Sample records for saturation vapor pressure

  1. Atmospheric sugar alcohols: evaporation rates and saturation vapor pressures

    NASA Astrophysics Data System (ADS)

    Bilde, M.; Zardini, A. A.; Hong, J.; Tschiskale, M.; Emanuelsson, E.

    2014-12-01

    The atmospheric partitioning between gas and condensed phase of organic molecules is poorly understood, and discrepancies exist between predicted and observed concentrations of secondary organic aerosols. A key problem is the lack of information about thermodynamic properties of semi- and low volatile organic molecules. Saturation vapor pressure and the associated temperature dependence (dH) are key parameters for improving predictive atmospheric models. In this work we combine experiments and thermodynamic modeling to investigate these parameters for a series of polyols, so-called sugar alcohols. These polyols are common in the water soluble fraction of atmospheric aerosols. In our experimental system sub-micron particles are generated by nebulization from aqueous solution, and a mono disperse fraction of the aerosol is selected using a differential mobility analyzer. The particles are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using thermodynamic modeling. Results are presented and discussed in context of atmospheric gas to particle partitioning.

  2. Saturated Vapor Pressure in a System Constituted by Anthranilic Acid and Hydrogen Fluoride

    Microsoft Academic Search

    A. P. Murlyshev; V. V. Lazarchuk; Yu. Ya. Tomash; A. G. Krupin; V. D. Filimonov; I. I. Zherin; V. V. Gordienko; S. N. Gerasimenko

    2003-01-01

    The saturated vapor pressure in a system constituted by anthranilic (o-aminobenzoic) acid and hydrogen fluoride was studied by the static method in the temperature range 0-90C. The isotherms of vapor pressure as a function of solution composition were approximated using the least-squares method.

  3. Low-Temperature Specific Heat of Liquid He3 near the Saturated Vapor Pressure and at Higher Pressures

    Microsoft Academic Search

    D. F. Brewer; J. G. Daunt; A. K. Sreedhar

    1959-01-01

    The specific heat of liquid He3 has been measured near the saturation vapor pressure in the range 0.085K to 0.75K, and at pressures up to the melting pressure between 0.12K and 0.6K. There is no evidence of a specific heat transition in the range of measurements. Near 0.1K the specific heat near the saturated vapor pressure appears to tend linearly

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

    PubMed

    Widegren, Jason A; Bruno, Thomas J

    2010-01-01

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

  5. LOW-TEMPERATURE SPECIFIC HEAT OF LIQUID He³ NEAR THE SATURATED VAPOR PRESSURE AND AT HIGHER PRESSURES

    Microsoft Academic Search

    D. F. Brewer; J. G. Daunt; A. K. Sreedhar

    1959-01-01

    The specific heat of liquid He³ was measured near the saturation ; vapor pressure in the range 0.085 to 0.75 deg K, and at pressures up to the ; melting pressure between 0.12 and 0.6 deg K. There is no evidence of a specific ; heat transition in the range of measurements. Near 0.1 deg K the specific heat ;

  6. Saturated Vapor Pressure over Molten Mixtures of GaCl 3 and Alkali Metal Chlorides

    Microsoft Academic Search

    A. B. Salyulev; V. V. Smolenskii; N. I. Moskalenko

    2004-01-01

    Fugacities of GaCl3 and alkali metal chlorides over molten dilute (up to 3 mol %) solutions of GaCl3 in LiCl, NaCl, KCl, RbCl, and CsCl were measured at 1100 K by dynamic and indirect static methods. The chemical composition of the saturated vapor over the mixed melts was determined. The partial pressures of the components were calculated. Their values substantially

  7. Study of temperature dependencies of saturated vapor pressure of ruthenium(III) beta-diketonate derivatives

    Microsoft Academic Search

    N. B. Morozova; K. V. Zherikova; P. P. Semyannikov; S. V. Trubin; I. K. Igumenov

    2009-01-01

    Complexes of ruthenium(III) with the following beta-diketones: 2,4-pentanedione (Ru(acac)3), 1,1,1-trifluoro-2,4-pentanedione (Ru(tfac)3), 2,2,6,6-tetramethyl-3,5-heptanedione (Ru(thd)3), 2,2,6,6tetramethyl-4-fluoro-3,5-heptanedione (Ru(tfhd)3) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (Ru(ptac)3) were synthesized and identified by means of mass spectrometry. By effusion Knudsen method with mass spectrometric registration\\u000a of gas phase composition the temperature dependencies of saturated vapor pressure were measured for ruthenium(III) compounds\\u000a and the thermodynamic characteristics of vaporization processes enthalpy ?H

  8. 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...

  9. Measurement of the vapor pressure of several low-volatility organochlorine chemicals at low temperatures with a gas saturation method

    SciTech Connect

    Wania, F.; Shiu, W.Y.; Mackay, D. (Univ. of Toronto, Ontario (Canada). Dept. of Chemical Engineering and Applied Chemistry)

    1994-07-01

    The vapor pressures of hexachlorobenzene, [gamma]-hexachlorocyclohexane, p,p[prime]-DDT, i.e., 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane, 4-monochlorobiphenyl, 4,4[prime]-dichlorobiphenyl, 2,3,4,5-tetrachlorobiphenyl, and 2,2[prime],4,4[prime],6,6[prime]-hexachlorobiphenyl were measured in the temperature range [minus]30 to +40 C with a gas saturation technique. Coefficients describing the temperature dependence of these vapor pressures are reported. Enthalpies of sublimation derived from these data show no significant temperature dependence in the temperature range investigated.

  10. Measurement of the vapor pressure of several low-volatility organochlorine chemicals at low temperatures with a gas saturation method

    Microsoft Academic Search

    Frank Wania; Wan-Ying Shiu; Donald Mackay

    1994-01-01

    The vapor pressures of hexachlorobenzene, [gamma]-hexachlorocyclohexane, p,p[prime]-DDT, i.e., 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane, 4-monochlorobiphenyl, 4,4[prime]-dichlorobiphenyl, 2,3,4,5-tetrachlorobiphenyl, and 2,2[prime],4,4[prime],6,6[prime]-hexachlorobiphenyl were measured in the temperature range [minus]30 to +40 C with a gas saturation technique. Coefficients describing the temperature dependence of these vapor pressures are reported. Enthalpies of sublimation derived from these data show no significant temperature dependence in the temperature range investigated.

  11. Electrical conductivity measurements of aqueous boric acid at 25--350°C at saturation vapor pressure. Final report

    Microsoft Academic Search

    P. C. Ho; D. A. Palmer

    1995-01-01

    Electrical conductance measurements of aqueous boric acid solutions (15-110 g\\/kg-HO 0.251--1.815 mol\\/kg-HO) 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-HO over

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

    Microsoft Academic Search

    Charles J. Weschler

    2003-01-01

    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 pressurethe 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.

  13. Infrared absorption bands of alkali saturated vapors

    Microsoft Academic Search

    A. Vasilakis

    1981-01-01

    A region of absorption was observed and measured in the near infrared region of the spectrum for saturated sodium vapor and for saturated rubidium vapor (absorption beyond 0.83 microns for saturated sodium vapor, and beyond 1.20 microns in rubidium saturated vapor). In addition, earlier data taken on near infrared absorption by cesium saturated vapor beyond 1.30 microns was reexamined in

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

    SciTech Connect

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

    1995-09-01

    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).

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

    SciTech Connect

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

    1999-03-01

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

  16. Vapor Pressure Data

    NSDL National Science Digital Library

    Ohe, Shuzo.

    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.

  17. Sedimentair equilibrium partitioning of semi-volatile hydrophobic organic compounds Part 2. Saturated vapor pressures, and the effects of sediment moisture content and temperature on the partitioning of polyaromatic hydrocarbons

    Microsoft Academic Search

    G de Seze; K. T Valsaraj; D. D Reible; L. J Thibodeaux

    2000-01-01

    A gas saturation methodology was used to determine the sediment\\/air partition coefficient (KSA) for phenanthrene and dibenzofuran on a local sediment from the Campus Lake, Baton Rouge. The effects of sediment moisture content, air relative humidity and temperature on KSA for phenanthrene were ascertained. The saturated vapor pressures of the compounds were also measured. The sediment moisture content had a

  18. Helium liquefier cycles with saturated vapor compression

    SciTech Connect

    Minta, M.; Smith, J.L. Jr.

    1982-01-01

    This paper is the design study of a saturated-vapor-compression helium liquefier operating at elevated pressure. The study was done to show the potential of the SVC cycle by direct comparison with a conventional cycle using the same precooling expanders and a supercritical wet expander instead of a J-T valve. A description of convential and SVC helium cycles is given with diagrams. Optimization of the SVC cycle is presented with a graph of the expander inlet temperatures. A discussion of the results includes conventional and SVC cycle dates for four states each. The SVC cycle has the potential for significant improvements of helium liquefiers producing atmospheric pressure liquid. This and other results encouraged the construction of apparatus to be used with a conventional helium liquefier to test a wet expander and a cold compressor and to demonstrate the potential of the SVC cycle.

  19. The vapor pressures of explosives

    SciTech Connect

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

    2013-01-05

    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.

  20. Experimental study of copper(I) chloride complexing in hydrothermal solutions at 40 to 300C and saturated water vapor pressure

    Microsoft Academic Search

    Zhifeng Xiao; C. H. Gammons; A. E. Williams-Jones

    1998-01-01

    The solubility of Cu phases was measured in vapor-saturated aqueous HCl\\/NaCl solutions at temperatures ranging from 40 to 300C, total chloride concentration from 0.01 to 1 m, and pH from 0 to 3.5. For temperatures up to and including 150C, CuCl(s) was used as the solid reactant. At higher temperatures, foils of metallic Cu and Ag were used. Silver was

  1. VAPORIZATION THERMODYNAMICS OF KCl. COMBINING VAPOR PRESSURE AND GRAVIMETRIC DATA

    E-print Network

    Rudnyi, Evgenii B.

    1 VAPORIZATION THERMODYNAMICS OF KCl. COMBINING VAPOR PRESSURE AND GRAVIMETRIC DATA Rudnyi E in the vapors above alkali halides at high temperature introduces special problems in the assessment of thermodynamic properties of the vapor and the vaporization process, coupling pressure measurements

  2. Vapor pressure of germanium precursors

    Microsoft Academic Search

    J. Pangrc; M. Fulem; E. Hulicius; K. Melichar; T. ime?ek; K. Ruzicka; P. Morvek; V. R?i?ka; S. A. Rushworth

    2008-01-01

    The vapor pressure of two germanium precursors tetrakis(methoxy)germanium (Ge(OCH3)4, CASRN 992-91-6) and tetrakis(ethoxy)germanium (Ge(OC2H5)4, CASRN 14165-55-0) was determined using a static method in the temperature range 259303K. The experimental vapor pressure data were fit with the Antoine equation. The mass spectra before and after degassing by vacuum distillation at low temperature are also reported and discussed.

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

    Microsoft Academic Search

    James Marti; Konrad Mauersberger

    1993-01-01

    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

  4. Vapor Pressure Measurements in a Closed System

    ERIC Educational Resources Information Center

    Iannone, Mark

    2006-01-01

    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

  5. Effects of Exposure to Vapors of Saturated Salt Aqueous Solutions

    Microsoft Academic Search

    RUDOLF SCHUBERT; HARLAND G. TOMPKINS

    1982-01-01

    Saturated salt aqueous solutions are used to produce controlled relative humidities in many laboratory tests. Components of the salt are shown to enter the gas phase and, in some instances, to alter surface film characteristics and chemisty. Coupons of Cu were exposed to the vapors of saturated salt aqueous solutions. NaNO3, (NH4)2SO4, and NaCI saturated solutions were kept at 85C

  6. Vapor pressure above ice at temperatures below 170 K

    Microsoft Academic Search

    Konrad Mauersberger; Dieter Krankowsky

    2003-01-01

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

  7. Volumetric properties of vapor-saturated aqueous NaCO solutions from 0°C to 100°C, vapor-saturated aqueous KCO solutions from 0°C to 100°C, vapor-saturated aqueous KHCO solutions from 0°C to 50°C, and vapor-saturated aqueous NaHCO solutions from 18°C to 60°C based on a regression of the available literature data

    Microsoft Academic Search

    D. L. Brown; R. W. II Potter

    1977-01-01

    Pressure-volume-temperature-composition (P-V-T-X) data for brines are required to establish optimum operating conditions for the production of geothermal brine fields. A compilation of density values is presented for vapor-saturated NaCO solutions of 0 to 14 weight percent concentrations from 0°C to 100°C, for vapor-saturated KCO solution of 0 to 50 weight percent concentrations from 0°C to 100°C, for vapor-saturated NaHCO solutions

  8. Helium liquefier cycles with saturated vapor compression

    Microsoft Academic Search

    M. Minta; J. L. Smith Jr.

    1982-01-01

    The three refrigeration stages of the conventional helium liquefaction cycle are related to liquid nitrogen precooling, the use of expansion engines, and a J-T expansion. For an operation of helium refrigerators at temperatures below 4.2 K reduced pressure levels are required. Such an operation makes it necessary to enhance the compressor size and the heat exchanger surface area. In the

  9. Volumetric properties of vapor saturated aqueous potassium hydroxide solutions from 0° to 400° and vapor saturated aqueous sodium hydroxide solutions from 0° to 350° based on a regression of the available literature data

    Microsoft Academic Search

    D. L. Brown; R. W. II Potter

    1977-01-01

    Pressure-volume-temperature-composition (P-V-T-X) data for brines are required to establish optimum operating conditions for the production of geothermal brine fields; to minimize scaling and corrosion; and to intelligently design turbines for production of electricity. An internally consistent set of density values is tabulated for vapor-saturated, aqueous potassium hydroxide solutions from 0°C to 400°C and for vapor-saturated, aqueous sodium hydroxide solutions from

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

    E-print Network

    Laverty, W. F.

    1964-01-01

    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 ...

  11. Experimentally Determined Vapor Pressures of Carbon Dioxide from 167 to 87 K

    Microsoft Academic Search

    R. N. Nelson; B. P. Michael; J. E. Allen Jr.

    1999-01-01

    Carbon dioxide (CO{_2}) is a major constituent in the Martian atmosphere and its abundance is controlled by surface condensation primarily at the poles. Because the sublimation temperature is determined by the vapor pressure curve, the saturation law is arguably the most important physical property of CO{_2} for Mars. A number of different representations have been used for the vapor pressure

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

    E-print Network

    Chickos, James S.

    The Vaporization Enthalpies and Vapor Pressures of Some Primary Amines of Pharmaceutical Importance Information ABSTRACT: Vapor pressures, vaporization, and sublimation enthalpies of several pharmaceuticals.5 2.1); p(cr)/Pa = 0.12 0.04]. Vapor pressure equations also derived from vapor pressureretention

  13. Vapor pressure and intramolecular hydrogen bonding in fluorotelomer alcohols.

    PubMed

    Krusic, Paul J; Marchione, Alexander A; Davidson, Fredric; Kaiser, Mary A; Kao, Chien-Ping C; Richardson, Raymond E; Botelho, Miguel; Waterland, Robert L; Buck, Robert C

    2005-07-21

    Vapor pressure and aqueous solubility are important parameters used to estimate the potential for transport of chemical substances in the atmosphere. For fluorotelomer alcohols (FTOHs), currently under scrutiny by environmental scientists as potential precursors of persistent perfluorocarboxylates (PFCAs), vapor pressure is the more significant property since these compounds are only very sparingly soluble in water. We have measured the vapor pressures of a homologous series of fluorotelomer alcohols, F(CF2CF2)nCH2CH2OH (n = 2-5), in the temperature range 21-250 degrees C by three independent methods: (a) a method suitable for very low vapor pressures at ambient temperatures (gas-saturation method), (b) an improved boiling point method at controlled pressures (Scott method), and (c) a novel method, requiring milligram quantities of substance, based on gas-phase NMR, a technique largely unfamiliar to chemists and holding promise for studies of relevance to environmental chemistry. The concordant values obtained indicate that recently published vapor pressure data overestimate the vapor pressure at ambient temperature, and therefore the volatility, of this series of fluorinated compounds. It was suggested that substantial intramolecular -O-H...F- hydrogen bonding between the hydroxylic proton and the two fluorines next to the ethanol moiety was responsible for their putative high volatility. Therefore, we have used gas-phase NMR, gas-phase FTIR, 2D NMR heteronuclear Overhauser effect measurements, and high-level ab initio computations to investigate the intramolecular hydrogen bonding in fluorotelomer alcohols. Our studies unequivocally show that hydrogen bonding of this type is not significant and cannot contribute to and cause unusual volatility. The substantially lower vapor pressure at ambient temperatures than previously reported resulting from our work is important in developing a valid understanding of the environmental transport behavior of this class of compounds. PMID:16833963

  14. Multicomponent fuel vaporization at high pressures.

    SciTech Connect

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

    2002-01-01

    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.

  15. Solubilities and vapour pressures of saturated aqueous solutions of sodium peroxydisulfate and potassium peroxydisulfate

    Microsoft Academic Search

    Emanuel Manzurola

    2001-01-01

    Solubilities of sodium peroxydisulfate and potassium peroxydisulfate in water and vapour pressures of saturated solutions were determined as a function of temperature. The vapour pressures served to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. The molar enthalpy of solution of sodium peroxydisulfate was determined calorimetrically.

  16. Vapor Pressure of Cesium Between 270 and 370 K Via Laser Absorption

    Microsoft Academic Search

    Robert J. Rafac; Carol E. Tanner

    1998-01-01

    For more than sixty years, experimenters have relied on the vapor pressure equations from Taylor and Langmuir's positive ion measurementsfootnote J. B. Taylor and I. Langmuir. Phys. Rev., 51:753 (1937). to calibrate the densities of saturated atomic cesium vapor for numerous spectroscopic applications. We update these results with additional data obtained via measurement of the direct absorption of narrow-band laser

  17. High temperature vapor pressure of pure plutonium

    Microsoft Academic Search

    M. H. Bradbury; R. W. Ohse

    1979-01-01

    High temperature vapor pressure measurements have been made on pure plutonium metal by the Knudsen effusion technique. The reported experimental results extend into the transition region between molecular and viscous or hydrodynamic flow. Under the conditions used, linearity was observed up to temperatures in excess of 2200 K where pressures approaching 100 Pa were measured. The results over the temperature

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

    E-print Network

    Chickos, James S.

    Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures The vaporization enthalpies and vapor pressures of the liqiud phase from T ) 298.15 K to T ) 500 K of a series. The vaporization enthalpies at T ) 298.15 K measured in kilojoules per mole include: tri-n-butylamine (62.7 ( 1

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

    E-print Network

    Chickos, James S.

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

  20. Vapor pressures of the aqueous desiccants

    SciTech Connect

    Chung, T.W.; Luo, C.M. [Chung Yuan Christian Univ., Chungli (Taiwan, Province of China). Chemical Engineering Dept.] [Chung Yuan Christian Univ., Chungli (Taiwan, Province of China). Chemical Engineering Dept.

    1999-09-01

    The vapor pressures of the aqueous desiccants lithium chloride, lithium bromide, calcium chloride, ethylene glycol, propylene glycol, and their mixtures were measured at their typical operating concentrations and at temperatures from 298 K to 313 K. The experimental data were fitted to an Antoine type of equation, ln[P(kPa)] = A {minus} B/[T(K) + C], where A, B, and C are constants and are concentration dependent. Vapor pressure data were further used to predict the effectiveness of dehumidification in liquid desiccant dehumidifiers.

  1. The Vapor Pressure of Plutonium Halides

    Microsoft Academic Search

    T. E. Phipps; G. W. Sears; R. L. Seifert; O. C. Simpson

    1950-01-01

    Vapor pressure measurements have been made with three halides of plutonium by a modification of the Knudsen effusion method. Measurements with solid plutonium trifluoride from 1200K to 1440K give the vapor pressure-temperature relation log10pmm=12.46821,120\\/T. Measurements with liquid plutonium trifluoride from 1440K to 1770K give log10pmm=11.27319,400\\/T. Measurements with solid plutonium trichloride from 850K to 1007K give log10pmm=12.72615,910\\/T; with liquid trichloride from

  2. Pressurized vapor driven rotary engine

    Microsoft Academic Search

    Schadeck

    1992-01-01

    This patent describes a pressurized fluid rotary engine. It comprises a piston housing; first and second hubs, each hub being rotatably supported in the piston housing about a common axis; piston heads extending radially outwardly from the hubs for travel in a circular path about the axis, each piston head having a pair of working surfaces, each working surface facing

  3. 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...

  4. 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

    Oak Ridge National Laboratory

    DIAGRAM OF A MIXTURE A convenient tool to assist in cycle calculations of refrigerating systems is a pressure- enthalpy diagram displaying the saturated-liquid and saturated-vapor lines, as well-114. The first noticeable difference between Figure 3 and a p-h diagram for a single refrigerant

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

    E-print Network

    Chickos, James S.

    Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures and Biochemistry, University of MissourisSt. Louis, St. Louis, Missouri 63121 The vaporization enthalpies and liquid vapor pressures from T ) 298.15 K to T ) 510 K of a series of polyaromatic hydrocarbons have been

  6. The vapour pressures over saturated aqueous solutions of cadmium chloride, cadmium bromide, cadmium iodide, cadmium nitrate, and cadmium sulphate

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    2007-01-01

    Vapour pressures of water over saturated solutions of cadmium salts (chloride, bromide, iodide, nitrate, and sulphate) were determined over the temperature range 280K to 322K and compared with the literature data. The vapour pressures determined were used to obtain the water activities, osmotic coefficients and the molar enthalpies of vaporization in the (cadmium salt+water) systems.

  7. Volumetric properties of vapor saturated aqueous HCl solutions from 0° to 100°C, vapor saturated aqueous FeCl solutions at 15° and 18°C, and vapor saturated aqueous FeCl from 0° to 35°C based on a regression of the available literature data

    Microsoft Academic Search

    D. L. Brown; R. W. II Potter

    1977-01-01

    Pressure-volume-temperature-composition (P-V-T-X) data for brines are required to establish optimum operating conditions for the production of geothermal brine fields. Precise thermodynamic data derived from the volumetric properties of the brines are prerequisite for chemical and reservoir modeling of geothermal brine systems. A compilation of density values is presented therein for vapor-saturated hydrochloric acid of 0 to 40 weight percent concentrations

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. Transpiration method: Vapor pressures and enthalpies of vaporization of some low-boiling esters

    Microsoft Academic Search

    Sergey P. Verevkin; Vladimir N. Emelyanenko

    2008-01-01

    This investigation was undertaken to reveal the upper limit of vapor pressures which could be measured by using the transpiration method accurately. Molar enthalpies of vaporization of 10 esters of monocarboxylic acids were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The measured data sets were successfully checked for internal consistency. A large number

  10. The vapour pressure of water over saturated aqueous solutions of malic, tartaric, and citric acids, at temperatures from 288 K to 323 K

    Microsoft Academic Search

    Alexander Apelblat; Mariana Dov; Jaime Wisniak; Jacob Zabicky

    1995-01-01

    Vapour pressures of saturated aqueous solutions ofDL-malic acid,L(+)-tartaric acid, and citric acid were measured in the temperature range 288 K to 323 K, applying the isoteniscope technique. The water activities, osmotic coefficients, and molar enthalpies of vaporization and of solution at saturation were evaluated from the measured vapour pressures.

  11. On the propagation of a coupled saturation and pressure front

    SciTech Connect

    Vasco, D. W.

    2010-12-01

    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.

  12. Hyperfine Studies of Lithium Vapor using Saturated Absorption Spectroscopy

    E-print Network

    Cronin, Alex D.

    Circuit . . . . . . . . . . . . . . 30 3 #12;Chapter 1 Introduction Diode lasers have numerous [4]. With slight modifications, these diodes provide narrow bandwidth light that can be tuned an extended cavity diode laser (ECDL) along with a saturated absorption spectroscopy system to study

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

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

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    2003-01-01

    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=0.1030molkg?1)=(17.40.5)kJmol?1; ammonium hydrogen

  15. Thermogravimetric study of vapor pressure of TATP synthesized without recrystallization.

    PubMed

    Mbah, Jonathan; Knott, Debra; Steward, Scott

    2014-11-01

    This study aims at characterizing the vapor pressure signatures generated by triacetone triperoxide (TATP) that was synthesized without recrystallization by thermogravimmetric analysis (TGA) for exploitation by standoff detection technologies of explosive devices. The thermal behavior of the nonrecrystallized sample was compared with reported values. Any phase change, melting point and decomposition identification were studied by differential scanning calorimeter. Vapor pressures were estimated by the Langmuir method of evaporation from an open surface in a vacuum. Vapor pressures of TATP at different temperatures were calculated using the linear logarithmic relationship obtained from benzoic acid reference standard. Sublimation of TATP was found to follow apparent zero-order kinetics and sublimes at steady rates at 298 K and above. While the enthalpy of sublimation found, 71.7 kJ mol(-1), is in agreement with reported values the vapor pressures deviated significantly. The differences in the vapor pressures behavior are attributable to the synthesis pathway chosen in this study. PMID:25127637

  16. Thermodynamic properties of saturated methane

    E-print Network

    Holt, James Louis

    1972-01-01

    , Derivative of Pressure With Respect to Temperature. . . . . . . . . . . 73 III. Saturated Liquid Der sity. . . . . . . . . . . . . IV. Heat of Vaporization V. Saturated Liquid Heat Capacity. . VI. Saturated Vapor Density. . VII. Enthalpy. VIII. Entropy... of Vaporization vs. Temperature (1) . . . 53 18. Heat of Vaporization vs. Temperature (2) . . . 55 19. Heat Capacity Residual vs. Temperature (1) 58 Figure Page 20 ~ Heat Capacity Residual vs. Temperature ( 2) . . . 60 21. Heat Capacity vs. Temperature (1...

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

    SciTech Connect

    Suuberg, E.M.

    1995-04-01

    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.

  18. LOX vaporization in high-pressure, hydrogen-rich gas

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Jeng, San-Mou

    1990-01-01

    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.

  19. LOX vaporization in high-pressure, hydrogen-rich gas

    Microsoft Academic Search

    Ron J. Litchford; San-Mou Jeng

    1990-01-01

    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

  20. Vapor pressures and vapor compositions in equilibrium with hypostoichiometric plutonium dioxide at high temperatures

    Microsoft Academic Search

    D. W. Green; J. K. Fink; L. Leibowitz

    1983-01-01

    Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric plutonium dioxide condensed phase have been calculated for the temperature range 1500 less than or equal to T less than or equal to 4000 K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model, which has been extended from the

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

    ERIC Educational Resources Information Center

    Levinson, Gerald S.

    1982-01-01

    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)

  2. Vapor pressures of a homologous series of polyethylene glycols as a reference data set for validating vapor pressure measurement techniques.

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Marcolli, Claudia; Siegrist, Franziska

    2015-04-01

    The production of secondary organic aerosol (SOA) by gas-to-particle partitioning is generally represented by an equilibrium partitioning model. A key physical parameter which governs gas-particle partitioning is the pure component vapor pressure, which is difficult to measure for low- and semivolatile compounds. For typical atmospheric compounds like e.g. citric acid or tartaric acid, vapor pressures have been reported in the literature which differ by up to six orders of magnitude [Huisman et al., 2013]. Here, we report vapor pressures of a homologous series of polyethylene glycols (triethylene glycol to octaethylene glycol) determined by measuring the evaporation rate of single, levitated aerosol particles in an electrodynamic balance. We propose to use those as a reference data set for validating different vapor pressure measurement techniques. With each addition of a (O-CH2-CH2)-group the vapor pressure is lowered by about one order of magnitude which makes it easy to detect the lower limit of vapor pressures accessible with a particular technique down to a pressure of 10-8 Pa at room temperature. Reference: Huisman, A. J., Krieger, U. K., Zuend, A., Marcolli, C., and Peter, T., Atmos. Chem. Phys., 13, 6647-6662, 2013.

  3. 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

    Alexander Apelblat; Eli Korin

    2008-01-01

    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.

  4. Measurement of the Molecular Weights of Vapors at High Temperature. II. The Vapor Pressure of Germanium and the Molecular Weight of Germanium Vapor

    Microsoft Academic Search

    Alan W. Searcy; Robert D. Freeman

    1955-01-01

    The vapor pressure of germanium and the molecular weight of germanium vapor have been determined by use of an apparatus for the simultaneous measurement of the weight of vapor effusing through two small orifices and of the force exerted by the effusing vapor. The molecular weight of germanium vapor at 1750K was found to be 5816 compared to the atomic

  5. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 January 1993--31 March 1993

    SciTech Connect

    Suuberg, E.M.

    1993-07-01

    The vapor pressure correlations that exist at present for high molecular weight organics 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. It has been concluded that the saturation method holds significant promise as technique for measuring vapor pressures of pure components in the correct molecular weight regime. There are several aspects of experimental design that need further work in to improve performance. Most critical is the saturator device.

  6. Deposition and electrical properties of insitu phosphorus-doped silicon films formed by low-pressure chemical vapor deposition

    Microsoft Academic Search

    Arthur J. Learn; Derrick W. Foster

    1987-01-01

    The low-pressure chemical vapor deposition of phosphorus-doped silicon films on oxidized silicon wafers was investigated as a function of phosphine\\/silane mole ratio, silane partial pressure, temperature, and wafer spacing. The deposition rate decreases, concomitant with increased phosphorus incorporation, as the mole ratio increases. The deposition rate tends to saturate or vary linearly with silane partial pressure for undoped and heavily

  7. Subatmospheric vapor pressures evaluated from internal-energy measurements

    NASA Astrophysics Data System (ADS)

    Duarte-Garza, H. A.; Magee, J. W.

    1997-01-01

    Vapor pressures were evaluated from measured internal-energy changes in the vapor+liquid two-phase region, ? U (2). The method employed a thermodynamic relationship between the derivative quantity (? U (2)/? V) T and the vapor pressure ( p ?) and its temperature derivative (? p/? T)?. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), and difluoromethane (R32). Agreement with experimentally measured vapor pressures near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately 0.04 kPa (0.04%). The method was applied to R134a to test the thermodynamic consistency of a published p-p-T equation of state with an equation for p ? for this substance. It was also applied to evaluate published p ? data which are in disagreement by more than their claimed uncertainty.

  8. Vapour pressures of H 2 16O and H 2 18O, and saturated aqueous solutions of KCl from T=298 K to T=318 K by the isoteniscopic method

    Microsoft Academic Search

    Alexander Apelblat

    1998-01-01

    Vapour pressures of normal water, water enriched by the heavy isotope of oxygen H218O, and saturated aqueous solutions of KCl were determined in the temperature range (298 to 318)K by the isoteniscopic method and compared with the literature data. Water activities, osmotic coefficients, vapour pressure lowerings, boiling point elevations, and molar enthalpies of vaporization at the saturation point of potassium

  9. Water-vapor pressure control in a volume

    NASA Technical Reports Server (NTRS)

    Scialdone, J. J.

    1978-01-01

    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.

  10. Global atmospheric mass, surface pressure, and water vapor variations

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Christy, John R.; Olson, Jerry G.

    1988-01-01

    Variations in the hydrological cycle and the water vapor content of the atmosphere form a vital part of the "greenhouse" feedback mechanism that can substantially enhance perturbations in the atmosphere arising from changes in forcing, such as those associated with increases in the carbon dioxide content of the atmosphere. An analysis is therefore made of the mean annual cycle interannual variability and trends in global-scale water vapor content of the atmosphere for December 1978 through December 1985, using global analyses from the European Centre for Medium Range Weather Forecasts. Since the variations in total atmospheric mass are almost entirely due to water vapor, two entirely independent global measures of the water vapor content can be compared. These are the total surface pressure due to water vapor from humidity analyses and the total surface pressure itself. For the mean annual cycle these show excellent agreement, and the analyses are therefore compatible with the constraint that the total mass of dry air is conserved. However, it appears that both the interannual variability and trends in water vapor are sufficiently small that they are lost in the noise level of the data, A new estimate of the total mass of the atmosphere is 5.13611018 kg for the annual mean, corresponding to a mean surface pressure of 984.43 mbar. It ranges from 5.13521018 kg in January to 5.13711018 kg in July, owing to the annual cycle in global water vapor which has an amplitude of 1.01015 kg (0.2 mbar). The total mass of dry air is estimated to be 5.1231018 kg (or 981.9 mbar). Also presented is the partitioning of the mass for both the total and the water vapor into the contributions from each hemisphere and as a function of latitude. Mean annual surface pressures in the northern and southern hemispheres are found to be 981.92 and 986.93 mbar, respectively. Monthly mean hemispheric fluctuations in surface pressures of 1 mbar are not uncommon and tend to be reflected by opposite anomalies in the other hemisphere (consistent with conservation of mass), but the residual in the global monthly mean is of the order of 0.1 mbar. Since this is greater than the magnitude of the possible signal in water vapor surface pressure, the available evidence indicates that the analyzed global monthly anomalies are mostly noise.

  11. Global atmospheric mass, surface pressure, and water vapor variations

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Christy, Johan R.; Olson, Jerry G.

    1987-12-01

    Variations in the hydrological cycle and the water vapor content of the atmosphere form a vital part of the "greenhouse" feedback mechanism that can substantially enhance perturbations in the atmosphere arising from changes in forcing, such as those associated with increases in the carbon dioxide content of the atmosphere. An analysis is therefore made of the mean annual cycle, interannual variability and trends in global-scale water vapor content of the atmosphere for December 1978 through December 1985, using global analyses from the European Centre for Medium Range Weather Forecasts. Since the variations in total atmospheric mass are almost entirely due to water vapor, two entirely independent global measures of the water vapor content can be compared. These are the total surface pressure due to water vapor from humidity analyses and the total surface pressure itself. For the mean annual cycle these show excellent agreement, and the analyses are therefore compatible with the constraint that the total mass of dry air is conserved. However, it appears that both the interannual variability and trends in water vapor are sufficiently small that they are lost in the noise level of the data. A new estimate of the total mass of the atmosphere is 5.13611018 kg for the annual mean, corresponding to a mean surface pressure of 984.43 mbar. It ranges from 5.13521018 kg in January to 5.13711018 kg in July, owing to the annual cycle in global water vapor which has an amplitude of 1.01015 kg (0.2 mbar). The total mass of dry air is estimated to be 5.1231018 kg (or 981.9 mbar). Also presented is the partitioning of the mass for both the total and the water vapor into the contributions from each hemisphere and as a function of latitude. Mean annual surface pressures in the northern and southern hemispheres are found to be 981.92 and 986.93 mbar, respectively. Monthly mean hemispheric fluctuations in surface pressures of 1 mbar are not uncommon and tend to be reflected by opposite anomalies in the other hemisphere (consistent with conservation of mass), but the residual in the global monthly mean is of the order of 0.1 mbar. Since this is greater than the magnitude of the possible signal in water vapor surface pressure, the available evidence indicates that the analyzed global monthly anomalies are mostly noise.

  12. Evidence of water vapor in excess of saturation in the atmosphere of Mars.

    PubMed

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

    2011-09-30

    The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale. PMID:21960630

  13. Laminar forced convection condensation of saturated vapors in the near-critical region

    SciTech Connect

    Fujii, Tetsu [Univ. of East Asia, Shimonoseki (Japan); Lee, J.B. [Kyungnam Univ., Masan (Korea, Republic of). Dept. of Mechanical Engineering; Shinzato, Kan`ei [Kyoto Electronics Manufacturing Co. Ltd., Kitakyushu (Japan). Kyushu Lab.

    1996-12-01

    A numerical analysis is presented for laminar forced convection condensation of saturated vapors of water and carbon dioxide on a flat surface in the reduced temperature range T{sub s}/T{sub c} = 0.990--0.999. The heat transfer coefficient in the region T{sub s}/T{sub c} < 0.998 can be correlated by using Fujii and Uehara`s equation when the representative physical properties are evaluated at the film temperature. The reduction of the condensation mass flux or the heat flux at the vapor-liquid interface due to the convection term in the condensate film is expressed as a function of the phase change number with the average isobaric specific heat.

  14. Fixed volume versus fixed pressure liquid-vapor transition

    NASA Astrophysics Data System (ADS)

    Calecki, D.; Lederer, D.; Roulet, B.; Diu, B.; Guthmann, C.

    2010-12-01

    We consider the equilibrium conditions for nucleation at the liquid-vapor transition at fixed volume in contrast to the traditional fixed pressure treatment. Significant differences appear, particularly for the stability of the diphasic states, which strongly depends on the external conditions.

  15. Vapor pressures and gas-film coefficients for ketones

    USGS Publications Warehouse

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

    1987-01-01

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

  16. Solubilities and vapour pressures of saturated aqueous solutions of sodium tetraborate, sodium carbonate, and magnesium sulfate and freezing-temperature lowerings of sodium tetraborate and sodium carbonate solutions

    Microsoft Academic Search

    Alexander Apelblat; Emanuel Manzurola

    2003-01-01

    Solubilities and vapour pressures of water over saturated solutions of sodium tetraborate, sodium carbonate, and magnesium sulfate and freezing-temperature lowerings of sodium tetraborate and sodium carbonate solutions were determined and compared with the literature data. These results permitted the evaluation of osmotic and activity coefficients and molar enthalpies of vaporization.

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

    SciTech Connect

    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

    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.

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

    SciTech Connect

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

    2008-05-15

    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)

  19. Water vapor pressure versus environmental lapse rate near the tropopause

    NASA Astrophysics Data System (ADS)

    Ferreira, Antonio; Castanheira, Jose; Gimeno, Luis

    2010-05-01

    The relationship between water vapor pressure and temperature lapse rate in the vicinity of the tropopause was investigated using in situ observations. The water vapor partial pressures and the lapse rates within a vertical distance of 1.5 km around the first thermal tropopause were calculated from the vertical soundings conducted by the NOAA/CMDL at several locations in the last few decades (GMD Data Archive). A positive non-linear relationship between the two quantities was found to hold across the studied tropopause region at mid-latitudes and polar latitudes. A similar analysis was performed on the 300 and 250 hPa pressure levels (which often intercept the tropopause region), by collecting temperature and humidity observations within 1979-2008 from the Integrated Global Radiosonde Archive (IGRA). A relationship having almost the same shape was detected for statically stable lapse rates at all latitude zones. Given the relevance of water vapor in the radiative transfer in the upper troposphere, the results are an indication of a local influence of water vapor on the thermal structure of the transition layer between the troposphere and stratosphere

  20. Pump for Saturated Liquids

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.

    1986-01-01

    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

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

    SciTech Connect

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

    1998-03-01

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

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

    Microsoft Academic Search

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

    2010-01-01

    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

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

    E-print Network

    Magee, Joseph W.

    Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point Allan the vapor pressure of heavy water (D2O) from its triple point to its critical point. This work takes and ordinary water,24 a determination of the vapor pressure of D2O at its triple point,5 and the adoption

  4. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Standards: Pressure relief devices in gas/vapor service. 264.1054...Emission Standards for Equipment Leaks 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except...each pressure relief device in gas/vapor service shall be...

  5. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Standards: Pressure relief devices in gas/vapor service. 265.1054...Emission Standards for Equipment Leaks 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except...each pressure relief device in gas/vapor service shall be...

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

    E-print Network

    Goddard III, William A.

