pressure and other properties of the system. The capillary pressure-saturation curve is the most widely used relationship to characterize hydraulic properties of multiphase flow in porous media. These curves are most commonly obtained from quasi-static drainage and imbibition experiments. It is then often assumed that the quasi-static curves can be applied to modeling transient flow conditions. In these models, the time it takes to reach a quasi-static state is completely ignored, which can be on the order of hours to months. Experimental evidence suggests that capillary pressure-saturation curves are not unique and that they exhibit dynamic effects depending on the flow conditions in the the system prior to and during the time of measurement. The extent to which dynamic flow conditions effect the measured capillary pressure is currently debated and the exact cause of the observed dynamic effects is not fully understood. In this study various drainage and imbibition experiments were conducted to further investigate the role dynamic effects play in the capillary pressure-saturation curve. Oil-water and air-water experiments were conducted on the same porous medium to compare the dynamic effects resulting from density and viscosity differences. Lattice-Boltzmann simulations of the dynamic effects were carried out to provide a comparison to the experimental results. The simulation results were then analyzed in an effort to identify the pore-scale mechanisms responsible for the dynamic effects observed in the macro-scale experiments.

Porter, M. L.; Schaap, M. G.; Wildenschild, D.

2006-12-01

193

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

194

Effects of ambient water vapor pressure and temperature on evaporative water loss in Peromyscus maniculatus and Mus musculus  

Microsoft Academic Search

Summary  The effects of ambient water vapor pressure (VP) and temperature on evaporative water loss (EWL) from the head and trunk ofPeromyscus maniculatus andMus musculus were measured with dew point hygrometry. At a given ambient temperature both head and trunk EWL were directly proportional to the water vapor pressure deficit. Cutaneous EWL in both species was directly related to the difference

Richard M. Edwards; Howard Haines

1978-01-01

195

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

196

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 April 1993--30 June 1993  

SciTech Connect

A significant amount of time has been devoted during this quarter to preparing the equipment for production of the tars to be measured, and preparing the equipment for measurements by the so-called Knudsen effusion method. This method will be summarized below. The various effusion methods are based on the effusion of the vaporized substance from a surface, or through an orifice [1]. One of these is the Knudsen method [2, 3], in which the substance effuses through small holes of known area. The principal applications of this method have been in the determination of the vapor pressure of metals such as mercury, cadmium, zinc and lead. It has however been equally effective for obtaining the vapor pressure of organic crystals and compounds [4, 5, 6, 7, 8, 99, 20]. The Knudsen method is used for the measurement of low vapor pressures in the range from 1 to 10{sup {minus}6} mm Hg under molecular flow conditions (pressures inside and outside cell are low enough for gas molecules make collisions only with the walls of the cell) and involves measurement of the rate of loss of molecules of the evaporating substance, leaving the opening of an effusion cell. Measurement are made under isothermal conditions, with weight loss being recorded as a function of time simultaneously with sample temperature, and with pressure measured outside the effusion cell. The basic theory of the effusion method was reviewed in the literature [2, 39, 12]. The basic theory of method is based upon the kinetic theory of gases, from which Knudsen derived an expression for the slow isothermal flow out of a cell with a small hole in it. According to Knudsen [1] the vapor pressure of a material in the cell can be calculated from his result, using the equation given.

Suuberg, E.M.

1993-11-01

197

Calculation of the vapor-saturated liquidus for the NaCl-CO2-H2O system  

USGS Publications Warehouse

The polybaric liquidus surface for the H2O-rich corner of the NaCl-CO2-H2O ternary is calculated, relying heavily on 1. (1) a Henry's law equation for CO2 in brines (modified from Drummond, 1981), 2. (2) the assumption that the contributions of dissolved NaCl and CO2 in lowering the activity of H2O are additive, and 3. (3) data on the CO2 clathrate solid solution (nominally CO2 ?? 7.3H2O, but ranging from 5.75 to 8 or 9 H2O) from Bozzo et al. (1975). The variation with composition of the activity of CO2??7.3H2O, or any other composition within the clathrate field, is small, thereby simplifying the calculations appreciably. Ternary invariant points are 1. (1) ternary eutectic at -21.5??C, with ice + clathrate + hydrohalite NaCl-??H2O + brine mNaCl = 5.15, mco2 = 0.22 + vapor Ptotal ??? Pco2 = 5.7 atm; 2. (2) peritectic at -9.6??C, with clathrate + hydrohalite + liquid CO2 + brine mNaCl = 5.18, mco2 = 0.55 + vapor (Ptotal ??? Pco2 = 26.47 atm); and 3. (3) peritectic slightly below +0.1 ??C, with halite + hydrohalite + liquid CO2 + brine (mNaCl ??? 5.5, mco2 ??? 0.64) + vapor (Ptotal ??? Pco2 ??? 34 atm). CO2 isobars have been contoured on the ternary liquidus and also on the 25??C isotherm. An important caveat regarding the application of this information to the interpretation of the freezing-thawing behavior of fluid inclusions is that metastable behavior is a common characteristic of the clathrate. ?? 1993.

Barton, P. B.; I-Ming, C.

1993-01-01

198

Resonance ionization spectroscopy measurement of the vapor pressure of several molecular species  

SciTech Connect

In recent years resonance ionization spectroscopy (RIS) has found increasing application to various problems involving detection of low levels of atomic, and more recently molecular, species. This work demonstrates the usefulness of RIS in measuring vapor pressure curves of molecular species at very low pressures. Specifically, the vapor pressures versus temperature relationship for rubidium iodide (RbI) and potassium iodide (KI) was measured by applying RIS to atomic Rb and K, using a two-laser system. A pulsed molecular nitrogen laser first dissociated the RbI to produce ground-state Rb atoms in the experimental cell. A flashlamp-pumped dye laser then ionized the Rb in a process wherein two photons of the same wavelength are absorbed, the first exciting Rb via an allowed transition to an upper state (5/sup 2/S/sub 1/2/ ..-->.. 6/sup 2//sub 1/2 or 3/2/) lying in energy slightly more than half the distance to the ionization limit, and the second photon ionizing the excited Rb. In the case of KI, an excimer-laser-pumped dye laser was used in a similar way. An applied dc electric field swept the photoelectrons to a proportional counter for subsequent amplification and detection. The photoelectron signal was then related back to RbI and KI concentrations.

Capelle, G.A.; Jessup, D.A.; Borella, H.M.; Franks, L.A.

1984-01-01

199

A systematic study of atmospheric pressure chemical vapor deposition growth of large-area monolayer graphene†  

PubMed Central

Graphene has attracted considerable interest as a potential material for future electronics. Although mechanical peel is known to produce high quality graphene flakes, practical applications require continuous graphene layers over a large area. The catalyst-assisted chemical vapor deposition (CVD) is a promising synthetic method to deliver wafer-sized graphene. Here we present a systematic study on the nucleation and growth of crystallized graphene domains in an atmospheric pressure chemical vapor deposition (APCVD) process. Parametric studies show that the mean size of the graphene domains increases with increasing growth temperature and CH4 partial pressure, while the density of domains decreases with increasing growth temperature and is independent of the CH4 partial pressure. Our studies show that nucleation of graphene domains on copper substrate is highly dependent on the initial annealing temperature. A two-step synthetic process with higher initial annealing temperature but lower growth temperature is developed to reduce domain density and achieve high quality full-surface coverage of monolayer graphene films. Electrical transport measurements demonstrate that the resulting graphene exhibits a high carrier mobility of up to 3000 cm2 V?1 s?1 at room temperature.

Liu, Lixin; Zhou, Hailong; Cheng, Rui; Chen, Yu; Lin, Yung-Chen; Qu, Yongquan; Bai, Jingwei; Ivanov, Ivan A.; Liu, Gang

2012-01-01

200

Correction factors for saturation effects in white light and laser absorption spectroscopy for application to low pressure plasmas  

SciTech Connect

In white light absorption spectroscopy, the broadening of the absorption signal due to the apparatus profile of the spectrometer may lead to an underestimation of the determined density as one measures an apparent optical depth. This is in particular true for high optical depth where saturation effects of the transmitted intensity occur. Provided that the line profile of the absorption line is known, the apparent optical depth effect can be accounted for by introducing a correction factor. The impact of the saturation and the approach of considering the effect are demonstrated for argon and indium lines in low pressure plasmas where correction factors of one order of magnitude or even higher are reached very easily. For the indium line, the hyperfine splitting has been taken into account. In laser absorption, the line profile is resolved. However, the weak but rather broad background emission of the laser diode can cause a saturation signal at the photo diode resulting also in an underestimation of the density obtained from the analysis. It is shown that this can be taken into account by fitting the theoretical line profile to the measured absorption signal which yields also a correction factor. The method is introduced and demonstrated at the example of the cesium resonance line including the hyperfine splitting. Typical correction factors around two are obtained for the cesium ground state density at conditions of a low pressure negative hydrogen ion source in which cesium is evaporated to enhance the negative ion production.

Briefi, S. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Wimmer, C.; Fantz, U. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2012-05-15

201

Vapor pressures and enthalpies of sublimation of polycyclic aromatic hydrocarbons and their derivatives  

SciTech Connect

The vapor pressures of a series of polycyclic aromatic hydrocarbons (PAH) and heteroatom-containing PAH have been measured using the Knudsen effusion technique. Aromatic hydrocarbons examined included anthracene, phenanthrene, pyrene, 2,3-benzofluorene, naphthacene, perylene, pentacene, and coronene. Heteroatomic aromatic species examined included phenanthridine, perinaphthenone, 3-hydroxy-1-phenalen-1-one, benz[g]isoquinoline-5,10-dione, 1,2-benzodiphenylene sulfide, 1-hydroxypyrene, and 6,11-dihydroxy-5,12-naphthacenedione. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Clapeyron equation.

Oja, V.; Suuberg, E.M. [Brown Univ., Providence, RI (United States). Div. of Engineering] [Brown Univ., Providence, RI (United States). Div. of Engineering

1998-05-01

202

Torsion vapor pressures and standard sublimation enthalpies of cobalt and nickel di-iodides  

SciTech Connect

The vapor pressures of CoI{sub 2} and NiI{sub 2} were measured by the torsion-effusion method. From second- and third-law treatments of the results, the standard sublimation enthalpies of both di-iodides were: {Delta}{sub m}H{sup o}(298) = 148 {+-} 1 and 158.0 {+-} 0.5 kJ/mol for CoI{sub 2} and NiI{sub 2}, respectively. From these values the corresponding enthalpies of formation were derived and compared with those reported in literature.

Brunetti, B.; Piacente, V.; Scardala, P. [Univ. degli Studi di Roma La Sapienza (Italy). Dipt. di Chimica

1996-06-01

203

Vapor Pressure of Solid Polybrominated Diphenyl Ethers Determined via Knudsen Effusion Method  

PubMed Central

Polybrominated diphenyl ethers (PBDEs) are flame retardants used in a variety of consumer products. The solid vapor pressures of BDE15 and BDE209 were determined by use of the Knudsen effusion method, and the values measured extrapolated to 298.15 K are 3.12×10?3 and 9.02×10?13 Pa, respectively. The enthalpies of sublimation for these compounds have also been estimated by using the Clausius-Clapeyron equation and are 102.0 ± 3.5 and 157.1 ± 3.5 kJ/mol, respectively. Additionally, the melting points and enthalpies of fusion were measured by differential scanning calorimetry. PMID:21766320

Fu, Jinxia; Suuberg, Eric M.

2013-01-01

204

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

205

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

206

Effects of dissolved air on subcooled and saturated flow boiling of water in a small diameter tube at low pressure  

SciTech Connect

Experimental results on flow boiling of air saturated water flowing through a tube of inner diameter d{sub i} = 4.03 mm are presented. Both subcooled and saturated flow boiling are investigated, covering pressures from 177 to 519 kPa, mass fluxes from 478 to 839 kg m{sup -2} s{sup -1} and heat fluxes from 210 to 736 kW m{sup -2}. By comparing the measured results with existing prediction methods derived for degassed liquids the study concludes that the presence of dissolved air in the testing fluid can be regarded as a second order effect, and no special attention to dissolved air appears required. (author)

Cioncolini, Andrea; Santini, Lorenzo; Ricotti, Marco E. [Department of Nuclear Engineering, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy)

2007-10-15

207

Comparison of height-averaged and point-measured capillary pressure-saturation relations for sands using a modified Tempe cell  

NASA Astrophysics Data System (ADS)

Tempe cells and similar devices are often used for measurements of capillary pressure versus saturation relationships (retention curves) of soils. Average water saturation within the sample is often used as the representative saturation. For cases where the saturation distribution along the cell height is nonuniform, use of the height-averaged water saturation artificially smoothes the retention curve when the capillary pressure head reaches the displacement pressure head. This leads to an inaccurate representation of the retention curve in flow modeling. For nine test sands with a wide range of displacement pressure head values (6-78 cm of water), height-averaged and point-measured retention curves were simultaneously obtained to investigate the effect of the height-averaging procedure. A Tempe cell was used, which was modified by installing a small time domain reflectometry probe and a tensiometer at the midpoint of the sample height to measure water saturation and pressure, respectively. When the sample height is large relative to the displacement pressure head, the bulk drainage (initial drainage at the top of the sample) leads to inaccuracies in the determination of retention curves. For such cases, point-measured saturation should be used, otherwise height correction is necessary.

Sakaki, Toshihiro; Illangasekare, Tissa H.

2007-12-01

208

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 October 1993--31 December 1993  

SciTech Connect

The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. Sophisticated general correlative approaches are slowly being developed, based upon group contribution methods, or based upon some key functional features of the molecules. These are as yet difficult to apply to coal tars. The detailed group contribution methods, in which fairly precise structural information is needed, do not lend themselves well for application to very complex, poorly characterized coal tars. The methods based upon more global types of characterizations have not yet dealt much with the question of oxygenated functional groups. In short, only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion.

Suuberg, E.M.

1993-12-31

209

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 July 1993--30 September 1993  

SciTech Connect

There is significant current interest in general area of coal pyrolysis, particularly with respect to comprehensive models of this complicated phenomenon. This interest derives from the central role of pyrolysis in all thermally driven coal conversion processes -- gasification, combustion, liquefaction, mild gasification, or thermal benefication. There remain several key data needs in these application areas. Among them is a need for more reliable correlation for prediction of vapor pressure of heavy, primary coal tars. Such information is important in design of all coal conversion processes, in which the volatility of tarry products is of major concern. Only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. Results of the literature survey are compiled. The experimental tasks have been concerned with setup and calibration.

Suuberg, E.M.; Oja, V.; Lilly, W.D.

1993-12-31

210

The Vapor Pressure of 1-(2,2,3,3-Tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-prop anol  

SciTech Connect

The vapor pressure of the compound 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol was measured over the temperature range 62 to 92 C using a Knudsen effusion technique. This compound, known as Cs-7SB, is the modifier component in the caustic-side solvent extraction process solvent. The vapor pressure is related to temperature by the equation ln(p/Pa) = (32.202 {+-} 0.265) - (12154 {+-} 93)/T, where p is the pressure, expressed in pascals; Pa is the reference pressure of 1 pascal; and T is the temperature, expressed in degrees kelvin. The derived heat of vaporization is 101.1 {+-} 0.8{sup kJ{center_dot}mol{sup 1} at 351 K. Because the vapor pressures over the temperature range of 15 to 50 C were lower than the design capabilities of the Knudsen effusion apparatus, the vapor pressures at these temperature limits were obtained by extrapolation. The estimated values are 4.6 {+-} 0.3E-05 (3.5 {+-} 0.2E-07 mm Hg) and 4.5 {+-} 0.1E-03 Pa (3.4 {+-} 0.1E-05 mm Hg) for 15 C and 50 C, respectively.

Steele, W.V.

2002-01-29

211

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 � Y. Y. Yang � H. N. G. Wadley Published online: 31 January 2009 � Springer Science+Business Media, LLC 2009 Abstract and molecular fluxes have created an interest in the atomic assembly of thin films under high pressure (10­ 500

Wadley, Haydn

212

Vapor pressure scanning of oxygen nonstoichiometry in YBa{sub 2}Cu{sub 3}O{sub y}  

SciTech Connect

Oxygen nonstoichiometry in high-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub y} was studied by vapor pressure measurements in a closed volume in the temperature range 673 to 1173 K and oxygen pressure up to 1 atm. P-T-X phase relationships were derived from the vapor pressure scanning of the solidus surface. Analytical representation of isothermal, isobaric, and isoplethal (X{sub s} = const) sections of the P-T-X diagram is given. Partial thermodynamic functions of oxygen were calculated in the oxygen nonstoichiometry range 6.30 to 6.85.

Guskov, V.N.; Tarasov, I.V.; Lazarev, V.B. [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation)] [and others] [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); and others

1995-10-01

213

High Vapor Pressure Perfluorocarbons Cause Vesicle Fusion and Changes in Membrane Packing  

PubMed Central

Perfluorocarbons (PFCs) hold great promise for biomedical applications. However, relatively little is known about the impact of these chemicals on membranes. We used unilamellar vesicles to explore the effects of PFCs on membrane packing and vesicle stability. Four clinically relevant PFCs with varying vapor pressures (PP1, 294 mbar; PP2, 141 mbar; PP4, 9.6 mbar; and PP9, 2.9 mbar) were examined. Microscopy imaging and spectroscopic measurements suggest that PFCs, especially those with high vapor pressures, lead to vesicle fusion within hours. Upon exposure to PP1 and PP2 for 72 h, vesicles retained a spherical shape, but the size changed from ?200 nm to ?20–40 ?m. In addition, membrane packing underwent marked changes during this timeframe. A significant decrease in water content in the lipid polar headgroup regions occurred during the first 1–2-h exposure to PFCs, followed by a steady increase in water content over time. Possible mechanisms were proposed to explain these dramatic structural changes. The finding that chemically inert PFCs exhibited fusogenic activity and marked changes in membrane surface packing is novel, and should be considered when using PFCs for biomedical applications. PMID:18689464

Venegas, Berenice; Wolfson, Marla R.; Cooke, Peter H.; Chong, Parkson Lee-Gau

2008-01-01

214

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

215

D0 Silicon Upgrade: Vapor Pressure Thermometry System Near LN2 Subcooler  

SciTech Connect

Fermi National Accelerator Laboratory (Fermilab) is in the process of upgrading its detectors. Among these upgrades is the need for more transfer lines containing both liquid nitrogen and helium gas. These two fluids are used to provide the necessary operating cryogenic temperatures for the various detectors, such as the Visible Light Photon Counter (VLPC) and the solenoid inside the detector's calorimeter. With additional piping, it is important to monitor the temperatures to assure that the detectors can operate correctly. This can be done two ways. The first method is to use a Resistance Temperature Device, called a RTD, which is made using either a carbon resistor or a platinum resistor and measures the temperature based on resistance. The second method is to use a vapor-pressure thermometry system. This design will focus on the second method. A nitrogen Vapor Pressure Thermometer (VPT) system is designed to determine the temperature of the liquid nitrogen (LN{sub 2}) supply line, after exiting the LN{sub 2} subcooler, inside the D-Zero Assembly Hall. The operating temperature range is designed from 77 to 300 Kelvin with an initial charge pressure of 100 psia. A cylindrical bulb with a 0.1875-inch diameter and 0.625-inch length allows for minimum cold and warm 1/4-inch O.D. SS 304L tubing lengths, 12-inch and 18-inch respectively, and maintains a liquid level of 50% inside the bulb during cold operation. The amount of nitrogen needed to fill the cylindrical bulb approximately half full is 0.149 grams. In order to conform to the conventional cold volume and warm volume VPT systems, we need to enlarge the existing 1/2-inch x 2-inch SCH. 10 LN{sub 2} supply line over a one foot section to 1-inch x 3-inch SCH. 10 piping.

Kuwazaki, Andrew; /Fermilab

1996-07-01

216

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

217

Fracturing processes due to temperature and pressure nonlinear waves propagating in fluid-saturated porous rocks  

NASA Astrophysics Data System (ADS)

A model is proposed of rock deformation-fracturing in the subsurface of hydrothermal systems in response to deep fluid-rock temperature and pore fluid pressure perturbations, carried upward by hot and pressurized fluid fronts. Since during these episodes of unrest one also has to take into account that rock parameters can evolve, a model of fluid diffusivity change as a function of pore fluid pressure is described. Through reformulating the linear thermoporoelastic equations, rock deformation-fracturing is thus thought of as being associated with migration of thermomechanical nonlinear waves, which travel upward, associated with an increase in concurrent fluid diffusivity. On dynamical grounds it is assumed that on the boundary of the two superimposed horizons the overlying rock suddenly starts rupturing, caused by the arrival of supercritical water from below, which drives up a pore fluid pressure excess. In this connection, the purpose of this analysis is to investigate the general evolution of the subsurface pressure and temperature fields, assuming that the original signal is itself strong enough to generate fracturing processes of the overburden rock on its arrival. A general formulation provides evidence of nonlinear "thermal waves," "compensated waves," and "residual pressure Burgers waves," that can be found for every value of the system parameters. A mechanical analogy is also presented, which is treated analytically and numerically, allowing one to gain intuitive insight into such complex phenomena. A characteristic of these nonlinear processes is that the resulting timescales (of the order of years for the case of the Campi Flegrei and the Izu Peninsula) can be particularly small, corresponding to quick hyperthermal phenomena during the filtrating movement of fluid toward the Earth's surface.

