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Sample records for reduced pressurized evaporator

  1. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates

    NASA Astrophysics Data System (ADS)

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-03-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges.

  2. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates

    PubMed Central

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-01-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges. PMID:26928329

  3. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates.

    PubMed

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-01-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges. PMID:26928329

  4. Turkish Undergraduates' Misconceptions of Evaporation, Evaporation Rate, and Vapour Pressure

    ERIC Educational Resources Information Center

    Canpolat, Nurtac

    2006-01-01

    This study focused on students' misconceptions related to evaporation, evaporation rate, and vapour pressure. Open-ended diagnostic questions were used with 107 undergraduates in the Primary Science Teacher Training Department in a state university in Turkey. In addition, 14 students from that sample were interviewed to clarify their written…

  5. Negative pressures in nanoporous membranes for thin film evaporation

    NASA Astrophysics Data System (ADS)

    Xiao, Rong; Maroo, Shalabh C.; Wang, Evelyn N.

    2013-03-01

    We present a nanoporous membrane-based approach, which decouples the capillary pressure from the viscous resistance, to achieve high driving pressures and efficient liquid delivery for thin film evaporation. By using alumina membranes with ≈150 nm pore diameters, absolute liquid pressures as low as -300 kPa were achieved using isopropyl alcohol, while dissipating maximum interfacial heat fluxes of ≈96 W/cm2. Design guidelines are provided to achieve higher interfacial heat fluxes with reduced membrane thicknesses. This work shows a promising approach to address thermal management needs for next generation electronic devices.

  6. Pressure reducing regulator

    DOEpatents

    Whitehead, John C.; Dilgard, Lemoyne W.

    1995-01-01

    A pressure reducing regulator that controls its downstream or outlet pressure to a fixed fraction of its upstream or inlet pressure. The regulator includes a housing which may be of a titanium alloy, within which is located a seal or gasket at the outlet end which may be made of annealed copper, a rod, and piston, each of which may be made of high density graphite. The regulator is insensitive to temperature by virtue of being without a spring or gas sealed behind a diaphragm, and provides a reference for a system in which it is being used. The rod and piston of the regulator are constructed, for example, to have a 1/20 ratio such that when the downstream pressure is less than 1/20 of the upstream pressure the regulator opens and when the downstream pressure exceeds 1/20 of the upstream pressure the regulator closes.

  7. Pressure reducing regulator

    DOEpatents

    Whitehead, J.C.; Dilgard, L.W.

    1995-10-10

    A pressure reducing regulator that controls its downstream or outlet pressure to a fixed fraction of its upstream or inlet pressure is disclosed. The regulator includes a housing which may be of a titanium alloy, within which is located a seal or gasket at the outlet end which may be made of annealed copper, a rod, and piston, each of which may be made of high density graphite. The regulator is insensitive to temperature by virtue of being without a spring or gas sealed behind a diaphragm, and provides a reference for a system in which it is being used. The rod and piston of the regulator are constructed, for example, to have a 1/20 ratio such that when the downstream pressure is less than 1/20 of the upstream pressure the regulator opens and when the downstream pressure exceeds 1/20 of the upstream pressure the regulator closes. 10 figs.

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

    NASA Technical Reports Server (NTRS)

    Gardos, M. N.

    1973-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1995-02-01

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

  10. Wind increases "evaporative demand" but reduces plant water requirements

    NASA Astrophysics Data System (ADS)

    Schymanski, S. J.; Or, D.

    2015-12-01

    Transpiration is commonly conceptualised as a fraction of some potential rate, determined by stomatal or canopy resistance. Therefore, so-called "atmospheric evaporative demand" or "potential evaporation" is generally used alongside with precipitation and soil moisture to characterise the environmental conditions that affect plant water use. An increase in potential evaporation (e.g. due to climate change) is generally believed to cause increased transpiration and/or vegetation water stress, aggravating drought effects. In the present study, we investigated the question whether potential evaporation constitutes a meaningful reference for transpiration and compared sensitivity of potential evaporation and leaf transpiration to atmospheric forcing. Based on modelling results and supporting experimental evidence, we conclude that stomatal resistance cannot be parameterised as a factor relating transpiration to potential evaporation, as the ratio between transpiration and potential evaporation not only varies with stomatal resistance, but also with wind speed, air temperature, irradiance and relative humidity. Furthermore, the effect of wind speed in particular implies increase in potential evaporation, which is commonly interpreted as increased "water stress", but at the same time can reduce leaf transpiration, implying a decrease in water demand at the leaf scale. In fact, in a range of field measurements, we found that water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, enabling plants to conserve water during photosynthesis. We estimate that the observed global decrease in terrestrial near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric carbon dioxide concentrations. We conclude that trends in wind speed and atmospheric carbon dioxide concentrations have to be considered explicitly for the estimation of drought effects on

  11. Pressure Reducer for Coal Gasifiers

    NASA Technical Reports Server (NTRS)

    Kendall, James M., Sr.

    1983-01-01

    Quasi-porous-plug pressure reducer is designed for gases containing abrasive particles. Gas used to generate high pressure steam to drive electric power generators. In giving up heat to steam, gas drops in temperature. Device used for coal gasification plants.

  12. Correlation of chemical evaporation rate with vapor pressure.

    PubMed

    Mackay, Donald; van Wesenbeeck, Ian

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Kinetics of Evaporation of Pinned Nanofluid Volatile Droplets at Subatmospheric Pressures.

    PubMed

    Orejon, Daniel; Shanahan, Martin E R; Takata, Yasuyuki; Sefiane, Khellil

    2016-06-14

    We examine the effects of nanoparticle addition at low concentration on the evaporation kinetics of droplets in the constant radius mode. The evaporative behavior of deionized water and Al2O3 nanoparticle laden water on an aluminum substrate was observed at atmospheric and at different subatmospheric pressures. The two fluids exhibit the same evaporative behavior, independent of the droplet volume or the subatmospheric pressure. Moreover, the linear relationship between evaporation rate and droplet radius, initially proposed by Picknett and Bexon nearly four decades ago for droplets evaporating in the constant radius mode, is satisfied for both liquids. In addition, we have established a unified correlation solely function of fluid properties that extends this relationship to any subatmospheric pressure and fluid tested. We conclude that the addition of a small quantity of nanoparticles to the base fluid does not modify the kinetics of evaporation for pinned volatile droplets. PMID:27218303

  15. Study on a new type of jet pressurization evaporation expansion apparatus

    NASA Astrophysics Data System (ADS)

    Chen, Boyi; Zhang, Mingxin; Yang, Li

    2001-04-01

    The volume expansion of the stuff (e. g. tobacco stem) is of great importance to an increase in the product quality and a decrease in the production cost. This paper puts forward the basic configuration and the expansion mechanism of a new type of jet pressurization evaporation expansion apparatus. By the thermodynamic calculation of the apparatus, we give variations in steam pressure on various cross sections of the flow system for the apparatus, manufacture a sample machine, and finish run tests of the machine. The test results show that the apparatus may make the relative increase in fill value of tobacco stem higher than 75%, and may cause the steam consumption required in the expansion process of each kilogram stem to reduced about 40% compared with conventional expansion apparatus. Additionally, the configuration of the apparatus is simple and small, its cost of manufacture is very low, and both its operation and maintenance are extremely convenient.

  16. Development of methanol evaporation plate to reduce methanol crossover in a direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Zhang, Ruiming

    This research focuses on methanol crossover reduction in direct methanol fuel cells (DMFC) through separating the methanol vapor from its liquid phase and feeding the vapor passively at low temperature range. Membrane electrode assemblies (MEAs) were fabricated by using commercial available membrane with different thickness at different anode catalyst loading levels, and tested under the operating conditions below 100°C in cell temperature and cathode exit open to ambient pressure. Liquid methanol transport from the anode through the membrane into cathode ("methanol crossover") is identified as one of the major efficiency losses in a DMFC. It is known that the methanol crossover rate in the vapor phase is much lower than in liquid phase. Vapor feed can be achieved by heating the liquid methanol to elevated temperatures (>100°C), but other issues limit the performance of the cell when operating above 100°C. High temperature membranes and much more active cathode catalyst structures are required, and a complex temperature control system must be employed. However, methanol vapor feed can also occur at a lower temperature range (<100°C) by separating its vapor from the liquid phase by evaporation through a porous body. The methanol crossover with this vapor feed mode is lower compared with the direct liquid methanol feed. A new method of using a methanol evaporation plate (MEP) to separate the vapor from its liquid phase to reduce the liquid methanol crossover at low temperature range is developed. A MEP plays the roles of liquid/vapor methanol phase separation and evaporation in a DMFC. The goal of this study is to develop a MEP with the proper properties to achieve high methanol phase separation efficiency and fast methanol evaporation rate over a wide range of temperature, i.e., from room temperature up to near boiling temperature (100°C). MEP materials were selected and characterized. MEPs made from three different types were tested extensively with different

  17. An Experimental Study of Pressure Oscillation in a Capillary Pumped Loop with Multiple Evaporators and Condensers

    NASA Technical Reports Server (NTRS)

    Ku, Jen-Tung; Hoang, Triem T.

    1998-01-01

    The heat transport capability of a capillary pumped loop (CPL) is limited by the pressure drop that its evaporator wick can sustain. The pressure drop in a CPL is not constant even under seemingly steady operation, but rather exhibits an oscillatory behavior. A hydrodynamic theory based on a mass-spring-dashpot model was previously developed to predict the pressure oscillation in a CPL with a single evaporator and a single condenser. The theory states that the pressure oscillation is a function of physical dimensions of the CPL components and operating conditions. Experimental data agreed very well with theoretical predictions. The hydrodynamic stability theory has recently been extended to predict the pressure oscillations in CPLs with multiple evaporators and multiple condensers. Concurrently, an experimental study was conducted to verify the theory and to investigate the effects of various parameters on the pressure oscillation. Four evaporators with different wick properties were tested using a test loop containing two condenser plates. The test loop allowed the four evaporators to be tested in a single-pump, two-pump or four-pump configuration, and the two condenser plates to be plumbed either in parallel or in series. Test conditions included varying the power input, the reservoir set point temperature, the condenser sink temperature, and the flow resistance between the reservoir and the loop. Experimental results agreed well with theoretical predictions.

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

    PubMed

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

    2008-04-01

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

  19. Water evaporation rates across hydrophobic acid monolayers at equilibrium spreading pressure.

    PubMed

    Tsuji, Minami; Nakahara, Hiromichi; Moroi, Yoshikiyo; Shibata, Osamu

    2008-02-15

    The effect of alkanoic acid [CH(3)(CH(2))(n-2)COOH; HCn] and perfluoroalkanoic acid [CF(3)(CF(2))(n-2)COOH; FCn] monolayers on the water evaporation rate was investigated by thermogravimetry tracing the decrease in amount of water with time. The evaporation rate from the surface covered by a monolayer was measured as a function of temperature and hydrophobic chain length of the acids, where the monolayer was under an equilibrium spreading pressure. From thermal behavior of the crystallized acids, their solid states are C-type in crystalline state over the temperature range from 298.2 to 323.2 K. The dry air was flowed through a furnace tube of a thermogravimetry apparatus at the flow rate of 80 mL min(-1), where the evaporation rate becomes almost constant irrespective of the flow rate. The temperature dependence of the evaporation rate was analyzed kinetically to evaluate the activation energy and thermodynamics values for the activated complex, which demonstrated that these values were almost the same for both alkanoic acids and perfluoroalkanoic acids, although the effect of perfluoroalkanoic acids on the evaporation rate was smaller than that of corresponding hydrogenated fatty acids. The difference in the evaporation rate between FCn and HCn was examined by atomic force microscopy (AFM), Brewster angle microscopy (BAM), surface potential (DeltaV) at equilibrium spreading pressure, and Langmuir curve (pi-A isotherm), and their results were consistent and supported the difference. PMID:18048050

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  1. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure. Research Report

    ERIC Educational Resources Information Center

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul

    2004-01-01

    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  2. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure

    ERIC Educational Resources Information Center

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul

    2004-01-01

    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  3. Reduced pressure quenching oil and distortion

    SciTech Connect

    Asada, S.; Ogino, M.

    1996-12-31

    Cooling process observed in a quenching oil`s cooling curve determination by JIS silver probe method, has been divided into three stages, vapor blanket stage, boiling stage and convection stage. Under reduced pressure vaporization is accelerated and extend the vapor blanket stage which shift the position of boiling stage the fastest of cooling speed among the cooling process toward low temperature side. Taking advantage of this behavior in quenching under reduced pressure, it is possible to improve quench hardenability by controlling reduced pressure. Vapor pressure of quenching oil increases under very high vacuum and accelerates vapor blanket formation and covers the material with more vapor blanket, resulting in reduction of cooling speed. Excessive vapor blanket covering the material will lead to partially uneven quenching of the treated material caused by uneven conditions by partial decomposition. Making vapor blanket distribution more even and to optimize uniform coating condition enables to prevent heat treatment distortion caused by uneven quenching conditions.

  4. Feasibility Study – Using a Solar Evaporator to Reduce the Metalworking Fluid (MWF) Waste Stream

    SciTech Connect

    Lazarus, Lloyd

    2008-12-03

    A solar evaporator was designed, built, and operated to reduce the water-based metalworking fluid waste stream. The evaporator was setup in Waste Management’s barrel lot inside one of the confinement areas. The unit processed three batches of waste fluid during the prototype testing. Initial tests removed 13% of the fluid waste stream. Subsequent modifications to the collector improved the rate to almost 20% per week. Evaluation of the risk during operation showed that even a small spill when associated with precipitation, and the unit placement within a confinement area, gave it the potential to contaminate more fluid that what it could save.

  5. Generation of Charged Nanoparticles During Thermal Evaporation of Silver at Atmospheric Pressure.

    PubMed

    Yang, S M; Kim, S R N; Youn, W K; Kim, C S; Kim, D S; Yi, K W; Hwang, N M

    2015-11-01

    The generation of charged silver nanoparticles in the gas phase during thermal evaporation of silver at atmospheric pressure was confirmed by the nano-differential mobility analyzer (DMA). Effects of the evaporation temperature, the nitrogen gas flow rate and the amount of silver to be evaporated on the size distribution of charged nanoparticles (CNPs) were examined. Both positively and negatively-charged nanoparticles were generated under all processing conditions adopted in this study. The deposition behavior of CNPs was affected by the gas flow, which is affected by the temperature gradient in the reactor and by the applied electric bias. The electric bias, which not only enhanced the film growth rate but also produced a much denser film surface, turned out to be an important process parameter under the condition where an appreciable amount of CNPs is generated. PMID:26726527

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  7. Theoretical and Experimental Investigations on Droplet Evaporation and Droplet Ignition at High Pressures

    NASA Technical Reports Server (NTRS)

    Ristau, R.; Nagel, U.; Iglseder, H.; Koenig, J.; Rath, H. J.; Normura, H.; Kono, M.; Tanabe, M.; Sato, J.

    1993-01-01

    The evaporation of fuel droplets under high ambient pressure and temperature in normal gravity and microgravity has been investigated experimentally. For subcritical ambient conditions, droplet evaporation after a heat-up period follows the d(exp 2)-law. For all data the evaporation constant increases as the ambient temperature increases. At identical ambient conditions the evaporation constant under microgravity is smaller compared to normal gravity. This effect can first be observed at 1 bar and increases with ambient pressure. Preliminary experiments on ignition delay for self-igniting fuel droplets have been performed. Above a 1 s delay time, at identical ambient conditions, significant differences in the results of the normal and microgravity data are observed. Self-ignition occurs within different temperature ranges due to the influence of gravity. The time dependent behavior of the droplet is examined theoretically. In the calculations two different approaches for the gas phase are applied. In the first approach the conditions at the interface are given using a quasi steady theory approximation. The second approach uses a set of time dependent governing equations for the gas phase which are then evaluated. In comparison, the second model shows a better agreement with the drop tower experiments. In both cases a time dependent gasification rate is observed.

  8. 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.

  9. [Safety of oxygen-pressure-reducing valves].

    PubMed

    Dauphin, A

    1999-11-01

    When a gas cylinder valve is opened slowly, as required, the associated pressure reducing valve works properly and gas expansion decreases the temperature of the device proportionally to the delivered gas flow. Conversely, when the valve is opened rapidly, the pressure in the high pressure chamber grows suddenly from 0 to 200 bars in the case of a full O2-cylinder, if no flow is required at the valve outlet. This adiabatic compression in a small space generates a peak of high temperature. In the presence of combustible foreign debris and O2, ignition can occur. When the melting point of the metallic component is reached the device bursts and those in the vicinity are at risk of burns or death from inhalation of melten metallic debris. As several of such critical incidents occurred with O2-pressure-reducing valves whose high pressure chambers were made of aluminium, the French medical devices agency has enacted a regulation prohibiting their use. PMID:10615550

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  11. Heat transfer and convective structure of evaporating films under pressure-modulated conditions

    NASA Astrophysics Data System (ADS)

    Gonzalez-Pons, Juan Carlos; Hermanson, James; Allen, Jeffrey

    2014-11-01

    The interfacial stability, convective structure, and evaporation rate of upward-facing, thin liquid films were studied experimentally. Dichloromethane films approximately 2 mm thick were subjected to impulsive, time-varying superheating. The films resided on a temperature controlled, copper surface in a closed, initially degassed test chamber. Superheating was achieved by modulating the pressure of the saturated pure vapor in the test chamber. The dynamic film thickness was measured at multiple points using ultrasound, and the convective structure information was visualized by schlieren imaging. Two distinct raises in heat transfer rate under unsteady conditions were observed. The first transition appears to be associated with conduction within the film only; the second, to a change in the pattern of convection within the film. Different pressure-modulation cycles were studied to capture one or both of the observed rises in heat transfer. The total film thickness change over multiple cycles, as indicated by ultrasound, allowed determination of the total heat rejected into the evaporating films. Results suggest that there are cycle combinations that lead to an elevation in the average rate of heat transfer compared to films undergoing quasi-steady evaporation. This work was sponsored by the National Aeronautics and Space Administration under Cooperative Agreement NNX09AL02G.

  12. Reduced Volume Prototype Spacesuit Water Membrane Evaporator; A Next-Generation Evaporative Cooling System for the Advanced Extravehicular Mobility Unit Portable Life Support System

    NASA Technical Reports Server (NTRS)

    Makinen, Janice V.; Anchondo, Ian; Bue, Grant C.; Campbell, Colin; Colunga, Aaron

    2013-01-01

    Development of the Advanced Extravehicular Mobility Unit (AEMU) portable life support subsystem (PLSS) is currently under way at NASA Johnson Space Center. The AEMU PLSS features a new evaporative cooling system, the reduced volume prototype (RVP) spacesuit water membrane evaporator (SWME). The RVP SWME is the third generation of hollow fiber SWME hardware. Like its predecessors, RVP SWME provides nominal crew member and electronics cooling by flowing water through porous hollow fibers. Water vapor escapes through the hollow fiber pores, thereby cooling the liquid water that remains inside of the fibers. This cooled water is then recirculated to remove heat from the crew member and PLSS electronics. Major design improvements, including a 36% reduction in volume, reduced weight, and a more flight-like backpressure valve, facilitate the packaging of RVP SWME in the AEMU PLSS envelope. The development of these evaporative cooling systems will contribute to a more robust and comprehensive AEMU PLSS.

  13. Biodegradation of artificial monolayers applied to water storages to reduce evaporative loss.

    PubMed

    Pittaway, P; Herzig, M; Stuckey, N; Larsen, K

    2015-01-01

    Repeat applications of an artificial monolayer to the interfacial boundary layer of large agricultural water storages during periods of high evaporative demand remains the most commercially feasible water conservation strategy. However, the interfacial boundary layer (or microlayer) is ecologically distinct from subsurface water, and repeat monolayer applications may adversely affect microlayer processes. In this study, the natural cleansing mechanisms operating within the microlayer were investigated to compare the biodegradability of two fatty alcohol (C16OH and C18OH) and one glycol ether (C18E1) monolayer compound. The C16OH and C18OH compounds were more susceptible to microbial degradation, but the C18E1 compound was most susceptible to indirect photodegradation. On clean water the surface pressure and evaporation reduction achieved with a compressed C18E1 monolayer was superior to the C18OH monolayer, but on brown water the surface pressure dropped rapidly. These results suggest artificial monolayers are readily degraded by the synergy between photo and microbial degradation. The residence time of C18OH and C18E1 monolayers on clear water is sufficient for cost-effective water conservation. However, the susceptibility of C18E1 to photodegradation indicates the application of this monolayer to brown water may not be cost-effective. PMID:26465303

  14. Optimization of the preparation of loperamide-loaded poly (L-lactide) nanoparticles by high pressure emulsification-solvent evaporation.

    PubMed

    Ueda, M; Kreuter, J

    1997-01-01

    The entrapment of loperamide hydrochloride (LPM) in biodegradable polymeric drug carriers such as nanoparticles might enable its passage across the blood-brain barrier. The optimization of the preparation of the LPM-loaded PLA nanoparticles was performed employing high pressure emulsification-solvent evaporation. The resulting nanoparticles were characterized by particle size, distribution, thermal analysis, and drug release profiles. The partition of LPM into the organic phase increased with an increase in pH of the aqueous phase and with addition of lipophilic surfactants such as sorbitan fatty acid esters, resulting in an increase in the drug entrapment in the nanoparticles. Evaporation of the organic phase under reduced pressure and the addition of ethanol in the organic phase yielded a high drug entrapment due to the rapid polymer precipitation. The addition of the sorbitan fatty acid esters further increased the drug entrapment even at higher LPM concentrations. The results of thermal analysis suggest that LPM was homogeneously dispersed in the amorphous polymer matrix. The in vitro release of the drug from nanoparticles was biphasic, with a fast initial phase, followed by a second slower phase. Different drug release profiles from nanoparticles can be achieved by addition of sorbitan fatty acid esters, or the employment of different solvents as the organic phase. PMID:9292435

  15. EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Ceulemans, K.; Müller, J.-F.

    2011-09-01

    We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects), a method to predict (subcooled) liquid pure compound vapour pressure p0 of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T) is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA).

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

    NASA Astrophysics Data System (ADS)

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

    2006-01-01

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

  17. Surface diagnostics of evaporating droplets of nanosphere suspension: Fano interference and surface pressure.

    PubMed

    Kolwas, Maciej; Kolwas, Krystyna; Derkachov, Gennadiy; Jakubczyk, Daniel

    2015-03-14

    The evaporation of a single, levitating microdroplet of glycols containing SiO2 nanospheres, both of similar refraction indices, was studied by observing changes in the interference pattern and intensities of polarized and depolarized scattered laser light. The evolution of the effective radius of the droplet has been found on the basis of Mie scattering theory supplemented by the "electrical weighting" measurement of droplet mass evolution. During formation of a layer of nanospheres on the droplet surface, the asymmetric Fano profile was observed which was found to be due to the destructive and constructive interference of overlapping processes: (i) the scattering on single nanospheres emerging on the droplet surface and (ii) the scattering on ensembles of closely spaced (comparing to the light wavelength) nanospheres of an evolving surface film. Therefore we report the first observation of the Fano interference in the time domain rather than in the spectral domain. The optical surface diagnostics was complemented with the thermodynamics-like analysis in terms of the effective droplet surface pressure isotherm and with numerical simulations illustrating evaporation driven changes in the distribution of nanospheres. The reported study can serve as the basis for a wide range of novel diagnostic methods for studying configuration changes in complex systems of nano- and microparticles evolving at the sub-wavelength scale. PMID:25673315

  18. Pressure-flow reducer for aerosol focusing devices

    DOEpatents

    Gard, Eric; Riot, Vincent; Coffee, Keith; Woods, Bruce; Tobias, Herbert; Birch, Jim; Weisgraber, Todd

    2008-04-22

    A pressure-flow reducer, and an aerosol focusing system incorporating such a pressure-flow reducer, for performing high-flow, atmosphere-pressure sampling while delivering a tightly focused particle beam in vacuum via an aerodynamic focusing lens stack. The pressure-flow reducer has an inlet nozzle for adjusting the sampling flow rate, a pressure-flow reduction region with a skimmer and pumping ports for reducing the pressure and flow to enable interfacing with low pressure, low flow aerosol focusing devices, and a relaxation chamber for slowing or stopping aerosol particles. In this manner, the pressure-flow reducer decouples pressure from flow, and enables aerosol sampling at atmospheric pressure and at rates greater than 1 liter per minute.

  19. Predicting Equations for Evaporation Pressure Drop Inside Horizontal Smooth and Grooved Tubes

    NASA Astrophysics Data System (ADS)

    Kubota, Atsushi; Uchida, Mari; Shikazono, Naoki

    A new prediction method for evaporation pressure drop inside horizontal smooth and grooved tubes is proposed. These tubes had an outer diameter of 7mm, and the working fluids were R407C (HFC-32/HFC-125/HFC-134a, 23/25/52 mass%) and R410A (HFC-32/HFC-125, 50/50 mass%). The previous and present experimental data were correlated by Lockhart-Martinelli method, where Colburn and Carnavos equations were utilized for predicting single phase pressure drop of smooth and grooved tubes, respectively. Different numerical constants were adopted for smooth and grooved tubes to calculate the L-M pressure parameter φ L.Inorder to express the gravitational effect, a damping function for φ L was introduced. The proposed damping function was expressed as a function of Froude number for both smooth and grooved tubes. It is confirmed that 95% of the predicted results are within the accuracy of ±30% for both smooth and grooved tubes.

  20. Method for reducing pressure drop through filters, and filter exhibiting reduced pressure drop

    SciTech Connect

    Sappok, Alexander; Wong, Victor

    2014-11-18

    Methods for generating and applying coatings to filters with porous material in order to reduce large pressure drop increases as material accumulates in a filter, as well as the filter exhibiting reduced and/or more uniform pressure drop. The filter can be a diesel particulate trap for removing particulate matter such as soot from the exhaust of a diesel engine. Porous material such as ash is loaded on the surface of the substrate or filter walls, such as by coating, depositing, distributing or layering the porous material along the channel walls of the filter in an amount effective for minimizing or preventing depth filtration during use of the filter. Efficient filtration at acceptable flow rates is achieved.

  1. Fluid Dynamics of a Pressure Reducing Inlet

    NASA Technical Reports Server (NTRS)

    Russell, John M.

    2001-01-01

    Instruments for the monitoring of hazardous gases in and near the space shuttle collect sample gas at pressures on the order of one atmosphere and analyze their properties in an ultra-high vacuum by means of a quadrupole-mass-spectrometer partial pressure transducer. Sampling systems for such devices normally produce the required pressure reduction through combinations of vacuum pumps, fluid Tees and flow restrictors (e.g. orifices, sintered metal frits or capillaries). The present work presents an analytical model of the fluid dynamics of such a pressure reduction system which enables the calculation of the pressure in the receiver vessal in terms of system parameters known from the specifications for a given system (e.g. rated pumping speeds of the pumping hardware and the diameters of two orifices situated in two branches of a fluid Tee). The resulting formulas will expedite the fine tuning of instruments now under development and the design of later generations of such devices.

  2. Ion/molecule reaction and ion evaporation in atmospheric pressure spray ionization

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Atsumu; Takada, Yasuaki; Kambara, Hideki; Umemura, Yuta; Ohta, Hitoshi; Ito, Haruhiko; Kuchitsu, Kozo

    1992-12-01

    The positive ions produced in atmospheric pressure spray ionization of ammonia, alanine and sucrose in aqueous solution were detected with a double-focusing mass spectrometer. The relative intensities of the quasi-molecular ions of ammonia, NH+4 (H2O)n (n = 0-3), were found to be proportional to the concentration of the ammonia solution and to increase with increasing distance d between the nozzle tip and the sample aperture of the mass spectrometer; this observation shows that the ammonia molecule is produced by the spray and is protonated at atmospheric pressure by a proton transfer reaction with the hydronium ion and its hydrated clusters. The observed dependences of the relative intensities of the protonated alanine molecules from alanine solution and the cationized sucrose molecules from sucrose solution on d show that some part of these quasi-molecular ions are also produced by the ion/molecule reaction in the gas phase. However, their dependences on the concentration, which are steeper than that in the ammonia case, indicate that a significant proportion of these ions are produced by ion evaporation from a droplet or liquid.

  3. Pressure to produce=pressure to reduce accident reporting?

    PubMed

    Probst, Tahira M; Graso, Maja

    2013-10-01

    Each year, more than 4 million U.S. workers are injured on the job - several thousand die (Bureau of Labor Statistics, 2008). Despite these staggering numbers, research suggests that they are gross underestimates of the true volume of workplace related illnesses and injuries due to accident under-reporting. Although accident under-reporting has been well-documented, less is known regarding why this occurs. The current study suggests that under-reporting may in part be due to high levels of perceived production pressure. Specifically, this study tested the hypotheses that production pressure would be related to more experienced accidents overall and more negative attitudes toward reporting accidents. Further, we expected that production pressure would exacerbate the under-reporting of accidents. Survey data were collected from a sample of 212 copper mining workers located in the southwestern United States. The survey measured employee perceptions regarding production pressure, attitudes toward reporting accidents, perceived consequences of reporting accidents, and actual reporting behaviors (e.g., types and numbers of accidents experienced vs. reported). As predicted, the average number of experienced accidents per employee was significantly higher (M=2.84) than the number of reported accidents (M=.49). In addition, production pressure was related to more negative reporting attitudes. Individuals who had positive reporting attitudes were injured less frequently; however, when an incident occurred, they were more likely to report it. Finally, higher levels of production pressure were related to greater accident under-reporting. Additionally, employees who perceived high levels of production pressure not only experienced more accidents overall, they also reported fewer of them to the organization. Implications for occupational safety initiatives--particularly in the current economic climate--are discussed, as are methodological challenges of conducting research in

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

    PubMed

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

    2013-04-11

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

  5. Kinetic resolution of (R,S)-sec-butylamine using omega-transaminase from Vibrio fluvialis JS17 under reduced pressure.

    PubMed

    Yun, Hyungdon; Cho, Byung-Kwan; Kim, Byung-Gee

    2004-09-20

    The kinetic resolution of (R,S) sec-butylamine with the omega-transaminase (TA) from Vibrio fluvialis JS17 was performed under reduced pressure (e.g., 150 torr) to selectively remove an inhibitory product (2-butanone). The evaporation kinetics of 2-butanone at 150 torr in the buffer solution followed the first-order rate law, and the evaporation rate constant was 2.19 1/h, and independent of pH, while the evaporation kinetics of sec-butylamine is dependent on pH. A simple mathematical model of the evaporation of sec-butylamine allowing the estimation of its concentration in the reaction media was developed. The evaporation rate constant of its free amine form and the protonated amine form were 1.00 1/h, and nearly zero, respectively. Although the optimum pH of the omega-TA activity for sec-butylamine is 9.0, the optimal pH of the enzyme reaction under reduced pressure was pH 7.0, due to the higher evaporation rate of sec-butylamine at higher pH above 7.0. Using the recombinant Escherichia coli BL21 overexpressing omega-TA, 400 mM racemic sec-butylamine was resolved successfully to 98% ee of (R)-sec-butylamine with 53% conversion at 150 torr and pH 7.0. PMID:15329935

  6. [Reducing blood pressure with Dipyron (novaminsulfone sodium)].

    PubMed

    Zoppi, M; Hoigné, R; Keller, M F; Streit, F; Hess, T

    1983-11-26

    A fall in systolic blood pressure without other symptoms of anaphylactic shock has been described following the administration of drugs containing dipyrone. This adverse reaction was first observed in 4 patients by the same team in 1972-1973. Ten further cases with a fall in systolic blood pressure by at least 20 mm Hg occurring within minutes to 6 hours after intravenous administration of dipyrone are presented in this paper. In each of them this adverse reaction was considered to be probable or even definite. During the years 1976-1981 drug exposure was registered for all 15 678 patients of the two medical divisions of Comprehensive Hospital Drug Monitoring Berne. This adverse reaction was found in 7, representing 0.34% of the 2053 patients who received intravenous treatment with a dipyrone preparation. PMID:6658424

  7. Influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube

    SciTech Connect

    Koehler, W; Hein, D

    1986-09-01

    The influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube was investigated for a parameter range occurring in fossil-fired steam generators. Included in the analysis are quantities which determine the wetting state in steady and transient flow. The experimental work consists of the following: Occurrence of critical heat flux (CHF) and post-CHF heat transfer in a vertical upflow evaporator tube; influence of pressure and enthalpy transients on heat transfer in the unwetted region; influence of pipe orientation on heat transfer; and two phase flow pressure loss in wetted and unwetted region. Based on these experiments a method of predicting CHF for a vertical upflow evaporator tube was developed. The heat transfer in the unwetted region was newly formulated taking into account thermal nonequilibrium between the water and steam phases. Wall temperature excursions during pressure and enthalpy transients are interpreted with the help of the boiling curve and the Leidenfrost phenomenon. A method is developed by means of which it is possible to determine the influence of the pipe orientation on the location of the boiling crisis as well as on the heat transfer in the unwetted region. The influence of the wetting state of the heated surface on the two phase flow pressure loss is interpreted as ''Wall effect'' and is calculated using a simplified computer model. 68 refs., 83 figs.

  8. Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

    PubMed

    Libralato, G; Ghirardini, A Volpi; Avezzù, F

    2008-05-30

    Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity. PMID:17980956

  9. Investigation of interfacial phenomena and thermocapillary effect on drop evaporation in reduced gravity condition

    NASA Astrophysics Data System (ADS)

    Xie, Jingchang; Lin, Hai

    2013-11-01

    Based on ground-based experiments, a drop evaporation experiment will fly aboard Chinese recoverable satellite in the near future This experiment will focus on the interfacial phenomena of phase chance, heat and mass transfer and the effect of thermocapillary convection on drop evaporation process Close attention will also be paid to the contact angle behavior, the triple line shifting and their relations Our ground-based experiments observed the interior flow field and the gaseous exterior of small suspended evaporating drops, the temperature distributions inside and outside the drops. Both good heat conductor and heat insulating material were used as substrate materials to investigate their influence on heat transfer and surface temperature distribution of an evaporating drop Experimental results indicate that for a drop evaporating in ambient temperature without substrate heating, temperature gradients existed along the drop surface which results in stable thermocapillary convection and cells appeared near the surface throughout entire evaporating process. The thermocapillary convection greatly changed drop's interior temperature distribution and the way of energy and mass transfer. Temperature jump or discontinuity was also measured at drop free surface.