    Prediction of Vapor Pressures and Enthalpies of Vaporization Using a COSMO Solvation Model Shiang a general predictive method for vapor pressures and enthalpies of vaporization based on the calculation of varying molecular structure, functionality, and size. The average accuracy of the model for vapor

  7. Pressure sensitivity of the vapor-cell atomic clock.

    PubMed

    Iyanu, Gebriel; Wang, He; Camparo, James

    2009-06-01

    Although atomic clocks have very low levels of frequency instability, they are nonetheless sensitive (albeit slightly) to various environmental parameters, including temperature, power supply voltage, and dc magnetic fields. In the terrestrial environment, however, atmospheric pressure (i.e., the air's molecular density) is not generally included in this list, because the air's density variations near the surface of the earth will typically have a negligible effect on the clock's performance. The situation is different, however, for clocks onboard satellites like Galileo, where manufacturing and testing are done at atmospheric pressure, while operation is in vacuum. The pressure sensitivity of atomic clocks, in particular vapor-cell atomic clocks, can therefore be of significance. Here, we discuss some of the ways in which changes in atmospheric pressure affect vapor-cell atomic clocks, and we demonstrate that, for one device, the pressure-sensitivity traces back to a pressure-induced change in the temperature of the clock's filter and resonance cells. PMID:19574121

  8. The vapour pressures of saturated aqueous solutions of magnesium, calcium, nickel and zinc acetates and molar enthalpies of solution of magnesium, calcium, zinc and lead acetates

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    2001-01-01

    Vapour pressures of water over saturated solutions of magnesium, calcium, nickel and zinc acetates were determined as a function of temperature. The vapour pressures served to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. Molar enthalpies of solution of magnesium acetate tetrahydrate,?solHm (T= 294.71K ;m= 0.01 mol kg?1) =?(15.65 0.97)kJ mol?1; calcium acetate,?solHm (T=

  9. Low vapor pressure braze alloys for thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1976-01-01

    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.

  10. Low vapor pressure braze alloys for thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1976-01-01

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

  11. 250W diode laser for low pressure Rb vapor pumping

    Microsoft Academic Search

    A. Podvyaznyy; G. Venus; V. Smirnov; O. Mokhun; V. Koulechov; D. Hostutler; L. Glebov

    2010-01-01

    The diode pumped alkali vapor lasers operating at subatmospheric pressure require developing of a new generation of high-power laser diode sources with about 10 GHz wide emission spectrum. The latest achievements in the technology of volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass opened new opportunities for the design and fabrication of compact external cavity laser diodes, diode bars and

  12. Diode laser study of high-pressure water vapor spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagali, Venu

    1999-10-01

    Measurements of water vapor are relevant to combustion, since water vapor concentration can be related to performance parameters such as combustion and propulsion efficiencies, and heat release. The development of a diode-laser based diagnostic to monitor water vapor and temperature in high-pressure and -temperature environments relevant to combustion by probing near-IR H 2O absorption features near 7117 and 7185 cm-1 is described. A comprehensive review of line-shape modeling that highlights spectroscopic phenomena that become important at high pressures, such as the breakdown of the impact approximation in the wings and line mixing due to inelastic collisions, is presented. A decision tree and a road map to choose an appropriate line-shape model are introduced. Spectrally resolved measurements of H2O transitions near 7117 and 7185 cm-1 were performed at sub- atmospheric pressures and over a temperature range of 296-1000 K. Line-shape analyses of the recorded spectra yielded the temperature-dependent self-, N2-, CO2- and Ar broadened half- widths. The room-temperature (296K) half-widths and temperature exponents were determined to an average uncertainty of +/-7% and +/-9%, respectively. Good agreement was obtained between static-cell data recorded near 7117 cm-1 and simulations, based on measured line parameters and simple addition of Voigt line shapes, leading to the conclusions that: (1)effects due to line mixing are negligible for number densities up to at least 18 amagat, and (2)line shapes based on the impact and the additive approximations can be used in the development of spectroscopic diagnostics to monitor H2O in high-pressure combustion gases. Super-Lorentzian behavior was observed near 7185 cm-1 and is attributed to finite duration of collision effects neglected by impact line shapes. Water-vapor absorption features near 7117, 7185 and 7462 cm-1 were probed at pressures and temperatures to 65 atm. and 1800 K, in shock-heated mixtures of H2O in N2 and Ar. Temperature-dependent N2- and Ar-shift parameters for H2O absorption features were obtained by shifting the calculated spectra to match the recorded absorption data. The measured absorbance at the probed wavelengths was used to ascertain the accuracy of simulations based on current spectroscopic databases. The design of a sensor using diode lasers fixed at 7185.4 and 7117.4 cm -1 to monitor water vapor and temperature in high-pressure combustion gases is discussed.

  13. Pore-scale modeling of transient and steady-state vapor diffusion in partially-saturated porous media

    SciTech Connect

    Webb, S.W.

    1998-05-01

    Vapor diffusion in porous media in the presence of its own liquid may be enhanced due to pore-scale processes, such as condensation and evaporation across isolated liquid islands. Webb and Ho (1997) developed a mechanistic pore-scale model of these processes under steady-state conditions in which condensation and evaporation on the liquid island were equal. The vapor diffusion rate was significantly enhanced by these liquid island processes by up to an order of magnitude compared to a dry porous media. However, vapor transport by diffusion is often complicated by transient effects, such as in drying applications, in which net evaporation of liquid may further augment the vapor flux from diffusion. The influence of transient effects on the enhancement factors for vapor diffusion is evaluated in this paper. In addition, the effect of vapor pressure lowering on the enhancement factor and on porescale vapor fluxes is shown.

  14. Vapor-Phase Thermal Conductivity, Vapor Pressure, and Liquid Density of R365mfc

    Microsoft Academic Search

    Isabel M. Marrucho; Nelson S. Oliveira; Ralf Dohrn

    2002-01-01

    The thermal conductivity of a new fluoroalkane, R365mfc (1,1,1,3,3-pentafluorobutane), important for the production of polyurethane rigid foams, was measured using a transient hot wire method, at temp- eratures between 336.85 K and 377.4 K. The extended corresponding states theory was used successfully to predict the results, with an average absolute deviation of 0.5%. The vapor pressure (302.90 K to 358.15

  15. Comparison of pressure-saturation characteristics derived from computed tomography and lattice Boltzmann simulations

    E-print Network

    Wildenschild, Dorthe

    Comparison of pressure-saturation characteristics derived from computed tomography and lattice. Analysis of the Bond, Reynolds, and Capillary numbers for these systems showed that capillary forces were pressure-saturation data for the water-air system, but that there were large differences between

  16. The vapour pressures over saturated aqueous solutions of sodium and potassium acetates, chlorates, and perchlorates

    Microsoft Academic Search

    Alexander Apelblat; Emanuel Manzurola

    2007-01-01

    Vapour pressures of water over saturated solutions of sodium acetate, potassium acetate, sodium perchlorate, and potassium perchlorate were determined over the (278 to 318)K temperature range and compared with available in the literature data. The cases of saturated solutions of sodium chlorate and potassium chlorate are also considered. The determined vapour pressures were used to obtain the water activities, the

  17. Vapor Pressure of Water at Its Triple Point: Highly Accurate Value

    Microsoft Academic Search

    L. A. Guildner; D. P. Johnson; F. E. Jones

    1976-01-01

    The vapor pressure of water at its triple point was measured with greatly increased accuracy. The triple point was realized with newly designed equipment that enhanced the stability of the pressure and permitted any air released from solution to be removed by pumping. A diaphragm pressure transducer separated the water vapor from the helium used to transmit the pressure to

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

    E-print Network

    Markowich, Peter A.

    A HOMOGENIZATION TECHNIQUE FOR THE BOLTZMANN EQUATION FOR LOW PRESSURE CHEMICAL VAPOR DEPOSITION 1 the approach. The setup models low pressure chemical vapor deposition processes in the manufacturing, microstructured surface, chemical vapor deposition. AMS subject classi#12;cations (2000). 65M06, 76P05, 35B27, 76M

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

    E-print Network

    Hasegawa, Shuji

    Selective Growth of Straight Carbon Nanotubes by Low-Pressure Thermal Chemical Vapor Deposition) were grown by low-pressure thermal chemical vapor deposition using pure ethylene. It was found chemical vapor deposition, ethylene, catalyst nano- particles 1. Introduction Recently, surface

  20. Generation of high concentration aerosols from low vapor pressure compounds

    SciTech Connect

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

    1987-10-01

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

  1. 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

    Chickos, James S.

    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 esters by correlation gas8 Thermochimica Acta xxx (2007) xxxxxx The vaporization enthalpies and vapor pressures of a series of unsaturated

  2. Ice nucleation of Snomax particles below water vapor saturation: immersion freezing in concentrated solution droplets

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Kanji, Zamin A.; Boose, Yvonne; Beyer, Alexander; Henning, Silvia; Augustin-Bauditz, Stefanie

    2015-04-01

    Heterogeneous ice nucleation has received an increasing amount of interest in the past years, as it initiates the ice phase in mixed phase clouds (MPCs) and, to some extent, also in cirrus clouds. The presence of ice influences cloud radiative properties and, for mixed phase clouds, also the formation of precipitation. Immersion freezing is thought to be the most important mechanism through which ice formation could take place in MPCs. Here, we examine the ice nucleation activity of biological ice nucleating particles (INP) derived from bacteria, namely, particles generated from Snomax suspensions, both above and below water vapor saturation. During a measurement campaign in Leipzig, ice nucleation measurements were conducted with PINC (Portable Ice Nucleus Counter, Chou et al., 2011) and LACIS (Leipzig Aerosol Cloud Interaction Simulator, see e.g. Wex et al., 2014a). Immersion freezing measurements from PINC and LACIS were in agreement in the temperature regime for which both instruments operate reliably. Here, we will show that measurements done below water vapour saturation and above the deliquescence relative humidity of the Snomax particles follow what would be expected for immersion freezing in concentrated solutions, similar to what was suggested for coated kaolinite particles in Wex et al. (2014b). Additionally, some measurements reported in the literature that were done in the water vapour sub-saturated regime will be evaluated based on the assumption made above, showing that at least some of the ice nucleation which previously was ascribed to deposition ice nucleation rather follows the behavior of immersion freezing in concentrated solutions. Literature: Chou, C., O. Stetzer, E. Weingartner, Z. Juranyi, Z. A. Kanji, and U. Lohmann (2011), Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps, Atmos. Chem. Phys., 11(10), 4725-4738, doi:10.5194/acp-11-4725-2011. Wex, H. et al. (2014a) Intercomparing different devices for the investigation of ice nucleating particles using Snomax as test substance, Atmos. Chem. Phys. Discuss. (accepted for ACP), 14, 22321-22384, 2014. Wex, H., P. J. DeMott, Y. Tobo, S. Hartmann, M. Rsch, T. Clauss, L. Tomsche, D. Niedermeier, and F. Stratmann (2014b), Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings, Atmos. Chem. Phys., 14, doi:10.5194/acp-14-5529-2014.

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

    Microsoft Academic Search

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

    1965-01-01

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

  4. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates

    NASA Technical Reports Server (NTRS)

    Johnson, N. M.; Meibom, A.; Ferguson, F. T.; Nuth, J. A., III

    2004-01-01

    Temperatures high enough to vaporize even refractory solids existed in the midplane of the solar nebula during its earliest evolutionary stages and played an important role in the processing of materials that went into the formation of the inner planets and asteroids. A variety of such high-T materials have been identified in primitive chondritic meteorites. These include chemically zoned FeNi metal grains that are generally believed to have formed directly by gas-solid condensation from a gas of approximately solar composition. These FeNi particles provide important information about the times scales of formation and physical transport mechanisms in the nebula, as well as formation temperature, pressure and gas chemistry. Currently, however, the interpretation of the chemical signatures in these FeNi particles rests on less than perfect information about the condensation sequence of siderophile elements. For example much, if not all, of the thermodynamic data for the vapor pressures of moderately refractory metals , such as Fe, Ni and Co, do not cover the desired temperature range. As a result, quite large extrapolations are needed. These extrapolations can be complex and uncertain due to factors such as oxygen fugacity or the presence of hydrogen gas.

  5. Simultaneous determination of residual saturation and capillary pressure curves utilizing the ultracentrifuge

    SciTech Connect

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

    1986-01-01

    Residual saturation and capillary pressure curves are important for modelling reservoir and laboratory processes. Knowledge of the residual saturation curve is necessary to determine the ultimate production from a tertiary recovery process. Capillary pressure is required to interpret laboratory core floods and to describe multi-phase reservoir fluid flow. The ultracentrifuge provides a rapid means of determining capillary pressure and residual saturation relationships. It is non-destructive, uses small samples, and is capable of attaining both high capillary pressures and extremely low residual saturations. The effects of variation in residual saturation with Bond number are not included in the traditional Hassier-Brunner analysis for capillary pressure. Such desaturation effects can explain the anomalous experimental saturation distributions reported at high rotation rates. The current work generalizes the Hassler-Brunner analysis to include desaturation and also to include the variation in centripeta acceleration through the core. The analysis also provides for the determination of residual saturation as a function of Bond number (k..delta..rhog/sigma.

  6. The Vapor Pressures and Derived Thermal Properties of Hydrogen and Deuterium

    Microsoft Academic Search

    R. B. Scott; F. G. Brickwedde; Harold C. Urey; M. H. Wahl

    1934-01-01

    (1) The vapor pressure equations of liquid and solid, normal deuterium were determined by comparison of the vapor pressure of deuterium with that of liquid, normal hydrogen between 13.9 and 20.40K. The triple and boiling points of deuterium were found to be 18.58 and 23.5K, respectively. (2) The changes with time in the vapor pressures of liquid hydrogen and liquid

  7. The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of aluminium chloride, aluminium nitrate and aluminium sulphate

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    2002-01-01

    Vapour pressures of water over saturated solutions of aluminium chloride, aluminium nitrate and aluminium sulphate were determined as a function of temperature. The vapour pressures served to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. Molar enthalpies of solution of aluminium chloride hexahydrate, ?solHm(AlCl36H2O, T=295.02K, m=0.02084molkg?1)=?(54.62.1)kJmol?1, aluminium nitrate nonahydrate, ?solHm(Al(NO3)39H2O; T=296.62K, m=0.01342molkg?1)=(30.71.0)kJmol?1 and aluminium sulphate octadecahydrate, ?solHm(Al2(SO4)318H2O,

  8. A Simultaneous Monitoring System for Non-Invasive Blood Pressure and Blood Oxygen Saturation

    Microsoft Academic Search

    Shumei Gao; Yilin Song

    2010-01-01

    A simultaneous monitoring system for blood pressure and blood oxygen saturation based on the volume-oscillometric method and the dual-wavelength spectrophotometry is developed, and principle of the dual-wavelength spectrophoto-metry for measurement of blood oxygen saturation is introduced in this research. Also, the local pressurizing cuff unit and the photo-detector are development. A preliminary experiment using the system is carried out. The

  9. Rate of water equilibration in vapor-diffusion crystallization: dependence on the residual pressure of air in the vapor space.

    PubMed

    DeTitta, G T; Luft, J R

    1995-09-01

    The kinetics of water equilibration in vapor-diffusion crystallization experiments are sensitive to the residual pressure of air in the vapor chamber. Experiments with sitting droplets of 10%(w/v) PEG, allowed to equilibrate with reservoirs of 20%(w/v) PEG, were conducted at pressures ranging from 80 to 760 mm Hg. Equilibrations were interrupted after one, four, five and seven days to assess their progress. Even down to the lowest pressures examined it was found that a decrease in pressure leads to an increase in the rate of equilibration. The residual pressure of air in the vapor chamber can be varied to tailor the time course of equilibration in macromolecular crystal growth experiments. PMID:15299810

  10. Effects of pressure and partial water saturation on gas permeability in tight sands: experimental results

    SciTech Connect

    Walls, J.D.; Nur, A.M.; Bourbie, T.

    1980-01-01

    Effective permeability to gas with varying degrees of brine saturation has been measured in the laboratory on several tight sandstones from the Spirit River formation of Alberta, Canada. Gas permeability as low as 2 x 10/sup -8/ darcy was successfully measured using a pulse decay permeameter with nitrogen as the mobile fluid. Results show a very strong dependence of gas permeability on degree of saturation with 40% saturation causing an order of magnitude decrease in permeability relative to the dry rock. Accurate knowledge of in situ saturations is crucial before estimates of natural gas production rates can be made in these formations. The experiments also show that confining pressure causes significant permeability reduction in these sandstones. It also was found that as brine saturation was increased the sensitivity of the rock's permeability to small changes in confining pressure was increased.

  11. Simultaneous measurements of relative permeability, capillary pressure, and elecrical resistivity with microwave system for saturation monitoring

    SciTech Connect

    Honarpour, M.M.; Huang, D.D.; Dogru, A.H.

    1995-12-31

    Accurate relative permeability (k{sub r}) and capillary pressure (P{sub c}) data are essential for predicting the performance of hydrocarbon reservoirs. Traditionally, k, and P, are measured independently in different experimental systems, and rarely on the same samples under identical conditions. However, because than properties can be very sensitive to the same variables, simultaneous measurements are needed for consistency and for rigorous modeling. It is also important to have the capability to establish field-observed initial water saturations in laboratory tests because relative permeability and capillary pressure during imbibition rely on the values of the initial water saturations. A novel apparatus has been constructed to allow simultaneous measurements of capillary pressure, relative permeability, and electrical resistivity on cores up to 2 inches diameter and 6 inches long. Fluid saturation profile is monitored by a state-of-the-art microwave technique. A microwave scanner moves along the core, and in-situ fluid saturation is calculated from the transmitted signal intensity. This method does not require tagging fluids which may affect wetting properties. The apparatus can reduce water saturation to a low initial value and can operate at moderate temperature, overburden stress, and fluid pressure. It is equipped with an in-line viscometer for continuous and accurate monitoring of oil viscosity. In this paper, the unique features of the apparatus is presented, along with some capillary pressure and relative permeability data measured simultaneously at elevated temperature and pressure.

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

    E-print Network

    Chen, Hui; Rostovtsev, Yuri V; Gubin, Mikhail A; Sautenkov, Vladimir A; Scully, Marlan O

    2009-01-01

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

  13. Vapor pressures in the ternary system water-nitric acid-sulfuric acid and low temperatures

    Microsoft Academic Search

    A. Jaecker-Voirol; J. L. Ponche; P. Mirabel

    1990-01-01

    The partial vapor pressures over liquid or supercooled solutions of water and nitric acid and of water and sulfuric acid are calculated for temperatures below 0 C. From these results, the partial vapor pressures over the tenary system water-nitric acid-sulfuric acid (liquid or supercooled) have been estimated and compared with the available experimental data of Vandoni (1944) at 0 C.

  14. Thermogravimetric determination of vapor pressure of diffusion pump oils by Knudsen effusion cell technique

    Microsoft Academic Search

    Steckel

    1980-01-01

    A procedure has been developed for the determination of vapor pressure of diffusion pump oils using a Knudsen effusion cell in conjunction with a vacuum balance. The extrapolated vapor pressure of the diffusion pump oils evaluated ranged from 4 x 10⁻⁸ to 2 x 10⁻⁶ torr at 20°C.

  15. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, M.W.; Biblarz, O.

    1991-10-15

    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.

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

    SciTech Connect

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

    2005-08-01

    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.

  17. Rapid measurements of boiling point and vapor pressure of short-chain triglycerides by thermogravimetric analysis

    Microsoft Academic Search

    J. W. Goodrum

    1997-01-01

    Temperature dependence of vapor pressure and the boiling points for tricaproin (Tcap) and tricaprylin (Tcpy) were measured\\u000a by a new rapid thermogravimetric analysis (TGA) method. Results were in agreement with data from other references. The Clausius\\/Clapeyron\\u000a model fitted Tcap and Tcpy vapor pressure data with errors of 6% or less for pressures ranging from ambient down to 20 mmHg.\\u000a This

  18. Correlation of chemical evaporation rate with vapor pressure.

    PubMed

    Mackay, Donald; van Wesenbeeck, Ian

    2014-09-01

    A new one-parameter correlation is developed for the evaporation rate (ER) of chemicals as a function of molar mass (M) and vapor pressure (P) that is simpler than existing correlations. It applies only to liquid surfaces that are unaffected by the underlying solid substrate as occurs in the standard ASTM evaporation rate test and to quiescent liquid pools. The relationship has a sounder theoretical basis than previous correlations because ER is correctly correlated with PM rather than P alone. The inclusion of M increases the slope of previous log ER versus log P regressions to a value close to 1.0 and yields a simpler one-parameter correlation, namely, ER (?g m(-1) h(-1)) = 1464P (Pa) M (g mol(-1)). Applications are discussed for the screening level assessment and ranking of chemicals for evaporation rate, such as pesticides, fumigants, and hydrocarbon carrier fluids used in pesticide formulations, liquid consumer products used indoors, and accidental spills of liquids. The mechanistic significance of the single parameter as a mass-transfer coefficient or velocity is discussed. PMID:25105222

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

    SciTech Connect

    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

    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.

  20. The vapor pressure of indium, silver, gallium, copper, tin, and gold between 0.1 and 3.0 bar

    Microsoft Academic Search

    F. Geiger; C. A. Busse; R. I. Loehrke

    1987-01-01

    The vapor pressure of several liquid metals was measured using a method based on the gas-controlled heat pipe. Small samples of the test material were placed in a tungsten tube and heated to temperatures above 2900 K. The vapor pressure was measured using a gas-buffered pressure transducer and the vapor temperature was inferred from the tube surface temperature, which was

  1. Evaporation monitoring and composition control of alloy systems with widely differing vapor pressures

    SciTech Connect

    Anklam, T.M.; Berzins, L.V.; Braun, D.G.; Haynam, C.; McClelland, M.A.; Meier, T. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    Lawrence Livermore National Laboratory is developing sensors and controls to improve and extend electron beam materials processing technology to alloy systems with constituents of widely varying vapor pressure. The approach under development involves using tunable lasers to measure the density and composition of the vapor plume. A laser based vaporizer control system for vaporization of a uranium-iron alloy has been previously demonstrated in multi-hundred hour, high rate vaporization experiments at LLNL. This paper reviews the design and performance of the uranium vaporization sensor and control system and discusses the extension of the technology to monitoring of titanium vaporization. Data is presented from an experiment in which titanium wire was fed into a molten niobium pool. Laser data is compared to deposited film composition and film cross sections. Finally, the potential for using this technique for composition control in melting applications is discussed.

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

    EPA Science Inventory

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

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

    Microsoft Academic Search

    J. B. Walsh; E. R. Decker

    1966-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Gao, L.; Morozov, I. B.

    2011-12-01

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

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

    SciTech Connect

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

    2002-06-10

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

  6. 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 ...

  7. CORRELATIONS BETWEEN VAPOR SATURATION, FLUID COMPOSITION, AND WELL DECLINE IN LARDERELLO

    SciTech Connect

    D'Amore, F.; Pruess, K.

    1985-01-22

    A large body of field data from Larderello shows striking temporal correlations between decline of well flow-rate, produced gas/steam ratio, chloride concentration and produced vapor fraction. The latter is inferred from measured concentrations of non-condensible gases in samples of well fluid, using chemical phase equilibrium principles. Observed temporal changes in the vapor fractions can be interpreted in term of a ''multiple source'' model, as suggested by D'Amore and Truesdell (1979). This provides clues to the dynamics of reservoir depletion, and to the evaluation of well productivity and longevity.

  8. Satellite-based estimation of surface vapor pressure deficits using MODIS land surface temperature data

    Microsoft Academic Search

    Hirofumi Hashimoto; Jennifer L. Dungan; Michael A. White; Feihua Yang; Andrew R. Michaelis; Steven W. Running; Ramakrishna R. Nemani

    2008-01-01

    Vapor Pressure Deficit (VPD) is a principle mediator of global terrestrial CO2 uptake and water vapor loss through plant stomata. As such, methods to estimate VPD accurately and efficiently are critical for ecosystem and climate modeling efforts. Based on prior work relating energy partitioning, remotely sensed land surface temperature (LST), and VPD, we developed simple linear models to predict VPD

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

    SciTech Connect

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

    1994-12-15

    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.

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

    E-print Network

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

    2012-01-01

    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 ...

  11. The Oxidation Rate of SiC in High Pressure Water Vapor Environments

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Robinson, R. Craig

    1999-01-01

    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.

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

    EPA Science Inventory

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

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

    E-print Network

    Reina Ceeco, Alfonso

    2010-01-01

    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 ...

  14. Saturation effects in the sub-Doppler spectroscopy of cesium vapor confined in an extremely thin cell

    SciTech Connect

    Andreeva, C.; Cartaleva, S.; Petrov, L.; Saltiel, S. M.; Sarkisyan, D.; Varzhapetyan, T.; Bloch, D.; Ducloy, M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shosse Boulevard, 1784 Sofia (Bulgaria); Faculty of Physics, Sofia University, 5 J. Bourchier Boulevard, 1164 Sofia (Bulgaria); Institute for Physical Research, NAS of Armenia, Ashtarak-2 (Armenia); Laboratoire de Physique des Lasers UMR 7538 du CNRS, Universite Paris-13, F-93430 Villetaneuse (France)

    2007-07-15

    Saturation effects affecting absorption and fluorescence spectra of an atomic vapor confined in an extremely thin cell (cell thickness L<1 {mu}m) are investigated experimentally and theoretically. The study is performed on the D{sub 2} line ({lambda}=852 nm) of Cs and concentrates on the two situations L={lambda}/2 and L={lambda}, the most contrasted ones with respect to the length dependence of the coherent Dicke narrowing. For L={lambda}/2, the Dicke-narrowed absorption profile simply broadens and saturates in amplitude when increasing the light intensity, while for L={lambda}, sub-Doppler dips of reduced absorption at the line-center appear on the broad absorption profile. For a fluorescence detection at L={lambda}, saturation induces narrow dips, but only for hyperfine components undergoing a population loss through optical pumping. These experimental results are interpreted with the help of the various existing models and are compared with numerical calculations based upon a two-level modeling that considers both a closed and an open system.

  15. Vaporizing Vapor

    NSDL National Science Digital Library

    2012-08-03

    In this demonstration, relative humidity is modeled using a sponge and a pan of water, and the concept of saturation is depicted. Students answer questions examining the relationship between temperature and the capacity of air to hold water vapor. The resource is part of the teacher's guide accompanying the video, NASA Sci Files: The Case of the Phenomenal Weather. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

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

    USGS Publications Warehouse

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

    1990-01-01

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

  17. Vapour pressures of saturated aqueous solutions of ammonium iodide, potassium iodide, potassium nitrate, strontium chloride, lithium sulphate, sodium thiosulphate, magnesium nitrate, and uranyl nitrate from T =(278 to 323) K

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    1998-01-01

    Vapour pressures of saturated aqueous solutions of NH4I, KI, KNO3, SrCl2, Li2SO4, Na2S2O3, Mg(NO3)2, and UO2(NO3)2were determined in the temperature range (278 to 323) K using an electronic hygrometer with an electrolyte sensor, and compared with literature data. Water activities, osmotic coefficients, and molar enthalpies of vaporization and solution at saturation point were evaluated from the determined vapour pressures.

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

    E-print Network

    Grossman, Lawrence

    VAPOR PRESSURES AND EVAPORATION COEFFICIENTS OF FE, NA AND K OVER CHONDRULE COMPOSITION MELTS. A. V Institute, University of Chicago, Chicago, IL 60637. avf@uchicago.edu. Introduction: Although vapor, , RTm2 P J x v xx x = in which ,P,m v xx and x are the molecular weight, equilibrium vapor pressure

  19. Oxygen saturation changes in the optic nerve head during acute intraocular pressure elevation in monkeys

    NASA Astrophysics Data System (ADS)

    Khoobehi, Bahram; Kawano, Hiroyuki; Ning, Jinfeng; Burgoyne, Claude F.; Rice, David A.; Khan, Fareeha; Thompson, Hilary W.; Beach, James M.

    2009-02-01

    Background and Objective: To evaluate the effect of an acute elevated intraocular pressure (IOP) on oxygen saturation of structures of the optic nerve head. Study Design/Materials and Methods: In the cynomolgus monkey eye, IOP was set to 10 mm Hg, and then raised to 30, 45, and 55 mm Hg. The ONH and overlying vessels were imaged using a fundus camera attached to a hyperspectral imaging system (HSI) at 10 and 30 minutes after IOP elevation. Results: Raising IOP from 10 to 30 mm Hg did not significantly (P < 0.0001) change saturation in vessels or ONH tissue structures but at 55 mm Hg, all structures showed significant reduction. Conclusions: Quantitative assay of the blood oxygen saturation in structures on the surface and overlying the optic nerve head is possible using hyperspectral imaging techniques.

  20. Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated Vapor

    E-print Network

    Bulavin, L A; Makhlaichuk, V N

    2015-01-01

    Water is the most common substance on Earth.The discovery of heavy water and its further study have shown that the change of hydrogen for deuterium leads to the significant differences in their properties.The triple point temperature of heavy water is higher,at the same time the critical temperature is lower.Experimental values of the second virial coefficient of the EOS for the vapor of normal and heavy water differ at all temperatures.This fact can influence the values of the dimerization constant for the heavy water vapor.The equilibrium properties of the dimerization process are described with the methods of chemical thermodynamics.The chemical potentials for monomers (m) and dimers (d)are the functions of their concentrations.The interactions of monomer-dimer and dimer-dimer types are taken into account within the solution of equation for chemical potentials.The obtained expression for the dimerization constant contains the contributions of these types.The averaged potentials are modeled by the Sutherlan...

  1. The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some cesium salts

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    2006-01-01

    Vapour pressures of water over saturated solutions of cesium chloride, cesium bromide, cesium nitrate, cesium sulfate, cesium formate, and cesium oxalate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vapourization. Molar enthalpies of solution of cesium chloride, ?solHm(T=295.73 K; m=0.0622 molkg?1)=(17.830.50) kJmol?1; cesium bromide, ?solHm(T=293.99

  2. The dynamics of vapor bubbles in acoustic pressure fields

    NASA Astrophysics Data System (ADS)

    Hao, Y.; Prosperetti, A.

    1999-08-01

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

  3. A Multiscale Simulator for Low Pressure Chemical Vapor Deposition

    Microsoft Academic Search

    Matthias K. Gobbert

    1997-01-01

    An integrated simulator for chemical vapor deposition is introduced. In addition to areactor scale and feature scale simulators, it consists of a "mesoscopic" scale simulator withthe typical length scale of a die. It is shown that the "three-scale" integrated simulator usedis a proper extension of "two-scale" deposition simulators that consist of reactor scale andfeature scale simulation models. Moreover, it is

  4. Can atmospheric pressure and water table fluctuations be neglected in soil vapor extraction?

    Microsoft Academic Search

    Kehua You; Hongbin Zhan

    Solutions to soil vapor extraction (SVE) are indispensable to characterize the unsaturated zone and to optimize SVE. Most of the existing solutions neglect the fluctuations of atmospheric pressure and water table. This study presents a new semi-analytical solution for SVE by considering the atmospheric pressure and water table fluctuations. Comparisons between the new and previous solutions indicate that the water

  5. Microwave measurements of water vapor partial pressure at temperatures up to 350{degree}C

    SciTech Connect

    Latorre, V.

    1989-09-01

    This paper describes the theory of operation, design, construction, calibration and installation of a microwave coaxial resonator system for measuring the partial pressure of water vapor in air at temperatures up to 350{degree}C. This is a relevant measurement for characterizing the unsaturated zone because the partial pressure of water vapor in the air in equilibrium with a rock mass is related to the capillary pressure of the rock. Microwave resonators can operate at high temperatures and, therefore, are the subject of this discussion. 7 refs., 8 figs.

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

    PubMed Central

    McPherson, Timothy B.

    2013-01-01

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

  7. The influence of surfactant sorption on capillary pressure-saturation relationships

    SciTech Connect

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

    1991-01-01

    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.

  8. The influence of surfactant sorption on capillary pressure-saturation relationships

    SciTech Connect

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

    1991-12-31

    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.

  9. Thermodynamic characterization of vaporization of the fourth group elements

    Microsoft Academic Search

    M. M. Stevanovic

    1983-01-01

    Thermodynamic characterization of silicon, germanium, tin, and lead vaporization is performed by the method applied earlier to alkali metals and carbon, i.e., by evaluation of analytical expressions representing dependence of the second virial coefficient and vapor pressure on temperature. Starting from saturation pressure values given as a sum of partial pressure of present species, through a modified procedure applied before

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

    Microsoft Academic Search

    Murat Kaya; Mrvet Volkan

    2011-01-01

    A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl4). In order to do so, a novel joint vapor production and gasliquid separation unit equipped with a

  11. Influence of temperature gradients on partial pressures in a low-pressure chemical-vapor-deposition reactor

    NASA Astrophysics Data System (ADS)

    Oosterlaken, T. G. M.; Leusink, G. J.; Janssen, G. C. A. M.; Radelaar, S.; Kuijlaars, K. J.; Kleijn, C. R.; van den Akker, H. E. A.

    1994-09-01

    Measurements and calculations of the influence of temperature gradients on the partial pressures of the gas species in a cold-wall chemical-vapor-deposition reactor are presented. The experiments were performed at low pressures (300-500 Pa total pressure) and gas mixtures consisting of hydrogen, nitrogen, and tetrafluoromethane. The partial pressures were determined by Raman spectroscopy. The Soret effect (or thermal diffusion) has a large influence on the partial pressures of heavy gases in the vicinity of the heated wafer. In some cases a decrease in partial pressure of 20% compared to the inlet partial pressures was observed. Numerical calculations were performed to predict the behavior of the gas mixture. For mixtures under investigation the gas temperatures as well as the changes in partial pressures due to the Soret effect were predicted correctly.

  12. Kinetics of silicon-germanium deposition by atmospheric-pressure chemical vapor deposition

    Microsoft Academic Search

    T. I. Kamins; D. J. Meyer

    1991-01-01

    The deposition of Si1?xGex alloy layers in an atmospheric-pressure, chemical vapor deposition reactor has been studied by separately examining the silicon and the germanium components of the deposition rate. The overall deposition rate increases approximately linearly with GeH4 partial pressure, but is relatively independent of SiH2Cl2 partial pressure. The silicon component of the deposition rate increases rapidly with increasing temperature

  13. Generation of ultrahigh pressure using single-crystal chemical-vapor-deposition diamond anvils

    NASA Astrophysics Data System (ADS)

    Mao, Wendy L.; Mao, Ho-kwang; Yan, Chih-shiue; Shu, Jinfu; Hu, Jingzhu; Hemley, Russell J.

    2003-12-01

    Two experiments were conducted compressing Ta, Re, Pt, and an Fe-Si alloy to ultrahigh pressures using single-crystal chemical vapor deposition (CVD) and natural diamonds. In situ energy-dispersive and angle-dispersive x-ray diffraction were used to determine pressure from known equations of state. We demonstrate that CVD diamonds can be used in diamond anvil cells to reach pressures of nearly 200 GPa.

  14. Se vapor pressure dependence of the phase diagram of the CuGa 1? x In x Se 2 system

    Microsoft Academic Search

    Hiroaki Matsushita; Takeo Takizawa

    1998-01-01

    Phase transition points of the CuGa1?xInxSe2 system are investigated by the differential thermal analysis with varying Se vapor pressure up to 760Torr. The phase diagrams constructed under controlled Se vapor pressure show that the solidus and liquidus points decrease more than 100C with increasing Se vapor pressure, and that the temperature zone of the (sphalerite+liquid) phase narrows in the region

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  16. Numerical modelling of pore-pressure measurements in saturated sandy seabed sediments

    SciTech Connect

    Magda, W. [Technical Univ. of Gdansk (Poland). Marine Civil Engineering Dept.

    1995-12-31

    The question of model conditions (i.e., saturation procedure and temporal dewatering of soil model, as well as existence of a geotextile on the top of seabed model and existence of pore-pressure transducers itself in seabed sediments) in large-scale modelling is discussed with respect to the quality of measured pore-pressure values. The meaning of locally unsaturated zones within the seabed model, due to an improper installation procedure or man-made mistake during the testing period, are illustrated by some example computations, based on 2-D finite-element model, the results of which are presented in terms of the momentaneous pore-pressure distribution with depth, induced by surface harmonic waves passing over the seabed.

  17. Preconcentrator with high volume chiller for high vapor pressure particle detection

    DOEpatents

    Linker, Kevin L

    2013-10-22

    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.

  18. Performance of thin-film transistors on polysilicon films grown by low-pressure chemical vapor deposition at various pressures

    Microsoft Academic Search

    Charalabos A. Dimitriadis; Penelope A. Coxon; Laszlo Dozsa; Leonidas Papadimitriou; Nicolaos Economou

    1992-01-01

    Defect properties of undoped low-pressure chemical-vapor-deposited (LPCVD) polysilicon films have been investigated by capacitance techniques on a simple metal-oxide-semiconductor (MOS) capacitor structure. The results show that the effective density of bulk and interface trap states is almost independent of the deposition pressure. After reducing the polysilicon film thickness by etching, although the grain size decreases due to the columnar mode

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

    EPA Science Inventory

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

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

    SciTech Connect

    Kuhne, W.

    2012-12-03

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

  1. Tetrakis(trimethylsilyl)silane: Temperature dependence of vapor pressure, kinetics, and silicon carbide thin films by plasma-assisted liquid injection chemical vapor deposition process

    Microsoft Academic Search

    J. Selvakumar; D. Sathiyamoorthy; K. S. Nagaraja

    2011-01-01

    Thermal stability, vapor pressure, enthalpy of sublimation and activation energy of tetrakis(trimethylsilyl)silane (TMSS) were investigated by non-isothermal and isothermal thermogravimetric (TG) analysis, which revealed good thermal stability, high volatility with a nil residue. The temperature dependence of vapor pressure measured by using a horizontal dual arm single furnace thermo-analyzer as a transpiration apparatus gave a value of 51.31.9kJmol?1 for the

  2. Saturation meter

    DOEpatents

    Gregurech, S.

    1984-08-01

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

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

    Microsoft Academic Search

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

    2005-01-01

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

  4. Ultrarapid flow-through polymerase chain reaction microfluidics using vapor pressure

    Microsoft Academic Search

    Yusuke Fuchiwaki; Hidenori Nagai; Masato Saito; Eiichi Tamiya

    2011-01-01

    A novel flow-through polymerase chain reaction (PCR) microfluidic system using vapor pressure was developed that can achieve ultra-rapid, small-volume DNA amplification on a chip. The 40-cycle amplification can be completed in as little as 120s, making this device the fastest PCR system in the world. The chip device is made of a pressure-sensitive polyolefin (PSP) film and cyclo-olefin polymer (COP)

  5. Impact of Vapor Pressure Deficit on the Performance of Bemisia tabaci: Adult, Nymphal, and Egg Survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The B-biotype sweetpotato whitefly, Bemisia tabaci, is a serious global pest with varying population dynamics among different ecosystems. An experiment was conducted to assess the impact of vapor pressure deficit (VPD) on the survival of adults, nymphs and eggs of B. tabaci. The insects were reared...

  6. Evaluation of Vapor Pressure and UltraHigh Vacuum Tribological Properties of Ionic Liquids

    Microsoft Academic Search

    Wilfredo Morales; Victor R. Koch; Daniel J. Valco; Ryan M. Richard; Nicole Hanks

    2011-01-01

    Ionic liquids are a class of salts that incorporate polyatomic anions and cations. These materials are typically viscous fluids at room temperature. The fluids are generally characterized as possessing negligible vapor pressures under ambient conditions. These beneficial properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as lubricants with space

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

    PubMed

    Goldfarb, Jillian L; Suuberg, Eric M

    2008-06-01

    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(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. PMID:18220445

  8. Vapor pressure deficit effects on leaf area expansion and transportation of soybean subjected to soil drying

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of leaf-to-air vapor pressure difference (VPD) and soil water deficit on transpiration rate (TR) of plants are well understood but their effects on plant leaf area expansion (PLAE) are less defined. Both PLAE and TR are unaffected by soil drying until the fraction transpirable soil water (FT...

