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Sample records for ambient pressure dried

  1. Ambient Dried Aerogels

    NASA Technical Reports Server (NTRS)

    Jones, Steven M.; Paik, Jong-Ah

    2013-01-01

    A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

  2. Synthesis of Silica Aerogel from Bagasse Ash by Ambient Pressure Drying

    NASA Astrophysics Data System (ADS)

    Setyawan, Nazriati Heru; Winardi, Sugeng

    2011-12-01

    Silica aerogels having very high surface area and pore volume have been succesfully synthesized from bagasse ash by ambient pressure drying (APD) method. Silica in bagasse ash was extracted by alkali extraction to produce sodium silicate solution. This is done by boiling bagasse ash in 2 N NaOH solution under continuous stirring for 1 h. To avoid the collapse of gel structure during drying at ambient pressure condition, the silica surface was modified with alkyl functional groups by a single step sol-gel process. Silicic acid produced by exchanging Na+ ions in dilute sodium silicate solution with H+ ions from cation resin was added with trimethylchlorosilane (TMCS) and let the reaction of TMCS with water pore proceeds for several minutes to produce hexamethyldisilazane (HMDS) and HCl. Then, HMDS was added to allow the modification of silica surface in which the silanol groups were exchanged with alkyl groups originating from HMDS. The solution pH was then adjusted to 8-9 by adding NH4OH solution to induce gel formation. The hydrogel was aged at 40 °C for 18 h and at 60 °C for 1 h. Then, it was dried at 80 °C at ambient pressure condition. The silica aerogels obtained have specific surface, as measured by BET method, ranging from 450.2 to 1360.4 m2/g depending on the synthesis condition. The pore volume was ranging from 0.7 to 1.9 cm3/g. It seems that silica aerogels with very high surface area and pore volume can be obtained if the silanols group in the silica surface was exchanged succesfully with alkyl groups from HMDS.

  3. Dry Kraft Pulping at Ambient Pressure for Cost Effective Energy Saving and Pollution Deduction

    SciTech Connect

    Yulin Deng; Art Ragauskas

    2012-08-28

    Sponsored by the DOE Industrial Energy Efficiency Grand Challenge program, our research team at the Georgia Institute of Technology conducted laboratory studies and confirmed the concept of making wood pulp using a dry pulping technology. This technology is a new process different from any prior pulping technology used in Kraft and CTMP pulping. Three different kinds of dry pulping methods were investigated. (a) Dry Pulping at Atmospheric Pressure: The first one is to dry and bake the pretreated woodchips in a conventional oven at atmospheric pressure without the use of a catalyst. (b) Dry Pulping at Reduced Pressure: The second method is to dry the pretreated woodchips first in a vacuum oven in the presence of anthraquinone (AQ) as a pulping catalyst, followed by baking at elevated temperature. (c) Liquid Free Chemical Pulping, LFCP. The third method is to first remove the free water of pretreated woodchips, followed by dry pulping using a conventional Kraft pulping digester with AQ and triton as additives. Method one: Experimental results indicated that Dry Pulping at Atmospheric Pressure could produce pulp with higher brightness and lower bulk than conventional Kraft pulp. However, tensile strength of the acquired pulp is much lower than traditional Kraft pulp, and their Kappa number and energy consumption are higher than conventional Kraft pulp. By fully analyzing the results, we concluded that wood fibers might be damaged during the drying process at elevated temperature. The main reason for wood fiber damage is that a long drying time was used during evaporation of water from the woodchips. This resulted in an un-uniform reaction condition on the woodchips: the outside layer of the woodchips was over reacted while inside the woodchips did not reacted at all. To solve this problem, dry pulping at reduced pressure was investigated. Method two: To achieve uniform reaction throughout the entire reaction system, the water inside the pretreated woodchips was

  4. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-01

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

  5. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy.

    PubMed

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-01

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup. PMID:25173282

  6. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy

    SciTech Connect

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-15

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

  7. Real-time observation of the dry oxidation of the Si (100) surface with ambient pressure x-ray photoelectron spectroscopy

    SciTech Connect

    Enta, Y.; Mun, B.S.; Rossi, M.; Ross Jr, P.N.; Hussain, Zahid; Fadley, C.S.; Lee, K.-S.; Kim, S.-K.

    2007-09-20

    We have applied ambient-pressure x-ray photoelectron spectroscopy with Si 2p chemical shifts to study the real-time dry oxidation of Si(100), using pressures in the range of 0.01-1 Torr and temperatures of 300-530 oC, and examining the oxide thickness range from 0 to ~;;25 Angstrom. The oxidation rate is initially very high (with rates of up to ~;;225 Angstrom/h) and then, after a certain initial thickness of the oxide in the range of 6-22 Angstrom is formed, decreases to a slow state (with rates of ~;;1.5-4.0 Angstrom/h). Neither the rapid nor the slow regime is explained by the standard Deal-Grove model for Si oxidation.

  8. Ambient pressure fuel cell system

    DOEpatents

    Wilson, Mahlon S.

    2000-01-01

    An ambient pressure fuel cell system is provided with a fuel cell stack formed from a plurality of fuel cells having membrane/electrode assemblies (MEAs) that are hydrated with liquid water and bipolar plates with anode and cathode sides for distributing hydrogen fuel gas and water to a first side of each one of the MEAs and air with reactant oxygen gas to a second side of each one of the MEAs. A pump supplies liquid water to the fuel cells. A recirculating system may be used to return unused hydrogen fuel gas to the stack. A near-ambient pressure blower blows air through the fuel cell stack in excess of reaction stoichiometric amounts to react with the hydrogen fuel gas.

  9. Effect of water ethanol solvents mixture on textural and gas sensing properties of tin oxide prepared using epoxide-assisted sol-gel process and dried at ambient pressure

    NASA Astrophysics Data System (ADS)

    Mahadik, D. B.; Lee, Yoon Kwang; Park, Chang-Sun; Chung, Hee-Yoon; Hong, Min-Hee; Jung, Hae-Noo-Ree; Han, Wooje; Park, Hyung-Ho

    2015-12-01

    High-surface-area tin oxide aerogels have been synthesized by an ambient-pressure drying method, using a non-alkoxide tin precursor and a hybrid sol-gel technique. The tin precursor was dissolved in different volume ratios of mixed water and ethanol solvents, and gelation was attained by means of an epoxide-initiated gelation process. The solvent in the gel was successively replaced with low-surface-tension solvents, and finally the gels were dried at ambient pressure in an oven. It was observed that solvent combinations significantly altered the textural properties of tin oxide aerogels. The solvent exchange process used prior to ambient-pressure drying helped to minimize impurities originating from the tin precursor. The tin oxide aerogels had the maximum specific surface area of 209 m2/g and small crystallite size (<6.5 nm) after an annealing treatment at 500 °C for 2 h. The sensitivity of a SnO2 sensor to CO gas was found to be strongly affected as the specific surface area of its constituent tin oxide aerogel was increased from 121 m2/g to 209 m2/g. This study offers evidence of the effects of tin oxide aerogel's specific surface area upon its gas sensing performance.

  10. Ambient Pressure LIF Instrument for Nitrogen Dioxide

    NASA Astrophysics Data System (ADS)

    Parra, J.; George, L. A.

    2009-12-01

    Concerns about the health effects of nitrogen dioxide (NO2) and its role in forming deleterious atmospheric species have made it desirable to have low-cost, sensitive ambient measurements of NO2. A continuous-wave laser-diode Laser Induced Fluorescence (LIF) system for NO2 that operates at ambient pressure has been developed, thereby eliminating the need for an expensive pumping system. The use of high quality optical filters has facilitated low-concentration detection of NO2 using atmospheric pressure LIF by providing substantial discrimination against scattered laser photons without the use of time-gated electronics, which add complexity and cost to the LIF instrumentation. This improvement allows operation at atmospheric pressure with a low-cost diaphragm sampling pump. The current prototype system has achieved sensitivity several orders of magnitude beyond previous efforts at ambient pressure (LOD of 2 ppb, 60 s averaging time). Ambient measurements of NO2 were made in Portland, OR using both the standard NO2 chemiluminescence method (CL-NO2) and the LIF instrument and showed good agreement (r2 = 0.92). Our instrument is currently being developed as a “back-end” detector for a more field portable NOy system. In addition, we are currently utilizing this instrument to study surface chemistry involving NO2 at atmospherically relevant concentrations and pressures.

  11. Improved Ambient Pressure Pyroelectric Ion Source

    NASA Technical Reports Server (NTRS)

    Beegle, Luther W.; Kim, Hugh I.; Kanik, Isik; Ryu, Ernest K.; Beckett, Brett

    2011-01-01

    The detection of volatile vapors of unknown species in a complex field environment is required in many different applications. Mass spectroscopic techniques require subsystems including an ionization unit and sample transport mechanism. All of these subsystems must have low mass, small volume, low power, and be rugged. A volatile molecular detector, an ambient pressure pyroelectric ion source (APPIS) that met these requirements, was recently reported by Caltech researchers to be used in in situ environments.

  12. Dry deposition of polycyclic aromatic hydrocarbons in ambient air

    SciTech Connect

    Sheu, H.L.; Lee, W.J.; Su, C.C.; Chao, H.R.; Fan, Y.C.

    1996-12-01

    Dry deposition and air sampling were undertaken, simultaneously, in the ambient air of an urban site and a petrochemical-industry (PCI) plant by using several dry deposition plates and PS-1 samplers from January to May 1994 in southern Taiwan. The dry deposition plate with a smooth surface was always pointed into the wind. Twenty-one polycyclic aromatic hydrocarbons (PAHs) were analyzed by a gas chromatography/mass spectrometer (GC/MSD). The dry deposition flux of total-PAHs in urban and PCI sites averaged 166 and 211 {micro}g/m{sup 2}{center_dot}d, respectively. In general, the PAH dry deposition flux increased with increases in the PAH concentration in the ambient air. The PAH pattern of dry deposition flux in both urban and PCI sites were similar to the pattern measured by the filter of the PS-1 sampler and completely different from the PAH pattern in the gas phase. The higher molecular weight PAHs have higher dry deposition velocities. This is due to the fact that higher molecular weight PAHs primarily associated with the particle phase are deposited mostly by gravitational settling, while the gas phase PAHs were between 0.001 and 0.010 cm/s, only the lower molecular-weight PAHs--Nap and AcPy--had a significant fraction of dry deposition flux contributed by the gas phase. All the remaining higher molecular-weight PAHs had more than 94.5% of their dry deposition flux resulting from the particle phase. This is due to the fact that higher molecular weight PAHs have a greater fraction in the particle phase and the dry deposition velocities of particulates are much higher than those of the gas phase.

  13. High-pressure inactivation of dried microorganisms.

    PubMed

    Espinasse, V; Perrier-Cornet, J-M; Marecat, A; Gervais, P

    2008-01-01

    Dried microorganisms are particularly resistant to high hydrostatic pressure effects. In this study, the survival of Saccharomyces cerevisiae was studied under pressure applied in different ways. Original processes and devices were purposely developed in our laboratory for long-term pressurization. Dried and wet yeast powders were submitted to high-pressure treatments (100-150 MPa for 24-144 h at 25 degrees C) through liquid media or inert gas. These powders were also pressurized after being vacuum-packed. In the case of wet yeasts, the pressurization procedure had little influence on the inactivation rate. In this case, inactivations were mainly due to hydrostatic pressure effects. Conversely, in the case of dried yeasts, inactivation was highly dependent on the treatment scheme. No mortality was observed when dried cells were pressurized in a non-aqueous liquid medium, but when nitrogen gas was used as the pressure-transmitting fluid, the inactivation rate was found to be between 1.5 and 2 log for the same pressure level and holding time. Several hypotheses were formulated to explain this phenomenon: the thermal effects induced by the pressure variations, the drying resulting from the gas pressure release and the sorption and desorption of the gas in cells. The highest inactivation rates were obtained with vacuum-packed dried yeasts. In this case, cell death occurred during the pressurization step and was induced by shear forces. Our results show that the mechanisms at the origin of cell death under pressure are strongly dependent on the nature of the pressure-transmitting medium and the hydration of microorganisms. PMID:17573691

  14. Bacterial decontamination using ambient pressure nonthermal discharges

    SciTech Connect

    Birmingham, J.G.; Hammerstrom, D.J.

    2000-02-01

    Atmospheric pressure nonthermal plasmas can efficiently deactivate bacteria in gases, liquids, and on surfaces, as well as can decompose hazardous chemicals. This paper focuses on the changes to bacterial spores and toxic biochemical compounds, such as mycotoxins, after their treatment in ambient pressure discharges. The ability of nonthermal plasmas to decompose toxic chemicals and deactivate hazardous biological materials has been applied to sterilizing medical instruments, ozonating water, and purifying air. In addition, the fast lysis of bacterial spores and other cells has led us to include plasma devices within pathogen detection instruments, where nucleic acids must be accessed. Decontaminating chemical and biological warfare materials from large, high value targets such as building surfaces, after a terrorist attack, are especially challenging. A large area plasma decontamination technology is described.

  15. Ambient pressure photoemission spectroscopy of metal surfaces

    NASA Astrophysics Data System (ADS)

    Baikie, Iain D.; Grain, Angela C.; Sutherland, James; Law, Jamie

    2014-12-01

    We describe a novel photoemission technique utilizing a traditional Kelvin probe as a detector of electrons/atmospheric ions ejected from metallic surfaces (Au, Ag, Cu, Fe, Ni, Ti, Zn, Al) illuminated by a deep ultra-violet (DUV) source under ambient pressure. To surmount the limitation of electron scattering in air the incident photon energy is rastered rather than applying a variable retarding electric field as is used with UPS. This arrangement can be applied in several operational modes: using the DUV source to determine the photoemission threshold (Φ) with 30-50 meV resolution and also the Kelvin probe, under dark conditions, to measure contact potential difference (CPD) between the Kelvin probe tip and the metallic sample with an accuracy of 1-3 meV. We have studied the relationship between the photoelectric threshold and CPD of metal surfaces cleaned in ambient conditions. Inclusion of a second spectroscopic visible source was used to confirm a semiconducting oxide, possibly Cu2O, via surface photovoltage measurements with the KP. This dual detection system can be easily extended to controlled gas conditions, relative humidity control and sample heating/cooling.

  16. Feasibility of Lettuce Growth at Hypoxic and Sub-Ambient Total Gas Pressures

    NASA Technical Reports Server (NTRS)

    Hoffman, Anne

    1997-01-01

    Lettuce (Lactuca saliva L. cv. 'Waldmann's Green') plants were grown (1) either from seed to 5 days old to study the effect of low atmospheric pressure (70 kPa) on their germination and early growth, or (2) until maturity at 30 days old to determine any long-term growth effects. The data were compared to plants grown in a second matching chamber which was maintained at ambient pressure (101 kPa) that served as a control. In other experiments, plants were grown at ambient pressure until maturity and then subjected to low atmospheric pressure for periods of 24 hours to determine possible effects of intermittent low pressure. The O2 and CO2 partial pressures in the low pressure chamber were adjusted to levels equal to those in the ambient pressure chamber to prevent differences in plant response which would have resulted from differences in the partial pressure of those gasses. The O2 partial pressure in the ambient chamber was maintained at 21 kPa and provision was made for additional CO2 during the fight phase. The germination rate and early seedling growth were insensitive to a low pressure environment. The rate of root elongation of plants grown at 70 kPa and at 101 kPa was also approximately the same. The rate of net carbon assimilation (per unit leaf area) of plants grown at low atmospheric pressure was unaffected at all growth stages even though plants grown at 70 kPa had slightly greater fresh and dry weights. There were consistent differences in assimilate partitioning, as shown by higher root/shoot ratios of plants grown at low pressure. Transpiration rates of plants grown until maturity under either constant or intermittent low pressure were reduced. Dark respiration rates of plants grown until maturity under either constant or intermittent low pressure were approximately 20% higher than the control plants.

  17. Blast wave parameters at diminished ambient pressure

    NASA Astrophysics Data System (ADS)

    Silnikov, M. V.; Chernyshov, M. V.; Mikhaylin, A. I.

    2015-04-01

    Relation between blast wave parameters resulted from a condensed high explosive (HE) charge detonation and a surrounding gas (air) pressure has been studied. Blast wave pressure and impulse differences at compression and rarefaction phases, which traditionally determine damage explosive effect, has been analyzed. An initial pressure effect on a post-explosion quasi-static component of the blast load has been investigated. The analysis is based on empirical relations between blast parameters and non-dimensional similarity criteria. The results can be directly applied to flying vehicle (aircraft or spacecraft) blast safety analysis.

  18. Carbon aerogel composites prepared by ambient drying and using oxidized polyacrylonitrile fibers as reinforcements.

    PubMed

    Feng, Junzong; Zhang, Changrui; Feng, Jian; Jiang, Yonggang; Zhao, Nan

    2011-12-01

    Carbon fiber-reinforced carbon aerogel composites (C/CAs) for thermal insulators were prepared by copyrolysis of resorcinol-formaldehyde (RF) aerogels reinforced by oxidized polyacrylonitrile (PAN) fiber felts. The RF aerogel composites were obtained by impregnating PAN fiber felts with RF sols, then aging, ethanol exchanging, and drying at ambient pressure. Upon carbonization, the PAN fibers shrink with the RF aerogels, thus reducing the difference of shrinkage rates between the fiber reinforcements and the aerogel matrices, and resulting in C/CAs without any obvious cracks. The three point bend strength of the C/CAs is 7.1 ± 1.7 MPa, and the thermal conductivity is 0.328 W m(-1) K(-1) at 300 °C in air. These composites can be used as high-temperature thermal insulators (in inert atmospheres or vacuum) or supports for phase change materials in thermal protection system. PMID:22047011

  19. Effect of ambient pressure on liquid swirl injector flow dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Yang, Vigor

    2014-10-01

    In this paper, a combined theoretical and numerical analysis is performed to study the internal and external flowfields of a liquid swirl injector. The effect of ambient pressure on the injector dynamics is explored systematically over a range of 1-50 atm. An increase in the ambient pressure increases the liquid film thickness, but decreases the spreading angle. This phenomenon can be attributed to the modification of the velocity profiles within the liquid film near the gas-liquid interface due to the alteration of the gas-phase shear stresses with pressure. The friction force at the interface plays a minor role. The generation and existence of stationary waves in the injector nozzle is also considered. At a higher ambient pressure, the pressure drop across the liquid sheet downstream of the injector exit increases, thereby suppressing the spreading of the liquid sheet. This in turn increases the thickness of the liquid sheet, and subsequently increases the breakup length at higher pressure. A semi-empirical model is developed to relate the velocity and pressure distributions near the surface of the liquid sheet. Good agreement is achieved between the measured and predicted shape and spreading angle of the liquid sheet.

  20. Modulated corona nanosecond discharge in air under ambient pressure

    NASA Astrophysics Data System (ADS)

    Lepekhin, N. M.; Priseko, Yu. S.; Filippov, V. G.; Bulatov, M. U.; Sukharevskii, D. I.; Syssoev, V. S.

    2015-04-01

    A unique type of corona discharge-modulated corona nanosecond discharge-has been obtained, the parameters of which have been determined in a geometric system of electrodes with a sharply heterogeneous electric field in air under ambient pressure and natural humidity.

  1. Measurement of Radiation Pressure in an Ambient Environment

    NASA Astrophysics Data System (ADS)

    Ma, Dakang; Garrett, Joseph; Munday, Jeremy

    2015-03-01

    Light has momentum and thus exerts ``radiation pressure'' when it is reflected or absorbed due to the conservation of momentum. Micromechanical transducers and oscillators are suitable for measurement and utilization of radiation pressure due to their high sensitivities. However, other light-induced mechanical deformations such as photothermal effects often obscure accurate measurements of radiation pressure in these systems. In this work, we investigate the radiation pressure and photothermal force on an uncoated silicon nitride microcantilever under illumination by a 660 nm laser in an ambient environment. To magnify the mechanical effects, the cantilever is driven optically from dc across its resonance frequency, and the amplitude and phase of its oscillation are acquired by an optical beam deflection method and a lockin amplifier. We show that radiation pressure and photothermal effects can be distinguished through the cantilever's frequency response. Furthermore, in a radiation pressure dominant regime, our measurement of the radiation force agrees quantitatively with the theoretical calculation.

  2. Two-phase flows within systems with ambient pressure

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Braun, M. J.; Wheeler, R. L., III; Mullen, R. L.

    1985-01-01

    In systems where the design inlet and outlet pressures are maintained above the thermodynamic critical pressure, it is often assumed that two phase flows within the system cannot occur. Designers rely on this simple rule of thumb to circumvent problems associated with a highly compressible two phase flow occurring within the supercritical pressure system along with the uncertainties in rotordynamics, load capacity, heat transfer, fluid mechanics, and thermophysical property variations. The simple rule of thumb is adequate in many low power designs but is inadequate for high performance turbomachines and linear systems, where two phase regions can exist even though outlet pressure is greater than critical pressure. Rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two phase zone can differ significantly from those for a single-phase zone. Using the Reynolds equation the angular velocity, eccentricity, geometry, and ambient conditions are varied to determine the point of two phase flow incipience.

  3. Photoelectron Spectroscopy under Ambient Pressure and Temperature Conditions

    SciTech Connect

    Ogletree, D. Frank; Bluhm, Hendrik; Hebenstreit, Eleonore B.; Salmeron, Miquel

    2009-02-27

    We describe the development and applications of novel instrumentation for photoemission spectroscopy of solid or liquid surfaces in the presence of gases under ambient conditions or pressure and temperature. The new instrument overcomes the strong scattering of electrons in gases by the use of an aperture close to the surface followed by a differentially-pumped electrostatic lens system. In addition to the scattering problem, experiments in the presence of condensed water or other liquids require the development of special sample holders to provide localized cooling. We discuss the first two generations of Ambient Pressure PhotoEmission Spectroscopy (APPES) instruments developed at synchrotron light sources (ALS in Berkeley and BESSY in Berlin), with special focus on the Berkeley instruments. Applications to environmental science and catalytic chemical research are illustrated in two examples.

  4. Impact of ambient pressure on performance of desiccant cooling systems

    NASA Astrophysics Data System (ADS)

    Pesaran, A. A.

    1991-12-01

    The impact of ambient pressure on the performance of the ventilation cycle desiccant cooling system and its components was studied using computer simulations. The impact of ambient pressure depended on whether the system was designed for fixed-mass flow rate or fixed-volume flow rate operation. As ambient pressure decreased from 1.0 to 0.8 atm, the system thermal coefficient of performance increased by 8 pct. for both fixed-mass and fixed-volume flow rate, the cooling capacity of the system (in kW) was decreased by 14 pct. for the fixed-volume flow rate system and increased by 7 pct. for the fixed-mass flow rate system, the electric power requirements for the system with fixed-volume flow rate did not change, and the electric power requirement for the fixed-mass flow rate system increased by 44 pct. The overall coefficient of performance increased up to 5 pct. for the fixed-volume flow rate systems, and decreased up to 4 pct. for the fixed-mass flow rate system.

  5. Stable Calcium Nitrides at Ambient and High Pressures.

    PubMed

    Zhu, Shuangshuang; Peng, Feng; Liu, Hanyu; Majumdar, Arnab; Gao, Tao; Yao, Yansun

    2016-08-01

    The knowledge of stoichiometries of alkaline-earth metal nitrides, where nitrogen can exist in polynitrogen forms, is of significant interest for understanding nitrogen bonding and its applications in energy storage. For calcium nitrides, there were three known crystalline forms, CaN2, Ca2N, and Ca3N2, at ambient conditions. In the present study, we demonstrated that there are more stable forms of calcium nitrides than what is already known to exist at ambient and high pressures. Using a global structure searching method, we theoretically explored the phase diagram of CaNx and discovered a series of new compounds in this family. In particular, we found a new CaN phase that is thermodynamically stable at ambient conditions, which may be synthesized using CaN2 and Ca2N. Four other stoichiometries, namely, Ca2N3, CaN3, CaN4, and CaN5, were shown to be stable under high pressure. The predicted CaNx compounds contain a rich variety of polynitrogen forms ranging from small molecules (N2, N4, N5, and N6) to extended chains (N∞). Because of the large energy difference between the single and triple nitrogen bonds, dissociation of the CaNx crystals with polynitrogens is expected to be highly exothermic, making them as potential high-energy-density materials. PMID:27428707

  6. Orion ECLSS/Suit System - Ambient Pressure Integrated Suit Test

    NASA Technical Reports Server (NTRS)

    Barido, Richard A.

    2012-01-01

    The Ambient Pressure Integrated Suit Test (APIST) phase of the integrated system testing of the Orion Vehicle Atmosphere Revitalization System (ARS) technology was conducted for the Multipurpose Crew Vehicle (MPCV) Program within the National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate. Crew and Thermal Systems Division performed this test in the eleven-foot human-rated vacuum chamber at the NASA Johnson Space Center. This testing is the first phase of suit loop testing to demonstrate the viability of the Environmental Control and Life Support System (ECLSS) being developed for Orion. APIST is the first in a series, which will consist of testing development hardware including the Carbon dioxide and Moisture Removal Amine Swing-bed (CAMRAS) and the air revitalization loop fan with human test subjects in pressure suits at varying suit pressures. Follow-on testing, to be conducted in 2013, will utilize the CAMRAS and a development regulator with human test subjects in pressure suits at varying cabin and suit pressures. This paper will discuss the results and findings of APIST and will also discuss future testing.

  7. CO oxidation on Pt(111) at near ambient pressures

    NASA Astrophysics Data System (ADS)

    Krick Calderón, S.; Grabau, M.; Ã`vári, L.; Kress, B.; Steinrück, H.-P.; Papp, C.

    2016-01-01

    The oxidation of CO on Pt(111) was investigated simultaneously by near ambient pressure X-ray photoelectron spectroscopy and online gas analysis. Different CO:O2 reaction mixtures at total pressures of up to 1 mbar were used in continuous flow mode to obtain an understanding of the surface chemistry. By temperature-programmed and by isothermal measurements, the onset temperature of the reaction was determined for the different reactant mixtures. Highest turnover frequencies were found for the stoichiometric mixture. At elevated temperatures, the reaction becomes diffusion-limited in both temperature-programmed and isothermal measurements. In the highly active regime, no adsorbates were detected on the surface; it is therefore concluded that the catalyst surface is in a metallic state, within the detection limits of the experiment, under the applied conditions. Minor bulk impurities such as silicon were observed to influence the reaction up to total inhibition by formation of non-platinum oxides.

  8. Live Pups from Evaporatively Dried Mouse Sperm Stored at Ambient Temperature for up to 2 Years

    PubMed Central

    Liu, Jie; Lee, Gloria Y.; Lawitts, Joel A.; Toner, Mehmet; Biggers, John D.

    2014-01-01

    The purpose of this study is to develop a mouse sperm preservation method based on evaporative drying. Mouse sperm were evaporatively dried and stored at 4°C and ambient temperature for 3 months to 2 years. Upon rehydration, a single sperm was injected into a mature oocyte to develop into a blastocyst after culture or a live birth after embryo transfer to a recipient female. For the samples stored at 4°C for 3, 6, 12, 18, and 24 months, the blastocyst formation rate was 61.5%, 49.1%, 31.5%, 32.2%, and 41.4%, respectively. The blastocyst rate for those stored at ambient temperature (∼22°C) for 3, 6, 12, and 18 months was 57.8%, 36.2%, 33.6%, and 34.4%, respectively. Fifteen, eight and three live pups were produced from sperm stored at room temperature for 12, 18, and 24 months, respectively. This is the first report of live offspring produced from dried mouse sperm stored at ambient temperature for up to 2 years. Based on these results, we suggest that evaporative drying is a potentially useful method for the routine preservation of mouse sperm. PMID:24924588

  9. Design principles for high-pressure force fields: Aqueous TMAO solutions from ambient to kilobar pressures.

    PubMed

    Hölzl, Christoph; Kibies, Patrick; Imoto, Sho; Frach, Roland; Suladze, Saba; Winter, Roland; Marx, Dominik; Horinek, Dominik; Kast, Stefan M

    2016-04-14

    Accurate force fields are one of the major pillars on which successful molecular dynamics simulations of complex biomolecular processes rest. They have been optimized for ambient conditions, whereas high-pressure simulations become increasingly important in pressure perturbation studies, using pressure as an independent thermodynamic variable. Here, we explore the design of non-polarizable force fields tailored to work well in the realm of kilobar pressures - while avoiding complete reparameterization. Our key is to first compute the pressure-induced electronic and structural response of a solute by combining an integral equation approach to include pressure effects on solvent structure with a quantum-chemical treatment of the solute within the embedded cluster reference interaction site model (EC-RISM) framework. Next, the solute's response to compression is taken into account by introducing pressure-dependence into selected parameters of a well-established force field. In our proof-of-principle study, the full machinery is applied to N,N,N-trimethylamine-N-oxide (TMAO) in water being a potent osmolyte that counteracts pressure denaturation. EC-RISM theory is shown to describe well the charge redistribution upon compression of TMAO(aq) to 10 kbar, which is then embodied in force field molecular dynamics by pressure-dependent partial charges. The performance of the high pressure force field is assessed by comparing to experimental and ab initio molecular dynamics data. Beyond its broad usefulness for designing non-polarizable force fields for extreme thermodynamic conditions, a good description of the pressure-response of solutions is highly recommended when constructing and validating polarizable force fields. PMID:27083705

  10. Design principles for high-pressure force fields: Aqueous TMAO solutions from ambient to kilobar pressures

    NASA Astrophysics Data System (ADS)

    Hölzl, Christoph; Kibies, Patrick; Imoto, Sho; Frach, Roland; Suladze, Saba; Winter, Roland; Marx, Dominik; Horinek, Dominik; Kast, Stefan M.

    2016-04-01

    Accurate force fields are one of the major pillars on which successful molecular dynamics simulations of complex biomolecular processes rest. They have been optimized for ambient conditions, whereas high-pressure simulations become increasingly important in pressure perturbation studies, using pressure as an independent thermodynamic variable. Here, we explore the design of non-polarizable force fields tailored to work well in the realm of kilobar pressures - while avoiding complete reparameterization. Our key is to first compute the pressure-induced electronic and structural response of a solute by combining an integral equation approach to include pressure effects on solvent structure with a quantum-chemical treatment of the solute within the embedded cluster reference interaction site model (EC-RISM) framework. Next, the solute's response to compression is taken into account by introducing pressure-dependence into selected parameters of a well-established force field. In our proof-of-principle study, the full machinery is applied to N,N,N-trimethylamine-N-oxide (TMAO) in water being a potent osmolyte that counteracts pressure denaturation. EC-RISM theory is shown to describe well the charge redistribution upon compression of TMAO(aq) to 10 kbar, which is then embodied in force field molecular dynamics by pressure-dependent partial charges. The performance of the high pressure force field is assessed by comparing to experimental and ab initio molecular dynamics data. Beyond its broad usefulness for designing non-polarizable force fields for extreme thermodynamic conditions, a good description of the pressure-response of solutions is highly recommended when constructing and validating polarizable force fields.

  11. The effect of ambient pressure on the spray characteristics of a twin-fluid atomizer

    NASA Astrophysics Data System (ADS)

    Drennan, S. A.; Sowa, W. A.; Samuelsen, G. S.

    1990-06-01

    A combined simplex/air-assist atomizer with swirl is characterized in an isothermal high-pressure spray-characterization chamber, with optical access, under various ambient pressures. A single-component, phase Doppler laser interferometer is used to obtain spatially resolved droplet size and velocity information. Data are obtained at atmospheric pressure as well as 3 and 6 atmospheres for conditions of constant fuel and atomizing air flow rates. Two different nozzle air flow rates and, hence, two different air-to-liquid ratios are considered. Increasing ambient pressure decreases the air-to-liquid momentum ratio and thereby decreases droplet mean axial velocity and increases the droplet size. The response of a spray to increasing ambient pressure is sensitive to the parameters which are held constant while increasing ambient pressure.

  12. Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions

    PubMed Central

    Groot, S. P. C.; Surki, A. A.; de Vos, R. C. H.; Kodde, J.

    2012-01-01

    Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. Key Results The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Conclusions Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice. PMID:22967856

  13. Permeability, drying, and sintering of pressure filtered ceramic nanopowders

    NASA Astrophysics Data System (ADS)

    Sweeney, Sean M.

    2002-01-01

    Three aspects of nanocrystalline ceramic body formation are examined in this work: permeability, drying stress, and sintering behavior. The permeabilities of nanocrystalline 3 mol% yttria-stabilized zirconia (3Y-TZP), silica, and boehmite powder compacts are measured during their formation by constant rate pressure filtration. The classic Carman-Kozeny equation with no account for the effect of adsorbed water often overestimates by a factor of 2 or more the measured permeabilities, with increasing deviation with decreasing permeability. A permeability equation from the literature and one derived here, both taking into account the effect of adsorbed water, show significant improvement over the classic Carman-Kozeny equation for predicting measured permeabilities. The equation derived here allows straightforward predictions to be made of how permeability will change as the critical point of drying (when shrinkage stops) is approached. An approximate expression for the maximum tensile stress occurring in an elastic finite cylinder during drying from all sides is derived. Numerical calculations of the exact state of stress during drying show that for cylinder length-to-diameter ratios up to 2/3, the present expression is more accurate than equations from the literature for an infinite plate and an infinite cylinder. For cylinders with length-to-diameter ratios greater than 2/3, numerical calculations show an equation from the literature for the drying stress in an infinite cylinder to be more accurate. To test the validity of the present expression, the drying rates above which fracture occurs are determined for disk-shaped samples of pressure filtered nanocrystalline 3Y-TZP, boehmite, and silica powders. These maximum safe drying rates are used with the present expression to calculate the maximum drying stresses that can be sustained without fracture, and these stresses are compared to diametral compression-measured strengths of similar samples dried to the critical

  14. Insights into electrochemical reactions from ambient pressure photoelectron spectroscopy.

    PubMed

    Stoerzinger, Kelsey A; Hong, Wesley T; Crumlin, Ethan J; Bluhm, Hendrik; Shao-Horn, Yang

    2015-11-17

    The understanding of fundamental processes in the bulk and at the interfaces of electrochemical devices is a prerequisite for the development of new technologies with higher efficiency and improved performance. One energy storage scheme of great interest is splitting water to form hydrogen and oxygen gas and converting back to electrical energy by their subsequent recombination with only water as a byproduct. However, kinetic limitations to the rate of oxygen-based electrochemical reactions hamper the efficiency in technologies such as solar fuels, fuel cells, and electrolyzers. For these reactions, the use of metal oxides as electrocatalysts is prevalent due to their stability, low cost, and ability to store oxygen within the lattice. However, due to the inherently convoluted nature of electrochemical and chemical processes in electrochemical systems, it is difficult to isolate and study individual electrochemical processes in a complex system. Therefore, in situ characterization tools are required for observing related physical and chemical processes directly at the places where and while they occur and can help elucidate the mechanisms of charge separation and charge transfer at electrochemical interfaces. X-ray photoelectron spectroscopy (XPS), also known as ESCA (electron spectroscopy for chemical analysis), has been used as a quantitative spectroscopic technique that measures the elemental composition, as well as chemical and electronic state of a material. Building from extensive ex situ characterization of electrochemical systems, initial in situ studies were conducted at or near ultrahigh vacuum (UHV) conditions (≤10(-6) Torr) to probe solid-state electrochemical systems. However, through the integration of differential-pumping stages, XPS can now operate at pressures in the torr range, comprising a technique called ambient pressure XPS (AP-XPS). In this Account, we briefly review the working principles and current status of AP-XPS. We use several recent

  15. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test for effect of variations in ambient pressure. 53.56 Section 53.56 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Testing Physical (Design) and...

  16. Barley Seed Aging: Genetics behind the Dry Elevated Pressure of Oxygen Aging and Moist Controlled Deterioration

    PubMed Central

    Nagel, Manuela; Kodde, Jan; Pistrick, Sibylle; Mascher, Martin; Börner, Andreas; Groot, Steven P. C.

    2016-01-01

    Experimental seed aging approaches intend to mimic seed deterioration processes to achieve a storage interval reduction. Common methods apply higher seed moisture levels and temperatures. In contrast, the “elevated partial pressure of oxygen” (EPPO) approach treats dry seed stored at ambient temperatures with high oxygen pressure. To analyse the genetic background of seed longevity and the effects of seed aging under dry conditions, the EPPO approach was applied to the progeny of the Oregon Wolfe Barley (OWB) mapping population. In comparison to a non-treated control and a control high-pressure nitrogen treatment, EPPO stored seeds showed typical symptoms of aging with a significant reduction of normal seedlings, slower germination, and less total germination. Thereby, the parent Dom (“OWB-D”), carrying dominant alleles, is more sensitive to aging in comparison to the population mean and in most cases to the parent Rec (“OWB-R”), carrying recessive alleles. Quantitative trait locus (QTL) analyses using 2832 markers revealed 65 QTLs, including two major loci for seed vigor on 2H and 7H. QTLs for EPPO tolerance were detected on 3H, 4H, and 5H. An applied controlled deterioration (CD) treatment (aged at higher moisture level and temperature) revealed a tolerance QTL on 5H, indicating that the mechanism of seed deterioration differs in part between EPPO or CD conditions. PMID:27066038

  17. Barley Seed Aging: Genetics behind the Dry Elevated Pressure of Oxygen Aging and Moist Controlled Deterioration.

    PubMed

    Nagel, Manuela; Kodde, Jan; Pistrick, Sibylle; Mascher, Martin; Börner, Andreas; Groot, Steven P C

    2016-01-01

    Experimental seed aging approaches intend to mimic seed deterioration processes to achieve a storage interval reduction. Common methods apply higher seed moisture levels and temperatures. In contrast, the "elevated partial pressure of oxygen" (EPPO) approach treats dry seed stored at ambient temperatures with high oxygen pressure. To analyse the genetic background of seed longevity and the effects of seed aging under dry conditions, the EPPO approach was applied to the progeny of the Oregon Wolfe Barley (OWB) mapping population. In comparison to a non-treated control and a control high-pressure nitrogen treatment, EPPO stored seeds showed typical symptoms of aging with a significant reduction of normal seedlings, slower germination, and less total germination. Thereby, the parent Dom ("OWB-D"), carrying dominant alleles, is more sensitive to aging in comparison to the population mean and in most cases to the parent Rec ("OWB-R"), carrying recessive alleles. Quantitative trait locus (QTL) analyses using 2832 markers revealed 65 QTLs, including two major loci for seed vigor on 2H and 7H. QTLs for EPPO tolerance were detected on 3H, 4H, and 5H. An applied controlled deterioration (CD) treatment (aged at higher moisture level and temperature) revealed a tolerance QTL on 5H, indicating that the mechanism of seed deterioration differs in part between EPPO or CD conditions. PMID:27066038

  18. Simulation of Low-density Nozzle Plumes in Non-zero Ambient Pressures

    NASA Technical Reports Server (NTRS)

    Chung, Chan-Hong; Dewitt, Kenneth J.; Stubbs, Robert M.; Penko, Paul F.

    1994-01-01

    The direct simulation Monte-Carlo (DSMC) method was applied to the analysis of low-density nitrogen plumes exhausting from a small converging-diverging nozzle into finite ambient pressures. Two cases were considered that simulated actual test conditions in a vacuum facility. The numerical simulations readily captured the complicated flow structure of the overexpanded plumes adjusting to the finite ambient pressures, including Mach disks and barrel shaped shocks. The numerical simulations compared well to experimental data of Rothe.

  19. Simulation of low-density nozzle plumes in non-zero ambient pressures

    NASA Astrophysics Data System (ADS)

    Chung, Chan-Hong; Dewitt, Kenneth J.; Stubbs, Robert M.; Penko, Paul F.

    1994-02-01

    The direct simulation Monte-Carlo (DSMC) method was applied to the analysis of low-density nitrogen plumes exhausting from a small converging-diverging nozzle into finite ambient pressures. Two cases were considered that simulated actual test conditions in a vacuum facility. The numerical simulations readily captured the complicated flow structure of the overexpanded plumes adjusting to the finite ambient pressures, including Mach disks and barrel shaped shocks. The numerical simulations compared well to experimental data of Rothe.

  20. Textile dry cleaning in high pressure CO2

    NASA Astrophysics Data System (ADS)

    Sutanto, Stevia; van der Kamp, Maaike; Witkamp, Geert-Jan

    2013-06-01

    High-pressure carbon dioxide (CO2) is one of the most suitable replacements for perchloroethylene (PER), a common but harmful textile dry cleaning solvent. Previous studies have indicated that the particulate soil removal with CO2 is lower compared to that with PER, because of the lesser amount of mechanical action in CO2. Furthermore, there is a lack of understanding of textile-dirt-CO2 interaction. It is the objective of this study to get an insight in the mechanical forces that play a role in CO2 dry cleaning and to use this information to improve the CO2 washing performance. Various mechanical actions were investigated with the experiments in an in-situ high pressure observation cell. Textiles stained with different kinds of particulate soils were washed in CO2. The washing results show that the combination of rotating and vertical action gives the highest cleaning performance and liquid CO2 spray may be a suitable additional mechanism to increase the cleaning performance. Authors thank the scientific foundation STW for the financial support.

  1. Experimental investigations of beet pulp drying in superheated steam under pressure

    SciTech Connect

    Urbaniec, K.; Malczewski, J.

    1997-10-01

    Beet pulp drying in superheated steam under pressure makes it possible to save energy in sugar factories. A new concept of a two-stage convective steam drier is presented. To obtain kinetic data on beet pulp drying, an experimental setup was built. Beet pulp samples were dried at steam pressure up to 4 bar and temperature up to 220 C.

  2. Pressure cycle rheology of nanofluids at ambient temperature

    NASA Astrophysics Data System (ADS)

    Kanjirakat, Anoop; Sadr, Reza; Yrac, Rommel; Amani, Mahmood

    2015-11-01

    Colloidal suspensions of particles dispersed in a base fluid (or drilling fluid) are commonly used in oil industry to aid the drilling of oil well into the ground. Nanofluids, the colloidal suspensions of nano-sized particles dispersed in a basefluid, have also shown potentials as cooling and abrasive fluids. Utilizing them along with drilling fluids under cyclic high-pressure loadings have not been investigated so far. In the present work, rheological characteristics of silicon oil based nanofluids (prepared with alumina nanoparticles) under pressures up to 1000 bar are investigated using a high-pressure viscometer. The rheological characteristics of nanofluids are measured and are compared with that of the basefluid under increasing and decreasing pressures. Relative viscosity variations of nanofluids were observed to have influenced by the shear rate. In addition, under cyclic high-pressure loading viscosity values of nanofluids are observed to have reduced. This reduction in viscosity at the second pressure cycle could have been caused by the de-agglomeration of particles in the first cycle while working a high-pressure and high-shear condition.

  3. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  4. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  5. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  6. A process to recover plastics from obsolete automobiles by using solvents at ambient pressure

    SciTech Connect

    Jody, B.J.; Daniels, E.J.; Bonsignore, P.V.; Brockmeier, N.F.

    1993-08-01

    Recycling of the metal content of obsolete vehicles has been actively pursued since the 1950s; today, obsolete automobiles are the single largest source of scrap iron. They contribute over 25% of the 36 metric tonnes (40 million short tons) of ferrous scrap recovered annually by the secondary metals industry and used in the production of finished steel products. They also contribute over one million metric tonnes (1.1 million short tons) of nonferrous metallic scrap a year for recycling. For each ton of metals recovered, about 500 lb of nonmetallic residue or waste is co-produced. Auto shredder residue (ASR) is a very heterogeneous mixture of solids and liquids. Table I lists most of the materials that are commonly present in the ASR are listed. We have developed and tested in the laboratory a three-step process to separate thermoplastics, and other potentially recyclable products, from ASR. The process involves a drying step followed by a mechanical separation step to concentrate the thermoplastics by separating the polyurethane foam and the fines, which are mostly metal oxides and other inert materials that are smaller than 0.62 cm (0.25 in.) in size. The concentrated plastics stream is then treated with organic solvents at ambient pressure and elevated temperatures to dissolve the desired plastics. The salient features of the process are described.

  7. Pressure-induced irreversible phase transitions of the monoclinic GdOOH nanorods at ambient temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanchao; Dai, Rucheng; Sui, Zhilei; Chen, Qiao; Wang, Zhongping; Yuan, Xiaodong; Zhang, Zengming; Ding, Zejun

    2014-09-01

    The structural transition of monoclinic GdOOH nanorods was studied by using a diamond anvil cell at room temperature with the probe of Eu3+ ion luminescence under pressures up to 21.4 GPa. The changes of luminescence spectra indicated that a pressure-induced phase transition from the monoclinic phase to the high pressure tetragonal phase occurs at 10.7 GPa for GdOOH nanorods, and the monoclinic GdOOH nanorods are gradually transformed into the tetragonal phase with increasing pressure. After releasing of pressure to the ambient, the high pressure tetragonal phase is retained, and the phase transition of GdOOH nanorods is irreversible.

  8. Emission features and expansion dynamics of nanosecond laser ablation plumes at different ambient pressures

    SciTech Connect

    Farid, N.; Harilal, S. S. Hassanein, A.; Ding, H.

    2014-01-21

    The influence of ambient pressure on the spectral emission features and expansion dynamics of a plasma plume generated on a metal target has been investigated. The plasma plumes were generated by irradiating Cu targets using 6 ns, 1064 nm pulses from a Q-switched Nd:YAG laser. The emission and expansion dynamics of the plasma plumes were studied by varying air ambient pressure levels ranging from vacuum to atmospheric pressure. The ambient pressure levels were found to affect both the line intensities and broadening along with the signal to background and signal to noise ratios and the optimum pressure conditions for analytical applications were evaluated. The characteristic plume parameters were estimated using emission spectroscopy means and noticed that the excitation temperature peaked ∼300 Torr, while the electron density showed a maximum ∼100 Torr. Fast-gated images showed a complex interaction between the plume and background air leading to changes in the plume geometry with pressure as well as time. Surface morphology of irradiated surface showed that the pressure of the ambient gas affects the laser-target coupling significantly.

  9. Determination of the thermodynamic scaling exponent for relaxation in liquids from static ambient-pressure quantities.

    PubMed

    Casalini, R; Roland, C M

    2014-08-22

    An equation is derived that expresses the thermodynamic scaling exponent, γ, which superposes relaxation times τ and other measures of molecular mobility determined over a range of temperatures and densities, in terms of static physical quantities. The latter are available in the literature or can be measured at ambient pressure. We show for 13 materials, both molecular liquids and polymers, that the calculated γ are equivalent to the scaling exponents obtained directly by superpositioning. The assumptions of the analysis are that the glass transition T(g) is isochronal (i.e., τ(α) is constant at T(g), which is true by definition) and that the pressure derivative of the glass temperature is given by the first Ehrenfest relation. The latter, derived assuming continuity of the entropy at the glass transition, has been corroborated for many glass-forming materials at ambient pressure. However, we find that the Ehrenfest relation breaks down at elevated pressure; this limitation is of no consequence herein, since the appeal of the new equation is its applicability to ambient-pressure data. The ability to determine, from ambient-pressure measurements, the scaling exponent describing the high-pressure dynamics extends the applicability of this approach to a broader range of materials. Since γ is linked to the intermolecular potential, the new equation thus provides ready access to information about the forces between molecules. PMID:25192107

  10. Cellular and neurophysiological effects of high ambient pressure.

    PubMed

    Daniels, S

    2008-01-01

    The observed cellular effects of pressure are entirely compatible with the acute manifestations of CNS hyperexcitability. Inhibition of the glycine receptor will reduce post-synaptic inhibition, leading to increased excitability (cf 'Startle Disease', an hereditary disease with increased excitability arising from a genetic modification to the glycine receptor (Becker et al., 2002)). Since glycine-mediated neurotransmission is particularly associated with motor reflex circuits (Lynch, 2004) it is not surprising that many of the acute manifestations of pressure involve motor dysfunction. Potentiation by pressure of the NR1-NR2C subtype of the NMDA-sensitive glutamate receptor will lead to increased excitability within the cerebellum (where this receptor sub-type is most highly expressed (Monyer et al., 1994)). Although the cerebellum receives input from many parts of the nervous system, it projects primarily to the motor and frontal lobe cognitive areas. Thus dysfunction of the glutamate-mediated excitatory neurotransmission in this area is most likely to result in locomotor and cognitive symptoms, characteristic of acute pressure effects. Finally, the effects observed on AC/cAMP intracellular signalling, probably mediated via dopamine receptors, is also likely to produce motor dysfunction (cf Parkinson's disease). The observed cellular effects also suggest potential mechanisms that could result in long-term CNS dysfunction. Potentiation of glutamate neurotransmission is likely to lead to excessive calcium entry into those neurons. This may trigger excitotoxicity via a signal cascade in which neuronal NO synthase is activated producing the toxic free radical peroxynitrite and activation of the proapoptotic protein poly(ADP-ribose) polymerase (Aarts & Tymianski, 2005). An additional mechanism, also initially triggered by a rise in intracellular calcium through NR1-NR2C receptors, involves activation of a member of the Transient Receptor Potential (TRP) channel

  11. MD studies of electron transfer at ambient and elevated pressures

    NASA Astrophysics Data System (ADS)

    Giles, Alex; Spooner, Jacob; Weinberg, Noham

    2013-06-01

    The effect of pressure on the rate constants of outer-sphere electron transfer reactions has often been described using the Marcus-Hush theory. This theory agrees well with experiment when internal reorganization of the ionic system is negligible, however it does not offer a recipe for calculation of the effects that result from significant solute restructuring. We have recently developed a molecular dynamics technique that accurately describes structural dependence of molecular volumes in non-polar and weakly polar systems. We are now extending this approach to the case of highly polar ionic systems where both solvent and solute restructuring components are important. For this purpose we construct pressure-dependent two-dimensional surfaces for electron transfer reactions in coordinate system composed of interionic distance and Marcus-type solvent polarization coordinate, and use these surfaces to describe pressure effects on reaction kinetics. R.A. Marcus. J. Chem. Phys. 24, 966 (1956); 24, 979 (1956); 26, 867 (1957). Discuss. Faraday Soc. 29, 21 (1960). Faraday Discuss. Chem. Soc. 74, 7 (1982); N.S. Hush. Trans. Faraday Soc. 57, 557 (1961).

  12. Novel lithium-nitrogen compounds at ambient and high pressures

    PubMed Central

    Shen, Yanqing; Oganov, Artem R.; Qian, Guangri; Zhang, Jin; Dong, Huafeng; Zhu, Qiang; Zhou, Zhongxiang

    2015-01-01

    Using ab initio evolutionary simulations, we predict the existence of five novel stable Li-N compounds at pressures from 0 to 100 GPa (Li13N, Li5N, Li3N2, LiN2, and LiN5). Structures of these compounds contain isolated N atoms, N2 dimers, polyacetylene-like N chains and N5 rings, respectively. The structure of Li13N consists of Li atoms and Li12N icosahedra (with N atom in the center of the Li12 icosahedron) – such icosahedra are not described by Wade-Jemmis electron counting rules and are unique. Electronic structure of Li-N compounds is found to dramatically depend on composition and pressure, making this system ideal for studying metal-insulator transitions. For example, the sequence of lowest-enthalpy structures of LiN3 shows peculiar electronic structure changes with increasing pressure: metal-insulator-metal-insulator. This work also resolves the previous controversies of theory and experiment on Li2N2. PMID:26374272

  13. Self-Propagating Frontal Polymerization in Water at Ambient Pressure

    NASA Technical Reports Server (NTRS)

    Olten, Nesrin; Kraigsley, Alison; Ronney, Paul D.

    2003-01-01

    Advances in polymer chemistry have led to the development of monomers and initiation agents that enable propagating free-radical polymerization fronts to exist. These fronts are driven by the exothermicity of the polymerization reaction and the transport of heat from the polymerized product to the reactant monomer/solvent/initiator solution. The thermal energy transported to the reactant solution causes the initiator to decompose, yielding free radicals, which start the free radical polymerization process as discussed in recent reviews. The use of polymerization processes based on propagating fronts has numerous applications. Perhaps the most important of these is that it enables rapid curing of polymers without external heating since the polymerization process itself provides the high temperatures necessary to initiate and sustain polymerization. This process also enables more uniform curing of arbitrarily thick samples since it does not rely on heat transfer from an external source, which will necessarily cause the temperature history of the sample to vary with distance from the surface according to a diffusion-like process. Frontal polymerization also enables filling and sealing of structures having cavities of arbitrary shape without having to externally heat the structure. Water at atmospheric pressure is most convenient solvent to employ and the most important for practical applications (because of the cost and environmental issues associated with DMSO and other solvents). Nevertheless, to our knowledge, steady, self-propagating polymerization fronts have not been reported in water at atmospheric pressure. Currently, polymerization fronts require a high boiling point solvent (either water at high pressures or an alternative solvent such as dimethyl sulfoxide (DMSO) (boiling point 189 C at atmospheric pressure.) Early work on frontal polymerization, employed pressures up to 5000 atm in order to avoid boiling of the monomer/solvent/initiator solution. High

  14. A measurement of summertime dry deposition of ambient air particulates and associated metallic pollutants in Central Taiwan.

    PubMed

    Fang, Guor-Cheng; Chiang, Hung-Che; Chen, Yu-Cheng; Xiao, You-Fu; Wu, Chia-Ming; Kuo, Yu-Chen

    2015-04-01

    The purpose of this study is to characterize metallic elements associated with atmospheric particulate matter in the dry deposition plate, total suspended particulate, fine particles, and coarse particles at Taichung Harbor and Gong Ming Junior High School (airport) in central Taiwan at a sampling site from June 2013 to August 2013. The results indicated that: (1) the average concentrations of the metallic elements Cr and Cd were highest at the Gong Ming Junior High School (airport), and the average concentrations of the metallic elements Ni, Cu, and Pb were highest at the Taichung Harbor sampling site. (2) The high smelting industry density and export/import rate of heavily loaded cargos were the main reasons leading to these findings. (3) The average metallic element dry deposition and metallic element PM(2.5-10) all followed the order of Pb > Cr > Cu > Ni > Cd at the two sampling sites. However, the average metallic elements Cu and Pb were found to have the highest dry deposition velocities and concentrations in PM(2.5) for the two sampling sites in this study. (4) The correlation coefficients of ambient air particle dry deposition and concentration with wind speed at the airport were higher than those from the harbor sampling site. The wind and broad open spaces at Taichung Airport were the possible reasons for the increasing correlation coefficients for ambient air particle concentration and dry deposition with wind speed at the Taichung Airport sampling site. PMID:25185928

  15. Automated Measurements of Ambient Aerosol Chemical Composition and its Dry and Wet Size Distributions at Pittsburgh Supersite

    NASA Astrophysics Data System (ADS)

    Khlystov, A. Y.; Stanier, C.; Chun, W.; Vayenas, D.; Mandiro, M.; Pandis, S. N.

    2001-12-01

    Ambient aerosol particles change size with changes in ambient relative humidity. The magnitude of the size change depends on the hygroscopic properties of the particles, which is determined by their chemical composition. Hygroscopic properties of particles influence many environmentally important aerosol qualities, such as light scattering and partitioning between the gas and particle phases of semivolitile compounds. Studying the hygroscopic growth of ambient particles is thus of paramount importance. The highroscopic growth of ambient particles and their chemical composition are measured continuously within the Pittsburgh Air Quality Study (EPA supersite program). The hygroscopic size changes are measured using an automated system built for this study. The system consists of two Scanning Mobility Particle Sizers (SMPS, TSI Inc.) and an Aerodynamic Particle Sizer (APS, TSI Inc.). The three instruments measure aerosol size distribution between 5 nanometers and 10 micrometers in diameter. The inlets of the instruments and the sheath air lines of the SMPS systems are equipped with computer controlled valves that direct air through Nafion dryers (PermaPure Inc.) or bypass them. The Nafion dryers are drying the air stream below 40% RH at which point ambient particles are expected to lose most or all water and thus be virtually dry. To avoid changes in relative humidity and evaporation of volatile particles due to temperature differences the system is kept at ambient temperature. The system measures alternatively dry (below 40% RH) and wet (actual ambient RH) aerosol size distributions every 6 minutes. The hygroscopic growth observed with the size-spectrometer system is compared with theoretic predictions based on the chemical composition of aerosol particles. A modified semi-continuous Steam-Jet Aerosol Collector provides the total available budget (particles and gas) of water-soluble species, which is used as an input to the thermodynamic model. The model calculates

  16. Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2013-09-01

    Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ηbw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

  17. Selective hydrogen purification through graphdiyne under ambient temperature and pressure.

    PubMed

    Cranford, Steven W; Buehler, Markus J

    2012-08-01

    Graphdiyne, a recently synthesized one-atom-thick carbon allotrope, is atomistically porous - characterized by a regular "nanomesh"- and suggests application as a separation membrane for hydrogen purification. Here we report a full atomistic reactive molecular dynamics investigation to determine the selective diffusion properties of hydrogen (H(2)) amongst carbon monoxide (CO) and methane (CH(4)), a mixture otherwise known as syngas, a product of the gasification of renewable biomass (such as animal wastes). Under constant temperature simulations, we find the mass flux of hydrogen molecules through a graphdiyne membrane to be on the order of 7 to 10 g cm(-2) s(-1) (between 300 K and 500 K), with carbon monoxide and methane remaining isolated. Using a simple Arrhenius relation, we determine the energy required for permeation on the order of 0.11 ± 0.03 eV for single H(2) molecules. We find that addition of marginal applied force (approximately 1 to 2 pN per molecule, representing a controlled pressure gradient, ΔP, on the order of 100 to 500 kPa) can successfully enhance the separation of hydrogen gas. Addition of larger driving forces (50 to 100 pN per molecule) is required to selectively filter carbon monoxide or methane, suggesting that, under near-atmospheric conditions, only hydrogen gas will pass such a membrane. Graphdiyne provides a unique, chemically inert and mechanically stable platform facilitating selective gas separation at nominal pressures using a homogeneous material system, without a need for chemical functionalization or the explicit introduction of molecular pores. PMID:22706782

  18. Application of a dry-gas meter for measuring air sample volumes in an ambient air monitoring network

    SciTech Connect

    Fritz, Brad G.

    2009-05-24

    Ambient air monitoring for non-research applications (e.g. compliance) occurs at locations throughout the world. Often, the air sampling systems employed for these purposes employee simple yet robust equipment capable of handling the rigors of demanding sampling schedules. At the Hanford Site (near Richland, Washington) concentrations of radionuclides in ambient air are monitored continuously at 44 locations. In 2004, mechanical dry-gas meters were incorporated into the Hanford Site ambient air sample collection system to allow the direct measurement of sample volumes. These meters replaced a portable airflow measurement system that required two manual flow measurements and a sample duration measurement to determine sample volume. A six-month evaluation of the dry-gas meters compared sample volumes calculated using the original flow rate method to the direct sample volume measurement (new method). The results of the evaluation indicate that use of the dry-gas meters result in accurate sample volume measurements and provide greater confidence in the measured sample volumes. In several years of in-network use, the meters have proven to be reliable and have resulted in an improved sampling system.

  19. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

    SciTech Connect

    Newberg, John T. Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia; Åhlund, John

    2015-08-15

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N{sub 2}(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  20. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

    NASA Astrophysics Data System (ADS)

    Newberg, John T.; Åhlund, John; Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia

    2015-08-01

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N2(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  1. Role of ambient dielectric in propagation of Ar atmospheric pressure nonequilibrium plasma jets

    SciTech Connect

    Song, Jian; Wang, Youyin; Yu, Daren; Tang, Jingfeng Wei, Liqiu; Ren, Chunsheng

    2015-05-15

    A single-electrode atmospheric pressure nonequilibrium plasma jet surrounded with different ambient dielectrics is investigated driven by AC power supply. Another three ambient dielectrics, distilled water, ethanol, and carbon tetrachloride, are adopted to compare with air. By examining electrical and optical characteristics, it was found that the molecular polarity of ambient dielectrics had its significant effect on the propagation of atmospheric pressure nonequilibrium plasma jets. When the polarization of molecules was enhanced, the discharge current and the bullet velocity were also increased. For nonpolar dielectric of carbon tetrachloride, this was mainly resulted from the electron polarization in the built-in electric field. For polar dielectrics of ethanol and distilled water, in addition to the electron polarization, orientation polarization was the main cause for the further increase in discharge current and bullet velocity.