  10. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    SciTech Connect

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-11-28

    This article describes the use of evaporation control lids that are fitted to crystallization plates to improve the reproducibility of trials using as little as 5 nl. The plate lids contain apertures which are large enough for the transfer of protein containing droplets, but small enough to greatly reduce the rate of evaporation during the time needed to prepare the plate. A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.

  11. Air Circulation and Heat Exchange Under Reduced Pressures

    NASA Technical Reports Server (NTRS)

    Rygalov, V.; Wheeler, R.; Dixon, M.; Fowler, P.; Hillhouse, L.

    2010-01-01

    Heat exchange rates decrease non-linearly with reductions in atmospheric pressure. This decrease creates risk of thermal stress (elevated leaf temperatures) for plants under reduced pressures. Forced convection (fans) significantly increases heat exchange rate under almost all pressures except below 10 kPa. Plant cultivation techniques under reduced pressures will require forced convection. The cooling curve technique is a reliable means of assessing the influence of environmental variables like pressure and gravity on gas exchange of plant. These results represent the extremes of gas exchange conditions for simple systems under variable pressures. In reality, dense plant canopies will exhibit responses in between these extremes. More research is needed to understand the dependence of forced convection on atmospheric pressure. The overall thermal balance model should include latent and radiative exchange components.

  12. Effects of carbonyl bond, metal cluster dissociation, and evaporation rates on predictions of nanotube production in high-pressure carbon monoxide

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Smalley, Richard E.

    2003-01-01

    The high-pressure carbon monoxide (HiPco) process for producing single-wall carbon nanotubes (SWNTs) uses iron pentacarbonyl as the source of iron for catalyzing the Boudouard reaction. Attempts using nickel tetracarbonyl led to no production of SWNTs. This paper discusses simulations at a constant condition of 1300 K and 30 atm in which the chemical rate equations are solved for different reaction schemes. A lumped cluster model is developed to limit the number of species in the models, yet it includes fairly large clusters. Reaction rate coefficients in these schemes are based on bond energies of iron and nickel species and on estimates of chemical rates for formation of SWNTs. SWNT growth is measured by the conformation of CO2. It is shown that the production of CO2 is significantly greater for FeCO because of its lower bond energy as compared with that of NiCO. It is also shown that the dissociation and evaporation rates of atoms from small metal clusters have a significant effect on CO2 production. A high rate of evaporation leads to a smaller number of metal clusters available to catalyze the Boudouard reaction. This suggests that if CO reacts with metal clusters and removes atoms from them by forming MeCO, this has the effect of enhancing the evaporation rate and reducing SWNT production. The study also investigates some other reactions in the model that have a less dramatic influence.

  13. Reducing cyclone pressure drop with evasés

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  14. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    SciTech Connect

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-11-28

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. Ultimately, the results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.

  15. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    PubMed Central

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-01-01

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations. PMID:25484231

  16. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    DOE PAGESBeta

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; et al

    2014-11-28

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under differentmore » conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. Ultimately, the results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.« less

  17. Water retention curves of loamy-sandy soils: Transient evaporation method versus steady-state tension and pressure techniques

    NASA Astrophysics Data System (ADS)

    Winkler, G.; Eberhard, E.; Fank, J.; Birk, S.

    2009-12-01

    Water retention curves of loamy-sandy soils at the agricultural test site Wagna (Austria) were measured using both the simplified evaporation method according to Schindler (Arch. Acker- u. Pflanzenbau u. Bodenkd. Berlin 24, 1-7, 1980) and steady-state tension and pressure techniques. The soil was sampled with 250-ccm and 100-ccm steel pipes for the evaporation method and the steady-state technique, respectively. In the transient evaporation method two tensiometers with a measurement range between 0 and 850 hPa are installed at a depth of 1.25 cm and 3.75 cm in a sample of 5 cm in height; the mean values of the two tensiometers and the water contents measured by weighing are used to obtain the water retention curve. The steady-state method employs a tension table (sand box) at tensions below 100 hPa and a pressure extractor at tensions between 300 hPa and 15,000 hPa; the water content is measured by weighing after the sample has equilibrated at the tension value set on the table or plate. First results of both methods suggest that the soil samples release water over the entire tension range measured. In particular, the release of water at very low tension values may suggest the presence of macropores. Despite the generally good agreement between the two methods, the values appear to deviate systematically close to saturation. This is potentially caused by the large relative error of the tension measurement close to saturation. Alternatively, the different size of the samples used for the evaporation experiment (250 ccm) and the steady-state method (100 ccm) might play a role. Because of the limited measurement range of the tensiometers used for the evaporation method, the measured curve must be extrapolated between 850 hPa and 15,000 hPa to allow comparison with the steady-state method. To this end, it was attempted to match the Brooks-Corey, the Van-Genuchten, and a bimodal Van-Genuchten retention function to the data from the evaporation experiments. This involves

  18. Cell Structure Evolution of Aluminum Foams Under Reduced Pressure Foaming

    NASA Astrophysics Data System (ADS)

    Cao, Zhuokun; Yu, Yang; Li, Min; Luo, Hongjie

    2016-07-01

    Ti-H particles are used to increase the gas content in aluminum melts for reduced pressure foaming. This paper reports on the RPF process of AlCa alloy by adding TiH2, but in smaller amounts compared to traditional process. TiH2 is completely decomposed by stirring the melt, following which reduced pressure is applied. TiH2 is not added as the blowing agent; instead, it is added for increasing the H2 concentration in the liquid AlCa melt. It is shown that pressure change induces further release of hydrogen from Ti phase. It is also found that foam collapse is caused by the fast bubble coalescing during pressure reducing procedure, and the instability of liquid film is related to the significant increase in critical thickness of film rupture. A combination of lower amounts of TiH2, coupled with reduced pressure, is another way of increasing hydrogen content in the liquid aluminum. A key benefit of this process is that it provides time to transfer the molten metal to a mold and then apply the reduced pressure to produce net shape foam parts.

  19. Cell Structure Evolution of Aluminum Foams Under Reduced Pressure Foaming

    NASA Astrophysics Data System (ADS)

    Cao, Zhuokun; Yu, Yang; Li, Min; Luo, Hongjie

    2016-09-01

    Ti-H particles are used to increase the gas content in aluminum melts for reduced pressure foaming. This paper reports on the RPF process of AlCa alloy by adding TiH2, but in smaller amounts compared to traditional process. TiH2 is completely decomposed by stirring the melt, following which reduced pressure is applied. TiH2 is not added as the blowing agent; instead, it is added for increasing the H2 concentration in the liquid AlCa melt. It is shown that pressure change induces further release of hydrogen from Ti phase. It is also found that foam collapse is caused by the fast bubble coalescing during pressure reducing procedure, and the instability of liquid film is related to the significant increase in critical thickness of film rupture. A combination of lower amounts of TiH2, coupled with reduced pressure, is another way of increasing hydrogen content in the liquid aluminum. A key benefit of this process is that it provides time to transfer the molten metal to a mold and then apply the reduced pressure to produce net shape foam parts.

  20. Operation of a low temperature absorption chiller at rating point and at reduced evaporator temperature

    NASA Astrophysics Data System (ADS)

    Best, R.; Biermann, W.; Reimann, R. C.

    1985-01-01

    The returned fifteen ton Solar Absorption Machine (SAM) 015 chiller was given a cursory visual inspection, some obvious problems were remedied, and then it was placed on a test stand to get a measure of dirty performance. It was then given a standard acid clean, the water side of the tubes was brushed clean, and then the machine was retested. The before and after cleaning data were compared to equivalent data taken before the machine was shipped. The second part of the work statement was to experimentally demonstrate the technical feasibility of operating the chiller at evaporator temperatures below 0(0)C (32(0)F) and identify any operational problems.

  1. Water cycle and its management for plant habitats at reduced pressures

    NASA Technical Reports Server (NTRS)

    Rygalov, Vadim Y.; Fowler, Philip A.; Wheeler, Raymond M.; Bucklin, Ray A.

    2004-01-01

    Experimental and mathematical models were developed for describing and testing temperature and humidity parameters for plant production in bioregenerative life support systems. A factor was included for analyzing systems operating at low (10-101.3 kPa) pressure to reduce gas leakage and structural mass (e.g., inflatable greenhouses for space application). The expected close relationship between temperature and relative humidity was observed, along with the importance of heat exchanger coil temperature and air circulation rate. The presence of plants in closed habitats results in increased water flux through the system. Changes in pressure affect gas diffusion rates and surface boundary layers, and change convective transfer capabilities and water evaporation rates. A consistent observation from studies with plants at reduced pressures is increased evapotranspiration rates, even at constant vapor pressure deficits. This suggests that plant water status is a critical factor for managing low-pressure production systems. The approach suggested should help space mission planners design artificial environments in closed habitats.

  2. Improvement of biohydrogen production using a reduced pressure fermentation.

    PubMed

    Kisielewska, M; Dębowski, M; Zieliński, M

    2015-10-01

    This study investigated the effect of reduced pressure on biohydrogen production in an upflow anaerobic sludge blanket (UASB) reactor from whey permeate. The results showed that the reduced pressure fermentation was more effective in enhancing biohydrogen production than dark fermentative hydrogen production at atmospheric pressure. Mesophilic fermentative biohydrogen production was investigated at a constant hydraulic retention time (HRT) of 24 h and increasing organic loading rates (OLRs) of 20, 25, 30, 35 kg COD/m(3) day. The reduced pressure fermentation was successfully operated at all OLRs tested. The maximum proportion of hydrogen in biogas of 47.7 %, volumetric hydrogen production rate (VHPR) of 7.10 L H2/day and hydrogen yield of 4.55 mol H2/kg COD removed occurred at the highest OLR. Increase in OLR affected the hydrogen production in UASB reactor exploited at atmospheric pressure. The reduced pressure process was able to remarkably improve the biohydrogen performance at high OLRs. PMID:26111633

  3. Reduced energy consumption evaporator for use in desalting impaired waters. Technical completion report (Final)

    SciTech Connect

    Tleimat, B.W.; Tleimat, M.C.

    1995-06-01

    The basic objective of this program is to demonstrate significant savings in energy consumption by the use of the wiped film rotating disk (WFRD) evaporator in a five-effect vapor compression distillation (MEVCD) system to recover the maximum amount of water from agricultural drainage water and other impaired waters. Tests were conducted using a 10,000 ppm aqueous solution of sodium sulfate and sodium chloride to simulate the composition of agricultural drainage water in the San Joaquin Valley, California. The feed was concentrated by a factor ranging from 15 to 20 resulting in a blowdown salinity of 150,000 to 200,000 ppm. The results showed the presence of dissolved salts has significant influence on energy consumption by the compressor of a commercial 60,000 gal/day VCD unit tested at Los Banos, California.

  4. Air Circulation and Heat Exchange under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim; Wheeler, Raymond; Dixon, Mike; Hillhouse, Len; Fowler, Philip

    Low pressure atmospheres were suggested for Space Greenhouses (SG) design to minimize sys-tem construction and re-supply materials, as well as system manufacturing and deployment costs. But rarified atmospheres modify heat exchange mechanisms what finally leads to alter-ations in thermal control for low pressure closed environments. Under low atmospheric pressures (e.g., lower than 25 kPa compare to 101.3 kPa for normal Earth atmosphere), convection is becoming replaced by diffusion and rate of heat exchange reduces significantly. During a period from 2001 to 2009, a series of hypobaric experiments were conducted at Space Life Sciences Lab (SLSLab) NASA's Kennedy Space Center and the Department of Space Studies, University of North Dakota. Findings from these experiments showed: -air circulation rate decreases non-linearly with lowering of total atmospheric pressure; -heat exchange slows down with pressure decrease creating risk of thermal stress (elevated leaf tem-peratures) for plants in closed environments; -low pressure-induced thermal stress could be reduced by either lowering system temperature set point or increasing forced convection rates (circulation fan power) within certain limits; Air circulation is an important constituent of controlled environments and plays crucial role in material and heat exchange. Theoretical schematics and mathematical models are developed from a series of observations. These models can be used to establish optimal control algorithms for low pressure environments, such as a space greenhouse, as well as assist in fundamental design concept developments for these or similar habitable structures.

  5. EVAPORATION: a new vapor pressure estimation method for organic molecules including non-additivity and intramolecular interactions

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Ceulemans, K.; Müller, J.-F.

    2011-04-01

    We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects), a method to predict vapour pressure p0 of organic molecules needing only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T) is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: carbonyls, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA).

  6. Reduced atmospheric pressure in Radish: Alteration of NCER and transpiration at decreased oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Wehkamp, Cara Ann; Stasiak, Michael; Wheeler, Raymond; Dixon, Mike

    Fundamental to the future of space exploration is the development of advanced life support systems capable of maintaining crews for significant periods without re-supply from Earth. Significant research is focused on the development of bioregenerative life support systems to be used in conjunction with the current physico-chemical methods. These bioregenerative life support systems harness natural ecosystem processes and employ plant photosynthesis and transpiration to produce food, oxygen and regenerate water while consuming carbon dioxide. The forthcoming exploration of the Moon and Mars has prompted interest into the effects of hypobaria on plant development. Reduced atmospheric pressures will lessen the pressure gradient between the structure and the local environment thereby decreasing gas leakage and possibly the structural mass of the plant growth facility. In order to establish the optimal specifications for reduced pressure plant growth structures it is essential to determine the atmospheric pressure limits required for conventional plant development and growth. Due to its physiological importance, oxygen will compose a significant portion of these minimal environments. The objective of this study was to test the hypothesis that reduced atmospheric pressure and decreased oxygen partial pressures had no effect on radish productivity. Radishes (Raphanus sativa L. cv. Cherry Bomb II) were grown from seed in the University of Guelph's Hypobaric Plant Growth Chambers for a period of 21 days. Treatments included total pressures of 10, 33, 66 and 96 kPa and oxygen partial pressures of 2, 7, 14 and 20 kPa. Experiments demonstrated that reduced partial pressures of oxygen had a greater effect on radish growth than hypobaria. Results showed a reduction in net carbon exchange rate and transpiration with decreasing oxygen partial pressures leading to diminished productivity. Keywords: hypobaric, radish, oxygen partial pressure, variable pressure chamber

  7. Reducing hospital acquired pressure ulcers in intensive care

    PubMed Central

    Cullen Gill, Emma

    2015-01-01

    Pressure ulcers are a definite problem in our health care system and are growing in numbers. Unfortunately, it is usually the most weak and vulnerable of our culture that faces these complications, causing the patient and their families discomfort, anguish, and economic hardship due to their expensive treatment. Data collected by the tissue viability department showed high incidence of hospital acquire pressure ulcers in the intensive care unit in March 2013. An action plan was initiated and implemented by the tissue viability team, senior nursing management, pressure ulcer prevention (PUP) team and respiratory therapists (RT's) within the ICU. Our objective was to reduce hospital acquired pressure ulcers in the intensive care unit using the plan, do, check, act quality improvement process. PMID:26734370

  8. Reducing peanut allergens by high pressure combined with polyphenol oxidase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO) has been shown to reduce major peanut allergens (Ara h 1 and Ara h 2). Because high pressure (HP) can increase enzyme activity, we postulated that further reduction of peanut allergens can be achieved through HP combined with PPO. Peanut extracts were treated with each of th...

  9. Features of erosion-corrosion wear in low-pressure evaporators of combined-cycle plant heat-recovery boilers at high void factor values

    NASA Astrophysics Data System (ADS)

    Galetsky, N. S.; Schwarz, A. L.

    2013-12-01

    The features of erosion-corrosion wear (ECW) in a low-pressure evaporator (LPE) combinedcycle plant (CCP) at high void factor values in the heat carrier are considered. It is shown that if the medium pressure in the evaporator is less than 1 MPa and steam quality x ≈ 0.5, the void fraction β is close to 1, at the outlet of the evaporator almost dry saturated steam moves, and the formation of liquid films is excluded. Under these conditions, the wear of the evaporator coil sections has an erosive nature, caused by high velocity steam, carrying the dense particles of corrosion products and large drops of water, previously plucked from the surface of the liquid films.

  10. Comparison of soil moisture retention characteristics obtained by the extended evaporation method and the pressure plate/sand box apparatus

    NASA Astrophysics Data System (ADS)

    Öztürk, Hasan S.; Durner, Wolfgang; Haghverdi, Amir; Walter, Birgit

    2013-04-01

    The water retention curve (WRC) characterizes the capacity of soil to hold water at specified soil matric potentials. It is a key property in any soil hydrologic application. To determine water retention data accurately and in turn use them to draw the whole curve by optimizing parameters of a proper soil hydraulic equation, it is of crucial importance to choose a suitable measurement procedure. For many years, the sand box-pressure plate apparatus are widely accepted as a reference laboratory procedure. To overcome shortcomings of the pressure plate, the evaporation method was introduced, besides many others. The method is not dependent on hydrostatic equilibrium conditions, thus allowing much quicker measurements, and yields the WRC in very high resolution. The method furthermore enables to quantify the unsaturated hydraulic conductivity function. We investigated a set of 40 fine-textured soils with both methods. The samples were packed from aggregated, dried and sieved material. Eight (-5, -10, -33, -100, -400, -700,-1000 and -1500kPa) water retention data points were obtained from sand box-pressure plate apparatus. Evaporation measurements were performed with the commercial apparatus HYPROP by UMS GmbH, Munich, applying the extended method, which yields water retention data in the range from 0 to -500kPa. We found that the sand box-pressure plate method lead to immediate drainage of water, whereas in HYPROP water started to drain only after reaching an air-entry point of pF 1.2-1.3. Accordingly, HYPROP gave higher water contents until pF 2, compared to the sand box/pressure plate apparatus, but from this point on both curves begin to be close and around the field capacity (pF 2.5) they overlap. Both methods show that the textural pore system starts to drain much later, around pF 3.5. We hypothesize that the reason for the different drainage behaviour of the interaggrate pore system lies in the saturation procedure. For HYPROP, samples were saturated under

  11. Quality characteristics of the radish grown under reduced atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Levine, Lanfang H.; Bisbee, Patricia A.; Richards, Jeffrey T.; Birmele, Michele N.; Prior, Ronald L.; Perchonok, Michele; Dixon, Mike; Yorio, Neil C.; Stutte, Gary W.; Wheeler, Raymond M.

    This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORACFL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.

  12. High pressure droplet burning experiments in reduced gravity

    NASA Technical Reports Server (NTRS)

    Chauveau, Christian; Goekalp, Iskender

    1995-01-01

    A parametric investigation of single droplet gasification regimes is helpful in providing the necessary physical ideas for sub-grid models used in spray combustion numerical prediction codes. A research program has been initiated at the LCSR to explore the vaporization regimes of single and interacting hydrocarbon and liquid oxygen droplets under high pressure conditions. This paper summarizes the status of the LCSR program on the high pressure burning of single fuel droplets; recent results obtained under normal and reduced gravity conditions with suspended droplets are presented. In the work described here, parabolic flights of the CNES Caravelle is used to create a reduced gravity environment of the order of 10(exp -2) g(sub O). For all the droplet burning experiments reported here, the suspended droplet initial diameters are scattered around 1.5 mm; and the ambient air temperature is 300 K. The ambient pressure is varied between 0.1 MPa and 12 MPa. Four fuels are investigated: methanol (Pc = 7.9 MPa), n-heptane (Pc = 2.74 MPa), n-hexane (Pc = 3.01 MPa) and n-octane (Pc = 2.48 MPa).

  13. Reducing uncertainty in geostatistical description with well testing pressure data

    SciTech Connect

    Reynolds, A.C.; He, Nanqun; Oliver, D.S.

    1997-08-01

    Geostatistics has proven to be an effective tool for generating realizations of reservoir properties conditioned to static data, e.g., core and log data and geologic knowledge. Due to the lack of closely spaced data in the lateral directions, there will be significant variability in reservoir descriptions generated by geostatistical simulation, i.e., significant uncertainty in the reservoir descriptions. In past work, we have presented procedures based on inverse problem theory for generating reservoir descriptions (rock property fields) conditioned to pressure data and geostatistical information represented as prior means for log-permeability and porosity and variograms. Although we have shown that the incorporation of pressure data reduces the uncertainty below the level contained in the geostatistical model based only on static information (the prior model), our previous results assumed did not explicitly account for uncertainties in the prior means and the parameters defining the variogram model. In this work, we investigate how pressure data can help detect errors in the prior means. If errors in the prior means are large and are not taken into account, realizations conditioned to pressure data represent incorrect samples of the a posteriori probability density function for the rock property fields, whereas, if the uncertainty in the prior mean is incorporated properly into the model, one obtains realistic realizations of the rock property fields.

  14. External Cooling Coupled to Reduced Extremity Pressure Device

    NASA Technical Reports Server (NTRS)

    Kuznetz, Lawrence H.

    2011-01-01

    Although suited astronauts are currently cooled with a Liquid Cooled Ventilation Garment (LCVG), which can remove up to 85 percent of body heat, their effectiveness is limited because cooling must penetrate layers of skin, muscle, fat, bone, and tissue to reach the bloodstream, where its effect is prominent. Vasoconstriction further reduces the effectiveness by limiting arterial flow when exposed to cold (the frostbite response), resulting in a time constant on the order of 20 minutes from application to maximum effect. This delay can be crucial in severe exposure to hypo- or hyper-thermic conditions, compromising homeostasis. The purpose of this innovation is to provide a lightweight, effective means of delivering heat or cold from an external source directly to the bloodstream. The effectiveness of this ECCREP (External Cooling Coupled to Reduced Extremity Pressure) device is based on not having to penetrate layers of skin, muscle, fat, and tissue, thereby avoiding the thermal lag associated with their mass and heat capacity. This is accomplished by means of an outer boot operating at a slightly reduced pressure than the rest of the body, combined with an inner boot cooled or heated by an external source via water or chemicals. Heat transfer from the external source to the foot takes place by means of circulating water or flexible heat pipes.

  15. Easing food waste could reduce pressure on natural resources

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-09-01

    Calls to reduce food waste and enhance agricultural water efficiency were among the points raised during the 27 August opening session of World Water Week in Stockholm, Sweden. “More than one fourth of all the water we use worldwide is taken to grow over one billion tons of food that nobody eats. That water, together with the billions of dollars spent to grow, ship, package, and purchase the food, is sent down the drain,” said Torgny Holmgren, executive director of the Stockholm International Water Institute, which organizes World Water Week. “Reducing the waste of food is the smartest and most direct route to relieve pressure on water and land resources. It's an opportunity we cannot afford to overlook,” he added.

  16. Measurement of intramedullary pressure in an animal experiment and propositions to reduce the pressure increase.

    PubMed

    Stürmer, K M

    1993-01-01

    1. During reaming of the medullary cavity prior to nailing, hydraulic pressure builds up in the cavity which far exceeds that of blood pressure. The peak values for 29 sheep clearly exceeds 2.5 bar. The highest values for individual reamers average 1.3 bar. The differences between the various reamers are only small. Intraoperative measurements on patients have confirmed these results. 2. The reamer acts as a hydraulic piston in a piston sleeve which is filled with a mixture of medullary fat, blood, blood clots and bone debris. The level of pressure depends on the flow rate of the medullary cavity contents between the reamer and the bone according to the gap formula. This is particularly dependent on the gap height which is to the third power in the gap equation. 3. The pressure rise can be most effectively prevented by reducing viscosity of the medullary content using the irrigation-suction technique. The reaming rod is cannulated and is continuously filled with Ringer solution in the distal part of the medullary cavity. This is then drawn off proximally after rinsing the reamer. Experimental measurements on 19 sheep did not produce high pressures, but rather negative pressures. 4. Venting holes in the bone only have little effect because their diameter is too small and local peak values must be assumed during the passage of the reamer. 5. Reaming the medullary cavity less does not prevent pressure increase. Pressure is high even for reamers of small diameter.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8168880

  17. On the evaporation of ammonium sulfate solution

    PubMed Central

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-01-01

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 ± 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor–liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly. PMID:19861551

  18. On the evaporation of ammonium sulfate solution

    SciTech Connect

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

  19. Generation of aerosols by the electrical explosion of wires at reduced air pressure

    SciTech Connect

    Sedoi, V.S.; Valevich, V.V.; Katz, J.D.

    1998-12-31

    The exploding wire method of particle production allows the authors to model the high speed formation of aerosols because of the fast heating and evaporation rates inherent to this technique. The method is also of interest from the viewpoint of controlling the production of aerosols of a particular material with a specific particle size distribution at a specific efficiency. The electrical explosion of iron, aluminum, titanium, and copper wires have been investigated in various gases at pressures from 0.01 to 1 atm. In these experiments the energy density introduced into the material, w, is normalized to the sublimation energy of the material, w{sub s}. The energy density also controls the heating rate. Particle and agglomerate sizes were determined using transmission electron microscopy and laser scattering methods. The specific surface area of the powder was measured by low-temperature adsorption. The phase composition was determined by X-ray diffraction. Increasing the energy density increases the internal energy of the material, the expansion velocity and the number of condensation centers, while the final particle size decreases. With an exothermic oxidation reaction, the optimum energy density can be less than the sublimation energy of the material. As a result, metal oxides are formed. Electrical explosion of wires, at reduced air pressures, allows for the production of ultra-fine powders of oxides of various metals with particle sizes of less than 50 nm. The method is environmentally safe and does not require excess energy expenditures. The electrical explosion of wire at reduced pressure allows for new possibilities in the production of ultra-fine powders (UFP).

  20. Metformin reduces hepatic resistance and portal pressure in cirrhotic rats.

    PubMed

    Tripathi, Dinesh M; Erice, Eva; Lafoz, Erica; García-Calderó, Héctor; Sarin, Shiv K; Bosch, Jaime; Gracia-Sancho, Jordi; García-Pagán, Juan Carlos

    2015-09-01

    Increased hepatic vascular resistance is the primary factor in the development of portal hypertension. Metformin ameliorates vascular cells function in several vascular beds. Our study was aimed at evaluating the effects, and the underlying mechanisms, of metformin on hepatic and systemic hemodynamics in cirrhotic rats and its possible interaction with the effects of propranolol (Prop), the current standard treatment for portal hypertension. CCl4-cirrhotic rats received by gavage metformin 300 mg/kg or its vehicle once a day for 1 wk, before mean arterial pressure (MAP), portal pressure (PP), portal blood flow (PBF), hepatic vascular resistance, and putative molecular/cellular mechanisms were measured. In a subgroup of cirrhotic rats, the hemodynamic response to acute Prop (5 mg/kg iv) was assessed. Effects of metformin ± Prop on PP and MAP were validated in common bile duct ligated-cirrhotic rats. Metformin-treated CCl4-cirrhotic rats had lower PP and hepatic vascular resistance than vehicle-treated rats, without significant changes in MAP or PBF. Metformin caused a significant reduction in liver fibrosis (Sirius red), hepatic stellate cell activation (α-smooth muscle actin, platelet-derived growth factor receptor β polypeptide, transforming growth factor-βR1, and Rho kinase), hepatic inflammation (CD68 and CD163), superoxide (dihydroethidium staining), and nitric oxide scavenging (protein nitrotyrosination). Prop, by decreasing PBF, further reduced PP. Similar findings were observed in common bile duct ligated-cirrhotic rats. Metformin administration reduces PP by decreasing the structural and functional components of the elevated hepatic resistance of cirrhosis. This effect is additive to that of Prop. The potential impact of this pharmacological combination, otherwise commonly used in patients with cirrhosis and diabetes, needs clinical evaluation. PMID:26138461

  1. Soil Evaporation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil evaporation can significantly influence energy flux partitioning of partially vegetated surfaces, ultimately affecting plant transpiration. While important, quantification of soil evaporation, separately from canopy transpiration, is challenging. Techniques for measuring soil evaporation exis...

  2. Chia flour supplementation reduces blood pressure in hypertensive subjects.

    PubMed

    Toscano, Luciana Tavares; da Silva, Cássia Surama Oliveira; Toscano, Lydiane Tavares; de Almeida, Antônio Eduardo Monteiro; Santos, Amilton da Cruz; Silva, Alexandre Sérgio

    2014-12-01

    The aim of this study was to investigate the effect of chia supplementation (Salvia hispanica L.) on blood pressure (BP) and its associated cardiometabolic factors in treated and untreated hypertensive individuals. The subjects were randomly assigned to one of the following groups: the hypertensive-drug treated (CHIA-MD, n = 10), hypertensive untreated (CHIA-NM, n = 9) and placebo (PLA-MD, n = 7) groups. The subjects consumed 35 g/day of either chia flour or a placebo for 12 weeks. The clinical and ambulatory BP, inflammation, oxidative stress and markers for nitric oxide were measured. While the PLA-MD group showed no changes in BP, there was a reduction in the mean clinical blood pressure (MBP) in the CHIA (111.5 ± 1.9 to 102.7 ± 1.5 mmHg, p < 0.001) and CHIA-MD (111.3 ± 2.2 to 100.1 ± 1.8 mmHg, p < 0.001) groups. The CHIA-NM group showed no reduction in the MBP but did show a decreased systolic BP (146.8 ± 3.8 to 137.3 ± 3.1 mmHg, p < 0.05). The clinical BP reduction was demonstrated by a 24 h ambulatory systolic reduction in all of the supplemented groups. However, the mean ambulatory BP was reduced only in the CHIA (98.1 ± 2.4 to 92.8 ± 2.2 mmHg, p < 0.05) group, and there was no change in the diastolic component in either of the CHIA groups. The lipid peroxidation was reduced in the CHIA (p = 0.04) and CHIA-NM (p = 0.02) groups compared with the PLA-MD group. A reduction in the plasma nitrite levels was observed only in the CHIA group (p = 0.02). Chia flour has the ability to reduce ambulatory and clinical BP in both treated and untreated hypertensive individuals. PMID:25403867

  3. A programme to reduce acquired pressure ulcers in care homes.

    PubMed

    Thompson, Trish Morris; Marks-Maran, Di

    Prevention of pressure ulcers is a major health concern, especially for older people. Much of the literature related to prevention of pressure ulcers focuses on hospital-acquired pressure ulcers. There is less literature related to prevention of pressure ulcers in care homes. This article presents a review of the literature related to prevention of pressure ulcers in care homes and an ambitious project undertaken by one care home provider to raise awareness of pressure ulcers, provide training in prevention and monitor and evaluate pressure ulcers in over 200 care home across the UK. Known as MI SKIN, the project involves ongoing training to all levels of care staff, a robust system of monitoring pressure ulcers and a mechanism to investigate and learn from any incident of pressure ulcer using root cause analysis. PMID:26110989

  4. Reduced Uterine Perfusion Pressure (RUPP) Model of Preeclampsia in Mice

    PubMed Central

    Fushima, Tomofumi; Sekimoto, Akiyo; Minato, Takahiro; Ito, Takuya; Oe, Yuji; Kisu, Kiyomi; Sato, Emiko; Funamoto, Kenichi; Hayase, Toshiyuki; Kimura, Yoshitaka; Ito, Sadayoshi; Sato, Hiroshi; Takahashi, Nobuyuki

    2016-01-01

    Preeclampsia (PE) is a pregnancy-induced hypertension with proteinuria that typically develops after 20 weeks of gestation. A reduction in uterine blood flow causes placental ischemia and placental release of anti-angiogenic factors such as sFlt-1 followed by PE. Although the reduced uterine perfusion pressure (RUPP) model is widely used in rats, investigating the role of genes on PE using genetically engineered animals has been problematic because it has been difficult to make a useful RUPP model in mice. To establish a RUPP model of PE in mice, we bilaterally ligated ovarian vessels distal to ovarian branches, uterine vessels, or both in ICR-strain mice at 14.5 days post coitum (dpc). Consequently, these mice had elevated BP, increased urinary albumin excretion, severe endotheliosis, and mesangial expansion. They also had an increased incidence of miscarriage and premature delivery. Embryonic weight at 18.5 dpc was significantly lower than that in sham mice. The closer to the ligation site the embryos were, the higher the resorption rate and the lower the embryonic weight. The phenotype was more severe in the order of ligation at the ovarian vessels < uterine vessels < both. Unlike the RUPP models described in the literature, this model did not constrict the abdominal aorta, which allowed BP to be measured with a tail cuff. This novel RUPP model in mice should be useful for investigating the pathogenesis of PE in genetically engineered mice and for evaluating new therapies for PE. PMID:27187738

  5. Reducing peanut allergens by high pressure combined with polyphenol oxidase

    NASA Astrophysics Data System (ADS)

    Chung, Si-Yin; Houska, Milan; Reed, Shawndrika

    2013-12-01

    Polyphenol oxidase (PPO) has been shown to reduce major peanut allergens. Since high pressure (HP) can increase enzyme activity, we postulated that further reduction of peanut allergens can be achieved through HP combined with PPO. Peanut extracts containing caffeic acid were treated with each of the following: (1) HP; (2) HP+PPO; (3) PPO; and (4) none. HP was conducted at 300 and 500 MPa, each for 3 and 10 min, 37 °C. After treatment, SDS-PAGE was performed and allergenic capacity (IgE binding) was determined colorimetrically in inhibition enzyme-linked immunosorbent assay and Western blots, using a pooled plasma from peanut-allergic patients. Data showed that HP alone had no effect on major peanut allergens. However, HP at 500 MPa combined with PPO (HP500/PPO) induced a higher (approximately twofold) reduction of major peanut allergens and IgE binding than PPO alone or HP300/PPO. There was no difference between treatment times. We concluded that HP500/PPO at 3-min enhanced a twofold reduction of the allergenic capacity of peanut extracts, as compared to PPO itself.

