Science.gov

Sample records for phosphorus vapor pressure

  1. Water vapor pressure calculation.

    PubMed

    Hall, J R; Brouillard, R G

    1985-06-01

    Accurate calculation of water vapor pressure for systems saturated with water vapor can be performed using the Goff-Gratch equation. A form of the equation that can be adapted for computer programming and for use in electronic databases is provided. PMID:4008425

  2. 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.

  3. Precision ozone vapor pressure measurements

    NASA Technical Reports Server (NTRS)

    Hanson, D.; Mauersberger, K.

    1985-01-01

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

  4. Vapor pressure measured with inflatable plastic bag

    NASA Technical Reports Server (NTRS)

    1965-01-01

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

  5. Vapor pressures of new fluorocarbons

    SciTech Connect

    Kubota, H.; Yamashita, T.; Tanaka, Y.; Makita, T. )

    1989-05-01

    The vapor pressures of four fluorocarbons have been measured at the following temperature ranges: R123 (2,2-dichloro-1,1,1-trifluoroethane), 273-457 K; R123a (1,2-dichloro-1,1,2-trifluoroethane), 303-458 K; R134a (1,1,1,2-tetrafluoroethane), 253-373 K; and R132b (1,2-dichloro-1,1-difluoroethane), 273-398 K. Determinations of the vapor pressure were carried out by a constant-volume apparatus with an uncertainty of less than 1.0%. The vapor pressures of R123 and R123a are very similar to those of R11 over the whole experimental temperature range, but the vapor pressures of R134a and R132b differ somewhat from those of R12 and R113, respectively, as the temperature increases. The numerical vapor pressure data can be fitted by an empirical equation using the Chebyshev polynomial with a mean deviation of less than 0.3%.

  6. Layered Black Phosphorus as a Selective Vapor Sensor.

    PubMed

    Mayorga-Martinez, Carmen C; Sofer, Zdeněk; Pumera, Martin

    2015-11-23

    Black phosphorus is a layered material that is sensitive to the surrounding atmosphere. This is generally considered as a disadvantage, especially when compared to more stable layered compounds, such as graphite or MoS2. This sensitivity is now turned into an advantage. A vapor sensor that is based on layered black phosphorus and uses electrochemical impedance spectroscopy as the detection method is presented; the device selectively detects methanol vapor. The impedance phase measured at a constant frequency is used as a distinctive parameter for the selective quantification of methanol, and increases with the methanol concentration. The low detection limit of 28 ppm is well below the approved exposure limit of 200 ppm. The results are highly reproducible, and the vapor sensor is shown to be very selective in the presence of other vapors and to have long-term stability. PMID:26403872

  7. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    ERIC Educational Resources Information Center

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

    2007-01-01

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

  8. 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…

  9. VAPOR PRESSURES AND HEATS OF VAPORIZATION OF PRIMARY COAL TARS

    SciTech Connect

    Eric M. Suuberg; Vahur Oja

    1997-07-01

    This project had as its main focus the determination of vapor pressures of coal pyrolysis tars. It involved performing measurements of these vapor pressures and from them, developing vapor pressure correlations suitable for use in advanced pyrolysis models (those models which explicitly account for mass transport limitations). This report is divided into five main chapters. Each chapter is a relatively stand-alone section. Chapter A reviews the general nature of coal tars and gives a summary of existing vapor pressure correlations for coal tars and model compounds. Chapter B summarizes the main experimental approaches for coal tar preparation and characterization which have been used throughout the project. Chapter C is concerned with the selection of the model compounds for coal pyrolysis tars and reviews the data available to us on the vapor pressures of high boiling point aromatic compounds. This chapter also deals with the question of identifying factors that govern the vapor pressures of coal tar model materials and their mixtures. Chapter D covers the vapor pressures and heats of vaporization of primary cellulose tars. Chapter E discusses the results of the main focus of this study. In summary, this work provides improved understanding of the volatility of coal and cellulose pyrolysis tars. It has resulted in new experimentally verified vapor pressure correlations for use in pyrolysis models. Further research on this topic should aim at developing general vapor pressure correlations for all coal tars, based on their molecular weight together with certain specific chemical characteristics i.e. hydroxyl group content.

  10. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 33 2013-07-01 2013-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  11. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 33 2012-07-01 2012-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  12. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 32 2014-07-01 2014-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  13. Specific vapor sorption properties of phosphorus-containing dendrimers.

    PubMed

    Gerasimov, Alexander V; Ziganshin, Marat A; Vandyukov, Alexander E; Kovalenko, Valeri I; Gorbatchuk, Valery V; Caminade, Anne-Marie; Majoral, Jean-Pierre

    2011-08-01

    Specific combination of guest sorption properties was observed for phosphorus-containing dendrimers, which distinguish them from ordinary polymers and clathrate-forming hosts. The sorption capacity for 30 volatile guests, binding reversibility, guest desorption kinetics and guest exchange, glass transition behavior and ability to be plasticized with guest were studied for phosphorus dendrimers of different generations (G(1)-G(4) and G(9)) using quartz crystal microbalance sensor, FTIR microspectroscopy, atomic force microscopy, simultaneous thermogravimetry and differential scanning calorimetry combined with mass-spectrometry of evolved vapors. The dendrimers were found to have a different selectivity for different homological series of guests, high glass transition points without plasticization with guest even at high temperatures and saturation levels, moderate guest-binding irreversibility and ability both for effective guest exchange and independent guest sorption. These properties constitute an advantage of the studied dendrimers as receptor materials in various applications. PMID:21546037

  14. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true Vapor pressure. 796.1950 Section 796.1950 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a) Introduction—(1) Background and...

  15. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 32 2011-07-01 2011-07-01 false Vapor pressure. 796.1950 Section 796.1950 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a) Introduction—(1) Background...

  16. Influence of phosphorus vapor ambient for InGaAsP growth on GaAs substrate

    NASA Astrophysics Data System (ADS)

    Ishikawa, Joji; Ito, Toshio; Shin-ichi Takahashi, N.; Kurita, Shoichi

    1986-12-01

    For visible-light-emitting laser diodes, InGaAsP double heterostructures have been grown on GaAs substrates using liquid-phase epitaxy. As the growth temperature is as high as about 780 °C, a large amount of phosphorus evaporates from the solutions for the cladding layers during the growth process. The phosphorus vapor disturbs the solution composition for the active layer, so that very thin and uniform active layers cannot be obtained. By using In-P-Sn solution and supplying the phosphorus partial pressure around the graphite boat, the influence of phosphorus vapor ambient for InGaAsP (λPL=805 nm) growth is confirmed. When the phosphorus partial pressure increases, the surface of epitaxial layer becomes rough and the substrate is partly etched back. From x-ray diffraction and photoluminescence spectral measurements, the composition of the grown layer is also found to be changed. As a result of increasing the flow rate of H2 gas in order to protect the solution for the active layer from phosphorus contamination, the double heterostructure wafers with the high-quality active layer can be obtained reproducibly. Thus, pulsed lasing operation at room temperature has been achieved. The lasing wavelength is 816 nm and the threshold current density is ˜4.6 kA/cm2.

  17. Multicomponent fuel vaporization at high pressures.

    SciTech Connect

    Torres, D. J.; O'Rourke, P. 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.

  18. Pressure-induced crystallization of amorphous red phosphorus

    NASA Astrophysics Data System (ADS)

    Rissi, Erin N.; Soignard, Emmanuel; McKiernan, Keri A.; Benmore, Chris. J.; Yarger, Jeffery L.

    2012-03-01

    Structural transitions in amorphous red phosphorus were studied at ambient temperature and pressures up to 12 GPa. Amorphous (red) phosphorus was observed to transform into crystalline black phosphorus at 7.5 ± 0.5 GPa using diamond anvil cell Raman spectroscopy, x-ray diffraction and a direct equation of state (EoS) measurement. The transition was found to be irreversible and the material recovered upon pressure cycling to 10 to 12 GPa was crystalline orthorhombic black phosphorus. A third order Birch-Murnaghan EoS was fit to the data and a bulk modulus (B0) of 11.2 GPa was measured for amorphous red phosphorus.

  19. The vapor pressure of iron pentacarbonyl

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  20. Vapor pressures of acetylene at low temperatures

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  1. Vapor pressures of the aqueous desiccants

    SciTech Connect

    Chung, T.W.; Luo, C.M.

    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.

  2. Low-pressure, chemical vapor deposition polysilicon

    NASA Technical Reports Server (NTRS)

    Gallagher, B. D.; Crotty, G. C.

    1986-01-01

    The low-pressure chemical vapor deposition (LPCVD) of polycrystalline silicon was investigted. The physical system was described, as was the controlling process parameters and requirements for producing films for use as an integral portion of the solar cell contact system.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  5. Salinity gradient power: utilizing vapor pressure differences.

    PubMed

    Olsson, M; Wick, G L; Isaacs, J D

    1979-10-26

    By utilizing the vapor pressure difference between high-salinity and lowsalinity wvater, one can obtain power from the gradients of salinity. This scheme eliminates the major problems associated with conversion methods in which membranes are used. The method we tested gave higher conversion efficiencies than membrane methods. Furthermore, hardware and techniques being developed for ocean thermal energy conversion may be applied to this approach to salinity gradient energy conversion. PMID:17809370

  6. Nucleation pressure threshold in acoustic droplet vaporization

    NASA Astrophysics Data System (ADS)

    Miles, Christopher J.; Doering, Charles R.; Kripfgans, Oliver D.

    2016-07-01

    We combine classical nucleation theory with superharmonic focusing to predict necessary pressures to induce nucleation in acoustic droplet vaporization. We show that linear acoustics is a valid approximation to leading order when particle displacements in the sound field are small relative to the radius of the droplet. This is done by perturbation analysis of an axisymmetric compressible inviscid flow about a droplet with small surface perturbations relative to the mean radius subjected to an incoming ultrasonic wave. The necessary nucleation pressure threshold inside the droplet is calculated to be -9.33 ± 0.30 MPa for typical experimental parameters by employing results from classical homogeneous nucleation theory. As a result, we are able to predict if a given incident pressure waveform will induce nucleation.

  7. Large improvement of phosphorus incorporation efficiency in n-type chemical vapor deposition of diamond

    SciTech Connect

    Ohtani, Ryota; Yamamoto, Takashi; Janssens, Stoffel D.; Yamasaki, Satoshi

    2014-12-08

    Microwave plasma enhanced chemical vapor deposition is a promising way to generate n-type, e.g., phosphorus-doped, diamond layers for the fabrication of electronic components, which can operate at extreme conditions. However, a deeper understanding of the doping process is lacking and low phosphorus incorporation efficiencies are generally observed. In this work, it is shown that systematically changing the internal design of a non-commercial chemical vapor deposition chamber, used to grow diamond layers, leads to a large increase of the phosphorus doping efficiency in diamond, produced in this device, without compromising its electronic properties. Compared to the initial reactor design, the doping efficiency is about 100 times higher, reaching 10%, and for a very broad doping range, the doping efficiency remains highly constant. It is hypothesized that redesigning the deposition chamber generates a higher flow of active phosphorus species towards the substrate, thereby increasing phosphorus incorporation in diamond and reducing deposition of phosphorus species at reactor walls, which additionally reduces undesirable memory effects.

  8. Large improvement of phosphorus incorporation efficiency in n-type chemical vapor deposition of diamond

    NASA Astrophysics Data System (ADS)

    Ohtani, Ryota; Yamamoto, Takashi; Janssens, Stoffel D.; Yamasaki, Satoshi; Koizumi, Satoshi

    2014-12-01

    Microwave plasma enhanced chemical vapor deposition is a promising way to generate n-type, e.g., phosphorus-doped, diamond layers for the fabrication of electronic components, which can operate at extreme conditions. However, a deeper understanding of the doping process is lacking and low phosphorus incorporation efficiencies are generally observed. In this work, it is shown that systematically changing the internal design of a non-commercial chemical vapor deposition chamber, used to grow diamond layers, leads to a large increase of the phosphorus doping efficiency in diamond, produced in this device, without compromising its electronic properties. Compared to the initial reactor design, the doping efficiency is about 100 times higher, reaching 10%, and for a very broad doping range, the doping efficiency remains highly constant. It is hypothesized that redesigning the deposition chamber generates a higher flow of active phosphorus species towards the substrate, thereby increasing phosphorus incorporation in diamond and reducing deposition of phosphorus species at reactor walls, which additionally reduces undesirable memory effects.

  9. A technique for eliminating white phosphorus deposits in vapor phase epitaxy systems

    NASA Technical Reports Server (NTRS)

    Wilt, D. M.; Hoffman, R. W.

    1993-01-01

    A technique of heating the exhaust lines is described whereby phosphorus in the exhaust portion of an organometallic vapor phase epitaxy reactor is encouraged to deposit in the red form rather than the pyrophoric white form. This technique is simple, effective, and does not hinder or limit the conditions under which the reactor may be operated.

  10. THE VAPOR PRESSURE OF DOG'S BLOOD AT BODY TEMPERATURE.

    PubMed

    Grollman, A

    1928-05-20

    The vapor pressures of dog's blood and blood plasma were determined at 37.5 degrees by the dynamic method and the osmotic pressures calculated from the experimental data. The vapor pressures calculated from experimentally determined freezing point data agreed, within the experimental error, with the values obtained from direct measurement. The vapor pressure lowering produced by the colloid constituents of the blood was also determined and found to be minimal compared to that of the other constituents. PMID:19872415

  11. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of...

  12. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of...

  13. Pressure-Induced Electronic Transition in Black Phosphorus.

    PubMed

    Xiang, Z J; Ye, G J; Shang, C; Lei, B; Wang, N Z; Yang, K S; Liu, D Y; Meng, F B; Luo, X G; Zou, L J; Sun, Z; Zhang, Y; Chen, X H

    2015-10-30

    In a semimetal, both electrons and holes contribute to the density of states at the Fermi level. The small band overlaps and multiband effects engender novel electronic properties. We show that a moderate hydrostatic pressure effectively suppresses the band gap in the elemental semiconductor black phosphorus. An electronic topological transition takes place at approximately 1.2 GPa, above which black phosphorus evolves into a semimetal state that is characterized by a colossal positive magnetoresistance and a nonlinear field dependence of Hall resistivity. The Shubnikov-de Haas oscillations detected in magnetic field reveal the complex Fermi surface topology of the semimetallic phase. In particular, we find a nontrivial Berry phase in one Fermi surface that emerges in the semimetal state, as evidence of a Dirac-like dispersion. The observed semimetallic behavior greatly enriches the material property of black phosphorus and sets the stage for the exploration of novel electronic states in this material. PMID:26565480

  14. Growth of 2D black phosphorus film from chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Smith, Joshua B.; Hagaman, Daniel; Ji, Hai-Feng

    2016-05-01

    Phosphorene, a novel 2D material isolated from bulk black phosphorus (BP), is an intrinsic p-type material with a variable bandgap for a variety of applications. However, these applications are limited by the inability to isolate large films of phosphorene. Here we present an in situ chemical vapor deposition type approach that demonstrates progress towards growth of large area 2D BP with average areas >3 μm2 and thicknesses representing samples around four layers and thicker samples with average areas >100 μm2. Transmission electron microscopy and Raman spectroscopy have confirmed successful growth of 2D BP from red phosphorus.

  15. Growth of 2D black phosphorus film from chemical vapor deposition.

    PubMed

    Smith, Joshua B; Hagaman, Daniel; Ji, Hai-Feng

    2016-05-27

    Phosphorene, a novel 2D material isolated from bulk black phosphorus (BP), is an intrinsic p-type material with a variable bandgap for a variety of applications. However, these applications are limited by the inability to isolate large films of phosphorene. Here we present an in situ chemical vapor deposition type approach that demonstrates progress towards growth of large area 2D BP with average areas >3 μm2 and thicknesses representing samples around four layers and thicker samples with average areas >100 μm2. Transmission electron microscopy and Raman spectroscopy have confirmed successful growth of 2D BP from red phosphorus. PMID:27087456

  16. Organometallic vapor phase epitaxial growth of InP using new phosphorus sources

    NASA Astrophysics Data System (ADS)

    Larsen, C. A.; Chen, C. H.; Kitamura, M.; Stringfellow, G. B.; Brown, D. W.; Robertson, A. J.

    1986-06-01

    Two organophosphorus compounds, isobutylphosphine and tertiarybutylphosphine, have been investigated for their possible use as precursors in the organometallic vapor phase epitaxy process. They are the first nonhydride compounds to be used as phosphorus sources. Pyrolysis studies show that the first decomposition products are phosphine and various organic compounds. The phosphine then pyrolyzes to give phosphorus. The materials are less pyrophoric and less toxic than phosphine, and so are safer to use. The compounds have been used to grow epitaxial layers of InP on InP and GaAs substrates. The layers exhibit photoluminescence and electrical properties which are similar to those of layers grown with phosphine.

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

    NASA Technical Reports Server (NTRS)

    Joachim, William F; Rothrock, A M

    1930-01-01

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

  18. 46 CFR 154.438 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type A § 154.438 Design vapor pressure. (a) If the surface of an independent tank type A...

  19. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.419 Section 154.419 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge...

  20. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.419 Section 154.419 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Integral Tanks § 154.419 Design vapor pressure....

  1. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type B...

  2. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.426 Section 154.426 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Membrane Tanks § 154.426 Design vapor pressure....

  3. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.426 Section 154.426 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Membrane Tanks § 154.426 Design vapor pressure....

  4. 46 CFR 154.438 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type A § 154.438 Design vapor pressure. (a) If the surface of an independent tank type A...

  5. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure. 154.436 Section 154.436 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS...-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5...

  6. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type B...

  7. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.419 Section 154.419 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge...

  8. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.436 Section 154.436 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS...-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5...

  9. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure. 154.426 Section 154.426 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge...

  10. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type B...

  11. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.419 Section 154.419 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Integral Tanks § 154.419 Design vapor pressure....

  12. 46 CFR 154.438 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Independent Tank Type A § 154.438 Design vapor pressure. (a) If the surface of an independent tank type A...

  13. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure. 154.426 Section 154.426 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge...

  14. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure. 154.419 Section 154.419 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge...

  15. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.436 Section 154.436 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS...-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5...

  16. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure. 154.426 Section 154.426 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge...

  17. High pressure chemistry of red phosphorus by photoactivated simple molecules

    NASA Astrophysics Data System (ADS)

    Ceppatelli, Matteo; Bini, Roberto; Fanetti, Samuele; Caporali, Maria; Peruzzini, Maurizio

    2013-06-01

    High pressure (HP) is very effective in reducing intermolecular distances and inducing unexpected chemical reactions. In particular the photoactivation of the reactants in HP conditions can lead to very efficient and selective processes. The chemistry of phosphorus is currently based on the white molecular form. The red polymeric allotrope, despite more stable and much less toxic, has not attracted much attention so far. However, switching from the white to the red form would benefit any industrial procedure, especially from an environmental point of view. On the other side, water and ethanol are renewable, environmental friendly and largely available molecules, usable as reactants and photoactivators in HP conditions. Here we report a study on the HP photoinduced reactivity of red phosphorus with water and ethanol, showing the possibility of very efficient and selective processes, leading to molecular hydrogen and valuable phosphorus compounds. The reactions have been studied by means of FTIR and Raman spectroscopy and pressure has been generated using DAC and SAC. HP reactivity has been activated by the two-photon absorption of near-UV wavelengths and occured in total absence of solvents, catalysts and radical initiators, at room T and mild pressure conditions (0.2-1.5 GPa).

  18. The hysteretic evapotranspiration - vapor pressure deficit relation

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  19. 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

  20. Controlling the vapor pressure of a mercury lamp

    DOEpatents

    Grossman, Mark W.; George, William A.

    1988-01-01

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

  1. 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.

  2. Controlling the vapor pressure of a mercury lamp

    DOEpatents

    Grossman, M.W.; George, W.A.

    1988-05-24

    The invention described herein discloses a method and apparatus for controlling the Hg vapor pressure within a lamp. This is done by establishing and controlling two temperature zones within the lamp. One zone is colder than the other zone. The first zone is called the cold spot. By controlling the temperature of the cold spot, the Hg vapor pressure within the lamp is controlled. Likewise, by controlling the Hg vapor pressure of the lamp, the intensity and linewidth of the radiation emitted from the lamp is controlled. 2 figs.

  3. 46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30.10-59...-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a liquid at a....01-3), Method of Test for Vapor Pressure of Petroleum Products. This Standard is available...

  4. 46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30.10-59...-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a liquid at a....01-3), Method of Test for Vapor Pressure of Petroleum Products. This Standard is available...

  5. 46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30.10-59...-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a liquid at a....01-3), Method of Test for Vapor Pressure of Petroleum Products. This Standard is available...

  6. 46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30.10-59...-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a liquid at a....01-3), Method of Test for Vapor Pressure of Petroleum Products. This Standard is available...

  7. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.436 Section 154.436 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Semi-Membrane Tanks § 154.436 Design vapor...

  8. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.436 Section 154.436 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Semi-Membrane Tanks § 154.436 Design vapor...

  9. 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)

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

    ERIC Educational Resources Information Center

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

    2007-01-01

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

  11. Evaluation of vapor intrusion using controlled building pressure.

    PubMed

    McHugh, Thomas E; Beckley, Lila; Bailey, Danielle; Gorder, Kyle; Dettenmaier, Erik; Rivera-Duarte, Ignacio; Brock, Samuel; MacGregor, Ian C

    2012-05-01

    The use of measured volatile organic chemical (VOC) concentrations in indoor air to evaluate vapor intrusion is complicated by (i) indoor sources of the same VOCs and (ii) temporal variability in vapor intrusion. This study evaluated the efficacy of utilizing induced negative and positive building pressure conditions during a vapor intrusion investigation program to provide an improved understanding of the potential for vapor intrusion. Pressure control was achieved in five of six buildings where the investigation program was tested. For these five buildings, the induced pressure differences were sufficient to control the flow of soil gas through the building foundation. A comparison of VOC concentrations in indoor air measured during the negative and positive pressure test conditions was sufficient to determine whether vapor intrusion was the primary source of VOCs in indoor air at these buildings. The study results indicate that sampling under controlled building pressure can help minimize ambiguity caused by both indoor sources of VOCs and temporal variability in vapor intrusion. PMID:22486634

  12. Autogenous pressurization of cryogenic vessels using submerged vapor injection

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  13. Plasma-assisted directed vapor deposition for synthesizing lithium phosphorus oxynitride thin films

    NASA Astrophysics Data System (ADS)

    Kim, Yoon Gu

    This dissertation explores a new vapor deposition route for synthesizing lithium phosphorus oxynitride (Lipon) thin-film electrolytes for rechargeable thin-film Li/Li-ion batteries. These batteries operate at a high voltage (around 4.0 V) and exhibit a long cyclic life (over 10,000 charge/discharge cycles). These features stem from the extremely low leakage current of the Lipon film electrolyte when in contact with a lithium anode, and its good Li-ion conductivity (in the 10-6-10-7 S/cm range). Lipon films have usually been synthesized by reactive RF-magnetron sputtering, which suffers from a very low deposition rate (˜2 nm/min). It therefore takes many hours to make the 1-2 mum thick films needed for battery applications. Other deposition approaches, such as Pulsed Laser Deposition, Ion Beam Assisted Deposition, and E-beam evaporation, have been investigated but resulted in unsatisfactory Lipon film performance. Here, a plasma-assisted directed vapor deposition (PA-DVD) approach has been explored to synthesize dense, amorphous Lipon films. Unlike conventional e-beam evaporation, the e-beam based DVD approach employs an annular nozzle to generate a rarefied supersonic inert gas jet around the periphery of an electron beam evaporated source material. The vapor is entrained in the jet and rapidly transferred to a substrate. Because the supersonic gas jet focuses the vapor (it impedes lateral spreading of the vapor flux), most of the evaporant reaches the substrate. As a result, the deposition rate of Lipon films can be potentially much higher than most other processes. The PA-DVD approach used here employs a hollow cathode to create low-energy plasma through which the vapor is propagated. This plasma ionized some of the evaporant and reactive gases (nitrogen) that were added to the jet. This increased their reactivity and atomic mobility on a substrate enabling the reactive synthesis of lithium phosphorus oxynitride from a lithium phosphate source. This dissertation

  14. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type C and Process Pressure...

  15. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type C and Process Pressure...

  16. A fast low-pressure transport route to large black phosphorus single crystals

    SciTech Connect

    Nilges, Tom Kersting, Marcel; Pfeifer, Thorben

    2008-08-15

    Black phosphorus, a promising candidate for lithium battery electrodes, can be prepared by a low-pressure transport reaction route representing the first effective and scalable access to this element modification. Crystal sizes larger than 1 cm were obtained at low-pressure conditions in silica ampoules. X-ray phase analyses, EDX, ICP-MS and optical microscopy were applied to characterize the resulting black phosphorus. The present method drastically improves the traditional preparation ways like mercury catalysis, bismuth-flux or high-pressure techniques and represents an easy, non-toxic, fast and highly efficient method to achieve black phosphorus. In contrast to a previously reported low-pressure route the present transport reaction allows an up-scaling to higher masses of starting materials, a larger black phosphorus yield and faster reaction time under retention of the high product crystallinity. - Graphical abstract: A low-pressure transport reaction route representing the first effective and scalable access to black phosphorus.

  17. 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.

  18. A new generalized correlation for accurate vapor pressure prediction

    NASA Astrophysics Data System (ADS)

    An, Hui; Yang, Wenming

    2012-08-01

    An accurate knowledge of the vapor pressure of organic liquids is very important for the oil and gas processing operations. In combustion modeling, the accuracy of numerical predictions is also highly dependent on the fuel properties such as vapor pressure. In this Letter, a new generalized correlation is proposed based on the Lee-Kesler's method where a fuel dependent parameter 'A' is introduced. The proposed method only requires the input parameters of critical temperature, normal boiling temperature and the acentric factor of the fluid. With this method, vapor pressures have been calculated and compared with the data reported in data compilation for 42 organic liquids over 1366 data points, and the overall average absolute percentage deviation is only 1.95%.

  19. Evaporation rate and vapor pressure of selected polymeric lubricating oils.

    NASA Technical Reports Server (NTRS)

    Gardos, M. N.

    1973-01-01

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

  20. Vapor Pressure of Aqueous Solutions of Ethylene Glycol

    NASA Astrophysics Data System (ADS)

    Fujita, Toshihiko; Kikuchi, Sakae

    Vapor pressures of aqueous solutions of ethylene glycol are measured in the range of temperature from -10 to 60°C and concentration from 20 to 50wt%. In a low concentration range, the measured values of vapor pressure decrease according to the Raoult's law independent of temperature, while in a high concentration range, they show a trend to decrease towards the estimated values of freezing point with decreasing temperature. The following correlation equation is obtained for practical calculations on heating towers and the like. log(p/P0) = 5.351 - 6.4×10-4y + (1817 + 0.008y(y + 10))/(t + 240) where p, vapor perssure of aqueous solutions of ethylene glycol [kPa] ; P0, atmospheric pressure [=101.325kPa] ; y, concentration [wt%] ; t, temperature [°C].

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

    SciTech Connect

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

    1982-06-01

    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 to obtain the partial pressures of O/sub 2/, O, Pu, PuO, and PuO/sub 2/. New thermodynamic functions for the solid oxide were calculated from available information and from new estimates of the heat capacity of the liquid. Thermodynamic functions for the vapor species were calculated previously. A suitable oxygen-potential model has been used previously for the solid hypostoichiometric plutonium dioxide; this model has been extended into the liquid region using several alternative methods. The effects of these alternatives on the calculated oxygen pressures have been examined in detail.

  2. Improved Magnus` form approximation of saturation vapor pressure

    SciTech Connect

    Alduchov, O.A.; Eskridge, R.E.

    1997-11-01

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

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

    SciTech Connect

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

    1982-01-01

    Vapor pressures and vapor compositions have been calculated for 1500 less than or equal to T less than or equal to 4000/sup 0/K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model extended into the liquid region to obtain the partial pressures of O/sub 2/, O, Pu, PuO and PuO/sub 2/. The calculated oxygen pressures increase very rapidly as stoichiometry is approached. At least part of this increase is a consequence of the exclusion of Pu/sup 6 +/ from the oxygen-potential model. No reliable method was found to estimate the importance of this ion. As a result of large oxygen potentials at high temperatures, extremely high total pressures that produced unreasonably high vapor densities were calculated. The highest temperature was therefore limited to 400 K, and the range of oxygen-to-metal ratios was limited to 1.994 to 1.70. These calculations show that vapor in equilibrium with hypostoichiometric plutonium dioxide is poorly approximated as PuO/sub 2/ for most of the temperture and composition range of interest. The vapor is much more oxygen-rich than the condensed phase. Implications for the (U,Pu)O/sub 2-x/ system are discussed. (DLC)

  4. Salinity-gradient vapor-pressure power conversion

    NASA Astrophysics Data System (ADS)

    Olsson, M. S.

    1982-03-01

    The interface between water bodies of different salinities represents a large unexploited source of energy. An energy conversion approach that does not require the use of membranes but uses the differences in vapor pressure between solutions is examined. The resource potential, source solutions, system components, and operating characteristics are evaluated and, where similar, compared to research and development on open-cycle OTEC (Ocean Thermal Energy Conversion). It is shown that salinity-gradient, vapor-pressure power generation is within reach of current technology.