  2. Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films

    DOEpatents

    Brinker, Charles Jeffrey; Prakash, Sai Sivasankaran

    1999-01-01

    A method for preparing aerogel thin films by an ambient-pressure, continuous process. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

  3. Electron yield soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions

    PubMed Central

    Tamenori, Yusuke

    2013-01-01

    Ambient-pressure soft X-ray photoabsorption spectroscopy (XAS) was demonstrated to be applicable to the chemical analysis of hydrated transition-metal compounds. For this purpose, even under ambient-pressure conditions, electron yield detection XAS (EY-XAS), based on a simple drain-current set-up, was used to overcome a weakness in fluorescence yield detection XAS (FY-XAS), which does not give a pure soft XAS. The feasibility of EY-XAS was investigated and it was clarified that the EY-XAS under ambient-pressure conditions corresponds to the mixed data of the total EY and conversion EY spectra. Normal ambient-pressure EY-XAS analysis was applied to anhydrous (CoCl2) and to hydrated (CoCl2·6H2O) cobalt chloride at the Co L 23-edge. The present measurements demonstrated the ability to unambiguously distinguish the different chemical states of cobalt ions, relying upon spectral differences that indicate octahedral/quasi-octahedral structural changes as a result of hydration/dehydration reactions. PMID:23592620

  4. Squeeze-film damping of flexible microcantilevers at low ambient pressures.

    SciTech Connect

    Sumali, Anton Hartono; Lee, Jin Woo; Raman, Arvind

    2008-02-01

    The conclusions of this presentation are: (1) The quality factors of a microcantilever under squeeze-film damping effect were calculated experimentally and theoretically. (2) The quality factors decreased with ambient pressure, but increased with resonant mode number. (3) The proposed theoretical model predicts well the quality factors of higher bending modes of a microcantilever under squeeze-film damping effect.

  5. High-pressure stability and ambient metastability of marcasite-type rhodium pernitride

    NASA Astrophysics Data System (ADS)

    Niwa, K.; Terabe, T.; Suzuki, K.; Shirako, Y.; Hasegawa, M.

    2016-02-01

    High-pressure stability, ambient metastability, and high-pressure crystal chemistry of chemical bonds of marcasite-type RhN2 have been investigated using a laser-heated diamond-anvil cell up to a pressure of 70.6 GPa. High-pressure in-situ X-ray diffraction and Raman scattering measurements revealed that the marcasite-type RhN2 structure is stable up to 70.6 GPa and exhibited an order of axial compressibility of βc > βb > βa. This indicates that single bonded nitrogen dimer (N-N) plays an important role in the incompressibility of a- and b-axes than in that of the c-axis and stabilizes the marcasite-type structure at high-pressure. Field emission scanning electron microscopic analysis in combination with the energy dispersive X-ray spectroscopic measurements and the result of our previous study indicates that the marcasite-type RhN2 can be quenched to ambient pressure when the grain size is less than 100 nm. Our study together with other previous studies indicates that the ambient metastability of 4d platinum group pernitrides (RuN2, RhN2, and PdN2) decreases from ruthenium to palladium.

  6. The effect of ambient pressure on well chamber response: experimental results with empirical correction factors.

    PubMed

    Griffin, S L; DeWerd, L A; Micka, J A; Bohm, T D

    2005-03-01

    For some air-communicating well-type chambers used for low-energy brachytherapy source assay, deviations from expected values of measured air kerma strength were observed at low pressures associated with high altitudes. This effect is consistent with an overcompensation by the air density correction to standard atmospheric temperature and pressure (P(TP)). This work demonstrates that the P(TP) correction does not fully compensate for the high altitude pressure effects that are seen with air-communicating chambers at low photon energies in the range of 20-100 keV. Deviations of up to 18% at a pressure corresponding to an approximate elevation of 8500 ft for photon energies of 20 keV are possible. For high-energy photons and for high-energy beta emitters in air-communicating chambers the P(TP) factor is applicable. As expected, the ambient pressure does not significantly affect the response of pressurized well chambers (within 1%) to either low- or high-energy photons. However, when used with beta emitters, pressurized chambers appear to exhibit a slight dependence on the ambient pressure. Using measured data, the response and correction factors were determined for three models of air-communicating well chambers for low-energy photon sources at various pressures corresponding to elevations above sea level. Monte Carlo calculations were also performed which were correlated with the experimental findings. A more complete study of the Monte Carlo calculations is presented in the accompanying paper, "The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR1000 Plus." PMID:15839341

  7. Noninvasive Ambient Pressure Estimation using Ultrasound Contrast Agents -- Invoking Subharmonics for Cardiac and Hepatic Applications

    NASA Astrophysics Data System (ADS)

    Dave, Jaydev K.

    Ultrasound contrast agents (UCAs) are encapsulated microbubbles that provide a source for acoustic impedance mismatch with the blood, due to difference in compressibility between the gas contained within these microbubbles and the blood. When insonified by an ultrasound beam, these UCAs act as nonlinear scatterers and enhance the echoes of the incident pulse, resulting in scattering of the incident ultrasound beam and emission of fundamental (f0), subharmonic (f0/2), harmonic (n*f0; n ∈ N) and ultraharmonic (((2n-1)/2)*f0; n ∈ N & n > 1) components in the echo response. A promising approach to monitor in vivo pressures revolves around the fact that the ultrasound transmit and receive parameters can be selected to induce an ambient pressure amplitude dependent subharmonic signal. This subharmonic signal may be used to estimate ambient pressure amplitude; such technique of estimating ambient pressure amplitude is referred to as subharmonic aided pressure estimation or SHAPE. This project develops and evaluates the feasibility of SHAPE to noninvasively monitor cardiac and hepatic pressures (using commercially available ultrasound scanners and UCAs) because invasive catheter based pressure measurements are used currently for these applications. Invasive catheter based pressure measurements pose risk of introducing infection while the catheter is guided towards the region of interest in the body through a percutaneous incision, pose risk of death due to structural or mechanical failure of the catheter (which has also triggered product recalls by the USA Food and Drug Administration) and may potentially modulate the pressures that are being measured. Also, catheterization procedures require fluoroscopic guidance to advance the catheter to the site of pressure measurements and such catheterization procedures are not performed in all clinical centers. Thus, a noninvasive technique to obtain ambient pressure values without the catheterization process is clinically

  8. Measurement of thoracic gas volume by low-frequency ambient pressure changes.

    PubMed

    Peslin, R; Duvivier, C; Hannhart, B; Gallina, C

    1987-01-01

    When the whole body is exposed to sinusoidal variations of ambient pressure (delta Pam) at very low frequencies (f), the resulting compression and expansion of alveolar gas is almost entirely achieved by gas flow through the airways (Vaw). As a consequence thoracic gas volume (TGV) may be computed from the imaginary part (Im) of the delta Pam/Vaw relationship: TGV = PB/[2 pi f X Im(delta Pam/Vaw)], where PB is barometric minus alveolar water vapor pressure. The method was tested in 35 normal subjects and compared with body plethysmography. The subjects sat in a chamber connected to a large-stroke-volume reciprocating pump that brought about pressure swings of 40 cmH2O at 0.05 Hz. delta Pam and Vaw were digitally processed by fast Fourier transform to extract the low-frequency component from the much larger respiratory flow. Total lung capacities (TLC) obtained by ambient pressure changes and by plethylsmography were highly correlated (r = 0.959, p less than 0.001) and not significantly different (6.96 +/- 1.38 l vs. 6.99 +/- 1.38). TLC obtained by ambient pressure changes were not influenced by lowering the frequency to 0.03 Hz, adding an external resistance at the mouth, or increasing abdominal gas volume. We conclude that the method is practical and in agreement with body plethysmography in normal subjects. PMID:3558194

  9. Quantitative measurement of radiation pressure on a microcantilever in ambient environment

    SciTech Connect

    Ma, Dakang; Munday, Jeremy N.; Garrett, Joseph L.

    2015-03-02

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Micro/nano-mechanical transducers have become sensitive enough that radiation pressure can influence these systems. However, photothermal effects often accompany and overwhelm the radiation pressure, complicating its measurement. In this letter, we investigate the radiation force on an uncoated silicon nitride microcantilever in ambient conditions. We identify and separate the radiation pressure and photothermal forces through an analysis of the cantilever's frequency response. Further, by working in a regime where radiation pressure is dominant, we are able to accurately measure the radiation pressure. Experimental results are compared to theory and found to agree within the measured and calculated uncertainties.

  10. Development of a simple model for predicting the spark-induced bubble behavior under different ambient pressures

    NASA Astrophysics Data System (ADS)

    Zhang, L. C.; Zhu, X. L.; Huang, Y. F.; Liu, Z.; Yan, K.

    2016-07-01

    In this paper, a simple model was developed to predict the dynamics of a spark-induced bubble under different ambient pressures. This work helps in developing a deep-towed plasma sparker, as the model can predict the dynamics of bubbles subjected to very high ambient pressures (about 20 MPa) which normally are difficult to obtain experimentally. Experimental results indicate that the maximum bubble radius for a fixed discharge energy decreases as a power-law function of the ambient pressure up to 1.0 MPa; the bubble period also decreases quickly with increasing ambient pressure. For a constant value of the ratio of bubble energy to discharge energy, the modeling results for both maximum radius and bubble period are in good agreement with the experimental results. Both sets of results indicate that the bubble period is proportional to the maximum radius under different ambient pressures.

  11. Effects of concentrated ambient particles on heart rate and blood pressure in pulmonary hypertensive rats.

    PubMed Central

    Cheng, Tsun-Jen; Hwang, Jing-Shiang; Wang, Peng-Yau; Tsai, Chia-Fang; Chen, Chun-Yen; Lin, Sheng-Hsiang; Chan, Chang-Chuan

    2003-01-01

    Epidemiologic studies have shown that increased concentrations of ambient particles are associated with cardiovascular morbidity and mortality. However, the exact mechanisms remain unclear. Recent studies have revealed that particulate air pollution exposure is associated with indicators of autonomic function including heart rate, blood pressure, and heart rate variability. However, this association has not been clearly demonstrated in animal studies. To overcome the problems of wide variations in diseased animals and circadian cycles, we adopted a novel approach using a mixed-effects model to investigate whether ambient particle exposure was associated with changes in heart rate and blood pressure in pulmonary hypertensive rats. Male Sprague-Dawley rats were implanted with radiotelemetry devices and exposed to concentrated ambient particles generated by an air particle concentrator. The rats were held in nose-only exposure chambers for 6 hr per day for 3 consecutive days and then rested for 4 days in each week during the experimental period of 5 weeks. These animals were exposed to concentrated particles during weeks 2, 3, and 4 and exposed to filtered air during weeks 1 and 5. The particle concentrations for tested animals ranged between 108 and 338 micro g/m(3). Statistical analysis using mixed-effects models revealed that entry and exit of exposure chamber and particle exposure were associated with changes in heart rate and mean blood pressure. Immediately after particle exposure, the hourly averaged heart rate decreased and reached the lowest at the first and second hour of exposure for a decrease of 14.9 (p < 0.01) and 11.7 (p = 0.01) beats per minute, respectively. The hourly mean blood pressure also decreased after the particle exposure, with a maximal decrease of 3.3 (p < 0.01) and 4.1 (p < 0.01) mm Hg at the first and second hour of exposure. Our results indicate that ambient particles might influence blood pressure and heart rate. PMID:12573896

  12. Ignition experiment of a fuel droplet in high-pressure high-temperature ambient

    SciTech Connect

    Nakanishi, Ryota; Kobayashi, Hideaki; Kato, Shinichiro; Niioka, Takashi

    1994-12-31

    In order to obtain the ignition behavior at supercritical pressures, ignition times of a single fuel droplet were measured in high-pressure high-temperature ambient. A suspended droplet of n-hexadecane or n-heptane with a diameter of 0.35--1.4 min was quickly immersed in an electric furnace with a temperature up to 950 K. Attachment of the droplet, movement of the furnace, and ignition measurement were carried out in an air vessel with pressures up to 3 MPa. At low pressures, ignition times of both fuels decreased with the initial droplet diameter and then increased. Therefore, the ignition time variation with the initial droplet diameter has a minimum. This phenomenon, however, disappeared at high pressures. Also, the ignitable limit of droplet diameter, below which the droplet vaporized completely before ignition, decreased as pressure increased. In the case of a droplet burning at high pressures, the preceding experiment showed that the burning rate constant increased and had a maximum around the critical pressure of fuel. This is significantly caused by variable properties around the critical point such as thermal conductivity and diffusion coefficient; and therefore, the present ignition time was expected to show similar characteristics due to the same reason. Ignition time, however, decreased monotonously with pressure, and even at supercritical pressures, the ignition time behavior did not change much. Being different from the case of combustion, it is suggested that drastic changes of properties did not take place in ignition processes.

  13. Conceptual Demonstration of Ambient Desorption-Optical Emission Spectroscopy Using a Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Source.

    PubMed

    Marcus, R Kenneth; Paing, Htoo W; Zhang, Lynn X

    2016-06-01

    The concept of ambient desorption-optical emission spectroscopy (AD-OES) is demonstrated using a liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma as the desorption/excitation source. The LS-APGD has previously been employed for elemental analysis of solution samples and particulates introduced via laser ablation in both the optical emission and mass spectrometries (OES, MS) modes. In addition, the device has been shown to be effective for the analysis of elemental and molecular species operating in an ambient desorption/ionization mass spectrometry (ADI-MS) mode. Proof-of-concept is presented here in the use of the LS-APGD to volatilize three very diverse sample forms (metallic thin films, dry solution residues, and bulk materials), with the liberated material excited within the microplasma and detected via OES, i.e., AD-OES. While the demonstration is principally qualitative at this point, it is believed that the basic approach may find application across a broad spectrum of analytical challenges requiring elemental analysis, including metals, soils, and volume-limited solutions, analogous to what has been seen in the development of the field of ADI-MS for molecular species determinations. PMID:27175512

  14. The effect of ambient pressure on the evaporation rate of materials

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.; Russell, W. M.

    1972-01-01

    A simple expression is obtained using a diffusion model for the effect of ambient pressure on the outgassing or evaporation rate of materials. The correctness of the expression is demonstrated by comparing the estimates from this expression with actual weight loss measurements. It is shown that the rate of mass loss is governed by the ratio of mean free path to the characteristic dimension of the surface in question.

  15. Effect of ambient pressure variation on closed loop gas system for India based Neutrino Observatory (INO)

    NASA Astrophysics Data System (ADS)

    Satyanarayana, B.; Majumder, G.; Mondal, N. K.; Kalmani, S. D.; Shinde, R. R.; Joshi, A.

    2014-10-01

    Pilot unit of a closed loop gas mixing and distribution system for the INO project was designed and is being operated with 1.8meters × 1.9meters RPCs for about two years. A number of studies on controlling the flow and optimisation of the gas mixture through the RPC stack were carried out during this period. The gas system essentially measures and attempts to maintain absolute pressure inside the RPC gas volume. During typical Mumbai monsoon seasons, the barometric pressure changes rather rapidly, due to which the gas system fails to maintain the set differential pressure between the ambience and the RPC gas volume. As the safety bubblers on the RPC gas input lines are set to work on fixed pressure differentials, the ambient pressure changes lead to either venting out and thus wasting gas through safety bubblers or over pressuring the RPCs gas volume and thus degrading its performance. The above problem also leads to gas mixture contamination through minute leaks in gas gap. The problem stated above was solved by including the ambient barometric pressure as an input parameter in the closed loop. Using this, it is now possible to maintain any set differential pressure between the ambience and RPC gas volumes between 0 to 20mm of water column, thus always ensuring a positive pressure inside the RPC gas volume with respect to the ambience. This has resulted in improved performance of the gas system by maintaining the constant gas flow and reducing the gas toping up frequency. In this paper, we will highlight the design features and improvements of the closed loop gas system. We will present some of the performance studies and considerations for scaling up the system to be used with the engineering module and then followed by Iron Calorimeter detector (ICAL), which is designed to deploy about 30,000 RPCs of 1.8meters × 1.9 meters in area.

  16. Optical properties of Bi2Te2Se at ambient and high pressures

    NASA Astrophysics Data System (ADS)

    Akrap, Ana; Tran, Michaël; Ubaldini, Alberto; Teyssier, Jérémie; Giannini, Enrico; van der Marel, Dirk; Lerch, Philippe; Homes, Christopher C.

    2012-12-01

    The temperature dependence of the complex optical properties of the three-dimensional topological insulator Bi2Te2Se is reported for light polarized in the a-b planes at ambient pressure, as well as the effects of pressure at room temperature. This material displays a semiconducting character with a bulk optical gap of Eg≃300 meV at 295 K. In addition to the two expected infrared-active vibrations observed in the planes, there is an additional fine structure that is attributed to either the removal of degeneracy or the activation of Raman modes due to disorder. A strong impurity band located at ≃200 cm-1 is also observed. At and just above the optical gap, several interband absorptions are found to show a strong temperature and pressure dependence. As the temperature is lowered these features increase in strength and harden. The application of pressure leads to a very abrupt closing of the gap above 8 GPa, and strongly modifies the interband absorptions in the midinfrared spectral range. While ab initio calculations fail to predict the collapse of the gap, they do successfully describe the size of the band gap at ambient pressure, and the magnitude and shape of the optical conductivity.

  17. Dynamic High Pressure: a novel approach toward near ambient pressure photoemission spectroscopy and spectromicroscopy

    NASA Astrophysics Data System (ADS)

    Amati, M.; Kazemian Abyaneh, M.; Gregoratti, L.

    2013-05-01

    A Dynamic High Pressure (DHP) system has been developed, tested and implemented in the scanning photoelectron microscope (SPEM) operated at ESCAmicroscopy beamline at Elettra synchrotron. The system consists of a compact gas injection set up that allows experiments with local pressure near the sample several orders of magnitude higher that the allowable pressure for X-ray photoelectron spectroscopy setups. The DHP setup controls the amount of gas injected toward the sample by fine tuning the time and spatial profiles using a pulsed valve and a nozzle, respectively. The DHP functionality and effectiveness has been demonstrated by in operando oxidation experiments of Ru and Si. The obtained results confirmed that using the DHP the gas exposure onto the sample is equivalent to a static pressure between 10-3 and 10-2 mbar, about 3 orders of magnitude higher than the maximum gas pressure for the XPS machines under operation.

  18. Effect of ambient temperature and sodium bicarbonate supplementation on water and electrolyte balances in dry and lactating Holstein cows.

    PubMed

    Khelil-Arfa, H; Faverdin, P; Boudon, A

    2014-01-01

    The aim of this study was to quantify the effect of the interaction between 2 constant ambient temperatures [thermoneutrality (TN; 15°C) and high temperature (HT; 28°C)] and 2 levels of Na bicarbonate supplementation [calculated to provide diet Na contents of 0.20%DM (Na-) and 0.50%DM (Na+)] on water partitioning in dairy cows. Treatments were compared on 4 dry and 4mid-lactation Holstein cows according to 2 Latin squares (1 for each physiological stage) over the course of 4 periods of 15d. Diets consisted of a total mixed ration based on maize silage. Dry cows were restricted to their protein and energy requirements, whereas lactating cows were fed ad libitum. The daily average temperature-humidity index was 59.4 for TN and 73.2 for HT. Lactating and dry cows had higher vaginal temperatures at HT than at TN, but the increase was more pronounced in lactating cows (+1.05 vs. +0.12°C for vaginal temperature, respectively). Dry matter intake (DMI) of lactating cows decreased by 2.3kg/d at HT. Free water intake (FWI) and estimated volume of water lost to evaporation increased at HT in both lactating and dry cows; no interactions were observed between temperature and physiological stage. When expressed as a proportion of DMI, the increase in evaporation that occurred with increasing temperature was completely compensated for by an increase in FWI for both physiological stages. The urinary water excretion increased slightly at HT in lactating cows but not in dry cows, which may be related to the low chloride content of the offered diet. High Na supplementation increased DMI slightly in lactating cows, but milk yield was not affected. Sodium supplementation did not limit the decrease in DMI observed in lactating cows at HT; this observation is likely due to the high diet electrolyte balance of the offered diets. Sodium supplementation increased FWI in lactating cows and urinary flow in both physiological states. The interaction between ambient temperature and Na

  19. The Effect of Argon Ambient Pressure and Annealing Time on Bulk MgB2 Superconductor

    NASA Astrophysics Data System (ADS)

    Erdem, Murat; Ozturk, Ozgur; Asikuzun, Elif; Kaya, Seydanur; Safran, Serap; Kilic, Ahmet; Terzioglu, Cabir

    2015-03-01

    The effects of Ar ambient pressure (vacuum, 0B, 10B and 20B) and annealing times (0.5 h and 1 h) on microstructural, superconducting and mechanical properties of bulk superconducting MgB2 are investigated. The samples are produced using the solid state reaction method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements were performed for determination of the crystal structure, and surface morphology of MgB2 samples, respectively. The superconducting properties were studied by AC magnetic susceptibility and DC resistivity measurements. Increasing the Ar pressure decreased the lattice parameters and hence the average grain size. Increasing the annealing time results in larger lattice parameters and larger grain formation. The susceptibility measurements revealed two step transition which is reminiscent of granular superconductors. The intra-grain transition temperature is determined to be 38.4 K for all samples. The inter-grain transition temperatures of 37.2 K is obtained for samples produced under Ar ambient. The samples produced under Ar ambient have better superconducting properties than the ones produced in vacuum. Increasing the annealing time under vacuum further decreases the superconducting properties probably due to Mg loss. This research is supported by Kastamonu University Scientific Research Projects Coordination Department under the Grant No. KUBAP-03/2012-03.

  20. Collaborative Processing of Wearable and Ambient Sensor System for Blood Pressure Monitoring

    PubMed Central

    Nakamura, Masayuki; Nakamura, Jiro; Lopez, Guillaume; Shuzo, Masaki; Yamada, Ichiro

    2011-01-01

    This paper describes wireless wearable and ambient sensors that cooperate to monitor a person’s vital signs such as heart rate and blood pressure during daily activities. Each wearable sensor is attached on different parts of the body. The wearable sensors require a high sampling rate and time synchronization to provide a precise analysis of the received signals. The trigger signal for synchronization is provided by the ambient sensors, which detect the user’s presence. The Bluetooth and IEEE 802.15.4 wireless technologies are used for real-time sensing and time synchronization. Thus, this wearable health-monitoring sensor response is closely related to the context in which it is being used. Experimental results indicate that the system simultaneously provides information about the user’s location and vital signs, and the synchronized wearable sensors successfully measures vital signs with a 1 ms resolution. PMID:22163984

  1. Water Dynamics in Shewanella oneidensis at Ambient and High Pressure using Quasi-Elastic Neutron Scattering

    PubMed Central

    Foglia, Fabrizia; Hazael, Rachael; Simeoni, Giovanna G.; Appavou, Marie-Sousai; Moulin, Martine; Haertlein, Michael; Trevor Forsyth, V.; Seydel, Tilo; Daniel, Isabelle; Meersman, Filip; McMillan, Paul F.

    2016-01-01

    Quasielastic neutron scattering (QENS) is an ideal technique for studying water transport and relaxation dynamics at pico- to nanosecond timescales and at length scales relevant to cellular dimensions. Studies of high pressure dynamic effects in live organisms are needed to understand Earth’s deep biosphere and biotechnology applications. Here we applied QENS to study water transport in Shewanella oneidensis at ambient (0.1 MPa) and high (200 MPa) pressure using H/D isotopic contrast experiments for normal and perdeuterated bacteria and buffer solutions to distinguish intracellular and transmembrane processes. The results indicate that intracellular water dynamics are comparable with bulk diffusion rates in aqueous fluids at ambient conditions but a significant reduction occurs in high pressure mobility. We interpret this as due to enhanced interactions with macromolecules in the nanoconfined environment. Overall diffusion rates across the cell envelope also occur at similar rates but unexpected narrowing of the QENS signal appears between momentum transfer values Q = 0.7–1.1 Å−1 corresponding to real space dimensions of 6–9 Å. The relaxation time increase can be explained by correlated dynamics of molecules passing through Aquaporin water transport complexes located within the inner or outer membrane structures. PMID:26738409

  2. Water Dynamics in Shewanella oneidensis at Ambient and High Pressure using Quasi-Elastic Neutron Scattering.

    PubMed

    Foglia, Fabrizia; Hazael, Rachael; Simeoni, Giovanna G; Appavou, Marie-Sousai; Moulin, Martine; Haertlein, Michael; Trevor Forsyth, V; Seydel, Tilo; Daniel, Isabelle; Meersman, Filip; McMillan, Paul F

    2016-01-01

    Quasielastic neutron scattering (QENS) is an ideal technique for studying water transport and relaxation dynamics at pico- to nanosecond timescales and at length scales relevant to cellular dimensions. Studies of high pressure dynamic effects in live organisms are needed to understand Earth's deep biosphere and biotechnology applications. Here we applied QENS to study water transport in Shewanella oneidensis at ambient (0.1 MPa) and high (200 MPa) pressure using H/D isotopic contrast experiments for normal and perdeuterated bacteria and buffer solutions to distinguish intracellular and transmembrane processes. The results indicate that intracellular water dynamics are comparable with bulk diffusion rates in aqueous fluids at ambient conditions but a significant reduction occurs in high pressure mobility. We interpret this as due to enhanced interactions with macromolecules in the nanoconfined environment. Overall diffusion rates across the cell envelope also occur at similar rates but unexpected narrowing of the QENS signal appears between momentum transfer values Q = 0.7-1.1 Å(-1) corresponding to real space dimensions of 6-9 Å. The relaxation time increase can be explained by correlated dynamics of molecules passing through Aquaporin water transport complexes located within the inner or outer membrane structures. PMID:26738409

  3. Water Dynamics in Shewanella oneidensis at Ambient and High Pressure using Quasi-Elastic Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Foglia, Fabrizia; Hazael, Rachael; Simeoni, Giovanna G.; Appavou, Marie-Sousai; Moulin, Martine; Haertlein, Michael; Trevor Forsyth, V.; Seydel, Tilo; Daniel, Isabelle; Meersman, Filip; McMillan, Paul F.

    2016-01-01

    Quasielastic neutron scattering (QENS) is an ideal technique for studying water transport and relaxation dynamics at pico- to nanosecond timescales and at length scales relevant to cellular dimensions. Studies of high pressure dynamic effects in live organisms are needed to understand Earth’s deep biosphere and biotechnology applications. Here we applied QENS to study water transport in Shewanella oneidensis at ambient (0.1 MPa) and high (200 MPa) pressure using H/D isotopic contrast experiments for normal and perdeuterated bacteria and buffer solutions to distinguish intracellular and transmembrane processes. The results indicate that intracellular water dynamics are comparable with bulk diffusion rates in aqueous fluids at ambient conditions but a significant reduction occurs in high pressure mobility. We interpret this as due to enhanced interactions with macromolecules in the nanoconfined environment. Overall diffusion rates across the cell envelope also occur at similar rates but unexpected narrowing of the QENS signal appears between momentum transfer values Q = 0.7-1.1 Å-1 corresponding to real space dimensions of 6-9 Å. The relaxation time increase can be explained by correlated dynamics of molecules passing through Aquaporin water transport complexes located within the inner or outer membrane structures.

  4. The Orion Atmosphere Revitalization Technology in Manned Ambient Pressure Space Suit Testing

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlitsch, Jeffrey

    2011-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System (ARS) for moderate duration missions of the Orion Multipurpose Crew Vehicle. The Orion ARS is designed to support not only open-cabin operations, tests of which have been reported in previous years at this conference, but also closed space suit-loop operations. A previous low-pressure suit loop test was performed with a human metabolic simulator, and humans wearing emergency masks were tested in a closed-loop configuration before that. In late 2011, simple tests were performed in a suit-loop configuration with human test subjects in prototype space suits with prototype umbilicals at ambient and two slightly above-ambient pressures. Trace contaminant filters and a prototype blower were also incorporated into the test rig. This paper discusses the performance of the ARS technology in that 2011 test configuration.

  5. Ambient pressure laser desorption and laser-induced acoustic desorption ion mobility spectrometry detection of explosives.

    PubMed

    Ehlert, Sven; Walte, Andreas; Zimmermann, Ralf

    2013-11-19

    The development of fast, mobile, and sensitive detection systems for security-relevant substances is of enormous importance. Because of the low vapor pressures of explosives and improvised explosive devices, adequate sampling procedures are crucial. Ion mobility spectrometers (IMSs) are fast and sensitive instruments that are used as detection systems for explosives. Ambient pressure laser desorption (APLD) and ambient pressure laser-induced acoustic desorption (AP-LIAD) are new tools suitable to evaporate explosives in order to detect them in the vapor phase. Indeed, the most important advantage of APLD or AP-LIAD is the capability to sample directly from the surface of interest without any transfer of the analyte to other surfaces such as wipe pads. A much more gentle desorption, compared to classical thermal-based desorption, is possible with laser-based desorption using very short laser pulses. With this approach the analyte molecules are evaporated in a very fast process, comparable to a shock wave. The thermal intake is reduced considerably. The functionality of APLD and AP-LIAD techniques combined with a hand-held IMS system is shown for a wide range of common explosives such as EGDN (ethylene glycol dinitrate), urea nitrate, PETN (pentaerythritol tetranitrate), HMTD (hexamethylene triperoxide diamine), RDX (hexogen), tetryl (2,4,6-trinitrophenylmethylnitramine), and TNT (trinitrotoluene). Detection limits down to the low nanogram range are obtained. The successful combination of IMS detection and APLD/AP-LIAD sampling is shown. PMID:24116702

  6. Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2015-09-01

    In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

  7. Study of emissivity changes presented by inorganic and organic soil under drying at ambient temperature

    NASA Astrophysics Data System (ADS)

    Villaseñor-Mora, C.; Gonzalez-Vega, A.; Martinez-Torres, P.; Hernández-Arellano, H.

    2015-09-01

    Thermal emissivity can be used to determine the moisture content in soils, but it is strongly influenced by the kind of soil and the organic matter content. These experiments were performed by recording infrared images of the wet soils as a function of water loss. Samples with different organic matter content were wet until reach the field capacity; then, a sequence of thermal images was acquired to follow the different stages of drying process of the studied samples. The emissivity was calculated indirectly by measuring the reflection and absorption of the samples.

  8. Synthesis of Ultra-Incompressible Superhard Rhenium Diboride at Ambient Pressure

    SciTech Connect

    Chung,H.; Weinberger, M.; Levine, J.; Kavner, A.; Yang, J.; Tolbert, S.; Kaner, R.

    2007-01-01

    The quest to create superhard materials rarely strays from the use of high-pressure synthetic methods, which typically require gigapascals of applied pressure. We report that rhenium diboride (ReB{sub 2}), synthesized in bulk quantities via arc-melting under ambient pressure, rivals materials produced with high-pressure methods. Microindentation measurements on ReB{sub 2} indicated an average hardness of 48 gigapascals under an applied load of 0.49 newton, and scratch marks left on a diamond surface confirmed its superhard nature. Its incompressibility along the c axis was equal in magnitude to the linear incompressibility of diamond. In situ high-pressure x-ray diffraction measurements yielded a bulk modulus of 360 gigapascals, and radial diffraction indicated that ReB{sub 2} is able to support a remarkably high differential stress. This combination of properties suggests that this material may find applications in cutting when the formation of carbides prevents the use of traditional materials such as diamond.

  9. High-pressure, ambient temperature hydrogen storage in metal-organic frameworks and porous carbon

    NASA Astrophysics Data System (ADS)

    Beckner, Matthew; Dailly, Anne

    2014-03-01

    We investigated hydrogen storage in micro-porous adsorbents at ambient temperature and pressures up to 320 bar. We measured three benchmark adsorbents: two metal-organic frameworks, Cu3(1,3,5-benzenetricarboxylate)2 [Cu3(btc)2; HKUST-1] and Zn4O(1,3,5-benzenetribenzoate)2 [Zn4O(btb)2; MOF-177], and the activated carbon MSC-30. In this talk, we focus on adsorption enthalpy calculations using a single adsorption isotherm. We use the differential form of the Claussius-Clapeyron equation applied to the Dubinin-Astakhov adsorption model to calculate adsorption enthalpies. Calculation of the adsorption enthalpy in this way gives a temperature independent enthalpy of 5-7 kJ/mol at the lowest coverage for the three materials investigated. Additionally, we discuss the assumptions and corrections that must be made when calculating adsorption isotherms at high-pressure and adsorption enthalpies.

  10. Dissociative Carbon Dioxide Adsorption and Morphological Changes on Cu(100) and Cu(111) at Ambient Pressures.

    PubMed

    Eren, Baran; Weatherup, Robert S; Liakakos, Nikos; Somorjai, Gabor A; Salmeron, Miquel

    2016-07-01

    Ambient-pressure X-ray photoelectron spectroscopy (APXPS) and high-pressure scanning tunneling microscopy (HPSTM) were used to study the structure and chemistry of model Cu(100) and Cu(111) catalyst surfaces in the adsorption and dissociation of CO2. It was found that the (100) face is more active in dissociating CO2 than the (111) face. Atomic oxygen formed after the dissociation of CO2 poisons the surface by blocking further adsorption of CO2. This "self-poisoning" mechanism explains the need to mix CO into the industrial feed for methanol production from CO2, as it scavenges the chemisorbed O. The HPSTM images show that the (100) surface breaks up into nanoclusters in the presence of CO2 at 20 Torr and above, producing active kink and step sites. If the surface is precovered with atomic oxygen, no such nanoclustering occurs. PMID:27280375

  11. Emission dynamics of an expanding ultrafast-laser produced Zn plasma under different ambient pressures

    SciTech Connect

    Smijesh, N.; Philip, Reji

    2013-09-07

    We report time and space resolved spectral measurements of neutral Zn emission from an ultrafast laser produced plasma, generated by the irradiation of a Zn target with laser pulses of 100 femtoseconds duration, carried out in a broad ambient pressure range of 0.05 to 100 Torr. The measurement is done for three different axial positions in the expanding plume. The spectra are rich in neutral Zn (Zn I) emissions at 334.5 nm, 468 nm, 472 nm, 481 nm, and 636 nm, respectively, depicting the characteristic triplet structure of Zn. Fast as well as slow peaks are observed in the time of flight data of 481 nm emission, which arise from recombination and atomic contributions, respectively, occurring at different time scales. Average speeds of the fast atomic species do not change appreciably with ambient pressure. The plasma parameters (electron temperature and number density) are evaluated from the measured optical emission spectra. The rates of ionization and recombination can be enhanced by a double-pulse excitation configuration in which optical energy is coupled to the ultrafast plasma through a delayed laser pulse.

  12. A versatile instrument for ambient pressure x-ray photoelectron spectroscopy: The Lund cell approach

    NASA Astrophysics Data System (ADS)

    Knudsen, Jan; Andersen, Jesper N.; Schnadt, Joachim

    2016-04-01

    During the past one and a half decades ambient pressure x-ray photoelectron spectroscopy (APXPS) has grown to become a mature technique for the real-time investigation of both solid and liquid surfaces in the presence of a gas or vapour phase. APXPS has been or is being implemented at most major synchrotron radiation facilities and in quite a large number of home laboratories. While most APXPS instruments operate using a standard vacuum chamber as the sample environment, more recently new instruments have been developed which focus on the possibility of custom-designed sample environments with exchangeable ambient pressure cells (AP cells). A particular kind of AP cell solution has been driven by the development of the APXPS instrument for the SPECIES beamline of the MAX IV Laboratory: the solution makes use of a moveable AP cell which for APXPS measurements is docked to the electron energy analyser inside the ultrahigh vacuum instrument. Only the inner volume of the AP cell is filled with gas, while the surrounding vacuum chamber remains under vacuum conditions. The design enables the direct connection of UHV experiments to APXPS experiments, and the swift exchange of AP cells allows different custom-designed sample environments. Moreover, the AP cell design allows the gas-filled inner volume to remain small, which is highly beneficial for experiments in which fast gas exchange is required. Here we report on the design of several AP cells and use a number of cases to exemplify the utility of our approach.

  13. Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

    SciTech Connect

    Newberg, John T.; Bluhm, Hendrik

    2015-08-18

    The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10-5 to 2 × 10-3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 103 Torr-1. The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.

  14. Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

    DOE PAGESBeta

    Newberg, John T.; Bluhm, Hendrik

    2015-08-18

    The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10-5 to 2 × 10-3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partialmore » pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 103 Torr-1. The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.« less

  15. Ambient pressure effects on the sputter particle distribution of insulating materials

    SciTech Connect

    Glaser, J.W.

    1985-07-01

    The effect of ion bombardment on several grades of alumina was investigated. Changes in the electrical resistance of the substrate as a function of incoming ion energy were of particular interest. Attention was also paid to the sputter particle distribution as a function of ambient pressure. This distribution was found to be dependent on the ion to substrate mass ratio. In general, the distribution follows a curve of growth; approximating a cosine distribution at the lower pressures and mass ratio, becoming isotropic at higher pressures. Pressures in the range of 10/sup -2/ to 10/sup -4/ Pascals have been used along with mass ratios in the range of 0.40 to 1.3. Samples of up to 80 cm/sup 2/ were subjected to a 10 cm diameter ion beam at energies of up to 6.25 keV. Average ion current densities of 1ma/cm/sup 2/ were used. Substrate temperatures while subjected to the ion beam were also monitored.

  16. Lung diffusing capacity for nitric oxide at lowered and raised ambient pressures.

    PubMed

    Linnarsson, Dag; Hemmingsson, Tryggve E; Frostell, Claes; Van Muylem, Alain; Kerckx, Yannick; Gustafsson, Lars E

    2013-12-01

    Lung diffusing capacity for NO (DLNO) was determined in eight subjects at ambient pressures of 505, 1015, and 4053hPa (379, 761 and 3040mmHg) as they breathed normoxic gases. Mean values were 116.9±11.1 (SEM), 113.4±11.1 and 99.3±10.1mlmin(-1)hPa(-1)at 505, 1015, and 4053hPa, with a 13% difference between the two higher pressures (P=0.017). The data were applied to a model with two serially coupled conductances; the gas phase (DgNO, variable with pressure), and the alveolo-capillary membrane (DmNO, constant). The data fitted the model well and we conclude that diffusive transport of NO in the peripheral lung is inversely related to gas density. At normal pressure DmNO was approximately 5% larger than DLNO, suggesting that the Dg factor then is not negligible. We also conclude that the density of the breathing gas is likely to impact the backdiffusion of naturally formed NO from conducting airways to the alveoli. PMID:24004985

  17. Pressure induced ionic-superionic transition in silver iodide at ambient temperature

    NASA Astrophysics Data System (ADS)

    Han, Y. H.; Wang, H. B.; Troyan, I. A.; Gao, C. X.; Eremets, M. I.

    2014-01-01

    Silver iodide (AgI-V) is an archetypical ionic compound for studying the formation mechanism of a superionic state. Previous studies have proven that superionic AgI with high ionic conductivity greater than 0.1 Ω-1cm-1 could only be obtained at high temperatures. We show in this paper that high pressure could also induce the superionic state in AgI even at ambient temperature. Using electrochemical impedance spectroscopy, we investigated Ag+ ions diffusing in rock-salt structured AgI-III and KOH-type AgI-V under high pressures and directly observed the superionic state in AgI-V. The diffusion coefficient of AgI-V is ˜3.4 × 10-4-8.6 × 10-4 cm2/s in the investigated pressure range of 12-17 GPa, comparable with those of superionic α-AgI and AgI-III'. By analyzing the half infinite length Warburg diffusion process, two parameters α and β, which closely relate to the disordered state of Ag+ ions, have been determined and it was suggested that Ag+ ions in AgI-V become disordered. The ionic conductivity of AgI-V is three orders of magnitude higher than that of AgI-III, and has reached around 0.1 Ω-1cm-1. Evidence for all three, the diffusion coefficient, α and β, and conductivity have proven that AgI-V is a superionic conductor at ambient temperature.

  18. Pressure induced ionic-superionic transition in silver iodide at ambient temperature.

    PubMed

    Han, Y H; Wang, H B; Troyan, I A; Gao, C X; Eremets, M I

    2014-01-28

    Silver iodide (AgI-V) is an archetypical ionic compound for studying the formation mechanism of a superionic state. Previous studies have proven that superionic AgI with high ionic conductivity greater than 0.1 Ω(-1)cm(-1) could only be obtained at high temperatures. We show in this paper that high pressure could also induce the superionic state in AgI even at ambient temperature. Using electrochemical impedance spectroscopy, we investigated Ag(+) ions diffusing in rock-salt structured AgI-III and KOH-type AgI-V under high pressures and directly observed the superionic state in AgI-V. The diffusion coefficient of AgI-V is ∼3.4 × 10(-4)-8.6 × 10(-4) cm(2)/s in the investigated pressure range of 12-17 GPa, comparable with those of superionic α-AgI and AgI-III'. By analyzing the half infinite length Warburg diffusion process, two parameters α and β, which closely relate to the disordered state of Ag(+) ions, have been determined and it was suggested that Ag(+) ions in AgI-V become disordered. The ionic conductivity of AgI-V is three orders of magnitude higher than that of AgI-III, and has reached around 0.1 Ω(-1)cm(-1). Evidence for all three, the diffusion coefficient, α and β, and conductivity have proven that AgI-V is a superionic conductor at ambient temperature. PMID:25669568

  19. Ambient Pressure Test Rig Developed for Testing Oil-Free Bearings in Alternate Gases and Variable Pressures

    NASA Technical Reports Server (NTRS)

    Bauman, Steven W.

    1990-01-01

    The Oil-Free Turbomachinery research team at the NASA Glenn Research Center is conducting research to develop turbomachinery systems that utilize high-speed, high temperature foil (air) bearings that do not require an oil lubrication system. Such systems combine the most advanced foil bearings from industry with NASA-developed hightemperature solid-lubricant technology. New applications are being pursued, such as Oil- Free turbochargers, auxiliary power units, and turbine propulsion systems for aircraft. An Oil-Free business jet engine, for example, would be simpler, lighter, more reliable, and less costly to purchase and maintain than current engines. Another application is NASA's Prometheus mission, where gas bearings will be required for the closed-cycle turbine based power-conversion system of a nuclear power generator for deep space. To support these applications, Glenn's Oil-Free Turbomachinery research team developed the Ambient Pressure Test Rig. Using this facility, researchers can load and heat a bearing and evaluate its performance with reduced air pressure to simulate high altitude conditions. For the nuclear application, the test chamber can be purged with gases such as helium to study foil gas bearing operation in working fluids other than air.

  20. 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...

  1. Formation of Hydroxyl and Water Layers on MgO Films Studied with Ambient Pressure XPS

    SciTech Connect

    Newberg, J.T.; Starr, D.; Yamamoto, S.; Kaya, S.; Kendelewicz, T.; Mysak, E.R.; Porsgaard, S.; Salmeron, M.B.; Brown Jr., G.E.; Nilsson, A.; Bluhm, H.

    2011-01-01

    To understand the interaction of water with MgO(100), a detailed quantitative assessment of the interfacial chemistry is necessary. We have used ambient pressure X-ray photoelectron spectroscopy (XPS) to measure molecular (H{sub 2}O) and dissociative (OH) water adsorption on a 4 monolayer (ML) thick MgO(100)/Ag(100) film under ambient conditions. Since the entire 4 ML metal oxide (Ox) film is probed by XPS, the reaction of the MgO film with water can be quantitatively studied. Using a multilayer model (Model 1) that measures changes in Ox thickness from O 1s (film) and Ag 3d (substrate) spectra, it is shown that the oxide portion of the MgO film becomes thinner upon hydroxylation. A reaction mechanism is postulated in which the top-most layer of MgO converts to Mg(OH)2 upon dissociation of water. Based on this mechanism a second model (Model 2) is developed to calculate Ox and OH thickness changes based on OH/Ox intensity ratios from O 1s spectra measured in situ, with the known initial Ox thickness prior to hydroxylation. Models 1 and 2 are applied to a 0.15 Torr isobar experiment, yielding similar results for H{sub 2}O, OH and Ox thickness changes as a function of relative humidity.

  2. Small Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

    NASA Technical Reports Server (NTRS)

    Broerman, Craig; Sweterlitsch, Jeffrey

    2011-01-01

    A principle concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has long been evaluated for use in this application and several programs are evaluating it for use in both a cabin as well as space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of small scale SA9T testing that was performed over a variety of test conditions and with a variety of trace contaminants. Testing evaluated the ability of SA9T media to sufficiently remove CO2 and H2O after exposure to a fully saturated trace contaminant at ambient conditions. Testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures during cyclic operation with a constant inlet contaminant load. In addition, testing evaluated the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream.

  3. Bench-Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

    NASA Technical Reports Server (NTRS)

    Broerman, Craig; Sweterlitsch, Jeff

    2011-01-01

    A principal concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has been evaluated for use in this application and several programs are evaluating it for use in both cabin and space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of bench-scale SA9T testing that was performed under a variety of test conditions and with several different trace contaminants. Tests were conducted to determine if the capacity of the SA9T media to sufficiently remove CO2 and H2O is compromised after exposure to a fully saturated trace contaminant at ambient conditions. Tests also were conducted to evaluate the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream. In addition, testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures (29.6 KPa/4.3 psia) during cyclic operation with a constant inlet contaminant load.

  4. Reaction of Small Insects to an Ambient Pressure Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Bures, Brian; Gray, Travis; Bourham, Mohamed; Roe, R. Michael; Long, Shengyou; Donohue, Kevin

    2003-10-01

    Ambient Pressure Dielectric Barrier Discharges (DBD's) are commonly studied for rapid sterilization of surfaces. In an effort to expand the application of DBD's to larger biological species, small insect species are directly exposed to a large gap(5 cm) DBD composed primarily of helium gas. In order to control the temperature, the electrodes are actively cooled and the current density remains low (<1 mA/cm^2). A direct measurement of the gas temperature by electrically insulated thermocouples shows that the ambient temperature in the discharge volume is below the threshold for thermal damage to the insect (40 ^oC). A microwave interferometer is used to measure the line average, time average, electron density. The electron density is between 10^8 and 10^10 cm-3 for the operating conditions of interest. Under these operating conditions, optical emission spectroscopy shows only a significant emission of helium lines with some emission of molecular nitrogen lines. Under these operational conditions green peach aphids and western flower thrips show a reduction in population by at least 50% with a 60 s exposure time. The goal of this research is to replace currently existing chemical and thermal insect control techniques with the more rapid plasma techniques for quarantine applications.

  5. The effect of ambient pressure on ejecta sheets from free-surface ablation

    NASA Astrophysics Data System (ADS)

    Marston, J. O.; Mansoor, M. M.; Thoroddsen, S. T.; Truscott, T. T.

    2016-05-01

    We present observations from an experimental study of the ablation of a free liquid surface promoted by a focused laser pulse, causing a rapid discharge of liquid in the form of a very thin conical-shaped sheet. In order to capture the dynamics, we employ a state-of-the-art ultra-high-speed video camera capable of capturing events at 5 × 106 fps with shutter speeds down to 20 ns, whereby we were able to capture not only the ejecta sheet, but also the shock wave, emerging at speeds of up to 1.75 km/s, which is thus found to be hypersonic (Mach 5). Experiments were performed at a range of ambient pressures in order to study the effect of air drag on the evolution of the sheet, which was always observed to dome over, even at pressures as low as 3.8 kPa. At reduced pressures, the extended sheet evolution led to the formation of interference fringe patterns from which, by comparison with the opening speed of rupture, we were able to determine the ejecta thickness.

  6. Ambient pressure synthesis of YBa 2Cu 4O 8 using citrate pyrolysis method

    NASA Astrophysics Data System (ADS)

    Hagiwara, M.; Yamao, T.; Matsuura, M.

    2003-10-01

    Synthetic method of YBa 2Cu 4O 8 (124) under a condition of ambient pressure of O 2 gas using citrate pyrolysis technique is examined in order to improve the reproducibility. A new reaction tube device is designed to ensure complete calcination reaction, and the process from the precursor to 124 phase is traced successively by X-ray diffraction analyses. From the experiments, enough contact of flowing O 2 gas with the precursor, and slow heating rate (1 °C/min) to the optimal reaction temperature 780 °C are suggested to be essential. Long reaction process (for 70 h or more) is necessary for higher purity. A transient mixture state of Y 2Cu 2O 5, BaCO 3 and CuO phases is found to grow up in early stage of the calcination process. This mixture state leads to the formation of final 124 phase with good reproducibility.

  7. Ambient-Pressure Bulk Superconductivity Deep in the Magnetic State of CeRhIn5

    SciTech Connect

    Paglione,J.; Ho, P.; Maple, M.; Tanatar, M.; Taillefer, L.; Lee, Y.; Petrovic, C.

    2008-01-01

    Specific heat, magnetic susceptibility and electrical transport measurements were performed at ambient pressure on high-quality single crystal specimens of CeRhIn5 down to ultra-low temperatures. We report signatures of an anomaly observed in all measured quantities consistent with a bulk phase transition to a superconducting state at T{sub c}=110 mK. Occurring far below the onset of antiferromagnetism at T{sub N}=3.8 K, this transition appears to involve a significant portion of the available low-temperature density of electronic states, exhibiting an entropy change in line with that found in other members of the 115 family of superconductors tuned away from quantum criticality.

  8. Ambient pressure synthesis of MIL-100(Fe) MOF from homogeneous solution using a redox pathway.

    PubMed

    Jeremias, Felix; Henninger, Stefan K; Janiak, Christoph

    2016-05-17

    Micro- to mesoporous iron(iii) trimesate MIL-100(Fe) is a MOF of high interest for numerous applications. With regard to large-scale synthesis, e.g., by continuous flow or the in situ deposition of coatings, a replacement for the conventional, hydrothermal low-yield fluoride-containing synthesis is desirable. In this contribution, we present a method to synthesize crystalline fluoride-free MIL-100(Fe) from iron(iii) nitrate and trimesic acid in zeotropic DMSO/water solution at normal ambient pressure involving a DMSO-nitrate redox pathway. Yields of 72%, surface areas of SBET = 1791 m(2) g(-1) and pore volumes of Vpore = 0.82 cm(3) g(-1) were achieved. PMID:27143562

  9. Thermal properties of PrBa 2Cu 4O 8 prepared at ambient oxygen pressure

    NASA Astrophysics Data System (ADS)

    Yang, H. D.; Lin, C. W.; Lin, J.-Y.; Meen, T. H.; Tsay, H. L.; Huang, J. C.; Sheen, S. R.; Wu, M. K.

    1997-08-01

    Polycrystalline PrBa 2Cu 4O 8 (Pr124) has been prepared at ambient oxygen pressure by nitrite pyrolysis method. Powder x-ray-diffraction patterns show a nearly single R124 phase. Thermogravimetric analysis indicates that its thermal stability is distinct from that of Pr123. Specific heat C has been measured from 0.5 to 40 K, and is very similar to that of Pr123. A maximum of C occurs around 17 K which could be due to a magnetic ordering. Entropy difference ΔS has been calculated from ΔC/ T between Pr124 and Y124. The possible origins of ΔS and the related magnetic properties are discussed. Resistivity ϱ( T) of Pr124 shows a nearly metallic behavior similar to what was observed in Pr124 made by the O 2-HIP technique. The metallic ϱ( T) at low temperatures is of interest and will be discussed.

  10. Synthesis of ammonia directly from air and water at ambient temperature and pressure

    PubMed Central

    Lan, Rong; Irvine, John T. S.; Tao, Shanwen

    2013-01-01

    The N≡N bond (225 kcal mol−1) in dinitrogen is one of the strongest bonds in chemistry therefore artificial synthesis of ammonia under mild conditions is a significant challenge. Based on current knowledge, only bacteria and some plants can synthesise ammonia from air and water at ambient temperature and pressure. Here, for the first time, we report artificial ammonia synthesis bypassing N2 separation and H2 production stages. A maximum ammonia production rate of 1.14 × 10−5 mol m−2 s−1 has been achieved when a voltage of 1.6 V was applied. Potentially this can provide an alternative route for the mass production of the basic chemical ammonia under mild conditions. Considering climate change and the depletion of fossil fuels used for synthesis of ammonia by conventional methods, this is a renewable and sustainable chemical synthesis process for future. PMID:23362454

  11. Static and dynamic fatigue behavior of glass filament-wound pressure vessels at ambient and cryogenic temperatures.

    NASA Technical Reports Server (NTRS)

    Hanson, M. P.

    1972-01-01

    Investigation of the pressure load carrying capacity and fatigue strength of filament-wound glass-reinforced plastic pressure vessels subjected to static and cyclic loading at ambient and cryogenic (liquid nitrogen) temperature environments. The results indicate that the static fatigue problem is not critical at cryogenic temperatures. Under static loading at liquid nitrogen temperature, a reinforced plastic cylinder sustained pressurization for 88 days without failure at about 90% of the single cycle burst strength. At ambient temperature, the static life at 90% of the burst strength was about 7 min. Under cyclic loading in liquid nitrogen, no failure resulted after 1509 cycles at 55% of the single cycle burst strength. Under the same cyclic loading at ambient temperature, the test results would predict failure in the reinforced plastic. The results of similar tests upon adhesively bonded polyimide aluminum-foil lined cylinders are also reviewed.-

  12. Acute Effects of Ambient Particulate Matter on Blood Pressure: Differential Effects across Urban Communities

    PubMed Central

    Dvonch, J. Timothy; Kannan, Srimathi; Schulz, Amy J.; Keeler, Gerald J.; Mentz, Graciela; House, James; Benjamin, Alison; Max, Paul; Bard, Robert L.; Brook, Robert D.

    2012-01-01

    Recent studies have suggested a link between exposure to ambient particulate matter <2.5μm in diameter (PM2.5) and adverse cardiovascular outcomes. The objective of this study was to examine the effects of differing community-level exposure to PM2.5 on daily measures of blood pressure (BP) among an adult population. During the period May 2002 through April 2003, BP was examined at two time points for 347 adults residing in three distinct communities of Detroit, MI. Exposure to PM2.5 was assessed in each community during this period, along with multivariate associations between PM2.5 and BP. In models combining all three communities, PM2.5 was significantly associated with systolic pressure (SP); a 10 μg/m3 increase in daily PM2.5 was associated with a 3.2 mm Hg increase in SP (p=0.05). However, in models that added a location interaction, larger effects were observed for SP within the community with highest PM2.5 levels; a 10 μg/m3 increase in daily PM2.5 was associated with a 8.6 mm Hg increase in SP (p=0.01). We also found young age (<55 years) and not taking BP medications to be significant predictors of increased BP effects. Among those taking BP medications, the PM2.5 effect on BP appeared to be mitigated, partially explaining the age effect, as those participants less than 55 years were less likely to take BP medications. Short-term increases in exposure to ambient PM2.5 are associated with acute increases in BP in adults, especially within communities with elevated levels of exposure. PMID:19273743

  13. Ambient pressure photoelectron spectroscopy: a new tool for surface science and nanotechnology

    SciTech Connect

    Salmeron, Miquel; Salmeron, Miquel; Schlogl, Robert

    2008-03-12

    Progress in science often follows or parallels the development of new techniques. The optical microscope helped convert medicine and biology from a speculative activity in old times to today's sophisticated scientific disciplines. The telescope changed the study and interpretation of heavens from mythology to science. X-ray diffraction enabled the flourishing of solid state physics and materials science. The technique object of this review, Ambient Pressure Photoelectron Spectroscopy or APPES for short, has also the potential of producing dramatic changes in the study of liquid and solid surfaces, particularly in areas such as atmospheric, environment and catalysis sciences. APPES adds an important missing element to the host of techniques that give fundamental information, i.e., spectroscopy and microscopy, about surfaces in the presence of gases and vapors, as encountered in industrial catalysis and atmospheric environments. APPES brings electron spectroscopy into the realm of techniques that can be used in practical environments. Decades of surface science in ultra high vacuum (UHV) has shown the power of electron spectroscopy in its various manifestations. Their unique property is the extremely short elastic mean free path of electrons as they travel through condensed matter, of the order of a few atomic distances in the energy range from a few eV to a few thousand eV. As a consequence of this the information obtained by analyzing electrons emitted or scattered from a surface refers to the top first few atomic layers, which is what surface science is all about. Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), and other such techniques have been used for decades and provided some of the most fundamental knowledge about surface crystallography, composition and electronic structure available today. Unfortunately the high interaction cross section of

  14. Measurement of activation volume for creep of dry olivine at upper mantle pressure

    NASA Astrophysics Data System (ADS)

    Dixon, N. A.; Durham, W. B.; Suzuki, A. M.; Mei, S.; Kohlstedt, D. L.; Hustoft, J. W.

    2011-12-01

    Olivine is the most abundant and weakest phase in the upper mantle, and thus its rheological properties have a critical role in controlling convective flow in this region. A resilient obstacle to understanding the behavior of olivine in the mantle has been the difficulty of determining activation volume (V*), the influence of hydrostatic pressure on flow strength. The bulk of previous studies examining V* were conducted at low pressure (<300 MPa) and small pressure ranges in gas-medium deformation apparatuses, limiting precision and raising questions about application to relevant geological conditions. For this study, we conducted deformation experiments on dry polycrystalline olivine in the D-DIA apparatus. The development of a new hybrid soft-fired pyrophyllite/mullite sample assembly allowed for a broadened pressure range (2-9 GPa), while stress and strain were measured in-situ with synchrotron x rays. Refinement in diffraction technique has allowed stress resolution of ±0.01 GPa. For the pressure range in this study, we have measured an average activation volume of about 17 cm^3/mol for dry polycrystalline San Carlos olivine. This is a substantial pressure effect, representing a pressure-induced viscosity increase of nearly 7 orders of magnitude from the base of the lithosphere to the bottom of the upper mantle.

  15. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions

    NASA Astrophysics Data System (ADS)

    Lu, Yi-Chun; Crumlin, Ethan J.; Veith, Gabriel M.; Harding, Jonathon R.; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J.; Liu, Zhi; Shao-Horn, Yang

    2012-10-01

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into LixV2O5 while molecular oxygen was reduced to form lithium peroxide on LixV2O5 in the presence of oxygen upon discharge. Interestingly, the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of conventional Li-O2 cells with aprotic electrolytes (~1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry.

  16. Ambient pressure proton transfer mass spectrometry: detection of amines and ammonia.

    PubMed

    Hanson, D R; McMurry, P H; Jiang, J; Tanner, D; Huey, L G

    2011-10-15

    An instrument to detect gaseous amines and ammonia is described, and representative data from an urban site and a laboratory setting are presented. The instrument, an Ambient pressure Proton transfer Mass Spectrometer (AmPMS), consists of a chemical ionization and drift region at atmospheric pressure coupled to a standard quadrupole mass spectrometer. Calibrations show that AmPMS sensitivity is good for amines, and AmPMS backgrounds were suitably determined by diverting sampled air through a catalytic converter. In urban air at a site in Atlanta, amines were detected at subpptv levels for methyl and dimethyl amine which were generally at a low abundance of <1 and ∼3 pptv, respectively. Trimethyl amine (or isomers) was on average about 4 pptv in the morning and increased to 15 pptv in the afternoon, while triethyl amine (or isomers or amides) increased to 25 pptv on average in the late afternoon. The background levels for the 4 and 5 carbon amines and ammonia were high, and data are very limited for these species. Improvements in detecting amines and ammonia from a smog chamber were evident due to improvements in AmPMS background determination; notably dimethyl amine and its OH oxidation products were followed along with impurity ammonia and other species. Future work will focus on accurate calibration standards and on improving the sample gas inlet. PMID:21892835

  17. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions

    PubMed Central

    Lu, Yi-Chun; Crumlin, Ethan J.; Veith, Gabriel M.; Harding, Jonathon R.; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J.; Liu, Zhi; Shao-Horn, Yang

    2012-01-01

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into LixV2O5 while molecular oxygen was reduced to form lithium peroxide on LixV2O5 in the presence of oxygen upon discharge. Interestingly, the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of conventional Li-O2 cells with aprotic electrolytes (~1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry. PMID:23056907

  18. In situ ambient pressure X-ray photoelectron spectroscopy studies of lithium-oxygen redox reactions.

    PubMed

    Lu, Yi-Chun; Crumlin, Ethan J; Veith, Gabriel M; Harding, Jonathon R; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J; Liu, Zhi; Shao-Horn, Yang

    2012-01-01

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li(4+x)Ti(5)O(12)/LiPON/Li(x)V(2)O(5) cell and examine in situ the chemistry of Li-O(2) reaction products on Li(x)V(2)O(5) as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into Li(x)V(2)O(5) while molecular oxygen was reduced to form lithium peroxide on Li(x)V(2)O(5) in the presence of oxygen upon discharge. Interestingly, the oxidation of Li(2)O(2) began at much lower overpotentials (~240 mV) than the charge overpotentials of conventional Li-O(2) cells with aprotic electrolytes (~1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O(2) chemistry. PMID:23056907

  19. Behavior of Supported Palladium Oxide Nanoparticles under Reaction Conditions, Studied with near Ambient Pressure XPS.