Merlani, Antonio Luigi; Natale, Giuseppe; Salusti, Ettore

2001-06-01

218

A study of capillary pressure in a partly saturated quartz powder  

E-print Network

'ollows: U c = U - U w s Equation (2) From Equations (1) and (2) it foU. ows that the reduction in pressure across the air-vater meniscus increases as the radius of the meniscus decreases. Therefore, for a given soil with unchanging void size...'ollows: U c = U - U w s Equation (2) From Equations (1) and (2) it foU. ows that the reduction in pressure across the air-vater meniscus increases as the radius of the meniscus decreases. Therefore, for a given soil with unchanging void size...

Burke, Jack Willard, Jr

2012-06-07

219

Pressure ulcer management in home health care: efficacy and cost effectiveness of moisture vapor permeable dressing.  

PubMed

This prospective randomized study was conducted in the home care setting to compare healing rates and costs of two different dressings for pressure ulcers: the gauze and tape dressing and the transparent moisture vapor permeable dressing (MVP). Demographic variables, healing rates, and cost of treatment were statistically analyzed for 77 pressure ulcers (48 patients). Each wound was randomly assigned to either a gauze dressing or a MVP dressing. Initial ulcer grade (Shea criteria) and measurements were determined at the start of treatment and weekly for an eight-week period. Photographs of the wound were taken at the beginning and end of treatment. The same protocol for irrigating the wound and relieving pressure was followed for both dressing groups. The median improvement for the grade II group was 100% for the MVP (n = 22) and 52% for gauze (n = 12), p less than 0.05 (Wilcoxon rank sum test). The healing rates for grade III ulcers were not significantly different in the two dressing groups. The mean (eight-week) labor and supply cost per ulcer using the MVP was $845, while that for gauze treatments was $1359, p less than 0.05 (Wilcoxon rank sum test). The cost difference for grade III ulcers was not significant in the two dressing groups. The MVP improved the healing rate and was more cost effective for grade II ulcers. Both gauze and MVP dressings proved effective for the treatment of grade III ulcers. PMID:3533007

Sebern, M D

1986-10-01

220

Vapor pressure and boiling point elevation of slash pine black liquors: Predictive models with statistical approach  

SciTech Connect

Vapor-liquid equilibria and boiling point elevation of slash pine kraft black liquors over a wide range of solid concentrations (up to 85% solids) has been studied. The liquors are from a statistically designed pulping experiment for pulping slash pine in a pilot scale digester with four cooking variables of effective alkali, sulfidity, cooking time, and cooking temperature. It was found that boiling point elevation of black liquors is pressure dependent, and this dependency is more significant at higher solids concentrations. The boiling point elevation data at different solids contents (at a fixed pressure) were correlated to the dissolved solids (S/(1 {minus} S)) in black liquor. Due to the solubility limit of some of the salts in black liquor, a change in the slope of the boiling point elevation as a function of the dissolved solids was observed at a concentration of around 65% solids. An empirical method was developed to describe the boiling point elevation of each liquor as a function of pressure and solids mass fraction. The boiling point elevation of slash pine black liquors was correlated quantitatively to the pulping variables, using different statistical procedures. These predictive models can be applied to determine the boiling point rise (and boiling point) of slash pine black liquors at processing conditions from the knowledge of pulping variables. The results are presented, and their utility is discussed.

Zaman, A.A.; McNally, T.W.; Fricke, A.L. [Univ. of Florida, Gainesville, FL (United States)] [Univ. of Florida, Gainesville, FL (United States)

1998-01-01

221

Network model investigation of interfacial area, capillary pressure and saturation relationships in granular porous media  

Microsoft Academic Search

We have developed a new approach for generating pore throat cross sections of various shapes based on distributions of shape factors and radii of inscribed circles. These distributions are obtained from analysis of grains packing. General formulas for calculating geometrical properties and entry capillary pressure for given shape factor and inscribed circle radius are developed. These relationships are employed in

V. Joekar-Niasar; M. Prodanovi?; D. Wildenschild; S. M. Hassanizadeh

2010-01-01

222

Preparation of zinc oxide films by low-pressure chemical vapor deposition method  

SciTech Connect

ZnO and Al-doped ZnO films prepared using a low-pressure chemical vapor deposition (LP-CVD) method were studied. The films were prepared on fused quartz substrates using bis (2,4-pentanedionato) zinc and tris (2,4-pentanedionato) aluminum which are inexpensive and stable source materials. The highly c-axis oriented ZnO films were grown on the substrates above 500 C. The minimum electrical resistivity of {rho} = 6.5 {times} 10{sup {minus}5} {Omega}m was obtained for the ZnO film, and of {rho} = 3.5 {times} 10{sup {minus}5} {Omega}m was obtained for the ZnO:Al film.

Nishino, Junichi; Ohshio, Shigeo; Kamata, Kiichiro [Nagaoka Univ. of Technology, Niigata (Japan). Dept. of Chemistry

1995-08-01

223

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

SciTech Connect

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

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

1994-08-01

224

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

225

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

226

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

227

Analysis of mass transport in an atmospheric pressure remote plasma-enhanced chemical vapor deposition process  

SciTech Connect

In remote microwave plasma enhanced chemical vapor deposition processes operated at atmospheric pressure, high deposition rates are associated with the localization of precursors on the treated surface. We show that mass transport can be advantageously ensured by convection for the heavier precursor, the lighter being driven by turbulent diffusion toward the surface. Transport by laminar diffusion is negligible. The use of high flow rates is mandatory to have a good mixing of species. The use of an injection nozzle with micrometer-sized hole enables us to define accurately the reaction area between the reactive species. The localization of the flow leads to high deposition rates by confining the reactive species over a small area, the deposition yield being therefore very high. Increasing the temperature modifies nonlinearly the deposition rates and the coating properties.

Cardoso, R. P.; Belmonte, T.; Henrion, G.; Gries, T. [Department of Chemistry and Physics of Solids and Surfaces, Institut Jean Lamour, Nancy-Universite, CNRS, Parc de Saurupt, CS 14234, F-54042 Nancy Cedex (France); Tixhon, E. [AGC Flat Coating, 2 Rue de l'aurore, B-6040 Jumet (Belgium)

2010-01-15

228

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

229

Modeling Conditional Stability of Gravity-Driven Unsaturated Infiltrating Flows Using a Non-equilibrium Capillary Pressure-Saturation Relation  

NASA Astrophysics Data System (ADS)

Gravity-driven unstable flow during infiltration in unsaturated porous media is considered to be an important preferential flow process. The conventional equation for modeling unsaturated flows is the Richards equation, but this equation cannot be used to model unstable flows as it has been shown (A.G. Egorov, R.Z. Dautov, J.L. Nieber, and A.Y. Sheshukov, 2003. Stability analysis of gravity-assisted infiltrating flow, Water Resour. Res., 39:,1266, doi:10.1029/2002WR001886) that solutions to the Richards equations are unconditionally stable. Therefore, modeling these unstable flows requires the use of new forms of the mass balance equation which contain features that might account for the cause of instabilities. One postulated cause for instabilities is the existence of non-equilibrium in the capillary pressure-saturation relation. In this presentation we will examine the conditional stability that results from the use of a non-equilibrium relation of the form ? (S,p){? S}/{? t}=p-P(S), where ? is the relaxation coefficient, S is the saturation, p is the dynamic pressure, and P(S) is the equilibrium pressure. The stability analysis is based on the perturbation of the traveling wave form of the governing mass balance equation and the associated relaxation equation. The numerical determination of the eigenvalues of the resulting perturbation equations yields the critical growth factor as related to perturbation frequency. The derived critical growth factor is used in evaluating the conditional stability as to its sensitivity to the flux and magnitude of the relaxation coefficient. It is interesting to see that as ? (S,p)-> 0 the flow becomes unconditionally stable, the result being that found for the Richards equation. The perturbation frequency associated with the critical growth factor is related to finger width and this is confirmed with simulations in the two-dimensional vertical plane.

Dautov, R. Z.; Egorov, A. G.; Nieber, J. L.; Sheshukov, A. Y.

2004-12-01

230

A study of capillary pressure in a partly saturated feldspar powder  

E-print Network

the suction inside the probe until the soil ceases to draw water from it. A soil suction versus moisture content relationship may be developed by using several initial soil moisture contents. This is a wetting method and is suitable for suctions up... equilibrium. The suction in the plate, and hence. the vapour pressure in the enclosure, may be controlled by using a vacuum pump and associated manometer (see Figure 2'-3). The centrifu e method This method may be used to measure soil suction up...

Turner, Dennis Marshall

2012-06-07

231

A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space  

NASA Astrophysics Data System (ADS)

This study presents a new model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for accurate prediction of spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and nonwetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity for void space to compute the hysteretic curves and to predict entrapped fluid-phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3-D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, Abdullah; Birkholzer, Jens; Illangasekare, Tissa H.; Zhou, Quanlin

2014-01-01

232

A Theoretical Approach Representing Hysteresis in Capillary Pressure-Saturation Relationship Based on Connectivity in Void Space  

NASA Astrophysics Data System (ADS)

This study presents a new theoretical model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for the accurate prediction of the spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, the connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity of void space to compute the hysteretic curves and to predict entrapped fluid phase saturations. Two functions, the probability of drainage and the probability of wetting, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, A.; Birkholzer, J. T.; Illangasekare, T. H.; Zhou, Q.

2013-12-01

233

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

234

Prediction of spatially distributed regional-scale fields of air temperature and vapor pressure over mountain glaciers  

Microsoft Academic Search

Physically based models of glacier melt require fields of near-surface air temperature (Tg) and vapor pressure (eg) for estimating turbulent heat exchanges. However, katabatic boundary layer (KBL) processes limit the effectiveness of standard interpolation or extrapolation routines for estimating Tg and eg from regional weather station networks. Climate data collected from nine automatic weather stations operated over three ablation seasons

J. M. Shea; R. D. Moore

2010-01-01

235

Odor vapor pressure and quality modulate local field potential oscillatory patterns in the olfactory bulb of the  

E-print Network

Odor vapor pressure and quality modulate local field potential oscillatory patterns in the olfactory bulb of the anesthetized rat Tristan Cenier,1 Corine Amat,1 Philippe Litaudon,1 Samuel Garcia,1 Laboratoire de Physique, Ecole Normale Supe´rieure de Lyon, Lyon, France Keywords: coding, local field

Roux, Stephane

236

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

237

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

238

COMPUTATIONAL CHEMISTRY METHOD FOR PREDICTING VAPOR PRESSURES AND ACTIVITY COEFFICIENTS OF POLAR ORGANIC OXYGENATES IN PM2.5  

EPA Science Inventory

Parameterizations of interactions of polar multifunctional organic oxygenates in PM2.5 must be included in aerosol chemistry models for evaluating control strategies for reducing ambient concentrations of PM2.5 compounds. Vapor pressures and activity coefficients of these compo...

239

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

240

Transport of Carbon Tetrachloride in a Fractured Vadose Zone due to Atmospheric Pressure Fluctuations, Diffusion, and Vapor Density  

NASA Astrophysics Data System (ADS)

DNAPL sources of carbon tetrachloride (CT) vapors are of interest at the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering and Environmental Laboratory (INEEL). The site is underlain by thick fractured basalt that includes sedimentary interbeds, each are a few meters thick. Daily atmospheric pressure fluctuations serve as driving forces for CT vapor transport in the subsurface. Other important transport processes for vapor movement include gas-phase diffusion and density-driven transport. The objective of this research is to investigate the influence and relative importance of these processes on gaseous transport of CT. Gas pressure and vapor concentration measurements were conducted at various depths in two wells. A numerical multiphase flow model (TOUGH2), calibrated to field pressure data, is used to conduct sensitivity analyses to elucidate the importance of the different transport mechanisms. Results show that the basalt is highly permeable to vertical air flow. The pressure dampening occurs mainly in the sedimentary interbeds. Model-calibrated permeability values for the interbeds are similar to those obtained in a study by the U.S. Geological Survey for shallow sediments, and an order of magnitude higher than column-scale values obtained by previous studies conducted by INEEL scientists. The transport simulations indicate that considering the effect of barometric pressure changes is critical to simulating transport of pollutants in the vadose zone above the DNAPL source. Predicted concentrations can be orders of magnitude smaller than actual concentrations if the effect is not considered. Below the DNAPL vapor source, accounting for density and diffusion alone would yield acceptable results provided that a 20% error in concentrations are acceptable, and that simulating concentrations trends (and not actual concentrations) is the primary goal.

McCray, J. E.; Downs, W.; Falta, R. W.; Housley, T.

2005-12-01

241

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

242

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

243

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

244

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

245

The effect of vapor pressure deficit on water use efficiency at the subdaily time scale  

NASA Astrophysics Data System (ADS)

use efficiency is a critical index for describing carbon-water coupling in terrestrial ecosystems. However, the nonlinear effect of vapor pressure deficit (VPD) on carbon-water coupling has not been fully considered. To improve the relationship between gross primary production (GPP) and evapotranspiration (ET) at the subdaily time scale, we propose a new underlying water use efficiency (uWUE = GPP · VPD0.5/ET) and a hysteresis model to minimize time lags among GPP, ET, and VPD. Half-hourly data were used to validate uWUE for seven vegetation types from 42 AmeriFlux sites. Correlation analysis shows that the GPP · VPD0.5 and ET relationship (r = 0.844) is better than that between GPP · VPD and ET (r = 0.802). The hysteresis model supports the GPP · VPD0.5 and ET relationship. As uWUE is related to CO2 concentration, its use can improve estimates of GPP and ET and help understand the effect of CO2 fertilization on carbon storage and water loss.

Zhou, Sha; Yu, Bofu; Huang, Yuefei; Wang, Guangqian

2014-07-01

246

Characteristics of low vapor pressure oil ignition developed with irradiation of mega hertz level ultrasonic  

Microsoft Academic Search

In liquid fuel vaporizing type combustor for civil use, large amount of the electric power is consumed in pre-heating of fuel vaporizer during a standby period. Reduction of consumed power in pre-heating is regarded as important to develop a performance of the vaporizing type combustor from the viewpoint of energy saving. We proposed the oil combustion system using the MHz-ultrasonic

Takuya Fuse; Yasuki Hirota; Noriyuki Kobayashi; Masanobu Hasatani; Yoshio Tanaka

2004-01-01

247

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

248

Reversibility of Water Vapor Sorption by Cottage Cheese Whey Solids  

Microsoft Academic Search

Desorption isotherms for water vapor from cottage cheese whey so,lids vary with the way water is first sorbed by the whey solids. When water is sorbed progressively in small increments be- tween zero pressure and saturation pres- sure, the powder becomes 'more porous during lactose crystallization. Subsequent desorption data follow a sigmoid pattern as a function of relative pressure. More

B. A. Anderson

1975-01-01

249

Vapor pressures and evaporation coefficients for melts of ferromagnesian chondrule-like compositions  

NASA Astrophysics Data System (ADS)

To determine evaporation coefficients for the major gaseous species that evaporate from silicate melts, the Hertz-Knudsen equation was used to model the compositions of residues of chondrule analogs produced by evaporation in vacuum by Hashimoto [Hashimoto A. (1983) Evaporation metamorphism in the early solar nebula-evaporation experiments on the melt FeO-MgO-SiO 2-CaO-Al 2O 3 and chemical fractionations of primitive materials. Geochem. J. 17, 111-145] and Wang et al. [Wang J., Davis A. M., Clayton R. N., Mayeda T. K., Hashimoto A. (2001) Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO 2-CaO-Al 2O 3-TiO 2 rare earth element melt system. Geochim. Cosmochim. Acta 65, 479-494], in vacuum and in H 2 by Yu et al. [Yu Y., Hewins R. H., Alexander C. M. O'D., Wang J. (2003) Experimental study of evaporation and isotopic mass fractionation of potassium in silicate melts. Geochim. Cosmochim. Acta 67, 773-786], and in H 2 by Cohen et al. [Cohen B. A., Hewins R. H., Alexander C. M. O'D. (2004) The formation of chondrules by open-system melting of nebular condensates. Geochim. Cosmochim. Acta 68, 1661-1675]. Vapor pressures were calculated using the thermodynamic model of Ghiorso and Sack [Ghiorso M. S., Sack R. O. (1995) Chemical mass transfer in magmatic processes IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures. Contrib. Mineral. Petrol. 119, 197-212], except for the late, FeO-free stages of the Wang et al. (2001) and Cohen et al. (2004) experiments, where the CMAS activity model of Berman [Berman R. G. (1983) A thermodynamic model for multicomponent melts, with application to the system CaO-MgO-Al 2O 3-SiO 2. Ph.D. thesis, University of British Columbia] was used. From these vapor pressures, evaporation coefficients ( ?) were obtained that give the best fits to the time variation of the residue compositions. Evaporation coefficients derived for Fe (g), Mg (g), and SiO (g) from the Hashimoto (1983) experiments are similar to those found by Alexander [Alexander C. M. O'D. (2004) Erratum. Meteoritics Planet. Sci. 39, 163] in his EQR treatment of the same data and also adequately describe the FeO-bearing stages of the Wang et al. (2001) experiments. From the Yu et al. (2003) experiments at 1723 K, ?Na = 0.26 ± 0.05, and ?K = 0.13 ± 0.02 in vacuum, and ?Na = 0.042 ± 0.020, and ?K = 0.017 ± 0.002 in 9 × 10 -5 bar H 2. In the FeO-free stages of the Wang et al. (2001) experiments, ?Mg and ?SiO are significantly different from their respective values in the FeO-bearing portions of the same experiments and from the vacuum values obtained at the same temperature by Richter [Richter F. M., Davis A. M., Ebel D. S., Hashimoto A. (2002) Elemental and isotopic fractionation of Type B calcium-, aluminum-rich inclusions: experiments, theoretical considerations, and constraints on their thermal evolution. Geochim. Cosmochim. Acta 66, 521-540] for CMAS compositions much lower in MgO. When corrected for temperature, the values of ?Mg and ?SiO that best describe the FeO-free stages of the Wang et al. (2001) experiments also adequately describe the FeO-free stage of the Cohen et al. (2004) H 2 experiments, but ?Fe that best describes the FeO-bearing stage of the latter experiment differs significantly from the temperature-corrected value derived from the Hashimoto (1983) vacuum data.

Fedkin, A. V.; Grossman, L.; Ghiorso, M. S.