  5. 46 CFR 154.438 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type A § 154.438 Design...

  6. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type B § 154.445 Design...

  7. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure. 154.445 Section 154.445 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type B § 154.445 Design...

  8. 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.

  9. New class of compounds have very low vapor pressures

    NASA Technical Reports Server (NTRS)

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

    1967-01-01

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

  10. 46 CFR 154.438 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure. 154.438 Section 154.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type A § 154.438 Design...

  11. Distillation device supplies cesium vapor at constant pressure

    NASA Technical Reports Server (NTRS)

    Basiulis, A.; Shefsiek, P. K.

    1968-01-01

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

  12. Vapor pressure of perfluoroalkylalkanes: the role of the dipole.

    PubMed

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

    2015-01-29

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

  13. Dynamic response of vaporizing droplet to pressure oscillation

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Shen, Chibing; Zhang, Xinqiao

    2016-06-01

    Combustion instability is a major challenge in the development of the liquid propellant engines, and droplet vaporization is viewed as a potential mechanism for driving instabilities. Based on the previous work, an unsteady droplet heating and vaporization model was developed. The model and numerical method are validated by experimental data available in literature, and then the oscillatory vaporization of n-Heptane droplet exposed to unsteady harmonic nitrogen atmosphere was numerically investigated over a wide range of amplitudes and frequencies. Also, temperature variations inside the droplet were demonstrated under oscillation environments. It was found that the thermal wave is attenuated with significantly reduced wave intensities as it penetrates deep into droplet from the ambient gas. Droplet surface temperature exhibits smaller fluctuation than that of the ambient gas, and it exhibits a time lag with regard to the pressure variation. Furthermore, the mechanism leading to phase lag of vaporization rate with respect to pressure oscillation was unraveled. Results show that this phase lag varies during the droplet lifetime and it is strongly influenced by oscillation frequency, indicating droplet vaporization is only capable of driving combustion instability in some certain frequency domains. Instead, the amplitude of the oscillation does not have very significant effects. It is noteworthy that thermal inertia of the droplet also plays a considerable role in determining the phase lag.

  14. Subatmospheric vapor pressures evaluated from internal-energy measurements

    SciTech Connect

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

    1997-01-01

    Vapor pressures were calculated from measured internal-energy changes in the vapor + liquid two-phase region, {Delta}U{sup (2)}. The method employed a thermodynamic relationship between the derivative quantity ({partial_derivative}U{sup (2)}/{partial_derivative}V){sub T} and the vapor pressure (p{sub {sigma}}) and its temperature derivative ({partial_derivative}p/{partial_derivative}T){sub {sigma}}. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 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{sub {sigma}} for this substance. It was also applied to evaluate published p{sub {sigma}} data which are in disagreement by more than their claimed uncertainty.

  15. Controlling Vapor Pressure In Hanging-Drop Crystallization

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Smith, Robbie

    1988-01-01

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

  16. Low temperature measurement of the vapor pressures of planetary molecules

    NASA Technical Reports Server (NTRS)

    Kraus, George F.

    1989-01-01

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

  17. Vapor pressure critical amplitudes from the normal boiling point

    NASA Astrophysics Data System (ADS)

    Velasco, S.; Román, F. L.; White, J. A.; Mulero, A.

    2007-04-01

    The authors propose a method to estimate the two first critical amplitudes for the vapor pressure of a fluid in terms only of the reduced pressure, Pbr=Pb/Pc, and temperature, Tbr=Tb/Tc, of the normal boiling point. The method is based on the fact that the product (1-Tr)Pr presents a maximum near the critical region. Based on a study of 43 fluids, the authors found that the reduced pressure and temperature of that maximum can be obtained from simple relations in terms of the parameter h ≡TbrlnPbr/(Tbr-1). These relations are checked against additional data for 1608 fluids.

  18. Solar radiation and water vapor pressure to forecast chickenpox epidemics.

    PubMed

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

    2015-03-01

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

  19. Vapor pressure and vapor fractionation of silicate melts of tektite composition

    USGS Publications Warehouse

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

    1964-01-01

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

  20. On Localized Vapor Pressure Gradients Governing Condensation and Frost Phenomena.

    PubMed

    Nath, Saurabh; Boreyko, Jonathan B

    2016-08-23

    Interdroplet vapor pressure gradients are the driving mechanism for several phase-change phenomena such as condensation dry zones, interdroplet ice bridging, dry zones around ice, and frost halos. Despite the fundamental nature of the underlying pressure gradients, the majority of studies on these emerging phenomena have been primarily empirical. Using classical nucleation theory and Becker-Döring embryo formation kinetics, here we calculate the pressure field for all possible modes of condensation and desublimation in order to gain fundamental insight into how pressure gradients govern the behavior of dry zones, condensation frosting, and frost halos. Our findings reveal that in a variety of phase-change systems the thermodynamically favorable mode of nucleation can switch between condensation and desublimation depending upon the temperature and wettability of the surface. The calculated pressure field is used to model the length of a dry zone around liquid or ice droplets over a broad parameter space. The long-standing question of whether the vapor pressure at the interface of growing frost is saturated or supersaturated is resolved by considering the kinetics of interdroplet ice bridging. Finally, on the basis of theoretical calculations, we propose that there exists a new mode of frost halo that is yet to be experimentally observed; a bimodal phase map is developed, demonstrating its dependence on the temperature and wettability of the underlying substrate. We hope that the model and predictions contained herein will assist future efforts to exploit localized vapor pressure gradients for the design of spatially controlled or antifrosting phase-change systems. PMID:27463696

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

    DOEpatents

    Grossman, Mark W.; Biblarz, Oscar

    1991-01-01

    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. Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

    2016-05-01

    The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

  3. 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.

  4. 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.

  5. Water vapor pressure should be addressed in Potomac study

    NASA Astrophysics Data System (ADS)

    Egan, Walter G.

    In Bruce Doe's article, “A Potomac Perspective on the Growing Global Greenhouse” (Eos, January 5,1999), a statement is made in the next to last paragraph that “other climatic parameters such as precipitation can correlate better than temperature among the five sites.” It would be expected that precipitation, and in particular the partial pressure of water vapor, should correlate with the carbon dioxide greenhouse effect. It was pointed out by W. G. Egan and coworkers in 1991 that there is an inverse relationship between carbon dioxide and water vapor partial pressure, seen both in laboratory experiments and at all worldwide Global Monitoring for Climate Change monitoring stations. Specific examples were presented for Cold Bay, Alaska and Palmer Station, Antarctica monthly and annually

  6. Vapor pressure measurements of LaGd alloys

    NASA Astrophysics Data System (ADS)

    Shoji, Yoshiyuki; Matsui, Tsuneo; Nakamura, Kinya; Inoue, Tadashi

    1997-08-01

    The vapor pressures of La(g) and Gd(g) over La xGd 1- x alloys ( x = 0.00, 0.12, 0.22, 0.45, 0.70, 0.74, 0.85, 1.00) were measured with a time-of-flight mass spectrometer equipped with a tungsten Knudsen cell over the temperature range 1588 to 1797 K. The chemical activities of lanthanum and gadolinium in the alloys were determined by comparing the vapor pressures of La(g) and Gd(g) over the alloys with those over the pure metals. The chemical activities, thus obtained, showed positive deviations from Raoult's law over the entire compositional range. The interatomic force between gadolinium and lanthanum was thought to be repulsive. The partial molar Gibbs free energy and the Gibbs free energy, enthalpy and entropy of formation were calculated from the activity values.

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

    NASA Technical Reports Server (NTRS)

    Marti, James; Mauersberger, Konrad

    1993-01-01

    New measurements of ice vapor pressures at temperatures between 170 and 250 K are presented and published vapor pressure data are summarized. An empirical vapor pressure equation was derived and allows prediction of vapor pressures between 170 k and the triple point of water with an accuracy of approximately 2 percent. Predictions obtained agree, within experimental uncertainty, with the most reliable equation derived from thermodynamic principles.

  8. Evaporation Rate and Saturated Vapor Pressure of Functional Organic Materials

    NASA Astrophysics Data System (ADS)

    Yase, Kiyoshi; Takahashi, Yoshikazu; Ara-kato, Norihiko; Kawazu, Akira

    1995-02-01

    The evaporation rate and saturated vapor pressure (p) for functional organic materials have been evaluated by thermogravimetry in vacuum. A series of metal phthalocyanines (M-Pc) such as Cu-Pc, Ni-Pc, Pb-Pc and TiO-Pc, Tris(8-hydroxy-quinoline) aluminum complex ( Alq3), fullerene (C60) and tetrathiafulvalene (TTF), tetracyanoquinodimethane (TCNQ) and TTF-TCNQ are examined, together with the relationship between p and the enthalpy of evaporation.

  9. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  10. 46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false High and low vapor pressure protection for tankships-T... CONTROL SYSTEMS Equipment and Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL. Each tankship with a vapor collection system must be fitted with a pressure-sensing...

  11. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  12. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  13. Chemical Vapor Deposition at High Pressure in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  14. 46 CFR 30.10-59 - Reid vapor pressure-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Reid vapor pressure-TB/ALL. 30.10-59 Section 30.10-59 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-59 Reid vapor pressure—TB/ALL. The term Reid vapor pressure means the vapor pressure of a liquid at a temperature of 100 °F., expressed in...

  15. 46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false High and low vapor pressure protection for tankships-T/ALL. 39.2013 Section 39.2013 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS VAPOR CONTROL SYSTEMS Equipment and Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL. Each tankship with a...

  16. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Pressure relief devices in gas/vapor service. 63.165 Section 63.165 Protection of Environment ENVIRONMENTAL PROTECTION...

  17. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  18. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  19. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure... 40 Protection of Environment 10 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 63.165 Section 63.165 Protection of Environment ENVIRONMENTAL PROTECTION...

  20. 40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., 2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas/vapor service shall be operated with no detectable emissions... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standards: Pressure relief devices...

  1. 40 CFR 60.482-4a - 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. (a) Except during pressure releases, each pressure... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4a Section 60.482-4a Protection of Environment ENVIRONMENTAL...

  2. 40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4a Section 60.482-4a Protection of Environment ENVIRONMENTAL...

  3. 40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., 2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas/vapor service shall be operated with no detectable emissions... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Standards: Pressure relief devices...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4a Section 60.482-4a Protection of Environment ENVIRONMENTAL...

  5. 40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., 2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas/vapor service shall be operated with no detectable emissions... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standards: Pressure relief devices...

  6. 40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., 2006 § 60.482-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas/vapor service shall be operated with no detectable emissions... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Pressure relief devices...

  7. 40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4a Section 60.482-4a Protection of Environment ENVIRONMENTAL...

  8. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Pressure relief devices in gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  9. Ignitability of DMSO vapors at elevated temperature and reduced pressure

    SciTech Connect

    Bergman, W; Ural, E A; Weisgerber, W

    1999-03-08

    Ignitability of DMSO vapors have been evaluated at 664 mm Hg pressure. The minimum temperature at which the DMSO vapors that are in equilibrium with liquid DMSO has been determined using two types of strong ignition sources. This temperature is 172 F for chemical igniters, and 178 F for spark ignition. Numerous tests have been conducted using controlled intensity sparks to define the shape of the minimum ignition energy curve as a function of temperature. The ignition energies spanned four orders of magnitude (approximately from 20,000 to 2 mJ) while the DMSO vapor mixture temperature varied from 185 to 207 F. The Sandia Generator was used to simulate worst case electrostatic sparks that can be produced by the human body. Although it was not designed for air discharges, this device had been used by LLNL for 1 mm spark gap and the resultant spark energy had been measured to fall within the range from 3.2 to 8.8 mJ. CRC tests using this device showed that the minimum ignition temperature strongly depends on the spark gap. The minimum ignition temperature was 207 F at 1 mm spark gap, 203 F at 3 mm spark gap, and 197 F at 6 mm spark gap. This strong dependence on the spark gap is believed to be partly due to the changes in the spark energy as the spark gap changes.

  10. Precision ozone calibration system based on vapor pressures of ozone

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  11. Hydrostatic pressure induced three-dimensional Dirac semimetal in black phosphorus

    NASA Astrophysics Data System (ADS)

    Gong, Peng-Lai; Liu, Da-Yong; Yang, Kai-Shuai; Xiang, Zi-Ji; Chen, Xian-Hui; Zeng, Zhi; Shen, Shun-Qing; Zou, Liang-Jian

    2016-05-01

    We present the first-principles studies on the hydrostatic pressure effect of the electronic properties of black phosphorus. We show that the energy bands crossover around the critical pressure Pc=1.23 GPa; with increasing pressure, the band reversal occurs at the Z point and evolves into 4 twofold-degenerate Dirac cones around the Z point, suggesting that pressured black phosphorus is a 3D Dirac semimetal. With further increasing pressure the Dirac cones in the Γ -Z line move toward the Γ point and evolve into two hole-type Fermi pockets, and those in the Z -M lines move toward the M point and evolve into two tiny electron-type Fermi pockets, and a band above the Z -M line sinks below EF and contributes four electron-type pockets. A clear Lifshitz transition occurs at Pc from semiconductor to 3D Dirac semimetal. Such a 3D Dirac semimetal is protected by the nonsymmorphic space symmetry of bulk black phosphorus. These suggest the bright perspective of black phosphorus for optoelectronic and electronic devices due to its easy modulation by pressure.

  12. 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.

  13. 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.

  14. 46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Gauges and vapor return for cargo vapor pressures... COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia). When table 1 references...

  15. 46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Gauges and vapor return for cargo vapor pressures... COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.372 Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia). When table 1 references...

  16. Temperature/pressure and water vapor sounding with microwave spectroscopy

    NASA Technical Reports Server (NTRS)

    Muhleman, D. O.; Janssen, M. A.; Clancy, R. T.; Gulkis, S.; Mccleese, D. J.; Zurek, R.; Haberle, R. M.; Frerking, M.

    1992-01-01

    Two intense microwave spectra lines exist in the martian atmosphere that allow unique sounding capabilities: water vapor at 183 GHz and the (2-1) rotational line of CO at 230 GHz. Microwave spectra line sounding is a well-developed technique for the Earth's atmosphere for sounding from above from spacecraft and airplanes, and from below from fixed surface sites. Two simple instruments for temperature sounding on Mars (the CO line) and water vapor measurements are described. The surface sounder proposed for the MESUR sites is designed to study the boundary layer water vapor distribution and the temperature/pressure profiles with vertical resolution of 0.25 km up to 1 km with reduced resolution above approaching a scale height. The water channel will be sensitive to a few tenths of a micrometer of water and the temperature profile will be retrieved to an accuracy between 1 and 2 K. The latter is routinely done on the Earth using oxygen lines near 60 GHz. The measurements are done with a single-channel heterodyne receiver looking into a 10-cm mirror that is canned through a range of elevation angles plus a target load. The frequency of the receiver is sweep across the water and CO lines generating the two spectra at about 1-hr intervals throughout the mission. The mass and power for the proposed instrument are 2 kg and 5-8 W continuously. The measurements are completely immune to the atmospheric dust and ice particle loads. It was felt that these measurements are the ultimate ones to properly study the martian boundary layer from the surface to a few kilometers. Sounding from above requires an orbiting spacecraft with multichannel microwave spectrometers such as the instrument proposed for MO by a subset of the authors, a putative MESUR orbiter, and a proposed Discovery mission called MOES. Such an instrument can be built with less than 10 kg and use less than 15 W. The obvious advantage of this approach is that the entire atmosphere can be sounded for temperature and

  17. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  18. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  19. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... § 63.1030 Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The... section, each pressure relief device in gas and vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Pressure relief devices in gas...

  20. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas... 40 Protection of Environment 8 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 61.242-4 Section 61.242-4 Protection of Environment ENVIRONMENTAL PROTECTION...

  1. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... § 63.1030 Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The... section, each pressure relief device in gas and vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Pressure relief devices in gas...

  2. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in gas... 40 Protection of Environment 9 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 61.242-4 Section 61.242-4 Protection of Environment ENVIRONMENTAL PROTECTION...

  3. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The owner or operator... section, each pressure relief device in gas or vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Pressure relief devices in gas...

  4. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The owner or operator... section, each pressure relief device in gas or vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Pressure relief devices in gas...

  5. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Pressure relief devices in gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION...

  6. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... § 63.1030 Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The... section, each pressure relief device in gas and vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Pressure relief devices in gas...

  7. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The owner or operator... section, each pressure relief device in gas or vapor service shall be operated with an instrument reading... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Pressure relief devices in gas...

  8. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 63.1030 Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The... section, each pressure relief device in gas and vapor service shall be operated with an instrument reading... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Pressure relief devices in gas...

  9. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Pressure relief devices in gas and vapor service standards. (a) Compliance schedule. The owner or operator... section, each pressure relief device in gas or vapor service shall be operated with an instrument reading... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Pressure relief devices in gas...

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

    SciTech Connect

    Suuberg, E.M.

    1995-10-01

    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, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. Both the gas saturation method and the Knudsen effusion method are being used. Results are presented for anthracene, naphthacene, pentacene, and a mixture of anthracene and perylene obtained using the effusion method.

  11. The vapor pressures of solid and liquid ozone

    NASA Technical Reports Server (NTRS)

    Hanson, David; Mauersberger, Konrad

    1986-01-01

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

  12. Molecular weight of aquatic fulvic acids by vapor pressure osmometry

    USGS Publications Warehouse

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

    1987-01-01

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

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

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false High and low vapor pressure protection for tankships-T... VAPOR CONTROL SYSTEMS Design and Equipment § 39.20-13 High and low vapor pressure protection for tankships—T/ALL. Each tankship vapor collection system must be fitted with a pressure sensing device...

  14. 46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false High and low vapor pressure protection for tankships-T... VAPOR CONTROL SYSTEMS Design and Equipment § 39.20-13 High and low vapor pressure protection for tankships—T/ALL. Each tankship vapor collection system must be fitted with a pressure sensing device...

  15. 46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false High and low vapor pressure protection for tankships-T... VAPOR CONTROL SYSTEMS Design and Equipment § 39.20-13 High and low vapor pressure protection for tankships—T/ALL. Each tankship vapor collection system must be fitted with a pressure sensing device...

  16. Pressure-induced zigzag phosphorus chain and superconductivity in boron monophosphide

    PubMed Central

    Zhang, Xinyu; Qin, Jiaqian; Liu, Hanyu; Zhang, Shiliang; Ma, Mingzhen; Luo, Wei; Liu, Riping; Ahuja, Rajeev

    2015-01-01

    We report on the prediction of the zinc-blende structure BP into a novel C2/m phase from 113 to 208 GPa which possesses zigzag phosphorus chain structure, followed by another P42/mnm structure above 208 GPa above using the particle-swarm search method. Strong electron-phonon coupling λ in compressed BP is found, in particular for C2/m phase with the zigzag phosphorus chain, which has the highest λ (0.56–0.61) value among them, leading to its high superconducting critical temperature Tc (9.4 K–11.5 K), which is comparable with the 4.5 K to 13 K value of black phosphorus phase I (orthorhombic, Cmca). This is the first system in the boron phosphides which shows superconductivity from the present theoretical calculations. Our results show that pressure-induced zigzag phosphorus chain in BP exhibit higher superconducting temperature TC, opening a new route to search and design new superconductor materials with zigzag phosphorus chains. PMID:25737341

  17. Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

    NASA Technical Reports Server (NTRS)

    Nash, W. P.; Hausel, W. D.

    1973-01-01

    Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

  18. Melt-vapor phase transition in the lead-selenium system at atmospheric and low pressure

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The boiling temperature and the corresponding vapor phase composition in the existence domain of liquid solutions were calculated from the partial pressures of saturated vapor of the components and lead selenide over liquid melts in the lead-selenium system. The phase diagram was complemented with the liquid-vapor phase transition at atmospheric pressure and in vacuum of 100 Pa, which allowed us to judge the behavior of the components during the distillation separation.

  19. 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.

  20. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Compliance schedule. The owner or operator shall comply... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 65.111 Section 65.111 Protection of Environment ENVIRONMENTAL PROTECTION...

  1. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 65.111 Section 65.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service....

  2. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Compliance schedule. The owner or operator shall comply... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Standards: Pressure relief devices in gas/vapor service. 65.111 Section 65.111 Protection of Environment ENVIRONMENTAL PROTECTION...

  3. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...: Pressure relief devices in gas/vapor service. (a) Compliance schedule. The owner or operator shall comply... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 65.111 Section 65.111 Protection of Environment ENVIRONMENTAL PROTECTION...

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

    SciTech Connect

    Rudeen, David Keith; 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

  5. Atmospheric pressure plasma-initiated chemical vapor deposition (AP-PiCVD) of poly(diethylallylphosphate) coating: a char-forming protective coating for cellulosic textile.

    PubMed

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

    2014-01-01

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

  6. Hydrogen bonding and vapor pressure isotope effect of deuterioisomeric methanethiols

    SciTech Connect

    Wolff, H.; Szydlowski, J.; Dill-Staffenberger, L.

    1981-04-16

    Wilson parameters, activity coefficients, association constants, and other thermodynamic functions which are derived from isothermal vapor pressure measurements between 223 and 293 K for binary mixtures of CH/sub 3/SH, CH/sub 3/SD, CS/sub 3/SH, and CD/sub 3/SD with n-hexane show the weakness of the hydrogen and the deuterium bonds of methanethiol. As far as these functions depend on the association model used for the calculation, the relation of their values to those obtained for the corresponding amines and alcohols under the same conditions attests the weak methanethiol association. While for the more strongly associated methylamines and methanols a greater energy of the deuterium bond compared to the hydrogen bond has clearly been observed, the differences between the thermodynamic functions of the systems with the SH compounds and of those with the SD compounds are insignificant. This observation as well as the fact that the vapor pressure ratios P-(CH/sub 3/SD)/P(CH/sub 3/SH) are only slightly greater than unity, that the ratios P(CD/sub 3/SD)/P(CH/sub 3/SH) are even greater than P(CD/sub 3/SH)/P(CH/sub 3/SH), and that the changes of these ratios with temperature and dilution are small in comparison to the strong increase of the corresponding quotients of the methylamines and the methanols are the consequence of the weak methanethiol association. P(CH/sub 3/SD)/P(CH/sub 3/SH), P(CD/sub 3/SH)/P(CH/sub 3/SH), and P(CD/sub 3/SD)/P(CH/sub 3/SH) are represented by equations of the type ln P/sub D/ P/sub H/ = -A/T/sup 2/ + B/T where A and B are nearly additive. The low values of A and B for CH/sub 3/SD/CH/sub 3/SH in comparison to the high values for CH/sub 3/ND/sub 2//CH/sub 3/NH/sub 2/ and CH/sub 3/OD/CH/sub 3/OH reflect the weakness of the methanethiol hydrogen bonds. The constants can be related to the thermochemical and the spectroscopic data reported in the literature.

  7. 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 (μg 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

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  9. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, July 1--September 30, 1995

    SciTech Connect

    Suuberg, E.M.

    1995-12-31

    There is significant current interest in general area of coal pyrolysis, particularly because of the central role of pyrolysis in all thermally driven coal conversion processes-gasification, combustion, liquefaction, mild gasification, or thermal beneficiation. There remain several key data needs in these application areas. Among them is a need for more reliable correlation for prediction of vapor pressure of heavy, primary coal tars. The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to extending the work on measurements of vapor pressures of tars. For this purpose, cellulose tar and cellulose tar related compounds have been selected as model systems. Cellulose tar has a much narrower distribution of molecular weight than does coal tar, and it is much more homogeneous. Thus it is better to develop the methods to be used for coal tars on this simpler model system first.

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

    SciTech Connect

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

    2010-05-01

    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 the environment and assure worker safety and public health from crude oil vapor emissions. The annual report reviews key program areas ncluding monitoring program status, mitigation program status, new developments in measurements and modeling, and path forward including specific recommendations on cavern sampling for the next year. The contents of this report were first presented to SPR senior anagement in December 2009, in a deliverable from the vapor pressure committee. The current SAND report is an adaptation for the Sandia technical audience.

  11. High pressure chemistry of red phosphorus by photo-activated simple molecules

    NASA Astrophysics Data System (ADS)

    Ceppatelli, M.; Fanetti, S.; Bini, R.; Caporali, M.; Peruzzini, M.

    2014-05-01

    High pressure (HP) is very effective in reducing intermolecular distances and inducing unexpected chemical reactions. In addition the photo-activation of the reactants in HP conditions can lead to very efficient and selective processes. The chemistry of phosphorus is currently based on the white molecular form. The red polymeric allotrope, despite more stable and much less toxic, has not attracted much attention so far. However, switching from the white to the red form would benefit any industrial procedure, especially from an environmental point of view. On the other side, water and ethanol are renewable, environmental friendly and largely available molecules, usable as reactants and photo-activators in HP conditions. Here we report a study on the HP photo-induced reactivity of red phosphorus with water and ethanol, showing the possibility of very efficient and selective processes, leading to molecular hydrogen and valuable phosphorus compounds. The reactions have been studied by means of FTIR and Raman spectroscopy and pressure has been generated using membrane Diamond (DAC) and Sapphire (SAC) anvil cells. HP reactivity has been activated by the two-photon absorption of near-UV wavelengths and occurred in total absence of solvents, catalysts and radical initiators, at room T and mild pressure conditions (0.2-1.5 GPa).

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

    NASA Technical Reports Server (NTRS)

    Eshleman, Von R.

    1989-01-01

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

  13. Accurate determination of the vapor pressure of potassium using optical absorption

    NASA Technical Reports Server (NTRS)

    Shirinzadeh, B.; Wang, C. C.

    1983-01-01

    The vapor pressure of potassium has been measured in absorption using a CW tunable laser and calibrated against the accurate radiative lifetime of the 4s-4p doublet of potassium. An accurate value of 20,850 + or - 30 cal/mol for the heat of vaporization (from the liquid phase) at the melting point was determined.

  14. Saturated vapor pressure above the amalgam of alkali metals in discharge lamps

    NASA Astrophysics Data System (ADS)

    Gavrish, S. V.

    2011-12-01

    A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

  15. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Standards: Pressure relief devices in gas/vapor service. 65.111 Section 65.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... device in gas/vapor service shall be operated with an instrument reading of less than 500 parts...

  16. Vapor Pressure of Hexamethylene Triperoxide Diamine (HMTD) Estimated Using Secondary Electrospray Ionization Mass Spectrometry.

    PubMed

    Aernecke, Matthew J; Mendum, Ted; Geurtsen, Geoff; Ostrinskaya, Alla; Kunz, Roderick R

    2015-11-25

    A rapid method for vapor pressure measurement was developed and used to derive the vapor pressure curve of the thermally labile peroxide-based explosive hexamethylene triperoxide diamine (HMTD) over the temperature range from 28 to 80 °C. This method uses a controlled flow of vapor from a solid-phase HMTD source that is presented to an ambient-pressure-ionization mass spectrometer equipped with a secondary-electrospray-ionization (SESI) source. The subpart-per-trillion sensitivity of this system enables direct detection of HMTD vapor through an intact [M + H](+) ion in real time at temperatures near 20 °C. By calibrating this method using vapor sources of cocaine and heroin, which have known pressure-temperature (P-T) curves, the temperature dependence of HMTD vapor was determined, and a Clausius-Clapeyron plot of ln[P (Pa)] vs 1/[T (K)] yielded a straight line with the expression ln[P (Pa)] = {(-11091 ± 356) × 1/[T (K)]} + 25 ± 1 (error limits are the standard error of the regression analysis). From this equation, the sublimation enthalpy of HMTD was estimated to be 92 ± 3 kJ/mol, which compares well with the theoretical estimate of 95 kJ/mol, and the vapor pressure at 20 °C was estimated to be ∼60 parts per trillion by volume, which is within a factor of 2 of previous theoretical estimates. Thus, this method provides not only the first direct experimental determination of HMTD vapor pressure but also a rapid, near-real-time capability to quantitatively measure low-vapor-pressure compounds, which will be useful for aiding in the development of training aids for bomb-sniffing canines. PMID:26505487

  17. Characterization of phosphorus segregation in neutron-irradiated pressure vessel steels by atom probe field ion microscopy

    SciTech Connect

    Miller, M.K.; Jayaram, R.; Russell, K.F.

    1995-04-01

    An atom probe field ion microscopy characterization of A533B and Russian VVER 440 and 1000 pressure vessel steels has been performed to determine the phosphorus coverage of grain and lath boundaries. Field ion micrographs of grain and lath boundaries have revealed that they are decorated with a semi-continuous film of discrete brightly-imaging precipitates that were identified as molybdenum carbonitride precipitates. In addition, extremely high phosphorus levels were measured at the boundaries. The phosphorus segregation was found to be confined to an extremely narrow region indicative of monolayer-type segregation. The phosphorus coverages determined from the atom probe results of the unirradiated materials were in excellent agreement with predictions based on McLean`s equilibrium model of grain boundary segregation. The boundary phosphorus coverage of a neutron-irradiated weld material was significantly higher than that observed in the unirradiated material.

  18. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... pressure release and being returned to organic HAP service, the pressure relief device shall be monitored... release, a rupture disk shall be installed upstream of the pressure relief device as soon as practicable... relief device in gas/vapor service shall be operated with an instrument reading of less than 500...

  19. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  1. Liquid-propellant droplet vaporization and combustion in high pressure environments

    NASA Technical Reports Server (NTRS)

    Yang, Vigor

    1991-01-01

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

  2. 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.