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

    USGS Publications Warehouse

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

    1978-01-01

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

  10. Design concept for pressure switch calibrator

    NASA Technical Reports Server (NTRS)

    Slingerland, M. G.

    1966-01-01

    Calibrator and switch design enables pressure switches to operate under 150 g shock loads. The design employs a saturated liquid-to-vapor phase transition at constant pressure to produce a known force independent of displacement over a usable range.

  11. Vapor pressure of indium, silver, gallium, copper, tin, and gold between 0. 1 and 3. 0 bar

    SciTech Connect

    Geiger, F.; Busse, C.A.; Loehrke, R.I.

    1987-07-01

    The vapor pressure of several liquid metals was measured using a method based on the gas-controlled heat pipe. Small samples of the test material were placed in a tungsten tube and heated to temperatures above 2900 K. The vapor pressure was measured using a gas-buffered pressure transducer and the vapor temperature was inferred from the tube surface temperature, which was measured with an optical pyrometer. Most of the tests were terminated by the failure of the containment tube. The measured pressures agree well with those calculated by thermodynamic methods from data at lower temperatures.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  13. Advanced Computational Modeling of Vapor Deposition in a High-Pressure Reactor

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  14. Adiabatic pressure dependence of the 2.7 and 1.9 micron water vapor bands

    NASA Technical Reports Server (NTRS)

    Mathai, C. V.; Walls, W. L.; Broersma, S.

    1977-01-01

    An acoustic excitation technique is used to determine the adiabatic pressure derivative of the spectral absorptance of the 2.7 and 1.9 micron water vapor bands, and the 3.5 micron HCl band. The dependence of this derivative on thermodynamic parameters such as temperature, concentration, and pressure is evaluated. A cross-flow water vapor system is used to measure spectral absorptance. Taking F as the ratio of nonrigid to rotor line strengths, it is found that an F factor correction is needed for the 2.7 micron band. The F factor for the 1.9 micron band is also determined. In the wings of each band a wavelength can be found where the concentration dependence is predominant. Farther out in the wings a local maximum occurs for the temperature derivative. It is suggested that the pressure derivative is significant in the core of the band.

  15. Investigations of dc electrical discharges in low-pressure sodium vapor with implications for AMTEC converters

    SciTech Connect

    Barkan, A.; Hunt, T.K.

    1998-07-01

    Upcoming designs for AMTEC modules capable of delivering as much as 150 watts will see the introduction of higher voltages into sodium vapor at pressures spanning a wide range. In theory, with any value for two out of three parameters: voltage, pressure, and electrode geometry, a value exists for the third parameter where DC electrical breakdown can occur; due to its low ionization energy, sodium vapor may be particularly susceptible to breakdown. This destructive event is not desirable in AMTEC modules, and sets a limit on the maximum voltage that can be built-up within any single enclosed module. An experimental cell was fabricated with representative electrode configurations and a separately heated sodium reservoir to test conditions typically expected during start-up, operation, and shutdown of AMTEC cells. Breakdown voltages were investigated in both sodium vapor and, for comparison, argon gas. The dependence on electrode material and polarity was also investigated. Additional information about leakage currents and the insulating properties of {alpha}-alumina in the presence of sodium vapor was collected, revealing a reversible tendency for conductive sodium films to build up under certain conditions, electrically shorting-out previously isolated components. In conclusion, safe operating limits on voltages, temperatures, and pressures are discussed.

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

    E-print Network

    Findley, Gary L.

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

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

    PubMed

    Hrabina, Jan; arbort, Martin; Acef, Ouali; Burck, Frdric Du; Chiodo, Nicola; Hol, Miroslava; ?p, Ond?ej; Lazar, Josef

    2014-11-01

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

  18. Experimental Investigation of the Effect of Pressure and Fluid Saturation on Carbonate Rocks

    NASA Astrophysics Data System (ADS)

    Scotellaro, C.; Vanorio, T.; Mavko, G.

    2006-12-01

    Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismic velocities. Although Gassmann's model is generally successful in medium to high porosity sandstones, its appropriateness for quantifying fluid effects in carbonate rocks is questioned in literature. Questions rice from the model assumptions which, very likely oversimplify the complex rock-fluid interaction in carbonates. Critical issues include 1) rock-fluid chemical interaction (e.g. dissolution), violating Gassmann's purely mechanical model, and 2) substantial pore fabric heterogeneity, potentially violating Gassmann's assumption of good fluid mobility in a well-connected pore space. We present the preliminary results of measurements showing the variation of Vp and Vs as a function of pressure and fluid saturation. Theoretical velocities predicted by Gassmann's equation are also shown for comparison. Different saturating fluids, an inert gas (Helium) and degassed, distilled water are used to create experimental conditions that vary one fluid interaction at a time. The goal is to identify the conditions (i.e. fluid type, pressure, pore shape distribution) under which the assumptions of Gassman's theory may apply to carbonates and evaluate which conditions appear to be responsible for the failure of the seismic property prediction. Carbonate samples (porosity range from 5% to 50%) from Gravina di Puglia (Bari, Italy), and Monte Sant'Angelo and Peschici (Foggia, Italy) have been classified based on mineralogy, pore type and connectivity. From each sample, 2 core plugs have been extracted and used for measurements. Dissolution (i.e., changes to the rock framework) is expected to be different for different pore fluids. Hence, seismic fluid substitution in carbonates is likely more than a purely mechanical problem.

  19. Preliminary Heat Capacity and Vapor Pressure Measurements of 2D 4He on ZYX Graphite

    NASA Astrophysics Data System (ADS)

    Nakamura, S.; Matsui, K.; Matsui, T.; Fukuyama, Hiroshi

    2013-06-01

    We report preliminary heat capacity and vapor pressure measurements of the first and second layers of 4He adsorbed on ZYX graphite. ZYX is known to have much better crystallinity than Grafoil, the most commonly-used exfoliated graphite substrate, such as a ten-times larger platelet size. This allows us to distinguish different phases in 2D 4He much more clearly and may provide qualitatively different insights into this system. We found a significantly asymmetric density-dependence of the heat-capacity peak associated with the sqrt{3}sqrt{3} phase formation comparing with that obtained with Grafoil. The 2nd-layer promotion density is determined as 11.80.3 nm-2 from the heat-capacity measurement of low density samples in the 2nd layer and vapor pressure measurement.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    We 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.

  1. Observations on vapor pressure in SPR caverns : sources.

    SciTech Connect

    Munson, Darrell Eugene

    2010-05-01

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

  2. Atmospheric pressure chemical vapor deposition of TiN from tetrakis(dimethylamido)titanium and ammonia

    Microsoft Academic Search

    J. N. Musher; R. G. Gordon

    1996-01-01

    Near stoichiometric titanium nitride (TiN) was deposited from tetrakis(dimethylamido)titanium (TDMAT) and ammonia using atmospheric pressure chemical vapor deposition. Experiments were conducted in a belt furnace; static experiments provided kinetic data and continuous operation uniformly coated 150-mm substrates. Growth rate, stoichiometry, and resistivity are examined as functions of deposition temperature (190420C), ammonia flow relative to TDMAT (030), and total gas-flow rate

  3. Surface electron accumulation in indium nitride layers grown by high pressure chemical vapor deposition

    Microsoft Academic Search

    R. P. Bhatta; B. D. Thoms; M. Alevli; N. Dietz

    2007-01-01

    Surface termination and electronic properties of InN layers grown by high pressure chemical vapor deposition have been studied by high resolution electron energy loss spectroscopy (HREELS). HREEL spectra from InN after atomic hydrogen cleaning show NH termination with no indium overlayer or droplets and indicate that the layer is N-polar. Broad conduction band plasmon excitations are observed centered at 3400cm?1

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

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1973-01-01

    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.

  5. Interface delamination in plastic IC packages induced by thermal loading and vapor pressure - a micromechanics model

    Microsoft Academic Search

    P. Liu; L. Cheng; Y.-W. Zhang

    2003-01-01

    A micromechanics model and an associated computational scheme are proposed to study interface delamination in plastic integrated circuit (IC) packages induced by thermal loading and vapor pressure. The die and die-pad are taken as elastic materials, while the die-attach and molding compound are taken as elasto-visco-plastic materials. The interface between molding compound and the die-pad is characterized by a cohesive

  6. Density, vapor pressure, solubility, and viscosity for water + lithium bromide + lithium nitrate + 1,3-propanediol

    Microsoft Academic Search

    Young Park; Jin-Soo Kim; Huen Lee; Sun Il Yu

    1997-01-01

    Four physical properties (solubility, vapor pressure, density, and viscosity) of water + lithium bromide + lithium nitrate + 1,3-propanediol (LiBr\\/LiNO mole ratio = 4, (LiBr + LiNO)\\/HO(CH)OH mass ratio = 3.5) were measured. The system, a possible working fluid for an absorption heat pump, mainly consists of absorbent (LiBr + LiNO + HO(CH)OH) and refrigerant (HO). Solubilities were measured by

  7. Crystallization of amorphous silicongermanium films deposited by low pressure chemical vapor deposition

    Microsoft Academic Search

    D. Guillet; M Sarret; L Haji; R Rogel; O Bonnaud

    2000-01-01

    Thin films of SiGe were prepared on SiO2 by low pressure chemical vapor deposition (LPCVD) from SiH4 and GeH4. With this technique there is in situ control of incorporation of germanium in SiGe films. In the deposition conditions, films of Si1?xGex are deposited amorphous. The parameters of crystallization kinetics of amorphous films are studied by in situ measurements of the

  8. Effect of silicon source gas on silicon-germanium chemical vapor deposition kinetics at atmospheric pressure

    Microsoft Academic Search

    T. I. Kamins; D. J. Meyer

    1992-01-01

    Epitaxial Si1?xGex alloy layers have been deposited in an atmospheric-pressure, chemical-vapor-deposition reactor using dichlorosilane, silane, and disilane, along with germane. The deposition rate increases and the Ge content decreases with increasing reactivity of the silicon-containing gas. The rate increases monotonically with increasing Ge content in the layer for all three gases, in contrast to the behavior seen in systems operating

  9. Pressure sensor using polycrystalline germanium films prepared by plasma assisted chemical vapor deposition

    Microsoft Academic Search

    K. Kamimura; N. Kimura; S. Miyashita; Y. Onuma; T. Homma

    1989-01-01

    Pressure sensors were fabricated using polycrystalline germanium films on a stainless steel diaphragm covered with an insulating layer. The polycrystalline germanium films, the sensing part of this device, were prepared by plasma-assisted chemical vapor deposition (plasma-CVD) at temperatures between 200C and 500C. The gauge factor of these films was about 20-60. The values were two times larger than those of

  10. Optical response of tin nitride thin films prepared by halide chemical vapor deposition under atmospheric pressure

    Microsoft Academic Search

    N. Takahashi; K. Terada; T. Takahashi; T. Nakamura; W. Inami; Y. Kawata

    2003-01-01

    Optical response of tin nitride (SnNx) films, which were deposited onto quartz substrates by means of atmospheric pressure, halide chemical vapor deposition (AP-HCVD),\\u000a were examined by pulsed irradiation of a YAG laser (532 nm). It was observed that the transmittance of a light of a He-Ne\\u000a laser (633 nm) through the SnNx film decreases after the film is irradiated with

  11. Heat Treatment with High-Pressure H2O Vapor of Pulsed Laser Crystallized Silicon Films

    Microsoft Academic Search

    Katsumi Asada; Keiji Sakamoto; Tadashi Watanabe; Toshiyuki Sameshima; Seiichiro Higashi

    2000-01-01

    Improvement of electrical properties for 7.4 1017 cm-3 phosphorus-doped pulsed laser crystallized silicon films of 50 nm thickness formed on quartz glass substrates was achieved by heat treatment with high-pressure H2O vapor. The electrical conductivity was increased from 1.3 10-5 S\\/cm (as-crystallized) to 2 S\\/cm by annealing at 270^\\\\circC@ for 3 h with 1.3 106 Pa H2O

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

    PubMed

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

    2005-11-15

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

  13. The relationship between gas hydrate saturation and P-wave velocity of pressure cores obtained in the Eastern Nankai Trough

    NASA Astrophysics Data System (ADS)

    Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Fujii, T.; Nagao, J.

    2014-12-01

    P-wave velocity is an important parameter to estimate gas hydrate saturation in sediments. In this study, the relationship between gas hydrate saturation and P-wave velocity have been analyzed using natural hydrate-bearing-sediments obtained in the Eastern Nankai Trough, Japan. The sediment samples were collected by the Hybrid Pressure Coring System developed by Japan Agency for Marine-Earth Science and Technology during June-July 2012, aboard the deep sea drilling vessel CHIKYU. P-wave velocity was measured on board by the Pressure Core Analysis and Transfer System developed by Geotek Ltd. The samples were maintained at a near in-situ pressure condition during coring and measurement. After the measurement, the samples were stored core storage chambers and transported to MHRC under pressure. The samples were manipulated and cut by the Pressure-core Non-destructive Analysis Tools or PNATs developed by MHRC. The cutting sections were determined on the basis of P-wave velocity and visual observations through an acrylic window equipped in the PNATs. The cut samples were depressurized to measure gas volume for saturation calculations. It was found that P-wave velocity correlates well with hydrate saturation and can be reproduced by the hydrate frame component model. Using pressure cores and pressure core analysis technology, nondestructive and near in-situ correlation between gas hydrate saturation and P-wave velocity can be obtained. This study was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

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

    SciTech Connect

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

    2015-01-01

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

  16. In-Reactor Oxidation of Zircaloy-4 Under Low Water Vapor Pressures

    SciTech Connect

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

    2015-01-01

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

  17. On the theory of pressure and temperature nonlinear waves in compressible fluid-saturated porous rocks

    NASA Astrophysics Data System (ADS)

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

    Thermo-poro-elastic equations describing fluid migration through fluid-saturated porous media at depth in the crust are analyzed theoretically following recent formulations of Rice and Cleary (1976), McTigue (1986) and Bonafede (1991). In this study these ideas are applied to a rather general model, namely to a deep hot and pressurized reservoir of fluid, which suddenly enters into contact with an overlaying large colder fluid-saturated layer. In a one-dimensional idealization this system can be described by two nonlinear differential heat-like equations on the matrix-fluid temperature and on the fluid overpressure over the hydrostatic value. The nonlinear couplings are due to Darcy thermal advection and to the mechanical work rate. Here we first sketch nonlinear solutions corresponding to Burgers' "solitary shock waves", which have recently been found valid for rocks with very low fluid diffusivity. Subsequently other nonlinear transient waves are discussed, such as "thermal" and "compensated" waves, which are found to exist for every value of the parameters present in the equations involved. One interesting aspect of these mechanisms is that the resulting time-scales are particularly small. Moreover, in order to figure out the system time-evolution and the role played by the fluid diffusivity/thermal diffusivity ratio, a mechanical similitude is proposed, which we treat both analytically and numerically. Although for realistic systems these solutions are somewhat idealized, they allow one to gain fundamental insight into fluid migration mechanisms in volcanic areas and in fault regions under strong frictional heating. As already discussed by McTigue, the theory is also of interest in studying areas of nuclear waste disposal. Furthermore such a theoretical study allows one to investigate the site at depth at which such nonlinear waves are generated.

  18. Dynamic hydrocarbon separation in high-temperature, high-pressure, liquid n-alkane water vapor systems by steam distillation

    E-print Network

    Vlierboom, Casper-Maarten

    1987-01-01

    DYNAMIC HYDROCARBON SEPARA1'ION IN HIGH-TEMPERATURE, HIGH-PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A Thesis by CASPER-MAARTEN VLIERBOOM Submitted to the Graduate College of Texas AGM University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1987 Major Subject: Petroleum Engineering DYNAMIC HYDROCARBON SEPARATION IN HIGH TEMPERATURE HIGH PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A...

  19. Rapid measurement of boiling points and vapor pressure of binary mixtures of short-chain triglycerides by TGA method

    Microsoft Academic Search

    J. W Goodrum; D. P Geller; S. A Lee

    1998-01-01

    Thermogravimetric analysis (TGA), has been used to rapidly obtain data on the temperature dependence of vapor pressure (760, down to 20mmHg) and the boiling points for simple binary mixtures of tributyrin (C4:0), tricaproin (C6:0) and\\/or tricaprylin (C8:0). Vapor-pressure measurements were taken for binary mixtures of the aforementioned compounds as a function of mole fraction. Additional measurements of methyl esters of

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

    Microsoft Academic Search

    Richard M. Edwards; Howard Haines

    1978-01-01

    SummaryThe 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

  1. Silicon dimethylamido complexes and ammonia as precursors for the atmospheric pressure chemical vapor deposition of silicon nitride thin films

    Microsoft Academic Search

    R. G. Gordon; D. M. Hoffman; U. Riaz

    2009-01-01

    Silicon nitride thin films are widely used in the microelectronics industry as diffusion barriers, passivation layers, and the active charge storage elements in metal-nitride-oxide semiconductor nonvolatile memory products. Silicon nitride films are normally prepared either by atmospheric pressure chemical vapor deposition (APCVD) using silane and ammonia as precursors or by low-pressure chemical vapor deposition (LPCVD) using dichlorosilane and ammonia. Herein,

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

    NASA Technical Reports Server (NTRS)

    Chauveau, Christian; Goekalp, Iskender

    1993-01-01

    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.

  3. The stability of Au-chloride complexes in water vapor at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Archibald, S. M.; Migdisov, A. A.; Williams-Jones, A. E.

    2001-12-01

    The solubility of gold in liquid-undersaturated HCl-bearing water vapor was investigated experimentally at temperatures of 300 to 360C and pressures up to 144 bars. Results of these experiments show that the solubility of gold in the vapor phase is significant and increases with increasing fHCl and fH 2O . This behavior of gold is attributed to formation of hydrated gold-chloride gas species, interpreted to have a gold-chlorine ratio of 1:1 and a hydration number varying from 5 at 300C to 3 at 360C. These complexes are proposed to have formed through the following reaction: Ausolid+ m HClgas+ n H2Ogas= AuClm( H2O) ngas+ m/2 H2gas which was determined to have log K values of -17.28 0.36 at 300C, -18.73 0.66 at 340C, and -18.74 0.43 at 360C. Gold solubility in the vapor was retrograde, i.e., it decreased with increasing temperature, possibly as a result of the inferred decrease in hydration number. Calculations based on our data indicate that at 300C and fO 2-pH conditions, encountered in high sulfidation epithermal systems, the vapor phase can transport up to 6.6 ppb gold, which would be sufficient to form an economic deposit (e.g., Nansatsu, Japan; 36 tonnes) in 30,000 yr.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

  5. Disjoining pressure and capillarity in the constrained vapor bubble heat transfer system.

    PubMed

    Chatterjee, Arya; Plawsky, Joel L; Wayner, Peter C

    2011-10-14

    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 of the Constrained Vapor Bubble (CVB) heat transfer system. In this non-isothermal "wickless heat pipe", liquid and vapor flow results from gradients in the intermolecular force field, which depend on the disjoining pressure, capillarity and temperature. A Kelvin-Clapeyron model allowed the use of the disjoining pressure to be expanded to describe non-isothermal heat, mass and momentum transport processes. The intermolecular force field described by the convenient disjoining pressure model is the boundary condition for "suction" and stability at the leading edge of the evaporating curved flow field. As demonstrated by the non-isothermal results, applications that depend on the characteristics of the evaporating meniscus are legion. PMID:21470588

  6. Synthetic fluid inclusions. V. Solubility relations in the system NaCl-KCl-H 2O under vapor-saturated conditions

    NASA Astrophysics Data System (ADS)

    Sterner, S. Michael; Hall, Donald L.; Bodnar, Robert J.

    1988-05-01

    Vapor-saturated solubility relationships in the system NaCl-KCl-H 2O have been determined by experimentally synthesizing fluid inclusions in quartz in the presence of known brine compositions and then measuring the dissolution temperatures of halite and/or sylvite daughter crystals within the inclusions using a microscope equipped with a heating stage. These data, along with other literature values have been used in a stepwise multiple regression routine to generate a series of equations describing vapor-saturated solubility relations within the halite, sylvite and hydrohalite stability fields. These equations, together with a recently published equation for the ice stability field ( HALLet al., 1987), have been used to construct the complete vapor-saturated solubility surface in the NaCl-KCl-H 2O ternary system. The diagram may be used in the interpretation of microthermometric data to determine the compositions of fluid inclusions approximated by the NaCl-KCl-H 2O system. For the NaCl-H 2O binary system, the ternary halite field expression reduces to Wt.% NaCl = 26.242 + 0.4928 ? + 1.42 ?2 - 0.223 ?3 + 0.04129 ?4 + 0.006295 ?5- 0.001967 ?6 + 0.0001112 ?7 ( ? = T C/100, where 0.1 ? T C ?801 C) which describes halite solubilities along the three-phase halite + liquid + vapor (H + L + V) curve. Similarly, sylvite solubilities along the three-phase sylvite + liquid + vapor (S + L + V) curve are described by the equation Wt.% KC1 = 21.886 + 20.28 ? - 9.603 ?2 + 4.078 ?3 - 0.8724 ?4 + 0.09174 ?5 - 0.003776 ?6 ( ?= T C/100, where -10.7 ? T C ? 770 C). Solubility data obtained from synthetic fluid inclusions are in good agreement with recently published data for the KC1-H 2O and NaCl-H 2O binary systems but are at variance with some earlier works.

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

    E-print Network

    Florida, University of

    grown by rapid thermal, low-pressure chemical vapor deposition (RT-LPCVD), using pure oxygen (0,) and 2 deposition (PECVD) ,* low-pres- sure chemical vapor deposition (LPCVD) ,' and irradiation and light assisted-pressure chemical vapor deposition (RT-LPCVD) . This technique allows for a very short dep- osition duration

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

    E-print Network

    Thierry Fouchet; Emmanuel Lellouch

    1999-11-15

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

  9. Effects of pressure and partial water saturation on gas permeability in tight sands: experimental results

    SciTech Connect

    Walls, J.D.; Nur, A.M.; Bourbie, T.

    1982-04-01

    Effective permeability to gas with various degrees of brine saturation has been measured in the laboratory for several very tight sandstones from the Spirit River formation of Alberta, Canada. Gas permeability as low as 20x10/sup -9/ darcy was measured successfully with a pulse-decay permeameter with nitrogen as the mobile fluid. Results show that gas permeability depends very strongly on the degree of saturation, with 40% saturation causing permeability to decrease an order of magnitude relative to the dry rock. Therefore, accurate knowledge of in-situ saturations is crucial before natural-gas production rates can be estimated in these formations. 9 refs.

  10. The vapour pressure of saturated aqueous solutions of D(+)-glucose, D(+)-galactose, and ?-lactose at temperatures from T=278 K to T=318 K

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    1998-01-01

    Vapour pressures of saturated aqueous solutions ofd(+)-glucose,d(+)-galactose, and ?-lactose were determined in the temperature range (278 to 323) K using an electronic hygrometer with an electrolyte sensor, and were compared with literature data. The water activities and osmotic coefficients at the saturation point were evaluated from the determined vapour pressures atT=298.15 K.

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

    SciTech Connect

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

    1984-01-01

    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.

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

    PubMed

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

    2012-01-28

    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 cm(2) V(-1) s(-1) at room temperature. PMID:25414547

  13. Deposition and properties of low-pressure chemical-vapor deposited polycrystalline silicon-germanium films

    Microsoft Academic Search

    Tsu-Jae King; Krishna C. Saraswat

    1994-01-01

    The deposition of undoped polycrystalline silicon-germanium (poly-Si(1-x)Ge(x)) alloy films onto SiO2 by the pyrolysis of SiH4 and GeH4 in a low-pressure chemical vapor deposition system is described. The deposited films are compatible with standard wet-cleaning baths, and their formation and patterning are very controllable processes; therefore, their application should not introduce significant process complexity into silicon-based technologies. Depending upon their

  14. High nitrogen composition GaAsN by atmospheric pressure metalorganic vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Toivonen, J.; Hakkarainen, T.; Sopanen, M.; Lipsanen, H.

    2000-12-01

    Highly luminescent GaAs 1- xN x alloys were successfully grown by atmospheric pressure metalorganic vapor-phase epitaxy (MOVPE). The nitrogen composition x of as high as 5.6% was obtained using trimethylgallium (TMGa), tertiarybutylarsine (TBAs) and dimethylhydrazine (DMHy) precursors. In-situ and post-growth rapid thermal annealing was performed to enhance the optical quality of the material. Intense low temperature photoluminescence was obtained from GaAsN down to 0.9 eV (1.38 ?m).

  15. Atmospheric-pressure chemical vapor deposition of fluorine-doped tin oxide thin films

    Microsoft Academic Search

    Seigi Suh; Zuhua Zhang; Wei-Kan Chu; David M. Hoffman

    1999-01-01

    Fluorine-doped tin oxide films were deposited on silicon, glass and quartz substrates at 370490C by atmospheric-pressure chemical vapor deposition from (CH3(CH2)3)2Sn(O2CCF3)2 and oxygen. Backscattering spectra indicate the films are stoichiometric with O\\/Sn ratios of 1.92.0. Nuclear reaction analysis (NRA) for fluorine gives F\\/Sn ratios of 0.0050.015 with the amount of fluorine in the films increasing with increasing deposition temperature. The

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  18. Grain boundary potential barrier inhomogeneities in low-pressure chemical vapor deposited polycrystalline silicon thin-film transistors

    Microsoft Academic Search

    C. A. Dimitriadis

    1997-01-01

    Arrhenius plots of conductivity in low-pressure chemical vapor deposited (LPCVD) polycrystalline silicon thin-film transistors (TFTs) are curved when the films are deposited at pressures below 40 mtorr. These deviations from straight lines are explained by spatial potential fluctuations over the grain boundary plane described by a Gaussian type distribution. When grain boundary inhomogeneities are not taken into account, the determined

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

    SciTech Connect

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

    1993-12-31

    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.

  20. Two-phase heat transfer and pressure drop of LNG during saturated flow boiling in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-12-01

    Two-phase heat transfer and pressure drop of LNG (liquefied natural gas) have been measured in a horizontal smooth tube with an inner diameter of 8 mm. The experiments were conducted at inlet pressures from 0.3 to 0.7 MPa with a heat flux of 8-36 kW m-2, and mass flux of 49.2-201.8 kg m-2 s-1. The effect of vapor quality, inlet pressure, heat flux and mass flux on the heat transfer characteristic are discussed. The comparisons of the experimental data with the predicted value by existing correlations are analyzed. Zou et al. (2010) correlation shows the best accuracy with 24.1% RMS deviation among them. Moreover four frictional pressure drop methods are also chosen to compare with the experimental database.

  1. Contribution of water vapor pressure to pressurization of plutonium dioxide storage containers

    Microsoft Academic Search

    D. Kirk Veirs; John S. Morris; Dane R. Spearing

    2000-01-01

    Pressurization of long-term storage containers filled with materials meeting the US DOE storage standard is of concern.1,2 For example, temperatures within storage containers packaged according to the standard and contained in 9975 shipping packages that are stored in full view of the sun can reach internal temperatures of 250 C.3 Twenty five grams of water (0.5 wt.%) at 250 C

  2. Density, vapor pressure, solubility, and viscosity for water + lithium bromide + lithium nitrate + 1,3-propanediol

    SciTech Connect

    Park, Y.; Kim, J.S.; Lee, H. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemical Engineering] [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemical Engineering; Yu, S.I. [Rinnai Korea, Taejon (Korea, Republic of). R and D Lab.] [Rinnai Korea, Taejon (Korea, Republic of). R and D Lab.

    1997-01-01

    Four physical properties (solubility, vapor pressure, density, and viscosity) of water + lithium bromide + lithium nitrate + 1,3-propanediol (LiBr/LiNO{sub 3} mole ratio = 4, (LiBr + LiNO{sub 3})/HO(CH{sub 2}){sub 3}OH mass ratio = 3.5) were measured. The system, a possible working fluid for an absorption heat pump, mainly consists of absorbent (LiBr + LiNO{sub 3} + HO(CH{sub 2}){sub 3}OH) and refrigerant (H{sub 2}O). Solubilities were measured by the visual polythermal method in the temperature range (285.55 to 346.65) K and in the absorbent concentration range (68.0 to 75.0) mass %. Vapor pressures were measured by the boiling point method in the temperature range (325.35 to 395.15) K and in the absorbent concentration range (46.0 to 69.6) mass %. Densities and viscosities were measured by a set of hydrometers and viscometers, respectively, in the temperature range (283.15 to 343.15) K and in the absorbent concentration range (24.3 to 70.3) mass %. The measured values were correlated.

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

    USGS Publications Warehouse

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

    2007-01-01

    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.

  4. Estimating Water Saturation at The Geysers Based on Historical Pressure and Temperature Production

    E-print Network

    Stanford University

    Engineering, Stanford University Stanford Geothermal Program Interdisciplinary Research in Engineering of the wells demonstrate "dry-out" due to the formation of superheated steam. The in-situ water saturation

  5. VAPORIZATION AND OXIDATION OF LIQUID FUEL DROPLETS AT HIGH TEMPERATURE AND HIGH PRESSURE: APPLICATION TO N-ALKANES AND VEGETABLE OIL METHYL ESTERS

    Microsoft Academic Search

    CLINE MORIN; CHRISTIAN CHAUVEAU; PHILIPPE DAGAUT; ISKENDER GKALP; MICHEL CATHONNET

    2004-01-01

    Vaporization and oxidation of liquid fuel droplets are basic mechanisms in spray combustion for various industrial applications. In this work, coupled effects of temperature and pressure on n-alkane droplet vaporization are investigated in experiments conducted in a high-pressure and high-temperature gasification facility equipped with the fiber-suspended droplet technique. The influence of temperature and pressure on n-heptane and n-decane vaporization rates

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    SciTech Connect

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

    1987-06-04

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

  8. Oxy-Mat Mattress System Development Utilizing Simultaneous Measurement of Interface Pressure and Deep Tissue Oxygen Saturation.

    PubMed

    Butler, Glenn J; Kenyon, David J; Gorenstein, Scott; Davenport, Thomas; Golembe, Edward; Lee, Bok; Vieweq, Jacques

    2015-05-01

    The development and management of pressure ulcers (PUs) among hospital and nursing home patients is one of the greatest preventable challenges to healthcare worldwide. For over 50 years, pressure mapping and subjective comfort has been the primary indicators for mattress selection. Our research demonstrates that mattress/patient interface pressure and relative blood/oxygen perfusion do not inversely correlate and pressure is not a meaningful, real-time indicator of tissue ischemia and risk of pressure ulcer development. Developed in our research is a real-time sensor system to simultaneously measure and record these parameters over the anatomical sites at risk for PUs. Measurements focused on the heel, sacrum, trochanter, ischium, scapula and occipital. A modified pressure mapping system is used for interface pressure measurements and integrated with multiple near-infrared sensors to measure specific deep tissue hemoglobin saturated oxygen or rSO2. Testing and mattress design development was done during the period of 2008 to present. Over 200 human tests of commercially available mattresses were conducted in supine, 30 degree, and 70 degree positions, ranging in times of up to four hours. During this time period, we utilized 20 test subjects-eight female and 12 male-with ages ranging from 18 to 65 years. The result of this proprietary off-loading device evaluation and design system shows that the new Oxy-Mat (Off-Loading Technologies, Tarrytown, NY) Non-Powered Mattress System consistently provides optimized tissue perfusion as measured by natural deep tissue oxygen saturation levels. In extensive laboratory and clinical evaluations, the Oxy-Mat was shown to be functionally superior to CMS Group 2 powered mattresses. Another outcome of our research was that a powered mattress system may not be appropriate for most sensate and semi-ambulatory patients. Further research is underway. PMID:26054994

  9. Non-canonical mass laws in equilibrium isotopic fractionations: Evidence from the vapor pressure isotope effect of SF6

    NASA Astrophysics Data System (ADS)

    Eiler, John; Cartigny, Pierre; Hofmann, Amy E.; Piasecki, Alison

    2013-04-01

    We report experimental observations of the vapor pressure isotope effect, including 33S/32S and 34S/32S ratios, for SF6 ice between 137 and 173 K. The temporal evolution of observed fractionations, mass-balance of reactants and products, and reversal of the fractionation at one temperature (155 K) are consistent with a subset of our experiments having reached or closely approached thermodynamic equilibrium. That equilibrium involves a reversed vapor pressure isotope effect; i.e., vapor is between 2 and 3 higher in 34S/32S than co-existing ice, with the difference increasing with decreasing temperature. At the explored temperatures, the apparent equilibrium fractionation of 33S/32S ratios is 0.551 0.010 times that for 34S/32S ratioshigher than the canonical ratio expected for mass dependent thermodynamic fractionations (0.515). Two experiments examining exchange between adsorbed and vapor SF6 suggest the sorbate-vapor fractionation at 180-188 K is similar to that for ice-vapor at 150 K. In contrast, the liquid-vapor fractionation at 228-300 K is negligibly small (0.1 for 34S/32S; the mass law is ill defined due to the low amplitude of fractionation). We hypothesize that the observed vapor pressure isotope for SF6 ice and sorbate is controlled by commonly understood effects of isotopic substitution on vibrational energies of molecules, but leads to both an exotic mass law and reversed fractionation due to the competition between isotope effects on intramolecular vibrations, which promote heavy isotope enrichment in vapor, and isotope effects on intermolecular (lattice) vibrations, which promote heavy isotope enrichment in ice. This explanation implies that a variety of naturally important compounds having diverse modes of vibration (i.e., varying greatly in frequency and particularly, reduced mass) could potentially exhibit similarly non-canonical mass laws for S and O isotope fractionations. We examined this hypothesis using a density function model of SF6 vapor and lattice dynamic model of SF6(ice). These models support the direction of the measured vapor pressure isotope effect, but do not quantitatively agree with the magnitude of the fractionation and poorly match the phonon spectrum of SF6 ice. A strict test of our hypothesis must await a more sophisticated model of the isotopic dependence of the phonon spectrum of SF6 ice.

  10. Epitaxial growth of 3C-SiC on Si by low-pressure chemical vapor deposition

    SciTech Connect

    Fujiwara, Y.; Sakuma, E.; Misawa, S.; Endo, K.; Yoshida, S.

    1986-08-01

    3C-SiC was grown on Si(100) substrates by low-pressure chemical vapor deposition using a C3H8-SiH4-H2 reaction gas system in the pressure range between 1.5 and 100 Torr. The dependences of the crystal structures, growth rates, thickness distributions, and electrical properties of the SiC layers on growth conditions were investigated. At low pressure, it was found that the thickness uniformity was improved, especially at 1.5 Torr compared to atmospheric pressure. The epitaxially grown 3C-SiC layers at 100 Torr have smooth surfaces and high crystalline quality and showed almost the same electrical properties as those of the epilayers by atmospheric pressure chemical vapor deposition. 14 references.

  11. Abstract--Doping reaction of diborane B2H6 on Si(100) substrates in an atmospheric pressure chemical vapor deposition

    E-print Network

    Technische Universiteit Delft

    chemical vapor deposition (APCVD) system has been studied in terms of dopant profile and junction depth in an atmospheric pressure chemical vapor deposition (APCVD) system at 700 C, effective B-doping of the silicon vapor deposition (CVD), junction depth, secondary ion mass spectrometry (SIMS), sheet resistance

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

    USGS Publications Warehouse

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

    1993-01-01

    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.

  13. Calculation of the vapor-saturated liquidus for the NaCl-CO 2-H 2O system

    NASA Astrophysics Data System (ADS)

    Barton, Paul B.; Chou, I.-Ming

    1993-06-01

    The polybaric liquidus surface for the H 2O-rich corner of the NaCl-CO 2-H 2O ternary is calculated, relying heavily on (1) a Henry's law equation for CO 2 in brines (modified from Drummond, 1981), (2) the assumption that the contributions of dissolved NaCl and CO 2 in lowering the activity of H 2O are additive, and (3) data on the CO 2 clathrate solid solution (nominally CO 2 7.3H 2O, but ranging from 5.75 to 8 or 9 H 2O) from Bozzo et al. (1975). The variation with composition of the activity of CO 27.3H 2O, or any other composition within the clathrate field, is small, thereby simplifying the calculations appreciably. Ternary invariant points are (1) ternary eutectic at -21.5C, with ice + clathrate + hydrohalite NaCl-H 2O + brine mNaCl = 5.15, mco2 = 0.22 + vapor Ptotal ? Pco2 = 5.7 atm; (2) peritectic at -9.6C, with clathrate + hydrohalite + liquid CO 2 + brine mNaCl = 5.18, mco2 = 0.55 + vapor ( Ptotal ? Pco2 = 26.47 atm ); and (3) peritectic slightly below +0.1 C, with halite + hydrohalite + liquid CO 2 + brine ( mNaCl ? 5.5, m co 2 ? 0.64 ) + vapor ( Ptotal ? Pco2 ? 34 atm). CO 2 isobars have been contoured on the ternary liquidus and also on the 25C 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.

  14. Frictional behavior of diamondlike carbon films in vacuum and under varying water vapor pressure.

    SciTech Connect

    Andersson, J.; Erck, R. A.; Erdemir, A.

    2002-03-25

    In this study, we investigated the frictional behavior of both hydrogenated and hydrogen-free diamondlike carbon (DLC) films in high vacuum (10{sup -6} Pa) at room temperature. Water was also introduced into the vacuum chamber to elucidate its effects on DLC film tribology. The hydrogen-free DLC (also referred to as tetrahedral amorphous carbon, or ta-C) was produced by an arc-PVD process, and the highly hydrogenated DLC was produced by plasma-enhanced chemical-vapor deposition. Tribological measurements of these films were made with a pin-on-disc machine with coated steel balls and coated steel discs in matched pairs under a 1 N load. The ball/disk pairs were rotated at sliding speeds in the range of 0.025-0.075 m/s. In vacuum, the steady-state friction coefficient of ta-C was of the order of 0.6 and the wear was severe, whereas for the highly hydrogenated film, friction was below 0.01, and in an optical microscope no wear could be detected. Adding water vapor to the sliding ta-C system in a vacuum chamber caused friction to decrease monotonically from 0.6 to {approx}0.05. In contrast, adding water vapor to the sliding DLC system caused the friction to increase linearly with pressure from 0.01 to 0.07. The results illustrate the importance of taking into account environmental conditions, especially the presence of water, when DLC films are being considered for a given application.

  15. PARAMETER ESTIMATION OF TWO-FLUID CAPILLARY PRESSURE-SATURATION AND PERMEABILITY FUNCTIONS

    EPA Science Inventory

    Capillary pressure and permeability functions are crucial to the quantitative description of subsurface flow and transport. Earlier work has demonstrated the feasibility of using the inverse parameter estimation approach in determining these functions if both capillary pressure ...

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

    PubMed

    Kaya, Murat; Volkan, Mrvet

    2011-03-15

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

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

    SciTech Connect

    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

    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.

  18. Measurement of soil saturated hydraulic conductivity: The method of constant pressure tubes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field method to measure the saturated soil hydraulic conductivity is presented that does not require expensive equipment and preserves natural water flow pathways that may be bloked during soil core sampling for laboratory measurements. Vegetation must be removed from the plot prior the measurement...

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

    SciTech Connect

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

    2007-10-15

    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)

  20. Effect of Vapor Pressure Scheme on Multiday Evolution of SOA in an Explicit Model

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Madronich, S.; Aumont, B.; Camredon, M.; Emmons, L. K.; Tyndall, G. S.; Valorso, R.