    PubMed

    Jürgensen, Astrid; Heutz, Niels; Raschke, Hannes; Merz, Klaus; Hergenröder, Roland

    2015-08-01

    Near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is a promising method to close the "pressure gap", and thus, study the surface composition during heterogeneous reactions in situ. The specialized spectrometers necessary for this analytical technique have recently been adapted to operate with a conventional X-ray source, making it available for routine quantitative analysis in the laboratory. This is shown in the present in situ study of the partial oxidation of 2-propanol catalyzed with PdO nanoparticles supported on TiO2, which was investigated under reaction conditions as a function of gas composition (alcohol-to-oxygen ratio) and temperature. Exposure of the nanoparticles to 2-propanol at 30 °C leads to immediate partial reduction of the PdO, followed by a continuous reduction of the remaining PdO during heating. However, gaseous oxygen inhibits the reduction of PdO below 90 °C, and the oxidation of 2-propanol to carboxylates only occurs in the presence of oxygen above 90 °C. These results support the theory that metallic palladium is the active catalyst material, and they show that environmental conditions affect the nanoparticles and the reaction process significantly. The study also revealed challenges and limitations of this analytical method. Specifically, the intensity and fixed photon energy of a conventional X-ray source limit the spectral resolution and surface sensitivity of lab-based NAP-XPS, which affect precision and accuracy of the quantitative analysis. PMID:26144222

  20. Nanosecond Time Resolved and Steady State Infrared Studies of Photoinduced Decomposition of TATB at Ambient and Elevated Pressures

    SciTech Connect

    Glascoe, E A; Zaug, J M; Armstrong, M R; Crowhurst, J C; Grant, C D; Fried, L E

    2009-03-05

    The timescale and/or products of photo-induced decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) were investigated at ambient pressure and compared with products formed at elevated pressure (i.e. 8 GPa). Ultrafast time-resolved infrared and steady state Fourier transform IR (FTIR) spectroscopies were used to probe TATB and its products after photoexcitation with a 5 ns pulse of 532 nm light. At ambient pressure, transient spectra of TATB indicate that the molecule has significantly decomposed within 60 ns; transient spectra also indicate that formation of CO{sub 2}, an observed decomposition product, is complete within 30-40 s. Proof of principle time resolved experiments at elevated pressures were performed and are discussed briefly. Comparison of steady-state FTIR spectra obtained at ambient and elevated pressure (ca. 8 GPa) indicate that the decomposition products vary with pressure. We find evidence for water as a decomposition product only at elevated pressure.

  1. Understanding the flowing atmospheric-pressure afterglow (FAPA) ambient ionization source through optical means.

    PubMed

    Shelley, Jacob T; Chan, George C-Y; Hieftje, Gary M

    2012-02-01

    The advent of ambient desorption/ionization mass spectrometry (ADI-MS) has led to the development of a large number of atmospheric-pressure ionization sources. The largest group of such sources is based on electrical discharges; yet, the desorption and ionization processes that they employ remain largely uncharacterized. Here, the atmospheric-pressure glow discharge (APGD) and afterglow of a helium flowing atmospheric-pressure afterglow (FAPA) ionization source were examined by optical emission spectroscopy. Spatial emission profiles of species created in the APGD and afterglow were recorded under a variety of operating conditions, including discharge current, electrode polarity, and plasma-gas flow rate. From these studies, it was found that an appreciable amount of atmospheric H(2)O vapor, N(2), and O(2) diffuses through the hole in the plate electrode into the discharge to become a major source of reagent ions in ADI-MS analyses. Spatially resolved plasma parameters, such as OH rotational temperature (T(rot)) and electron number density (n(e)), were also measured in the APGD. Maximum values for T(rot) and n(e) were found to be ~1100 K and ~4×10(19) m(-3), respectively, and were both located at the pin cathode. In the afterglow, rotational temperatures from OH and N(2)(+) yielded drastically different values, with OH temperatures matching those obtained from infrared thermography measurements. The higher N(2)(+) temperature is believed to be caused by charge-transfer ionization of N(2) by He(2)(+). These findings are discussed in the context of previously reported ADI-MS analyses with the FAPA source. PMID:22125181

  2. Surface stabilized GMR nanorods of silver coated CrO2 synthesized via a polymer complex at ambient pressure

    NASA Astrophysics Data System (ADS)

    Biswas, S.; Singh, G. P.; Ram, S.; Fecht, H.-J.

    2013-08-01

    Stable anisotropic nanorods of surface modified CrO2 (˜18 nm diameter) with a correlated diamagnetic layer (2-3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr4+ ions by Ag atoms on the CrO2 surface (topotactic surface layer) via an etching reaction of a CrO2-polymer complex with Ag+ ions in hot water followed by heating the dried sample at 300-400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO2 such that it no longer converts to Cr2O3 in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO2 structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d5/2 and 3d3/2 X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (-) 7.6% at 77 K, than reported values in compacted CrO2 powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO2 nanorods.

  3. Dynamic response of berea sandstone shock-loaded under dry, wet and water-pressurized conditions

    SciTech Connect

    Carney, T C; Hagelberg, C R; Hilt, M; Nellis, W J; Swift, R P

    1999-09-03

    A single-stage light-gas gun was used to perform shock-recovery experiments on Berea sandstone under dry, wet and hydrostatically water-pressurized conditions. The samples were impacted by flyer-plates to achieve stress levels in the range 1.3 to 9.8 GPa. The microstructure of the shocked samples was analyzed using scanning electron microscopy (SEM), laser particle analysis and X-ray computed microtomography (XCMT). The dry samples show strongly fragmented and irregularly fractured quartz grains with a considerably reduced porosity, whereas the wet and water-pressurized specimens show less grain damage and less porosity reduction. During shock compression the water in the pores distributes the stresses and therefore the contact force between the grains is reduced. The interaction between the grains during the shock process was modeled by explicitly treating the grain-pore structure using Smooth Particle Hydrodynamics (SPH) and the Discrete Element Method (DEM).

  4. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions

    SciTech Connect

    Lu, Yi-Chun; Crumlin, Ethan J.; Veith, Gabriel M.; Harding, Jonathon R.; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J.; Liu, Zhi; Shao-Horn, Yang

    2012-10-08

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and near ambient-pressure of oxygen using X-ray photoelectron spectroscopy (APXPS). Oxygen reduction and evolution reactions take place on the surface of the mixed electronic and Li+ ionic conductor, LixV2O5, which eliminate parasitic reactions between oxygen reduction/evolution reaction intermediates and aprotic electrolytes used in Li-O2 batteries reported to date. Under UHV, reversible lithium intercalation and de-intercalation from LixV2O5 was noted, where the changes in the vanadium valence state revealed from XPS in this study were comparable to that reported previously from Li/LixV2O5 thin film batteries. In presence of oxygen near ambient pressure, the LixV2O5 surface was covered gradually by the reaction product of oxygen reduction, namely lithium peroxide (Li2O2) (approximately 1-2 unit cells) upon discharge. Interestingly, the LixV2O5 surface became re-exposed upon charging, and the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of Li-O2 cells (~1000 mV) with aprotic electrolytes, which can be attributed to subnanometer-thick Li2O2 with surfaces free of contaminants such as carbonate species. Our study provides first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry.

  5. Fundamentals of ambient metastable-induced chemical ionization mass spectrometry and atmospheric pressure ion mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Harris, Glenn A.

    Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions. New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (< 1000 Da) molecules with a wide range of polarities. Although there is a large list of reported applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms. The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in

  6. 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

  7. 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

  8. Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air

    NASA Astrophysics Data System (ADS)

    Annette, Meiners; Michael, Leck; Bernd, Abel

    2015-01-01

    In this paper, a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is highlighted. In the present technological approach, the employment of air poses a significant challenge. The high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species lifetime. The plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission coefficient. In this way, the electron density and in turn the density of reactive species is increased. In addition, the plasma jet assembly is equipped with a short electrode. This leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma species. The plasma jet is formed within and emitted by a small conical nozzle. A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the nozzle. In the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the plasma. The range of short-lived active plasma species is in turn considerably enhanced. The jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma treatment. Numerical modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume.

  9. Direct Transformation of Amorphous Silicon Carbide into Graphene under Low Temperature and Ambient Pressure

    PubMed Central

    Peng, Tao; Lv, Haifeng; He, Daping; Pan, Mu; Mu, Shichun

    2013-01-01

    A large-scale availability of the graphene is critical to the successful application of graphene-based electronic devices. The growth of epitaxial graphene (EG) on insulating silicon carbide (SiC) surfaces has opened a new promising route for large-scale high-quality graphene production. However, two key obstacles to epitaxial growth are extremely high requirements for almost perfectly ordered crystal SiC and harsh process conditions. Here, we report that the amorphous SiC (a-Si1−xCx) nano-shell (nano-film) can be directly transformed into graphene by using chlorination method under very mild reaction conditions of relative low temperature (800°C) and the ambient pressure in chlorine (Cl2) atmosphere. Therefore, our finding, the direct transformation of a-Si1−xCx into graphene under much milder condition, will open a door to apply this new method to the large-scale production of graphene at low costs. PMID:23359349

  10. Direct Transformation of Amorphous Silicon Carbide into Graphene under Low Temperature and Ambient Pressure

    NASA Astrophysics Data System (ADS)

    Peng, Tao; Lv, Haifeng; He, Daping; Pan, Mu; Mu, Shichun

    2013-01-01

    A large-scale availability of the graphene is critical to the successful application of graphene-based electronic devices. The growth of epitaxial graphene (EG) on insulating silicon carbide (SiC) surfaces has opened a new promising route for large-scale high-quality graphene production. However, two key obstacles to epitaxial growth are extremely high requirements for almost perfectly ordered crystal SiC and harsh process conditions. Here, we report that the amorphous SiC (a-Si1-xCx) nano-shell (nano-film) can be directly transformed into graphene by using chlorination method under very mild reaction conditions of relative low temperature (800°C) and the ambient pressure in chlorine (Cl2) atmosphere. Therefore, our finding, the direct transformation of a-Si1-xCx into graphene under much milder condition, will open a door to apply this new method to the large-scale production of graphene at low costs.

  11. Direct transformation of amorphous silicon carbide into graphene under low temperature and ambient pressure.

    PubMed

    Peng, Tao; Lv, Haifeng; He, Daping; Pan, Mu; Mu, Shichun

    2013-01-01

    A large-scale availability of the graphene is critical to the successful application of graphene-based electronic devices. The growth of epitaxial graphene (EG) on insulating silicon carbide (SiC) surfaces has opened a new promising route for large-scale high-quality graphene production. However, two key obstacles to epitaxial growth are extremely high requirements for almost perfectly ordered crystal SiC and harsh process conditions. Here, we report that the amorphous SiC (a-Si(1-x)C(x)) nano-shell (nano-film) can be directly transformed into graphene by using chlorination method under very mild reaction conditions of relative low temperature (800°C) and the ambient pressure in chlorine (Cl(2)) atmosphere. Therefore, our finding, the direct transformation of a-Si(1-x)C(x) into graphene under much milder condition, will open a door to apply this new method to the large-scale production of graphene at low costs. PMID:23359349

  12. 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.

  13. Structural and superconducting features of Tl-1223 prepared at ambient pressure

    DOE PAGESBeta

    Shipra, Fnu; Idrobo Tapia, Juan Carlos; Sefat, Athena Safa

    2015-09-25

    This study provides an account of the bulk preparation of TlBa2Ca2Cu3O9-δ (Tl-1223) superconductor at ambient pressure, and the Tc features under thermal-annealing conditions. The ‘as-prepared’ Tl-1223 (Tc =106 K) presents a significantly higher Tc = 125 K after annealing the polycrystalline material in either flowing Ar+4% H2, or N2 gases. In order to understand the fundamental reasons for a particular Tc, we refined the average bulk structures using powder X-ray diffraction data. Although Ar+4%H2 annealed Tl- 1223 shows an increased ‘c’ lattice parameter, it shrinks by 0.03% (approximately unchanged) upon N2 anneal. Due to such indeterminate conclusions on the averagemore » structural changes, local structures were investigated at using aberration-corrected scanning-transmission electron microscopy technique. Similar compositional changes in the atomic arrangements of both annealed-samples of Tl-1223 were detected in which the plane containing Ca atomic layer gives a non-uniform contrast, due to substitution of some heavier Tl. In this report, extensive bulk properties are summarized through temperature-dependent resistivity, and shielding and Meissner fractions of magnetic susceptibility results; the bulk and local structures are investigated to correlate to properties.« less

  14. Structural and superconducting features of Tl-1223 prepared at ambient pressure

    SciTech Connect

    Shipra, Fnu; Idrobo Tapia, Juan Carlos; Sefat, Athena Safa

    2015-09-25

    This study provides an account of the bulk preparation of TlBa2Ca2Cu3O9-δ (Tl-1223) superconductor at ambient pressure, and the Tc features under thermal-annealing conditions. The ‘as-prepared’ Tl-1223 (Tc =106 K) presents a significantly higher Tc = 125 K after annealing the polycrystalline material in either flowing Ar+4% H2, or N2 gases. In order to understand the fundamental reasons for a particular Tc, we refined the average bulk structures using powder X-ray diffraction data. Although Ar+4%H2 annealed Tl- 1223 shows an increased ‘c’ lattice parameter, it shrinks by 0.03% (approximately unchanged) upon N2 anneal. Due to such indeterminate conclusions on the average structural changes, local structures were investigated at using aberration-corrected scanning-transmission electron microscopy technique. Similar compositional changes in the atomic arrangements of both annealed-samples of Tl-1223 were detected in which the plane containing Ca atomic layer gives a non-uniform contrast, due to substitution of some heavier Tl. In this report, extensive bulk properties are summarized through temperature-dependent resistivity, and shielding and Meissner fractions of magnetic susceptibility results; the bulk and local structures are investigated to correlate to properties.

  15. Differences in Blood Pressure and Vascular Responses Associated with Ambient Fine Particulate Matter Exposures Measured at the Personal Versus Community Level

    EPA Science Inventory

    Background Higher ambient fine particulate matter (PM2.5) levels can be associated with increased blood pressure and vascular dysfunction. Objectives To determine the differential effects on blood pressure and vascular function of daily changes in community ambient-...

  16. Water confinement in hydrophobic nanopores. Pressure-induced wetting and drying.

    PubMed

    Smirnov, Sergei; Vlassiouk, Ivan; Takmakov, Pavel; Rios, Fabian

    2010-09-28

    Wetting and drying of hydrophobic pores with diameters lower than 0.2 μm by aqueous solutions at different hydrostatic pressures is investigated by measuring the ionic conductance variation through the nanopores. The critical pressure for water intrusion into the nanopores increases with lowering the pore diameter and the surface tension of the hydrophobic modification, in agreement with the Laplace equation. Nevertheless, restoring the pressure to the atmospheric one does not result in spontaneous pore dewetting unless bubbles are left inside the pores. Such bubbles can appear at the regions of narrowing cross section and/or varying quality of the hydrophobic modification and thus can be engineered to control water expulsion. PMID:20690599

  17. What Is the Opposite of Pandora's Box? Direct Analysis, Ambient Ionization, and a New Generation of Atmospheric Pressure Ion Sources.

    PubMed

    B Cody, Robert

    2013-01-01

    The introduction of DART and DESI sources approximately seven years ago led to the development of a new series of atmospheric pressure ion sources referred to as "ambient ionization" sources. These fall into two major categories: spray techniques like DESI or plasma techniques like DART. The selectivity of "direct ionization," meaning analysis without chromatography and with little or no sample preparation, depends on the mass spectrometer selectivity. Although high resolution and tandem mass spectrometry are valuable tools, rapid and simple sample preparation methods can improve the utility of ambient ionization methods. The concept of ambient ionization has led to the realization that there are many more ways to form ions than might be expected. An interesting example is the use of a flint-and-steel spark source to generate ions from compounds such as phenolphthalein and Gramicidin S. PMID:24349926

  18. Effect of Substrate Temperature and Ambient Pressure on Heat Transfer at Interface Between Molten Droplet and Substrate Surface

    NASA Astrophysics Data System (ADS)

    Fukumoto, M.; Yang, K.; Tanaka, K.; Usami, T.; Yasui, T.; Yamada, M.

    2011-01-01

    Millimeter-sized molten Cu droplets were deposited on AISI304 substrate surface by free falling experiment. The roles of substrate temperature and ambient pressure on heat transfer at interface between molten droplet and substrate surface were systematically investigated. The splat characteristics were evaluated in detail. Temperature history of molten droplet was measured at splat-substrate interface. Cooling rate of the flattening droplet was calculated as well. Furthermore, the spreading behavior of molten droplet on substrate surface was captured by high speed camera. The heat transfer from splat to substrate was enhanced both by substrate heating and by ambient pressure reduction, which can be attributed to the good contact at splat bottom surface. The splats in free falling experiment showed similar changing tendency as thermal-sprayed particles. Consequently, substrate temperature and ambient pressure have an equivalent effect to contact condition at interface between droplet and substrate surface. Substrate heating and pressure reduction may enhance the wetting during splat flattening, and then affect the flattening and solidification behavior of the molten droplet.

  19. Sequential Coordination between Lingual and Pharyngeal Pressures Produced during Dry Swallowing

    PubMed Central

    Yano, Jitsuro; Aoyagi, Yoichiro; Ono, Takahiro; Hori, Kazuhiro; Yamaguchi, Wakami; Fujiwara, Shigehiro; Kumakura, Isami; Minagi, Shogo; Tsubahara, Akio

    2014-01-01

    The aim of this study was to investigate oropharyngeal pressure flow dynamics during dry swallowing in ten healthy subjects. Tongue pressure (TP) was measured using a sensor sheet system with five measuring points on the hard palate, and pharyngeal pressure (PP) was measured using a manometric catheter with four measuring points. The order and correlations of sequential events, such as onset, peak, and offset times of pressure production, at each pressure measuring point were analyzed on the synchronized waveforms. Onset of TP was earlier than that of PP. The peak of TP did not show significant differences with the onset of PP, and it was earlier than that of PP. There was no significant difference between the offset of TP and PP. The onset of PP was temporally time-locked to the peak of TP, and there was an especially strong correlation between the onset of PP and TP at the posterior-median part on the hard palate. The offset of PP was temporally time-locked to that of TP. These results could be interpreted as providing an explanation for the generation of oropharyngeal pressure flow to ensure efficient bolus transport and safe swallowing. PMID:25580436

  20. Tricalcium silicate (C{sub 3}S) hydration under high pressure at ambient and high temperature (200 deg. C)

    SciTech Connect

    Meducin, F.; Zanni, H.; Noik, C.; Hamel, G.; Bresson, B.

    2008-03-15

    The hydration of a tricalcium silicate paste at ambient temperature and at 200 deg. C under high pressure (up to 1000 bar) has been studied. Two high pressure cells have been used, one allows in-situ electrical conductivity measurements during hydration under high pressure. The hydration products were characterized by thermal analysis, X-ray diffraction and {sup 29}Si NMR measurements. The pressure has a large kinetic effect on the hydration of a C{sub 3}S paste at room temperature. The pressure was seen to affect drastically the hydration of a C{sub 3}S paste at 200 deg. C and this study evidences the competition between the different high temperature phases during the hydration.

  1. Etching of hexagonal SiC surfaces in chlorine-containing gas media at ambient pressure

    NASA Astrophysics Data System (ADS)

    Zinovev, A. V.; Moore, J. F.; Hryn, J.; Pellin, M. J.

    2006-06-01

    The modification of the silicon carbide (4H-SiC) single-crystal surface in a chlorine-containing gas mixture at high temperature (800-1000 °C) and ambient pressure was investigated. The results of silicon carbide chlorination are found to strongly depend on the hexagonal surface orientation. Due to the thermodynamically more favorable reaction of chlorine with silicon rather than carbon, the C-terminated side (0 0 0 1¯) clearly undergoes considerable changes, resulting in coverage by a black-colored carbon film, whereas the Si-side (0 0 0 1) surprisingly remains visually untouched. With using X-ray photoelectron spectroscopy (XPS), angle-resolved XPS and SEM it is shown that this drastic change in behavior is associated with a different structure of oxicarbide/silicate adlayer formed on the C- and Si-terminated sides of silicon carbide surface during experimental pre-treatment and air exposure. The presence of oxygen bridges connecting the silicate adlayer with the bulk SiC in the case of Si-side inhibits the chlorination reaction and makes this surface strongly resistant to chlorine attack. Only some places on the Si-terminated side demonstrate traces of chlorine etching in the form of hexagonal-shaped voids, which are possibly initiated by distortion of the initial crystalline structure by micropipes. In contrast, a thin carbon layer resulted on the C-terminated side as a consequence of the chlorination process. XPS, ARXPS, SEM and Raman spectroscopy study of created film allows us to argue that it consists mainly of sp2-bonded carbon, mostly in the form of nanoscale graphene sheets. The absence of a protective oxygen bridge between the silicate adlayer and the bulk silicon carbide crystal leads to unlimited growth of carbon film on the SiC(0 0 0 1¯) side.

  2. Effect of strain amplitude on relaxation spectra of attenuation in dry and saturated sandstone under pressure

    NASA Astrophysics Data System (ADS)

    Mashinskii, E. I.

    2007-06-01

    Laboratory experiments have been carried out to investigate the amplitude-frequency dependence of compressional- and shear-wave attenuation in samples of dry and saturated sandstone. The measurements were performed using the reflection method on a pulse frequency of 1 MHz in the strain range ~(0.3-2.0) × 10-6 under a confining pressure of 20 MPa. In general, the attenuation decreases monotonically with increasing strain amplitude as Q^{-1} \\propto \\varepsilon ^{-n_{\\sim} }, where n~ = 0.003-0.045. The decrease in P-wave attenuation, Q-1p, for dry sandstone is 5%, but for saturated sandstone there is no change. The analogous decrease for Q-1s in the dry and the saturated sandstone is 8% and 4%, respectively. The P-wave relaxation spectra, Q-1p(f), in the dry and saturated sandstone are slightly different from each other but the S-wave relaxation spectra, Q-1s(f), are very different. The amplitude variation causes the change in the value of the relaxation strength Δ that leads to the displacement of the curve Q-1(f) in the Y-direction. The value of Δs in the saturated rock is four times more than the value Δp in the dry rock, and the curves Q-1s(f) are shifted relative to Q-1p(f) towards higher frequencies. The upward-downward amplitude dependence Δp(ɛ1-6-1) both in the dry and the saturated rock is represented by the descending curve. The Δs(ɛ1-6-1) curve for the saturated rock shows hysteresis, but for the dry rock hysteresis is absent. The increase in the strain amplitude gives rise to a small change in peak frequency, but stimulates considerable (up to 40%) decrease in the S-wave relaxation peak width. The unusual behaviour of attenuation is explained by a feature of the joint action of viscoelastic and microplastic mechanisms. These results can be used to improve methods of geological interpretation of acoustical and seismic data.

  3. Formation of the -N(NO)N(NO)- polymer at high pressure and stabilization at ambient conditions.

    PubMed

    Xiao, Hai; An, Qi; Goddard, William A; Liu, Wei-Guang; Zybin, Sergey V

    2013-04-01

    A number of exotic structures have been formed through high-pressure chemistry, but applications have been hindered by difficulties in recovering the high-pressure phase to ambient conditions (i.e., one atmosphere and 300 K). Here we use dispersion-corrected density functional theory [PBE-ulg (Perdew-Burke-Ernzerhof flavor of DFT with the universal low gradient correction for long range London dispersion)] to predict that above 60 gigapascal (GPa) the most stable form of N2O (the laughing gas in its molecular form) is a one-dimensional polymer with an all-nitrogen backbone analogous to cis-polyacetylene in which alternate N are bonded (ionic covalent) to O. The analogous trans-polymer is only 0.03∼0.10 eV/molecular unit less stable. Upon relaxation to ambient conditions, both polymers relax below 14 GPa to the same stable nonplanar trans-polymer. The predicted phonon spectrum and dissociation kinetics validates the stability of this trans-poly-NNO at ambient conditions, which has potential applications as a type of conducting nonlinear optical polymer with all-nitrogen chains and as a high-energy oxidizer for rocket propulsion. This work illustrates in silico materials discovery particularly in the realm of extreme conditions (very high pressure or temperature). PMID:23503849

  4. A novel dry coal feeding concept for high-pressure gasifiers

    NASA Technical Reports Server (NTRS)

    Trumbull, H. E.; Davis, H. C.

    1977-01-01

    A novel dry coal feeding concept was developed for injecting ground coal into high-pressure gasifiers. Significant power savings are projected because the coal is injected directly with a ram and there is no requirement for pumping large volumes of gas or fluid against pressure. A novel feature of the concept is that a new seal zone is formed between the ram and injection tube each cycle. The seal zone comprises a mixture of a small quantity of finely ground coal and a fluid. To demonstrate the feasibility of the concept, coal was injected into a 1000-psi chamber with an experimental device having a 7-1/2-inch-diameter ram and a 28-inch-long stroke.

  5. Magnetic, electrical, and thermodynamic properties of NpIr: Ambient and high-pressure measurements, and electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Walker, H. C.; McEwen, K. A.; Griveau, J.-C.; Eloirdi, R.; Amador, P.; Maldonado, P.; Oppeneer, P. M.; Colineau, E.

    2015-05-01

    We present bulk property measurements of NpIr, a newly synthesized member of the Np-Ir binary phase diagram, which is isostructural to the noncentrosymmetric pressure-induced ferromagnetic superconductor UIr. Magnetic susceptibility, electronic transport properties at ambient and high pressure, and heat capacity measurements have been performed for temperatures T =0.55 -300 K in a range of magnetic fields up to 14 T and under pressure up to 17.3 GPa. These reveal that NpIr is a moderately heavy fermion Kondo system with strong antiferromagnetic interactions, but there is no evidence of any phase transition down to 0.55 K or at the highest pressure achieved. Experimental results are compared with ab initio calculations of the electronic band structure and lattice heat capacity. An extremely low lattice thermal conductivity is predicted for NpIr at temperatures above 300 K.

  6. Primary and secondary relaxations in supercooled eugenol and isoeugenol at ambient and elevated pressures: Dependence on chemical microstructure

    NASA Astrophysics Data System (ADS)

    Kaminska, E.; Kaminski, K.; Paluch, M.; Ngai, K. L.

    2006-04-01

    Dielectric loss spectra of two glass-forming isomers, eugenol and isoeugenol, measured at ambient and elevated pressures in the normal liquid, supercooled, and glassy states are presented. The isomeric chemical compounds studied differ only by the location of the double bond in the alkyl chain. Above the glass transition temperature Tg, the dielectric loss spectra of both isomers exhibit an excess wing on the high frequency flank of the loss peak of the α relaxation and an additional faster γ process at the megahertz frequency range. By decreasing temperature below Tg at ambient pressure or by elevating pressure above Pg, the glass transition pressure, at constant temperature, the excess wing of isoeugenol shifts to lower frequencies and is transformed into a secondary β-loss peak, while in eugenol it becomes a shoulder. These spectral features enable the β-relaxation time τβ to be determined in the glassy state. These changes indicate that the excess wings in isoeugenol and eugenol are similar and both are secondary β relaxations that are not resolved in the liquid state. While in both isoeugenol and eugenol the loss peak of the β relaxation in the glassy state and the corresponding excess wing in the liquid state shifts to lower frequencies on elevating pressure, the locations of their γ relaxation show little change with increasing pressure. The different pressure sensitivities of the excess wing and γ relaxation are further demonstrated by the nearly perfect superposition of the α-loss peak together with excess wing from the data taken at ambient pressure and at elevated pressure (and higher temperature so as to have the same α-peak frequency), but not the γ-loss peak in both isoeugenol and eugenol. On physical aging isoeugenol, the β-loss peak shifts to lower frequencies, but not the γ relaxation. Basing on these experimental facts, the faster γ relaxation is a local intramolecular process involving a side group and the slower β relaxation

  7. Ambient-condition growth of high-pressure phase centrosymmetric crystalline KDP microstructures for optical second harmonic generation.

    PubMed

    Ren, Yan; Zhao, Xian; Hagley, Edward W; Deng, Lu

    2016-08-01

    Noncentrosymmetric potassium dihydrogen phosphate (KH2PO4 or KDP) in the tetragonal crystal phase is arguably the most extensively studied nonlinear optical crystal in history. It has prolific applications ranging from simple laser pointers to laser inertial confinement fusion systems. Recently, type IV high-pressure KDP crystal sheets with a monoclinic crystal phase having centrosymmetric properties have been observed. However, it was found that this new crystal phase is highly unstable under ambient conditions. We report ambient-condition growth of one-dimensional, self-assembled, single-crystalline KDP hexagonal hollow/solid-core microstructures that have a molecular structure and symmetry identical to the type IV KDP monoclinic crystal that was previously found to exist only at extremely high pressures (>1.6 GPa). Furthermore, we report highly efficient bulk optical second harmonic generation (SHG) from these ambient condition-grown single-crystalline microstructures, even though they have a highly centrosymmetric crystal phase. However, fundamental physics dictates that a bulk optical medium with a significant second-order nonlinear susceptibility supporting SHG must have noncentrosymmetric properties. Laue diffraction analysis reveals a weak symmetry-breaking twin-crystal lattice that, in conjunction with tight confinement of the light field by the tubular structure, is attributed to the significant SHG even with sample volumes <0.001 mm(3). A robust polarization-preserving effect is also observed, raising the possibility of advanced optical technological applications. PMID:27574703

  8. Ambient-condition growth of high-pressure phase centrosymmetric crystalline KDP microstructures for optical second harmonic generation

    PubMed Central

    Ren, Yan; Zhao, Xian; Hagley, Edward W.; Deng, Lu

    2016-01-01

    Noncentrosymmetric potassium dihydrogen phosphate (KH2PO4 or KDP) in the tetragonal crystal phase is arguably the most extensively studied nonlinear optical crystal in history. It has prolific applications ranging from simple laser pointers to laser inertial confinement fusion systems. Recently, type IV high-pressure KDP crystal sheets with a monoclinic crystal phase having centrosymmetric properties have been observed. However, it was found that this new crystal phase is highly unstable under ambient conditions. We report ambient-condition growth of one-dimensional, self-assembled, single-crystalline KDP hexagonal hollow/solid-core microstructures that have a molecular structure and symmetry identical to the type IV KDP monoclinic crystal that was previously found to exist only at extremely high pressures (>1.6 GPa). Furthermore, we report highly efficient bulk optical second harmonic generation (SHG) from these ambient condition–grown single-crystalline microstructures, even though they have a highly centrosymmetric crystal phase. However, fundamental physics dictates that a bulk optical medium with a significant second-order nonlinear susceptibility supporting SHG must have noncentrosymmetric properties. Laue diffraction analysis reveals a weak symmetry-breaking twin-crystal lattice that, in conjunction with tight confinement of the light field by the tubular structure, is attributed to the significant SHG even with sample volumes <0.001 mm3. A robust polarization-preserving effect is also observed, raising the possibility of advanced optical technological applications. PMID:27574703

  9. Characterization Testing of H20-SO2 Electrolyzer at Ambient Pressure

    SciTech Connect

    Steimke, J

    2005-07-29

    are included to allow variation of the operating pressure in the range of 1 to 2 bar. Hydrogen generated at the cathode of the cell can be collected for the purpose of flow measurement and composition analysis. The test facility proved to be easy to operate, versatile, and reliable. Two slightly different SDE's were designed, procured and tested. The first electrolyzer was based on a commercially available PEM water electrolyzer manufactured by Proton Energy Systems, Inc. (PES). The PES electrolyzer was built with Hastelloy B and Teflon wetted parts, a PEM electrolyte, and porous titanium electrodes. The second electrolyzer was assembled for SRNL by the University of South Carolina (USC). It was constructed with platinized carbon cloth electrodes, a Nafion 115 PEM electrolyte, carbon paper flow fields, and solid graphite back plates. Proof-of-concept testing was performed on each electrolyzer at near-ambient pressure and room temperature under various feed conditions. SDE operation was evidenced by hydrogen production at the cathode and sulfuric acid production at the anode (witnessed by the absence of oxygen generation) and with cell voltages substantially less than the theoretical reversible voltage for simple water electrolysis (1.23 V). Cell performance at low currents equaled or exceeded that achieved in the two-compartment cells built by Westinghouse Electric Corporation during the original development of the HyS Process. Performance at higher currents was less efficient due to mass transfer and hydraulic issues associated with the use of cells not optimized for liquid feed. Test results were analyzed to determine performance trends, improvement needs, and long-term SDE potential. The PES cell failed after several days of operation due to internal corrosion of the titanium electrodes in the presence of sulfuric acid. Although it was anticipated that the titanium would react in the presence of acid, the rapid deterioration of the electrodes was unexpected. The

  10. Distributed sensing of Composite Over-wrapped Pressure Vessel using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Grant, Joseph

    2005-01-01

    Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

  11. Distributed Sensing of Composite Over-wrapped Pressure Vessel Using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Grant, Joseph

    2004-01-01

    Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

  12. Structure, Mobility, and Composition of Transition Metal Catalyst Surfaces. High-Pressure Scanning Tunneling Microscopy and Ambient-Pressure X-ray Photoelectron Spectroscopy Studies

    SciTech Connect

    Zhu, Zhongwei

    2013-12-06

    Surface structure, mobility, and composition of transition metal catalysts were studied by high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at high gas pressures. HP-STM makes it possible to determine the atomic or molecular rearrangement at catalyst surfaces, particularly at the low-coordinated active surface sites. AP-XPS monitors changes in elemental composition and chemical states of catalysts in response to variations in gas environments. Stepped Pt and Cu single crystals, the hexagonally reconstructed Pt(100) single crystal, and Pt-based bimetallic nanoparticles with controlled size, shape and composition, were employed as the model catalysts for experiments in this thesis.

  13. Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection.

    PubMed

    Neidholdt, Evan L; Beauchamp, J L

    2009-11-01

    We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions such as protonated water clusters or clusters of hydroxide and water. Reactant ions can be observed directly in the mass spectrometer. These go on to react with trace neutrals via proton transfer reactions to produce the ions observed in mass spectra, which are usually singly protonated or deprotonated species. Further implicating gas-phase ionization, observed product distributions are highly dependent on the composition of ambient gases, especially the concentration of water vapor and oxygen surrounding the source. For example, basic species such as triethylamine are observed as singly protonated cations at a water partial pressure of 10 torr. At a water pressure of 4 torr, reactive oxygen species are formed and lead to observation of protonated amine oxides. The ability of the APPIS source to detect basic molecules with high proton affinities makes it highly suited for the detection of chemical nerve agents. We demonstrate this application using simulants corresponding to VX and GA (Tabun). With the present source configuration pyridine is detected readily at a concentration of 4 ppm, indicating ultimate sensitivity in the high ppb range. PMID:19682922

  14. Atmospheric Pressure Liquefaction of Dried Distillers Grains (DDG and Making Polyurethane Foams from Liquefied DDG

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Le, Zhiping; Chen, Paul; Liu, Yuhuan; Lin, Xiangyang; Ruan, Roger

    In this study, dried distillers grains (DDG) was liquefied in acidic conditions at atmospheric pressure, and polyurethane foams were subsequently prepared from the liquefied DDG. Liquefaction was examined over a range of conditions including liquefaction time of 1-3 h, temperature of 150-170 °C, sulfuric acid (as catalyst) concentration of 1.0-3.0 wt%, and liquefaction solvent (ethylene carbonate) to DDG ratio of 3:1-5:1. The bio-polyols in the liquefied DDG were rich in hydroxyl groups, which can react with methylene diphenyl diisocyanate (MDI) to form cross-linked polyurethane networks. The biodegradability of the prepared polyurethane foams was also evaluated. This study strives to broaden the application of DDG as a feedstock for bio-polyurethane preparation.

  15. Superconductivity at 93 K in a new mixed-phase Y-Ba-Cu-O compound system at ambient pressure

    NASA Technical Reports Server (NTRS)

    Wu, M. K.; Ashburn, J. R.; Torng, C. J.; Hor, P. H.; Meng, R. L.

    1987-01-01

    A stable and reproducible superconductivity transition between 80 and 93 K has been achieved and maintained in a Y-Ba-Cu-O compound system at ambient pressure in a simple liquid-nitrogen Dewar. An upper critical field Hc2(0) estimate of between 80 and 180 T is obtained, and the paramagnetic limiting field at 0 K for a sample with a T(c) of about 90 K is 165 T. It is suggested that the lattice parameters, the valence ratio, and the sample treatments all play a role in achieving superconductivity above 77 K.

  16. Experimental Study of the Momentum Coupling Coefficient with the Pulse Frequency and Ambient Pressure for Air-Breathing Laser Propulsion

    NASA Astrophysics Data System (ADS)

    Tang, Zhiping; Cai, Jian; Gong, Ping; Hu, Xiaojun; Tan, Rongqin; Zheng, Zhijun; Wu, Jin; Lu, Yan

    2006-05-01

    The air-breathing laser propulsion tests are conducted for parabolic models by using a high power TEA-CO2 pulsed laser. It is found the momentum coupling coefficient Cm varies with the pulse repeatable frequency and reaches the maximum near 50Hz. With a multi-use pendulum chamber, the change of Cm at different ambient pressure is measured. The experimental results show that the propulsion efficiency Cm does not decrease below the altitude of 10km, even increases a little bit. The calculated Cm fits the experimental result up to altitude 3km, then, they are separated. One possible reason is the temperature which is constant in the experiments.

  17. Monitoring ambient air pollutants and apply Woods' model in the prediction seasonal dry deposition at Chang-Hua (urban) and Kao-Mei (wetland) county, Taiwan.

    PubMed

    Fang, Guor-Cheng; Chang, Chia-Ying

    2014-09-01

    The main purpose for this study was to monitor ambient air particles and metallic elements (Mn, Fe, Zn, Cr, Cu and Pb) in total suspended particulate (TSP) concentration and dry deposition. In addition, the calculated/measured dry deposition flux ratios of ambient air particles and metallic elements (Mn, Fe, Zn, Cr, Cu and Pb) were evaluated using Woods' model at urban and wetland areas for the 2009-2010 period. The results indicated that the mean highest concentrations of metallic elements Mn, Fe, Zn, Cr, Cu and Pb in TSP were found in Chang-Hua (urban) sampling site. And as for the two characteristic sampling sites, the Woods' model exhibits better dry deposition of particulates of 18 µm particle size than the rest of the other particle sizes at any sampling site in this study. The average calculated/measured flux ratios for two seasons (summer and fall) by using Woods model at 2.5, 10 and 18 µm particles sizes were also studied. The results indicated that the average calculated/measured flux ratios orders for two seasons of various particles sizes were all displayed as Fe > Mn > Zn > Cu > Cr > Pb > particle. And these calculated/measured flux ratios orders were Fe > Mn > Cu > Zn > Cr > Pb > particle and were Fe > Mn > Zn > Cu > Cr > particle > Pb, during spring and winter seasons, respectively. Finally, in the spring and summer seasons of Gao-Mei (wetland) sampling site, the average calculated/measured flux ratios using Woods' model was found to be 2.5, 10 and 18 µm, showing the order of the calculated/measured flux ratios to be Fe > Cu > Zn > Mn > Cr > Pb > particle. And the calculated/measured flux ratio orders were Fe > Zn > Mn > Cu > Cr > particle > Pb and were Fe > Cu > Zn > Mn > Cr > particle > Pb for fall and winter season, respectively. PMID:23070636

  18. ACTRIS-Inter-laboratory comparison of VOCs in Europe: measurements of synthetic mixture and ambient air from pressurized cylinders

    NASA Astrophysics Data System (ADS)

    Hoerger, Corinne C.; Plass-Duelmer, Christian; Steinbrecher, Rainer; Weiss, Elisabeth; Werner, Anja; Reimann, Stefan

    2013-04-01

    For the analysis of volatile organic compounds (VOCs) in a synthetic mixture and in ambient air a comparison study between 19 European laboratories (see affiliations) running 21 research facilities was performed during 2012. The participating laboratories performed five measurements of a synthetic mixture (VOC in nitrogen) and of ambient air (VOCs in urban air) from high pressure cylinders. Reported VOCs include: 14 alkanes, 12 alkenes, 2 alkynes, 1 cyclic alkane, and 5 aromatics. For the synthetic mixture, most laboratories reported VOC concentrations in a range close to the reference value (± 10-15%), which was defined as the error weighted average of measurements previously performed by three selected laboratories (Empa-Duebendorf, DWD-Hohenpeissenberg, KIT-Garmisch-Partenkirchen). The compound with the largest difference between reported and reference value was n-hexane with a difference exceeding 300% for one laboratory. For ambient air, the range of concentrations measured by the laboratories was considerably larger. Whereas measurements were close to the reference values for alkanes (e.g. propane) (± 10-15%), alkenes (e.g. cis-butene) and alkynes (e.g. ethyne) led to the largest differences between reported concentrations and reference values (up to 900%). Further investigations related to the measurement techniques applied by the participating laboratories and the elaboration of possible improvements will be shown. This will contribute to the preparation of a measurement guideline to be used for quantifying VOCs in air.

  19. Heart rate and blood pressure time courses during prolonged dry apnoea in breath-hold divers.

    PubMed

    Perini, Renza; Tironi, Adelaide; Gheza, Alberto; Butti, Ferdinando; Moia, Christian; Ferretti, Guido

    2008-09-01

    To define the dynamics of cardiovascular adjustments to apnoea, beat-to-beat heart rate (HR) and blood pressure and arterial oxygen saturation (SaO(2)) were recorded during prolonged breath-holding in air in 20 divers. Apnoea had a mean duration of 210 +/- 70 s. In all subjects, HR attained a value 14 beats min(-1) lower than control within the initial 30 s (phase I). HR did not change for the following 2-2.5 min (phase II). Then, nine subjects interrupted the apnoea (group A), whereas 11 subjects (group B) could prolong the breath-holding for about 100 s, during which HR continuously decreased (phase III). In both groups, mean blood pressure was 8 mmHg above control at the end of phase I; it then further increased by additional 12 mmHg at the end of the apnoea. In both groups, SaO(2) did not change in the initial 100-140 s of apnoea; then, it decreased to 95% at the end of phase II. In group B, SaO(2) further diminished to 84% at the end of phase III. A typical pattern of cardiovascular readjustments was identified during dry apnoea. This pattern was not compatible with a role for baroreflexes in phase I and phase II. Further readjustment in group B may imply a role for both baroreflexes and chemoreflexes. Hypothesis has been made that the end of phase II corresponds to physiological breakpoint. PMID:18496707

  20. Self-dispersible nanocrystals of albendazole produced by high pressure homogenization and spray-drying.

    PubMed

    Paredes, Alejandro Javier; Llabot, Juan Manuel; Sánchez Bruni, Sergio; Allemandi, Daniel; Palma, Santiago Daniel

    2016-10-01

    Albendazole (ABZ) is a broad-spectrum antiparasitic drug used in the treatment of human or animal infections. Although ABZ has shown a high efficacy for repeated doses in monogastric mammals, its low aqueous solubility leads to erratic bioavailability. The aim of this work was to optimize a procedure in order to obtain ABZ self-dispersible nanocrystals (SDNC) by combining high pressure homogenization (HPH) and spray-drying (SD). The material thus obtained was characterized and the variables affecting both the HPH and SD processes were studied. As expected, the homogenizing pressure and number of cycles influenced the final particle size, while the stabilizer concentration had a strong impact on SD output and redispersion of powders upon contact with water. ABZ SDNC were successfully obtained with high process yield and redispersibility. The characteristic peaks of ABZ were clearly identified in the X-ray patterns of the processed samples. A noticeable increase in the dissolution rate was observed in the aqueous environment. PMID:26856301

  1. A near-ambient-pressure XPS study on catalytic CO oxidation reaction over a Ru(101¯0) surface

    NASA Astrophysics Data System (ADS)

    Toyoshima, Ryo; Shimura, Masahiro; Yoshida, Masaaki; Monya, Yuji; Suzuki, Kazuma; Amemiya, Kenta; Mase, Kazuhiko; Mun, Bongjin Simon; Kondoh, Hiroshi

    2014-03-01

    We investigated the interactions of CO and O2 with Ru(101¯0) single crystal surfaces, and studied the in-situ catalytic oxidation reaction of CO on the surface under near realistic pressure conditions by using a combination of near-ambient-pressure x-ray photoelectron spectroscopy and differential pumping mass spectroscopy. At lower temperatures (T < 190 °C), most of the surface keeps metallic and is covered by both chemisorbed atomic oxygen and CO, and the CO2 formation rate is relatively slow. At higher temperatures, the reaction rate significantly increases and reaches the saturation, where the Ru surface is dominated by a bulk oxide (i.e. RuO2).

  2. Quantitative analysis of aluminum samples in He ambient gas at different pressures in a thick LIBS plasma

    NASA Astrophysics Data System (ADS)

    Rezaei, Fatemeh; Tavassoli, Seyed Hassan

    2015-09-01

    In this paper, the influences of He ambient gas on aluminum emissions are investigated by experimental analysis of LIBS spectrum. Plasma is produced by focusing of a Nd:YAG laser pulse at a wavelength of 1064 nm on Al standard samples. In this work, the effects of helium atmosphere at different pressures on the amount of spectral self-absorption are studied. The results are discussed by utilizing two approaches: the curve of growth and calibration curve. It is seen that by increasing the gas pressure, the self-absorption enhances. Also, a new method of applying one standard sample instead of other traditional techniques is introduced for concentration prediction. The presented method would be helpful for the situation in which supplying standard samples is not very easy. Then, the accuracy of this new method can be checked by comparison of concentration prediction of the standard samples with their real concentrations.

  3. Prediction of Solids Circulation Rate of Cork Particles in an Ambient-Pressure Pilot-Scale Circulating Fluidized Bed

    SciTech Connect

    Huang, Yue; Turton, Richard; Famouri, Parviz; Boyle, Edward J.

    2009-01-07

    Circulating fluidized beds (CFB) are currently used in many industrial processes for noncatalytic and catalytic because its effective control is the key to smooth operation of a CFB system. This paper presents a method for solids flow metering from pressure drop measurements in the standpipe dense phase. A model based on the Ergun equation is developed to predict the solids flow rate and voidage in the dense phase of the standpipe. The profile of the solids flow rate under unsteady state is also presented. With the use of this method, the dynamic response time at different locations along the standpipe of a pilot-scale fluidized bed operating at ambient conditions with 812 mu m cork particles is estimated successfully. Through the use of a pressure balance analysis, solids flow models for the standpipe, riser, and other sections of the flow loop are combined to give an integrated CFB model.

  4. In-Situ observation of wet oxidation kinetics on Si (100) via ambient pressure x-ray photoemission spectroscopy

    SciTech Connect

    Hussain, Zahid; Rossi, Massimiliano; Mun, Bongjin S.; Enta, Yoshiharu; Fadley, Charles S.; Lee, Ki-Suk; Kim, Sang-Koog; Shin, Hyun-Joon; Hussain, Zahid; Ross, Jr., Philip N.

    2007-08-24

    The initial stages of wet thermal oxidation of Si(100)-(2x1) have been investigated by in-situ ambient pressure x-ray photoemission spectroscopy (APXPS), including chemical-state resolution via Si 2p core-level spectra. Real-time growth rates of silicon dioxide have been monitored at 100 mTorr of water vapor. This pressure is considerably higher than in any prior study using XPS. Substrate temperatures have been varied between 250 and 500 C. Above a temperature of {approx} 400 C, two distinct regimes, a rapid and a quasi-saturated one, are identified and growth rates show a strong temperature dependence which cannot be explained by the conventional Deal-Grove model.

  5. Molecular Studies of Surfaces under Reaction Conditions; Sum Frequency Generation Vibrational Spectroscopy, Scanning Tunneling Microscopy and Ambient Pressure X-Ray Photoelectron Spectroscopy

    SciTech Connect

    Somorjai, G.A.

    2009-11-11

    Instruments developed in our laboratory permit the atomic and molecular level study of NPs under reaction conditions (SFG, ambient pressure XPS and high pressure STM). These studies indicate continuous restructuring of the metal substrate and the adsorbate molecules, changes of oxidation states with NP size and surface composition variations of bimetallic NPs with changes of reactant molecules.

  6. Temperature and electron density distributions of laser-induced plasmas generated with an iron sample at different ambient gas pressures

    NASA Astrophysics Data System (ADS)

    Aguilera, J. A.; Aragón, C.

    2002-09-01

    Intensity, temperature and electron density distributions of laser-induced plasmas (LIPs) have been measured by emission spectroscopy with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated with an iron sample at different pressures of air, in the range 10-1000 mbar. An experimental system based in an imaging spectrometer equipped with an intensified CCD detector has been used to obtain the spectra with two-dimensional spatial resolution. The evolution of the intensity distributions is described by the blast wave model only at initial times. The temperature distributions are shown to correspond to a slight difference between the intensity distributions of two Fe I emission lines that have a high difference of their upper energy levels (3.38 eV). The electron density distributions have similar features to those of the temperature distributions. The features of the intensity and temperature distributions show a significant change with the ambient gas pressure: they have separated maxima in the plasmas generated at pressures below 100 mbar, whereas at higher pressures, the maxima of the two distributions coincide.

  7. Effect of Fe on the Elastic Constants of Magnesiowustite [(Mg,Fe)O] at Ambient Conditions and High Pressure

    NASA Astrophysics Data System (ADS)

    Sinogeikin, S. V.; Reichmann, H. J.; Bass, J. D.; Mackwell, S. J.; Jacobsen, S. D.

    2001-12-01

    Magnesiowustite is a major mineral in the lower mantle of the Earth. While the effect of temperature and pressure on the elasticity of MgO is well constrained, the effect of Fe on the elastic constants and their pressure derivatives is still uncertain, especially for compositions close to the Mg end-member. Here we present the Brillouin spectroscopy measurements of the single-crystal elastic constants of magnesiowustite at ambient conditions ( ~5.8 mol.% Fe) and to high pressures up to about 10 GPa ( ~1.3 mol.% Fe). The single-crystal samples were prepared by Mg:Fe interdiffusion between periclase single crystals and magnesiowustite powders with carefully controlled oxygen fugacity. The Brillouin scattering measurements were performed in platelet symmetric geometry, which significantly increases the accuracy, and is calibrated with respect to standard periclase sample. High-pressure measurements were performed in a large optical opening Merrill-Basset type diamond anvil cell with Methanol-Ethanol-Water mixture as a pressure-transmitting medium. The new results confirm earlier single-crystal ultrasonic measurements (gigahertz interferometry) which indicated that the behavior of the elastic moduli of magnesiowustite are highly nonlinear in Mg-rich end. A pronounced decrease in acoustic velocities with increasing Fe content is especially obvious in samples with Fe contents of <10 mol. %. The pressure derivatives of the elastic moduli of the sample with XFe = 1.3 mol % are equal to those of periclase within the experimental uncertainties, although the Fe content of the sample may be too small to allow compositional trends to be clearly identified.

  8. Comparison of Surfactant Distributions in Pressure-Sensitive Adhesive Films Dried from Dispersion under Lab-Scale and Industrial Drying Conditions.

    PubMed

    Baesch, S; Siebel, D; Schmidt-Hansberg, B; Eichholz, C; Gerst, M; Scharfer, P; Schabel, W

    2016-03-01

    Film-forming latex dispersions are an important class of material systems for a variety of applications, for example, pressure-sensitive adhesives, which are used for the manufacturing of adhesive tapes and labels. The mechanisms occurring during drying have been under intense investigations in a number of literature works. Of special interest is the distribution of surfactants during the film formation. However, most of the studies are performed at experimental conditions very different from those usually encountered in industrial processes. This leaves the impact of the drying conditions and the resulting influence on the film properties unclear. In this work, two different 2-ethylhexyl-acrylate (EHA)-based adhesives with varying characteristics regarding glass transition temperature, surfactants, and particle size distribution were investigated on two different substrates. The drying conditions, defined by film temperature and mass transfer in the gas phase, were varied to emulate typical conditions encountered in the laboratory and industrial processes. Extreme conditions equivalent to air temperatures up to 250 °C in a belt dryer and drying rates of 12 g/(m(2)·s) were realized. The surfactant distributions were measured by means of 3D confocal Raman spectroscopy in the dry film. The surfactant distributions were found to differ significantly with drying conditions at moderate film temperatures. At elevated film temperatures the surfactant distributions are independent of the investigated gas side transport coefficients: the heat and mass transfer coefficient. Coating on substrates with significantly different surface energies has a large impact on surfactant concentration gradients, as the equilibrium between surface and bulk concentration changes. Dispersions with higher colloidal stability showed more homogeneous lateral surfactant distributions. These results indicate that the choice of the drying conditions, colloidal stability, and substrates is crucial

  9. Effect of compression pressure on inhalation grade lactose as carrier for dry powder inhalations

    PubMed Central

    Raut, Neha Sureshrao; Jamaiwar, Swapnil; Umekar, Milind Janrao; Kotagale, Nandkishor Ramdas

    2016-01-01

    Introduction: This study focused on the potential effects of compression forces experienced during lactose (InhaLac 70, 120, and 230) storage and transport on the flowability and aerosol performance in dry powder inhaler formulation. Materials and Methods: Lactose was subjected to typical compression forces 4, 10, and 20 N/cm2. Powder flowability and particle size distribution analysis of un-compressed and compressed lactose was evaluated by Carr's index, Hausner's ratio, the angle of repose and by laser diffraction method. Aerosol performance of un-compressed and compressed lactose was assessed in dispersion studies using glass twin-stage-liquid-impenger at flow rate 40-80 L/min. Results: At compression forces, the flowability of compressed lactose was observed same or slightly improved. Furthermore, compression of lactose caused a decrease in in vitro aerosol dispersion performance. Conclusion: The present study illustrates that, as carrier size increases, a concurrent decrease in drug aerosolization performance was observed. Thus, the compression of the lactose fines onto the surfaces of the larger lactose particles due to compression pressures was hypothesized to be the cause of these observed performance variations. The simulations of storage and transport in an industrial scale can induce significant variations in formulation performance, and it could be a source of batch-to-batch variations. PMID:27014618

  10. Vertical distribution of optical and micro-physical properties of ambient aerosols during dry haze periods in Shanghai

    NASA Astrophysics Data System (ADS)

    Chen, Yonghang; Liu, Qiong; Geng, Fuhai; Zhang, Hua; Cai, Changjie; Xu, Tingting; Ma, Xiaojun; Li, Hao

    2012-04-01

    Based on the lidar data obtained from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite of NASA (National Aeronautics and Space Administration), the vertical distributions of aerosols are revealed during dry haze periods in the Shanghai vicinity by analyzing the optical and micro-physical parameters including total attenuated backscatter coefficient (TABC), volume depolarization ratio (VDR) and total attenuated color ratio (TACR). The preliminary conclusion is that when dry haze occurs in the Shanghai vicinity, smoke and maritime aerosols are the major types in summer and autumn and aerosols might be affected by long-distance transport of dust in spring; lower troposphere below 2 km is the layer polluted most severely and aerosol scattering with relatively irregular shape is much stronger than that of aerosols with relatively regular shape within 2-10 km in middle and upper troposphere; relatively large aerosols appear more frequently in lower (0-2 km) and middle troposphere (2-6 km) than those in upper troposphere (6-10 km). In addition, HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model is applied to analyze the aerosol sources during two typical episodes. The results indicate that the middle and upper troposphere in the Shanghai vicinity are affected by the long-distance transport of dusts from northwest of China or other upstream regions. The high aerosol concentrations in the Shanghai vicinity are mainly caused not only by local human activities but also by the long-distance transport from other places.

  11. Approximating Fluid Flow from Ambient to Very Low Pressures: Modeling ISS Experiments that Vent to Vacuum

    NASA Technical Reports Server (NTRS)

    Minor, Robert

    2002-01-01

    Two ISS (International Space Station) experiment payloads will vent a volume of gas overboard via either the ISS Vacuum Exhaust System or the Vacuum Resource System. A system of ducts, valves and sensors, under design, will connect the experiments to the ISS systems. The following tasks are required: Create an analysis tool that will verify the rack vacuum system design with respect to design requirements, more specifically approximate pressure at given locations within the vacuum systems; Determine the vent duration required to achieve desired pressure within the experiment modules; Update the analysis as systems and operations definitions mature.

  12. Characterization of Ultrafast Laser-Ablation Plasma Plumes at Various Ar Ambient Pressures

    SciTech Connect

    Diwakar, P. K.; Harilal, S. S.; Phillips, Mark C.; Hassanein, A.

    2015-07-28

    Expansion dynamics and internal plume structures of fs laser ablated brass plasma in Ar at various pressure levels ranging from vacuum to atmospheric were studied using multitude of diagnostic tools including time resolved and time integrated 2-dimensional imaging, optical time of flight measurements and visible emission spectroscopy. Temporal evolution of excited Cu and Zn species in the plume were imaged using band pass interference filters and compared its hydrodynamic expansion features with spectrally integrated images of the plume. 2D imaging coupled with monochromatic line selection showed several interesting features at various pressure levels which include velocity differences among the plume species, emission intensity distribution, plasma temperature, electron density etc. Plume confinement, enhanced signal intensity, and dual peak structures in time-of-flight profiles were observed at intermediate pressure range of ~10 Torr. Optimum signal to background ratio was also observed in this pressure range. Possible mechanisms for observed changes in plume shape, optical emission intensity and dual peak structures in time-of-flight profiles were discussed.

  13. Molecular dynamics at ambient and elevated pressure of the amorphous pharmaceutical: Nonivamide (pelargonic acid vanillylamide)

    NASA Astrophysics Data System (ADS)

    Wojnarowska, Z.; Hawelek, L.; Paluch, M.; Sawicki, W.; Ngai, K. L.

    2011-01-01

    Broadband dielectric spectroscopy was employed to investigate the relaxation dynamics of supercooled and glassy nonivamide—the synthetic form of capsaicin being the most spicy-hot substance known to man. The material is of great importance in the pharmaceutical industry because it has wide usage in the medical field for relief of pain, and more recently it has been shown to be effective in fighting cancers. Dielectric measurements carried out at various isobaric and isothermal conditions (pressure up to 400 MPa) revealed very narrow α-loss peak and unresolved secondary relaxations appearing in the form of an excess wing on the high frequency flank. Moreover, our studies have shown the shape of dielectric loss spectrum at any fixed loss peak frequency is invariant to different combinations of temperature and pressure, i.e., validity of the time-temperature-pressure superpositioning. We also found the fragility index is nearly constant on varying pressure. This property is likely due to the unusual structure of nonivamide, which has a part characteristic of van der Waals glass-former and another part characteristic of hydrogen-bonded glass-former.

  14. Characteristics of low-temperature plasma ionization for ambient mass spectrometry compared to electrospray ionization and atmospheric pressure chemical ionization.