2006-01-01

250

Mechanistic study of borosilicate glass growth by low-pressure chemical vapor deposition from tetraethylorthosilicate and trimethylborate  

Microsoft Academic Search

A reaction mechanism and film morphology as a function of reactor conditions and post growth thermal annealing for borosilicate\\u000a glass (BSG), (SiO2)x(B2O3)1?x, films deposited from tetraethylorthosilicate (TEOS), trimethylborate (TMB), and oxygen (O2) precursors by low-pressure chemical vapor deposition (LPCVD) was determined. An empirically derived reaction model for BSG\\u000a film growth is proposed that predicts the growth rate and composition of

D. M. Hansen; D. Charters; Y. L. Au; W. K. Mak; W. Tejasukmana; P. D. Moran; T. F. Kuech

2000-01-01

251

Visualization and numerical simulation of fine particle transport in a low-pressure parallel plate chemical vapor deposition reactor  

Microsoft Academic Search

The behavior of fine particles in a low-pressure parallel plate chemical vapor deposition reactor was investigated by constructing a system that permits particle motion in the reactor to be visualized. The test spherical silica aerosol particles, which were 1.0?m in diameter and dispersed in argon gas, were fed into the reactor from the outside and particle motion was detected by

Heru Setyawan; Manabu Shimada; Kenji Ohtsuka; Kikuo Okuyama

2002-01-01

252

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

253

Whole field vapor pressure modeling of QFN during reflow with coupled hygro-mechanical and thermo-mechanical stresses  

Microsoft Academic Search

A comprehensive and integrated package stress model is established for QFN (Quad Flat Non-lead) packages with consideration of the effects of moisture diffusion, heat transfer, thermo-mechanical stress, hygro-mechanical stress, and vapor pressure induced during reflow. The critical plastic materials, i.e. mold compound and die attach, are characterized for hygroswelling and moisture properties. The moisture absorption during preconditioning at JEDEC Level

Tong Yan Tee; Hun Shen Ng

2002-01-01

254

Pressure-pulsed chemical vapor infiltration of pyrolytic carbon into fibrous tin prepared from carbonized paper preform  

Microsoft Academic Search

The plate-type negative electrodes for Li-ion rechargeable battery were prepared by pressure-pulsed chemical vapor infiltration of pyrolytic carbon at 950°C from C 3 H 8 (30%)-H 2 into the TiN-based electroconductive forms having the fibrous structure. The electrodes had the three-dimensional current paths in the layers of active materials without the organic binders and the conductive additives. The charge-discharge profiles

Yoshimi Ohzawa; Masami Mitani; Vinay Gupta; Michio Inagaki; Tsuyoshi Nakajima

2002-01-01

255

Excess internal pressure, excess energy of vaporization and excess pseudo-Gruneisen parameter of binary, ternary and quaternary liquid mixtures  

Microsoft Academic Search

Densities, viscosities and ultrasonic velocities were measured for four binary, one ternary and one quaternary liquid systems at 298.15 K to obtain values of excess internal pressure and excess energy of vaporization. Values of pseudo-Gruneisen parameter and excess pseudo-Gruneisen parameter have been evaluated theoretically for two quaternary liquid systems. A quantitative relationship has been established among these thermodynamic properties with the

R. K. Shukla; S. K. Shukla; V. K. Pandey; Piyush Awasthi

2008-01-01

256

A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion)  

SciTech Connect

Alkali vapors (Na and K) in the hot flue gas from the pressurized fluidized-bed combustion (PFBC) of coal could cause corrosion problems with the gas turbine blades. In a laboratory-scale PFBC test with Beulah lignite, a fixed granular bed of activated bauxite sorbent was used to demonstrate its capability for measuring and controlling alkali vapors in the PFBC flue gas. The Beulah lignite was combusted in a bed of Tymochtee dolomite at bed temperatures ranging from 850 to 875{degrees}C and a system pressure of 9.2 atm absolute. The time-averaged concentration of sodium vapor in the PFBC flue gas was determined from the analysis of two identical beds of activated bauxite and found to be 1.42 and 1.50 ppmW. The potassium vapor concentration was determined to be 0.10 ppmW. The sodium material balance showed that only 0.24% of the total sodium in the lignite was released as vapor species in the PFBC flue gas. This results in an average of 1.56 ppmW alkali vapors in the PFBC flue gas. This average is more than 1.5 orders of magnitude greater than the currently suggested alkali specification limit of 0.024 ppm for an industrial gas turbine. The adsorption data obtained with the activated bauxite beds were also analyzed mathematically by use of a LUB (length of unused bed)/equilibrium section concept. Analytical results showed that the length of the bed, L{sub o} in centimeters, relates to the break through time, {theta}{sub b} in hours, for the alkali vapor to break through the bed as follows: L{sub o} = 33.02 + 1.99 {theta}{sub b}. This formula provides useful information for the engineering design of fixed-bed activated bauxite sorbers for the measurement and control of alkali vapors in PFBC flue gas. 26 refs., 4 figs., 4 tabs.

Lee, S.H.D.; Swift, W.M.

1990-01-01

257

Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives  

NASA Technical Reports Server (NTRS)

Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

2008-01-01

258

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

259

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

260

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

261

Alkali vapor pressure modulation on the 100ms scale in a single-cell vacuum system for cold atom experiments  

E-print Network

We describe and characterize a device for alkali vapor pressure modulation on the 100ms 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; Reichel, Jakob

2014-01-01

262

Alkali vapor pressure modulation on the 100ms scale in a single-cell vacuum system for cold atom experiments  

E-print Network

We describe and characterize a device for alkali vapor pressure modulation on the 100ms 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.

Vincent Dugrain; Peter Rosenbusch; Jakob Reichel

2014-06-19

263

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

264

Optimization of multi-pressure himidification-dehumidification desalination using thermal vapor compression and hybridization  

E-print Network

Humidification-dehumidification (HD or HDH) desalination, and specifically HD driven by a thermal vapor compressor (TVC), is a thermal desalination method that has the potential to produce potable water efficiently in order ...

Mistry, Karan Hemant

265

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

266

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces.  

PubMed

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 mum 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. PMID:18688373

Starr, David E; Wong, Ed K; Worsnop, Douglas R; Wilson, Kevin R; Bluhm, Hendrik

2008-06-01

267

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

line is subcooled liquid. The region enclosed by the pair represents a mixture of liquid and vapor are as follows: Assume the system is charged with a mixture having a concentration of component A designated, the refrigerant will be a mixture of liquid and vapor, as usually occurs in a single-refrigerant system. One

Oak Ridge National Laboratory

268

A new approach to determine vapor pressures of compounds in multicomponent systems by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry.  

PubMed

A method is described to determine vapor pressures of compounds in multicomponent systems simultaneously. The method is based on temperature-gradient analysis by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS). Vapor pressures are determined with the aid of known vapor pressure values of reference compounds eluting before and after the analytes. Reference compounds with the same functionalities as the analytes are preferred, but when these are not available, the alkane series can be utilized. The number of compounds whose vapor pressures can be determined is limited only by the peak capacity of the chromatographic system. Although the lowest subcooled vapor pressure determined was 0.006 Pa, for tetrahydroaraucarolone in an atmospheric aerosol sample, vapor pressures as low as 10(-6) Pa can be measured with the described set-up. Even lower values can be measured with higher GC temperatures and longer analysis times. Since only a few picograms of compound is required, in a mixture of any complexity, the GCxGC-TOFMS method offers unique sensitivity, rapidity, and comprehensiveness. PMID:24767441

Parshintsev, Jevgeni; Lai, Ching Kwan; Hartonen, Kari; Kulmala, Markku; Riekkola, Marja-Liisa

2014-06-01

269

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

270

Meteorological Tables for Determination of Precipitable Water, Temperatures and Pressures Aloft for a Saturated Pseudoadiabatic Atmosphere -- in the Metric System  

E-print Network

The hydrometeorologist is often confronted with the problem of determination of precipitable water in the atmosphere based on surface dewpoints and the assumption of a saturated atmosphere with a pseudoadiabatic lapse rate. Tables have been prepared...

Eihle, W. O.; Powers, R. J.; Clark, R.A.

271

Uniqueness of specific interfacial area-capillary pressure-saturation relationship under non-equilibrium conditions in two-phase porous media flow  

Microsoft Academic Search

The capillary pressure–saturation (P c–S w) relationship is one of the central constitutive relationships used in two-phase flow simulations. There are two major concerns regarding this relation. These concerns are partially studied in a hypothetical porous medium using a dynamic pore-network model called DYPOSIT, which has been employed and extended for this study: (a) P c–S w relationship is measured

V. Joekar-Niasar; S. M. Hassanizadeh

2012-01-01

272

Effects of hot isostatic pressure on titanium nitride films deposited by physical vapor deposition  

Microsoft Academic Search

Films of titanium nitride deposited by physical vapor deposition on 304 L stainless steel substrates were hot isostatic pressed (HIP) under 150 MPa at 550 °C. To study the effects of this treatment on the microstructure of those films, X-ray diffraction analyses, Rutherford Backscattering spectroscopy, scanning electron microscopy, and atomic force microscopy were performed. Surface hardness, and roughness were also

M. J. Carbonari; J. R. Martinelli

2001-01-01

273

Physical and electrical properties of graphene grown under different hydrogen flow in low pressure chemical vapor deposition  

PubMed Central

Hydrogen flow during low pressure chemical vapor deposition had significant effect not only on the physical properties but also on the electrical properties of graphene. Nucleation and grain growth of graphene increased at higher hydrogen flows. And, more oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination of graphene remained on the graphene surface at low H2 flow conditions. It is believed that at low hydrogen flow, those remained oxygen or other oxidizing impurities make the graphene films p-doped and result in decreasing the carrier mobility. PMID:25332692

2014-01-01

274

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

275

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

SciTech Connect

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

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

1996-03-01

276

Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method  

SciTech Connect

Boron nitride nanotubes (BNNTs) are desired for their exceptional mechanical, electronic, thermal, structural, textural, optical, and quantum properties. 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.

Michael W. Smith, Kevin Jordan, Cheol Park, Jae-Woo Kim, Peter Lillehei, Roy Crooks, Joycelyn Harrison

2009-11-01

277

M. Bahrami ENSC 461 (S 11) Vapor Power Cycles 1 Vapor Power Cycles  

E-print Network

steam is condensed in the condenser 4 3 1 2 s T 1 2 34 s #12;M. Bahrami ENSC 461 (S 11) Vapor Power. For instance lake @ 15°C + T (10°C) = 25°C. The steam saturation pressure (or the condenser pressure is not a suitable model for steam power cycle since: The turbine has to handle steam with low quality which

Bahrami, Majid

278

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

Code of Federal Regulations, 2013 CFR

... false Standards: Pressure relief devices in gas...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...for Organic Hazardous Air Pollutants for Equipment...63.165 Standards: Pressure relief devices in...

2013-07-01

279

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

Code of Federal Regulations, 2012 CFR

... false Standards: Pressure relief devices in gas...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE...for Organic Hazardous Air Pollutants for Equipment...63.165 Standards: Pressure relief devices in...

2012-07-01

280

Silicate liquid-carbonatite liquid transition along the melting curve of model, vapor-saturated peridotite in the system CaO-MgO-Al2O3-SiO2-CO2 from 1.1 to 2 GPa  

NASA Astrophysics Data System (ADS)

phase relations of carbon dioxide-saturated (CO2 vapor) model peridotite in the system CaO-MgO-Al2O3-SiO2-CO2 in the 1.1-2.1 GPa pressure range are reported. The solidus has a positive slope in pressure-temperature (PT) space from 1.1 to 2 GPa. Between 2 and 2.1 GPa, the melting curve changes to a negative slope. From 1.1 to 1.9 GPa, the liquid, best described as CO2-bearing silicate liquid, is in equilibrium with forsterite, orthopyroxene, clinopyroxene, spinel, and vapor. At 2 GPa, the same crystalline phase assemblage plus vapor is in equilibrium with two liquids, which are silicate and carbonatitic in composition, making the solidus at 2 GPa PT invariant. The presence of two liquids is interpreted as being due to liquid immiscibility. Melting reactions written over 1.1-1.9 GPa are peritectic, with forsterite being produced upon melting, and the liquid is silicate in composition. Upon melting at 2.1 GPa, orthopyroxene is produced, and the liquid is carbonatitic in composition. Hence, the invariance between 1.9 and 2.1 GPa is not only the reason for the dramatic change in the liquid composition over an interval of 0.2 GPa, but the carbonated peridotite solidus ledge itself most likely appears because of this PT invariance. It is suggested that because carbonatitic liquid is produced at the highest solidus temperature at 2 GPa in PT space in the system studied, such liquids, in principle, can erupt through liquid immiscibility, as near-primary magmas from depths of approximately 60 km.

Keshav, Shantanu; Gudfinnsson, Gudmundur H.

2013-07-01

281

Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains.  

PubMed

This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [CN/2CN/2im][NTf2] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [CN/2CN/2im][NTf2] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [CN-1C1im][NTf2]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C6C6im][NTf2], was detected. An intensification of the odd-even effect was observed starting from [C6C6im][NTf2], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C7C7im][NTf2] and [C9C9im][NTf2]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [CN/2CN/2im][NTf2] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C6C1and C6C6) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length. PMID:25296816

Rocha, Marisa A A; Coutinho, João A P; Santos, Luís M N B F

2014-10-01

282

Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains  

NASA Astrophysics Data System (ADS)

This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [CN/2CN/2im][NTf2] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [CN/2CN/2im][NTf2] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [CN-1C1im][NTf2]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C6C6im][NTf2], was detected. An intensification of the odd-even effect was observed starting from [C6C6im][NTf2], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C7C7im][NTf2] and [C9C9im][NTf2]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [CN/2CN/2im][NTf2] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C6C1and C6C6) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

Rocha, Marisa A. A.; Coutinho, João A. P.; Santos, Luís M. N. B. F.

2014-10-01

283

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

284

Enhanced Reliability of Hard Disk Drive by Vapor Corrosion Inhibitor  

Microsoft Academic Search

Vapor corrosion inhibitor can improve the reliability of heads and disks in a hard disk drive by forming a protective film over exposed metal. Diffusion channels from a source and to a drain are designed to control the steady state relative partial pressure of the desirable species below saturation. Extended accelerated life tests and repeated condensing humidity cycle tests demonstrate

Run-Han Wang; H. Russ Wendt; Charlie A. Brown; Sharon Lum; Scott McCoy; Tom Karis

2006-01-01

285

High pressure range of the addition of HO to HO, NO, NO2, and CO. I. Saturated laser induced fluorescence measurements at 298 K  

NASA Astrophysics Data System (ADS)

Saturated laser induced fluorescence is used for the sensitive detection of radicals in high pressure gases. The method and its application to a series of addition reactions of HO radicals in the high pressure regime are described. Experiments between 1 and 150 bar of the bath gas He allow for falloff extrapolations to the high pressure limit of the recombination reactions. Limiting rate constants (in cm3 molecule-1 s-1) of 2.2×10-11 for HO+HO?H2O2, of 3.3×10-11 for HO+NO?HONO, of 7.5×10-11 for HO+NO2?HONO2, and of 9.7×10-13 for HO+CO?HOCO (and H+CO2) are derived at 298 K.

Forster, R.; Frost, M.; Fulle, D.; Hamann, H. F.; Hippler, H.; Schlepegrell, A.; Troe, J.

1995-08-01

286

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

287

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

288

Saturated defect densities of hydrogenated amorphous silicon grown by hot-wire chemical vapor deposition at rates up to 150 Å\\/s  

Microsoft Academic Search

Hydrogenated amorphous-silicon (a-Si:H) is grown by hot-wire chemical vapor deposition (HWCVD) at deposition rates (Rd) exceeding 140 Å\\/s (?0.8 ?m\\/min). These high rates are achieved by using multiple filaments and deposition conditions different than those used to produce our standard 20 Å\\/s material. With proper deposition parameter optimization, an AM1.5 photo-to-dark-conductivity ratio of 105 is maintained at an Rd up

A. H. Mahan; Y. Xu; B. P. Nelson; R. S. Crandall; J. D. Cohen; K. C. Palinginis; A. C. Gallagher

2001-01-01

289

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.

Valizadeh, Sousan; Hosseini, Mohammad Bagher; Asghari Jafarabadi, Mohammad; Ajoodanian, Najmeh

2012-01-01

290

Mass Spectrometric Identification of Si-O-H(g) Species from the Reaction of Silica with Water Vapor at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

A high-pressure sampling mass spectrometer was used to detect the volatile species formed from SiO2 at temperatures between 1200C and 1400C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH)4. The fragment ion Si(OH)3+,' was observed in quantities 3 to 5 times larger than the parent ion Si(OH)4+. The Si(OH)3+ intensity was found to have a small temperature dependence and to increase with the water vapor partial pressure as expected. In addition, SiO(OH)+ believed to be a fragment of SiO(OH)2, was observed. These mass spectral results were compared to the behavior of silicon halides.

Opila, Elizabeth J.; Fox, Dennis S.; Jacobson, Nathan S.

1997-01-01

291

Comparison of a Lattice-Boltzmann Model, a Full-Morphology Model, and a Pore Network Model for Determining Capillary Pressure–Saturation Relationships  

Microsoft Academic Search

specific situation, only the wetting phase may need to beconsidered,(e.g.,theRichardsequation),ortheNWP Effective hydraulic properties of porousmedia such as the capillary is considered additionally. pressure-saturation relation and the hydraulic conductivity function Clearly,theconstitutiverelationsareadirectmanifes- areadirectmanifestationoftheunderlyingporegeometry.Theporous tation of the complicated geometry of the underlying structureofamacroscopicallyhomogeneousporousmedium(sintered glass)wasmeasuredindetailusingX-raymicrotomography.Weinves- pore space. However, sw,n(pc) and Kw,n(sw,n) are typically tigated the possibility of deriving the water characteristic on the basis

H.-J. Vogel; J. Tölke; V. P. Schulz; M. Krafczyk; K. Roth

2005-01-01

292

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

293

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

294

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

295

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

296

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

297

Water entry into detached root systems saturates with increasing externally applied pressure; a result inconsistent with models of simple passive diffusion.  

PubMed

The most widely accepted model of radial water entry from the soil into the xylem of roots is based on principles of ordinary passive diffusion. However, long-standing problems with this model remain unresolved, which concern variable intrinsic properties of conductivity, Lp, changing reflection coefficients, sigma, and inaccurate resolution of osmotic differentials between the soil and xylem. Our study re-examined pressure flow relationships in isolated roots of tomato (Lycopersicon esculentum Mill. cv. Montfavet), pea (Pisum sativum cv. Baccara) and soybean (Glycine max L. Merryl cv. Essor) manipulated in a pressure chamber. In addition to problems previously recognized with the simple passive diffusion model, a new conflict, flow saturation, was observed at high pressures. Experiments revealed that the plateau in flow, Jmax seen at high pressures followed natural rhythms diurnally and developmentally, and was not due to root damage or unnatural flow restriction. Near the end of the photoperiod, Jmax closely correlated with root dry mass. The above inconsistencies between observations in pressure-flow kinetics and ordinary passive diffusion indicate that either the current model should be adjusted or a new model should be proposed. PMID:12081534

Emery, R. J. Neil; Salon, Christophe

2002-07-01

298

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

299

Vapor pressures of binary mixtures of hexane + 1-butanol, + 2-butanol, + 2-methyl-1-propanol, or + 2-methyl-2-propanol at 298. 15 K  

SciTech Connect

Previous papers from this laboratory reported measurements of excess enthalpies, excess volumes, vapor pressures, and dipole moments for mixtures containing an alkanol. The authors have now begun a systematic study of the properties of mixtures containing isomeric butanols. While many studies of the thermodynamic properties of 1-butanol have been published, only a few systematic investigations have been carried out for mixtures containing isomeric butanols. The total vapor pressures of binary mixtures of hexane + 1-butanol, + 2-butanol, + 2-methyl-1-propanol, or + 2-methyl-2-propanol were measured by a static method at 298.15 K. Vapor-phase compositions, activity coefficients, and excess molar Gibbs energies were calculated by Barker's method.

Rodriguez, V.; Pardo, J.; Lopez, M.C.; Royo, F.M.; Urieta, J.S. (Univ. de Zaragoza (Spain). Dept. de Quimica Organica-Quimica Fisica)

1993-07-01

300

Enhanced optical properties of chemical vapor deposited single crystal diamond by low-pressure/high-temperature annealing  

PubMed Central

Single crystal diamond produced by chemical vapor deposition (CVD) at very high growth rates (up to 150 ?m/h) has been successfully annealed without graphitization at temperatures up to 2200 °C and pressures <300 torr. Crystals were annealed in a hydrogen environment by using microwave plasma techniques for periods of time ranging from a fraction of minute to a few hours. This low-pressure/high-temperature (LPHT) annealing enhances the optical properties of this high-growth rate CVD single crystal diamond. Significant decreases are observed in UV, visible, and infrared absorption and photoluminescence spectra. The decrease in optical absorption after the LPHT annealing arises from the changes in defect structure associated with hydrogen incorporation during CVD growth. There is a decrease in sharp line spectral features indicating a reduction in nitrogen-vacancy-hydrogen (NVH?) defects. These measurements indicate an increase in relative concentration of nitrogen-vacancy (NV) centers in nitrogen-containing LPHT-annealed diamond as compared with as-grown CVD material. The large overall changes in optical properties and the specific types of alterations in defect structure induced by this facile LPHT processing of high-growth rate single-crystal CVD diamond will be useful in the creation of diamond for a variety of scientific and technological applications. PMID:19004770

Meng, Yu-fei; Yan, Chih-shiue; Lai, Joseph; Krasnicki, Szczesny; Shu, Haiyun; Yu, Thomas; Liang, Qi; Mao, Ho-kwang; Hemley, Russell J.