    2011-12-01

    Recent modeling of the evolution of Secondary Organic Aerosol (SOA) has led to the critically important prediction that SOA mass continues to increase for several days after emission of primary pollutants. This growth of organic aerosol in dispersing plumes originating from urban point sources has direct implications for regional aerosol radiative forcing. We investigate the robustness of predicted SOA mass growth downwind of Mexico City in the model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), by assessing its sensitivity to the choice of vapor pressure prediction scheme. We also explore the implications for multi-day SOA mass growth of glassification / solidification of SOA constituents during aging. Finally we use output from the MOZART-4 chemical transport model to evaluate our results in the regional and global context.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  2. Net vapor generation point in boiling flow of trichlorotrifluoroethane at high pressures

    NASA Technical Reports Server (NTRS)

    Dougall, R. S.; Lippert, T. E.

    1973-01-01

    The conditions at which the void in subcooled boiling starts to undergo a rapid increase were studied experimentally. The experiments were performed in a 12.7 x 9.5 mm rectangular channel. Heating was from a 3.2 mm wide strip embedded in one wall. The pressure ranged from 9.45 to 20.7 bar, mass velocity from 600 to 7000 kg/sq m sec, and subcooling from 16 to 67 C. Photographs were used to determine when detached bubbles first appeared in the bulk flow. Measurements of bubble layer thickness along the wall were also made. Results showed that the point of net vapor generation is close to the occurrence of fully-developed boiling.

  3. Defect Characterization in Ge/(001)Si Epitaxial Films Grown by Reduced-Pressure Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Bharathan, Jayesh; Narayan, Jagdish; Rozgonyi, George; Bulman, Gary E.

    2013-10-01

    We studied the microstructural characteristics and electrical properties of epitaxial Ge films grown on Si(001) substrates by x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The films were grown using a two-step technique by reduced-pressure chemical vapor deposition, where the first step promotes two-dimensional growth at a lower substrate temperature. We observed a decrease in defect density with increasing film thickness. Ge films with thickness of 3.5 ?m exhibited threading dislocation densities of 5 106 cm-2, which yielded devices with dark current density of 5 mA cm-2 (1 V reverse bias). We also noted the presence of stacking faults in the form of lines in the films and establish that this is an important defect for Ge films grown by this deposition technique.

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

    NASA Technical Reports Server (NTRS)

    Zwillenberg, M. L.

    1975-01-01

    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).

  5. Epitaxial Growth of Zinc Oxide Whiskers by Chemical-Vapor Deposition under Atmospheric Pressure

    Microsoft Academic Search

    Minoru Satoh; Norio Tanaka; Yoshikazu Ueda; Shigeo Saitoh; Hidetoshi Saitoh

    1999-01-01

    ZnO whiskers were epitaxially grown by a chemical-vapor deposition technique employed at atmospheric pressure. Highly oriented ZnO whiskers grew at a substrate temperature of 550C on (0001)alpha-Al2O3 substrates with a growth rate of 3.7 nm\\/s. X-ray diffractometry revealed that the epitaxial relationship between the whiskers and the substrate was determined as ZnO[\\\\bar{1}010](0001)\\/\\/Al2O3[\\\\bar{1}2\\\\bar{1}0](0001) or ZnO[\\\\bar{1}2\\\\bar{1}0](0001)\\/\\/Al2O3[\\\\bar{1}010](0001). In addition, the full-width at half

  6. Effect of cluster\\/particle deposition on atmospheric pressure chemical vapor deposition of SiO2 from four gaseous organic Si-containing precursors and ozone

    Microsoft Academic Search

    Toshiyuki Fujimoto; Kikuo Okuyama; Satoshi Yamada; Motoaki Adachi

    1999-01-01

    In order to analyze the particle generation and its effect on the SiO2 thin film in an atmospheric pressure chemical vapor deposition (APCVD) process using four organic silicon vapors and ozone gas, gas-phase particle generation, growth, transportation and vapor-cluster\\/particle codeposition processes were studied experimentally and theoretically using a flow-type vertical tube reactor. Decomposition reaction rates of four organic silicon vapors

  7. Comparing magnetotransport and surface magnetic properties of half-metallic CrO2 films grown by low pressure and atmospheric pressure chemical vapor deposition

    Microsoft Academic Search

    M. Pathak; X. Zhong; J. Wang; X. Zhang; T. M. Klein; P. Leclair; A. Gupta

    2010-01-01

    CrO2 films prepared by low pressure chemical vapor deposition (LPCVD) using Cr(CO)6 precursor have been investigated and compared with epitaxial half metallic CrO2 films prepared at atmospheric pressure (APCVD) using CrO3 precursor for their magnetotransport and surface magnetic properties. LPCVD films showed higher resistivity than APCVD epitaxial (100) CrO2 films prepared on (100) TiO2 substrates. Magnetoresistance of LPCVD films is

  8. Continuous mixed venous oxygen saturation, not mean blood pressure, is associated with early bupivacaine cardiotoxicity in dogs

    Microsoft Academic Search

    Jin-Tae Kim; Ka-Young Rhee; Jae-Hyon Bahk; Sang-Hwan Do; Young-Jin Lim; Hong Ko; Kook-Hyun Lee

    2003-01-01

    PurposeTo investigate changes of continuous mixed venous oxygen saturation (cSvO2) and mean arterial blood pressure (MBP) in dogs with bupivacaine-induced cardiac depression.\\u000a \\u000a \\u000a \\u000a MethodsBupivacaine was infused into pentobarbital-anesthetized mongrel dogs (n = 8) at a rate of 0.5 mgkg?1min?1 until the MBP was 40 mmHg or less (end of bupivacaine infusion; BIE). The infusion time was divided into the early period,

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

    Microsoft Academic Search

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

    1992-01-01

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

  10. Photosynthetic photon flux density, carbon dioxide concentration, and vapor pressure deficit effects on photosynthesis in cacao seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cacao (Theobroma cacao) is a shade plant, native to the under-story of the evergreen rain forest of the Amazon basin and adapted to low levels of photosynthetic photon flux density (PPFD). The influence of PPFD, leaf to air water vapor pressure deficit (VPD) and external carbon dioxide concentration...

  11. Nanocluster Formation within the Vapor Plume, Produced by Nanosecond-Laser Ablation: Effect of Initial Density and Pressure Distributions

    Microsoft Academic Search

    Masahiro Kuwata; Boris Luk'yanchuk; Takashi Yabe

    2001-01-01

    The condensation of vapor in the expanding plume produced by ns-laser ablation is discussed within the framework of the Zeldovich and Raizer theory of condensation. The spherical plume expansion is described by a numerical solution of the hydrodynamic equations by the cubic interpolated pseudo-particle (CIP) method. This permits us to analyze the role of initial distributions of density and pressure

  12. Nanocluster formation within the vapor plume produced by nanosecond laser ablation: effect of the initial density and pressure distributions

    Microsoft Academic Search

    Y. Kuwata; Boris S. Luk'yanchuk; Takashi Yabe

    2000-01-01

    The condensation of vapor within the expanding plume produced by ns-laser ablation is discussed in the framework of Zeldovich and Raizer theory of condensation. The spherical plume expansion is described by numerical solution of hydrodynamic equations by CIP method. This permits to analyze the role of initial distributions in density and pressure onto the size distribution function for nanoclusters. With

  13. Nonlinear continuous time modeling of a high pressure mercury vapor discharge lamp using feed forward back-propagation neural networks

    Microsoft Academic Search

    A. Zouidi; M. Stambouli; A. Chaari; F. Fnaiech

    2004-01-01

    A continuous time nonlinear model is proposed in this paper for modeling a high pressure mercury vapor discharge lamp. Parametric continuous models of discharge lamps exist in the literature. However, the development of new nonlinear models of this discharge lamp is an appealing area. Hence, this paper focuses on the performance study of a non linear model namely Herrick's conductance

  14. The effect of carrier gas pressure on vapor phase nucleation experiments using a thermal diffusion cloud chamber

    Microsoft Academic Search

    D. Kane; S. P. Fisenko; M. Rusyniak; M. S. El-Shall

    1999-01-01

    Recent measurements of critical supersaturations for the vapor phase homogeneous nucleation of several substances using a diffusion cloud chamber technique exhibit a dependence on the pressure of the carrier gas used in the experiments. A model of droplet growth and motion in a diffusion cloud chamber, combined with the density and temperature profiles of the chamber is presented to explain

  15. Impact of seed layer on material quality of epitaxial germanium on silicon deposited by low pressure chemical vapor deposition

    Microsoft Academic Search

    Oluwamuyiwa O. Olubuyide; David T. Danielson; Lionel C. Kimerling; Judy L. Hoyt

    2006-01-01

    The impact of the growth conditions of the germanium seed layer on the material quality of epitaxial germanium grown on (100) silicon by Low Pressure Chemical Vapor Deposition is studied. In order to obtain a smooth surface morphology, a thin Ge seed layer is grown at low temperature, followed by a thick Ge cap layer at high temperature. An optimal

  16. Abscisic Acid Synthesis in Acer rubrum L. Leaves A Vapor-pressure-defi cit-mediated Response

    Microsoft Academic Search

    W. L. Bauerle; T. H. Whitlow; F. M. Vermeylen

    Quantitative differences in leaf abscisic acid (ABA) among Acer rubrum L. (red maple) ecotypes were in- vestigated. This study tested the hypothesis that seedlings from wet and dry maternal sites display distinctly different capacities to synthesize ABA in response to atmospheric vapor pressure defi cits. The increased levels of ABA in leaf tissue in the red maple ecotypes were associated

  17. First experimental determination of the absolute gas-phase rate coefficient for the reaction of OH with 4-hydroxy-2-butanone (4H2B) at 294 K by vapor pressure measurements of 4H2B.

    PubMed

    El Dib, Gisle; Sleiman, Chantal; Canosa, Andr; Travers, Daniel; Courbe, Jonathan; Sawaya, Terufat; Mokbel, Ilham; Chakir, Abdelkhaleq

    2013-01-10

    The reaction of the OH radicals with 4-hydroxy-2-butanone was investigated in the gas phase using an absolute rate method at room temperature and over the pressure range 10-330 Torr in He and air as diluent gases. The rate coefficients were measured using pulsed laser photolysis (PLP) of H(2)O(2) to produce OH and laser induced fluorescence (LIF) to measure the OH temporal profile. An average value of (4.8 1.2) 10(-12) cm(3) molecule(-1) s(-1) was obtained. The OH quantum yield following the 266 nm pulsed laser photolysis of 4-hydroxy-2-butanone was measured for the first time and found to be about 0.3%. The investigated kinetic study required accurate measurements of the vapor pressure of 4-hydroxy-2-butanone, which was measured using a static apparatus. The vapor pressure was found to range from 0.056 to 7.11 Torr between 254 and 323 K. This work provides the first absolute rate coefficients for the reaction of 4-hydroxy-2-butanone with OH and the first experimental saturated vapor pressures of the studied compound below 311 K. The obtained results are compared to those of the literature and the effects of the experimental conditions on the reactivity are examined. The calculated tropospheric lifetime obtained in this work suggests that once emitted into the atmosphere, 4H2B may contribute to the photochemical pollution in a local or regional scale. PMID:23210721

  18. A method for measuring vapor pressures of low-volatility organic aerosol compounds using a thermal desorption particle beam mass spectrometer.

    PubMed

    Chattopadhyay, S; Tobias, H J; Ziemann, P J

    2001-08-15

    A temperature-programmed thermal desorption method for measuring vapor pressures of low-volatility organic aerosol compounds has been developed. The technique employs a thermal desorption particle beam mass spectrometer we have recently developed for real-time composition analysis of organic aerosols. Particles are size selected using a differential mobility analyzer, sampled into a high-vacuum chamber as an aerodynamically focused beam, collected by impaction on a cryogenically cooled surface, slowly vaporized by resistive heating, and analyzed in a quadrupole mass spectrometer. A simple evaporation model developed from the kinetic theory of gases is used to calculate compound vapor pressures over the temperature range of evaporation. The data are fit to a Clausius-Clapeyron equation to obtain a relationship between vapor pressure and temperature and to determine the heat of vaporization. The technique has been evaluated using C13-C18 monocarboxylic and C6-C8 dicarboxylic acids, which have vapor pressures at 25 degrees C of approximately 10(-4) - 10(-6) Pa, but less volatile compounds can also be analyzed. The method is relatively simple and rapid and yields vapor pressures and heats of vaporization that are in good agreement with literature values. The technique will be used to generate a new database of vapor pressures for low-volatility atmospheric organic compounds. PMID:11534699

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

    Microsoft Academic Search

    H. R. Kroeger; J. W. Stephenson

    1957-01-01

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

  20. Influence of Pore-Fluid Pressure on Elastic Wave Velocity and Electrical Conductivity in Water-Saturated Rocks

    NASA Astrophysics Data System (ADS)

    Higuchi, A.; Watanabe, T.

    2013-12-01

    Pore-fluid pressure in seismogenic zones can play a key role in the occurrence of earthquakes (e.g., Sibson, 2009). Its evaluation via geophysical observations can lead to a good understanding of seismic activities. The evaluation requires a thorough understanding of the influence of the pore-fluid pressure on geophysical observables like seismic velocity and electrical conductivity. We have studied the influence of pore-fluid pressure on elastic wave velocity and electrical conductivity in water-saturated rocks. Fine grained (100-500?m) biotite granite (Aji, Kagawa pref., Japan) was used as rock samples. The density is 2.658-2.668 g/cm3, and the porosity 0.68-0.87%. The sample is composed of 52.8% plagioclase, 36.0% Quartz, 3.0% K-feldspar, 8.2% biotite. SEM images show that a lot of grain boundaries are open. Few intracrystalline cracks were observed. Following the method proposed by David and Zimmerman (2012), the distribution function of crack aspect ratio was evaluated from the pressure dependence of compressional and shear wave velocities in a dry sample. Cylindrical sample has dimensions of 25 mm in diameter and 30 mm in length, and saturated with 0.01 mol/l KCl aqueous solution. Compressional and shear wave velocities were measured with the pulse transmission technique (PZT transducers, f=2 MHz), and electrical conductivity the two-electrode method (Ag-AgCl electrodes, f=1 Hz-100 kHz). Simultaneous measurements of velocities and conductivity were made using a 200 MPa hydrostatic pressure vessel, in which confining and pore-fluid pressures can be separately controlled. The pore-fluid is electrically insulated from the metal work of the pressure vessel by using a newly designed plastic device (Watanabe and Higuchi, 2013). The confining pressure was progressively increased up to 25 MPa, while the pore-fluid pressure was kept at 0.1 MPa. It took five days or longer for the electrical conductivity to become stationary after increasing the confining pressure. Elastic wave velocities and electrical conductivity showed reproducibly contrasting changes for a small increase in the confining pressure. The elastic wave velocities increased only by 5% as the confining pressure increased from 0.1 MPa to 25 MPa, while the electrical conductivity decreased by an order of magnitude. Based on the SEM examinations, open grain boundaries work as cracks. The changes in elastic wave velocities and electrical conductivity must be caused by the closure of open grain boundaries. Most (80%) of the decrease in electrical conductivity occurred below the confining pressure of 5 MPa. As the confining pressure increased from 0.1 MPa to 5 MPa, cracks with the aspect ratio smaller than 7.510-5 were closed. The decrease in porosity was only 0.0005%. Such a small change in porosity caused a large change in electrical conductivity. The connectivity of fluid was maintained at the confining pressure of 25 MPa by cracks with the aspect ratio larger than 3.710-4. Simultaneous measurements have provided us a lot of information on the microstructure of fluid-bearing rocks.

  1. 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

    Findley, Gary L.

    Ex 8.1(a) At 90C, the vapor pressure of methylbenzene is 400 Torr and that of 1,2- dimethylbenzene? What is the composition of the vapor produced? Ex 8.2(a) The vapor pressure of pure liquid A at 300 K mixtures. Consider the equilibrium composition of a mixture in which the mole fraction of A in the vapor

  2. High pressure chemical vapor deposition: A novel approach for the growth of indium nitride

    NASA Astrophysics Data System (ADS)

    Woods, Vincent Timothy

    The development of next generation devices for high speed switching, high efficiency energy conversion, spintronic devices require the development of advanced material systems. While conventional group IV, group II-VI and group III-V based materials systems have served as a base material in many modern device structures, they posses fundamental materials properties that limit their suitability in next generation device structures. The group III-N material system is very promising for the development of advanced device structures. GaN is currently widely used in high efficiency lighting applications. However, the development of this material system has been limited to material systems with limited indium. The growth of high indium concentration materials such as InN and GaxIn1-xN has proven difficulty due to the high thermal decomposition pressure of InN. In response to this difficulty, a high pressure chemical vapor deposition reactor system has been developed for the growth of InN which enables elevated processing temperatures as compared to conventional low-pressure growth techniques. The design criteria and implementation of this unique design is presented here. In addition, the results of in-situ real time optical characterization capabilities of this reactor system are presented as applied to thermal characterization, flow dynamics, gas phase kinetics and surface reactions. Ex-situ InN thin films grown on sapphire substrates and GaN epilayers have been analyzed by x-ray diffraction, transmission spectroscopy and raman spectroscopy. These results indicated single crystal indium nitride films with an optical absorption edge which varies between 0.7 and 1.9 eV as a function of precursor flow stoichiometry.

  3. Influence of saturated fat and linolenic acid on the association between intake of dairy products and blood pressure.

    PubMed

    Djouss, Luc; Pankow, James S; Hunt, Steven C; Heiss, Gerardo; Province, Michael A; Kabagambe, Edmond K; Ellison, R Curtis

    2006-08-01

    Data on the association between dairy consumption and blood pressure have been inconsistent. We sought to examine the relation between dairy consumption and prevalent hypertension (HTN) among 4797 participants of the National Heart, Lung, and Blood Institute Family Heart Study. We used generalized estimating equations to estimate prevalence odds ratios of HTN across categories of dairy consumption. From the lowest to the highest sex-, age-, and energy-adjusted quartile of dairy consumption, there was an inverse association between dairy intake and prevalent HTN: odds ratios (95% CIs) were 1.0 (reference), 0.82 (0.64 to 1.05), 0.68 (0.53 to 0.89), and 0.62 (0.45 to 0.84), respectively, in a model adjusting for age, sex, energy intake, field center, body mass index, dietary linolenic acid, saturated and monounsaturated fat, sodium intake, potassium, caffeine, fiber, and fruits and vegetables (P for trend = 0.002). This association was independent of calcium intake and was mainly observed among subjects consuming fewer calories from saturated fat (P for interaction = 0.014). Dairy consumption was inversely associated with systolic (P for trend = 0.003) but not diastolic (P for trend = 0.09) blood pressure. Although subjects consuming > or = 2 servings per day of dairy products and higher total linolenic acid had the lowest prevalence odds of HTN, there was no evidence for interaction between linolenic acid and dairy consumption on HTN (P for interaction = 0.65). In conclusion, our data indicate an inverse association between dairy consumption and prevalent HTN that was independent of dietary calcium, mainly among individuals consuming less saturated fat. This suggests that consumption of low-fat dairy products might be more beneficial for preventing HTN. PMID:16801477

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

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1979-01-01

    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.

  5. Vapour pressure and enthalpy of vaporization of di-iso-propyl and di-tert-butyl esters of dicarboxylic acids

    Microsoft Academic Search

    Svetlana V. Portnova; Eugen L. Krasnykh; Sergey P. Verevkin

    2011-01-01

    Molar enthalpies of vaporization of the branched aliphatic alkyl esters of dicarboxylic acids R-CO2-(CH2)n-CO2-R with n=(04) with R=iso-C3H7, tert-C4H9 were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. These experimental results were checked for internal consistency and compared with the data available from the literature. A linear correlation of enthalpies of vaporization ?lgHm (298.15K)

  6. Comprehensive characterization of temperature- and pressure-induced bilayer phase transitions for saturated phosphatidylcholines containing longer chain homologs.

    PubMed

    Goto, Masaki; Endo, Takuya; Yano, Takahiro; Tamai, Nobutake; Kohlbrecher, Joachim; Matsuki, Hitoshi

    2015-04-01

    Complete elucidation of the phase behavior of phospholipid bilayers requires information on the subtransition from the lamellar crystal (Lc) phase to the gel phase. However, for bilayers of saturated diacylphosphatidylcholines (CnPCs), especially longer chain homologs, equilibration in the Lc phase is known to be very slow. In this study, bilayer phase transitions of three CnPCs with longer acyl chains, C19PC, C20PC and C21PC, were observed by differential scanning calorimetry under atmospheric pressure and by light-transmittance measurements under high pressure. Using lipid samples treated by thermal annealing enabled the observation of the sub-, pre- and main transitions of the C19PC and C20PC bilayers under atmospheric pressure. Only the pre- and main transitions could be observed for the C21PC bilayer due to very slow kinetics of the Lc phase formation for lipids with long acyl chains. The temperature and pressure phase diagrams constructed and phase-transitions quantities (enthalpy, entropy and volume changes) evaluated for these bilayers were compared with one another and with those of bilayers of the CnPC homologs examined in previous studies. These results allowed us (1) to clarify the temperature- and pressure-dependent phase sequence and phase stability of the CnPC (n=12-22) bilayers as a function of the hydrophobicity of the molecules, (2) to prove the presence of a shorter and a longer limit (n=13 and 21) in the acyl chain length for the pressure-induced bilayer interdigitation and (3) to reveal the chain-length dependence of the thermodynamic quantities of the subtransitions including the volume change. PMID:25779604

  7. Irradiation techniques under high pressurized water using hybrid type saturated temperature capsule in the JMTR

    NASA Astrophysics Data System (ADS)

    Matsui, Y.; Niimi, M.; Hoshiya, T.; Tsukada, T.; Tsuji, H.

    1998-10-01

    The IASCC is one of the major concerns on the integrity of in-core materials not only for the LWRs but also for the materials to be cooled by water in fusion reactor. It is desired to irradiate test materials in a high temperature water environment in order to investigate simultaneous effects of irradiation and corrosive environments, which are essential for the study of IASCC. In the JMTR, an irradiation rig named the SATCAP was developed and applied for the IASCC study. Inside of this capsule, cooling water is boiling during irradiation due to heat generated by gamma heating, thus the temperature of the specimens is kept nearly at saturation temperature of water. Recently a new hybrid type SATCAP with electric heaters and vacuum control systems was developed to improve temperature control capability of the original SATCAP. A design and results of performance test of the new hybrid type SATCAP are reported.

  8. Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapor equilibration laser spectroscopy method

    NASA Astrophysics Data System (ADS)

    Hendry, M. J.; Schmeling, E.; Wassenaar, L. I.; Barbour, S. L.; Pratt, D.

    2015-06-01

    A method to measure the ?2H and ?18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapor equilibration and laser spectroscopy (DVE-LS) was first described in 2008, and has since been widely adopted by others. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE-LS over several years. Generally, good comparative agreement and accuracy is obtained between core pore water isotopic data obtained using DVE-LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE-LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g., water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE-LS analyses yield accurate formational isotopic data for fine-textured core (e.g., clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g., sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE-LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE-LS results can be obtained on core samples with gravimetric water contents < 5 % by increasing the sample size tested. Inexpensive Ziploc gas sampling bags were determined to be as good as, if not better, than other, more expensive bags. Sample storage in gas tight sample bags provides acceptable results for up to 10 days of storage; however, measureable water loss and evaporitic isotopic enrichment occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE-LS approach for obtaining high resolution pore water isotopic data remains a promising alternative to study the hydrogeology of saturated and unsaturated sediments. Eliminating analytical interferences from volatile organics remains a challenge.

  9. Solid state phase transition and vapor pressure studies in ammonium nitrate-potassium nitrate binary system

    NASA Astrophysics Data System (ADS)

    Chien, Wen-Ming

    The solid-state phase transitions in ammonium nitrate (NH4NO 3) and potassium nitrate (KNO3) solid solutions and the equilibrium NH4NO3-KNO3 (AN-KN) phase diagram have been determined. The phase transitions and phase diagram were determined by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special "Dry Room" with very low humidity. In the X-ray diffraction experiments, the samples were heated on Pt-Rh strip and LaB6 or Si was added for internal calibration. Equilibrium phase diagram was also calculated by using the "FactSage" computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 25wt% KNO3 in NH4NO3 that is critical for air bag gas generators. The higher temperature KNO3 (KN I) phase has a wide stability range, from 100%KNO3 to 20%KNO3 solution. There is one eutectic, two eutectoids, and two peritectoids in this phase diagram. Two newly discovered solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria and lattice expansions during heating have been determined. Phase diagram calculations show a reasonable match of the phase boundaries. The total vapor pressures as well as the average molecular weights of pure ammonium nitrate and 16% KNO3 solid solution were measured at various temperatures by the torsion-Knudsen effusion method. The partial pressures of NH4NO3 (PNH4NO 3), NH3 (PNH3), and HNO3 (PHNO 3) have also been determined.

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

    PubMed

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

    2015-01-29

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  12. The Evolution of Mechanisms Driving the Stomatal Response to Vapor Pressure Deficit1[OPEN

    PubMed Central

    McAdam, Scott A.M.; Brodribb, Timothy J.

    2015-01-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. PMID:25637454

  13. Altered physiology and biochemistry of imported litchi fruit held under different vapor pressure deficits.

    PubMed

    Somboonkaew, Nettra; Terry, Leon A

    2010-05-26

    The effects of vapor pressure deficit (VPD) on litchi fruit quality have not yet been fully defined. The aim of this study was to detail the changes in physiology, sugars, organic acids, and individual anthocyanin concentrations in imported litchi fruit held at various controlled relative humidity (RH) and VPD levels. SO(2)-fumigated (but not acid-treated) litchi imported from Thailand (cv. Kom) and from Israel (cv. Mauritius) were air freighted to the United Kingdom and then stored for 9 days at either 5 or 13 degrees C to simulate shelf-life conditions. Fruits were stored under a series of controlled RH conditions for the duration of the trial using different concentrations of glycerol in deonized water. Respiration rates and weight losses of both fruit lots were greater in litchi stored at 13 degrees C and a VPD of 0.274 kPa. At 5 degrees C and a VPD of 0 or 0.042 kPa, sugars and organic acids in aril and pericarp tissue and individual anthocyanins in pericarp were better maintained. This is the first piece of work that has systematically evaluated the effect of a series of VPDs on litchi fruit biochemistry such that implications for designing systems to better maintain the physiological quality of imported litchi fruit are discussed. PMID:20438127

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  15. Solubilities and vapor pressures of the water + lithium bromide + ethanolamine system

    SciTech Connect

    Kim, J.S.; Park, Y.; Lee, H. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemical Engineering] [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemical Engineering

    1996-03-01

    Solubilities of lithium bromide in the water (1) + lithium bromide (2) + ethanolamine (3) system at three different ratios (w{sub 2}/w{sub 3} = 4.5, 4, and 3.5) were measured by using the visual polythermal method in temperature ranges of (281.35 to 333.55) K, (281.65 to 333.55) K, and (275.45 to 345.95) K, respectively. Each set of experimental measurements was correlated with two least-squares regression equations as a function of temperature. The average absolute deviations between the experimental and the calculated solubilities were less than 0.04%. Vapor pressures of the water + lithium bromide + ethanolamine system (LiBr/H{sub 2}N(CH{sub 2}){sub 2}OH mass ratio 3.5/1) were also measured by a boiling point method in the temperature range of (319.75 to 418.35) K and in the absorbent concentration range of (50.0 to 79.3) mass %. The experimental values were well correlated with an Antoine-type equation, and the overall average absolute deviation was found to be 0.85%. These experimental results indicate that the mixture studied can be used as a new working fluid in an absorption chiller.

  16. Thermal stability of InN epilayers grown by high pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Acharya, Ananta R.; Gamage, Sampath; Senevirathna, M. K. Indika; Alevli, Mustafa; Bahadir, Kucukgok; Melton, Andrew G.; Ferguson, Ian; Dietz, Nikolaus; Thoms, Brian D.

    2013-03-01

    The thermal stability of InN layers grown on sapphire by high-pressure chemical vapor deposition has been studied by thermal desorption, atomic force microscopy, X-ray diffraction, and infrared reflection measurements. Desorption products from samples grown with group V/III precursor ratios from 1200 to 4800, but otherwise identical growth conditions, have been monitored using differentially-pumped mass spectrometry while the sample temperature was ramped from room temperature to 825 C. No significant desorption of nitrogen from the surface was observed below 630 C, with a rapid increase of desorption of molecular nitrogen at substrate temperatures above 630 C. No significant desorption of NH*/NH2* fragments was observed. From Arrhenius plots, the activation energy for desorption of nitrogen was found to be 1.6 0.2 eV. It was observed that the activation energy for the desorption of nitrogen from InN samples was independent of V/III precursor ratio. However, the temperature corresponding to the maximum desorption was found to be dependent on V/III precursor ratio, increasing from 749 C for V/III precursor ratio of 1200 to 776 C for V/III precursor ratio of 4800. The observed shift in the peak desorption temperature with increasing group V/III precursor ratio is attributed to the decrease in extended defects and the increase in grain size.

  17. The evolution of mechanisms driving the stomatal response to vapor pressure deficit.

    PubMed

    McAdam, Scott A M; Brodribb, Timothy J

    2015-03-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. PMID:25637454

  18. Growth of Pb 1- xSn xTe ( x?0.12) epitaxial layers by temperature difference under controlled vapor pressure liquid-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Nugraha, .; Tamura, Wataru; Itoh, Osamu; Suto, Ken; Nishizawa, Jun-ichi

    2000-10-01

    Pb 1- xSn xTe ( x?0.12) liquid-phase epitaxial layers have been grown by the temperature difference method under controlled vapor pressure (TDM-CVP) using Pb solvents on PbTe substrates at temperatures 490C and 600C. The grown layers are usually n-type, and the optimum Te vapor pressure where the carrier concentration becomes minimum is 3.110 -3> PTe>1.410 -3 Torr for Tg=600C, and 3.110-5 >P Te>1.410-5 Torr for Tg=490C. The activation energy of the optimum Te vapor pressure for Pb 1- xSn xTe ( x?0.12) is 2.38 eV, which is larger than the activation energy for PbTe, 2.12 eV. Two different types of etch pits are observed on Pb 1- xSn xTe ( x?0.12) layers. The density of the smaller size etch pits tends to become minimum at the optimum Te vapor pressure, while the larger size etch pits are dominantly observed at the vapor pressure region above the optimum vapor pressure. This tendency and lower electron mobility suggest defect aggregation taking place above the optimum vapor pressure.

  19. An investigation of saturation-capillary pressure relations in two- and three-fluid systems for several NAPLS in different porous media

    SciTech Connect

    Busby, R.D. [ICF Kaiser, Rancho Cordova, CA (United States); Lenhard, R.J. [Pacific Northwest Lab., Richland, WA (United States); Rolston, D.E. [Univ. of California, Davis, CA (United States)

    1995-07-01

    Lack of constitutive data has impeded efforts to model the subsurface transport of organic-liquid contaminants. To help fill this need, functional relationships between fluid saturations and capillary pressures were obtained using a unique fluid-retention cell. The functional relationships between water saturations and NAPL-water capillary pressures, and between total-liquid saturations and air-NAPL capillary pressures in two- and three-fluid phase systems were measured directly during monotonic drainage of a fine quartz sand and a nonswelling loam soil. Additionally, measurements were made between water saturations and air-water capillary pressures for an air-water fluid system in both porous media. The NAPLs investigated were Soltrol 170{reg_sign}, toluene, and trichloroethylene (TCE). Following the measurements, the two- and three-fluid retention relations were compared to test the validity of extending two-phase saturation-pressure (S-P) relations to three-fluid systems. Good agreement was observed between the two- and three-fluid data for Soltrol 170{reg_sign}, toluene, and TCE in both porous media. An S-P scaling format for two- and three-phase systems was also evaluated. Results indicate that a single multiphase retention function is suitable for describing two- and three-phase S-P relations in similar porous media; however, it is unclear whether the scaling factors can be predicted a priori from ratios of interfacial tensions.

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

    PubMed

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

    1992-08-01

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

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

    USGS Publications Warehouse

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

    1992-01-01

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

  2. Hydration of the organized molecular assembly of ionic surfactants as studied by vapor pressure and x-ray diffraction

    Microsoft Academic Search

    K. Fukada; Y. Matsuzaka; Y. Ito; T. Nakazato; K. Matsui; Y. Hosoi; M. Fujii; T. Kato; T. Shirakawa; T. Seimiya

    1993-01-01

    Equilibrium vapor pressure of water was measured for ionic surfactant-water binary systems as a function of water content over the temperature range 511C. The measurement of x-ray powder diffraction has also been performed to characterize the microscopic structures of these two-component systems. Examined surfactants were the homologs of sodium alkyl sulfate and alkyltrimethylammonium bromide. It was found that dodecyl and

  3. Transparent and Conductive ZnO Thin Films Prepared by Atmospheric-Pressure Chemical Vapor Deposition Using Zinc Acetylacetonate

    Microsoft Academic Search

    Tadatsugu Minami; Hideo Sonohara; Shinzo Takata; Hirotoshi Sato

    1994-01-01

    Highly transparent and conductive undoped and impurity-doped ZnO thin films have been prepared by atmospheric-pressure chemical vapor deposition (CVD) using Zn(C5H7O2)2 as a zinc source. A resistivity as low as 4.610-3 Omega cm and an average transmittance above 85% in the visible range were obtained for undoped ZnO thin films deposited at 550C using H2O as the oxygen source.

  4. Formation of Nanometer Silicon Dots with Germanium Core by Highly-Selective Low-Pressure Chemical Vapor Deposition

    Microsoft Academic Search

    Yudi Darma; Hideki Murakami; Seiichi Miyazaki

    2003-01-01

    Spherical Si nanocrystallites with a Ge core on ultrathin SiO2 have been prepared by controlling the selective growth conditions of low-pressure chemical vapor deposition (LPCVD) using alternately pure SiH4 and 5% GeH4 diluted with He. Cross-sectional transmission electron microscopy (TEM) images show spherical Si nanocrystallites with a Ge core in contrast with hemispherical Si dots on SiO2, implying a high

  5. Selective epitaxial growth of silicon-germanium by a tubular hot-wall low pressure chemical vapor deposition system

    Microsoft Academic Search

    I-Ming Lee

    1997-01-01

    The goal of this study is to obtain fundamental process-property relationships for the SiGe epitaxial growth and from such knowledge to assemble a tubular hot-wall low pressure chemical vapor deposition system capable of producing selective epitaxial SiGe films. This is the very first report of such an attempt by any research group to produce epitaxial SiGe films using this type

  6. Self-assembled germanium islands grown on (0 0 1) silicon substrates by low-pressure chemical vapor deposition

    Microsoft Academic Search

    G. D. M. Dilliway; D. M. Bagnall; N. E. B. Cowern; C. Jeynes

    2003-01-01

    The time evolution of self-assembled Ge islands, during low-pressure chemical vapor deposition (LPCVD) of Ge on Si at 650 C using high growth rates, has been investigated by atomic force microscopy, transmission electron microscopy, and Rutherford backscattering spectrometry. We have found three different island structures. The smallest islands are lens-shaped and characterized by a rather narrow size distribution, 4 nm

  7. Reaction Engineering Modeling of Low-Pressure Metalorganic Chemical Vapor Deposition of Nb2O5 Thin Film

    Microsoft Academic Search

    Sang-Chul Jung; Nobuyuki Imaishi; Heung-Chul Park

    1995-01-01

    Thin films of niobium oxide (V) were prepared by low-pressure metalorganic chemical vapor deposition (LPMOCVD) from bis-dipivaloylmethanate niobium trichloride in a horizontal tube hot-wall reactor. The dependence of growth rate, crystal orientation, morphology and chemical composition on operating conditions were studied experimentally. The profile of the thin film grown on microscale trenches and the macroscopic growth rate distribution in the

  8. Oxynitride gate dielectric prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride

    Microsoft Academic Search

    Jackie Chan; Hei Wong; M. C. Poon; C. W. Kok

    2003-01-01

    Thin oxynitride gate dielectric films were prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride at temperature ranging 8501050 C. X-ray photoelectron spectroscopy results indicate that the conversion of the as-deposited silicon nitride into oxynitride with different composition or oxide is feasible and the process is governed by the oxidation temperature. For sample oxidized at 1050 C

  9. Preparation of an oxidation protection coating for c\\/c composites by low pressure chemical vapor deposition

    Microsoft Academic Search

    L. F. Cheng; Yongdong Xu; Litong Zhang; Xiaowei Yin

    2000-01-01

    Preparation defects in a SiC coating on C\\/C substrates are considered to be the controlling factor which decreases the oxidation protection life at the temperature of preparing. To decrease the number of such defects, a low-pressure chemical vapor deposition (LPCVD) method, instead of general CVD was used, and the substrates were suspended, rather than supported. Multi-deposition was employed to seal

  10. Recrystallization of amorphous silicon films deposited by low-pressure chemical vapor deposition from Si2H6 gas

    Microsoft Academic Search

    Kenji Nakazawa

    1991-01-01

    This paper investigated the recrystallization of low-pressure chemical vapor deposition amorphous silicon (a-Si) films deposited using Si2H6 gas at various substrate temperatures. The grain size of recrystallized films formed from Si2H6 is larger than that formed from SiH4. The maximum grain size is obtained at the substrate temperature of 460 C, where the nucleation rate is minimum due to the

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

    E-print Network

    Wang, Gwo-Ching

    Surface roughening in low-pressure chemical vapor deposition Jason T. Drotar, Y.-P. Zhao, T.-M. Lu of a reemission model for chemical vapor deposition. We find that, for pure first-order reemission, the interface on chemical vapor deposition. DOI: 10.1103/PhysRevB.64.125411 PACS number s : 68.55.Jk, 05.40. a, 05.45. a, 68

  12. Effusion Cell Measurements of the Vapor Pressure of Cobalt at Temperatures up to 2000K; Comparisons with Iron and Nickel

    NASA Technical Reports Server (NTRS)

    Nuth, J. A.; Ferguson, F. T.; Johnson, N. M.

    2004-01-01

    It has become increasingly clear over the past decade that high temperature processes played important roles in the Primitive Solar Nebula. Unfortunately, basic data, such as the vapor pressures of Fe, Ni, Co or SiO have not been measured over the appropriate temperature range (near T approx. 2000K), but must be extrapolated from lower temperature measurements often made more than 50 years ago. The extrapolation of the available data to higher temperatures can be quite complex (e.g., see [1] for SiO vapor pressures) and can depend on other factors such as the oxygen fugacity or the presence of hydrogen gas not accounted for in the original measurements. Moreover, modern technology has made possible more accurate measurements of such quantities over a wider temperature range. We have acquired a commercial Thermo-Cahn Thermogravimetric system capable of vacuum operation to 1700C and measurement of a 10g change in sample mass using up to a 100g sample, with microgram accuracy. With this new system we have initiated a series of basic vapor pressure measurements on simple metals such as Fe[2] and Ni[3] with the intention to extend such measurements to more complex systems once we gain sufficient experience.

  13. Volatile times for the very first ionic liquid: understanding the vapor pressures and enthalpies of vaporization of ethylammonium nitrate.

    PubMed

    Emel'yanenko, Vladimir N; Boeck, Gisela; Verevkin, Sergey P; Ludwig, Ralf

    2014-09-01

    A hundred years ago, Paul Walden studied ethyl ammonium nitrate (EAN), which became the first widely known ionic liquid. Although EAN has been investigated extensively, some important issues still have not been addressed; they are now tackled in this communication. By combining experimental thermogravimetric analysis with time of flight mass spectrometry (TGA-ToF-MS) and transpiration method with theoretical methods, we clarify the volatilisation of EAN from ambient to elevated temperatures. It was observed that up to 419?K, EAN evaporates as contact-ion pairs leading to very low vapour pressures of a few Pascal. Starting from 419?K, the decomposition to nitric acid and ethylamine becomes more thermodynamically favourable than proton transfer. This finding was supported by DFT calculations, which provide the free energies of all possible gas-phase species, and show that neutral molecules dominate over ion pairs above 500?K, an observation that is in nearly prefect agreement with the experimental boiling point of 513?K. This result is crucial for the ongoing practical applications of protic ionic liquids such as electrolytes for batteries and fuel cells because, in contrast to high-boiling conventional solvents, EAN exhibits no significant vapour pressure below 419?K and this property fulfils the requirements for the thermal behaviour of safe electrolytes. Overall, EAN shows the same barely measurable vapour pressures as typical aprotic ionic liquids at temperatures only 70?K lower. PMID:25077820

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

    USGS Publications Warehouse

    Iverson, R.M.