    PubMed

    Albert, Anastasia; Engelhard, Carsten

    2012-12-18

    Ambient desorption/ionization mass spectrometry (ADI-MS) is an attractive method for direct analysis with applications in homeland security, forensics, and human health. For example, low-temperature plasma probe (LTP) ionization was successfully used to detect, e.g., explosives, drugs, and pesticides directly on the target. Despite the fact that the field is gaining significant attention, few attempts have been made to classify ambient ionization techniques based on their ionization characteristics and performance compared to conventional ionization sources used in mass spectrometry. In the present study, relative ionization efficiencies (RIEs) for a large group of compound families were determined with LTP-Orbitrap-MS and compared to those obtained with electrospray ionization mass spectrometry (ESI-MS) and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). RIEs were normalized against one reference compound used across all methods to ensure comparability of the results. Typically, LTP analyte ionization through protonation/deprotonation (e.g., 4-acetamidophenol) was observed; in some cases (e.g., acenaphthene) radicals were formed. Amines, amides, and aldehydes were ionized successfully with LTP. A benefit of LTP over conventional methods is the possibility to successfully ionize PAHs and imides. Here, the studied model compounds could be detected by neither APCI nor ESI. LTP is a relatively soft ionization method because little fragmentation of model compounds was observed. It is considered to be an attractive method for the ionization of low molecular weight compounds over a relatively wide polarity range. PMID:23134531

  15. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

    NASA Astrophysics Data System (ADS)

    Feng Tao, Franklin; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ˜10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

  16. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

    NASA Astrophysics Data System (ADS)

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ~10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

  17. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies.

    PubMed

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ∼10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified. PMID:23556828

  18. Stabilization of HfB12 in Y1-xHfxB12 under Ambient Pressure.

    PubMed

    Akopov, Georgiy; Yeung, Michael T; Turner, Christopher L; Li, Rebecca L; Kaner, Richard B

    2016-05-16

    Alloys of metal dodecaborides-YB12 with HfB12-were prepared via arc-melting in order to stabilize the metastable HfB12 high-pressure phase under ambient pressure. Previously, HfB12 had been synthesized only under high-pressure (6.5 GPa). Powder X-ray diffraction (PXRD) and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the purity and phase composition of the prepared samples. The solubility limit for HfB12 in Y1-xHfxB12 (cubic UB12 structure type) was determined to be ∼35 at. % Hf by PXRD and EDS analysis. The value of the cubic unit cell parameter (a) changed from 7.505 Å (pure YB12) to 7.454 Å across the solid solution range. Vickers hardness increased from 40.9 ± 1.6 GPa for pure YB12 to 45.0 ± 1.9 GPa under an applied load of 0.49 N for the Y1-xHfxB12 solid solution composition with ∼28 at. % Hf, suggesting both solid solution hardening and extrinsic hardening due to the formation of secondary phases of hafnium. PMID:27115173

  19. Pressure-induced collapsed-tetragonal phase in SrCo2As2 at ambient temperature

    NASA Astrophysics Data System (ADS)

    Jayasekara, W. T.; Kaluarachchi, U. S.; Ueland, B. G.; Pandey, A.; Lee, Y. B.; Taufour, V.; Sapkota, A.; Kothapalli, K.; Sangeetha, N. S.; Bud'Ko, S. L.; Harmon, B. N.; Canfield, P. C.; Johnston, D. C.; Kreyssig, A.; Goldman, A. I.; Fabbris, G.; Feng, Y.; Veiga, L. S. I.; Dos Santos, A. M.

    Our recent high-energy (HE) high-pressure (HP) x-ray powder diffraction measurements on tetragonal (T) SrCo2As2 have revealed a first-order pressure-induced structural phase transition to a collapsed tetragonal (cT) phase with a reduction in c by -7.9% and the c / a ratio by -9.9%. The T and cT phases coexist for applied pressures 6 GPa to 18 GPa at 7 K. Resistance measurements up to 5.9 GPa and down to 1.8 K signatures likely associated with the cT phase above 5.5 GPa and found no evidence for superconductivity. Neutron diffraction data show no evidence of magnetic order up to 1.1 GPa. Here, we show that the T to cT transition occurs around 6.8 GPa at ambient temperature, and that the transition is nearly temperature-independent from 300 K down to 7 K, which indicates a steep p - T phase line. Work at Ames Lab. was supported by US DOE, BES, DMSE under DE-AC02-07CH11358. This research used resources at the APS and ORNL, US DOE, SC, User Facilities.

  20. Laser-induced breakdown spectroscopy on metallic samples at very low temperature in different ambient gas pressures

    NASA Astrophysics Data System (ADS)

    El-Saeid, R. H.; Abdelhamid, M.; Harith, M. A.

    2016-02-01

    Analysis of metals at very low temperature adopting laser-induced breakdown spectroscopy (LIBS) is greatly beneficial in space exploration expeditions and in some important industrial applications. In the present work, the effect of very low sample temperature on the spectral emission intensity of laser-induced plasma under both atmospheric pressure and vacuum has been studied for different bronze alloy samples. The sample was cooled down to liquid nitrogen (LN) temperature 77 K in a special vacuum chamber. Laser-induced plasma has been produced onto the sample surface using the fundamental wavelength of Nd:YAG laser. The optical emission from the plasma is collected by an optical fiber and analyzed by an echelle spectrometer combined with an intensified CCD camera. The integrated intensities of certain spectral emission lines of Cu, Pb, Sn, and Zn have been estimated from the obtained LIBS spectra and compared with that measured at room temperature. The laser-induced plasma parameters (electron number density Ne and electron temperature Te) were investigated at room and liquid nitrogen temperatures for both atmospheric pressure and vacuum ambient conditions. The results suggest that reducing the sample temperature leads to decrease in the emission line intensities under both environments. Plasma parameters were found to decrease at atmospheric pressure but increased under vacuum conditions.

  1. 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.

  2. Pressure drop of two-phase dry-plug flow in round mini-channels: Effect of moving contact line

    SciTech Connect

    Lee, Chi Young; Lee, Sang Yong

    2010-01-15

    In the present experimental study, the pressure drop of the two-phase dry-plug flow (dry wall condition at the gas portions) in round mini-channels was investigated. The air-water mixtures were flowed through the round mini-channels made of polyurethane and Teflon, respectively, with their inner diameters ranging from 1.62 to 2.16 mm. In the dry-plug flow regime, the pressure drop measured became larger either by increasing the liquid superficial velocity or by decreasing the gas superficial velocity due to the increase of the number of the moving contact lines in the test section. In such a case, the role of the moving contact lines turned out to be significant. Therefore, a pressure drop model of dry-plug flow was proposed through modification of the dynamic contact angle analysis taking account of the energy dissipation by the moving contact lines, which represents the experimental data within the mean deviation of 4%. (author)

  3. A constant altitude flight survey method for mapping atmospheric ambient pressures and systematic radar errors

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Ehernberger, L. J.

    1985-01-01

    The flight test technique described uses controlled survey runs to determine horizontal atmospheric pressure variations and systematic altitude errors that result from space positioning measurements. The survey data can be used not only for improved air data calibrations, but also for studies of atmospheric structure and space positioning accuracy performance. The examples presented cover a wide range of radar tracking conditions for both subsonic and supersonic flight to an altitude of 42,000 ft.

  4. Ice phases under ambient and high pressure: Insights from density functional theory

    NASA Astrophysics Data System (ADS)

    Fang, Yuan; Xiao, Bing; Tao, Jianmin; Sun, Jianwei; Perdew, John P.

    2013-06-01

    Water is common and plays a crucial role in biological, chemical, and physical processes, but its crystalline or ice state has a complicated structure. In this work, we study the lattice mismatch challenge for ice nucleation on silver iodide, the sublimation energy for different ice phases, and the structural phase-transition pressures of ice, with various density functionals. Our calculations show that the recently developed meta-generalized gradient approximation made simple (MGGA_MS) yields a lattice mismatch (3%) of hexagonal ice (ice Ih) with β-AgI in good agreement with experiment (2%), significantly better than the Perdew-Burke-Ernzerhof (PBE) GGA mismatch (6%). MGGA_MS is a computationally efficient semilocal functional that incorporates intermediate-range van der Waals (vdW) interaction, which, overall, performs well for ice and may be expected to improve upon PBE for liquid water. While MGGA_MS predicts the most realistic volumes and volume changes in the phase transitions of ice Ih to trigonal ice (ice II) and tetragonal ice (ice VIII), a more accurate description of some other properties of the higher-pressure phases (ice II and ice VIII) is provided by some functionals that include long-range vdW corrections (e.g., revised Tao-Perdew-Staroverov-Scuseria+vdW for sublimation energy and optB88-vdW for transition pressure).

  5. Modelling of heat and mass transfer in a granular medium during high-temperature air drying. Effect of the internal gas pressure

    NASA Astrophysics Data System (ADS)

    Othmani, Hammouda; Hassini, Lamine; Lamloumi, Raja; El Cafsi, Mohamed Afif

    2016-02-01

    A comprehensive internal heat and water transfer model including the gas pressure effect has been proposed in order to improve the industrial high-temperature air drying of inserts made of agglomerated sand. In this model, the internal gas phase pressure effect was made perfectly explicit, by considering the liquid and vapour transfer by filtration and the liquid expulsion at the surface. Wet sand enclosed in a tight cylindrical glass bottle dried convectively at a high temperature was chosen as an application case. The model was validated on the basis of the experimental average water content and core temperature curves for drying trials at different operating conditions. The simulations of the spatio-temporal distribution of internal gas pressure were performed and interpreted in terms of product potential damage. Based on a compromise between the drying time and the pressure increase, a simple drying cycle was implemented in order to optimize the drying process.

  6. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    SciTech Connect

    Narayan, Jagdish Bhaumik, Anagh

    2015-10-01

    We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals.

  7. Effect of nanoscale confinement on freezing of modified water at room temperature and ambient pressure.

    PubMed

    Deshmukh, Sanket; Kamath, Ganesh; Sankaranarayanan, Subramanian K R S

    2014-06-01

    Understanding the phase behavior of confined water is central to fields as diverse as heterogeneous catalysis, corrosion, nanofluidics, and to emerging energy technologies. Altering the state points (temperature, pressure, etc.) or introduction of a foreign surface can result in the phase transformation of water. At room temperature, ice nucleation is a very rare event and extremely high pressures in the GPa-TPa range are required to freeze water. Here, we perform computer experiments to artificially alter the balance between electrostatic and dispersion interactions between water molecules, and demonstrate nucleation and growth of ice at room temperature in a nanoconfined environment. Local perturbations in dispersive and electrostatic interactions near the surface are shown to provide the seed for nucleation (nucleation sites), which lead to room temperature liquid-solid phase transition of confined water. Crystallization of water occurs over several tens of nanometers and is shown to be independent of the nature of the substrate (hydrophilic oxide vs. hydrophobic graphene and crystalline oxide vs. amorphous diamond-like carbon). Our results lead us to hypothesize that the freezing transition of confined water can be controlled by tuning the relative dispersive and electrostatic interaction. PMID:24715572

  8. Boron: a frustrated element. Physical properties at ambient conditions and under pressure from ab-initio calculations

    NASA Astrophysics Data System (ADS)

    Ogitsu, Tadashi; Gygi, Francois; Galli, Giulia

    2004-03-01

    Boron is the only low-Z element in the periodic table whose atomic ground state structure has not yet been fully determined. For example, it is yet unclear whether perfectly pure elemental Boron is stable in an ordered crystalline form and the number of atoms in the unit cell (varying from 315 to about 325) is still the subject of debate. Using ab-initio calculations and supercells with 1260-1280 atoms, we have studied the physical properties of Boron at ambient conditions and under pressure (P). Results about the ionic and electronic structure will be presented, in particular the role of interstitial atoms and the presence of localized states right above the Fermi level will be discussed in detail. The computed equation of state under pressure is in agreement with recent experimental data. At about 120 GPa we observe amorphization, consistent with the results of Ref. [1] at l00 GPa. Amorphization occurs by random deformation of icosahedral units which remain intact; it is accompanied by a delocalization of states near the Fermi level yielding a poorly conducting system. This work was performed under the auspices of the U.S. Dept. of Energy at the University of California/ LLNL under contract no. W-7405-Eng-48. [1] Sanz et al. Phys. Rev. Lett. 89, 245501 (2002)

  9. Preparation of YBa 2Cu 4O 8 by a seeding method at ambient pressure

    NASA Astrophysics Data System (ADS)

    Iwai, Yutaka; Noguchi, Mutsumi; Saito, Hiroshi; Takata, Masasuke

    1991-10-01

    A seeding method was applied to the processing method of YBa 2Cu 4O 8 superconducting oxide (124 phase). Seed of the 124 phase was prepared by the HIP process. Seed with 25 wt.% was mixed with the matrix oxide prepared by decomposition of nitric salt. They were pressed and fired at 850°C under oxygen gas flow (1 atm of oxygen partial pressure). After repeating the firing, the 124 single phase was obtained. The sample of this 124 phase exhibited superconductivity at onset temperature of 82 K and zero resistive point at 76 K. From the matrix oxide (unseeded), however, the 124 phase could not be formed under the same conditions.

  10. Measurement of Apparent Thermal Conductivity of JSC-1A Under Ambient Pressure

    NASA Technical Reports Server (NTRS)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    The apparent thermal conductivity of JSC-1A lunar regolith simulant was measured experimentally using a cylindrical apparatus. Eleven thermocouples were embedded in the simulant bed to obtain the steady state temperature distribution at various radial, axial, and azimuthal locations. The high aspect ratio of a cylindrical geometry was proven to provide a one-dimensional, axisymmetric temperature field. A test series was performed at atmospheric pressure with varying heat fluxes. The radial temperature distribution in each test fit a logarithmic function, indicating a constant thermal conductivity throughout the soil bed. However, thermal conductivity was not constant between tests at different heat fluxes. This variation is attributed to stresses created by thermal expansion of the simulant particles against the rigid chamber wall. Under stress-free conditions (20 deg C), the data suggest a temperature independent apparent conductivity of 0.1961 +/- 0.0070 W/m/ deg C

  11. The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR 1000 plus.

    PubMed

    Bohm, Tim D; Griffin, Sheridan L; DeLuca, Paul M; DeWerd, Larry A

    2005-04-01

    The determination of the air kerma strength of a brachytherapy seed is necessary for effective treatment planning. Well ionization chambers are used on site at therapy clinics to determine the air kerma strength of seeds. In this work, the response of the Standard Imaging HDR 1000 Plus well chamber to ambient pressure is examined using Monte Carlo calculations. The experimental work examining the response of this chamber as well as other chambers is presented in a companion paper. The Monte Carlo results show that for low-energy photon sources, the application of the standard temperature pressure PTP correction factor produces an over-response at the reduced air densities/pressures corresponding to high elevations. With photon sources of 20 to 40 keV, the normalized PTP corrected chamber response is as much as 10% to 20% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. At air densities corresponding to an elevation of 1524 m (5000 ft), the normalized PTP-corrected chamber response is 5% to 10% over unity for these photon sources. With higher-energy photon sources (>100 keV), the normalized PTP corrected chamber response is near unity. For low-energy beta sources of 0.25 to 0.50 MeV, the normalized PTP-corrected chamber response is as much as 4% to 12% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. Higher-energy beta sources (>0.75 MeV) have a normalized PTP corrected chamber response near unity. Comparing calculated and measured chamber responses for common 103Pd- and 125I-based brachytherapy seeds show agreement to within 2.7% and 1.9%, respectively. Comparing MCNP calculated chamber responses with EGSnrc calculated chamber responses show agreement to within 3.1% at photon energies of 20 to 40 keV. We conclude that Monte Carlo transport calculations accurately model the response of this well chamber. Further, applying the standard PTP correction

  12. The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR 1000 Plus

    SciTech Connect

    Bohm, Tim D.; Griffin, Sheridan L.; DeLuca, Paul M. Jr.; DeWerd, Larry A.

    2005-04-01

    The determination of the air kerma strength of a brachytherapy seed is necessary for effective treatment planning. Well ionization chambers are used on site at therapy clinics to determine the air kerma strength of seeds. In this work, the response of the Standard Imaging HDR 1000 Plus well chamber to ambient pressure is examined using Monte Carlo calculations. The experimental work examining the response of this chamber as well as other chambers is presented in a companion paper. The Monte Carlo results show that for low-energy photon sources, the application of the standard temperature pressure P{sub TP} correction factor produces an over-response at the reduced air densities/pressures corresponding to high elevations. With photon sources of 20 to 40 keV, the normalized P{sub TP} corrected chamber response is as much as 10% to 20% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. At air densities corresponding to an elevation of 1524 m (5000 ft), the normalized P{sub TP}-corrected chamber response is 5% to 10% over unity for these photon sources. With higher-energy photon sources (>100 keV), the normalized P{sub TP} corrected chamber response is near unity. For low-energy {beta} sources of 0.25 to 0.50 MeV, the normalized P{sub TP}-corrected chamber response is as much as 4% to 12% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. Higher-energy {beta} sources (>0.75 MeV) have a normalized P{sub TP} corrected chamber response near unity. Comparing calculated and measured chamber responses for common {sup 103}Pd- and {sup 125}I-based brachytherapy seeds show agreement to within 2.7% and 1.9%, respectively. Comparing MCNP calculated chamber responses with EGSnrc calculated chamber responses show agreement to within 3.1% at photon energies of 20 to 40 keV. We conclude that Monte Carlo transport calculations accurately model the response of this well

  13. Dry and Wet Friction of Plagioclase: Pure Cataclastic Flow(CF) vs. CF with Concurrent Pressure Solution

    NASA Astrophysics Data System (ADS)

    He, C.; Tan, W.

    2015-12-01

    To distinguish different deformation mechanisms at hydrothermal conditions, friction experiments of plagioclase under nominally dry conditions were compared with that at hydrothermal conditions documented in a previous study[He et al.,2013]. Preliminary result[Tan and He, 2008] shows that the rate dependence of plagioclase under confining pressure of 150MPa and nominally dry conditions is velocity strengthening at temperatures of 50-600oC, in contrast to the full velocity weakening at hydrothermal conditions. Here a) we conducted data fitting to the rate and state friction law to compare with the hydrothermal case; b) microstructural comparison was performed to understand the difference between the dry and wet conditions in the operative deformation mechanisms. The evolution effect (b value) under dry conditions exhibits much smaller values than that at wet conditions, and in contrast to the increasing trend at wet conditions, b values under dry conditions have a decreasing trend as temperature increases, from ~0.007 at 300oC down to 0 at 600oC. The direct effect (a value) at dry conditions has a peak of ~0.01 at 300oC and decreases to a level of 0.007-0.008 at higher temperatures, in contrast to the increasing trend seen at hydrothermal conditions. In the dry case, microstructure at temperatures of 300-600oC transitions gradually from a fabric characterized by localized Riedel shear zones to pervasive shear deformation, with the grain size reduced to a level of 1-3 micron in a submicron matrix in the latter case, corresponding to a lower porosity. The close association between porosity evolution and that of state variable revealed in previous studies[Morrow and Byerlee, 1989; Marone et al.,1990] suggests that the porosity change contributes largely to the evolution effect in addition to plasticity at intergranular contacts, probably due to gradual switching between different densities of packing. Our dry experiments indicate a cataclastic flow where the evolution

  14. ZK-5: a CO₂-selective zeolite with high working capacity at ambient temperature and pressure.

    PubMed

    Liu, Qingling; Pham, Trong; Porosoff, Marc D; Lobo, Raul F

    2012-11-01

    The increased carbon dioxide concentration in the atmosphere caused by combustion of fossil fuels has been a leading contributor to global climate change. The adsorption-driven pressure or vacuum swing (PSA/VSA) processes are promising as affordable means for the capture and separation of CO₂. Herein, an 8-membered-ring zeolite ZK-5 (Framework Type Code: KFI) exchanged with different cations (H⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺) was synthesized as novel CO₂ adsorbent. The samples were characterized by SEM, energy-dispersive X-ray spectroscopy (EDAX), XRD, and gas adsorption (CO₂ and N₂). The Toth adsorption model was used to describe the CO₂ adsorption isotherms, and the isosteric heats of adsorption were calculated. CO₂ capture adsorbent evaluation criteria such as working capacity, regenerability and CO₂/N₂ selectivity were applied to evaluate the zeolite adsorbents for PSA/VSA applications. The in situ FTIR CO₂ adsorption spectra show that physisorption accounts for the largest fraction of the total CO₂ adsorbed. The CO₂ adsorption analysis shows that Mg-ZK-5 is the most promising adsorbent for PSA applications with the highest working capacity (ΔN(CO₂)=2.05 mmol g⁻¹), excellent selectivity (α(CO₂/N₂)=121), and low isosteric heat. Li-, Na- and K-ZK-5 with good working capacity (ΔN(CO₂)=1.55-2.16 mmol g⁻¹) and excellent selectivity (α(CO₂/N₂)=103-128) are promising CO₂ adsorbents for the VSA working region. PMID:22907818

  15. Near-ambient pressure XPS of high-temperature surface chemistry in Sr2Co2O5 thin films

    DOE PAGESBeta

    Hong, Wesley T.; Stoerzinger, Kelsey; Crumlin, Ethan J.; Mutoro, Eva; Jeen, Hyoung Jeen; Lee, Ho Nyung; Shao-Horn, Yang

    2016-02-11

    Transition metal perovskite oxides are promising electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells, but a lack of fundamental understanding of oxide surfaces impedes the rational design of novel catalysts with improved device efficiencies. In particular, understanding the surface chemistry of oxides is essential for controlling both catalytic activity and long-term stability. Thus, elucidating the physical nature of species on perovskite surfaces and their catalytic enhancement would generate new insights in developing oxide electrocatalysts. In this article, we perform near-ambient pressure XPS of model brownmillerite Sr2Co2O5 (SCO) epitaxial thin films with different crystallographic orientations. Detailed analysis of themore » Co 2p spectra suggests that the films lose oxygen as a function of temperature. Moreover, deconvolution of the O 1s spectra shows distinct behavior for (114)-oriented SCO films compared to (001)-oriented SCO films, where an additional bulk oxygen species is observed. These findings indicate a change to a perovskite-like oxygen chemistry that occurs more easily in (114) SCO than (001) SCO, likely due to the orientation of oxygen vacancy channels out-of-plane with respect to the film surface. This difference in surface chemistry is responsible for the anisotropy of the oxygen surface exchange coefficient of SCO and may contribute to the enhanced ORR kinetics of La0.8Sr0.2CoO3-δ thin films by SCO surface particles observed previously.« less

  16. Reverse Water-Gas Shift or Sabatier Methanation on Ni(110)? Stable Surface Species at Near-Ambient Pressure.

    PubMed

    Roiaz, Matteo; Monachino, Enrico; Dri, Carlo; Greiner, Mark; Knop-Gericke, Axel; Schlögl, Robert; Comelli, Giovanni; Vesselli, Erik

    2016-03-30

    The interaction of CO, CO2, CO + H2, CO2 + H2, and CO + CO2 + H2 with the nickel (110) single crystal termination has been investigated at 10(-1) mbar in situ as a function of the surface temperature in the 300-525 K range by means of infrared-visible sum frequency generation (IR-vis SFG) vibrational spectroscopy and by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). Several stable surface species have been observed and identified. Besides atomic carbon and precursors for graphenic C phases, five nonequivalent CO species have been distinguished, evidencing the role of coadsorption effects with H and C atoms, of H-induced activation of CO, and of surface reconstruction. At low temperature, carbonate species produced by the interaction of CO2 with atomic oxygen, which stems from the dissociation of CO2 into CO + O, are found on the surface. A metastable activated CO2(-) species is also detected, being at the same time a precursor state toward dissociation into CO and O in the reverse water-gas shift mechanism and a reactive species that undergoes direct conversion in the Sabatier methanation process. Finally, the stability of ethylidyne is deduced on the basis of our spectroscopic observations. PMID:26954458

  17. Reactivity of Au nanoparticles supported over SiO2 and TiO2 studiedby ambient pressure photoelectron spectroscopy

    SciTech Connect

    Herranz, Tirma; Deng, Xingyi; Cabot, Andreu; Alivisatos, Paul; Liu, Zhi; Soler-Illia, Galo; Salmeron, Miquel

    2009-04-15

    The influence of the metal cluster size and the identity of the support on the reactivity of gold based catalysts have been studied in the CO oxidation reaction. To overcome the structural complexity of the supported catalysts, gold nanoparticles synthesized from colloidal chemistry with precisely controlled size have been used. Those particles were supported over SiO{sub 2} and TiO{sub 2} and their catalytic activity was measured in a flow reactor. The reaction rate was dependent on the particle size and the support, suggesting two reaction pathways in the CO oxidation reaction. In parallel, ambient pressure photoelectron spectroscopy (APPS) has been performed under reaction conditions using bidimensional model catalysts prepared upon supporting the Au nanoparticles over planar polycrystalline SiO{sub 2} and TiO{sub 2} thin films by means of the Langmuir-Blodgett (LB) technique to mimic the characteristic of the powder samples. In this way, the catalytically active surface was characterized under true reaction conditions, revealing that during CO oxidation gold remains in the metallic state.

  18. Analysis of local bond-orientational order for liquid gallium at ambient pressure: Two types of cluster structures.

    PubMed

    Chen, Lin-Yuan; Tang, Ping-Han; Wu, Ten-Ming

    2016-07-14

    In terms of the local bond-orientational order (LBOO) parameters, a cluster approach to analyze local structures of simple liquids was developed. In this approach, a cluster is defined as a combination of neighboring seeds having at least nb local-orientational bonds and their nearest neighbors, and a cluster ensemble is a collection of clusters with a specified nb and number of seeds ns. This cluster analysis was applied to investigate the microscopic structures of liquid Ga at ambient pressure (AP). The liquid structures studied were generated through ab initio molecular dynamics simulations. By scrutinizing the static structure factors (SSFs) of cluster ensembles with different combinations of nb and ns, we found that liquid Ga at AP contained two types of cluster structures, one characterized by sixfold orientational symmetry and the other showing fourfold orientational symmetry. The SSFs of cluster structures with sixfold orientational symmetry were akin to the SSF of a hard-sphere fluid. On the contrary, the SSFs of cluster structures showing fourfold orientational symmetry behaved similarly as the anomalous SSF of liquid Ga at AP, which is well known for exhibiting a high-q shoulder. The local structures of a highly LBOO cluster whose SSF displayed a high-q shoulder were found to be more similar to the structure of β-Ga than those of other solid phases of Ga. More generally, the cluster structures showing fourfold orientational symmetry have an inclination to resemble more to β-Ga. PMID:27421419

  19. Investigating the effect of additional gases in an atmospheric-pressure helium plasma jet using ambient mass spectrometry

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu; Bradley, James W.

    2015-01-01

    Using ambient mass spectrometry, positive and negative ions created in an atmospheric-pressure plasma jet have been detected for a variation of different traces gases (Ar, N2, and O2) added to the flow, downstream of the main helium discharge plasma. We find that such additions can change the chemistry in the outflow plasma plume. For instance, small amounts of O2 increases the formation of positive ion clusters, e.g., water clusters H+(H2O)n (with n up to 5) through hydration reactions, but decreases the intensity of heavy negative ions detected. With the addition of Ar and N2 we see a marked decrease in the intensity of negative ions in the plume but with increased Ar+ and nitrous oxide ions (e.g., N2O+) for the two cases respectively. From broadband optical emission measurements of the glowing plasma we see that the relative emission intensity of OH radical were changed with addition of the four different gases but the emission spectra were not changed. A calculation of rotational temperature of OH radicals, indicates that the gas temperatures is about 290 K for the four different gas mixture cases.

  20. Experimental Determination of Spatial and Temporal Discharge Parameters for an Ambient Pressure Dielectric Barrier Discharge in Helium

    NASA Astrophysics Data System (ADS)

    Bures, Brian; Bourham, Mohamed

    2004-11-01

    Ambient pressure Dielectric Barrier Discharges (DBD's) are studied for a number of applications. Barrier discharges composed primarily of inert gases are potentially useful for the production of intense excimer light, sterilization of thermally sensitive materials and control of insects for quarantine. The neutral bremsstrahlung technique is used to determine spatial variations of electron density and electron temperature in a parallel plate, helium (99.9% by vol) dielectric barrier discharge operated at an average power density between 50 and 75 mW/cm^3. The applied frequency is varied between 2 kHz and 6 kHz. The time average electron density suggests a more intense discharge near the surface of the electrodes than the bulk of the discharge for all frequencies and power densities. When moving parallel to the electrodes, the electron temperature remains constant, while the electron density is constant within 20% of the average value. A monochromator tuned to a nitrogen ion line (391.4 nm) and a helium line (706.5 nm) has a more intense emission when the electrode is negatively biased.

  1. Analysis of local bond-orientational order for liquid gallium at ambient pressure: Two types of cluster structures

    NASA Astrophysics Data System (ADS)

    Chen, Lin-Yuan; Tang, Ping-Han; Wu, Ten-Ming

    2016-07-01

    In terms of the local bond-orientational order (LBOO) parameters, a cluster approach to analyze local structures of simple liquids was developed. In this approach, a cluster is defined as a combination of neighboring seeds having at least nb local-orientational bonds and their nearest neighbors, and a cluster ensemble is a collection of clusters with a specified nb and number of seeds ns. This cluster analysis was applied to investigate the microscopic structures of liquid Ga at ambient pressure (AP). The liquid structures studied were generated through ab initio molecular dynamics simulations. By scrutinizing the static structure factors (SSFs) of cluster ensembles with different combinations of nb and ns, we found that liquid Ga at AP contained two types of cluster structures, one characterized by sixfold orientational symmetry and the other showing fourfold orientational symmetry. The SSFs of cluster structures with sixfold orientational symmetry were akin to the SSF of a hard-sphere fluid. On the contrary, the SSFs of cluster structures showing fourfold orientational symmetry behaved similarly as the anomalous SSF of liquid Ga at AP, which is well known for exhibiting a high-q shoulder. The local structures of a highly LBOO cluster whose SSF displayed a high-q shoulder were found to be more similar to the structure of β-Ga than those of other solid phases of Ga. More generally, the cluster structures showing fourfold orientational symmetry have an inclination to resemble more to β-Ga.

  2. Coupled fluid-thermal analysis of low-pressure sublimation and condensation with application to freeze-drying

    NASA Astrophysics Data System (ADS)

    Ganguly, Arnab

    Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of bio-pharmaceuticals for removal of solvents by sublimation. The goal of the process is to provide a stable dosage form by removing the solvent in such a way that the sensitive molecular structure of the active substance is least disturbed. The vacuum environment presents unique challenges for understanding and controlling heat and mass transfer in the process. As a result, the design of equipment and associated processes has been largely empirical, slow and inefficient. A comprehensive simulation framework to predict both, process and equipment performance is critical to improve current practice. A part of the dissertation is aimed at performing coupled fluid-thermal analysis of low-pressure sublimation-condensation processes typical of freeze-drying technologies. Both, experimental and computational models are used to first understand the key heat transfer modes during the process. A modeling and computational framework, validated with experiments for analysis of sublimation, water-vapor flow and condensation in application to pharmaceutical freeze-drying is developed. Augmented with computational fluid dynamics modeling, the simulation framework presented here allows to predict for the first time, dynamic product/process conditions taking into consideration specifics of equipment design. Moreover, by applying the modeling framework to process design based on a design-space approach, it has demonstrated that there is a viable alternative to empiricism.

  3. Development of open air silicon deposition technology by silane-free atmospheric pressure plasma enhanced chemical transport under local ambient gas control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2016-07-01

    Open air silicon deposition was performed by combining silane-free atmospheric pressure plasma-enhanced chemical transport and a newly developed local ambient gas control technology. The effect of air contamination on silicon deposition was investigated using a vacuum chamber, and the allowable air contamination level was confirmed to be 3 ppm. The capability of the local ambient gas control head was investigated numerically and experimentally. A safe and clean process environment with air contamination less than 1 ppm was achieved. Combining these technologies, a microcrystalline silicon film was deposited in open air, the properties of which were comparable to those of silicon films deposited in a vacuum chamber.

  4. First-principles calculations of solid and liquid aluminum optical absorption spectra near the melting curve: Ambient and high-pressure results

    DOE PAGESBeta

    Ogitsu, Tadashi; Benedict, Lorin X.; Schwegler, Eric; Draeger, Erik W.; Prendergast, David

    2009-12-04

    Here, we present ab initio calculations of the linear optical conductivity of heated Al at ambient pressure and at the conditions relevant for shock melting (P~125 GPa, T~5000 K). It is shown that the visible and near-UV optical spectrum is very sensitive to the phase (fcc solid versus liquid) of Al for both P=0 and 125 GPa. The ambient-P results confirm an earlier prediction and the results of a recent experiment while the high-(P,T) results allow us to conclude that in situ measurements of optical constants should be able to diagnose the shock melting of Al.

  5. First-principles calculations of solid and liquid aluminum optical absorption spectra near the melting curve: Ambient and high-pressure results

    SciTech Connect

    Ogitsu, Tadashi; Benedict, Lorin X.; Schwegler, Eric; Draeger, Erik W.; Prendergast, David

    2009-12-04

    Here, we present ab initio calculations of the linear optical conductivity of heated Al at ambient pressure and at the conditions relevant for shock melting (P~125 GPa, T~5000 K). It is shown that the visible and near-UV optical spectrum is very sensitive to the phase (fcc solid versus liquid) of Al for both P=0 and 125 GPa. The ambient-P results confirm an earlier prediction and the results of a recent experiment while the high-(P,T) results allow us to conclude that in situ measurements of optical constants should be able to diagnose the shock melting of Al.

  6. Competitiveness of small power plants using ambient pressure, air-blown gasifiers. Final report. [Seven 50 MW designs using fuel gas, fuel oil, natural gas and coal

    SciTech Connect

    Boulay, R.B.; Chen, H.T.; Harvey, L.E.; Losovsky, M.L.

    1986-02-01

    Small power plants have become more attractive to utilities recently for a variety of reasons, including the desire to minimize new plant investment and to tailor increases in generation base to smaller annual load growths. The study presented herein is an analysis and comparison of seven different 50 MW commercially available power plants designs, including four utilizing ambient pressure, air-blown, fixed-bed coal gasifiers for fuel supply. Plant designs, capital costs, and busbar electricity costs for each plant are presented. The results of the study indicate that nominal 50 MW coal gasification based power plants, when using commercially available, ambient pressure, air-blown, fixed-bed gasifiers, are not competitive with conventional coal-fired steam plants or combined cycle plants fueled with fuel oil or natural gas. Capital costs, heat rates, and operating costs are higher for the coal gasification based plants. This leads to costs-of-electricity for gasification based plants that range from 18 to 59% higher than costs of electricity produced in conventional plants. The two major influences leading to high costs of the gasification based plants are the small size of a gasification train (about 5 MW) and the need to compress the ambient pressure gas to required combustion pressure. 47 figs., 89 tabs.

  7. Effects of ambient and acute partial pressures of ozone on leaf net CO sub 2 assimilation of field-grown Vitis vinifera L

    SciTech Connect

    Roper, T.R.; Williams, L.E. Kearney Agricultural Center, Parlier, CA )

    1989-12-01

    Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O{sub 3} partial pressures reduced net CO{sub 2} assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O{sub 3} for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O{sub 3} when compared to the controls after 5 hours. Intercellular CO{sub 2} partial pressure (c{sub i}) was lower for leaves exposed to 0.2 micropascals per pascal O{sub 3} when compared to the controls, while c{sub i} of the leaves treated with 0.6 micropascals per pascal of O{sub 3} increased during the fumigation. The long-term effects of ambient O{sub 3} and short-term exposure to acute levels of O{sub 3} reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances.

  8. Effects of Ambient and Acute Partial Pressures of Ozone on Leaf Net CO2 Assimilation of Field-Grown Vitis vinifera L. 1

    PubMed Central

    Roper, Teryl R.; Williams, Larry E.

    1989-01-01

    Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O3 partial pressures reduced net CO2 assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O3 for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O3 when compared to the controls after 5 hours. Intercellular CO2 partial pressure (ci) was lower for leaves exposed to 0.2 micropascals per pascal O3 when compared to the controls, while ci of the leaves treated with 0.6 micropascals per pascal of 03 increased during the fumigation. The long-term effects of ambient O3 and short-term exposure to acute levels of O3 reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances. PMID:16667208

  9. Ultrasensitive ambient mass spectrometric analysis with a pin-to-capillary flowing atmospheric-pressure afterglow source.

    PubMed

    Shelley, Jacob T; Wiley, Joshua S; Hieftje, Gary M

    2011-07-15

    The advent of ambient desorption/ionization mass spectrometry has resulted in a strong interest in ionization sources that are capable of direct analyte sampling and ionization. One source that has enjoyed increasing interest is the flowing atmospheric-pressure afterglow (FAPA). The FAPA has been proven capable of directly desorbing/ionizing samples in any phase (solid, liquid, or gas) and with impressive limits of detection (<100 fmol). The FAPA was also shown to be less affected by competitive-ionization matrix effects than other plasma-based sources. However, the original FAPA design exhibited substantial background levels, cluttered background spectra in the negative-ion mode, and significant oxidation of aromatic analytes, which ultimately compromised analyte identification and quantification. In the present study, a change in the FAPA configuration from a pin-to-plate to a pin-to-capillary geometry was found to vastly improve performance. Background signals in positive- and negative-ionization modes were reduced by 89% and 99%, respectively. Additionally, the capillary anode strongly reduced the amount of atomic oxygen that could cause oxidation of analytes. Temperatures of the gas stream that interacts with the sample, which heavily influences desorption capabilities, were compared between the two sources by means of IR thermography. The performance of the new FAPA configuration is evaluated through the determination of a variety of compounds in positive- and negative-ion mode, including agrochemicals and explosives. A detection limit of 4 amol was found for the direct determination of the agrochemical ametryn and appears to be spectrometer-limited. The ability to quickly screen for analytes in bulk liquid samples with the pin-to-capillary FAPA is also shown. PMID:21627097

  10. Ultrasensitive Ambient Mass Spectrometric Analysis with a Pin-to-Capillary Flowing Atmospheric-Pressure Afterglow Source

    PubMed Central

    Shelley, Jacob T.; Wiley, Joshua S.; Hieftje, Gary M.

    2011-01-01

    The advent of ambient desorption/ionization mass spectrometry has resulted in a strong interest in ionization sources that are capable of direct analyte sampling and ionization. One source that has enjoyed increasing interest is the Flowing Atmospheric-Pressure Afterglow (FAPA). FAPA has been proven capable of directly desorbing/ionizing samples in any phase (solid, liquid, or gas) and with impressive limits of detection (<100 fmol). The FAPA was also shown to be less affected by competitive-ionization matrix effects than other plasma-based sources. However, the original FAPA design exhibited substantial background levels, cluttered background spectra in the negative-ion mode, and significant oxidation of aromatic analytes, which ultimately compromised analyte identification and quantification. In the present study, a change in the FAPA configuration from a pin-to-plate to a pin-to-capillary geometry was found to vastly improve performance. Background signals in positive- and negative-ionization modes were reduced by 89% and 99%, respectively. Additionally, the capillary anode strongly reduced the amount of atomic oxygen that could cause oxidation of analytes. Temperatures of the gas stream that interacts with the sample, which heavily influences desorption capabilities, were compared between the two sources by means of IR thermography. The performance of the new FAPA configuration is evaluated through the determination of a variety of compounds in positive- and negative-ion mode, including agrochemicals and explosives. A detection limit of 4 amol was found for the direct determination of the agrochemical ametryn, and appears to be spectrometer-limited. The ability to quickly screen for analytes in bulk liquid samples with the pin-to-capillary FAPA is also shown. PMID:21627097

  11. Low Shock Pressure Recovery Experiments with Dry Sandstone Samples Within the MEMIN Research Program

    NASA Astrophysics Data System (ADS)

    Schmitt, R. T.; Reimold, W. U.; Hornemann, U.

    2011-03-01

    Within the MEMIN program shock recovery experiments with Seeberger sandstone were carried out in the pressure range of 5 to 12.5 GPa to investigate shock effects in quartz and the influence of porosity on progressive shock metamorphism.

  12. Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure

    NASA Astrophysics Data System (ADS)

    Wojnarowska, Z.; Swiety-Pospiech, A.; Grzybowska, K.; Hawelek, L.; Paluch, M.; Ngai, K. L.

    2012-04-01

    The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M″(f ) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across Tg. The situation is analogous to many non-ionic glass-formers showing the presence of the structural α-relaxation together with the Johari-Goldstein (JG) β-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary α-conductivity relaxation and the secondary β-conductivity relaxation, respectively. The analogy of the β-conductivity relaxation in procaine HCl and procainamide HCl with JG β-relaxation in non-ionic glass-formers goes further by the finding that the β-conductivity is strongly related to the α-conductivity relaxation at temperatures above and below Tg. At elevated pressure but compensated by raising temperature to maintain α-conductivity relaxation time constant, the data show invariance of the ratio between the β- and the α-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the β-conductivity relaxation has fundamental importance and is indispensable as the precursor of the α-conductivity relaxation, analogous to the relation found

  13. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    SciTech Connect

    Butcher, Derek Robert

    2010-06-01

    High Pressure Scanning Tunneling Microscopy (HP-STM) and Ambient Pressure X-ray Photoelectron Spectroscopy were used to study the structural properties and catalytic behavior of noble metal surfaces at high pressure. HP-STM was used to study the structural rearrangement of the top most atomic surface layer of the metal surfaces in response to changes in gas pressure and reactive conditions. AP-XPS was applied to single crystal and nanoparticle systems to monitor changes in the chemical composition of the surface layer in response to changing gas conditions. STM studies on the Pt(100) crystal face showed the lifting of the Pt(100)-hex surface reconstruction in the presence of CO, H2, and Benzene. The gas adsorption and subsequent charge transfer relieves the surface strain caused by the low coordination number of the (100) surface atoms allowing the formation of a (1 x 1) surface structure commensurate with the bulk terminated crystal structure. The surface phase change causes a transformation of the surface layer from hexagonal packing geometry to a four-fold symmetric surface which is rich in atomic defects. Lifting the hex reconstruction at room temperature resulted in a surface structure decorated with 2-3 nm Pt adatom islands with a high density of step edge sites. Annealing the surface at a modest temperature (150 C) in the presence of a high pressure of CO or H2 increased the surface diffusion of the Pt atoms causing the adatom islands to aggregate reducing the surface concentration of low coordination defect sites. Ethylene hydrogenation was studied on the Pt(100) surface using HP-STM. At low pressure, the lifting of the hex reconstruction was observed in the STM images. Increasing the ethylene pressure to 1 Torr, was found to regenerate the hexagonally symmetric reconstructed phase. At room temperature ethylene undergoes a structural rearrangement to form ethylidyne. Ethylidyne preferentially binds at the three-fold hollow sites, which

  14. Microautoradiography of Water-Soluble Compounds in Plant Tissue after Freeze-Drying and Pressure Infiltration with Epoxy Resin

    PubMed Central

    Vogelmann, Thomas C.; Dickson, Richard E.

    1982-01-01

    It is difficult to retain and localize radioactive, water-soluble compounds within plant cells. Existing techniques retain water-soluble compounds with varying rates of efficiency and are limited to processing only a few samples at one time. We developed a modified pressure infiltration technique for the preparation of microautoradiographs of 14C-labeled, water-soluble compounds in plant tissue. Samples from cottonwood (Populus deltoides Bartr. ex Marsh.) labeled with 14C were excised, quick frozen in liquid N2, freeze-dried at −50°C, and pressure-infiltrated with epoxy resin without intermediate solvents or prolonged incubation times. The technique facilitates the mass processing of samples for microautoradiography, gives good cellular retention of labeled water-soluble compounds, and is highly reproducible. Images Fig. 2 PMID:16662542

  15. One-Pot Template-Free Synthesis of Cu-MOR Zeolite toward Efficient Catalyst Support for Aerobic Oxidation of 5-Hydroxymethylfurfural under Ambient Pressure.

    PubMed

    Zhang, Wei; Xie, Jingyan; Hou, Wei; Liu, Yangqing; Zhou, Yu; Wang, Jun

    2016-09-01

    Supported catalysts are widely studied, and exploring new promising supports is significant to access more applications. In this work, novel copper-containing MOR-type zeolites Cu-MOR were synthesized in a one-pot template-free route and served as efficient supports for vanadium oxide. In the heterogeneous oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with molecular oxygen (O2) under ambient pressure, the obtained catalyst demonstrated high yield (91.5%) and good reusability. Even under the ambient air pressure, it gave a DFF yield of 72.1%. Structure-activity relationship analysis indicated that the strong interaction between the framework Cu species and the guest V sites accounted for the remarkable performance. This work reveals that the Cu-MOR zeolite uniquely acts as the robust support toward well-performed non-noble metal heterogeneous catalyst for biomass conversion. PMID:27523255

  16. Creating extra pores in microporous carbon via a template strategy for a remarkable enhancement of ambient-pressure CO2 uptake.

    PubMed

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Zhu, Liangkui; Zhang, Daliang; Chrzanowski, Matthew; Shi, Zhan; Ma, Shengqian

    2015-05-21

    In this work, we illustrate a template strategy to create extra pores in microporous carbon for enhancing ambient-pressure CO2 uptake, as exemplified in the context of carbonizing the silicon-containing POP, PPN-4, followed by removal of the silicon template. The resultant PPN-4/C600 demonstrates a remarkable enhancement of CO2 uptake capacity at 295 K and 1 bar by a factor of 2.3 compared to the parent PPN-4. PMID:25907601

  17. High gas pressure: an innovative method for the inactivation of dried bacterial spores.

    PubMed

    Colas de la Noue, A; Espinasse, V; Perrier-Cornet, J-M; Gervais, P

    2012-08-01

    In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pressure by the spores' structures such as residual pores and plasma membranes, followed by a sudden drop in pressure. Observation by phase-contrast microscopy suggests that internal structures have been affected by the treatment. Some parallels with polymer permeability to gas and rigidity at various water activities offer a few clues about the behavior of the outer layers of spores in response to this parameter and provide a good explanation for the sensitivity of spores to high gas pressure discharge at low hydration levels. Specificity of microorganisms such as size, organization, and composition could help in understanding the differences between spores and yeast regarding the parameters required for inactivation, such as pressure or maintenance time. PMID:22362566

  18. Method of low pressure and/or evaporative drying of aerogel

    DOEpatents

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1995-01-01

    A process whereby Resorcinol/Formaldehyde (RF) aerogel having a density of about 0.4-1.2 g/cc can be manufactured using a simple air drying procedure. This process is inherently simpler, quicker, and less expensive than the more conventional supercritical or subcritical CO.sub.2 extraction procedures. RF aerogels can be used as produced, such as in insulation applications, or pyrolyzed to form carbon aerogels with a density of about 0.9 g/cc for use in applications such as batteries, supercapacitors, etc.

  19. Method of low pressure and/or evaporative drying of aerogel

    DOEpatents

    Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

    1995-05-30

    A process is described whereby Resorcinol/Formaldehyde (RF) aerogel having a density of about 0.4--1.2 g/cc can be manufactured using a simple air drying procedure. This process is inherently simpler, quicker, and less expensive than the more conventional supercritical or subcritical CO{sub 2} extraction procedures. RF aerogels can be used as produced, such as in insulation applications, or pyrolyzed to form carbon aerogels with a density of about 0.9 g/cc for use in applications such as batteries, supercapacitors, etc.

  20. Evaluation of the high pressure oxidizer turbopump (HPOTP) vacuum drying procedures

    NASA Technical Reports Server (NTRS)

    Fears, S. D.

    1991-01-01

    Tests carried out on the HPOTP to determine the effects of surface finish on the rate at which water vapor could be removed from the bearing/spacer cavity are described. Data from these tests are used to evaluate the effects of a lower drying temperature on the flow rate of water vapor from the bearing/spacer cavity as well. It was found that, if the normality nut is torqued, there is no evidence of moisture entering the bearing/spacer cavity from external sources.

  1. Ambient pressure structural quantum critical point in the phase diagram of (Ca(x)Sr(1-x))(3)Rh(4)Sn(13).

    PubMed

    Goh, S K; Tompsett, D A; Saines, P J; Chang, H C; Matsumoto, T; Imai, M; Yoshimura, K; Grosche, F M

    2015-03-01

    The quasiskutterudite superconductor Sr_{3}Rh_{4}Sn_{13} features a pronounced anomaly in electrical resistivity at T^{*}∼138  K. We show that the anomaly is caused by a second-order structural transition, which can be tuned to 0 K by applying physical pressure and chemical pressure via the substitution of Ca for Sr. A broad superconducting dome is centered around the structural quantum critical point. Detailed analysis of the tuning parameter dependence of T^{*} as well as insights from lattice dynamics calculations strongly support the existence of a structural quantum critical point at ambient pressure when the fraction of Ca is 0.9 (i.e., x_{c}=0.9). This establishes the (Ca_{x}Sr_{1-x})_{3}Rh_{4}Sn_{13} series as an important system for exploring the physics of structural quantum criticality without the need of applying high pressures. PMID:25793843

  2. Dry Zones Around Frozen Droplets

    NASA Astrophysics Data System (ADS)

    Bisbano, Caitlin; Nath, Saurabh; Boreyko, Jonathan; Nature-Inspired Fluids; Interfaces Team

    2015-11-01

    The saturation pressure of water vapor above supercooled water exceeds that above ice at the same temperature. A frozen droplet will therefore grow by harvesting water vapor from neighboring supercooled condensate, which has recently been demonstrated to be a primary mechanism of in-plane frost growth on hydrophobic surfaces. The underlying physics of this source-sink interaction is still poorly understood. In this work, a deposited water droplet is frozen on a dry hydrophobic surface initially held above the dew point. We demonstrate that when the surface is then cooled beneath the dew point, the frozen droplet harvests nearby water vapor in the air. This results in an annular dry zone that forms between the frozen droplet and the forming supercooled condensation. For a given ambient temperature and humidity, the length of the dry zone varied strongly with surface temperature and weakly with droplet volume. The dependence of the dry zone on surface temperature is due to the fact that the vapor pressure gradients between the ambient and the surface and between the liquid and frozen water are both functions of temperature.

  3. High temperature postirradiation materials performance of spent pressurized water reactor fuel rods under dry storage conditions

    SciTech Connect

    Einziger, R.E.; Atkin, S.D.; Pasupathi, V.; Stellrecht, D.E.

    1982-04-01

    Postirradiation studies on failure mechanisms of well-characterized pressurized water reactor rods were conducted for up to a year at 482, 510, and 571/sup 0/C in limited air and inert gas atmospheres. No cladding breaches occurred even though the tests operated many orders of magnitude longer in time than the lifetime predicted by Blackburn's analyses. The extended lifetime is due to significant creep strain of the Zircaloy cladding, which decreases the internal rod pressure. The cladding creep also contributes to radial cracks, through the external oxide and internal fuel-cladding chemical interaction layers, which propagated into and arrested in an oxygen stabilized alpha-Zircaloy layer. There were no signs of either additional cladding hydriding, stress corrosion cracking, or fuel pellet degradation. If irradiation hardening does not reduce the stress rupture properties of Zircaloy, a conservative maximum storage temperature of 400/sup 0/C based on a stress-rupture mechanism is recommended to ensure a 1000-yr cladding lifetime.

  4. Microbiological, physicochemical and sensory parameters of dry fermented sausages manufactured with high hydrostatic pressure processed raw meat.

    PubMed

    Omer, M K; Prieto, B; Rendueles, E; Alvarez-Ordoñez, A; Lunde, K; Alvseike, O; Prieto, M

    2015-10-01

    The aim of this trial was to describe physicochemical, microbiological and organoleptic characteristics of dry fermented sausages produced from high hydrostatic pressure (HHP) pre-processed trimmings. During ripening of the meat products pH, weight, water activity (aw), and several microbiological parameters were measured at zero, eight, fifteen days and after 6weeks. Sensory characteristics were estimated at day 15 and after six weeks by a test panel by using several sensory tests. Enterobacteriaceae were not detected in sausages from HHP-processed trimmings. Fermentation was little affected, but weight and aw of the HHP-processed sausages decreased faster during ripening. HHP-treated sausages were consistently less favoured than non HHP-treated sausages, but the strategy may be an alternative approach if the process is optimized. PMID:26093224

  5. High-Temperature Phase Transitions in CsH2PO4 Under Ambient and High-Pressure Conditions: A Synchrotron X-ray Diffraction Study

    SciTech Connect

    Botez,C.; Hermosillo, J.; Zhang, J.; Qian, J.; Zhao, Y.; Majzlan, J.; Chianelli, R.; Pantea, C.

    2007-01-01

    To clarify the microscopic origin of the temperature-induced three-order-of-magnitude jump in the proton conductivity of CsH2PO4 (superprotonic behavior), we have investigated its crystal structure modifications within the 25-300 C temperature range under both ambient- and high-pressure conditions using synchrotron x-ray diffraction. Our high-pressure data show no indication of the thermal decomposition/polymerization at the crystal surface recently proposed as the origin of the enhanced proton conductivity. Instead, we found direct evidence that the superprotonic behavior of the title material is associated with a polymorphic structural transition to a high-temperature cubic phase. Our results are in excellent agreement with previous high-pressure ac impedance measurements.

  6. Dry Electrodes for ECG and Pulse Transit Time for Blood Pressure: A Wearable Sensor and Smartphone Communication Approach

    NASA Astrophysics Data System (ADS)

    Shyamkumar, Prashanth

    Cardiovascular Diseases (CVDs) have been a major cause for deaths in both men and women in United States. Cerebrovascular Diseases like Strokes are known to have origins in CVDs as well. Moreover, nearly 18 Million Americans have a history of myocardial infarction and are currently undergoing cardiac rehabilitation. Consequently, CVDs are the highest costing disease groups and cost more than all types of cancer combined. However, significant cost reduction is possible through the effective use of the vast advances in embedded and pervasive electronic devices for healthcare. These devices can automate and move a significant portion of disease management to the patient's home through cyber connectivity, a concept known as point-of-care (POC) diagnostics and healthcare services. POC can minimize hospital visits and potentially avoid admission altogether with prognostic tools that give advanced notice of any abnormalities or chronic illnesses so that the treatment can be planned in advance. The POC concept requires continuous remote health monitoring. Therefore, the various sensors needed for comprehensive monitoring need to be worn daily and throughout the day. Moreover, true "roaming" capability is necessary so that it does not restrict the user's travel or his/her quotidian activities. Two biomedical signals namely, Electrocardiogram (ECG) and Blood Pressure are important diagnostic tests in assessing the cardiac health of a person. To that end, the research presented in this thesis: First , describes the development of a remote monitoring solution based on Bluetooth(TM), smartphones and cyber infrastructure for cardiac care called e-nanoflex. Second, Sensors for ECG that are compatible with everyday life style namely, (a) dry, gel-less vertically aligned gold nanowire electrodes, (b) dry textile-based conductive sensor electrodes to address the need for this technology to monitor cardiovascular diseases in women are tested with e-nanoflex and discussed. Third, non

  7. Nanosecond Nd-YAG laser induced plasma emission characteristics in low pressure CO2 ambient gas for spectrochemical application on Mars

    NASA Astrophysics Data System (ADS)

    Lie, Zener Sukra; Pardede, Marincan; Tjia, May On; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2015-08-01

    An experimental study is conducted on the possibility and viability of performing spectrochemical analysis of carbon and other elements in trace amount in Mars, in particular, the clean detection of C, which is indispensible for tracking the sign of life in Mars. For this study, a nanosecond Nd-YAG laser is employed to generate plasma emission from a pure copper target in CO2 ambient gas of reduced pressure simulating the atmospheric condition of Mars. It is shown that the same shock wave excitation mechanism also works this case while exhibiting remarkably long cooling stage. The highest Cu emission intensities induced by 4 mJ laser ablation energy is attained in 600 Pa CO2 ambient gas. Meanwhile the considerably weaker carbon emission from the CO2 gas appears relatively featureless over the entire range of pressure variation, posing a serious problem for sensitive trace analysis of C contained in a solid sample. Our time resolved intensity measurement nevertheless reveals earlier appearance of C emission from the CO2 gas with a limited duration from 50 ns to 400 ns after the laser irradiation, well before the initial appearance of the long lasting C emission from the solid target at about 1 μs, due to the different C-releasing processes from their different host materials. The unwanted C emission from the ambient gas can thus be eliminated from the detected spectrum by a proper time gated detection window. The excellent spectra of carbon, aluminum, calcium, sodium, hydrogen, and oxygen obtained from an agate sample are presented to further demonstrate and verify merit of this special time gated LIBS using CO2 ambient gas and suggesting its viability for broad ranging in-situ applications in Mars.

  8. Nanosecond Nd-YAG laser induced plasma emission characteristics in low pressure CO{sub 2} ambient gas for spectrochemical application on Mars

    SciTech Connect

    Lie, Zener Sukra; Kurniawan, Koo Hendrik; Tjia, May On; Kagawa, Kiichiro

    2015-08-28

    An experimental study is conducted on the possibility and viability of performing spectrochemical analysis of carbon and other elements in trace amount in Mars, in particular, the clean detection of C, which is indispensible for tracking the sign of life in Mars. For this study, a nanosecond Nd-YAG laser is employed to generate plasma emission from a pure copper target in CO{sub 2} ambient gas of reduced pressure simulating the atmospheric condition of Mars. It is shown that the same shock wave excitation mechanism also works this case while exhibiting remarkably long cooling stage. The highest Cu emission intensities induced by 4 mJ laser ablation energy is attained in 600 Pa CO{sub 2} ambient gas. Meanwhile the considerably weaker carbon emission from the CO{sub 2} gas appears relatively featureless over the entire range of pressure variation, posing a serious problem for sensitive trace analysis of C contained in a solid sample. Our time resolved intensity measurement nevertheless reveals earlier appearance of C emission from the CO{sub 2} gas with a limited duration from 50 ns to 400 ns after the laser irradiation, well before the initial appearance of the long lasting C emission from the solid target at about 1 μs, due to the different C-releasing processes from their different host materials. The unwanted C emission from the ambient gas can thus be eliminated from the detected spectrum by a proper time gated detection window. The excellent spectra of carbon, aluminum, calcium, sodium, hydrogen, and oxygen obtained from an agate sample are presented to further demonstrate and verify merit of this special time gated LIBS using CO{sub 2} ambient gas and suggesting its viability for broad ranging in-situ applications in Mars.

  9. Boosting the value of biodiesel byproduct by the non-catalytic transesterification of dimethyl carbonate via a continuous flow system under ambient pressure.

    PubMed

    Kwon, Eilhann E; Yi, Haakrho; Jeon, Young Jae

    2014-10-01

    Transformation of coconut oil into biodiesel by using dimethyl carbonate (DMC) via a non-catalytic transesterification reaction under ambient pressure was investigated in this study. The non-catalytic transformation to biodiesel was achieved by means of a heterogeneous reaction between liquid triglycerides and gas phase DMC. The reaction was enhanced in the presence of porous material due to its intrinsic physical properties such as tortuosity and absorption/adsorption. The numerous pores in the material served as micro reaction chambers and ensured that there was enough contact time between the liquid triglycerides and the gaseous DMC, which enabled the completion of the transesterification. The highest fatty acid methyl esters (FAMEs) yield achieved was 98±0.5% within 1-2min at a temperature of 360-450°C under ambient pressure. The fast reaction rates made it possible to convert the lipid feedstock into biodiesel via a continuous flow system without the application of increased pressure. This suggested that the commonly used supercritical conditions could be avoided, resulting in huge cost benefits for biodiesel production. In addition, the high value of the byproduct from the transesterification of the lipid feedstock with DMC suggested that the production biodiesel using this method could be more economically competitive. Finally, the basic properties of biodiesel derived from the non-catalytic conversion of rapeseed oil with DMC were summarised. PMID:25065794

  10. Effect of chemical composition and high pressure processing on the volatile fraction of Serrano dry-cured ham.

    PubMed

    Martínez-Onandi, Nerea; Rivas-Cañedo, Ana; Nuñez, Manuel; Picon, Antonia

    2016-01-01

    The volatile fraction of 30 Serrano dry-cured hams with different salt and intramuscular fat contents was investigated. In addition, the effect of high pressure processing (HPP) at 600 MPa for 6 min at 21°C on the volatile compounds of those hams was studied. One hundred volatile compounds were identified and their levels subjected to analysis of variance with ham chemical composition (aw, salt content, intramuscular fat content and salt in lean ratio) and HPP treatment as main effects. Chemical composition mainly affected the relative abundance of acids, alcohols, branched-chain aldehydes, ketones, benzene compounds, sulfur compounds and some miscellaneous compounds. Salt content and fat content influenced a greater number of volatile compounds than aw. High pressure processing had a significant effect on only 8 volatile compounds, with higher levels of methanethiol and sulfur dioxide in HPP-treated samples and higher levels of ethyl acetate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, dimethyl disulfide and dimethyl trisulfide in control untreated samples. PMID:26398007

  11. Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report

    SciTech Connect

    Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

    1980-11-01

    Rock types that are likely candidates for drilling were tested. Reported herein are the short-time ultimate strengths and ductilities determined at temperatures of 25/sup 0/ to 1050/sup 0/C and a strain rate of 10/sup -4/s/sup -1/ of (a) room-dry Mt. Hood Andesite, Cuerbio Basalt, and Charcoal (St. Cloud Gray) Granodiorite at confining pressures of 0, 50, and 100 MPa, (b) water-saturated specimens of the same three rocks at zero effective pressure (both pore and confining pressures of 50 MPa), and (c) room-dry Newberry Rhyolite Obsidian at 0 and 50 MPa. These strengths are then compared with the stresses developed at the wall of a borehole in an elastic medium at the appropriate temperatures and mean pressures to assess the problem of borehole stability. (MHR)

  12. Polystyrene as a model system to probe the impact of ambient gas chemistry on polymer surface modifications using remote atmospheric pressure plasma under well-controlled conditions.