2008-01-01

301

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

302

Properties of titanium nitride thin films deposited by rapid-thermal-low-pressure-metalorganic-chemical- vapor-deposition technique using tetrakis (dimethylamido) titanium precursor  

Microsoft Academic Search

Titanium nitride (TiNx) thin films were deposited onto InP by means of the rapid-thermal-low-pressure-chemical-vapor-deposition (RT-LPMOCVD) technique, using the tetrakis (dimethylamido) titanium (Ti(NMe2)4 or DMATi) complex as the precursor. Depositions were successfully carried out at temperatures below 550 °C, pressure range of 5–20 Torr and duration of 50 to 90 s, to give layer thicknesses up to 200 nm and growth

A. Katz; A. Feingold; S. J. Pearton; S. Nakahara; M. Ellington; U. K. Chakrabarti; M. Geva; E. Lane

1991-01-01

303

Effects of pore diameters and system pressure on saturated pool nucleate boiling heat transfer from porous surfaces  

Microsoft Academic Search

The porous surface structure was manufactured with precision for the experimental study of nucleate boiling heat transfer in R-11. Boiling curves and the data of bubble formation were obtained with a variety of geometrical and operational parameters; the pore diameters were of 50, 100, 150 ..mu..m, there was a combination of pores of different sizes; and the system pressures were

W. Nakayama; T. Daikoku; T. Nakajima

1982-01-01

304

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

305

A Theoretical Analysis of the Formation of Nonstoichiometric Point Defects in SiC Single Crystals Grown under Equilibrium Conditions at Different Partial Pressures of Silicon Vapor  

Microsoft Academic Search

Formation of Schottky and Frenkel vacancy-type point defects in silicon carbide single crystals is analyzed. Relevant equations for numerical analysis are derived and a method for their solution is proposed. The partial pressure of silicon vapor over the growing crystal is shown to play a role in the formation of defects in SiC single crystals.

A. P. Garshin; E. N. Mokhov; V. E. Shvaiko-Shvaikovskii

2003-01-01

306

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

is 150 Torr. What is the composition of a liquid mixture that boils at 90°C when the pressure is 0.50 atm mixtures. Consider the equilibrium composition of a mixture in which the mole fraction of A in the vapor is 0.350. Calculate the total pressure of the vapor and the composition of the liquid mixture. Prob 8

Findley, Gary L.

307

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

308

Atmospheric Pressure Chemical Vapor Deposition and Jet Vapor Deposition of CdTe for High Efficiency Thin Film PV Devices: Final Technical Report, 26 January 2000 - 15 August 2002  

Microsoft Academic Search

ITN's three-year project, Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices, had the overall objectives of improving thin-film CdTe PV manufacturing technology and increasing CdTe PV device power-conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16%-efficient CdTe PV films, i.e., close-spaced sublimation, but employs

L Woods; P. Meyers

2002-01-01

309

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.

310

Calibrated vapor generator source  

DOEpatents

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.

Davies, John P. (Idaho Falls, ID); Larson, Ronald A. (Idaho Falls, ID); Goodrich, Lorenzo D. (Shelley, ID); Hall, Harold J. (Idaho Falls, ID); Stoddard, Billy D. (Idaho Falls, ID); Davis, Sean G. (Idaho Falls, ID); Kaser, Timothy G. (Idaho Falls, ID); Conrad, Frank J. (Albuquerque, NM)

1995-01-01

311

Calibrated vapor generator source  

DOEpatents

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

312

Thermodynamic and transport properties of sodium liquid and vapor  

SciTech Connect

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

Fink, J.K.; Leibowitz, L.

1995-01-01

313

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

314

A method for the calculation of the adsorbed phase volume and pseudo-saturation pressure from adsorption isotherm data on activated carbon.  

PubMed

We propose a new method for evaluating the adsorbed phase volume during physisorption of several gases on activated carbon specimens. We treat the adsorbed phase as another equilibrium phase which satisfies the Gibbs equation and hence assume that the law of rectilinear diameters is applicable. Since invariably the bulk gas phase densities are known along measured isotherms, the constants of the adsorbed phase volume can be regressed from the experimental data. We take the Dubinin-Astakhov isotherm as the model for verifying our hypothesis since it is one of the few equations that accounts for adsorbed phase volume changes. In addition, the pseudo-saturation pressure in the supercritical region is calculated by letting the index of the temperature term in Dubinin's equation to be temperature dependent. Based on over 50 combinations of activated carbons and adsorbates (nitrogen, oxygen, argon, carbon dioxide, hydrocarbons and halocarbon refrigerants) it is observed that the proposed changes fit experimental data quite well. PMID:21670804

Srinivasan, Kandadai; Saha, Bidyut Baran; Ng, Kim Choon; Dutta, Pradip; Prasad, Madhu

2011-07-21

315

The Effect of Total Reactor Pressure on GaInSb Grown on Gd3Ga5O12 Substrate by Metal Organic Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

To investigate the possibility of improving the crystal quality of a GaInSb layer grown on a Gd3Ga5O12 substrate by metal organic chemical vapor deposition (MOCVD), experimental studies were carried out on the effect of the total reactor pressure. The lattice constant was affected by the pressure. The effect of reducing the pressure was dependent on the growth temperature. In a low-temperature regime, the lattice constant increased, and at high temperature it decreased, as the pressure was reduced. The growth rate increased as the pressure was reduced in both temperature regimes. Upon reduction of the pressure, the range of growth conditions which gives a preferentially (111)-oriented GaInSb layer became narrow.

Totoki, Machiko; Mizumoto, Tetsuya; Nakamura, Toshihiko; Maru, Kouichi; Sato, Yoshiyasu; Naito, Yoshiyuki

1995-07-01

316

Effects of Temperature, Pressure, and Metal Promoter on the Recrystallized Structure and Optical Transmission of Chemical Vapor Deposited Zinc Sulfide  

SciTech Connect

Structural changes from processing in polytype-rich ZnS are complex and poorly understood In this study, recrystallization was induced in chemical vapor deposited (CVD) ZnS by annealing and hot isostatic pressing (HIPing). Samples were characterized using optical microscopy, SEM, TEM, electron diffraction, polycrystalline and powder x-ray diffraction, and transmission spectroscopy. Recrystallization was found to reduce the hexagonality and increase the texture of as deposited ZnS. Changes in hexagonality and texture can occur independently of each other. HIP’d ZnS with superior transmission exhibits both a change in texture as well as a reduction in hexagonal content. Reduction in hexagonality, alone, was not sufficient to improve optical transmission from the visible to the infrared. For the first time, the effects of pressure, temperature, and the presence of platinum on recrystallization during commercial ZnS HIPing are separated and identified. Platinum was found to actively promote recrystallization and silver demonstrated a similar effect. Several theories focusing on the unique polytypic nature of ZnS are offered to explain the changes in structure and properties occurring during recrystallization, These findings contribute to a broader understanding of the nature of order-disorder and martensitic phase transformations in ceramic materials.

McCloy, John S.; Korenstein, Ralph; Zelinski, Brian

2009-08-01

317

Patterning and overgrowth of nanostructure quantum well wire arrays by LP-MOVPE (low pressure Metalorganic Vapor Phase Epitaxy)  

SciTech Connect

Nanometer scale GaAs Quantum Well Wire (QWW) arrays with lateral dimensions in the range of 10--70 nm and a period of 200 nm have been fabricated in the GaAs/AlGaAs system using x-ray nanolithography patterning and overgrowth by a low pressure Metalorganic Vapor Phase Epitaxy (LP-MOVPE) technique. The QWW structures were either fabricated by post-growth patterning of a thin GaAs film on a AlGaAs-coated substrate followed by AlGaAs deposition, or by continuous in-situ deposition of a GaAs/AlGaAs QWW structure on a prepatterned GaAs substrate. Although cross-sectional transmission electron microscopy showed no structural defects in either QWW fabrication process, photoluminescence (PL) was only observed in the in-situ-deposited structures. Strong polarization dependence of the PL peak with respect to wire orientation has been confirmed and evidence of lateral confinement was observed. 17 refs., 4 figs.

Karam, N.H.; Mastrovito, A.; Haven, V. (Spire Corp., Bedford, MA (USA)); Ismail, K. (International Business Machines Corp., Yorktown Heights, NY (USA). Thomas J. Watson Research Center); Pennycook, S. (Oak Ridge National Lab., TN (USA)); Smith, H.I. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Electrical Engineering and Computer Science)

1990-06-01

318

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 ...

319

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

320

Dolomite-calcite equilibrium at 220 to 240[degrees]C at saturation vapour pressure: Experimental data  

SciTech Connect

Small amounts of dolomite and calcite were added as reactants to a series of CaCl[sub 2-]MgCl[sub 2] solutions with variable Ca:Mg ratios at temperatures of 220[degrees]C and 240[degrees]C at vapour pressure in sixty experimental runs. Dolomitization of calcite and calcitization of dolomite in these runs indicates that the value of log (aCa[sup 2+]/aMg[sup 2+]) in solutions at equilibrium with calcite and dolomite ranges from about 0.4 to 0.9 at these temperatures. This is in agreement with previous experimental work at higher and lower temperatures. These experimentally determined equilibrium log (aCa[sup 2+]/aMg[sup 2+]) values are less than calculated by thermodynamic based programs, such as SUPCRT and PTA, for equilibrium with ordered dolomite and those which may be calculated from calorimetric data obtained from ordered, ideal dolomite. This may indicate that the experimentally observed calcite-dolomite equilibrium is metastable and that the precipitated dolomites are imperfectly ordered. Precipitation of partially disordered, metastable dolomite of stoichiometric composition may be favoured over that of ideal dolomite at these temperatures for kinetic reasons.

Morrow, D.W.; Gorham, B.L.; Wong, J.N.Y. (Institute of Sedimentary and Petroleum Geology, Calgary, Alberta (Canada))

1994-01-01

321

Vapor pressure studies of the solubilization of hydrocarbons by surfactant micelles. Quarterly report, July 1, 1984-September 30, 1984. [Sodium octylsulfate/NaCl/benzene/water system  

SciTech Connect

The objectives of the project are to obtain accurate thermodynamic information about the solubilization of hydrocarbons and polar derivatives of hydrocarbons by surfactant solutions. Several aqueous surfactant systems, including sodium octylsulfate, sodium octylbenzenesulfonate, and cetylpyridinium chloride, are being investigated with vapor pressure, surface tension, ion activity, and osmometery methods. The extensive analysis of solubilization results for the system sodium octylsulfate/NaCl/benzene/water has been completed, and results summarized in an article to appear in the Journal of Colloid and Interface Science (1). The mathematical analysis of the precise vapor pressure data for this system has been performed to correlate all the results with a mass-action, modified-Poisson distribution model developed in our laboratory. The vapor pressure data for the system at 15, 25, 35, and 45/sup 0/C are fitted by the model to a root mean square deviation in dissolved benzene concentration of approximately 0.00001 M in each case. Partial pressure of benzene, n-butanol, n-pentanol, and n-hexane have been determined for solutions of cetylpyridinium chloride (CPC) at several CPC concentrations at 25/sup 0/C. Systems containing an aromatic or alphatic hydrocarbon and a co-surfactant (e.g., an aliphatic alcohol having 4 to 8 carbon atoms) are currently under investigation.

Christian, S.D.; Tucker, E.E.

1984-01-01

322

Real-Time Optical Monitoring and Simulations of Gas Phase Kinetics in InN Vapor Phase Epitaxy at High Pressure  

NASA Technical Reports Server (NTRS)

Understanding the kinetics of nucleation and coalescence of heteroepitaxial thin films is a crucial step in controlling a chemical vapor deposition process, since it defines the perfection of the heteroepitaxial film both in terms of extended defect formation and chemical integrity of the interface. The initial nucleation process also defines the film quality during the later stages of film growth. The growth of emerging new materials heterostructures such as InN or In-rich Ga(x)In(1-x)N require deposition methods operating at higher vapor densities due to the high thermal decomposition pressure in these materials. High nitrogen pressure has been demonstrated to suppress thermal decomposition of InN, but has not been applied yet in chemical vapor deposition or etching experiments. Because of the difficulty with maintaining stochiometry at elevated temperature, current knowledge regarding thermodynamic data for InN, e.g., its melting point, temperature-dependent heat capacity, heat and entropy of formation are known with far less accuracy than for InP, InAs and InSb. Also, no information exists regarding the partial pressures of nitrogen and phosphorus along the liquidus surfaces of mixed-anion alloys of InN, of which the InN(x)P(1-x) system is the most interesting option. A miscibility gap is expected for InN(x)P(1-x) pseudobinary solidus compositions, but its extent is not established at this point by experimental studies under near equilibrium conditions. The extension of chemical vapor deposition to elevated pressure is also necessary for retaining stoichiometric single phase surface composition for materials that are characterized by large thermal decomposition pressures at optimum processing temperatures.

Dietz, Nikolaus; Woods, Vincent; McCall, Sonya D.; Bachmann, Klaus J.

2003-01-01

323

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

324

Origin of the bimodal distribution of low-pressure metal-organic-vapor-phase-epitaxy grown InGaAs\\/GaAs quantum dots  

Microsoft Academic Search

The formation process of a bimodal distribution of low-pressure metal-organic-vapor-phase-epitaxy (LP-MOVPE) grown InGaAs\\/GaAs quantum dots (QDs) is studied by transmission electronic microscopy. We demonstrate that in our growth conditions, the deposition of an InGaAs layer on an already existing array of InAs formed QDs leads to the nucleation of a second dots population. The InAs QDs nucleation is diffusion limited,

G. Saint-Girons; G. Patriarche; A. Mereuta; I. Sagnes

2002-01-01

325

Atmospheric pressure chemical vapor deposition of CdTe for high efficiency thin film PV devices: Annual subcontract report, 26 January 1999--25 January 2000  

Microsoft Academic Search

ITN's three year project Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices has the overall objectives of improving thin film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16% efficient CdTe PV films, i.e.,

P. V. Meyers; R. Kee; C. Wolden; J. Kestner; L. Raja; V. Kaydanov; T. Ohno; R. Collins; A. Fahrenbruch

2000-01-01

326

Atmospheric Pressure Chemical Vapor Deposition of CdTe for High-Efficiency Thin-Film PV Devices; Annual Report, 26 January 1998-25 January 1999  

Microsoft Academic Search

ITN's 3-year project, titled ''Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High-Efficiency Thin-Film Photovoltaic (PV) Devices,'' has the overall objectives of improving thin-film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16%-efficient CdTe PV films, i.e., close-spaced sublimation, but

P. V. Meyers; R. Kee; C. Wolden; L. Raja; V. Kaydanov; T. Ohno; R. Collins; M. Aire; J. Kestner; A. Fahrenbruch

1999-01-01

327

Multilayer coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP\\/FBR-CVD): TiN\\/TaN and TiN\\/W  

Microsoft Academic Search

TiN\\/W and TiN\\/TaN multilayer coatings were deposited on stainless steel by Chemical Vapor Deposition in a Fluidized Bed Reactor at Atmospheric Pressure (AP\\/FBR-CVD). First, the conditions for the deposition of TiN single layers were investigated, both from the experiment and thermochemical estimations. TiN was deposited from TiCl4 and NH3 at temperatures in the range of 750–950 °C. In the synthesis of

J. Perez-Mariano; K.-H. Lau; A. Sanjurjo; J. Caro; J. M. Prado; C. Colominas

2006-01-01

328

TiSiN nanocomposite coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP\\/FBR-CVD)  

Microsoft Academic Search

TiSiN nanocomposite coatings were deposited on stainless steel by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP\\/FBR-CVD) by reaction of TiCl4 and SiCl4 with NH3 at 850 °C. Coatings were characterized by means of GD-OES, XPS and XRD. TiSiN coatings with a Si content of 9 at.% showed a hardness of 28 GPa (the hardness of TiN and

J. Perez-Mariano; K.-H. Lau; A. Sanjurjo; J. Caro; D. Casellas; C. Colominas

2006-01-01

329

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

330

Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites  

NASA Astrophysics Data System (ADS)

In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

2013-06-01

331

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

332

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

333

Sulfur Concentration of High-FeO* Basalts at Sulfide Saturation at High Pressures and Temperatures - Implications for Deep Sulfur Cycle on Mars (Invited)  

NASA Astrophysics Data System (ADS)

One of the chief influences of magma in the mantles terrestrial planets is its role in outgassing and ingassing of key volatiles and thus affecting planetary dynamics and climate over long timescales. For Mars, magmatic release of greenhouse gases has been argued to be a major factor in creating warm ancient climate. However, the responsible magmatic gas has not been unequivocally identified. SO2 or H2S could have been the main greenhouse gases, yet the magmatic outflux of S from the martian mantle is poorly constrained. Righter et al. [1] showed that the use of sulfur content at sulfide saturation (SCSS) models based on low-FeO*, high-alumina terrestrial basalts to martian basalts leads to significant error. However, experiments on high-FeO* basalts remain limited to ?0.8 GPa [1], although the onset of melting in the martian mantle may take place at 250-400 km depth (3-5 GPa) [2]. To constrain SCSS of martian magmas at mantle conditions, we simulated basalt-sulfide melt equilibria using two synthesized meteorite compositions, i.e., Yamato980459 (FeO* ˜17 wt.%; Al2O3 ˜6 wt.%) and NWA2990 (FeO* ˜16 wt.%; Al2O3 ˜9 wt.%) in both anhydrous and hydrous conditions at 1-3 GPa and 1500-1700 °C. Experiments were conducted in graphite capsules, using an end-loaded piston cylinder device. Sulfur contents of sulfide melt-saturated experimental quenched basalts were determined using electron microprobe. Our experimental results show that SCSS decreases with increasing pressure and increases with increasing temperature and melt hydration. Based on our experimental SCSS and those from previous low-pressure experiments on high-FeO* martian basalts [2], we developed a new parameterization to predict martian basalt SCSS as a function of depth, temperature, and melt composition. Our model suggests that at the conditions of last equilibration with the sulfide-saturated mantle [2], martian basalts may contain as high as 3500-4700 ppm S and thus S-rich gases might have caused the greenhouse conditions during the late Noachian. However, modeling the fate of sulfur along the liquid line of descent of primitive martian basalts suggests that a part of the magmatic sulfur could precipitate as sulfides in the cumulates during cooling and fractional crystallization of basaltic magmas. Moreover, the existing and new data on bulk sulfur contents of martian meteorites [3,4] suggest that they can be explained by variable amount of S-bearing liquid, trapped as intercumulus phase and thus the degassed S flux to the atmosphere may be lower than that predicted by SCSS. Modeling the SCSS of martian mantle composition along the possible liquidus of Mars to the base of the martian magma ocean (MO) predicts an average S storage capacity of 3700 ppm, whereas the same for low-FeO*, deep terrestrial MO is only ~860 ppm. Lastly, pronounced inverse correlation between pressure and SCSS could have triggered a sulfur pump for the martian magma ocean where the post-core-formation bulk silicate Mars would gain sulfur through interaction with SO2/H2S rich primitive atmosphere. [1] Righter et al. (2009) EPSL 288, 235-243; [2] Filiberto and Dasgupta (2011) EPSL 304, 527-537; [3] Lodders (1998) MAPS 33, A183-A190; [4] Ding et al. (2013) Fall AGU meeting.

Dasgupta, R.; Ding, S.

2013-12-01

334

Atmospheric Pressure Plasma-Initiated Chemical Vapor Deposition (AP-PiCVD) of Poly(diethylallylphosphate) Coating: A Char-Forming Protective Coating for Cellulosic Textile.  

PubMed

An innovative atmospheric pressure chemical vapor deposition method toward the deposition of polymeric layers has been developed. This latter involves the use of a nanopulsed plasma discharge to initiate the free-radical polymerization of an allyl monomer containing phosphorus (diethylallylphosphate, DEAP) at atmospheric pressure. The polymeric structure of the film is evidence by mass spectrometry. The method, highly suitable for the treatment of natural biopolymer substrate, has been carried out on cotton textile to perform the deposition of an efficient and conformal protective coating. PMID:25362895

Hilt, Florian; Boscher, Nicolas D; Duday, David; Desbenoit, Nicolas; Levalois-Grützmacher, Joëlle; Choquet, Patrick

2014-11-12

335

Methane hydrate pore saturation evaluation from geophysical logging and pressure core analysis, at the first offshore production test site in the eastern Nankai Trough, Japan  

NASA Astrophysics Data System (ADS)

On March 2013, the first offshore production test form methane hydrate (MH) concentrated zone (MHCZ) was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21) at the AT1 site located in the north-western slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. Before the production test, extensive geophysical logging and pressure coring using Hybrid Pressure Coring System were conducted in 2012 at monitoring well (AT1-MC) and coring well (AT1-C), in order to obtain basic information for the MH reservoir characterization. MH pore saturation (Sh) is one of the important basic parameters not only for reservoir characterization, but also the resource assessment. However, precise evaluation of Sh from geophysical logging is still challenging technical issue. The MHCZ confirmed by the geophysical logging at AT1-MC has a turbidite assemblage (from several tens of centimeters to a few meters) with 60 m of gross thickness; it is composed of lobe/sheet type sequences in the upper part, and relatively thick channel sand sequences in the lower part. In this study, the Sh evaluated from geophysical logging data were compared with those evaluated from pressure core analysis. Resistivity logs and nuclear magnetic resonance (NMR) log were used for the Sh evaluation by geophysical logging. Standard Archie equation was applied for Sh evaluation from resistivity log, while density magnetic resonance (DMR) method was used for Sh evaluation from NMR log. The Sh from pressure core samples were evaluated using the amount of dissociated gas volume, together with core sample bulk volume, measured porosity, net sand intervals, and assumed methane solubility in pore water. In the upper part of the MHCZ, Sh estimated from resistivity log showed distinct difference in value between sand and mud layers, compared to Sh from NMR log. Resistivity log has higher vertical resolution than NMR log, so it is favorable for these kinds of thin bed evaluation. In this part, 50 to 80% of Sh was observed in sandy layer, which showed fairly good agreement with core derived Sh. On the other hand, lower part of the MHCZ, Sh estimated from both resistivity and NMR log showed higher background value and relatively smoother curve than upper part. In this part, 50 to 80% of Sh was observed in sandy layer, which was also showed good agreement with core derived Sh. This study was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21).