    1993-01-01

    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.

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

    SciTech Connect

    Dugrain, Vincent; Reichel, Jakob [Laboratoire Kastler Brossel, ENS, UPMC, CNRS, 24 rue Lhomond, 75005 Paris (France); Rosenbusch, Peter [LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 av de lObservatoire, 75014 Paris (France)

    2014-08-15

    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.

  16. Preparation and residual stress characterization of polycrystalline silicon germanium films grown by atmospheric pressure chemical vapor deposition

    SciTech Connect

    Fiorini, P.; Sedky, S.; Caymax, M.; Baert, C.

    1997-07-01

    Polycrystalline silicon-germanium alloys (poly-SiGe) are deposited by chemical vapor deposition at atmospheric and reduced pressure. The stress, as well as its profile along the growth direction, are measured. Depending on the deposition pressure the stress can be compressive or tensile, the profile of the stress is in both cases rather uniform. The behavior of the stress as a function of annealing temperature is also investigated. Films which are compressive as grown can be made tensile by annealing, films which are tensile as grown remains tensile even after high temperature annealing.

  17. Effects of capillarity and vapor adsorption in the depletion of vapor-dominated geothermal reservoirs

    SciTech Connect

    Pruess, Karsten; O'Sullivan, Michael

    1992-01-01

    Vapor-dominated geothermal reservoirs in natural (undisturbed) conditions contain water as both vapor and liquid phases. The most compelling evidence for the presence of distributed liquid water is the observation that vapor pressures in these systems are close to saturated vapor pressure for measured reservoir temperatures (White et al., 1971; Truesdell and White, 1973). Analysis of natural heat flow conditions provides additional, indirect evidence for the ubiquitous presence of liquid. From an analysis of the heat pipe process (vapor-liquid counterflow) Preuss (1985) inferred that effective vertical permeability to liquid phase in vapor-dominated reservoirs is approximately 10{sup 17} m{sup 2}, for a heat flux of 1 W/m{sup 2}. This value appears to be at the high end of matrix permeabilities of unfractured rocks at The Geysers, suggesting that at least the smaller fractures contribute to liquid permeability. For liquid to be mobile in fractures, the rock matrix must be essentially completely liquid-saturated, because otherwise liquid phase would be sucked from the fractures into the matrix by capillary force. Large water saturation in the matrix, well above the irreducible saturation of perhaps 30%, has been shown to be compatible with production of superheated steam (Pruess and Narasimhan, 1982). In response to fluid production the liquid phase will boil, with heat of vaporization supplied by the reservoir rocks. As reservoir temperatures decline reservoir pressures will decline also. For depletion of ''bulk'' liquid, the pressure would decline along the saturated vapor pressure curve, while for liquid held by capillary and adsorptive forces inside porous media, an additional decline will arise from ''vapor pressure lowering''. Capillary pressure and vapor adsorption effects, and associated vapor pressure lowering phenomena, have received considerable attention in the geothermal literature, and also in studies related to geologic disposal of heat generating nuclear wastes, and in the drying of porous materials. Geothermally oriented studies were presented by Chicoine et al. (1977), Hsieh and Ramey (1978, 1981), Herkelrath et al. (1983), and Nghiem and Ramey (1991). Nuclear waste-related work includes papers by Herkelrath and O'Neal (1985), Pollock (1986), Eaton and Bixler (1987), Pruess et al. (1990), Nitao (1990), and Doughty and E'ruess (1991). Applications to industrial drying of porous materials have been discussed by Hamiathy (1969) arid Whitaker (1977). This paper is primarily concerned with evaluating the impact of vapor pressure lowering (VPL) effects on the depletion behavior of vapor-dominated reservoirs. We have examined experimental data on vapor adsorption and capillary pressures in an effort to identify constitutive relationships that would be applicable to the tight matrix rocks of vapor-dominated systems. Numerical simulations have been performed to evaluate the impact of these effects on the depletion of vapor-dominated reservoirs.

  18. Vapor pressure deficit controls on fire ignition and fire spread in boreal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Sedano, F.; Randerson, J. T.

    2014-01-01

    Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different fire processes, including ignition, daily fire spread rates, and cumulative annual burned area. Here we combined MODIS active fires (MCD14ML), MODIS imagery (MOD13A1) and ancillary historic fire perimeter information to produce a dataset of daily fire spread maps of Alaska for the period 2002-2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed together with daily vapor pressure deficit (VPD) observations from the North American Regional Reanalysis (NARR) and lightning strikes from the Alaska Lightning Detection Network (ALDN). We found a significant relationship between daily VPD and probability that a lightning strike would develop into a fire ignition. In the first 5 days after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread rates, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979-2011; R2 = 0.45). Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our spatiotemporal analysis provide new information about temporal and spatial dynamics of wildfires and have implications for modeling the terrestrial carbon cycle.

  19. Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films

    SciTech Connect

    Hoffman, D.M. [Houston Univ., TX (United States); Atagi, L.M. [Houston Univ., TX (United States)]|[Los Alamos National Lab., NM (United States); Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang [Houston Univ., TX (United States); Rubiano, R.R. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Springer, R.W.; Smith, D.C. [Los Alamos National Lab., NM (United States)

    1994-06-01

    Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

  20. Fabrication of Ferrite Thin Film using Low Pressure Metalorganic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Yang, Yi

    This thesis is based on the research work on the multiferroic material fabrications using low pressure metalorganic chemical vapor deposition (MOCVD). Multiferroic material refers to the ones who have two or more ferroic properties, like ferroelectricity, ferromagnetism, ferroelasticity and ferrotoroidicity. Extensive research findings focused on pure nano scale thin films and composites those were related to presenting both ferroelectricity and ferromagnetism coupling within the material. BiFeO3 (BFO) was known to be the only single phase multiferroic material which exhibited magnetoelectric (ME) coupling effect at room temperature. This coupling effect provided an extra degree of freedom for designs of whole new devices and applications never thought to be possible before. Recently, large ME effect was found in its thin epitaxial-strained films. However, very few papers reported the CVD techniques for depositing BFO thin films so far. Most of these reports used direct liquid injection method to deliver the organometallic reactants during the CVD process (ie. DLICVD). Here, we introduced a novel liquid iron precursor, n-butylferrocene, delivered into the reactor by heating the precursor canisters at certain temperatures for growing BFO thin films. Other crucial MOCVD conditions (reactor's pressure, reactor's temperature, substrates...) were also discussed and optimized. Characterizations for the film composition, crystallinity, ferroelectricity, ferromagnetism and the magneto-dielectric coupling effect were analyzed in detail. The results confirmed that BFO film had multiferroic properties and could be potentially used in future tunable high-frequency devices. Although single-phase BFO exhibited ME effect, this suffered from problems such as current leakages, weak ME coupling and low ordering temperatures. Doping or ion substitution was a limited way to enhance the ME property since the compounds had definite compositions. Therefore, heterostructures such as bilayered/multilayered thin films, nanoparticles/nanopillars embedded in different materials and nanowires became more promising for the future on-chip integration applications because the coupling in such structures was many orders of magnitude stronger. Another research scientists interested in was the heterostructural magnetostrictive NiFe2O4 (NFO) with piezoelectric materials. NFO was a promising magnetic phase for ME heterostructures due to its low anisotropy, high permeability with high resistivity, low eddy current losses and smaller coercive field. In this study, the nickel ferrite thin films had been deposited using computer controlled MOCVD setup in both co-deposition mode and cyclic-deposition mode. Conditions for CVD process were discussed and optimized for growing NFO thin film. The thin films showed NFO composition, uniformity in chemical states and thickness, trevorite crystalline form, free from carbon contamination and similar magnetic property as other literature reported.

  1. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    SciTech Connect

    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

    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.

  2. Numerical study of two-phase flows in porous media : extraction of a capillary pressure saturation curve free from boundary effects

    NASA Astrophysics Data System (ADS)

    Fiorentino, Eve-Agns; Moura, Marcel; Jrgen Mly, Knut; Toussaint, Renaud; Schfer, Gerhard

    2015-04-01

    The capillary pressure saturation relationship is a key element in the resolution of hydrological problems that involve the closure partial-flow Darcy relations. This relationship is derived empirically, and the two typical curve fitting equations that are used to describe it are the Brooks-Corey and Van Genchten models. The question we tackle is the influence of the boundary conditions of the experimental set-up on the measurement of this retention curve, resulting in a non physical pressure-saturation curve in porous media, due the "end effects" phenomenon. In this study we analyze the drainage of a two-phase flow from a quasi 2D random porous medium, and compare it to simulations arising from an invasion percolation algorithm. The medium is initially saturated with a viscous fluid, and as the pressure difference is gradually increased, air penetrates from an open inlet, thus displacing the fluid which leaves the system from the outlet in the opposing side. In the initial stage, the liquid-air interface evolves from a planar front to the fractal structure characteristic of slow drainage processes, giving the initial downward curvature. In the final stage, air spreads all along the filter, and must reach narrower pores, calling for an increase of the pressure difference, reflected by the final upward curvature. Measuring the pressure-saturation (P-S) law in subwindows located at the inlet, outlet and middle of the network, we emphasize that these boundary effects are the fact of a fraction of pores that is likely to be negligible for high scale systems. We analyze the value of the air saturation at the end of the experiment for a series of simulations with different sample geometries : we observe that this saturation converges to a plateau when the distance between the inlet ant outlet increases, and that the value of this plateau is determined by the distance between the lateral walls. We finally show that the pressure difference between the two phases converges to a value determined by the cumulative density function of the capillary pressures distribution, until the filter is reached, triggering the upward curvature of the curve. The boundary effects bring unphysical features to the P-S curve, that may be present in the results of widely used core sample tests. Far from the boundaries, the relationship between pressure and saturation shows a flat profile dominated by a unique constant determined by the capillary pressure distribution of the medium.

  3. Vapor pressure measurement for water, methanol, ethanol, and their binary mixtures in the presence of an ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate

    Microsoft Academic Search

    Jun-Feng Wang; Chun-Xi Li; Zi-Hao Wang; Zi-Jia Li; Yan-Bin Jiang

    2007-01-01

    Vapor pressure data were measured for water, methanol and ethanol as well as their binary mixtures with an ionic liquid (IL) 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) at varying temperature and IL-content ranging from mass fraction of 0.100.70 by a quasi-static method. The vapor pressure data for the IL-containing binary systems were correlated using NRTL equation with average absolute relative deviation (ARD) within

  4. Thin film properties of low-pressure chemical vapor deposition TiN barrier for ultra-large-scale integration applications

    Microsoft Academic Search

    Rama I. Hegde; Robert W. Fiordalice; Edward O. Travis; Philip J. Tobin

    1993-01-01

    Titanium nitride films deposited by low-pressure chemical vapor deposition (LPCVD) on Si(100) using TiCl and NH as reactants, were investigated as a function of deposition temperature between 400 and 700°C. LPCVD TiN depositions were carried out in a rapid thermal chemical vapor deposition system with a total deposition pressure of 155 mTorr. Stoichiometric TiN films were formed regardless of the

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

    E-print Network

    Mistry, Karan Hemant

    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 ...

  6. Pressure and power generation during explosive vaporization on a thin-film microheater

    Microsoft Academic Search

    Z. Zhao; S. Glod; D. Poulikakos

    2000-01-01

    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?m110?m) was placed on the underside of a water layer. The surface

  7. Graphene chemical vapor deposition at very low pressure: The impact of substrate surface self-diffusion in domain shape

    SciTech Connect

    Cunha, T. H. R.; Ek-Weis, J.; Lacerda, R. G.; Ferlauto, A. S., E-mail: ferlauto@fisica.ufmg.br [Department of Physics, Federal University of Minas Gerais, Belo Horizonte 31270-901 (Brazil)

    2014-08-18

    The initial stages of graphene chemical vapor deposition at very low pressures (<10{sup ?5?}Torr) were investigated. The growth of large graphene domains (?up to 100??m) at very high rates (up to 3??m{sup 2} s{sup ?1}) has been achieved in a cold-wall reactor using a liquid carbon precursor. For high temperature growth (>900?C), graphene grain shape and symmetry were found to depend on the underlying symmetry of the Cu crystal, whereas for lower temperatures (<900?C), mostly rounded grains are observed. The temperature dependence of graphene nucleation density was determined, displaying two thermally activated regimes, with activation energy values of 6??1?eV for temperatures ranging from 900?C to 960?C and 9??1?eV for temperatures above 960?C. The comparison of such dependence with the temperature dependence of Cu surface self-diffusion suggests that graphene growth at high temperatures and low pressures is strongly influenced by copper surface rearrangement. We propose a model that incorporates Cu surface self-diffusion as an essential process to explain the orientation correlation between graphene and Cu crystals, and which can clarify the difference generally observed between graphene domain shapes in atmospheric-pressure and low-pressure chemical vapor deposition.

  8. Water saturated phase relations of some andesites with application to the estimation of the initial temperature and water pressure at the time of eruption

    Microsoft Academic Search

    Toshimori Sekine; Takashi Katsura; Shigeo Aramaki

    1979-01-01

    Near-liquidus phase relations in one-atmosphere dry and water-saturated high pressure conditions were experimentally determined on products of three historic andesitic eruptions. Run conditions ranged from 900 to 1100C, at pressures up to 1500 bars with fO 2 controlled close to the nickel-nickel oxide (NNO) buffer. In order to represent the compositions of the true liquid parts of the erupting magmas,

  9. Validity of the Ruff-MKW-boiling point method: Vapor pressure of liquid cesium chloride, viscosity coefficient of gaseous cesium chloride, and gaseous interdiffusion coefficient for cesium chloride in argon and helium

    Microsoft Academic Search

    P. G. Wahlbeck; D. L. Myers; T. L. Hendrixson; F. D. Pierson; S. A. Pyles

    1984-01-01

    The Ruff-MKW-boiling point method is used to determine equilibrium vapor pressures, viscosity coefficients of the sample vapor, and the gaseous interdiffusion coefficients of the sample vapor in an inert gas. The experimental data are mass flow rates from a sample container which has a capillary exit, in the presence of an inert gas at a measured pressure, under isothermal conditions.

  10. Solvent vapor recovery by pressure swing adsorption. 3: Comparison of simulation with experiment for the butane-activated carbon system

    SciTech Connect

    Liu, J.; Holland, C.E.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)] [Univ. of South Carolina, Columbia, SC (United States)

    1999-06-01

    A fully predictive (no adjustable parameters), nonisothermal, multicomponent mathematical model was developed and used to simulate a pressure swing adsorption (PSA) process designed for the separation and recovery of concentrated butane vapor from nitrogen using BAX activated carbon. Nearly quantitative agreement with experiment was realized with this model over a wide range of process conditions, and for both the transient and periodic state process dynamics and the periodic state process performance. The model also verified some unique characteristics of this PSA process, and it revealed some of the subtleties associated with accurately simulating a PSA-solvent vapor recovery (SVR) process. These subtleties included the need to account for the adsorbate heat capacity and the temperature dependence of the gas-phase physical properties. No PSA models in the literature have included both of these features, which were critical to the accurate prediction of the heat effects in this PSA-SVR process.

  11. Temporal evolution of the electron density produced by nanosecond repetitively pulsed discharges in water vapor at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Sainct, Florent; Lacoste, Deanna; Kirkpatrick, Michael; Odic, Emmanuel; Laux, Christophe

    2014-10-01

    A study of plasma discharges produced by nanosecond repetitive pulses (NRP) in water vapor at 450 K and 1 atm is presented. The plasma was generated between two point electrodes with 20-ns duration, high-voltage (0--20 kV) pulses, at a repetition frequency of 10 kHz, in the spark regime (2 mJ/pulse). Atomic lines measured by optical emission spectroscopy were used to determine the electron number density in this non-equilibrium water-vapor plasma. The broadenings and shifts of the H? and H? lines of the hydrogen Balmer series and of the atomic oxygen triplet at 777 nm were analyzed. For a maximum reduced electric field of about 200 Td, a maximum electron density of 2 1018 cm-3 was measured, corresponding to an ionization level of about 10 %. This ionization level is two orders of magnitude higher than the one obtained for similar NRP discharges in air at atmospheric pressure.

  12. Transport properties of nonelectrolyte liquid mixturesV. Viscosity coefficients for binary mixtures of benzene plus alkanes at saturation pressure from 283 to 393 K

    Microsoft Academic Search

    J. H. Dymond; K. J. Young

    1981-01-01

    Viscosity coefficient measurements at saturation pressure are reported for benzene + n-hexane, benzene + n-octane, benzene + n-decane, benzene + n-dodecane, benzene + n-hexadecane, and benzene + cyclohexane at temperatures from 283 to 393 K. The characteristic parameter G in the Grunberg and Nissan equation

  13. Does Spatial Variation in Soil Characteristics Affect Tree Transpiration Responses to Vapor Pressure Deficit?

    NASA Astrophysics Data System (ADS)

    Traver, E.; Ewers, B. E.; Loranty, M.; Mackay, D. S.

    2006-12-01

    Forest canopy transpiration (Ec) both depends on and influences the local and regional atmospheric conditions. Because soil is the source of water for Ec, the soil's chemical and physical properties are also likely to be drivers of transpiration. The objective of this study is to spatially quantify the relationship between the soil's chemical and physical characteristics and Ec across environmental gradients. The two study sites are in northern Wisconsin, in mixed hardwood forest. In one site, the environmental gradient runs from a dry upland dominated by aspen (Populus tremuloides) to a wetland dominated by alders (Alnus rugosa). The second site has little elevational variation, is well-drained, and is dominated by sugar maple (Acer saccharum) bisected by a swath of red pine (Pinus resinosa). Ec data have been collected over three summers on the same set of trees using Granier sensors, while the soil samples were collected in 2006 from the same plots as the measured trees. Both of the approximately 120 m x 120 m plots have been sampled in 10 m x 10 m subplots based on a 3/7 cyclic sampling scheme to maximize spatially explicit information with a minimum number of sampled points. Roughly 150 trees were measured in each plot. We have previously shown an inverse relationship between the spatial autocorrelation of Ec and vapor pressure deficit (D). We thus hypothesize that a significant amount of this relationship can be explained by soil properties. Preliminary analysis of soil data from a representative transect in the aspen site show that soil texture, carbon (C) content, and nitrogen (N) content change along the gradient. From the upland through the wetland, Ec declined significantly, and, while all the soils were a sandy loam, the sand content showed a decreasing trend, while the silt content increased nearly two-fold. Across the same (upland to wetland) gradient, the C:N ratio showed a slightly increasing trend, but the total percentage values of the two elements increased nearly 25 fold: from C of 0.884 and N of 0.060 to C of 22.34 and N of 1.283. We hypothesize that the maple site will show less variability in Ec because of its more uniform soil characteristics. Ongoing work of soil moisture release curves, bulk density, and root biomass will provide additional explanations of the spatial relationships between Ec and D. Our analytical approach, then, provides a first step in explaining the processes behind spatial patterns in transpiration.

  14. High-Throughput Walkthrough Detection Portal as a Measure for Counter Terrorism: Design of a Vapor Sampler for Detecting Triacetone Triperoxide Vapor by Atmospheric-Pressure Chemical-Ionization Ion-Trap Mass Spectrometry

    Microsoft Academic Search

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

    2012-01-01

    Aiming to prevent terrorist attacks in places where many people are coming and going, we have been developing a high-throughput detection portal system. The portal system consists of a vapor sampler, an atmospheric-pressure chemical-ionization ion source, and an explosives detector based on ion-trap mass spectrometry. The vapor sampler was designed to be installed in an automated ticket gate of a

  15. Optical detection of growth oscillations from high vacuum up to low-pressure metalorganic vapor phase epitaxy like conditions

    NASA Astrophysics Data System (ADS)

    Deppert, K.; Jnsson, J.; Samuelson, L.

    1992-09-01

    We report optical, real-time detection of growth oscillations for pressures up to low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) like conditions. The measurements were performed using the reflectance difference technique during epitaxial growth of GaAs in a vacuum chemical epitaxy (VCE) chamber in which the LP-MOVPE conditions were obtained by adding hydrogen. Growth oscillations could still be obtained over a wide range of V/III ratios at pressures in the mbar range. Under LP-MOVPE conditions we could observe oscillation amplitudes comparable to those found under VCE conditions. Furthermore, the occurrence of oscillations when hydrogen is introduced shows that the layer-by-layer growth is not affected by the presence of hydrogen. These results seem to open the way for the in situ detection of growth oscillations even in conventional MOVPE systems.

  16. An experimental study of the stability of copper chloride complexes in water vapor at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Archibald, S. M.; Migdisov, A. A.; Williams-Jones, A. E.

    2002-05-01

    The solubility of copper chloride in liquid-undersaturated HCl-bearing water vapor was investigated experimentally at temperatures of 280 to 320C and pressures up to 103 bars. Results of these experiments show that the solubility of copper in the vapor phase is significant and increases with increasing fH 2O , but is retrograde with respect to temperature. This solubility is attributed to the formation of hydrated copper-chloride gas species, interpreted to have a copper-chlorine ratio of 1:1 (e.g., CuCl, Cu 3Cl 3, etc.) and a hydration number varying from 7.6 at 320C, to 6.0 at 300C, and 6.1 at 280C. Complex formation is proposed to have occurred through the reaction: 3 CuCl solid+nH 2O gas? Cu 3Cl 3(H 2O) ngas Log K values determined for this reaction are -21.46 0.05 at 280C (n = 7.6), -19.03 0.10 at 300C (n = 6.0), and -19.45 0.12 at 320C (n = 6.1), if it is assumed that the vapor species is the trimer, Cu 3Cl 3(H 2O) 6-8. Calculations based on the above data indicate that at 300C and HCl fluxes encountered in passively degassing volcanic systems, the vapor phase could transport copper in concentrations as high as 280 ppm. Theoretically, this vapor could form an economic copper deposit (e.g., 50 million tonnes of 0.5% Cu) in as little as 20,500 yr.

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

    NASA Astrophysics Data System (ADS)

    Tokunaga, Tetsu K.; Wan, Jiamin; Jung, Jong-Won; Kim, Tae Wook; Kim, Yongman; Dong, Wenming

    2013-08-01

    In geologic carbon sequestration, reliable predictions of CO2 storage require understanding the capillary behavior of supercritical (sc) CO2. Given the limited availability of measurements of the capillary pressure (Pc) dependence on water saturation (Sw) with scCO2 as the displacing fluid, simulations of CO2 sequestration commonly rely on modifying more familiar air/H2O and oil/H2O Pc(Sw) relations, adjusted to account for differences in interfacial tensions. In order to test such capillary scaling-based predictions, we developed a high-pressure Pc(Sw) controller/meter, allowing accurate Pc and Sw measurements. Drainage and imbibition processes were measured on quartz sand with scCO2-brine at pressures of 8.5 and 12.0 MPa (45C), and air-brine at 21C and 0.1 MPa. Drainage and rewetting at intermediate Sw levels shifted to Pc values that were from 30% to 90% lower than predicted based on interfacial tension changes. Augmenting interfacial tension-based predictions with differences in independently measured contact angles from different sources led to more similar scaled Pc(Sw) relations but still did not converge onto universal drainage and imbibition curves. Equilibrium capillary trapping of the nonwetting phases was determined for Pc = 0 during rewetting. The capillary-trapped volumes for scCO2 were significantly greater than for air. Given that the experiments were all conducted on a system with well-defined pore geometry (homogeneous sand), and that scCO2-brine interfacial tensions are fairly well constrained, we conclude that the observed deviations from scaling predictions resulted from scCO2-induced decreased wettability. Wettability alteration by scCO2 makes predicting hydraulic behavior more challenging than for less reactive fluids.

  18. Experiments on two-phase flow in a quasi-2D porous medium: investigation of boundary effects in the measurement of pressure-saturation relationships

    NASA Astrophysics Data System (ADS)

    Moura, Marcel; Fiorentino, Eve-Agns; Jrgen Mly, Knut; Toussaint, Renaud; Schfer, Gerhard

    2015-04-01

    We have performed two-phase flow experiments to analyze the drainage from a quasi-2D random porous medium. The medium is transparent, which allows for the visualization of the invasion pattern during the flow and is initially fully saturated with a viscous fluid (a dyed glycerol-water mix). As the pressure in the fluid is gradually reduced, air penetrates from an open inlet, thus displacing the fluid which leaves the system from the outlet in the opposite side. A feedback mechanism was devised to control the experiment: the capillary pressure (difference in pressure between the non-wetting and wetting phases) is continuously increased to be just above the threshold value necessary to drive the invasion process. This mechanism is intended to keep the invasion process slow, in the so-called capillary regime, where capillary forces dominate the dynamics. Pressure measurements and pictures of the flow are recorded and the pressure-saturation relationship is computed. The effects of the boundary conditions to this quantity are verified experimentally by repeatedly performing the analysis using porous media of different sizes. We show that some features of the pressure-saturation curve are strongly affected by boundary effects. The invasion close to the inlet and outlet of the model are particularly influenced by the boundaries and this is reflected in the phases of pressure building up in the pressure-saturation curves, in the beginning and end of the invasion process. Conversely, at the central part of the model (away from the boundaries), the invasion process happens at an essentially constant capillary pressure, which is reflected as a plateau in the pressure-saturation curve. Additionally, the use of a high-resolution camera allows us to analyze the images down to the pore scale. We can directly obtain a distribution of pore-throat sizes in the model (and their associated capillary pressure thresholds) and divide it into distributions of invaded / non-invaded pores. By measuring these separate distributions dynamically, we can show how they evolve with the invasion process.

  19. Liquid-vapor phase equilibrium in a tin-selenium system

    NASA Astrophysics Data System (ADS)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2014-12-01

    Based on the pressure of the saturated vapor and components over liquid alloys in a tin-selenium system, determined using the boiling points approach (isothermal variant), its boiling point and corresponding vapor phase composition are calculated in the region of liquid solutions. The phase diagram is supple-mented with the liquid-vapor phase transition under atmospheric pressure and in vacuums of 100 and 10 Pa with the boundaries of the region in which the regions of liquid and vapor coexist being determined.

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

    Microsoft Academic Search

    STEFAN ARNORSSON; ANDRI STEFANSSON

    1999-01-01

    The equilibrium constants for endmember feldspar hydrolysis for the following reactions: NaAlSiO + 8HO = Na{sup +} + Al(OH)⁻ + 3HSiO°; KAlSiO + 8HO = K{sup +} + Al(OH)⁻ + 3HSiO°; CaAlSiO + 8HO = Ca{sup +2} + 2Al(OH)⁻ + 2HSiO° are accurately described by five equations where temperature is in K. They are valid in the range 0 to

  1. Realization of the 3He Vapor-Pressure Temperature Scale and Development of a Liquid-He-Free Calibration Apparatus

    NASA Astrophysics Data System (ADS)

    Shimazaki, T.; Toyoda, K.; Tamura, O.

    2011-12-01

    The 3He vapor-pressure temperature scale was realized using an apparatus based on a continuously operating 3He cryostat at the National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST). The cryostat has two operational modes: a 3He circulation mode and a 1 K pot mode. The 3He circulation mode can be used for 3He vapor-pressure measurements below 1.6 K, and the 1 K pot mode can be used for measurements above 1.3 K. Either mode can be selected for measurements from 1.3 K to 1.6 K. The realization of the 3He vapor-pressure temperature scale in this study fully covers its defined temperature range from 0.65 K to 3.2 K in the International Temperature Scale of 1990. The latest realization results are presented in this article. In addition, a liquid-He-free calibration apparatus was developed. It does not require liquid helium as a cryogen, which usually entails cumbersome handling and periodic refilling. The apparatus was designed for the calibration of capsule-type resistance thermometers from 0.65 K to 24.5561 K (the triple point of neon). The cooling system of the apparatus consists of a commercially available pulse-tube refrigerator and a 3He Joule-Thomson (JT) cooling circuit developed at NMIJ/AIST. The pulse-tube refrigerator is used in a pre-cooling stage and cools the apparatus to approximately 5 K. The 3He JT cooling circuit is used to cool the apparatus from 5 K to below 0.65 K. Since the 3He JT cooling circuit is a closed circuit, the apparatus can run continuously with only simple maintenance required. The basic characteristics of the apparatus are described.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  3. Very Long Single and Few-Walled Boron Nitride Nanotubes via the Pressurized Vapor/Condenser Method

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

  4. Transformation of Bromine Species During Decomposition of Bromate under UV Light from Low Pressure Mercury Vapor Lamps

    Microsoft Academic Search

    Neal H. Phillip; Erdal Grten; Vasil Diyamando?lu

    2006-01-01

    Bromate decomposition with low pressure mercury vapor lamps (LPMVL) was studied in buffer-free and buffered Milli-Q water by following the fate of bromine species BrO3 , Br, and free bromine. BrO3 was converted over time to Br with total free bromine (TFBr) as secondary reaction product. BrO3 decay followed pseudo-first-order kinetics and was independent of [BrO3 ]o (0.060.6 mM), pHo

  5. Polycrystalline silicon-germanium films on oxide using plasma-enhanced very-low-pressure chemical vapor deposition

    Microsoft Academic Search

    Julie A. Tsai; Rafael Reif

    1995-01-01

    Si1?xGex thin films on oxide-coated Si substrates have been formed by plasma-enhanced very-low-pressure chemical vapor deposition. Two modes of deposition, thermal and plasma enhanced, were studied using SiH4 and GeH4 at temperatures ?600 C. In both cases, growth rates and grain sizes increase with Ge content, and the polycrystalline-to-amorphous transition temperature is lower for Si1?xGex than Si. Compared to thermal

  6. Vapor pressures in the ternary system water-nitric acid-sulfuric acid at low temperature: A reexamination

    Microsoft Academic Search

    Djamel-Eddine Taleb; Jean-Luc Ponche; Philippe Mirabel

    1996-01-01

    The equilibrium partial vapor pressures over the binary solutions H2O\\/HNO3, H2SO4\\/H2O, HNO3\\/H2SO4 and the ternary mixture H2SO4\\/HNO3\\/H2O have been re-determined for temperatures below 25C. The model presented here is valid over the entire range of concentrations, for temperatures in the range 190-298 K. The predictions of this model are compared with the existing measurements and other predictions, both at room

  7. Electrical characterization of low-pressure chemical-vapor-deposited silicon dioxide metal-oxide-silicon structures

    Microsoft Academic Search

    S. S. Ang; Y. J. Shi; W. D. Brown

    1993-01-01

    The electrical characteristics of as-deposited and oxygen-annealed low-pressure chemical-vapor-deposited (LPCVD) silicon dioxide (SiO2) metal-oxide-silicon (MOS) structures were investigated. As-deposited LPCVD SiO2 MOS structures exhibit a high oxide fixed charge density in the mid-1011 cm?2 and an interface state density in the low-1011 cm?2 eV?1 due to the large number of oxygen and silicon dangling bonds. A low electron barrier height

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

    PubMed

    Hussain, Sajjad; Iqbal, Muhmmad Waqas; Park, Jaehyun; Ahmad, Muneer; Singh, Jai; Eom, Jonghwa; Jung, Jongwan

    2014-01-01

    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

  9. Energy Management - Using Steam Pressure Efficiently

    E-print Network

    Jiandani, N.

    1983-01-01

    Saturated steam contains heat in two different forms. Sensible heat and latent heat. Due to the nature of this vapor, the relative proportion of latent heat is higher at lower pressures compared to higher pressures. When steam is used for heating...

  10. Solvent vapor recovery by pressure swing adsorption. 1: Experimental transient and periodic dynamics of the butane-activated carbon system

    SciTech Connect

    Liu, Y.; Holland, C.E.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)

    1998-11-01

    An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon in a twin-bed pressure swing adsorption (PSA) system utilizing a 4-step Skarstrom-type cycle. Twenty-four runs, covering a broad range of process and initial column conditions, were performed to investigate the transient and period process dynamics. In all cases the approach to the periodic state was very slow, taking up to 160 cycles depending on the initial condition of the beds; and peak bed temperatures of up to 105 C were observed depending on both the initial condition of the beds and the process conditions. Also, the periodic state of each run was unique when approaching a new periodic state from less contaminated beds. The uniqueness of the periodic states, together with the exceedingly high peak temperatures, inferred much about the practice of preconditioning beds to avoid high temperature excursions. The periodic enriched butane vapor concentration histories also gave considerable insight into new cycle designs for improved solvent vapor enrichment.

  11. Spatial and temporal variability of water vapor pressure in the arid region of northwest China, during 1961-2011

    NASA Astrophysics Data System (ADS)

    Yao, Junqiang; Chen, Yaning; Yang, Qing

    2015-01-01

    This paper investigated the spatial and temporal variations of the water vapor pressure (WVP) of the arid region of northwest China (ARNC) from 1961 to 2011. The original daily temperature and relative humidity data were collected from 96 meteorological stations in the region and analyzed by a Mann-Kendall test and linear trend. The results showed that (1) the WVP possesses vertical zonality and longitude zonality, which decreased from the low to high with the elevation increasing, and the WVP changed obviously from the northwest and southeast to the middle of the ARNC. (2) WVP exhibited an abrupt increasing trend in most of the stations over the past 51 years; only four meteorological stations displayed upward trend in the ARNC. The WVP in the desert increased most rapidly, followed by the oasis and mountainous area. (3) The northwest of Xinjiang and northwest of the Hexi Corridor were sensitive to the water vapor change. Thus, further studies should be performed on the relations between the land use and cover and the water vapor change.

  12. Z .Thin Solid Films 392 2001 231 235 Atmospheric pressure chemical vapor deposition of

    E-print Network

    of electrochromic tungsten oxide films Roy G. Gordona,U , Sean Barryb , Jeffrey T. Bartona , Randy N.R. Broomhall oxide, WO , is a coloring layer commonly used in electrochromic windows and displays. Successful: Chemical vapor deposition; Tungsten; Oxides; Electrochromism 1. Introduction Tungsten oxide is a key

  13. Achieving high nucleation density of diamond film under low pressures in hot-filament chemical vapor deposition

    SciTech Connect

    Chen, Y.; Chen, Q.; Lin, Z. [Chinese Academy of Sciences, Beijing (China). Inst. of Physics; Mei, J. [Chinese Academy of Engineering Physics, Sichuan (China)

    1995-08-01

    Diamonds have been deposited rapidly under low pressures (< 0.1 Torr) via hot filament chemical vapor deposition (HFCVD) on either scratched or mirror-smooth single crystalline silicon and titanium with nucleation densities of 10{sup 9}-10{sup 11}/cm{sup 2}. The nucleation density increases with the pressure decreases. Hydrogen and methane were used as the gaseous source. Raman spectroscopy and scanning electron microscopy (SEM) were used to analyze the obtained films. These results breaks through the limit that diamond film can only be synthesized above 10 Torr, showing a promising prospect that, as is essential for heteroepitaxial growth of monocrystalline diamond films, diamond films can be easily nucleated on unscratched substrate via Hot Filament CVD.

  14. Speciation of High-Pressure Carbon-Saturated COH Fluids at Buffered fO2 Conditions: An Experimental Approach

    NASA Astrophysics Data System (ADS)

    Tumiati, S.; Tiraboschi, C.; Recchia, S.; Poli, S.

    2014-12-01

    The quantitative assessment of species in COH fluids is crucial in modelling mantle processes. For instance, H2O/CO2 ratio in the fluid phase influences the location of the solidus and of carbonation/decarbonation reactions in peridotitic systems . In the scientific literature, the speciation of COH fluids has been generally assumed on the basis of thermodynamic calculations using equations of state of simple H2O-non-polar gas systems (e.g., H2O-CO2-CH4). Only few authors dealt with the experimental determination of high-pressure COH fluid species at different conditions, using diverse experimental and analytical approaches (e.g., piston cylinder+capsule-piercing+gas-chromatography/mass-spectrometry; cold-seal+silica glass capsules+Raman). We performed experiments on COH fluids using a capsule-piercing device coupled with a quadrupole mass spectrometry. This type of analyzer ensures superior performances in terms of selectivity of molecules to be detected, high acquisition rates and extended linear response range. Experiments were carried out in a rocking piston cylinder apparatus at pressure of 1 GPa and temperatures from 800 to 900C. Carbon-saturated fluids were generated through the addition of oxalic acid dihydrate and graphite. Single/double capsules and different packing materials (BN and MgO) were used to evaluate the divergence from the thermodynamic speciation model. Moreover, to assess the effect of solutes on COH fluid speciation we also performed a set of experiments adding synthetic forsterite to the charge. To determine the speciation we assembled a capsule-piercing device that allows to puncture the capsule in a gas-tight vessel at 80C. The extraction Teflon vessel is composed of a base part, where the capsule is allocated on a steel support, and a top part where a steel drill is mounted. To release the quenched fluids from the capsule, the base part of vessel is hand-tighten to the top part, allowing the steel pointer to pierce the capsule. The evolved gases are then convoyed to a quadrupole mass spectrometer through a heated line to avoid the condensation of water. Our results suggest that fluid speciation can diverge considerably compared to the thermodynamic model depending on the experimental strategies adopted and on the presence of solutes in complex COH systems.

  15. Real-time explosives/narcotics vapor enhancement and collection systems for use with the atmospheric pressure ionization time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Hintze, M. Marx; Hansen, Byron L.; Heath, Russell L.

    1992-05-01

    This paper is a companion document to the Atmospheric Pressure Ionization Time-of-Flight Mass Spectrometer (API TOFMS) presentation (Lee, et al., 1992). Two significant technique challenges related to design and implementation of vapor collection systems are addressed. They are as follows: (1) freeing deposited or trapped explosive material particles or vapor; and (2) transportation of sample specimen from the pickup point to the detector. Addressed in this dissertation will be both hand-held collection and air shower booth accumulation.

  16. Validity of the RuffMKW boiling point method: Vapor pressures, diffusion coefficients in argon and helium, and viscosity coefficients for gaseous cadmium and zinc

    Microsoft Academic Search

    P. G. Wahlbeck; D. L. Myers; V. V. Truong

    1985-01-01

    The RuffMKW boiling point method is used to determine equilibrium vapor pressures greater than 660 Pa (5 Torr). Samples are vaporized from a Ruff cell, which has a capillary exit, in the presence of an inert gas. Viscosity coefficients and gaseous interdiffusion coefficients may be determined also. This is a second study of the method using Cd(l) and Zn(l) as

  17. 4-62 The water in a rigid tank is cooled until the vapor starts condensing. The initial pressure in the tank is to be determined.

    E-print Network

    Bahrami, Majid

    pressure in the tank is to be determined. Analysis This is a constant volume process (v = V /m = constant that contains water at a specified state. The volume of the tank, the final temperature and pressure contains saturated liquid water. The volume of the cylinder at the initial state is 33 11 m001619.0/kg

  18. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    NASA Technical Reports Server (NTRS)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  19. Low pressure chemical vapor deposition of Si{sub 1-x}Ge films using SiH and GeH source gases

    Microsoft Academic Search

    J. W. Kim; M. K. Ryu; K. B. Kim; S. J. Kim

    1996-01-01

    The authors have investigated the deposition behavior of Si{sub 1-x}Ge (x 0.31) films using SiH and GeH source gases in low pressure chemical vapor deposition. The deposition temperature and pressure were varied from 400 to 500 C and from 0.5 to 1 Torr, respectively. The authors identified that the germanium content in the film slightly increased with pressure, while

  20. Growth of non-polar ZnO thin films with different working pressures by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chao, Chung-Hua; Wei, Da-Hua

    2014-11-01

    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.