  3. Vapor pressures and gas-phase PVT data for 1,1,1,2-tetrafluoroethane

    SciTech Connect

    Weber, L.A. )

    1989-05-01

    The authors present new data for the vapor pressure and PVT surface of 1,1,1,2-tetrafluoroethane (Refrigerant 134a) in the temperature range 40{degree}C (313 K) to 150{degree}C (423 K). The PVT data are for the gas phase at densities up to one-half critical. Densities of the saturated vapor are derived at five temperatures from the intersections of the experimental isochores with the vapor pressure curve. The data are represented analytically in order to demonstrate experimental precision and to facilitate calculation of thermodynamic properties.

  4. The Dynamics of Vapor Bubbles in Acoustic Pressure Fields

    NASA Technical Reports Server (NTRS)

    Hao, Y.; Prosperetti, A.

    1999-01-01

    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 size-if one exists at all-is found to require far more than several tens of thousands of cycles. It is also found that some small bubbles may grow or collapse depending on the phase of the sound field. The model accounts in detail for the thermo-fluid-mechanic processes in the vapor. In the second part of the paper, an approximate formulation valid for bubbles small with respect to the thermal penetration length in the vapor is derived and its accuracy examined, The present findings have implications for acoustically enhanced boiling heat transfer and other special applications such as boiling in microgravity.

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

    SciTech Connect

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

    2009-07-01

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

  6. Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method

    NASA Technical Reports Server (NTRS)

    Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor)

    2014-01-01

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

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

    DOEpatents

    Smith, Michael W; Jordan, Kevin C

    2014-03-25

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

  8. High Pressure Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Films and Solar Cells.

    PubMed

    He, Rongrui; Day, Todd D; Sparks, Justin R; Sullivan, Nichole F; Badding, John V

    2016-07-01

    Thin films of hydrogenated amorphous silicon can be produced at MPa pressures from silane without the use of plasma at temperatures as low as 345 °C. High pressure chemical vapor deposition may open a new way to low cost deposition of amorphous silicon solar cells and other thin film structures over very large areas in very compact, simple reactors. PMID:27174318

  9. Effects of growth pressure on morphology of ZnO nanostructures by chemical vapor transport

    NASA Astrophysics Data System (ADS)

    Babu, Eadi Sunil; Kim, Sungjin; Song, Jung-Hoon; Hong, Soon-Ku

    2016-08-01

    The effect of growth pressure on the morphology of the ZnO nanostructures in chemical vapor transport by using Zn powder and oxygen as source materials has been investigated. Highly uniform aligned ZnO nanorods or multifaceted tripod structures were grown depending on the growth pressure. The mechanism governing the morphology change was explained by the relative concentration of Zn vapor and supersaturation based on experimental observations. It was concluded that heterogeneous nucleation on the substrate is enhanced at low growth pressure, while homogeneous nucleation from vapor phase is enhanced at high growth pressure. The difference resulted in different morphology of ZnO nanostructures. ZnO nanorods grown at optimized condition were used for the fabrication of gas sensor for the detection of H2 gas.

  10. 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

  11. Vapor Pressure of Aqueous Solutions of Electrolytes Reproduced with Coarse-Grained Models without Electrostatics.

    PubMed

    Perez Sirkin, Yamila A; Factorovich, Matías H; Molinero, Valeria; Scherlis, Damian A

    2016-06-14

    The vapor pressure of water is a key property in a large class of applications from the design of membranes for fuel cells and separations to the prediction of the mixing state of atmospheric aerosols. Molecular simulations have been used to compute vapor pressures, and a few studies on liquid mixtures and solutions have been reported on the basis of the Gibbs Ensemble Monte Carlo method in combination with atomistic force fields. These simulations are costly, making them impractical for the prediction of the vapor pressure of complex materials. The goal of the present work is twofold: (1) to demonstrate the use of the grand canonical screening approach ( Factorovich , M. H. J. Chem. Phys. 2014 , 140 , 064111 ) to compute the vapor pressure of solutions and to extend the methodology for the treatment of systems without a liquid-vapor interface and (2) to investigate the ability of computationally efficient high-resolution coarse-grained models based on the mW monatomic water potential and ions described exclusively with short-range interactions to reproduce the relative vapor pressure of aqueous solutions. We find that coarse-grained models of LiCl and NaCl solutions faithfully reproduce the experimental relative pressures up to high salt concentrations, despite the inability of these models to predict cohesive energies of the solutions or the salts. A thermodynamic analysis reveals that the coarse-grained models achieve the experimental activity coefficients of water in solution through a compensation of severely underestimated hydration and vaporization free energies of the salts. Our results suggest that coarse-grained models developed to replicate the hydration structure and the effective ion-ion attraction in solution may lead to this compensation. Moreover, they suggest an avenue for the design of coarse-grained models that accurately reproduce the activity coefficients of solutions. PMID:27196963

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  14. Application of quantitative structure-property relationship analysis to estimate the vapor pressure of pesticides.

    PubMed

    Goodarzi, Mohammad; Coelho, Leandro dos Santos; Honarparvar, Bahareh; Ortiz, Erlinda V; Duchowicz, Pablo R

    2016-06-01

    The application of molecular descriptors in describing Quantitative Structure Property Relationships (QSPR) for the estimation of vapor pressure (VP) of pesticides is of ongoing interest. In this study, QSPR models were developed using multiple linear regression (MLR) methods to predict the vapor pressure values of 162 pesticides. Several feature selection methods, namely the replacement method (RM), genetic algorithms (GA), stepwise regression (SR) and forward selection (FS), were used to select the most relevant molecular descriptors from a pool of variables. The optimum subset of molecular descriptors was used to build a QSPR model to estimate the vapor pressures of the selected pesticides. The Replacement Method improved the predictive ability of vapor pressures and was more reliable for the feature selection of these selected pesticides. The results provided satisfactory MLR models that had a satisfactory predictive ability, and will be important for predicting vapor pressure values for compounds with unknown values. This study may open new opportunities for designing and developing new pesticide. PMID:26890190

  15. Modeling atomization processes in high-pressure vaporizing sprays

    NASA Astrophysics Data System (ADS)

    Reitz, Rolf D.

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

  16. Vapor pressure of ionic liquids at low temperatures from AC-chip-calorimetry.

    PubMed

    Ahrenberg, Mathias; Beck, Martin; Neise, Christin; Keßler, Olaf; Kragl, Udo; Verevkin, Sergey P; Schick, Christoph

    2016-08-01

    The very low vapor pressure of ionic liquids is challenging to measure. At elevated temperatures the liquids might start to decompose, and at relatively low temperatures the vapor pressure becomes too low to be measured by conventional methods. In this work we developed a highly sensitive method for mass loss determination at temperatures starting from 350 K. This technique is based on an alternating current calorimeter equipped with a chip sensor that consists of a free-standing SiNx-membrane (thickness <1 μm) and a measuring area with lateral dimensions of the order of 1 mm. A small droplet (diameter ca. 600 μm) of an ionic liquid is vaporized isothermally from the chip sensor in a vacuum-chamber. The surface-to-volume-ratio of such a droplet is large and the relative mass loss due to evaporation is therefore easy to monitor by the changing heat capacity (J K(-1)) of the remaining liquid. The vapor pressure is determined from the measured mass loss rates using the Langmuir equation. The method was successfully tested for the determination of the vapor pressure and the vaporization enthalpy of an archetypical ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][NTf2]). The data set created in this way in an extremely broad temperature range from 358 K to 780 K has allowed the estimation of the boiling temperature of [EMIm][NTf2]. The value (1120 ± 50) K should be considered as the first reliable boiling point of the archetypical ionic liquid obtained from experimental vapor pressures measured in the most possible close proximity to the normal boiling temperature. PMID:27425628

  17. Effects of FeNi-phosphorus-carbon system on crystal growth of diamond under high pressure and high temperature conditions

    NASA Astrophysics Data System (ADS)

    Hu, Mei-Hua; Bi, Ning; Li, Shang-Sheng; Su, Tai-Chao; Zhou, Ai-Guo; Hu, Qiang; Jia, Xiao-Peng; Ma, Hong-An

    2015-03-01

    This paper reports the crystal growth of diamond from the FeNi-Carbon system with additive phosphorus at high pressures and high temperatures of 5.4-5.8 GPa and 1280-1360 °C. Attributed to the presence of additive phosphorus, the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the FeNi-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications. Project supported by the Doctoral Fund of Henan Polytechnic University, China (Grant Nos. B2013-013 and B2013-044) and the Research Projects of Science and Technology of the Education Department of Henan Province, China (Grant Nos. 14B430026 and 12A430010).

  18. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... pressure of the remediation material: (i) Method 25E in 40 CFR part 60 appendix A; (ii) Methods described... vapor pressure of my remediation material? 63.7944 Section 63.7944 Protection of Environment... Pollutants: Site Remediation Performance Tests § 63.7944 How do I determine the maximum HAP vapor pressure...

  19. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... pressure of the remediation material: (i) Method 25E in 40 CFR part 60 appendix A; (ii) Methods described... vapor pressure of my remediation material? 63.7944 Section 63.7944 Protection of Environment... Pollutants: Site Remediation Performance Tests § 63.7944 How do I determine the maximum HAP vapor pressure...

  20. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pressure of the remediation material: (i) Method 25E in 40 CFR part 60 appendix A; (ii) Methods described... vapor pressure of my remediation material? 63.7944 Section 63.7944 Protection of Environment... Pollutants: Site Remediation Performance Tests § 63.7944 How do I determine the maximum HAP vapor pressure...

  1. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... pressure of the remediation material: (i) Method 25E in 40 CFR part 60 appendix A; (ii) Methods described... vapor pressure of my remediation material? 63.7944 Section 63.7944 Protection of Environment... Pollutants: Site Remediation Performance Tests § 63.7944 How do I determine the maximum HAP vapor pressure...

  2. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... pressure of the remediation material: (i) Method 25E in 40 CFR part 60 appendix A; (ii) Methods described... vapor pressure of my remediation material? 63.7944 Section 63.7944 Protection of Environment... Pollutants: Site Remediation Performance Tests § 63.7944 How do I determine the maximum HAP vapor pressure...

  3. 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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    Factorovich, Matías H.; Scherlis, Damián A.

    2014-02-14

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

  6. Vapor Pressure of R12/Oil and R22/Oil Mixtures

    NASA Astrophysics Data System (ADS)

    Takaishi, Yoshinori; Oguchi, Kosei

    The paper describes measurements of vapor pressures for R 12/0il and R 22/0il mixtures. Refrigeration oil employed in the present study is an alkyl benzene base synthetic oil. The measurements have been carried out in the range of temperatures between 283.15 K and 333.15 K for both R 12/0il and R 22/0il mixtures using the same refrigeration oil. Correlations that interpolate the experimental vapor pressures with average pressure deviations of 0.21% for R 12/0il system and 0.42% for R 22/0il system have been reported. Furthermore, a calculation method based on a theory of vapor-liquid phase equilibrium has been tested for the systems using the present experimental data.

  7. Structure of liquid phosphorus: A liquid-liquid phase transition via constant-pressure first-principles molecular dynamics

    NASA Astrophysics Data System (ADS)

    Morishita, Tetsuya

    2001-12-01

    Constant-pressure first-principles molecular dynamics simulations have been carried out to study structural phase transitions of liquid black phosphorus. By compressing the tetrahedral molecular liquid (a low-pressure phase), a structural phase transition from the molecular to polymeric liquid (a high-pressure phase) was successfully realized just as observed in the recent experiment by Katayama et al. [Nature 170 (2000) 403]. Structural properties in the polymeric liquid were investigated and it is found that the covalent p-state bonds are dominant within the first nearest neighbors of each atom. However, further compression of the polymeric liquid shows that the covalent bonding is weakened as pressure is increased. As a result, liquid phosphorus becomes similar to the simple liquid in which atoms form a close-packed structure at very high pressure.

  8. 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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  10. Critical parameters and vapor pressure measurements for 1,1,1-trifluoroethane (R-143a)

    SciTech Connect

    Fujiwara, K.; Nakamura, S.; Noguchi, M.

    1998-01-01

    An apparatus to measure the critical pressure, density, and temperature by visual observation of the meniscus in an optical cell is presented. The critical parameters and vapor pressures for 1,1,1,2-tetrafluoroethane (R-134a) were measured to confirm the reliability of the measurements with the present apparatus. The critical pressure, density, and temperature of 1,1,1-trifluoroethane (R-143a) were determined to be 3.7639 MPa, 434 kg/m{sup 3}, and 345.861 K, respectively. Thirteen vapor pressures of R-143a were obtained at temperatures from 263 K to the critical temperature. The uncertainties of pressure, density, and temperature measurements are estimated to be within {+-} 2.6 kPa, {+-} 2 kg/m{sup 3}, and {+-} 6 mK, respectively.

  11. Relationship between the evaporation rate and vapor pressure of moderately and highly volatile chemicals.

    PubMed

    van Wesenbeeck, Ian; Driver, Jeffrey; Ross, John

    2008-04-01

    Volatilization of chemicals can be an important form of dissipation in the environment. Rates of evaporative losses from plant and soil surfaces are useful for estimating the potential for food-related dietary residues and operator and bystander exposure, and can be used as source functions for screening models that predict off-site movement of volatile materials. A regression of evaporation on vapor pressure from three datasets containing 82 pesticidal active ingredients and co-formulants, ranging in vapor pressure from 0.0001 to >30,000 Pa was developed for this purpose with a regression correlation coefficient of 0.98. PMID:18344074

  12. Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions.

    PubMed

    Kiyosawa, Keitaro

    2003-05-01

    For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit. Measurement of the osmotic pressure of plants under water stress has been mainly based on vapor pressure deficit. However, differences have been noted for osmotic pressure values of aqueous polyethylene glycol (PEG) solutions measured by freezing point depression and vapor pressure deficit. For this paper, the physicochemical basis of freezing point depression and vapor pressure deficit were first examined theoretically and then, the osmotic pressure of aqueous ethylene glycol and of PEG solutions were measured by both freezing point depression and vapor pressure deficit in comparison with other aqueous solutions such as NaCl, KCl, CaCl(2), glucose, sucrose, raffinose, and bovine serum albumin (BSA) solutions. The results showed that: (1) freezing point depression and vapor pressure deficit share theoretically the same physicochemical basis; (2) theoretically, they are proportional to the molal concentration of the aqueous solutions to be measured; (3) in practice, the osmotic pressure levels of aqueous NaCl, KCl, CaCl(2), glucose, sucrose, and raffinose solutions increase in proportion to their molal concentrations and there is little inconsistency between those measured by freezing point depression and vapor pressure deficit; (4) the osmotic pressure levels of aqueous ethylene glycol and PEG solutions measured by freezing point depression differed from the values measured by vapor pressure deficit; (5) the osmotic pressure of aqueous BSA solution measured by freezing point depression differed slightly from that measured by vapor pressure deficit. PMID:12834836

  13. Pressure-dependent structures of amorphous red phosphorus and the origin of first sharp diffraction peaks.

    NASA Astrophysics Data System (ADS)

    Zaug, Joseph; Soper, Alan; Clark, Simon

    2009-03-01

    Characterizing the nature of medium range order (MRO) in liquids and disordered solids is important for understanding their structure and transport properties. However, accurately portraying MRO, as manifested by the first sharp diffraction peak (FSDP) in neutron and X-ray scattering measurements, has remained elusive for more than 80 years. Here, using X-ray diffraction of amorphous red phosphorus (a-rP) compressed to 6.30 GPa, supplemented with micro-Raman scattering studies, we build three-dimensional structural models consistent with the diffraction data. We discover that the pressure dependence of the FSDP intensity and line position can be quantitatively accounted for by a characteristic void distribution function, defined in terms of average void-size, void-spacing, and void-density. This work provides a template to unambiguously interpret atomic and void-space MRO across a broad range of technologically promising network-forming materials.

  14. 46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia). 153.372 Section 153.372 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design...

  15. 46 CFR 153.372 - Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Gauges and vapor return for cargo vapor pressures exceeding 100 kPa (approx. 14.7 psia). 153.372 Section 153.372 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design...

  16. Communication: Dynamical and structural analyses of solid hydrogen under vapor pressure

    SciTech Connect

    Hyeon-Deuk, Kim; Ando, Koji

    2015-11-07

    Nuclear quantum effects play a dominant role in determining the phase diagram of H{sub 2}. With a recently developed quantum molecular dynamics simulation method, we examine dynamical and structural characters of solid H{sub 2} under vapor pressure, demonstrating the difference from liquid and high-pressure solid H{sub 2}. While stable hexagonal close-packed lattice structures are reproduced with reasonable lattice phonon frequencies, the most stable adjacent configuration exhibits a zigzag structure, in contrast with the T-shape liquid configuration. The periodic angular distributions of H{sub 2} molecules indicate that molecules are not a completely free rotor in the vapor-pressure solid reflecting asymmetric potentials from surrounding molecules on adjacent lattice sites. Discrete jumps of librational and H–H vibrational frequencies as well as H–H bond length caused by structural rearrangements under vapor pressure effectively discriminate the liquid and solid phases. The obtained dynamical and structural information of the vapor-pressure H{sub 2} solid will be useful in monitoring thermodynamic states of condensed hydrogens.

  17. Communication: Dynamical and structural analyses of solid hydrogen under vapor pressure

    NASA Astrophysics Data System (ADS)

    Hyeon-Deuk, Kim; Ando, Koji

    2015-11-01

    Nuclear quantum effects play a dominant role in determining the phase diagram of H2. With a recently developed quantum molecular dynamics simulation method, we examine dynamical and structural characters of solid H2 under vapor pressure, demonstrating the difference from liquid and high-pressure solid H2. While stable hexagonal close-packed lattice structures are reproduced with reasonable lattice phonon frequencies, the most stable adjacent configuration exhibits a zigzag structure, in contrast with the T-shape liquid configuration. The periodic angular distributions of H2 molecules indicate that molecules are not a completely free rotor in the vapor-pressure solid reflecting asymmetric potentials from surrounding molecules on adjacent lattice sites. Discrete jumps of librational and H-H vibrational frequencies as well as H-H bond length caused by structural rearrangements under vapor pressure effectively discriminate the liquid and solid phases. The obtained dynamical and structural information of the vapor-pressure H2 solid will be useful in monitoring thermodynamic states of condensed hydrogens.

  18. Communication: Dynamical and structural analyses of solid hydrogen under vapor pressure.

    PubMed

    Hyeon-Deuk, Kim; Ando, Koji

    2015-11-01

    Nuclear quantum effects play a dominant role in determining the phase diagram of H2. With a recently developed quantum molecular dynamics simulation method, we examine dynamical and structural characters of solid H2 under vapor pressure, demonstrating the difference from liquid and high-pressure solid H2. While stable hexagonal close-packed lattice structures are reproduced with reasonable lattice phonon frequencies, the most stable adjacent configuration exhibits a zigzag structure, in contrast with the T-shape liquid configuration. The periodic angular distributions of H2 molecules indicate that molecules are not a completely free rotor in the vapor-pressure solid reflecting asymmetric potentials from surrounding molecules on adjacent lattice sites. Discrete jumps of librational and H-H vibrational frequencies as well as H-H bond length caused by structural rearrangements under vapor pressure effectively discriminate the liquid and solid phases. The obtained dynamical and structural information of the vapor-pressure H2 solid will be useful in monitoring thermodynamic states of condensed hydrogens. PMID:26547150

  19. Vapor pressure predictions of multi-functional oxygen-containing organic compounds with COSMO-RS

    NASA Astrophysics Data System (ADS)

    Schröder, Bernd; Fulem, Michal; Martins, Mónia A. R.

    2016-05-01

    Given the recent interest in multi-functional oxygen-containing organic compounds and the need of accurate and consistent data, a complete review and systematic analysis of available experimental vapor pressure data, as published in the original work of (Asher et al., 2002), was performed with the ThermoData Engine (TDE). A revised set of critical evaluated vapor pressure data, including their uncertainties based on the principles of dynamic data evaluation, is here recommended for a total of 58 compounds. COSMO-RS was further used for vapor pressure estimations for these compounds. The quality of the results is discussed in terms of the chemical functionalities of the molecules. To illustrate the partition behaviour of the title compounds under ambient conditions, a simple comparison of volatility binning between estimates and measurements was performed. Since the encountered vapor pressures are rather high, with respect to pressure range of semi-volatile organic compounds (SVOC), a large fraction is expected to stay in the atmosphere rather than to form secondary organic aerosol.

  20. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND...

  1. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 9 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 61.242-4 Section 61.242-4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Equipment Leaks...

  2. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND...

  3. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 10 2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service standards. 63.1030 Section 63.1030 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Air...

  5. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 10 2014-07-01 2014-07-01 false Standards: Pressure relief devices in gas/vapor service. 63.165 Section 63.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES National Emission Standards...

  6. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems...

  7. 40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4 Section 60.482-4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Equipment Leaks of VOC in...

  8. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Standards: Pressure relief devices in gas/vapor service. 63.165 Section 63.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES National Emission Standards...

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

    NASA Technical Reports Server (NTRS)

    Fischer, A. K.

    1968-01-01

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

  10. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 10 2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service standards. 63.1011 Section 63.1011 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National...

  11. 40 CFR 60.482-4a - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 60.482-4a Section 60.482-4a Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Equipment Leaks of VOC...

  12. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Air...

  13. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems...

  14. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 9 2013-07-01 2013-07-01 false Standards: Pressure relief devices in gas/vapor service. 61.242-4 Section 61.242-4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Equipment Leaks...

  15. Soybean leaf expansion subjected to high and low atmospheric vapor pressure deficits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vapor pressure deficit (VPD) is considered an important environmental factor that might affect leaf expansion and TR in plants. Two slow-wilting soybean genotypes PI 416937 and PI 471938 along with commercial cultivar Hutcheson were subjected to low (1.2 – 1.6 kPa) and high VPD (2.8 – 3 kPa) enviro...

  16. VAPOR PRESSURE AND MELTING BEHAVIOR OF SULFURIC ACID-WATER SYSTEMS

    EPA Science Inventory

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

  17. Molar Mass and Second Virial Coefficient of Polyethylene Glycol by Vapor Pressure Osmometry

    ERIC Educational Resources Information Center

    Schwinefus, Jeffrey J.; Checkal, Caleb; Saksa, Brian; Baka, Nadia; Modi, Kalpit; Rivera, Carlos

    2015-01-01

    In this laboratory experiment, students determine the number-average molar masses and second virial coefficients of polyethylene glycol (PEG) polymers ranging in molar mass from 200 to 1500 g mol[superscript -1] using vapor pressure osmometry (VPO). Students assess VPO in relation to accurate molar mass calculations of PEG polymers. Additionally,…

  18. 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...

  19. SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    NASA Astrophysics Data System (ADS)

    Pankow, J. F.; Asher, W. E.

    2007-08-01

    The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm) and enthalpy of vaporization ΔHvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10pL,io(T)=Σkνk,ibk(T) where νk,i is the number of groups of type k, and bk(T) is the contribution to log10 pL,io(T) by each group of type k. A zeroeth group is included that uses b0(T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C-C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T) is assumed to follow b(T)=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test set of 161 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10pL,io(T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, pL,io(T) values are predicted to within a factor of 2. Because d(log10pL,io(T))/d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of

  20. 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.

  1. Liquid-Liquid Phase Transitions of Phosphorus via Constant-Pressure First-Principles Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Morishita, Tetsuya

    2001-09-01

    Pressure-induced phase transitions in liquid phosphorus have been studied by constant-pressure first-principles molecular dynamics simulations. By compressing a low-pressure liquid which consists of the tetrahedral P4 molecules, a structural phase transition from the molecular to polymeric liquid (a high-pressure phase) observed in the recent experiment by Katayama et al. [Nature (London) 403, 170 (2000)] was successfully realized. It is found that this transition is caused by a breakup of the tetrahedral molecules with large volume contraction. The same transition is also realized by heating. This indicates that only the polymeric liquid can stably exist at high temperature.

  2. The vapor pressure of 1, 1, 1, 2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)

    SciTech Connect

    Goodwin, A.R.H.; Defibaugh, D.R.; Weber, L.A. )

    1992-09-01

    The authors measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7 kPa (corresponding to temperatures in the range 265.6 to 313.2 K), additional measurements were made with a Burnett apparatus. The results have been combined for 1, 1, 1, 2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane the results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature. 58 refs., 6 figs., 2 tabs.

  3. Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

    SciTech Connect

    Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

    1995-09-01

    In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that there exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.

  4. 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.

  5. 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.

  6. Effect of superficial velocity on vaporization pressure drop with propane in horizontal circular tube

    NASA Astrophysics Data System (ADS)

    Novianto, S.; Pamitran, A. S.; Nasruddin, Alhamid, M. I.

    2016-06-01

    Due to its friendly effect on the environment, natural refrigerants could be the best alternative refrigerant to replace conventional refrigerants. The present study was devoted to the effect of superficial velocity on vaporization pressure drop with propane in a horizontal circular tube with an inner diameter of 7.6 mm. The experiments were conditioned with 4 to 10 °C for saturation temperature, 9 to 20 kW/m2 for heat flux, and 250 to 380 kg/m2s for mass flux. It is shown here that increased heat flux may result in increasing vapor superficial velocity, and then increasing pressure drop. The present experimental results were evaluated with some existing correlations of pressure drop. The best prediction was evaluated by Lockhart-Martinelli (1949) with MARD 25.7%. In order to observe the experimental flow pattern, the present results were also mapped on the Wang flow pattern map.

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

    NASA Technical Reports Server (NTRS)

    Hanson, David R.

    1990-01-01

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

  8. Sublimation characterization and vapor pressure estimation of an HIV nonnucleoside reverse transcriptase inhibitor using thermogravimetric analysis.

    PubMed

    Xie, Minli; Ziemba, Theresa M; Maurin, Michael B

    2003-01-01

    The purpose of this research is to investigate the sublimation process of DPC 963, a second-generation nonnucleoside reverse transcriptase inhibitor for HIV-1 retrovirus, and to better understand the effect of sublimation during active pharmaceutical ingredient (API) manufacture and formulation development, especially the drying processes. Sublimation of DPC 963 at 150 degrees C and above was determined by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR). The rates of sublimation at different temperatures were measured using isothermal TGA. Condensed material was collected and analyzed by differential scanning calorimetry (DSC), x-ray powder diffraction (XRPD), and infrared (IR) spectrometry. Benzoic acid was used as a reference standard to derive a linear logarithmic relationship between sublimation/evaporation rate and vapor pressure specific to the TGA system used in this study. Sublimation and evaporation of DPC 963 were found to follow apparent zero-order kinetics. Using the Eyring equation, the enthalpy and entropy of the sublimation and evaporation processes were obtained. The enthalpies of sublimation and evaporation were found to be 29 and 22 kcal/mol, respectively. The condensed material from the vapor phase was found to exist in 2 physical forms, amorphous and crystalline. Using benzoic acid as a reference standard, vapor pressure of DPC 963 at different temperatures was calculated using the linear logarithmic relationship obtained. DPC 963 undergoes sublimation at appreciable rates at 150 degrees C and above but this is not likely to pose a serious issue during the manufacturing process. Vapor pressure estimation using thermogravimetric analysis provided sufficient accuracy to be used as a fast, simple, and safe alternative to the traditional methods of vapor pressure determination. PMID:12916905

  9. Measurements of blast waves from bursting frangible spheres pressurized with flash-evaporation vapor or liquid

    NASA Technical Reports Server (NTRS)

    Esparaza, E. D.; Baker, W. E.

    1977-01-01

    Incident overpressure data from frangible spheres pressurized with a flash-evaporating fluid in liquid and vapor form were obtained in laboratory experiments. Glass spheres under higher than ambient internal pressure of Freon-12 were purposely burst to obtain time histories of overpressure. Nondimensional peak pressures, arrival and duration times, and impulses are presented, and whenever possible plotted and compared with compiled data for Pentolite high-explosive. The data are generally quite repeatable and show differences from blast data produced by condensed high-explosives.

  10. Phosphorus contents in garnet from an ultrahigh pressure, high-temperature eclogite of the Saxonian Erzgebirge

    NASA Astrophysics Data System (ADS)

    Žigovečki Gobac, Željka; Massonne, Hans-Joachim; Theye, Thomas

    2015-04-01

    In the central Saxonian Erzgebirge, ultrahigh pressure rocks occur close to the Saidenbach reservoir. Among these rocks there are eclogites which have experienced metamorphic temperatures in excess of 1000°C (e.g., Massonne, 2013, Elements 9, 267-272). As a result of these high temperatures, the garnet was chemically homogenized with respect to a former growth zonation. Such kind of zonation can be deduced from inclusion minerals such as kyanite, phengite, and (clino)zoisite in garnet cores which point to metamorphic temperatures somewhat below 700°C. In order to test this view of a former prograde zonation in garnet, the content of phosphorus, a presumably much less mobile element at high temperatures compared to the common divalent cations, was determined in this mineral. Concentrations of P in mm-sized garnet in thin sections of eclogite were analyzed by a CAMECA SX100 electron microprobe (EMP). Different instrumental conditions, ranging from beam currents of 50 to 100 nA and counting times of 100 to 600 s on both peak and background at an acceleration voltage of 15 kV, were used in order to find the optimal way to determine this concentration in addition to the concentrations of the common elements at significantly shorter counting times. The interference of the CaKβ 2nd order and PKα 1st order peaks was considered by test measurements on standard material. The calculated detection limit for our P measurements was found to be around 13 ppm at the highest beam current and counting time. Several chemical profiles through a more or less concentrically zoned garnet grain were determined by spot analyses. These measurements on a high temperature eclogite from the Saidenbach reservoir yielded relatively low P contents in the core region of garnet of approximately 150 ppm and a significant increase towards the garnet rim. Maximum P contents were found to be around 350 ppm. In the core of garnet small apatite crystals were included whereas in the matrix no

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

    SciTech Connect

    Munson, Darrell Eugene

    2010-05-01

    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.