  6. Strategies to reduce pitfalls in measuring blood pressure.

    PubMed

    Badeli, Hamidreza; Assadi, Farahnak

    2014-03-01

    Errors in blood pressure (BP) measurement are common in the clinical practice. Inaccurate measurements of BP may lead to misdiagnosis and inappropriate treatment of hypertension. The preferred method of BP measurement in the clinical setting is auscultation, using the first and the fifth Korotkoff sounds. However, the use of mercury sphygmomanometer is declining. Automated oscillometric devices are an acceptable alternative method of BP measurements if the proper cuff size is used. Aneroid devices are suitable, but they require frequent calibration. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. At 24 h ambulatory monitoring is also useful for diagnosing white-coat hypertension and resistance hypertension. There is increasing evidence that lack of nocturnal BP dipping during the night may be associated with increased cardiovascular event. This report attempts to address the need for accurate BP measurements in children and adolescents by reducing human and equipment errors and providing clinicians with the accurate measurement of BP, which is essential to classify individuals, to ascertain BP-related CV risks and to guide management. PMID:24791186

  7. Reduced Uterine Perfusion Pressure (RUPP) Model of Preeclampsia in Mice.

    PubMed

    Fushima, Tomofumi; Sekimoto, Akiyo; Minato, Takahiro; Ito, Takuya; Oe, Yuji; Kisu, Kiyomi; Sato, Emiko; Funamoto, Kenichi; Hayase, Toshiyuki; Kimura, Yoshitaka; Ito, Sadayoshi; Sato, Hiroshi; Takahashi, Nobuyuki

    2016-01-01

    Preeclampsia (PE) is a pregnancy-induced hypertension with proteinuria that typically develops after 20 weeks of gestation. A reduction in uterine blood flow causes placental ischemia and placental release of anti-angiogenic factors such as sFlt-1 followed by PE. Although the reduced uterine perfusion pressure (RUPP) model is widely used in rats, investigating the role of genes on PE using genetically engineered animals has been problematic because it has been difficult to make a useful RUPP model in mice. To establish a RUPP model of PE in mice, we bilaterally ligated ovarian vessels distal to ovarian branches, uterine vessels, or both in ICR-strain mice at 14.5 days post coitum (dpc). Consequently, these mice had elevated BP, increased urinary albumin excretion, severe endotheliosis, and mesangial expansion. They also had an increased incidence of miscarriage and premature delivery. Embryonic weight at 18.5 dpc was significantly lower than that in sham mice. The closer to the ligation site the embryos were, the higher the resorption rate and the lower the embryonic weight. The phenotype was more severe in the order of ligation at the ovarian vessels < uterine vessels < both. Unlike the RUPP models described in the literature, this model did not constrict the abdominal aorta, which allowed BP to be measured with a tail cuff. This novel RUPP model in mice should be useful for investigating the pathogenesis of PE in genetically engineered mice and for evaluating new therapies for PE. PMID:27187738

  8. Evaporation- and Solution-Process-Feasible Highly Efficient Thianthrene-9,9',10,10'-Tetraoxide-Based Thermally Activated Delayed Fluorescence Emitters with Reduced Efficiency Roll-Off.

    PubMed

    Xie, Gaozhan; Li, Xianglong; Chen, Dongjun; Wang, Zhiheng; Cai, Xinyi; Chen, Dongcheng; Li, Yunchuan; Liu, Kunkun; Cao, Yong; Su, Shi-Jian

    2016-01-01

    Two novel evaporation- and solution-process-feasible thermally activated delayed fluorescence emitters, green-light-emission ACRDSO2 and yellow-light-emission PXZDSO2, based on a brand-new electron-acceptor moiety thianthrene-9,9',10,10'-tetraoxide, are developed for organic light-emitting diodes. The solution-processed devices, without any hole-transport layer, exhibit competitive performance and reduced efficiency roll-off compared with corresponding vacuum-deposited devices. PMID:26551788

  9. The Effects of Popping Popcorn Under Reduced Pressure

    NASA Astrophysics Data System (ADS)

    Quinn, Paul; Cooper, Amanda

    2008-03-01

    In our experiments, we model the popping of popcorn as an adiabatic process and develop a process for improving the efficiency of popcorn production. By lowering the pressure of the popcorn during the popping process, we induce an increase in popcorn size, while decreasing the number of remaining unpopped kernels. In this project we run numerous experiments using three of the most common popping devices, a movie popcorn maker, a stove pot, and a microwave. We specifically examine the effects of varying the pressure on total sample size, flake size and waste. An empirical relationship is found between these variables and the pressure.

  10. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Sweterlitsch, Jeffrey J.

    2013-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by United Technologies Corp. Aerospace Systems (UTAS, formerly Hamilton Sundstrand) and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle (MPCV). In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure testing with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight project computer model predictions with specific operating conditions.

  11. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlisch, Jeffery J.

    2013-01-01

    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 for moderate duration missions of the Orion Multipurpose Crew Vehicle. In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight program computer model predictions with specific operating conditions.

  12. Growing wheat to maturity in reduced gas pressures

    NASA Technical Reports Server (NTRS)

    Rykiel, Edward J., Jr.; Drew, Malcolm C.; Etter, Brad D.

    1993-01-01

    The main objective of this project was to determine assimilation of CO2 and efficiency of water use in wheat grown to maturity in a low pressure total gas pressure environment. A functional test of the low pressure plant growth chamber system was accomplished in February and March of 1993 wherein this objective was partially achieved. Plants were grown to maturity in the chambers. Data were actively collected during the first 29 days. The plants were allowed to maintain themselves at the CO2 compensation point until day 45 of the study at which point active atmospheric regulation was resumed. This provided data at the vegetative and reproductive stages of the life cycle of the plants. However, this information may not be representative of the performance of the plants due to the loss of low pressure on a number of days during the study, which affected the plants by changing the pressure potential of the tissues. The performance of the system will be discussed on a component by component basis. The maintenance of the plants at the CO2 compensation point was driven by the failure of the computer program operating the system. The software problems that arose during the functional test have since been corrected. Results from the functional test also indicated that the plants were not receiving adequate light and nutrients. The growth chambers have been relocated and the growth room modified to compensate for these deficiencies.

  13. Feed system design for a reduced pressure tank

    NASA Technical Reports Server (NTRS)

    Lui, Hurbert

    1994-01-01

    Three designs were considered to satisfy the design objective. These designs were the current design, a Land Based Pressurized Feed System, and a fuel recirculation system. A computer code was developed to analyze the current feed system and assist in the analysis of the two experimental systems. After comparing the three concepts, the land Based Pressurized Feed System seemed to be the most promising new development. This design coupled with the piping configuration described in the report provides a justifiable fuel feed system which satisfies all the necessary requirements.

  14. Health Promotion to Reduce Blood Pressure Level among Older Blacks.

    ERIC Educational Resources Information Center

    Haber, David

    1986-01-01

    Low-income Black elders completed a 10-week health promotion program for the purpose of lowering or stabilizing blood pressure levels. Comparisons were made between classes that met weekly versus three times a week, and between yoga and aerobics formats. A peer-led program was developed that continued for 10 months after the professionally-led…

  15. Demonstration of Reduced Gas Pressure in a Centrifugal Field.

    ERIC Educational Resources Information Center

    Fischer, Fred; Wild, R. L.

    1979-01-01

    Describes a simple demonstration that shows the change in molecular density and the reduction in pressure of air in a centrifugal field. Uses two circular disks with the same radius and rotating with the same angular velocity, in loose mutual contact, around their symmetry axis. (GA)

  16. 95-1 Campaign evaporator boildown results

    SciTech Connect

    Miller, G.L.

    1994-10-10

    The Process Chemistry Laboratories were requested to support the 242-A Evaporator restart as part of the overall 222-S laboratory effort. The net purpose of these studies is to determine the characteristics of double-shell tank materials as they are processed in the evaporator. The results for the boildown study (which includes pressure and temperature versus % waste volume reduction and density of final boildown residue) supporting the 242-A Evaporator restart are reported below. The boildown was performed in a vacuum distillation apparatus with an adjustable vacuum limiting manometer and an isolatable collection graduated cylinder. The boildown was conducted over a seven hour period. The evaporation was done at 60 torr (to avoid excessive foaming and bumping of solution) for approximately half of the boildown, the pressure then being reduced to 40 torr when the reduction in solution volume allowed this to be done. Percent waste volume reduction was measured by observing the amount of condensate collected in a graduated cylinder. As the graduated cylinder became full, it was isolated from the rest of the system and the condensate removed. Pressure was set using an electronic manometer with a low pressure limiter set at the desired level. Temperature was measured using a J-type thermocouple. The apparatus was calibrated by observing the pressure versus temperature response of pure water, and comparing the values thus obtained to published values.

  17. Gravity Effects in Condensing and Evaporating Films

    NASA Technical Reports Server (NTRS)

    Hermanson, J. C.; Som, S. M.; Allen, J. S.; Pedersen, P. C.

    2004-01-01

    A general overview of gravity effects in condensing and evaporating films is presented. The topics include: 1) Research Overview; 2) NASA Recognizes Critical Need for Condensation & Evaporation Research to Enable Human Exploration of Space; 3) Condensation and Evaporation Research in Reduced Gravity is Enabling for AHST Technology Needs; 4) Differing Role of Surface Tension on Condensing/Evaporating Film Stability; 5) Fluid Mechanisms in Condensing and Evaporating Films in Reduced Gravity; 6) Research Plan; 7) Experimental Configurations for Condensing Films; 8) Laboratory Condensation Test Cell; 9) Aircraft Experiment; 10) Condensation Study Current Test Conditions; 11) Diagnostics; 12) Shadowgraph Images of Condensing n- pentane Film in Unstable (-1g) Configuration; 13) Condensing n-Pentane Film in Normal Gravity (-1g) at Constant Pressure; 14) Condensing n-Pentane Film in Normal Gravity (-1g) with Cyclic Pressure; 15) Non-condensing Pumped Film in Normal Gravity (-1g); 16) Heat Transfer Coefficient in Developing, Unstable Condensing Film in Normal Gravity; 17) Heat Transfer for Unsteady Condensing Film (-1g); 18) Ultrasound Measurement of Film Thickness N-pentane Film, Stable (+1g) Configuration; and 19) Ultrasound Measurement of Film Thickness N-pentane Film, Unstable (-1g) Configuration.

  18. Mixed feed evaporator

    DOEpatents

    Vakil, Himanshu B.; Kosky, Philip G.

    1982-01-01

    In the preparation of the gaseous reactant feed to undergo a chemical reaction requiring the presence of steam, the efficiency of overall power utilization is improved by premixing the gaseous reactant feed with water and then heating to evaporate the water in the presence of the gaseous reactant feed, the heating fluid utilized being at a temperature below the boiling point of water at the pressure in the volume where the evaporation occurs.

  19. Laser-induced damage threshold of ZrO{sub 2} thin films prepared at different oxygen partial pressures by electron-beam evaporation

    SciTech Connect

    Zhang Dongping; Shao Jianda; Zhao Yuanan; Fan Shuhai; Hong Ruijing; Fan Zhengxiu

    2005-01-01

    ZrO{sub 2} films were deposited by electron-beam evaporation with the oxygen partial pressure varying from 3x10{sup -3} Pa to 11x10{sup -3} Pa. The phase structure of the samples was characterized by x-ray diffraction (XRD). The thermal absorption of the films was measured by the surface thermal lensing technique. A spectrophotometer was employed to measure the refractive indices of the samples. The laser-induced damage threshold (LIDT) was assessed using a 1064 nm Nd: yttritium-aluminum-garnet pulsed laser at pulse width of 12 ns. The influence of oxygen partial pressure on the microstructure and LIDT of ZrO{sub 2} films was investigated. XRD data revealed that the films changed from polycrystalline to amorphous as the oxygen partial pressure increased. The variation of refractive index at 550 nm wavelength indicated that the packing density of the films decreased gradually with increasing oxygen partial pressure. The absorptance of the samples decreased monotonically from 125.2 to 84.5 ppm with increasing oxygen partial pressure. The damage threshold values increased from 18.5 to 26.7 J/cm{sup 2} for oxygen partial pressures varying from 3x10{sup -3} Pa to 9x10{sup -3} Pa, but decreased to 17.3 J/cm{sup 2} in the case of 11x10{sup -3} Pa.

  20. EXPERIENCE IN REDUCING ELECTRON CLOUD AND DYNAMIC PRESSURE RISE IN WARM AND COLD REGIONS IN RHIC.

    SciTech Connect

    ZHANG, S.Y.; AHRENS,L.; ALLESI, J.; BAI, M.; BLASKIEWICZ, M.; CAMERON, P.; CONNOLLY, R.; DREES, A.; FISCHER, W.; GULLOTTA, J.; HE, P.; HSEUH, H.C.; HUANG, H.; LEE, R.; LITVINENKO, V.; MACKAY, W.W.; MONTAG, C.; NICOLETTI, A.; OERTER, B.; PILAT, F.; PTITSYN, V.; ROSER, T.; SATOGATA, T.; SMART, L.; SYNDSTRUP, L.; TEPIKIAN, S.; THIEBERGER, P.; TRBOJEVIC, D.; WEI, J.; ZENO, K.

    2006-06-23

    The large scale application of non-evaporable getter coating in RHIC has been effective in reducing the electron cloud. Since beams with higher intensity and smaller bunch spacing became possible in operation, the emittance growth is of concern. Study results are reported together with experiences of machine improvements: saturated NEG coatings, anti-grazing ridges in warm sections, and the pre-pumping in cryogenic regions.

  1. Energy-efficient evaporators can cut operating costs for wastewater treatment, reuse

    SciTech Connect

    Kersey, D.

    1996-05-01

    High-efficiency evaporators can substantially lower the costs of recycling water, separating and reducing waste, and reclaiming industrial byproducts. Although capital costs run higher than conventional, stream-driven systems, energy efficient designs can allow users to recoup those costs over time and provide significant, ongoing utility savings. This is especially true in applications in which evaporation requirements are more than 75,000 pounds per hour, and steam costs exceed $3 per 1,000 pounds. In conventional, multistage evaporators, vapor resulting from wastewater evaporation is reused as a heating agent to effect further evaporation, but fresh steam must be added continuously to the system to maintain adequate temperature and pressure--two factors critical to evaporation. In contrast, three energy-efficient designs maintain temperature and pressure by recycling otherwise wasted resources, thereby greatly reducing or eliminating steam costs and other utility expenses.

  2. Rare-gas liquids - Equation of state and reduced-pressure, reduced-bulk-modulus, and reduced-sound-velocity functions

    NASA Technical Reports Server (NTRS)

    Schlosser, Herbert

    1990-01-01

    This paper is concerned with verification of the applicability of the Vinet et al. (1987) universal equation of state to the liquid phase of the rare-gas elements under pressure. As previously observed in solids and liquids metals, to a good approximation, in the absence of phase transitions, plots of the logarithms of the reduced pressure function, of the reduced sound velocity, and of the reduced bulk modulus, are all linear functions of 1 - X over the entire experimental pressure range. The results obtained on the rare-gas liquids are comparable in accuracy to those obtained in previous work on solids and liquid metals.

  3. Noise reducing screen devices for in-flow pressure sensors

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric (Inventor); Liu, Sandy (Inventor); Jaeger, Stephen (Inventor); Horne, W. Clifton (Inventor)

    1997-01-01

    An acoustic sensor assembly is provided for sensing acoustic signals in a moving fluid such as high speed fluid stream. The assembly includes one or more acoustic sensors and a porous, acoustically transparent screen supported between the moving fluid stream and the sensor and having a major surface disposed so as to be tangent to the moving fluid. A layer of reduced velocity fluid separating the sensor from the porous screen. This reduced velocity fluid can comprise substantially still air. A foam filler material attenuates acoustic signals arriving at the assembly from other than a predetermined range of incident angles.

  4. Enhancing Documentation of Pressure Ulcer Prevention Interventions: A Quality Improvement Strategy to Reduce Pressure Ulcers.

    PubMed

    Jacobson, Therese M; Thompson, Susan L; Halvorson, Anna M; Zeitler, Kristine

    2016-01-01

    Prevention of hospital-acquired pressure ulcers requires the implementation of evidence-based interventions. A quality improvement project was conducted to provide nurses with data on the frequency with which pressure ulcer prevention interventions were performed as measured by documentation. Documentation reports provided feedback to stakeholders, triggering reminders and reeducation. Intervention reports and modifications to the documentation system were effective both in increasing the documentation of pressure ulcer prevention interventions and in decreasing the number of avoidable hospital-acquired pressure ulcers. PMID:26863048

  5. Optic Nerve Head Blood Flow Response to Reduced Ocular Perfusion Pressure by alteration of either the Blood Pressure or Intraocular Pressure

    PubMed Central

    Wang, Lin; Cull, Grant A; Fortune, Brad

    2015-01-01

    Purpose To test the hypothesis that blood flow autoregulation in the optic nerve head has less reserve to maintain normal blood flow in the face of blood pressure-induced ocular perfusion pressure decrease than a similar magnitude intraocular pressure-induced ocular perfusion pressure decrease. Materials and Methods Twelve normal nonhuman primates were anesthetized by continuous intravenous infusion of pentobarbital. Optic nerve blood flow was monitored by laser speckle flowgraphy. In the first group of animals (n=6), the experimental eye intraocular pressure was maintained at 10 mmHg using a saline reservoir connected to the anterior chamber. The blood pressure was gradually reduced by a slow injection of pentobarbital. In the second group (n=6), the intraocular pressure was slowly increased from 10 mmHg to 50 mmHg by raising the reservoir. In both experimental groups, optic nerve head blood flow was measured continuously. The blood pressure and intraocular pressure were simultaneously recorded in all experiments. Results The optic nerve head blood flow showed significant difference between the two groups (P = 0.021, repeat measures analysis of variance). It declined significantly more in the blood pressure group compared to the intraocular pressure group when the ocular perfusion pressure was reduced to 35 mmHg (P<0.045) and below. There was also a significant interaction between blood flow changes and the ocular perfusion pressure treatment (P=0.004, adjusted Greenhouse & Geisser univariate test), indicating the gradually enlarged blood flow difference between the two groups was due to the ocular perfusion pressure decrease. Conclusions The results show that optic nerve head blood flow is more susceptible to an ocular perfusion pressure decrease induced by lowering the blood pressure compared with that induced by increasing the intraocular pressure. This blood flow autoregulation capacity vulnerability to low blood pressure may provide experimental evidence

  6. Low-Temperature Synthesis of Nanoparticles in the Process of Evaporation of Femtoliter Droplets of a Solution at a Low Pressure

    NASA Astrophysics Data System (ADS)

    Penyazkov, O. G.; Saverchenko, V. I.; Fisenko, S. P.

    2014-07-01

    Results of an X-ray phase analysis of the products of the low-temperature spray pyrolysis of femtoliter droplets of aqueous nickel-chloride solutions are presented. It is shown that the composition of the nanoparticles accumulated on the electrode-substrate in an aerosol reactor depends on the pressure in it and the initial supersaturation of the solution. It was established that marked chemical transformations of the indicated droplets begin at a pressure lower than 80 Torr. The influence of the evaporation of droplets from a solution and the nucleation in the supersaturated solution formed on the kinetics of the chemical transformations of these droplets, giving rise to the substances obtained in the experiments, is discussed.

  7. Conductance enhancement due to interface magnons in electron-beam evaporated MgO magnetic tunnel junctions with CoFeB free layer deposited at different pressure

    SciTech Connect

    Guo, P.; Yu, G. Q.; Wei, H. X.; Han, X. F. E-mail: xfhan@aphy.iphy.ac.cn; Li, D. L.; Feng, J. F. E-mail: xfhan@aphy.iphy.ac.cn; Kurt, H.; Chen, J. Y.; Coey, J. M. D.

    2014-10-21

    Electron-beam evaporated MgO-based magnetic tunnel junctions have been fabricated with the CoFeB free layer deposited at Ar pressure from 1 to 4 mTorr, and their tunneling process has been studied as a function of temperature and bias voltage. By changing the growth pressure, the junction dynamic conductance dI/dV, inelastic electron tunneling spectrum d²I/dV², and tunneling magnetoresistance vary with temperature. Moreover, the low-energy magnon cutoff energy E{sub C} derived from the conductance versus temperature curve agrees with interface magnon energy obtained directly from the inelastic electron tunneling spectrum, which demonstrates that interface magnons are involved in the electron tunneling process, opening an additional conductance channel and thus enhancing the total conductance.

  8. Electronic SSKIN pathway: reducing device-related pressure ulcers.

    PubMed

    Campbell, Natalie

    2016-08-11

    This article describes how an interprofessional project in a London NHS Foundation Trust was undertaken to develop an intranet-based medical device-related pressure ulcer prevention and management pathway for clinical staff working across an adult critical care directorate, where life-threatening events require interventions using medical devices. The aim of this project was to improve working policies and processes to define key prevention strategies and provide clinicians with a clear, standardised approach to risk and skin assessment, equipment use, documentation and reporting clinical data using the Trust's CareVue (electronic medical records), Datix (incident reporting and risk-management tool) and eTRACE (online clinical protocol ordering) systems. The process included the development, trial and local implementation of the pathway using collaborative teamwork and the SSKIN care bundle tool. The experience of identifying issues, overcoming challenges, defining best practice and cascading SSKIN awareness training is shared. PMID:27523768

  9. Interannual to Decadal Variability of Ocean Evaporation as Viewed from Climate Reanalyses

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Bosilovich, Michael G.; Roberts, Jason B.; Wang, Hailan

    2015-01-01

    Questions we'll address: Given the uncoupled framework of "AMIP" (Atmosphere Model Inter-comparison Project) experiments, what can they tell us regarding evaporation variability? Do Reduced Observations Reanalyses (RedObs) using Surface Fluxes and Clouds (SFC) pressure (and wind) provide a more realistic picture of evaporation variability? What signals of interannual variability (e.g. El Nino/Southern Oscillation (ENSO)) and decadal variability (Interdecadal Pacific Oscillation (IPO)) are detectable with this hierarchy of evaporation estimates?

  10. Experimental two-phase pressure gradients during evaporation of pure and mixed refrigerants in a smooth horizontal tube. Comparison with correlations

    NASA Astrophysics Data System (ADS)

    Greco, A.; Vanoli, G. P.

    2006-06-01

    The paper reports the results of an experimental study on pressure drop during horizontal flow boiling of refrigerants R22, R507, R404A, R134a, R407C and R410A. The test section is a smooth, horizontal, stainless steel tube (6 mm I.D., 6 m length) uniformly heated by Joule effect. The experimental tests are carried out at an almost constant evaporating pressure of 7.0 bar varying the mass flow rate in the range 280 1,080 kg/m2 s. The experimental comparison clearly shown that the pressure drop of R22 is significantly higher as compared to all the other fluids. The results are compared against well-known pressure drop prediction methods. The available correlations can be used for both pure fluids and mixtures with no corrective factors, provided the mixture properties are evaluated at local compositions. The Chawla friction correlation is the best-fitting of our experimental data in combination with the heterogeneous momentum pressure drop model on the basis of the Rouhani-Axelsson void fraction correlation.

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

    SciTech Connect

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

    1999-03-08

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

  12. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes.

    PubMed

    Martinez, N; Michoud, G; Cario, A; Ollivier, J; Franzetti, B; Jebbar, M; Oger, P; Peters, J

    2016-01-01

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure. PMID:27595789

  13. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    PubMed Central

    Martinez, N.; Michoud, G.; Cario, A.; Ollivier, J.; Franzetti, B.; Jebbar, M.; Oger, P.; Peters, J.

    2016-01-01

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure. PMID:27595789

  14. High pressure processing alters water distribution enabling the production of reduced-fat and reduced-salt pork sausages.

    PubMed

    Yang, Huijuan; Han, Minyi; Bai, Yun; Han, Yanqing; Xu, Xinglian; Zhou, Guanghong

    2015-04-01

    High pressure processing (HPP) was used to explore novel methods for modifying the textural properties of pork sausages with reduced-salt, reduced-fat and no fat replacement additions. A 2×7 factorial design was set up, incorporating two pressure levels (0.1 or 200 MPa) and seven fat levels (0, 5, 10, 15, 20, 25 and 30%). Sausages treated at 200 MPa exhibited improved tenderness at all fat levels compared with 0.1 MPa treated samples, and the shear force of sausages treated at 200 MPa with 15 or 20% fat content was similar to the 0.1 MPa treated sausages with 30% fat. HPP significantly changed the P₂ peak ratio of the four water components in raw sausages, resulting in improved textural properties of emulsion-type sausages with reduced-fat and reduced-salt. Significant correlations were found between pH, color, shear force and water proportions. The scanning and transmission micrographs revealed the formation of smaller fat globules and an improved network structure in the pressure treated sausages. In conclusion, there is potential to manufacture sausages with reduced-fat and reduced-salt by using HPP to maintain textural qualities. PMID:25553411

  15. Evaporation dynamics of femtoliter water capillary bridges

    NASA Astrophysics Data System (ADS)

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Kim, Jung Gu; Weon, Byung Mook

    2015-11-01

    Capillary bridges are usually formed by a small liquid volume in confined space between two solid surfaces and particularly they have lower internal pressure than 1 atm at femtoliter scales. Femtoliter capillary bridges exhibit rapid evaporation rates. To quantify detailed evaporation kinetics of femtoliter bridges, we present a feasible protocol to directly visualize femtoliter water bridges that evaporate in still air between a microsphere and a flat substrate by utilizing transmission X-ray microscopy. Precise measurements of evaporation kinetics for water bridges indicate that lower water pressure than 1 atm can significantly decelerate evaporation by suppression of vapor diffusion. This finding would provide a consensus to understand evaporation of ultrasmall capillary bridges.

  16. Infrared thermography of evaporative fluxes and dynamics of salt deposition on heterogeneous porous surfaces

    NASA Astrophysics Data System (ADS)

    Nachshon, Uri; Shahraeeni, Ebrahim; Or, Dani; Dragila, Maria; Weisbrod, Noam

    2011-12-01

    Evaporation of saline solutions from porous media, common in arid areas, involves complex interactions between mass transport, energy exchange and phase transitions. We quantified evaporation of saline solutions from heterogeneous sand columns under constant hydraulic boundary conditions to focus on effects of salt precipitation on evaporation dynamics. Mass loss measurements and infrared thermography were used to quantify evaporation rates. The latter method enables quantification of spatial and temporal variability of salt precipitation to identify its dynamic effects on evaporation. Evaporation from columns filled with texturally-contrasting sand using different salt solutions revealed preferential salt precipitation within the fine textured domains. Salt precipitation reduced evaporation rates from the fine textured regions by nearly an order of magnitude. In contrast, low evaporation rates from coarse-textured regions (due to low capillary drive) exhibited less salt precipitation and consequently less evaporation rate suppression. Experiments provided insights into two new phenomena: (1) a distinct increase in evaporation rate at the onset of evaporation; and (2) a vapor pumping mechanism related to the presence of a salt crust over semidry media. Both phenomena are related to local vapor pressure gradients established between pore water and the surface salt crust. Comparison of two salts: NaCl and NaI, which tend to precipitate above the matrix surface and within matrix pores, respectively, shows a much stronger influence of NaCl on evaporation rate suppression. This disparity reflects the limited effect of NaI precipitation on matrix resistivity for solution and vapor flows.

  17. Choking under monitoring pressure: being watched by the experimenter reduces executive attention.

    PubMed

    Belletier, Clément; Davranche, Karen; Tellier, Idriss S; Dumas, Florence; Vidal, Franck; Hasbroucq, Thierry; Huguet, Pascal

    2015-10-01

    Performing more poorly given one's skill level ("choking") is likely in situations that offer an incentive if a certain outcome is achieved (outcome pressure) or when one is being watched by others-especially when one's performance is being evaluated (monitoring pressure). According to the choking literature, outcome pressure is associated with reduced executive control of attention, whereas monitoring pressure is associated with increased, yet counterproductive, attention to skill processes. Here, we show the first evidence that monitoring pressure-being watched by the experimenter-may lead individuals with higher working memory to choke on a classic measure of executive control-just the task effect thought to result from outcome pressure. Not only does this finding help refine our understanding of the processes underlying choking under monitoring pressure, but it also leads to a new look at classic audience effects, with an important implication for experimental psychology. PMID:25673216

  18. Observation of antibacterial effects obtained at atmospheric and reduced pressures in afterglow conditions

    NASA Astrophysics Data System (ADS)

    Sarrette, J.-P.; Cousty, S.; Merbahi, N.; Nègre-Salvayre, A.; Clément, F.

    2010-01-01

    Bactericidal activities of three different afterglows operating at reduced and atmospheric pressures and ambient temperature are established and compared through the use of a unique protocol for bacteria (E. coli, CIP 54.8 T) exposition, recovery and numeration. The influence of three important parameters is shown. An original scenario for bacterial inactivation at reduced pressure is proposed, compatible with previously published results and with the observation of conformational changes appearing on the treated bacteria.

  19. A phylogenetic approach to total evaporative water loss in mammals.

    PubMed

    Van Sant, Matthew J; Oufiero, Christopher E; Muñoz-Garcia, Agustí; Hammond, Kimberly A; Williams, Joseph B

    2012-01-01

    Maintaining appropriate water balance is a constant challenge for terrestrial mammals, and this problem can be exacerbated in desiccating environments. It has been proposed that natural selection has provided desert-dwelling mammals physiological mechanisms to reduce rates of total evaporative water loss. In this study, we evaluated the relationship between total evaporative water loss and body mass in mammals by using a recent phylogenetic hypothesis. We compared total evaporative water loss in 80 species of arid-zone mammals to that in 56 species that inhabit mesic regions, ranging in size from 4 g to 3,500 kg, to test the hypothesis that mammals from arid environments have lower rates of total evaporative water loss than mammals from mesic environments once phylogeny is taken into account. We found that arid species had lower rates of total evaporative water loss than mesic species when using a dichotomous variable to describe habitat (arid or mesic). We also found that total evaporative water loss was negatively correlated with the average maximum and minimum environmental temperature as well as the maximum vapor pressure deficit of the environment. Annual precipitation and the variable Q (a measure of habitat aridity) were positively correlated with total evaporative water loss. These results support the hypothesis that desert-dwelling mammals have lower rates of total evaporative water loss than mesic species after controlling for body mass and evolutionary relatedness regardless of whether categorical or continuous variables are used to describe habitat. PMID:22902381

  20. Does pulmonary rehabilitation reduce peripheral blood pressure in patients with chronic obstructive pulmonary disease?

    PubMed

    Canavan, Jane L; Kaliaraju, Djeya; Nolan, Claire M; Clark, Amy L; Jones, Sarah E; Kon, Samantha S C; Polkey, Michael I; Man, William D-C

    2015-08-01

    Pulmonary rehabilitation (PR) can improve aerobic exercise capacity, health-related quality of life and dyspnoea in patients with chronic obstructive pulmonary disease (COPD). Recent studies have suggested that exercise training may improve blood pressure and arterial stiffness, albeit in small highly selected cohorts. The aim of the study was to establish whether supervised outpatient or unsupervised home PR can reduce peripheral blood pressure. Resting blood pressure was measured in 418 patients with COPD before and after outpatient PR, supervised by a hospital-based team (HOSP). Seventy-four patients with COPD undergoing an unsupervised home-based programme acted as a comparator group (HOME). Despite significant improvements in mean (95% confidence interval) exercise capacity in the HOSP group (56 (50-60) m, p < 0.001) and HOME group (30 (17-42) m, p < 0.001) systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) did not change in either the HOSP (SBP: p = 0.47; DBP: p = 0.06; MAP: p = 0.38) or HOME group (SBP: p = 0.67; DBP: p = 0.38; MAP: p = 0.76). Planned subgroup analysis of HOSP patients with known hypertension and/or cardiovascular disease showed no impact of PR upon blood pressure. PR is unlikely to reduce blood pressure, and by implication, makes a mechanism of action in which arterial stiffness is reduced, less likely. PMID:26015460

  1. Vacuum-assisted headspace solid phase microextraction: improved extraction of semivolatiles by non-equilibrium headspace sampling under reduced pressure conditions.

    PubMed

    Psillakis, Elefteria; Yiantzi, Evangelia; Sanchez-Prado, Lucia; Kalogerakis, Nicolas

    2012-09-12

    A new headspace solid-phase microextraction (HSSPME) procedure carried out under vacuum conditions is proposed here where sample volumes commonly used in HSSPME (9 mL) were introduced into pre-evacuated commercially available large sampling chambers (1000 mL) prior to HSSPME sampling. The proposed procedure ensured reproducible conditions for HSSPME and excluded the possibility of analyte losses. A theoretical model was formulated demonstrating for the first time the pressure dependence of HSSPME sampling procedure under non equilibrium conditions. Although reduced pressure conditions during HSSPME sampling are not expected to increase the amount of analytes extracted at equilibrium, they greatly increase extraction rates compared to HSSPME under atmospheric pressure due to the enhancement of evaporation rates in the presence of an air-evacuated headspace. The effect is larger for semivolatiles whose evaporation rates are controlled by mass transfer resistance in the thin gas film adjacent to the sample/headspace interface. Parameters that affect HSSPME extraction were investigated under both vacuum and atmospheric conditions and the experimental data obtained were used to discuss and verify the theory. The use of an excessively large headspace volume was also considered. The applicability of Vac-HSSPME was assessed using chlorophenols as model compounds yielding linearities better than 0.9915 and detection limits in the low-ppt level. The repeatability was found to vary from 3.1 to 8.6%. PMID:22884204

  2. Local charge transport properties of hydrazine reduced monolayer graphene oxide sheets prepared under pressure condition

    SciTech Connect

    Ryuzaki, Sou Meyer, Jakob A. S.; Petersen, Søren; Nørgaard, Kasper; Hassenkam, Tue; Laursen, Bo W.

    2014-09-01

    Charge transport properties of chemically reduced graphene oxide (RGO) sheets prepared by treatment with hydrazine were examined using conductive atomic force microscopy. The current-voltage (I-V) characteristics of monolayer RGO sheets prepared under atmospheric pressure followed an exponentially increase due to 2D variable-range hopping conduction through small graphene domains in an RGO sheet containing defect regions of residual sp{sup 3} carbon clusters bonded to oxygen groups, whereas RGO sheets prepared in a closed container under moderate pressure showed linear I-V characteristics with a conductivity of 267.2−537.5 S/m. It was found that the chemical reduction under pressure results in larger graphene domains (sp{sup 2} networks) in the RGO sheets when compared to that prepared under atmospheric pressure, indicating that the present reduction of GO sheets under the pressure is one of the effective methods to make well-reduced GO sheets.

  3. A refinement of the combination equations for evaporation

    USGS Publications Warehouse

    Milly, P.C.D.

    1991-01-01

    Most combination equations for evaporation rely on a linear expansion of the saturation vapor-pressure curve around the air temperature. Because the temperature at the surface may differ from this temperature by several degrees, and because the saturation vapor-pressure curve is nonlinear, this approximation leads to a certain degree of error in those evaporation equations. It is possible, however, to introduce higher-order polynomial approximations for the saturation vapor-pressure curve and to derive a family of explicit equations for evaporation, having any desired degree of accuracy. Under the linear approximation, the new family of equations for evaporation reduces, in particular cases, to the combination equations of H. L. Penman (Natural evaporation from open water, bare soil and grass, Proc. R. Soc. London, Ser. A193, 120-145, 1948) and of subsequent workers. Comparison of the linear and quadratic approximations leads to a simple approximate expression for the error associated with the linear case. Equations based on the conventional linear approximation consistently underestimate evaporation, sometimes by a substantial amount. ?? 1991 Kluwer Academic Publishers.