  1. Bridgman-type apparatus for the study of growth-property relationships - Arsenic vapor pressure-GaAs property relationship

    NASA Technical Reports Server (NTRS)

    Parsey, J. M.; Nanishi, Y.; Lagowski, J.; Gatos, H. C.

    1982-01-01

    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.

  2. Effect of cluster/particle deposition on atmospheric pressure chemical vapor deposition of SiO2 from four gaseous organic Si-containing precursors and ozone

    NASA Astrophysics Data System (ADS)

    Fujimoto, Toshiyuki; Okuyama, Kikuo; Yamada, Satoshi; Adachi, Motoaki

    1999-04-01

    In order to analyze the particle generation and its effect on the SiO2 thin film in an atmospheric pressure chemical vapor deposition (APCVD) process using four organic silicon vapors and ozone gas, gas-phase particle generation, growth, transportation and vapor-cluster/particle codeposition processes were studied experimentally and theoretically using a flow-type vertical tube reactor. Decomposition reaction rates of four organic silicon vapors (tetraethylorthosilicate, triethoxysilane, tetramethylorthosilicate, and octamethylcyclotetrasiloxane) due to the O?oxidation were determined by arranging the number concentrations of the generated particles in Arrhenius plots. The obtained activation energies and frequency factors of reaction rate constants were used to simulate the vapor-cluster/particle codeposition in the CVD process. In the numerical simulation, computational fluid dynamics equations (continuity, momentum, and energy conservation equations) were solved to evaluate the gas velocity, vapor concentration, and temperature profile inside the reactor. Particle population balance equations based on discrete-sectional presentation for the particle size spectrum were solved coupling with diffusion equations of vapors and clusters/particles. This numerical simulation code could explain the vapor-cluster/particle codeposition in the thin film preparation by the APCVD process. The film growth rate and the surface morphology of the film could be reasonably explained by the deposition flux and the size of deposited clusters/particles obtained as numerical simulation results, respectively.

  3. Transport properties of nonelectrolyte liquid mixturesI. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K

    Microsoft Academic Search

    J. H. Dymond; K. J. Young

    1980-01-01

    Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, ?*GE, at temperatures other than 298 K. However, curves

  4. Transport properties of nonelectrolyte liquid mixtures---I. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K

    Microsoft Academic Search

    J. H. Dymond; K. J. Young

    1980-01-01

    Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, delta* G E, at temperatures other than 298 K.

  5. Transport properties of nonelectrolyte liquid mixtures---V. Viscosity coefficients for binary mixtures of benzene plus alkanes at saturation pressure from 283 to 393 K

    Microsoft Academic Search

    J. H. Dymond; K. J. Young

    1981-01-01

    Viscosity coefficient measurements at saturation pressure are reported for benzene + n-hexane, benzene + n-octane, benzene + n-decane, benzene + n-dodecane, benzene + n-hexadecane, and benzene + cyclohexane at temperatures from 283 to 393 K. The characteristic parameter G in the Grunberg and Nissan equation 10765_2004_Article_BF00504187_TeX2GIFE1.gif ell neta = x_1 ell neta _1 + x_2 ell neta _2 + x_1

  6. 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)

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

    1997-01-01

    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.

  7. Chemical transport in silicone rubber membranes from pure powders and saturated aqueous solutions

    Microsoft Academic Search

    Eugene E. Ley; Annette L. Bunge

    2007-01-01

    In this study membrane permeation was measured from finely divided pure powder and saturated aqueous solutions of two test chemicals with low vapor pressure, methyl paraben and 4-cyanophenol, through silicone rubber (polydimethylsiloxane) using diffusion cells operated to insure the concentration was negligible at the interface between the membrane and the receptor solution. The steady-state flux from the pure powder was

  8. Modeling and Real-Time Process Monitoring of Organometallic Chemical Vapor Deposition of III-V Phosphides and Nitrides at Low and High Pressure

    NASA Technical Reports Server (NTRS)

    Bachmann, K. J.; Cardelino, B. H.; Moore, C. E.; Cardelino, C. A.; Sukidi, N.; McCall, S.

    1999-01-01

    The purpose of this paper is to review modeling and real-time monitoring by robust methods of reflectance spectroscopy of organometallic chemical vapor deposition (OMCVD) processes in extreme regimes of pressure. The merits of p-polarized reflectance spectroscopy under the conditions of chemical beam epitaxy (CBE) and of internal transmission spectroscopy and principal angle spectroscopy at high pressure are assessed. In order to extend OMCVD to materials that exhibit large thermal decomposition pressure at their optimum growth temperature we have designed and built a differentially-pressure-controlled (DCP) OMCVD reactor for use at pressures greater than or equal to 6 atm. We also describe a compact hard-shell (CHS) reactor for extending the pressure range to 100 atm. At such very high pressure the decomposition of source vapors occurs in the vapor phase, and is coupled to flow dynamics and transport. Rate constants for homogeneous gas phase reactions can be predicted based on a combination of first principles and semi-empirical calculations. The pressure dependence of unimolecular rate constants is described by RRKM theory, but requires variational and anharmonicity corrections not included in presently available calculations with the exception of ammonia decomposition. Commercial codes that include chemical reactions and transport exist, but do not adequately cover at present the kinetics of heteroepitaxial crystal growth.

  9. Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest.

    PubMed

    Oren, R.; Phillips, N.; Ewers, B. E.; Pataki, D. E.; Megonigal, J. P.

    1999-05-01

    We used 20-mm-long, Granier-type sensors to quantify the effects of tree size, azimuth and radial position in the xylem on the spatial variability in xylem sap flux in 64-year-old trees of Taxodium distichum L. Rich. growing in a flooded forest. This information was used to scale flux to the stand level to investigate variations in half-hourly and daily (24-hour) sums of sap flow, transpiration per unit of leaf area, and stand transpiration in relation to vapor pressure deficit (D) and photosynthetically active radiation (Q(o)). Measurements of xylem sap flux density (J(s)) indicated that: (1) J(s) in small diameter trees was 0.70 of that in medium and large diameter trees, but the relationship between stem diameter as a continuous variable and J(s) was not significant; (2) J(s) at 20-40 mm depth in the xylem was 0.40 of that at 0-20 mm depth; and (3) J(s) on the north side of trees was 0.64 of that in directions 120 degrees from the north. Daily transpiration was linearly related to daily daytime mean D, and reached a modest value of 1.3 mm day(-1), reflecting the low leaf area index (LAI = 2.2) of the stand. Because there was no soil water limitation, half-hourly water uptake was nearly linearly related to D at D < 0.6 kPa during both night and day, increasing to saturation during daytime at higher values of D. The positive effect of Q(o) on J(s) was significant, but relatively minor. Thus, a second-order polynomial with D explained 94% of the variation in J(s) and transpiration. An approximately 40% reduction in LAI by a hurricane resulted in decreases of about 18% in J(s) and stand transpiration, indicating partial stomatal compensation. PMID:12651555

  10. The influence of water vapor content on electrical and spectral properties of an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Nikiforov, A. Yu; Sarani, A.; Leys, Ch

    2011-02-01

    An atmospheric pressure plasma jet generated in Ar with water vapor is investigated. It is shown that an increase in the water content results in a decrease in the input power and asymmetry of the current waveform on positive and negative half-periods of the applied voltage. Space-resolved spectroscopy with a resolution of 1 mm and an imaging technique are applied for the characterization of the afterglow and investigation of the influence of water content on plasma properties. The rotational temperature of the jet is determined by simulation of the OH radical emission spectrum, transition A 2?+(v = 0) ? X 2?(v = 0). It is revealed that the temperature of the discharge increases from 450 K (Ar) up to 850 K with an increase in the water content up to 7600 ppm. Generation of the discharge in mixtures of argon with water vapor at a concentration of 350 ppm results in a maximal yield of OH radicals that can be useful in plasma jet applications. Preliminary tests of polypropylene surface modification are carried out in order to estimate the influence of water content on the results of treatment.

  11. Modeling of hydrogen-based plasmas in microwave plasma-assisted chemical vapor deposition reactors at moderate pressures

    NASA Astrophysics Data System (ADS)

    Meierbachtol, Collin Stephen

    Microwave Plasma-Assisted Chemical Vapor Deposition (MPACVD) systems are used in the deposition of high quality diamond films. These systems have traditionally been operated at less than 20% atmospheric pressure (atm), resulting in growth rates up to 5 mum/hr. Under such conditions, the system operation and plasma behavior are well-understood and have been successfully modeled. Recent experiments at pressures approaching 40% atm have demonstrated faster growth rates and better quality samples. At these increased pressures, the system operation and plasma behavior are not completely understood, with unusual plasma behavior sometimes observed. Experimental measurements within these systems can be difficult, making numerical models attractive for aiding in understanding this behavior. This thesis presents a self-consistent multiphysics numerical model of MPACVD systems, which is accurate under these operating conditions. Electromagnetic field propagation, chemical reactions, species diffusion, thermal processes, energy transfer, and convective flows are all included in the multiphysics model. The model is verified against canonical problems and validated against experimental data. Extensive numerical results are provided for different operating conditions and system configurations.

  12. MESOSCOPIC SCALE MODELING FOR CHEMICAL VAPOR DEPOSITION

    E-print Network

    Ringhofer, Christian

    MESOSCOPIC SCALE MODELING FOR CHEMICAL VAPOR DEPOSITION IN SEMICONDUCTOR MANUFACTURING MATTHIAS K. GOBBERT \\Lambda AND CHRISTIAN RINGHOFER y Abstract. Low pressure chemical vapor deposition is a process, homogenization, multiscale modeling, chemical vapor deposition. 1. Introduction. Chemical vapor deposition (CVD

  13. Melting and crystallization behavior of low-pressure chemical-vapor-deposition amorphous Si films during excimer-laser annealing

    NASA Astrophysics Data System (ADS)

    Voogt, F. C.; Ishihara, R.; Tichelaar, F. D.

    2004-03-01

    Results are presented of cross-sectional transmission-electron microscopy and time-resolved optical reflectivity investigations into the excimer-laser annealing of low-pressure chemical-vapor-deposition amorphous Si films. It is found that, in the initial stages of the laser pulse, a thin surface layer melts. This is directly followed by explosive crystallization of the film into to small, columnar, and defect-rich grains. As more laser energy is consumed, the Si film melts in from the surface for a second time, eventually leading to complete melting of the film. It is argued that melting along grain boundaries and defects is a crucial step in obtaining large, single-crystalline grains in the super-lateral growth regime.

  14. {ital Ex situ} ellipsometry characterization of excimer laser annealed amorphous silicon thin films grown by low pressure chemical vapor deposition

    SciTech Connect

    Kuo, C.; Hsieh, I.; Schroder, D.K. [Center for Solid State Electronics Research and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287-6206 (United States)] [Center for Solid State Electronics Research and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287-6206 (United States); Maracas, G.N. [Motorola, Phoenix Corporate Research Laboratory, Tempe, Arizona 85284 (United States)] [Motorola, Phoenix Corporate Research Laboratory, Tempe, Arizona 85284 (United States); Chen, S. [XMR Inc., Fremont, California 94538 (United States)] [XMR Inc., Fremont, California 94538 (United States); Sigmon, T.W. [Lawrence Livermore National Laboratory, L-271, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, L-271, Livermore, California 94551 (United States)

    1997-07-01

    Spectroscopic ellipsometry was used to monitor excimer laser annealed thin ({approximately}100nm) amorphous silicon (a-Si) films grown on quartz substrates by low pressure chemical vapor deposition (LPCVD). The peak position of the imaginary part of the complex dielectric function {epsilon}{sub 2} was used to determine the degree of crystallization of the a-Si. The amplitude of {epsilon}{sub 2} at the Si E{sub 1} transition energy is found to be a good indicator of the polycrystalline silicon (poly-Si) grain size after laser annealing with good correlation between {ital ex situ} ellipsometric data and poly-Si grain sizes being observed. Spectroscopic ellipsometry provides a contactless, nondestructive, and simple technique for monitoring laser annealing both {ital in situ} during the annealing process or {ital ex situ} after annealing. {copyright} {ital 1997 American Institute of Physics.}

  15. Tree ring wood analysis after hydrogen peroxide pressure decomposition with inductively coupled plasma atomic emission spectrometry and electrothermal vaporization

    SciTech Connect

    Matusiewicz, H.; Barnes, R.M.

    1985-02-01

    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.

  16. Growth of selective tungsten films on self-aligned CoSi2 by low pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    van der Putte, P.; Sadana, D. K.; Broadbent, E. K.; Morgan, A. E.

    1986-12-01

    The selective deposition of tungsten films onto CoSi2 and onto Co by low pressure chemical vapor deposition and their material properties have been investigated with Auger electron spectroscopy, transmission electron microscopy, and Rutherford backscattering. When using WF6 and H2, uniformly thick tungsten films can be deposited onto CoSi2 without substrate alteration. In patterned structures, however, void formation was found at the perimeters of CoSi2 contacts to silicon, indicating encroachment of WF6 down the edge of the silicide-Si interface. In WF6 and Ar, the film thickness was limited to 10 nm and some Si was locally consumed from the upper part of the CoSi2 film. Transmission electron diffraction showed evidence of Co2Si formation in these areas.

  17. Vapor-pressure osmometric study of the molecular weight and aggregation tendency of a reference-soil fulvic acid

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.

    1990-01-01

    The molecular weight and aggregation tendency of a reference-soil fulvic acid in Armadale horizon Bh were determined by vapor-pressure osmometry using tetrahydrofuran and water as solvents. With tetrahydrofuran, number-average molecular weight values of 767 ?? 34 and 699 ?? 8 daltons were obtained from two separate sets of measurements. Two sets of measurements with water also yielded values within this range (754 ?? 70 daltons) provided that the fulvic acid concentration in water did not exceed 7 mg ml-1; at higher concentrations (9.1-13.7 mg ml-1) a number-average molecular weight of 956 ?? 25 daltons was resolved, providing evidence of molecular aggregation. Extension of these studies to 80% neutralized fulvic acid showed that a sizeable fraction of the sodium counter ion is not osmotically active.

  18. Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

    PubMed

    Worsnop, D R; Zahniser, M S; Fox, L E; Wofsy, S C

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone. PMID:17757475

  19. Microstructure of Cu(In,Ga)Se2 Films Deposited in Low Se Vapor Pressure

    NASA Astrophysics Data System (ADS)

    Nishiwaki, Shiro; Kohara, Naoki; Negami, Takayuki; Miyake, Hideo; Wada, Takahiro

    1999-05-01

    The microstructure of Cu(In,Ga)Se2 (CIGS) films deposited under low Se flux was studied using scanning electron microscopy, scanning Auger electron spectroscopy and high resolution and analytical electron microscopy. CIGS films were deposited on Mo coated soda-lime glass substrate using the 3-stage process in which the Se flux used during the third stage was restricted to a forth of standard value. In the as-grown CIGS films, voids were observed along the grain boundaries and a Cu2Se phase was identified at the surface and the grain boundaries. The voids and Cu2Se layer were produced by vaporization of an In Se compound from the films during the third stage of deposition. A reaction model on the CIGS grain surface is proposed based on the microstructure observations.

  20. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    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.

  1. Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.

    1996-01-01

    A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.

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

    E-print Network

    Dietz, Nikolaus

    Surface structure, composition, and polarity of indium nitride grown by high-pressure chemical of the surface was observed, N-polarity indium nitride is indicated. © 2006 American Institute of Physics. DOI: 10.1063/1.2187513 Research on the growth and characterization of indium nitride InN has increased

  3. The Mechanism of the Positive Column in Mercury Vapor at Intermediate Pressures

    Microsoft Academic Search

    Elliot Q. Adams; Bentley T. Barnes

    1938-01-01

    Calculations based on the radiant intensity for the principal spectral lines of 4-ampere mercury arcs at 450 mm and 500 mm (Hg) pressure, indicate for low quantum states a dynamic equilibrium with electrons at approximately 6000K, the temperature indicated by the absolute spectral intensity for three reversed lines. For high quantum states differing only in total quantum number, there appears

  4. Influence of Water Vapor on the Cyclic-Oxidation Behavior of a Low-Pressure Plasma-Sprayed NiCrAlY Coating

    Microsoft Academic Search

    Chungen Zhou; Huibin Xu; Shengkai Gong

    2004-01-01

    The oxidation of a low-pressure plasma-sprayed (LPPS) NiCrAlY coating on a nickel-base superalloy was studied at 1050C in flows of O2, and mixture of O2 and 5% H2O under atmospheric pressure. Water vapor has an obvious effect on the cyclic oxidation of the NiCrAlY coating. There is more decrease in weight gain when exposure to O2 is replaced by exposure

  5. STOMATAL SENSITIVITY TO VAPOR PRESSURE DIFFERENCE OVER A SUBAMBIENT TO ELEVATED CO2 GRADIENT IN A C3/C4 GRASSLAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the response of stomatal conductance (gs) to increasing leaf-to-air vapor pressure difference (D) in early season C3 (Bromus japonicus) and late season C4 (Bothriochloa ischaemum) grasses grown in the field across a range of CO2 (200-550 umol mol-1). Stomatal sensitivity to D was calcul...

  6. Seasonal trends in leaf photosynthesis and stomatal conductance of drought stressed and nonstressed pearl millet as associated to vapor pressure deficit

    Microsoft Academic Search

    H. Tewolde; A. K. Dobrenz; R. L. Voigt

    1993-01-01

    Single leaf photosynthesis (Pn) and stomatal conductance (Cg) of drought stressed and nonstressed pearl millet [Pennisetum americanum (L.) Leeke] were measured across growth stages to determine if a pattern exists in Pn and Cg during the growing season and to evaluate the influence of air vapor pressure deficit (VPDa) on the seasonal variations of Pn and Cg. Leaf photosynthesis and

  7. Retardation of nucleation rate for grain size enhancement by deep silicon ion implantation of low-pressure chemical vapor deposited amorphous silicon films

    Microsoft Academic Search

    I.-W. Wu; A. Chiang; M. Fuse; T. Y. Huang

    1989-01-01

    The effects of silicon ion implantation on the crystallization kinetics and grain size of low-pressure chemical vapor deposited amorphous silicon on oxidized silicon substrate have been studied by x-ray diffraction and transmission electron microscopy. The most effective grain size enhancement was achieved by deep silicon ion implantation with the projected range located beyond the bottom interface to allow the maximum

  8. Homoleptic tin and silicon amido compounds as precursors for low-temperature atmospheric pressure chemical vapor deposition of tin and silicon oxide thin films

    Microsoft Academic Search

    Lauren M. Atagi; David M. Hoffman; Jia-Rui Liu; Zongshuang Zheng; Wei-Kan Chu; Rodrigo R. Rubiano; Robert W. Springer; David C. Smith

    1994-01-01

    Tin oxide films doped with fluorine or antimony are transparent conductors used in optoelectronic devices and solar cells. Silicon oxide thin films are used as diffusion barriers, passivation layers and dielectric layers in the microelectronics industry. Tin oxide thin films are commonly deposited in atmospheric pressure chemical vapor deposition (APCVD) processes by hydrolyzing SnCl[sub 4] or by reacting tetramethyltin with

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

    Microsoft Academic Search

    V. Rodriguez; J. Pardo; M. C. Lopez; F. M. Royo; J. S. Urieta

    1993-01-01

    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

  10. Partial Pressures in Equilibrium with Group IV Tellurides. III. Germanium Telluride

    Microsoft Academic Search

    Robert F. Brebrick

    1964-01-01

    The partial pressures of Te2(g) and GeTe(g) over Ge&sngbnd;Te condensed phases between 1 and 52 at. % Te have been determined between 525 and 940C by measuring the optical density of the vapor. Partial optical densities due to each species are calculated and converted to partial pressures by assuming Beer's law and published vapor pressures.Over Te-saturated GeTe(c), pTe2 reaches a

  11. 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

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

    2012-01-01

    Introduction: Nowadays particular emphasis is placed on the developmental aspects of premature infants care. Massage therapy is one of the best-known methods of caring. Due to the minimal touch policy in neonatal intensive care units (NICUs), massaging is not usually performed on premature infants. However, there is not sufficient evidence to support the claim that newborn infants with complex medical conditions should not be massaged. This study aimed to determine the effects of massage with coconut and sunflower oils on oxygen saturation of infants with respiratory distress syndrome (RDS) treated with nasal continuous positive airway pressure (NCPAP). Methods: This was a randomized controlled trial on 90 newborns who were admitted to Alzahra Hospital (Tabriz, Iran). The infants were divided into control and massage therapy groups (massage with coconut and sunflower oils). Data was collected using a hospital documentation form. A 15-minute daily massage was performed for 3 days. Respiratory rate (RR), fraction of inspired oxygen (FiO2) and oxygen saturation were measured 5 minutes before the massage, 3 times during the massage, and 5 minutes after the massage. The collected data was analyzed using a mixed model. Results: In comparison to coconut oil and control groups, mean oxygen saturation of sunflower oil group was improved. In addition, the coconut massage group showed lower oxygen saturation than the control group but was all values were within the normal range. Although massage decreased oxygen saturation, there was no need to increase FiO2. Conclusion: Massage therapy can provide developmental care for infants treated with NCPAP. PMID:25276695

  12. Studies of air, water, and ethanol vapor atmospheric pressure plasmas for antimicrobial applications.

    PubMed

    Ferrell, James R; Bogovich, Erinn R; Lee, Nicholas R; Gray, Robert L; Pappas, Daphne D

    2015-01-01

    The generation of air-based plasmas under atmospheric plasma conditions was studied to assess their antimicrobial efficacy against commonly found pathogenic bacteria. The mixture of initial gases supplied to the plasma was found to be critical for the formation of bactericidal actives. The optimal gas ratio for bactericidal effect was determined to be 99% nitrogen and 1% oxygen, which led to a 99.999% reduction of a pathogenic strain of Escherichia coli on stainless steel surfaces. The experimental substrate, soil load on the substrate, flow rate of the gases, and addition of ethanol vapor all were found to affect antimicrobial efficacy of studied plasmas. Optical emission spectroscopy was used to identify the species that were present in the plasma bulk phase for multiple concentrations of nitrogen and oxygen ratios. The collected spectra indicate a unique series of bands present in the ultraviolet region of the electromagnetic spectrum that can be attributed to nitric oxide species known to be highly antimicrobial. This intense spectral profile dramatically changes as the concentration of nitrogen decreases. PMID:25810273

  13. Thermodynamic and transport properties of sodium liquid and vapor

    SciTech Connect

    Fink, J.K.; Leibowitz, L.

    1995-01-01

    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.

  14. Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries

    NASA Astrophysics Data System (ADS)

    Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

    2014-12-01

    The ?-? interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance.

  15. Synthesis of ordered mesoporous phenanthrenequinone-carbon via ?-? interaction-dependent vapor pressure for rechargeable batteries.

    PubMed

    Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

    2014-01-01

    The ?-? interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance. PMID:25490893

  16. Capillary Pressure-Saturation Relations for Supercritical CO2 and Brine in Limestone/Dolomite Sands: Implications for Geologic Carbon Sequestration in Carbonate Reservoirs.

    PubMed

    Wang, Shibo; Tokunaga, Tetsu K

    2015-06-16

    In geologic carbon sequestration, capillary pressure (Pc)-saturation (Sw) relations are needed to predict reservoir processes. Capillarity and its hysteresis have been extensively studied in oil-water and gas-water systems, but few measurements have been reported for supercritical (sc) CO2-water. Here, Pc-Sw relations of scCO2 displacing brine (drainage), and brine rewetting (imbibition) were studied to understand CO2 transport and trapping behavior under reservoir conditions. Hysteretic drainage and imbibition Pc-Sw curves were measured in limestone sands at 45 C under elevated pressures (8.5 and 12.0 MPa) for scCO2-brine, and in limestone and dolomite sands at 23 C (0.1 MPa) for air-brine using a new computer programmed porous plate apparatus. scCO2-brine drainage and imbibition curves shifted to lower Pc relative to predictions based on interfacial tension, and therefore deviated from capillary scaling predictions for hydrophilic interactions. Fitting universal scaled drainage and imbibition curves show that wettability alteration resulted from scCO2 exposure over the course of months-long experiments. Residual trapping of the nonwetting phases was determined at Pc = 0 during imbibition. Amounts of trapped scCO2 were significantly larger than for those for air, and increased with pressure (depth), initial scCO2 saturation, and time. These results have important implications for scCO2 distribution, trapping, and leakage potential. PMID:25945400

  17. Calibrated vapor generator source

    SciTech Connect

    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

    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.

  18. Measurement and prediction of the relationship between capillary pressure, saturation, and interfacial area in a NAPL-water-glass bead system

    NASA Astrophysics Data System (ADS)

    Porter, Mark L.; Wildenschild, Dorthe; Grant, Gavin; Gerhard, Jason I.

    2010-08-01

    In this work, the constitutive relationship between capillary pressure (Pc), saturation (Sw), and fluid-fluid interfacial area per volume (IFA) is characterized using computed microtomography for drainage and imbibition experiments consisting of a nonaqueous phase liquid and water. The experimentally measured relationship was compared to a thermodynamic model that relates the area under the Pc - Sw curve to the total IFA, an, and the capillary-associated IFA, anw. Surfaces were fit to the experimental and modeled Pc - Sw - an and Pc - Sw - anw data in order to characterize the relationship in three dimensions (3D). For the experimental system, it was shown that the Pc - Sw - an relationship does not exhibit hysteresis. The model is found to provide a reasonable approximation of the magnitude of the 3D surfaces for an and anw, with a mean absolute percent error of 26% and 15%, respectively. The relatively high mean absolute percent errors are primarily the result of discrepancies observed at the wetting- and nonwetting-phase residual saturation values. Differences in the shapes of the surfaces are noted, particularly in the curvature (arising from the addition of scanning curves and presence of an - Sw hysteresis in the predicted results) and endpoints (particularly the inherent nature of thermodynamic models to predict significant anw associated with residual nonwetting-phase saturation). Overall, the thermodynamic model is shown to be a practical, inexpensive tool for predicting the Pc - Sw - an and Pc - Sw - anw surfaces from Pc - Sw data.

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

    PubMed

    Emery, R. J. Neil; Salon, Christophe

    2002-07-01

    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

  20. Prediction of subcooled vapor pressures (log PL) of 399 polychlorinated trans-azoxybenzenes by using the QSPR and ANN approach.

    PubMed

    Piliszek, S?awomir; Wilczy?ska-Piliszek, Agata J; Falandysz, Jerzy

    2012-01-01

    Environmentally relevant partitioning properties such as the sub-cooled vapor pressures (log PL) have been predicted for 399 congeners of chloro-trans-azoxybenzene (C-t-AOBs) by two computational methods. The quantitative structure-property relationship (QSPR), an approach which is based on geometry optimalization and quantum-chemical structural descriptors in RM1 and DFT methods and artificial neural networks (ANNs), an approach that predicts abilities that give similar results of estimated log P(L) and the accuracy of the methods was also similar. The RM1 method was less time consuming and less costly compared to calculations by the DFT method. Estimated from the RM1 and DFT methods of log P(L) values of 399 Ct-AOBs varied between -1.98 to -0.93 and -1.83 to -0.79 for Mono-, 3.12 to -1.46 and -3.00 to -1.46 for Di-, -4.03 to -1.39 and -3.53 to -1.67 for Tri-, -4.75 to -2.33 and -4.59 to -1.91 for Tetra-, -5.37 to -2.59 and -5.42 to -2.09 for Penta-, -5.82 to -2.88 and -5.66 to -2.58 for Hexa-, -5.88 to -3.24 and -5.60 to -2.93 for Hepta-, -6.28 to -4.33 and -5.60 to -4.29 for Octa-, -6.54 to -5.28 and -5.66 to -4.93 for NonaCt-AOBs, and -6.59 and -5.61 for DecaCt-AOB. According to a common classification of environmental contaminants and by sub-cooled vapor pressure values, MonoCt-AOBs and a few of the Di- and TriCt-AOBs (log P(L)from -2 to 0) fall into the group of compounds that are relatively well mobile in the ambient environment, while most of the Di- to HeptaCt-AOBs (log P(L) < -4 to -2) mobility is relatively weak. Octa- and NonaCt-AOBs and DecaCt-AOB (log P(L) < -4) are also weak mobile contaminants. PMID:22320698

  1. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations

    SciTech Connect

    Vold, E.L.

    1997-03-01

    There is evidence for migration of tritiated water vapor through the tuff in the unsaturated zone from the buried disposal shafts located on a narrow mesa top at Area G, Los Alamos, NM. Field data are consistent with an effective in-situ vapor phase diffusion coefficient of 1.5x10{sup {minus}3} m{sup s}/s, or a factor of 60 greater than the binary diffusion coefficient for water vapor in air. A model is derived to explain this observation of anomolously large diffusion, which relates an effective vapor or gas phase diffusion coefficient in the fractured porous media to the subsurface propagation of atmospheric pressure fluctuations (barometric pumping). The near surface (unattenuated) diffusion coefficient is independent of mode period under the simplified assumptions of a complete {open_quote}mixing mechanism{close_quote} for the effective diffusion process. The unattenuated effective diffusion driven by this barometric pumping is proportional to an average media permeability times the sum of the square of pressure mode amplitudes, while the attenuation length is proportional to the squarer root of the product of permeability times mode period. There is evidence that the permeability needed to evaluate the pressure attenuation length is the in-situ value, approximately that of the matrix. The diffusion which results using Area G parameter values is negligible in the matrix but becomes large at the effective permeability of the fractured tuff matrix. The effective diffusion coefficient predicted by this model, due to pressure fluctuations and the observed fracture characteristics, is in good agreement with the observed in-situ diffusion coefficient for tritium field measurements. It is concluded that barometric pumping in combination with the enhanced permeability of the fractured media is a likely candidate to account for the observed in-field migration of vapor in the near surface unsaturated zone at Area G.

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

    E-print Network

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

    of snowmelt over mountainous basins where the temperatures range considerably with elevation. Additionally, information on atmospheric pressure in millibars for selected heights was obtained. Thermodynamic considerations in the computational scheme...

  3. Dependence of Waterflood Remaining Oil Saturation on Relative Permeability, Capillary Pressure, and Reservoir Parameters in Mixed-Wet Turbidite Sands

    Microsoft Academic Search

    G. J. Hirasaki

    1996-01-01

    The dependence of waterflood oil recovery on relative permeability, capillary pressure, and reservoir parameters was investigated by numerical simulation. The relative permeability and capillary pressure curves were based on laboratory measurements on unconsolidated sands. The water-wet case is based on the assumption that the system is water-wet and measurements were made with refined oil. The mixed-wet case assumed that the

  4. Step-coverage simulation for tetraethoxysilane and ozone atmospheric pressure chemical vapor deposition

    SciTech Connect

    Fujino, K. (Semiconductor Process Lab., Toyko (Japan)); Egashira, Y.; Shimogaki, Y.; Komiyama, H. (Univ. of Tokyo, (Japan). Dept. of Chemical Engineering)

    1993-08-01

    A simulation model for atmospheric pressure (AP) CVD has bee developed using one-dimensional diffusion and mass conservation equations. The model was applied to trench step-coverage of the tetraethoxysilane (TEOS) and O[sub 3] CVD, in which it was not necessary to consider lateral diffusion because of narrow (and deep) trenches. For nondoped silicate glass (NSG), the step-coverage of a 4.5 aspect ratio trench showed a good fit if a sticking probability of 0.0039 was assumed for the 0.6% ozone (in oxygen) deposition and of 0.0026 for the 6% ozone deposition (both 400 C). The reaction rate constant was compared with the diffusion mass-transfer coefficient, and the reaction proved to be limited by diffusion of the reactant, TEOS, which directly participated in the CVD reaction. For the 2 m/o phosphosilicate glass (PSG) step-coverage, which had a slight overhang, the model matched the obtained results well only when an active growth species with a high sticking probability of 1.0 was added to the growth species of nondoped oxide. This analytical simulation method satisfactorily explains the experimental data.

  5. Deposition mechanisms and profile modeling of SiO2 films deposited by low-pressure chemical vapor deposition

    SciTech Connect

    Cheng, Lie-Yea.

    1991-01-01

    This research describes a new test structure that successfully separates the mechanisms controlling step coverage of low pressure chemical vapor deposition (LPCVD) SiO2 surface diffusion and re-emission due to a low reactive sticking coefficient of the reactive species. The new test structure has overhangs above a cavity which isolate most of the cavity from gas phase direct flux. Deposition in the shadowed area occurs either through surface diffusion or re-emission of species originating in the non-shadowed area. Variation in the geometry of the test structure allows us to determine the dominant mechanism. The results show that re-emission, not surface diffusion, is the dominant step coverage controlling mechanism for LPCVD SiO2 films deposited with oxygen and any one of four silicon sources: silane, diethylsilane (DES), tetraethoxysilane (TEOS) and 1,3,5,7 tetramethylcyclotetrasiloxane (TMCTS). This research also describes a Monte Carlo LPCVD profile simulator (part of SPEEDIE, Stanford Profile Emulator for Etching and Deposition in IC Engineering) which determines the relative importance of these two mechanisms and extracts surface diffusion lengths, L(sub d), and reactive sticking coefficients, S(sub c). The results show that only the reactive sticking coefficient is required to accurately simulate the deposition profiles on test structures with different cavity heights and trenches with different aspect ratios. The values of S(sub c) differ for each silicon source. The more conformal films deposited with TEOS/oxygen or TMCTS/oxygen sources have lower sticking coefficients than the less conformal films deposited with silane/oxygen and DES/oxygen sources. This research also includes a study of the effects of temperature and pressure on S(sub c) and hence, step coverage. Temperature can improve or degrade step coverage depending upon the specifics of the surface reaction.

  6. Stomatal Responses to Light and Leaf-Air Water Vapor Pressure Difference Show Similar Kinetics in Sugarcane and Soybean 1

    PubMed Central

    Grantz, David A.; Zeiger, Eduardo

    1986-01-01

    Stomatal responses to light and humidity (vapor pressure difference, VPD) are important determinants of stomatal conductance. Stomatal movements induced by light are the result of a transduction of the light stimulus into modulated ion fluxes in guard cells and concomitant osmotic adjustments and turgor changes. It is generally assumed that this transduction process is a general stomatal property, with different environmental stimuli integrated into guard cell metabolism through their modulation of ion fluxes. In contrast with this notion, the VPD response, which is unique because both its triggering signal and the turgor changes required for aperture modulations involve water molecules, has been considered to be hydropassive and thus independent of guard cell metabolism. We used a kinetic approach to compare the light and VPD responses in order to test the hypothesis that hydropassive changes in guard cell turgor could be faster than the metabolism-dependent light responses. Changes in stomatal conductance in intact leaves of sugarcane and soybean were measured after application of step changes in VPD and in light. In spite of a 5-fold difference in overall rates between the two species, the response rates following light or VPD steps were similar. Although a coincidental kinetic similarity between two mechanistically different responses cannot be ruled out, the data suggest a common mechanism controlling stomatal movements, with the VPD stimulus inducing metabolic modulations of ion fluxes analogous to other stomatal responses. PMID:16664916

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

    SciTech Connect

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

    2009-08-01

    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. HIPd 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.

  8. High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

    Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

  9. Pre-conditioning the epigenetic response to high vapor pressure deficit increases the drought tolerance of Arabidopsis thaliana

    PubMed Central

    Tricker, Penny J; Rodrguez Lpez, Carlos M; Hadley, P; Wagstaff, C; Wilkinson, Mike J

    2013-01-01

    Epigenetic modification of the genome via cytosine methylation is a dynamic process that responds to changes in the growing environment. This modification can also be heritable. The combination of both properties means that there is the potential for the life experiences of the parental generation to modify the methylation profiles of their offspring and so potentially to pre-condition them to better accommodate abiotic conditions encountered by their parents. We recently identified high vapor pressure deficit (vpd)-induced DNA methylation at 2 gene loci in the stomatal development pathway and an associated reduction in leaf stomatal frequency.1 Here, we test whether this epigenetic modification pre-conditioned parents and their offspring to the more severe water stress of periodic drought. We found that 3 generations of high vpd-grown plants were better able to withstand periodic drought stress over 2 generations. This resistance was not directly associated with de novo methylation of the target stomata genes, but was associated with the cmt3 mutants inability to maintain asymmetric sequence context methylation. If our finding applies widely, it could have significant implications for evolutionary biology and breeding for stressful environments. PMID:24270688

  10. Pre-conditioning the epigenetic response to high vapor pressure deficit increases the drought tolerance of Arabidopsis thaliana.

    PubMed

    Tricker, Penny; Rodrguez Lpez, Carlos; Hadley, Paul; Wagstaff, Carol; Wilkinson, Mike

    2013-10-01

    Epigenetic modification of the genome via cytosine methylation is a dynamic process that responds to changes in the growing environment. This modification can also be heritable. The combination of both properties means that there is the potential for the life experiences of the parental generation to modify the methylation profiles of their offspring and so potentially to "pre-condition" them to better accommodate abiotic conditions encountered by their parents. We recently identified high vapor pressure deficit (vpd)-induced DNA methylation at 2 gene loci in the stomatal development pathway and an associated reduction in leaf stomatal frequency. (1) Here, we test whether this epigenetic modification pre-conditioned parents and their offspring to the more severe water stress of periodic drought. We found that 3 generations of high vpd-grown plants were better able to withstand periodic drought stress over 2 generations. This resistance was not directly associated with de novo methylation of the target stomata genes, but was associated with the cmt3 mutant's inability to maintain asymmetric sequence context methylation. If our finding applies widely, it could have significant implications for evolutionary biology and breeding for stressful environments. PMID:24270688

  11. Properties of low-pressure chemical vapor epitaxial GaN films grown using hydrazoic acid (HN{sub 3})

    SciTech Connect

    Chtchekine, D.G.; Fu, L.P.; Gilliland, G.D.; Chen, Y.; Ralph, S.E.; Bajaj, K.K. [Physics Department, Emory University, Atlanta, Georgia 30322 (United States)] [Physics Department, Emory University, Atlanta, Georgia 30322 (United States); Bu, Y.; Lin, M.C.; Bacalzo, F.T. [Chemistry Department, Emory University, Atlanta, Georgia 30322 (United States)] [Chemistry Department, Emory University, Atlanta, Georgia 30322 (United States); Stock, S.R. [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30322 (United States)] [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30322 (United States)

    1997-03-01

    We have grown high-quality GaN films on sapphire using a new nitrogen precursor, hydrazoic acid (HN{sub 3}). Films were grown at 600{degree}C on (0001) sapphire substrates in a low-pressure chemical-vapor-deposition system using triethylgallium and hydrazoic acid as precursors. Subsequently, we have conducted a complete study of the surface, structural, electrical, and optical properties of these GaN films, and our early results are very encouraging. All films were of wurtzite crystal structure, slightly polycrystalline, and {ital n} type at about 2{times}10{sup 17} cm{sup {minus}3}. We find the films to be efficient light emitters in the near-band edge region of the spectrum. Analysis of the emission energies and kinetics suggests that the midgap emission results from a superimposed deep-donor-to-shallow-acceptor emission and a deep-donor-to-valence-band emission, where the deep donor consists of a distribution of energy levels, thereby yielding a broad emission band. {copyright} {ital 1997 American Institute of Physics.}

  12. In Situ Measurement, Characterization, and Modeling of Two-Phase Pressure Drop Incorporating Local Water Saturation in PEMFC Gas Channels

    NASA Astrophysics Data System (ADS)

    See, Evan J.