Fujii, T.; Suzuki, K.; Takayama, T.; Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Nagao, J.

2013-12-01

336

Vapour pressure of water over saturated solutions of tartaric acid, sodium hydrogen tartrate, sodium tartrate, potassium tartrate, calcium tartrate, barium tartrate, citric acid, disodium hydrogen citrate, sodium citrate, and potassium citrate at temperatures from 277 K to 317 K  

Microsoft Academic Search

Vapour pressures of saturated aqueous solutions of tartaric acid, sodium hydrogen tartrate, sodium tartrate, potassium tartrate, calcium tartrate, barium tartrate, citric acid, disodium hydrogen citrate, sodium citrate, and potassium citrate were determined in the temperature range (277 to 317)K using an electronic hygrometer. Only for tartaric acid, sodium tartrate, potassium tartrate and citric acid was it possible to compare the

Emanuel Manzurola; Alexander Apelblat

2003-01-01

337

Using time-lapse seismic amplitude data to detect variations of pore pressure and fluid saturation due to oil displacement by water: a numerical study based on one-dimensional  

E-print Network

Using time-lapse seismic amplitude data to detect variations of pore pressure and fluid saturation due to oil displacement by water: a numerical study based on one-dimensional prestack inversion. Geophys. Eng. 3 (2006) 177­193 doi:10.1088/1742-2132/3/2/009 Using time-lapse seismic amplitude data

Torres-Verdín, Carlos

338

Storm pulse chemographs of saturation index and carbon dioxide pressure: implications for shifting recharge sources during storm events in the karst aquifer at Fort Campbell, Kentucky\\/Tennessee, USA  

Microsoft Academic Search

Continuous records of discharge, specific conductance, and temperature were collected through a series of storm pulses on two limestone springs at Fort Campbell, western Kentucky\\/Tennessee, USA. Water samples, collected at short time intervals across the same storm pulses, were analyzed for calcium, magnesium, bicarbonate, total organic carbon, and pH. Chemographs of calcium, calcite saturation index, and carbon dioxide partial pressure

Dorothy J. Vesper; William B. White

2004-01-01

339

Operating a radio-frequency plasma source on water vapor.  

PubMed

A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n(i) approximately = n(e), where n(i) is the positive ion density. But in the electronegative water plasma, quasineutrality requires n(i+) = n(i-) + n(e). The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production. PMID:19725651

Nguyen, Sonca V T; Foster, John E; Gallimore, Alec D

2009-08-01

340

Operating a radio-frequency plasma source on water vapor  

SciTech Connect

A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n{sub i}{approx_equal}n{sub e}, where n{sub i} is the positive ion density. But in the electronegative water plasma, quasineutrality requires n{sub i+}=n{sub i-}+n{sub e}. The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production.

Nguyen, Sonca V. T.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States); Foster, John E. [Plasma Science and Technology Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States)

2009-08-15

341

The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method  

PubMed Central

The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

Wada, Takao; Ueda, Noriaki

2013-01-01

342

The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method.  

PubMed

The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

Wada, Takao; Ueda, Noriaki

2013-04-21

343

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

344

Unified Application Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields  

NASA Technical Reports Server (NTRS)

Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack (alpha). The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

Erickson, Gary E.

2008-01-01

345

Unified Application of Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields  

NASA Technical Reports Server (NTRS)

Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack. The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

Erickson, Gary E.

2010-01-01

346

Diffusion barriers in the kinetics of water vapor adsorption/desorption on activated carbons  

SciTech Connect

The adsorption of water vapor on a highly microporous coconut-shell-derived carbon and a mesoporous wood-derived carbon was studied. These carbons were chosen as they had markedly different porous structures. The adsorption and desorption characteristics of water vapor on the activated carbons were investigated over the relative pressure range p/p{degree} = 0--0.9 for temperatures in the range 285--313 K in a static water vapor system. The adsorption isotherms were analyzed using the Dubinin-Serpinski equation, and this provided an assessment of the polarity of the carbons. The kinetics of water vapor adsorption and desorption were studied with different amounts of preadsorbed water for set changes in pressure relative to the saturated vapor pressure (p/p{degree}). The adsorption kinetics for each relative pressure step were compared and used to calculate the activation energies for the vapor pressure increments. The kinetic results are discussed in relation to their relative position on the equilibrium isotherm and the adsorption mechanism of water vapor on activated carbons.

Harding, A.W.; Foley, N.J.; Thomas, K.M. [Univ. of Newcastle upon Tyne (United Kingdom)] [Univ. of Newcastle upon Tyne (United Kingdom); Norman, P.R.; Francis, D.C. [CBD, Salisbury (United Kingdom)] [CBD, Salisbury (United Kingdom)

1998-07-07

347

Distributed Saturation  

NASA Technical Reports Server (NTRS)

The Saturation algorithm for symbolic state-space generation, has been a recent break-through in the exhaustive veri cation of complex systems, in particular globally-asyn- chronous/locally-synchronous systems. The algorithm uses a very compact Multiway Decision Diagram (MDD) encoding for states and the fastest symbolic exploration algo- rithm to date. The distributed version of Saturation uses the overall memory available on a network of workstations (NOW) to efficiently spread the memory load during the highly irregular exploration. A crucial factor in limiting the memory consumption during the symbolic state-space generation is the ability to perform garbage collection to free up the memory occupied by dead nodes. However, garbage collection over a NOW requires a nontrivial communication overhead. In addition, operation cache policies become critical while analyzing large-scale systems using the symbolic approach. In this technical report, we develop a garbage collection scheme and several operation cache policies to help on solving extremely complex systems. Experiments show that our schemes improve the performance of the original distributed implementation, SmArTNow, in terms of time and memory efficiency.

Chung, Ming-Ying; Ciardo, Gianfranco; Siminiceanu, Radu I.

2007-01-01

348

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

Microsoft Academic Search

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

H. Orbey; S. I. Sandier

1995-01-01

349

Sulfur Concentration of Martian Magmas at Sulfide Saturation at High Pressures and Temperatures - Implications for Martian Magma Ocean and Magmatic Differentiation  

NASA Astrophysics Data System (ADS)

Sulfur is critical for a wide range of processes of terrestrial planets including thermal evolution of core and atmosphere and geochemistry of mantle and crust. For Mars, sulfur is particularly important because it may be abundant in the core [1] while SO 2 and H2 S might have exerted a strong greenhouse climate in the past [2]. A critical parameter that affects sulfur distribution during differentiation is the sulfur carrying capacity of mantle melts. However, most experiments constraining sulfur content at sulfide saturation (SCSS) are conducted on FeO poor (~5-12 wt.%) basalts [3] and recent experiments on high-FeO (~16-22 wt.%, [4]) Martian basalts are restricted to ?0.8 GPa [5]. To constrain SCSS of Martian magmas at mantle conditions, we simulated basalt-sulfide melt equilibria (S added as 15-30 wt.% FeS) in Gr capsules using a piston cylinder at 1-3 GPa and 1500-1700 °C. Two starting compositions, equivalent to olivine-phyric shergottites Yamato980459 (Y98; ~17.53 wt.% FeO) and NWA 2990 (NWA; ~16.42 wt.% FeO) and thought to be primary magma [6] were used. A composition Y98+1.4 wt.% H2O was also explored to constrain the effect of water on SCSS. All experiments produced quenched sulfide and silicate melts ± opx . FeS species in the NWA glasses was confirmed from peaks at 300-400 cm-1 in Raman spectra [7]. At 1600 °C, SCSS, measured using EPMA, decreases with pressure, 4800 to 3500 ppm from 1 to 2.5 GPa for Y98, ~5440 to 4380 ppm from 1 to 2 GPa for Y98+1.4 wt.% H2O, and 5000 to 3000 ppm from 1 to 3 GPa for NWA. At 2 GPa, SCSS of NWA increases with temperature, 3300 to 4600 ppm from 1500 to 1700 °C. Combining new and previous experiments on Martian basalts [5] (a total of 28 SCSS data with FeO* of 9.3-32.78 wt.%), a preliminary equation of the form LnS (ppm) = a + b.P + c/T +d.XSiO2 + e.XAl2O3 + f.LnXFeO was fitted, where P is in GPa, T in K, and X represents mole fraction of a given oxide. Our study suggests that at conditions of final melt-mantle equilibration [6], primary Mars basalts likely have ~2970-3480 ppm S. This implies that shergottites with 1300-2700 ppm S [4] might have either experienced sulfur degassing during the ascent thereby causing the Noachian greenhouse conditions by sulfur-rich gases or sulfide residue separation during segregation from deeper mantle sources. Furthermore, the inverse relationship of SCSS and pressure suggests that Martian magma ocean may have gained sulfur through interaction a sulfur-rich atmosphere and depositing sulfide phases at deeper part of the magma ocean. References: [1] Stewart et al. (2007) Sci., 316, 1323-1325. [2] Johnson et al. (2008) JGR, 113, 1-15. [3] Holzheid and Grove, AM, 87, 227-237. [4] Meyer (2008). Mars Meteor. Comp. [5] Righter et al. (2009) EPSL, 288, 235-243. [6] Filiberto and Dasgupta (2011) EPSL, 304, 527-537. [7] Klimm and Botcharnikov (2010) AM, 95, 1574-1579.

Ding, S.; Dasgupta, R.

2012-12-01

350

-Saturated Solutions  

NASA Astrophysics Data System (ADS)

This paper presents an electrochemical study on the corrosion behavior of API-X100 steel, heat-treated to have microstructures similar to those of the heat-affected zones (HAZs) of pipeline welding, in bicarbonate-CO2 saturated solutions. The corrosion reactions, onto the surface and through the passive films, are simulated by cyclic voltammetry. The interrelation between bicarbonate concentration and CO2 hydration is analyzed during the filming process at the open-circuit potentials. In dilute bicarbonate solutions, H2CO3 drives more dominantly the cathodic reduction and the passive films form slowly. In the concentrated solutions, bicarbonate catalyzes both the anodic and cathodic reactions, only initially, after which it drives a fast-forming thick passivation that inhibits the underlying dissolution and impedes the cathodic reduction. The significance of the substrate is as critical as that of passivation in controlling the course of the corrosion reactions in the dilute solutions. For fast-cooled (heat treatment) HAZs, its metallurgical significance becomes more comparable to that of slower-cooled HAZs as the bicarbonate concentration is higher.

Eliyan, Faysal Fayez; Alfantazi, Akram

2014-11-01

351

Saturated fat (image)  

MedlinePLUS

... saturated fats. Vegetable sources of saturated fat include coconut and palm oils. When looking at a food ... saturated fats. Vegetable sources of saturated fat include coconut and palm oils. When looking at a food ...

352

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

PubMed

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

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

2009-01-15

353

InP substrate temperature measurements in a horizontal, low-pressure metalorganic chemical vapor deposition reactor by infrared laser interferometric thermometry  

NASA Astrophysics Data System (ADS)

Infrared laser interferometric thermometry was used to measure InP substrate temperatures in a horizontal, low pressure metalorganic chemical vapor deposition (MOCVD) reactor. These measurements were made by using a 1.53 ?m distributed feedback laser, demonstrating the use of semiconductor lasers to diagnose an epitaxial crystal growth process. The laser beam was reflected off of 2 inch diameter (100) n-type InP substrates in a commercial low-pressure MOCVD reactor. Substrate temperature profiles were taken as a function of reactor pressure from 20-1000 mbar and as a function of substrate position on the susceptor. For a constant susceptor set-point temperature of 640°C, temperatures increase monotonically from 600 to 615°C at 20 mbar along the substrate in the gas flow direction, increasing to 621 to 655°C at 1000 mbar for a substrate positioned in the downstream location of a two-well susceptor used for normal epitaxial growth runs. The variation in temperature decreases when the substrate is placed in a center well susceptor. The data shows that improvements in temperature uniformity, and hence compositional uniformity can be achieved by judicious choice of substrate position and reactor pressure. In particular, uniform temperature profiles resulted in improved compositional uniformity obtained for 1.15 ?m InGaAsP layers grown on a 2 inch diameter substrate placed in the center well susceptor.

McCrary, V. R.; Donnelly, V. M.; Napholtz, S. G.; Hayes, T. R.; Davisson, P. S.; Bruno, D. C.

1992-11-01

354

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method  

NASA Astrophysics Data System (ADS)

Diamond-like carbon (DLC) films were synthesized by the dielectric barrier discharge-based plasma deposition at atmospheric pressure and their hardness and gas barrier properties were measured. A decrease in size of grains and heating substrate temperature improved nano-hardness up to 3.3 GPa. The gas barrier properties of DLC-coated poly(ethylene terephthalate) (PET) sheets were obtained by 3-5 times of non-coated PET with approximately 0.5 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

Noborisaka, Mayui; Hirako, Tomoaki; Shirakura, Akira; Watanabe, Toshiyuki; Morikawa, Masashi; Seki, Masaki; Suzuki, Tetsuya

2012-09-01

355

VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c- CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH  

EPA Science Inventory

Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

356

Electrical properties of microporous rock as a function of saturation and temperature  

NASA Astrophysics Data System (ADS)

We measured the electrical resistivity of densely welded tuff (Topopah Spring tuff) as a function of saturation by water between 23 and 145 °C. Measurements at 23-95 °C were performed at ambient pressure and measurements up to 145 °C were performed at pressures up to 5.5 MPa in an externally heated pressure vessel. Pore and confining pressures were controlled independently, allowing electrical measurements as the sample was subjected to boiling conditions. Resistivity changes associated with liquid water flashing to steam were observed. Incremental increases in resistivity with decreasing pore pressure are attributed to vapor pressure lowering caused by capillary tension in the nanometer-size pores. This result has important implications for models of reservoir engineering, geologic nuclear-waste disposal, and geophysical sensing techniques.

Roberts, Jeffery J.

2002-02-01

357

Correlations for Vapor Pressure Computation of Light and Heavy Water in the Range 40 exp 0 -214 exp 0 F.  

National Technical Information Service (NTIS)

Correlations have been obtained by the least squares method using number pairs (temperature, pressure) taken from literature. The computation model created was developed in computer IBM-1130. The results have shown deviations slightly smaller than other c...

M. J. Amaral, J. C. M. Coelho

1975-01-01

358

The Effect of Water Vapor on Flame Velocity in Equivalent Carbon Monoxide and Oxygen Mixtures  

NASA Technical Reports Server (NTRS)

This report presents the results of an investigation to study the effect of water vapor upon the spatial speed of flame in equivalent mixtures of carbon monoxide and oxygen at various total pressures from 100 to 780 mm.hg. These results show that, within this pressure range, an increase in flame speed is produced by increasing the mole fraction of water vapor at least as far as saturation at 25 degrees c., and that the rate of this increase is greater the higher the pressure. It is evident that water vapor plays an important part in the explosive oxidation of carbon monoxide; the need for further experimental evidence as to the nature of its action is indicated.

Fiock, Ernest F; King, H Kendall

1936-01-01

359

Effects of Natural Environmental Changes on Soil-Vapor Extraction Rates  

SciTech Connect

Remediation by soil-vapor extraction has been used for over a decade at Lawrence Livermore National Laboratory (LLNL). We have found that natural changes in environmental conditions affect the rate of soil-vapor extraction. Data on flow rate observations collected over this time are compared to in-situ measurements of several different environmental parameters (soil-gas pressure, soil-temperature, soil-moisture, Electrical Resistance Tomography (ERT), rainfall and barometric pressure). Environmental changes that lead to increased soil-moisture are associated with reduced soil-vapor extraction flow rates. We have found that the use of higher extraction vacuums combined with dual-phase extraction can help to increase pneumatic conductivity when vadose zone saturation is a problem. Daily changes in barometric pressure and soil-gas temperature were found to change flow rate measurements by as much as 10% over the course of a day.

Martins, S; Gregory, S

2006-03-23

360

Effects of pressure, temperature, and hydrogen during graphene growth on SiC(0001) using propane-hydrogen chemical vapor deposition  

SciTech Connect

Graphene growth from a propane flow in a hydrogen environment (propane-hydrogen chemical vapor deposition (CVD)) on SiC differentiates from other growth methods in that it offers the possibility to obtain various graphene structures on the Si-face depending on growth conditions. The different structures include the (6{radical}3 Multiplication-Sign 6{radical}3)-R30 Degree-Sign reconstruction of the graphene/SiC interface, which is commonly observed on the Si-face, but also the rotational disorder which is generally observed on the C-face. In this work, growth mechanisms leading to the formation of the different structures are studied and discussed. For that purpose, we have grown graphene on SiC(0001) (Si-face) using propane-hydrogen CVD at various pressure and temperature and studied these samples extensively by means of low energy electron diffraction and atomic force microscopy. Pressure and temperature conditions leading to the formation of the different structures are identified and plotted in a pressure-temperature diagram. This diagram, together with other characterizations (X-ray photoemission and scanning tunneling microscopy), is the basis of further discussions on the carbon supply mechanisms and on the kinetics effects. The entire work underlines the important role of hydrogen during growth and its effects on the final graphene structure.

Michon, A.; Vezian, S.; Roudon, E.; Lefebvre, D.; Portail, M. [CNRS-CRHEA, Rue Bernard Gregory, 06560 Valbonne (France)] [CNRS-CRHEA, Rue Bernard Gregory, 06560 Valbonne (France); Zielinski, M.; Chassagne, T. [NOVASiC, Savoie Technolac, Arche Bat 4, BP267, 73375 Le Bourget du Lac (France)] [NOVASiC, Savoie Technolac, Arche Bat 4, BP267, 73375 Le Bourget du Lac (France)

2013-05-28

361

Atmospheric Pressure Chemical Vapor Deposition and Jet Vapor Deposition of CdTe for High Efficiency Thin Film PV Devices: Final Technical Report, 26 January 2000 - 15 August 2002  

SciTech Connect

ITN's three-year project, Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices, had the overall objectives of improving thin-film CdTe PV manufacturing technology and increasing CdTe PV device power-conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16%-efficient CdTe PV films, i.e., close-spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstration of APCVD of CdTe films, discovery of fundamental mass-transport parameters, application of established engineering principles to the deposition of CdTe films, and verification of reactor design principles that could be used to design high-throughput, high-yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation, and ultimately, to higher device conversion efficiency and greater stability. Under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two-dimensional measurements and modeling. Accomplishments of the concluding year and extension of the APCVD subcontract included: incorporation of high-resistivity transparent buffer layers and achievement of 12.3%-efficient (NREL-measured, but not certified) devices by APCVD; analysis of scale-up issues related to APCVD, analysis of dust formation dynamics; demonstration of the inherent deficiencies of APCVD for CdTe manufacturing; modeling effects of CdSTe and SnOx layers; and electrical modeling of grain boundaries; design and construction of a low-pressure jet vapor deposition (JVD) reactor; JVD CdTe film characterization as a function of substrate and source temperature; demonstration of high growth rates using JVD; and superstrate-type and substrate-type device fabrication using low-substrate-temperature JVD CdTe films.

Woods, L; Meyers, P.

2002-08-01

362

Effective stress model for partially and fully saturated rocks  

SciTech Connect

An effective stress model which calculates the pressure-volume (P-V) and deviatoric stress response of partially and fully saturated rocks is described here. The model includes pore pressure effects on pore crushing and shear strength as well as effects of shear enhanced void collapse and shear caused dilatancy. The model can directly use tabular data for the P-V behavior of the rock solids and the water, and for the drained pore crushing behavior and shear strength, which simplifies model fitting. Phase transitions in the solids and vaporization of the water are also allowed. Use of the model is illustrated by an example of wave propagation in limestone. 6 refs., 4 figs.

Dey, T.N.

1989-01-01

363

High-throughput walkthrough detection portal for counter terrorism: detection of triacetone triperoxide (TATP) vapor by atmospheric-pressure chemical ionization ion trap mass spectrometry.  