  4. Product PCNPsurv or the "reduced" evaporation residue cross section σER/σfusion for "hot" fusion reactions studied with the dynamical cluster-decay model

    NASA Astrophysics Data System (ADS)

    Chopra, Sahila; Kaur, Arshdeep; Hemdeep, Gupta, Raj K.

    2016-04-01

    The product PCNPsurv of compound nucleus (CN) fusion probability PCN and survival probability Psurv is calculated to determine the reduced evaporation residue cross section σER/σfusion , denoted σERreduced, with (total) fusion cross section σfusion given as a sum of CN-formation cross section σCN and non-CN cross section σnCN for each reaction, where σCN is the sum of evaporation residue cross section σER and fusion-fission cross section σff and σnCN, if not measured, is estimated empirically as the difference between measured and calculated σfusion. Our calculations of PCN and Psurv, based on the dynamical cluster-decay model, were successfully made for some 17 "hot" fusion reactions, forming different CN of mass numbers ACN˜100 -300 , with deformations of nuclei up to hexadecapole deformations and "compact" orientations for both coplanar (Φc=0∘ ) and noncoplanar (Φc≠0∘ ) configurations, using various different nuclear interaction potentials. Interesting variations of σERreduced with CN excitation energy E*, fissility parameter χ , CN mass ACN, and Coulomb parameter Z1Z2 show that, independent of entrance channel, different isotopes of CN, and nuclear interaction potentials used, the dominant quantity in the product is Psurv, which classifies all the studied CN into three groups of weakly fissioning, radioactive, and strongly fissioning superheavy nuclei, with relative magnitudes of σERreduced˜1 , ˜10-6 , and ˜10-11 , which, like for PCN, get further grouped in two dependencies of (i) weakly fissioning and strongly fissioning superheavy nuclei decreasing with increasing E* and (ii) radioactive nuclei increasing with increasing E*.

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

    SciTech Connect

    Choi, B.J.

    1999-12-01

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

  6. Evaporating firewalls

    NASA Astrophysics Data System (ADS)

    Van Raamsdonk, Mark

    2014-11-01

    In this note, we begin by presenting an argument suggesting that large AdS black holes dual to typical high-energy pure states of a single holographic CFT must have some structure at the horizon, i.e. a fuzzball/firewall, unless the procedure to probe physics behind the horizon is state-dependent. By weakly coupling the CFT to an auxiliary system, such a black hole can be made to evaporate. In a case where the auxiliary system is a second identical CFT, it is possible (for specific initial states) that the system evolves to precisely the thermofield double state as the original black hole evaporates. In this case, the dual geometry should include the "late-time" part of the eternal AdS black hole spacetime which includes smooth spacetime behind the horizon of the original black hole. Thus, if a firewall is present initially, it evaporates. This provides a specific realization of the recent ideas of Maldacena and Susskind that the existence of smooth spacetime behind the horizon of an evaporating black hole can be enabled by maximal entanglement with a Hawking radiation system (in our case the second CFT) rather than prevented by it. For initial states which are not finely-tuned to produce the thermofield double state, the question of whether a late-time infalling observer experiences a firewall translates to a question about the gravity dual of a typical high-energy state of a two-CFT system.

  7. Combined non-adaptive light and smell stimuli lowered blood pressure, reduced heart rate and reduced negative affect.

    PubMed

    Dong, Shan; Jacob, Tim J C

    2016-03-15

    Bright light therapy has been shown to have a positive impact on seasonal affective disorder (SAD), depression and anxiety. Smell has also has been shown to have effects on mood, stress, anxiety and depression. The objective of this study was to investigate the effect of the combination of light and smell in a non-adaptive cycle. Human subjects were given smell (lemon, lavender or peppermint) and light stimuli in a triangular wave (60scycle) for 15min. Blood pressure and heart rate were monitored before and after each session for 5 consecutive days and a Profile of Mood States (POMS) test was administered before and after the sensory stimulation on days 1, 3 and 5. The light-smell stimulus lowered blood pressure, both systolic and diastolic, and reduced heart rate for all odours compared to control. Of the two sensory stimuli, the odour stimulus contributed most to this effect. The different aromas in the light-smell combinations could be distinguished by their different effects on the mood factors with lemon inducing the greatest mood changes in Dejection-Depression, Anger-Hostility, Tension-Anxiety. In conclusion, combined light and smell stimulation was effective in lowering blood pressure, reducing heart rate and improving mood. The combination was more effective than either smell or light stimuli alone, suggesting that a light-smell combination would be a more robust and efficacious alternative treatment for depression, anxiety and stress. PMID:26780148

  8. Numerical Simulation of Flow-Induced Noise in High Pressure Reducing Valve

    PubMed Central

    Wei, Lin; Zhu, Guorong; Qian, Jinyuan; Fei, Yang; Jin, Zhijiang

    2015-01-01

    The main objective of this paper is to study the characteristics of flow-induced noise in high pressure reducing valve (HPRV) and to provide some guidance for noise control. Based on computational fluid dynamics (CFD), numerical method was used to compute flow field. Ffowcs Williams and Hawkings Model was applied to obtain acoustic signals. The unsteady flow field shows that noise sources are located at the bottom of plug for valve without perforated plate, and noise sources are behind the plate for valve with perforated plate. Noise directivity analysis and spectrum characteristics indicate that the perforated plate could help to reduce noise effectively. Inlet pressure has great effects on sound pressure level (SPL). The higher inlet pressure will lead to larger SPL at high frequency. When the maximum Ma is close to 1, SPL at low frequency becomes very high. PMID:26061396

  9. Innovative, High-Pressure, Cryogenic Control Valve: Short Face-to-Face, Reduced Cost

    NASA Technical Reports Server (NTRS)

    Wilkes, Karlin; Larsen, Ed; McCourt, Jackson

    2003-01-01

    A control valve that can throttle high-pressure cryogenic fluid embodies several design features that distinguish it over conventional valves designed for similar applications. Field and design engineers worked together to create a valve that would simplify installation, trim changes, and maintenance, thus reducing overall cost. The seals and plug stem packing were designed to perform optimally in cryogenic temperature ranges. Unlike conventional high-pressure cryogenic valves, the trim size can be changed independent of the body.

  10. Flammability limits of hydrated and anhydrous ethanol at reduced pressures in aeronautical applications.

    PubMed

    Coronado, Christian J R; Jr, João A Carvalho; Andrade, José C; Mendiburu, Andrés Z; Cortez, Ely V; Carvalho, Felipe S; Gonçalves, Beatriz; Quintero, Juan C; Velásquez, Elkin I Gutiérrez; Silva, Marcos H; Santos, José C; Nascimento, Marco A R

    2014-09-15

    There is interest in finding the flammability limits of ethanol at reduced pressures for the future use of this biofuel in aeronautical applications taking into account typical commercial aviation altitude (<40,000 ft). The lower and upper flammability limits (LFL and UFL, respectively) for hydrated ethanol and anhydrous ethanol (92.6% and 99.5% p/p, respectively) were determined for a pressure of 101.3 kPa at temperatures between 0 and 200°C. A heating chamber with a spherical 20-l vessel was used. First, LFL and the UFL were determined as functions of temperature and atmospheric pressure to compare results with data published in the scientific literature. Second, after checking the veracity of the data obtained for standard atmospheric pressure, the work proceeded with reduced pressures in the same temperature range. 295 experiments were carried out in total; the first 80 were to calibrate the heating chamber and compare the results with those given in the published scientific literature. 215 experiments were performed both at atmospheric and reduced pressures. The results had a correlation with the values obtained for the LFL, but values for the UFL had some differences. With respect to the water content in ethanol, it was shown that the water vapor contained in the fuel can act as an inert substance, narrowing flammability. PMID:25151240

  11. Numerical simulation analysis and optimum design for combined type pressure reducing valves

    NASA Astrophysics Data System (ADS)

    Gou, D. M.; Guo, P. C.; Zheng, X. B.; Luo, X. Q.; Sun, L. G.

    2016-05-01

    Pressure reducing valve is an extremely significant equipment of energy dissipation for the water supply by gravity with pressure reducing technology in hydropower stations, and which has a pronounced effect on the normal technical water supply even safety operation for the hydropower units. A three-dimensional numerical calculation of flow field and cavitation characteristics towards a combined type pressure reducing valves was carried out based on the system of technical water supply in this paper. The numerical results show that the investigated valve could meet the requirements of technological supply water pressure and great pressure loss was caused when the water flow was accelerated by narrow overflowing section between throttling cone and valve seat. At working operation, obvious cavitation phenomenon was observed on the surface of throttling cone, and the maximum volume fraction of vapor reached 0.537%. Based on above researches, this paper introduces an optimization model for profile line design of throttling cone. The optimal results show that the cavitation performance is effectively improved with identical pressure drop compared with original results.

  12. Reduced Pressure Alone Does Not Affect the Overall Sensory and Antioxidant Values of Radish

    NASA Astrophysics Data System (ADS)

    Levine, L. H.; Bisbee, P.; Yorio, N. C.; Stutte, G. W.; Richards, J. T.; Birmele, M.; Prior, R. L.; Perchonok, M.; Wheeler, R. M.; Dixon, M.

    Use of reduced atmospheric pressures e g 101 kPa for space exploration can offer several advantages during long duration space missions including reduced launch mass for containment vessels reduced gas leakage reduced resupply costs and increased potential for using transparent materials in greenhouses for a bioregenerative life support system on Mars and on the Moon Limited testing with crop plants at reduced atmospheres has been conducted with results focused on whole plant growth and gas exchange but there are no studies regarding the quality of resulting products This question is of importance not only from the standpoint of food palatability but of potential nutritional and health benefits to the crew To study this we grew radish Raphanus sativus L cv Cherry Bomb Hybrid II plants at three atmospheric pressures 33 kPa 66 kPa and 96 kPa nominal ambient while maintaining oxygen and carbon dioxide partial pressures constant at 21 kPa and 0 12 kPa respectively After 21 days growth chambers were repressurized and ten plants were harvested within the same time frame of the photoperiod for all three pressure treatments The experiment was repeated three times Arial shoots and storage roots were separated immediately upon removal from growth chambers frozen with liquid nitrogen and stored at -80 r C until analysis Six of the ten plants were lyophilized ground to pass a 40 mesh screen and used for determination of the total antioxidant capacity and glucosinolate composition while the remaining four plants were used

  13. Streamer Evaporation

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Wang, A.-H.; Wu, S. T.; Nerney, S. F.

    1998-01-01

    Evaporation is the consequence of heating near the top of streamers in ideal Magnetohydrodynamics (MHD) models, where the plasma is weakly contained by the magnetic field. Heating causes slow opening of field lines and release of new solar wind. It was discovered in simulations and, due to the absence of loss mechanisms, the ultimate end point is the complete evaporation of the streamer. Of course streamers do not behave in this way because there are losses by thermal conduction and radiation. Physically, heating is also expected to depend on ambient conditions. We use our global MHD model with thermal conduction to examine the effect of changing the heating scale height. We also apply and extend an analytic model of streamers developed by Pneuman (1968) to show that steady streamers are unable to contain plasma for temperatures near the cusp greater than approximately 2 x 10(exp 6) K.

  14. Group evaporation

    NASA Technical Reports Server (NTRS)

    Shen, Hayley H.

    1991-01-01

    Liquid fuel combustion process is greatly affected by the rate of droplet evaporation. The heat and mass exchanges between gas and liquid couple the dynamics of both phases in all aspects: mass, momentum, and energy. Correct prediction of the evaporation rate is therefore a key issue in engineering design of liquid combustion devices. Current analytical tools for characterizing the behavior of these devices are based on results from a single isolated droplet. Numerous experimental studies have challenged the applicability of these results in a dense spray. To account for the droplets' interaction in a dense spray, a number of theories have been developed in the past decade. Herein, two tasks are examined. One was to study how to implement the existing theoretical results, and the other was to explore the possibility of experimental verifications. The current theoretical results of group evaporation are given for a monodispersed cluster subject to adiabatic conditions. The time evolution of the fluid mechanic and thermodynamic behavior in this cluster is derived. The results given are not in the form of a subscale model for CFD codes.

  15. Evaporation of Liquid Droplet in Nano and Micro Scales from Statistical Rate Theory.

    PubMed

    Duan, Fei; He, Bin; Wei, Tao

    2015-04-01

    The statistical rate theory (SRT) is applied to predict the average evaporation flux of liquid droplet after the approach is validated in the sessile droplet experiments of the water and heavy water. The steady-state experiments show a temperature discontinuity at the evaporating interface. The average evaporation flux is evaluated by individually changing the measurement at a liquid-vapor interface, including the interfacial liquid temperature, the interfacial vapor temperature, the vapor-phase pressure, and the droplet size. The parameter study shows that a higher temperature jump would reduce the average evaporation flux. The average evaporation flux can significantly be influenced by the interfacial liquid temperature and the vapor-phase pressure. The variation can switch the evaporation into condensation. The evaporation flux is found to remain relative constant if the droplet is larger than a micro scale, while the smaller diameters in nano scale can produce a much higher evaporation flux. In addition, a smaller diameter of droplets with the same liquid volume has a larger surface area. It is suggested that the evaporation rate increases dramatically as the droplet shrinks into nano size. PMID:26353528

  16. On the role of physiochemical properties on evaporation behavior of DISI biofuel sprays

    NASA Astrophysics Data System (ADS)

    Knorsch, Tobias; Heldmann, Markus; Zigan, Lars; Wensing, Michael; Leipertz, Alfred

    2013-06-01

    Biofuels and alternative fuels are increasingly being blended to conventional gasoline fuel to reduce the overall CO2 emissions. The effect on NOx and soot formation is still unclear as the atomization and evaporation of gasoline with biocomponents differ depending on fuel specific physiochemical properties. This work focuses on describing the biofuel evaporation behavior of gasoline sprays at homogeneous charge (early injection timing) and stratified-charge conditions (late injection timing mode) used in modern direct injection spark ignition engines (DISI). A spray plume of a 6-hole solenoid injector is analyzed in terms of liquid spray propagation, and local droplet sizes studied in an injection chamber. Depending on the operating conditions, different physiochemical properties are found to dominate the atomization and evaporation processes: For low and moderate ambient temperature and pressure, high-boiling point components show a strong influence on the spray droplet size distribution. However, at elevated temperature and pressure, the evaporation behavior changes completely. Due to a high degree of evaporation, the evaporation cooling effect dominates the local droplet sizes. Fuel mixtures owing a larger heat of vaporization show larger droplet sizes—even if these fuels have a lower boiling point. Depending on the local evaporation behavior, the different remaining droplet momentum in the spray controls the air entrainment and the subsequent progress of evaporation and mixing. Overall, it can be stated that the heat of vaporization is a dominating physiochemical property for the droplet evaporation rate at high-level supercharged conditions.

  17. Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels

    NASA Astrophysics Data System (ADS)

    Paine, Jeffrey S.; Rogers, Craig A.

    1995-05-01

    Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R/h < 15) vessels are required. For efficient material use in composite material vessels, the radial dilation (expansion or swelling) of the composite vessel can often approach values nearing 2 percent of the diameter. Over long periods of internal pressure loading over elevated temperatures, composite material cylinders may also experience substantial creep. The short term dilation and long term creep are not problematic for applications requiring only the containment of the pressurized fluid. In applications where metallic liners are required, however, substantial dilation and creep causes plastic yielding which leads to reduced fatigue life. To applications such as a hydraulic accumulator, where a piston is employed to fit and seal the fluid in the composite cylinder, the dilation and creep may allow leakage and pressure loss around the piston. A concept called the adaptive composite cylinder is experimentally presented. Shape memory alloy wire in epoxy resin is wrapped around or within polymer matrix composite cylinders to reduce radial dilation of the cylinder. Experimental results are presented that demonstrate the ability of the SMA wire layers to reduce radial dilation. Results from experimental testing of the recovery stress fatigue response of nitinol shape memory alloy wires is also presented.

  18. Use of microwave-assisted evaporation for the complete recovery of volatile species of inorganic trace analytes

    PubMed

    Link; Kingston

    2000-07-01

    Solutions must often be evaporated prior to analysis either to preconcentrate the analyte or to eliminate an incompatible matrix component. Elimination of the halogen-based acids HCI and HF using traditional evaporation methods poses recovery problems because of volatilization of the target analyte as the chloride or fluoride species. A new sample preparation chemistry for trace analysis, where losses of analyte due to volatilization during the evaporation process are minimized, is explored using the unique heating mechanisms of the microwave-assisted evaporation process. The heating mechanisms of hot plate evaporation and microwave-assisted evaporation are compared, and temperatures throughout the evaporation process using each method are predicted and experimentally verified. Because the solution actually cools during microwave-assisted evaporation, volatilization due to overheating at dryness is minimized. Elemental standard solutions and SRM soil and tissue digestates were evaporated using a hot plate method and a newly developed reduced-pressure microwave-assisted evaporation apparatus. Redissolution and analysis of the residue by ICPMS showed that complete recovery was achieved using microwave-assisted evaporation while losses of several classically volatile analytes occurred using hot plate evaporation. PMID:10905326

  19. Adiabatically reduced magnetohydrodynamic equations for a cylindrical plasma with an anisotropic pressure

    SciTech Connect

    Nebogatov, V. A.; Pastukhov, V. P.

    2013-06-15

    A closed set of reduced equations describing low-frequency nonlinear flute magnetohydrodynamic (MHD) convection and the resulting nondiffusive processes of particle and energy transport in a weakly collisional cylindrical plasma with an anisotropic pressure is derived. The Chew-Goldberger-Low anisotropic magnetohydrodynamics is used as the basic dynamic model, because this model is applicable to describing flute convection in a cylindrical plasma column even in the low-frequency limit. The reduced set of equations was derived using the method of adiabatic separation of fast and slow motions. It is shown that the structure of the adiabatic transformation and the corresponding velocity field are identical to those obtained earlier in the isotropic MHD model. However, the derived heat transfer equations differ drastically from the isotropic pressure model. In particular, they indicate a tendency toward maintaining different radial profiles of the longitudinal and transverse pressures.

  20. A Sharp-Interface Immersed Boundary Method with Improved Mass Conservation and Reduced Spurious Pressure Oscillations.

    PubMed

    Seo, Jung Hee; Mittal, Rajat

    2011-08-10

    A method for reducing the spurious pressure oscillations observed when simulating moving boundary flow problems with sharp-interface immersed boundary methods (IBMs) is proposed. By first identifying the primary cause of these oscillations to be the violation of the geometric conservation law near the immersed boundary, we adopt a cut-cell based approach to strictly enforce geometric conservation. In order to limit the complexity associated with the cut-cell method, the cut-cell based discretization is limited only to the pressure Poisson and velocity correction equations in the fractional-step method and the small-cell problem tackled by introducing a virtual cell-merging technique. The method is shown to retain all the desirable properties of the original finite-difference based IBM while at the same time, reducing pressure oscillations for moving boundaries by roughly an order of magnitude. PMID:21857745

  1. Countermeasure for reducing post-flight orthostatic intolerance: Lower Body Negative Pressure (LBNP) experiment E140

    NASA Technical Reports Server (NTRS)

    Charles, John B.

    1993-01-01

    Investigators have shown that after 1-2 weeks of bed rest ingestion of 1000 ml of a salt water solution during 4 hours of continuous exposure to 30 mm Hg of lower body negative pressure will protect plasma volume and orthostatic function for up to 24 hours. We hypothesize that a similar countermeasure will reduce the effects of fluid loss induced by headward fluid shift during space flight. The objective of this flight experiment is to evaluate the efficacy of the proposed countermeasure in reversing these effects on the cardiovascular system. Lower Body Negative Pressure (LBNP) involves exposing the legs and lower abdomen to reduced air pressure. The LBNP device is an air-tight chamber that seals the subject's waist to enclose the lower body. As used in this experiment, LBNP provides both the candidate treatment as well as the means of assessing the effectiveness of the treatment.

  2. Protein sterilization method of firefly luciferase using reduced pressure and molecular sieves

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Rich, E., Jr. (Inventor)

    1973-01-01

    The sterilization of the protein fruitfly luciferase under conditions that prevent denaturation is examined. Denaturation is prevented by heating the protein in contact with molecular seives and under a reduced pressure of the order of 0.00005 millimeters of mercury.

  3. Axially Tapered And Bilayer Microchannels For Evaporative Cooling Devices

    DOEpatents

    Nilson, Robert; Griffiths, Stewart

    2005-10-04

    The invention consists of an evaporative cooling device comprising one or more microchannels whose cross section is axially reduced to control the maximum capillary pressure differential between liquid and vapor phases. In one embodiment, the evaporation channels have a rectangular cross section that is reduced in width along a flow path. In another embodiment, channels of fixed width are patterned with an array of microfabricated post-like features such that the feature size and spacing are gradually reduced along the flow path. Other embodiments incorporate bilayer channels consisting of an upper cover plate having a pattern of slots or holes of axially decreasing size and a lower fluid flow layer having channel widths substantially greater than the characteristic microscale dimensions of the patterned cover plate. The small dimensions of the cover plate holes afford large capillary pressure differentials while the larger dimensions of the lower region reduce viscous flow resistance.

  4. Role of ocean evaporation in California droughts and floods

    NASA Astrophysics Data System (ADS)

    Wei, Jiangfeng; Jin, Qinjian; Yang, Zong-Liang; Dirmeyer, Paul A.

    2016-06-01

    Since winter 2011, a record-breaking drought has occurred in California. Studies found that the drought is mainly caused by a persistent high-pressure system off the U.S. West Coast, which is linked to Pacific sea surface temperature anomalies. The water cycles associated with the droughts and floods are still not clearly understood. Here we show that the atmospheric circulation off the West Coast not only controls the atmospheric convergence and formation of precipitation but also largely determines surface wind speed, which further affects the evaporation over the eastern North Pacific, the major evaporative moisture source for California precipitation. Because of this mechanism, the ocean evaporation over the eastern North Pacific has been reduced during the recent drought. However, the ocean evaporation anomalies have little direct influence on California precipitation, especially during dry years, mainly because of their weak amplitudes. The California droughts cannot be readily attributed to the reduced ocean evaporation. The association between increased Pacific evaporation and floods over California is somewhat stronger.

  5. Explosive evaporation in solar flares

    NASA Technical Reports Server (NTRS)

    Fisher, George H.

    1987-01-01

    This paper develops a simple analytical model for the phenomenon of 'explosive evaporation' driven by nonthermal electron heating in solar flares. The model relates the electron energy flux and spectrum, plus details of the preflare atmosphere, to the time scale for explosive evaporation to occur, the maximum pressure and temperature to be reached, rough estimates for the UV pulse emission flux and duration, and the evolution of the blueshifted component of the soft X-ray lines. An expression is given for the time scale for buildup to maximum pressures and the onset of rapid motion of the explosively evaporating plasma. This evaporation can excite a rapid response of UV line and continuum emission. The emission lines formed in the plasma approach a given emissivity-weighted blueshift speed.

  6. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, E. J.; Serra, J. L.

    2007-01-01

    T-300 carbon fibers and T-300 carbon fiber reinforced silicon carbide composites (C/SiC) were oxidized in flowing reduced oxygen partial pressure environments at a total pressure of one atmosphere (0.5 atm O2, 0.05 atm O2 and 0.005 atm O2, balance argon). Experiments were conducted at four temperatures (816deg, 1149deg, 1343deg, and 1538 C). The oxidation kinetics were monitored using thermogravimetric analysis. T-300 fibers were oxidized to completion for times between 0.6 and 90 h. Results indicated that fiber oxidation kinetics were gas phase diffusion controlled. Oxidation rates had an oxygen partial pressure dependence with a power law exponent close to one. In addition, oxidation rates were only weakly dependent on temperature. The C/SiC coupon oxidation kinetics showed some variability, attributed to differences in the number and width of cracks in the SiC seal coat. In general, weight losses were observed indicating oxidation of the carbon fibers dominated the oxidation behavior. Low temperatures and high oxygen pressures resulted in the most rapid consumption of the carbon fibers. At higher temperatures, the lower oxidation rates were primarily attributed to crack closure due to SiC thermal expansion, rather than oxidation of SiC since these reduced rates were observed even at the lowest oxygen partial pressures where SiC oxidation is minimal.

  7. Evaporation from the shallow Lake Massaciuccoli (Tuscany, Italy) studied using stable isotopes and evaporation pan data

    NASA Astrophysics Data System (ADS)

    Baneschi, I.; Gonfiantini, R.; Guidi, M.

    2009-04-01

    Oxygen and hydrogen isotope variations monitored in Lake Massaciuccoli (7 km2, 2 m deep, seasonally variable water level) during summer 2008, were compared with those observed in a Class A evaporation pan (diameter 120.6 cm, depth 25.4 cm) placed on the lake eastern shore. Air temperature, pressure, relative humidity, wind speed and direction, solar radiation, water temperature in the lake and the pan were also measured. The pluviometer indicated that no precipitation occurred during the study period. The pan was initially filled with groundwater up to the level of 19.2 cm (219 L), depleted in heavy isotopes with respect to tha lake water. Sodium chloride was added up to the concentration of 1 g×L-1, which is assumed do not affect significantly the evaporation rate till the water volume is reduced to less than 10 %. The Cl- concentration was used to provide an estimation of the evaporated water fraction, in addition to the micrometer measuring the water level variations. The pan water was sampled every 2-3 days and Cl- and stable isotopes determined. The set of stable isotope and evaporation data enabled us to compute the parameters governing the evaporation process and the isotopic exchanges with the atmospheric moisture, according to the procedure proposed by Gonfiantini (1986). The values were applied to test three working hypotheses of water balance of Lake Massaciuccoli: (i) surface inflow and outflow of liquid water are negligible and only evaporation is important; (ii) the inflow is negligible and outflow and evaporation are both significant; (iii) the three terms of balance are all important but the losses by evaporation and outflow exceed inflow (as the lake water level was decreasing). Water exchanges with groundwater are considered negligible. The best agreement between lake and pan data was obtained with the second hypothesis, for which the fraction of water removed by evaporation was estimated to be about 40 % ot he total water losses. This residual

  8. Performance of TSI 3760 condensation nuclei counter at reduced pressures and flow rates

    SciTech Connect

    Zhiqun Zhang; Liu, B.Y.H. )

    1991-01-01

    This article describes an experimental study of the performance of the TSI model 3760 clean room condensation nuclei counter (CNC) at various pressures and flow rates. Studies were made to determine the counting efficiency of the instrument in the pressure range of 0.1-1 atom and flow rate range of 0.15-1.4 L/min. The counting efficiency curves were found to be shifted to larger particle sizes as the pressure or flow rate was reduced. The low pressure and low flow rate limits of the instrument were also determined. The numerical model developed in a previous study was used to predict the performance of the CNC. The numerical results were compared with the experimental data and found to agree well in the pressure range of 0.2-1.0 atm and flow rate range of 0.3-1.4 L/min. Discrepancies were found to be more significant at the lower pressures and flow rates.

  9. Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Hedayat, Ali; Lopez, Alfredo; Grayson, Gary D.; Chandler, Frank O.; Hastings, Leon J.

    2008-01-01

    A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in low gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-3D software and simulates low gravity extrapolations of engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage Technology Demonstrator (STUSTD) program. Model results illustrate that stable low gravity liquid-gas interfaces are maintained during all phases of the pressure control cycle. Steady and relatively smooth ullage pressurization rates are predicted. This work advances current low gravity CFD modeling capabilities for cryogenic pressure control and aids the development of a low cost CFD-based design process for space hardware.

  10. Isometric handgrip training reduces arterial pressure at rest without changes in sympathetic nerve activity

    NASA Technical Reports Server (NTRS)

    Ray, C. A.; Carrasco, D. I.

    2000-01-01

    The purpose of this study was to determine whether isometric handgrip (IHG) training reduces arterial pressure and whether reductions in muscle sympathetic nerve activity (MSNA) mediate this drop in arterial pressure. Normotensive subjects were assigned to training (n = 9), sham training (n = 7), or control (n = 8) groups. The training protocol consisted of four 3-min bouts of IHG exercise at 30% of maximal voluntary contraction (MVC) separated by 5-min rest periods. Training was performed four times per week for 5 wk. Subjects' resting arterial pressure and heart rate were measured three times on 3 consecutive days before and after training, with resting MSNA (peroneal nerve) recorded on the third day. Additionally, subjects performed IHG exercise at 30% of MVC to fatigue followed by muscle ischemia. In the trained group, resting diastolic (67 +/- 1 to 62 +/- 1 mmHg) and mean arterial pressure (86 +/- 1 to 82 +/- 1 mmHg) significantly decreased, whereas systolic arterial pressure (116 +/- 3 to 113 +/- 2 mmHg), heart rate (67 +/- 4 to 66 +/- 4 beats/min), and MSNA (14 +/- 2 to 15 +/- 2 bursts/min) did not significantly change following training. MSNA and cardiovascular responses to exercise and postexercise muscle ischemia were unchanged by training. There were no significant changes in any variables for the sham training and control groups. The results indicate that IHG training is an effective nonpharmacological intervention in lowering arterial pressure.

  11. Strength training reduces arterial blood pressure but not sympathetic neural activity in young normotensive subjects

    NASA Technical Reports Server (NTRS)

    Carter, Jason R.; Ray, Chester A.; Downs, Emily M.; Cooke, William H.

    2003-01-01

    The effects of resistance training on arterial blood pressure and muscle sympathetic nerve activity (MSNA) at rest have not been established. Although endurance training is commonly recommended to lower arterial blood pressure, it is not known whether similar adaptations occur with resistance training. Therefore, we tested the hypothesis that whole body resistance training reduces arterial blood pressure at rest, with concomitant reductions in MSNA. Twelve young [21 +/- 0.3 (SE) yr] subjects underwent a program of whole body resistance training 3 days/wk for 8 wk. Resting arterial blood pressure (n = 12; automated sphygmomanometer) and MSNA (n = 8; peroneal nerve microneurography) were measured during a 5-min period of supine rest before and after exercise training. Thirteen additional young (21 +/- 0.8 yr) subjects served as controls. Resistance training significantly increased one-repetition maximum values in all trained muscle groups (P < 0.001), and it significantly decreased systolic (130 +/- 3 to 121 +/- 2 mmHg; P = 0.01), diastolic (69 +/- 3 to 61 +/- 2 mmHg; P = 0.04), and mean (89 +/- 2 to 81 +/- 2 mmHg; P = 0.01) arterial blood pressures at rest. Resistance training did not affect MSNA or heart rate. Arterial blood pressures and MSNA were unchanged, but heart rate increased after 8 wk of relative inactivity for subjects in the control group (61 +/- 2 to 67 +/- 3 beats/min; P = 0.01). These results indicate that whole body resistance exercise training might decrease the risk for development of cardiovascular disease by lowering arterial blood pressure but that reductions of pressure are not coupled to resistance exercise-induced decreases of sympathetic tone.

  12. Watermelon extract reduces blood pressure but does not change sympathovagal balance in prehypertensive and hypertensive subjects.

    PubMed

    Massa, Nayara Moreira Lacerda; Silva, Alexandre Sérgio; Toscano, Luciana Tavares; Silva, Joanna D'arc Gomes Rodrigues; Persuhn, Darlene Camati; Gonçalves, Maria Da Conceição Rodrigues

    2016-08-01

    Previous studies have shown that watermelon extract reduces blood pressure through vasodilation. However, those studies have not verified whether sympathetic nervous activity is influenced by watermelon extract. This study aimed to evaluate the effect of supplementation with watermelon extract for 6 weeks on blood pressure and sympathovagal balance of prehypertensive and hypertensive individuals. Forty volunteers participated in a randomized, double-blind, experimental and placebo-controlled study. They consumed 6 g of watermelon extract daily (n = 20; age 48.7 ± 1.9 years, 10 men) or a placebo (n = 20; age 47.4 ± 1.2 years, 11 men) for 6 weeks. Blood pressure and cardiac autonomic modulation were measured. Watermelon extract promoted a significant reduction in systolic (137.8 ± 3.9 to 126.0 ± 4.0 mmHg, p < 0.0001) and diastolic (79.2 ± 2.2 to 72.3 ± 2.0 mmHg, p < 0.001) blood pressure, but showed no differences compared to the placebo group. This significant reduction in blood pressure occurred without a significant change in sympathovagal balance from the beginning (1.7 ± 0.1) to the end of the study (1.7 ± 0.4). In conclusion, supplementation with watermelon extract reduces systolic and diastolic blood pressure in prehypertensive and hypertensive individuals, but does not alter the cardiac autonomic modulation of these individuals. PMID:26947668

  13. Synthesis of Bulk BC8 Silicon Allotrope by Direct Transformation and Reduced-Pressure Chemical Pathways.

    PubMed

    Kurakevych, Oleksandr O; Le Godec, Yann; Crichton, Wilson A; Guignard, Jérémy; Strobel, Timothy A; Zhang, Haidong; Liu, Hanyu; Coelho Diogo, Cristina; Polian, Alain; Menguy, Nicolas; Juhl, Stephen J; Gervais, Christel

    2016-09-01

    Phase-pure samples of a metastable allotrope of silicon, Si-III or BC8, were synthesized by direct elemental transformation at 14 GPa and ∼900 K and also at significantly reduced pressure in the Na-Si system at 9.5 GPa by quenching from high temperatures ∼1000 K. Pure sintered polycrystalline ingots with dimensions ranging from 0.5 to 2 mm can be easily recovered at ambient conditions. The chemical route also allowed us to decrease the synthetic pressures to as low as 7 GPa, while pressures required for direct phase transition in elemental silicon are significantly higher. In situ control of the synthetic protocol, using synchrotron radiation, allowed us to observe the underlying mechanism of chemical interactions and phase transformations in the Na-Si system. Detailed characterization of Si-III using X-ray diffraction, Raman spectroscopy, (29)Si NMR spectroscopy, and transmission electron microscopy are discussed. These large-volume syntheses at significantly reduced pressures extend the range of possible future bulk characterization methods and applications. PMID:27532223

  14. Heterozygous disruption of renal outer medullary potassium channel in rats is associated with reduced blood pressure.