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

    USGS Publications Warehouse

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

    1990-01-01

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

  13. Initial Measurement of the Vapor Pressures of Simple Refractory Materials: Cu and Fe

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A., III; Ferguson, Frank T.; Johnson, Natasha; Martinez, Daniel

    2003-01-01

    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 iron or SiO have not been measured over the appropriate temperature range (near T approximately equal to 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 and can depend on other factors such as the oxygen fugacity or the presence of hydrogen gas. Moreover, modern technology has made possible more accurate measurements of such quantities over a wider temperature range. We recently acquired a commercial Thermo-Cahn Thermogravimetric system capable of vacuum operation to 1700 C and measurement of mass change with microgram accuracy in a 100g sample or smaller. In this paper, we will report our progress in learning to make vapor pressure measurements using this system.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1999-09-01

    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 of CO{_2}; however, they are all based on data taken sixty-five years ago (Meyers and Van Dusen 1933) or calculations and extrapolations based on that data (e.g., Brown and Ziegler 1980). Using our apparatus specifically designed for low-temperature measurements of thermodynamic properties, we have experimentally determined the vapor pressure of CO{_2} from 167 to 87 K, corresponding to a pressure range of 100 to 1.8x10{(-6}) Torr and set by our lowest measurable pressure. Our preliminary data have been fitted with a simple Clausius-Clapeyron representation and compared with an extrapolation of the form recommended by Brown and Ziegler (1980). For comparison the extrapolation predicts a pressure of 1.1x10{(-6}) Torr at 87 K, whereas our measured value is 1.8x10{(-6}) Torr at this temperature. Further refinement of the data to account for thermal transpiration and fitting with a more comprehensive three-parameter model are in progress. References: Brown, G. N., Jr. and Ziegler, W. T. 1980. In Advances in Cryogenic Engineering, vol. 25 (K. Timmerhaus and H. A. Snyder, Eds.), pp. 662-670. (New York: Plenum Press). Meyers, C. H. and Van Dusen, M. S. 1933, J. Res. Natl. Bur. Stndrds. 84, 2843. Support from NASA's Planetary Atmospheres Program is gratefully acknowledged.

  16. Vapor Pressure and Evaporation Coefficient of Silicon Monoxide over a Mixture of Silicon and Silica

    NASA Technical Reports Server (NTRS)

    Ferguson, Frank T.; Nuth, Joseph A., III

    2012-01-01

    The evaporation coefficient and equilibrium vapor pressure of silicon monoxide over a mixture of silicon and vitreous silica have been studied over the temperature range (1433 to 1608) K. The evaporation coefficient for this temperature range was (0.007 plus or minus 0.002) and is approximately an order of magnitude lower than the evaporation coefficient over amorphous silicon monoxide powder and in general agreement with previous measurements of this quantity. The enthalpy of reaction at 298.15 K for this reaction was calculated via second and third law analyses as (355 plus or minus 25) kJ per mol and (363.6 plus or minus 4.1) kJ per mol respectively. In comparison with previous work with the evaporation of amorphous silicon monoxide powder as well as other experimental measurements of the vapor pressure of silicon monoxide gas over mixtures of silicon and silica, these systems all tend to give similar equilibrium vapor pressures when the evaporation coefficient is correctly taken into account. This provides further evidence that amorphous silicon monoxide is an intimate mixture of small domains of silicon and silica and not strictly a true compound.

  17. 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.

  18. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure drop is unaffected by large changes in the volume fraction of benzoate drops and their size distribution. Measured power spectra of the static wall pressure fluctuations induced by the turbulent water-benzoate flow also revealed that their dynamics is essentially unaltered by the presence of the droplets. These experimental findings, together with the theoretical analysis, led to the conclusion that the pressure drop in fully developed, dispersed liquid-vapor flow in straight ducts of constant cross section at 0-g is identical to that due to liquid flowing alone at the same total volumetric flow rate of the liquid-vapor mixture and, therefore, can be readily determined.

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

    SciTech Connect

    Oja, V.; Suuberg, E.M.

    1999-01-01

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

  20. 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 370°C). 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.

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

    SciTech Connect

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

    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 ºC). 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.

  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

  3. Static Pressure Above 300 GPa Using Chemical Vapor Deposited Two-stage Diamond Micro-anvils

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey; Samudrala, Gopi; Tsoi, Georgiy; Smith, Spencer; Vohra, Yogesh

    Two-stage diamond micro-anvils were grown via chemical vapor deposition (CVD) on beveled diamond anvils with 30 micron central flats. These anvils were used to compress a pre-indented rhenium foil to pressures in excess of 300 Gigapascals (GPa) at relatively small applied loads. Powder diffraction patterns were collected across the high-pressure region using an x-ray beam collimated to 1x2 microns in a grid with a spacing of 1 micron. While multi-megabar pressures were seen across the entire second stage, the highest pressure regions were confined to areas of a few microns in diameter. These were observed at points near the edge of the second stage with nearby pressure gradients as high as 100 GPa/micron. The transmitted x-rays show that the second stage plastically deformed while maintaining multi-megabar pressures. This may have created a second-stage gasket consisting of CVD diamond and rhenium that supported the pressure gradient without substantial external confining pressure. Further improvements in two-stage diamond micro-anvils would require controlling the geometry and microcrystalline/nanocrystalline diamond content during CVD growth process. This work was supported by the Department of Energy (DOE), National Nuclear Security Administration under Grant Number DE-NA0002014.

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

    NASA Astrophysics Data System (ADS)

    Weschler, Charles J.

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

  6. Simple fabrication of air-stable black phosphorus heterostructures with large-area hBN sheets grown by chemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Sinha, Sapna; Takabayashi, Yuya; Shinohara, Hisanori; Kitaura, Ryo

    2016-09-01

    We have developed a facile and general method to passivate thin black phosphorus (BP) flakes with large-area high-quality monolayer hexagonal boron nitride (hBN) sheets grown by the chemical vapor deposition (CVD) method. In spite of the one-atom-thick structure, the high-quality CVD-grown monolayer hBN has proven to be useful to prevent the degradation of thin BP flakes exfoliated on substrates. Mechanically exfoliated BP flakes prepared on a Si substrate are covered by the monolayer hBN sheet to preserve (otherwise unstable) atomic layered BP flakes from degradation. The present technique can generally be applied to fabricating BP-based electronic devices with much easiness.

  7. Comparative study of the effects of phosphorus and boron doping in vapor-liquid-solid growth with fixed flow of silicon gas

    NASA Astrophysics Data System (ADS)

    Islam, Md. Shofiqul; Mehedi, Ibrahim Mustafa

    2016-04-01

    This work was carried out to investigate the comparative effects of phosphorus and boron doing in vapor-liquid-solid (VLS) growth. Doped Si microneedles were grown by VLS mechanism at the temperature of 700 °C or less using Au as the catalyst. VLS growth using in-situ doping with the mixed gas of Si2H6 and PH3 produced phosphorus doped n-Si microneedles at Au dot sites, whereas, the mixed gas of Si2H6 and B2H6 produced boron doped p-Si microneedles. The variation of growth rate, diameter, resistivity, impurity concentration and carrier (electron, hole) mobility of these n-Si and p-Si microneeedles were investigated and compared with the variation of dopant gas (PH3 or B2H6) flow, with a fixed flow of Si gas (Si2H6). This comparative study shall be helpful while fabricating devices by growing n-Si and p-Si microneedles one above another by multistep (2-step or 3-step) VLS growth.

  8. Remote catalyzation for growth of boron nitride nanotubes by low pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wang, Liangjie; Li, Taotao; Ling, Lin; Luo, Jie; Zhang, Kai; Xu, Yancui; Lu, Huifen; Yao, Yagang

    2016-05-01

    Direct deposition of high purity and quality boron nitride nanotubes (BNNTs) on Si substrate were obtained using low pressure chemical vapor deposition (LPCVD). We find Fe-Mg-O species may act as catalysts for growing BNNTs. This synthesis process conforms to vapor-liquid-solid (VLS) growth mechanism. As-grown BNNTs also show a large optical energy band gap of 6.12 eV, approaching to hexagonal phase BN single crystals. Meanwhile, as-grown BNNTs exhibit an intense UV-emission band located at 345 nm and a weak deep band at 237 nm. Their optoelectronic properties make them have promising for future nanoscale deep-UV light emitting devices.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  10. Ultrasonic speeds in compressed liquid and vapor pressures for 1,1,1,2-tetrafluoroethane

    SciTech Connect

    Takagi, T.

    1996-09-01

    Ultrasonic speeds in the liquid phase of 1,1,1,2-tetrafluoroethane (CF{sub 3}CH{sub 2}F) have been measured from 243.11 K to 333.15 K and from near the saturation line to about 30 MPa. The measurements were made using a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz. The probable uncertainty in the results was no greater than {+-}0.2% except in the low-density region at near the saturation line at higher temperatures. The vapor pressures have also been observed to within {+-}10 kPa by monitoring the acoustic signal at vapor-liquid equilibrium. When these results were combined, the ultrasonic speeds for the saturated liquid were estimated to within {+-}1 m/s.

  11. Vapor Pressure Isotope Fractionation Effects in Planetary Atmospheres: Application to Deuterium

    NASA Astrophysics Data System (ADS)

    Fouchet, Thierry; Lellouch, Emmanuel

    2000-03-01

    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 CH 3D 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.

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

    SciTech Connect

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

    2012-04-02

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  14. 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.

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

    PubMed Central

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

    2012-01-01

    Graphene has attracted considerable interest as a potential material for future electronics. Although mechanical peel is known to produce high quality graphene flakes, practical applications require continuous graphene layers over a large area. The catalyst-assisted chemical vapor deposition (CVD) is a promising synthetic method to deliver wafer-sized graphene. Here we present a systematic study on the nucleation and growth of crystallized graphene domains in an atmospheric pressure chemical vapor deposition (APCVD) process. Parametric studies show that the mean size of the graphene domains increases with increasing growth temperature and CH4 partial pressure, while the density of domains decreases with increasing growth temperature and is independent of the CH4 partial pressure. Our studies show that nucleation of graphene domains on copper substrate is highly dependent on the initial annealing temperature. A two-step synthetic process with higher initial annealing temperature but lower growth temperature is developed to reduce domain density and achieve high quality full-surface coverage of monolayer graphene films. Electrical transport measurements demonstrate that the resulting graphene exhibits a high carrier mobility of up to 3000 cm2 V−1 s−1 at room temperature. PMID:25414547

  16. A differential vapor-pressure equipment for investigations of biopolymer interactions.

    PubMed

    Andersen, Kim B; Koga, Yoshikata; Westh, Peter

    2002-01-01

    The design and performance of an equipment for the measurement of vapor pressures over liquid or solid samples is presented. The equilibrium pressure difference, DeltaP, between a sample and a reference of known vapor pressure is recorded as a function of composition and/or temperature. Through the use of high-accuracy capacitance manometers and a leak-tight system of stainless steel pipes, below-sealed valves and metal-gasket fittings, DeltaP can be measured with a resolution of about 0.5 micro bar (0.05 Pa) in some applications. This sensitivity level, along with other features of the equipment, particularly a "gas-phase titration" routine for changing the cell composition, makes it effective for the investigations of several types of biopolymer interactions. These include isothermal studies of net affinities such as the adsorption of water to proteins or membranes, the preferential interaction of biopolymers with the components of a mixed solvent, the partitioning of solutes between a membrane and the aqueous bulk and the weak, specific binding of ligands to macromolecules. Furthermore, a temperature-scanning mode allows real-time elucidation of such interactions at thermally induced conformational changes in biopolymers. Selected examples of these applications are presented and discussed. PMID:11741714

  17. Measurement of vapor pressures and heats of sublimation of dicarboxylic acids using atmospheric solids analysis probe mass spectrometry.

    PubMed

    Bruns, Emily A; Greaves, John; Finlayson-Pitts, Barbara J

    2012-06-21

    Vapor pressures of low volatility compounds are important parameters in several atmospheric processes, including the formation of new particles and the partitioning of compounds between the gas phase and particles. Understanding these processes is critical for elucidating the impacts of aerosols on climate, visibility, and human health. Dicarboxylic acids are an important class of compounds in the atmosphere for which reported vapor pressures often vary by more than an order of magnitude. In this study, atmospheric solids analysis probe mass spectrometry (ASAP-MS), a relatively new atmospheric pressure ionization technique, is applied for the first time to the measurement of vapor pressures and heats of sublimation of a series of dicarboxylic acids. Pyrene was also studied because its vapor pressures and heat of sublimation are relatively well-known. The heats of sublimation measured using ASAP-MS were in good agreement with published values. The vapor pressures, assuming an evaporation coefficient of unity, were typically within a factor of ∼3 lower than published values made at similar temperatures for most of the acids. The underestimation may be due to diffusional constraints resulting from evaporation at atmospheric pressure. However, this study establishes that ASAP-MS is a promising new technique for such measurements. PMID:22432524

  18. Estimation of Fracture Toughness of Anisotropic Rocks by Semi-Circular Bend (SCB) Tests Under Water Vapor Pressure

    NASA Astrophysics Data System (ADS)

    Kataoka, M.; Obara, Y.; Kuruppu, M.

    2015-07-01

    In order to investigate the influence of water vapor pressure in the surrounding environment on mode I fracture toughness ( K Ic) of rocks, semi-circular bend (SCB) tests under various water vapor pressures were conducted. Water vapor is one of the most effective agents which promote stress corrosion of rocks. The range of water vapor pressure used was 10-2 to 103 Pa, and two anisotropic rock types, African granodiorite and Korean granite, were used in this work. The measurement of elastic wave velocity and observation of thin sections of these rocks were performed to investigate the microstructures of the rocks. It was found that the distribution of inherent microcracks and grains have a preferred orientation. Two types of specimens in different orientations, namely Type-1 and Type-3, were prepared based on the anisotropy identified by the differences in the elastic wave velocity. K Ic of both rock types was dependent on the water vapor pressure in the surrounding environment and decreased with increasing water vapor pressure. It was found that the degree of the dependence is influenced by the orientation and density of inherent microcracks. The experimental results also showed that K Ic depended on the material anisotropy. A fracture process was discussed on the basis of the geometry of fractures within fractured specimens visualized by the X-ray computed tomography (CT) method. It was concluded that the dominant factor causing the anisotropy of K Ic is the distribution of grains rather than inherent microcracks in these rocks.

  19. The control of purity and stoichiometry of compound semiconductors by high vapor pressure transport

    NASA Technical Reports Server (NTRS)

    Bachmann, Klaus J.; Ito, Kazufumi; Scroggs, Jeffery S.; Tran, Hien T.

    1995-01-01

    In this report we summarize the results of a three year research program on high pressure vapor transport (HPVT) of compound semiconductors. Most of our work focused onto pnictides, in particular ZnGeP2, as a model system. Access to single crystals of well controlled composition of this material is desired for advancing the understanding and control of its point defect chemistry in the contest of remote, real-time sensing of trace impurities, e.g., greenhouse gases, in the atmosphere by ZnGeP2 optical parametric oscillators (OPO's).

  20. Atmospheric pressure chemical vapor deposition of CdTe—reactor design considerations

    NASA Astrophysics Data System (ADS)

    Meyers, Peter V.; Kee, Robert J.; Raja, Laxminarayan; Wolden, Colin A.; Aire, Michael

    1999-03-01

    Atmospheric Pressure Chemical Vapor Deposition (APCVD) of polycrystalline thin-film CdTe appears to offer several practical advantages over state-of-the-art manufacturing techniques. APCVD employs the same reaction chemistry utilized to produce 16% efficient CdTe cells (i.e., same reaction chemistry as Close Spaced Sublimation), avoids use of vacuum equipment, allows for physical separation of the source and substrate, and employs forced convection to ensure uniform delivery of source material over large-area substrates. Reactor design considerations and preliminary numerical simulations of mass transport are presented.

  1. Track studies in water vapor using a low-pressure cloud chamber. II. Microdosimetric measurements.

    PubMed

    Stonell, G P; Marshall, M; Simmons, J A

    1993-12-01

    A low-pressure cloud chamber has been adapted to operate with pure water vapor. Photographs were obtained of tracks arising from the passage of ionizing radiation. The sources used were low-energy X rays, 242Cm alpha particles, and low-energy protons. Distributions of lineal energy, radial distances around an ion track, and interdroplet distances were measured and compared with the predictions of Monte Carlo calculations. After allowing for diffusion and the limitations of the geometry of the system, the measured and calculated distributions were found to be in good agreement. PMID:8278576

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

    SciTech Connect

    Gray, M.; Nilsson, M.; Zalupski, P.

    2013-07-01

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

  3. Laser scattering diagnostics of an argon atmospheric-pressure plasma jet in contact with vaporized water

    NASA Astrophysics Data System (ADS)

    Seo, B. H.; Kim, J. H.; You, S. J.; Seong, D. J.

    2015-12-01

    The radial profiles of the electron density, electron temperature, and molecular rotational temperature are investigated in an argon atmospheric-pressure plasma jet in contact with vaporized water, which is driven by a 13.56 MHz radio frequency by means of the Thomson and Raman laser scattering methods. There is a distinct difference in the radial profiles of the plasma parameters between plasmas in contact with water and those without water contact. In the case of plasmas without vaporized water contact, all the parameters have a single-peak distribution with maximum values at the center of the discharge. In the case of plasmas in contact with vaporized water, all parameters have double-peak distributions; a neighboring peak appears beside the main peak. The new peak may have originated from the ripple of the water surface, which works as a cathode, and the peak of the ripple offers a sharp curvature point, playing the role of a pin. Our experimental results and the underlying physics are described in detail.

  4. 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.

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

    SciTech Connect

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

    1985-11-01

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

  6. LETTER TO THE EDITOR: High pressure behaviour of the ?-cristobalite-type phase of phosphorus oxynitride, PON

    NASA Astrophysics Data System (ADS)

    Léger, J. M.; Haines, J.; de Oliveira, L. S.; Chateau, C.; LeSauze, A.; Marchand, R.

    1996-12-01

    Phosphorus oxynitride, PON, is isoelectronic with 0953-8984/8/50/001/img10 and can be used as a model for silica. The crystalline behaviour of the 0953-8984/8/50/001/img11-cristobalite-type phase was determined as a function of pressure by angular dispersive x-ray diffraction in a diamond anvil cell to 48 GPa. No evidence for a phase transition or amorphization was observed. The cell parameters were measured as a function of pressure. The macroscopic bulk modulus is 71(3) GPa with a first pressure derivative of 3.2(5). The polyhedral bulk modulus was inferred to be about 800 GPa, assuming that the tetrahedra remain regular.

  7. 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.

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

    SciTech Connect

    Suuberg, E.M.

    1993-12-31

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  10. Dependence of the isobaric specific heat capacity of water vapor on the pressure and temperature

    NASA Astrophysics Data System (ADS)

    Vestfálová, Magda; Šafařík, Pavel

    2016-03-01

    The fundamental base for the calculation of the thermodynamic properties of substances is the thermal equation of state and the dependence of some of the basic specific heat capacities on temperature. Dependence of isobaric specific heat capacity on the pressure can already be deduced from these relations. International standards of the properties of water and steam are based on the new scientific formulation IAPWS-95. The equation is in the form of Helmholtz dimensionless function with very much parameters. The aim of this paper is to design the simple dependence of the isobaric specific heat capacity of water vapor on the pressure and temperature in the range in which the steam occurs in the atmospheric moist air.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  12. Gas-phase reaction study of disilane pyrolysis: Applications to low pressure chemical vapor deposition

    SciTech Connect

    Johannes, J.E.; Ekerdt, J.G. . Dept. of Chemical Engineering)

    1994-08-01

    The gas-phase thermal reactions during disilane decomposition at low pressure chemical vapor deposition conditions were studied from 300 to 1,000 K using resonance enhanced multiphoton ionization (REMPI) and multiphoton ionization (MPI). REMPI of gas-phase Si, mass 28, was detected from 640 to 840 K and 1 to 10 Torr, with a maximum signal intensity between 700 to 720 K. During disilane decomposition, no SiH (427.8 nm), SiH[sub 2] (494-515 nm), or SiH[sub 3] (419.0 nm) was detected. MPI of higher silanes, silenes, and silylenes were detected through mass fragments 2, 32, and 60; these species reached a maximum signal intensity 20 degrees prior to the mass-28 maximum. Modeling studies that included a detailed low pressure gas-phase kinetic scheme predict relative gas-phase partial pressures generated during disilane pyrolysis. The model predicted experimental trends in the Si partial pressure and the higher silane, silene, and silylene partial pressures.

  13. 46 CFR 154.1836 - Vapor venting as a means of cargo tank pressure and temperature control.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... temperature control. 154.1836 Section 154.1836 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... LIQUEFIED GASES Operations § 154.1836 Vapor venting as a means of cargo tank pressure and temperature... cargo pressure and temperature control system under §§ 154.701 through 154.709 is operating and...

  14. 46 CFR 154.1836 - Vapor venting as a means of cargo tank pressure and temperature control.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... temperature control. 154.1836 Section 154.1836 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... LIQUEFIED GASES Operations § 154.1836 Vapor venting as a means of cargo tank pressure and temperature... cargo pressure and temperature control system under §§ 154.701 through 154.709 is operating and...

  15. 46 CFR 154.1836 - Vapor venting as a means of cargo tank pressure and temperature control.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... temperature control. 154.1836 Section 154.1836 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... LIQUEFIED GASES Operations § 154.1836 Vapor venting as a means of cargo tank pressure and temperature... cargo pressure and temperature control system under §§ 154.701 through 154.709 is operating and...

  16. 46 CFR 154.1836 - Vapor venting as a means of cargo tank pressure and temperature control.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... temperature control. 154.1836 Section 154.1836 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... LIQUEFIED GASES Operations § 154.1836 Vapor venting as a means of cargo tank pressure and temperature... cargo pressure and temperature control system under §§ 154.701 through 154.709 is operating and...

  17. 46 CFR 154.1836 - Vapor venting as a means of cargo tank pressure and temperature control.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... temperature control. 154.1836 Section 154.1836 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... LIQUEFIED GASES Operations § 154.1836 Vapor venting as a means of cargo tank pressure and temperature... cargo pressure and temperature control system under §§ 154.701 through 154.709 is operating and...

  18. Vapor pressures, thermodynamic stability, and fluorescence properties of three 2,6-alkyl naphthalenes.

    PubMed

    Santos, Ana Filipa L O M; Oliveira, Juliana A S A; Ribeiro da Silva, Maria D M C; Monte, Manuel J S

    2016-03-01

    This work reports the experimental determination of relevant thermodynamic properties and the characterization of luminescence properties of the following polycyclic aromatic hydrocarbons (PAHs): 2,6-diethylnaphthalene, 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene. The standard (p(o) = 0.1 MPa) molar enthalpies of combustion, ΔcHm(o), of the three compounds were determined using static bomb combustion calorimetry. The vapor pressures of the crystalline phase of 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene were measured at different temperatures using the Knudsen effusion method and the vapor pressures of both liquid and crystalline phases of 2,6-diethylnaphthalene were measured by means of a static method. The temperatures and the molar enthalpies of fusion of the three compounds were determined using differential scanning calorimetry. The gas-phase molar heat capacities and absolute entropies of the three 2,6-dialkylnaphthalenes studied were determined computationally. The thermodynamic stability of the compounds in both the crystalline and gaseous phases was evaluated by the determination of the Gibbs energies of formation and compared with the ones reported in the literature for 2,6-dimethylnaphthalene. From fluorescence spectroscopy measurements, the optical properties of the compounds studied and of naphthalene were evaluated in solution and in the solid state. PMID:26716880

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

    PubMed

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

    2010-04-01

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

  20. Measurements of the vapor pressures of difluoromethane, 1-chloro-1,2,2,2-tetrafluoroethane, and pentafluoroethane

    SciTech Connect

    Weber, L.A.; Silva, A.M. . Chemical Science and Technology Lab.)

    1994-10-01

    Information about vapor pressures is important initially to qualify potential candidates as working fluids in refrigeration machinery. Later, it is also very useful in calculating the thermodynamic properties necessary for the design of that machinery. The authors present new measurements of the vapor pressures of difluoromethane (R32) from 235 to 265 K, of 1-chloro-1, 2, 2, 2-tetrafluoroethane (R124) from 220 to 286 K, and of pentafluoroethane (R125) from 218 to 286 K. Measurements were made in two ebulliometers, one of glass and one of metal. Overall, pressures ranged from 13 to about 950 kPa. The authors also present vapor pressures of R125, calculated via thermodynamic relationships, for temperature down to 170 K (2.3 kPa). They study the azeotropic mixture of R125 with chloropentafluoroethane (R115), and they correct the data for a small R115 impurity.

  1. 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.

  2. Predicting temperature-dependent solid vapor pressures of explosives and related compounds using a quantum mechanical continuum solvation model.

    PubMed

    Alnemrat, Sufian; Hooper, Joseph P

    2013-03-01

    Temperature-dependent vapor pressures of solid explosives and their byproducts are calculated to an accuracy of 0.32 log units using a modified form of the conductor-like screening model for real solvents (COSMO-RS). Accurate predictions for solids within COSMO-RS require correction for the free energy of fusion as well as other effects such as van der Waals interactions. Limited experimental data on explosives is available to determine these corrections, and thus we have extended the COSMO-RS model by introducing a quantitative structure-property relationship to estimate a lumped correction factor using only information from standard quantum chemistry calculations. This modification improves the COSMO-RS estimate of ambient vapor pressure by more than 1 order of magnitude for a range of nitrogen-rich explosives and their derivatives, bringing the theoretical predictions to within typical experimental error bars for vapor pressure measurements. The estimated temperature dependence of these vapor pressures also agrees well with available experimental data, which is particularly important for estimating environmental transport and gas evolution for buried explosives or environmentally contaminated locations. This technique is then used to predict vapor pressures for a number of explosives and degradation products for which experimental data is not readily available. PMID:23398143

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

    SciTech Connect

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

    2015-01-28

    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-O{sub x} 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.

  4. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    DOE PAGESBeta

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage ofmore » 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.« less

  5. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    SciTech Connect

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage of 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.

  6. D0 Silicon Upgrade: Vapor Pressure Thermometry System Near LN2 Subcooler

    SciTech Connect

    Kuwazaki, Andrew; /Fermilab

    1996-07-01

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

  7. Flexible Electronics: High Pressure Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Films and Solar Cells (Adv. Mater. 28/2016).

    PubMed

    He, Rongrui; Day, Todd D; Sparks, Justin R; Sullivan, Nichole F; Badding, John V

    2016-07-01

    On page 5939, J. V. Badding and co-workers describe the unrolling of a flexible hydrogenated amorphous silicon solar cell, deposited by high-pressure chemical vapor deposition. The high-pressure deposition process is represented by the molecules of silane infiltrating the small voids between the rolled up substrate, facilitating plasma-free deposition over a very large area. The high-pressure approach is expected to also find application for 3D nanoarchitectures. PMID:27442970

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

    SciTech Connect

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

    1987-01-01

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

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

    PubMed

    Kaya, Murat; Volkan, Mürvet

    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

  10. Track studies in water vapor using a low-pressure cloud chamber. I. Macroscopic measurements.

    PubMed

    Stonell, G P; Marshall, M; Simmons, J A

    1993-12-01

    Techniques have been developed to operate a low-pressure cloud chamber with pure water vapor. Photographs have been obtained of the tracks arising in this medium from the passage of ionizing radiation. The sources used were low-energy X rays, 242Cm alpha particles, and low-energy protons. Track lengths of the electrons were similar to those found previously in tissue-equivalent gas. W values of 35.6 +/- 0.4 and 32.6 +/- 0.6 eV per ion pair for carbon and aluminum X rays also compare closely with those in tissue-equivalent gas, but are somewhat higher than the predictions of Monte Carlo calculations. Differential w values were obtained: for alpha particles of energy 5.3 MeV the value was 33.0 +/- 3.0 eV per ion pair; for protons of energy 390, 230, and 85 keV the values were 30.6 +/- 1.9, 31.9 +/- 2.0, and 33.6 +/- 3.4 eV per ion pair. The energy losses of protons in water vapor were measured in a second (dummy) chamber used for energy calibration. Results support Janni's values of stopping power for protons in the energy range 40-480 keV. PMID:8278575

  11. 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.

    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.

  12. Linking Turgor with ABA Biosynthesis: Implications for Stomatal Responses to Vapor Pressure Deficit across Land Plants.