    PubMed

    Bartis, Elliot A J; Luan, Pingshan; Knoll, Andrew J; Hart, Connor; Seog, Joonil; Oehrlein, Gottlieb S

    2015-01-01

    An atmospheric pressure plasma jet (APPJ) was used to treat polystyrene (PS) films under remote conditions where neither the plume nor visible afterglow interacts with the film surface. Carefully controlled conditions were achieved by mounting the APPJ inside a vacuum chamber interfaced to a UHV surface analysis system. PS was chosen as a model system as it contains neither oxygen nor nitrogen, has been extensively studied, and provides insight into how the aromatic structures widespread in biological systems are modified by atmospheric plasma. These remote treatments cause negligible etching and surface roughening, which is promising for treatment of sensitive materials. The surface chemistry was measured by X-ray photoelectron spectroscopy to evaluate how ambient chemistry, feed gas chemistry, and plasma-ambient interaction impact the formation of specific moieties. A variety of oxidized carbon species and low concentrations of NOx species were measured after APPJ treatment. In the remote conditions used in this work, modifications are not attributed to short-lived species, e.g., O atoms. It was found that O3 does not correlate with modifications, suggesting that other long-lived species such as singlet delta oxygen or NOx are important. Indeed, surface-bound NO3 was observed after treatment, which must originate from gas phase NOx as neither N nor O are found in the pristine film. By varying the ambient and feed gas chemistry to produce O-rich and O-poor conditions, a possible correlation between the oxygen and nitrogen composition was established. When oxygen is present in the feed gas or ambient, high levels of oxidation with low concentrations of NO3 on the surface were observed. For O-poor conditions, NO and NO2 were measured, suggesting that these species contribute to the oxidation process, but are easily oxidized when oxygen is present. That is, surface oxidation limits and competes with surface nitridation. Overall, surface oxidation takes place easily

  13. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    SciTech Connect

    Dawood, Mahmoud S.; Hamdan, Ahmad E-mail: Joelle.margot@umontreal.ca; Margot, Joëlle E-mail: Joelle.margot@umontreal.ca

    2015-11-15

    The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure) and compositions (argon, nitrogen and helium) on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  14. Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy.

    PubMed

    Zhang, Xueqiang; Ptasinska, Sylwia

    2015-02-01

    Water adsorption and dissociation on a GaP(111) crystal surface are investigated using near-ambient pressure X-ray photoelectron spectroscopy (NAP XPS) in a wide range of pressures (∼10(-10)-5 mbar) and temperatures (∼300-773 K). Dynamic changes in chemical evolution at the H2O/GaP(111) interface are reflected in Ga 2p3/2, O 1s, and P 2p spectra. In the pressure-dependent study performed at room temperature, an enhancement of surface Ga hydroxylation and oxidation with an increase in H2O pressure is observed. In the temperature-dependent study performed at elevated pressures, two distinct regions can be defined in which drastic changes occur in the surface chemistry. Below 673 K, the surface Ga hydroxylation and oxidation progress continuously. However, above 673 K, a large-scale conversion of surface O-Ga-OH species into non-stoichiometric Ga hydroxide along with oxidation of surface P atoms occurs through an intermediate state. The NAP XPS technique enabled us to experimentally track the chemistry at the H2O/GaP interface under near-realistic conditions, thereby providing evidence to compare with recent theoretical efforts to improve the understanding of water-splitting mechanisms and photo-corrosion on semiconductor surfaces. PMID:25559043

  15. On the accuracy of van der Waals inclusive density-functional theory exchange-correlation functionals for ice at ambient and high pressures

    NASA Astrophysics Data System (ADS)

    Santra, Biswajit; Klimeš, Jiří; Tkatchenko, Alexandre; Alfè, Dario; Slater, Ben; Michaelides, Angelos; Car, Roberto; Scheffler, Matthias

    2013-10-01

    Density-functional theory (DFT) has been widely used to study water and ice for at least 20 years. However, the reliability of different DFT exchange-correlation (xc) functionals for water remains a matter of considerable debate. This is particularly true in light of the recent development of DFT based methods that account for van der Waals (vdW) dispersion forces. Here, we report a detailed study with several xc functionals (semi-local, hybrid, and vdW inclusive approaches) on ice Ih and six proton ordered phases of ice. Consistent with our previous study [B. Santra, J. Klimeš, D. Alfè, A. Tkatchenko, B. Slater, A. Michaelides, R. Car, and M. Scheffler, Phys. Rev. Lett. 107, 185701 (2011)] which showed that vdW forces become increasingly important at high pressures, we find here that all vdW inclusive methods considered improve the relative energies and transition pressures of the high-pressure ice phases compared to those obtained with semi-local or hybrid xc functionals. However, we also find that significant discrepancies between experiment and the vdW inclusive approaches remain in the cohesive properties of the various phases, causing certain phases to be absent from the phase diagram. Therefore, room for improvement in the description of water at ambient and high pressures remains and we suggest that because of the stern test the high pressure ice phases pose they should be used in future benchmark studies of simulation methods for water.

  16. On the accuracy of van der Waals inclusive density-functional theory exchange-correlation functionals for ice at ambient and high pressures.

    PubMed

    Santra, Biswajit; Klimes, Jirí; Tkatchenko, Alexandre; Alfè, Dario; Slater, Ben; Michaelides, Angelos; Car, Roberto; Scheffler, Matthias

    2013-10-21

    Density-functional theory (DFT) has been widely used to study water and ice for at least 20 years. However, the reliability of different DFT exchange-correlation (xc) functionals for water remains a matter of considerable debate. This is particularly true in light of the recent development of DFT based methods that account for van der Waals (vdW) dispersion forces. Here, we report a detailed study with several xc functionals (semi-local, hybrid, and vdW inclusive approaches) on ice Ih and six proton ordered phases of ice. Consistent with our previous study [B. Santra, J. Klimeš, D. Alfè, A. Tkatchenko, B. Slater, A. Michaelides, R. Car, and M. Scheffler, Phys. Rev. Lett. 107, 185701 (2011)] which showed that vdW forces become increasingly important at high pressures, we find here that all vdW inclusive methods considered improve the relative energies and transition pressures of the high-pressure ice phases compared to those obtained with semi-local or hybrid xc functionals. However, we also find that significant discrepancies between experiment and the vdW inclusive approaches remain in the cohesive properties of the various phases, causing certain phases to be absent from the phase diagram. Therefore, room for improvement in the description of water at ambient and high pressures remains and we suggest that because of the stern test the high pressure ice phases pose they should be used in future benchmark studies of simulation methods for water. PMID:24160528

  17. Electronic properties and the nature of metal-insulator transition in NdNiO3 prepared at ambient oxygen pressure

    NASA Astrophysics Data System (ADS)

    Hooda, M. K.; Yadav, C. S.

    2016-06-01

    We report the electronic properties of the NdNiO3, prepared at the ambient oxygen pressure condition. The metal-insulator transition temperature is observed at 192 K, but the low temperature state is found to be less insulating compared to the NdNiO3 prepared at high oxygen pressure. The electric resistivity, Seebeck coefficient and thermal conductivity of the compound show large hysteresis below the metal-insulator transition. The large value of the effective mass (m*~8me) in the metallic state indicates the narrow character of the 3d band. The electric conduction at low temperatures (T=2-20 K) is governed by the variable range hopping of the charge carriers.

  18. The first MEMIN shock recovery experiments at low shock pressure (5-12.5 GPa) with dry, porous sandstone

    NASA Astrophysics Data System (ADS)

    Kowitz, Astrid; Schmitt, Ralf T.; Uwe Reimold, W.; Hornemann, Ulrich

    2013-01-01

    As part of the MEMIN research program this project is focused on shock deformation experimentally generated in dry, porous Seeberger sandstone in the low shock pressure range from 5 to 12.5 GPa. Special attention is paid to the influence of porosity on progressive shock metamorphism. Shock recovery experiments were carried out with a high-explosive set-up that generates a planar shock wave, and using the shock impedance method. Cylinders of sandstone of average grain size of 0.17 mm and porosity of about 19 vol%, and containing some 96 wt% SiO2, were shock deformed. Shock effects induced with increasing shock pressure include: (1) Already at 5 GPa the entire pore space is closed; quartz grains show undulatory extinction. On average, 134 fractures per mm are observed. Dark vesicular melt (glass) of the composition of the montmorillonitic phyllosilicate component of this sandstone occurs at an average amount of 1.6 vol%. (2) At 7.5 GPa, quartz grains show weak but prominent mosaicism and the number of fractures increases to 171 per millimeter. Two additional kinds of melt, both based on phyllosilicate precursor, could be observed: a light colored, vesicular melt and a melt containing large iron particles. The total amount of melt (all types) increased in this experiment to 2.4 vol%. Raman spectroscopy confirmed the presence of shock-deformed quartz grains near the surface. (3) At 10 and 12.5 GPa, quartz grains also show weak but prominent mosaicism, the number of fractures per mm has reached a plateau value of approximately 200, and the total amount of the different melt types has increased to 4.8 vol%. Diaplectic quartz glass could be observed locally near the impacted surface. In addition, local shock effects, most likely caused by multiple shock wave reflections at sandstone-container interfaces, occur throughout the sample cylinders and include locally enhanced formation of PDF, as well as shear zones associated with cataclastic microbreccia, diaplectic quartz

  19. Measurement and Visualization of Mass Transport for the Flowing Atmospheric Pressure Afterglow (FAPA) Ambient Mass-Spectrometry Source

    PubMed Central

    Pfeuffer, Kevin P.; Ray, Steven J.; Hieftje, Gary M.

    2014-01-01

    Ambient desorption/ionization mass spectrometry (ADI-MS) has developed into an important analytical field over the last nine years. The ability to analyze samples under ambient conditions while retaining the sensitivity and specificity of mass spectrometry has led to numerous applications and a corresponding jump in the popularity of this field. Despite the great potential of ADI-MS, problems remain in the areas of ion identification and quantification. Difficulties with ion identification can be solved through modified instrumentation, including accurate-mass or MS/MS capabilities for analyte identification. More difficult problems include quantification due to the ambient nature of the sampling process. To characterize and improve sample volatilization, ionization, and introduction into the mass-spectrometer interface, a method of visualizing mass transport into the mass spectrometer is needed. Schlieren imaging is a well-established technique that renders small changes in refractive index visible. Here, schlieren imaging was used to visualize helium flow from a plasma-based ADI-MS source into a mass spectrometer while ion signals were recorded. Optimal sample positions for melting-point capillary and transmission-mode (stainless steel mesh) introduction were found to be near (within 1 mm of) the mass spectrometer inlet. Additionally, the orientation of the sampled surface plays a significant role. More efficient mass transport resulted for analyte deposits directly facing the MS inlet. Different surfaces (glass slide and rough surface) were also examined; for both it was found that the optimal position is immediately beneath the MS inlet. PMID:24658804

  20. Effectiveness of fermentation/drying and post-process pressurization on viability of Listeria monocytogenes and Salmonella spp. in Genoa salami

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effectiveness of fermentation and drying alone and in combination with high pressure processing (HPP) to inactivate five-strain cocktails of L. monocytogenes or Salmonella spp. (ca. 7.0 log10 per gram of each in batter) in Genoa salami. The inoculated chubs were fermented at 20 degr...

  1. Evaluation of high pressure processing, freezing, and fermentation/drying on viability of Trichinella spiralis larvae in raw pork and in Genoa salami

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated high pressure processing (HPP), freezing, and fermentation/drying to inactivate Trichinella spiralis larvae in both infected pig muscle and in Genoa salami produced with trichinae infected pork. In part A, in each of two trials 10 gram portions (2 replicates per treatment) of fresh pig ...

  2. A study of the O/Ag(111) system with scanning tunneling microscopy and x-ray photoelectron spectroscopy at ambient pressures

    NASA Astrophysics Data System (ADS)

    Heine, Christian; Eren, Baran; Lechner, Barbara A. J.; Salmeron, Miquel

    2016-10-01

    The interaction of O2 with the Ag(111) surface was studied with scanning tunneling microscopy (STM) in the pressure range from 10- 9 Torr to 1 atm at room temperature and with X-ray photoelectron spectroscopy (XPS) up to 0.3 Torr O2 in the temperature range from RT to 413 K. STM images show that the Ag(111) surface topography is little affected in regions with large flat terraces, except for the appearance of mobile features due to oxygen atoms at pressures above 0.01 Torr. In regions where the step density is high, the surface became rough under 0.01 Torr of O2, due to the local oxidation of Ag. Various chemical states of oxygen due to chemisorbed, oxide and subsurface species were identified by XPS as a function of pressure and temperature. The findings from the STM images and XPS measurements indicate that formation of an oxide phase, the thermodynamically stable form at room temperature under ambient O2 pressure, is kinetically hindered in the flat terrace areas but proceeds readily in regions with high-step density.

  3. Ambient Pressure Structural Quantum Critical Point in the Phase Diagram of (CaxSr1-x)3Rh4Sn13

    NASA Astrophysics Data System (ADS)

    Goh, Swee K.; Tompsett, D. A.; Saines, P. J.; Chang, H. C.; Matsumoto, T.; Imai, M.; Yoshimura, K.; Grosche, F. M.

    The quasiskutterudite superconductor Sr3Rh4Sn13 features a pronounced anomaly in electrical resistivity at T* ~ 138 K. The anomaly is caused by a second-order structural transition, which can be tuned to 0 K by applying physical pressure and chemical pressure via the substitution of Ca for Sr. A broad superconducting dome is centered around the structural quantum critical point. Detailed analysis of the tuning parameter dependence of T* as well as insights from lattice dynamics calculations strongly support the existence of a structural quantum critical point at ambient pressure when the fraction of Ca is 0.9 (xc=0.9). This establishes the (CaxSr1-x)3Rh4Sn13 series as an important system for exploring the physics of structural quantum criticality and its interplay with the superconductivity, without the need of applying high pressures. This work was supported by CUHK (Startup Grant, Direct Grant No. 4053071), UGC Hong Kong (ECS/24300214), Trinity College (Cam- bridge), Grants-in-Aid from MEXT (No. 22350029 and 23550152) and Glasstone Bequest (Oxford).

  4. Electronic transport properties of MFe2As2 (M = Ca, Eu, Sr) at ambient and high pressures up to 20 GPa

    NASA Astrophysics Data System (ADS)

    Morozova, Natalia V.; Karkin, Alexander E.; Ovsyannikov, Sergey V.; Umerova, Yuliya A.; Shchennikov, Vladimir V.; Mittal, R.; Thamizhavel, A.

    2015-12-01

    We experimentally investigated the electronic transport properties of four iron pnictide crystals, namely, EuFe2As2, SrFe2As2, and CaFe2As2 parent compounds, and superconducting CaFe1.94Co0.06As2 at ambient and high pressures up to 20 GPa. At ambient pressure we examined the electrical resistivity, Hall and magnetoresistance effects of the samples in a temperature range from 1.5 to 380 K in high magnetic fields up to 13.6 T. In this work we carried out the first simultaneous investigations of the in-plane and out-of-plane Hall coefficients, and found new peculiarities of the low-temperature magnetic and structural transitions that occur in these materials. In addition, the Hall coefficient data suggested that the parent compounds are semimetals with a multi-band conductivity that includes hole-type and electron-type bands. We measured the pressure dependence of the thermoelectric power (the Seebeck effect) of these samples up to 20 GPa, i.e. across the known phase transition from the tetragonal to the collapsed tetragonal lattice. The high-pressure behavior of the thermopower of EuFe2As2 and CaFe2As2 showing the p-n sign inversions was consistent with the semimetal model described above. By means of thermopower, we found in single-crystalline CaFe2As2 direct evidence of the band structure crossover related to the formation of As-As bonds along the c-axis on the tetragonal → collapsed tetragonal phase transition near 2 GPa. We showed that this feature is distinctly observable only in high-quality samples, and already for re-pressurization cycles this crossover was strongly smeared because of the moderate deterioration of the sample. We also demonstrated by means of thermopower that the band structure crossover that should accompany the tetragonal → collapsed tetragonal phase transition in EuFe2As2 near 8 GPa is hardly visible even in high-quality single crystals. This behavior may be related to a gradual valence change of the Eu ions under pressure that leads to

  5. On the ambient pressure polymorph of K2Ca3Si3O10-An unusual mixed-anion silicate and its structural and spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Schmidmair, Daniela; Kahlenberg, Volker; Perfler, Lukas; Tribus, Martina; Hildebrandt, Johannes; Többens, Daniel M.

    2015-08-01

    An ambient pressure polymorph of K2Ca3Si3O10 has been synthesized via solid state reactions. Single-crystal X-ray diffraction experiments show, that this new modification crystallizes in the triclinic space group P 1 bar with the following lattice parameters: a=5.6699(6) Å, b=7.3754(12) Å, c=11.8310(13) Å, α=86.199(11)°, β=80.625(9)°, γ=88.700(11)°. The structure was solved by direct methods and subsequently refined to a residual of R1=0.0261 for 1761 independent observed reflections (I>2σ(I)) and 163 parameters. A special feature of the crystal structure is the coexistence of two different types of silicate anions. Isolated [SiO4]- tetrahedra as well as [Si4O12]- vierer single rings occur in the ratio 2:1, resulting in the crystallochemical formula K4Ca6[SiO4]2[Si4O12]. To the best of our knowledge, this is the first example of an oxo-silicate where insular and cyclic silicate anions appear concomitantly. Charge compensation is provided by Ca and K cations. All calcium atoms are coordinated by 6 oxygen atoms, forming distorted octahedra. By sharing common corners, edges and faces, these [CaO6]-polyhedra build up octahedral layer-like motifs parallel to (010). Potassium ions are located in voids between the silicate anions and [CaO6]-octahedra and are coordinated by 8-9 oxygen atoms. Further characterization of this new compound was carried out by electron microprobe analysis and Raman spectroscopy. DFT calculations were employed (i) to assign Raman bands to certain vibrational modes and (ii) to determine the relative stabilities of the monoclinic high-pressure and the triclinic ambient pressure polymorph of K2Ca3Si3O10.

  6. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    PubMed

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully. PMID:23455645

  7. High strength air-dried aerogels

    DOEpatents

    Coronado, Paul R.; Satcher, Jr., Joe H.

    2012-11-06

    A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

  8. Sum frequency generation vibrational spectroscopy at solid gas interfaces: CO adsorption on Pd model catalysts at ambient pressure

    NASA Astrophysics Data System (ADS)

    Rupprechter, Günther; Unterhalt, Holger; Morkel, Matthias; Galletto, Paolo; Hu, Linjie; Freund, Hans-Joachim

    2002-04-01

    Carbon monoxide adsorption on Pd(1 1 1) and Pd nanoparticles supported by Al 2O 3/NiAl(1 1 0) was examined by vibrational sum frequency generation spectroscopy from 10 -8 to 1000 mbar, and from 100 to 400 K. Identical CO saturation structures were observed on Pd(1 1 1) under ultrahigh vacuum (˜10 -7 mbar, 95 K) and at high pressure (e.g. ⩾1 mbar, 190 K) with no indications of pressure-induced surface rearrangements. Special attention was paid to experimental artifacts that may occur under elevated pressure and may be misinterpreted as "high pressure effects". Vibrational spectra of CO on defect-rich Pd(1 1 1) exhibited an additional peak that originated from CO bound to defect (step or edge) sites. The CO adsorbate structure on supported Pd nanoparticles was different from Pd(1 1 1) but more similar to stepped Pd(1 1 1). At low pressure (10 -7 mbar CO) the adsorbate structure depended strongly on the Pd morphology revealing specific differences in the adsorption properties of supported nanoparticles and single crystal surfaces. At high pressure (e.g. 200 mbar CO) these differences were even more pronounced. Prominent high coverage CO structures on Pd(1 1 1) could not be established on Pd particles. However, in spite of structural differences between well faceted and rough Pd nanoparticles nearly identical adsorption site occupancies were observed in both cases at 200 mbar CO. Initial tests of the catalytic activity of Pd/Al 2O 3/NiAl(1 1 0) for ethylene hydrogenation at 1 bar revealed a remarkable activity and stability of the model system with catalytic properties similar to impregnated catalysts.

  9. Transition-metal-free, ambient-pressure carbonylative cross-coupling reactions of aryl halides with potassium aryltrifluoroborates.

    PubMed

    Jin, Fengli; Han, Wei

    2015-06-01

    We disclose an unprecedented transition-metal-free carbonylative cross coupling of aryl halides with potassium aryl trifluoroborates even at atmospheric pressure of carbon monoxide. This protocol is efficient, operationally simple, and shows wide scope with regard to both aryl halides and potassium aryl trifluoroborates containing a series of active functional groups. PMID:25939449

  10. Flow rate/pressure drop data gathered from testing a sample of the Space Shuttle Strain Isolation Pad (SIP): Effects of ambient pressure combined with tension and compression conditions

    NASA Technical Reports Server (NTRS)

    Springfield, R. D.; Lawing, P. L.

    1983-01-01

    Tests were conducted on a sample of strain isolation pad (SIP) typical of that used in the shuttle orbiter thermal protection system to determine the characteristics of SIP internal flow. Data obtained were pressure drop as a function of flow rate for a range of ambient pressures representing various points along the Shuttle trajectory and for stretched and compressed conditions of the SIP. Flow was in the direction of the weave parallel to most of the fibers. The data are plotted in several standard engineering formats in order to be of maximum utility to the user. In addition to providing support to the Space Shuttle Program, these data are a source of experimental information on flow through fiberous (rather than the more usual sand bed type) porous media.

  11. Convoluted effect of laser fluence and pulse duration on the property of a nanosecond laser-induced plasma into an argon ambient gas at the atmospheric pressure

    SciTech Connect

    Bai Xueshi; Ma Qianli; Motto-Ros, Vincent; Yu Jin; Sabourdy, David; Nguyen, Luc; Jalocha, Alain

    2013-01-07

    We studied the behavior of the plasma induced by a nanosecond infrared (1064 nm) laser pulse on a metallic target (Al) during its propagation into argon ambient gas at the atmospheric pressure and especially over the delay interval ranging from several hundred nanoseconds to several microseconds. In such interval, the plasma is particularly interesting as a spectroscopic emission source for laser-induced plasma spectroscopy (LIBS). We show a convoluted effect between laser fluence and pulse duration on the structure and the emission property of the plasma. With a relatively high fluence of about 160 J/cm{sup 2} where a strong plasma shielding effect is observed, a short pulse of about 4 ns duration is shown to be significantly more efficient to excite the optical emission from the ablation vapor than a long pulse of about 25 ns duration. While with a lower fluence of about 65 J/cm{sup 2}, a significantly more efficient excitation is observed with the long pulse. We interpret our observations by considering the post-ablation interaction between the generated plume and the tailing part of the laser pulse. We demonstrate that the ionization of the layer of ambient gas surrounding the ablation vapor plays an important role in plasma shielding. Such ionization is the consequence of laser-supported absorption wave and directly dependent on the laser fluence and the pulse duration. Further observations of the structure of the generated plume in its early stage of expansion support our explanations.

  12. Comparison of the clinical effects of combined salmeterol/fluticasone delivered by dry powder or pressurized metered dose inhaler.

    PubMed

    Hojo, Masayuki; Shirai, Toshihiro; Hirashima, Junko; Iikura, Motoyasu; Sugiyama, Haruhito

    2016-04-01

    The salmeterol/fluticasone combination (SFC) inhaler is currently the most widely used maintenance drug for asthmatics worldwide. Although the effectiveness of SFC as either a dry powder inhaler (DPI) or a pressurized metered dose inhaler (pMDI) is well documented, there is limited data comparing the clinical efficacies of the two devices. To address this issue, we carried out a randomized crossover trial in which asthmatic patients (n = 47; mean age, 62.5 ± 16.5 years old) received a 12-week treatment of SFC DPI (50/250 μg twice daily) or SFC pMDI (four puffs of 25/125 μg daily). After a 4-week washout period, patients received another crossover treatment for 12 weeks. Respiratory resistance and reactance were measured by forced oscillation technique (MostGraph-01), spirometry, fractional exhaled nitric oxide (FeNO), and an asthma control test (ACT) every 4 weeks. The mean forced expiratory volume1.0 at the baseline was 2.16 ± 0.86 (L). Respiratory system resistance at 5 Hz (R5), the difference between R5 and R at 20 Hz (R5 - R20), and FeNO improved in both treatment groups, while reactance at 5 Hz (X5) and ACT score improved only in the pMDI group. In patients >70 years old (n = 21), R5, R5 - R20, ΔX5, and FeNO improved only in the pMDI group. These results suggest that SFC by pMDI produces a stronger anti-inflammatory and bronchodilatory effect even in patients whose asthma is well controlled by SFC delivered by DPI. PMID:26898348

  13. Evaluation of nucleic acid stabilization products for ambient temperature shipping and storage of viral RNA and antibody in a dried whole blood format.

    PubMed

    Dauner, Allison L; Gilliland, Theron C; Mitra, Indrani; Pal, Subhamoy; Morrison, Amy C; Hontz, Robert D; Wu, Shuenn-Jue L

    2015-07-01

    Loss of sample integrity during specimen transport can lead to false-negative diagnostic results. In an effort to improve upon the status quo, we used dengue as a model RNA virus to evaluate the stabilization of RNA and antibodies in three commercially available sample stabilization products: Whatman FTA Micro Cards (GE Healthcare Life Sciences, Pittsburgh, PA), DNAstāble Blood tubes (Biomātrica, San Diego, CA), and ViveST tubes (ViveBio, Alpharetta, GA). Both contrived and clinical dengue-positive specimens were stored on these products at ambient temperature or 37°C for up to 1 month. Antibody and viral RNA levels were measured by enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays, respectively, and compared with frozen unloaded controls. We observed reduced RNA and antibody levels between stabilized contrived samples and frozen controls at our earliest time point, and this was particularly pronounced for the FTA cards. However, despite some time and temperature dependent loss, a 94.6-97.3% agreement was observed between stabilized clinical specimens and their frozen controls for all products. Additional considerations such as cost, sample volume, matrix, and ease of use should inform any decision to incorporate sample stabilization products into a diagnostic testing workflow. We conclude that DNAstāble Blood and ViveST tubes are useful alternatives to traditional filter paper for ambient temperature shipment of clinical specimens for downstream molecular and serological testing. PMID:25940193

  14. A Reactive Oxide Overlayer on Rh Nanoparticles during CO Oxidation and Its Size Dependence Studied by in Situ Ambient Pressure XPS

    SciTech Connect

    Grass, Michael E.; Zhang, Yawen; Butcher, Derek R.; Park, Jeong Y.; Li, Yimin; Bluhm, Hendrik; Bratlie, Kaitlin M.; Zhang, Tianfu; Somorjai, Gabor A.

    2008-09-15

    CO oxidation is one of the most studied heterogeneous reactions, being scientifically and industrially important, particularly for removal of CO from exhaust streams and preferential oxidation for hydrogen purification in fuel cell applications. The precious metals Ru, Rh, Pd, Pt, and Au are most commonly used for this reaction because of their high activity and stability. Despite the wealth of experimental and theoretical data, it remains unclear what is the active surface for CO oxidation under catalytic conditions for these metals. In this communication, we utilize in situ synchrotron ambient pressure X-ray photoelectron spectroscopy (APXPS) to monitor the oxidation state at the surface of Rh nanoparticles during CO oxidation and demonstrate that the active catalyst is a surface oxide, the formation of which is dependent on particle size. The amount of oxide formed and the reaction rate both increase with decreasing particle size.

  15. The nature of the water nucleation sites on TiO2(110) surfacesrelvealed by ambient pressure x-ray photoelectron spectroscopy

    SciTech Connect

    Ketteler, Guido; Yamamoto, Susumu; Bluhm, Hendrik; Andersson,Klas; Starr, David E.; Ogletree, D. Frank; Ogasawara, Hirohito; Nilsson,Anders; Salmeron, Miquel

    2007-05-01

    X-ray photoelectron spectroscopy at ambient conditions of pressure (up to 1.5 Torr) and temperature (265K

  16. Transport properties and structural features of the ambient-pressure superconductor {kappa}{sup '}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl

    SciTech Connect

    Zverev, V. N.; Manakov, A. I.; Khasanov, S. S.; Shibaeva, R. P.; Kushch, N. D.; Kazakova, A. V.; Buravov, L. I.; Yagubskii, E. B.; Canadell, E.

    2006-09-01

    The crystal structure and low-temperature transport properties of the recently synthesized {kappa}{sup '}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl radical cation salt are investigated. The crystals exhibit metallic conductivity and are ambient-pressure superconductors with critical temperature in the range (11.3-11.9) K. The crystals show some distinctions in structure as compared to that of the Mott insulator {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl: smaller size of the unit cell and deficiency in the occupancy of the copper positions. Anisotropy of superconducting properties as well as a nontrivial temperature dependence of the upper critical field were observed.

  17. An improved high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry method for determination of chlorophylls and their derivatives in freeze-dried and hot-air-dried Rhinacanthus nasutus (L.) Kurz.

    PubMed

    Kao, Tsai Hua; Chen, Chia Ju; Chen, Bing Huei

    2011-10-30

    Rhinacanthus nasutus (L.) Kurz, a traditional Chinese herb possessing antioxidant and anti-cancer activities, has been reported to contain functional components like carotenoids and chlorophylls. However, the variety and amount of chlorophylls remain uncertain. The objectives of this study were to develop a high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry (HPLC-DAD-APCI-MS) method for determination of chlorophylls and their derivatives in hot-air-dried and freeze-dried R. nasutus. An Agilent Eclipse XDB-C18 column and a gradient mobile phase composed of methanol/N,N-dimethylformamide (97:3, v/v), acetonitrile and acetone were employed to separate internal standard zinc-phthalocyanine plus 12 cholorophylls and their derivatives within 21 min, including chlorophyll a, chlorophyll a', hydroxychlorophyll a, 15-OH-lactone chlorophyll a, chlorophyll b, chlorophyll b', hydroxychlorophyll b, pheophytin a, pheophytin a', hydroxypheophytin a, hydroxypheophytin a' and pheophytin b in hot-air-dried R. nasutus with flow rate at 1 mL/min and detection at 660 nm. But, in freeze-dried R. nasutus, only 4 chlorophylls and their derivatives, including chlorophyll a, chlorophyll a', chlorophyll b and pheophytin a were detected. Zinc-phthalocyanine was found to be an appropriate internal standard to quantify all the chlorophyll compounds. After quantification by HPLC-DAD, both chlorophyll a and pheophytin a were the most abundant in hot-air-dried R. nasutus, while in freeze-dried R. nasutus, chlorophyll a and chlorophyll b dominated. PMID:22063550

  18. Halo-shaped flowing atmospheric pressure afterglow: a heavenly design for simplified sample introduction and improved ionization in ambient mass spectrometry.

    PubMed

    Pfeuffer, Kevin P; Schaper, J Niklas; Shelley, Jacob T; Ray, Steven J; Chan, George C-Y; Bings, Nicolas H; Hieftje, Gary M

    2013-08-01

    The flowing atmospheric-pressure afterglow (FAPA) is a promising new source for atmospheric-pressure, ambient desorption/ionization mass spectrometry. However, problems exist with reproducible sample introduction into the FAPA source. To overcome this limitation, a new FAPA geometry has been developed in which concentric tubular electrodes are utilized to form a halo-shaped discharge; this geometry has been termed the halo-FAPA or h-FAPA. With this new geometry, it is still possible to achieve direct desorption and ionization from a surface; however, sample introduction through the inner capillary is also possible and improves interaction between the sample material (solution, vapor, or aerosol) and the plasma to promote desorption and ionization. The h-FAPA operates with a helium gas flow of 0.60 L/min outer, 0.30 L/min inner, and applied current of 30 mA at 200 V for 6 W of power. In addition, separation of the discharge proper and sample material prevents perturbations to the plasma. Optical-emission characterization and gas rotational temperatures reveal that the temperature of the discharge is not significantly affected (<3% change at 450 K) by water vapor during solution-aerosol sample introduction. The primary mass-spectral background species are protonated water clusters, and the primary analyte ions are protonated molecular ions (M + H(+)). Flexibility of the new ambient sampling source is demonstrated by coupling it with a laser ablation unit, a concentric nebulizer, and a droplet-on-demand system for sample introduction. A novel arrangement is also presented in which the central channel of the h-FAPA is used as the inlet to a mass spectrometer. PMID:23808829

  19. Cyclic-load crack growth in ASME SA-105 grade II steel in high-pressure hydrogen at ambient temperature

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Chandler, W. T.

    1976-01-01

    ASME SA-105 Grade II steel, which is used in high-pressure hydrogen compressor systems, is similar to steels used or considered for use in high-pressure hydrogen storage vessels and pipelines. This paper summarizes the results of a program conducted to provide cyclic-load crack growth rate (da/dN) data for a fracture mechanics analysis of a 15,000 psi hydrogen compressor facility which contains pulse quieter and after-cooler separator vessels constructed of the ASME SA-105 Grade II steel. Included in the program were tests performed to assist in establishing operating procedures that could minimize the effect of hydrogen on crack growth rates during operation.

  20. Equation of state in the generalized density scaling regime studied from ambient to ultra-high pressure conditions.

    PubMed

    Grzybowski, A; Koperwas, K; Paluch, M

    2014-01-28

    In this paper, based on the effective intermolecular potential with well separated density and configuration contributions and the definition of the isothermal bulk modulus, we derive two similar equations of state dedicated to describe volumetric data of supercooled liquids studied in the extremely wide pressure range related to the density range, which is extremely wide in comparison with the experimental range reached so far in pressure-volume-temperature measurements of glass-forming liquids. Both the equations comply with the generalized density scaling law of molecular dynamics versus h(ρ)/T at different densities ρ and temperatures T, where the scaling exponent can be in general only a density function γ(ρ) = d ln h/d ln ρ as recently argued by the theory of isomorphs. We successfully verify these equations of state by using data obtained from molecular dynamics simulations of the Kob-Andersen binary Lennard-Jones liquid. As a very important result, we find that the one-parameter density function h(ρ) analytically formulated in the case of this prototypical model of supercooled liquid, which implies the one-parameter density function γ(ρ), is able to scale the structural relaxation times with the value of this function parameter determined by fitting the volumetric simulation data to the equations of state. We also show that these equations of state properly describe the pressure dependences of the isothermal bulk modulus and the configurational isothermal bulk modulus in the extremely wide pressure range investigated by the computer simulations. Moreover, we discuss the possible forms of the density functions h(ρ) and γ(ρ) for real glass formers, which are suggested to be different from those valid for the model of supercooled liquid based on the Lennard-Jones intermolecular potential. PMID:25669550

  1. A conversion model of graphite to ultrananocrystalline diamond via laser processing at ambient temperature and normal pressure

    SciTech Connect

    Ren, X. D. Yang, H. M.; Zheng, L. M.; Tang, S. X.; Ren, N. F.; Xu, S. D.; Yuan, S. Q.

    2014-07-14

    The synthesis mechanism of ultrananocrystalline diamond via laser shock processing of graphite suspension was presented at room temperature and normal pressure, which yielded the ultrananocrystalline diamond in size of about 5 nm. X-ray diffraction, high-resolution transmission electron microscopy, and laser Raman spectroscopy were used to characterize the nano-crystals. The transformation model and growth restriction mechanism of high power density with short-pulsed laser shocking of graphite particles in liquid was put forward.

  2. Investigating half-metallicity in PtXSb alloys (X=V, Mn, Cr, Co) at ambient and high pressure

    NASA Astrophysics Data System (ADS)

    Habbak, Enas L.; Shabara, Reham M.; Aly, Samy H.; Yehia, Sherif

    2016-08-01

    The structural, electronic, magnetic and elastic properties of half-Heusler alloys PtMnSb, PtVSb, PtCrSb and PtCoSb are investigated using first-principles calculation based on Density Functional Theory DFT. The Full Potential local Orbital (FPLO) method, within the General Gradient Approximation (GGA) and Local Spin Density Approximation (LSDA), have been used. The calculated structural, electronic and magnetic properties are in good agreement with available experimental and theoretical data. Using GGA approximation, only PtVSb shows a half-metallic behavior with a spin-down band gap and total magnetic moment of 0.802 eV and 2 μB respectively. Both of PtVSb and PtMnSb alloys are half-metallic with spin-down band gaps of 0.925 eV and 0.832 eV and magnetic moments of 2 μB and 4 μB respectively using LSDA approximation. The bulk modulus and its first pressure-derivative of these alloys are calculated using the modified Birch-Murnaghan equation of state (EOS). The effect of pressure on the lattice constant, energy gap and bulk modulus is investigated. Under pressure, PtMnSb and PtCrSb turn into half-metallic alloys at nearly 6 GPa and 27 GPa respectively using GGA approximation.

  3. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  4. Electronic properties of Fe1-xVxBO3 at ambient conditions and at high pressure

    NASA Astrophysics Data System (ADS)

    Kazak, N. V.; Ovchinnikov, S. G.; Abd-Elmeguid, M. M.; Ivanova, N. B.

    2005-03-01

    We present the results of an in-plane resistivity study of the solid solutions Fe1-xVxBO3. The measurements were made on single crystals with concentration x = 0.02, 0.13, 0.18, 0.3, 0.95, 1.0 in the temperature range 220-600 K. Semiconducting behaviour for samples with x \\ge 0.13 was found. Mott variable-range-hopping transport ρ(T) = ρ0exp(T*/T)α has been observed with α = 1/4 at T<290 K, suggesting carrier localization. Above this temperature the activation-type conductivity, with activation energies, Ea, about 1 eV for all samples, is observed. The possible electronic states and band structure of Fe1-xVxBO3 crystals are discussed in the different pressure ranges: P< PcFe, PcFe< P< PcV, P> PcV, where PcFe, PcV are the critical pressure values for FeBO3 and V BO3, respectively.

  5. In-situ spectroscopic monitoring of the ambient pressure hydrogenation of C2 to ethane on Pt(111)

    NASA Astrophysics Data System (ADS)

    Krooswyk, Joel D.; Kruppe, Christopher M.; Trenary, Michael

    2016-10-01

    The hydrogenation of C2 molecules formed on the Pt(111) surface through acetylene exposure at 750 K was monitored in-situ with reflection absorption infrared spectroscopy (RAIRS) in the presence of up to 10 Torr of H2. The coverage of post-reaction surface carbon was measured with Auger electron spectroscopy. The RAIR spectra show that C2 is hydrogenated to an ethylidyne intermediate. The hydrogenation of ethylidyne was also monitored at 400 K for H2(g) pressures of 1.0 × 10- 2 to 10 Torr. At H2(g) pressures greater than 1.0 Torr, ethylidyne is completely hydrogenated. In an attempt to probe the nature of the C2 adsorption sites, RAIR spectra of coadsorbed CO were obtained. It is found that while C2 does not block CO adsorption, the spectra indicate that the surface carbon is free of hydrogen. In contrast, ethylidyne blocks CO adsorption sites. In the presence of coadsorbed CO, complete hydrogenation of ethylidyne occurs at 450 K versus 400 K in the absence of CO.

  6. Preservation of H2 production activity in nanoporous latex coatings of Rhodopseudomonas palustris CGA009 during dry storage at ambient temperatures

    PubMed Central

    Piskorska, M; Soule, T; Gosse, J L; Milliken, C; Flickinger, M C; Smith, G W; Yeager, C M

    2013-01-01

    Summary To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0–0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27–53% of their H2 production activity after 8 weeks of storage. When stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state. PMID:23331993

  7. PRESERVATION OF H2 PRODUCTION ACTIVITY IN NANOPOROUS LATEX COATINGS OF RHODOPSEUDOMONAS PALUSTRIS CGA009 DURING DRY STORAGE AT AMBIENT TEMPERATURES

    SciTech Connect

    Milliken, C.; Piskorska, M.; Soule, T.; Gosse, J.; Flickinger, M.; Smith, G.; Yeager, C.

    2012-08-27

    To assess the applicability of latex cell coatings as an "off-the-shelf' biocatalyst, the effect of osmoprotectants, temperature, humidity and O{sub 2} on preservation of H{sub 2} production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H{sub 2} production. Beyond 2 weeks of storage, sorbitol- treated coatings lost all H{sub 2} production activity, whereas considerable H{sub 2} production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H{sub 2} production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H{sub 2} (0-0.1% headspace accumulation), whereas those stored at <5% humidity retained 27-53% of their H{sub 2} production activity after 8 weeks of storage. When stored in argon at <5% humidity and room temperature, R. palustris coatings retained full H{sub 2} production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.

  8. Using “Tender” x-ray ambient pressure x-Ray photoelectron spectroscopy as a direct probe of solid-liquid interface

    SciTech Connect

    Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua; Rani, Sana; Chang, Rui; Karlsson, Patrik G.; Edwards, Mårten O. M.; Lundqvist, Måns; Moberg, Robert; Ross, Phil; Hussain, Zahid; Liu, Zhi

    2015-05-07

    We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV–7 keV), we are able to access the interface between liquid and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt²⁺ and Pt⁴⁺ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.

  9. Using “Tender” x-ray ambient pressure x-Ray photoelectron spectroscopy as a direct probe of solid-liquid interface

    DOE PAGESBeta

    Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua; Rani, Sana; Chang, Rui; Karlsson, Patrik G.; Edwards, Mårten O. M.; Lundqvist, Måns; Moberg, Robert; Ross, Phil; et al

    2015-05-07

    We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV–7 keV), we are able to access the interface between liquidmore » and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt²⁺ and Pt⁴⁺ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.« less

  10. Using “Tender” X-ray Ambient Pressure X-Ray Photoelectron Spectroscopy as A Direct Probe of Solid-Liquid Interface

    PubMed Central

    Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua; Rani, Sana; Chang, Rui; Karlsson, Patrik G.; Edwards, Mårten O. M.; Lundqvist, Måns; Moberg, Robert; Ross, Phil; Hussain, Zahid; Liu, Zhi

    2015-01-01

    We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV–7 keV), we are able to access the interface between liquid and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt2+ and Pt4+ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry. PMID:25950241

  11. SiO{sub 2}-like film deposition by dielectric barrier discharge plasma gun at ambient temperature under an atmospheric pressure

    SciTech Connect

    Chen Qiang; Zhang Yuefei; Han Erli; Ge Yuanjing

    2006-11-15

    A medium-frequency dielectric barrier discharge (DBD) plasma gun was used to deposit SiO{sub 2}-like films at ambient temperature under atmospheric pressure. SiO{sub 2}-like films were deposited on Si and stainless-steel surfaces by flowing Ar gas containing hexamethyldisiloxane (HMDSO) monomer through the gun. The authors found that the chemical structure of the deposited SiO{sub 2}-like film strongly depended on the HMDSO monomer ratio in the flowing gas and on the incident power. Fourier transform infrared spectroscopy showed no hydroxyl group in the chemical structure under the low HMDSO ratio in flowing gas or high incident plasma power. Scanning electron microscopy and atomic force microscopy revealed that SiO{sub 2}-like films began to grow as islands and then formed in columns having porosity. Oxygen added to the plasma-gun flow plays a lesser role in the SiO{sub 2}-like deposition from a DBD plasma gun at atmospheric pressure, and the critical temperature for pure SiO{sub 2} formation is also greatly lowered.

  12. Using “Tender” X-ray Ambient Pressure X-Ray Photoelectron Spectroscopy as A Direct Probe of Solid-Liquid Interface

    NASA Astrophysics Data System (ADS)

    Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua; Rani, Sana; Chang, Rui; Karlsson, Patrik G.; Edwards, Mårten O. M.; Lundqvist, Måns; Moberg, Robert; Ross, Phil; Hussain, Zahid; Liu, Zhi

    2015-05-01

    We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV-7 keV), we are able to access the interface between liquid and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt2+ and Pt4+ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.

  13. Recent developments in the experimental investigations of relaxations in pharmaceuticals by dielectric techniques at ambient and elevated pressure.

    PubMed

    Grzybowska, Katarzyna; Capaccioli, Simone; Paluch, Marian

    2016-05-01

    In recent years, there is a growing interest in improving the physicochemical stability of amorphous pharmaceutical solids due to their very promising applications to manufacture medicines characterized by a better water solubility, and consequently by a higher dissolution rate than those of their crystalline counterparts. In this review article, we show that the molecular mobility investigated both in the supercooled liquid and glassy states is the crucial factor required to understand molecular mechanisms that govern the physical stability of amorphous drugs. We demonstrate that pharmaceuticals can be thoroughly examined by means of the broadband dielectric spectroscopy, which is a very useful experimental technique to explore different relaxation processes and crystallization kinetics as well. Such studies conducted in the wide temperature and pressure ranges provide data needed in searching correlations between properties of molecular dynamics and crystallization process, which are aimed at developing effective and efficient methods for stabilizing amorphous drugs. PMID:26705851

  14. Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications

    NASA Astrophysics Data System (ADS)

    Wu, Q. Q.; Huang, L. B.; Liang, H.; Zhao, Y.; Huang, D.; Chen, Z. M.

    2015-06-01

    Hydrogen peroxide (H2O2) and organic peroxides play important roles in the cycle of oxidants and the formation of secondary aerosols in the atmosphere. Recent field observations have suggested that the budget of peroxyacetic acid (PAA, CH3C(O)OOH) is potentially related to the aerosol phase processes, especially to secondary aerosol formation. Here, we present the first laboratory measurements of the uptake coefficient of gaseous PAA and H2O2 onto ambient fine particulate matter (PM2.5) as a function of relative humidity (RH) at 298 K. The results show that the PM2.5, which was collected in an urban area, can take up PAA and H2O2 at the uptake coefficient (γ) of 10-4, and both γPAA and γH2O2 increase with increasing RH. The value of γPAA at 90 % RH is 5.4 ± 1.9 times that at 3 % RH, whereas γH2O2 at 90 % RH is 2.4 ± 0.5 times that at 3 % RH, which suggests that PAA is more sensitive to the RH variation than H2O2 is. Considering the larger Henry's law constant of H2O2 than that of PAA, the smaller RH sensitivity of the H2O2 uptake coefficient suggests that the enhanced uptake of peroxide compounds on PM2.5 under humid conditions is dominated by chemical processes rather than dissolution. Considering that mineral dust is one of the main components of PM2.5 in Beijing, we also determined the uptake coefficients of gaseous PAA and H2O2 on authentic Asian Dust storm (ADS) and Arizona Test Dust (ATD) particles. Compared to ambient PM2.5, ADS shows a similar γ value and RH dependence in its uptake coefficient for PAA and H2O2, while ATD gives a negative dependence on RH. The present study indicates that, in addition to the mineral dust in PM2.5, other components (e.g., soluble inorganic salts) are also important to the uptake of peroxide compounds. When the heterogeneous reaction of PAA on PM2.5 is considered, its atmospheric lifetime is estimated to be 3.0 h on haze days and 7.1 h on non-haze days, values that are in good agreement with the field observations.

  15. Use of ethyl lactate to extract bioactive compounds from Cytisus scoparius: Comparison of pressurized liquid extraction and medium scale ambient temperature systems.

    PubMed

    Lores, Marta; Pájaro, Marta; Álvarez-Casas, Marta; Domínguez, Jorge; García-Jares, Carmen

    2015-08-01

    An important trend in the extraction of chemical compounds is the application of new environmentally friendly, food grade solvents. Ethyl lactate (ethyl 2-hydroxypropanoate), produced by fermentation of carbohydrates, is miscible with both hydrophilic and hydrophobic compounds being a potentially good solvent for bioactive compounds. Despite its relatively wide use as a general solvent, the utilization of ethyl lactate as an extraction solvent has only recently been considered. Here, we evaluate the possible use of ethyl lactate to extract phenolic compounds from wild plants belonging to Cytisus scoparius, and we compare the characteristics of the extracts obtained by Pressurized Solvent Extraction (the total phenolics content, the antioxidant activity and the concentration of the major polyphenols) with those of other extracts obtained with methanol. In order to explore the industrial production of the ethyl lactate Cytisus extract, we also evaluate medium scale ambient temperature setups. The whole plant and the different parts (flowers, branches, and seed pods) were evaluated separately as potential sources of polyphenols. All extracts were analyzed by LC-MS/MS for accurate identification of the major polyphenols. Similar phenolic profiles were obtained when using ethyl lactate or methanol. The main bioactives found in the Cytisus extract were the non-flavonoid phenolic compounds caffeic and protocatechuic acids and 3,4-dihydroxybenzaldehyde; the flavonoids rutin, kaempferol and quercetin; the flavones chrysin, orientin and apigenin; and the alkaloid lupanine. Regarding the comparison of the extraction systems, although the performance of the PLE was much better than that of the ambient-temperature columns, the energy consumption was also much higher. Ethyl lactate has resulted an efficient extraction solvent for polyphenols from C. scoparius, yielding extracts with high levels of plant phenolics and antioxidant activity. The antimicrobial activity of these

  16. A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

    PubMed

    Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

    2014-06-28

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase. PMID:24985659

  17. Silver nanoparticles embedded over porous metal organic frameworks for carbon dioxide fixation via carboxylation of terminal alkynes at ambient pressure.

    PubMed

    Molla, Rostam Ali; Ghosh, Kajari; Banerjee, Biplab; Iqubal, Md Asif; Kundu, Sudipta K; Islam, Sk Manirul; Bhaumik, Asim

    2016-09-01

    Ag nanoparticles (NPs) has been supported over a porous Co(II)-salicylate metal-organic framework to yield a new nanocatalyst AgNPs/Co-MOF and it has been thoroughly characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectrometry (EDX), high-resolution transmission electron microscopy (HR-TEM), UV-vis diffuse reflection spectroscopy (DRS) and N2 adsorption/desorption analysis. The AgNPs/Co-MOF material showed high catalytic activity in the carboxylation of terminal alkynes via CO2 fixation reaction to yield alkynyl carboxylic acids under very mild conditions. Due to the presence of highly reactive AgNPs bound at the porous MOF framework the reaction proceeded smoothly at 1atm CO2 pressure. Moreover, the catalyst is very convenient to handle and it can be reused for several reaction cycles without appreciable loss of catalytic activity in this CO2 fixation reaction, which suggested a promising future of AgNPs/Co-MOF nanocatalyst. PMID:27309859

  18. Microscopic origins of macroscopic properties of silicate melts and glasses at ambient and high pressure: Implications for melt generation and dynamics

    NASA Astrophysics Data System (ADS)

    Lee, Sung Keun

    2005-07-01

    Recent development and advances in solid state NMR, together with theoretical analyses using quantum-chemical calculations and statistical mechanical modeling, have allowed us to estimate and quantify the detailed distributions of cations and anions in model silicate glasses and melts with varying pressure, temperature and composition. How these microscopic, atomic-scale distributions in the melts from NMR and simulations affect the thermodynamic and transport properties relevant to magmatic processes has been extensively explored recently. Here, based on these previous studies, we present a classification scheme to quantify the various aspects of disorder in covalent oxide glasses and melts on scales of less than 1 nm. The scheme includes contributions from both chemical and topological disorder. Chemical disorder can further be divided into [1] connectivity, which quantifies the extent of mixing among framework units (often parameterized by the degree of Al avoidance or phase separation) and the extent of polymerization (mixing between framework and nonframework cations), and [2] nonframework disorder, which denotes the distribution of network-modifying or charge-balancing cations. Topological disorder includes the distribution of bond lengths and angles. We use this framework of disorder quantification to summarize recent progress on the structures of silicate melts and glasses, mainly obtained from 2D triple quantum magic-angle spinning (3QMAS) NMR, as functions of temperature, pressure, and composition. Most glasses and melts studied show a tendency for chemical ordering in connectivity, nonframework disorder and topological disorder at ambient and high pressure. The chemical ordering in framework disorder, a manifestation of energetics in the melts and glasses, contributes to the total negative deviation of activity of oxides from ideal solution in silicate melts (reduced activity). While no definite evidence of clustering among nonframework cations was found

  19. A fully automated method for simultaneous determination of aflatoxins and ochratoxin A in dried fruits by pressurized liquid extraction and online solid-phase extraction cleanup coupled to ultra-high-pressure liquid chromatography-tandem mass spectrometry.

    PubMed

    Campone, Luca; Piccinelli, Anna Lisa; Celano, Rita; Russo, Mariateresa; Valdés, Alberto; Ibáñez, Clara; Rastrelli, Luca

    2015-04-01

    According to current demands and future perspectives in food safety, this study reports a fast and fully automated analytical method for the simultaneous analysis of the mycotoxins with high toxicity and wide spread, aflatoxins (AFs) and ochratoxin A (OTA) in dried fruits, a high-risk foodstuff. The method is based on pressurized liquid extraction (PLE), with aqueous methanol (30%) at 110 °C, of the slurried dried fruit and online solid-phase extraction (online SPE) cleanup of the PLE extracts with a C18 cartridge. The purified sample was directly analysed by ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for sensitive and selective determination of AFs and OTA. The proposed analytical procedure was validated for different dried fruits (vine fruit, fig and apricot), providing method detection and quantification limits much lower than the AFs and OTA maximum levels imposed by EU regulation in dried fruit for direct human consumption. Also, recoveries (83-103%) and repeatability (RSD < 8, n = 3) meet the performance criteria required by EU regulation for the determination of the levels of mycotoxins in foodstuffs. The main advantage of the proposed method is full automation of the whole analytical procedure that reduces the time and cost of the analysis, sample manipulation and solvent consumption, enabling high-throughput analysis and highly accurate and precise results. PMID:25694147

  20. Long-Term Exposure to Concentrated Ambient PM2.5 Increases Mouse Blood Pressure through Abnormal Activation of the Sympathetic Nervous System: A Role for Hypothalamic Inflammation

    PubMed Central

    Xu, Xiaohua; Bai, Yuntao; Zhong, Jixin; Chen, Minjie; Liang, Yijia; Zhao, Jinzhuo; Liu, Dongyao; Morishita, Masako; Sun, Qinghua; Spino, Catherine; Brook, Robert D.; Harkema, Jack R.; Rajagopalan, Sanjay

    2013-01-01

    Background: Exposure to particulate matter ≤ 2.5 μm in diameter (PM2.5) increases blood pressure (BP) in humans and animal models. Abnormal activation of the sympathetic nervous system may have a role in the acute BP response to PM2.5 exposure. The mechanisms responsible for sympathetic nervous system activation and its role in chronic sustenance of hypertension in response to PM2.5 exposure are currently unknown. Objectives: We investigated whether central nervous system inflammation may be implicated in chronic PM2.5 exposure-induced increases in BP and sympathetic nervous system activation. Methods: C57BL/6J mice were exposed to concentrated ambient PM2.5 (CAPs) for 6 months, and we analyzed BP using radioactive telemetric transmitters. We assessed sympathetic tone by measuring low-frequency BP variability (LF-BPV) and urinary norepinephrine excretion. We also tested the effects of acute pharmacologic inhibitors of the sympathetic nervous system and parasympathetic nervous system. Results: Long-term CAPs exposure significantly increased basal BP, paralleled by increases in LF-BPV and urinary norepinephrine excretion. The increased basal BP was attenuated by the centrally acting α2a agonist guanfacine, suggesting a role of increased sympathetic tone in CAPs exposure–induced hypertension. The increase in sympathetic tone was accompanied by an inflammatory response in the arcuate nucleus of the hypothalamus, evidenced by increased expression of pro-inflammatory genes and inhibitor kappaB kinase (IKK)/nuclear factor–kappaB (NF-κB) pathway activation. Conclusion: Long-term CAPs exposure increases BP through sympathetic nervous system activation, which may involve hypothalamic inflammation. Citation: Ying Z, Xu X, Bai Y, Zhong J, Chen M, Liang Y, Zhao J, Liu D, Morishita M, Sun Q, Spino C, Brook RD, Harkema JR, Rajagopalan S. 2014. Long-term exposure to concentrated ambient PM2.5 increases mouse blood pressure through abnormal activation of the sympathetic

  1. Dry Mouth

    MedlinePlus

    ... of this page please turn Javascript on. Dry Mouth What Is Dry Mouth? Dry mouth is the feeling that there is ... when a person has dry mouth. How Dry Mouth Feels Dry mouth can be uncomfortable. Some people ...

  2. Behavior of aircraft antiskid braking systems on dry and wet runway surfaces - A velocity-rate-controlled, pressure-bias-modulated system

    NASA Technical Reports Server (NTRS)

    Stubbs, S. M.; Tanner, J. A.

    1976-01-01

    During maximum braking the average ratio of drag-force friction coefficient developed by the antiskid system to maximum drag-force friction coefficient available at the tire/runway interface was higher on dry surfaces than on wet surfaces. The gross stopping power generated by the brake system on the dry surface was more than twice that obtained on the wet surfaces. With maximum braking applied, the average ratio of side-force friction coefficient developed by the tire under antiskid control to maximum side-force friction available at the tire/runway interface of a free-rolling yawed tire was shown to decrease with increasing yaw angle. Braking reduced the side-force friction coefficient on a dry surface by 75 percent as the wheel slip ratio was increased to 0.3; on a flooded surface the coefficient dropped to near zero for the same slip ratio. Locked wheel skids were observed when the tire encountered a runway surface transition from dry to flooded, due in part to the response time required for the system to sense abrupt changes in the runway friction; however, the antiskid system quickly responded by reducing brake pressure and cycling normally during the remainder of the run on the flooded surface.

  3. Ambient Pressure XPS Study of Mixed Conducting Perovskite-Type SOFC Cathode and Anode Materials under Well-Defined Electrochemical Polarization

    PubMed Central

    2015-01-01

    The oxygen exchange activity of mixed conducting oxide surfaces has been widely investigated, but a detailed understanding of the corresponding reaction mechanisms and the rate-limiting steps is largely still missing. Combined in situ investigation of electrochemically polarized model electrode surfaces under realistic temperature and pressure conditions by near-ambient pressure (NAP) XPS and impedance spectroscopy enables very surface-sensitive chemical analysis and may detect species that are involved in the rate-limiting step. In the present study, acceptor-doped perovskite-type La0.6Sr0.4CoO3-δ (LSC), La0.6Sr0.4FeO3-δ (LSF), and SrTi0.7Fe0.3O3-δ (STF) thin film model electrodes were investigated under well-defined electrochemical polarization as cathodes in oxidizing (O2) and as anodes in reducing (H2/H2O) atmospheres. In oxidizing atmosphere all materials exhibit additional surface species of strontium and oxygen. The polaron-type electronic conduction mechanism of LSF and STF and the metal-like mechanism of LSC are reflected by distinct differences in the valence band spectra. Switching between oxidizing and reducing atmosphere as well as electrochemical polarization cause reversible shifts in the measured binding energy. This can be correlated to a Fermi level shift due to variations in the chemical potential of oxygen. Changes of oxidation states were detected on Fe, which appears as FeIII in oxidizing atmosphere and as mixed FeII/III in H2/H2O. Cathodic polarization in reducing atmosphere leads to the reversible formation of a catalytically active Fe0 phase. PMID:26877827

  4. Detection of Amines and Ammonia with an Ambient Pressure Mass Spectrometer using a Corona Discharge Ion Source, in an Urban Atmosphere and in a Teflon Film Chamber

    NASA Astrophysics Data System (ADS)

    Alves, M.; Hanson, D. R.; Grieves, C.; Ortega, J. V.