    PubMed

    Zhou, Xiaoyan; Zhang, Zuo; Shin, Myung Kyun; Horwitz, Sarah Beth; Levorse, John M; Zhu, Lei; Sharif-Rodriguez, Wanda; Streltsov, Denis Y; Dajee, Maya; Hernandez, Melba; Pan, Yi; Urosevic-Price, Olga; Wang, Li; Forrest, Gail; Szeto, Daphne; Zhu, Yonghua; Cui, Yan; Michael, Bindhu; Balogh, Leslie Ann; Welling, Paul A; Wade, James B; Roy, Sophie; Sullivan, Kathleen A

    2013-08-01

    The renal outer medullary potassium channel (ROMK, KCNJ1) mediates potassium recycling and facilitates sodium reabsorption through the Na(+)/K(+)/2Cl(-) cotransporter in the loop of Henle and potassium secretion at the cortical collecting duct. Human genetic studies indicate that ROMK homozygous loss-of-function mutations cause type II Bartter syndrome, featuring polyuria, renal salt wasting, and hypotension; humans heterozygous for ROMK mutations identified in the Framingham Heart Study have reduced blood pressure. ROMK null mice recapitulate many of the features of type II Bartter syndrome. We have generated an ROMK knockout rat model in Dahl salt-sensitive background by using zinc finger nuclease technology and investigated the effects of knocking out ROMK on systemic and renal hemodynamics and kidney histology in the Dahl salt-sensitive rats. The ROMK(-/-) pups recapitulated features identified in the ROMK null mice. The ROMK(+/-) rats, when challenged with a 4% salt diet, exhibited a reduced blood pressure compared with their ROMK(+/+) littermates. More importantly, when challenged with an 8% salt diet, the Dahl salt-sensitive rats with 50% less ROMK expression showed increased protection from salt-induced blood pressure elevation and signs of protection from renal injury. Our findings in ROMK knockout Dahl salt-sensitive rats, together with the previous reports in humans and mice, underscore a critical role of ROMK in blood pressure regulation. PMID:23753405

  15. New Results in Two-Phase Pressure Drop Calculations at Reduced Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Braisted, Jon; Kurwitz, Cable; Best, Frederick

    2004-02-01

    The mass, power, and volume energy savings of two-phase systems for future spacecraft creates many advantages over current single-phase systems. Current models of two-phase phenomena such as pressure drop, void fraction, and flow regime prediction are still not well defined for space applications. Commercially available two-phase modeling software has been developed for a large range of acceleration fields including reduced-gravity conditions. Recently, a two-phase experiment has been flown to expand the two-phase database. A model of the experiment was created in the software to determine how well the software could predict the pressure drop observed in the experiment. Of the simulations conducted, the computer model shows good agreement of the pressure drop in the experiment to within 30%. However, the software does begin to over-predict pressure drop in certain regions of a flow regime map indicating that some models used in the software package for reduced-gravity modeling need improvement.

  16. Analysis of hydrogen vehicles with cryogenic high pressure storage

    SciTech Connect

    Aceves, S. M.; Berry, G. D.

    1998-06-19

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LIQ) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). This paper shows an evaluation of the applicability of the insulated pressure vessels for light-duty vehicles. The paper shows an evaluation of evaporative losses and insulation requirements and a description of the current experimental plans for testing insulated pressure vessels. The results show significant advantages to the use of insulated pressure vessels for light-duty vehicles.

  17. Streamer Evaporation

    NASA Technical Reports Server (NTRS)

    Suess, Steven T.; Wang, A. H.; Wu, Shi T.; Nerney, S.

    1998-01-01

    Evaporation is the consequence of slow plasma heating near the tops of streamers where the plasma is only weakly contained by the magnetic field. The form it takes is the slow opening of field lines at the top of the streamer and transient formation of new solar wind. It was discovered in polytropic model calculations, where due to the absence of other energy loss mechanisms in magnetostatic streamers, its ultimate endpoint is the complete evaporation of the streamer. This takes, for plausible heating rates, weeks to months in these models. Of course streamers do not behave this way, for more than one reason. One is that there are losses due to thermal conduction to the base of the streamer and radiation from the transition region. Another is that streamer heating must have a characteristic time constant and depend on the ambient physical conditions. We use our global Magnetohydrodynamics (MHD) model with thermal conduction to examine a few examples of the effect of changing the heating scale height and of making ad hoc choices for how the heating depends on ambient conditions. At the same time, we apply and extend the analytic model of streamers, which showed that streamers will be unable to contain plasma for temperatures near the cusp greater than about 2xl0(exp 6) K. Slow solar wind is observed to come from streamers through transient releases. A scenario for this that is consistent with the above physical process is that heating increases the near-cusp temperature until field lines there are forced open. The subsequent evacuation of the flux tubes by the newly forming slow wind decreases the temperature and heating until the flux tubes are able to reclose. Then, over a longer time scale, heating begins to again refill the flux tubes with plasma and increase the temperature until the cycle repeats itself. The calculations we report here are first steps towards quantitative evaluation of this scenario.

  18. Water savings through reduced evaporative loss from SDI compared with sprinkler irrigation: Degree of savings and effect on yield and WUE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Subsurface drip irrigation (SDI) wets the soil at the depth of the drip line and in a volume around each emitter, but the soil wetted often does not include the soil surface. Because of this, the soil surface remains completely or at least partially dry and evaporative losses of irrigation water are...

  19. Nitrogenase Activity Is Affected by Reduced Partial Pressures of N2 and NO3- 1.

    PubMed Central

    Blumenthal, J. M.; Russelle, M. P.; Vance, C. P.

    1997-01-01

    Optimal use of legumes in cropping systems requires a thorough understanding of the interaction between inorganic N nutrition and symbiotic N2 fixation. Our objective was to test the hypothesis that increased NO3- uptake by alfalfa (Medicago sativa L.) would compensate for lower N2 fixation caused by low partial pressure of N2. Root systems of hydroponically grown alfalfa at 2 mg L-1 NO3--N were exposed to (a) 80% N2, (b) 7% N2, (c) 2% N2, or (d) 0% N2. Exposure to reduced partial pressures of N2 reduced total nitrogenase activity (TNA, measured as H2 production in 20% O2 and 80% Ar) by 40% within less than 30 min, followed by a recovery period over the next 30 min to initial activity. Five hours after treatments began, the TNA of plants exposed to 7 and 2% N2 was substantially higher than pretreatment activities, whereas the TNA of plants exposed either to 0 or 80% N2 did not differ from pretreatment values. The decline in TNA due to NO3- exposure over 4 d was not affected by reduced partial pressure of N2. During the 1st h the proportion of electrons used for the reduction of N2 fell from 0.52 to 0.23 for plants exposed to 7% N2, and to 0.09 for plants exposed to 2% N2, and remained unchanged for the rest of the experiment. Although the hypothesis that alfalfa compensated with increased NO3- uptake for lower N2 fixation was not validated by our results, we unexpectedly demonstrated that the decline in TNA upon exposure to NO3- was independent of the N2-fixing efficiency (i.e. the amount of N2 reduced by nitrogenase) of the symbiosis. PMID:12223779

  20. Reduced grazing pressure delivers production and environmental benefits for the typical steppe of north China

    PubMed Central

    Zhang, Yingjun; Huang, Ding; Badgery, Warwick B.; Kemp, David R.; Chen, Wenqing; Wang, Xiaoya; Liu, Nan

    2015-01-01

    Degradation by overgrazing is common in many areas of the world and optimising grassland functions depends upon finding suitable grazing tactics. This four-year study on the northern China steppe investigated combinations of rest, moderate or heavy grazing pressure early in the summer growing season, then moderate or heavy grazing in the mid and late season. Results showed that moderate grazing pressure (~550 sheep equivalent (SE) grazing days ha−1 year−1) gave the optimal balance between maintaining a productive and diverse grassland, a profitable livestock system, and greenhouse gas mitigation. Further analyses identified that more conservative stocking (~400 SE grazing days ha−1 year−1) maintained a desirable Leymus chinensis composition and achieved a higher live weight gain of sheep. Early summer rest best maintained a desirable grassland composition, but had few other benefits and reduced incomes. These findings demonstrate that reducing grazing pressure to half the current district stocking rates can deliver improved ecosystem services (lower greenhouse gases and improved grassland composition) while sustaining herder incomes. PMID:26553566

  1. Reduced grazing pressure delivers production and environmental benefits for the typical steppe of north China.

    PubMed

    Zhang, Yingjun; Huang, Ding; Badgery, Warwick B; Kemp, David R; Chen, Wenqing; Wang, Xiaoya; Liu, Nan

    2015-01-01

    Degradation by overgrazing is common in many areas of the world and optimising grassland functions depends upon finding suitable grazing tactics. This four-year study on the northern China steppe investigated combinations of rest, moderate or heavy grazing pressure early in the summer growing season, then moderate or heavy grazing in the mid and late season. Results showed that moderate grazing pressure (~550 sheep equivalent (SE) grazing days ha(-1) year(-1)) gave the optimal balance between maintaining a productive and diverse grassland, a profitable livestock system, and greenhouse gas mitigation. Further analyses identified that more conservative stocking (~400 SE grazing days ha(-1) year(-1)) maintained a desirable Leymus chinensis composition and achieved a higher live weight gain of sheep. Early summer rest best maintained a desirable grassland composition, but had few other benefits and reduced incomes. These findings demonstrate that reducing grazing pressure to half the current district stocking rates can deliver improved ecosystem services (lower greenhouse gases and improved grassland composition) while sustaining herder incomes. PMID:26553566

  2. Farnesoid X receptor agonist CDCA reduces blood pressure and regulates vascular tone in spontaneously hypertensive rats.

    PubMed

    Li, Chenyu; Li, Jing; Weng, Xu; Lan, Xiaofang; Chi, Xiangbo

    2015-07-01

    The Farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily, which plays an essential role in lipid homeostasis and glucose metabolism. However, whether or not FXR can prevent rise in blood pressure remains unknown. Here, we investigate the possibility of using chenodeoxycholic acid (CDCA), a natural ligand of FXR, to attenuate elevated blood pressure in spontaneously hypertensive rats (SHR). SHR and Wistar-Kyoto rats (WKY) were treated with CDCA (30 mg/kg) for 8 weeks. Compared with vehicle control, CDCA attenuated rise in blood pressure in SHR. In addition, CDCA improved vasorelaxation and diminished the contractile response to endothelin-1 (ET-1) in mesenteric arteries from SHR. CDCA also stimulated endothelial nitric oxide synthase (eNOS) expression, repressed ET-1 levels, and inhibited NF-κB activities in mesenteric arteries of the SHR. Overall, we showed that CDCA treatment reduces systolic blood pressure, improves vascular relaxation, and inhibits vasoconstriction activity in SHR. The repressed ET-1 level, the raised eNOS expression, and the ameliorated inflammation in mesenteric arteries could be responsible for the vasorelaxant and hypotensive effect of CDCA. These findings support a potential role for FXR as a regulator in vascular activities and in the development of treatment for hypertension. PMID:26188398

  3. Evaporative cooling of flare plasma

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.; Sturrock, P. A.

    1976-01-01

    A one-dimensional loop model for the evaporative cooling of the coronal flare plasma was investigated. Conductive losses dominated radiative cooling, and the evaporative velocities were small compared to the sound speed. The profile and evolution of the temperature were calculated. The model was in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation was to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.

  4. Evaporative cooling of flare plasma

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.; Sturrock, P. A.

    1978-01-01

    We investigate a one-dimensional loop model for the evaporative cooling of the coronal flare plasma. The important assumptions are that conductive losses dominate radiative cooling and that the evaporative velocities are small compared with the sound speed. We calculate the profile and evolution of the temperature and verify the accuracy of our assumptions for plasma parameters typical of flare regions. The model is in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation is to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.

  5. Waste Evaporator Accident Simulation Using RELAP5 Computer Code

    SciTech Connect

    POLIZZI, L.M.

    2004-04-28

    An evaporator is used on liquid waste from processing facilities to reduce the volume of the waste through heating the waste and allowing some of the water to be separated from the waste through boiling. This separation process allows for more efficient processing and storage of liquid waste. Commonly, the liquid waste consists of an aqueous solution of chemicals that over time could induce corrosion, and in turn weaken the tubes in the steam tube bundle of the waste evaporator that are used to heat the waste. This chemically induced corrosion could escalate into a possible tube leakage and/or the severance of a tube(s) in the tube bundle. In this paper, analyses of a waste evaporator system for the processing of liquid waste containing corrosive chemicals are presented to assess the system response to this accident scenario. This accident scenario is evaluated since its consequences can propagate to a release of hazardous material to the outside environment. It is therefore important to ensure that the evaporator system component structural integrity is not compromised, i.e. the design pressure and temperature of the system is not exceeded during the accident transient. The computer code used for the accident simulation is RELAP5-MOD31. The accident scenario analyzed includes a double-ended guillotine break of a tube in the tube bundle of the evaporator. A mitigated scenario is presented to evaluate the excursion of the peak pressure and temperature in the various components of the evaporator system to assess whether the protective actions and controls available are adequate to ensure that the structural integrity of the evaporator system is maintained and that no atmospheric release occurs.

  6. Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  7. Placental Growth Factor Reduces Blood Pressure in a Uteroplacental Ischemia Model of Preeclampsia in Nonhuman Primates.

    PubMed

    Makris, Angela; Yeung, Kristen R; Lim, Shirlene M; Sunderland, Neroli; Heffernan, Scott; Thompson, John F; Iliopoulos, Jim; Killingsworth, Murray C; Yong, Jim; Xu, Bei; Ogle, Robert F; Thadhani, Ravi; Karumanchi, S Ananth; Hennessy, Annemarie

    2016-06-01

    An imbalance in the angiogenesis axis during pregnancy manifests as clinical preeclampsia because of endothelial dysfunction. Circulating soluble fms-like tyrosine kinase 1 (sFLT-1) increases and placental growth factor (PlGF) reduces before and during disease. We investigated the clinical and biochemical effects of replenishing the reduced circulating PlGF with recombinant human PlGF (rhPlGF) and thus restoring the angiogenic balance. Hypertensive proteinuria was induced in a nonhuman primate (Papio hamadryas) by uterine artery ligation at 136 days gestation (of a 182-day pregnancy). Two weeks after uteroplacental ischemia, rhPlGF (rhPlGF, n=3) or normal saline (control, n=4) was administered by subcutaneous injection (100 μg/kg per day) for 5 days. Blood pressure was monitored by intra-arterial radiotelemetry and sFLT-1 and PlGF by ELISA. Uteroplacental ischemia resulted in experimental preeclampsia evidenced by increased blood pressure, proteinuria, and endotheliosis on renal biopsy and elevated sFLT-1. PlGF significantly reduced after uteroplacental ischemia. rhPlGF reduced systolic blood pressure in the treated group (-5.2±0.8 mm Hg; from 132.6±6.6 mm Hg to 124.1±7.6 mm Hg) compared with an increase in systolic blood pressure in controls (6.5±3 mm Hg; from 131.3±1.5 mm Hg to 138.6±1.5 mm Hg). Proteinuria reduced in the treated group (-72.7±55.7 mg/mmol) but increased in the control group. Circulating levels of total sFLT-1 were not affected by the administration of PlGF; however, a reduction in placental sFLT-1 mRNA expression was demonstrated. There was no significant difference between the weights or lengths of the neonates in the rhPlGF or control group; however, this study was not designed to assess fetal safety or outcomes. Increasing circulating PlGF by the administration of rhPlGF improves clinical parameters in a primate animal model of experimental preeclampsia. PMID:27091894

  8. Innovative, High-Pressure, Cryogenic Control Valve: Short Face-to-Face, Reduced Cost

    NASA Technical Reports Server (NTRS)

    Wilkes, Karlin; Larsen, Ed; McCourt, Jackson

    2004-01-01

    A control valve that can throttle high pressure cryogenic fluid embodies several design features that distinguish it over conventional valves designed for similar applications. Field and design engineers worked together to create a valve that would simplify installation, trim changes, and maintenance, thus reducing overall cost. The seals and plug stem packing were designed to perform optimally in cryogenic temperature ranges. Unlike conventional high-pressure cryogenic valves, the trim size can be changed independent of the body. The design feature that provides flexibility for changing the trim is a split body. The body is divided into an upper and a lower section with the seat ring sandwiched in between. In order to maintain the plug stem packing at an acceptable sealing temperature during cryogenic service, heat-exchanging fins were added to the upper body section (see figure). The body is made of stainless steel.

  9. Suppression of gas detonation by a dust cloud at reduced mixture pressures

    NASA Astrophysics Data System (ADS)

    Pinaev, A. V.; Vasil'ev, A. A.; Pinaev, P. A.

    2015-05-01

    The decay of a detonation wave in a mixture propagating through a dust cloud is experimentally studied for three types of silica sand with particle sizes 250-600, 120-250, and 90-120 , mean volume densities 2.2-3.5 g/l, and initial pressure 0.1-0.01 MPa. A non-monotonic character of reduction of wave velocity in the dust cloud is observed, where a secondary detonation can arise behind the leading front of the wave in the course of its attenuation. This situation is induced by the dual role of sand particles in decelerating the flow and simultaneously generating hot spots that promote reaction excitation. As a result, the mechanism of ignition in the decaying detonation wave becomes different. Critical parameters of the dust cloud providing complete suppression of the detonation wave and the flame propagating behind the latter at a reduced initial pressure of the gas mixture are determined.

  10. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Serra, Jessica

    2009-01-01

    Carbon-fiber reinforced SiC (C/SiC) composites are proposed for leading edge applications of hypersonic vehicles due to the superior strength of carbon fibers at high temperatures (greater than 1500 C). However, the vulnerability of the carbon fibers in C/SiC to oxidation over a wide range of temperatures remains a problem. Previous oxidation studies of C/SiC have mainly been conducted in air or oxygen, so that the oxidation behavior of C/SiC at reduced oxygen partial pressures of the hypersonic flight regime are less well understood. In this study, both carbon fibers and C/SiC composites were oxidized over a wide range of temperatures and oxygen partial pressures to facilitate the understanding and modeling of C/SiC oxidation kinetics for hypersonic flight conditions.

  11. BaroLoop: using a multichannel cuff electrode and selective stimulation to reduce blood pressure.

    PubMed

    Plachta, Dennis T T; Gierthmuehlen, Mortimer; Cota, Oscar; Boeser, Fabian; Stieglitz, Thomas

    2013-01-01

    The therapy of refractory hypertension is an increasing problem for health care systems and a frontend in research in both pharmacology and neuroelectronic engineering. Overriding the baroreceptive information of afferent nerve fibers, originating from pressure sensors in the aortic arch, can trigger the baroreflex, a systemic control system that lowers the blood pressure (BP) almost instantaneously. Using a multichannel cuff electrode, wrapped around a rat vagal nerve, we were able to regulate the BP using selective, tripolar stimulation. The tripolar stimulation was sufficiently selective to not trigger any unwanted side effects like bradycardia or bradypnea. The BP was reduced best with charge balanced stimulation amplitudes of 1 mA and pulse duration of 0.3 ms. The stimulation frequency had only a mild influence on the effectiveness of the stimulation and did work best at 40 Hz. We found that the BP took up to five times the stimulation period to recover to the value prior to stimulation. PMID:24109797

  12. Improvement to Air2Air Technology to Reduce Fresh-Water Evaporative Cooling Loss at Coal-Based Thermoelectric Power Plants

    SciTech Connect

    Ken Mortensen

    2011-12-31

    This program was undertaken to enhance the manufacturability, constructability, and cost of the Air2Air{TM} Water Conservation and Plume Abatement Cooling Tower, giving a validated cost basis and capability. Air2Air{TM} water conservation technology recovers a portion of the traditional cooling tower evaporate. The Condensing Module provides an air-to-air heat exchanger above the wet fill media, extracting the heat from the hot saturated moist air leaving in the cooling tower and condensing water. The rate of evaporate water recovery is typically 10% - 25% annually, depending on the cooling tower location (climate). This program improved the efficiency and cost of the Air2Air{TM} Water Conservation Cooling Tower capability, and led to the first commercial sale of the product, as described.

  13. Acid evaporation property in chemically amplified resists

    NASA Astrophysics Data System (ADS)

    Hashimoto, Shuichi; Itani, Toshiro; Yoshino, Hiroshi; Yamana, Mitsuharu; Samoto, Norihiko; Kasama, Kunihiko

    1997-07-01

    The lithographic performance of a chemically amplified resist system very much depends on the photo-generated acid structure. In a previous paper, we reported the molecular structure dependence of two typical photo-generated acids (aromatic sulfonic acid and alkyl sulfonic acid) from the viewpoints of lithographic performance and acid characteristics such as acid generation efficiency, acid diffusion behavior and acid evaporation property. In this paper, we evaluate the effect of the remaining solvent in a resist film on the acid evaporation property. Four types of two-component chemically amplified positive KrF resists were prepared consisting of tert-butoxycarbonyl (t-BOC) protected polyhydroxystyrene and sulfonic acid derivative photo-acid generator (PAG). Here, a different combination of two types of PAGs [2,4-dimethylbenzenesulfonic acid (aromatic sulfonic acid) derivative PAG and cyclohexanesulfonic acid (alkyl sulfonic acid) derivative PAG] and two types of solvents (propylene glycol monomethyl ether acetate; PGMEA and ethyl lactate; EL) were evaluated. The aromatic sulfonic acid was able to evaporate easily during post exposure bake (PEB) treatment, but the alkyl sulfonic acid was not. The higher evaporation property of aromatic sulfonic acid might be due to the higher vapor pressure and the longer acid diffusion length. Furthermore, the amount of aromatic sulfonic acid in the PGMEA resist was reduced by more than that in the EL resist. The amount of acid loss also became smaller at a higher prebake temperature. The concentration of the remaining solvent in the resist film decreased with the increasing prebake temperature. We think that the acid evaporation property was affected by the remaining solvent in the resist, film; the large amount of remaining solvent promoted the acid diffusion and eventually accelerated the acid evaporation from the resist film surface in the PGMEA resist. In summary, the acid evaporation property depends on both the acid

  14. Heat transfer in two-phase flow at high reduced pressures

    NASA Astrophysics Data System (ADS)

    Yagov, V. V.; Minko, M. V.

    2011-04-01

    It is shown that heat transfer that takes place in vapor-liquid flows in the region of high reduced pressures is mainly due to the nucleate boiling mechanism even at high values of vapor quality. At relatively low heat fluxes, a noticeable enhancement of heat transfer is observed as vapor quality increases. A procedure for calculating heat transfer is proposed, which is confirmed by a comparison of calculated results with experimental data on the boiling of carbon dioxide and other liquids in channels.

  15. High-pressure highly reduced nitrides and oxides from chromitite of a Tibetan ophiolite

    PubMed Central

    Dobrzhinetskaya, Larissa F.; Wirth, Richard; Yang, Jingsui; Hutcheon, Ian D.; Weber, Peter K.; Green, Harry W.

    2009-01-01

    The deepest rocks known from within Earth are fragments of normal mantle (≈400 km) and metamorphosed sediments (≈350 km), both found exhumed in continental collision terranes. Here, we report fragments of a highly reduced deep mantle environment from at least 300 km, perhaps very much more, extracted from chromite of a Tibetan ophiolite. The sample consists, in part, of diamond, coesite-after-stishovite, the high-pressure form of TiO2, native iron, high-pressure nitrides with a deep mantle isotopic signature, and associated SiC. This appears to be a natural example of the recently discovered disproportionation of Fe2+ at very high pressure and consequent low oxygen fugacity (fO2) in deep Earth. Encapsulation within chromitite enclosed within upwelling solid mantle rock appears to be the only vehicle capable of transporting these phases and preserving their low-fO2 environment at the very high temperatures of oceanic spreading centers. PMID:19880742

  16. Morphology of gas cavities on patterned hydrophobic surfaces under reduced pressure

    NASA Astrophysics Data System (ADS)

    Xue, Yahui; Lv, Pengyu; Liu, Ying; Shi, Yipeng; Lin, Hao; Duan, Huiling

    2015-09-01

    Gas cavities trapped on structured hydrophobic surfaces play important roles in realizing functionalities such as superhydrophobicity, drag reduction, and surface cleaning. The morphology of the cavities exhibits strong dependence on system parameters which impact the performance of these surfaces. In this work, a complete theoretical analysis is presented to predict cavity morphological change under reduced liquid pressure, on a submerged hydrophobic surface patterned with cylindrical pores. Equilibrium solutions are derived for five different phases, namely, (I) pinned recession, (II) depinned recession, (III) Cassie-Baxter, (IV) expansion, and (V) coalescence; their stabilities are also analyzed. A phase map is developed outlining the different regimes with respect to the gas amount and liquid pressure. Importantly, phase (IV) exhibits a complex stability behavior that leads to two possible routes to coalescence, which lends two different mechanisms of cavitation. Accordingly, the threshold pressure for cavitation can be calculated. The theoretical model is supported by direct experimental measurements via confocal microscopy and demonstrates good quantitative accuracy. This work provides a predictive tool for the design of functional structured hydrophobic surfaces.

  17. Hydrogen Isotope Separation by Combined Electrolysis Catalytic Exchange Under Reduced Pressure

    SciTech Connect

    Sugiyama, T.; Asakura, Y.; Uda, T.; Abe, Y.; Shiozaki, T.; Enokida, Y.; Yamamoto, I.

    2005-07-15

    At the National Institute for Fusion Science experimental studies on hydrogen isotope separation by a Combined Electrolysis Catalytic Exchange (CECE) process have been carried out in order to apply it to the system of water detritiation for D-D burning experiments of the Large Helical Device. As an improvement of the CECE process, we have developed a reduced-pressure method as a means of enhancing the separation factor. The feasibility of this method is examined through application to a CECE process using a prototype separation column. Hydrogen-deuterium isotope separation experiments are performed in the two cases where column pressures are 12 and 101 kPa, and the separation factors for hydrogen and deuterium are obtained as 6.8 and 5.6, respectively. It is confirmed that the present method is applicable and useful to the CECE process. The values of Height Equivalent to a Theoretical Plate (HETP) are estimated by analyses with the equilibrium stage model. The HETP values are 15 cm at 12 kPa and 13 cm at 101 kPa. The increase of superficial velocity with decreasing pressure may spoil the efficiency of the mass transfer.

  18. Escherichia coli Morphological Changes and Lipid A Removal Induced by Reduced Pressure Nitrogen Afterglow Exposure

    PubMed Central

    Zerrouki, Hayat; Rizzati, Virginie; Bernis, Corinne; Nègre-Salvayre, Anne; Sarrette, Jean Philippe; Cousty, Sarah

    2015-01-01

    Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria. PMID:25837580

  19. Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

    PubMed

    Zerrouki, Hayat; Rizzati, Virginie; Bernis, Corinne; Nègre-Salvayre, Anne; Sarrette, Jean Philippe; Cousty, Sarah

    2015-01-01

    Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria. PMID:25837580

  20. 242-A evaporator vacuum condenser system

    SciTech Connect

    Smith, V.A.

    1994-09-28

    This document is written for the 242-A evaporator vacuum condenser system (VCS), describing its purpose and operation within the evaporator. The document establishes the operating parameters specifying pressure, temperature, flow rates, interlock safety features and interfacing sub-systems to support its operation.

  1. Resistance Exercise Restores Endothelial Function and Reduces Blood Pressure in Type 1 Diabetic Rats

    PubMed Central

    Mota, Marcelo Mendonça; da Silva, Tharciano Luiz Teixeira Braga; Fontes, Milene Tavares; Barreto, André Sales; Araújo, João Eliakim dos Santos; de Oliveira, Antônio Cesar Cabral; Wichi, Rogério Brandão; Santos, Márcio Roberto Viana

    2014-01-01

    Background Resistance exercise effects on cardiovascular parameters are not consistent. Objectives The effects of resistance exercise on changes in blood glucose, blood pressure and vascular reactivity were evaluated in diabetic rats. Methods Wistar rats were divided into three groups: control group (n = 8); sedentary diabetic (n = 8); and trained diabetic (n = 8). Resistance exercise was carried out in a squat device for rats and consisted of three sets of ten repetitions with an intensity of 50%, three times per week, for eight weeks. Changes in vascular reactivity were evaluated in superior mesenteric artery rings. Results A significant reduction in the maximum response of acetylcholine-induced relaxation was observed in the sedentary diabetic group (78.1 ± 2%) and an increase in the trained diabetic group (95 ± 3%) without changing potency. In the presence of NG-nitro-L-arginine methyl ester, the acetylcholine-induced relaxation was significantly reduced in the control and trained diabetic groups, but not in the sedentary diabetic group. Furthermore, a significant increase (p < 0.05) in mean arterial blood pressure was observed in the sedentary diabetic group (104.9 ± 5 to 126.7 ± 5 mmHg) as compared to that in the control group. However, the trained diabetic group showed a significant decrease (p < 0.05) in the mean arterial blood pressure levels (126.7 ± 5 to 105.1 ± 4 mmHg) as compared to the sedentary diabetic group. Conclusions Resistance exercise could restore endothelial function and prevent an increase in arterial blood pressure in type 1 diabetic rats. PMID:25120082

  2. Strategies to reduce the environmental impact of an aluminium pressure die casting plant: a scenario analysis.

    PubMed

    Neto, Belmira; Kroeze, Carolien; Hordijk, Leen; Costa, Carlos; Pulles, Tinus

    2009-02-01

    This study explores a model (MIKADO) to analyse scenarios for the reduction of the environmental impact of an aluminium die casting plant. Our model calculates the potential to reduce emissions, and the costs associated with implementation of reduction options. In an earlier paper [Neto, B., Kroeze, C., Hordijk, L., Costa, C., 2008. Modelling the environmental impact of an aluminium pressure die casting company and options for control. Environmental Modelling & Software 23 (2) 147-168] we included the model description and explored the model by applying it to a plant in which no reduction options are assumed to be implemented (so-called zero case, reflecting the current practice in the plant). Here, we perform a systematic analysis of reduction options. We analysed seven types of reduction strategies, assuming the simultaneous implementation of different reduction options. These strategies are analysed with respect to their potential to reduce emissions, environmental impact and costs associated with the implementation of options. These strategies were found to differ largely in their potential to reduce the environmental impact of the plant (10-87%), as well as in the costs associated with the implementation of options (-268 to +277keuro/year). We were able to define 11 strategies, reducing the overall environmental impact by more than 50%. Of these, two have net negative costs, indicating that the company may in fact earn money through their implementation. PMID:18342428

  3. Steam Pressure-Reducing Station Safety and Energy Efficiency Improvement Project

    SciTech Connect

    Lower, Mark D; Christopher, Timothy W; Oland, C Barry

    2011-06-01

    The Facilities and Operations (F&O) Directorate is sponsoring a continuous process improvement (CPI) program. Its purpose is to stimulate, promote, and sustain a culture of improvement throughout all levels of the organization. The CPI program ensures that a scientific and repeatable process exists for improving the delivery of F&O products and services in support of Oak Ridge National Laboratory (ORNL) Management Systems. Strategic objectives of the CPI program include achieving excellence in laboratory operations in the areas of safety, health, and the environment. Identifying and promoting opportunities for achieving the following critical outcomes are important business goals of the CPI program: improved safety performance; process focused on consumer needs; modern and secure campus; flexibility to respond to changing laboratory needs; bench strength for the future; and elimination of legacy issues. The Steam Pressure-Reducing Station (SPRS) Safety and Energy Efficiency Improvement Project, which is under the CPI program, focuses on maintaining and upgrading SPRSs that are part of the ORNL steam distribution network. This steam pipe network transports steam produced at the ORNL steam plant to many buildings in the main campus site. The SPRS Safety and Energy Efficiency Improvement Project promotes excellence in laboratory operations by (1) improving personnel safety, (2) decreasing fuel consumption through improved steam system energy efficiency, and (3) achieving compliance with applicable worker health and safety requirements. The SPRS Safety and Energy Efficiency Improvement Project being performed by F&O is helping ORNL improve both energy efficiency and worker safety by modifying, maintaining, and repairing SPRSs. Since work began in 2006, numerous energy-wasting steam leaks have been eliminated, heat losses from uninsulated steam pipe surfaces have been reduced, and deficient pressure retaining components have been replaced. These improvements helped ORNL

  4. Study of Critical Heat Flux and Two-Phase Pressure Drop Under Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Abdollahian, Davood; Quintal, Joseph; Barez, Fred; Zahm, Jennifer; Lohr, Victor

    1996-01-01

    The design of the two-phase flow systems which are anticipated to be utilized in future spacecraft thermal management systems requires a knowledge of two-phase flow and heat transfer phenomena in reduced gravities. This program was funded by NASA headquarters in response to NRA-91-OSSA-17 and was managed by Lewis Research Center. The main objective of this program was to design and construct a two-phase test loop, and perform a series of normal gravity and aircraft trajectory experiments to study the effect of gravity on the Critical Heat Flux (CHF) and onset of instability. The test loop was packaged on two aircraft racks and was also instrumented to generate data for two-phase pressure drop. The normal gravity tests were performed with vertical up and downflow configurations to bound the effect of gravity on the test parameters. One set of aircraft trajectory tests was performed aboard the NASA DC-9 aircraft. These tests were mainly intended to evaluate the test loop and its operational performance under actual reduced gravity conditions, and to produce preliminary data for the test parameters. The test results were used to demonstrate the applicability of the normal gravity models for prediction of the two-phase friction pressure drop. It was shown that the two-phase friction multipliers for vertical upflow and reduced gravity conditions can be successfully predicted by the appropriate normal gravity models. Limited critical heat flux data showed that the measured CHF under reduced gravities are of the same order of magnitude as the test results with vertical upflow configuration. A simplified correlation was only successful in predicting the measured CHF for low flow rates. Instability tests with vertical upflow showed that flow becomes unstable and critical heat flux occurs at smaller powers when a parallel flow path exists. However, downflow tests and a single reduced gravity instability experiment indicated that the system actually became more stable with a

  5. Experimental study on the double-evaporator thermosiphon for cooling HTS (high temperature superconductor) system

    NASA Astrophysics Data System (ADS)

    Lee, Junghyun; Ko, Junseok; Kim, Youngkwon; Jeong, Sangkwon; Sung, Taehyun; Han, Younghee; Lee, Jeong-Phil; Jung, Seyong

    2009-08-01

    A cryogenic thermosiphons is an efficient heat transfer device between a cryocooler and a thermal load that is to be cooled. This paper presents an idea of thermosiphon which contains two vertically-separated evaporators. This unique configuration of the thermosiphon is suitable for the purpose of cooling simultaneously two superconducting bearings of the HTS (high temperature superconducting) flywheel system at the same temperature. A so-called double-evaporator thermosiphon was designed, fabricated and tested using nitrogen as the working fluid under sub-atmospheric pressure condition. The interior thermal condition of the double-evaporator thermosiphon was examined in detail during its cool-down process according to the internal thermal states. The double-evaporator thermosiphon has operated successfully at steady-state operation under sub-atmospheric pressure. At the heat flow of 10.6 W, the total temperature difference of the thermosiphon was only 1.59 K and the temperature difference between the evaporators was 0.64 K. The temperature difference of two evaporators is attributed to the conductive thermal resistance of the adiabatic section between the evaporators. The method to reduce this temperature difference has been investigated and presented in this paper. The proper area selection of condenser, evaporator 1, and evaporator 2 was studied by using thermal resistance model to optimize the performance of a thermosiphon. The superior heat transfer characteristic of the double-evaporator thermosiphon without involving any cryogenic pump can be a great potential advantage for cooling HTS bulk modules that are separated vertically.