    PubMed

    McAdam, Scott A M; Brodribb, Timothy J

    2016-07-01

    Stomatal responses to changes in vapor pressure deficit (VPD) constitute the predominant form of daytime gas-exchange regulation in plants. Stomatal closure in response to increased VPD is driven by the rapid up-regulation of foliar abscisic acid (ABA) biosynthesis and ABA levels in angiosperms; however, very little is known about the physiological trigger for this increase in ABA biosynthesis at increased VPD Using a novel method of modifying leaf cell turgor by the application of external pressures, we test whether changes in turgor pressure can trigger increases in foliar ABA levels over 20 min, a period of time most relevant to the stomatal response to VPD We found in angiosperm species that the biosynthesis of ABA was triggered by reductions in leaf turgor, and in two species tested, that a higher sensitivity of ABA synthesis to leaf turgor corresponded with a higher stomatal sensitivity to VPD In contrast, representative species from nonflowering plant lineages did not show a rapid turgor-triggered increase in foliar ABA levels, which is consistent with previous studies demonstrating passive stomatal responses to changes in VPD in these lineages. Our method provides a new tool for characterizing the response of stomata to water availability. PMID:27208264

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

    SciTech Connect

    Butters, R.A.

    1990-09-30

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

  14. 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.

  15. The Vapor Pressure of Palladium at Temperatures up to 1973K

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  16. 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.

  17. The Action of Pressure-Radiation Forces on Pulsating Vapor Bubbles

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  18. Fabrication of Planar Heterojunction Perovskite Solar Cells by Controlled Low-Pressure Vapor Annealing.

    PubMed

    Li, Yanbo; Cooper, Jason K; Buonsanti, Raffaella; Giannini, Cinzia; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2015-02-01

    A new method for achieving high efficiency planar CH3NH3I3-xClx perovskite photovoltaics, based on a low pressure, reduced temperature vapor annealing is demonstrated. Heterojunction devices based on this hybrid halide perovskite exhibit a top PCE of 16.8%, reduced J-V hysteresis, and highly repeatable performance without need for a mesoporous or nanocrystalline metal oxide layer. Our findings demonstrate that large hysteresis is not an inherent feature of planar heterojunctions, and that efficient charge extraction can be achieved with uniform halide perovskite materials with desired composition. X-ray diffraction, valence band spectroscopy, and transient absorption measurements of these thin films reveal that structural modifications induced by chlorine clearly dominate over chemical and electronic doping effects, without affecting the Fermi level or photocarrier lifetime in the material. PMID:26261969

  19. Luminescence of mesoporous silicon powders treated by high-pressure water vapor annealing

    NASA Astrophysics Data System (ADS)

    Gelloz, Bernard; Loni, Armando; Canham, Leigh; Koshida, Nobuyoshi

    2012-07-01

    We have studied the photoluminescence of nanocrystalline silicon microparticle powders fabricated by fragmentation of PSi membranes. Several porosities were studied. Some powders have been subjected to further chemical etching in HF in order to reduce the size of the silicon skeleton and reach quantum sizes. High-pressure water vapor annealing was then used to enhance both the luminescence efficiency and stability. Two visible emission bands were observed. A red band characteristic of the emission of Si nanocrystals and a blue band related to localized centers in oxidized powders. The blue band included a long-lived component, with a lifetime exceeding 1 sec. Both emission bands depended strongly on the PSi initial porosity. The colors of the processed powders were tunable from brown to off-white, depending on the level of oxidation. The surface area and pore volume of some powders were also measured and discussed. The targeted applications are in cosmetics and medicine.

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

    SciTech Connect

    Cardoso, R. P.; Belmonte, T.; Henrion, G.; Gries, T.; Tixhon, E.

    2010-01-15

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

  1. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-01

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ, and Hα were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit "coral" and "cauliflower-like" morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  2. 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 μm 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.

  3. 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.

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

    PubMed

    Manatt, Stanley L; Manatt, Margaret R R

    2004-12-01

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

  6. Fracture toughness of low-pressure chemical-vapor-deposited polycrystalline silicon carbide thin films

    NASA Astrophysics Data System (ADS)

    Hatty, V.; Kahn, H.; Trevino, J.; Zorman, C. A.; Mehregany, M.; Ballarini, R.; Heuer, A. H.

    2006-01-01

    The fracture toughness of thin-film polycrystalline silicon carbide (poly-SiC) deposited on silicon (Si) wafers via low-pressure chemical-vapor deposition (LPCVD) has been measured on a scale useful for micromachined devices; the results are compared to previous studies on poly-SiC thin films deposited by atmospheric pressure chemical-vapor deposition (APCVD) [Bellante et al., Appl. Phys. Lett. 86, 071920 (2005)]. Samples in this study included those with and without silicon dioxide (SiO2) sacrificial release layers. The LPCVD processing technique induces residual tensile stresses in the films. Doubly clamped microtensile specimens were fabricated using standard micromachining processes, and microindentation was used to initiate atomically sharp precracks. The residual stresses in the films create stress intensity factors K at the crack tips; upon release, the precracks whose K exceeded a critical value, KIC, propagated to failure. The fracture toughness KIC was the same for both types of devices, 2.9+/-0.2 MPa m1/2 for the SiC on Si samples and 3.0+/-0.2 MPa m1/2 for the SiC on SiO2/Si samples, and similar to that found for APCVD poly-SiC, 2.8<=KIC<=3.4 MPa m1/2 [Bellante et al., Appl. Phys. Lett. 86, 071920 (2005)], indicating that KIC is truly a structure-insensitive material property. The fracture toughness of poly-SiC compares favorably with that for polysilicon, 0.85+/-0.05 MPa m1/2 [Kahn et al., Science 298, 1215 (2002)].

  7. Gas chromatographic vapor pressure determination of atmospherically relevant oxidation products of β-caryophyllene and α-pinene

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  8. Pressure-dependent structures of amorphous red phosphorus and the origin of the first sharp diffraction peaks.

    PubMed

    Zaug, Joseph M; Soper, Alan K; Clark, Simon M

    2008-11-01

    Characterizing the nature of medium-range order (MRO) in liquids and disordered solids is important for understanding their structure and transport properties. However, accurately portraying MRO, as manifested by the first sharp diffraction peak (FSDP) in neutron and X-ray scattering measurements, has remained elusive for more than 80 years. Here, using X-ray diffraction of amorphous red phosphorus compressed to 6.30 GPa, supplemented with micro-Raman scattering studies, we build three-dimensional structural models consistent with the diffraction data. We discover that the pressure dependence of the FSDP intensity and line position can be quantitatively accounted for by a characteristic void distribution function, defined in terms of average void size, void spacing and void density. This work provides a template to unambiguously interpret atomic and void-space MRO across a broad range of technologically promising network-forming materials. PMID:18849976

  9. Pressure-dependent structures of amorphous red phosphorus and the origin of the first sharp diffraction peaks

    NASA Astrophysics Data System (ADS)

    Zaug, Joseph M.; Soper, Alan K.; Clark, Simon M.

    2008-11-01

    Characterizing the nature of medium-range order (MRO) in liquids and disordered solids is important for understanding their structure and transport properties. However, accurately portraying MRO, as manifested by the first sharp diffraction peak (FSDP) in neutron and X-ray scattering measurements, has remained elusive for more than 80 years. Here, using X-ray diffraction of amorphous red phosphorus compressed to 6.30GPa, supplemented with micro-Raman scattering studies, we build three-dimensional structural models consistent with the diffraction data. We discover that the pressure dependence of the FSDP intensity and line position can be quantitatively accounted for by a characteristic void distribution function, defined in terms of average void size, void spacing and void density. This work provides a template to unambiguously interpret atomic and void-space MRO across a broad range of technologically promising network-forming materials.

  10. Atmospheric-Pressure Chemical Vapor Deposition of Iron Pyrite Thin Films

    SciTech Connect

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

    2012-10-23

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

  11. Vapor Pressure Isotope Effects and the Stable Isotope Geochemistry of the Martian Surface

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.

    2002-12-01

    naturally must be understood before one could confidently identify carbon or oxygen isotope evidence for life. Recent experiments indicate that both ice/vapor and adsorbate/vapor phase changes produce oxygen isotope fractionations of the same direction and magnitude as those for condensation/evaporation of water vapor in the earth's atmosphere. This suggests that seasonal and longer-term cycles of condensation and release of CO2 produce variations of-order 10 % in d18O. The current seasonal cycle of ice-cap formation and sublimation likely produces a similar-magnitude latitudinal gradient in the d18O of CO2. This gradient must be sensitive to mixing between high- and low-latitude air and therefore provides a constraint on martian atmospheric circulation. In contrast, carbon isotopes of CO2 are not measurably fractionated by condensation/sublimation of ice and should be invariant in a martian atmosphere in which this is the only major phase change. Adsorption significantly (ca. 1 to 2 %) concentrates 13CO2 into the vapor phase and 12CO2 into adsorbate. This is opposite in direction to all familiar vapor-pressure isotope effects. Thus, cycles of adsorption/desorption of CO2 have a unique isotopic signature that should be distinguishable for other processes influencing the Martian atmosphere. Measurements of the variation in d13C of CO2 would constrain the extent to which the atmosphere and surface interact by adsorption/desorption processes.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  14. 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...

  15. Temperature influences the ability of tall fescue to control transpiration in response to atmospheric vapor pressure deficit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water availability for turfgrass systems is often limited, and likely to become more so in the future. These experiments examined the ability of tall fescue (Festuca arundinacea Schreb.) to control transpiration with increasing vapor pressure deficit and whether control was influenced by temperature...

  16. 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...

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

    EPA Science Inventory

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

  18. α-Pinene Autoxidation Products May Not Have Extremely Low Saturation Vapor Pressures Despite High O:C Ratios.

    PubMed

    Kurtén, Theo; Tiusanen, Kirsi; Roldin, Pontus; Rissanen, Matti; Luy, Jan-Niclas; Boy, Michael; Ehn, Mikael; Donahue, Neil

    2016-04-28

    COSMO-RS (conductor-like screening model for real solvents) and three different group-contribution methods were used to compute saturation (subcooled) liquid vapor pressures for 16 possible products of ozone-initiated α-pinene autoxidation, with elemental compositions C10H16O4-10 and C20H30O10-12. The saturation vapor pressures predicted by the different methods varied widely. COSMO-RS predicted relatively high saturation vapor pressures values in the range of 10(-6) to 10(-10) bar for the C10H16O4-10 "monomers", and 10(-11) to 10(-16) bar for the C20H30O10-12 "dimers". The group-contribution methods predicted significantly (up to 8 order of magnitude) lower saturation vapor pressures for most of the more highly oxidized monomers. For the dimers, the COSMO-RS predictions were within the (wide) range spanned by the three group-contribution methods. The main reason for the discrepancies between the methods is likely that the group-contribution methods do not contain the necessary parameters to accurately treat autoxidation products containing multiple hydroperoxide, peroxy acid or peroxide functional groups, which form intramolecular hydrogen bonds with each other. While the COSMO-RS saturation vapor pressures for these systems may be overestimated, the results strongly indicate that despite their high O:C ratios, the volatilities of the autoxidation products of α-pinene (and possibly other atmospherically relevant alkenes) are not necessarily extremely low. In other words, while autoxidation products are able to adsorb onto aerosol particles, their evaporation back into the gas phase cannot be assumed to be negligible, especially from the smallest nanometer-scale particles. Their observed effective contribution to aerosol particle growth may therefore involve rapid heterogeneous reactions (reactive uptake) rather than effectively irreversible physical absorption. PMID:27049168

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

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

  1. Vapor pressure and gas phase PVT data and correlation for 1,1,1-trifluoroethane (R143a)

    SciTech Connect

    Giuliani, G.; Polonara, F.; Kumar, S. |; Zazzini, P.

    1995-07-01

    A constant volume apparatus has been used to measure the vapor pressure and single phase densities (PVT) for 1,1,1-trifluoroethane (R143a), an ozone friendly refrigerant. The sample has a purity greater than 99.91% by mass. The measurements were done from 244 to 365 K at pressures up to 4.4 MPa and at densities ranging from 5% to 99% of the critical density. The uncertainties involved in the measurement of temperature, pressure, mass, volume, and specific volume are explicitly given. Thirty-three values for the vapor pressure and sixty-three densities along six isochores are presented and have been compared with previously published data and correlations. A Wagner type correlation for the vapor pressure and a Martin-Hou equation of state have been used to fit the measured data, which have been analyzed using the average absolute deviation, bias, and standard deviation. The gas phase densities have been used to determine the second virial coefficients.

  2. Vapor pressure and viscosity of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione

    SciTech Connect

    George, M.A.; Young, K.M.; Robertson, E.A. III; Beck, S.E.; Voloshin, G.

    1998-01-01

    1,1,1,5,5,5-Hexafluoro-2,4-pentanedione (H{sup +}hfac) is a potential vapor-phase cleaning agent for removing trace transition metals from silicon wafer surfaces and for in situ removal of spurious bulk copper in Cu CVD chamber cleaning applications. The viscosity and vapor pressure of the reactive chelating ligand, H{sup +}hfac have been determined. The viscosity of liquid H{sup +}hfac was determined to be (1.39 {+-} 0.19) {times} 10{sup {minus}3} Pa{center_dot}s at 24 C and (8.35 {+-} 0.25) {times} 10{sup {minus}4} Pa{center_dot}s at 35 C. The vapor pressure of H{sup +}hfac was found to range from 4 kPa at 0 C to 49.5 kPa at 57 C. The viscosity was measured using a capillary tube viscometer, and the vapor pressure was measured using a mass transfer gas saturation apparatus. These methods were employed because conventional methodologies would have produced unreliable data due to the formation of the tetrol hydrate of H{sup +}hfac inside the apparatus and potentially exposed laboratory personnel to hazardous working conditions.

  3. 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.

  4. High-pressure thermal oxidation of n-GaAs in an atmosphere of oxygen and water vapor

    NASA Astrophysics Data System (ADS)

    Basu, Nandita; Bhat, K. N.

    1988-06-01

    A low-temperature (˜250 °C) high-pressure oxidation technique is used for the thermal oxidation of gallium arsenide in an ambient of oxygen and water vapor. It is shown that a uniform and chemically stable oxide with high band-gap energy can be grown on GaAs by this process. The role of water vapor and oxygen is studied in detail to obtain information on the oxidation mechanism. The electrical characteristics and the composition of this oxide are presented to demonstrate its suitability for surface passivation and metal-oxide-semiconductor devices.

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

    USGS Publications Warehouse

    Fournier, R.O.

    1976-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  7. [Optical Spectroscopy for High-Pressure Microwave Plasma Chemical Vapor Deposition of Diamond Films].

    PubMed

    Cao, Wei; Ma, Zhi-bin

    2015-11-01

    Polycrystalline diamond growth by microwave plasma chemical vapor deposition (MPCVD) at high-pressure (34.5 kPa) was investigated. The CH₄/H₂/O₂plasma was detected online by optical emission spectroscopy (OES), and the spatial distribution of radicals in the CH₄/H₂/O₂plasma was studied. Raman spectroscopy was employed to analyze the properties of the diamond films deposited in different oxygen volume fraction. The uniformity of diamond films quality was researched. The results indicate that the spectrum intensities of C₂, CH and Hα decrease with the oxygen volume fraction increasing. While the intensity ratios of C₂, CH to Hα also reduced as a function of increasing oxygen volume fraction. It is shown that the decrease of the absolute concentration of carbon radicals is attributed to the rise volume fraction of oxygen, while the relative concentration of carbon radicals to hydrogen atom is also reducing, which depressing the growth rate but improving the quality of diamond film. Furthermore, the OH radicals, role of etching, its intensities increase with the increase of oxygen volume fraction. Indicated that the improvement of OH concentration is also beneficial to reduce the content of amorphous carbon in diamond films. The spectrum space diagnosis results show that under high deposition pressure the distribution of the radicals in the CH₄/H₂/O₂plasma is inhomogeneous, especially, that of radical C₂ gathered in the central region. And causing a rapid increase of non-diamond components in the central area, eventually enable the uneven distribution of diamond films quality. PMID:26978897

  8. 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

  9. 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

  10. Combinatorial atmospheric pressure chemical vapor deposition (cAPCVD): a route to functional property optimization.

    PubMed

    Kafizas, Andreas; Parkin, Ivan P

    2011-12-21

    We demonstrate how combinatorial atmospheric pressure chemical vapor deposition (cAPCVD) can be used as a synthetic tool for rapidly optimizing the functional properties of thin-films, by analyzing the self-cleaning properties of tungsten doped anatase as an example. By introducing reagents at separate points inside the reactor, a tungsten/titanium compositional gradient was formed and a diverse range of film growth conditions were obtained. By partially mixing the metal sources, a combinatorial film with a compositional profile that varied primarily in the lateral plane was synthesized. A combinatorial thin-film of anatase TiO(2) doped with an array of tungsten levels as a solid solution ranging from 0.38-13.8 W/Ti atom % was formed on a single glass substrate. The compositional-functional relationships were understood through comprehensively analyzing combinatorial phase space, with 200 positions investigated by high-throughput methods in this study. Physical and functional properties, and their compositional dependencies, were intercorrelated. It was found that increases in photocatalytic activity and conductivity were most highly dependent on film crystallinity within the 0.38-13.8 atom % W/Ti doping regime. However, enhancements in photoinduced surface wetting were primarily dependent on increases in preferred growth in the (211) crystal plane. PMID:22050427

  11. 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.

  12. Low-temperature-grown continuous graphene films from benzene by chemical vapor deposition at ambient pressure.

    PubMed

    Jang, Jisu; Son, Myungwoo; Chung, Sunki; Kim, Kihyeun; Cho, Chunhum; Lee, Byoung Hun; Ham, Moon-Ho

    2015-01-01

    There is significant interest in synthesizing large-area graphene films at low temperatures by chemical vapor deposition (CVD) for nanoelectronic and flexible device applications. However, to date, low-temperature CVD methods have suffered from lower surface coverage because micro-sized graphene flakes are produced. Here, we demonstrate a modified CVD technique for the production of large-area, continuous monolayer graphene films from benzene on Cu at 100-300 °C at ambient pressure. In this method, we extended the graphene growth step in the absence of residual oxidizing species by introducing pumping and purging cycles prior to growth. This led to continuous monolayer graphene films with full surface coverage and excellent quality, which were comparable to those achieved with high-temperature CVD; for example, the surface coverage, transmittance, and carrier mobilities of the graphene grown at 300 °C were 100%, 97.6%, and 1,900-2,500 cm(2) V(-1) s(-1), respectively. In addition, the growth temperature was substantially reduced to as low as 100 °C, which is the lowest temperature reported to date for pristine graphene produced by CVD. Our modified CVD method is expected to allow the direct growth of graphene in device manufacturing processes for practical applications while keeping underlying devices intact. PMID:26658923

  13. Improved ultrathin oxynitride formed by thermal nitridation and low pressure chemical vapor deposition process

    NASA Astrophysics Data System (ADS)

    Maiti, Bikas; Hao, Ming Yin; Lee, Insup; Lee, Jack C.

    1992-10-01

    In this letter, we will present the electrical and reliability characteristics of ultrathin oxynitrides (65-73 Å) formed by thermal nitridation of silicon substrate followed by deposition of silicon dioxide by low pressure chemical vapor deposition (LPCVD) technique. The dielectric integrity has been compared to those of the conventional thermal oxide and reoxidized nitrided oxides. It has been found that the new oxynitrides have lower electron trapping, higher charge-to-breakdown, and lower interface state generation under electrical stress even in comparison to reoxidized nitrided oxides with the same thermal budget. The improved characteristics are believed to be due to the combination of the nitrogen-rich layer at the Si/SiO2 interface, the higher quality of LPCVD oxides over thermally grown oxides, and the reduced hydrogen concentration in the dielectrics in comparison to conventional nitrided oxides. The results indicate that these new oxynitride films may be promising for ultra large scale integrated metal-oxide-semiconductor device applications, especially in cases where low thermal budget processes are desirable.

  14. Low-temperature-grown continuous graphene films from benzene by chemical vapor deposition at ambient pressure

    PubMed Central

    Jang, Jisu; Son, Myungwoo; Chung, Sunki; Kim, Kihyeun; Cho, Chunhum; Lee, Byoung Hun; Ham, Moon-Ho

    2015-01-01

    There is significant interest in synthesizing large-area graphene films at low temperatures by chemical vapor deposition (CVD) for nanoelectronic and flexible device applications. However, to date, low-temperature CVD methods have suffered from lower surface coverage because micro-sized graphene flakes are produced. Here, we demonstrate a modified CVD technique for the production of large-area, continuous monolayer graphene films from benzene on Cu at 100–300 °C at ambient pressure. In this method, we extended the graphene growth step in the absence of residual oxidizing species by introducing pumping and purging cycles prior to growth. This led to continuous monolayer graphene films with full surface coverage and excellent quality, which were comparable to those achieved with high-temperature CVD; for example, the surface coverage, transmittance, and carrier mobilities of the graphene grown at 300 °C were 100%, 97.6%, and 1,900–2,500 cm2 V−1 s−1, respectively. In addition, the growth temperature was substantially reduced to as low as 100 °C, which is the lowest temperature reported to date for pristine graphene produced by CVD. Our modified CVD method is expected to allow the direct growth of graphene in device manufacturing processes for practical applications while keeping underlying devices intact. PMID:26658923

  15. Chain Assemblies from Nanoparticles Synthesized by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition: The Computational View.

    PubMed

    Mishin, Maxim V; Zamotin, Kirill Y; Protopopova, Vera S; Alexandrov, Sergey E

    2015-12-01

    This article refers to the computational study of nanoparticle self-organization on the solid-state substrate surface with consideration of the experimental results, when nanoparticles were synthesised during atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD). The experimental study of silicon dioxide nanoparticle synthesis by AP-PECVD demonstrated that all deposit volume consists of tangled chains of nanoparticles. In certain cases, micron-sized fractals are formed from tangled chains due to deposit rearrangement. This work is focused on the study of tangled chain formation only. In order to reveal their formation mechanism, a physico-mathematical model was developed. The suggested model was based on the motion equation solution for charged and neutral nanoparticles in the potential fields with the use of the empirical interaction potentials. In addition, the computational simulation was carried out based on the suggested model. As a result, the influence of such experimental parameters as deposition duration, particle charge, gas flow velocity, and angle of gas flow was found. It was demonstrated that electrical charges carried by nanoparticles from the discharge area are not responsible for the formation of tangled chains from nanoparticles, whereas nanoparticle kinetic energy plays a crucial role in deposit morphology and density. The computational results were consistent with experimental results. PMID:26682441

  16. High vapor pressure deficit drives salt-stress-induced rice yield losses in India.

    PubMed

    Tack, Jesse; Singh, Rakesh K; Nalley, Lawton L; Viraktamath, Basavaraj C; Krishnamurthy, Saraswathipura L; Lyman, Nate; Jagadish, Krishna S V

    2015-04-01

    Flooded rice is grown across wide geographic boundaries from as far north as Manchuria and as far south as Uruguay and New South Wales, primarily because of its adaptability across diverse agronomic and climatic conditions. Salt-stress damage, a common occurrence in delta and coastal rice production zones, could be heightened by the interactions between high temperature and relative humidity (vapor pressure deficit--VPD). Using temporal and spatial observations spanning 107 seasons and 19 rice-growing locations throughout India with varying electrical conductivity (EC), including coastal saline, inland saline, and alkaline soils, we quantified the proportion of VPD inducing salinity damage in rice. While controlling for time-invariant factors such as trial locations, rice cultivars, and soil types, our regression analysis indicates that EC has a nonlinear detrimental effect on paddy rice yield. Our estimates suggest these yield reductions become larger at higher VPD. A one standard deviation (SD) increase in EC from its mean value is associated with 1.68% and 4.13% yield reductions at median and maximum observed VPD levels, respectively. Yield reductions increase roughly sixfold when the one SD increase is taken from the 75th percentile of EC. In combination, high EC and VPD generate near catastrophic crop loss as predicted yield approaches zero. If higher VPD levels driven by global warming materialize in conjunction with rising sea levels or salinity incursion in groundwater, this interaction becomes an important and necessary predictor of expected yield losses and global food security. PMID:25379616

  17. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    SciTech Connect

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-02

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  18. Low-temperature-grown continuous graphene films from benzene by chemical vapor deposition at ambient pressure

    NASA Astrophysics Data System (ADS)

    Jang, Jisu; Son, Myungwoo; Chung, Sunki; Kim, Kihyeun; Cho, Chunhum; Lee, Byoung Hun; Ham, Moon-Ho

    2015-12-01

    There is significant interest in synthesizing large-area graphene films at low temperatures by chemical vapor deposition (CVD) for nanoelectronic and flexible device applications. However, to date, low-temperature CVD methods have suffered from lower surface coverage because micro-sized graphene flakes are produced. Here, we demonstrate a modified CVD technique for the production of large-area, continuous monolayer graphene films from benzene on Cu at 100-300 °C at ambient pressure. In this method, we extended the graphene growth step in the absence of residual oxidizing species by introducing pumping and purging cycles prior to growth. This led to continuous monolayer graphene films with full surface coverage and excellent quality, which were comparable to those achieved with high-temperature CVD; for example, the surface coverage, transmittance, and carrier mobilities of the graphene grown at 300 °C were 100%, 97.6%, and 1,900-2,500 cm2 V-1 s-1, respectively. In addition, the growth temperature was substantially reduced to as low as 100 °C, which is the lowest temperature reported to date for pristine graphene produced by CVD. Our modified CVD method is expected to allow the direct growth of graphene in device manufacturing processes for practical applications while keeping underlying devices intact.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  2. 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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  4. 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

  5. vapor pressure of uranyl beta-diketonates. IV. effect of adduct formation on volatility of uranyl pivaloyltrifluoroacetonate

    SciTech Connect

    Sidorenko, G.V.; Suglobov, D.N.

    1986-07-01

    Gas-phase adduct formation of uranyl pivaloyltrifluoroacetonate (I) with donor active materials such as trimethyl phosphate (TMP), pyridine (Py), tetrahydrofuran (THF), and ethanol (EtOH) was demonstrated by IR spectroscopy. Vapor pressure of the I-TMF adduct was measured by the flow method. The volatility of I was studied in a stream of helium saturated with vapors of donor-active materials: Py, THF, diethyl ether (Et/sub 2/O), EtOH, and acetonitrile. The temperature dependence of the pressure of saturated I.TMP and I vapor in a stream of neutral ligand vapor is described by log p (Pa) = -A/T + B. Following are, respectively, neutral ligand, T range (degreeK), and coefficiencts A, B: TMP 383453, 4648 +/- 48, 12.06 +/- 0.18; Py, 383-463, 5277 +/- 87, 13.36 +/- 0.21; THF, 363453, 4662 +/- 69, 12.66 +/- 0.17; Et/sub 2/O, 353-423, 4864 +/- 110, 13.29 +/- 0.28; EtOH, 363-443, 4509 +/- 89, 12.18 +/- 0.22. Adduct formation with these neutral ligands decreases the volatility of I significantly. A tendency to increase of adduct volatility was observed when the donor properties of the neutral ligand decrease.

  6. 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.

  7. Vapor pressures and gas-phase PVT data for 1-chloro-1,2,2,2-tetrafluoroethane (R124)

    SciTech Connect

    Boyes, S.J.; Weber, L.A. )

    1994-05-01

    We present new data for the vapor pressure and PVT surface of 1-chloro-1,2,2,2-tetrafluoroethane (designated R124 by the refrigeration industry) in the temperature range 278-423 K. The PVT data are for the gas phase at densities up to 1.5 times the critical density. Correlating equations are given for the vapor pressures from 220 K to the critical temperature, 395.43 K, and for the PVT surface at densities up to 2 mol [center dot] L[sup [minus]1] (approximately 0.5 times the critical density). Second and third virial coefficients have been derived from the PVT measurements. 16 refs., 4 figs., 6 tabs.

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

    SciTech Connect

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

    1990-01-01

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

  9. Vapor pressure deficit is as important as soil moisture in determining limitations to evapotranspiration during drought

    NASA Astrophysics Data System (ADS)

    Novick, K. A.; Williams, C. A.; Phillips, R.; Oishi, A. C.; Sulman, B. N.; Bohrer, G.; Ficklin, D. L.

    2015-12-01

    The decoupling between potential evapotranspiration (PET) and actual evapotranspiration (AET) is a useful metric to characterize ecosystem hydrologic stress. As hydrologic stress evolves, PET increases following increases in incident radiation and vapor pressure deficit (VPD). AET, on the other hand, remains stationary or decreases due to declines in surface conductance imposed by decreasing soil water and stomatal closure under high VPD. Historically, it has been difficult to quantify the extent to which soil moisture as compared to VPD ultimately limits AET during hydrologic stress. Part of this difficulty relates to the strong correlation between soil moisture and VPD at timescales over which hydrologic stress evolves (weekly to monthly). Further, while it is relatively easy to manipulate soil moisture in experimental settings, manipulating VPD is much more difficult. Recently, the proliferation of eddy covariance flux sites has produced a rich collection of AET observations at fine timescales (i.e. hourly to daily) over which VPD and soil moisture are more decoupled. In this study, we leverage such data to quantify the extent to which soil moisture versus VPD constrains AET in more than 25 Ameriflux sites spanning a wide climate gradient. We found that AET was most significantly limited by soil moisture in dry sites where the annual PET was much higher than precipitation. VPD limitations to AET dominated in wetter sites, but even among the driest sites, they were of similar magnitude to soil moisture limitations. Our results highlight the critical, if at time underappreciated, role of VPD in determining ecohydrological functioning during periods of hydrologic stress. We also leverage these results together with future projections for VPD, soil moisture, and other relevant meteorological drivers to explore the extent to which the coherence between VPD and soil moisture, and their relative importance for limiting AET, may shift under future climate conditions.