    Proton Exchange Membrane Fuel Cells (PEMFCs) have been an area of focus as an alternative for internal combustion engines in the transportation sector. Water and thermal management techniques remain as one of the key roadblocks in PEMFC development. The ability to model two-phase flow and pressure drop in PEMFCs is of significant importance to the performance and optimization of PEMFCs. This work provides a perspective on the numerous factors that affect the two-phase flow in the gas channels and presents a comprehensive pressure drop model through an extensive in situ fuel cell investigation. The study focused on low current density and low temperature operation of the cell, as these conditions present the most challenging scenario for water transport in the PEMFC reactant channels. Tests were conducted using two PEMFCs that were representative of the actual full scale commercial automotive geometry. The design of the flow fields allowed visual access to both cathode and anode sides for correlating the visual observations to the two-phase flow patterns and pressure drop. A total of 198 tests were conducted varying gas diffusion layer (GDL), inlet humidity, current density, and stoichiometry; this generated over 1500 average pressure drop measurements to develop and validate two-phase models. A two-phase 1+1 D modeling scheme is proposed that incorporates an elemental approach and control volume analysis to provide a comprehensive methodology and correlation for predicting two-phase pressure drop in PEMFC conditions. Key considerations, such as condensation within the channel, consumption of reactant gases, water transport across the membrane, and thermal gradients within the fuel cell, are reviewed and their relative importance illustrated. The modeling scheme is shown to predict channel pressure drop with a mean error of 10% over the full range of conditions and with a mean error of 5% for the primary conditions of interest. The model provides a unique and comprehensive basis for developing a fundamental adiabatic two-phase flow pressure drop predictive scheme for PEMFC reactant channels.

  13. Gas exchange rates at different vapor pressure deficits and water relations of Pera sweet orange plants with citrus variegated chlorosis (CVC)

    Microsoft Academic Search

    Gustavo Habermann; Eduardo Caruso Machado; Joo Domingos Rodrigues; Camilo Lzaro Medina

    2003-01-01

    Net photosynthesis (A) and transpiration rates (E), stomatal conductance (g), water use efficiency (WUE), intrinsic water use efficiency (IWUE) and internal leaf CO2 concentration (Ci) in response to different vapor pressure deficit (1.2 and 2.5kPa) were investigated in Pera sweet orange plants affected by citrus variegated chlorosis (CVC), a disease caused by Xylella fastidiosa. All plants were well watered and

  14. lambda=2537 line from a low-pressure mercury discharge lamp emission profile and line absorption by a gas containing a mercury vapor

    Microsoft Academic Search

    Y. Nishimura; T. Fujimoto

    1985-01-01

    By measuring the emission-line intensity of Hg i lambda=2537 (63 P-->61 S) from a low-pressure mercurcury lamp, we have determined the dependence of the upper-level population on the discharge current and the mercury vapor density. From the radial profile of the intensity the spatial distribution function of the population has been determined to be the zero-th order decay mode

  15. Embedding of reduced pressure-chemical vapor deposition grown Ge nanocrystals in a high quality SiO 2 matrix for non-volatile memory applications

    Microsoft Academic Search

    L. Masarotto; K. Yckache; A. Fanton; F. Aussenac; F. Fillot

    2010-01-01

    We have obtained thanks to reduced pressure-chemical vapor deposition germanium nanocrystals in a high quality SiO2 matrix. A perfect control of (i) the tunnel and control oxide layer thicknesses and (ii) the germanium nanocrystals' density and diameter has been achieved. Scanning electron microscopy was used to (i) determine the nucleation and growth rate of the germanium nanocrystals and (ii) evaluate

  16. Single crystal growth of Cu(Ga,In)Se 2 solid solutions by horizontal Bridgman method with controlling Se vapor pressure and their defect properties

    Microsoft Academic Search

    Hiroaki Matsushita; Koji Mitake; Takeo Takizawa

    2005-01-01

    The analysis of chemical reactions shows that In-rich Cu(Ga,In)Se2 bulk crystals can be grown using the horizontal Bridgman method from melts. We have grown the In-rich solid solutions using the above-mentioned method with controlling Se vapor pressure from 20 to 500Torr, based on temperature dependence of the Cu(Ga,In)Se2 phase diagram. These products are shown to have a single chalcopyrite phase

  17. Photosynthesis is limited at high leaf to air vapor pressure deficit in a mutant of Arabidopsis thaliana that lacks trienoic fatty acids

    Microsoft Academic Search

    Mary E. Poulson; Gerald E. Edwards; John Browse

    2002-01-01

    We have investigated the role of polyunsaturated fatty acids in photosynthesis using a triple mutant of Arabidopsis thaliana that lacks trienoic fatty acids (fad 3-2 fad 7-2 fad 8). Though this mutant is male sterile, vegetative growth and development under normal conditions are largely unaffected (McConn and Browse, 1996 Plant Cell 8: 403- 416). At 0.2-1.0 kPa vapor pressure deficit

  18. Preparation of Cu 2O films on MgO (1 1 0) substrate by means of halide chemical vapor deposition under atmospheric pressure

    Microsoft Academic Search

    Hiroki Kobayashi; Takato Nakamura; Naoyuki Takahashi

    2007-01-01

    High-quality Cu2O thin films were grown epitaxially on MgO (110) substrate by halide chemical vapor deposition under atmospheric pressure (AP-HCVD). The full width at half maximum of X-ray diffraction ? rocking measurement of the (220) plane was 0.1429 and that the of the (1?10) plane was 0.303.This result showed that the Cu2O films have a high degree of out-of-plane and

  19. Growth of the AlN nano-pillar crystal films by means of a halide chemical vapor deposition under atmospheric pressure

    Microsoft Academic Search

    Masayuki Yoshioka; Naoyuki Takahashi; Takato Nakamura

    2004-01-01

    Preparation of AlN thin film has been examined by halide chemical vapor deposition technique using AlI3 and NH3 as starting materials under atmospheric pressure (AP-HCVD). The structural analysis of the deposited AlN films prepared on a Si(100) substrate by the AP-HCVD technique were carried out by the X-ray pole figure analysis. They consist of the hexagonal AlN nano-pillar crystals. It

  20. Electrical characterization of rapid thermal nitrided and re-oxidized low-pressure chemical-vapor-deposited silicon dioxide metaloxidesilicon structures

    Microsoft Academic Search

    S. S. Ang; Y. J. Shi; W. D. Brown

    1996-01-01

    The electrical characteristics of rapid thermal nitrided and re-oxidized low-pressure chemical-vapor-deposited (LPCVD) silicon dioxide metaloxidesilicon (MOS) structures were investigated. Both nitridation temperature and time affect the properties of the MOS structures as revealed by capacitancevoltage characteristics. Nitridation at 1000 C for 15 s followed by re-oxidation for 60 s at 1000 C in an oxygen\\/nitrogen ambient was found to be

  1. Mobility behaviour of n-channel and p-channel MOSFETs with oxynitride gate dielectrics formed by low-pressure rapid thermal chemical vapor deposition

    Microsoft Academic Search

    Eric M. Vogel; Winford L. Hill; Veena Misra; Peter K. McLarty; Jimmie J. Wortman; J. R. Hauser; P. Morfouli; GCrard Ghibaudo; T. Ouisse

    1996-01-01

    The electric field dependence of electron and hole mobility was investigated in n-channel and p-channel metal-oxide-semiconductor field-effect transistors with oxynitride gate dielectrics formed using low-pressure rapid thermal chemical vapor deposition with SiH4, N2O and NH3 as the reactive gases. The peak electron mobility was observed to decrease with increasing nitrogen and hydrogen concentration whereas the high-field mobility degradation was improved.

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

    Microsoft Academic Search

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

    2008-01-01

    Accurate thermo-physical data are of utmost interest for the development of new efficient refrigeration systems. Carbon dioxide (R744) and 1,1-difluoroethane (R152a) are addressed here. Isothermal (vapor+liquid) equilibrium data are reported herein for (R744+R152a) binary system in the (258343) K temperature range and in the (0.14 to 7.65) MPa pressure range. A reliable static-analytic method taking advantage of two online ROLSI

  3. Note: Implementation of a cold spot setup for controlled variation of vapor pressures and its application to an InBr containing discharge lamp

    NASA Astrophysics Data System (ADS)

    Briefi, S.

    2013-02-01

    In order to allow for a systematic investigation of the plasma properties of discharges containing indium halides, which are proposed as an efficient alternative for mercury based low pressure discharge lamps, a controlled variation of the indium halide density is mandatory. This can be achieved by applying a newly designed setup in which a well-defined cold spot location is implemented and the cold spot temperature can be adjusted between 50 and 350 C without influencing the gas temperature. The performance of the setup has been proved by comparing the calculated evaporated InBr density (using the vapor pressure curve) with the one measured via white light absorption spectroscopy.

  4. Note: implementation of a cold spot setup for controlled variation of vapor pressures and its application to an InBr containing discharge lamp.

    PubMed

    Briefi, S

    2013-02-01

    In order to allow for a systematic investigation of the plasma properties of discharges containing indium halides, which are proposed as an efficient alternative for mercury based low pressure discharge lamps, a controlled variation of the indium halide density is mandatory. This can be achieved by applying a newly designed setup in which a well-defined cold spot location is implemented and the cold spot temperature can be adjusted between 50 and 350 C without influencing the gas temperature. The performance of the setup has been proved by comparing the calculated evaporated InBr density (using the vapor pressure curve) with the one measured via white light absorption spectroscopy. PMID:23464268

  5. Variability in Proline-Accumulating Ability of Barley (Hordeum vulgare L.) Cultivars Induced by Vapor Pressure Deficit 1

    PubMed Central

    Naidu, Bodapati P.; Aspinall, Donald; Paleg, Leslie G.

    1992-01-01

    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

  6. Temperature and flow modulation doping of manganese in ZnS electroluminescent films by low pressure metalorganic chemical vapor deposition

    SciTech Connect

    Yu, J.E.; Jones, K.S.; Holloway, P.H. [Univ. of Florida, Gainesville, FL (United States)] [and others

    1994-03-01

    A temperature and flow modulation (TFM) technique has been developed to modulate the manganese doping profile in ZnS phosphor material grown by low-pressure metalorganic chemical vapor deposition for alternating-current thin film electroluminescent devices (TFELDs). In the TFM technique, modulation of both the substrate temperature as well as the flows of metalorganic sources, diethylzinc and tricarbonyl-(methylcyclopentadienyl)-manganese (TCPMn), was used to grow a structure consisting of alternating layers of undoped ZnS at 400{degrees}C and Mn-doped ZnS where Mn being incorporated into the undoped ZnS at 550{degrees}C. X-ray results indicated that MnS. phases were present within the ZnS host crystal matrix for the modulation doped samples, while a Mn{sub x}Zn{sub 1-x}S solid solution was present in the uniformly doped samples. The luminescence efficiency of the TFELDs could be modified by growing the phosphor with dopant (luminescent center) modulation. The TFELDs with a single modulated doping phosphor layer showed lower threshold voltages in the range 70 to 80 V with light emission in the 580 to 587 nm wavelength range. With a twofold increase in the total thickness of the undoped ZnS layer, the brightness and the luminescence efficiency, measured at the threshold voltage plus 40 V, increased by a factor of 20 and 10, respectively. The electroluminescent (EL) characteristics of the phosphors with multiple dopant layers showed higher luminescence efficiency. By using the TFM growth technique, one can engineer the luminescent center distribution in the phosphor layer to improve the EL characteristics. 13 refs., 8 figs., 1 tab.

  7. Multi-scale influence of vapor pressure deficit on fire ignition and spread in boreal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Sedano, F.; Randerson, J. T.

    2014-07-01

    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.

  8. Investigation of vapor film motion regularities at boiling liquids

    NASA Astrophysics Data System (ADS)

    Agaltsov, A.; Zeigarnik, Y. U.

    2013-04-01

    The experimental investigation of the saturated Freon-113 and distilled water film boiling on spheres with different diameters at atmospheric pressure under conditions of free convection is executed. With high-speed video average thickness and cumulative distribution function of vapor film as a function of the angle was measured. It was found that with increasing the angle the average thickness of vapor film can change by different laws depending on diameter of the sphere and the temperature difference. It was found also that the increase in the average vapor film thickness with increasing angle is more connected with the increase of large components of cumulative distribution function. It also noted the presence of quasi-periodic pulsations of the vapor film thickness in the lower part, which eventually largely determine the behavior of the interface at large angles.

  9. The Joule-Thomson effect in cesium vapor

    Microsoft Academic Search

    I. I. Novikov; V. V. Roshchupkin; M. M. Liakhovitskii

    1977-01-01

    The paper reports results of the measurement of the Joule-Thomson coefficient in cesium vapor near the saturation line in the temperature range 768-1234 K and the pressure range of about 0 to 790,000 Pa. The experimental apparatus and technique of measurement are described and attention is given to data reduction procedures. The Joule-Thomson coefficient is studied as a function of

  10. Experimental study of ultracold neutron production in pressurized superfluid helium

    E-print Network

    P. Schmidt-Wellenburg; J. Bossy; E. Farhi; M. Fertl; K. K. H. Leung; A. Rahli; T. Soldner; O. Zimmer

    2015-06-25

    We have investigated experimentally the pressure dependence of the production of ultracold neutrons (UCN) in superfluid helium in the range from saturated vapor pressure to 20bar. A neutron velocity selector allowed the separation of underlying single-phonon and multiphonon pro- cesses by varying the incident cold neutron (CN) wavelength in the range from 3.5 to 10{\\AA}. The predicted pressure dependence of UCN production derived from inelastic neutron scattering data was confirmed for the single-phonon excitation. For multiphonon based UCN production we found no significant dependence on pressure whereas calculations from inelastic neutron scattering data predict an increase of 43(6)% at 20bar relative to saturated vapor pressure. From our data we conclude that applying pressure to superfluid helium does not increase the overall UCN production rate at a typical CN guide.

  11. Experimental study of ultracold neutron production in pressurized superfluid helium

    E-print Network

    Schmidt-Wellenburg, P; Farhi, E; Fertl, M; Leung, K K H; Rahli, A; Soldner, T; Zimmer, O

    2015-01-01

    We have investigated experimentally the pressure dependence of the production of ultracold neutrons (UCN) in superfluid helium in the range from saturated vapor pressure to 20bar. A neutron velocity selector allowed the separation of underlying single-phonon and multiphonon pro- cesses by varying the incident cold neutron (CN) wavelength in the range from 3.5 to 10{\\AA}. The predicted pressure dependence of UCN production derived from inelastic neutron scattering data was confirmed for the single-phonon excitation. For multiphonon based UCN production we found no significant dependence on pressure whereas calculations from inelastic neutron scattering data predict an increase of 43(6)% at 20bar relative to saturated vapor pressure. From our data we conclude that applying pressure to superfluid helium does not increase the overall UCN production rate at a typical CN guide.

  12. Operating a radio-frequency plasma source on water vapor.

    PubMed

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

    2009-08-01

    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

  13. Binary vapor-liquid equilibrium data without measurement of composition

    E-print Network

    Nehzat, Mohammad Sadegh

    1975-01-01

    Saturated liquid 2 Saturated vapor 65 APPENDIX D Isochores for Peed Composition of 33. 335 mold n-Butane Zsochore Number 1 Density= 0. 74129 lb mol/ft 3 lemperature (oP) Pressure (psia) 1 Sat. Liq. 2 Sat. Yap. Densit lb mol ft 460. 0 400. 0 340... magnetic densimeter. In this work, Hall and Eubank's method is applied to a carbon dioxide-normal butane mixture, studied by Olds, et al (15). Since the apparatus used by these investigators was not a Burnett-Isochoric apparatus, a simulation program...

  14. Dynamic hydrocarbon separation in high-temperature, high-pressure, liquid n-alkane water vapor systems by steam distillation

    E-print Network

    Vlierboom, Casper-Maarten

    1987-01-01

    32 Rate of 4. 00 cc/min. , 345 'F and 126 psia 33 14. Effect of Rate on a n-Hexane, n-Heptane, n-Octane Ternary System at Saturated Steam Conditions of 345 'F and 126 psia 35 15. Comparison of Multi-component Yield to Pure n-Heptane Yield at 2...-Hexane Distribution for a n-Hexane- n-Heptane - n-Octane Ternary Mixture at Saturated Steam Conditions of 345 0F and 126 psia 77 42. Rate Effect on the n-Heptane Distribution for a n-Hexane- n-Heptane ? n-Octane Ternary Mixture at Saturated Steam Conditions...

  15. 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

    Wada, Takao; Ueda, Noriaki

    2013-01-01

    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

  16. Finite-size thermomechanical effects in smectic liquid crystals: The vapor pressure paradox as an anharmonic phenomenon.

    PubMed

    Gao, Lianghui; Golubovi?, Leonardo

    2003-10-01

    We pursue a systematic statistical mechanics study of finite smectic stacks of semiflexible manifolds bounded by interfaces under tension. We address, by analytic calculations and Monte Carlo simulations, the effects of the surface tension on smectic interlayer distances. We use our theoretical results to elucidate the so called vapor pressure paradox (VPP) in multilamellar membrane phases and explain the experiments of Katsaras [Biophys. J. 73, 2924 (1997); 75, 2157 (1998)]. We show that the effects of the interfacial tension are substantially weaker than suggested by the previous theoretical discussion of the VPP effects [R. Podgornik and V. A. Parsegian, Biophys. J. 72, 942 (1997)]. By consistently taking into account the discrete, layered character of smectic liquid crystals, and anharmonic phonon effects, we show that the essence of VPP effects is in spatially nonuniform thermal expansion of smectic interlayer separations. We find that the average period of the whole finite stack can be both smaller (ordinary VPP effect at high enough interfacial tensions) or bigger (a reverse VPP effect at low interfacial tensions, overlooked in previous studies), relative to the average period of the corresponding infinite smectic stack. Looking at stacks from outside, these two effects show up as if there is an attractive (for the ordinary VPP effect), or repulsive (for the reverse VPP effect) pseudo-Casimir force acting between the two stack interfaces. We show however that the physics of VPP effects is obscured by schematically invoking Casimir-like forces. Rather, the ordinary and the reverse VPP effects are to be both characterized as thermomechanical anharmonic effects caused by a spatially nonuniform thermal expansion of smectic interlayer distances. Interlayer distances close to stack surfaces expand less (more) for the ordinary (reverse) VPP effect than those deep in the stack. The reverse VPP prevails at low interfacial tensions, simply because the membrane at the top of the stack is more free to fluctuate than membranes in the bulk. By increasing interfacial tension above a threshold value, fluctuations of the membrane at the stack top become suppressed, and the ordinary VPP effect prevails. In this study, we demonstrate that finite-size VPP effects in a strongly entropic system, such as the sterically stabilized lamellar phases, can be described quantitatively well by a simple analytic approach. PMID:14682973

  17. 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)

    Erickson, Gary E.

    2010-01-01

    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).

  18. 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)

    Erickson, Gary E.

    2008-01-01

    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).

  19. Transport Properties of CrO2 (100) Film Grown on TiO2 by a Simple Atmosphere Pressure Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Xie, Liang; Zhang, Jin Zhi; Cui, Nai Yi; Zhang, Hong Guang

    2014-06-01

    Epitaxial CrO2 (100)-oriented film was successfully fabricated on TiO2 (100) substrate by a simple chemical vapor deposition in a two-zone furnace with oxygen flow from a CrO3 precursor. The transport measurements show that the CrO2 film is metallic with a small residual resistivity 4 ?? cm down to 0.6 K. The temperature dependence of resistivity was best described by a phenomenological expression ?(T) = ?0 + AT2exp(-?/T) over the range of 0.6-300 K with ? = 123.6 K. The magnetization of the film becomes saturated in a relatively low field with a small coercive field. The temperature dependence of magnetization shows Bloch's T3/2 law and the slope of the curve suggests a critical wavelength of ?? 26.6 beyond which spin-flip scattering becomes important.

  20. Capillary pressure - saturation relations for supercritical CO2 and brine: Implications for capillary/residual trapping in carbonate reservoirs during geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Wang, S.; Tokunaga, T. K.

    2014-12-01

    In geologic carbon sequestration (GCS), data on capillary pressure (Pc) - saturation (Sw) relations are routinely needed to appraise reservoir processes. Capillarity and its hysteresis have been often experimentally studied in oil-water, gas-water and three phase gas-oil-water systems, but fewer works have been reported on scCO2-water under in-situ reservoir conditions. Here, Pc-Sw relations of supercritical (sc) CO2 displacing brine, and brine rewetting the porous medium to trap scCO2 were studied to understand CO2 transport and trapping behavior in carbonate reservoirs under representative reservoir conditions. High-quality drainage and imbibition (and associated capillary pressure hysteresis) curves were measured under elevated temperature and pressure (45 C, 8.5 and 12 MPa) for scCO2-brine as well as at room temperature and pressure (23 C, 0.1 MPa) for air-brine in unconsolidated limestone and dolomite sand columns using newly developed semi-automated multistep outflow-inflow porous plate apparatus. Drainage and imbibition curves for scCO2-brine deviated from the universal scaling curves for hydrophilic interactions (with greater deviation under higher pressure) and shifted to lower Pc than predicted based on interfacial tension (IFT) changes. Augmented scaling incorporating differences in IFT and contact angle improved the scaling results but the scaled curves still did not converge onto the universal curves. Equilibrium residual trapping of the nonwetting phase was determined at Pc =0 during imbibition. The capillary-trapped amounts of scCO2 were significantly larger than for air. It is concluded that the deviations from the universal capillary scaling curves are caused by scCO2-induced wettability alteration, given the fact that pore geometry remained constant and IFT is well constrained. In-situ wettability alteration by reactive scCO2 is of critical importance and must be accounted for to achieve reliable predictions of CO2 behavior in GCS reservoirs.

  1. The vapour pressures of saturated aqueous solutions of sodium chloride, sodium bromide, sodium nitrate, sodium nitrite, potassium iodate, and rubidium chloride at temperatures from 227 K to 323 K

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    1998-01-01

    The vapour pressures of saturated aqueous solutions of NaCl, NaBr, NaNO3, NaNO2, KIO3, and RbCl were determined in the temperature rangeT=(278 to 323) K using an electronic hygrometer with an electrolyte sensor and compared with the literature data, which are available only for the first four salts. These vapour pressures serve to evaluate the water activities, osmotic coefficients, and molar

  2. Preparation of Ferroelectric Bi4Ti3O12 Thin Films with c-Axis Orientation by Atmospheric-Pressure MetalOrganic Chemical Vapor Deposition

    Microsoft Academic Search

    Kuniaki Yoshimura; Minoru Ishinabe; Soichiro Okamura; Takeyo Tsukamoto

    1995-01-01

    Ferroelectric Bi4Ti3O12 thin films were prepared by the metal-organic chemical vapor deposition (MOCVD) method at atmospheric pressure using Bi( o-C7H7)3 and Ti( i-OC3H7)2(DPM)2 as metalorganic sources. Assist Ar gas flow rate effects on the growth of the thin films were also examined. Thin films obtained were characterized by XRD analysis, SEM, AFM and D-E hysteresis loop observations. Most of the

  3. Mass spectroscopic investigation of vapor composition and pressure above Ca/sub 3/Ga/sub 2/Ge/sub 3/O/sub 12/

    SciTech Connect

    Nosenko, A.E.; Kozenchuk, N.M.; Bilyi, A.I.; Kravchishin, V.V.

    1987-01-01

    Mass spectroscopic investigations of the amounts if the volatile components and the vapor pressure above Ca/sub 3/Ga/sub 2/Ge/sub 3/O/sub 12/ were carried out on a mass spectrometer with an ion source. The mass spectra contained the following monovalent cations: K, Rb, Cs, Ge, GeO, Ga, Ga/sub 2/O and Ga/sub 2/. The obtained results show that the main components in the gaseous phase above the title compound in the investigated temperature range are Ga, GeO, and Ga/sub 2/O.

  4. Study of the dependence of the radiative properties of high-frequency electrodeless lamps in an Hg-Ar mixture on the pressure of mercury vapor

    Microsoft Academic Search

    N. V. Denisova; G. Revalde; A. Skudra

    2006-01-01

    The radiative characteristics of high-frequency electrodeless lamps in a mixture of mercury and argon have been studied theoretically\\u000a and experimentally as functions of the cold spot temperature (the pressure of mercury vapor). The intensity of the mercury\\u000a lines at 404.7, 435.8, and 546.1 nm, corresponding to the triplet transition (73\\u000a S\\u000a 1-63\\u000a P\\u000a 0,1,2) in the visible spectral region, as

  5. Reaction analysis for ZrO 2 and Y 2O 3 thin film growth by low-pressure metalorganic chemical vapor deposition using ?-diketonate complexes

    Microsoft Academic Search

    Yasunobu Akiyama; Tsuneyuki Sato; Nobuyuki Imaishi

    1995-01-01

    A mathematical model was developed for low-pressure metalorganic chemical vapor deposition (LPMOCVD) of ZrO2 and Y2O3 film growth. Zr(DPM)4(tetrakis-2,2,6,6-tetramethyl-3,5-heptandionate zirconium (?-diketonate complex)) and Y(DPM)3 were used as source materials. The surface reaction rate constant (or the reactive sticking coefficient) was determined by comparing the experimentally observed step coverages on micro-scale trenches with those predicted by a simplified Monte Carlo simulation.

  6. Growth of zinc oxide films and nanowires by atmospheric-pressure chemical vapor deposition using zinc powder and water as source materials

    Microsoft Academic Search

    T. Terasako; M. Yagi; M. Ishizaki; Y. Senda; H. Matsuura; S. Shirakata

    2007-01-01

    Highly oriented ZnO films have been grown on c-plane sapphire substrate by atmospheric-pressure chemical vapor deposition using Zn powder and H2O as source materials. Photoluminescence intensity ratio of the green band at ?2.5eV to the near-band-edge emission at ?3.2eV (IGB\\/INBE) decreased with increasing the source feeding ratio of H2O to Zn (VI\\/II), indicating the possibility of the defect control. The

  7. Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms.

    PubMed

    Laus, Gerhard; Andre, Max; Bentivoglio, Gino; Schottenberger, Herwig

    2009-08-01

    1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and limits of detection were in the low microgram per gram range. The detection of traces of sulfolane in a real sample of tablets containing the drug cefpodoxim proxetil demonstrated the applicability of the method. PMID:19560778

  8. Phase liquid-vapor equilibria and thermodynamic properties of solutions of n-propanol-aliphatic ketones

    NASA Astrophysics Data System (ADS)

    Suntsov, Yu. K.; Vlasov, M. V.; Chuikov, A. M.

    2015-06-01

    The boiling points of solutions of five binary systems are measured using the ebulliometric method in the pressure range of 4.4-101.3 kPa. Compositions of the equilibrium vapor phases of systems are calculated, based on the constructed pressure isotherms of saturated vapor. The values of excess Gibbs energy and the enthalpy and entropy of solutions are calculated from the data on the liquid-vapor equilibrium. The patterns of change in the phase equilibria and thermodynamic properties of the solutions are established, based on the composition and temperature of the systems. The liquid-vapor equilibrium of systems is described using the equations of Wilson and the NRTL (Non-Random Two-Liquid model).

  9. Study on Condensing Heat Transfer Test under High Temperature and High Pressure Conditions

    NASA Astrophysics Data System (ADS)

    Morooka, Shinichi; Kubo, Shinji; Shirakawa, Ken-Etu; Yuasa, Hiroko; Yamamoto, Tetuzou; Ono, Hiroshi

    The condensing heat transfer coefficient is one of the important factors to evaluate the pressure change under BWR (Boiling Water Reactors) abnormal transients. Condensing condition is about 7 MPa of pressure with vapor flow. Many condensing studies have been done under atmospheric conditions with stagnant vapor. However, the condensing test results under BWR conditions have not reported. Therefore, the condensing heat transfer test of the saturated vapor with vertical upward vapor flow has been done under high temperature and high pressure conditions. The final purpose of this study is to develop the condensing correlation under BWR conditions. In this report, the data under pressures of 0.5 and 1 MPa are reported. Test section is tube. The inner diameter and condensing length is 57.6 mm and 2000 mm. Test fluid is saturated vapor. The following test results were obtained (1) Flooding may have occurred at a higher vapor velocity. (2) Vertical vapor flow has the effect to enhance the condensing heat transfer. (3) The measured heat transfer coefficients are larger than that of Nusselt model due to the vertical vapor flow

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

    Microsoft Academic Search

    John. S. McCloy; Ralph Korenstein; Brian Zelinski

    2009-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Fiock, Ernest F; King, H Kendall

    1936-01-01

    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.

  12. 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)

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

    2012-09-01

    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 m 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.

  13. Influence of omega-3 polyunsaturated fatty acids on blood pressure and some physiological parameters of female rats fed with a diet high in saturated fat and salt

    Microsoft Academic Search

    AP Jayasooriya; JA Armitage; HS Weisinger; RS Weisinger; P Burns; B Purcell; M Mathai; M. Morris; AJ Vingrys; AJ Sinclair

    Many western diets, although nutritionally adequate in most respects, may be deficient in omega-3 fatty acids. Recent data from our group (Sinclair, unpub) shows reduced neural DHA levels in animals maintained on a diet high in saturated fat, a diet not dissimilar to that of western societies. Furthermore, diets high in salt and saturated fats have been associated with elevated

  14. Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Quarterly report, October-December 1979

    SciTech Connect

    Johnson, I.; Swift, W.M.; Lee, S.H.D.; Jonke, A.A.

    1980-07-01

    This work supports the program to develop methods for the cleanup of combustion gases from pressurized fluidized-bed coal combustors so that the cleaned gases can be used for downstream gas turbines. This report presents the results of studies to develop granular sorbents for removing gaseous alkali metal compounds from high-temperature high-pressure combustion gases. Activated bauxite, one of the sorbents found to be effective, can be reused after removal of the alkali compound by a water-leaching process. Results of testing of this leaching process are reported. An experimental appartus for testing sorbents at high pressure has been built; results of preliminary tests are reported.

  15. Temporal evolution of OH density and gas temperature of nanosecond repetitively pulsed discharges in water vapor at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Sainct, Florent; Lacoste, Deanna; Laux, Christophe; Kirkpatrick, Michael J.; Odic, Emmanuel

    2013-09-01

    We present a study of plasma discharges produced by nanosecond repetitively pulses in water vapor at 450 K and 1 atm. The plasma was generated in water vapor with 20-ns duration high-voltage (0-20 kV) pulses, at a repetition frequency of 10 kHz, in the spark regime (2 mJ/pulse). To investigate plasma kinetics we focused on intermediate products of the discharge, in particular the hydroxyl radical. Between two discharges, the time-resolved density of OH was measured by Planar Laser Induced Fluorescence (OH-PLIF). The temperature during the discharge was determined by optical emission spectroscopy, and between two pulses by two-color OH-PLIF. A 150 K preheating effect from the previous pulses is measured, with a maximum temperature elevation of 950 K during the first 10 ?s following each pulse. The OH density measurements were compared with chemical kinetics simulations. The numerical results obtained with an initial OH density of 500 ppm show good agreement with the experimental data, thus providing a quantification of the OH density produced by the pulse. The electron number density is also measured via stark broadened H? lines. A kinetics model is proposed to interpret the measures.

  16. Saturation NOW

    Microsoft Academic Search

    Ming-ying Chung; Gianfranco Ciardo

    2004-01-01

    We present a distributed version of the saturation algorithm for symbolic state-space generation of discrete-state models. The execution is strictly sequential but utilizes the overall available memory. A level-based allocation of the decision diagram nodes onto the workstations is created. No additional node or work is created. A dynamic memory load balancing heuristic helps coping with the uneven growth of

  17. Saturation Unbound

    Microsoft Academic Search

    Gianfranco Ciardo; Robert M. Marmorstein; Radu Siminiceanu

    2003-01-01

    In previous work, we proposed a "saturation" algorithm for symbolic state-space generation characterized by the use of multi-valued decision diagrams, boolean Kronecker operators, event locality, and a special iteration strategy. This approach outperforms traditional BDD-based techniques by several orders of magnitude in both space and time but, like them, assumes a priori knowledge of each submodel's state space. We introduce

  18. Mathematical relationships between vapor pressure, water solubility, Henry's law constant, n-octanol/water partition coefficent and gas chromatographic retention index of polychlorinated-dibenzo-dioxins.

    PubMed

    Wan, Y H; Wong, P K

    2002-01-01

    Mathematical relationships between vapor pressures (P), water solubilities (S), Henry's law constants (Hc). noctanol/water partition coefficients (Kow) and gas chromatograph retention indices (GC-RIs) of polychlorinated-dibenzo-dioxins (PCDDs) were established. A model equation was established between GC-RIs (= RI) and other physico-chemical parameters (K) of PCDDs in the form of log K = aRI2 + bRI + c with correlation coefficients (R2) greater than 0.97, except Hc. These equations were derived from 56 experimental data of PCDDs reported previously. The values of P, S, Hc and Kow of PCDDs predicted by these equations based on their GC-RIs in the present study deviated from those calculated by the SOFA method in a previous study by only 0.19, 0.13, 0.18 and 0.096 log units, respectively. PMID:11766813

  19. Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels

    SciTech Connect

    Klobukowski, Erik R [ORNL; Tenhaeff, Wyatt E [ORNL; McCamy, James [PPG; Harris, Caroline [PPG; Narula, Chaitanya Kumar [ORNL

    2013-01-01

    The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    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.

  1. Experimental Study on the Mercury Vapor Pressures in Amalgam-Dosed Discharge Tubes for Compact Fluorescent Lamps during Switch-off Period

    NASA Astrophysics Data System (ADS)

    Yasuda, Takeo; Kando, Masashi

    Ballast-integrated compact fluorescent lamps are widely used for replacing incandescent lamps as energy saving alternative light sources. In spite of their high efficacies, the luminous run-up characteristics of the lamps having outer globes are slow and rather unsatisfactory, especially within a second or two. This problem is due to the lower mercury vapor pressure PHg of amalgam dosed in the discharge tube than that of liquid mercury. In order to improve the luminous flux at starting the lamp ignition, the PHg changes in the discharge tubes including bismuth-indium main amalgam and indium auxiliary amalgam were studied during switch-off period by atomic absorption spectrometry using 254 nm line. The amounts of mercury absorbed in both the main and auxiliary amalgam were also measured by wet chemical analyses. It is found that the PHg during switch-off period is not controlled by only the auxiliary amalgam but also the main amalgam.

  2. Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Vincent, B.; Gencarelli, F.; Bender, H.; Merckling, C.; Douhard, B.; Petersen, D. H.; Hansen, O.; Henrichsen, H. H.; Meersschaut, J.; Vandervorst, W.; Heyns, M.; Loo, R.; Caymax, M.

    2011-10-01

    In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sn contents up to 8%. Those metastable layers stay fully strained after 30 min anneal in N2 at 500 C; Ge-Sn interdiffusion is seen at 500 C but not at lower temperature. B is 100% active in the in-situ GeSn:B layers up to a concentration of 1.7 1019 cm-3. GeSn:B provides slightly lower Hall hole mobility values than in pure p-type Ge especially for low B concentrations.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  4. Study of spray cooling of a pressure vessel head of a boiling water reactor

    Microsoft Academic Search

    Henryk Anglart; Farid Alavyoon; Rmi Novarini

    2010-01-01

    The present paper deals with a theoretical analysis of the spray cooling of a Reactor Pressure Vessel (RPV) head in a Boiling Water Reactor (BWR). To this end a detailed computational model has been developed. The model predicts the trajectories, diameters and temperatures of subcooled droplets moving in saturated vapor. The model has been validated through comparison with experimental data,

  5. Carrier concentration and surface electron accumulation in indium nitride layers grown by high pressure chemical vapor deposition

    E-print Network

    Perera, A. G. Unil

    Carrier concentration and surface electron accumulation in indium nitride layers grown by high techniques in order to grow III-V semiconductors.1 However, the growth of InN and indium-rich group III-nitride different partial pressures in the group III-nitride system, stabilizing indium-rich alloys at growth

  6. Effective stress model for partially and fully saturated rocks

    SciTech Connect

    Dey, T.N.

    1989-01-01

    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.

  7. Global change-type drought-induced tree mortality: vapor pressure deficit is more important than temperature per se in causing decline in tree health

    PubMed Central

    Eamus, Derek; Boulain, Nicolas; Cleverly, James; Breshears, David D

    2013-01-01

    Abstract Drought-induced tree mortality is occurring across all forested continents and is expected to increase worldwide during the coming century. Regional-scale forest die-off influences terrestrial albedo, carbon and water budgets, and land-surface energy partitioning. Although increased temperatures during drought are widely identified as a critical contributor to exacerbated tree mortality associated with global-change-type drought, corresponding changes in vapor pressure deficit (D) have rarely been considered explicitly and have not been disaggregated from that of temperature per se. Here, we apply a detailed mechanistic soilplantatmosphere model to examine the impacts of drought, increased air temperature (+2C or +5C), and increased vapor pressure deficit (D; +1kPa or +2.5kPa), singly and in combination, on net primary productivity (NPP) and transpiration and forest responses, especially soil moisture content, leaf water potential, and stomatal conductance. We show that increased D exerts a larger detrimental effect on transpiration and NPP, than increased temperature alone, with or without the imposition of a 3-month drought. Combined with drought, the effect of increased D on NPP was substantially larger than that of drought plus increased temperature. Thus, the number of days when NPP was zero across the 2-year simulation was 13 or 14days in the control and increased temperature scenarios, but increased to approximately 200days when D was increased. Drought alone increased the number of days of zero NPP to 88, but drought plus increased temperature did not increase the number of days. In contrast, drought and increased D resulted in the number of days when NPP=0 increasing to 235 (+1kPa) or 304days (+2.5kPa). We conclude that correct identification of the causes of global change-type mortality events requires explicit consideration of the influence of D as well as its interaction with drought and temperature. This study disaggregates the influence of temperature and vapour pressure deficit on net primary productivity of an Australian woodland and their interactions with drought as potential causal agents in recent widespread forest mortality. PMID:24567834

  8. Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1979-September 1980

    SciTech Connect

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

    1980-10-01

    In the application of pressurized fluidized-bed combustion (PFBC) to the generation of electricity, hot corrosion of the gas turbine (downstream from the combustor) by alkali metal compounds is a potential problem. The objective of this investigation is to develop a method for the removal of gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. The use of a granular bed filter, with either diatomaceous earth or activated bauxite as the bed material, is under study. Breakthrough data are reported on the sorption of gaseous NaCl by activated bauxite. Results are reported for the regeneration of activated bauxite using water leaching and a thermal swing method.

  9. Selective growth of silicon-germanium alloys by atmospheric-pressure chemical vapor deposition at low temperatures

    Microsoft Academic Search

    P. D. Agnello; T. O. Sedgwick; M. S. Goorsky; J. Ott; T. S. Kuan; G. Scilla

    1991-01-01

    Dichlorosilane and germane were used to grow silicon-germanium alloys at temperatures as low as 550 C at atmospheric pressure. The silicon-germanium alloy composition was varied over the range 15%44%. Films containing high Ge mole fractions were grown at a temperature of 625 C and below and exhibit smooth surface morphology. Silicon-germanium\\/silicon multilayers with abrupt heterointerfaces have been achieved. Selective growth

  10. A study of vapor-phase deposition of silicon nitride layers by ammonolysis of dichlorosilane at lowered pressure

    SciTech Connect

    Manzha, N. M., E-mail: magazine@miee.ru [Moscow Institute of Electronic Technology, Technological Center Research-and-Production Company (Russian Federation)

    2010-12-15

    Deposition kinetics of silicon nitride layers at lowered reactor pressures of 10-130 Pa and temperatures in the range 973-1073 K has been studied. The equilibrium constant of the bimolecular reaction of dichlorosilane with ammonia has been calculated. The apparent activation energies calculated taking into account the experimental growth rate nearly coincide with the experimental data. Recommendations for improving the quality of silicon nitride layers are made.