    2015-12-01

    Amines and ammonia are an important group of molecules that can greatly affect atmospheric particle formation that can go on to impact cloud formation and their scattering of thermal and solar radiation, and as a result human health and ecosystems. In this study, an Ambient Pressure Mass Spectrometer (AmPMS) that is selective and sensitive to molecules with a high proton affinity, such as amines, was coupled with a newly built corona discharge ion source. AmPMS was used to monitor many different nitrogenous compound that are found in an urban atmosphere (July 2015, Minneapolis), down to the single digit pmol/mol level. Simultaneous to this, a proton transfer mass spectrometer also sampled the atmosphere through an inlet within 20 m of the AmPMS inlet. In another set of studies, a similar AmPMS was attached to a large Teflon film chamber at the Atmospheric Chemistry Division at NCAR (August 2015, Boulder). Exploratory studies are planned on the sticking of amines to the chamber walls as well as oxidizing the amine and monitoring products. Depending on the success of these studies, results will be presented on the reversability of amine partitioning and mass balance for these species in the chamber.

  5. Adsorption of acetic acid on ice studied by ambient-pressure XPS and partial-electron-yield NEXAFS spectroscopy at 230-240 K.

    PubMed

    Křepelová, Adéla; Bartels-Rausch, Thorsten; Brown, Matthew A; Bluhm, Hendrik; Ammann, Markus

    2013-01-17

    Ice plays a key role in the environment, and the ice-air interface influences heterogeneous chemical reactions between snowpack or cirrus clouds and the surrounding air. Soluble gases have been suspected to affect the topmost, disordered layer on ice (often referred to as a quasiliquid layer, QLL). Changes are especially expected in the hydrogen-bonding structure of water in the presence of solutes at the ice surface. Here, we used ambient-pressure X-ray photoelectron spectroscopy (XPS) to detect acetic acid at the ice surface at 230-240 K under atmospheric conditions for the first time. Electron-kinetic-energy-dependent C 1s spectra indicate that acetic acid remains confined to the topmost ice surface layers. Spectral analysis provides information about the protonation state of acetate at the ice surface. Surface-sensitive Auger-electron-yield C-edge near-edge X-ray absorption fine structure (NEXAFS) spectra were recorded to probe the molecular state of the adsorbed species. The O-edge NEXAFS spectra show only minor differences between clean ice and ice with adsorbed acetic acid and thus indicate that acetic acid does not lead to an extended disordered layer on the ice surface between 230 and 240 K. PMID:23252403

  6. Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy

    SciTech Connect

    Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik; Salmeron, Miquel

    2010-03-31

    The adsorption of water on KBr thin films evaporated onto SiO2 was investigated as a function of relative humidity (RH) by ambient pressure X-ray photoelectron spectroscopy. At 30percent RH adsorbed water reaches a coverage of approximately one monolayer. As the humidity continues to increase, the coverage of water remains constant or increases very slowly until 60percent RH, followed by a rapid increase up to 100percent RH. At low RH a significant number of the Br atoms are lost due to irradiation damage. With increasing humidity solvation increases ion mobility and gives rise to a partial recovery of the Br/K ratio. Above 60percent RH the increase of the Br/K ratio accelerates. Above the deliquescence point (85percent RH), the thickness of the water layer continues to increase and reaches more than three layers near saturation. The enhancement of the Br/K ratio at this stage is roughly a factor 2.3 on a 0.5 nm KBr film, indicating a strong preferential segregation of Br ions to the surface of the thin saline solution on SiO2.

  7. Staying dry under water

    NASA Astrophysics Data System (ADS)

    Jones, Paul; Cruz-Chu, Eduardo; Megaridis, Constantine; Walther, Jens; Koumoutsakos, Petros; Patankar, Neelesh

    2012-11-01

    Lotus leaves are known for their non-wetting properties due to the presence of surface texture. The superhydrophobic behavior arises because of the prevention of liquid water from entering the pores of the roughness. Present superhydrophobic materials rely on air trapped within the surface pores to avoid liquid permeation. This is typically unsustainable for immersed bodies due to dissolution of the air, especially under elevated pressures. Here, molecular dynamics simulations are used to demonstrate the non-wetting behavior of an immersed ten-nanometer pore. This is accomplished by establishing thermodynamically sustained vapor pockets of the surrounding liquid medium. Over 300,000 atoms were used to construct the nanopore geometry and simulate SPC/E water molecules. Ambient pressure was varied along two isotherms (300 K, and 500 K). This approach for vapor-stabilization could offer valuable guidance for maintaining surfaces dry even in a submerged state without relying on trapped air. The approach may be extended to control general phase behavior of water adjacent to textured surfaces. ISEN support is gratefully acknowledged.

  8. century drying

    NASA Astrophysics Data System (ADS)

    Cook, Benjamin I.; Smerdon, Jason E.; Seager, Richard; Coats, Sloan

    2014-11-01

    Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twenty-first century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman-Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both

  9. Pressurized pyrolysis of dried distillers grains with solubles and canola seed press cake in a fixed-bed reactor.

    PubMed

    Ateş, Funda; Miskolczi, Norbert; Saricaoğlu, Beyza

    2015-02-01

    Pressurized pyrolysis of biomasses was carried in a fixed bed reactor to obtain gases, bio-oils and chars at elevated temperatures. The products were characterized by GC-MS, FTIR, viscometer, SEM, BET and EDXRFS methods. Experiments were performed at 1, 5 and 10 bar pressure and 400, 500 and 600°C temperatures. The experimental results show that in all the experimental condition the yield of bio-oil from DDGS as higher than that of canola. Yield of non-condensable gases and chars increased, while that of liquid products decreased by pressure. Increasing pressure favoured the formation of low molecular weight gas, such as H2. Maximum surface area of chars was obtained at atmospheric pressure and the surface areas decreased rapidly with increasing pressure. GC/MS results shows that the amount of fatty acids in bio-oils was increased by increasing pressure and bio-oils showed non-Newtonian behavior. Based on EDXRFS results, bio-oils and char contained lots of elements. PMID:25484126

  10. Endotoxin and β-1,3-d-Glucan in Concentrated Ambient Particles Induce Rapid Increase in Blood Pressure in Controlled Human Exposures.

    PubMed

    Zhong, Jia; Urch, Bruce; Speck, Mary; Coull, Brent A; Koutrakis, Petros; Thorne, Peter S; Scott, James; Liu, Ling; Brook, Robert D; Behbod, Behrooz; Gibson, Heike; Silverman, Frances; Mittleman, Murray A; Baccarelli, Andrea A; Gold, Diane R

    2015-09-01

    Short-term exposure to particulate matter (PM) is associated with increased blood pressure (BP) in epidemiological studies. Understanding the impact of specific PM components on BP is essential in developing effective risk-reduction strategies. We investigated the association between endotoxin and β-1,3-d-Glucan-two major biological PM components-and BP. We also examined whether vascular endothelial growth factor, a vasodilatory inflammatory marker, modified these associations. We conducted a single-blind, randomized, crossover trial of controlled human exposure to concentrated ambient particles with 50 healthy adults. Particle-associated-endotoxin and β-1,3-d-Glucan were sampled using polycarbonate-membrane-filters. Supine resting systolic BP and diastolic BP were measured pre-, 0.5-hour post-, and 20-hour postexposure. Urine vascular endothelial growth factor concentration was determined using enzyme-linked immunosorbant assay and creatinine-corrected. Exposures to endotoxin and β-1,3-d-Glucan for 130 minutes were associated with increases in BPs: at 0.5-hour postexposure, every doubling in endotoxin concentration was associated with 1.73 mm Hg higher systolic BP (95% confidence interval, 0.28, 3.18; P=0.02) and 2.07 mm Hg higher diastolic BP (95% confidence interval, 0.74, 3.39; P=0.003); every doubling in β-1,3-d-Glucan concentration was associated with 0.80 mm Hg higher systolic BP (95% confidence interval, -0.07, 1.67; P=0.07) and 0.88 mm Hg higher diastolic BP (95% confidence interval, 0.09, 1.66; P=0.03). Vascular endothelial growth factor rose after concentrated ambient particle endotoxin exposure and attenuated the association between endotoxin and 0.5-hour postexposure diastolic BP (Pinteraction=0.02). In healthy adults, short-term endotoxin and β-1,3-d-Glucan exposures were associated with increased BP. Our findings suggest that the biological PM components contribute to PM-related cardiovascular outcomes, and postexposure vascular endothelial

  11. Behavior of aircraft antiskid braking systems on dry and wet runway surfaces. A slip-velocity-controlled, pressure-bias-modulated system

    NASA Technical Reports Server (NTRS)

    Stubbs, S. M.; Tanner, J. A.; Smith, E. G.

    1979-01-01

    The braking and cornering response of a slip velocity controlled, pressure bias modulated aircraft antiskid braking system is investigated. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC 9 series 10 airplane. The landing gear strut was replaced by a dynamometer. The parameters, which were varied, included the carriage speed, tire loading, yaw angle, tire tread condition, brake system operating pressure, and runway wetness conditions. The effects of each of these parameters on the behavior of the skid control system is presented. Comparisons between data obtained with the skid control system and data obtained from single cycle braking tests without antiskid protection are examined.

  12. Ambient-pressure organic superconductor

    DOEpatents

    Williams, Jack M.; Wang, Hsien-Hau; Beno, Mark A.

    1986-01-01

    A new class of organic superconductors having the formula (ET).sub.2 MX.sub.2 wherein ET represents bis(ethylenedithio)-tetrathiafulvalene, M is a metal such as Au, Ag, In, Tl, Rb, Pd and the like and X is a halide. The superconductor (ET).sub.2 AuI.sub.2 exhibits a transition temperature of 5 K which is high for organic superconductors.

  13. Near-Ambient-Pressure X-ray Photoelectron Spectroscopy Study of Methane-Induced Carbon Deposition on Clean and Copper-Modified Polycrystalline Nickel Materials

    PubMed Central

    2015-01-01

    In order to simulate solid-oxide fuel cell (SOFC)-related coking mechanisms of Ni, methane-induced surface carbide and carbon growth was studied under close-to-real conditions by synchrotron-based near-ambient-pressure (NAP) X-ray photoelectron spectroscopy (XPS) in the temperature region between 250 and 600 °C. Two complementary polycrystalline Ni samples were used, namely, Ni foam—serving as a model structure for bulk Ni in cermet materials such as Ni/YSZ—and Ni foil. The growth mechanism of graphene/graphite species was found to be closely related to that previously described for ethylene-induced graphene growth on Ni(111). After a sufficiently long “incubation” period of the Ni foam in methane at 0.2 mbar and temperatures around 400 °C, cooling down to ∼250 °C, and keeping the sample at this temperature for 50–60 min, initial formation of a near-surface carbide phase was observed, which exhibited the same spectroscopic fingerprint as the C2H4 induced Ni2C phase on Ni(111). Only in the presence of this carbidic species, subsequent graphene/graphite nucleation and growth was observed. Vice versa, the absence of this species excluded further graphene/graphite formation. At temperatures above 400 °C, decomposition/bulk dissolution of the graphene/graphite phase was observed on the rather “open” surface of the Ni foam. In contrast, Ni foil showed—under otherwise identical conditions—predominant formation of unreactive amorphous carbon, which can only be removed at ≥500 °C by oxidative clean-off. Moreover, the complete suppression of carbide and subsequent graphene/graphite formation by Cu-alloying of the Ni foam and by addition of water to the methane atmosphere was verified. PMID:26692914

  14. Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

    NASA Astrophysics Data System (ADS)

    Amende, Max; Kaftan, Andre; Bachmann, Philipp; Brehmer, Richard; Preuster, Patrick; Koch, Marcus; Wasserscheid, Peter; Libuda, Jörg

    2016-01-01

    The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al2O3 model catalysts, and near-ambient pressure (NAP) measurements on real core-shell Pt/Al2O3 catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al2O3 model catalyst and core-shell pellet were only partially restored under the applied reaction conditions. Whereas partial regeneration on facet-like sites on supported catalysts is more facile than on Pt(111), carbonaceous deposits adsorbed at low-coordinated defect sites impede full regeneration of the Pt/Al2O3 catalysts.

  15. Turbine airfoil with ambient cooling system

    DOEpatents

    Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.

    2016-06-07

    A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.

  16. Modification of surface energy, dry etching, and organic film removal using atmospheric-pressure pulsed-corona plasma

    SciTech Connect

    Yamamoto, Toshiaki; Newsome, J.R.; Ensor, D.S.

    1995-05-01

    A laboratory-scale atmospheric-pressure plasma reactor, using a nanosecond pulsed corona, was constructed to demonstrate potential applications ranging from modification of surface energy to removal of surface organic films. For surface modification studies, three different substrates were selected to evaluate the surface energies: bare aluminum, polyurethane, and silicon coated with photoresist. The critical surface energy for all materials studied significantly increased after the plasma treatment. The effects of gas composition and plasma treatment time were also investigated. Photoresist, ethylene glycol, and Micro surfactant were used as test organic films. The etching rate of a photoresist coating on silicon was 9 nm/min. Organic film removal using atmospheric pressure plasma technology was shown to be feasible.

  17. Profiling of acylcarnitines and sterols from dried blood or plasma spot by atmospheric pressure thermal desorption chemical ionization (APTDCI) tandem mass spectrometry.

    PubMed

    Corso, Gaetano; D'Apolito, Oceania; Garofalo, Daniela; Paglia, Giuseppe; Dello Russo, Antonio

    2011-11-01

    Free carnitine and acylcarnitines play an important role in the metabolism of fatty acids. Sterols are structural lipids found in the membranes of many eukaryotic cells, and they also have functional roles such as the regulation of membrane permeability and fluidity, activity of membrane-bound enzymes and signals transduction. Abnormal profiles of these compounds in biological fluids may be useful markers of metabolic changes. In this review, we describe the subset of the lipidome represented by acylcarnitines and sterols, and we summarize how these compounds have been analyzed in the past. Over the last 50years, lipid mass spectrometry (MS) has evolved to become one of the most useful techniques for metabolic analysis. Today, the introduction of new ambient ionization techniques coupled to MS (AMS), which are characterized by the direct desorbing/ionizing of molecules from solid samples, is generating new possibilities for in situ analysis. Recently, we developed an AMS approach called APTDCI to desorb/ionize using a heated gas flow and an electrical discharge to directly analyze sterols and indirectly investigate acylcarnitines in dried blood or plasma spot samples. Here, we also describe the APTDCI method and some of its clinical applications, and we underline the common complications and issues that remain to be resolved. PMID:21683155

  18. Ambient Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Huang, Min-Zong; Yuan, Cheng-Hui; Cheng, Sy-Chyi; Cho, Yi-Tzu; Shiea, Jentaie

    2010-07-01

    Mass spectrometric ionization methods that operate under ambient conditions and require minimal or no sample pretreatment have attracted much attention in such fields as biomedicine, food safety, antiterrorism, pharmaceuticals, and environmental pollution. These technologies usually involve separate ionization and sample-introduction events, allowing independent control over each set of conditions. Ionization is typically performed under ambient conditions through use of existing electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) techniques. Rapid analyses of gas, liquid, and solid samples are possible with the adoption of various sample-introduction methods. This review sorts different ambient ionization techniques into two main subcategories, primarily on the basis of the ionization processes, that are further differentiated in terms of the approach used for sampling.

  19. Accurate mass fragment library for rapid analysis of pesticides on produce using ambient pressure desorption ionization with high-resolution mass spectrometry.

    PubMed

    Kern, Sara E; Lin, Lora A; Fricke, Frederick L

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]⁺) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]⁺ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]⁺ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli

  20. Accurate Mass Fragment Library for Rapid Analysis of Pesticides on Produce Using Ambient Pressure Desorption Ionization with High-Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Kern, Sara E.; Lin, Lora A.; Fricke, Frederick L.

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]+) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]+ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]+ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli. The

  1. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources

    SciTech Connect

    Shavorskiy, Andrey; Slaughter, Daniel S.; Zegkinoglou, Ioannis; Rude, Bruce S.; Bluhm, Hendrik; Neppl, Stefan; Cryan, James P.; Siefermann, Katrin R.; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P.; Fraund, Matthew W.; Khurmi, Champak; Wright, Travis W.; Schoenlein, Robert W.; Gessner, Oliver; Hertlein, Marcus P.; Tyliszczak, Tolek; Huse, Nils; and others

    2014-09-15

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ∼0.1 mm spatial resolution and ∼150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E{sub p} = 150 eV and an electron kinetic energy range KE = 503–508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ∼9 ns at a pass energy of 50 eV and ∼1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular

  2. High-temperature superconducting radiofrequency probe for magnetic resonance imaging applications operated below ambient pressure in a simple liquid-nitrogen cryostat

    NASA Astrophysics Data System (ADS)

    Lambert, Simon; Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Darrasse, Luc

    2013-05-01

    The present work investigates the joined effects of temperature and static magnetic field on the electrical properties of a 64 MHz planar high-temperature superconducting (HTS) coil, in order to enhance the signal-to-noise ratio (SNR) in nuclear magnetic resonance (NMR) applications with a moderate decrease of the HTS coil temperature (THTS). Temperature control is provided with accuracy better than 0.1 K from 80 to 66 K by regulating the pressure of the liquid nitrogen bath of a dedicated cryostat. The actual temperature of the HTS coil is obtained using a straightforward wireless method that eliminates the risks of coupling electromagnetic interference to the HTS coil and of disturbing the static magnetic field by DC currents near the region of interest. The resonance frequency ( f0) and the quality factor (Q) of the HTS coil are measured as a function of temperature in the 0-4.7 T field range with parallel and orthogonal orientations relative to the coil plane. The intrinsic HTS coil sensitivity and the detuning effect are then analyzed from the Q and f0 data. In the presence of the static magnetic field, the initial value of f0 in Earth's field could be entirely recovered by decreasing THTS, except for the orthogonal orientation above 1 T. The improvement of Q by lowering THTS was substantial. From 80 to 66 K, Q was multiplied by a factor of 6 at 1.5 T in orthogonal orientation. In parallel orientation, the maximum measured improvement of Q from 80 K to 66 K was a factor of 2. From 80 to 66 K, the improvement of the RF sensitivity relative to the initial value at the Earth's field and ambient pressure was up to 4.4 dB in parallel orientation. It was even more important in orthogonal orientation and continued to increase, up to 8.4 dB, at the maximum explored field of 1.5 T. Assuming that the noise contributions from the RF receiver are negligible, the SNR improvement using enhanced HTS coil cooling in NMR experiments was extracted from Q measurements either

  3. High temperature post-irradiation performance of spent pressurized-water-reactor fuel rods under dry-storage conditions

    SciTech Connect

    Einziger, R.E.; Atkin, S.D.; Stellrecht, D.E.; Pasupathi, V.

    1981-06-01

    Post-irradiation studies on failure mechanisms of well characterized PWR rods were conducted for up to a year at 482, 510 and 571/sup 0/C in unlimited air and inert gas atmospheres. No cladding breaches occurred even though the tests operated many orders of magnitude longer in time than the lifetime predicted by Blackburn's analyses. The extended lifetime is due to significant creep strain of the Zircaloy cladding which decreases the internal rod pressures. The cladding creep also contributes to radial cracks, through the external oxide and internal FCCI layers, which propagated into and arrested in an oxygen stabilized ..cap alpha..-Zircaloy layer. There were no signs of either additional cladding hydriding, stress-corrosion cracking or fuel pellet degradation. Using the Larson-Miller formulization, a conservative maximum storage temperature of 400/sup 0/C is recommended to ensure a 1000-year cladding lifetime. This accounts for crack propagation and assumes annealing of the irradiation-hardened cladding.

  4. Near-ambient solid polymer fuel cell

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.

    1993-01-01

    Fuel cells are extremely attractive for extraterrestrial and terrestrial applications because of their high energy conversion efficiency without noise or environmental pollution. Among the various fuel cell systems the advanced polymer electrolyte membrane fuel cells based on sulfonated fluoropolymers (e.g., Nafion) are particularly attractive because they are fairly rugged, solid state, quite conductive, of good chemical and thermal stability and show good oxygen reduction kinetics due to the low specific adsorption of the electrolyte on the platinum catalyst. The objective of this program is to develop a solid polymer fuel cell which can efficiently operate at near ambient temperatures without ancillary components for humidification and/or pressurization of the fuel or oxidant gases. During the Phase 1 effort we fabricated novel integral electrode-membrane structures where the dispersed platinum catalyst is precipitated within the Nafion ionomer. This resulted in electrode-membrane units without interfacial barriers permitting unhindered water diffusion from cathode to anode. The integral electrode-membrane structures were tested as fuel cells operating on H2 and O2 or air at 1 to 2 atm and 10 to 50 C without gas humidification. We demonstrated that cells with completely dry membranes could be self started at room temperature and subsequently operated on dry gas for extended time. Typical room temperature low pressure operation with unoptimized electrodes yielded 100 mA/cm(exp 2) at 0.5V and maximum currents over 300 mA/cm(exp 2) with low platinum loadings. Our results clearly demonstrate that operation of proton exchange membrane fuel cells at ambient conditions is feasible. Optimization of the electrode-membrane structure is necessary to assess the full performance potential but we expect significant gains in weight and volume power density for the system. The reduced complexity will make fuel cells also attractive for smaller and portable power supplies and as

  5. Drying of fiber webs

    DOEpatents

    Warren, David W.

    1997-01-01

    A process and an apparatus for high-intensity drying of fiber webs or sheets, such as newsprint, printing and writing papers, packaging paper, and paperboard or linerboard, as they are formed on a paper machine. The invention uses direct contact between the wet fiber web or sheet and various molten heat transfer fluids, such as liquified eutectic metal alloys, to impart heat at high rates over prolonged durations, in order to achieve ambient boiling of moisture contained within the web. The molten fluid contact process causes steam vapor to emanate from the web surface, without dilution by ambient air; and it is differentiated from the evaporative drying techniques of the prior industrial art, which depend on the uses of steam-heated cylinders to supply heat to the paper web surface, and ambient air to carry away moisture, which is evaporated from the web surface. Contact between the wet fiber web and the molten fluid can be accomplished either by submersing the web within a molten bath or by coating the surface of the web with the molten media. Because of the high interfacial surface tension between the molten media and the cellulose fiber comprising the paper web, the molten media does not appreciately stick to the paper after it is dried. Steam generated from the paper web is collected and condensed without dilution by ambient air to allow heat recovery at significantly higher temperature levels than attainable in evaporative dryers.

  6. Drying of fiber webs

    DOEpatents

    Warren, D.W.

    1997-04-15

    A process and an apparatus are disclosed for high-intensity drying of fiber webs or sheets, such as newsprint, printing and writing papers, packaging paper, and paperboard or linerboard, as they are formed on a paper machine. The invention uses direct contact between the wet fiber web or sheet and various molten heat transfer fluids, such as liquefied eutectic metal alloys, to impart heat at high rates over prolonged durations, in order to achieve ambient boiling of moisture contained within the web. The molten fluid contact process causes steam vapor to emanate from the web surface, without dilution by ambient air; and it is differentiated from the evaporative drying techniques of the prior industrial art, which depend on the uses of steam-heated cylinders to supply heat to the paper web surface, and ambient air to carry away moisture, which is evaporated from the web surface. Contact between the wet fiber web and the molten fluid can be accomplished either by submersing the web within a molten bath or by coating the surface of the web with the molten media. Because of the high interfacial surface tension between the molten media and the cellulose fiber comprising the paper web, the molten media does not appreciatively stick to the paper after it is dried. Steam generated from the paper web is collected and condensed without dilution by ambient air to allow heat recovery at significantly higher temperature levels than attainable in evaporative dryers. 6 figs.

  7. Oxidation Behavior and Cracking Susceptibility of Ni-Cr Alloys in Dry Steam and Inert Gas under Extremely-Low Oxygen Partial Pressure

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Kenmoku, Yasuhiro; Endo, Takayuki; Miyazaki, Takamichi; Watanabe, Yutaka

    In order to investigate oxidation behavior and cracking susceptibility of the Ni-Cr alloys under extremely-low oxygen partial pressure, three Ni-Cr alloys (Ni-14Cr, Ni-22Cr and Ni-30Cr) were used as plate specimen and reverse U-bend specimen for oxidation experiments for 750 hours at 400 °C in two kinds of gas system (inert gas and dry steam) under various oxygen potential (Ni stable, Ni/NiO equilibrium and NiO stable). The Ni-Cr alloys cracked along grain boundary both in inert gas system (with trace O2, without H2O) and in hydrogenated steam. In the inert gas system, the cracking susceptibility was confirmed in near NiO stable condition. On the other hand, no crack was found in near Ni stable condition. In the dry steam system, the cracking susceptibility was confirmed in near Ni/NiO equilibrium. In contrast, no crack was found in near NiO stable condition. The cracking susceptibility was confirmed in near Ni/NiO equilibrium in hydrogenated steam as contrasted with higher oxygen potential in inert gas system. This result shows that potential range for the cracking susceptibility seemed to be different between the two kinds of gas system. Cracking severity was highest for Ni-14Cr and lowest for Ni-30Cr both in inert gas and steam; however, even Ni-30Cr was not immune to intergranular cracking in steam near Ni/NiO equilibrium.

  8. Correlation between Charge State of Insulating NaCl Surfaces and Ionic Mobility Induced by Water Adsorption: A Combined Ambient Pressure X-ray Photoelectron Spectroscopy and Scanning Force Microscopy Study

    SciTech Connect

    Verdaguer, Albert; Jose Segura, Juan; Fraxedas, Jordi; Bluhm, Hendrik; Salmeron, Miquel

    2008-09-03

    In situ ambient pressure X-ray photoelectron spectroscopy (APPES) and scanning force microscopy were used to characterize the surface discharge induced by water layers grown on (001) surfaces of sodium chloride single crystals. The APPES studies show that both kinetic energy (KE) and full width at half-maximum (FWHM) of the Na 2s and Cl 2p core level peaks, monitored as a function of relative humidity (RH), mimic surface conductivity curves measured using scanning force microscopy. The KE position and FWHM of the core level peaks therefore are directly related to the solvation and diffusion of ions at the NaCl(100) surface upon adsorption of water.

  9. Dry hair

    MedlinePlus

    ... or using harsh soaps or alcohols Excessive blow-drying Dry air Menkes kinky hair syndrome Malnutrition Underactive ... or twice a week Add conditioners Avoid blow drying and harsh styling products

  10. Dry hair

    MedlinePlus

    Some causes of dry hair are: Anorexia nervosa Excessive hair washing, or using harsh soaps or alcohols Excessive blow-drying Dry air Menkes kinky hair syndrome Malnutrition Underactive parathyroid ( ...

  11. Dry pressing technical ceramics

    SciTech Connect

    Lewis, W.A. Jr.

    1996-04-01

    Dry pressing of technical ceramics is a fundamental method of producing high-quality ceramic components. The goals of dry pressing technical ceramics are uniform compact size and green density, consistent part-to-part green density and defect-free compact. Dry pressing is the axial compaction of loosely granulated dry ceramic powders (< 3% free moisture) within a die/punch arrangement. The powder, under pressure, conforms to the specific shape of the punch faces and die. Powder compaction occurs within a rigid-walled die and usually between a top and bottom punch. Press configurations include anvil, rotary, multiple-punch and multiple-action.

  12. Evaluation of fermentation, drying, and high pressure processing on viability of Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Trichinella spiralis in raw pork and/or Genoa salami

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effectiveness of fermentation, drying, and high pressure processing (HPP) to inactivate Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Trichinella spiralis in Genoa salami produced with trichinae infected pork. In addition, we evaluated the effectiveness of u...

  13. Imaging with ambient noise

    SciTech Connect

    Snieder, Roel; Wapenaar, Kees

    2010-09-15

    Recent developments in seismology, ultrasonics, and underwater acoustics have led to a radical change in the way scientists think about ambient noise--the diffuse waves generated by pressure fluctuations in the atmosphere, the scattering of water waves in the ocean, and any number of other sources that pervade our world. Because diffuse waves consist of the superposition of waves propagating in all directions, they appear to be chaotic and random. That appearance notwithstanding, diffuse waves carry information about the medium through which they propagate.

  14. Ductile shear zones can induce hydraulically over-pressured fractures in deep hot-dry rock reservoirs: a new target for geothermal exploration?

    NASA Astrophysics Data System (ADS)

    Schrank, C. E.; Karrech, A.; Regenauer-Lieb, K.

    2014-12-01

    It is notoriously difficult to create and maintain permeability in deep hot-dry rock (HDR) geothermal reservoirs with engineering strategies. However, we predict that long-lived, slowly deforming HDR reservoirs likely contain hydraulically conductive, over-pressured fracture systems, provided that (a) the underlying lower crust and/or mantle are not entirely depleted of fluids and (b) the fracture system has not been drained into highly permeable overlying rocks. Such fracture systems could be targeted for the extraction of geothermal energy. Our prediction hinges on the notion that polycrystalline creep through matter transfer by a liquid phase (dissolution-precipitation creep) is a widespread mechanism for extracting fluids from the lower crust and mantle. Such processes - where creep cavities form during the slow, high-temperature deformation of crystalline solids, e.g., ceramics, metals, and rocks - entail the formation of (intergranular) fluid-assisted creep fractures. They constitute micron-scale voids formed along grain boundaries due to incompatibilities arising from diffusion or dislocation creep. Field and laboratory evidence suggest that the process leading to creep fractures may generate a dynamic permeability in the ductile crust, thus extracting fluids from this domain. We employed an elasto-visco-plastic material model that simulates creep fractures with continuum damage mechanics to model the slow contraction of high-heat-producing granites overlain by sedimentary rocks in 2D. The models suggest that deformation always leads to the initiation of a horizontal creep-damage front in the lower crust. This front propagates upwards towards the brittle-ductile transition (BDT) during protracted deformation where it collapses into highly damaged brittle-ductile shear zones. If the BDT is sufficiently shallow or finite strain sufficiently large, these shear zones trigger brittle faults emerging from their tips, which connect to the sub-horizontal damage

  15. The effect of dry needling on pain, pressure pain threshold and disability in patients with a myofascial trigger point in the upper trapezius muscle.

    PubMed

    Ziaeifar, Maryam; Arab, Amir Massoud; Karimi, Noureddin; Nourbakhsh, Mohammad Reza

    2014-04-01

    Dry needling (DN) has been used recently by physical therapists as a therapy of choice for patients with myofascial trigger points (TrP). The purpose of this randomized controlled trial was to investigate the effect of DN in the treatment of TrPs in the upper trapezius (UT) muscle. A sample of convenience of 33 patients with TrP in the UT muscle participated in this study. Patients were randomly assigned to a standard (N = 17) or experimental group (N = 16). The treatment protocol for the standard group consisted of trigger point compression technique (TCT) on MTP, while the patients in the experimental group received DN. Pain intensity and pressure pain thresholds were assessed for both groups before and after the treatment sessions. In addition, the Disability of Arm, Hand, and Shoulder (DASH) was administered. Statistical analysis (paired t-test) revealed a significant improvement in pain, PPT and DASH scores after treatment in the experimental (DN) and standard (TCT) group compared with before treatment (P < 0.05). The ANCOVA revealed significant differences between the DN and TCT groups on the post-measurement VAS score (P = 0.01). There was, however, no significant difference between the two groups on the post-measurement score of the PPT (P = 0.08) and DASH (P = 0.34). DN produces an improvement in pain intensity, PPT and DASH and may be prescribed for subjects with TrP in UT muscles especially when pain relief is the goal of the treatment. PMID:24725800

  16. Ambient insect pressure and recipient genotypes determine fecundity of transgenic crop-weed rice hybrid progeny: Implications for environmental biosafety assessment.

    PubMed

    Xia, Hui; Zhang, Hongbin; Wang, Wei; Yang, Xiao; Wang, Feng; Su, Jun; Xia, Hanbing; Xu, Kai; Cai, Xingxing; Lu, Bao-Rong

    2016-08-01

    Transgene introgression into crop weedy/wild relatives can provide natural selective advantages, probably causing undesirable environmental impact. The advantages are likely associated with factors such as transgenes, selective pressure, and genetic background of transgene recipients. To explore the role of the environment and background of transgene recipients in affecting the advantages, we estimated the fitness of crop-weed hybrid lineages derived from crosses between marker-free insect-resistant transgenic (Bt/CpTI) rice with five weedy rice populations under varied insect pressure. Multiway anova indicated the significant effect of both transgenes and weedy rice genotypes on the performance of crop-weed hybrid lineages in the high-insect environment. Increased fecundity was detected in most transgene-present F1 and F2 hybrid lineages under high-insect pressure, but varied among crop-weed hybrid lineages with different weedy rice parents. Increased fecundity of transgenic crop-weed hybrid lineages was associated with the environmental insect pressure and genotypes of their weedy rice parents. The findings suggest that the fitness effects of an insect-resistant transgene introgressed into weedy populations are not uniform across different environments and genotypes of the recipient plants that have acquired the transgene. Therefore, these factors should be considered when assessing the environmental impact of transgene flow to weedy or wild rice relatives. PMID:27468303

  17. Ultrasonic Drying Processing Chamber

    NASA Astrophysics Data System (ADS)

    Acosta, V.; Bon, J.; Riera, E.; Pinto, A.

    The design of a high intensity ultrasonic chamber for drying process was investigated. The acoustic pressure distribution in the ultrasonic drying chamber was simulated solving linear elastic models with attenuation for the acoustic-structure interaction. Together with the government equations, the selection of appropriate boundary conditions, mesh refinement, and configuration parameters of the calculation methods, which is of great importance to simulate adequately the process, were considered. Numerical solution, applying the finite element method (FEM), of acoustic-structure interactions involves to couple structural and fluid elements (with different degrees of freedom), whose solution implies several problems of hardware requirements and software configuration, which were solved. To design the drying chamber, the influence of the directivity of the drying open camera and the staggered reflectors over the acoustic pressure distribution was analyzed. Furthermore, to optimize the influence of the acoustic energy on the drying process, the average value of the acoustic energy distribution in the drying chamber was studied. This would determine the adequate position of the food samples to be dried. For this purpose, the acoustic power absorbed by the samples will be analyzed in later studies.

  18. Effects of living at two ambient temperatures on 24-h blood pressure and neuroendocrine function among obese and non-obese humans: a pilot study

    NASA Astrophysics Data System (ADS)

    Kanikowska, Dominika; Sato, Maki; Iwase, Satoshi; Shimizu, Yuuki; Nishimura, Naoki; Inukai, Yoko; Sugenoya, Junichi

    2013-05-01

    The effects of environmental temperature on blood pressure and hormones in obese subjects in Japan were compared in two seasons: summer vs winter. Five obese (BMI, 32 ± 5 kg/m2) and five non-obese (BMI, 23 ±3 kg/m2) men participated in this experiment at latitude 35°10' N and longitude 136°57.9' E. The average environmental temperature was 29 ± 1 °C in summer and 3 ± 1 °C in winter. Blood samples were analyzed for leptin, ghrelin, catecholamines, thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), total cholesterol, triglycerides, insulin and glucose. Blood pressure was measured over the course of 24 h in summer and winter. A Japanese version of the Profile of Mood States (POMS) questionnaire was also administered each season. Systolic and diastolic blood pressures in obese men were significantly higher in winter (lower environmental temperatures) than in summer (higher environmental temperatures). Noradrenaline and dopamine concentrations were also significantly higher at lower environmental temperatures in obese subjects, but ghrelin, TSH, fT3, fT4, insulin and glucose were not significantly different in summer and winter between obese and non-obese subjects. Leptin, total cholesterol and triglyceride concentrations were significantly higher in winter in obese than non-obese men. Results from the POMS questionnaire showed a significant rise in Confusion at lower environmental temperatures (winter) in obese subjects. In this pilot study, increased blood pressure may have been due to increased secretion of noradrenaline in obese men in winter, and the results suggest that blood pressure control in obese men is particularly important in winter.

  19. Dry Mouth

    MedlinePlus

    Dry mouth is the feeling that there is not enough saliva in your mouth. Everyone has a dry mouth once in a while - if they are nervous, ... or under stress. But if you have a dry mouth all or most of the time, it can ...

  20. Dry Mouth

    MedlinePlus

    Dry mouth is the feeling that there is not enough saliva in your mouth. Everyone has a dry mouth once in a while - if they are nervous, ... under stress. But if you have a dry mouth all or most of the time, it can ...

  1. Nd2K2IrO7 and Sm2K2IrO7: Iridium(VI) Oxides Prepared under Ambient Pressure

    SciTech Connect

    Mugavero, III, S.; Smith, M; Yoon, W; zur Loye, H

    2009-01-01

    The most-oxidized iridium oxides known to date are prepared in a hydroxide flux under normal pressure. They contain iridium centers exclusively in the +VI oxidation state and are characterized crystallographically. The picture shows the structure of the Ln2K2IrO7 (Ln=Nd, Sm) and its structural components: IrO6 octahedra (black), KO10 polyhedra (beige), LnO10 polyhedra (blue).

  2. Antimicrobial Applications of Ambient--Air Plasmas

    NASA Astrophysics Data System (ADS)

    Pavlovich, Matthew John

    from ozone mode to nitrogen oxides mode occurs as the discharge power increases. One prominent example of plasma biotechnology is the use of plasma-derived reactive species as a novel disinfectant. Ambient-air plasma is an attractive means of disinfection because it is non-thermal, expends a small amount of power, and requires only air and electricity to operate. Both solid surfaces and liquid volumes can be effectively and efficiently decontaminated by the reactive oxygen and nitrogen species that plasma generates. Dry surfaces are decontaminated most effectively by the plasma operating in NOx mode and less effectively in ozone mode, with the weakest antibacterial effects in the transition region, and neutral reactive species are more influential in surface disinfection than charged particles. Aqueous bacterial inactivation correlates well with ozone concentration, suggesting that ozone is the dominant species for bacterial inactivation under the condition of a low-power discharge. Alternatively, air plasma operating in the higher-power, nitrogen oxides-rich mode can create a persistently antibacterial solution. Finally, when near-UV (UVA) treatment follows plasma treatment of bacterial suspension, the antimicrobial effect exceeds the effect predicted from the two treatments alone, and addition of nitrite to aqueous solution, followed by photolysis of nitrite by UVA photons, is hypothesized as the primary mechanism of synergy. The results presented in this dissertation underscore the dynamic nature of air plasma chemistry and the importance of careful chemical characterization of plasma devices intended for biological applications. The complexity of atmospheric pressure plasma devices, and their sensitivity to subtle differences in design and operation, can lead to different results with different mechanisms.

  3. Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities.

    PubMed

    Horikoshi, Satoshi; Shirasaka, Yutaro; Uchida, Hiroshi; Horikoshi, Natsuko; Serpone, Nick

    2016-08-01

    To date syntheses of nitrogen-doped TiO2 photocatalysts (TiO2-xNx) have been carried out under high temperatures and high pressures with either NH3 or urea as the nitrogen sources. This article reports for the first time the facile preparation of N-doped TiO2 (P25 titania) in aqueous media at ambient temperature and pressure under inert conditions (Ar- and N2-purged dispersions) with 4-nitrophenol (or 4-nitrobenzaldehyde) as the nitrogen source. The resulting N-doped P25 TiO2 materials were characterized by UV/Vis and X-ray photoelectron spectroscopies (XPS) that confirmed the presence of nitrogen within the photocatalyst; X-ray diffraction (XRD) techniques confirmed the crystalline phases of the doped material. The photocatalytic activity of N-doped TiO2 was assessed through examining the photodegradation of 4-chlorophenol in aqueous media and iso-propanol as a volatile pollutant under UV/Vis and visible-light irradiation. Under visible light irradiation, undoped P25 was inactive contrary to N-doped P25 that successfully degraded 95% of the 4-chlorophenol (after 10 h) and 23% of iso-propanol (after 2.5 h). PMID:27444263

  4. Dry piston coal feeder

    DOEpatents

    Hathaway, Thomas J.; Bell, Jr., Harold S.

    1979-01-01

    This invention provides a solids feeder for feeding dry coal to a pressurized gasifier at elevated temperatures substantially without losing gas from the gasifier by providing a lock having a double-acting piston that feeds the coals into the gasifier, traps the gas from escaping, and expels the trapped gas back into the gasifier.

  5. Dry socket

    MedlinePlus

    ... care for the dry socket at home: Take pain medicine and antibiotics as directed Apply a cold pack to the outside of your jaw Carefully rinse the dry socket as directed by your dentist If taking antibiotics, avoid smoking or using tobacco and alcohol

  6. Decoupling the Influence of Leaf and Root Hydraulic Conductances on Stomatal Conductance and its Sensitivity to Vapor Pressure Deficit as Soil Dries in a Drained Loblolly Pine Plantation

    NASA Astrophysics Data System (ADS)

    Domec, J.; Noormets, A.; King, J. S.; McNulty, S. G.; Sun, G.; Gavazzi, M. J.; Boggs, J. L.

    2008-12-01

    The conversion of wetlands to intensively managed forest lands in eastern North Carolina is widespread and the consequences on plant hydraulic properties and water balances are not well studied. Precipitation and soil moisture in North America will be modified in the future and forest trees in the US will be challenged by warmer temperature, higher leaf-to-air water vapor pressure deficit (D), and more frequent summer droughts. Many studies have examined the relationships between whole tree hydraulic conductance (Ktree) and stomatal conductance (gs), but Ktree remains an ill-defined quantity because it depends on a series of resistances, mainly controlled by the conductance in roots (Kroot) and leaves (Kleaf). To explain the variation in Ktree, we characterized Kroot and Kleaf and how they responded to environmental drivers such as soil moisture availability and D. In addition, the role of dynamic variations in Kroot and Kleaf in mediating stomatal control of transpiration and its response to D was studied. The 2007 summer drought was used as a means to challenge the hydraulic system, allowing testing how broadly predictions about its behaviour hold outside the range of typical conditions. Roots and leaves were the weakest points in the whole tree hydraulic system, and contributed for more than 75% of the total tree hydraulic resistance. Effects of drought on Ktree altered the partitioning of the resistance between roots and leaves and as soil moisture declined below 50% relative extractable water (REW), Kroot declined faster than Kleaf and became the dominant hydraulic fuse regulating Ktree. Although Ktree depended on soil moisture, its dynamics was tempered by current-year needle elongation that increased significantly Kleaf during the dry months when REW was below 50%. To maintain the integrity of the xylem hydraulic continuum from roots to leaves, stomata were highly responsive in coordinating transpiration with dynamic variation in Ktree. Daily maximum gs and

  7. Simultaneous detection of polar and nonpolar compounds by ambient mass spectrometry with a dual electrospray and atmospheric pressure chemical ionization source.

    PubMed

    Cheng, Sy-Chyi; Jhang, Siou-Sian; Huang, Min-Zong; Shiea, Jentaie

    2015-02-01

    A dual ionization source combining electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) was developed to simultaneously ionize both polar and nonpolar compounds. The source was constructed by inserting a fused silica capillary into a stainless steel column enclosed in a glass tube. A high dc voltage was applied to a methanol solution flowing in the fused silica capillary to generate an ESI plume at the capillary tip. A high ac voltage was applied to a ring electrode attached to the glass tube to generate plasma from the nitrogen gas flowing between the glass tube and the stainless steel column. The concentric arrangement of the ESI plume and the APCI plasma in the source ensured that analytes entering the ionization region interacted with both ESI and APCI primary ion species generated in the source. Because the high voltages required for ESI and APCI were independently applied and controlled, the dual ion source could be operated in ESI-only, APCI-only, or ESI+APCI modes. Analytes were introduced into the ESI and/or APCI plumes by irradiating sample surfaces with a continuous-wavelength laser or a pulsed laser beam. Analyte ions could also be produced by directing the dual ESI+APCI source toward sample surfaces for desorption and ionization. The ionization mechanisms involved in the dual ion source include Penning ionization, ion molecule reactions, and fused-droplet electrospray ionization. Standards of polycyclic aromatic hydrocarbons, angiotensin I, lidocaine, ferrocene, diesel, and rosemary oils were used for testing. Protonated analyte ions were detected in ESI-only mode, radical cations were detected in APCI-only mode, and both types of ions were detected in ESI+APCI mode. PMID:25562530

  8. Influence of drying methods and agronomic variables on the chemical composition of mate tea leaves (Ilex paraguariensis A. St.-Hil) obtained from high-pressure CO2 extraction.

    PubMed

    Jacques, Rosângela Assis; Krause, Laiza Canielas; Freitas, Lisiane dos Santos; Dariva, Cláudio; Oliveira, J Vladimir; Caramão, Elina Bastos

    2007-12-12

    The main objective of this work is to assess the influence of two drying methods (microwave and vacuum oven) and some agronomic variables (plant fertilization conditions and sunlight intensity) on the characteristics of mate tea (Ilex paraguariensis) leaves extracts obtained from high-pressure carbon dioxide extractions performed in the temperature range from 20 to 40 degrees C and from 100 to 250 bar. Samples of mate were collected in an experiment conducted under agronomic control at Ervateira Barão LTDA, Brazil. Chemical distribution of the extracts was evaluated by gas chromatography coupled with a mass spectrometer detector (GC/MS). In addition to extraction variables, results showed that both sample drying methods and agronomic conditions exert a pronounced influence on the extraction yield and on the chemical distribution of the extracts. PMID:17985842

  9. Cooling of dried coal

    SciTech Connect

    Siddoway, M.A.

    1988-06-14

    This patent describes a process for noncombustibly drying particulate coal comprising: separating the coal into two wet coal streams; passing one wet coal system into a dryer to form a bed; heating air in a furnace; admitting the heated air to the dryer to fluidize the bed; withdrawing dryer exhaust gas; passing the exhaust gas through a cyclone and withdrawing coal fines from the cyclone; withdrawing a hot, dry coal stream from the dryer; blending the drier hot dry coal stream with the cyclone coal fines; withdrawing cyclone exhaust gas; wet scrubbing the cyclone exhaust gas to form a coal fines slurry and scrubber exhaust gas; passing the coal fines slurry to a sedimentation pool; blending the second wet coal stream with the drier hot dry coal stream and the cyclone coal fines; passing the latter blended stream to a cooler to form a bed; fluidizing the latter bed with ambient air; withdrawing cooler exhaust gas and passing the gas to a cyclone; passing exhaust gas from the latter cyclone to a baghouse and collecting coal fines therein; passing the latter coal fines to the furnace as fuel for heating the air; and withdrawing cooled coal from the cooler and blending the cooled coal with coal fines from the latter cyclone.

  10. Parallel ultra high pressure liquid chromatography-mass spectrometry for the quantification of HIV protease inhibitors using dried spot sample collection format.

    PubMed

    Watanabe, Kyoko; Varesio, Emmanuel; Hopfgartner, Gérard

    2014-08-15

    An assay was developed and validated for the quantification of eight protease inhibitors (indinavir (IDV), ritonavir (RTV), lopinavir (LPV), saquinavir (SQV), amprenavir (APV), nelfinavir (NFV), atazanavir (AZV) and darunavir (DRV)) in dried plasma spots using parallel ultra-high performance liquid chromatography and mass spectrometry detection in the multiple reaction monitoring mode. For each analyte an isotopically labeled internal standard was used and the assay based on liquid-solid extraction the area response ratio (analyte/IS) was found to be linear; from 0.025 μg/ml to 20 μg/ml for IDV, SQV, DRV, AZV, LPV, from 0.025 μg/ml to 10 μg/ml for NFV, APV and from 0.025 μg/ml to 5 μg/ml for RTV using 15 μl of plasma spotted on filter paper placed in a sample tube. The total analysis time was of 4 min and inter-assay accuracies and precisions were in the range of 87.7-109% and 2.5-11.8%, respectively. On dried plasma spots all analytes were found to be stable for at least 7 days. Practicability of the assay to blood was also demonstrated. The sample drying process could be reduced to 5 min using a commercial microwave system without any analyte degradation. Together with quantification, confirmatory analysis was performed on representative clinical samples. PMID:25049214

  11. High temperature and vapor pressure deficit aggravate architectural effects but ameliorate non-architectural effects of salinity on dry mass production of tomato

    PubMed Central

    Chen, Tsu-Wei; Nguyen, Thi M. N.; Kahlen, Katrin; Stützel, Hartmut

    2015-01-01

    Tomato (Solanum lycopersicum L.) is an important vegetable crop and often cultivated in regions exposed to salinity and high temperatures (HT) which change plant architecture, decrease canopy light interception and disturb physiological functions. However, the long-term effects of salinity and HT combination (S+HT) on plant growth are still unclear. A dynamic functional-structural plant model (FSPM) of tomato was parameterized and evaluated for different levels of S+HT combinations. The evaluated model was used to quantify the contributions of morphological changes (architectural effects) and physiological disturbances (non-architectural effects) on the reduction of shoot dry mass under S+HT. The model predicted architectural variables with high accuracy (>85%), which ensured the reliability of the model analyses. HT enhanced architectural effects but reduced non-architectural effects of salinity on dry mass production. The stronger architectural effects of salinity under HT could not be counterbalanced by the smaller non-architectural effects. Therefore, long-term influences of HT on shoot dry mass under salinity were negative at the whole plant level. Our model analysis highlights the importance of plant architecture at canopy level in studying the plant responses to the environments and shows the merits of dynamic FSPMs as heuristic tools. PMID:26539203

  12. Evidence of feasible hardness test on Mars using ratio of ionic/neutral emission intensities measured with laser-induced breakdown spectroscopy in low pressure CO2 ambient gas

    NASA Astrophysics Data System (ADS)

    Abdulmadjid, Syahrun Nur; Pardede, Marincan; Suyanto, Hery; Ramli, Muliadi; Lahna, Kurnia; Marpaung, Alion Mangasi; Hedwig, Rinda; Lie, Zener Sukra; Kurniawan, Davy Putra; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Idris, Nasrullah; Tjia, May On; Kagawa, Kiichiro

    2016-04-01

    An experimental study is conducted on the possibility and viability of performing hardness measurement of the various stone and chert samples in low pressure (600 Pa) CO2 ambient gas, a condition that is encountered in the Mars atmosphere. For this study, a nanosecond Nd-YAG laser is employed to generate plasma emission from the samples with different degrees of hardness. This technique is developed in light of the role of the shock wave in the generation of a laser-induced plasma. It was previously shown that the speed of the shock front depends on the hardness of the sample, and a positive relationship was found between the speed of the shock front and the ionization rate of the ablated atoms. Hence, the ratio of the intensity between the Mg II 279.5 nm and Mg I 285.2 nm emission lines detected from the laser-induced plasma can be used to estimate the hardness of a material. In fact, it is shown that the ratio changes linearly with respect to changes of sample hardness. The result has thus demonstrated the feasibility and viability of using LIBS for non contact hardness measurement on Mars.

  13. Improvement in Storage Stability of Infrared Dried Rough Rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to develop infrared drying (IRD) method to improve the stability of physicochemical properties of rough rice during storage. The effect of IRD on the physicochemical properties of stored rough rice was compared with that of hot air drying (HAD) and ambient air drying ...

  14. Improvement in storage stability of infrared dried rough rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to develop infrared drying (IRD) method to improve the stability of physicochemical properties of rough rice during storage. The effect of IRD on the physicochemical properties of stored rough rice was compared with that of hot air drying (HAD) and ambient air drying ...

  15. Real-time monitoring of peanut drying parameters in semitrailers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of peanut drying parameters such as temperature and relative humidity of the ambient air, temperature and relative humidity of the air being blown into the peanuts and kernel moisture content is essential in managing the dryer for optimal drying rate. The optimal drying rate is required to...

  16. Space Technology for Crop Drying

    NASA Technical Reports Server (NTRS)

    1980-01-01

    McDonnell Douglas came up with a new method of drying agricultural crops derived from vacuum chamber technology called MIVAC, a compression of microwave vacuum drying system. A distant cousin of the home microwave oven, MIVAC dries by means of electrically- generated microwaves introduced to a crop-containing vacuum chamber. Microwaves remove moisture quickly and the very low pressure atmosphere in the chamber permits effective drying at much lower than customary temperatures. Thus energy demand is doubly reduced by lower heat requirement and by the shorter time electric power is needed.

  17. Investigation of drop impact on dry and wet surfaces with consideration of surrounding air

    NASA Astrophysics Data System (ADS)

    Guo, Yisen; Lian, Yongsheng; Sussman, Mark

    2016-07-01

    Numerical simulations were conducted to investigate drop impingement and splashing on both dry and wet surfaces at impact velocities greater than 50 m/s with the consideration of the effect of surrounding air. The Navier-Stokes equations were solved using the variable density pressure projection method on a dynamic block structured adaptive grid. The moment of fluid method was used to reconstruct interfaces separating different phases. A dynamic contact angle model was used to define the boundary condition at the moving contact line. Simulations showed that lowering the ambient gas density can suppress dry surface splashing, which is in agreement with the experiments. A recirculation zone was observed inside the drop after contact: a larger recirculation zone was formed earlier in the higher gas density case than in the lower gas density case. Increasing gas density also enhances the creation of secondary droplets from the lamella breakup. For high speed impact on a dry surface, lowering ambient gas density attenuates splashing. However, ambient air does not significantly affect splashing on a wet surface. Simulations showed that the splashed droplets are primarily from the exiting liquid film.

  18. Dry cell battery poisoning

    MedlinePlus

    Batteries - dry cell ... Acidic dry cell batteries contain: Manganese dioxide Ammonium chloride Alkaline dry cell batteries contain: Sodium hydroxide Potassium hydroxide Lithium dioxide dry cell batteries ...

  19. Hydrodynamic model for drying emulsions

    NASA Astrophysics Data System (ADS)

    Feng, Huanhuan; Sprakel, Joris; van der Gucht, Jasper

    2015-08-01

    We present a hydrodynamic model for film formation in a dense oil-in-water emulsion under a unidirectional drying stress. Water flow through the plateau borders towards the drying end leads to the buildup of a pressure gradient. When the local pressure exceeds the critical disjoining pressure, the water films between droplets break and the droplets coalesce. We show that, depending on the critical pressure and the evaporation rate, the coalescence can occur in two distinct modes. At low critical pressures and low evaporation rates, coalescence occurs throughout the sample, whereas at high critical pressures and high evaporation rate, coalescence occurs only at the front. In the latter case, an oil layer develops on top of the film, which acts as a diffusive barrier and slows down film formation. Our findings, which are summarized in a state diagram for film formation, are in agreement with recent experimental findings.

  20. Colorful drying.

    PubMed

    Lakio, Satu; Heinämäki, Jyrki; Yliruusi, Jouko

    2010-03-01

    Drying is one of the standard unit operations in the pharmaceutical industry and it is important to become aware of the circumstances that dominate during the process. The purpose of this study was to test microcapsulated thermochromic pigments as heat indicators in a fluid bed drying process. The indicator powders were manually granulated with alpha-lactose monohydrate resulting in three particle-size groups. Also, pellets were coated with the indicator powders. The granules and pellets were fluidized in fluid bed dryer to observe the progress of the heat flow in the material and to study the heat indicator properties of the indicator materials. A tristimulus colorimeter was used to measure CIELAB color values. Color indicator for heat detection can be utilized to test if the heat-sensitive API would go through physical changes during the pharmaceutical drying process. Both the prepared granules and pellets can be used as heat indicator in fluid bed drying process. The colored heat indicators give an opportunity to learn new aspects of the process at real time and could be exploded, for example, for scaling-up studies. PMID:20039220

  1. Dry Eye

    MedlinePlus

    ... surgery, called punctal cautery, is recommended to permanently close the drainage holes. The procedure helps keep the limited volume of tears on the eye for a longer period of time. In some patients with dry eye, supplements or dietary sources (such as tuna fish) of omega-3 fatty ...

  2. Ambient pressure XPS and IRRAS investigation of ethanol steam reforming on Ni-CeO2(111) catalysts: an in situ study of C-C and O-H bond scission.

    PubMed

    Liu, Zongyuan; Duchoň, Tomáš; Wang, Huanru; Grinter, David C; Waluyo, Iradwikanari; Zhou, Jing; Liu, Qiang; Jeong, Beomgyun; Crumlin, Ethan J; Matolín, Vladimír; Stacchiola, Dario J; Rodriguez, José A; Senanayake, Sanjaya D

    2016-06-22

    Ambient-Pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Infrared Reflection Absorption Spectroscopy (AP-IRRAS) have been used to elucidate the active sites and mechanistic steps associated with the ethanol steam reforming reaction (ESR) over Ni-CeO2(111) model catalysts. Our results reveal that surface layers of the ceria substrate are both highly reduced and hydroxylated under reaction conditions while the small supported Ni nanoparticles are present as Ni(0)/NixC. A multifunctional, synergistic role is highlighted in which Ni, CeOx and the interface provide an ensemble effect in the active chemistry that leads to H2. Ni(0) is the active phase leading to both C-C and C-H bond cleavage in ethanol and it is also responsible for carbon accumulation. On the other hand, CeOx is important for the deprotonation of ethanol/water to ethoxy and OH intermediates. The active state of CeOx is a Ce(3+)(OH)x compound that results from extensive reduction by ethanol and the efficient dissociation of water. Additionally, we gain an important insight into the stability and selectivity of the catalyst by its effective water dissociation, where the accumulation of surface carbon can be mitigated by the increased presence of surface OH groups. The co-existence and cooperative interplay of Ni(0) and Ce(3+)(OH)x through a metal-support interaction facilitate oxygen transfer, activation of ethanol/water as well as the removal of coke. PMID:27095305

  3. The future is 'ambient'

    NASA Astrophysics Data System (ADS)

    Lugmayr, Artur

    2006-02-01

    The research field of ambient media starts to spread rapidly and first applications for consumer homes are on the way. Ambient media is the logical continuation of research around media. Media has been evolving from old media (e.g. print media), to integrated presentation in one form (multimedia - or new media), to generating a synthetic world (virtual reality), to the natural environment is the user-interface (ambient media), and will be evolving towards real/synthetic undistinguishable media (bio-media or bio-multimedia). After the IT bubble was bursting, multimedia was lacking a vision of potential future scenarios and applications. Within this research paper the potentials, applications, and market available solutions of mobile ambient multimedia are studied. The different features of ambient mobile multimedia are manifold and include wearable computers, adaptive software, context awareness, ubiquitous computers, middleware, and wireless networks. The paper especially focuses on algorithms and methods that can be utilized to realize modern mobile ambient systems.

  4. Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.

    PubMed

    Haque, M Amdadul; Aldred, Peter; Chen, Jie; Barrow, Colin J; Adhikari, Benu

    2013-11-15

    The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s). PMID:23790837

  5. Drying apparatus for photographic sheet material

    NASA Technical Reports Server (NTRS)

    Epstein, P.; Donovan, G.; Lawhite, E. (Inventor)

    1973-01-01

    An elongated drying chamber is provided with transport means for carrying photographic sheet material edgewise with the sheets in end-to-end relationship past a plurality of tubes that issue drying air streams. The tubes are slotted a distance equal to substantially the full width of the sheet material for complete, gentle drying by sheets of air. A common plenum supplies the tubes with heated air; the air is directed from the tube slots at a pronounced angle to the sheet surface to provide for arraying the tubes close to the surface for maximum drying effect while minimizing the danger of mechanical interference between the edges of the sheets and the slots in the tubes. The driver for the transport is housed in an enclosure between the plenum and the drying chamber; an air return duct is provided along another side to complete insulation of the drying chamber from ambient conditions.

  6. Ultrahigh-pressure liquid chromatography triple-quadrupole tandem mass spectrometry quantitation of polyphenols and secoiridoids in california-style black ripe olives and dry salt-cured olives.