  10. 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

  11. Simple method for preparing hydrogenated amorphous silicon films by chemical vapor deposition at atmospheric pressure

    SciTech Connect

    Ellis, F.B. Jr.

    1983-01-01

    An inexpensive one-step method is presented for fabricating hydrogenated amorphous silicon (a-Si:H) films with good photovoltaic properties using chemical vapor deposition (CVD) from a mixture of silane, disilane, trisilane, and higher polysilanes in hydrogen at one atmosphere total pressure. The gas mixture is generated by the action of dilute acid on magnesium silicide and used immediately in the CVD process. Thus, elaborate techniques for handling, transporting or storing the pyrophoric polysilanes are avoided. In addition, the method requires no expensive vacuum or electrical equipment. The conditions necessary for high (approx. =10%) hydrogen incorporation and very high deposition rates (50-100 A/sec) are explained. Experimental parameters are explained and properties as a function of these parameters are shown. The measurements include hydrogen content, optical, electrical and photovoltaic properties of the a-Si:H films. A chemical kinetic model is presented for this and other silane and polysilane CVD systems between about 400 and 600/sup 0/C. Both homogeneous and heterogeneous reactions are considered. The model is derived from homogeneous gas-phase silane and polysilane chemistry and predicts, in agreement with our experiments, that the homogeneous gas-phase chemistry determines the a-Si:H film growth rate under a variety of conditions. The model is sufficiently predictive to be useful in determining appropriate experimental conditions. Stable solar cells are proposed for a-Si:H and fluorine doped tin oxide which can be produced by CVD at very high deposition rates. The unstable a-Si:H/tin oxide interface is eliminated by a very thin layer of titanium nitride and oxide between the a-Si:H and tin oxide.

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

    SciTech Connect

    Hoffman, D.M.; Atagi, L.M. |; Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang; Rubiano, R.R.; Springer, R.W.; Smith, D.C.

    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.

  13. Effects of Pressure on Optically Active Deep Levels in Phosphorus Doped ZnSe

    NASA Astrophysics Data System (ADS)

    Weinstein, B. A.; Iota, V.

    1998-03-01

    We report high pressure photoluminescence (PL) and PL-excitation (PLE) studies at 8K of the 'midgap' emission in P-doped ZnSe using a diamond-cell with He medium. The dominant emission at low pressure is due to donor-acceptor-pair (DAP) transitions between shallow donors and deep trigonally relaxed P_Se acceptors.(J. Davies, et al., J. Luminescence 18/19, 322 (1979)) Its PL and PLE peaks shift by 8.2meV/kbar and 5.9meV/kbar, respectively -- Stokes shift decreasing with pressure. At 35kbar a new PL band, shifting to lower energy (-5.4meV/kbar), emerges from above the absorption edge, and concurrently the original DAP PL quenches. This shows that a resonant level, a deep donor or possibly a P_Se antibonding state,(R. Watts, et al., Phys. Rev. B3), 404 (1971) crosses the conduction edge into the gap. A third PL band is seen only with internse UV excitation. It occurs initially as a high energy shoulder of the original DAP peak, but shifts more rapidly upward (9.4meV/kbar) until it crosses the edge and quenches at 40kbar. We discuss candidates for this band, including donor-P_Se complexes, and we compare our results to similar work on the Zn vacancy in ZnSe. (figures)

  14. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  16. Interactive response of photosynthetic characteristics in Haloxylon ammodendron and Hedysarum scoparium exposed to soil water and air vapor pressure deficits.

    PubMed

    Gong, Chunmei; Wang, Jiajia; Hu, Congxia; Wang, Junhui; Ning, Pengbo; Bai, Juan

    2015-08-01

    C4 plants possess better drought tolerance than C3 plants. However, Hedysarum scoparium, a C3 species, is dominant and widely distributed in the desert areas of northwestern China due to its strong drought tolerance. This study compared it with Haloxylon ammodendron, a C4 species, regarding the interactive effects of drought stress and different leaf-air vapor pressure deficits. Variables of interest included gas exchange, the activity levels of key C4 photosynthetic enzymes, and cellular anatomy. In both species, gas exchange parameters were more sensitive to high vapor pressure deficit than to strong water stress, and the net CO2 assimilation rate (An) was enhanced as vapor pressure deficits increased. A close relationship between An and stomatal conductance (gs) suggested that the species shared a similar response mechanism. In H. ammodendron, the activity levels of key C4 enzymes were higher, including those of phosphoenolpyruvate carboxylase (PEPC) and nicotinamide adenine dinucleotide phosphate-malate enzyme (NADP-ME), whereas in H. scoparium, the activity level of nicotinamide adenine dinucleotide-malate enzyme (NAD-ME) was higher. Meanwhile, H. scoparium utilized adaptive structural features, including a larger relative vessel area and a shorter distance from vein to stomata, which facilitated the movement of water. These findings implied that some C4 biochemical pathways were present in H. scoparium to respond to environmental challenges. PMID:26257361

  17. 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.

    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

  18. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... each pressure release, the pressure relief device shall be returned to a condition of no detectable.... (2) No later than 5 calendar days after the pressure release, the pressure relief device shall be... release, a new rupture disk shall be installed upstream of the pressure relief device as soon...

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

    NASA Astrophysics Data System (ADS)

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

    2006-01-01

    To determine evaporation coefficients for the major gaseous species that evaporate from silicate melts, the Hertz-Knudsen equation was used to model the compositions of residues of chondrule analogs produced by evaporation in vacuum by Hashimoto [Hashimoto A. (1983) Evaporation metamorphism in the early solar nebula-evaporation experiments on the melt FeO-MgO-SiO 2-CaO-Al 2O 3 and chemical fractionations of primitive materials. Geochem. J. 17, 111-145] and Wang et al. [Wang J., Davis A. M., Clayton R. N., Mayeda T. K., Hashimoto A. (2001) Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO 2-CaO-Al 2O 3-TiO 2 rare earth element melt system. Geochim. Cosmochim. Acta 65, 479-494], in vacuum and in H 2 by Yu et al. [Yu Y., Hewins R. H., Alexander C. M. O'D., Wang J. (2003) Experimental study of evaporation and isotopic mass fractionation of potassium in silicate melts. Geochim. Cosmochim. Acta 67, 773-786], and in H 2 by Cohen et al. [Cohen B. A., Hewins R. H., Alexander C. M. O'D. (2004) The formation of chondrules by open-system melting of nebular condensates. Geochim. Cosmochim. Acta 68, 1661-1675]. Vapor pressures were calculated using the thermodynamic model of Ghiorso and Sack [Ghiorso M. S., Sack R. O. (1995) Chemical mass transfer in magmatic processes IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures. Contrib. Mineral. Petrol. 119, 197-212], except for the late, FeO-free stages of the Wang et al. (2001) and Cohen et al. (2004) experiments, where the CMAS activity model of Berman [Berman R. G. (1983) A thermodynamic model for multicomponent melts, with application to the system CaO-MgO-Al 2O 3-SiO 2. Ph.D. thesis, University of British Columbia] was used. From these vapor pressures, evaporation coefficients ( α) were obtained that give the best fits to the time variation of the residue compositions

  20. Evaluation of saturation vapor pressure over hypersaline water bodies at the southern edge of the Dead Sea, Jordan

    SciTech Connect

    Oroud, I.M. )

    1994-12-01

    The activity coefficient and saturation vapor pressure for hypersaline solutions located at the southern edge of the Dead Sea are computed analytically. The collected data consist of temperature and evaporation rates measured for a freshwater pan and three other hypersaline solutions with specific gravities of 1.26, 1.31, and 1.34, respectively. The activity coefficients of the three saline pans were computed after accounting for the effect of buoyancy, which was included in the computations because of consistently large, positive virtual temperature differences between the saline pans and the ambient air. The ratios of saline to fresh pan evaporation (Es/Ef: the [alpha] ratio) of the present study are also compared to data reported for the Bonneville Salt Brines, Utah. It is found that the a ratios of the present study, although conducted over an extended period of time, are larger than those reported for the Bonneville Brines. Results of the present study imply that evaporation from the various brine-concentrated, shallow lakes at the southern edge of the Dead Sea is likely to proceed during the entire year, and water vapor deposition from the atmosphere, due to an inverted vapor pressure, is less likely to occur particularly for brines with specific gravities of less than 1.3.

  1. 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.

    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 μm) at very high rates (up to 3 μm{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.

  2. CVD mullite coatings in high-temperature, high-pressure air-H{sub 2}O[Chemical Vapor Deposition

    SciTech Connect

    Haynes, J.A.; Lance, M.J.; Cooley, K.M.; Ferber, M.K.; Lowden, R.A.; Stinton, D.P.

    2000-03-01

    Crystalline mullite was deposited by chemical vapor deposition (CVD) onto SiC/SiC composites overlaid with CVD SiC. Specimens were exposed to isothermal oxidation tests in high-pressure air +H{sub 2}O at 1,200 C. Unprotected CVD SiC formed silica scales with a dense amorphous inner layer and a thick, porous, outer layer of cristobalite. Thin coatings ({approximately}2{mu}m) of dense CVD mullite effectively suppressed the rapid oxidation of CVD SiC. No microstructural evidence of mullite volatility was observed under these temperature, pressure, and low-flow-rate conditions. Results of this preliminary study indicate that dense, crystalline, high-purity CVD mullite is stable and protective in low-velocity, high-pressure, moisture-containing environments.

  3. Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Quarterly report, April-June 1980

    SciTech Connect

    Johnson, I.; Swift, W.M.; Lee, S.H.D.; Boyd, W.A.

    1980-07-01

    In the application of pressurized fluidized-bed combustors (PFBC) to the generation of electricity, hot corrosion of gas turbine components by alkali metal compounds is a potential problem. The objective of this investigation is to develop a method for removing these gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. A granular-bed filter, using either diatomaceous earth or activated bauxite as the bed material, is the concept currently being studied. Results are presented for the testing of diatomaceous earth for alkali vapor sorption at 800/sup 0/C and 9-atm pressure, using a simulated flue gas. Activated bauxite sorbent can be regenerated by leaching with water, and the kinetics of the leaching is under study.

  4. Reduction in the Vapor Pressure in Condensation on Cold Droplets of a Liquid

    NASA Astrophysics Data System (ADS)

    Bochkareva, E. M.; Nemtsev, V. A.; Sorokin, V. V.; Terekhov, V. V.; Terekhov, V. I.

    2016-06-01

    A physicomathematical model of the process of depressurization in a pure saturated and superheated vapor due to the injection of monodisperse cold droplets of a liquid has been developed. A cellular model has been developed that is based on solving the equation of heat conduction in a liquid phase and on the integral method for a gas phase in a spherically symmetric one-dimensional formulation. Numerical investigation has been carried out of the influence of the size and concentration of the droplets and of the initial parameters of the steam on the dynamics of depressurization during the vapor condensation on the droplets.

  5. Reduction in the Vapor Pressure in Condensation on Cold Droplets of a Liquid

    NASA Astrophysics Data System (ADS)

    Bochkareva, E. M.; Nemtsev, V. A.; Sorokin, V. V.; Terekhov, V. V.; Terekhov, V. I.

    2016-05-01

    A physicomathematical model of the process of depressurization in a pure saturated and superheated vapor due to the injection of monodisperse cold droplets of a liquid has been developed. A cellular model has been developed that is based on solving the equation of heat conduction in a liquid phase and on the integral method for a gas phase in a spherically symmetric one-dimensional formulation. Numerical investigation has been carried out of the influence of the size and concentration of the droplets and of the initial parameters of the steam on the dynamics of depressurization during the vapor condensation on the droplets.

  6. Surface vapor conductance derived from the ETRHEQ: Dependence on environmental variables and similarity to Oren's stomatal stress model for vapor pressure deficit

    NASA Astrophysics Data System (ADS)

    Salvucci, G.; Rigden, A. J.

    2015-12-01

    Daily time series of evapotranspiration and surface conductance to water vapor were estimated using the ETRHEQ method (Evapotranspiration from Relative Humidity at Equilibrium). ETRHEQ has been previously compared with ameriflux site-level measurements of ET at daily and seasonal time scales, with watershed water balance estimates, and with various benchmark ET data sets. The ETRHEQ method uses meteorological data collected at common weather stations and estimates the surface conductance by minimizing the vertical variance of the calculated relative humidity profile averaged over the day. The key advantage of the ETRHEQ method is that it does not require knowledge of the surface state (soil moisture, stomatal conductance, leaf are index, etc.) or site-specific calibration. The daily estimates of conductance from 229 weather stations for 53 years were analyzed for dependence on environmental variables known to impact stomatal conductance and soil diffusivity: surface temperature, surface vapor pressure deficit, solar radiation, antecedent precipitation (as a surrogate for soil moisture), and a seasonal vegetation greenness index. At each site the summertime (JJAS) conductance values estimated from ETRHEQ were fitted to a multiplicate Jarvis-type stress model. Functional dependence was not proscribed, but instead fitted using flexible piecewise-linear splines. The resulting stress functions reproduce the time series of conductance across a wide range of ecosystems and climates. The VPD stress term resembles that proposed by Oren (i.e., 1-m*log(VPD) ), with VPD measured in kilopascals. The equivalent value of m derived from our spline-fits at each station varied over a remarkably small range of 0.58 to 0.62, in agreement with Oren's original analysis based on leaf and tree-level measurements.

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

    SciTech Connect

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

    2009-11-01

    Boron nitride nanotubes (BNNTs) are desired for their exceptional mechanical, electronic, thermal, structural, textural, optical, and quantum properties. A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

  8. Synthesis of multi-layer graphene films on copper tape by atmospheric pressure chemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Tu; Doan Le, Huu; Chuc Nguyen, Van; Thanh Tam Ngo, Thi; Quang Le, Dinh; Nghia Nguyen, Xuan; Phan, Ngoc Minh

    2013-09-01

    Graphene films were successfully synthesized by atmospheric pressure chemical vapor deposition (APCVD) method. Methane (CH4) gas and copper (Cu) tapes were used as a carbon source and a catalyst, respectively. The CVD temperature and time were in the range of 800-1000 °C and 10 s to 45 min, respectively. The role of the CVD temperature and time on the growth of graphene films was investigated in detail via scanning electron microscopy (SEM) and Raman spectroscopy techniques. The results of SEM images and Raman spectra show that the quality of the graphene films was improved with increasing of CVD temperature due to the increase of catalytic activity.

  9. 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.

  10. 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.

  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

    2016-02-01

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

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

    2002-01-01

    Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

  13. Various Shapes of ZnO and CdO Nanostructures Grown by Atmospheric-Pressure Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Terasako, Tomoaki; Fujiwara, Tetsuro; Yagi, Masakazu; Shirakata, Sho

    2011-01-01

    Various shapes of ZnO and CdO nanostructures were successfully grown on a- and c-plane sapphire substrates coated with Au nanocolloidal solution by atmospheric-pressure chemical vapor deposition methods under a simultaneous source supply of metal powder (Zn or Cd) and H2O. The ZnO and CdO nanorods (NRs) grown at higher substrate temperatures (TSs) exhibited tapered shapes, resulting from the competition between the axial growth due to the vapor-liquid-solid (VLS) mechanism and the radial growth due to the vapor-solid (VS) mechanism. The alternate source supply of Zn and H2O was found to be effective for suppressing the tapering of ZnO NRs. The appearance of the Y- and T-shaped nanotrees of CdO may be due to the splitting and migration of catalytic particles during the growth process. These results suggest that both the source supply sequence and the substrate temperature are important factors for the shape design of oxide nanostructures.

  14. Copper vapor laser machining of polyimide and polymethylmethacrylate in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Ventzek, P. L. G.; Gilgenbach, R. M.; Ching, C. H.; Lindley, R. A.; McColl, W. B.

    1992-10-01

    A repetitively pulsed copper vapor laser (510 and 578 nm) is used to machine an opaque polymer (polyimide-Vespel) and a transparent polymer (polymethylmethacrylate-Lucite). Lucite is machinable by coating the surface with an ink which is semi-opaque to the green and yellow laser light. The repetition rate of the laser was 10 kHz with approximately 0.35 mJ/pulse and 3.5 W average power at the copper vapor laser wavelengths for a pulse width of 40 ns. The copper vapor laser thermally loads the target, generating thermal waves and sound waves in the gas which are investigated using HeNe laser beam deflection. The gas adjacent to the target is heated to steady state on the order of 100-400 s. Above the etching threshold, at approximately 10 mJ/cm2/pulse, the target is rapidly machined: 2-mm-diam, 2-mm-deep holes are drilled in 300 s in Vespel. At higher fluences of 100-150 mJ/cm2/pulse in 760 Torr of air it takes 180 s to bore through a 2-mm-thick disk of Vespel. The machined surfaces of the two polymers are very different. Machined Vespel samples are charred and cratered, whereas the Lucite samples show evidence of melting with little charring. The machining of polymers by visible-light copper vapor lasers is being compared to UV photoablation by KrF excimer laser light in order to study thermal versus nonthermal etching mechanisms.

  15. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid.

    PubMed

    Rodier, Marion; Li, Qingfeng; Berg, Rolf Willestofte; Bjerrum, Niels Janniksen

    2016-07-01

    A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case the scattering ratios between water and reference ν1 Q-branches were found to be 1.20 ± 0.03 and 0.40 ± 0.02 for H2 and CH4, respectively. PMID:27273974

  16. 3D transient multiphase model for keyhole, vapor plume, and weld pool dynamics in laser welding including the ambient pressure effect

    NASA Astrophysics Data System (ADS)

    Pang, Shengyong; Chen, Xin; Zhou, Jianxin; Shao, Xinyu; Wang, Chunming

    2015-11-01

    The physical process of deep penetration laser welding involves complex, self-consistent multiphase keyhole, metallic vapor plume, and weld pool dynamics. Currently, efforts are still needed to understand these multiphase dynamics. In this paper, a novel 3D transient multiphase model capable of describing a self-consistent keyhole, metallic vapor plume in the keyhole, and weld pool dynamics in deep penetration fiber laser welding is proposed. Major physical factors of the welding process, such as recoil pressure, surface tension, Marangoni shear stress, Fresnel absorptions mechanisms, heat transfer, and fluid flow in weld pool, keyhole free surface evolutions and solid-liquid-vapor three phase transformations are coupling considered. The effect of ambient pressure in laser welding is rigorously treated using an improved recoil pressure model. The predicated weld bead dimensions, transient keyhole instability, weld pool dynamics, and vapor plume dynamics are compared with experimental and literature results, and good agreements are obtained. The predicted results are investigated by not considering the effects of the ambient pressure. It is found that by not considering the effects of ambient pressure, the average keyhole wall temperature is underestimated about 500 K; besides, the average speed of metallic vapor will be significantly overestimated. The ambient pressure is an essential physical factor for a comprehensive understanding the dynamics of deep penetration laser welding.

  17. Enhanced growth of high quality single crystal diamond by microwave plasma assisted chemical vapor deposition at high gas pressures

    SciTech Connect

    Liang Qi; Chin Chengyi; Lai, Joseph; Yan Chihshiue; Meng Yufei; Mao Hokwang; Hemley, Russell J.

    2009-01-12

    Single crystals of diamond up to 18 mm in thickness have been grown by microwave plasma assisted chemical vapor deposition at gas pressures of up to 350 torr. Growth rates of up to 165 {mu}m/h at 300 torr at high power density have been achieved. The processes were evaluated by optical emission spectroscopy. The high-quality single-crystal diamond grown at optimized conditions was characterized by UV-visible absorption and photoluminescence spectroscopy. The measurements reveal a direct relationship between residual absorption and nitrogen content in the gas chemistry. Fabrication of high quality single-crystal diamond at higher growth rates should be possible with improved reactor design that allows still higher gas synthesis pressures.

  18. Very narrow SiGe/Si quantum wells deposited by low-temperature atmospheric pressure chemical vapor deposition

    SciTech Connect

    Gruetzmacher, D.A.; Sedgwick, T.O.; Northrop, G.A.

    1993-05-01

    The optical, structural, and electrical properties of very narrow SiGe quantum wells grown by {open_quotes}ultra-clean{close_quotes} atmospheric pressure chemical vapor deposition (APCVD) are investigated. X-ray reflectivity data reveal abrupt interfaces with a root-mean-square roughness of not more than 0.2 nm. For the first time narrow (4.3 meV) excitonic photoluminescence (PL) spectra were obtained from APCVD grown samples containing SiGe wells with 12.5% to 32.5% Ge. For the narrowest wells PL doublets are observed which are attributed to atomic steps at the SiGe/Si interfaces. The Pl and x-ray diffractometry data show that process deposition control for well and barrier width is within the monolayer range. Resonant tunneling diodes fabricated with 2.5-mm-wide Si{sub 0.75}Ge{sub 0.25} wells show world record peak to valley ratios of 4.2. Magneto-transport measurements performed at high magnetic fields of two-dimensional hole gases exhibit pronounced Hall plateaus and well-defined Shubnikov de Hass oscillations, indicating high material quality. The results give evidence that atmospheric pressure chemical vapor deposition, which relies on gas switching sequences of the reactive gases in a hydrogen ambience, is able to produce interface abruptness comparable if not better than reported by any other technique. 22 refs., 7 figs.

  19. Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in the mid-infrared at atmospheric pressure

    SciTech Connect

    Johnson, Timothy J.; Sams, Robert L.; Burton, Sarah D.; Blake, Thomas A.

    2009-09-01

    We report quantitative broadband infrared spectra of vapor-phase hydrogen peroxide (H2O2) with all spectra pressure broadened to atmospheric pressure. The spectra were generated by flowing a concentrated solution (83 weight%) of H2O2 into a gently heated disseminator and diluting with a flow of pure nitrogen carrier gas. The water vapor lines were subtracted from the resulting spectra to yield the spectrum of pure H2O2. Comparison with previous results for the ν6 band strength (including hot bands) compares favorably with the results of Klee et al. [(1999) J. Mol. Spectr. 195, 154] as well as HITRAN. The present results are 433 and 467 cm-2 atm-1 (±8% and ±3% at 298 and 323 K, respectively) for the band strength, matching well the Klee value (S = 467 cm-2 atm-1 at 296 K) for the integrated band. Other bands in the 520-7500 cm-1 interval and their potential for atmospheric monitoring are discussed.

  20. Cohesive zone laws for void growth — II. Numerical field projection of elasto-plastic fracture processes with vapor pressure

    NASA Astrophysics Data System (ADS)

    Chew, Huck Beng; Hong, Soonsung; Kim, Kyung-Suk

    2009-08-01

    Modeling ductile fracture processes using Gurson-type cell elements has achieved considerable success in recent years. However, incorporating the full mechanisms of void growth and coalescence in cohesive zone laws for ductile fracture still remains an open challenge. In this work, a planar field projection method, combined with equilibrium field regularization, is used to extract crack-tip cohesive zone laws of void growth in an elastic-plastic solid. To this end, a single row of void-containing cell elements is deployed directly ahead of a crack in an elastic-plastic medium subjected to a remote K-field loading; the macroscopic behavior of each cell element is governed by the Gurson porous material relation, extended to incorporate vapor pressure effects. A thin elastic strip surrounding this fracture process zone is introduced, from which the cohesive zone variables can be extracted via the planar field projection method. We show that the material's initial porosity induces a highly convex traction-separation relationship — the cohesive traction reaches the peak almost instantaneously and decreases gradually with void growth, before succumbing to rapid softening during coalescence. The profile of this numerically extracted cohesive zone law is consistent with experimentally determined cohesive zone law in Part I for multiple micro-crazing in HIPS. In the presence of vapor pressure, both the cohesive traction and energy are dramatically lowered; the shape of the cohesive zone law, however, remains highly convex, which suggests that diffusive damage is still the governing failure mechanism.

  1. Vapor-liquid equilibria for the hexane + hexadecane and hexane + 1-hexadecanol systems at elevated temperatures and pressures

    SciTech Connect

    Joyce, P.C.; Thies, M.C.

    1998-09-01

    Fischer-Tropsch (F-T) synthesis produces a broad range of products (known as waxes) consisting primarily of paraffins, olefins, and alcohols with carbon numbers ranging from 1 up to about 200. Slurry bubble column (SBC) reactors are receiving increasing attention as the preferred way to carry out the F-T reaction. However, the separation of the reactor catalyst from the wax product is an issue that has yet to be satisfactorily resolved. Vapor and liquid equilibrium compositions have been measured for the hexane + hexadecane and the hexane + 1-hexadecanol systems at temperatures from 472.0 K to 623.0 K and pressures from 6.2 bar to 46.4 bar. A continuous-flow apparatus was used both to minimize possible thermal degradation and to accurately measure the lower hexadecanol concentrations in the vapor phase. Mixture critical pressures and compositions were also measured. Results indicate that the addition of the hydroxyl group to the C{sub 16} hydrocarbon backbone significantly affects the phase behavior with hexane.

  2. Ionic liquids by proton transfer: vapor pressure, conductivity, and the relevance of DeltapKa from aqueous solutions.

    PubMed

    Yoshizawa, Masahiro; Xu, Wu; Angell, C Austen

    2003-12-17

    We describe the behavior of the conductivity, viscosity, and vapor pressure of various binary liquid systems in which proton transfer occurs between neat Brönsted acids and bases to form salts with melting points below ambient. Such liquids form an important subgroup of the ionic liquid (IL) class of reaction media and electrolytes on which so much attention is currently being focused. Such "protic ionic liquids" exhibit a wide range of thermal stabilities. We find a simple relation between the limit set by boiling, when the total vapor pressure reaches one atm, and the difference in pK(a) value for the acid and base determined in dilute aqueous solutions. For DeltapK(a) values above 10, the boiling point elevation becomes so high (>300 degrees C) that preemptive decomposition prevents its measurement. The completeness of proton transfer in such cases is suggested by the molten salt-like values of the Walden product, which is used to distinguish good from poor ionic liquids. For the good ionic liquids, the hydrogen bonding of acid molecules to the proton-transfer anion is strong enough that boiling points, but not melting points, may maximize at the hydrogen-bonded dianion composition. High boiling liquids of this type constitute an interesting class of high-temperature protonic acid that may have high-temperature fuel cell applications. PMID:14664586

  3. [Time lag effect between stem sap flow and photosynthetically active radiation, vapor pressure deficit of Acacia mangium].

    PubMed

    Wang, Hua; Zhao, Ping; Cai, Xi-An; Ma, Ling; Rao, Xing-Quan; Zeng, Xiao-Ping

    2008-02-01

    Based on the measurement of the stem sap flow of Acacia mangium with Granier' s thermal dissipation probe, and the cross-correlation and time serial analysis of the sap flow and corresponding photosynthetically active radiation and vapor pressure deficit, this paper studied the time lag effect between the stem sap flow of A. mangium and the driving factors of the tree canopy transpiration. The results indicated that the main driving factors of the transpiration were photosynthetically active radiation (PAR) and vapor pressure deficit (VPD). Sap flux density (Js) was more dependent on PAR than on VPD, and the dependence was more significant in dry season than in wet season. Sap flow lagged behind PAR but advanced than VPD in both dry and wet seasons. The time lag did not show any significant variation across different size tree individuals, but showed significant variation in different seasons. Time lag effect was not correlated with tree height, diameter at the breast, and canopy size. The time lag between Js and VPD was significantly related to nighttime water recharge in dry season, but reversed in wet season. PMID:18464623

  4. Chemical vapor deposition of hexagonal boron nitride films in the reduced pressure

    SciTech Connect

    Choi, B.J.

    1999-12-01

    Hexagonal boron nitride (h-BN) films were deposited onto a graphite substrate in reduced pressure by reacting ammonia and boron tribromide at 800--1,200 C. The growth rate of h-BN films was dependent on the substrate temperature and the total pressures. The growth rate increased with increasing the substrate temperature at the pressure of 2 kPa, while it showed a maximum value at the pressures of 4 and 8 kPa. The temperature at which the maximum growth rate occurs decreased with increasing total pressure. With increasing the substrate temperature and total pressure, the apparent grain size increased and the surface morphology showed a rough, cauliflower-like structure.

  5. Phosphorus Test

    MedlinePlus

    ... be limited. Home Visit Global Sites Search Help? Phosphorus Share this page: Was this page helpful? Also ... else I should know? How is it used? Phosphorus tests are most often ordered along with other ...

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

    NASA Technical Reports Server (NTRS)

    Rutherford, J. A.; Vroom, D. A.

    1978-01-01

    In order to form metal vapors for neutral beam studies, an electron-beam heater and a power supply have been designed. The source, which measures about 30 x 50 x 70 mm, consists of a filament, accelerating plate (defined by pole pieces), and a supported target. The electrons from the filament are focused by the field penetration through a 2 mm slit in the high-voltage cage. They are then accelerated to about 5 kV to a ground plate. The electrons then follow a path in the magnetic field and strike the sample to be heated on its front surface. The assembly is attached to a water-cooled base plate. The electron beam source has produced beams of Ta and C particles with densities of about 10 to the 8th power/cu cm.

  12. 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

  13. Protective arrangement for a plug-connected electric motor sealed against pressure, vapors and radiation

    SciTech Connect

    Heuer, D.; Schmiedke, G.