  11. Growth of InN and In rich InGaN by ``High Pressure Chemical Vapor Deposition'' (HPCVD)

    NASA Astrophysics Data System (ADS)

    Buegler, Max; Alevli, Mustafa; Atalay, Ramazan; Durkaya, Goksel; Wang, Jielei; Senevirathna, Indika; Jamil, Muhammad; Ferguson, Ian; Dietz, Nikolaus

    2009-11-01

    We present the growth of III-nitrides under elevated nitrogen pressure to stabilize the growth surface at elevated temperatures. The achievable growth temperatures are significantly higher than in conventional low pressure MOCVD systems. With this the integration of In-rich materials into GaN and GaAlN becomes possible. In addition we present structural and optical properties of thin films grown by HPCVD at a reactor pressure of 15bar and temperatures of 870^oC. The Samples have been analyzed by Raman, optical absorption, IR reflectance and photoluminescence spectroscopy and by XRD. The growth of single phase layers of high crystalline quality has been proven by XRD with InN (0002) Bragg reflex FWHM's of 200arcsec (2?-?-scan) and 1600arcsec (rocking curves). These is backed up by Raman spectra with InN E2(high) peak FWHM's of below 10cm-1. Free carrier concentrations in the mid 10^18 cm-3 to low 10^19cm-3 have been calculated from IR reflection spectra. Photoluminescence spectroscopy showed luminescence at 0.77eV.

  12. Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2010-01-01

    Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature

  13. 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 ...

  14. Temperature and flow modulation doping of manganese in ZnS electroluminescent films by low pressure metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Yu, J. E.; Jones, K. S.; Holloway, P. H.; Pathangey, B.; Bretschneider, E.; Anderson, T. J.; Sun, S. S.; King, C. N.

    1994-03-01

    A temperature and flow modulation (TFM) technique has been developed to modulate the manganese doping profile in ZnS phosphor material grown by lowpressure metalorganic chemical vapor deposition for alternating-current thin film electroluminescent devices (TFELDs). In the TFM technique, modulation of both the substrate temperature as well as the flows of metalorganic sources, diethylzinc and tricarbonyl-(methylcyclopentadienyl)-manganese (TCPMn), was used to grow a structure consisting of alternating layers of undoped ZnS at 400C and Mn-doped ZnS where Mn being incorporated into the undoped ZnS at 550C. X-ray results indicated that MnSx phases were present within the ZnS host crystal matrix for the modulation doped samples, while a MnxZn1-xS solid solution was present in the uniformly doped samples. The luminescence efficiency of the TFELDs could be modified by growing the phosphor with dopant (luminescent center) modulation. The TFELDs with a single modulated doping phosphor layer showed lower threshold voltages in the range 70 to 80 V with light emission in the 580 to 587 nm wavelength range. With a twofold increase in the total thickness of the undoped ZnS layer, the brightness and the luminescence efficiency, measured at the threshold voltage plus 40 V, increased by a factor of 20 and 10, respectively. The electroluminescent (EL) characteristics of the phosphors with multiple dopant layers showed higher luminescence efficiency. By using the TFM growth technique, one can engineer the luminescent center distribution in the phosphor layer to improve the EL characteristics.

  15. Is CHF triggered by the vapor recoil effect?

    E-print Network

    Nikolayev, Vadim S; Chatain, D

    2007-01-01

    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.

  16. Optical sensor for diverse organic vapors at ppm concentration ranges.

    PubMed

    Thomas, J Christopher; Trend, John E; Rakow, Neal A; Wendland, Michael S; Poirier, Richard J; Paolucci, Dora M

    2011-01-01

    A broadly responsive optical organic vapor sensor is described that responds to low concentrations of organic vapors without significant interference from water vapor. Responses to several classes of organic vapors are highlighted, and trends within classes are presented. The relationship between molecular properties (vapor pressure, boiling point, polarizability, and refractive index) and sensor response are discussed. PMID:22163798

  17. Role of thermal stability and vapor pressure of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)magnesium(II) and its triamine adduct in producing magnesium oxide thin film using a plasma-assisted LICVD process

    Microsoft Academic Search

    Mathew Maria; J. Selvakumar; V. S. Raghunathan; K. S. Nagaraja

    2009-01-01

    Thin films of magnesia were deposited on various substrates using plasma-assisted liquid injection chemical vapor deposition with volatile Mg(tmhd)22H2O (1) (tmhd=2,2,6,6-tetramethyl-3,5-heptanedione). The precursor complexes, Mg2(tmhd)4(2), and Mg(tmhd)2pmdien (3) (pmdien; N,N,N?,N?,N?-pentamethyldiethylenetriamine) were prepared from Mg(tmhd)22H2O (1). The temperature dependence equilibrium vapor pressure (pe)T data yielded a straight line when log pe was plotted against reciprocal temperature in the range of 360475K,

  18. Insulator-insulator contact charging as a function of pressure

    NASA Astrophysics Data System (ADS)

    Hogue, Michael Duane

    Metal - metal and to an extent metal - insulator contact or triboelectric charging are well known phenomena with good theoretical understanding of the charge exchange mechanism. However, insulator - insulator charging is not as well understood. Theoretical and experimental research has been performed that shows that the surface charge on an insulator after triboelectric charging with another insulator is rapidly dissipated with lowered atmospheric pressure. This pressure discharge is consistent with surface ions being evaporated off the surface once their vapor pressure falls below the saturation vapor pressure. A two-phase equilibrium model based on an ideal gas of singly charged ions in equilibrium with a submonolayer adsorbed film was developed to describe the pressure dependence of the surface charge on an insulator. The resulting charge density equation is an electrostatic version of the Langmuir isotherm for adsorbed surface particles, which describes well the experimental observations.

  19. Production of superheated steam from vapor-dominated geothermal reservoirs

    USGS Publications Warehouse

    Truesdell, A.H.; White, D.E.

    1973-01-01

    Vapor-dominated geothermal systems such as Larderello, Italy, The Geysers, California, and Matsukawa, Japan yield dry or superheated steam when exploited. Models for these systems are examined along with production data and the thermodynamic properties of water, steam and rock. It is concluded that these systems initially consist of a water and steam filled reservoir, a water-saturated cap rock, and a water or brine-saturated deep reservoir below a water table. Most liquid water in all parts of the system is relatively immobilized in small pores and crevices; steam dominates the large fractures and voids of the reservoir and is the continuous, pressure-controlling phase. With production, the pressure is lowered and the liquid water boils, causing massive transfer of heat from the rock and its eventual drying. Passage of steam through already dried rock produces superheating. After an initial vaporization of liquid water in the reservoir, the decrease in pressure produces increased boiling below the deep water table. With heavy exploitation, boiling extends deeper into hotter rock and the temperature of the steam increases. This model explains most features of the published production behavior of these systems and can be used to guide exploitation policies. ?? 1973.

  20. -Saturated Solutions

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2014-11-01

    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.

  1. Performance of multiple mini-tube heat exchangers as an internal heat exchanger of a vapor-injection cycle heat pump

    NASA Astrophysics Data System (ADS)

    Jang, Jin Yong; Jeong, Ji Hwan

    2015-05-01

    A multiple mini-tube (MMT) heat exchanger was considered as an internal heat exchanger of vapor-injection cycle heat pump. Heat transfer and pressure drop in multiple mini-tube heat exchangers were numerically and experimentally investigated. Results show that the best performance of the MMT heat exchanger can be obtained when the intermediate-pressure two-phase refrigerant is supplied to the shell-side and this refrigerant reaches a saturated vapor state at the exit of the heat exchanger.

  2. The Extended Oxygen Window Concept for Programming Saturation Decompressions Using Air and Nitrox

    PubMed Central

    Kot, Jacek; Sicko, Zdzislaw

    2015-01-01

    Saturation decompression is a physiological process of transition from one steady state, full saturation with inert gas at pressure, to another one: standard conditions at surface. It is defined by the borderline condition for time spent at a particular depth (pressure) and inert gas in the breathing mixture (nitrogen, helium). It is a delicate and long lasting process during which single milliliters of inert gas are eliminated every minute, and any disturbance can lead to the creation of gas bubbles leading to decompression sickness (DCS). Most operational procedures rely on experimentally found parameters describing a continuous slow decompression rate. In Poland, the system for programming of continuous decompression after saturation with compressed air and nitrox has been developed as based on the concept of the Extended Oxygen Window (EOW). EOW mainly depends on the physiology of the metabolic oxygen windowalso called inherent unsaturation or partial pressure vacancybut also on metabolism of carbon dioxide, the existence of water vapor, as well as tissue tension. Initially, ambient pressure can be reduced at a higher rate allowing the elimination of inert gas from faster compartments using the EOW concept, and maximum outflow of nitrogen. Then, keeping a driving force for long decompression not exceeding the EOW allows optimal elimination of nitrogen from the limiting compartment with half-time of 360 min. The model has been theoretically verified through its application for estimation of risk of decompression sickness in published systems of air and nitrox saturation decompressions, where DCS cases were observed. Clear dose-reaction relation exists, and this confirms that any supersaturation over the EOW creates a risk for DCS. Using the concept of the EOW, 76 man-decompressions were conducted after air and nitrox saturations in depth range between 18 and 45 meters with no single case of DCS. In summary, the EOW concept describes physiology of decompression after saturation with nitrogen-based breathing mixtures. PMID:26111113

  3. Tunable alkali metallic vapor laser

    Microsoft Academic Search

    I. Itzkan; R. T. V. Kung

    1979-01-01

    A tunable alkali metallic vapor laser system is disclosed. Stimulated Raman scattering (SRS) in a low pressure atomic alkali metallic vapor of potassium or cesium is utilized wherein the atomic vapor is provided and then primed to populate an intermediate level such as the 4P level for potassium and the 6P level for cesium from which the desired upper laser

  4. Pressure and Density Series Equations of State for Steam as Derived from the HaarGallagherKell Formulation

    Microsoft Academic Search

    R. A. Dobbins; K. Mohammed; D. A. Sullivan

    1988-01-01

    Two equations of state for the properties of steam, which are in the form of power series in pressure and density, are developed from the HGK84 formulation. These equations are of high accuracy in the equilibrium region where extensive measurements exist. They also accurately represent the extrapolated data in the metastable region between the vapor saturation and spinodal lines. The

  5. The saturation of the electron beam filamentation instability by the self-generated magnetic field and magnetic pressure gradient-driven electric field

    Microsoft Academic Search

    M E Dieckmann; G Rowlands; I Kourakis; M Borghesi

    2008-01-01

    Two counter-propagating cool and equally dense electron beams are modelled with particle-in-cell (PIC) simulations. The electron beam filamentation instability is examined in one spatial dimension. The box length resolves one pair of current filaments. A small, a medium-sized and a large filament are considered and compared. The magnetic field amplitude at the saturation time of the filamentation instability is proportional

  6. Vacuum vapor deposition

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  7. Characterization of amorphous hydrogenated carbon formed by low-pressure inductively coupled plasma enhanced chemical vapor deposition using multiple low-inductance antenna units.

    PubMed

    Tsuda, Osamu; Ishihara, Masatou; Koga, Yoshinori; Fujiwara, Shuzo; Setsuhara, Yuichi; Sato, Naoyuki

    2005-03-24

    Three-dimensional plasma enhanced chemical vapor deposition (CVD) of hydrogenated amorphous carbon (a-C:H) has been demonstrated using a new type high-density volumetric plasma source with multiple low-inductance antenna system. The plasma density in the volume of phi 200 mm x 100 mm is 5.1 x 10(10) cm(-3) within +/-5% in the lateral directions and 5.2 x 10(10)cm(-3) within +/-10% in the axial direction for argon plasma under the pressure of 0.1 Pa and the total power as low as 400 W. The uniformity of the thickness and refractive index is within +/-3.5% and +/-1%, respectively, for the a-C:H films deposited on the substrates placed on the six side walls, the top of the phi 60 mm x 80 mm hexagonal substrate holder in the pure toluene plasma under the pressure is as low as 0.04 Pa, and the total power is as low as 300 W. It is also found that precisely controlled ion bombardment by pulse biasing led to the explicit observation in Raman and IR spectra of the transition from polymer-like structure to diamond-like structure accompanied by dehydrogenation due to ion bombardment. Moreover, it is also concluded that the pulse biasing technique is effective for stress reduction without a significant degradation of hardness. The stress of 0.6 GPa and the hardness of 15 GPa have been obtained for 2.0 microm thick films deposited with the optimized deposition conditions. The films are durable for the tribology test with a high load of 20 N up to more than 20,000 cycles, showing the specific wear rate and the friction coefficient were 1.2 x 10(-7) mm3/Nm and 0.04, respectively. PMID:16863147

  8. Band gap energy bowing and residual strain in CuAl(SxSe1-x)2 chalcopyrite semiconductor epilayers grown by low-pressure metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Harada, Yoshiyuki; Nakanishi, Hisayuki; Chichibu, Shigefusa F.

    2002-05-01

    A quadratic dependence of the band gap energy on the alloy composition x was quantified for CuAl(SxSe1-x)2 films grown by low-pressure metalorganic vapor phase epitaxy, by means of photoreflectance and photoluminescence excitation spectroscopies. The bowing parameter for the A-exciton energy was estimated to be 0.20 eV. Several high-quality films grown on GaAs(001) substrates exhibited excitonic photoluminescence peaks in the blue to ultraviolet spectral ranges. The flow rate of the Al precursor was found to affect the incorporation ratio of S/Se, indicating that the Al-S compound plays a key role in controlling x. All films grown on GaAs(001) showed c(001) orientation. Conversely, the epitaxitial orientation of the films on GaP(001) changed from a(100) to c(001) with an increase in x. The critical value of x was around 0.5. The preferred orientations were explained by the natural selection rule under which the lattice strain in the epilayer is minimized. The residual strain in the 0.5-?m-thick epilayers on GaAs(001) was nearly constant for all x, although the lattice mismatch between the epilayer and the GaAs substrate varied from 0.62% to 5.39% with an increase in x. Consequently the strain was attributed to thermal stress.

  9. The photosynthetic response of tobacco plants overexpressing ice plant aquaporin McMIPB to a soil water deficit and high vapor pressure deficit.

    PubMed

    Kawase, Miki; Hanba, Yuko T; Katsuhara, Maki

    2013-07-01

    We investigated the photosynthetic capacity and plant growth of tobacco plants overexpressing ice plant (Mesembryanthemum crystallinum L.) aquaporin McMIPB under (1) a well-watered growth condition, (2) a well-watered and temporal higher vapor pressure deficit (VPD) condition, and (3) a soil water deficit growth condition to investigate the effect of McMIPB on photosynthetic responses under moderate soil and atmospheric humidity and water deficit conditions. Transgenic plants showed a significantly higher photosynthesis rate (by 48%), higher mesophyll conductance (by 52%), and enhanced growth under the well-watered growth condition than those of control plants. Decreases in the photosynthesis rate and stomatal conductance from ambient to higher VPD were slightly higher in transgenic plants than those in control plants. When plants were grown under the soil water deficit condition, decreases in the photosynthesis rate and stomatal conductance were less significant in transgenic plants than those in control plants. McMIPB is likely to work as a CO2 transporter, as well as control the regulation of stomata to water deficits. PMID:23371744

  10. The influence of radiative heat exchange on the character of gasdynamic flows under conditions of pulsed discharge in high-pressure cesium vapor

    NASA Astrophysics Data System (ADS)

    Baksht, F. G.; Lapshin, V. F.

    2015-01-01

    The gasdynamics of pulse-periodic radiative discharge in high-pressure cesium vapor has been studied in the framework of a two-temperature multifluid model. It is established that, at a limited volume of the gas-discharge tube, the character of gasdynamic flows depends on the conditions of radiative heat exchange in discharge plasma. In cases in which the main contribution to radiative energy losses is related to a spectral region with optical thickness ? R (?) 1, there is nonlocal radiative heat exchange in discharge plasma, which is uniformly heated over the entire tube volume and moves from the discharge axis to tube walls during the entire pulse of discharge current. Under the conditions of radiative losses determined by the spectral region where ? R (?) ? 1, the reabsorption of radiation is absent and discharge plasma is nonuniformly heated by the current pulse. This leads to the appearance of reverse motions, so that the heated plasma is partly pushed toward the tube walls and partly returned to the discharge axis.

  11. Effects of Nitrate Application on Amaranthus powellii Wats : II. Stomatal Response to Vapor Pressure Difference is Consistent with Optimization of Stomatal Conductance.

    PubMed

    Hunt, E R; Weber, J A; Gates, D M

    1985-11-01

    The hypothesis of optimal stomatal conductance predicts conductance should vary with changes of the vapor pressure difference between leaf and air (VPD) to keep the partial derivative of transpiration rate (E) with respect to assimilation rate (A) constant ( partial differentialE/ partial differentialA = lambda). Stomatal conductance of Amaranthus powellii Wats. decreased strongly with increasing VPD for leaves with high total leaf nitrogen concentrations; whereas, it decreased slightly with increasing VPD for leaves with low leaf nitrogen concentrations. The calculated value of partial differentialE/ partial differentialA was constant for leaves with high leaf nitrogen concentrations but was not constant for leaves with low leaf nitrogen concentrations. However, the predicted values of stomatal conductance, transpiration rate, and assimilation rate for a constant lambda = 220 moles H(2)O/mole CO(2) and the measured values fit the y = x line for all nitrate treatments. These data extend the experimental support for the optimal water use efficiency hypothesis for a C(4) plant grown under different nitrate concentrations. PMID:16664460

  12. Low pressure chemical vapor deposition of Si{sub 1{minus}x}Ge{sub x} films on SiO{sub 2}: Characterization and modeling

    SciTech Connect

    Cao, M.; Wang, A.; Saraswat, K.C. [Stanford Univ., CA (United States). Center for Integrated Systems

    1995-05-01

    Deposition of silicon-germanium (Si{sub 1{minus}x}Ge{sub x}) thin films in a hot wall tubular low-pressure chemical vapor deposition (LPCVD) furnace using SiH{sub 4} and GeH{sub 4} at 100 mTorr with temperatures ranging from 297 to 650 C has been studied. The deposited films range from pure Si to pure Ge. The deposition rate behavior is presented. The apparent activation energy of deposition rate of Ge from GeH{sub 4} in reaction-rate limited regime was found to be 0.91 eV, and for the deposition of Si from SiH{sub 4} was found to be 1.7 eV. The relation between the GeH{sub 4} mole fraction in the gas phase during deposition and Ge atomic fraction in the film is described. A model based on the sticking probability of Si and Ge precursors on the surface is proposed to describe this relation. Applications of the Si{sub 1{minus}x}Ge{sub x} include heterojunction bipolar transistors, resonant tunneling diodes, modulation-doped field-effect transistors, quantum-well metal-oxide-semiconductor (MOS) FETs, infrared photodetectors used in fiber optics, gate electrodes for MOSFETs, polycrystalline thin film transistors, and high efficiency solar cells.

  13. Growth of silicon carbide on Si(100) substrate with an intermediate aluminum nitride layer by ultralow-pressure chemical vapor deposition using monomethylsilane

    NASA Astrophysics Data System (ADS)

    Nakazawa, Hideki; Suzuki, Daiki; Narita, Tsugitada; Meguro, Kazuki; Tsuchiya, Masato

    2015-05-01

    We have epitaxially grown silicon carbide (SiC) films on an aluminum nitride (AlN) layer on Si(100) substrate by ultralow-pressure chemical vapor deposition using monomethylsilane (CH3SiH3), and investigated the crystallinity and surface morphology of the grown films. Wurtzite AlN(0001) layers were formed on Si(100) substrate by pulsed laser deposition using an AlN target and a N2 gas, and then 3C-SiC(111) films were grown on the AlN layers. The growth rates of the 3C-SiC(111) films on the AlN layers were higher than those of 3C-SiC(100) films on the Si substrate. In the case of the SiC growth on the Si substrate, Si outdiffusion from the Si substrate occurred, leading to the formation of voids at the SiC/Si interface. It was found that the formation of the AlN intermediate layer was very effective in preventing the Si outdiffusion during the SiC growth. Concurrently, the crystallinity and surface morphology of the SiC films on the AlN layers were improved by insertion of the AlN layer.

  14. Effects of large daily variation of vapor pressure deficit on evapotranspiration and energy budget of wetland in a subalpine mountain valley

    NASA Astrophysics Data System (ADS)

    Chai, M. W.; Yan, Chunhua; Zhang, Qingtao; Xiang, Jiao; Wang, Yongqiang; Qiu, guo Yu

    2015-04-01

    Our early study showed that the daily relatively humidity in subalpine mountain valley varied very large, which may affect evapotranspiration (ET) and energy budget of valley. However, the effect of large humidity variation on ET and energy budget in subalpine valley is still not clear because of lacking of detail observation data. For this reason, we carried out a field experiment over a wetland in Jiuzhaigou Valley (a subalpine area in China). ET and energy budget was observed for 2 years period using Energy Balance Bowen Ratio (EBBR) method. Results show that in clear days, the relatively humidity of air could decrease from more than 90% in the early morning to less than 10% around noon time, which can result in vapor pressure deficit (VPD) changing from less than 0.1 to more than 2.0. We also find that the latent heat flux is about 80% of net radiation and the sensible heat flux is very low in the valley. The regression coefficient of the ratio of latent heat flux to net radiation and VPD is 0.21 and is 0.79 between ET and VPD. Therefore, it is concluded that the relative humidity is one of the most important factors affecting ET and energy budget in subalpine valleys.

  15. Analysis of the dynamics of saturation and pressure close to the wellbore for condensate reservoirs as a tool to optimize liquid production

    E-print Network

    Guerra Camargo, Andrea M

    2001-01-01

    REFERENCES. 109 APPENDIX A 115 VITA 125 LIST OF FIGURES FIGURE Page 2. 1 Sketch of a typical phase diagram for a gas condensate reservoir. . . . . . . 7 2. 2 Sketch of a constant volume dcplction test (CVD) . 2. 3 Sketch of a constant composition.... Validation of EOS from CCE at 150'F ? Relative volume, . . . . . . 43 3. 3 Cupiagua K-5. Validation ol'EOS liom CCE at 285'F ? Relative volume ?. .?. . . . . . 44 3. 4 Cupiagua K-5. Validation of EOS from CVD at 285'F ? Vapor density . . . . . . . 44 3. 5...

  16. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous media with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model

    NASA Astrophysics Data System (ADS)

    Sunil; Choudhary, Shalu; Mahajan, Amit

    2014-06-01

    A nonlinear stability threshold for convection in a rotating couple-stress fluid saturating a porous medium with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model is found to be exactly the same as the linear instability boundary. This optimal result is important because it shows that linear theory has completely captured the physics of the onset of convection. The effects of couple-stress fluid parameter F, temperature- and pressure-dependent viscosity ?, interface heat transfer coefficient H, Taylor number TA, Darcy-Brinkman number Da, and porosity modified conductivity ratio ? on the onset of convection have been investigated. Asymptotic analysis for both small and large values of interface heat transfer coefficient H is also presented. An excellent agreement is found between the exact solutions and asymptotic solutions.

  17. Explosive vaporization in microenclosures

    Microsoft Academic Search

    G. Romera-Guereca; J. Lichtenberg; A. Hierlemann; D. Poulikakos; B. Kang

    2006-01-01

    The explosive vaporization of a liquid above planar microheaters induces a fast increase of pressure that is exploited in many thermally driven actuators in MEMS components such as ink jet printer cartridges, pumps, valves and optical switches. Some of these components need to enclose the working fluid as it is the case of valves in which the heated liquid is

  18. Tides in water saturated rock

    Microsoft Academic Search

    Hans-Joachim Kctmpel

    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

  19. Pressure Field Study of the Tevatron Cold Compressors

    Microsoft Academic Search

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

    2004-01-01

    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

  20. Pressure field study of the Tevatron cold compressors

    Microsoft Academic Search

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

    2003-01-01

    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

  1. High pressure ratio cryocooler with integral expander and heat exchanger

    Microsoft Academic Search

    J. A. Crunkleton; J. L. Smith Jr.; Y. Iwasa

    1988-01-01

    A new 1 W, 4.2 K cryocooler is under development that is intended to miniaturize helium temperature refrigeration systems using a high-pressure-ratio Collins-type cycle. The configuration resulted from optimization studies of a saturated vapor compression (SCV) cycle that employs miniature parallel-plate heat exchangers. The basic configuration is a long displacer in a close-fitting, thin-walled cylinder. The displacer-to-cylinder gap is the

  2. Development of neural network models for the prediction of dewpoint pressure of retrograde gases and saturated oil viscosity of black oil systems

    E-print Network

    Gonzalez Zambrano, Alfredo Antonio

    2002-01-01

    Accurate prediction of gas condensate and crude oil fluid properties are critical elements in reservoir-engineering calculations. Dewpoint pressure of gas condensate reservoirs and oil viscosity of black oil systems are ...

  3. Growth and characterization of undoped and in situ doped Si1 - xGex on patterned oxide Si substrates by very low pressure chemical vapor deposition at 700 and 625 C

    Microsoft Academic Search

    Curtis Tsai; Syun-Ming Jang; Julie Tsai; Rafael Reif

    1991-01-01

    Results of strained layer Si1?xGex heteroepitaxy on patterned oxide silicon substrates using a very low pressure chemical vapor deposition reactor are presented. Patterned oxide wafers were insitu cleaned at 700 C using an Ar\\/H2 plasma. Undoped Si1?xGex strained layers at 625 and 700 C along with insitu doped p and n-type Si1?xGex strained layers at 625 C were deposited using

  4. Phonon and Roton Propagation in He II under Pressure

    Microsoft Academic Search

    R. C. Dynes; V. Narayanamurti; K. Andres

    1973-01-01

    We have studied the transition from second sound to ballistic phonon flow in He II up to pressures of 24 bar. At saturated vapor pressure the phonon-phonon scattering rate taupp-1?1.7106T3 sec-1 for T<0.6 K. At 24 bar, taupp-1<8104 sec-1 for T<0.7 K. The phonon-roton scattering rate taupr-1 is ~ 106 sec-1 at 0.75 K and almost pressure independent. At 24

  5. Use of a minimally invasive method of measuring leaf stomatal conductance to examine stomatal responses to water vapor pressure difference under field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most methods of measuring the diffusive conductance to water vapor of individual plant leaves potentially change the leaf environment by enclosing part of the leaf in order to measure the rate of water vapor exchange and the driving force for that exchange. Some types of porometers rely on the assu...

  6. Recipe for residual oil saturation determination

    Microsoft Academic Search

    A. J. Guillory; C. M. Kidwell

    1979-01-01

    In 1978, Shell Oil Co., in conjunction with the US Department of Energy, conducted a residual oil saturation study in a deep, hot high-pressured Gulf Coast Reservoir. The work was conducted prior to initiation of CO tertiary recovery pilot. Many problems had to be resolved prior to and during the residual oil saturation determination. The problems confronted are outlined such

  7. Externally predictive quantitative modeling of supercooled liquid vapor pressure of polychlorinated-naphthalenes through electron-correlation based quantum-mechanical descriptors.

    PubMed

    Vikas; Chayawan

    2014-01-01

    For predicting physico-chemical properties related to environmental fate of molecules, quantitative structure-property relationships (QSPRs) are valuable tools in environmental chemistry. For developing a QSPR, molecular descriptors computed through quantum-mechanical methods are generally employed. The accuracy of a quantum-mechanical method, however, rests on the amount of electron-correlation estimated by the method. In this work, single-descriptor QSPRs for supercooled liquid vapor pressure of chloronaphthalenes and polychlorinated-naphthalenes are developed using molecular descriptors based on the electron-correlation contribution of the quantum-mechanical descriptor. The quantum-mechanical descriptors for which the electron-correlation contribution is analyzed include total-energy, mean polarizability, dipole moment, frontier orbital (HOMO/LUMO) energy, and density-functional theory (DFT) based descriptors, namely, absolute electronegativity, chemical hardness, and electrophilicity index. A total of 40 single-descriptor QSPRs were developed using molecular descriptors computed with advanced semi-empirical (SE) methods, namely, RM1, PM7, and ab intio methods, namely, Hartree-Fock and DFT. The developed QSPRs are validated using state-of-the-art external validation procedures employing an external prediction set. From the comparison of external predictivity of the models, it is observed that the single-descriptor QSPRs developed using total energy and correlation energy are found to be far more robust and predictive than those developed using commonly employed descriptors such as HOMO/LUMO energy and dipole moment. The work proposes that if real external predictivity of a QSPR model is desired to be explored, particularly, in terms of intra-molecular interactions, correlation-energy serves as a more appropriate descriptor than the polarizability. However, for developing QSPRs, computationally inexpensive advanced SE methods such as PM7 can be more reliable than the expensive ab inito methods. PMID:24168755

  8. 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

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

    2000-05-30

    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.

  9. Atmospheric-pressure plasma-enhanced chemical vapor deposition of a-SiCN:H films: role of precursors on the film growth and properties.

    PubMed

    Guruvenket, Srinivasan; Andrie, Steven; Simon, Mark; Johnson, Kyle W; Sailer, Robert A

    2012-10-24

    Atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) using Surfx Atomflow(TM) 250D APPJ was utilized to synthesize amorphous silicon carbonitride coatings using tetramethyldisilizane (TMDZ) and hexamethyldisilizane (HMDZ) as the single source precursors. The effect of precursor chemistry and substrate temperature (T(s)) on the properties of a-SiCN:H films were evaluated, while nitrogen was used as the reactive gas. Surface morphology of the films was evaluated using atomic force microscopy (AFM); chemical properties were determined using Fourier transform infrared spectroscopy (FTIR); thickness and optical properties were determined using spectroscopic ellipsometry and mechanical properties were determined using nanoindentation. In general, films deposited at substrate temperature (T(s)) < 200 C contained organic moieties, while the films deposited at T(s) > 200 C depicted strong Si-N and Si-CN absorption. Refractive indices (n) of the thin films showed values between 1.5 and 2.0, depending on the deposition parameters. Mechanical properties of the films determined using nanoindentation revealed that these films have hardness between 0.5 GPa and 15 GPa, depending on the T(s) value. AFM evaluation of the films showed high roughness (R(a)) values of 2-3 nm for the films grown at low T(s) (<250 C) while the films grown at T(s) ? 300 C exhibited atomically smooth surface with R(a) of ~0.5 nm. Based on the gas-phase (plasma) chemistry, precursor chemistry and the other experimental observations, a possible growth model that prevails in the AP-PECVD of a-SiCN:H thin films is proposed. PMID:22979919

  10. Different architectures of relaxed Si 1- xGe x/Si pseudo-substrates grown by low-pressure chemical vapor deposition: Structural and morphological characteristics

    NASA Astrophysics Data System (ADS)

    Rassi, M.; Regula, G.; Hadj Belgacem, C.; Rochdi, N.; Bozzo-Escoubas, S.; Coudreau, C.; Hollnder, B.; Fnaiech, M.; D'Avitaya, F. A.; Lazzari, J.-L.

    2011-08-01

    A detailed characterization of SiGe thin layers grown by low-pressure chemical vapor deposition (LP-CVD) on different types of Si buffer layers (BLs) is presented. Using the same conditions of SiGe growth, Si BLs were elaborated in ultra-high vacuum conditions at low (575 C) and medium (700 C) temperatures to improve the crystalline quality of the Si buffer layer. Using both types of Si BLs, the SiGe layer exhibits a very high density of dislocations (>10 5 cm -2). Here, we proposed to create a ductile area in the Si BL, before the SiGe deposition. It consists of nanocavities located at about 100 nm under the Si BL surface and obtained by He + implantation at 10 keV and at room temperature with fluencies of 510 15 ions cm -2 or 510 16 ions cm -2. The creation of the nanocavity layer is enabled by an annealing step at 700 C for one hour. These kinds of Si BLs were studied by cross section transmission electron microscopy, X-ray diffraction, Rutherford backscattering, photoluminescence, atomic force and optical microscopy before and after revealing the dislocations by the chemical etching of SiGe layers. From these analyses, we evidenced the blocking of threading dislocations by the formation of loops located between the region of nanocavities formed in the substrate and the SiGe/Si interface. This method allows to strongly enhance the relaxation rate (97%) of SiGe layers, and to improve their crystalline and morphological quality for their use for high-speed microelectronic and optoelectronic devices for which the surface roughness and the threading dislocation density are key issues.

  11. Seasonal trends in leaf photosynthesis and stomatal conductance of drought stressed and nonstressed pearl millet as associated to vapor pressure deficit.

    PubMed

    Tewolde, H; Dobrenz, A K; Voigt, R L

    1993-10-01

    Single leaf photosynthesis (Pn) and stomatal conductance (Cg) of drought stressed and nonstressed pearl millet [Pennisetum americanum (L.) Leeke] were measured across growth stages to determine if a pattern exists in Pn and Cg during the growing season and to evaluate the influence of air vapor pressure deficit (VPDa) on the seasonal variations of Pn and Cg. Leaf photosynthesis and Cg were measured independently on pearl millet plants grown at the driest (drought stressed) and wettest (nonstressed) ends of a line-source irrigation gradient system. Well defined and predictable variations in both Pn and Cg were found across two growing seasons. Leaf photosynthesis of the nonstressed plants declined from a maximumof 25.8 ?mol m(-2) s(-1) at the flag leaf emergence (48 days after planting, DAP) to a minimum of 14.5 ?mol m(-2) s(-1) at physiological maturity. Stomatal conductance of the nonstressed plants peaked at the flowering and early grain fill stages and declined as plants approached maturity. In contrast, Pn and Cg of the stressed plants declined from a maximum at flag leaf emergence to a minimum at flowering and increased as plants approached maturity. High VPDa during the flowering and grain fill stages induced stomatal closure and decreased Pn in the stressed plants. High mid-season VPDa did not induce stomatal closure and did not reduce leaf photosynthesis in nonstressed plants. The lack of sensitivity of Pn to VPDa in the nonstressed treatment suggests large air VPD such as that prevalent in southern Arizona does not limit the growth of irrigated pearl millet by limiting CO2 assimilation. PMID:24317829

  12. Influences of damage and contamination from reactive ion etching on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor

    NASA Astrophysics Data System (ADS)

    Chang, Kow-Ming; Yeh, Ta-Hsun; Wang, Shih-Wei; Li, Chii-Horng

    1996-09-01

    Reactive ion etching (RIE) used in contact hole formation can result in damage and contamination of the underlying silicon substrate. In this work, influences of these phenomena on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor have been studied. The damage was generated because of ion bombardment and radiation-induced bonding changes in silicon lattices. It causes large Si consumption, rough W/Si interface during tungsten deposition, and large leakage current of W/Si Schottky structure. Simultaneously, contamination occurred with two forms of residual layers and impurity permeation layers in fluorocarbon-based RIE chemistries. The CF4/CHF3/O2 RIE of oxide produces the SiFxCyOz complex layers deposited on the sidewall and on the Si surface as well as the embedding of impurities such as F and C in the Si substrate. The creep-up, selectivity loss, lateral encroachment, high W film resistivity, and rough W/Si interface have been observed in the contaminated samples. Accordingly, a post-RIE etching technique used to remove the damage and contaminants before tungsten growth has been developed. A CF4/O2 plasma etching followed with an O2 plasma ashing step exhibits the capability of efficient surface cleaning. The excellent characteristics of W films such as elimination of encroachment and creep-up, low selectivity loss (i.e., 0.25 pcs/cm2), low resistivity of W films, smooth W/Si interface, and very low leakage current of W/Si contacts are thus obtained.

  13. Passive Vaporizing Heat Sink

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  14. Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

    SciTech Connect

    Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2012-02-20

    Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

  15. A vapor generator for transonic flow visualization

    NASA Technical Reports Server (NTRS)

    Bruce, Robert A.; Hess, Robert W.; Rivera, Jose A., Jr.

    1989-01-01

    A vapor generator was developed for use in the NASA Langley Transonic Dynamics Tunnel (TDT). Propylene glycol was used as the vapor material. The vapor generator system was evaluated in a laboratory setting and then used in the TDT as part of a laser light sheet flow visualization system. The vapor generator provided satisfactory seeding of the air flow with visible condensate particles, smoke, for tests ranging from low subsonic through transonic speeds for tunnel total pressures from atmospheric pressure down to less than 0.1 atmospheric pressure.

  16. Vapor Pressure measurements for dichlorosilane

    E-print Network

    Morris, Tony Knimbula

    1997-01-01

    Research Laboratory was also used briefly. The sensitivity control would not adjust properly, so it remained on exnemely high sensitivity and became more of a nuisance than a benefit. A Matheson Gas Products leak detector was also borrowed to find small..., this fitting was adequate for this process. The tubing was connected to the sample cylinder through a bellows valve. To check the connections for leaks, a vacuum was created up to the entrance of the dichlorosilane cylinder. The de-gassing cylinder had...

  17. Thermodynamic Properties of Ethylene from the Freezing Line to 450 K at Pressures to 260 MPa

    NASA Astrophysics Data System (ADS)

    Jahangiri, Majid; Jacobsen, Richard T.; Stewart, Richard B.; McCarty, Robert D.

    1986-04-01

    A new fundamental equation explicit in Helmholtz energy for thermodynamic properties of ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. Independent equations for the vapor pressure for the saturated liquid and vapor densities as functions of temperature, and for the ideal gas heat capacity are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least-squares fit to selected P-?-T data, saturated liquid, and saturated vapor density data to define the phase equilibrium criteria for coexistence, Cv data, velocity of sound data, and second virial coefficient data. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), and velocity of sound are included. Tables of thermodynamic properties of ethylene are given for liquid and vapor states within the range of validity of the fundamental equation. The fundamental equation reported here may generally be used to calculate pressures and densities with an uncertainty of 0.1%, heat capacities within 3%, and velocity of sound values within 1%. Comparisons of calculated properties to experimental data are included to verify the accuracy of the formulation.

  18. Pressure

    NSDL National Science Digital Library

    Wolfgang Christian

    This page contains three Physlets that are able to share data using a connection made by a common superclass, SApplet. The ensemble walls keep track of the change in momentum, i.e., the pressure, during each time step, dt, and provides this data to the DataGraph Physlet and the DataTable Physlet.

  19. Shock-induced vaporization of zinc -- Experiments and numerical simulations

    Microsoft Academic Search

    L. C. Chhabildas; R. M. Brannon

    1996-01-01

    Prediction of the interaction between expanded vaporized debris and target materials for applications such as meteorite impact on space vehicles, ballistic penetration of armors, debris shield design, etc. demands an accurate treatment of the melting and vaporization process and the kinetics of liquid-vapor propagation. Historically, experimental efforts to understand high-pressure melting and vaporization have been hindered by unavailability of experimental

  20. Condensing phenomena of a single vapor bubble into subcooled water

    SciTech Connect

    Kamei, S. (Dept. of Mechanical Engineering, Univ. of Tokyo, Tokyo (JP)); Hirata, M. (Research Center for Advanced Science and Technology, Univ. of Tokyo, Tokyo (JP))

    1990-01-01

    This paper reports on experiments carried out to investigated direct contact condensation of saturated vapor bubbles introduced into a quiescent subcooled water environment. The experiments were performed for a range of pressures from atmospheric to 1 MPa, for subcooling from 10 to 70 K, and for initial bubble diameters of about 10 mm. Flow visualization by high-speed motion pictures was based on a frame-by-frame analysis. The authors show that the successive shapes of the bubbles during their collapse histories proceeded from a sphere to a hemisphere, to an ellipsoid, to a sphere, and finally to collapse. They show that the cavities of the bubbles during their collapse histories proceeded from the bottom to the top. The time to collapse increased with increasing pressure difference. The rising velocities of the bubbles were essentially constant, with an overall range of 20--25 cm/s.