PubMed

With the aim of improving security, a high-throughput portal system for detecting triacetone triperoxide (TATP) vapor emitted from passengers and luggage was developed. The portal system consists of a push-pull air sampler, an atmospheric-pressure chemical ionization (APCI) ion source, and an explosives detector based on mass spectrometry. To improve the sensitivity of the explosives detector, a novel linear ion trap mass spectrometer with wire electrodes (wire-LIT) is installed in the portal system. TATP signals were clearly obtained 2?s after the subject under detection passed through the portal system. Preliminary results on sensitivity and throughput show that the portal system is a useful tool for preventing the use of TATP-based improvised explosive devices by screening persons in places where many people are coming and going. PMID:21818804

Takada, Yasuaki; Nagano, Hisashi; Suzuki, Yasutaka; Sugiyama, Masuyuki; Nakajima, Eri; Hashimoto, Yuichiro; Sakairi, Minoru

2011-09-15

364

Investigations of structure and morphology of the AlN nano-pillar crystal films prepared by halide chemical vapor deposition under atmospheric pressure  

NASA Astrophysics Data System (ADS)

Aluminum nitride (AlN) prepared under atmospheric pressure using a halide chemical vapor deposition method has been examined by means of a variety of analytical techniques. Scanning electron microscopic observations showed that the crystals deposited onto a Si(100) substrate have hexagonal pillar structure. Based on the X-ray diffraction and X-ray pole-figure analyses, it was deduced that the each AlN pillar crystal grows with a different rotation angle around the <001> axis. Transmission electron diffraction showed that they are of single-like form. This was also confirmed by the selected area electron diffraction image as well. It was found that the diameter of pillar which constitutes an AlN film was significantly dependent upon the ratio of NH3/AlCl3 used as source materials and the growth temperature.

Takahashi, Naoyuki; Matsumoto, Yoriko; Nakamura, Takato

2006-04-01

365

Selective epitaxial growth of Ge/Si0.15Ge0.85 quantum wells on Si substrate using reduced pressure chemical vapor deposition  

NASA Astrophysics Data System (ADS)

We investigate the selective epitaxial growth of Ge/Si0.15Ge0.85 quantum wells on prepatterned silicon substrates by reduced pressure chemical vapor deposition. A vertical p-i-n Si0.1Ge0.9 diode with Ge/Si0.15Ge0.85 quantum wells in the intrinsic region is selectively grown in holes in a SiO2 mask. We find perfect growth selectivity and very low dependence on size or arrangement of the mask holes. The fabricated p-i-n diode shows very low reverse leakage current and high breakdown voltage, suggesting good epitaxy quality. The quantum-confined Stark effect in this quantum-well system is observed for wavelengths >1.5 ?m at room temperature.

Ren, Shen; Rong, Yiwen; Kamins, Theodore I.; Harris, James S.; Miller, David A. B.

2011-04-01

366

Modeling and Numerical Investigation of the Process of Vapor-Oxygen Gasification of Solid Fuels in a Vertical Flow Reactor Under Pressure  

NASA Astrophysics Data System (ADS)

With the use of the developed model, detailed information has been obtained on the working process in a flow reactor with single- and two-stage schemes of vapor-oxygen gasification of coals under a pressure of 3 MPa. The dependence of the ratios of mass flow rates O2/coal and H2O/coal on the type of fuel has been established and their optimal values for the "Shell" process have been found. At a given consumption ratio of gas coal and brown coal of brand B1, the optimum diameters of particles providing minimum combustible loss of the carbon mixture have been determined. It has been found that the content of methane in the syngas in the case of two-stage gasification is much higher than in the case of single-stage gasification.

Rokhman, B. B.

2014-09-01

367

Self-organization of SiO{sub 2} nanodots deposited by chemical vapor deposition using an atmospheric pressure remote microplasma  

SciTech Connect

Self-organization of SiO{sub 2} nanodots is obtained by chemical vapor deposition out of hexamethyldisiloxane (HMDSO) and atmospheric pressure remote Ar-O{sub 2} plasma operating at high temperature (1200-1600 K). The dewetting of the film being deposited when it is still thin enough (<500 nm) is found to be partly responsible for this self-organization. When the coating becomes thicker (approx1 mum), and for relatively high contents in HMDSO, SiO{sub 2} walls forming hexagonal cells are obtained on a SiO{sub 2} sublayer. For thicker coatings (>1 mum), droplet-shaped coatings with a Gaussian distribution in thickness over their width are deposited. The coatings are submitted to high compressive stress. When it is relaxed, 'nestlike structures' made of nanoribbons are synthesized.

Arnoult, G.; Belmonte, T.; Henrion, G. [Department of Physics and Chemistry of Solids and Surfaces, Institut Jean Lamour, Nancy-Universite, CNRS, Parc de Saurupt, CS 14234, F-54042 Nancy Cedex (France)

2010-03-08

368

Modeling vapor transients in heat pipes  

NASA Astrophysics Data System (ADS)

In this paper an implicit solution method for modeling transient vapor flow in a heat pipe is compared to an earlier explicit model. For both models the vapor is assumed to be spatially incompressible, compressible in time, and one dimensional. The vapor is also treated like a saturated vapor, not an ideal gas. It is shown that the implicit solution method is a factor of 102 faster than the explicit method.

Bowman, W. Jerry; Beran, Philip S.

1993-01-01

369

Adsorption of radon and water vapor on commercial activated carbons  

SciTech Connect

Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauer`s classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and relative humidity. The heat of adsorption data indicated that the PCB- and the BD-activated carbons provided a heterogeneous surface for radon adsorption. The equilibrium data for radon were correlated with a modified Freundlich equation.

Hassan, N.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Ghosh, T.K.; Hines, A.L.; Loyalka, S.K. [Univ. of Missouri, Columbia, MO (United States)

1995-02-01

370

Simultaneous effects of inlet stagnation pressure and heat transfer to the water vapor condensing flow of supersonic laval nozzle  

NASA Astrophysics Data System (ADS)

The formation of droplets in low-pressure stages of power steam turbines is due to the nucleation phenomenon and its effects, such as sudden pressure rise, also known as the condensation shock, where the irreversible internal heat transfer causes a drop in the efficiency of the turbine. Furthermore, the existence of the liquid phase causes erosion of turbine blade surfaces, and consequently, creates high mechanical costs. Therefore, proposing a solution for reducing these unwanted thermodynamic and mechanical effects is desirable. In the previous work of the authors, volumetric heating of the convergent section was introduced as an approach for reducing the mentioned damages and losses. However, further investigations revealed that heating the convergent section results in the expansion of the flow, and decreases the total mass flow rate, which is not favorable. In this paper, using semi-analytical and one dimensional modeling, the simultaneous effects of volumetric heat transfer and inlet stagnation pressure rise are investigated in order to propose a strategy for modifying this shortcoming and to stabilize the mass flow rate. The results show that for the boundary conditions used in this research, increasing the inlet stagnation pressure up to 5 percent can stabilize the mass flow rate of the non-adiabatic flow, compared to the flow in adiabatic conditions.

Rad, E. Amiri; Mahpeykar, M. R.; Teymourtash, A. R.

2012-06-01

371

Millimeter-size single-crystal graphene by suppressing evaporative loss of Cu during low pressure chemical vapor deposition.  

PubMed

Millimeter-size single-crystal monolayer graphene is synthesized on polycrystalline Cu foil by a method that involves suppressing loss by evaporation of the Cu at high temperature under low pressure. This significantly diminishes the number of graphene domains, and large single crystal domains up to ?2 mm in size are grown. PMID:23386288

Chen, Shanshan; Ji, Hengxing; Chou, Harry; Li, Qiongyu; Li, Hongyang; Suk, Ji Won; Piner, Richard; Liao, Lei; Cai, Weiwei; Ruoff, Rodney S

2013-04-11

372

Application of detonation wave theory to subcritical vapor explosions  

SciTech Connect

Detonation wave theory was applied to the physical process of a vapor explosion. Initially, the experimental observations using hot water as the fuel and saturated refrigerant liquid as the coolant were analyzed with this technique. These tests are notable since peak explosion pressures were far below the critical pressure of the coolant. From the analysis, the volume fractions of the coolant vapor and the volume ratio of the two liquids prior to the explosion were estimated from the measured peak explosion pressures and associated explosion propagation velocities under the assumption that the process was steady and one-dimensional. Complete Hugoniot curves were constructed, and the detonation condition was initially determined under the assumption that flow velocity behind the shock was equal to the mixture sound speed. This assumption was checked with the tangency condition between the Rayleigh line and Hugoniot curve at the Chapman-Jouguet point, as well as the existence of a minimum in the entropy change across the shock wave. The point of minimum entropy showed good agreement with the graphical tangency point, but was slightly different than the sound speed criteria in pressure (<2%) with a larger difference in propagation speed (50%). This discrepancy between the three criteria becomes insignificant as the explosion pressure rises. This is demonstrated by examining a tin-water explosion experiment. This technique appears to be a useful tool to estimate initial conditions for subcritical vapor explosions.

Tibkin, L.; El-Beshbeeshy, M.; Bonazza, R.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

1995-07-01

373

Generation and characteristic survey of atmospheric-pressure dry, vapor, mist plasma jet using high-frequency high-voltage power supply  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure plasma jet has attracted in the various fields for example surface treatment of materials, bacterial killing and so on. The reasons why the plasma used these applications are because it is a non-thermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. While passing through the plasma, the feed gas becomes excited, dissociated or ionized by electron impact. Once the gas exits, the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains neutral metastable species and radicals. In our previous study, GFP-7R proteins were promoted delivering into the HeLa cells by dry plasma jet. In this case, we irradiated dry plasma jet only the surface of cell suspension. Therefore, it may be expected that raising the ratio of surface area/volume exposed to plasma by to mist the cell suspension causes further improvement of protein transduction efficiency by irradiating plasma. In this study, we investigated the optimal driving parameters of the plasma jets. The length of dry, vapor, and mist plasma jets and the generated chemical species of each plasma jet will be introduced at the conference.

Takamura, Norimitsu; Wang, Douyan; Namihira, Takao; Akiyama, Hidenori

2012-10-01

374

Tides in water saturated rock  

Microsoft Academic Search

Analysis of water table records from wells or boreholes often reveals the presence of tidal fluctuations. Amplitudes of well tides can attain several centimeters when the well or borehole is open to a confined aquifer. The phenomenon reflects extension and compression cycles of the aquifer rock, i.e. volume strain tides of a water saturated formation. Besides tidal fluctuations, barometric pressure

Hans-Joachim Kctmpel

375

A Microstructural Comparison of the Initial Growth of AIN and GaN Layers on Basal Plane Sapphire and SiC Substrates by Low Pressure Metalorganic Chemical Vapor Depositon  

NASA Technical Reports Server (NTRS)

The initial growth by low pressure metalorganic chemical vapor deposition and subsequent thermal annealing of AIN and GaN epitaxial layers on SiC and sapphire substrates is examined using high resolution transmission electron microscopy and atomic force microscopy.

George, T.; Pike, W. T.; Khan, M. A.; Kuznia, J. N.; Chang-Chien, P.

1994-01-01

376

Hydrogen bonding Part 53. Correlation of differential scanning calorimetric data with IR and dissociation vapor pressure studies of transitions of hexamethonium chloride and bromide dihydrates and hexamethonium bromide monohydrate  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry of hexamethonium chloride dihydrate shows an endothermic transition of 2.70 kcal mol -1 at 36.81°C. This correlates well with the temperatures observed by IR spectra (36°C) and equilibrium dissociation vapor pressure studies (37°C) for the transition between Type I planar cluster and Type II extended linear HOH⋯Cl - hydrogen bonding, and with the value of 2.77 kcal mol -1 for this transition derived by Hess' law treatment of dissociation vapor pressure data. Differential scanning calorimetry of hexamethonium bromide shows a rapid endothermic transition of 2.38 kcal mol -1 at 35.15°C and a very slow endothermic transition of about 12-13 kcal mol -1 centered near 50°C. This latter endotherm corresponds to the transition between Type I and Type II HOH⋯Br - hydrogen bonding observed by IR and vapor pressure studies at 49°C. The nature of the 35.15°C endotherm is not known. Hexamethonium bromide also shows a third endotherm at 142.91°C, which presumably results from melting of hydrate in the sealed DSC cell. Combined analysis of differential scanning calorimetry and dissociation vapor pressure data predicts a value of about -13 kcal mol -1 for an exothermic disproportionation at 52°C of two hexamethonium bromide monohydrate to Type II dihydrate and anhydrous bromide.

Snider, Barbara L.; Harmon, Kenneth M.

1994-03-01

377

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

378

In-Situ Partial Pressure Measurements and Visual Observation during Crystal Growth of ZnSe by Seeded Physical Vapor Transport  

NASA Technical Reports Server (NTRS)

An in-situ monitoring furnace was constructed with side windows to perform partial pressure measurements by optical absorption and visual observation of the growing crystal. A fused silica -rowth ampoule with a 4.5 cm long square tube between the source and the seed was prepared for the optical absorption measurements. A ZnSe crystal was grown by the seeded physical vapor transport (PVT) technique in the horizontal configuration. The growth temperature was 1120 C and the furnace translation rate was 3nmVday. Partial pressures of Se2, P(sub Se2), at three locations along the length of the growth ampoule were measured at 90 min intervals during the growth process. The measured P (sub Se2) were in the range of 2.0 to 6.5 x 10(exp -3) atm. The P(sub Se2) results indicated that the partial pressure profile was inconsistent with the results of the one-dimensional diffusion mass transport model and that the source composition shifted toward Se-rich during the run, i.e. the grown crystal was more Zn-rich than the source. The visual observation showed that the seed crystal first etched back, with greater thermal etching occurring along the edges of the seed crystal. Once the growth started, the crystal crew in a predominately contactless mode and facets were evident during growth. The crystal did not grow symmetrically which is believed to be due to the unintentional asymmetry of the radial thermal profile in the furnace.

Su, Ching-Hua; Feth, Shari; Lehoczky, Sandor L.

1999-01-01

379

Formation of fractal structures from silicon dioxide nanoparticles synthesized by RF atmospheric pressure plasma enhanced chemical vapor deposition.  

PubMed

Fractal structures were formed on silicon substrates from SiO2 nanoparticles homogeneously synthesized in low temperature atmospheric pressure plasma from tetraethoxysilane (TEOS). RF discharge (power absorbed was about 10 W) sustained between two parallel mesh electrodes was used to generate plasma. The average size of nanoparticles was in the range of 8-20 nm and was determined by process parameters. The obtained products were analyzed by SEM (scanning electron microscopy) and XPS (X-ray photoelectron spectroscopy). Values of fractal dimension parameter of bidimensionals agglomerates formed on the substrate surface from nanoparticles were calculated with the use of Gwyddion and others. It was found that values of this parameter of the deposited structures varied in the range of 1.48-2 and were determined by combination of the process parameters. An empirical model explaining mechanism of the fractal structures formation and variation of the fractal dimension parameter with the process parameters was proposed. PMID:22097514

Alexandrov, S E; Kretusheva, I V; Mishin, M V; Yasenovets, G M

2011-09-01

380

Use of a low pressure helium/water vapor discharge as a mercury-free source of ultraviolet emission  

NASA Astrophysics Data System (ADS)

This paper presents the results of study of the longitudinal low-pressure glow discharge in a helium/water mixture. This discharge is proposed for use as a mercury-free source of ultraviolet emission. The emission spectra in the ultraviolet range are recorded by a monochromator and analyzed. In order to interpret the experimental results, the numerical modeling is carried out using global model for 46 species and 577 plasma chemical reactions between them. This model allows us to define the main reactions responsible for the generation and quenching of the excited species, which emit in the ultraviolet range. The optimal conditions are found when the lines with wavelengths of 309 nm OH(A-X) and 150-190 nm OH(X-C,B) have the largest intensity.

Levko, Dmitry; Shuaibov, Alexander; Shevera, Igor; Gritzak, Roksolana; Tsymbaliuk, Alexander

2014-09-01

381

Is CHF triggered by the vapor recoil effect?  

E-print Network

This paper deals with the triggering mechanism of the boiling crisis, a transition from nucleate to film boiling. We observe the boiling crisis in pool saturated boiling experimentally at nearly critical pressure to take advantage of the slowness of the bubble growth and of the smallness of the Critical Heat Flux (CHF) that defines the transition point. Such experiments require the reduced gravity conditions. Close to the CHF, the slow growth of the individual dry spots and their subsequent fusion on the transparent heater are observed through the latter. As discussed in the paper, these observations are consistent with numerical results obtained with the vapor recoil model of the boiling crisis.

Nikolayev, Vadim S; Chatain, D

2007-01-01

382

Molecular-dynamics evaluation of fluid-phase equilibrium properties by a novel free-energy perturbation approach: Application to gas solubility and vapor pressure of liquid hexane  

NASA Astrophysics Data System (ADS)

A novel free-energy perturbation method is developed for the computation of the free energy of transferring a molecule between fluid phases. The methodology consists in drawing a free-energy profile of the target molecule moving across a binary-phase structure built in the computer. The novelty of the method lies in the difference of the definition of the free-energy profile from the common definition. As an important element of the method, the process of making a correction to the transfer free energy with respect to the cutoff of intermolecular forces is elucidated. In order to examine the performance of the method in the application to fluid-phase equilibrium properties, molecular-dynamics computations are carried out for the evaluation of gas solubility and vapor pressure of liquid n-hexane at 298.15K. The gas species treated are methane, ethane, propane, and n-butane, with the gas solubility expressed as Henry's constant. It is shown that the method works fine and calculated results are generally in good agreement with experiments. It is found that the cutoff correction is strikingly large, constituting a dominant part of the calculated transfer free energy at the cutoff of 8Å.

Kuwajima, Satoru; Kikuchi, Hiroaki; Fukuda, Mitsuhiro

2006-03-01

383

Scalable high-mobility MoS2 thin films fabricated by an atmospheric pressure chemical vapor deposition process at ambient temperature.  

PubMed

Nano-scale MoS2 thin films are successfully deposited on a variety of substrates by atmospheric pressure chemical vapor deposition (APCVD) at ambient temperature, followed by a two-step annealing process. These annealed MoS2 thin films are characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), micro-Raman, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-VIS-NIR spectrometry, photoluminescence (PL) and Hall Effect measurement. Key optical and electronic properties of APCVD grown MoS2 thin films are determined. This APCVD process is scalable and can be easily incorporated with conventional lithography as the deposition is taking place at room temperature. We also find that the substrate material plays a significant role in the crystalline structure formation during the annealing process and single crystalline MoS2 thin films can be achieved by using both c-plane ZnO and c-plane sapphire substrates. These APCVD grown nano-scale MoS2 thin films show great promise for nanoelectronic and optoelectronic applications. PMID:25226424

Huang, Chung-Che; Al-Saab, Feras; Wang, Yudong; Ou, Jun-Yu; Walker, John C; Wang, Shuncai; Gholipour, Behrad; Simpson, Robert E; Hewak, Daniel W

2014-10-01

384

Scalable high-mobility MoS2 thin films fabricated by an atmospheric pressure chemical vapor deposition process at ambient temperature  

NASA Astrophysics Data System (ADS)

Nano-scale MoS2 thin films are successfully deposited on a variety of substrates by atmospheric pressure chemical vapor deposition (APCVD) at ambient temperature, followed by a two-step annealing process. These annealed MoS2 thin films are characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), micro-Raman, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-VIS-NIR spectrometry, photoluminescence (PL) and Hall Effect measurement. Key optical and electronic properties of APCVD grown MoS2 thin films are determined. This APCVD process is scalable and can be easily incorporated with conventional lithography as the deposition is taking place at room temperature. We also find that the substrate material plays a significant role in the crystalline structure formation during the annealing process and single crystalline MoS2 thin films can be achieved by using both c-plane ZnO and c-plane sapphire substrates. These APCVD grown nano-scale MoS2 thin films show great promise for nanoelectronic and optoelectronic applications.

Huang, Chung-Che; Al-Saab, Feras; Wang, Yudong; Ou, Jun-Yu; Walker, John C.; Wang, Shuncai; Gholipour, Behrad; Simpson, Robert E.; Hewak, Daniel W.