    1984-05-29

    An electric motor construction comprises a housing with a motor rotor rotatably mounted in the housing with stator windings disposed in the housing around the rotor. The housing has a wall with an opening therein and a terminal box plug connector for the stator windings is mounted on the wall around the opening and includes an upper and a lower interengageable connector parts. A sealing gasket disposed between the parts which may be plug interconnected and held into position by a snap action lock. The stator windings have lead wires leading from the housing into the connector part and a continuous sealing compound resistant to humidity, vapors and gamma radiation embeds the stator windings and the lead wires and extends from the housing into the connector parts.

  14. 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 Hα and Hβ 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.

  15. Linking Turgor with ABA Biosynthesis: Implications for Stomatal Responses to Vapor Pressure Deficit across Land Plants1[OPEN

    PubMed Central

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

    2016-01-01

    Stomatal responses to changes in vapor pressure deficit (VPD) constitute the predominant form of daytime gas-exchange regulation in plants. Stomatal closure in response to increased VPD is driven by the rapid up-regulation of foliar abscisic acid (ABA) biosynthesis and ABA levels in angiosperms; however, very little is known about the physiological trigger for this increase in ABA biosynthesis at increased VPD. Using a novel method of modifying leaf cell turgor by the application of external pressures, we test whether changes in turgor pressure can trigger increases in foliar ABA levels over 20 min, a period of time most relevant to the stomatal response to VPD. We found in angiosperm species that the biosynthesis of ABA was triggered by reductions in leaf turgor, and in two species tested, that a higher sensitivity of ABA synthesis to leaf turgor corresponded with a higher stomatal sensitivity to VPD. In contrast, representative species from nonflowering plant lineages did not show a rapid turgor-triggered increase in foliar ABA levels, which is consistent with previous studies demonstrating passive stomatal responses to changes in VPD in these lineages. Our method provides a new tool for characterizing the response of stomata to water availability. PMID:27208264

  16. Interaction between phosphorus removal and hybrid granular sludge formation under low hydraulic selection pressure at alternating anaerobic/aerobic conditions.

    PubMed

    Lang, Longqi; Wan, Junfeng; Zhang, Jing; Wang, Jie; Wang, Yan

    2015-01-01

    The hybrid granular sludge (HGS) formation and its performances on phosphorus removal were investigated in a sequencing batch airlift reactor. Under conditions of low superficial air velocity (SAV = 0.68 cm s(-1)) and relatively long settling time (15-30 min), aerobic granules appeared and coexisted with bio-flocs after 120 days operation. At the stable phase, 54% of total suspended solid (m/m) was granular sludge with the two typical sizes (D(mean) = 1.77 ± 0.33 and 0.89 ± 0.11 mm) in the reactor, where the settling velocity was 98.7 ± 12.4 and 37.8 ± 0.9 m h(-1) for the big and small granules. With progressive extension of anaerobic time from 15 to 60 min before aerobic condition per cycle during the whole experiment, the HGS system can be maintained at a high total phosphorus removal efficiency (ca. 99%) since Day-270. The phosphorus content (wt %) in biomass was respectively 9.54 ± 0.29, 7.60 ± 0.48 and 6.15 ± 0.59 for the big granules, small granules and flocs. PMID:25921951

  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. 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.

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

    SciTech Connect

    Rocha, Marisa A. A. E-mail: marisa.alexandra.rocha@gmail.com; Coutinho, João A. P.; Santos, Luís M. N. B. F. E-mail: marisa.alexandra.rocha@gmail.com

    2014-10-07

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [C{sub N-1}C{sub 1}im][NTf{sub 2}]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C{sub 6}C{sub 6}im][NTf{sub 2}], was detected. An intensification of the odd-even effect was observed starting from [C{sub 6}C{sub 6}im][NTf{sub 2}], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C{sub 7}C{sub 7}im][NTf{sub 2}] and [C{sub 9}C{sub 9}im][NTf{sub 2}]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C{sub 6}C{sub 1}and C{sub 6}C{sub 6}) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

  20. Persistent Water-Nitric Acid Condensate with Saturation Water Vapor Pressure Greater than That of Hexagonal Ice.

    PubMed

    Gao, Ru-Shan; Gierczak, Tomasz; Thornberry, Troy D; Rollins, Andrew W; Burkholder, James B; Telg, Hagen; Voigt, Christiane; Peter, Thomas; Fahey, David W

    2016-03-10

    A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3 from the airstream following the formation of an initial condensate on the mirror that resembled nitric acid trihydrate (NAT). Typical conditions for the formation of the persistent condensate were a H2O mixing ratio greater than 18 ppm, pressure of 128 hPa, and mirror temperature between 202 and 216 K. In steady-state operation, a CMH maintains a condensate of constant optical diffusivity on a mirror through control of only the mirror temperature. Maintaining the persistent condensate on the mirror required that the mirror temperature be below the H2O saturation temperature with respect to Ih by as much as 3 K, corresponding to up to 63% H2O supersaturation with respect to Ih. The condensate was observed to persist in steady state for up to 16 h. Compositional analysis of the condensate confirmed the co-condensation of H2O and HNO3 and thereby strongly supports the conclusion that the Ih supersaturation is due to residual HNO3 in the condensate. Although the exact structure or stoichiometry of the condensate could not be determined, other known stable phases of HNO3 and H2O are excluded as possible condensates. This persistent condensate, if it also forms in the upper tropical troposphere, might explain some of the high Ih supersaturations in cirrus and contrails that have been reported in the tropical tropopause region. PMID:26447682

  1. 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

  2. High pressure-assisted transfer of ultraclean chemical vapor deposited graphene

    NASA Astrophysics Data System (ADS)

    Chen, Zhiying; Ge, Xiaoming; Zhang, Haoran; Zhang, Yanhui; Sui, Yanping; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

    2016-03-01

    We develop a high pressure-assisted (approximately 1000 kPa) transfer method to remove polymer residues and effectively reduce damages on the surface of graphene. By introducing an ethanol pre-dehydration technique and optimizing temperature, the graphene surface becomes nearly free of residues, and the quality of graphene is improved obviously when temperature reaches 140 °C. The graphene obtained using the high pressure-assisted transfer method also exhibits excellent electrical properties with an average sheet resistance of approximately 290 Ω/sq and a mobility of 1210 cm2/V.s at room temperature. Sheet resistance and mobility are considerably improved compared with those of the graphene obtained using the normal wet transfer method (average sheet resistance of approximately 510 ohm/sq and mobility of 750 cm2/V.s).

  3. Atmospheric pressure plasma chemical vapor deposition reactor for 100 mm wafers, optimized for minimum contamination at low gas flow rates

    NASA Astrophysics Data System (ADS)

    Anand, Venu; Nair, Aswathi R.; Shivashankar, S. A.; Mohan Rao, G.

    2015-08-01

    Gas discharge plasmas used for thinfilm deposition by plasma-enhanced chemical vapor deposition (PECVD) must be devoid of contaminants, like dust or active species which disturb the intended chemical reaction. In atmospheric pressure plasma systems employing an inert gas, the main source of such contamination is the residual air inside the system. To enable the construction of an atmospheric pressure plasma (APP) system with minimal contamination, we have carried out fluid dynamic simulation of the APP chamber into which an inert gas is injected at different mass flow rates. On the basis of the simulation results, we have designed and built a simple, scaled APP system, which is capable of holding a 100 mm substrate wafer, so that the presence of air (contamination) in the APP chamber is minimized with as low a flow rate of argon as possible. This is examined systematically by examining optical emission from the plasma as a function of inert gas flow rate. It is found that optical emission from the plasma shows the presence of atmospheric air, if the inlet argon flow rate is lowered below 300 sccm. That there is minimal contamination of the APP reactor built here, was verified by conducting an atmospheric pressure PECVD process under acetylene flow, combined with argon flow at 100 sccm and 500 sccm. The deposition of a polymer coating is confirmed by infrared spectroscopy. X-ray photoelectron spectroscopy shows that the polymer coating contains only 5% of oxygen, which is comparable to the oxygen content in polymer deposits obtained in low-pressure PECVD systems.

  4. 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

  5. Phosphorus removal using nanofiltration membranes.

    PubMed

    Leo, C P; Chai, W K; Mohammad, A W; Qi, Y; Hoedley, A F A; Chai, S P

    2011-01-01

    A high concentration of phosphorus in wastewater may lead to excessive algae growth and deoxygenation of the water. In this work, nanofiltration (NF) of phosphorus-rich solutions is studied in order to investigate its potential in removing and recycling phosphorus. Wastewater samples from a pulp and paper plant were first analyzed. Commercial membranes (DK5, MPF34, NF90, NF270, NF200) were characterized and tested in permeability and phosphorus removal experiments. NF90 membranes offer the highest rejection of phosphorus; a rejection of more than 70% phosphorus was achieved for a feed containing 2.5 g/L of phosphorus at a pH <2. Additionally, NF90, NF200 and NF270 membranes show higher permeability than DK5 and MPF34 membranes. The separation performance of NF90 is slightly affected by phosphorus concentration and pressure, which may be due to concentration polarization and fouling. By adjusting the pH to 2 or adding sulfuric acid, the separation performance of NF90 was improved in removing phosphorus. However, the presence of acetic acid significantly impairs the rejection of phosphorus. PMID:22053475

  6. Long Term Measurement of the Vapor Pressure of Gold in the Au-C System

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.

    2009-01-01

    Incorporating the {Au(s,l) + graphite} reference in component activity measurements made with the multiple effusion-cell vapor source mass spectrometry (multicell KEMS) technique provides a fixed temperature defining ITS-90 (T(sub mp)(Au) = 1337.33K) and a systematic method to check accuracy. Over a 2 year period delta H sub(298)Au was determined by the 2nd and 3rd law methods in 25 separate experiments and were in the ranges 362.2 plus or minus 3.3 kJmol(sup -1) and 367.8 plus or minus 1.1 kJmol(sup -1), respectively. This 5 kJmol-1 discrepancy is transferred directly to the measured activities. This is unacceptable and the source of this discrepancy needs to be understood and corrected. Accepting the 2nd law value increases p(Au) by about 50 percent, brings the 2nd and 3rd law values into agreement and removes the T dependence in the 3rd law values. While compelling, there is no way to independently determine instrument sensitivities, S(sub Au), with T in a single experiment with KEMS. This lack of capability is stopping a deeper understanding of this problem. In addition, the Au-C phase diagram suggests a eutectic invariant reaction: L-Au(4.7at%C) = FCC-Au(0.08at%C) + C(graphite) at T(sub e) approximately 1323K. This high C concentration in Au(l) must reduce p(Au) in equilibrium with {Au(s,l) + graphite} and raises some critical questions about the Gibbs free energy functions of Au(s,l) and the Au fixed point (T(sub mp)(Au) = 1337.33K) which is always measured in graphite.

  7. Novel solid-phase epitaxy for multi-component materials with extremely high vapor pressure elements: An application to KFe2As2

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Taisuke; Sato, Hikaru; Hiramatsu, Hidenori; Kamiya, Toshio; Hosono, Hideo

    2016-05-01

    We propose a novel solid-phase epitaxy technique applicable to high annealing temperatures up to 1000 °C without re-vaporization of alkali metal elements with high vapor pressures. This technique is demonstrated through the successful growth of high-quality KFe2As2 epitaxial films. The key factors are employing a custom-designed alumina vessel/cover and sealing it in a stainless tube with a large amount of atmospheric KFe2As2 powder in tightly closed sample spaces. This technique can also be effective for other materials composed of elements with very high vapor pressures, such as alkali metals, and can lead to the realization of spintronics devices in the future using KFe2As2.

  8. Enhanced Optical Properties of Chemical Vapor Deposited Single Crystal Diamond by Low-Pressure/High-Temperature Annealing

    SciTech Connect

    Meng, Y.; Yan, C; Lai, Y; Krasnicki, S; Shu, H; Yu, T; Liang, Q; Mao, H; Hemley, R

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Jacobsen, Richard T.; Stewart, Richard B.

    1973-01-01

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

  10. Identifying Liquid-Gas System Misconceptions and Addressing Them Using a Laboratory Exercise on Pressure-Temperature Diagrams of a Mixed Gas Involving Liquid-Vapor Equilibrium

    ERIC Educational Resources Information Center

    Yoshikawa, Masahiro; Koga, Nobuyoshi

    2016-01-01

    This study focuses on students' understandings of a liquid-gas system with liquid-vapor equilibrium in a closed system using a pressure-temperature ("P-T") diagram. By administrating three assessment questions concerning the "P-T" diagrams of liquid-gas systems to students at the beginning of undergraduate general chemistry…

  11. The gas phase emitter effect of lanthanum within ceramic metal halide lamps and its dependence on the La vapor pressure and operating frequency

    SciTech Connect

    Ruhrmann, C.; Hoebing, T.; Bergner, A.; Groeger, S.; Awakowicz, P.; Mentel, J.; Denissen, C.; Suijker, J.

    2015-08-07

    The gas phase emitter effect increases the lamp lifetime by lowering the work function and, with it, the temperature of the tungsten electrodes of metal halide lamps especially for lamps in ceramic vessels due to their high rare earth pressures. It is generated by a monolayer on the electrode surface of electropositive atoms of certain emitter elements, which are inserted into the lamp bulb by metal iodide salts. They are vaporized, dissociated, ionized, and deposited by an emitter ion current onto the electrode surface within the cathodic phase of lamp operation with a switched-dc or ac-current. The gas phase emitter effect of La and the influence of Na on the emitter effect of La are studied by spatially and phase-resolved pyrometric measurements of the electrode tip temperature, La atom, and ion densities by optical emission spectroscopy as well as optical broadband absorption spectroscopy and arc attachment images by short time photography. An addition of Na to the lamp filling increases the La vapor pressure within the lamp considerably, resulting in an improved gas phase emitter effect of La. Furthermore, the La vapor pressure is raised by a heating of the cold spot. In this way, conditions depending on the La vapor pressure and operating frequency are identified, at which the temperature of the electrodes becomes a minimum.

  12. The gas phase emitter effect of lanthanum within ceramic metal halide lamps and its dependence on the La vapor pressure and operating frequency

    NASA Astrophysics Data System (ADS)

    Ruhrmann, C.; Hoebing, T.; Bergner, A.; Groeger, S.; Denissen, C.; Suijker, J.; Awakowicz, P.; Mentel, J.

    2015-08-01

    The gas phase emitter effect increases the lamp lifetime by lowering the work function and, with it, the temperature of the tungsten electrodes of metal halide lamps especially for lamps in ceramic vessels due to their high rare earth pressures. It is generated by a monolayer on the electrode surface of electropositive atoms of certain emitter elements, which are inserted into the lamp bulb by metal iodide salts. They are vaporized, dissociated, ionized, and deposited by an emitter ion current onto the electrode surface within the cathodic phase of lamp operation with a switched-dc or ac-current. The gas phase emitter effect of La and the influence of Na on the emitter effect of La are studied by spatially and phase-resolved pyrometric measurements of the electrode tip temperature, La atom, and ion densities by optical emission spectroscopy as well as optical broadband absorption spectroscopy and arc attachment images by short time photography. An addition of Na to the lamp filling increases the La vapor pressure within the lamp considerably, resulting in an improved gas phase emitter effect of La. Furthermore, the La vapor pressure is raised by a heating of the cold spot. In this way, conditions depending on the La vapor pressure and operating frequency are identified, at which the temperature of the electrodes becomes a minimum.

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

    EPA Science Inventory

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

  14. 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...

  15. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test requirements. 84.163 Section 84.163 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL...

  16. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test requirements. 84.163 Section 84.163 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL...

  17. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test requirements. 84.163 Section 84.163 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL...

  18. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test requirements. 84.163 Section 84.163 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL...

  19. 42 CFR 84.163 - Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Man test for gases and vapors; Type C supplied-air respirators, demand and pressure-demand classes; test requirements. 84.163 Section 84.163 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL...

  20. Ultrafine aerosol size distributions and sulfuric acid vapor pressures: Implications for new particle formation in the atmosphere. Year 2 progress report

    SciTech Connect

    McMurry, P.H.

    1993-07-01

    This project has two components: (1) measurement of H{sub 2}SO{sub 4} vapor pressures in air under temperature/relative humidity conditions similar to atmospheric, and (2) measurement of ultrafine aerosol size distributions. During Year 2, more effort was put on size distribution measurements. 4 figs.

  1. Boiling liquid expanding vapor explosion: experimental research in the evolution of the two-phase flow and over-pressure.

    PubMed

    Chen, Sining; Sun, Jinhua; Wan, Wei

    2008-08-15

    In a boiling liquid expanding vapor explosion (BLEVE), the superheating and boiling of the liquefied gas inside the vessel as it fails is important information necessary to understand the mechanism of this type of disaster. In this paper, a small-scale experiment was developed to investigate the possible processes that could lead to a BLEVE. Water was used as the test fluid. High-speed video was utilized to observe the two-phase flow swelling which occurred immediately following the partial loss of containment through a simulated crack. The velocity of the two-phase swelling was measured along with pressure and temperature. It was observed that initially a mist-like two-phase layer was rapidly formed on the liquid surface (~3-4 ms) after the vessel opened. The superheated liquid rapidly boiled and this accelerated upwards the two-phase layer, the whole liquid boiled after about 17 ms form opening. It was supposed that the swelling of the two-phase layer was the possible reason for the first over-pressure measured at the top and bottom of the vessel. From 38 ms to 168 ms, the boiling of the superheated liquid weakened. And from 170 ms, the original drop/mist-like two-phase flow turned into a churn-turbulent bubbly two-phase flow, rose quickly in the field of the camera and eventually impacted the vessel top wall. The force of its impact and "cavitation" and "choke" following with the two-phase ejection were maybe main reasons for the second obvious pressure increasing. PMID:18261848

  2. Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Ouazzani, Jalil; Rosenberger, Franz

    1990-01-01

    A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

  3. Effect of water vapor on sound absorption in nitrogen at low frequency/pressure ratios

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Griffin, W. A.

    1981-01-01

    Sound absorption measurements were made in N2-H2O binary mixtures at 297 K over the frequency/pressure range f/P of 0.1-2500 Hz/atm to investigate the vibrational relaxation peak of N2 and its location on f/P axis as a function of humidity. At low humidities the best fit to a linear relationship between the f/P(max) and humidity yields an intercept of 0.013 Hz/atm and a slope of 20,000 Hz/atm-mole fraction. The reaction rate constants derived from this model are lower than those obtained from the extrapolation of previous high-temperature data.

  4. Calibrated vapor generator source

    DOEpatents

    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.

  5. Calibrated vapor generator source

    DOEpatents

    Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

    1995-01-01

    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.

  6. Characterization and sonochemical synthesis of black phosphorus from red phosphorus

    NASA Astrophysics Data System (ADS)

    Aldave, Sandra H.; Yogeesh, Maruthi N.; Zhu, Weinan; Kim, Joonseok; Sonde, Sushant S.; Nayak, Avinash P.; Akinwande, Deji

    2016-03-01

    Phosphorene is a new two-dimensional material which is commonly prepared by exfoliation from black phosphorus bulk crystals that historically have been synthesized from white phosphorus under high-pressure conditions. The few layers of phosphorene have a direct band gap in the range of 0.3-2 eV and high mobility at room temperature comparable to epitaxial graphene. These characteristics can be used for the design of high speed digital circuits, radio frequency circuits, flexible and printed systems, and optoelectronic devices. In this work, we synthesized black phosphorus from red phosphorus, which is a safer solid precursor, using sonochemistry. Furthermore, via a variety of microscopy and spectroscopy techniques, we report characterization results of the sonochemically synthesized black phosphorus in addition to the commercial black phosphorus. Finally, we describe the air stability of black phosphors and the crystalline structure of the synthesized material. This is the first result of sonochemical or solution-based synthesis of black phosphorus based on readily available low-cost red phosphorus. This solution-based synthesis of black phosphorus is suitable for printable applications of nanomaterial.

  7. Some properties of low-vapor-pressure braze alloys for thermionic converters

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1978-01-01

    Density, dc electrical resistivity, thermal conductivity, and linear thermal expansion are measured for arc-melted rod-shaped samples of binary eutectics of Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W selected as very-low-pressure braze fillers for thermionic converters. The first two properties are measured at 296 K for Zr-21.7 at% Ru, Zr-13 wt% W, Zr-19 wt% W, Zr-22.3 at% Nb, Nb-66.9 at% Ru, Hf-25.3 wt% Re, Zr-25.7 at% Ta, Hf-22.5 at% W, and Nb-35 wt% Mo. The last property is measured from 293 K to 2/3 melting point for specified alloys of different compositions. Resistivities of 0.000055 to 0.000181 ohm-cm are observed with the alloys having resistivities about ten times that of the less resistive constituent metal and about three times that of the more resistive constituent metal, except for Zr-19 wt% W and Nb-35 wt% Mo (greater resistivities). Thermal expansion coefficients vary from 0.000006 to 0.0000105/K. All brazes exhibit linear thermal expansion near that of their constituent metals.

  8. Microstructure characteristics of ZrO2 coating produced by atmospheric pressure chemical vapor deposition.

    PubMed

    Sun, Wei; Xiong, Xiang; Li, Xiaobin

    2011-09-01

    To settle the problem of low growth rate when prepare ZrO2 thermal barrier coating by Metalorganic CVD (MOCVD), a simple method was employed-atmospheric pressure CVD (APCVD). The paper firstly thermodynamic calculated the effect of O/Zr ratio and temperature on phase formation at various H/C ratios for ZrCl4-CO2-H2-Ar system. With temperature increment, the solid phase changes from C+ monoclinic ZrO2 to Monoclinic ZrO2 then to tetragonal ZrO2. With the increase of H/C ratio, the phase zone of C+ monoclinic ZrO2 expands. XRD and Raman spectrum were employed to measure phase structure of ZrO2 coating at different temperature. At 1300 degrees C, the coating contains a small amount tetragonal ZrO2 phase besides monoclinic phase; at 1100 degrees C, the coating is composed of monoclinic ZrO2 phase and a little C. The surface SEM images show the small grains evolve to polycrystals which have clear crystal form when raising temperature. The cross-section images show that dense ZrO2 column crystals arrange normal to the substrate. PMID:22097578

  9. 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.

  10. Synthesis and modeling of uniform complex metal oxides by close-proximity atmospheric pressure chemical vapor deposition.

    PubMed

    Hoye, Robert L Z; Muñoz-Rojas, David; Musselman, Kevin P; Vaynzof, Yana; MacManus-Driscoll, Judith L

    2015-05-27

    A close-proximity atmospheric pressure chemical vapor deposition (AP-CVD) reactor is developed for synthesizing high quality multicomponent metal oxides for electronics. This combines the advantages of a mechanically controllable substrate-manifold spacing and vertical gas flows. As a result, our AP-CVD reactor can rapidly grow uniform crystalline films on a variety of substrate types at low temperatures without requiring plasma enhancements or low pressures. To demonstrate this, we take the zinc magnesium oxide (Zn(1-x)Mg(x)O) system as an example. By introducing the precursor gases vertically and uniformly to the substrate across the gas manifold, we show that films can be produced with only 3% variation in thickness over a 375 mm(2) deposition area. These thicknesses are significantly more uniform than for films from previous AP-CVD reactors. Our films are also compact, pinhole-free, and have a thickness that is linearly controllable by the number of oscillations of the substrate beneath the gas manifold. Using photoluminescence and X-ray diffraction measurements, we show that for Mg contents below 46 at. %, single phase Zn(1-x)Mg(x)O was produced. To further optimize the growth conditions, we developed a model relating the composition of a ternary oxide with the bubbling rates through the metal precursors. We fitted this model to the X-ray photoelectron spectroscopy measured compositions with an error of Δx = 0.0005. This model showed that the incorporation of Mg into ZnO can be maximized by using the maximum bubbling rate through the Mg precursor for each bubbling rate ratio. When applied to poly(3-hexylthiophene-2,5-diyl) hybrid solar cells, our films yielded an open-circuit voltage increase of over 100% by controlling the Mg content. Such films were deposited in short times (under 2 min over 4 cm(2)). PMID:25939729

  11. Influence of deposition conditions on mechanical properties of low-pressure chemical vapor deposited low-stress silicon nitride films

    NASA Astrophysics Data System (ADS)

    Toivola, Yvete; Thurn, Jeremy; Cook, Robert F.; Cibuzar, Greg; Roberts, Kevin

    2003-11-01

    The effect of deposition temperature, deposition pressure, or input gas ratio (SiH2Cl2:NH3) on film stress was determined for low-pressure chemical vapor deposited silicon nitride films. Wafer curvature measurements were performed for films deposited on single crystal silicon and amorphous silica wafer substrates to determine film stress σdep, biaxial modulus Ef+, and coefficient of thermal expansion αf. Apparent plane strain film modulus Ēf' and hardness H were measured using depth-sensing indentation. Ellipsometry was used to measure film thickness tf and refractive index n. Infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), forward recoil energy spectroscopy (FReS), and Rutherford backscattering spectroscopy (RBS) experiments were performed to determine film composition. Although film deposition stress varied from -135 MPa (compressive) to 235 MPa (tensile) Ef+, Ēf', H, and αf remained nearly constant. Infrared spectroscopy resolved only Si-N species for all films, and results from FReS on three films confirmed that the hydrogen content was negligible. RBS and XPS indicated that Si/N increased with increased compressive σdep. Ellipsometry and RBS indicated that all films were silicon-rich, to a greater extent with increased compressive σdep. As RBS indicated that atomic density decreased with increased compressive deposition stress, it was concluded that the deposition conditions changed both thermal and intrinsic deposition stress for all films. In particular, intrinsic stress was tensile, and became increasingly tensile for increased Si/N and decreased atomic density. Assuming thermal stress was similar for all films examined here, the intrinsic stress must have varied from changes dependent on the deposition conditions.

  12. Thermodynamics of hydrogen bonding of weak bases in alcohol solutions: Calorimetry of solution, IR-spectroscopy and vapor pressure analysis

    NASA Astrophysics Data System (ADS)

    Zaitseva, Ksenia V.; Varfolomeev, Mikhail A.; Solomonov, Boris N.

    2012-06-01

    The properties of solutes and their reactivity in aliphatic alcohols significantly depend on the formation of hydrogen bonds. In this work, calorimetric, FTIR-spectroscopic and gas chromatographic vapor pressure studies of hydrogen bonds of weak bases in solution of aliphatic alcohols were carried out. Enthalpies of solutions at infinite dilution of ketones, nitriles and acetates in methanol and octan-1-ol were measured. Obtained from the calorimetric data, the enthalpies of specific interaction of weak bases in aliphatic alcohols unexpectedly found to be positive. IR spectra of solutions of ketones in aliphatic alcohols at infinite dilution were measured at different temperatures. Enthalpies of specific interaction in studied systems obtained from the spectroscopic data confirmed the endothermic process and are in good agreement with calorimetric results. Gibbs energies and entropies of specific interaction of weak bases in aliphatic alcohols were determined. Obtained results show, that the hydrogen bonding process of weak bases in aliphatic alcohols differs substantially from the formation of complexes 1:1 ROH⋯B (B - weak proton acceptor) in aprotic media. The complicated process of hydrogen bonding of weak bases in aliphatic alcohols apparently is controlled by the entropy factor, because these values are above zero.

  13. In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Okumura, Akihiko; Takada, Yasuaki; Watanabe, Susumu; Hashimoto, Hiroaki; Ezawa, Naoya; Seto, Yasuo; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Kondo, Tomohide; Nagashima, Hisayuki; Nagoya, Tomoki

    2016-07-01

    We propose detecting a fragment ion (Ph2As+) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH+) of DA, DC, DPAH, and BDPAO could produce Ph2As+ through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As+ signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH+ signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As+.

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

    NASA Astrophysics Data System (ADS)

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

    1993-03-01

    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 in these structures (1.2 eV) is presumed to be due to lowering of the barrier by excess silicon microclusters. Oxygen-annealed LPCVD SiO2 MOS structures exhibit oxide fixed charge and interface state densities in the mid-1010 cm-2 and mid-1010 cm-2 eV-1, respectively. Both the as-deposited and annealed devices exhibit turnaround in flatband voltage shift with avalanche electron injection. However, the direction of shift is opposite for the two devices with the annealed device being very similar to that of thermally grown SiO2 MOS structures. Apparently, oxygen annealing restructures and oxidizes the partial SiOx in the as-deposited LPCVD oxide into stochiometric SiO2. However, the residual nonstochiometric SiO2 microclusters in the bulk result in an electron barrier height of only 2.3 eV.

  16. In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry.

    PubMed

    Okumura, Akihiko; Takada, Yasuaki; Watanabe, Susumu; Hashimoto, Hiroaki; Ezawa, Naoya; Seto, Yasuo; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Kondo, Tomohide; Nagashima, Hisayuki; Nagoya, Tomoki

    2016-07-01

    We propose detecting a fragment ion (Ph2As(+)) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH(+)) of DA, DC, DPAH, and BDPAO could produce Ph2As(+) through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As(+) signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH(+) signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As(+). Graphical Abstract ᅟ. PMID:27098411

  17. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  18. In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Okumura, Akihiko; Takada, Yasuaki; Watanabe, Susumu; Hashimoto, Hiroaki; Ezawa, Naoya; Seto, Yasuo; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Kondo, Tomohide; Nagashima, Hisayuki; Nagoya, Tomoki

    2016-04-01

    We propose detecting a fragment ion (Ph2As+) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH+) of DA, DC, DPAH, and BDPAO could produce Ph2As+ through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As+ signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH+ signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As+.