  6. Coupling dynamic blow down and pool evaporation model for LNG.

    PubMed

    Woodward, John L

    2007-02-20

    Treating the dynamic effects of accidental discharges of liquefied natural gas (LNG) is important for realistic predictions of pool radius. Two phenomena have important influence on pool spread dynamics, time-varying discharge (blow down) and pool ignition. Time-varying discharge occurs because a punctured LNG tanker or storage tank drains with a decreasing liquid head and decreasing head-space pressure. Pool ignition increases the evaporation rate of a pool and consequently decreases the ultimate pool area. This paper describes an approach to treat these phenomena in a dynamic pool evaporation model. The pool evaporation model developed here has two separate regimes. Early in the spill, momentum forces dominate and the pool spreads independently of pool evaporation rate and the corresponding heat transfer rate. After the average pool depth drops below a minimum value, momentum forces are largely dissipated and the thin edges of the pool completely evaporate, so pool area is established by the heat transfer rate. The maximum extent of a burning pool is predicted to be significantly less than that of an unignited pool because the duration of the first regime is reduced by higher heat transfer rates. The maximum extent of an LNG pool is predicted to be larger upon accounting for blow down compared with using a constant average discharge rate. However, the maximum pool extent occurs only momentarily before retreating. PMID:17184912

  7. Yoga lifestyle intervention reduces blood pressure in HIV-infected adults with cardiovascular disease risk factors

    PubMed Central

    Cade, Todd; Reeds, Dominic N.; Mondy, Kristin E.; Overton, Turner; Grassino, Joseph; Tucker, Shawn; Bopp, Coco; Laciny, Erin; Hubert, Sara; Lassa-Claxton, Sherry; Yarasheski, Kevin E.

    2009-01-01

    People living with human immunodeficiency virus infection (HIV) are at increased risk for developing cardiovascular disease (CVD). Safe and effective interventions for lowering CVD risk in HIV are high priorities. Objective We conducted a prospective, randomized, controlled study to evaluate whether a yoga lifestyle intervention improves CVD risk factors, virologic or immunologic status, or quality of life in HIV-infected adults more than in a matched control group. Methods Sixty HIV-infected adults with mild-moderate CVD risk were assigned to 20 wks of supervised yoga practice or standard of care treatment. Baseline and week 20 measures were; 2hr-oral glucose tolerance test with insulin monitoring, body composition, fasting serum lipid/lipoprotein profile, resting blood pressures, CD4+ T-cell number and plasma HIV RNA, and the Medical Outcomes Study SF-36 health-related quality of life inventory. Results Resting systolic and diastolic blood pressures were reduced more (p=0.04) in the yoga group (−5±2 and −3±1 mmHg) than in the standard of care group (+1±2 and +2±2 mmHg), despite no greater reduction in body weight, fat mass, proatherogenic lipids, or improvements in glucose tolerance or overall quality of life after yoga. Immune and virologic status was not adversely affected. Conclusion Among traditional lifestyle modifications, yoga is a low cost, simple to administer, non-pharmacological, popular behavioral intervention that can lower blood pressure in pre-hypertensive HIV-infected adults with mild-moderate CVD risk factors. PMID:20059570

  8. Differential Scanning Calorimetry of Phyllosilicate Minerals at Reduced Pressures: A Mineral Database for the Thermal Evolved Gas Analyzer (TEGA)

    NASA Technical Reports Server (NTRS)

    Tripathi, A. B.; Ming, D. W.; Lauer, H. V., Jr.; Golden, D. C.; Boynton, W. V.

    2002-01-01

    Reduced pressure thermal analysis measurements of the phyllosilicates kaolinite and nontronite were taken to observe the effect of pressure on their thermal curves. This is part of the database for the TEGA instrument. Additional information is contained in the original extended abstract.

  9. Observations on an evaporative, elbow thermosyphon

    SciTech Connect

    Lock, G.S.H.; Fu, J. )

    1993-05-01

    The performance of the evaporative elbow system was found to be superior to that of the nonevaporative system, but comparable to the performance of the linear system. The parametric role of the evaporator wall temperature, the condenser wall temperature, and the vapor saturation temperature was demonstrated, each revealing a similar monotonic effect. With the evaporator upright, the data were found to be similar to, but displaced from, the upright condenser data. The upright evaporator gave the better performance, but not overwhelmingly so. The limit of performance with the condenser upright was found to be dictated by evaporator dryout. In the upright evaporator configuration, the limit may be attributed to flooding in the poorly draining condenser; this limit was indistinguishable from geyser behavior at low vapor pressures. 16 refs., 3 figs.

  10. Pressure Drop Characteristics in Tight-Lattice Bundles for Reduced-Moderation Water Reactors

    NASA Astrophysics Data System (ADS)

    Tamai, Hidesada; Kureta, Masatoshi; Yoshida, Hiroyuki; Akimoto, Hajime

    The reduced-moderation water reactor (RMWR) consists of several distinctive structures; a triangular tight-lattice configuration and a double-flat core. In order to design the RMWR core from the point of view of thermal-hydraulics, an evaluation method on pressure drop characteristics in the rod bundles at the tight-lattice configuration is required. In this study, calculated results by the Martinelli-Nelson's and Hancox's correlations were compared with experimental results in 4×5 rod bundles and seven-rod bundles. Consequently, the friction loss in two-phase flows becomes smaller at the tight-lattice configuration with the hydraulic diameter less than about 3mm. This reason is due to the difference of the configuration between the multi-rod bundle and the circular tube and due to the effect of the small hydraulic diameter on the two-phase multiplier.

  11. A jazz-based approach for optimal setting of pressure reducing valves in water distribution networks

    NASA Astrophysics Data System (ADS)

    De Paola, Francesco; Galdiero, Enzo; Giugni, Maurizio

    2016-05-01

    This study presents a model for valve setting in water distribution networks (WDNs), with the aim of reducing the level of leakage. The approach is based on the harmony search (HS) optimization algorithm. The HS mimics a jazz improvisation process able to find the best solutions, in this case corresponding to valve settings in a WDN. The model also interfaces with the improved version of a popular hydraulic simulator, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the solutions. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to two case studies, and the obtained results in terms of pressure reductions are comparable with those of competitive metaheuristic algorithms (e.g. genetic algorithms). The results demonstrate the suitability of the HS algorithm for water network management and optimization.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  13. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    Day, S D; Wong, F M G; Gordon, S R; Wong, L L; Rebak, R B

    2003-09-07

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the Yucca Mountain waste package program has been the integrity of container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal to determine their relative corrosion behavior in SCW at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the electrochemical behavior in the three tested solutions.

  14. Means and method for reducing differential pressure loading in an augmented gas turbine engine

    SciTech Connect

    Mayer, J.C.

    1991-12-10

    This patent describes a gas turbine engine having a fan, a core engine for generating combustion exhaust gases, a core outlet for discharging the exhaust gases, a bypass duct for channeling cooling bypass airflow from the fan and over the core engine, a duct outlet for discharging the bypass airflow, an augmentor including an annular combustion liner for receiving therein the exhaust gases and a first portion of the bypass airflow discharged from the duct outlet, and an annular plenum surrounding the liner and having an inlet spaced axially from the bypass duct outlet for receiving from the bypass duct outlet a second portion of the bypass airflow for cooling the augmentor liner. It comprises accelerating the bypass airflow discharged from the bypass duct outlet to a velocity greater than Mach 1 for providing accelerated bypass airflow to the augmentor; and decelerating the accelerated bypass airflow to a velocity less than Mach 1 at the plenum duct inlet for creating pressure losses due to shock waves to the bypass airflow second portion channeled to the plenum for reducing differential pressure acting across the liner.

  15. Focusing polycapillary to reduce parasitic scattering for inelastic x-ray measurements at high pressure

    SciTech Connect

    Chow, P. Xiao, Y. M.; Rod, E.; Bai, L. G.; Shen, G. Y.; Sinogeikin, S.; Gao, N.; Ding, Y.; Mao, H.-K.

    2015-07-15

    The double-differential scattering cross-section for the inelastic scattering of x-ray photons from electrons is typically orders of magnitude smaller than that of elastic scattering. With samples 10-100 μm size in a diamond anvil cell at high pressure, the inelastic x-ray scattering signals from samples are obscured by scattering from the cell gasket and diamonds. One major experimental challenge is to measure a clean inelastic signal from the sample in a diamond anvil cell. Among the many strategies for doing this, we have used a focusing polycapillary as a post-sample optic, which allows essentially only scattered photons within its input field of view to be refocused and transmitted to the backscattering energy analyzer of the spectrometer. We describe the modified inelastic x-ray spectrometer and its alignment. With a focused incident beam which matches the sample size and the field of view of polycapillary, at relatively large scattering angles, the polycapillary effectively reduces parasitic scattering from the diamond anvil cell gasket and diamonds. Raw data collected from the helium exciton measured by x-ray inelastic scattering at high pressure using the polycapillary method are compared with those using conventional post-sample slit collimation.

  16. Pressure-constrained, reduced-DOF, interconnected parallel manipulators with applications to space suit design

    NASA Astrophysics Data System (ADS)

    Jacobs, Shane Earl

    This dissertation presents the concept of a Morphing Upper Torso, an innovative pressure suit design that incorporates robotic elements to enable a resizable, highly mobile and easy to don/doff spacesuit. The torso is modeled as a system of interconnected, pressure-constrained, reduced-DOF, wire-actuated parallel manipulators, that enable the dimensions of the suit to be reconfigured to match the wearer. The kinematics, dynamics and control of wire-actuated manipulators are derived and simulated, along with the Jacobian transforms, which relate the total twist vector of the system to the vector of actuator velocities. Tools are developed that allow calculation of the workspace for both single and interconnected reduced-DOF robots of this type, using knowledge of the link lengths. The forward kinematics and statics equations are combined and solved to produce the pose of the platforms along with the link tensions. These tools allow analysis of the full Morphing Upper Torso design, in which the back hatch of a rear-entry torso is interconnected with the waist ring, helmet ring and two scye bearings. Half-scale and full-scale experimental models are used along with analytical models to examine the feasibility of this novel space suit concept. The analytical and experimental results demonstrate that the torso could be expanded to facilitate donning and doffng, and then contracted to match different wearer's body dimensions. Using the system of interconnected parallel manipulators, suit components can be accurately repositioned to different desired configurations. The demonstrated feasibility of the Morphing Upper Torso concept makes it an exciting candidate for inclusion in a future planetary suit architecture.

  17. Clonidine reduces blood pressure and heart rate oscillations in the conscious rat.

    PubMed

    Grichois, M L; Japundzic, N; Head, G A; Elghozi, J L

    1990-09-01

    We investigated the effects of clonidine on the fluctuations that underlie the spontaneous variability of blood pressure (BP) and heart rate (HR) in conscious rats. Analog-to-digital conversion of the intrafemoral BP was used to determine systolic, diastolic, and mean BP and HR every 200 ms. The equidistant sampling allowed a direct spectral analysis using a fast Fourier transform algorithm. An i.v. dose of 10 micrograms/kg of clonidine markedly reduced the variability of BP and HR after 20 min as indicated by a reduction in the variances by approximately one-half of the control value for BP and to one-third of the control value for HR. At this time, clonidine had not significantly altered BP or HR. Spectral profiles of systolic BP and HR illustrated the alterations in the spontaneous oscillations underlying these variance changes. Clonidine dramatically reduced the amplitude of BP and HR oscillations in the frequency region of 195-605 mHZ, which depends on the activity of the autonomic nervous system. We suggest that an increased sensitivity of the baroreflex is responsible for the apparent better control of BP and HR with clonidine. PMID:1700217

  18. A nanoparticle formulation of disulfiram prolongs corneal residence time of the drug and reduces intraocular pressure.

    PubMed

    Nagai, Noriaki; Yoshioka, Chiaki; Mano, Yu; Tnabe, Wataru; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

    2015-03-01

    The goal in the search for successful therapies for glaucoma is the reduction of intraocular pressure (IOP), and the search for effective eye drops that reduce IOP is a high priority. We previously reported the potential of a 2-hydroxypropyl-β-cyclodextrin (HPβCD) solution containing 0.5% DSF (DSF solution) to provide effective anti-glaucoma treatment in eye drop form. In this study, we designed new ophthalmic formulations containing 0.5% DSF nanoparticles prepared by a bead mill method (DSFnano dispersion; particle size 183 ± 92 nm, mean ± S.D.), and compared the IOP-reducing effects of a DSFnano dispersion with those of a DSF solution. The high stability of the DSFnano dispersion was observed until 7 days after preparation, and the DSFnano dispersion showed high antimicrobial activity against Escherichia coli (ATCC 8739). In transcorneal penetration experiments using rabbit corneas, only diethyldithiocarbamate (DDC) was detected in the aqueous humor, while no DSF was detected. The DDC penetration level (area under the curve, AUC) and corneal residence time (mean residence time, MRT) of the DSFnano dispersion were approximately 1.45- and 1.44-fold higher than those of the DSF, respectively. Moreover, the IOP-reducing effects of the DSFnano dispersion were significantly greater than those of the DSF solution in rabbits (the IOP was enhanced by placing the rabbits in a dark room for 5 h). In addition, DSFnano dispersion are tolerated better by a corneal epithelial cell than DSF solution and commercially available timolol maleate eye drops. It is possible that dispersions containing DSF nanoparticles will provide new possibilities for the effective treatment of glaucoma, and that an ocular drug delivery system using drug nanoparticles may expand their usage as therapy in the ophthalmologic field. These findings provide significant information that can be used to design further studies aimed at developing anti-glaucoma drugs. PMID:25633346

  19. A Quality-Improvement Collaborative Project to Reduce Pressure Ulcers in PICUs

    PubMed Central

    King, Alice; Nie, Ann Marie; Schaffer, Pat; Taylor, Teresa; Pruitt, David; Giaccone, Mary Jo; Ashby, Marshall; Keswani, Sundeep

    2013-01-01

    BACKGROUND AND OBJECTIVE: Pediatric patients are at risk for developing pressure ulcers (PUs) and associated pain, infection risk, and prolonged hospitalization. Stage III and IV ulcers are serious, reportable events. The objective of this study was to develop and implement a quality-improvement (QI) intervention to reduce PUs by 50% in our ICUs. METHODS: We established a QI collaborative leadership team, measured PU rates during an initial period of rapid-cycle tests of change, developed a QI bundle, and evaluated the PU rates after the QI implementation. The prospective study encompassed 1425 patients over 54 351 patient-days in the PICU and NICU. RESULTS: The PU rate in the PICU was 14.3/1000 patient-days during the QI development and 3.7/1000 patient-days after QI implementation (P < .05), achieving the aim of 50% reduction. The PICU rates of stages I, II, and III conventional and device-related PUs decreased after the QI intervention. The PU rate in the NICU did not change significantly over time but remained at a mean of 0.9/1000 patient-days. In the postimplementation period, 3 points were outside the control limits, primarily due to an increase in PUs associated with pulse oximeters and cannulas. CONCLUSIONS: The collaborative QI model was effective at reducing PUs in the PICU. Pediatric patients, particularly neonates, are at risk for device-related ulcers. Heightened awareness, early detection, and identification of strategies to mitigate device-related injury are necessary to further reduce PU rates. PMID:23650292

  20. Iron reduction and mineralization of deep-sea iron reducing bacterium Shewanella piezotolerans WP3 at elevated hydrostatic pressures.

    PubMed

    Wu, W F; Wang, F P; Li, J H; Yang, X W; Xiao, X; Pan, Y X

    2013-11-01

    In this study, iron reduction and concomitant biomineralization of a deep-sea iron reducing bacterium (IRB), Shewanella piezotolerans WP3, were systematically examined at different hydrostatic pressures (0.1, 5, 20, and 50 MPa). Our results indicate that bacterial iron reduction and induced biomineralization are influenced by hydrostatic pressure. Specifically, the iron reduction rate and extent consistently decreases with the increase in hydrostatic pressure. By extrapolation, the iron reduction rate should drop to zero by ~68 MPa, which suggests a possible shut-off of enzymatic iron reduction of WP3 at this pressure. Nano-sized superparamagnetic magnetite minerals are formed under all the experimental pressures; nevertheless, even as magnetite production decreases, the crystallinity and grain size of magnetite minerals increase at higher pressure. These results imply that IRB may play an important role in iron reduction, biomineralization, and biogeochemical cycling in deep-sea environments. PMID:24102974

  1. Innovative, High-Pressure, Cryogenic Control Valve: Short Face-to-Face, Reduced Cost

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A control valve that can throttle high-pressure cryogenic fluid embodies several design features that distinguish it over conventional valves designed for similar applications. Field and design engineers worked together to create a valve that would simplify installation, trim changes, and maintenance, thus reducing overall cost. The seals and plug stem packing were designed to perform optimally in cryogenic temperature ranges. Unlike conventional high-pressure cryogenic valves, the trim size can be changed independent of the body. The design feature that provides flexibility for changing the trim is a split body. The body is divided into an upper and a lower section with the seat ring sandwiched in between. In order to maintain the plug stem packing at an acceptable sealing temperature during cryogenic service, heat-exchanging fins were added to the upper body section. The body is made of stainless steel. The seat ring is made of a nickel-based alloy having a coefficient of thermal expansion less than that of the body material. Consequently, when the interior of the valve is cooled cryogenically, the body surrounding the seat ring contracts more than the seat ring. This feature prevents external leakage at the body-seat joint. The seat ring has been machined to have small, raised-face sealing surfaces on both sides of the seal groove. These sealing surfaces concentrate the body bolt load over a small area, thereby preventing external leakage. The design of the body bolt circle is different from that of conventional highpressure control valves. Half of the bolts clamp the split body together from the top, and half from the bottom side. This bolt-circle design allows a short, clean flow path, which minimizes frictional flow losses. This bolt-circle design also makes it possible to shorten the face-toface length of the valve, which is 25.5 in. (65 cm). In contrast, a conventional, high-pressure control valve face-to-face dimension may be greater than 40 in. (>1 m

  2. Does yoga therapy reduce blood pressure in patients with hypertension?: an integrative review.

    PubMed

    Okonta, Nkechi Rose

    2012-01-01

    The aim of this article was to present a evidence-based integrative research review that validates yoga therapy as an effective complementary treatment in the management of high blood pressure (BP). The article also uses the theoretical framework of Dr Hans Selye's general adaptation syndrome. Yoga researchers demonstrate that yoga works because it modulates the physiological system of the body, specifically its effect on the heart rate. This review is significant because yoga presents an effective method of treating hypertension that is nonpharmacologic and therefore there are no adverse effects and there are other valuable health benefits. Research suggests that stress is a contributing factor to high BP; hence, the use of the general adaptation syndrome and the most important attribute of yoga, that is, it is a physical and mental exercise program, that is in sync with the philosophy of holistic nursing care where one treats the whole individual and not just the disease. The review was conducted with a search of computerized databases such as OVID, Academic Search Premier, CINAHL, MEDLINE, and Health Source: Nursing/Academic edition, PsychINFO, as well as reliable Web sites such as the cdc.gov, among others. An integrative review search was conducted, and 10 studies met the inclusion criteria. They include a combination of randomized controlled trials, quasi-experimental studies, and pilot studies. Yoga therapy is a multifunctional exercise modality with numerous benefits. Not only does yoga reduce high BP but it has also been demonstrated to effectively reduce blood glucose level, cholesterol level, and body weight, major problems affecting the American society. The completed integrative review provides guidelines for nursing implementation as a complementary treatment of high BP. PMID:22517349

  3. Low-Sodium DASH Diet Reduces Blood Pressure, Arterial Stiffness, and Oxidative Stress in Hypertensive HFPEF

    PubMed Central

    Hummel, Scott L.; Seymour, E. Mitchell; Brook, Robert D.; Kolias, Theodore J.; Sheth, Samar S.; Rosenblum, Hannah R.; Wells, Joanna M.; Weder, Alan B.

    2012-01-01

    Recent studies suggest that oxidative stress and vascular dysfunction contribute to heart failure with preserved ejection fraction (HFPEF). In ‘salt-sensitive’ HFPEF animal models, diets low in sodium and high in potassium, calcium, magnesium, and antioxidants attenuate oxidative stress and cardiovascular damage. We hypothesized that the sodium-restricted Dietary Approaches to Stop Hypertension diet (DASH/SRD) would have similar effects in human hypertensive HFPEF. Thirteen patients with treated hypertension and compensated HFPEF consumed the DASH/SRD for 21 days (all food/most beverages provided). The DASH/SRD reduced clinic systolic (155 to 138 mmHg, p=.02) and diastolic BP (79 to 72 mmHg, p=.04), 24-hour ambulatory systolic (130 to 123 mmHg, p=.02) and diastolic BP (67 to 62 mmHg, p=.02), and carotid-femoral pulse wave velocity (12.4 to 11.0 m/s, p=.03). Urinary F2-isoprostanes decreased by 31% (209 to 144 pmol/mmol Cr, p=.02) despite increased urinary aldosterone excretion. The reduction in urinary F2-isoprostanes closely correlated with the reduction in urinary sodium excretion on the DASH/SRD. In this cohort of HFPEF patients with treated hypertension, the DASH/SRD reduced systemic blood pressure, arterial stiffness, and oxidative stress. These findings are characteristic of ‘salt-sensitive’ hypertension, a phenotype present in many HFPEF animal models, and suggest shared pathophysiological mechanisms linking these two conditions. Further dietary modification studies could provide insights into the development and progression of hypertensive HFPEF. PMID:23033371

  4. DWPF Recycle Evaporator Simulant Tests

    SciTech Connect

    Stone, M

    2005-04-05

    Testing was performed to determine the feasibility and processing characteristics of an evaporation process to reduce the volume of the recycle stream from the Defense Waste Processing Facility (DWPF). The concentrated recycle would be returned to DWPF while the overhead condensate would be transferred to the Effluent Treatment Plant. Various blends of evaporator feed were tested using simulants developed from characterization of actual recycle streams from DWPF and input from DWPF-Engineering. The simulated feed was evaporated in laboratory scale apparatus to target a 30X volume reduction. Condensate and concentrate samples from each run were analyzed and the process characteristics (foaming, scaling, etc) were visually monitored during each run. The following conclusions were made from the testing: Concentration of the ''typical'' recycle stream in DWPF by 30X was feasible. The addition of DWTT recycle streams to the typical recycle stream raises the solids content of the evaporator feed considerably and lowers the amount of concentration that can be achieved. Foaming was noted during all evaporation tests and must be addressed prior to operation of the full-scale evaporator. Tests were conducted that identified Dow Corning 2210 as an antifoam candidate that warrants further evaluation. The condensate has the potential to exceed the ETP WAC for mercury, silicon, and TOC. Controlling the amount of equipment decontamination recycle in the evaporator blend would help meet the TOC limits. The evaporator condensate will be saturated with mercury and elemental mercury will collect in the evaporator condensate collection vessel. No scaling on heating surfaces was noted during the tests, but splatter onto the walls of the evaporation vessels led to a buildup of solids. These solids were difficult to remove with 2M nitric acid. Precipitation of solids was not noted during the testing. Some of the aluminum present in the recycle streams was converted from gibbsite to

  5. Effect of pressure-reducing devices on the quality of anterior orbit anesthesia.

    PubMed

    Riad, Waleed

    2011-06-01

    Needle length is an important consideration in the safe conduct of ophthalmic blocks. A shorter needle could be used to insert the local anesthetic before the globe equator in the anterior orbit and to direct the injectable posteriorly using Honan's balloon to produce the desired effect. However, the use of pressure-reducing devices is not advisable in procedures with impaired retinal blood flow. The aim of this work was to demonstrate the effect of ocular compression with a Honan's balloon on the quality of peribulbar anesthesia when a short needle was used. The blockades were performed in 120 patients using a 27 G, half-inch-long needle. The needle was inserted into the inferotemporal quadrant adherent to the inferior orbital notch. The 7 to 10 ml of local anesthetic solution, consisting of bupivacaine 0.5%, lidocaine 2% in a ratio of 3:2 with hyaluronidase 5 U/ml, was injected followed by application of Honan's balloon or no compression. Ocular akinesia was assessed 10 min later; if inadequate, supplementary anesthesia was provided. No difference was detected in terms of volume injected, supplementation, and akinesia score. Under the conditions of this study, Honan's balloon did not contribute to the quality of the anterior orbit anesthesia, and the technique can be successfully used when ocular compression is contraindicated. PMID:21409353

  6. Reducing stroke in women with risk factor management: blood pressure and cholesterol.

    PubMed

    Baghshomali, Sanam; Bushnell, Cheryl

    2014-09-01

    Stroke is a major cause of death and disability in adults worldwide. Prevention focused on modifiable risk factors, such as hypertension and hyperlipidemia, has shown them to be of significant importance in decreasing the risk of stroke. Multiple studies have brought to light the differences between men and women with regards to stroke and these risk factors. Women have a higher prevalence of stroke, mortality and disability and it has been shown that preventive and treatment options are not as comprehensive for women. Hence, it is of great necessity to evaluate and summarize the differences in gender and stroke risk factors in order to target disparities and optimize prevention, especially because women have a higher lifetime risk of stroke. The purpose of this review is to summarize sex differences in the prevalence of hypertension and hyperlipidemia. In addition, we will review the sex differences in stroke prevention effectiveness and adherence to blood pressure and cholesterol medications, and suggest future directions for research to reduce the burden of stroke in women. PMID:25335544

  7. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    Day, S D; Wong, F G; Gordon, S R; Wong, L L; Rebak, R B

    2006-02-05

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.

  8. Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

    2006-05-08

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.

  9. Evaporator Cleaning Studies

    SciTech Connect

    Wilmarth, W.R.

    1999-04-15

    Operation of the 242-16H High Level Waste Evaporator proves crucial to liquid waste management in the H-Area Tank Farm. Recent operational history of the Evaporator showed significant solid formation in secondary lines and in the evaporator pot. Additional samples remain necessary to ensure material identity in the evaporator pot. Analysis of these future samples will provide actinide partitioning information and dissolution characteristics of the solid material from the pot to ensure safe chemical cleaning.

  10. Evaporative cooling in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Maltezos, George; Rajagopal, Aditya; Scherer, Axel

    2006-08-01

    Evaporative cooling is an effective and energy efficient way to rapidly remove heat from a system. Specifically, evaporative cooling in microfluidic channels can provide a cost-effective solution for the cooling of electronic devices and chemical reactors. Here we present microfluidic devices fabricated by using soft-lithography techniques to form simple fluidic junctions between channels carrying refrigerant and channels carrying N2 gas. The effects of channel geometry and delivery pressure on the performance of refrigeration through vaporization of acetone, isopropyl alcohol, and ethyl ether were characterized. By varying gas inlet pressures, refrigerants, and angles of the microfluidic junctions, optimal cooling conditions were found. Refrigeration rates in excess of 40°C/s were measured, and long lasting subzero cooling in the junction could be observed.

  11. A requirement for reduced pressure and modified atmosphere composition in lunar and martian biological life support systems

    NASA Astrophysics Data System (ADS)

    Dixon, Mike; Stasiak, Michael; Wehkamp, Cara Ann; Lawson, Jamie

    The Controlled Environment Systems Research Facility at the PlaceTypeUniversity of Place- NameGuelph (country-regionplaceCanada) represents an extensive collection of variable pressure plant growth chambers devoted to the study of biological systems including plants and microbes, in life support roles for space exploration. To simplify engineering requirements for plant growth structures on the Moon or Mars, lower pressures are required in order to reduce mass and decrease atmospheric leakage. Few facilities exist that can provide low pressure plant growth capabilities coupled with complete control over temperature, vapour pressure deficit (humidity), gas composition, nutrient delivery, and pressure. The Controlled Environment Systems Research Facility maintains five canopy-scale hypobaric plant growth chambers with capabilities ideally suited for low pressure advanced life support research. System performance evaluations during low pressure experiments on radish (Raphanus sativa L. cv. Cherry Bomb II) have demonstrated temperature control of +/- 0.5 ° C, vapour pressure deficit control of +/- 0.5 mb, CO2 injection control of +/- 20 ` ımol mol-1 , and leakage rates of less than 1% per day. Keywords: hypobaric, plant growth chamber, advanced life support, controlled environment, low pressure, atmospheric control

  12. Continuous positive airway pressure therapy reduces oxidative stress markers and blood pressure in sleep apnea-hypopnea syndrome patients.

    PubMed

    Murri, Mora; García-Delgado, Regina; Alcázar-Ramírez, José; Fernández de Rota, Luis; Fernández-Ramos, Ana; Cardona, Fernando; Tinahones, Francisco J

    2011-12-01

    Sleep apnea-hypopnea syndrome (SAHS) is characterized by recurrent episodes of hypoxia/reoxygenation, which seems to promote oxidative stress. SAHS patients experience increases in hypertension, obesity and insulin resistance (IR). The purpose was to evaluate in SAHS patients the effects of 1 month of treatment with continuous positive airway pressure (CPAP) on oxidative stress and the association between oxidative stress and insulin resistance and blood pressure (BP). Twenty-six SAHS patients requiring CPAP were enrolled. Measurements were recorded before and 1 month after treatment. Cellular oxidative stress parameters were notably decreased after CPAP. Intracellular glutathione and mitochondrial membrane potential increased significantly. Also, total antioxidant capacity and most of the plasma antioxidant activities increased significantly. Significant decreases were seen in BP. Negative correlations were observed between SAHS severity and markers of protection against oxidative stress. BP correlated with oxidative stress markers. In conclusion, we observed an obvious improvement in oxidative stress and found that it was accompanied by an evident decrease in BP with no modification in IR. Consequently, we believe that the decrease in oxidative stress after 1 month of CPAP treatment in these patients is not contributing much to IR genesis, though it could be related to the hypertension etiology. PMID:21286851

  13. Sheet Membrane Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  14. Evaporation in space manufacturing

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1974-01-01

    'Normal evaporation' equations for predicting the compositional changes with time and temperature have been developed and correlated with actual experimental data. An evaporative congruent temperature is defined and used to explain, predict, or plan space experiments on anomalous constitutional melting (on cooling) or solidification (on heating). Uneven evaporation causes reactive jetting forces capable of initiating new convection currents, nongravitational accelerations, surface vibrations, or other disturbances. Applications of evaporation to space manufacturing are described concerning evaporative purification, surface cooling, specimen selection, particles splitting, freezing data interpretation, material loss and dimensional control, and surface contamination or compositional changes.

  15. Hydrogen storage in insulated pressure vessels

    SciTech Connect

    Aceves, S.M.; Garcia-Villazana, O.

    1998-08-01

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). This paper shows an evaluation of the applicability of the insulated pressure vessels for light-duty vehicles. The paper shows an evaluation of evaporative losses and insulation requirements and a description of the current analysis and experimental plans for testing insulated pressure vessels. The results show significant advantages to the use of insulated pressure vessels for light-duty vehicles.

  16. Use of continuous positive airway pressure reduces airway reactivity in adults with asthma

    PubMed Central

    Busk, Michael; Busk, Nancy; Puntenney, Paula; Hutchins, Janet; Yu, Zhangsheng; Gunst, Susan J.; Tepper, Robert S.

    2015-01-01

    Asthma is characterised by airway hyperreactivity, which is primarily treated with β-adrenergic bronchodilators and anti-inflammatory agents. However, mechanical strain during breathing is an important modulator of airway responsiveness and we have previously demonstrated in animal models that continuous positive airway pressure (CPAP) resulted in lower in vivo airway reactivity. We now evaluated whether using nocturnal CPAP decreased airway reactivity in clinically-stable adults with asthma. Adults with stable asthma and normal spirometry used nocturnal CPAP (8–10 cmH2O) or sham treatment (0–2 cmH2O) for 7 days. Spirometry and bronchial challenges were obtained before and after treatment. The primary outcome was the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC20). The CPAP group (n=16) had a significant decrease in airway reactivity (change in (Δ)logPC20 0.406, p<0.0017) while the sham group (n=9) had no significant change in airway reactivity (ΔlogPC20 0.003, p=0.9850). There was a significant difference in the change in airway reactivity for the CPAP versus the sham group (ΔlogPC20 0.41, p<0.043). Our findings indicate that chronic mechanical strain of the lungs produced using nocturnal CPAP for 7 days reduced airway reactivity in clinically stable asthmatics. Future studies of longer duration are required to determine whether CPAP can also decrease asthma symptoms and/or medication usage. PMID:22835615

  17. Reducing False Alarm Rates for Critical Arrhythmias Using the Arterial Blood Pressure Waveform

    PubMed Central

    Aboukhalil, Anton; Nielsen, Larry; Saeed, Mohammed; Mark, Roger G.; Clifford, Gari D.

    2008-01-01

    Background Over the past two decades, high false alarm (FA) rates have remained an important yet unresolved concern in the Intensive Care Unit (ICU). High FA rates lead to desensitization of the attending staff to such warnings, with associated slowing in response times and detrimental decreases in the quality of care for the patient. False arrhythmia alarms are commonly due to single channel ECG artifacts and low voltage signals, and therefore it is likely that the FA rates may be reduced if information from other independent signals is used to form a more robust hypothesis of the alarm’s etiology. Methods A large multi-parameter ICU database (PhysioNet’s MIMIC II database) was used to investigate the frequency of five categories of false critical (“red” or “life-threatening”) ECG arrhythmia alarms produced by a commercial ICU monitoring system, namely: asystole, extreme bradycardia, extreme tachycardia, ventricular tachycardia and ventricular fibrillation/tachycardia. Non-critical (“yellow”) arrhythmia alarms were not considered in this study. Multiple expert reviews of 5,386 critical ECG arrhythmia alarms from a total of 447 adult patient records in the MIMIC II database were made using the associated 41,301 hours of simultaneous ECG and arterial blood pressure (ABP) waveforms. An algorithm to suppress false critical ECG arrhythmia alarms using morphological and timing information derived from the ABP signal was then tested. Results An average of 42.7% of the critical ECG arrhythmia alarms were found to be false, with each of the five alarm categories having FA rates between 23.1% and 90.7%. The FA suppression algorithm developed was able to suppress 59.7% of the false alarms, with FA reduction rates as high as 93.5% for asystole and 81.0% for extreme bradycardia. FA reduction rates were lowest for extreme tachycardia (63.7%) and ventricular-related alarms (58.2% for ventricular fibrillation/tachycardia and 33.0% for ventricular tachycardia

  18. Chronotherapy with conventional blood pressure medications improves management of hypertension and reduces cardiovascular and stroke risks.