2014-10-01

385

Photoinduced current transient spectroscopy of deep levels and transport mechanisms in iron-doped GaN thin films grown by low pressure-metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Electrical transport and deep levels are investigated in GaN:Fe layers epitaxially grown on sapphire by low pressure metalorganic vapor phase epitaxy. Photoinduced current transient spectroscopy and current detected deep level spectroscopy are performed between 200 and 650 K on three Fe-doped samples and an undoped sample. A detailed study of the detected deep levels assigns dominant centers to a deep donor 1.39 eV below the conduction band edge EC and to a deep acceptor 0.75 eV above the valence band edge EV at low electric field. A strong Poole-Frenkel effect is evidenced for the donor. Schottky diodes characteristics and transport properties in the bulk GaN:Fe layer containing a homogenous concentration of 1019 Fe/cm3 are typical of a compensated semiconductor. They both indicate that the bulk Fermi level is located typically 1.4 eV below EC, in agreement with the neutrality equation and dominance of the deep donor concentration. This set of results demonstrates unambiguously that electrical transport in GaN:Fe is governed by both types, either donor or acceptor, of the iron impurity, either substitutional in gallium sites or associated with other defects.

Muret, P.; Pernot, J.; Azize, M.; Bougrioua, Z.

2007-09-01

386

Vacuum vapor deposition  

NASA Technical Reports Server (NTRS)

A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

Poorman, Richard M. (inventor); Weeks, Jack L. (inventor)

1995-01-01

387

Combining vapor pressure and evaporimetric methods to generate swrc - and its application to interprete soil moisture data in hydrologic studies  

NASA Astrophysics Data System (ADS)

Transport of soil water affects heat and solute transport in soils, also it de?nes rates of biological processes in soil and water supply to plants, over transpiration and ground water replenishment, controls runoff, and has many other important functions in the environment. Therefore, the knowledge of soil water storage and its movement inside the matrix have many applications in hydrology, meteorology, agronomy, environmental protection, and other soil-related disciplines. The aim of this research is to evaluate the combination of two different methods to obtain the complete water retention characteristic curve for a silt loam soil under laboratory conditions. The first method used for wetting part of the curve is the HYPROP System. This method is based on evaporation rates (Wind, 1968), i.e. loss water by evaporation and in some cases by plant transpiration as well. The evaporation method of Schindler (1980) is a simplification of the Wind (1968) approach. Tension is measured at two depths within a short soil column device (250 cm3), evaporating water from its surface, and taking the measured with two micro-tensiometers. Water content is determined by weighing in a accurate scale (0.01 g). The change in sample mass or water loss from the sample during evaporation is the ground for deriving soil water retention curve up to tensions <100 kPa. A second method to obtain the driest part of the soil water characteristic curve was used. The method is called the vapour pressure method, using for it a dew point hygrometer WP4C. This device measures dew point temperature of air in vapour equilibrium with a soil sample and sample temperature to determine relative humidity. The relative humidity of air in vapour equilibrium with the sample should be related to water potential by the Kelvin equation. Using specific Hyprop Data Evaluation software both types of data (HYPROP and WP4C) can be related and fitted to several hydraulic models. In our case, we used an unconstrained closed form from Van Genuchten (1980). The quality of the fits was quantified in the group in terms of the root mean square error calculated for the water content data. To sum up, the application of both methods allowed obtaining the soil moisture characteristic curve for this kind of soil. The outstanding features were a faster reach the complete curve, a small performance was carried out to assemble the devices, and especially the time consuming, such that only needs less than one week to achieve one curve accurately. On the other hand, some weakness of the methodology used could be to obtain good unaltered samples and reliable weights of them. Some variations on the data could prompt a low accurate results and high uncertainty.

Rubio, C. M.; Ferrer, F.

2012-04-01

388

Stabilization of the emission frequency of a high-pressure waveguide CO/sub 2/ laser with the aid of resonances of saturated absorption in /sup 192/OsO/sub 4/ molecules  

SciTech Connect

The emission frequency of a high-pressure waveguide CO/sub 2/ laser was stabilized using resonances of saturated absorption of the P(14) CO/sub 2/ line in /sup 192/OsO/sub 4/. The heterodyne method was used to measure (to within 2 x 10/sup -10/) the relative frequency of a new strong resonance corresponding to the A/sub 2//sup 2/ P(46) transition from the ground state of the /sup 192/OsO/sub 4/ molecule. The measurements were made relative to a narrow resonance of /sup 192/OsO/sub 4/ located near the center of the P(14) CO/sub 2/ line profile and corresponding to a transition from an excited state. The precision of the measurements was probably limited by stray amplitude modulation resulting from misalignment of the laser resonator caused by the operation of a piezoelectric ceramic plate.

Bazarov, E.N.; Gerasimov, G.A.; Gubin, V.P.; Sazonov, A.I.; Starostin, N.I.; Fomin, V.V.

1980-12-01

389

Atmospheric pressure chemical vapor deposition of CdTe for high efficiency thin film PV devices: Annual subcontract report, 26 January 1999--25 January 2000  

SciTech Connect

ITN's three year project Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices has the overall objectives of improving thin film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16% efficient CdTe PV films, i.e., close spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstration of APCVD of CdTe films, discovery of fundamental mass transport parameters, application of established engineering principles to the deposition of CdTe films, and verification of reactor design principles which could be used to design high throughput, high yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation and ultimately to higher device conversion efficiency and greater stability. Under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two dimension measurements and modeling. Accomplishments of the second year of the APCVD subcontract include: deposition of the first APCVD CdTe; identification of deficiencies in the first generation APCVD reactor; design, fabrication and testing of a ``simplified'' APCVD reactor; deposition of the first dense, adherent APCVD CdTe films; fabrication of the first APCVD CdTe PV device; modeling effects of CdSTe and SnOx layers; and electrical modeling of grain boundaries.

Meyers, P. V.; Kee, R.; Wolden, C.; Kestner, J.; Raja, L.; Kaydanov, V.; Ohno, T.; Collins, R.; Fahrenbruch, A.

2000-05-30

390

Vapor Pressure measurements for dichlorosilane  

E-print Network

; proprietary), a procedure was developed that would allow the Inixture to enter a well-stirred bath of a basic solution. A diagram of this system is provided as Figure 6. Baking soda was mixed in a large container with water that was stirred by a motor... was partially completed during the first stage of system preparation. While the temperature was increasing in the cell, and the system evacuated, baking soda and water was added to the bath. Several months had passed since the last usage of the container, so...

Morris, Tony Knimbula

2012-06-07

391

Pressure Field Study of the Tevatron Cold Compressors  

Microsoft Academic Search

The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations. The compressor is designed to pump 60 g\\/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g\\/sec. Operating speeds are between 40,000 and 95,000 rpm, with a

A. L. Klebaner; A. Martinez; W. M. Soyars; J. C. Theilacker

2004-01-01

392

Pressure field study of the Tevatron cold compressors  

Microsoft Academic Search

The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations [1]. The compressor is designed to pump 60 g\\/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g\\/sec. Operating speeds are between 40 and 95 krpm, with

A. L. Klebaner; A. Martinez; W. M. Soyars; J. C. Theilacker

2003-01-01

393

Passive Vaporizing Heat Sink  

NASA Technical Reports Server (NTRS)

A passive vaporizing heat sink has been developed as a relatively lightweight, compact alternative to related prior heat sinks based, variously, on evaporation of sprayed liquids or on sublimation of solids. This heat sink is designed for short-term dissipation of a large amount of heat and was originally intended for use in regulating the temperature of spacecraft equipment during launch or re-entry. It could also be useful in a terrestrial setting in which there is a requirement for a lightweight, compact means of short-term cooling. This heat sink includes a hermetic package closed with a pressure-relief valve and containing an expendable and rechargeable coolant liquid (e.g., water) and a conductive carbon-fiber wick. The vapor of the liquid escapes when the temperature exceeds the boiling point corresponding to the vapor pressure determined by the setting of the pressure-relief valve. The great advantage of this heat sink over a melting-paraffin or similar phase-change heat sink of equal capacity is that by virtue of the =10x greater latent heat of vaporization, a coolant-liquid volume equal to =1/10 of the paraffin volume can suffice.

Knowles, TImothy R.; Ashford, Victor A.; Carpenter, Michael G.; Bier, Thomas M.

2011-01-01

394

Condensation coefficient of methanol vapor near vapor-liquid equilibrium states  

NASA Astrophysics Data System (ADS)

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

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

395

Pressure  

NSDL National Science Digital Library

This lab is not inquiry-based because the teacher must explain how to calculate pressure before doing the activity, but the lab gives students a great concept of what PSI means. They usually have no idea if 10 PSI is a lot or a little. They also don't und

Horton, Michael

2009-05-30

396

Fuel Vaporization Effects  

NASA Technical Reports Server (NTRS)

A study of the effects of fuel-air preparation characteristics on combustor performance and emissions at temperature and pressure ranges representative of actual gas turbine combustors is discussed. The effect of flameholding devices on the vaporization process and NOx formation is discussed. Flameholder blockage and geometry are some of the elements that affect the recirculation zone characteristics and subsequently alter combustion stability, emissions and performance. A water cooled combustor is used as the test rig. Preheated air and Jet A fuel are mixed at the entrance of the apparatus. A vaporization probe is used to determine percentage of vaporization and a gas sample probe to determine concentration of emissions in the exhaust gases. The experimental design is presented and experimental expected results are discussed.

Bosque, M. A.

1983-01-01

397

Droplet Vaporization in a Supercritical Microgravity Environment  

NASA Technical Reports Server (NTRS)

A model is presented which describes single liquid droplet vaporization at nearly critical liquid pressures and temperatures. A modified Redlich-Kwong equation of state is used to evaluate the fugacities and liquid and vapor mole fractions at the interface under the assumption of interface equilibrium. Results obtained for different droplet sizes and conditions indicate significant differences in behavior in comparison with low-pressure quasi-steady droplet vaporization.

Curtis, E. W.; Farrell, P. V.

1987-01-01

398

Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer  

Microsoft Academic Search

The Al-in-hornblende barometer, which correlates Altot content of magmatic hornblende linearly with crystallization pressure of intrusion (Hammarstrom and Zen 1986), has been calibrated experimentally under water-saturated conditions at pressures of 2.5–13 kbar and temperatures of 700–655°C. Equilibration of the assemblage hornlende-biotite-plagioclase-orthoclasequartz-sphene-Fe-Ti-oxide-melt-vapor from a natural tonalite 15–20° above its wet solidus results in hornblende compositions which can be fit by the

Max W. Schmidt

1992-01-01

399

Saturation diving; physiology and pathophysiology.  

PubMed

In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia may lead to the production of reactive oxygen species (ROS) that interact with cell structures, causing damage to proteins, lipids, and nucleic acid. Vascular gas-bubble formation and hyperoxia may lead to dysfunction of the endothelium. The antioxidant status of the diver is an important mechanism in the protection against injury and is influenced both by diet and genetic factors. The factors mentioned above may lead to production of heat shock proteins (HSP) that also may have a negative effect on endothelial function. On the other hand, there is a great deal of evidence that HSPs may also have a "conditioning" effect, thus protecting against injury. As people age, their ability to produce antioxidants decreases. We do not currently know the capacity for antioxidant defense, but it is reasonable to assume that it has a limit. Many studies have linked ROS to disease states such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, and atherosclerosis as well as to old age. However, ROS are also involved in a number of protective mechanisms, for instance immune defense, antibacterial action, vascular tone, and signal transduction. Low-grade oxidative stress can increase antioxidant production. While under pressure, divers change depth frequently. After such changes and at the end of the dive, divers must follow procedures to decompress safely. Decompression sickness (DCS) used to be one of the major causes of injury in saturation diving. Improved decompression procedures have significantly reduced the number of reported incidents; however, data indicate considerable underreporting of injuries. Furthermore, divers who are required to return to the surface quickly are under higher risk of serious injury as no adequate decompression procedures for such situations are available. Decompression also leads to the production of endothelial microparticles that may reduce endothelial function. As good endothelial function is a documented indicator of health that can be influenced by regular exercise, regular physical exercise is recommended for saturation divers. Nowadays, saturation diving is a reasonably safe and well controlled method for working under water. Until now, no long-term impact on health due to diving has been documented. However, we still have limited knowledge about the pathophysiologic mechanisms involved. In particular we know little about the effect of long exposure to hyperoxia and microparticles on the endothelium. PMID:24944036

Brubakk, Alf O; Ross, John A S; Thom, Stephen R

2014-07-01

400

Gluon saturation in a saturated environment  

SciTech Connect

A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q{sub sA}{sup 2}, in AA compared with pA collisions.

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan [Departamento de Fisica Universidad Tecnica Federico Santa Maria (Chile) and Instituto de Estudios Avanzados en Ciencias e Ingenieria (Chile) and Centro Cientifico-Tecnologico de Valparaiso; Casilla 110-V, Valparaiso (Chile)

2011-07-15

401

Free-jet expansions from laser-vaporized planar surfaces  

NASA Technical Reports Server (NTRS)

Characteristics of free-jet vapor expansions created by the pulsed-laser vaporization of some refractory materials are examined. Such expansions were generated from planar surfaces at laser power densities up to 2.5 MW/sq cm. Time-integrated and time-resolved photography were used to show that the structure and pressures of such flows are correlated by the same relationship that is valid for free jets from orifice flows. Data show that the vapor velocity becomes sonic at or very near the vaporizing surface. A method is presented for deriving vaporization pressure from flow-field photos; such pressures from carbon-vaporization data for temperatures to 4500 K are in good agreement with extrapolated equilibrium vapor pressures. It is shown that this technique may be a means to determine vapor pressures of refractory materials at high temperatures.

Covington, M. A.; Liu, G. N.; Lincoln, K. A.

1976-01-01

402

Vapor phase heat transport systems  

NASA Astrophysics Data System (ADS)

Progress in theoretical and experimental investigations of various forms of a vapor transport system for solar space heating is described, which could also be applied to service water heating. The refrigerant is evaporated in a solar collector, which may be located on the external wall or roof of a building. The vapor is condensed in a passively discharged thermal storage unit located within the building. The condensed liquid can be returned to the collector either by a motor-driven pump or by a completely passive self-pumping mechanism in which the vapor pressure lifts the liquid from the condenser to the collector. The theoretical investigation analyzes this self-pumping scheme. Experiments in solar test cells compared the operation of both passive and active forms of the vapor system with the operation of a passive water wall. The vapor system operates as expected, with potential advantages over other passive systems in design flexibility and energy yield.

Hedstrom, J. C.; Neeper, D. A.

1985-09-01

403

42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...  

Code of Federal Regulations, 2011 CFR

(a) The completely assembled respirator will be worn in a chamber containing 0.1 ±0.025 percent isoamyl acetate vapor, the intake of the hose will be connected to a suitable source of respirable air, and not more than 25 percent of the hose length will be located in isoamyl acetate-free...

2011-10-01

404

42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...  

Code of Federal Regulations, 2013 CFR

(a) The completely assembled respirator will be worn in a chamber containing 0.1 ±0.025 percent isoamyl acetate vapor, the intake of the hose will be connected to a suitable source of respirable air, and not more than 25 percent of the hose length will be located in isoamyl acetate-free...

2013-10-01

405

42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...  

Code of Federal Regulations, 2012 CFR

(a) The completely assembled respirator will be worn in a chamber containing 0.1 ±0.025 percent isoamyl acetate vapor, the intake of the hose will be connected to a suitable source of respirable air, and not more than 25 percent of the hose length will be located in isoamyl acetate-free...

2012-10-01

406

Vaporizer performance  

NASA Astrophysics Data System (ADS)

This paper examines the nature of the flow leaving a vaporizer, its dependence on the flowrates of air and kerosene fuel, the inlet air temperature, and the possible consequences for the performance of a combustor fueled by the vaporizer. A phase Doppler velocimeter was used to examine the distribution of droplet diameters, velocities of the droplets, and the liquid-fuel flux at the exit. Measurements are also reported which show the nature of the two-phase flow away from the vaporizer exits and in important regions within a combustor corresponding to a one-sixth annular sector of a reverse-flow arrangement. The distribution of droplets within the combustor was observed and photographs of the combusting flow are presented.

Liu, C. H.; Perez-Ortiz, B. M.; Whitelaw, J. H.

407

Collapse of large vapor bubbles  

NASA Technical Reports Server (NTRS)

The refilling of propellant tanks while in a low-gravity environment requires that entrapped vapor bubbles be collapsed by increasing the system pressure. Tests were performed to verify the mechanism of collapse for these large vapor bubbles with the thermodynamic conditions, geometry, and boundary conditions being those applicable to propellant storage systems. For these conditions it was found that conduction heat transfer determined the collapse rate, with the specific bubble geometry having a significant influence.

Tegart, J.; Dominick, S.

1982-01-01

408

Sensing and characterization of explosive vapors near 700 cm-1  

Microsoft Academic Search

One of the technological challenges associated with trace vapor detection of explosive materials are the relatively low vapor pressures exhibited by most energetic materials under ambient conditions. For example, the vapor pressure for TNT is ~10 ppbv at room temperature, a concentration near the Limit of Detection for many of the technologies currently being deployed. In the case of improvised

Alan R. Ford; Scott W. Reeve

2007-01-01

409

Vapor generation methods for explosives detection research  

SciTech Connect

The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

2012-12-01

410

Storm pulse chemographs of saturation index and carbon dioxide pressure: implications for shifting recharge sources during storm events in the karst aquifer at Fort Campbell, Kentucky/Tennessee, USA  

NASA Astrophysics Data System (ADS)

Continuous records of discharge, specific conductance, and temperature were collected through a series of storm pulses on two limestone springs at Fort Campbell, western Kentucky/Tennessee, USA. Water samples, collected at short time intervals across the same storm pulses, were analyzed for calcium, magnesium, bicarbonate, total organic carbon, and pH. Chemographs of calcium, calcite saturation index, and carbon dioxide partial pressure were superimposed on the storm hydrographs. Calcium concentration and specific conductance track together and dip to a minimum either coincident with the peak of the hydrograph or lag slightly behind it. The CO2 pressure continues to rise on the recession limb of the hydrograph and, as a result, the saturation index decreases on the recession limb of the hydrograph. These results are interpreted as being due to dispersed infiltration through CO2-rich soils lagging the arrival of quickflow from sinkhole recharge in the transport of storm flow to the springs. Karst spring hydrographs reflect not only the changing mix of base flow and storm flow but also a shift in source of recharge water over the course of the storm. L'enregistrement en continu du débit, de la conductivité et de la température de l'eau a été réalisé au cours d'une série de crues à deux sources émergeant de calcaires, à Fort Campbell (Kentucky occidental, Tennessee, États-Unis). Des échantillons d'eau, prélevés à de courts pas de temps lors de ces crues, ont été analysés pour le calcium, le magnésium, les bicarbonates, le carbone organique total et le pH. Les chimiogrammes de calcium, d'indice de saturation de la calcite et de la pression partielle en CO2 ont été superposés aux hydrogrammes de crue. La concentration en calcium et la conductivité de l'eau se suivent bien et passent par un minimum correspondant au pic de l'hydrogramme ou légèrement retardé. La pression partielle en CO2 continue de croître au cours de la récession de l'hydrogramme de même que l'indice de saturation de la calcite décroît. Ces résultats sont interprétés comme étant dus à l'infiltration dispersée au travers de sols riches en CO2, décalée par rapport à l'arrivée de l'écoulement rapide provenant de la recharge, à partir d'une perte, de l'écoulement de crue vers les sources. Les hydrogrammes de sources karstiques ne reflètent pas seulement le mélange variable de l'écoulement de base et de l'écoulement de crue, mais également un changement d'origine de l'eau de la recharge au cours de l'épisode de crue. Se ha registrado en continuo la descarga, conductancia específica y temperatura de una serie de episodios de tormenta en dos manantiales en calizas ubicados en Fort Campbell, en el oeste de Kentucky/Tennessee (Estados Unidos de América). Se ha analizado muestras de agua recogidas en breves intervalos de tiempo durante los episodios de tormenta, determinando el calcio, magnesio, bicarbonato, carbono orgánico total y pH. Se ha superpuesto quimiogramas de calcio, índice de saturación en calcita y presión parcial de dióxido de carbono en los hidrogramas de las tormentas. La concentración de calcio y la conductancia específica se comportan de forma similar y presentan un mínimo que coincide también con un pico del hidrograma o que se retrasa ligeramente con respecto a él. La presión de dióxido de carbono sigue aumentando en la rama de recesión del hidrograma y, como consecuencia, disminuye el índice de saturación de la rama de recesión del hidrograma. Se interpreta que estos resultados son debidos a la infiltración dispersa a través de suelos enriquecidos en dióxido de carbono que retrasan el flujo rápido desde la recarga en los sumideros hasta su afloramiento en los manantiales. Los hidrogramas en manantiales kársticos reflejan no sólo la mezcla cambiante del flujo de base y el de tormenta, sino también el cambio en el origen del agua de recarga durante el curso de la tormenta.

Vesper, Dorothy J.; White, William B.