    PubMed

    Melliou, Eleni; Zweigenbaum, Jerry A; Mitchell, Alyson E

    2015-03-11

    The chemical composition of finished table olive products is influenced by the olive variety and the processing method used to debitter or cure table olives. Herein, a rapid ultrahigh-pressure liquid chromatography triple-quadrupole tandem mass spectrometry method, using dynamic multiple reaction monitoring, was developed for the quantitation of 12 predominant phenolic and secoiridoid compounds in olive fruit, including hydroxytyrosol, oleuropein, hydroxytyrosol-4-O-glucoside, luteolin-7-O-glucoside, rutin, verbascoside, oleoside-11-methyl ester, 2,6-dimethoxy-p-benzoquinone, phenolic acids (chlorogenic and o-coumaric acids), oleuropein aglycone, and ligstroside aglycone. Levels of these compounds were measured in fresh and California-style black ripe processed Manzanilla olives and two dry salt-cured olive varieties (Mission from California and Throuba Thassos from Greece). Results indicate that the variety and debittering processing method have strong impact on the profile of phenolic and secoiridoid compounds in table olives. The dry salt-cured olives contained higher amounts of most compounds studied, especially oleuropein (1459.5 ± 100.1 μg/g), whereas California-style black ripe olives had a significant reduction or loss of these bioactive compounds (e.g., oleuropein level at 36.7 ± 3.1 μg/g). PMID:25668132

  7. Why do drying films crack?

    PubMed

    Lee, Wai Peng; Routh, Alexander F

    2004-11-01

    Understanding the mechanism by which films fail during drying is the first step in controlling this natural process. Previous studies have examined the spacing between cracks with predictions made by assuming a balance between elastic energy released with a surface energy consumed. We introduce a new scaling for the spacing between cracks in drying dispersions. The scaling relates to the distance that solvent can flow, to relieve capillary stresses, as a film fails. The scaling collapses data for a range of evaporation rates, film thicknesses, particle sizes, and materials. This work identifies capillary pressures, induced by packed particle fronts travelling horizontally across films, as responsible for the failure in dried films. PMID:15518466

  8. rf-generated ambient-afterglow plasma

    NASA Astrophysics Data System (ADS)

    Shakir, Shariff; Mynampati, Sandhya; Pashaie, Bijan; Dhali, Shirshak K.

    2006-04-01

    Atmospheric pressure plasmas have gained importance due to their potential application in polymer surface treatment, surface cleaning of metals, thin film deposition, and destruction of biological hazards. In this paper a radio-frequency driven atmospheric pressure afterglow plasma source in argon and helium is discussed. The light intensity measurement shows that the radio-frequency discharge is continuous in time unlike the intermittent nature of a low frequency dielectric-barrier discharge. The discharge, under ambient conditions, can be generated in argon, helium, and nitrogen. Spectroscopic measurements show that metastables are capable of producing oxygen atoms and other excited species. The argon afterglow, in particular, is capable of dissociating oxygen molecules in the ambient gas. An afterglow model has been developed to study the interaction of the plasma with the ambient gas. Results from applications of the plasma to surface treatment of metals and polymers, and bacterial decontamination are briefly discussed.

  9. AMBIENT AIR MONITORING STRATEGY

    EPA Science Inventory

    The Clean Air Act requires EPA to establish national ambient air quality standards and to regulate as necessary, hazardous air pollutants. EPA uses ambient air monitoring to determine current air quality conditions, and to assess progress toward meeting these standards and relat...

  10. Ambient Tropospheric Particles

    EPA Science Inventory

    Atmospheric particulate matter (PM) is a complex mixture of solid and liquid particles suspended in ambient air (also known as the atmospheric aerosol). Ambient PM arises from a wide-range of sources and/or processes, and consists of particles of different shapes, sizes, and com...

  11. Drying Thermoplastics

    NASA Technical Reports Server (NTRS)

    1976-01-01

    In searching for an improved method of removing water from polyester type resins without damaging the materials, Conair Inc. turned to the NASA Center at the University of Pittsburgh for assistance. Taking an organized, thorough look at existing technology before beginning research has helped many companies save significant time and money. They searched the NASA and other computerized files for microwave drying of thermoplastics. About 300 relevant citations were retrieved - eight of which were identified as directly applicable to the problem. Company estimates it saved a minimum of a full year in compiling research results assembled by the information center.

  12. Reactions of Organic Ions at Ambient Surfaces in a Solvent-Free Environment

    NASA Astrophysics Data System (ADS)

    Badu-Tawiah, Abraham K.; Cyriac, Jobin; Cooks, R. Graham

    2012-05-01

    Solvent-free ion/surface chemistry is studied at atmospheric pressure, specifically pyrylium cations, are reacted at ambient surfaces with organic amines to generate pyridinium ions. The dry reagent ions were generated by electrospraying a solution of the organic salt and passing the resulting electrosprayed droplets pneumatically through a heated metal drying tube. The dry ions were then passed through an electric field in air to separate the cations from anions and direct the cations onto a gold substrate coated with an amine. This nontraditional way of manipulating polyatomic ions has provided new chemical insights, for example, the surface reaction involving dry isolated 2,4,6-triphenylpyrylium cations and condensed solid-phase ethanolamine was found to produce the expected N-substituted pyridinium product ion via a pseudobase intermediate in a regiospecific fashion. In solution however, ethanolamine was observed to react through its N-centered and O-centered nucleophilic groups to generate two isomeric products via 2H-pyran intermediates. The O-centered nucleophile reacted less rapidly to give the minor product. The surface reaction product was characterized in situ by surface enhanced Raman spectroscopy, and ex situ using mass spectrometry and H/D exchange, and found to be chemically the same as the major pyridinium solution-phase reaction product.

  13. Dry sand foam generator

    SciTech Connect

    Edgley, K.D.; Stromberg, J.L.

    1988-10-25

    A method of generating a foam containing particulate material for treating a subsurface earth formation penetrated by a well bore, the method comprising: (a) introducing a first stream of pressurized gas having dry particulate material entrained therein into a vessel, the particulate material flowing vertically downward into the vessel, at least in part due to the action of gravity; (b) introducing a second stream of liquid into the vessel; (c) varying the second stream into a self-impinging conical jet; (d) impinging the conical jet onto the first stream and thereby forming a foam containing particulate material; and (e) injecting such a foam into the well bore.

  14. Dry Mouth or Xerostomia

    MedlinePlus

    ... or Xerostomia Request Permissions Print to PDF Dry Mouth or Xerostomia Approved by the Cancer.Net Editorial ... a dry mouth. Signs and symptoms of dry mouth The signs and symptoms of dry mouth include ...

  15. Ambient Temperature and Obesity

    PubMed Central

    Moellering, Douglas R.; Smith, Daniel L.

    2014-01-01

    Homeotherms maintain an optimal body temperature that is most often above their environment or ambient temperature. As ambient temperature decreases, energy expenditure (and energy intake) must increase to maintain thermal homeostasis. With the wide spread adoption of climate control, humans in modern society are buffered from temperature extremes and spend an increasing amount of time in a thermally comfortable state where energetic demands are minimized. This is hypothesized to contribute to the contemporary increase in obesity rates. Studies reporting exposures of animals and humans to different ambient temperatures are discussed. Additional consideration is given to the potentially altered metabolic and physiologic responses in obese versus lean subjects at a given temperature. The data suggest that ambient temperature is a significant contributor to both energy intake and energy expenditure, and that this variable should be more thoroughly explored in future studies as a potential contributor to obesity susceptibility. PMID:24707450

  16. Asthma control in patients receiving inhaled corticosteroid and long-acting beta2-agonist fixed combinations. A real-life study comparing dry powder inhalers and a pressurized metered dose inhaler extrafine formulation

    PubMed Central

    2011-01-01

    Background Although patients have more problems using metered dose inhalers, clinical comparisons suggest they provide similar control to dry powder inhalers. Using real-life situations this study was designed to evaluate asthma control in outpatients with moderate to severe persistent asthma and to compare efficacy of fixed combinations of inhaled corticosteroids (ICS) and long acting beta-agonists (LABA). Methods This real-life study had a cross-sectional design. Patients using fixed combinations of ICS and LABA had their asthma control and spirometry assessed during regular visits. Results 111 patients were analyzed: 53 (47.7%) received maintenance therapy of extrafine beclomethasone-formoterol (BDP/F) pressurized metered dose inhaler (pMDI), 25 (22.5%) fluticasone-salmeterol (FP/S) dry powder inhaler (DPI), and 33 (29.7%) budesonide-formoterol (BUD/F) DPI. Severity of asthma at time of diagnosis, assessed by the treating physician, was comparable among groups. Asthma control was achieved by 45.9% of patients; 38.7% were partially controlled and 15.3% were uncontrolled. In the extrafine BDF/F group, asthma control total score, daytime symptom score and rescue medication use score were significantly better than those using fixed DPI combinations (5.8 ± 6.2 vs. 8.5 ± 6.8; 1.4 ± 1.8 vs. 2.3 ± 2.1; 1.8 ± 2.2 vs. 2.6 ± 2.2; p = 0.0160; p = 0.012 and p = 0.025, respectively) and the mean daily ICS dose were significantly lower. Conclusions pMDI extrafine BDP/F combination demonstrated better asthma control compared to DPIs formulated with larger particles. This could be due to the improved lung deposition of the dose or less reliance on the optimal inhalation technique or both. PMID:21762500

  17. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... pressure (pressure in the IBC above ambient atmospheric pressure) measured in the IBC at 55 °C (131 °F... pressure of the hazardous material plus atmospheric pressure) is used, 1.5 multiplied by the vapor pressure... pressure (vapor pressure of the hazardous material plus atmospheric pressure) is used, 1.75......

  18. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... pressure (pressure in the IBC above ambient atmospheric pressure) measured in the IBC at 55 °C (131 °F... pressure of the hazardous material plus atmospheric pressure) is used, 1.5 multiplied by the vapor pressure... pressure (vapor pressure of the hazardous material plus atmospheric pressure) is used, 1.75......

  19. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... pressure (pressure in the IBC above ambient atmospheric pressure) measured in the IBC at 55 °C (131 °F... pressure of the hazardous material plus atmospheric pressure) is used, 1.5 multiplied by the vapor pressure... pressure (vapor pressure of the hazardous material plus atmospheric pressure) is used, 1.75......

  20. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... pressure (pressure in the IBC above ambient atmospheric pressure) measured in the IBC at 55 °C (131 °F... pressure of the hazardous material plus atmospheric pressure) is used, 1.5 multiplied by the vapor pressure... pressure (vapor pressure of the hazardous material plus atmospheric pressure) is used, 1.75......

  1. Fundamentals of freeze-drying.

    PubMed

    Nail, Steven L; Jiang, Shan; Chongprasert, Suchart; Knopp, Shawn A

    2002-01-01

    --the dominant mechanism of heat transfer in freeze-drying--is inefficient at the pressures used in freeze-drying. Steps should be taken to improve the thermal contact between the product and the shelf of the freeze dryer, such as eliminating metal trays from the drying process. Quantitation of the heat transfer coefficient for the geometry used is a useful way of assessing the impact of changes in the system such as elimination of product trays and changes in the vial. Because heat transfer by conduction through the vapor increases with increasing pressure, the commonly held point of view that "the lower the pressure, the better" is not true with respect to process efficiency. The optimum pressure for a given product is a function of the temperature at which freeze-drying is carried out, and lower pressures are needed at low product temperatures. The controlling resistance to mass transfer is almost always the resistance of the partially dried solids above the submination interface. This resistance can be minimized by avoiding fill volumes of more than about half the volume of the container. The development scientist should also recognize that very high concentrations of solute may not be appropriate for optimum freeze-drying, particularly if the resistance of the dried product layer increases sharply with concentration. Although the last 10 years has seen the publication of a significant body of literature of great value in allowing development scientists and engineers to "work smarter," there is still much work needed in both the science and the technology of freeze-drying. Scientific development is needed for improving analytical methodology for characterization of frozen systems and freeze-dried solids. A better understanding of the relationship between molecular mobility and reactivity is needed to allow accurate prediction of product stability at the intended storage temperature based on accelerated stability at higher temperatures. This requires that the temperature

  2. A statistical approach to optimize the spray drying of starch particles: application to dry powder coating.

    PubMed

    Bilancetti, Luca; Poncelet, Denis; Loisel, Catherine; Mazzitelli, Stefania; Nastruzzi, Claudio

    2010-09-01

    This article describes the preparation of starch particles, by spray drying, for possible application to a dry powder coating process. Dry powder coating consists of spraying a fine powder and a plasticizer on particles. The efficiency of the coating is linked to the powder morphological and dimensional characteristics. Different experimental parameters of the spray-drying process were analyzed, including type of solvent, starch concentration, rate of polymer feeding, pressure of the atomizing air, drying air flow, and temperature of drying air. An optimization and screening of the experimental parameters by a design of the experiment (DOE) approach have been done. Finally, the produced spray-dried starch particles were conveniently tested in a dry coating process, in comparison to the commercial initial starch. The obtained results, in terms of coating efficiency, demonstrated that the spray-dried particles led to a sharp increase of coating efficiency value. PMID:20706878

  3. 14 CFR 29.1325 - Static pressure and pressure altimeter systems.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... between air pressure in the static pressure system and true ambient atmospheric static pressure is not... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Static pressure and pressure altimeter...: Installation § 29.1325 Static pressure and pressure altimeter systems. (a) Each instrument with static air...

  4. 14 CFR 29.1325 - Static pressure and pressure altimeter systems.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... between air pressure in the static pressure system and true ambient atmospheric static pressure is not... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static pressure and pressure altimeter...: Installation § 29.1325 Static pressure and pressure altimeter systems. (a) Each instrument with static air...

  5. 14 CFR 29.1325 - Static pressure and pressure altimeter systems.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... between air pressure in the static pressure system and true ambient atmospheric static pressure is not... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Static pressure and pressure altimeter...: Installation § 29.1325 Static pressure and pressure altimeter systems. (a) Each instrument with static air...

  6. 14 CFR 29.1325 - Static pressure and pressure altimeter systems.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... between air pressure in the static pressure system and true ambient atmospheric static pressure is not... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Static pressure and pressure altimeter...: Installation § 29.1325 Static pressure and pressure altimeter systems. (a) Each instrument with static air...

  7. 14 CFR 29.1325 - Static pressure and pressure altimeter systems.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... between air pressure in the static pressure system and true ambient atmospheric static pressure is not... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Static pressure and pressure altimeter...: Installation § 29.1325 Static pressure and pressure altimeter systems. (a) Each instrument with static air...

  8. Dry sump crankcase

    SciTech Connect

    Berger, A.H.; Dichi, R.E.

    1987-06-23

    A dry sump type crankcase is described for an automotive type internal combustion engine having an intake manifold and a positive crankcase ventilation (PCV) system for automatically and continuously ventilating the crankcase. The system includes an essentially atmospheric pressure fresh air inlet to the engine passing air through to the crankcase and a connection from the oil pan to the vacuum in the intake manifold establishing a constant flow of crankcase vapors. The oil pan has a baffle partitioning it into an inner oil collecting funnel-like crankcase cavity and an outer oil reservoir. The inner cavity has an opening at its lower-most point for communication of oil with the reservoir. The opening is of a controlled vertical height for creating a pressure differential across the baffle during operation of the engine. Means connects the inner cavity to the air inlet pressure side of the PCV System while connecting the reservoir to the vacuum side of the PCV system for establishing a constant pressure differential across the baffle sufficient to displace the oil against gravity and maintain the oil level in the crankcase during operation of the engine at the height of the opening in the baffle. Gravity causes the oil to seek a level higher than the opening upon shutdown of the engine and the consequential decay of vacuum in the intake manifold.

  9. High silicon self-diffusion coefficient in dry forsterite

    NASA Astrophysics Data System (ADS)

    Katsura, T.; Fei, H.; Hegoda, C.; Yamazaki, D.; Wiedenbeck, M.; Yurimoto, H.; Shcheka, S.

    2012-12-01

    Plastic deformation of mantle minerals is believed to be controlled by self-diffusion of the slowest species, which is silicon in silicate minerals. Olivine is the main constituent of upper mantle. Therefore, silicon self-diffusion coefficient (DSi) in olivine provides the basic information of upper mantle rheology. Dohmen et al. [1] and Jaoul et al. [2] measured the DSi at ambient pressure under dry conditions in natural olivine and iron-free forsterite, respectively. However, their results were ~2-3 orders of magnitude lower than that estimated from deformation experiments [3]. In this study, we revisited DSi in forsterite and resolved this discrepancy [4]. Forsterite single crystals were polished in colloidal silica solution, deposited with 300-500 nm of 29Si enriched Mg2SiO4 films, covered by 100 nm of ZrO2 films, and annealed at 1600-1800 K from ambient pressure up to 13 GPa using an ambient pressure furnace and multi-anvil apparatus. The surface roughness after diffusion were reduced to <50 nm by polishing again in colloidal silica solution. Diffusion profiles were obtained by SIMS. Water contents in the samples were <1 μg/g by FT-IR [4]. logDSi were determined to be -19.7±0.4 and -18.1±0.3 log[m2/s] under ambient pressure at 1600 and 1800 K, respectively. These values were 2.4 orders of magnitude higher than that determined by Jaoul et al. [2] in forsterite, as well as that reprted by Dohmen et al. [1] in natural olivine. Their low DSi could be obtained due to the bad contact of the coated films with the substrate. Our results well explain the high dislocation climb rates in deformation experiments [4]. We also determined a small negative pressure dependence of DSi with an activation volume of 1.7±0.4 cm3/mol, and an activation energy of ~410 kJ/mol. Calibratied to the same temperature, the nearly linear relationship of DSi against pressure in dry forsterite in this study, iron and water bearing wadsleyite and ringwoodite by Shimojuku et al. [5

  10. Pressure passivation of mild pyrolysis char

    SciTech Connect

    Ochs, T.; Summers, C.; Schroeder, K.; Sands, W.

    1999-07-01

    Low-rank coals that have been thermally dried in the mild pyrolysis process have a tendency to spontaneously combust. The spontaneous combustion of coals and chars has been linked to their affinity for oxygen. The USDOE has developed a method for the passivation of mild pyrolysis char derived from a low-rank coal using pressure differentials to control the oxidation of the active sites in the char rapidly and safely. Initial experiments performed by the USDOE show that the affinity of the coal for oxygen uptake (residual oxygen demand, ROD) is reduced by exposure of the coal-char to high-pressure gas mixtures including air or oxygen-enriched air. Laboratory-scale tests have shown that the ROD can be rapidly reduced by cycling the active coals between low-pressure (atmospheric pressure or less) and high-pressure (500 psi to 1,500 psi) regimes. Cycling the pressure of the treatment gas provides rapid passivation resulting from two effects: The high-pressure cycle forces fresh oxygen into the pores which have been purged of adsorbed gases and reaction products. The pores of coal are small enough to prohibit free convection and force oxygen exchange to take place by way of diffusion under ambient conditions. The forced introduction of fresh process gas under high pressure overcomes the restrictions due to diffusion limits while the removal of adsorbed products clears the way to active surface sites. The high pressure increases the number of oxygen molecules with sufficient energy to overcome the activation barrier of the passivation reaction, due to the increased number of molecules per unit volume of the high-pressure gas. Combined, the two effects rapidly produce a coal with a significantly reduced ROD.

  11. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  12. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives

    PubMed Central

    2015-01-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm2 provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  13. Ambient ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lebedev, A. T.

    2015-07-01

    Ambient ionization mass spectrometry emerged as a new scientific discipline only about ten years ago. A considerable body of information has been reported since that time. Keeping the sensitivity, performance and informativity of classical mass spectrometry methods, the new approach made it possible to eliminate laborious sample preparation procedures and triggered the development of miniaturized instruments to work directly in the field. The review concerns the theoretical foundations and design of ambient ionization methods. Their advantages and drawbacks, as well as prospects for application in chemistry, biology, medicine, environmetal analysis, etc., are discussed. The bibliography includes 194 references.

  14. Dry MJO

    NASA Astrophysics Data System (ADS)

    Zhang, Chidong; Zermeno, David

    2015-04-01

    The Madden-Julian Oscillation (MJO) has always been perceived as a phenomenon resulted from coupling between atmospheric convection and circulations. In this presentation, a different perspective of the MJO is introduced. Diagnoses of tropical sounding observations and global reanalysis products have revealed intraseasonal, slow eastward moving signals in temperature, geopotential height or pressure, and wind that exist over the equatorial Indian and eastern Pacific Oceans without any accompanying precipitation or deep convection. Even at locations where MJO convection is vigorous, associated MJO perturbations in these fields cannot be explained by diabatic heating along. These observations lead to a hypothesis that the intrinsic nature of the MJO eastward propagation is dynamically determined and independent of deep convection. Deep convection acts as an effective source of energy for the dynamical signals of the MJO. Other processes, such as lateral and upstream forcing, stochastic convection, may also act to supply energy to the MJO. Other implications of this hypothesis and possible ways to falsify this hypothesis are discussed.

  15. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following methods: (A) The gauge pressure (pressure in the IBC above ambient atmospheric pressure) measured...); (B) If absolute pressure (vapor pressure of the hazardous material plus atmospheric pressure) is used... atmospheric pressure) is used, 1.75 multiplied by the vapor pressure of the hazardous material at 50......

  16. AMBIENT CARBON MONOXIDE MONITOR

    EPA Science Inventory

    A portable instrument has been designed and two units have been built to monitor the concentration of CO in ambient air. The air flows through a sampling section that is approximately 43 cm long with a 28-pass optical system that produces a total path of 12 meters. Gas-filter cor...

  17. Bisulfate - cluster based atmospheric pressure chemical ionization mass spectrometer for high-sensitivity (< 100 ppqV) detection of atmospheric dimethyl amine: proof-of-concept and first ambient data from boreal forest

    NASA Astrophysics Data System (ADS)

    Sipilä, M.; Sarnela, N.; Jokinen, T.; Junninen, H.; Hakala, J.; Rissanen, M. P.; Praplan, A.; Simon, M.; Kürten, A.; Bianchi, F.; Dommen, J.; Curtius, J.; Petäjä, T.; Worsnop, D. R.

    2015-10-01

    Atmospheric amines may play a crucial role in formation of new aerosol particles via nucleation with sulfuric acid. Recent studies have revealed that concentrations below 1 pptV can significantly promote nucleation of sulfuric acid particles. While sulfuric acid detection is relatively straightforward, no amine measurements to date have been able to reach the critical sub-pptV concentration range and atmospheric amine concentrations are in general poorly characterized. In this work we present a proof-of-concept of an instrument capable of detecting dimethyl amine (DMA) with concentrations even down to 70 ppqV (parts per quadrillion, 0.07 pptV) for a 15 min integration time. Detection of ammonia and amines other than dimethyl amine is discussed. We also report results from the first ambient measurements performed in spring 2013 at a boreal forest site. While minute signals above the signal-to-noise ratio that could be attributed to trimethyl or propyl amine were observed, DMA concentration never exceeded the detection threshold of ambient measurements (150 ppqV), thereby questioning, though not excluding, the role of DMA in nucleation at this location.

  18. Development of a compact freeze vacuum drying for jelly fish (Schypomedusae)

    NASA Astrophysics Data System (ADS)

    Alhamid, M. Idrus; Yulianto, M.; Nasruddin

    2012-06-01

    A new design of a freeze vacuum drying with internal cooling and heater from condenser's heat loss was built and tested. The dryer was used to dry jelly fish (schypomedusae), to study the effect of drying parameters such as the temperature within the drying chamber on mass losses (evaporation) during the freezing stage and the moisture ratio at the end of the drying process. The midili thin layer mathematical drying model was used to estimate and predict the moisture ratio curve based on different drying chamber temperatures. This experiment shows that decreasing the drying chamber temperature with constant pressure results in less mass loss during the freezing stage Drying time was reduced with an increase in drying temperature. Decreasing the drying chamber temperature results in lower pressure saturation of the material has no effect of drying chamber pressure on mass transfer.

  19. System Would Regulate Low Gas Pressure

    NASA Technical Reports Server (NTRS)

    Frazer, Robert E.

    1994-01-01

    System intended to maintain gases in containers at pressures near atmospheric. Includes ballast volume in form of underinflated balloon that communicates with working volume. Balloon housed in rigid chamber not subjected to extremes of temperature of working volume. Pressure in chamber surrounding balloon regulated at ambient atmospheric pressure or at constant small differential pressure above or below ambient. Expansion and contraction of balloon accommodates expansion or contraction of gas during operational heating or cooling in working volume, maintaining pressure in working volume at ambient or constant differential above or below ambient. Gas lost from system due to leakage or diffusion, low-pressure sensor responds, signaling valve actuators to supply more gas to working volume. If pressure rises too high, overpressure relief valve opens before excessive pressure damages system.

  20. Dry gas operation of proton exchange membrane fuel cells with parallel channels: Non-porous versus porous plates

    NASA Astrophysics Data System (ADS)

    Litster, Shawn; Santiago, Juan G.

    We present a study of proton exchange membrane (PEM) fuel cells with parallel channel flow fields for the cathode, dry inlet gases, and ambient pressure at the outlets. The study compares the performance of two designs: a standard, non-porous graphite cathode plate design and a porous hydrophilic carbon plate version. The experimental study of the non-porous plate is a control case and highlights the significant challenges of operation with dry gases and non-porous, parallel channel cathodes. These challenges include significant transients in power density and severe performance loss due to flooding and electrolyte dry-out. Our experimental study shows that the porous plate yields significant improvements in performance and robustness of operation. We hypothesize that the porous plate distributes water throughout the cell area by capillary action; including pumping water upstream to normally dry inlet regions. The porous plate reduces membrane resistance and air pressure drop. Further, IR-free polarization curves confirm operation free of flooding. With an air stoichiometric ratio of 1.3, we obtain a maximum power density of 0.40 W cm -2, which is 3.5 times greater than that achieved with the non-porous plate at the same operating condition.

  1. High-intensity drying processes-impulse drying. Yearly report

    SciTech Connect

    Orloff, D.I.

    1991-06-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. To eliminate sheet delamination, low thermal mass ceramic press roll coatings were developed to reduce heat transfer to the sheet, while maintaining high heat flux during early stages of the process. In so doing, most of the transferred energy is used to form steam that displaces liquid water, rather than in excessively heating the sheet. During this period, a prototype ceramic coating was developed and its impulse drying performance was compared to that of steel surfaces. It was observed that ceramic platens can be operated at higher temperatures and pressures resulting in improved water removal and physical properties without inducing sheet delamination. Heat flux measurement techniques were developed to provide a mechanistic explanation for the superior performance of the prototype. The work confirmed that the prototype ceramic coating is more energy efficient than the steel surface.

  2. High-intensity drying processes-impulse drying

    SciTech Connect

    Orloff, D.I.

    1991-06-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. To eliminate sheet delamination, low thermal mass ceramic press roll coatings were developed to reduce heat transfer to the sheet, while maintaining high heat flux during early stages of the process. In so doing, most of the transferred energy is used to form steam that displaces liquid water, rather than in excessively heating the sheet. During this period, a prototype ceramic coating was developed and its impulse drying performance was compared to that of steel surfaces. It was observed that ceramic platens can be operated at higher temperatures and pressures resulting in improved water removal and physical properties without inducing sheet delamination. Heat flux measurement techniques were developed to provide a mechanistic explanation for the superior performance of the prototype. The work confirmed that the prototype ceramic coating is more energy efficient than the steel surface.

  3. High-intensity drying processes: Impulse drying

    SciTech Connect

    Orloff, D.I.

    1989-05-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during manufacture of paper and similar web products. Impulse drying occurs when a wet paper web passes through a press nip where one of the rolls is heated to a very high temperature. Steam generated by contact with the hot roll expands and displaces water from the sheet in a very efficient manner. The energy required for water removal is much lower than that required for conventional evaporative drying. Tests have been completed that elucidate the unique displacement mechanism of water removal in the impulse drying process. A pilot roll press has been designed, installed and used to examine impulse drying under conditions that simulate commercial press conditions. The results of this earlier work have been reported in three previous reports. During this report period October, 1987 to September, 1988, the pilot press was equipped with a second impulse drying roll to facilitate studies of surface uniformity in impulse dried paper. Studies have also been completed which examine the origins of sheet delamination that has been been encountered during impulse drying of certain heavyweight paper grades, and which investigate approaches to prevent delamination in these grades. Finally, an experimental plan has been formalized to examine impulse drying of lightweight grades which are candidates for early commercialization. 7 refs., 30 figs., 3 tabs.

  4. CO2 (dry ice) cleaning system

    NASA Technical Reports Server (NTRS)

    Barnett, Donald M.

    1995-01-01

    Tomco Equipment Company has participated in the dry ice (solid carbon dioxide, CO2) cleaning industry for over ten years as a pioneer in the manufacturer of high density, dry ice cleaning pellet production equipment. For over four years Tomco high density pelletizers have been available to the dry ice cleaning industry. Approximately one year ago Tomco introduced the DI-250, a new dry ice blast unit making Tomco a single source supplier for sublimable media, particle blast, cleaning systems. This new blast unit is an all pneumatic, single discharge hose device. It meters the insertion of 1/8 inch diameter (or smaller), high density, dry ice pellets into a high pressure, propellant gas stream. The dry ice and propellant streams are controlled and mixed from the blast cabinet. From there the mixture is transported to the nozzle where the pellets are accelerated to an appropriate blasting velocity. When directed to impact upon a target area, these dry ice pellets have sufficient energy to effectively remove most surface coatings through dry, abrasive contact. The meta-stable, dry ice pellets used for CO2 cleaning, while labeled 'high density,' are less dense than alternate, abrasive, particle blast media. In addition, after contacting the target surface, they return to their equilibrium condition: a superheated gas state. Most currently used grit blasting media are silicon dioxide based, which possess a sharp tetrahedral molecular structure. Silicon dioxide crystal structures will always produce smaller sharp-edged replicas of the original crystal upon fracture. Larger, softer dry ice pellets do not share the same sharp-edged crystalline structures as their non-sublimable counterparts when broken. In fact, upon contact with the target surface, dry ice pellets will plastically deform and break apart. As such, dry ice cleaning is less harmful to sensitive substrates, workers and the environment than chemical or abrasive cleaning systems. Dry ice cleaning system

  5. CO2 (dry ice) cleaning system

    NASA Astrophysics Data System (ADS)

    Barnett, Donald M.

    1995-03-01

    Tomco Equipment Company has participated in the dry ice (solid carbon dioxide, CO2) cleaning industry for over ten years as a pioneer in the manufacturer of high density, dry ice cleaning pellet production equipment. For over four years Tomco high density pelletizers have been available to the dry ice cleaning industry. Approximately one year ago Tomco introduced the DI-250, a new dry ice blast unit making Tomco a single source supplier for sublimable media, particle blast, cleaning systems. This new blast unit is an all pneumatic, single discharge hose device. It meters the insertion of 1/8 inch diameter (or smaller), high density, dry ice pellets into a high pressure, propellant gas stream. The dry ice and propellant streams are controlled and mixed from the blast cabinet. From there the mixture is transported to the nozzle where the pellets are accelerated to an appropriate blasting velocity. When directed to impact upon a target area, these dry ice pellets have sufficient energy to effectively remove most surface coatings through dry, abrasive contact. The meta-stable, dry ice pellets used for CO2 cleaning, while labeled 'high density,' are less dense than alternate, abrasive, particle blast media. In addition, after contacting the target surface, they return to their equilibrium condition: a superheated gas state. Most currently used grit blasting media are silicon dioxide based, which possess a sharp tetrahedral molecular structure. Silicon dioxide crystal structures will always produce smaller sharp-edged replicas of the original crystal upon fracture. Larger, softer dry ice pellets do not share the same sharp-edged crystalline structures as their non-sublimable counterparts when broken. In fact, upon contact with the target surface, dry ice pellets will plastically deform and break apart. As such, dry ice cleaning is less harmful to sensitive substrates, workers and the environment than chemical or abrasive cleaning systems. Dry ice cleaning system

  6. NIF Ambient Vibration Measurements

    SciTech Connect

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  7. 49 CFR 173.217 - Carbon dioxide, solid (dry ice).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Carbon dioxide, solid (dry ice). 173.217 Section... Class 7 § 173.217 Carbon dioxide, solid (dry ice). (a) Carbon dioxide, solid (dry ice), when offered for... permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture...

  8. 49 CFR 173.217 - Carbon dioxide, solid (dry ice).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Carbon dioxide, solid (dry ice). 173.217 Section... Class 7 § 173.217 Carbon dioxide, solid (dry ice). (a) Carbon dioxide, solid (dry ice), when offered for... permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture...

  9. 49 CFR 173.217 - Carbon dioxide, solid (dry ice).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Carbon dioxide, solid (dry ice). 173.217 Section... Class 7 § 173.217 Carbon dioxide, solid (dry ice). (a) Carbon dioxide, solid (dry ice), when offered for... permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture...

  10. 49 CFR 173.217 - Carbon dioxide, solid (dry ice).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Carbon dioxide, solid (dry ice). 173.217 Section... Class 7 § 173.217 Carbon dioxide, solid (dry ice). (a) Carbon dioxide, solid (dry ice), when offered for... permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture...

  11. 49 CFR 173.217 - Carbon dioxide, solid (dry ice).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Carbon dioxide, solid (dry ice). 173.217 Section... Class 7 § 173.217 Carbon dioxide, solid (dry ice). (a) Carbon dioxide, solid (dry ice), when offered for... permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture...

  12. BIOMASS DRYING TECHNOLOGIES

    EPA Science Inventory

    The report examines the technologies used for drying of biomass and the energy requirements of biomass dryers. Biomass drying processes, drying methods, and the conventional types of dryers are surveyed generally. Drying methods and dryer studies using superheated steam as the d...

  13. Mass Spectrometry Imaging under Ambient Conditions

    PubMed Central

    Wu, Chunping; Dill, Allison L.; Eberlin, Livia S.; Cooks, R. Graham; Ifa, Demian R.

    2012-01-01

    Mass spectrometry imaging (MSI) has emerged as an important tool in the last decade and it is beginning to show potential to provide new information in many fields owing to its unique ability to acquire molecularly specific images and to provide multiplexed information, without the need for labeling or staining. In MSI, the chemical identity of molecules present on a surface is investigated as a function of spatial distribution. In addition to now standard methods involving MSI in vacuum, recently developed ambient ionization techniques allow MSI to be performed under atmospheric pressure on untreated samples outside the mass spectrometer. Here we review recent developments and applications of MSI emphasizing the ambient ionization techniques of desorption electrospray ionization (DESI), laser ablation electrospray ionization (LAESI), probe electrospray ionization (PESI), desorption atmospheric pressure photoionization (DAPPI), femtosecond laser desorption ionization (fs-LDI), laser electrospray mass spectrometry (LEMS), infrared laser ablation metastable-induced chemical ionization (IR-LAMICI), liquid microjunction surface sampling probe mass spectrometry (LMJ-SSP MS), nanospray desorption electrospray ionization (nano-DESI), and plasma sources such as the low temperature plasma (LTP) probe and laser ablation coupled to flowing atmospheric-pressure afterglow (LA-FAPA). Included are discussions of some of the features of ambient MSI including the ability to implement chemical reactions with the goal of providing high abundance ions characteristic of specific compounds of interest and the use of tandem mass spectrometry to either map the distribution of targeted molecules with high specificity or to provide additional MS information in the structural identification of compounds. We also describe the role of bioinformatics in acquiring and interpreting the chemical and spatial information obtained through MSI, especially in biological applications for tissue

  14. New ambient pressure organic superconductors:. alpha. -(BEDT-TTF) sub 2 (NH sub 4 )Hg(SCN) sub 4 ,. beta. m-(BEDO-TTF) sub 3 Cu sub 2 (NCS) sub 3 , and. kappa. -(BEDT-TTF) sub 2 Cu(N(CN) sub 2 )Br

    SciTech Connect

    Wang, H.H.; Beno, M.A.; Carlson, K.D.; Geiser, U.; Kini, A.M.; Montgomery, L.K.; Thompson, J.E.; Williams, J.M.

    1990-01-01

    More than one hundred and twenty conducting salts based on the organic donor-molecule BEDT-TTF are known, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene (abbreviated herein as ET). Several of the early salts possessed tetrahedral and octahedral anions, such as (ET){sub 2}ClO{sub 4}(TCE), (ET){sub 2}PF{sub 6}, (ET){sub 2}ReO{sub 4}, and (ET){sub 2}BrO{sub 4}. The perchlorate salt is metallic to 1.4 K,{sup 1} and the perrenate derivative was the first ET based organic superconductor ({Tc} 2 K, 4.5 kbar). Since the discovery of ambient pressure superconductivity in {beta}-(ET){sub 2}I{sub 3} ({Tc} 1.4 K),{sup 5} other isostructural {beta}-(ET){sub 2}X salts have been prepared with higher {Tc}'s. A structure-property correlation for the {beta}-type salts has been reviewed in this volume; it predicts that {Tc}'s higher than 8K are possible if {beta}-salts with linear anions longer than I{sub 3}{sup {minus}} can be synthesized. During the search for new linear anions, a variety of compounds with discovered with polymeric anions. The report of superconductivity in {kappa}-(ET){sub 4}Hg{sub 3}X{sub 8} (X = Cl, {Tc} 5.4 K 29 kbar and X = Br, {Tc} 4.3 K ambient pressure and 6.7 K 3.5 kbar) and {kappa}-(ET){sub 2}Cu(NCS){sub 2} ({Tc} 10.4 K) further stimulated the search for novel polymeric anions. A general synthetic strategy for preparing new salts containing polymeric anions is to couple a coordinatively unsaturated neutral transition metal halide/pseudohalide with a simple halide or pseudohalide during an electrocrystallization synthesis. In this article, the authors discuss three new ambient pressure organic superconductors with novel polymeric anions, {alpha}-(ET){sub 2}(NH{sub 4})Hg(SCN){sub 4}, {beta}m-(BO){sub 3}Cu{sub 2}(NCS){sub 3} and {kappa}-(ET){sub 2}Cu(N(CN){sub 2})Br. 48 refs., 8 figs., 2 tabs.

  15. Welding polarity effects on weld spatters and bead geometry of hyperbaric dry GMAW

    NASA Astrophysics Data System (ADS)

    Xue, Long; Wu, Jinming; Huang, Junfen; Huang, Jiqiang; Zou, Yong; Liu, Jian

    2016-03-01

    Welding polarity has influence on welding stability to some extent, but the specific relationship between welding polarity and weld quality has not been found, especially under the hyperbaric environment. Based on a hyperbaric dry welding experiment system, gas metal arc welding(GMAW) experiments with direct current electrode positive(DCEP) and direct current electrode negative(DCEN) operations are carried out under the ambient pressures of 0.1 MPa, 0.4 MPa, 0.7 MPa and 1.0 MPa to find the influence rule of different welding polarities on welding spatters and weld bead geometry. The effects of welding polarities on the weld bead geometry such as the reinforcement, the weld width and the penetration are discussed. The experimental results show that the welding spatters gradually grow in quantity and size for GMAW with DCEP, while GMAW with DCEN can produce fewer spatters comparatively with the increase of the ambient pressure. Compared with DCEP, the welding current and arc voltage waveforms for DCEN is more stable and the distribution of welding current probability density for DCEN is more concentrated under the hyperbaric environment. When the ambient pressure is increased from 0.1 MPa to 1.0 MPa, the effects of welding polarities on the reinforcement, the weld width and the penetration are as follows: an increase of 0.8 mm for the weld reinforcement is produced by GMAW with DCEN and 1.3 mm by GMAW with DCEP, a decrease of 7.2 mm for the weld width is produced by DCEN and 6.1 mm by DCEP; and an increase of 3.9 mm for the penetration is produced by DCEN and 1.9 mm by DCEP. The proposed research indicates that the desirable stability in the welding procedure can be achieved by GMAW with DCEN operation under the hyperbaric environment.

  16. Dry mouth during cancer treatment

    MedlinePlus

    Chemotherapy - dry mouth; Radiation therapy - dry mouth; Transplant - dry mouth; Transplantation - dry mouth ... Some cancer treatments and medicines can cause dry mouth. Symptoms you may have include: Mouth sores Thick ...

  17. Simulations of high and low viscosity micro-scale droplets splashing on a dry surface

    NASA Astrophysics Data System (ADS)

    Boelens, Arnout; Latka, Andrzej; de Pablo, Juan

    When a droplet hits a dry surface at atmospheric pressure with a high enough impact velocity, it splashes and breaks apart into many smaller droplet. However, when the ambient gas pressure is reduced, splashing is suppressed. This is contrary to intuition, which suggest a more violent splash should occur at lower gas densities due to reduced drag forces. Although splashes of high and low viscosity liquids visually look very different, they also obey the pressure effect. In this study the effect of viscosity on splashing is investigated, to get a better understanding of the pressure effect in general. Simulation results are presented comparing splashing of low viscosity ethanol with high viscosity silicone oil in air. The droplets are several hundred microns large. The simulations are 2D, and are performed using a Volume Of Fluid approach. The contact line is described using the Generalized Navier Boundary Condition. Both the gas phase and the liquid phase are assumed to be incompressible. The results of the simulations show good agreement with experiments, including reproduction of the pressure effect, and suggest that the same scaling laws that apply to lamella formation in simple drop deposition, also apply to splashing droplets.

  18. Drying of a coffee drop: differences between dry and wet tables?

    NASA Astrophysics Data System (ADS)

    Boulogne, François; Ingremeau, François; Stone, Howard

    2015-11-01

    We have all experienced that a coffee drop drying on a table leaves a ring stain. The radial flow in the drop coupled with a larger drying flux at its edge are the reasons for the particle accumulation in the liquid wedge. However, if the substrate is wet, the liquid surrounding the drop modifies the vapor distribution, and thus the drop evaporation dynamics. Our experimental observations show that the drying kinetics and the particle motion are affected by the ambient conditions. We rationalize our experimental findings with a model that describes the spatially varying evaporation as well as the temporal evolution of the particles forming the ring. We believe that these results are of practical interest for printing applications involving multiple drop systems or drying surfaces. F.B. acknowledges that the research leading to these results received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement 623541.

  19. Stabilized, Freeze-Dried PCR Mix for Detection of Mycobacteria

    PubMed Central

    Klatser, Paul R.; Kuijper, Sjoukje; van Ingen, Cor W.; Kolk, Arend H. J.

    1998-01-01

    We report here the development of a freeze-drying procedure allowing stabilization at ambient temperature of preoptimized, premixed, and predispensed PCR mixes aimed at the detection of mycobacteria in clinical materials. The freeze-dried mixes retained activity at 4°C and at 20°C for 1 year and for 3 months at 37°C, as judged by their performance with 50 and 500 fg of purified Mycobacterium bovis BCG target DNA. PMID:9620427

  20. Thermodynamic Pressure/Temperature Transducer Health Check

    NASA Technical Reports Server (NTRS)

    Immer, Christopher D. (Inventor); Eckhoff, Anthony (Inventor); Medelius, Pedro J. (Inventor); Deyoe, Richard T. (Inventor); Starr, Stanley O. (Inventor)

    2004-01-01

    A device and procedure for checking the health of a pressure transducer in situ is provided. The procedure includes measuring a fixed change in pressure above ambient pressure and a fixed change in pressure below ambient pressure. This is done by first sealing an enclosed volume around the transducer with a valve. A piston inside the sealed volume is increasing the pressure. A fixed pressure below ambient pressure is obtained by opening the valve, driving the piston The output of the pressure transducer is recorded for both the overpressuring and the underpressuring. By comparing this data with data taken during a preoperative calibration, the health of the transducer is determined from the linearity, the hysteresis, and the repeatability of its output. The further addition of a thermometer allows constant offset error in the transducer output to be determined.

  1. Using solar dryers to dry clay bricks

    SciTech Connect

    Bernal, J.A.; Wicker, R.B.

    1996-12-31

    Experiments using a small-scale solar dryer have been performed to determine the effect of incorporating solar dryers in the pre-firing stage of clay brick production. A comparison of brick moisture content over time is presented for dry bricks that underwent additional drying either naturally through direct exposure, in convection ovens set at 65.6 C and 104 C, in the solar dryer, or sealed in plastic bags. The ambient temperature and relative humidity were monitored along with the solar dryer temperature. Results indicated the solar dryer removed from one to two percent more moisture than natural drying, but removed less moisture than did the ovens. A similar comparison of wet bricks naturally dried, oven dried, and placed in the solar dryer for periods of five and seven days is also presented. The solar dryer reduced the amount of time required for bricks to be dried to a specified moisture content and increased the amount of moisture removed for a given amount of time.

  2. Superconductivity in the metallic elements at high pressures

    NASA Astrophysics Data System (ADS)

    Hamlin, J. J.

    2015-07-01

    Although the highest superconducting critical temperature, Tc , found in an elemental solid at ambient pressure is 9.2 K (niobium), under the application of ultra-high pressures, several elements exhibit Tc values near or above 20 K. This review includes a survey of the occurrence and understanding of pressure-induced superconductivity in the subset of elements that are metallic at ambient pressure. A particular focus is directed towards those elements that display the highest superconducting critical temperatures or exhibit substantial increases in Tc with pressure. A separate article in this issue by Shimizu will cover pressure-induced superconductivity in elements that are insulating at ambient pressure.

  3. Dry Mouth (Xerostomia)

    MedlinePlus

    ... Gum Disease TMJ Disorders Oral Cancer Dry Mouth Burning Mouth Tooth Decay See All Oral Complications of Systemic ... mouth trouble chewing, swallowing, tasting, or speaking a burning feeling in the mouth a dry feeling in the throat cracked lips ...

  4. Dry eye syndrome

    MedlinePlus

    ... of dry eyes include: Dry environment or workplace (wind, air conditioning) Sun exposure Smoking or second-hand ... NOT smoke and avoid second-hand smoke, direct wind, and air conditioning. Use a humidifier, especially in ...

  5. Dry Skin (Xerosis)

    MedlinePlus

    ... skin, which may bleed if severe. Chapped or cracked lips. When dry skin cracks, germs can get ... cause the skin to become dry, raw, and cracked. Swimming : Some pools have high levels of chlorine, ...

  6. Acute cardiopulmonary effects induced by the inhalation of concentrated ambient particles during seasonal variation in the city of São Paulo.

    PubMed

    Brito, Jôse Mára de; Macchione, Mariângela; Yoshizaki, Kelly; Toledo-Arruda, Alessandra Choqueta; Saraiva-Romanholo, Beatriz Mangueira; Andrade, Maria de Fátima; Mauad, Thaís; Rivero, Dolores Helena Rodriguez Ferreira; Saldiva, Paulo Hilário Nascimento

    2014-09-01

    Ambient particles may undergo modifications to their chemical composition as a consequence of climatic variability. The determination of whether these changes modify the toxicity of the particles is important for the understanding of the health effects associated with particle exposure. The objectives were to determine whether low levels of particles promote cardiopulmonary effects, and to assess if the observed alterations are influenced by season. Mice were exposed to 200 μg/m(3) concentrated ambient particles (CAPs) and filtered air (FA) in cold/dry and warm/humid periods. Lung hyperresponsiveness, heart rate, heart rate variability, and blood pressure were evaluated 30 min after each exposure. After 24 h, blood and tissue samples were collected. During both periods (warm/humid and cold/dry), CAPs induced alterations in red blood cells and lung inflammation. During the cold/dry period, CAPs reduced the mean corpuscular volume levels and increased erythrocytes, hemoglobin, mean corpuscular hemoglobin concentration, and red cell distribution width coefficient variation levels compared with the FA group. Similarly, CAPs during the warm/humid period decreased mean corpuscular volume levels and increased erythrocytes, hemoglobin, hematocrit, and red cell distribution width coefficient variation levels compared with the FA group. CAPs during the cold/dry period increased the influx of neutrophils in the alveolar parenchyma. Short-term exposure to low concentrations of CAPs elicited modest but significant pulmonary inflammation and, to a lesser extent, changes in blood parameters. In addition, our data support the concept that changes in climate conditions slightly modify particle toxicity because equivalent doses of CAPs in the cold/dry period produced a more exacerbated response. PMID:25012028

  7. The importance of the poikilohydric nature of lichens as natural tracers for delta18O of ambient vapour

    NASA Astrophysics Data System (ADS)

    Hartard, Britta; Cuntz, Matthias; Lakatos, Michael; Máguas, Cristina

    2010-05-01

    The stable isotope composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in poikilohydric organisms (i.e. lichens and bryophytes), where relative water content equilibrate with the surrounding humidity conditions and that are able to use distinct water sources such as precipitation, dew, fog and also water vapour. Moreover, lichens are ubiquitous organisms, and on a global scale, they are found in nearly all terrestrial ecosystems and also within these ecosystems they inhabit many microhabitats. As poikilohydric. especially green algal lichens are known to photosynthetically reactivate solely upon uptake of atmospheric moisture, even at non-saturated ambient humidity conditions. To understand basic isotope exchange processes on non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrates with the isotopic composition of surrounding water vapour. We found that the thallus water of lichens exposed to high relative humidity shows fast isotopic equilibration with the surrounding vapour regardless of whether the lichen experiences water loss or vapour uptake. The time until isotopic equilibrium is achieved depends on the initial water status as well as on the lichen's specific morphology. It ranged from 5 to 12h in previously dried lichens to approximately 40h in lichens previously rehydrated with liquid water of distinct isotopic composition. Even though markedly slower, isotopic equilibration between leaf water and ambient vapour may also occur in homoiohydric plants exposed to high relative humidity. At low relative humidity, however, the apparent vapour pressure deficit between the evaporative sites and the ambient air and the increased stomatal diffusion resistance generally causes leaf water enrichment. In contrast, poikilohydric lichens lack

  8. Determination of end point of primary drying in freeze-drying process control.

    PubMed

    Patel, Sajal M; Doen, Takayuki; Pikal, Michael J

    2010-03-01

    Freeze-drying is a relatively expensive process requiring long processing time, and hence one of the key objectives during freeze-drying process development is to minimize the primary drying time, which is the longest of the three steps in freeze-drying. However, increasing the shelf temperature into secondary drying before all of the ice is removed from the product will likely cause collapse or eutectic melt. Thus, from product quality as well as process economics standpoint, it is very critical to detect the end of primary drying. Experiments were conducted with 5% mannitol and 5% sucrose as model systems. The apparent end point of primary drying was determined by comparative pressure measurement (i.e., Pirani vs. MKS Baratron), dew point, Lyotrack (gas plasma spectroscopy), water concentration from tunable diode laser absorption spectroscopy, condenser pressure, pressure rise test (manometric temperature measurement or variations of this method), and product thermocouples. Vials were pulled out from the drying chamber using a sample thief during late primary and early secondary drying to determine percent residual moisture either gravimetrically or by Karl Fischer, and the cake structure was determined visually for melt-back, collapse, and retention of cake structure at the apparent end point of primary drying (i.e., onset, midpoint, and offset). By far, the Pirani is the best choice of the methods tested for evaluation of the end point of primary drying. Also, it is a batch technique, which is cheap, steam sterilizable, and easy to install without requiring any modification to the existing dryer. PMID:20058107

  9. Design and Application of Variable Temperature Setup for Scanning Electron Microscopy in Gases and Liquids at Ambient Conditions.

    PubMed

    Al-Asadi, Ahmed S; Zhang, Jie; Li, Jianbo; Potyrailo, Radislav A; Kolmakov, Andrei

    2015-06-01

    Scanning electron microscopy (SEM) of nanoscale objects in dry and fully hydrated conditions at different temperatures is of critical importance in revealing details of their interactions with an ambient environment. Currently available WETSEM capsules are equipped with thin electron-transparent membranes and allow imaging of samples at atmospheric pressure, but do not provide temperature control over the sample. Here, we developed and tested a thermoelectric cooling/heating setup for WETSEM capsules to allow ambient pressure in situ SEM studies with a temperature range between -15 and 100°C in gaseous, liquid, and frozen conditions. The design of the setup also allows for correlation of the SEM with optical microscopy and spectroscopy. As a demonstration of the possibilities of the developed approach, we performed real-time in situ microscopy studies of water condensation on a surface of Morpho sulkowskyi butterfly wing scales. We observed that initial water nucleation takes place on top of the scale ridges. These results confirmed earlier discovery of a preexisting polarity gradient of the ridges of Morpho butterflies. Our developed thermoelectric cooling/heating setup for environmental capsules meets the diverse needs for in situ nanocharacterization in material science, catalysis, microelectronics, chemistry, and biology. PMID:26036327

  10. National Ambient Radiation Database

    SciTech Connect

    Dziuban, J.; Sears, R.

    2003-02-25

    The U.S. Environmental Protection Agency (EPA) recently developed a searchable database and website for the Environmental Radiation Ambient Monitoring System (ERAMS) data. This site contains nationwide radiation monitoring data for air particulates, precipitation, drinking water, surface water and pasteurized milk. This site provides location-specific as well as national information on environmental radioactivity across several media. It provides high quality data for assessing public exposure and environmental impacts resulting from nuclear emergencies and provides baseline data during routine conditions. The database and website are accessible at www.epa.gov/enviro/. This site contains (1) a query for the general public which is easy to use--limits the amount of information provided, but includes the ability to graph the data with risk benchmarks and (2) a query for a more technical user which allows access to all of the data in the database, (3) background information on ER AMS.

  11. Effect of ambient humidity on ionic electroactive polymer actuators

    NASA Astrophysics Data System (ADS)

    Vunder, Veiko; Hamburg, Edgar; Johanson, Urmas; Punning, Andres; Aabloo, Alvo

    2016-05-01

    Comparable electromechanical measurements were carried out with carbon-based ionic electroactive polymer actuators in vacuum, dry inert, and in ambient air environment. The results bring forward the effect of ambient humidity on the electrical and mechanical parameters of the laminates of this type. Presence of water decreases the Young’s modulus of the polymer and lowers the viscosity of the ionic liquid, which, in turn, is accompanied by the increase of ionic conductivity of the electrolyte. The factual bending behavior of the actuator is a result of the combined effect of these factors. A four-parameter model was developed for the quantitative estimation of the rates of forward-actuation and back-relaxation as well as the electrical parameters. An important outcome of the experiments is the observation that there is nearly no back-relaxation in vacuum and in dry inert environment.

  12. Catalyst Chemical State during CO Oxidation Reaction on Cu(111) Studied with Ambient-Pressure X-ray Photoelectron Spectroscopy and Near Edge X-ray Adsorption Fine Structure Spectroscopy.

    PubMed

    Eren, Baran; Heine, Christian; Bluhm, Hendrik; Somorjai, Gabor A; Salmeron, Miquel

    2015-09-01

    The chemical structure of a Cu(111) model catalyst during the CO oxidation reaction in the CO+O2 pressure range of 10-300 mTorr at 298-413 K was studied in situ using surface sensitive X-ray photoelectron and adsorption spectroscopy techniques [X-ray photoelectron spectroscopy (XPS) and near edge X-ray adsorption fine structure spectroscopy (NEXAFS)]. For O2:CO partial pressure ratios below 1:3, the surface is covered by chemisorbed O and by a thin (∼1 nm) Cu2O layer, which covers completely the surface for ratios above 1:3 between 333 and 413 K. The Cu2O film increases in thickness and exceeds the escape depth (∼3-4 nm) of the XPS and NEXAFS photoelectrons used for analysis at 413 K. No CuO formation was detected under the reaction conditions used in this work. The main reaction intermediate was found to be CO2(δ-), with a coverage that correlates with the amount of Cu2O, suggesting that this phase is the most active for CO oxidation. PMID:26275662

  13. High-intensity drying processes: Impulse drying

    SciTech Connect

    Orloff, D.I.

    1990-09-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. Impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. Hence, it has been projected that wide commercialization of impulse drying would result in at least a 10% industry-wide energy saving. This report covers work completed between October, 1988 and September, 1989. During this period, pilot press trails demonstrated that newsprint as well as linerboard experience delamination. Hence, the major focus of the research was the resolution of the delamination problem. In order to document potential process improvements, measurement methods were developed to quantify sheet delamination. Using these methods, low thermal diffusivity ceramic roll surfaces were shown to extend the range of impulse drying operating conditions while avoiding sheet delamination. As compared to steel surfaces, ceramics were found to provide significantly higher water volume without inducing sheet delamination. 46 figs., 4 tabs.

  14. Dry deposition velocities

    SciTech Connect

    Sehmel, G.A.

    1984-03-01

    Dry deposition velocities are very difficult to predict accurately. In this article, reported values of dry deposition velocities are summarized. This summary includes values from the literature on field measurements of gas and particle dry deposition velocities, and the uncertainties inherent in extrapolating field results to predict dry deposition velocities are discussed. A new method is described for predicting dry deposition velocity using a least-squares correlation of surface mass transfer resistances evaluated in wind tunnel experiments. 14 references, 4 figures, 1 table.

  15. Ambient Radon-222 Monitoring in Amargosa Valley, Nevada

    SciTech Connect

    L.H. Karr; J.J. Tappen; D. Shafer; K.J. Gray

    2008-06-05

    As part of a program to characterize and baseline selected environmental parameters in the region around the proposed repository at Yucca Mountain, Nevada, ambient radon-222 monitoring was conducted in the rural community of Amargosa Valley, the community closest to the proposed repository site. Passive integrating radon monitors and a continuous radon monitoring instrument were deployed adjacent to the Community Environmental Monitoring Program (CEMP) (http://www.cemp.dri.edu/index.html) station located in the Amargosa Valley Community Center near the library. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated radon measurements as well as verify meteorological data collected by the continuous radon monitoring instrument. Additionally, different types of environmental enclosures that housed the monitors and instrument were used to determine if particular designs influenced the ambient radon measurements.

  16. Electronically-Scanned Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Coe, C. F.; Parra, G. T.; Kauffman, R. C.

    1984-01-01

    Sensors not pneumatically switched. Electronic pressure-transducer scanning system constructed in modular form. Pressure transducer modules and analog to digital converter module small enough to fit within cavities of average-sized wind-tunnel models. All switching done electronically. Temperature controlled environment maintained within sensor modules so accuracy maintained while ambient temperature varies.

  17. Ambient pyrite in precambrian chert: new evidence and a theory.

    PubMed

    Knoll, A H; Barghoorn, E S

    1974-06-01

    Ambient pyrites of two distinct types were described from middle Precambrian rocks of the Lake Superior area. A new class of this phenomenon is here described from middle Precambrian chert from western Australia. The newly found ambient pyrites are quite minute and characteristically occur in groups forming a "starburst" pattern. All three types of ambient pyrite may be explained in terms of pressure solution initiated by gas evolution from organic material attached to the pyrite. Thermal degradation of the kerogen produces the gases which, due to the impermeability of the encompassing chert, build up the pressures necessary to initiate solution. Pyrite appendages bear a striking resemblance to micro-organisms and, thus, constitute the smallest pseudofossils known. PMID:16592159

  18. Evaluation of Fermentation, Drying, and/or High Pressure Processing on Viability of Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Trichinella spiralis in Raw Pork and Genoa Salami

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the present study, we evaluated the effect of fermentation/drying on viability of T. spiralis in Genoa salami. We also evaluated HPP for efficacy towards T. spiralis larvae in trichinae-infected pig masseter muscle as an alternate to curing for trichinae control. We also validated the integrated ...

  19. Ambient Concentrations of Carbon Monoxide

    EPA Science Inventory

    This indicator presents trends in ambient carbon monoxide concentrations across the U.S. from 1980 to 2009. By tracking ambient carbon monoxide (CO) – a criteria pollutant with the potential to cause cardiovascular and neurological damage – this dataset shows how a...

  20. Spectral analysis of ambient weather patterns

    SciTech Connect

    Anderson, J.V.; Subbarao, K.

    1981-01-01

    A Fourier spectral analysis of ambient weather data, consisting of global and direct solar radiation, dry and wet bulb temperatures, and wind speed, is given. By analyzing the heating and cooling seasons independently, seasonal variations are isolated and a cleaner spectrum emerges. This represents an improvement over previous work in this area, in which data for the entire year were analyzed together. As a demonstration of the efficacy of this method, synthetic data constructed with a small number of parameters are used in typical simulations, and the results are compared with those obtained with the original data. A spectral characterization of fluctuations around the moving average is given, and the changes in the fluctuation from season to season are examined.