    PubMed

    Hermida, Ramón C; Ayala, Diana E; Smolensky, Michael H; Fernández, José R; Mojón, Artemio; Portaluppi, Francesco

    2016-05-01

    Correlation between blood pressure (BP) and target organ damage, vascular risk and long-term patient prognosis is greater for measurements derived from around-the-clock ambulatory BP monitoring than in-clinic daytime ones. Numerous studies consistently substantiate the asleep BP mean is both an independent and a much better predictor of cardiovascular disease (CVD) risk than either the awake or 24 h means. Sleep-time hypertension is much more prevalent than suspected, not only in patients with sleep disorders, but also among those who are elderly or have type 2 diabetes, chronic kidney disease or resistant hypertension. Hence, cost-effective adequate control of sleep-time BP is of marked clinical relevance. Ingestion time, according to circadian rhythms, of hypertension medications of six different classes and their combinations significantly affects BP control, particularly sleep-time BP, and adverse effects. For example, because the high-amplitude circadian rhythm of the renin-angiotensin-aldosterone system activates during nighttime sleep, bedtime vs. morning ingestion of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers better reduces the asleep BP mean, with additional benefit, independent of medication terminal half-life, of converting the 24 h BP profile into more normal dipper patterning. The MAPEC (Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares) study, first prospective randomized treatment-time investigation designed to test the worthiness of bedtime chronotherapy with ⩾1 conventional hypertension medications so as to specifically target attenuation of asleep BP, demonstrated, relative to conventional morning therapy, 61% reduction of total CVD events and 67% decrease of major CVD events, that is, CVD death, myocardial infarction, and ischemic and hemorrhagic stroke. The MAPEC study, along with other earlier conducted less refined trials, documents the asleep BP mean is the most significant

  19. The Reamer/Irrigator/Aspirator Reduces Femoral Canal Pressure in Simulated TKA

    PubMed Central

    Van Gorp, Cornel C.; Falk, James V.; Kmiec, Stanley J.

    2008-01-01

    Inserting the femoral intramedullary alignment rod during total knee arthroplasty (TKA) can generate high intramedullary pressure, which increases the risk of intraoperative complications caused by fat embolism. Despite modifications to the surgical procedure, the best method to prevent this increase in pressure remains unknown. The reamer/irrigator/aspirator is a surgical instrument designed for use during femoral canal entry to increase the canal size and remove intramedullary fat and may prevent this pressure increase. We posed two hypotheses: (1) using the reamer/irrigator/aspirator system will result in lower maximum femoral intramedullary pressure than using only conventional instrumentation during the initial steps of a TKA; and (2) using the reamer/irrigator/aspirator system in the initial steps of TKA will result in a mean maximum intramedullary pressure less than 200 mm Hg. We simulated a TKA on 14 cadaveric femurs to compare the femoral intramedullary pressure using both methods. Considerable decreases in femoral intramedullary pressure of 86% proximally and 87% distally were obtained by using the reamer/irrigator/aspirator system. The mean maximum pressure using the reamer/irrigator/aspirator system was less than 200 mm Hg. Additional clinical studies are needed to confirm any reduction in complications using the reamer/irrigator/aspirator system. PMID:18425558

  20. An optimized design of in-shoe heel lifts reduces plantar pressure of healthy males.

    PubMed

    Zhang, Xianyi; Li, Bo; Liang, Kaiyun; Wan, Qiufeng; Vanwanseele, Benedicte

    2016-06-01

    Conventional heel lift with a flat surface increases the risk of foot problems related to higher plantar pressure and decreased stability. In this study, an optimized design of in-shoe heel lifts developed to maintain the midfoot function was tested to investigate if the plantar pressure distribution was improved. The design was based on three dimensional foot plantar contour which was captured by an Infoot 3D scanning system while the heel was elevated by a heel wedge. To facilitate midfoot function, an arch support was designed to support the lateral longitudinal arch, while allowing functional movement of the medial longitudinal arch. Twenty healthy male subjects were asked to walk along an 8m walkway while wearing high-cut footwear with and without the optimized heel lift. Peak pressure, contact area and force-time integral were measured using the Pedar insole system. Range and velocity of medial-lateral center of pressure during forefoot contact phase and foot flat phase were collected using a Footscan pressure plate. Compared to the shoe only condition, peak pressure under the rearfoot decreased with the optimized heel lift, while no increase of peak pressure was observed under the forefoot and midfoot regions, indicating improved plantar pressure distribution. The findings of this study suggest that this optimized heel lift has better biomechanical performance than a conventional flat heel lift. Results from this study may have implications for insole and shoe last design, especially for people who need additional heel height without sacrificing midfoot function. PMID:27264401

  1. Evaporation drift of pesticides active ingredients.

    PubMed

    De Schampheleire, M; Nuyttens, D; De Keyser, D; Spanoghe, P

    2008-01-01

    Losses of pesticide active ingredients (a.i.) into the atmosphere can occur through several pathways. A main pathway is evaporation drift. The evaporation process of pesticide a.i., after application, is affected by three main factors: Physicochemical properties of the pesticide a.i., weather conditions and crop structure. The main physicochemical parameters are the Henry coefficient, which is a measure for the volatilization tendency of the pesticide a.i. from a dilute aqueous solution, and the vapour pressure, which is a measure for the volatilization tendency of the pesticide a.i. from the solid phase. Five pesticide a.i., with various Henry coefficients and various vapour pressures, were selected to conduct laboratory experiments: metalaxyl-m, dichlorovos, diazinon, Lindane and trifluralin. Evaporation experiments were conducted in a volatilization chamber. It was found that the evaporation tendencies significantly differed according to the physicochemical properties of the a.i. PMID:19226822

  2. Effects of reduced pressure and additives on streamers in white oil in long point-plane gap

    NASA Astrophysics Data System (ADS)

    Dung, N. V.; Høidalen, H. K.; Linhjell, D.; Lundgaard, L. E.; Unge, M.

    2013-06-01

    Recent experiments show that modern dielectric liquids behave differently from traditional mineral oil, particularly with respect to breakdown voltages for lightning impulse. This paper describes an experimental investigation addressing underlying reasons for this. The influences of reduced pressure and additives on streamers in white oil were investigated under both positive and negative polarities using an 8 cm long point-plane gap. Reduced pressure significantly accelerates streamers, thus increasing stopping length and reducing both breakdown and acceleration voltages. With increasing applied voltage, different typical propagation modes of streamers were recorded for both polarities. A low ionization potential additive strongly affects positive streamers. It significantly changes streamer velocity and reduces the breakdown voltage but increases the acceleration voltage where breakdown streamer velocity increases drastically. Adding an electron scavenger influences streamers of both polarities, but it mainly increases the velocity of negative streamers and results in a reduction of both the breakdown and the acceleration voltages. The propagation mechanisms of streamers are also discussed.

  3. The evaporative gas turbine (EGT) cycle

    SciTech Connect

    Horlock, J.H.

    1998-04-01

    Humidification of the flow through a gas turbine has been proposed in a variety of forms. The STIG plant involves the generation of steam by the gas turbine exhaust in a heat recovery steam generator (HRSG), and its injection into or downstream of the combustion chamber. This increases the mass flow through the turbine and the power output from the plant, with a small increase in efficiency. In the evaporative gas turbine (or EGT) cycle, water is injected in the compressor discharge in a regenerative gas turbine cycle (a so-called CBTX plant--compressor [C], burner [B], turbine [T], heat exchanger [X]); the air is evaporatively cooled before it enters the heat exchanger. While the addition of water increases the turbine mass flow and power output, there is also apparent benefit in reducing the temperature drop in the exhaust stack. In one variation of the basic EGT cycle, water is also added downstream of the evaporative aftercooler, even continuously in the heat exchanger. There are several other variations on the basic cycle (e.g., the cascaded humidified advanced turbine [CHAT]). The present paper analyzes the performance of the EGT cycle. The basic thermodynamics are first discussed, and related to the cycle analysis of a dry regenerative gas turbine plant. Subsequently some detailed calculations of EGT cycles are presented. The main purpose of the work is to seek the optimum pressure ratio in the EGT cycle for given constraints (e.g., fixed maximum to minimum temperature). It is argued that this optimum has a relatively low value.

  4. Temperature and pressure adaptation of a sulfate reducer from the deep subsurface

    PubMed Central

    Fichtel, Katja; Logemann, Jörn; Fichtel, Jörg; Rullkötter, Jürgen; Cypionka, Heribert; Engelen, Bert

    2015-01-01

    Microbial life in deep marine subsurface faces increasing temperatures and hydrostatic pressure with depth. In this study, we have examined growth characteristics and temperature-related adaptation of the Desulfovibrio indonesiensis strain P23 to the in situ pressure of 30 MPa. The strain originates from the deep subsurface of the eastern flank of the Juan de Fuca Ridge (IODP Site U1301). The organism was isolated at 20°C and atmospheric pressure from ~61°C-warm sediments approximately 5 m above the sediment–basement interface. In comparison to standard laboratory conditions (20°C and 0.1 MPa), faster growth was recorded when incubated at in situ pressure and high temperature (45°C), while cell filamentation was induced by further compression. The maximum growth temperature shifted from 48°C at atmospheric pressure to 50°C under high-pressure conditions. Complementary cellular lipid analyses revealed a two-step response of membrane viscosity to increasing temperature with an exchange of unsaturated by saturated fatty acids and subsequent change from branched to unbranched alkyl moieties. While temperature had a stronger effect on the degree of fatty acid saturation and restructuring of main phospholipids, pressure mainly affected branching and length of side chains. The simultaneous decrease of temperature and pressure to ambient laboratory conditions allowed the cultivation of our moderately thermophilic strain. This may in turn be one key to a successful isolation of microorganisms from the deep subsurface adapted to high temperature and pressure. PMID:26500624

  5. Temperature and pressure adaptation of a sulfate reducer from the deep subsurface.

    PubMed

    Fichtel, Katja; Logemann, Jörn; Fichtel, Jörg; Rullkötter, Jürgen; Cypionka, Heribert; Engelen, Bert

    2015-01-01

    Microbial life in deep marine subsurface faces increasing temperatures and hydrostatic pressure with depth. In this study, we have examined growth characteristics and temperature-related adaptation of the Desulfovibrio indonesiensis strain P23 to the in situ pressure of 30 MPa. The strain originates from the deep subsurface of the eastern flank of the Juan de Fuca Ridge (IODP Site U1301). The organism was isolated at 20°C and atmospheric pressure from ~61°C-warm sediments approximately 5 m above the sediment-basement interface. In comparison to standard laboratory conditions (20°C and 0.1 MPa), faster growth was recorded when incubated at in situ pressure and high temperature (45°C), while cell filamentation was induced by further compression. The maximum growth temperature shifted from 48°C at atmospheric pressure to 50°C under high-pressure conditions. Complementary cellular lipid analyses revealed a two-step response of membrane viscosity to increasing temperature with an exchange of unsaturated by saturated fatty acids and subsequent change from branched to unbranched alkyl moieties. While temperature had a stronger effect on the degree of fatty acid saturation and restructuring of main phospholipids, pressure mainly affected branching and length of side chains. The simultaneous decrease of temperature and pressure to ambient laboratory conditions allowed the cultivation of our moderately thermophilic strain. This may in turn be one key to a successful isolation of microorganisms from the deep subsurface adapted to high temperature and pressure. PMID:26500624

  6. New Directions for Evaporative Cooling Systems.

    ERIC Educational Resources Information Center

    Robison, Rita

    1981-01-01

    New energy saving technology can be applied to older cooling towers; in addition, evaporative chilling, a process that links a cooling tower to the chilling equipment, can reduce energy use by 80 percent. (Author/MLF)

  7. Evaporation mitigation using floating modular devices

    NASA Astrophysics Data System (ADS)

    Hassan, M. Mahmudul; Peirson, William Leslie; Neyland, Bryce M.; Fiddis, Nicholas McQuistan

    2015-11-01

    Reducing evaporation losses from open water storages is of paramount importance in the improvement of water security in arid countries, including Australia. Widespread adoption of evaporation mitigation techniques has been prevented by their high capital and maintenance or operating costs. The use of clean, floating recycled materials to mitigate evaporation technique has been investigated systematically at sites within both the coastal and semi-arid zones of Australia. Evaporation reduction systematically increases with the proportion of covered surface. Evaporation is reduced by 43% at coastal site and 37% at arid zone site at the maximum packing densities achievable for a single layer of floating devices. The study highlights the importance of both long-term investigations and the climatic influences in the robust quantification of evaporation mitigation. The effects of solar radiation, temperature, wind speed and relative humidity on the evaporation rate at both study sites have been determined in terms of both the classical Penman model and FAO Penman Monteith model with corresponding pan coefficients quantified. FAO Penman Monteith model better estimates evaporation from the open reference tank.

  8. Aerobic endurance training reduces bubble formation and increases survival in rats exposed to hyperbaric pressure

    PubMed Central

    Wisløff, Ulrik; Brubakk, Alf O

    2001-01-01

    The formation of bubbles is the basis for injury to divers after decompression, a condition known as decompression illness. In the present study we investigated the effect of endurance training in the rat on decompression-induced bubble formation. A total of 52 adult female Sprague-Dawley rats (300-370 g) were randomly assigned to one of two experimental groups: training or sedentary control. Trained rats exercised on a treadmill for 1.5 h per day for 1 day, or for 2 or 6 weeks (5 days per week) at exercise intervals that alternated between 8 min at 85-90 % of maximal oxygen uptake (V̇O2,max) and 2 min at 50-60 % of V̇O2,max. Rats were compressed (simulated dive) in a decompression chamber in pairs, one sedentary and one trained, at a rate of 200 kPa min−1 to a pressure of 700 kPa, and maintained for 45 min breathing air. At the end of the exposure period, rats were decompressed linearly to the ‘surface’ (100 kPa) at a rate of 50 kPa min−1. Immediately after reaching the ‘surface’ (100 kPa) the animals were anaesthetized and the right ventricle was insonated using Doppler ultrasound. Intensity-controlled interval training significantly increased V̇O2,max by 12 and 60 % after 2 and 6 weeks, respectively. At 6 weeks, left and right ventricular weights were 14 and 17 % higher, respectively, in trained compared to control rats. No effect of training was observed on skeletal muscle weight. Bubble formation was significantly reduced in trained rats after both 2 and 6 weeks. However, the same effect was seen after a single bout of aerobic exercise lasting 1.5 h on the day prior to decompression. All of the rats that exercised for 1.5 h and 2 weeks, and most of those that trained for 6 weeks, survived the protocol, whereas most sedentary rats died within 60 min post-decompression. This study shows that aerobic exercise protects rats from severe decompression and death. This may be a result of less bubbling in the trained animals. The data showed that the

  9. Development of Advanced ISS-WPA Catalysts for Organic Oxidation at Reduced Pressure/Temperature

    NASA Technical Reports Server (NTRS)

    Yu, Ping; Nalette, Tim; Kayatin, Matthew

    2016-01-01

    The Water Processor Assembly (WPA) at International Space Station (ISS) processes a waste stream via multi-filtration beds, where inorganic and non-volatile organic contaminants are removed, and a catalytic reactor, where low molecular weight organics not removed by the adsorption process are oxidized at elevated pressure in the presence of oxygen and elevated temperature above the normal water boiling point. Operation at an elevated pressure requires a more complex system design compared to a reactor that could operate at ambient pressure. However, catalysts currently available have insufficient activity to achieve complete oxidation of the organic load at a temperature less than the water boiling point and ambient pressure. Therefore, it is highly desirable to develop a more active and efficient catalyst at ambient pressure and a moderate temperature that is less than water boiling temperature. This paper describes our efforts in developing high efficiency water processing catalysts. Different catalyst support structures and coating metals were investigated in subscale reactors and results were compared against the flight WPA catalyst. Detailed improvements achieved on alternate metal catalysts at ambient pressure and 200 F will also be presented in the paper.

  10. The Effect of an e-Health Intervention Designed to Reduce Prolonged Occupational Sitting on Mean Arterial Pressure

    PubMed Central

    Cooley, Paul D.; Fraser, Sharon P.; Pedersen, Scott J.

    2014-01-01

    Objective: To evaluate the effect of a workplace health intervention designed to reduce prolonged occupational sitting on the mean arterial pressure (MAP) of desk-based employees. Methods: This randomized controlled trial involved an experimental group who received an e-health intervention and a control group who did not. The 13-week intervention passively prompted participants to stand and engage in short bouts of office-based physical activity by interrupting prolonged occupational sitting time periodically throughout the workday. Mean arterial pressure was measured at pretest and posttest. Results: Between pretest and posttest the experimental group significantly reduced their MAP, whereas MAP in the control group did not. Conclusions: A workplace e-health intervention designed to reduce prolonged occupational sitting was effective in decreasing MAP in desk-based employees. PMID:25376414

  11. Laboratory prototype flash evaporator

    NASA Technical Reports Server (NTRS)

    Gaddis, J. L.

    1972-01-01

    A laboratory prototype flash evaporator that is being developed as a candidate for the space shuttle environmental control system expendable heat sink is described. The single evaporator configuration uses water as an evaporant to accommodate reentry and on-orbit peak heat loads, and Freon 22 for terrestrial flight phases below 120,000 feet altitude. The design features, fabrication techniques used for the prototype unit, redundancy considerations, and the fluid temperature control arrangement are reported in detail. The results of an extensive test program to determine the evaporator operational characteristics under a wide variety of conditions are presented.

  12. Reduced Pressure Atmosphere Impacts on Life Support and Internal Thermal Systems

    NASA Technical Reports Server (NTRS)

    Anderson, Molly

    2006-01-01

    Selecting the appropriate atmosphere for a spacecraft and mission is a complicated problem. NASA has previously used atmospheres from Earth normal composition and pressure to pure oxygen at low pressures. Future exploration missions will likely strike a compromise somewhere between the two, trying to balance operation impacts on EVA, safety concerns for flammability and health risks, life science and physiology questions, and other issues. Life support systems and internal thermal control systems are areas that will have to respond to changes in the atmospheric composition and pressure away from the Earthlike conditions currently used on the International Space Station. This paper examines life support and internal thermal control technologies currently in use or in development to find what impacts in design, efficiency and performance, or feasibility might be expected. Understanding these changes should be helpful in producing better results during future trade studies or mission analyses.

  13. Growth of Anaerobic Methane-Oxidizing Archaea and Sulfate-Reducing Bacteria in a High-Pressure Membrane Capsule Bioreactor

    PubMed Central

    Gieteling, Jarno; Widjaja-Greefkes, H. C. Aura; Plugge, Caroline M.; Stams, Alfons J. M.; Lens, Piet N. L.; Meulepas, Roel J. W.

    2014-01-01

    Communities of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB) grow slowly, which limits the ability to perform physiological studies. High methane partial pressure was previously successfully applied to stimulate growth, but it is not clear how different ANME subtypes and associated SRB are affected by it. Here, we report on the growth of ANME-SRB in a membrane capsule bioreactor inoculated with Eckernförde Bay sediment that combines high-pressure incubation (10.1 MPa methane) and thorough mixing (100 rpm) with complete cell retention by a 0.2-μm-pore-size membrane. The results were compared to previously obtained data from an ambient-pressure (0.101 MPa methane) bioreactor inoculated with the same sediment. The rates of oxidation of labeled methane were not higher at 10.1 MPa, likely because measurements were done at ambient pressure. The subtype ANME-2a/b was abundant in both reactors, but subtype ANME-2c was enriched only at 10.1 MPa. SRB at 10.1 MPa mainly belonged to the SEEP-SRB2 and Eel-1 groups and the Desulfuromonadales and not to the typically found SEEP-SRB1 group. The increase of ANME-2a/b occurred in parallel with the increase of SEEP-SRB2, which was previously found to be associated only with ANME-2c. Our results imply that the syntrophic association is flexible and that methane pressure and sulfide concentration influence the growth of different ANME-SRB consortia. We also studied the effect of elevated methane pressure on methane production and oxidation by a mixture of methanogenic and sulfate-reducing sludge. Here, methane oxidation rates decreased and were not coupled to sulfide production, indicating trace methane oxidation during net methanogenesis and not anaerobic methane oxidation, even at a high methane partial pressure. PMID:25501484

  14. Growth of anaerobic methane-oxidizing archaea and sulfate-reducing bacteria in a high-pressure membrane capsule bioreactor.

    PubMed

    Timmers, Peer H A; Gieteling, Jarno; Widjaja-Greefkes, H C Aura; Plugge, Caroline M; Stams, Alfons J M; Lens, Piet N L; Meulepas, Roel J W

    2015-02-01

    Communities of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB) grow slowly, which limits the ability to perform physiological studies. High methane partial pressure was previously successfully applied to stimulate growth, but it is not clear how different ANME subtypes and associated SRB are affected by it. Here, we report on the growth of ANME-SRB in a membrane capsule bioreactor inoculated with Eckernförde Bay sediment that combines high-pressure incubation (10.1 MPa methane) and thorough mixing (100 rpm) with complete cell retention by a 0.2-m-pore-size membrane. The results were compared to previously obtained data from an ambient-pressure (0.101 MPa methane) bioreactor inoculated with the same sediment. The rates of oxidation of labeled methane were not higher at 10.1 MPa, likely because measurements were done at ambient pressure. The subtype ANME-2a/b was abundant in both reactors, but subtype ANME-2c was enriched only at 10.1 MPa. SRB at 10.1 MPa mainly belonged to the SEEP-SRB2 and Eel-1 groups and the Desulfuromonadales and not to the typically found SEEP-SRB1 group. The increase of ANME-2a/b occurred in parallel with the increase of SEEP-SRB2, which was previously found to be associated only with ANME-2c. Our results imply that the syntrophic association is flexible and that methane pressure and sulfide concentration influence the growth of different ANME-SRB consortia. We also studied the effect of elevated methane pressure on methane production and oxidation by a mixture of methanogenic and sulfate-reducing sludge. Here, methane oxidation rates decreased and were not coupled to sulfide production, indicating trace methane oxidation during net methanogenesis and not anaerobic methane oxidation, even at a high methane partial pressure. PMID:25501484

  15. An effective strategy to reduce blood pressure after forest walking in middle-aged and aged people.

    PubMed

    Horiuchi, Masahiro; Endo, Junko; Akatsuka, Shin; Hasegawa, Tatsuya; Yamamoto, Eriko; Uno, Tadashi; Kikuchi, Sachiko

    2015-12-01

    [Purpose] Forest walking may be effective for human health, but little information is available about effects of energy expenditure on blood pressure responses after forest walking. The aim of this study was to investigate the relationship between the activity energy expenditure and changes in blood pressure in individuals after forest walking. [Subjects] The subjects were 54 middle-aged and elderly people. [Methods] All subjects walked in the forest for approximately 90 min. Blood pressure, salivary amylase, and the Profile of Mood States were evaluated before and after forest walking, and activity energy expenditure was monitored throughout forest walking. Subjects were divided into two groups according to mean arterial pressure changes: a responder group (>5% decreases) and a nonresponder group (<5%). [Results] Forest walking significantly reduced the mean arterial pressure and improved the Profile of Mood States in both groups. Activity energy expenditure was related to changes in mean arterial pressure in the responder group, while this relation was not observed in the nonresponder group. Differential activity energy expenditure did not strongly affect improvement of the Profile of Mood States. [Conclusion] Greater walking-related greater activity energy expenditure might be required to accentuate physiological beneficial effects on in middle-aged and aged people. Furthermore, the forest environment per se can attenuate psychological stress. PMID:26834337

  16. An effective strategy to reduce blood pressure after forest walking in middle-aged and aged people

    PubMed Central

    Horiuchi, Masahiro; Endo, Junko; Akatsuka, Shin; Hasegawa, Tatsuya; Yamamoto, Eriko; Uno, Tadashi; Kikuchi, Sachiko

    2015-01-01

    [Purpose] Forest walking may be effective for human health, but little information is available about effects of energy expenditure on blood pressure responses after forest walking. The aim of this study was to investigate the relationship between the activity energy expenditure and changes in blood pressure in individuals after forest walking. [Subjects] The subjects were 54 middle-aged and elderly people. [Methods] All subjects walked in the forest for approximately 90 min. Blood pressure, salivary amylase, and the Profile of Mood States were evaluated before and after forest walking, and activity energy expenditure was monitored throughout forest walking. Subjects were divided into two groups according to mean arterial pressure changes: a responder group (>5% decreases) and a nonresponder group (<5%). [Results] Forest walking significantly reduced the mean arterial pressure and improved the Profile of Mood States in both groups. Activity energy expenditure was related to changes in mean arterial pressure in the responder group, while this relation was not observed in the nonresponder group. Differential activity energy expenditure did not strongly affect improvement of the Profile of Mood States. [Conclusion] Greater walking-related greater activity energy expenditure might be required to accentuate physiological beneficial effects on in middle-aged and aged people. Furthermore, the forest environment per se can attenuate psychological stress. PMID:26834337

  17. Advanced evaporator technology progress report FY 1992

    SciTech Connect

    Chamberlain, D.; Hutter, J.C.; Leonard, R.A.

    1995-01-01

    This report summarizes the work that was completed in FY 1992 on the program {open_quotes}Technology Development for Concentrating Process Streams.{close_quotes} The purpose of this program is to evaluate and develop evaporator technology for concentrating radioactive waste and product streams such as those generated by the TRUEX process. Concentrating these streams and minimizing the volume of waste generated can significantly reduce disposal costs; however, equipment to concentrate the streams and recycle the decontaminated condensates must be installed. LICON, Inc., is developing an evaporator that shows a great deal of potential for this application. In this report, concepts that need to be incorporated into the design of an evaporator operated in a radioactive environment are discussed. These concepts include criticality safety, remote operation and maintenance, and materials of construction. Both solubility and vapor-liquid equilibrium data are needed to design an effective process for concentrating process streams. Therefore, literature surveys were completed and are summarized in this report. A model that is being developed to predict vapor phase compositions is described. A laboratory-scale evaporator was purchased and installed to study the evaporation process and to collect additional data. This unit is described in detail. Two new LICON evaporators are being designed for installation at Argonne-East in FY 1993 to process low-level radioactive waste generated throughout the laboratory. They will also provide operating data from a full-sized evaporator processing radioactive solutions. Details on these evaporators are included in this report.

  18. Will the Increasing of Anthropogenic Pressures Reduce the Biopotential Value of Sponges?

    PubMed

    Januar, Hedi Indra; Pratitis, Asri; Bramandito, Aditya

    2015-01-01

    Production of bioactive compounds from marine benthic organisms is suggested to relate ecologically with environment. However, anthropogenic pressures cause a considerable damage to coral reefs environment. This research aimed to define the pattern sponges biopotential values at the increasing of anthropogenic pressures to coral reef environment. Three representative sponges were selected (Theonella sp., Hyrtios sp., and Niphates sp.) and study had been conducted in Hoga Island, Indonesia, to define the relationship between seawater variables (DO, pH, phosphate, and ammonia ions), sponges spatial competition, and their bioactivity level (Brine Shrimp Lethality Test). The study showed anthropogenic pressures affect the reef environment, as abiotic cover was increased and eutrophication was detected at the site closer to the run-off domesticated area. Statistical multivariate analyses revealed sponges spatial competition was significantly different (P < 0.05) between groups of high, moderate, and low bioactivity level. Abiotic cover was detected as the major factor (36.19%) contributed to the differences and also the most discriminant factor distinguishing sponges spatial competition in the groups of bioactivity level (93.91%). These results showed the increasing anthropogenic pressures may result in a higher abiotic area and may directly be a consequence to the lower production of bioactive compounds in sponges. PMID:26457226

  19. Measure Guideline: Evaporative Condensers

    SciTech Connect

    German, A; Dakin, B.; Hoeschele, M.

    2012-03-01

    This measure guideline on evaporative condensers provides information on properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices.

  20. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  1. Evaporation of petroleum products from contaminated soils

    SciTech Connect

    Kang, S.H.; Oulman, C.S.

    1996-05-01

    Bioremediation can remove petroleum products from soil that has been contaminated by leaking underground storage tanks, but abiotic processes such as evaporation can contribute significantly to the overall removal process. The mathematical model described in this paper was developed to predict the evaporation rate of volatile liquids from petroleum-contaminated sand. The model is based on simple concepts relating to molecular diffusion embodied in the theory underlying the estimation of binary diffusivities using measurements made with an Arnold diffusion cell. The model in its simplified form indicates that the rate of evaporation for a particular volatile liquid is proportional to the square root of the product of diffusivity and partial pressure divided by the molecular weight of the liquid. This in part explains why evaporative losses from sand are so much higher for gasoline than for diesel fuel. The model also shows that the time for evaporation is directly proportional to the square of the depth dried out and inversely proportional to the vapor pressure of the volatile liquid. The model was tested using gravimetric measurements of the evaporation of n-heptane, unleaded gasoline, and diesel fuel from sand under laboratory conditions.

  2. Aortic distensibility is reduced during intense lower body negative pressure and is related to low frequency power of systolic blood pressure.

    PubMed

    Phillips, Aaron A; Bredin, Shannon S D; Cote, Anita T; Drury, C Taylor; Warburton, Darren E R

    2013-03-01

    As sympathetic activity approximately doubles during intense lower body negative pressure (LBNP) of -60 mmHg or greater, we examined the relationship between surrogate markers of sympathetic activation and central arterial distensibility during severe LBNP. Eight participants were exposed to progressive 8-min stages of LBNP of increasing intensity (-20, -40, -60, and -80 mmHg), while recording carotid-femoral pulse wave velocity (cPWV), stroke volume (SV), heart rate, and beat-by-beat blood pressure. The spectral power of low frequency oscillations in SBP (SBP(LF)) was used as a surrogate indicator of sympathetically modulated vasomotor modulation. Total arterial compliance (C) was calculated as C = SV/pulse pressure. Both cPWV and C were compared between baseline, 50 % of the maximally tolerated LBNP stage (LBNP(50)), and the maximum fully tolerated stage of LBNP (LBNP(max)). No change in mean arterial pressure (MAP) occurred over LBNP. An increase in cPWV (6.5 ± 2.2; 7.2 ± 1.4; 9.0 ± 2.5 m/s; P = 0.004) occurred during LBNP(max). Over progressive LBNP, SBP(LF) increased (8.5 ± 4.6; 9.3 ± 5.8; 16.1 ± 12.9 mmHg(2); P = 0.04) and C decreased significantly (18.3 ± 6.8; 14.3 ± 4.1; 11.6 ± 4.8 ml/mmHg × 10; P = 0.03). The mean correlation (r) between cPWV and SBP(LF) was 0.9 ± 0.03 (95 % CI 0.79-0.99). Severe LBNP increased central stiffness and reduced total arterial compliance. It appears that increased sympathetic vasomotor tone during LBNP is associated with reduced aortic distensibility in the absence of changes in MAP. PMID:22971725

  3. Evaporative Cooling Membrane Device

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis (Inventor); Moskito, John (Inventor)

    1999-01-01

    An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

  4. External Counterpulsation Reduces Beat-to-Beat Blood Pressure Variability When Augmenting Blood Pressure and Cerebral Blood Flow in Ischemic Stroke

    PubMed Central

    Tian, Ge; Xiong, Li; Lin, Wenhua; Han, Jinghao; Chen, Xiangyan; Leung, Thomas Wai Hong; Soo, Yannie Oi Yan

    2016-01-01

    Background and Purpose External counterpulsation (ECP) is a noninvasive method used to enhance cerebral perfusion by elevating the blood pressure in ischemic stroke. However, the response of the beat-to-beat blood pressure variability (BPV) in ischemic stroke patients during ECP remains unknown. Methods We enrolled recent ischemic stroke patients and healthy controls. Changes in the blood flow velocities in bilateral middle cerebral arteries and the continuous beat-to-beat blood pressure before, during, and after ECP were monitored. Power spectral analysis revealed that the BPV included oscillations at very low frequency (VLF; <0.04 Hz), low frequency (LF; 0.04–0.15 Hz), and high frequency (HF; 0.15–0.40 Hz), and the total power spectral density (TP; <0.40 Hz) and LF/HF ratio were calculated. Results We found that ECP significantly increased the systolic and diastolic blood pressures in both stroke patients and controls. ECP decreased markedly the systolic and diastolic BPVs at VLF and LF and the TP, and the diastolic BPV at HF when compared with baseline. The decreases in diastolic and systolic BPV reached 37.56% and 23.20%, respectively, at VLF, 21.15% and 12.19% at LF, 8.76% and 16.59% at HF, and 31.92% and 23.62% for the total TP in stroke patients, which did not differ from those in healthy controls. The change in flow velocity on the contralateral side was positively correlated with the total TP systolic BPV change induced by ECP (r=0.312, p=0.035). Conclusions ECP reduces the beat-to-beat BPV when increasing the blood pressure and cerebral blood flow velocity in ischemic stroke patients. ECP might be able to improve the clinical outcome by decreasing the beat-to-beat BPV in stroke patients, and this should be explored further in future studies. PMID:27095525

  5. Vapor compression evaporator concentrates, recovers alcohol

    SciTech Connect

    Miller, M.N.; Robe, K.; Bacchetti, J.A.

    1982-11-01

    This article focuses on presenting a solution to the high energy cost of operating a steam heated, single effect evaporator used by Monsanto Industrial Chemical Company at a plant in Seattle, Wash., to produce vanillin from pulp and paper mill sulfite. Use of the single effect flash evaporator resulted in high energy usage due not only to the ''single effect'' use of steam, but also because energy consumption was reduced only slightly at low operating rates. The solution to this problem was the replacement of the single effect evaporator with a vapor recompression evaporator. Operating for over 1 1/2 years, the vapor recompression evaporator system has had no significant maintenance problems. The system operates with only 1/60th the steam consumption and 15% of the total energy consumption of the previous evaporator and has had no tube fouling. Also, since the distillate is condensed within the evaporator, less cooling water is required, allowing two heat exchangers to be taken out of service. When operating at less than design capacity, the energy consumption drops almost linearly with the feed rate. At low feed rates, a by-pass valve unloads the compressor to reduce energy consumption. Total energy consumption, now 15% of the previous level, results in an estimated pay-back of less than three years.

  6. Changes in protein structures to improve the rheology and texture of reduced-fat sausages using high pressure processing.