411

Plasma enhanced chemical vapor deposition of TiO 2 films on silica gel powders at atmospheric pressure in a circulating fluidized bed reactor  

Microsoft Academic Search

Anatase TiO2 thin films were deposited on silica gel powders by plasma enhanced chemical vapor deposition (PECVD) method in a circulating fluidized bed (CFB) reactor using TTIP [Ti(O-i-C3H7)4] and oxygen without any post-treatment. The optimum solid circulation rates were determined for the stable He-plasma glow discharge with He fluidizing gas. The optimum deposition conditions of TiO2 thin films by PECVD

Gook Hee Kim; Sang Done Kim; Soung Hee Park

2009-01-01

412

Phase relations in the carbon-saturated C-Mg-Fe-Si-O system and C and Si solubility in liquid Fe at high pressure and temperature: implications for planetary interiors  

NASA Astrophysics Data System (ADS)

The phase and melting relations of the C-saturated C-Mg-Fe-Si-O system were investigated at high pressure and temperature to understand the role of carbon in the structure of the Earth, terrestrial planets, and carbon-enriched extraterrestrial planets. The phase relations were studied using two types of experiments at 4 GPa: analyses of recovered samples and in situ X-ray diffractions. Our experiments revealed that the composition of metallic iron melts changes from a C-rich composition with up to about 5 wt.% C under oxidizing conditions (?IW = -1.7 to -1.2, where ?IW is the deviation of the oxygen fugacity ( fO2) from an iron-wüstite (IW) buffer) to a C-depleted composition with 21 wt.% Si under reducing conditions (?IW < -3.3) at 4 GPa and 1,873 K. SiC grains also coexisted with the Fe-Si melt under the most reducing conditions. The solubility of C in liquid Fe increased with increasing fO2, whereas the solubility of Si decreased with increasing fO2. The carbon-bearing phases were graphite, Fe3C, SiC, and Fe alloy melt (Fe-C or Fe-Si-C melts) under the redox conditions applied at 4 GPa, but carbonate was not observed under our experimental conditions. The phase relations observed in this study can be applicable to the Earth and other planets. In hypothetical reducing carbon planets (?IW < -6.2), graphite/diamond and/or SiC exist in the mantle, whereas the core would be an Fe-Si alloy containing very small amount of C even in the carbon-enriched planets. The mutually exclusive nature of C and Si may be important also for considering the light elements of the Earth's core.

Takahashi, Suguru; Ohtani, Eiji; Terasaki, Hidenori; Ito, Yoshinori; Shibazaki, Yuki; Ishii, Miho; Funakoshi, Ken-ichi; Higo, Yuji

2013-09-01

413

Heat transfer during film condensation of potassium vapor  

E-print Network

The object of this work is to investigate theoretically and experimentally the following two phases of heat transfer during condensation of potassium vapore, a. Heat transfer during film condensation of pure saturated ...

Kroger, Detlev Gustav

1966-01-01

414

A colorimetric sensor array for detection of triacetone triperoxide vapor.  

PubMed

Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample preparation, or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquantitative analysis from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decomposition products (e.g., H(2)O(2)) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its saturation vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile organic compounds, etc.) do not generate an array response, and the array can also differentiate TATP from other chemical oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid). PMID:20949933

Lin, Hengwei; Suslick, Kenneth S

2010-11-10

415

A constitutive model for partially saturated soils  

Microsoft Academic Search

The Paper presents a constitutive model for describing the stress-strain behaviour of partially saturated soils. The model is formulated within the framework of hardening plasticity using two iode- pendent sets of stress variables: the excess of total stress over air pressure and the suction. The mode1 is able to represent, in a consistent and unified manner, many of the fundamental

E. E. ALONSO; A. GENS; A. JOSA

1990-01-01

416

Effective thermal conductivity of fully and partially saturated metal wicks  

NASA Technical Reports Server (NTRS)

The purpose of the study is threefold: (1) to perform accurate experiments covering a wide range of porosities to determine the effective thermal conductivity of sintered fiber porous metals fully saturated with air, water, and water vapor; (2) to propose correlations for these cases, and to compare these correlations with existing analytical predictions, experimental correlations and data; and (3) to determine the effective thermal conductivity of porous metals partially saturated with water and water vapor, respectively. The experimental apparatus, based on the steady-state method of comparison, is designed and used for determining the effective thermal conductivity. The wicks are made of nickel 200, stainless steel 430, and copper, covering a porosity range 0.30-0.67. Based on the experimental results, a single correlation is derived for predicting the effective thermal conductivity of all wicks fully saturated with air, water, and water vapor. For two partially saturated wick specimens with both high porosity and large matrix thermal conductivity, a liquid-vapor transition zone is observed between the phases, which increases the total combined effective thermal conductivity of the specimen.

Kar, K.; Dybbs, A.

1978-01-01

417

Colors of maximal saturation.  

PubMed

The spectrum locus on the CIE Chromaticity Diagram represents monochromatic stimuli which have been exposed to a dark adapted fovea. Some of these colors can be made to appear more saturated by chromatic adaptation. The colors both inside the spectrum locus and the supersaturated colors outside are bounded by a four-sided boundary line which constitutes the locus of colors of maximal saturation. An attempt has been made to show how this quadrilateral is related to the fundamental colors and to a zone theory of color vision. PMID:8539020

Fry, G A

1995-08-01

418

Solubility and equilibrium vapor pressures of HC1 dissolved in polar stratospheric cloud materials - Ice and the trihydrate of nitric acid  

NASA Technical Reports Server (NTRS)

Measurements of the pressure-solubility behavior of HC1 in water ice and in the nitric acid trihydrate (NAT) crystal at 200 K are reported. It was found that HC1 is about 20 times more soluble in NAT than in ice for stratospheric conditions. A relation between HC1 pressure and substrate composition based on the Gibbs-Duhem equation is developed. This relation, along with other thermodynamic data, can be used to obtain the HC1 pressure-solubility behavior at different temperatures. Implications of these results for the south polar ozone hole are discussed.

Hanson, David; Mauersberger, Konrad

1988-01-01

419

Metamaterial saturable absorber mirror.  

PubMed

We propose a metamaterial saturable absorber mirror at midinfrared wavelengths that can show a saturation of absorption with intensity of incident light and switch to a reflecting state. The design consists of an array of circular metallic disks separated by a thin film of vanadium dioxide (VO(2)) from a continuous metallic film. The heating due to the absorption in the absorptive state causes the VO(2) to transit to a metallic phase from the low temperature insulating phase. The metamaterial switches from an absorptive state (R?0.1%) to a reflective state (R>95%) for a specific threshold intensity of the incident radiation corresponding to the phase transition of VO(2), resulting in the saturation of absorption in the metamaterial. The computer simulations show over 99.9% peak absorbance, a resonant bandwidth of about 0.8 ?m at 10.22 ?m wavelengths, and saturation intensity of 140 mW cm(-2) for undoped VO(2) at room temperature. We also carried out numerical simulations to investigate the effects of localized heating and temperature distribution by solving the heat diffusion problem. PMID:23381408

Dayal, Govind; Ramakrishna, S Anantha

2013-02-01

420

THE ROLE OF INERTIAL CAVITATION IN ACOUSTIC DROPLET VAPORIZATION  

PubMed Central

The vaporization of a superheated droplet emulsion into gas bubbles using ultrasound – termed acoustic droplet vaporization (ADV) – has potential therapeutic applications in embolotherapy and drug delivery. The optimization of ADV for therapeutic applications can be enhanced by understanding the physical mechanisms underlying ADV, which are currently not clearly elucidated. Acoustic cavitation is one possible mechanism. This paper investigates the relationship between the ADV and inertial cavitation (IC) thresholds (measured as peak rarefactional pressures) by studying parameters that are known to influence the IC threshold. These parameters include bulk fluid properties such as gas saturation, temperature, viscosity, and surface tension; droplet parameters such as degree of superheat, surfactant type, and size; and acoustic properties such as pulse repetition frequency and pulse width. In all cases the ADV threshold occurred at a lower rarefactional pressure than the IC threshold indicating that the phase-transition occurs before IC events. The viscosity and temperature of the bulk fluid are shown to influence both thresholds directly and inversely, respectively. An inverse trend is observed between threshold and diameter for droplets in the 1 to 2.5 ? range. Based on a choice of experimental parameters, it is possible to achieve ADV with or without IC. PMID:19473917

Fabiilli, Mario L.; Haworth, Kevin J.; Fakhri, Nasir H.; Kripfgans, Oliver D.; Carson, Paul L.; Fowlkes, J. Brian

2011-01-01

421

Investigation of sodium carbonate, sodium bicarbonate and water systems for saturated solar ponds. Final report  

SciTech Connect

The overall objective of this study was to gather relevant data primarily from the published literature to investigate the technical feasibility of using a Na/sub 2/CO/sub 3/-NaHCO/sub 3/ mixture for a saturated solar pond. This objective was accomplished by a literature search and review of existing chemical information and by performing simple chemistry experiments in the laboratory. Information on density, solubility, phase diagram, equilibrium compositions, reaction rate constant, equilibrium constant, diffusion coefficient, vapor pressure and potentially useful additives is compiled. It is concluded that even though both the saturation density and solubility increase with temperature for trona, it is not chemically stable either at room temperature or higher temperatures (80/sup 0/C). Therefore, as is, trona is not suitable for use in a saturated solar pond. From the literature it has been found that sugar and gum can retard the decomposition of bicarbonate to carbonate in the mixture. Nevertheless, trona is a very attractive solute for an unsaturated solar pond. A laboratory unsaturated pond with a stable density gradient has worked without any problems for about two months at InterTechnology/Solar Corporation.

None

1980-03-28

422

Water vapor adsorption on plutonium dioxide  

Microsoft Academic Search

Adsorption isotherms of water vapor on plutonium dioxide were measured ; gravimetrically at 30, 50, and 85 deg C. The data show water to be irreversibly ; chemisorbed until the oxide is saturated. Any subsequent adsorption is physical ; and completely reversible. The chemisorbed limit varied from 1 monolayer at 85 ; deg C to 3 monolayers at 30 deg

J. L. Stakebake; L. M. Steward

1973-01-01

423

Multilead, Vaporization-Cooled Soldering Heat Sink  

NASA Technical Reports Server (NTRS)

Vaporization-cooled heat sink proposed for use during soldering of multiple electrical leads of packaged electronic devices to circuit boards. Heat sink includes compliant wicks held in grooves on edges of metal fixture. Wicks saturated with water. Prevents excessive increases in temperature at entrances of leads into package.

Rice, John

1995-01-01

424

Vaporization Would Cool Primary Battery  

NASA Technical Reports Server (NTRS)

Temperature of discharging high-power-density primary battery maintained below specified level by evaporation of suitable liquid from jacket surrounding battery, according to proposal. Pressure-relief valve regulates pressure and boiling temperature of liquid. Less material needed in cooling by vaporization than in cooling by melting. Technique used to cool batteries in situations in which engineering constraints on volume, mass, and location prevent attachment of cooling fins, heat pipes, or like.

Bhandari, Pradeep; Miyake, Robert N.

1991-01-01

425

WAVES IN PARTIALLY SATURATED POROUS MEDIA James G. Berryman \\Lambday  

E-print Network

WAVES IN PARTIALLY SATURATED POROUS MEDIA James G. Berryman \\Lambday in Wave Propagation saturated porous media and the reasons for needing such a theory are also discussed. The main results are these: (a) Using the physically reasonable assumption of negligible capillary pressure change during

426

Water Vapor Effects on Silica-Forming Ceramics  

NASA Technical Reports Server (NTRS)

Silica-forming ceramics such as SiC and Si3N4 are proposed for applications in combustion environments. These environments contain water vapor as a product of combustion. Oxidation of silica-formers is more rapid in water vapor than in oxygen. Parabolic oxidation rates increase with the water vapor partial pressure with a power law exponent value close to one. Molecular water vapor is therefore the mobile species in silica. Rapid oxidation rates and large amounts of gases generated during the oxidation reaction in high water vapor pressures may result in bubble formation in the silica and nonprotective scale formation. It is also shown that silica reacts with water vapor to form Si(OH)4(g). Silica volatility has been modeled using a laminar flow boundary layer controlled reaction equation. Silica volatility depends on the partial pressure of water vapor, the total pressure, and the gas velocity. Simultaneous oxidation and volatilization reactions have been modeled with paralinear kinetics.

Opila, E. J.; Greenbauer-Seng, L. (Technical Monitor)

2000-01-01

427

Cavitating flow during water hammer using a generalized interface vaporous cavitation model  

NASA Astrophysics Data System (ADS)

In a transient flow simulation, column separation may occur when the calculated pressure head decreases to the saturated vapor pressure head in a computational grid. Abrupt valve closure or pump failure can result in a fast transient flow with column separation, potentially causing problems such as pipe failure, hydraulic equipment damage, cavitation or corrosion. This paper reports a numerical study of water hammer with column separation in a simple reservoir-pipeline-valve system and pumping station. The governing equations for two-phase transient flow in pipes are solved based on the method of characteristics (MOC) using a generalized interface vaporous cavitating model (GIVCM). The numerical results were compared with the experimental data for validation purposes, and the comparison indicated that the GIVCM describes the experimental results more accurately than the discrete vapor cavity model (DVCM). In particular, the GIVCM correlated better with the experimental data than the DVCM in terms of timing and pressure magnitude. The effects of geometric and hydraulic parameters on flow behavior in a pumping station with column separation were also investigated in this study.

Sadafi, Mohamadhosein; Riasi, Alireza; Nourbakhsh, Seyed Ahmad

2012-10-01

428

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

SciTech Connect

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

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

2004-10-20

429

cw operation of 1. 57-. mu. m Ga/sub x/In/sub 1-x/As/sub y/P/sub 1-y/InP distributed feedback lasers grown by low-pressure metalorganic chemical vapor deposition  

SciTech Connect

Continuous wave operation of 1.57-..mu..m distributed feedback lasers fabricated on material grown by two-step low-pressure metalorganic chemical vapor deposition growth process is reported for the first time. Room-temperature continuous wave threshold currents as low as 60 mA have been measured for devices with cavity length of 300 ..mu..m and stripe width of 5 ..mu..m. Single longitudinal mode operation at fixed mode was obtained under the continuous wave condition, in the temperature range 9--90 /sup 0/C, with the wavelength shift of 0.9 A//sup 0/C. A stop band of 25 A in which no resonance mode emission existed, was observed in the output spectrum of the distributed feedback laser.

Razeghi, M.; Blondeau, R.; Kazmierski, K.; Krakowski, M.; de Cremoux, B.; Duchemin, J.P.; Bouley, J.C.

1984-10-01

430

Tropospheric water vapor measurements over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX)  

NASA Astrophysics Data System (ADS)

Fast-response tunable diode laser measurements of water vapor were made over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) conducted in the fall of 1997. Resulting water vapor mixing ratios, in conjunction with air temperature and pressure measurements obtained by the DC-8's Data Acquisition and Distribution System (DADS), were used to calculate the prevalence of ice-saturated conditions (relative humidity with respect to ice >100% or frost saturation) in the upper troposphere over the SONEX sampling region. Additionally, Appleman theory was applied to the data to determine the subset of ice-saturated regions which would support formation of contrails. Results suggest that studies to determine the potential climate or radiative impact of contrails and aviation-induced cirrus clouds should not only consider the climatology of frost-saturated regions, but should also address whether ambient conditions can support contrail formation within these regions. A separate discussion within the paper describes an in-flight intercomparison between the SONEX diode laser hygrometer and the Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) cryogenic hygrometer and shows that the instruments perform to within their stated accuracies (˜10%) over a range of mixing ratios and altitudes.

Vay, S. A.; Anderson, B. E.; Jensen, E. J.; Sachse, G. W.; Ovarlez, J.; Gregory, G. L.; Nolf, S. R.; Podolske, J. R.; Slate, T. A.; Sorenson, C. E.

2000-02-01

431

Solar-powered alkali metal vapor lasers  

NASA Technical Reports Server (NTRS)

The emission spectrum of the A(1 Sigma u +) - X(1 Sigma g +) band of Na2 has been recorded following excitation by monochromatic radiation in the region of X-A and X-B absorption. The spectral profile has been investigated as a function of excitation wavelength, sodium vapor temperature and buffer gas pressure. Additionally, gain measurements were made for the satellite of the A-X band as a function of the sodium vapor temperature and buffer gas pressure.

Blount, Charles E.

1989-01-01

432

Recover heat by mechanical vapor recompression  

SciTech Connect

Several examples illustrating recompression of head vapors for heating the reboiler of a distillation tower are presented. The advantages of the mechanical vapor recompression system using a screw compressor are discussed in detail. The system is economically attractive with simple payback periods often less than two years. Numerous studies have identified a number of alternatives for lowering energy consumption in the distillation process through various heat recovery techniques. One such technique utilizes mechanical vapor recompression. By mechanically recompressing low-pressure vapors, a better match can be made between low-grade waste energy sources and process uses, thereby improving plant energy efficiency.

Becker, F.E.; Zakak, A.I.

1985-05-01

433

Phase relations in the system NaCl-KCl-H2O. III: Solubilities of halite in vapor-saturated liquids above 445??C and redetermination of phase equilibrium properties in the system NaCl-H2O to 1000??C and 1500 bars  

USGS Publications Warehouse

Halite solubilities along the three-phase curve in the binary system NaCl-H2O determined by DTA experiment can be represented by the equation Wt.% NaCl (??0.2) = 19.39 - 0.0364t + 3.553 ?? 10-4T2 - 2.298 ?? 10-7T3, where 447??? T ??? 800??C. Even though these halite solubilities are up to ~7 wt.% higher than those reported in literature, extrapolated values at temperatures below 447??C merge with the literature values. It is considered that the equation adequately describes halite solubilities between 382 and 800??C. The newly established solubility data are believed to be more reliable because they are compatible with data obtained by using synthetic fluid inclusions and with the observed DTA signals and also because they were measured in a relatively corrosion-free system. In an earlier publication (GUNTER et al., 1983), we were puzzled greatly by multiple and rather unreproducible DTA peaks appearing during isobaric cooling (heating experiments were nondefinitive) at pressures below about 500 bars. These DTA signals apparently suggested that the "halite liquidus" swung sharply upward in temperature as pressure decreased from about 500 bars to that of the halite-saturated boiling curve. Further analysis of the data and helpful discussions with several individuals have revealed that the behavior is a consequence of the initial (precooling) separation of the fluid into NaCl-poor gas and NaCl-rich liquid that failed to homogenize in the short time encompassed by the DTA experiments. The present analysis is based on extrapolations of the dP dT slopes from pressures above 500 bars. Through use of these new halite solubility data and the data from synthetic fluid inclusions [formed by healing fractures in inclusion-free Brazilian quartz in the presence of two coexisting, immiscible NaCl-H2O fluids at various temperatures and pressures (Bodnar et al., 1985)], phase equilibria in the system NaCl-H2O have been redetermined to 1000??C and 1500 bars. ?? 1987.

Chou, I. -M.

1987-01-01

434

Sand Castle Saturation  

NSDL National Science Digital Library

In this activity about saturation (page 1 of PDF), learners will build a series of sand castle towers using a 16 oz cup. Learners begin with completely dry sand and then add a ¼ cup of water to the sand for each successive tower, each time measuring the height and width of the resulting sand mound until they make a tower that maintains the shape of the cup. Relates to the linked video, DragonflyTV: Sand Dunes.

Twin Cities Public Television, Inc.

2005-01-01

435

Saturated Zone Colloid Transport  

Microsoft Academic Search

This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh,

H. S. Viswanathan

2004-01-01

436

Saturated Operational Amplifier  

NSDL National Science Digital Library

This animated gif illustrates the changing voltages when an operational amplifier (op-amp) becomes saturated. This animation would be useful for visually respresenting Finley's law. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

2009-11-27

437

Impact Vaporization of Planetesimal Cores  

NASA Astrophysics Data System (ADS)

The degree of mixing and chemical equilibration between the iron cores of planetesimals and the mantle of the growing Earth has important consequences for understanding the end stages of Earth's formation and planet formation in general. At the Sandia Z machine, we developed a new shock-and-release technique to determine the density on the liquid-vapor dome of iron, the entropy on the iron shock Hugoniot, and the criteria for shock-induced vaporization of iron. We find that the critical shock pressure to vaporize iron is 507(+65,-85) GPa and show that decompression from a 15 km/s impact will initiate vaporization of iron cores, which is a velocity that is readily achieved at the end stages of planet formation. Vaporization of the iron cores increases dispersal of planetesimal cores, enables more complete chemical equilibration of the planetesimal cores with Earth's mantle, and reduces the highly siderophile element abundance on the Moon relative to Earth due to the expanding iron vapor exceeding the Moon's escape velocity. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

Kraus, R. G.; Root, S.; Lemke, R. W.; Stewart, S. T.; Jacobsen, S. B.; Mattsson, T. R.

2013-12-01

438