  19. Homoepitaxial growth of β-Ga2O3 thin films by low pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Rafique, Subrina; Han, Lu; Tadjer, Marko J.; Freitas, Jaime A.; Mahadik, Nadeemullah A.; Zhao, Hongping

    2016-05-01

    This paper presents the homoepitaxial growth of phase pure (010) β-Ga2O3 thin films on (010) β-Ga2O3 substrate by low pressure chemical vapor deposition. The effects of growth temperature on the surface morphology and crystal quality of the thin films were systematically investigated. The thin films were synthesized using high purity metallic gallium (Ga) and oxygen (O2) as precursors for gallium and oxygen, respectively. The surface morphology and structural properties of the thin films were characterized by atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. Material characterization indicates the growth temperature played an important role in controlling both surface morphology and crystal quality of the β-Ga2O3 thin films. The smallest root-mean-square surface roughness of ˜7 nm was for thin films grown at a temperature of 950 °C, whereas the highest growth rate (˜1.3 μm/h) with a fixed oxygen flow rate was obtained for the epitaxial layers grown at 850 °C.

  20. 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).

  1. Investigation on growth behavior of CNTs synthesized by atmospheric pressure plasma enhanced chemical vapor deposition system on Fe catalyzed substrate.

    PubMed

    Choi, Bum Ho; Kim, Won Jae; Kim, Young Baek; Lee, Jong Ho; Park, Jong Woon; Kim, Woo Sam; Shin, Dong Chan

    2008-10-01

    We have studied growth behavior of carbon nanotubes (CNTs) on iron (Fe) catalyzed substrate using newly developed atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) system. To investigate the improved growth performance with simple equipment and process on large scale, a new AP-PECVD system containing different concept on downstream gas was designed and manufactured. As a catalyst, either sputtered or evaporated Fe thin film on SiO2/Si substrate was used and acetylene gas was used as a carbon source. We observed growth behavior of CNTs such as height, rate and density were strongly affected by plasma power. The maximum height of 427 microm and 267 microm was synthesized under RF plasma power of 30 W for 30 min and 40 W for 3 min, respectively. The growth rate dramatically increased to 6.27 times as plasma power increased from 30 to 40 W which opens the possibility the mass production of CNTs. By SEM and TEM observation, it was verified the grown CNTs was consists of mixture of single-wall and multi-wall CNTs. The graphitization ratio was measured to be 0.93, indicating that the graphitized CNTs forest was formed and relatively high purity of CNTs was synthesized, being useful for nano-composite materials to reinforce the strength. From our experiments, we can observe that the height and growth rate of CNTs is strong function of plasma power. PMID:19198378

  2. 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. HIP’d ZnS with superior transmission exhibits both a change in texture as well as a reduction in hexagonal content. Reduction in hexagonality, alone, was not sufficient to improve optical transmission from the visible to the infrared. For the first time, the effects of pressure, temperature, and the presence of platinum on recrystallization during commercial ZnS HIPing are separated and identified. Platinum was found to actively promote recrystallization and silver demonstrated a similar effect. Several theories focusing on the unique polytypic nature of ZnS are offered to explain the changes in structure and properties occurring during recrystallization, These findings contribute to a broader understanding of the nature of order-disorder and martensitic phase transformations in ceramic materials.

  3. Prediction of thermodynamic properties, including solubility equilibria and vapor pressures, for mixed aqueous electrolytes to high temperatures

    SciTech Connect

    Pabalan, R.T.; Pitzer, K.S.

    1988-01-01

    A number of different models have been proposed in the literature that treat the thermodynamic properties of electrolyte solutions. The most frequently used at present is the ion-interaction or virial coefficient approach, which was initially developed by Pitzer (1973) and Pitzer and Kim (1974) for aqueous solutions near room temperature. Since the model is based on a general equation for the excess Gibbs energy of the aqueous fluid, any thermodynamic property can be obtained from the appropriate derivatives. Thus the model has been used to describe osmotic and activity coefficients, as well as volumetric and thermal properties (e.g., heat capacity and enthalpy) of aqueous electrolytes. Success of this model when applied to complex and concentrated electrolyte mixtures was initially demonstrated for calculations of equilibria at room temperature between a brine phase and one or more solids by Harvie and Weare (1980). In this study we show that the same success holds over a wider range of temperature conditions. The model is applied to calculations of solubility equilibria, as well as to calculations of vapor pressures of electrolyte mixtures to high temperatures. 32 refs., 8 figs., 2 tabs.

  4. Vapor Pressures in the Al(I)+Al2O3(s) System: Reconsidering Al2O3(s) Condensation

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2005-01-01

    The vaporization behavior of the A1-O system has been studied on numerous occasions but significant uncertainties remain. The origin of this uncertainty must be understood before A1-O vaporization behavior can be accurately determined. The condensation of A12O3 and clogging of the effusion orifice is a difficult problem for the Knudsen effusion technique that influences the measured vaporization behavior but has only received limited attention. This study reconsiders this behavior in detail. A new theory for A12O3 condensation is proposed together with procedures that will improve the measured thermodynamic properties of A1-O vaporization.

  5. Oxygen partial pressure dependent electrical conductivity type conversion of phosphorus-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Lee, S.; Jeong, Y. E.; Lee, D.; Bae, J. S.; Lee, W. J.; Park, K. H.; Bu, S. D.; Park, S.

    2014-02-01

    In this study, the oxygen partial pressure dependent physical properties of phosphorous-doped ZnO thin films were investigated. All thin films, grown on Al2O3(0 0 0 1) substrates using pulsed laser deposition, exhibited (0 0 2) orientation regardless of the oxygen partial pressure. However, as the oxygen partial pressure increased, the degree of crystallinity and the concentration of oxygen vacancies in the films decreased. All the thin-film samples showed n-type characteristics except for a sample grown at 100 mTorr, which exhibited p-type characteristics. The optical band gap energy also changed with the oxygen partial pressure. The feasible microscopic mechanism of conductivity conversion is explained in terms of the lattice constant, crystallinity, and the relative roles of the substituted phosphorous in the Zn-site and/or oxygen vacancies depending on the oxygen partial pressure.

  6. Electrical and Material Characteristics of Low Pressure Chemical-Vapor Deposited Tungsten Films in Cold Wall Systems.

    NASA Astrophysics Data System (ADS)

    Joshi, Rajiv V.

    The kinetics and related mechanisms of non-self limiting nature of Si reduction of WF_6 in cold wall systems are investigated. The growth of such films in Low Pressure Chemical Vapor Deposition (LPCVD) and Ultra High Vacuum (UHV) systems is compared. Based on thermodynamic considerations, the origin of W-O layer is attributed to a secondary reaction between water vapors, WF_6 and substrate Si. The beneficial role played by the W-O layer is that it prevents the volume shrinkage and restricts lateral encroachment. A physical model is proposed which explains the non-self limiting growth of W films based on the microstructure of the film, the process parameters, the presence of W-O, and the Si gradient across the W films. The surface science study in the UHV system has helped in developing this model. It is postulated that the fine grained W structure surrounded by W-O layer formed in the LPCVD system assists in faster out-diffusion of Si through W films compared to an UHV system. This explains why the activation energy (0.2 eV) is lower for Si out-diffusion through films grown in the LPCVD system than that for the UHV system (0.48 eV). This, also, supports the significantly lower values of coefficient for Si out-diffusion in the case of LPCVD system. The out-diffused Si is substituted to W to complete the film growth. The effects of deposition temperature on growth, composition, structure, adhesion properties, stress and resistivity of tungsten films deposited purely by SiH _4 reduction of WF_6 are also reported. Silicon reduced W is characterized electrically by fabricating Schottky Barriers and FET (Field Effect Transistors). Increased diffusion of Si into W as a function of deposition temperature increases the barrier height from 0.60 eV to 0.64 eV. The contact resistances of Si reduced W surrounded by amorphous layer of W-O is very close to that for H_2 reduced W. Raised source and drain are formed on NFET and PFET by low temperature selective epitaxial Si, which

  7. Prediction of high-temperature thermodynamic properties of mixed electrolyte solutions including solubility equilibria, vapor pressure depression and boiling point elevation

    SciTech Connect

    Pabalan, R.T.; Pitzer, K.S.

    1988-01-01

    The Pitzer ion-interaction model, which is theoretically derived but uses empirical parameters evaluated from experimental data on binary and ternary aqueous mixtures, is shown to accurately predict thermodynamic properties of aqueous eletrolytes to high temperatures and concentrations and for more complex compositions. Applications of the model include calculations of solubility equilibria, vapor pressures and boiling points of electrolyte mixtures. Examples of these calculations are given below. 32 refs., 5 figs., 2 tabs.

  8. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  10. Vapor Pressure Deficit, Soil Moisture, and Stream Flow Relationships to Land-Atmosphere Fluxes of Water and Carbon.

    NASA Astrophysics Data System (ADS)

    Mitchell, S. R.; Emanuel, R. E.; McGlynn, B. L.

    2014-12-01

    Climatic change is exerting considerable influence on the hydrologic and biogeochemical cycles of snow- dominated montane forest ecosystems. Growing season drought stress is a common occurrence after snowmelt-derived soil water content (WC) and stream flow (Q) have declined, leading to an increase in atmospheric water demands (i.e. vapor pressure deficit, VPD). Here, we analyzed a 6-year record (2006-2011) of H2O and CO2 fluxes from the Tenderfoot Creek Experimental Forest, a montane forest in the northern Rocky Mountains to examine (1) how growing season evapotranspiration (ET), net ecosystem production of carbon (NEP), and water use efficiency (WUENEP/ET) respond to changing WC and VPD, (2) how annual NEP is influenced by annual precipitation and growing season length (GSL), and (3) the relationship of stream flow (Q), a catchment-wide indicator of water availability, to NEP and WUENEP/ET. Growing season NEP exhibited a linear relationship with WC and a log-linear relationship with Q, indicative of persistent water limitations when streamflow and soil moisture reach their annual minima late in the growing season. Nevertheless, years with long GSLs had relatively higher NEP, with a small net carbon sink maintained even at low levels of WC and Q, suggesting that trees are able to obtain water from deeper portions of the soil profile (>30 cm) during droughts. However, the warmer, drier climate projected for this region could bring this system closer to a critical threshold of GSL, WC, and VPD, introducing vegetation water stress that could alter the current relationship between GSL and annual NEP.

  11. 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

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

    SciTech Connect

    Dugrain, Vincent; Reichel, Jakob; Rosenbusch, Peter

    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.

  13. Investigation of NH3 input partial pressure for N-polarity InGaN growth on GaN substrates by tri-halide vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Hirasaki, Takahide; Hasegawa, Tomoyasu; Meguro, Misaki; Thieu, Quang Tu; Murakami, Hisashi; Kumagai, Yoshinao; Monemar, Bo; Koukitu, Akinori

    2016-05-01

    The influence of NH3 input partial pressure on N-polarity InGaN grown by tri-halide vapor phase epitaxy was investigated. It was found that surface morphology, solid composition and optical properties were affected by NH3 input partial pressure. As shown in thermodynamic analyses, the indium content increased due to an increase in the driving force for InN deposition caused by increased NH3 input partial pressure. In addition, the deep level emission around 2.1 eV in photoluminescence measurements drastically decreased at higher NH3 input partial pressures. Ab initio calculations and subsequent secondary ion mass spectrometry measurements suggested the reduction of metal-vacancies and/or carbon impurity incorporation in the InGaN layers.

  14. Ultra-Long Crystalline Red Phosphorus Nanowires from Amorphous Red Phosphorus Thin Films.

    PubMed

    Smith, Joshua B; Hagaman, Daniel; DiGuiseppi, David; Schweitzer-Stenner, Reinhard; Ji, Hai-Feng

    2016-09-19

    Heating red phosphorus in sealed ampoules in the presence of a Sn/SnI4 catalyst mixture has provided bulk black phosphorus at much lower pressures than those required for allotropic conversion by anvil cells. Herein we report the growth of ultra-long 1D red phosphorus nanowires (>1 mm) selectively onto a wafer substrate from red phosphorus powder and a thin film of red phosphorus in the present of a Sn/SnI4 catalyst. Raman spectra and X-ray diffraction characterization suggested the formation of crystalline red phosphorus nanowires. FET devices constructed with the red phosphorus nanowires displayed a typical I-V curve similar to that of black phosphorus and a similar mobility reaching 300 cm(2)  V(-1)  s with an Ion /Ioff ratio approaching 10(2) . A significant response to infrared light was observed from the FET device. PMID:27553637

  15. Vapor phase pyrolysis

    NASA Technical Reports Server (NTRS)

    Steurer, Wolfgang

    1992-01-01

    The vapor phase pyrolysis process is designed exclusively for the lunar production of oxygen. In this concept, granulated raw material (soil) that consists almost entirely of metal oxides is vaporized and the vapor is raised to a temperature where it dissociates into suboxides and free oxygen. Rapid cooling of the dissociated vapor to a discrete temperature causes condensation of the suboxides, while the oxygen remains essentially intact and can be collected downstream. The gas flow path and flow rate are maintained at an optimum level by control of the pressure differential between the vaporization region and the oxygen collection system with the aid of the environmental vacuum.

  16. Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition.

    PubMed

    Benjamin, Sophie L; de Groot, C H Kees; Gurnani, Chitra; Hector, Andrew L; Huang, Ruomeng; Ignatyev, Konstantin; Levason, William; Pearce, Stuart J; Thomas, Fiona; Reid, Gillian

    2013-12-10

    The neutral, distorted octahedral complex [TiCl4(Se (n) Bu2)2] (1), prepared from the reaction of TiCl4 with the neutral Se (n) Bu2 in a 1:2 ratio and characterized by IR and multinuclear ((1)H, (13)C{(1)H}, (77)Se{(1)H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3̅m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10(-3) Ω·cm with a carrier density of 1 × 10(22) cm(-3). Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 μm diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ∼20 μm hole size, whereas their lengths/widths continue to increase. PMID:24489437

  17. Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition

    PubMed Central

    2013-01-01

    The neutral, distorted octahedral complex [TiCl4(SenBu2)2] (1), prepared from the reaction of TiCl4 with the neutral SenBu2 in a 1:2 ratio and characterized by IR and multinuclear (1H, 13C{1H}, 77Se{1H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3̅m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10–3 Ω·cm with a carrier density of 1 × 1022 cm–3. Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 μm diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ∼20 μm hole size, whereas their lengths/widths continue to increase. PMID:24489437

  18. Finite-size thermomechanical effects in smectic liquid crystals: The vapor pressure paradox as an anharmonic phenomenon

    NASA Astrophysics Data System (ADS)

    Gao, Lianghui; Golubović, 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

  19. Vapor pressure measurements on non-aqueous electrolyte solutions. Part 2. Tetraalkylammonium salts in methanol. Activity coefficients of various 1-1 electrolytes at high concentrations

    SciTech Connect

    Barthel, J.; Lauermann, G.; Neueder, R.

    1986-10-01

    Precise vapor pressure data for solutions of Et/sub 4/NBr, Bu/sub 4/NBr, Bu/sub 4/Nl, Bu/sub 4/NClO/sub 4/, and Am/sub 4/NBr in methanol at 25/sup 0/C in the concentration range 0.04 < m(mol-(kg of solvent)/sup -1/) < 1.6 are communicated and discussed. Polynomials in molalities are given which may be used for calculating precise vapor pressure depressions of these solutions. Osmotic coefficients are calculated by taking into account the second virial coefficient of methanol vapor. Discussion of the data at low concentrations is based on the chemical model of electrolyte solutions taking into account non-coulombic interactions; ion-pair association constants are compared to those of conductance measurements. Pitzer equations are used to reproduce osmotic and activity coefficient at high concentrations; the set of Pitzer parameters b = 3.2, ..cap alpha../sub 1/ = 2.0 and ..cap alpha../sub 2/ = 20.0 is proposed for methanol solutions.

  20. Tested Demonstrations. Gasoline Vapor: An Invisible Pollutant

    ERIC Educational Resources Information Center

    Stephens, Edgar R.

    1977-01-01

    Describes a demonstration concerning the air pollution aspects of gasoline vapor which provides an estimation of the vapor pressure of test fuel, the molecular weight of the vapor, and illustrates a method of controlling the pollution. (SL)

  1. Cu2Te Synthesis and In-Vacuum Thermal Decomposition: Chemical-Kinetics Analysis and Comparison to Equilibrium Vapor-Pressure Measurements

    SciTech Connect

    Teeter, G.

    2007-01-01

    In this study, polycrystalline Cu-foil substrates are exposed to elemental Te vapor at substrate temperatures below 373 K. Auger electron spectroscopy measurements indicate that copper-telluride films are formed at the substrate surface that have a 2:1 Cu-to-Te ratio, as predicted by the Cu--Te phase diagram. When these films are annealed above about 700 K in vacuum, Te desorbs from the substrate with zero-order kinetics. An analysis of Te-desorption traces that assumes the reaction Cu{sub 2}Te(s) {yields} 2Cu(s) + {alpha}Te(?) + 1/2(1 - {alpha})Te2({nu}) finds a thermal-decomposition activation energy of 217 {+-} 3 kJ mol{sup -1}. These Te-desorption data are compared to the Te impingement rate calculated from Cu{sub 2}Te equilibrium vapor-pressure data from the literature and found to be in excellent agreement.

  2. Mass spectrometric determination of partial pressures of ions in the saturated vapor over the NaF-Na3AlF6 system

    NASA Astrophysics Data System (ADS)

    Abramov, S. V.; Chilingarov, N. S.; Borshchevsky, A. Ya; Sidorov, L. N.

    2004-01-01

    Mass spectrometric determination of absolute partial pressures of basic charged species Na2F+ and AlF4- in the saturated vapor over the NaF-Na3AlF6 system (1:1 molar ratio) was carried out in the 974-1090 K temperature range. The ion pressures were 5-8 orders of magnitude lower than the pressures of basic molecular components NaAlF4 and NaF. Particular attention was given to the equality of device sensitivity constants for positive and negative ions. Absolute device calibration was carried out using the measured ion currents Na2F+ and AlF4- and the equilibrium constant of heterolytic dissociation available in the literature.

  3. 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).

  4. 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).

  5. White phosphorus

    Integrated Risk Information System (IRIS)

    White phosphorus ; CASRN 7723 - 14 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  6. Numerical Simulation of Phosphorus Removal from Silicon by Induction Vacuum Refining

    NASA Astrophysics Data System (ADS)

    Zheng, Songsheng; Engh, Thorvald Abel; Tangstad, Merete; Luo, Xue-Tao

    2011-08-01

    Phosphorus can be expected to evaporate preferentially from silicon melt by induction vacuum refining (IVR). In the present study, on the assumption of phosphorus evaporating from silicon melt as gas species P and P 2, a numerical model of phosphorus removal from silicon by IVR was developed. The factors affecting phosphorus removal in decreasing order are temperature, chamber pressure, geometry of silicon melt, holding time, and original phosphorus concentration. Calculated phosphorus removal shows good agreement with the present experimental data.

  7. Low temperature carrier transport study of monolayer MoS{sub 2} field effect transistors prepared by chemical vapor deposition under an atmospheric pressure

    SciTech Connect

    Liu, Xinke E-mail: wujing026@gmail.com; He, Jiazhu; Tang, Dan; Lu, Youming; Zhu, Deliang; Liu, Wenjun; Cao, Peijiang; Han, Sun; Liu, Qiang; Wen, Jiao; Yu, Wenjie; Liu, Wenjun; Wu, Jing E-mail: wujing026@gmail.com; He, Zhubing; Ang, Kah-Wee

    2015-09-28

    Large size monolayer Molybdenum disulphide (MoS{sub 2}) was successfully grown by chemical vapor deposition method under an atmospheric pressure. The electrical transport properties of the fabricated back-gate monolayer MoS{sub 2} field effect transistors (FETs) were investigated under low temperatures; a peak field effect mobility of 59 cm{sup 2}V{sup −1}s{sup −1} was achieved. With the assist of Raman measurement under low temperature, this work identified the mobility limiting factor for the monolayer MoS{sub 2} FETs: homopolar phonon scattering under low temperature and electron-polar optical phonon scattering at room temperature.

  8. Progress of serpentinization in olivine-H2O system at 250 °C and vapor-saturated pressure

    NASA Astrophysics Data System (ADS)

    Okamoto, A.; Ogasawara, Y.; Tsuchiya, N.

    2011-12-01

    Fluids play a crucial role in global-scale mass transfer, metamorphism, volcanism, and seismic processes in subduction zones. Serpentine minerals, which are produced by interaction between ultramafic rocks and fluids, contain about 13% water and are the greatest carrier of H2O into the deep interior of Earth. Therefore, the volume and distribution of hydrated oceanic mantle are of special interest in evaluating the effects of fluids on subduction zone processes. We conducted hydrothermal experiments in olivine (Ol; Fo91)-H2O and orthopyroxenite (Opx; composed of 95% of orthopyroxene, En66)-H2O systems under conditions of 250 °C and vapor-saturated pressure (Psat) to examine the temporal evolution of the solution chemistry and products in runs of up to 1008 h in duration. The maximal degree of hydration (i.e., H2O content in the solid sample) in the Ol-H2O experiments (3.6 wt.%) was much higher than that in the Opx-H2O experiments (0.4 wt.%). In the Ol-H2O experiments, Mg and Si in solution showed an initial increase (stage 1) before decreasing (stage 2) and finally attaining a steady state after 504 h (stage 3). Following a drop in silica activity toward the level of brucite stability filed, the products also changed from serpentine + magnetite (stages 1 and 2) to serpentine + brucite + magnetite (stage 3). Serpentine minerals also changed from lizardite (stages 1 and 2) to lizardite + chrysotile (stage 3). The textures observed in this study were similar to those observed in partly serpentinized dunites. In the Opx-H2O experiments, chlorite formed after orthopyroxene grains, which differs from the formation of talc and serpentine after orthopyroxene (bastite), as observed in natural hydrated harzburgites. The Opx-H2O system maintained 10-103 times higher silica activity than Ol-H2O system, suggesting that brucite does not form after olivine during hydration of peridotites when the Ol-H2O system is linked to the Opx-H2O system. The progress of hydration reactions

  9. Measurements of octanol-air partition coefficients, vapor pressures and vaporization enthalpies of the (E) and (Z) isomers of the 2-ethylhexyl 4-methoxycinnamate as parameters of environmental impact assessment.

    PubMed

    Pegoraro, César N; Chiappero, Malisa S; Montejano, Hernán A

    2015-11-01

    2-Ethylhexyl 4-methoxycinnamate is one of the UVB blocking agents more widely used in a variety of industrial fields. There are more than one hundred industrial suppliers worldwide. Given the enormous annual consumption of octinoxate, problems that arise due to the accumulation of this compound in nature should be taken into consideration. The GC-RT was used in this work with the aim of determining the vapor pressure, enthalpies of vaporization and octanol-air partition coefficient, for the BBP, DOP, E- and Z-EHMC esters. The results showed that Z-EHMC is almost five times more volatile than E-EHMC. Moreover, BBP, Z-EHMC and E-EHMC can be classified as substances with a relatively low mobility since they lie within the range of 810 and log(PL/Pa)<-4, therefore, a low mobility can be expected. From these parameters, their particle-bound fraction and gas-particle partition coefficient were also derived. PMID:26210018

  10. High-quality graphene grown on polycrystalline PtRh20 alloy foils by low pressure chemical vapor deposition and its electrical transport properties

    NASA Astrophysics Data System (ADS)

    Yang, He; Shen, Chengmin; Tian, Yuan; Bao, Lihong; Chen, Peng; Yang, Rong; Yang, Tianzhong; Li, Junjie; Gu, Changzhi; Gao, Hong-Jun

    2016-02-01

    High-quality continuous uniform monolayer graphene was grown on polycrystalline PtRh20 alloy foils by low pressure chemical vapor deposition. The morphology of graphene was investigated by Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. Analysis results confirm that high quality single-layer graphene was fabricated on PtRh20 foil at 1050 °C using a lower flux of methane under low pressure. Graphene films were transferred onto the SiO2/Si substrate by the bubbling transfer method. The mobility of a test field effect transistor made of the graphene grown on PtRh20 was measured and reckoned at room temperature, showing that the carrier mobility was about 4000 cm2 V-1 s-1. The results indicate that desired quality of single-layer graphene grown on PtRh20 foils can be obtained by tuning reaction conditions.

  11. Density distributions of OH, Na, water vapor, and water mist in atmospheric-pressure dc helium glow plasmas in contact with NaCl solution

    NASA Astrophysics Data System (ADS)

    Sasaki, Koichi; Ishigame, Hiroaki; Nishiyama, Shusuke

    2015-07-01

    This paper reports the density distributions of OH, Na, water vapor and water mist in atmospheric-pressure dc helium glow plasmas in contact with NaCl solution. The densities of OH, Na and H2O had different spatial distributions, while the Na density had a similar distribution to mist, suggesting that mist is the source of Na in the gas phase. When the flow rate of helium toward the electrolyte surface was increased, the distributions of all the species densities concentrated in the neighboring region to the electrolyte surface more significantly. The densities of all the species were sensitive to the electric polarity of the power supply. In particular, we never detected Na and mist when the electrolyte worked as the anode of the dc discharge. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  12. 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

  13. Leaf aquaporin transcript abundance in peanut genotypes diverging in expression of the limited-transpiration trait when subjected to differing vapor pressure deficits and aquaporin inhibitors.

    PubMed

    Devi, M Jyostna; Sinclair, Thomas R; Jain, Mukesh; Gallo, Maria

    2016-04-01

    A plant trait currently being exploited to decrease crop yield loss under water-deficit conditions is limited-transpiration rate (TRlim ) under high atmospheric vapor pressure deficit (VPD) conditions. Although limited genotype comparisons for the TRlim trait have been performed in peanut (Arachis hypogaea), no detailed study to describe the basis for this trait in peanut has been reported. Since it has been hypothesized that the TRlim trait may be a result of low leaf hydraulic conductance associated with aquaporins (AQPs), the first objective of this study was to examine a possible correlation of TRlim to leaf AQP transcriptional profiles in six peanut cultivars. Five of the studied cultivars were selected because they expressed TRlim while the cultivar York did not. Transcripts of six AQPs were measured. Under exposure to high vapor pressure deficit, cultivar C 76-16 had decreased AQP transcript abundance for four of the six AQPs but in York only one AQP had decreased abundance. The second objective was to explore the influence of AQP inhibitors mercury and silver on expression of TRlim and AQP transcription profiles. Quantitative RT-PCR data were compared in cultivars York and C 76-16, which had the extreme response in TR to VPD. Inhibitor treatment resulted in increased abundance of AQP transcripts in both. The results of these experiments indicate that AQP transcript abundance itself may not be useful in identifying genotypes expressing the TRlim trait under high VPD conditions. PMID:26303261

  14. DESIGN MANUAL: PHOSPHORUS REMOVAL

    EPA Science Inventory

    This manual summarizes process design information for the best developed methods for removing phosphorus from wastewater. his manual discusses several proven phosphorus removal methods, including phosphorus removal obtainable through biological activity as well as chemical precip...

  15. 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 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

  16. Effects of total CH 4/Ar gas pressure on the structures and field electron emission properties of carbon nanomaterials grown by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Qi, J. L.; Wang, X.; Zheng, W. T.; Tian, H. W.; Liu, C.; Lu, Y. L.; Peng, Y. S.; Cheng, G.

    2009-12-01

    The effects of total CH 4/Ar gas pressure on the growth of carbon nanomaterials on Si (1 0 0) substrate covered with CoO nanoparticles, using plasma-enhanced chemical vapor deposition (PECVD), were investigated. The structures of obtained products were correlated with the total gas pressure and changed from pure carbon nanotubes (CNTs) through hybrid CNTs/graphene sheets (GSs), to pure GSs as the total gas pressure changed from 20 to 4 Torr. The total gas pressure influenced the density of hydrogen radicals and Ar ions in chamber, which in turn determined the degree of how CoO nanoparticles were deoxidized and ion bombardment energy that governed the final carbon nanomaterials. Moreover, the obtained hybrid CNTs/GSs exhibited a lower turn-on field (1.4 V/μm) emission, compared to either 2.7 V/μm for pure CNTs or 2.2 V/μm for pure GSs, at current density of 10 μA/cm 2.

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

    EPA Science Inventory

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

  18. 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.

  19. Pressure (Or No Royal Road)

    ERIC Educational Resources Information Center

    Bradley, J.

    1973-01-01

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

  20. Adsorption and Decomposition of Organometallics on GaAs Surfaces in Low-Pressure Metalorganic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Sato, Michio; Weyers, Markus

    1991-11-01

    To determine the mechanism of surface reactions during metalorganic chemical vapor deposition, we perform mass spectrometric studies of the products desorbed from a GaAs surface upon pulsed supply of the reactants. We find that the surface after trimethylgallium (TMG) exposure is terminated by CH3 and that the desorption of the CH3 from the surface is activated by the presence of As. The adsorption of triethylgallium (TEG) is inhibited on a CH3-terminated surface whereas TEG is decomposed both on As-rich and on Ga-rich surfaces. The effect of CH3 termination is highlighted by the complete inhibition of triethylaluminum decomposition when it is introduced together with TMG.