  1. Drying-Induced Evaporation of Secondary Organic Aerosol during Summer.

    PubMed

    El-Sayed, Marwa M H; Amenumey, Dziedzorm; Hennigan, Christopher J

    2016-04-01

    This study characterized the effect of drying on the concentration of atmospheric secondary organic aerosol (SOA). Simultaneous measurements of water-soluble organic carbon in the gas (WSOCg) and particle (WSOCp) phases were carried out in Baltimore, MD during the summertime. To investigate the effect of drying on SOA, the WSOCp measurement was alternated through an ambient channel (WSOCp) and a "dried" channel (WSOCp,dry) maintained at ∼35% relative humidity (RH). The average mass ratio between WSOCp,dry and WSOCp was 0.85, showing that significant evaporation of the organic aerosol occurred due to drying. The average amount of evaporated water-soluble organic matter (WSOM = WSOC × 1.95) was 0.6 μg m(-3); however, the maximum evaporated WSOM concentration exceeded 5 μg m(-3), demonstrating the importance of this phenomenon. The systematic difference between ambient and dry channels indicates a significant and persistent source of aqueous SOA formed through reversible uptake processes. The wide-ranging implications of the work are discussed, and include: new insight into atmospheric SOA formation; impacts on particle measurement techniques; a newly identified bias in PM2.5 measurements using the EPA's Federal Reference and Equivalent Methods (FRM and FEM); atmospheric model evaluations; and the challenge in relating ground-based measurements to remote sensing of aerosol properties. PMID:26910726

  2. Anisotropic Ambient Volume Shading.

    PubMed

    Ament, Marco; Dachsbacher, Carsten

    2016-01-01

    We present a novel method to compute anisotropic shading for direct volume rendering to improve the perception of the orientation and shape of surface-like structures. We determine the scale-aware anisotropy of a shading point by analyzing its ambient region. We sample adjacent points with similar scalar values to perform a principal component analysis by computing the eigenvectors and eigenvalues of the covariance matrix. In particular, we estimate the tangent directions, which serve as the tangent frame for anisotropic bidirectional reflectance distribution functions. Moreover, we exploit the ratio of the eigenvalues to measure the magnitude of the anisotropy at each shading point. Altogether, this allows us to model a data-driven, smooth transition from isotropic to strongly anisotropic volume shading. In this way, the shape of volumetric features can be enhanced significantly by aligning specular highlights along the principal direction of anisotropy. Our algorithm is independent of the transfer function, which allows us to compute all shading parameters once and store them with the data set. We integrated our method in a GPU-based volume renderer, which offers interactive control of the transfer function, light source positions, and viewpoint. Our results demonstrate the benefit of anisotropic shading for visualization to achieve data-driven local illumination for improved perception compared to isotropic shading. PMID:26529745

  3. Polycyclic aromatic hydrocarbons (PAHs) in ambient aerosols from Beijing: characterization of low volatile PAHs by positive-ion atmospheric pressure photoionization (APPI) coupled with Fourier transform ion cyclotron resonance.

    PubMed

    Jiang, Bin; Liang, Yongmei; Xu, Chunming; Zhang, Jingyi; Hu, Miao; Shi, Quan

    2014-05-01

    Aromatic fractions derived from aerosol samples were characterized by gas chromatography and mass spectrometry (GC-MS), high temperature simulated distillation (SIMDIS), and positive-ion atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. It was found that about 27 wt % compounds in aromatic fractions could not be eluted from a GC column and some large molecule PAHs were neglected in GC-MS analysis. APPI FT-ICR MS was proven to be a powerful approach for characterizing the molecular composition of aromatics, especially for the large molecular species. An aromatic sample from Beijing urban aerosol was successfully characterized by APPI FT-ICR MS. Results showed that most abundant aromatic compounds in PM2.5 (particles with aerodynamic diameter ≤ 2.5 μm) were highly condensed hydrocarbons with 4-8 aromatic rings and their homologues with very short alkyl chains. Furthermore, heteroatom-containing hydrocarbons were found as the significant components of the aromatic fractions: O1, O2, N1, and S1 class species with 10-28 DBEs (double bond equivalents) and 14-38 carbon numbers were identified by APPI FT-ICR MS. The heteroatom PAHs had similar DBEs and carbon number distribution as regular PAHs. PMID:24702199

  4. 46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F)....

  5. 46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F)....

  6. 46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F)....

  7. Dephosphorization when using DRI

    SciTech Connect

    2005-09-21

    The increase in high quality steel production in electric arc furnaces (EAFs) requires the use of scrap substitute materials, such as Direct Reduced Iron (DRI) and Hot Briquetted Iron (HBI). Although DRI and HBI products have lower copper and nickel contents than most scrap materials, they can contain up to ten times more phosphorus. This project, led by Carnegie Mellon University’s Center for Iron and Steelmaking Research, improves the understanding of how phosphorus behaves when DRI and HBI melt.

  8. Studies on drying and storage of chilgoza (Pinus gerardiana) nuts.

    PubMed

    Thakur, N S; Sharma, Somesh; Gupta, Rakesh; Gupta, Atul

    2014-09-01

    Present studies were undertaken with the aim of screening a suitable mode of drying and packaging material for storage of chilgoza nuts. A temperature of 55 °C was found most suitable for the drying of nuts in cabinet drier. Cabinet drier was found the best drying mode among four for drying of chilgoza nuts on the basis of quality characteristics such as moisture, water activity and sensory attributes. Further, out of five packaging materials selected in the study, glass jar followed by aluminium laminate pouch was found to be suitable for the packing and storage of dried nuts in ambient conditions for 6 months on the basis of retention of better physico-chemical and sensory attributes. PMID:25190868

  9. Effect of far-infrared radiation assisted microwave-vacuum drying on drying characteristics and quality of red chilli.

    PubMed

    Saengrayap, Rattapon; Tansakul, Ampawan; Mittal, Gauri S

    2015-05-01

    Fresh red chilli (Capsicum frutescens L.) was dried using microwave-vacuum drying (MVD) and the far-infrared radiation assisted microwave-vacuum drying (FIR-MVD) method. The MVD was operated using the microwave power of 100, 200 and 300 W under absolute pressure of 21.33, 28.00 and 34.66 kPa. In terms of FIR-MVD, far-infrared power was applied at 100, 200 and 300 W. The effect of drying conditions, i.e., microwave power, absolute pressure and FIR power, on drying characteristics and qualities of dried product were investigated. It was observed that an increase in microwave power and FIR power with a decrease in absolute pressure could accelerate the drying rate. It was also found that FIR-MVD method required shorter drying time than MVD. Moreover, qualities, i.e., color changes, texture, rehydration ability and shrinkage, of FIR-MVD chilli were found to be better than those of MVD. Consequently, the optimum drying condition of FIR-MVD within this study was microwave power of 300 W under absolute pressure of 21.33 kPa with FIR power of 300 W. PMID:25892759

  10. Moisture-swing sorption for carbon dioxide capture from ambient air: a thermodynamic analysis.

    PubMed

    Wang, Tao; Lackner, Klaus S; Wright, Allen B

    2013-01-14

    An ideal chemical sorbent for carbon dioxide capture from ambient air (air capture) must have a number of favourable properties, such as environmentally benign behaviour, a high affinity for CO(2) at very low concentration (400 ppm), and a low energy cost for regeneration. The last two properties seem contradictory, especially for sorbents employing thermal swing adsorption. On the other hand, thermodynamic analysis shows that the energy cost of an air capture device need only be slightly larger than that of a flue gas scrubber. The moisture swing separation process studied in this paper provides a novel approach to low cost CO(2) capture from air. The anionic exchange resin sorbent binds CO(2) when dry and releases it when wet. A thermodynamic model with coupled phase and chemical equilibria is developed to study the complex H(2)O-CO(2)-resin system. The moisture swing behaviour is compatible with hydration energies changing with the activity of water on the resin surfaces. This activity is in turn set by the humidity. The rearrangement of hydration water on the resin upon the sorption of a CO(2) molecule is predicted as a function of the humidity and temperature. Using water as fuel to drive the moisture swing enables an economical, large-scale implementation of air capture. By generating CO(2) with low partial pressures, the present technology has implications for in situ CO(2) utilizations which require low pressure CO(2) gas rather than liquid CO(2). PMID:23172123

  11. To Dry Or Not To Dry

    ERIC Educational Resources Information Center

    Oaks, Audrey E.

    1977-01-01

    Perhaps one of the most frustrating problems which confront many teachers is lack of adequate drying space or facilities for prints, paintings and three-dimensional art activities. Suggests requirements necessary for an adequate storage unit and how to construct one. (Author/RK)

  12. Indiana Corn Dry Mill

    SciTech Connect

    2006-09-01

    The goal of this project is to perform engineering, project design, and permitting for the creation and commercial demonstration of a corn dry mill biorefinery that will produce fuel-grade ethanol, distillers dry grain for animal feed, and carbon dioxide for industrial use.

  13. Tray Drying of Solids.

    ERIC Educational Resources Information Center

    Afacan, Artin; Masliyah, Jacob

    1984-01-01

    Describes a drying experiment useful in presenting the concept of simultaneous heat and mass transfer. Background information, equipment requirements, experimental procedures, and results are provided. The reasonably good agreement in the calculated rate of drying and that observed experimentally makes students feel confident in applying…

  14. Dynamic Stratification in Drying Films of Colloidal Mixtures.

    PubMed

    Fortini, Andrea; Martín-Fabiani, Ignacio; De La Haye, Jennifer Lesage; Dugas, Pierre-Yves; Lansalot, Muriel; D'Agosto, Franck; Bourgeat-Lami, Elodie; Keddie, Joseph L; Sear, Richard P

    2016-03-18

    In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification. PMID:27035324

  15. Dynamic Stratification in Drying Films of Colloidal Mixtures

    NASA Astrophysics Data System (ADS)

    Fortini, Andrea; Martín-Fabiani, Ignacio; De La Haye, Jennifer Lesage; Dugas, Pierre-Yves; Lansalot, Muriel; D'Agosto, Franck; Bourgeat-Lami, Elodie; Keddie, Joseph L.; Sear, Richard P.

    2016-03-01

    In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.

  16. Viewpoint-based ambient occlusion.

    PubMed

    González, Francisco; Sbert, Mateu; Feixas, Miquel

    2008-01-01

    A new ambient occlusion technique builds a channel between various viewpoints and an object's polygons, providing the information needed to create an occlusion map with multiple application possibilities. PMID:18350932

  17. Microbial activity at gigapascal pressures.

    PubMed

    Sharma, Anurag; Scott, James H; Cody, George D; Fogel, Marilyn L; Hazen, Robert M; Hemley, Russell J; Huntress, Wesley T

    2002-02-22

    We observed physiological and metabolic activity of Shewanella oneidensis strain MR1 and Escherichia coli strain MG1655 at pressures of 68 to 1680 megapascals (MPa) in diamond anvil cells. We measured biological formate oxidation at high pressures (68 to 1060 MPa). At pressures of 1200 to 1600 MPa, living bacteria resided in fluid inclusions in ice-VI crystals and continued to be viable upon subsequent release to ambient pressures (0.1 MPa). Evidence of microbial viability and activity at these extreme pressures expands by an order of magnitude the range of conditions representing the habitable zone in the solar system. PMID:11859192

  18. Calculation Of Pneumatic Attenuation In Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.

    1991-01-01

    Errors caused by attenuation of air-pressure waves in narrow tubes calculated by method based on fundamental equations of flow. Changes in ambient pressure transmitted along narrow tube to sensor. Attenuation of high-frequency components of pressure wave calculated from wave equation derived from Navier-Stokes equations of viscous flow in tube. Developed to understand and compensate for frictional attenuation in narrow tubes used to connect aircraft pressure sensors with pressure taps on affected surfaces.

  19. 14 CFR 23.1325 - Static pressure system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure...

  20. 14 CFR 23.1325 - Static pressure system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure...

  1. 14 CFR 23.1325 - Static pressure system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure...

  2. 14 CFR 23.1325 - Static pressure system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure...

  3. 14 CFR 23.1325 - Static pressure system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure...

  4. Dry imaging cameras

    PubMed Central

    Indrajit, IK; Alam, Aftab; Sahni, Hirdesh; Bhatia, Mukul; Sahu, Samaresh

    2011-01-01

    Dry imaging cameras are important hard copy devices in radiology. Using dry imaging camera, multiformat images of digital modalities in radiology are created from a sealed unit of unexposed films. The functioning of a modern dry camera, involves a blend of concurrent processes, in areas of diverse sciences like computers, mechanics, thermal, optics, electricity and radiography. Broadly, hard copy devices are classified as laser and non laser based technology. When compared with the working knowledge and technical awareness of different modalities in radiology, the understanding of a dry imaging camera is often superficial and neglected. To fill this void, this article outlines the key features of a modern dry camera and its important issues that impact radiology workflow. PMID:21799589

  5. Packaged kiln dried firewood

    SciTech Connect

    Cutrara, A.

    1986-07-01

    A process is described for kiln drying firewood consisting of essentially uniform lengths of split firewood pieces, the process comprising splitting essentially uniform lengths of green tree logs to form firewood pieces, placing the firewood pieces in open mesh bags to provide a plurality of bags of firewood, placing the plurality of bags of green firewood pieces in a kiln drying oven, kiln drying the pieces at temperatures in excess of 150/sup 0/F. by moving heated air over the pieces until the pieces have an overall moisture content ranging from 15% up to 30% by weight, operating the kiln at a temperature below a level which would render the structural characteristics of the bag useless and removing the kiln dried firewood pieces in the plurality of bags from the kiln drying oven.

  6. 29 CFR 1910.161 - Fixed extinguishing systems, dry chemical.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Fire Protection Fixed Fire Suppression Equipment... employer shall sample the dry chemical supply of all but stored pressure systems at least annually...

  7. Vacuum contact drying kinetics of Jack pine wood and its influence on mechanical properties: industrial applications

    NASA Astrophysics Data System (ADS)

    Ouertani, Sahbi; Koubaa, Ahmed; Azzouz, Soufien; Hassini, Lamine; Dhib, Kamel Ben; Belghith, Ali

    2014-12-01

    Wood can be dried rapidly using combined contact heating and low vacuum. However, the impact on Jack pine wood drying and its mechanical strength remains unclear. The aim of this paper was to determine the kinetics of vacuum contact drying of Jack pine (Pinus banksiana) wood boards (dimensions 50 × 100 × 2480 mm3) under various drying temperatures and vacuum pressures at a pilot scale. Drying temperatures and vacuum pressures ranged from 65 to 95 °C and from 169.32 to 507.96 mbar, respectively. Dried samples were subjected to flexural loading to determine mechanical strength. Results indicated that drying time decreased with higher drying temperature and vacuum pressure, where as decreased vacuum pressure increased the temperature of wood samples at a constant drying temperature. Results also indicated that the mechanical properties of dried samples were affected by drying temperature, vacuum pressure, and lumber grade. Mechanical test results were then compared to those for a conventional drying process, revealing that vacuum contact drying do not have a negative impact on the wood mechanical properties.

  8. Measuring barometric pressure with a manifold pressure sensor in a microprocessor based engine control system

    SciTech Connect

    Pauwels, M.A.; Wright, D.O.

    1986-07-15

    A microprocessor based electronic engine control system is described for an internal combustion engine, a method for updating the stored ambient pressure signal by measuring the ambient barometric pressure during engine operation using a manifold pressure sensor. The method consists of: generating timing signals indicating the rotational position of an engine member and including a signal indicating a predetermined rotational position in the rotation of the engine member; generating a pressure signal from the manifold pressure sensor representing the pressure surrounding the sensor in response to the predetermined rotational position; reading the value of ambient barometric pressure stored in the memory of the microprocessor; comparing the value of the barometric pressure stored in the memory of the microprocessor and the value of the pressure signal; increasing the value of the barometric pressure by one unit to generate a new barometric pressure value when the value of the pressure signal is greater than the value of the barometric pressure; comparing the new barometric pressure value with a predetermined fixed constant representing the maximum barometric pressure; and storing in the memory of the microprocessor either the new barometric pressure value if equal to or less than the fixed constant or the value of the maximum barometric pressure if the new barometric pressure value is greater than the fixed constant.

  9. Ambient Noise in an Urbanized Tidal Channel

    NASA Astrophysics Data System (ADS)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  10. Ambient gas effects on the dynamics of laser-produced tin plume expansion

    NASA Astrophysics Data System (ADS)

    Harilal, S. S.; O'Shay, Beau; Tao, Yezheng; Tillack, Mark S.

    2006-04-01

    Controlling the debris from a laser-generated tin plume is one of the prime issues in the development of an extreme ultraviolet lithographic light source. An ambient gas that is transparent to 13.5 nm radiation can be used for controlling highly energetic particles from the tin plume. We employed a partial ambient argon pressure for decelerating various species in the tin plume. The kinetic energy distributions of tin species were analyzed at short and large distances using time and space resolved optical emission spectroscopy and a Faraday cup, respectively. A fast-gated intensified charged coupled device was used for understanding the hydrodynamics of the plume's expansion into argon ambient. Our results indicate that the tin ions can be effectively mitigated with a partial argon pressure ~65 mTorr. Apart from thermalization and deceleration of plume species, the addition of ambient gas leads to other events such as double peak formation in the temporal distributions and ambient plasma formation.

  11. Influence of factors on the drying of cassava in a solar simulator

    SciTech Connect

    Njie, D.N.; Rumsey, T.R.

    1997-03-01

    In tropical countries, sun drying is still the most popular method used for processing root and tuber crops like cassava and yam. Relatively very little has been done on studying the kinetics of sun drying a bed of chips of cassava and similar crops, but this information is invaluable in finding options for reducing drying time and costs, and increasing tonnage produced. This project studied some factors that have an effect on the sun drying rate of cassava chips. The factors were ambient temperature, relative humidity, radiation intensity, air velocity, and loading density. A solar simulation chamber was constructed so that drying could be achieved under controllable conditions similar to those obtained in sun drying. Experiments carried out in the simulator revealed that temperature had the most significant effect on drying rate, followed by air velocity, and radiation intensity. Regression equations were developed relating the drying rate with the factors studied.

  12. 2. INTERIOR OF SAND DRAINING & DRYING BUILDING WITH DRYING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. INTERIOR OF SAND DRAINING & DRYING BUILDING WITH DRYING BINS TO THE RIGHT, LOOKING SOUTHWEST - Mill "C" Complex, Sand Draining & Drying Building, South of Dee Bennet Road, near Illinois River, Ottawa, La Salle County, IL

  13. A Forecast Procedure for Dry Thunderstorms

    NASA Astrophysics Data System (ADS)

    Nauslar, Nicholas J.

    Dry thunderstorm (traditionally less than 2.5 mm or 0.1" of rainfall) forecasting has long been a forecast problem for the western United States. Dry thunderstorms are responsible for starting thousands of wildland fires every year. In the largest lightning outbreaks (or busts in the wildland fire-meteorological community), hundreds of fires may be started in a 24- to 36-hour period. These extreme events put a huge strain on fire suppression efforts. Many of these fires may go unstaffed due to the lack of available fire personnel simply because of the large number of fire starts. Forecasting these events in advance, even just 24-48 hours, could help fire agencies plan resources in preparation of a large outbreak. Fires are much more likely to be controlled during the early stages, and therefore cost much less to suppress. . Due to the seemingly innocuous conditions preceding dry thunderstorm development across the western United States (west of the Rocky Mountains), forecasting dry thunderstorm events can prove challenging and inconsistent. To improve dry thunderstorm forecasting, the National Weather Service (NWS) Reno Weather Forecast Office (WFO) developed WA04 (Wallmann 2004, 2010), a conceptual model of dry thunderstorms that includes the pressure of the dynamic tropopause, jet streak dynamics, equivalent potential temperature, and upper level lapse rates in conjunction with the High Level Total Totals. This thesis supplements WA04 by adding moist isentropic analysis and enhancing the jet streak analysis to help a Dry Thunderstorm Procedure (DTP). Moist isentropic analysis resolves moisture and instability better than analyzing constant pressure maps, thus making it ideal to find the pockets of instability and plumes of moisture that spawn dry thunderstorms. The enhanced jet streak analysis in DTP more completely resolves upward motion and divergence aloft that might not be distinguished using constant pressure maps or traditional quasi-geostrophic theory. The

  14. Method of drying fine coal particles

    SciTech Connect

    Ladt, M.A.

    1984-04-24

    A method of drying wet coal fines smaller than 28 mesh in size employs both a vibrating fluidized bed type dryer and a coal fired burner for supplying hot drying gases to the dryer. A regenerative separator is interposed between the coal fired burner and the fluidized bed type dryer to satisfactorily remove particle matter from the gases without unacceptable pressure losses. Hot gases exhausted from the fluidized bed type dryer are also cleansed to remove particulate coal particles which are used as fuel for the coal fired burner.

  15. Monoclinic deformation of calcite crystals at ambient conditions

    NASA Astrophysics Data System (ADS)

    Przeniosło, R.; Fabrykiewicz, P.; Sosnowska, I.

    2016-09-01

    High resolution synchrotron radiation powder diffraction shows that the average crystal structure of calcite at ambient conditions is described with the trigonal space group R 3 bar c but there is a systematic hkl-dependent Bragg peak broadening. A modelling of this anisotropic peak broadening with the microstrain model from Stephens (1999) [15] is presented. The observed lattice parameters' correlations can be described by assuming a monoclinic-type deformation of calcite crystallites. A quantitative model of this monoclinic deformation observed at ambient conditions is described with the space group C 2 / c . The monoclinic unit cell suggested at ambient conditions is related with the monoclinic unit cell reported in calcite at high pressure (Merrill and Bassett (1975) [10]).

  16. Drying a tuberculosis vaccine without freezing.

    PubMed

    Wong, Yun-Ling; Sampson, Samantha; Germishuizen, Willem Andreas; Goonesekera, Sunali; Caponetti, Giovanni; Sadoff, Jerry; Bloom, Barry R; Edwards, David

    2007-02-20

    With the increasing incidence of tuberculosis and drug resistant disease in developing countries due to HIV/AIDS, there is a need for vaccines that are more effective than the present bacillus Calmette-Guérin (BCG) vaccine. We demonstrate that BCG vaccine can be dried without traditional freezing and maintained with remarkable refrigerated and room-temperature stability for months through spray drying. Studies with a model Mycobacterium (Mycobacterium smegmatis) revealed that by removing salts and cryoprotectant (e.g., glycerol) from bacterial suspensions, the significant osmotic pressures that are normally produced on bacterial membranes through droplet drying can be reduced sufficiently to minimize loss of viability on drying by up to 2 orders of magnitude. By placing the bacteria in a matrix of leucine, high-yield, free-flowing, "vial-fillable" powders of bacteria (including M. smegmatis and M. bovis BCG) can be produced. These powders show relatively minor losses of activity after maintenance at 4 degrees C and 25 degrees C up to and beyond 4 months. Comparisons with lyophilized material prepared both with the same formulation and with a commercial formulation reveal that the spray-dried BCG has better overall viability on drying. PMID:17299039

  17. Freeze drying method

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    1999-01-01

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser.

  18. Freeze drying apparatus

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    2001-01-01

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser.

  19. Dry Skin (Xerosis)

    MedlinePlus

    ... by medical conditions, such as atopic dermatitis and malnutrition. Dry skin develops due to a decrease in ... Diabetes Hypothyroidism Down syndrome Liver or kidney disease Malnutrition HIV/AIDS Lymphoma Signs and Symptoms The most ...

  20. Development of spray dried liposomal dry powder inhaler of Dapsone.

    PubMed

    Chougule, Mahavir; Padhi, Bijay; Misra, Ambikanandan

    2008-01-01

    This investigation was undertaken to evaluate practical feasibility of site specific pulmonary delivery of liposomal encapsulated Dapsone (DS) dry powder inhaler for prolonged drug retention in lungs as an effective alternative in prevention of Pneumocystis carinii pneumonia (PCP) associated with immunocompromised patients. DS encapsulated liposomes were prepared by thin film evaporation technique and resultant liposomal dispersion was passed through high pressure homogenizer. DS nano-liposomes (NLs) were separated by ultra centrifugation and characterized. NLs were dispersed in phosphate buffer saline (PBS) pH 7.4 containing different carriers like lactose, sucrose, and hydrolyzed gelatin, and 15% L-leucine as antiadherent. The resultant dispersion was spray dried and spray dried formulation were characterized to ascertain its performance. In vitro pulmonary deposition was assessed using Andersen Cascade Impactor as per USP. NLs were found to have average size of 137 +/- 15 nm, 95.17 +/- 3.43% drug entrapment, and zeta potential of 0.8314 +/- 0.0827 mV. Hydrolyzed gelatin based formulation was found to have low density, good flowability, particle size of 7.9 +/- 1.1 microm, maximum fine particle fraction (FPF) of 75.6 +/- 1.6%, mean mass aerodynamic diameter (MMAD) 2.2 +/- 0.1 microm, and geometric standard deviation (GSD) 2.3 +/- 0.1. Developed formulations were found to have in vitro prolonged drug release up to 16 h, and obeys Higuchi's Controlled Release model. The investigation provides a practical approach for direct delivery of DS encapsulated in NLs for site specific controlled and prolonged release behavior at the site of action and hence, may play a promising role in prevention of PCP. PMID:18446460

  1. Acoustoconvection Drying of Meat

    NASA Astrophysics Data System (ADS)

    Zhilin, A. A.; Fedorov, A. V.

    2016-03-01

    The dynamics of moisture extraction from meat samples by the acoustoconvection and thermoconvection methods has been investigated. To describe the dynamics of moisture extraction from meat, we propose a simple relaxation model with a relaxation time of 8-10 min in satisfactorily describing experimental data on acoustoconvection drying of meat. For thermoconvection drying the relaxation time is thereby 30 and 45 min for the longitudinal and transverse positions of fibers, respectively.

  2. Orion ECLSS/Suit System - Ambient Pressure Integrated Suit Test

    NASA Technical Reports Server (NTRS)

    Barido, Richard A.

    2011-01-01

    The International Space Station (ISS) Crew Quarters (CQ) is a permanent personal space for crewmembers to sleep, perform personal recreation and communication, as well as provide on-orbit stowage of personal belongings. The CQs provide visual, light, and acoustic isolation for the crewmember. Over a two year period, four CQs were launched to the ISS and currently reside in Node 2. Since their deployment, all CQs have been occupied and continue to be utilized. After four years on-orbit, this paper will review failures that have occurred and the investigations that have resulted in successful on-orbit operations. This paper documents the on-orbit performance and sustaining activities that have been performed to maintain the integrity and utilization of the CQs.

  3. Protein Chips Compatible with MALDI Mass Spectrometry Prepared by Ambient Ion Landing.

    PubMed

    Pompach, Petr; Benada, Oldřich; Rosůlek, Michal; Darebná, Petra; Hausner, Jiří; Růžička, Viktor; Volný, Michael; Novák, Petr

    2016-09-01

    We present a technology that allows the preparation of matrix-assisted laser desorption/ionization (MALDI)-compatible protein chips by ambient ion landing of proteins and successive utilization of the resulting protein chips for the development of bioanalytical assays. These assays are based on the interaction between the immobilized protein and the sampled analyte directly on the protein chip and subsequent in situ analysis by MALDI mass spectrometry. The electrosprayed proteins are immobilized on dry metal and metal oxide surfaces, which are nonreactive under normal conditions. The ion landing of electrosprayed protein molecules is performed under atmospheric pressure by an automated ion landing apparatus that can manufacture protein chips with a predefined array of sample positions or any other geometry of choice. The protein chips prepared by this technique are fully compatible with MALDI ionization because the metal-based substrates are conductive and durable enough to be used directly as MALDI plates. Compared to other materials, the nonreactive surfaces show minimal nonspecific interactions with chemical species in the investigated sample and are thus an ideal substrate for selective protein chips. Three types of protein chips were used in this report to demonstrate the bioanalytical applications of ambient ion landing. The protein chips with immobilized proteolytic enzymes showed the usefulness for fast in situ peptide MALDI sequencing; the lectin-based protein chips showed the ability to enrich glycopeptides from complex mixtures with subsequent MALDI analysis, and the protein chips with immobilized antibodies were used for a novel immunoMALDI workflow that allowed the enrichment of antigens from the serum followed by highly specific MALDI detection. PMID:27478994

  4. Creep of dry clinopyroxene aggregates

    NASA Astrophysics Data System (ADS)

    Bystricky, Misha; Mackwell, Stephen

    2001-01-01

    We have determined diffusional and dislocation creep rheologies for clinopyroxenite Ca1.0Mg0.8Fe0.2Si2O6 under dry conditions by deforming natural and hot-pressed samples at confining pressures of 300-430 MPa and temperatures of 1100°-1250°C with the oxygen fugacity buffered by either nickel-nickel oxide or iron-wüstite powders. The coarse-grained natural Sleaford Bay clinopyroxenite yielded a stress exponent of n = 4.7 ± 0.2 and an activation energy for creep of Q = 760 ± 40 kJ mol-1, consistent with deformation in the dislocation creep regime. The strength of the natural clinopyroxenite is consistent with previous high-temperature measurements of dislocation creep behavior of Sleaford Bay clinopyroxenite by Kirby and Kronenberg [1984] and Boland and Tullis [1986]. Fine-grained clinopyroxenite was prepared from ground powders of the natural clinopyroxenite. Hot-pressed samples were deformed under similar conditions to the natural samples. Mixed-mode deformation behavior was observed, with diffusional creep (n = 1) at lower differential stresses and dislocation creep (with n and Q similar to those of the natural samples) at higher differential stresses. Within the dislocation creep field the predried hot-pressed samples generally yielded creep rates that were about an order of magnitude faster than the natural samples. Thus, even at the highest differential stresses, a component of strain accommodation by grain boundary diffusion was present in the hot-pressed samples. Optical and electron microscope investigations of the deformation microstructures of the natural and hot-pressed samples show evidence for mechanical twinning and activation of dislocation slip systems. When extrapolated to geological conditions expected in the deep crust and upper mantle on Earth and other terrestrial planets, the strength of dry single-phase clinopyroxene aggregates is very high, exceeding that of dry olivine-rich rocks.

  5. Stress and Strain Distributions during Machining of Ti-6Al-4V at Ambient and Cryogenic Temperatures

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Fahim

    Dry and liquid nitrogen pre-cooled Ti-6Al-4V samples were machined at a cutting speed of 43.2 m/min and at low (0.1 mm/rev) to high (0.4 mm/rev) feed rates for understanding the effects of temperature and strain rate on chip microstructures. During cryogenic machining, it was observed that between feed rates of 0.10 and 0.30 mm/rev, a 25% pressure reduction on tool occurred. Smaller number of chips and low tool/chip contact time and temperature were observed (compared to dry machining under ambient conditions). An in-situ set-up that consisted of a microscope and a lathe was constructed and helped to propose a novel serrated chip formation mechanism when microstructures (strain localization) and surface roughness were considered. Dimpled fracture surfaces observed in high-speed-machined chips were formed due to stable crack propagation that was also recorded during in-situ machining. An instability criterion was developed that showed easier strain localization within the 0.10-0.30mm/rev feed rate range.

  6. Evaluation and Comparison of Chemiluminescence and UV Photometric Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O3) that may be p...

  7. Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air, described in EPA regulations at 40 CFR Part 50, Appendix D, is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O

  8. Experimental evidence of thermo-mechanical pressurization of faults during earthquakes

    NASA Astrophysics Data System (ADS)

    Violay, Marie; Di Toro, Giulio; Nielsen, Stefan; Spagnuolo, Elena; Burg, Jean-Pierre

    2015-04-01

    Earthquakes occur while fault strength decreases with increasing slip and slip rate. Thermo-mechanical pressurization of pore fluids induced by frictional heating during seismic slip is one of the possible mechanisms responsible for fault dynamic weakening. However, has not yet been observed in the laboratory. To investigate seismic slip in the presence of pore fluids, 26 friction experiments were conducted at room temperature on hollow cylinders (50/30 mm external/internal diameter) of Etna basalt (1) under room-dry conditions or immersed in water under either (2) drained conditions (constant pore pressure, preventing fluid pressurization), and (3) undrained conditions (constant pore volume). Experiments were performed by spinning two basalt cylinders with the rotary shear machine (SHIVA, INGV Rome) at target slip rates (V) of 3 m/s, displacements (δ) from 4 m to 6 m, normal stress (σn) ranging from 15 to 35 MPa and initial pore fluid pressure (Pf) of 5 MPa.The experimental data are compared with those obtained from carbonate-bearing rocks (Carrara marble). In all the experiments, the coefficient of friction μ decayed exponentially from a peak value (μp = 0.55 ∓ 0.07) at about the initiation of slip towards a steady-state value μss of 0.1 under room-dry conditions, 0.1 under drained conditions and 0.08 under undrained conditions. The shear stress decay was about 75 percent over the first 5 cm of slip, independently of the ambient conditions. However, at a given σneff, δ and V, steady state shear stress was 20 percent lower under undrained than under drained and room dry conditions. Moreover, Pf under undrained conditions increased with displacement following a power law. Conversely, Pf and σn did not vary under drained conditions. After all experiments, a continuous, 100-200 µm thick, layer of glass (Scanning Electron Microscope investigation) separated the rock cylinders, irrespective of the ambient and hydraulic conditions. In summary, the mechanical

  9. Ambient air metallic pollutant study at HAF areas during 2013-2014

    NASA Astrophysics Data System (ADS)

    Fang, Guor-Cheng; Kuo, Yu-Chen; Zhuang, Yuan-Jie

    2015-05-01

    This study characterized diurnal variations of the total suspended particulate (TSP) concentrations, dry deposition flux and dry deposition velocity of metallic elements at Taichung Harbor (Harbor), Gong Ming Junior High School (Airport) and Sha lu Farmland (Farmland) sampling sites in central Taiwan between August, 2013 and July, 2014 in this study. The result indicated that: 1) the ambient air particulate concentrations, dry depositions were displayed as Harbor > Farmland > Airport during the day time sampling period. However, dry deposition velocities were shown as Airport > Harbor > Farmland for this study. 2) The ambient air particulate concentrations, dry depositions were displayed as Airport > Harbor > Farmland during the night time sampling period. However, dry deposition velocities were shown as Farmland > Harbor > Airport for this study. 3) The metallic element Zn has the average highest concentrations at Airport, Harbor and Farmland among all the metallic elements during the day time sampling period in this study. 4) There were significant differences for the metallic elements (Cr, Cu, Zn and Pb) in dry depositions at these three characteristic sampling sites (HAF) for the night time sampling period. The only exception is metallic element Cd. It displayed that there were no significant differences for the metallic element Cd at the Airport and Farmland sampling sites during the night time sampling period. 5) The average highest values for the metallic element Cu in TSP among the three characteristic sampling sites occurred during the fall and winter seasons for this study. As for the dry depositions, the average highest values in dry deposition among the three characteristic sampling sites occurred during the spring and summer seasons for this study. 6) The average highest values for the metallic element Cd in TSP among the three characteristic sampling sites occurred during the spring and summer seasons for this study. As for the dry depositions, the

  10. Ambient acceleration dependence of single-bubble sonoluminescence.

    PubMed

    Thomas, Charles R; Roy, Ronald A; Holt, R Glynn

    2011-11-01

    Much of the research performed to study SBSL deals with the influence of external parameters (e.g., the host water temperature, the ambient pressure, the type and amount of dissolved gas in the liquid, to name a few) on the bubble dynamics and light emission. In the current paper, work carried out to study the influence of another external parameter-ambient acceleration-is described. The experiments described here were performed on the NASA KC-135 which provided both periods of reduced gravity (10(-3) g) and increased gravity (1.8 g) by flying repeated parabolic maneuvers. The resulting measurements are compared with the predictions of a numerical model and can be understood in the context of the changing hydrostatic head pressure and buoyant force acting on the bubble. PMID:22088000

  11. Dry Dock No. 3. View of head of Dry Dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Dry Dock No. 3. View of head of Dry Dock with stair to right of shot. View facing west - U.S. Naval Base, Pearl Harbor, Dry Dock No. 3, On northern shoreline of shipyard, west of Dry Dock Nos. 1 & 2, near the intersection of Avenue G and Sixth Street, Pearl City, Honolulu County, HI

  12. Effect of pressure on electrospray characteristics

    SciTech Connect

    Marginean, Ioan; Page, Jason S.; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2009-11-02

    An experimental study of sub-ambient pressure electrosprays is reported. The pressure domain that affords stable electrospray operation appears to be limited by the vapor pressure of the liquid. The voltage driving the electrospray is shown to have a logarithmic dependence on the pressure. This scaling amends the relationship currently in use to calculate the electric field at the tip of the meniscus of an electrified liquid

  13. Ambient curing fire resistant foams

    NASA Technical Reports Server (NTRS)

    Hamermesh, C. L.; Hogenson, P. A.; Tung, C. Y.; Sawko, P. M.; Riccitiello, S. R.

    1979-01-01

    The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

  14. Influence of the drying medium parameters on drying induced stresses

    SciTech Connect

    Musielak, G.

    2000-03-01

    A thermomechanical model of drying of capillary-porous materials whose material constants depend on moisture content and temperature is presented in the paper. The finite element method is used for the solution of two-dimensional problem of convective drying of a prismatic bar. The moisture distributions, temperature distributions, drying induced strains and stresses for various drying medium parameters are determined. The effect of these parameters on moisture distribution and in particular on drying induced stresses is discussed.

  15. Dry anaerobic methane fermentation

    SciTech Connect

    Jewell, W.J.; Dell'Orto, S.; Fanfoni, K.J.; Fast, S.; Jackson, D.; Kabrick, R.M.

    1981-01-01

    The conversion of relatively dry organics directly to biogas increases the potential of using large amounts of organics such as mixtures of crop residues and animal manures on the farm, crop residues, and urban solid wastes. Besides the use of the dry fermentation process on farms and in centralized facilities, the possibility of using this concept as a residential energy generating system exists. Existing crop residues can be used to generate biogas without major water needs problems. Requirements for an efficient reaction include initial solid content less than 30%, an active methanogenic slurry addition of 40% dry weight (depending on the substrate), and a reaction period of 60-300 days, depending on the reactor temperatures. Further analyses are required to clarify the controlling parameters and the economic feasibility.

  16. Magnetically responsive dry fluids.

    PubMed

    Sousa, Filipa L; Bustamante, Rodney; Millán, Angel; Palacio, Fernando; Trindade, Tito; Silva, Nuno J O

    2013-08-21

    Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid. PMID:23831769

  17. Dynamics of cracking in drying colloidal sheets.

    PubMed

    Sengupta, Rajarshi; Tirumkudulu, Mahesh S

    2016-04-01

    Colloidal dispersions are known to display a fascinating network of cracks on drying. We probe the fracture mechanics of free-standing films of aqueous polymer-particle dispersions. Thin films of the dispersion are cast between a pair of plain steel wires and allowed to dry under ambient conditions. The strain induced on the particle network during drying is relieved by cracking. The stress which causes the films to crack has been calculated by measuring the deflection of the wires. The critical cracking stress varied inversely to the two-thirds' power of the film thickness. We also measure the velocity of the tip of a moving crack. The motion of a crack has been modeled as a competition between the release of the elastic energy stored in the particle network, the increase in surface energy as a result of the growth of a crack, the rate of viscous dissipation of the interstitial fluid and the kinetic energy associated with a moving crack. There is fair agreement between the measured crack velocities and predictions. PMID:26924546

  18. Magnetically responsive dry fluids

    NASA Astrophysics Data System (ADS)

    Sousa, Filipa L.; Bustamante, Rodney; Millán, Angel; Palacio, Fernando; Trindade, Tito; Silva, Nuno J. O.

    2013-07-01

    Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid.Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01784b

  19. Intensity Distribution of Laser Induced Plasma Generated at Different Ambient Gas Preassure

    NASA Astrophysics Data System (ADS)

    Sarmiento, Rafael; Cabanzo, Rafael; Mejia-Ospino, Enrique

    2008-04-01

    In this work, intensity distributions of laser induced plasmas have been measured by emission with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated on the surfaces of steel samples at different pressures of air and argon, in the ranges from l*10-6 to 680 Torr. We compare the features of the intensity spatial and temporal distribution in the two ambient studied here. We observed that the maxima values of intensity are obtained when the pressure is maxima. The features of intensity distribution show a significant change with the ambient and gas pressure. Also, we have measured how change the size of the plasma plume with the pressure at two different ambient.

  20. Compliant Foil Journal Bearing Performance at Alternate Pressures and Temperatures

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J.; Puleo, Bernadette J.

    2008-01-01

    An experimental test program has been conducted to determine the highly loaded performance of current generation gas foil bearings at alternate pressures and temperatures. Typically foil bearing performance has been reported at temperatures relevant to turbomachinery applications but only at an ambient pressure of one atmosphere. This dearth of data at alternate pressures has motivated the current test program. Two facilities were used in the test program, the ambient pressure rig and the high pressure rig. The test program utilized a 35 mm diameter by 27 mm long foil journal bearing having an uncoated Inconel X-750 top foil running against a shaft with a PS304 coated journal. Load capacity tests were conducted at 3, 6, 9, 12, 15, 18, and 21 krpm at temperatures from 25 to 500 C and at pressures from 0.1 to 2.5 atmospheres. Results show an increase in load capacity with increased ambient pressure and a reduction in load capacity with increased ambient temperature. Below one-half atmosphere of ambient pressure a dramatic loss of load capacity is experienced. Additional lightly loaded foil bearing performance in nitrogen at 25 C and up to 48 atmospheres of ambient pressure has also been reported. In the lightly loaded region of operation the power loss increases for increasing pressure at a fixed load. Knowledge of foil bearing performance at operating conditions found within potential machine applications will reduce program development risk of future foil bearing supported turbomachines.

  1. Energy-saving drying and its application

    NASA Astrophysics Data System (ADS)

    Kovbasyuk, V. I.

    2015-09-01

    Superheated steam is efficiently applied as a coolant for the intensification of drying, which is an important component of many up-to-date technologies. However, traditional drying is extremely energy consuming, and many drying apparatus are environmentally unfriendly. Thus, it is important to implement the proposed drying technique using superheated steam under pressure significantly higher than the atmospheric one with subsequent steam transfer for use in a turbine for electric power generation as a compensation of energy costs for drying. This paper includes a brief thermodynamic analysis of such a technique, its environmental advantages, and possible benefits of the use of wet wastes and obtaining high-quality fuels from wet raw materials. A scheme is developed for the turbine protection from impurities that can occur in the steam at drying. Potential advantage of the technique are also the absence of heating surfaces that are in contact with wet media, the absence of the emissions to the atmosphere, and the use of low potential heat for desalination and the purification of water. The new drying technique can play an extremely important part in the implementation in the field of thermal destruction of anthropogenic wastes. In spite of the promotion of waste sorting to obtain valuable secondary raw materials, the main problem of big cities is nonutilizable waste, which makes not less than 85% of the starting quantity of waste. This can only be totally solved by combustion, which even more relates to the sewage sludge utilization. The wastes can be safely and efficiently combusted only provided that they are free of moisture. Combustion temperature optimization makes possible full destruction of dioxins and their toxic analogues.

  2. Synthesis and characterization of nanocrystalline mesoporous zirconia using supercritical drying.

    PubMed

    Tyagi, Beena; Sidhpuria, Kalpesh; Shaik, Basha; Jasra, Raksh Vir

    2006-06-01

    Synthesis of nano-crystalline zirconia aerogel was done by sol-gel technique and supercritical drying using n-propanol solvent at and above supercritical temperature (235-280 degrees C) and pressure (48-52 bar) of n-propanol. Zirconia xerogel samples have also been prepared by conventional thermal drying method to compare with the super critically dried samples. Crystalline phase, crystallite size, surface area, pore volume, and pore size distribution were determined for all the samples in detail to understand the effect of gel drying methods on these properties. Supercritical drying of zirconia gel was observed to give thermally stable, nano-crystalline, tetragonal zirconia aerogels having high specific surface area and porosity with narrow and uniform pore size distribution as compared to thermally dried zirconia. With supercritical drying, zirconia samples show the formation of only mesopores whereas in thermally dried samples, substantial amount of micropores are observed along with mesopores. The samples prepared using supercritical drying yield nano-crystalline zirconia with smaller crystallite size (4-6 nm) as compared to higher crystallite size (13-20 nm) observed with thermally dried zirconia. PMID:17025056

  3. Ambient Noise in an Urbanized Tidal Channel

    NASA Astrophysics Data System (ADS)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  4. DOE hot dry rock program

    SciTech Connect

    Nunz, G.J.

    1980-01-01

    Hydraulic fracturing has been used to create and subsequently to enlarge the first hot dry rock heat-extraction loop at Fenton Hill, New Mexico. Encouraging results prompted the DOE to expand this project into a program of national scope. The elements of that Program and their present status are discussed. Emphasis is given the ongoing Fenton Hill Project where techniques and information developed in the existing research system will soon be used to produce a multiply-fractured engineering system in hotter rock at the same site. Recent results from research loop operation and progress in constructing the engineering system are reported. Although acoustic mapping and system geometry indicate that the primary hydraulic fractures are essentially vertical, relatively low fracturing pressure and absence of a sharp breakdown suggest that at Fenton Hill fracture initiation occurs by reopening of old natural fractures rather than by initiation of new ones. Flow patterns and temperature behavior suggest opening of additional old fractures as the loop is operated. Except where the hot fluid leaves the crack system to enter the production well, flow impedances are very low without either artificial propping or inflation by pressurization.

  5. Combined infrared-vacuum drying of pumpkin slices.

    PubMed

    Ghaboos, Seyyed Hossein Hosseini; Ardabili, Seyed Mahdi Seyedain; Kashaninejad, Mahdi; Asadi, Gholamhassan; Aalami, Mehran

    2016-05-01

    Infrared-vacuum dehydration characteristics of pumpkin (Cucurbita moschata) were evaluated in a combined dryer system. The effects of drying parameters, infrared radiation power (204-272 W), system pressure (5-15 kPa), slice thickness (5 and 7 mm) and time (0-220 min) on the drying kinetics and characteristics of pumpkin slices were investigated. The vacuum pressure, lamp power and slice had significant effect on the drying kinetics and various qualities of the dried pumpkin. Moisture ratios were fitted to 10 different mathematical equations using nonlinear regression analysis. The quadratic equation satisfactorily described the drying behavior of pumpkin slices with the highest r value and the lowest SE values. The effective moisture diffusivity increased with power and ranged between 0.71 and 2.86 × 10(-9) m(2)/s. With increasing in infrared radiation power from 204 to 272 W, β-carotene content of dried pumpkins decreased from 30.04 to 24.55 mg/100 g. The rise in infrared power has a negative effect on the color changes (ΔE). The optimum condition was determined as power, 238W, pressure, 5 kPa and slice thickness, 5mm. These conditions resulted into dried pumpkin slices with maximum B-carotene retention. PMID:27407204

  6. Global Warming and 21st Century Drying

    NASA Technical Reports Server (NTRS)

    Cook, Benjamin I.; Smerdun, Jason E.; Seager, Richard; Coats, Sloan

    2014-01-01

    Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twentyfirst century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman- Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both

  7. Properties of Spray Dried Food and Spray Drying Characteristics

    NASA Astrophysics Data System (ADS)

    Katoh, Fumio

    The following conclusions are obtained, studying properties of spray dried food and drying characteristics. (a) Dried particles are similar to spray droplets in size distribution (y=2.5), and particle count distribution is arranged as (dn/dx = ae-bx). (b) The ratio of the particle diameters before and after drying is calculated with moisture before and after drying, and porosity is given as (εp = ww4). (c) The standard drying method is presented to evaluate accurately drying problems at a certain standard. (d) Equilibrium moisture at 20 up to 100°C are summarized in terms of adsorption potential. (e) It makes clear that calulation based on the theory of residence time and drying time represents well complex spray drying characteristics.

  8. Drying drops of blood

    NASA Astrophysics Data System (ADS)

    Brutin, David; Sobac, Benjamin; Loquet, Boris; Sampol, José.

    2010-11-01

    The drying of a drop of human blood is fascinating by the complexity of the physical mechanisms that occur as well as the beauty of the phenomenon which has never been previously evidenced in the literature. The final stage of full blood evaporation reveals for a healthy person the same regular pattern with a good reproducibility. Other tests on anemia and hyperlipidemic persons were performed and presented different patterns. By means of digital camera, the influence of the motion of red blood cells (RBCs) which represent about 50% of the blood volume, is revealed as well as its consequences on the final stages of drying. The mechanisms which lead to the final pattern of dried blood drops are presented and explained on the basis of fluid and solid mechanics in conjunction with the principles of hematology. Our group is the first to evidence that the specific regular patterns characteristic of a healthy individual do not appear in a dried drop of blood from a person with blood disease. Blood is a complex colloidal suspension for which the flow motion is clearly non-Newtonian. When drops of blood evaporate, all the colloids are carried by the flow motion inside the drop and interact.

  9. Hydrogen confinement in carbon nanopores: extreme densification at ambient temperature.

    PubMed

    Gallego, Nidia C; He, Lilin; Saha, Dipendu; Contescu, Cristian I; Melnichenko, Yuri B

    2011-09-01

    In-situ small-angle neutron scattering studies of H(2) confined in small pores of polyfurfuryl alcohol-derived activated carbon at room temperature have provided for the first time its phase behavior in equilibrium with external H(2) at pressures up to 200 bar. The data were used to evaluate the density of the adsorbed fluid, which appears to be a function of both pore size and pressure and is comparable to the density of liquid H(2) in narrow nanopores at ∼200 bar. The surface-molecule interactions responsible for densification of H(2) within the pores create internal pressures that exceed the external gas pressure by a factor of up to ∼50, confirming the benefits of adsorptive storage over compressive storage. These results can be used to guide the development of new carbon adsorbents tailored for maximum H(2) storage capacities at near-ambient temperatures. PMID:21819066

  10. Hydrogen Confinement in Carbon Nanopores: Extreme Densification at Ambient Temperature

    SciTech Connect

    Gallego, Nidia C; He, Lilin; Saha, Dipendu; Contescu, Cristian I; Melnichenko, Yuri B

    2011-01-01

    In-situ small angle neutron scattering (SANS) studies of hydrogen confined in small pores of polyfurfuryl alcohol-derived activated carbon (PFAC) at room-temperature provided for the first time its phase behavior in equilibrium with external H2 at pressures up to 200 bar. The data was used to evaluate the density of the adsorbed fluid, which appears to be a function of both pore size and pressure, and approaches the liquid hydrogen density in narrow nanopores at 200 bar. The surface-molecule interactions responsible for densification of hydrogen within the pores create internal pressures which exceed by a factor of up to ~ 60 the external gas pressures, confirming the benefits of adsorptive over compressive storage. These results can be utilized to guide the development of new carbon adsorbents tailored for maximum hydrogen storage capacities at near ambient temperatures.

  11. Infrared Drying Parameter Optimization

    NASA Astrophysics Data System (ADS)

    Jackson, Matthew R.

    In recent years, much research has been done to explore direct printing methods, such as screen and inkjet printing, as alternatives to the traditional lithographic process. The primary motivation is reduction of the material costs associated with producing common electronic devices. Much of this research has focused on developing inkjet or screen paste formulations that can be printed on a variety of substrates, and which have similar conductivity performance to the materials currently used in the manufacturing of circuit boards and other electronic devices. Very little research has been done to develop a process that would use direct printing methods to manufacture electronic devices in high volumes. This study focuses on developing and optimizing a drying process for conductive copper ink in a high volume manufacturing setting. Using an infrared (IR) dryer, it was determined that conductive copper prints could be dried in seconds or minutes as opposed to tens of minutes or hours that it would take with other drying devices, such as a vacuum oven. In addition, this study also identifies significant parameters that can affect the conductivity of IR dried prints. Using designed experiments and statistical analysis; the dryer parameters were optimized to produce the best conductivity performance for a specific ink formulation and substrate combination. It was determined that for an ethylene glycol, butanol, 1-methoxy 2- propanol ink formulation printed on Kapton, the optimal drying parameters consisted of a dryer height of 4 inches, a temperature setting between 190 - 200°C, and a dry time of 50-65 seconds depending on the printed film thickness as determined by the number of print passes. It is important to note that these parameters are optimized specifically for the ink formulation and substrate used in this study. There is still much research that needs to be done into optimizing the IR dryer for different ink substrate combinations, as well as developing a

  12. High gas pressure effects on yeast.

    PubMed

    Espinasse, V; Perrier-Cornet, J-M; Marecat, A; Gervais, P

    2008-11-01

    Dried microorganisms are particularly resistant to high hydrostatic pressure effects. However, exposure to high pressures of nitrogen proved to be effective in inactivating dried yeasts. In this study, we tried to elucidate this mechanism on Saccharomyces cerevisiae. High-pressure treatments were performed using different inert gases at 150 MPa and 25 degrees C with holding time values up to 12 months. The influence of cell hydration was also investigated. For fully hydrated cells, pressurized gases had little specific effect: cell inactivation was mainly due to compression effects. However, dried cells were sensitive to high pressure of gases. In this latter case, two inactivation kinetics were observed. For holding time up to 1 h, the inactivation rate increased to 4 log and was linked to a loss of membrane integrity and the presence of damage on the cell wall. In such case cell inactivation would be due to gas sorption and desorption phenomena which would rupture dried cells during a fast pressure release. Gas sorption would occur in cell lipid phases. For longer holding times, the inactivation rate increased more slightly due to compression effects and/or to a slower gas sorption. Water therefore played a key role in cell sensitivity to fast gas pressure release. Two hypotheses were proposed to explain this phenomenon: the rigidity of vitrified dried cells and the presence of glassy solid phases which would favor intracellular gas expansion. Our results showed that dried microorganisms can be ruptured and inactivated by a fast pressure release with gases. PMID:18814287

  13. Characterization and Application of Microplasma Devices for Ambient Mass Spectrometry and Surface Analysis

    NASA Astrophysics Data System (ADS)

    Symonds, Joshua; Gann, Reuben; Fernández, Facundo; Orlando, Thomas

    2012-10-01

    In ambient mass spectrometry, ionization sources with broad chemical compatibility, low fragmentation, and high reliability are one of the keys necessary to enable effective and rapid analysis of unknown samples. One such approach, employing a variety of ambient-pressure microplasma discharges, has demonstrated itself to be a promising technique with a variety of successful applications and results. This class of devices holds a competitive edge over alternative ambient ionization methods when cost and portability are a concern: microplasmas typically require only modest electrical power and minimal gas flows to operate. We have developed our own such devices and methods, and look more closely into the physical nature of what makes particular designs successful. We focus on the development of these devices to perform mass spectrometry imaging in tandem with optical microscope imaging of samples at ambient pressure. Additionally, we investigate the use of microplasma devices for production of VUV photons, another highly effective ionization source.

  14. Structural lubricity under ambient conditions

    PubMed Central

    Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z.

    2016-01-01

    Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000–130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold–graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions. PMID:27350035

  15. Dry-season ultraviolet radiation primes litter for wet season decomposition in a Mediterranean grassland

    NASA Astrophysics Data System (ADS)

    Baker, N. R.; Allison, S. D.

    2013-12-01

    -lignin, ambient UV samples was 85.9 μmol/hr*g during the wet season, compared to 44.1 μmol/hr*g in attenuated UV samples (p < 0.028). This increased potential cellulase activity under attenuated UV may indicate that dry season photodegradation primes low-lignin litter for wet season decomposition, reducing the selective pressure for microbial decomposers to invest in costly extracellular enzyme production. Similarly, the reduced potential oxidative enzyme activity in high-lignin samples exposed to attenuated UV may indicate that photodegradation is necessary to facilitate the breakdown of more complex compounds such as lignin by microbial decomposers. We conclude that while abiotic factors such as photodegradation can have a significant effect on the mechanisms of plant matter decomposition in semiarid ecosystems, these effects are not only restricted to the dry season and may also facilitate wet season decomposition.

  16. Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyser (TEGA)

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Boynton, W. V.; Ming, D. W.; Quadlander, G. A.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

    2000-01-01

    We are conducting DSC/EGA experiments at Mars ambient temperature and pressure using the TEGA engineering model. These tests illustrate the outstanding capabilities of a TEGA-like instrument on the surface of Mars.

  17. Development and Evaluation of Solar Tunnel Dryer for Commercial Fish Drying

    NASA Astrophysics Data System (ADS)

    Mohod, A. G.; Khandetod, Y. P.; Shrirame, H. Y.

    2014-01-01

    The local practice of drying fish in open sun drying poses problems such as high moisture content, uncontrolled drying and contamination. These problems can be avoided by proper use of improved methods such as the solar tunnel dryer, which results in faster drying of fish. The semi cylindrical walk-in type natural convection solar tunnel dryer, having drying area of 37.5 m2 was developed and evaluated for the drying of fish products in comparison with the conventional method of open sun drying. The experiments were conducted without fish and with fish to evaluate the performance of solar tunnel dryer. The average rise in temperature inside the solar tunnel dryer was found to be 11.24 °C and 18.29 °C over the ambient temperature during no load test in winter and summer respectively. The average 28 % saving in time was observed for selected fish drying using solar tunnel dryer over open sun drying method with average drying efficiency of 19 %. The economics was calculated for drying of prawns ( Parapaeneopsis stylifera) by solar tunnel dryer and open sun drying system on the basis of business as a whole. The economics of the solar tunnel dryer is presented in term of Net present worth, Benefit-Cost Ratio, Payback period, Profitability index and Internal rate of return. The pay back period for solar tunnel dryer was found to be 2.84 years.

  18. Ambient resonance of rock arches

    NASA Astrophysics Data System (ADS)

    Starr, Alison Margaret

    Resonant frequencies of structural elements are related to fundamental material properties of mass and stiffness, and monitoring over time can thus serve as an indirect indictor of internal mechanical change. Until now, however, this methodology has not been applied to natural rock structures such as arches and towers. We evaluated the resonance characteristics of four rock arches in southeastern Utah, combining in-situ ambient vibration measurements with numerical modal analysis. At each location, we measured the spectral and polarization attributes of ambient vibrations using up to two broadband seismometers. Ambient vibration spectra measured on the arches showed clear peaks at distinct frequencies (typically between 1-10 Hz), which we interpret as resonant frequencies, as opposed to the relatively flat spectra recorded on nearby bedrock. Polarization analysis helped us identify the orientations of vibration and explore resonant mode shapes. We then verified the measured resonant frequencies through 3D finite-element numerical modal analysis, and in most cases we were able to match the fundamental along with several higher-order modes. Repeat occupation and short-term continuous ambient vibration monitoring were aimed at assessing daily and seasonal changes in resonant frequencies, which in turn may provide evidence of internal mechanical change; Mesa Arch in Canyonlands National Park served as the main focus for our repeat measurements. Results revealed that minor, reversible changes in resonant frequencies can be created by thermal effects, i.e., changes in bulk material stiffness as the arch expands and contracts on daily and seasonal time scales. No irreversible change in the resonant frequency of Mesa Arch was detected over the period of this study. Our research provides the first step towards monitoring the long-term structural health of natural rock arches as they change through time or in the wake of a damaging event. We have shown that the resonance

  19. Effect of ambient temperature and humidity on emissions of an idling gas turbine

    NASA Technical Reports Server (NTRS)

    Kauffman, C. W.

    1977-01-01

    The effects of inlet pressure, temperature, and humidity on the oxides of nitrogen produced by an engine operating at takeoff power setting were investigated and numerous correction factors were formulated. The effect of ambient relative humidity on gas turbine idle emissions was ascertained. Experimentally, a nonvitiating combustor rig was employed to simulate changing combustor inlet conditions as generated by changing ambient conditions. Emissions measurements were made at the combustor exit. For carbon monoxide, a reaction kinetic scheme was applied within each zone of the combustor where initial species concentrations reflected not only local combustor characteristics but also changing ambient conditions.

  20. Computer tracks pigs to speed gas drying

    SciTech Connect

    Ashburner, M.

    1984-04-01

    Advanced pipeline drying techniques have been used to commission a 27-mile, 30-in. undersea natural gas pipeline in Malaysia's Luconia field. After first sending a series of torpedo-shape foam and rubber cup pigs through the line to force out some 4 million gal of seawater, a new technique combines a vacuum drying process with a sophisticated computer program to keep track of the pigs, thereby enabling the job to be completed in just 4 weeks. The program simulates pipeline conditions at the pig air/water interface under constant propelling flow conditions. The computer produces a pressure profile, calculates the overall time along the pipe, and then uses the resultant time-pressure model to interpret the actual results from the flow measurement-pressure plot for the pig's progress. The program was developed primarily to forecast the effects of changes in propelling capacity in deepwater conditions to ensure that adequate pressure capacity was available to maintain pig speeds above minimum self-cleaning velocities.