    PubMed

    Yang, Huijuan; Khan, Muhammad Ammar; Yu, Xiaobo; Zheng, Haibo; Han, Minyi; Xu, Xinglian; Zhou, Guanghong

    2016-11-01

    This study investigated the role of high-pressure processing (HPP) for improving the functional properties of meat batters and the textural properties of reduced-fat sausages. Application of 200MPa pressure at 10°C for 2min to pork batters containing various fat contents (0-30%) affected their rheological properties, cooking losses, color, textual properties and their protein imaging. The results revealed that both application of 200MPa and increasing fat content decreased cooking loss, as well as improved the textural and rheological properties. Cooking losses, texture and sensory evaluation of 200MPa treated sausages having 20% fat were similar to those of the 0.1MPa treated sausages having 30% fat. Principal component analysis revealed that certain quality attributes were affected differently by the levels of fat addition and by HPP. These findings indicated the potential of HPP for improving yield and texture of emulsion-type sausages having reduced fat contents. PMID:27288900

  7. Thermal and Evolved Gas Analyses at Reduced Pressures: A Mineral Database for the Thermal Evolved Gas Analyzer (TEGA)

    NASA Technical Reports Server (NTRS)

    Lauer, H. V., Jr.; Ming, Douglas W.; Golden, D. C.; Lin, I.-C.; Morris, R. V.; Boynton, W. V.

    2000-01-01

    Volatile-bearing minerals (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates) may be important phases on the surface of Mars. The Thermal Evolved Gas Analyzer (TEGA), which was part of the Mars Polar Lander payload, was to detect and identify volatile-bearing phases in the Martian regolith. The TEGA instrument is composed of a differential scanning calorimetry (DSC) interfaced with an evolved gas analyzer (EGA). The EGA consists of a Herriott cell of a tunable-diode laser (TDL) spectrometer that determines CO, and H2O abundances. The sample chamber in TEGA operates at about 100 mbar (-76 torr) with a N2 carrier gas flow of 0.4 sccm. Essentially no information exists on the effects of reduced pressure on the thermal properties of volatile-bearing minerals. Here we present a database for the thermal behavior of volatile-bearing phases under reduced pressure conditions.

  8. Manufacturing and finite element assessment of a novel pressure reducing insole for Diabetic Neuropathic patients.

    PubMed

    Ghassemi, A; Mossayebi, A R; Jamshidi, N; Naemi, R; Karimi, M T

    2015-03-01

    Diabetes is one of the metabolic diseases. Uncontrolled diabetes can lead to diabetic foot ulcers and if it was not treated would lead to amputation. Foot ulcers can be prevented by using suitable insoles which are made of appropriate material and geometrically designed by constituent layers. In this study, single-layer and three-layer insoles have been compared during static and dynamic loading. The selected materials were silicone gel (SG), plastazote foam (PLZ), polyfoam (PF) and ethyl vinyl acetate foam (EVA). Four single-layer and 18 combinations of three-layer insoles were selected. Materials behaviors were determined by using a uniaxial pressure test. The description of stress and strain is obtained by using the model of three dimensional nonlinear Finite Element Method (FEM). Then samples were tested by using commercially available plantar pressure measurement system. The FEM results showed that the SG and PLZ insoles are more appropriate compared to single-layer insoles. The combinations of PLZ, SG and EVA (from top to bottom) are recognized as the best between three-layer insoles. Also the best three-layer insole is more effective in promoting a favourable stress and strain distribution than single-layer insoles, especially in dynamic mode. According to simulation results, three-layer insole decreases stress concentration by 9%. Also experimental tests showed that using three-layer insole decreases plantar pressure by 63% compared to barefoot condition bare foot. PMID:25536901

  9. A national project to evaluate and reduce high sound pressure levels from music.

    PubMed

    Ryberg, Johanna Bengtsson

    2009-01-01

    The highest recommended sound pressure levels for leisure sounds (music) in Sweden are 100 dB LAeq and 115 dB LAFmax for adults, and 97 dB LAeq and 110 dB LAFmax where children under the age of 13 have access. For arrangements intended for children, levels should be consistently less than 90 dB LAeq. In 2005, a national project was carried out with the aim of improving environments with high sound pressure levels from music, such as concert halls, restaurants, and cinemas. The project covered both live and recorded music. Of Sweden's 290 municipalities, 134 took part in the project, and 93 of these carried out sound measurements. Four hundred and seventy one establishments were investigated, 24% of which exceeded the highest recommended sound pressure levels for leisure sounds in Sweden. Of festival and concert events, 42% exceeded the recommended levels. Those who visit music events/establishments thus run a relatively high risk of exposure to harmful sound levels. Continued supervision in this field is therefore crucial. PMID:19414933

  10. Systolic blood pressure goals to reduce cardiovascular disease among older adults.

    PubMed

    Muntner, Paul; Bowling, C Barrett; Shimbo, Daichi

    2014-08-01

    The 2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults Report From the Panel Members Appointed to the Eighth Joint National Committee (JNC 8) was recently published. This guideline recommended that older adults (≥60 years) without diabetes or chronic kidney disease with systolic blood pressure (SBP) ≥150 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg be initiated on antihypertensive medication with a treatment goal SBP/DBP <150/90 mm Hg. In contrast, the previous 3 JNC guidelines recommended treatment for these individuals be initiated at SBP/DBP ≥140/90 mm Hg with goal SBP/DBP <140/90 mm Hg. In this article, we review randomized trials of antihypertensive medication and observational data on SBP and DBP with cardiovascular outcomes among older adults, possible explanations underlying the different findings from these randomized trials and observational studies, and contemporary antihypertensive treatment patterns among older U.S. adults. In closing, we highlight future research needs related to hypertension and outcomes among older adults. PMID:24978394

  11. Reduced gas pressure operation of sludge digesters: Expanded studies. Final report

    SciTech Connect

    Not Available

    1993-09-01

    Previous investigations strongly suggested that the municipal anaerobic sludge digestion process could be enhanced by reactor operation with subatmospheric headspace pressures. Enhanced solids destruction and methane production along with increased process stability were observed in these earlier studies. However, due to the small scale of the anaerobic reactors used ( {approx}1.5 L), definitive steady-state measurements could not be obtained. These expanded studies were undertaken to verify and define the magnitude of the benefits that might be obtained with vacuum operation of sludge digesters. Four reactors ({approx}15.0 L) were fed municipal sludge at three different organic loading rates while being maintained with a 15-day solids retention time. One reactor had a constant headspace pressure of 1.02 atm; a second was maintained at 0.75 atm; and the remaining two reactors were operated for the majority of the day at 1.02 atm, and for part of the day with a 0.75 atm headspace pressure. Additional small-scale, batch experiments were performed to help identify controlling digestion mechanisms. The results of these expanded studies indicate that vacuum operation did not yield significant advantages over the organic loading range investigated (0.088 to 0.352 lb VSS/ft{sup 3}{center_dot}d).

  12. Boiling and Evaporation on Micro/nanoengineered Surfaces

    NASA Astrophysics Data System (ADS)

    Dai, Xianming

    .e., type 3 surfaces, were developed to separate liquid flows and capillary pressure generation. This new type of surfaces consists of a microchannel array and a micromembrane made from a single layer of micromesh. The capillary evaporation CHF were substantially increased because of the increased capillary pressure provided by micromeshes and the reduced friction drag resulted from microchannels. Based on this newly developed hybrid wick, the effect of interfacial wettability on capillary evaporation was systematically studied. Firstly, superhydrophilic ALD SiO2 was deposited on this type of hybrid wick to create intrinsically superhydrophilic interfaces, i.e., type 4 surfaces, resulting in significantly increased HTC because of the enhanced thin film evaporation on micromeshes. Secondly, CNT-enabled hydrophobic-hydrophilic composite interfaces were deposited on the hybrid wicks to increase the nucleate site density, bubble departure frequency and reduce friction drag. Both nucleate boiling and thin film evaporation were improved, resulting in enhanced HTC and CHF. In conclusion, the interfacial wettability of micro/nanoengineered surfaces can significantly alter bubble dynamics such as nucleation site density, bubble departure diameter and frequency. Superhydrophilic surface can substantially increase the boiling CHF because of the superwetting property. In addition, more hydrophobic surfaces yield higher HTC, while more hydrophilic surfaces result in higher CHF. The partially hydrophobic and partially hydrophilic surfaces perform better than both superhydrphobic and superhydrophilic surfaces. The separation of liquid flow and capillary pressure generation can be achieved using micromembranes, resulting in dramatically increased CHF. Improved wettability can result in better wettings and enhanced thin film evaporation. Hydrophobic and hydrophilic nanoporous coatings can improve the wetting and reduce the friction, resulting in enhanced HTC and CHF simultaneously.

  13. Nitrous oxide withdrawal reduces intracranial pressure in the presence of pneumocephalus.

    PubMed

    Skahen, S; Shapiro, H M; Drummond, J C; Todd, M M; Zelman, V

    1986-08-01

    Nitrous oxide anesthesia has been implicated as contributing to the development of delayed tension pneumocephalus following surgery performed in the sitting position. The authors tested the hypothesis that withdrawal of nitrous oxide anesthesia administered during formation of an intracranial gas cavity would lead to a decrease in intracranial pressure (ICP) as N2O diffuses from the cavity back into the blood. Ten halothane-anesthetized rabbits were prepared for measurement of supracortical ICP and arterial blood pressure (BP) and for intracranial volume alterations via a cisterna magna infusion catheter. Hyperventilation (Paco2 = 28-30 mmHg) and mannitol were used to shrink the brain to accommodate intracranial infusion of either air or lactated Ringer's (LR) solution, which was used to elevate ICP to between 10-15 mmHg from a baseline ICP of 2.1 +/- 2.5 mmHg over a period of 8 to 10 min. Following stabilization at an elevated ICP, inhalation of nitrous oxide (75%) was either initiated or withdrawn (if already present during the induced ICP increase) and the subsequent changes in mean ICP and BP were recorded. Following ICP elevation with LR to 10 +/- 1 mmHg, initiation of 75% N2O administration resulted in no change in ICP and modest increases (P less than 0.05) in BP and cerebral perfusion pressure (CPP = BP - ICP) after 4 min. However, when ICP was raised (to 12 +/- 3.5 mmHg) with intracranial air infusion, subsequent initiation of 75% N2O inhalation caused an abrupt ICP increase to 22.3 +/- 9 mmHg (from control P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3740508

  14. Evaporation study at Warm Springs Reservoir, Oregon

    USGS Publications Warehouse

    Harris, D.D.

    1968-01-01

    The mass transfer-water budget method of computing reservoir evaporation was tested on Warm Springs Reservoir, whose contents and surface area change greatly from early spring to late summer. The mass-transfer coefficient computed for the reservoir is two to three times greater than expected and results in a computed evaporation much greater than that from a land pan. Because of the remoteness of the area, the recommended study technique was modified, which could have reduced the accuracy of the results.

  15. Oxidation of SiC/BN/SiC Composites in Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Boyd, Meredith

    2010-01-01

    SiC fiber-reinforced SiC composites with a BN interphase are proposed for use as leading edge structures of hypersonic vehicles. The durability of these materials under hypersonic flight conditions is therefore of interest. Thermogravimetric analysis was used to characterize the oxidation kinetics of both the constituent fibers and composite coupons at four temperatures: 816, 1149, 1343, and 1538 C (1500, 2100, 2450, and 2800 F) and in oxygen partial pressures between 5% and 0.1% (balance argon) at 1 atm total pressure. One edge of the coupons was ground off so the effects of oxygen ingress into the composite could be monitored by post-test SEM and EDS. Additional characterization of the oxidation products was conducted by XPS and TOF-SIMS. Under most conditions, the BN oxidized rapidly, leading to the formation of borosilicate glass. Rapid initial oxidation followed by volatilization of boria lead to protective oxide formation and further oxidation was slow. At 1538C in 5% oxygen, both the fibers and coupons exhibited borosilicate glass formation and bubbling. At 1538C in 0.1% oxygen, active oxidation of both the fibers and the composites was observed leading to rapid SiC degradation. BN oxidation at 1538C in 0.1% oxygen was not significant.

  16. Flash evaporator systems test

    NASA Technical Reports Server (NTRS)

    Dietz, J. B.

    1976-01-01

    A flash evaporator heat rejection system representative of that proposed for the space shuttle orbiter underwent extensive system testing at the NASA Johnson Space Center (JSC) to determine its operational suitability and to establish system performance/operational characteristics for use in the shuttle system. During the tests the evaporator system demonstrated its suitability to meet the shuttle requirements by: (1) efficient operation with 90 to 95% water evaporation efficiency, (2) control of outlet temperature to 40 + or - 2 F for partial heat load operation, (3) stability of control system for rapid changes in Freon inlet temperature, and (4) repeated dormant-to-active device operation without any startup procedures.

  17. A pharmacologic activator of endothelial KCa channels increases systemic conductance and reduces arterial pressure in an anesthetized pig model.

    PubMed

    Mishra, Ramesh C; Mitchell, Jamie R; Gibbons-Kroeker, Carol; Wulff, Heike; Belenkie, Israel; Tyberg, John V; Braun, Andrew P

    2016-04-01

    SKA-31, an activator of endothelial KCa2.3 and KCa3.1 channels, reduces systemic blood pressure in mice and dogs, however, its effects in larger mammals are not well known. We therefore examined the hemodynamic effects of SKA-31, along with sodium nitroprusside (SNP), in anesthetized, juvenile male domestic pigs. Experimentally, continuous measurements of left ventricular (LV), aortic and inferior vena cava (IVC) pressures, along with flows in the ascending aorta, carotid artery, left anterior descending coronary artery and renal artery, were performed during acute administration of SKA-31 (0.1, 0.3, 1.0, 3.0 and 5.0mg/ml/kg) and a single dose of SNP (5.0μg/ml/kg). SKA-31 dose-dependently reduced mean aortic pressure (mPAO), with the highest dose decreasing mPAO to a similar extent as SNP (-23±3 and -28±4mmHg, respectively). IVC pressure did not change. Systemic conductance and conductance in coronary and carotid arteries increased in response to SKA-31 and SNP, but renal artery conductance was unaffected. There was no change in either LV stroke volume (SV) or heart rate (versus the preceding control) for any infusion. With no change in SV, drug-evoked decreases in LV stroke work (SW) were attributed to reductions in mPAO (SW vs. mPAO, r(2)=0.82, P<0.001). In summary, SKA-31 dose-dependently reduced mPAO by increasing systemic and arterial conductances. Primary reductions in mPAO by SKA-31 largely account for associated decreases in SW, implying that SKA-31 does not directly impair cardiac contractility. PMID:26239885

  18. The application of high-pressure treatment in the reduction of salt levels in reduced-phosphate breakfast sausages.

    PubMed

    O'Flynn, Claire C; Cruz-Romero, Malco C; Troy, Declan; Mullen, Anne M; Kerry, Joe P

    2014-03-01

    This study investigated the effects of high pressure (HP) treatment of pork meat before manufacturing sausages with reduced salt levels and compared them to sausages manufactured with untreated meat (control sausages). A 2×5 factorial design was set up incorporating two pressure levels (0 or 150 MPa) and five salt levels (0.5, 1.0, 1.5, 2.0 and 2.5%). Most quality attributes were affected when salt levels were reduced below 1.5%. Fat loss (FL) was (P<0.05) affected by salt level; samples with <1.5% salt had the highest FL. HP treatment increased emulsion stability and reduced cook loss (CL) compared to control sausages. Increased CL was observed when salt was reduced below 2.0%. Salt reduction below 1.5% adversely affected colour, sensory and texture attributes. Independent of salt, HP treatment affected adversely juiciness and cohesiveness while adhesiveness was improved. Overall, there is potential to manufacture sausages maintaining organoleptic and functional properties traditionally associated with sausages using HP treated meat. PMID:24334049

  19. Antihyperglycemic and blood pressure-reducing effects of stevioside in the diabetic Goto-Kakizaki rat.

    PubMed

    Jeppesen, P B; Gregersen, S; Rolfsen, S E D; Jepsen, M; Colombo, M; Agger, A; Xiao, J; Kruhøffer, M; Orntoft, T; Hermansen, K

    2003-03-01

    Stevioside, a glycoside present in the leaves of the plant, Stevia rebaudiana Bertoni (SrB), has acute insulinotropic effects in vitro. Its potential antihyperglycemic and blood pressure-lowering effects were examined in a long-term study in the type 2 diabetic Goto-Kakizaki (GK) rat. Rats were fed 0.025 g x kg(-1) x d(-1) of stevioside (purity > 99.6%) for 6 weeks. An intra-arterial catheter was inserted into the rats after 5 weeks, and conscious rats were subjected to arterial glucose tolerance test (2.0 g x kg(-1)) during week 6. Stevioside had an antihyperglycemic effect (incremental area under the glucose response curve [IAUC]): 985 +/- 20 (stevioside) versus 1,575 +/- 21 (control) mmol/L x 180 minutes, (P <.05), it enhanced the first-phase insulin response (IAUC: 343 +/- 33 [stevioside] v 136 +/- 24 [control] microU/mL insulin x 30 minutes, P <.05) and concomitantly suppressed the glucagon levels (total AUC: 2,026 +/- 234 [stevioside] v 3,535 +/- 282 [control] pg/mL x 180 minutes, P <.05). In addition, stevioside caused a pronounced suppression of both the systolic (135 +/- 2 v 153 +/- 5 mm Hg; P <.001) and the diastolic blood pressure (74 +/- 1 v 83 +/- 1 mm Hg; P <.001). Bolus injections of stevioside (0.025 g x kg(-1)) did not induce hypoglycemia. Stevioside augmented the insulin content in the beta-cell line, INS-1. Stevioside may increase the insulin secretion, in part, by induction of genes involved in glycolysis. It may also improve the nutrient-sensing mechanisms, increase cytosolic long-chain fatty acyl-coenzyme A (CoA), and downregulate phosphodiesterase 1 (PDE1) estimated by the microarray gene chip technology. In conclusion, stevioside enjoys a dual positive effect by acting as an antihyperglycemic and a blood pressure-lowering substance; effects that may have therapeutic potential in the treatment of type 2 diabetes and the metabolic syndrome. PMID:12647278

  20. Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control

    NASA Technical Reports Server (NTRS)

    Ingle, W. M.; Thompson, S. W.; Chaney, R. E. (Inventor)

    1979-01-01

    A method in which a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, as well as certain transition metals including nickel, iron, and manganese is described. The tube is then evacuated and heated to a temperature within a range of 800 C to 1400 C. A stream of gas comprising a reactant, such as silicon tetrafluoride, is continuously delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. The reactant which included carbon monoxide gas and impurities such as iron and nickel react to form volatile carbonyls.

  1. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, N.; Lukenbach, M.; Hokanson, K. J.; Devito, K. J.; Petrone, R. M.; Hopkinson, C.; Waddington, J. M.

    2015-12-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This large scale reduction in evaporation promotes high water table positions at a landscape scale which limits the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  2. A model for calculation of RCS pressure during reflux boiling under reduced inventory conditions and its assessment against PKL data

    SciTech Connect

    Palmrose, D.E.; Mandl, R.M.

    1991-12-31

    There has been recent interest in the United States concerning the loss of residual heat removal system (RHRS) under reduced coolant inventory conditions for pressurized water reactors. This issue is also of interest in the Federal Republic of Germany and an experiment was performed in the integral PKL-HI experimental facility at Siemens-KWU to supply applicable data. Recently, an NRC-sponsored effort has been undertaken at the Idaho-National Engineering Laboratory to identify and analyze the important thermal-hydraulic phenomena in pressurized water reactors following the long term loss-of-RHRS during reduced inventory operation. The thermal-hydraulic response of a closed reactor coolant system during such a transient is investigated in this report. Some of the specific processes investigated include: reflux condensation in the steam generators, the corresponding pressure increase in the reactor coolant system, and void fraction distributions on the primary side of the system. Mathematical models of these and other physical processes Experiment B4.5.

  3. CAPSULE REPORT: EVAPORATION PROCESS

    EPA Science Inventory

    Evaporation has been an established technology in the metal finishing industry for many years. In this process, wastewaters containing reusable materials, such as copper, nickel, or chromium compounds are heated, producing a water vapor that is continuously removed and condensed....

  4. Performance of insole in reducing plantar pressure on diabetic patients in the early stages of the disease.

    PubMed

    Zequera, Martha L; Solomonidis, Stephan

    2010-01-01

    It has been well documented that subjects with peripheral neuropathy resulting from diabetes mellitus are at high risk of developing foot ulceration. Decreased sensation, in combination with high underfoot pressures, have been identified as prime etiology factors in the cause of plantar naturopathic ulceration [1]. This study presents the effect of four orthotic treatment techniques in reducing metatarsal head, heel and toes pressure during walking. A pressure measurement study was carried out on a diabetic patients group wearing four insoles, including the insole designed by the computer model proposed in this project. The aim of this study was to evaluate the effect on plantar pressure in diverse insoles prescribed and manufactured with various techniques on a random group of patients with diabetes mellitus in the early stages of the disease. Four types of insoles were designed and manufactured by methods available in the market; the computer model proposed on this project was used in order to design and manufacture the insole. The results show that every patient requires an individual assessment and often a personalized insole. PMID:21095715

  5. Reduced cerebral and cardiovascular hemodynamics during sustained affective stimulation in young women with chronic low blood pressure.

    PubMed

    Cellini, Nicola; de Zambotti, Massimiliano; Covassin, Naima; Gallicchio, Germano; Stegagno, Luciano; Sarlo, Michela

    2015-05-01

    Although low blood pressure has been associated with lower affect and higher depressive symptoms in the elderly, the presence of possible impairment in emotional reactivity in chronic hypotensive individuals in early adulthood remains largely unexplored. Using a combination of transcranial Doppler sonography, beat-to-beat blood pressure recording and impedance cardiography we assessed central and peripheral hemodynamic changes in 15 undergraduate women with chronic hypotension (Age: 23.9 ± 2.7 years) and 15 normotensive controls (Age: 23.7 ± 3.1 years) during sustained exposure to pleasant, unpleasant and neutral pictures. Overall, systolic blood pressure (SBP) increased in normotensives and decreased in hypotensives during picture viewing as compared to baseline. Also, compared to normotensives, in hypotensives mean cerebral blood flow velocity increased to a lesser extent during the viewing of pleasant pictures and the magnitude of this increase was negatively associated with subjective emotional arousal. In addition, in hypotensives screening SBP was positively associated with valence rating of pleasant contents. These findings indicate a close association between chronic low blood pressure and reduced processing of pleasant stimuli in young adulthood. PMID:25727023

  6. Measure Guideline: Evaporative Condensers

    SciTech Connect

    German, A.; Dakin, B.; Hoeschele, M.

    2012-03-01

    The purpose of this measure guideline on evaporative condensers is to provide information on a cost-effective solution for energy and demand savings in homes with cooling loads. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices. This document has been prepared to provide a process for properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs.

  7. Isotopic Compositions of Evaporative Fluxes

    NASA Astrophysics Data System (ADS)

    Feng, X.; Lauder, A. M.; Kopec, B. G.; Dade, W. B.; Virginia, R. A.; Posmentier, E. S.

    2013-12-01

    The isotopic fluxes of evaporation from a water surface are typically computed using a one-dimensional model, originally conceptualized by Craig and Gordon (1965) and further developed and adapted to different natural settings (such as transpiration, open surface evaporation, etc.) by various investigators. These models have two distinguishing characteristics. First, there exists a laminar layer where molecular diffusion away from the water-air interface causes kinetic isotopic fractionation. The magnitude of this fractionation is controlled by the diffusion/transport coefficient of each vapor isotopologue in air and their concentration gradients, the latter being controlled by relative humidity, isotopic ratios of ambient air, and turbulent conditions (such as wind and surface roughness). Second, the horizontal variations are ignored. In particular, the effect of horizontal advection on isotopic variations in the ambient air is not considered. The research reported here addresses the effects of relinquishing the simplifying assumptions in both of these areas. We developed a model, in which the simplification of a purely laminar layer is dropped. Instead, we express the vertical transport coefficient as the sum of the molecular diffusivity, that differs for each water isotopologue, and the turbulent diffusivity that increases linearly with height but does not vary among water isotopologues. With this model, the kinetic isotopic effect reduces with height in the vicinity of the water surface, and the net isotopic fractionation through the boundary layer can be integrated. The advantage of this conceptualization is that the magnitude of kinetic isotopic fractionation can be assessed directly with changing environmental conditions, such as humidity and wind speed, rather than approximated by discontinuous empirical functions of the environmental conditions, as in the conventional models mentioned above. To address the effect of lateral heterogeneity, we expanded the

  8. Evaporation-induced cavitation in nanofluidic channels

    PubMed Central

    Duan, Chuanhua; Karnik, Rohit; Lu, Ming-Chang; Majumdar, Arun

    2012-01-01

    Cavitation, known as the formation of vapor bubbles when liquids are under tension, is of great interest both in condensed matter science as well as in diverse applications such as botany, hydraulic engineering, and medicine. Although widely studied in bulk and microscale-confined liquids, cavitation in the nanoscale is generally believed to be energetically unfavorable and has never been experimentally demonstrated. Here we report evaporation-induced cavitation in water-filled hydrophilic nanochannels under enormous negative pressures up to -7 MPa. As opposed to receding menisci observed in microchannel evaporation, the menisci in nanochannels are pinned at the entrance while vapor bubbles form and expand inside. Evaporation in the channels is found to be aided by advective liquid transport, which leads to an evaporation rate that is an order of magnitude higher than that governed by Fickian vapor diffusion in macro- and microscale evaporation. The vapor bubbles also exhibit unusual motion as well as translational stability and symmetry, which occur because of a balance between two competing mass fluxes driven by thermocapillarity and evaporation. Our studies expand our understanding of cavitation and provide new insights for phase-change phenomena at the nanoscale. PMID:22343530

  9. Flow Visualization within the Evaporator of Planar Loop Heat Pipe

    NASA Astrophysics Data System (ADS)

    Suh, Junwoo; Cytrynowicz, Debra; Medis, Praveen; Gerner, Frank M.; Henderson, H. Thurman

    2005-02-01

    A planar micro loop heat pipe (LHP) with coherent porous silicon (CPS) wick in the evaporator is a two-phase heat transfer device that utilizes evaporation and condensation to transfer heat. This CPS wick has thousands of pores, which are 2 micrometer in diameter, contained over an area of one square centimeter. As heat is applied to the evaporator, liquid is vaporized and evaporator chamber's pressure is increased. A meniscus formed at the liquid/vapor interface inside the pore of the CPS wick is supported by capillary forces even though pressure force pushes it down. Vapor flows through the vapor line to the condenser and condenses. Liquid is transported back to the evaporator due to pressure difference. The internal thermodynamics and fluid dynamics are poorly understood due to the difficulty of taking internal measurements and the complexity of two-phase phenomena. To understand this thermal device, the clear evaporator machined from Pyrex glass was utilized to monitor the complex phenomena which occur in the evaporator. These phenomena include vapor formation, nucleate boiling, evaporation, depriming, and pressure oscillation. DI-water was utilized as the working fluid.

  10. Measured performance of falling-jet flash evaporators

    NASA Astrophysics Data System (ADS)

    Green, H. J.; Olson, D. A.; Bharathan, D.; Johnson, D. H.

    1981-06-01

    The rates of heat transfer and approach to thermal equilibrium of flash evaporators operating at pressures of 2 to 4 kPa were investigated. Heat and mass transfer rates from falling jet evaporators operating in the temperature range of 18 to 30 C are measured. The initial experimental results are given and the apparatus is described.

  11. Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water

    NASA Astrophysics Data System (ADS)

    Sterniczuk, Marcin; Yakabuskie, Pamela A.; Wren, J. Clara; Jacob, Jasmine A.; Bartels, David M.

    2016-04-01

    Low Linear Energy Transfer (LET) radiolysis escape yields (G values) are reported for the sum (G(radH)+G(e-)aq) and for G(H2) in subcritical water up to 350 °C. The scavenger system 1-10 mM acetate/0.001 M hydroxide/0.00048 M N2O was used with simultaneous mass spectroscopic detection of H2 and N2 product. Temperature-dependent measurements were carried out with 2.5 MeV electrons from a van de Graaff accelerator, while room temperature calibration measurements were done with a 60Co gamma source. The concentrations and dose range were carefully chosen so that initial spur chemistry is not perturbed and the N2 product yield corresponds to those reducing radicals that escape recombination in pure water. In comparison with a recent review recommendation of Elliot and Bartels (AECL report 153-127160-450-001, 2009), the measured reducing radical yield is seven percent smaller at room temperature but in fairly good agreement above 150 °C. The H2 escape yield is in good agreement throughout the temperature range with several previous studies that used much larger radical scavenging rates. Previous analysis of earlier high temperature measurements of Gesc(radOH) is shown to be flawed, although the actual G values may be nearly correct. The methodology used in the present report greatly reduces the range of possible error and puts the high temperature escape yields for low-LET radiation on a much firmer quantitative foundation than was previously available.

  12. Reduced sarcoplasmic reticulum Ca(2+) load mediates impaired contractile reserve in right ventricular pressure overload.

    PubMed

    Quaile, Michael P; Rossman, Eric I; Berretta, Remus M; Bratinov, George; Kubo, Hajime; Houser, Steven R; Margulies, Kenneth B

    2007-11-01

    Myocardial contractile reserve is significantly attenuated in patients with advanced heart failure. The aim of this study was to identify mechanisms of impaired contractile reserve in a large animal model that closely mimics human myocardial failure. Progressive right ventricular hypertrophy and failure were induced by banding the pulmonary artery in kittens. Isometric contractile force was measured in right ventricular trabeculae (n=115) from age-matched Control and Banded feline hearts. Rapid cooling contractures (RCC) were used to determine sarcoplasmic reticulum (SR) Ca(2+) load while assessing the ability of changes in rate, adrenergic stimulation and bath Ca(2+) to augment contractility. The positive force-frequency relationship and robust pre- and post-receptor adrenergic responses observed in Control trabeculae were closely paralleled by increases in RCC amplitude and the RCC2/RCC1 ratio. Conversely, the severely blunted force-frequency and adrenergic responses in Banded trabeculae were paralleled by an unchanged RCC amplitude and RCC2/RCC1 ratio. Likewise, supraphysiologic levels of bath Ca(2+) were associated with severely reduced contractility and RCC amplitude in Banded trabeculae compared to Controls. There were no differences in myofilament Ca(2+) sensitivity or length-dependent increases in contractility between Control and Banded trabeculae. There was a significant decrease in SR Ca(2+)-ATPase pump abundance and phosphorylation of phospholamban and ryanodine receptor in Banded trabeculae compared with Controls. A reduced ability to increase SR Ca(2+) load is the primary mechanism of reduced contractile reserve in failing feline myocardium. The similarity of impaired contractile reserve phenomenology in this feline model and transplanted hearts suggests mechanistic relevance to human myocardial failure. PMID:17931654

  13. Controlled aerobic exercise training reduces resting blood pressure in sedentary older adults.

    PubMed

    Huang, Guoyuan; Shi, Xiangrong; Gibson, Cheryl A; Huang, Sunny C; Coudret, Nadine A; Ehlman, Mary C

    2013-12-01

    The results of existing controlled clinical trials were synthesized to determine effects of aerobic exercise training on resting systolic (SBP) and diastolic blood pressure (DBP) among previously sedentary older adults, to quantify the magnitude of observed changes, and to examine the influence of the associated interventional variables on these changes. Studies were identified via a systematic computer database search, hand searching, and cross-referencing of previously located articles. All potentially eligible articles were carefully reviewed and examined with the established inclusion criteria. Twenty-three studies, representing a total of 1226 older subjects, were included in the final analysis. Robust statistically significant effects were found in terms of the pooled standardized effect size of - 0.33 ± 0.06 (p < 0.0001) in SBP and - 0.39 ± 0.09 (p < 0.0001) in DBP. When compared with the control group, net decreases in both SBP (- 5.39 ± 1.21 mmHg, p < 0.0001) and DBP (-3.68 ± 0.83 mmHg, p < 0.0001) were observed in older exercisers, representing a 3.9% and a 4.5% reduction, respectively. This meta-analytic study provides robust quantitative data to support the efficacy and effectiveness of controlled endurance exercise training in decreasing resting SBP and DBP among previously sedentary older adults. PMID:23550511

  14. DPP-4 Inhibitor Reduces Central Blood Pressure in a Diabetic and Hypertensive Patient: A Case Report.

    PubMed

    Cosenso-Martin, Luciana Neves; Giollo-Junior, Luiz Tadeu; Vilela-Martin, José Fernando

    2015-07-01

    Hypertension and type 2 diabetes mellitus (DM) are among the main risk factors for the development of cardiovascular disease. Pharmacotherapy for DM should not only improve blood glucose control, but also provide beneficial glucose-independent cardiovascular effects. The central systolic blood pressure (SBP) has become more important than the brachial SBP in the assessment of cardiovascular risk.This case report describes the effect of vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, on the central SBP in a 54-year-old woman with hypertension and DM. She was submitted to applanation tonometry (AT) before and after vildagliptin association. AT of the radial artery is a non-invasive method that indirectly assesses arterial stiffness by calculating the central SBP and the augmentation index (AIx).After 3 months of follow-up using vildagliptin, central SBP and AIx were improved. Moreover, she presented better glycemic control.This case suggests an effect of DPP-4 inhibitor on arterial stiffness parameter (central SBP) in a hypertensive and diabetic patient, which shows a glucose-independent beneficial cardiovascular effect of this group of drugs. PMID:26166078

  15. 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.

  16. 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.

  17. Application of Cornelian Cherry Iridoid-Polyphenolic Fraction and Loganic Acid to Reduce Intraocular Pressure

    PubMed Central

    Szumny, Dorota; Sozański, Tomasz; Kucharska, Alicja Z.; Dziewiszek, Wojciech; Piórecki, Narcyz; Magdalan, Jan; Chlebda-Sieragowska, Ewa; Kupczynski, Robert; Szeląg, Adam; Szumny, Antoni

    2015-01-01

    One of the most common diseases of old age in modern societies is glaucoma. It is strongly connected with increased intraocular pressure (IOP) and could permanently damage vision in the affected eye. As there are only a limited number of chemical compounds that can decrease IOP as well as blood flow in eye vessels, the up-to-date investigation of new molecules is important. The chemical composition of the dried Cornelian cherry (Cornus mas L.) polar, iridoid-polyphenol-rich fraction was investigated. Loganic acid (50%) and pelargonidin-3-galactoside (7%) were found as the main components. Among the other constituents, iridoid compound cornuside and the anthocyans cyanidin 3-O-galactoside, cyanidin 3-O-robinobioside, and pelargonidin 3-O-robinobioside were quantified in the fraction. In an animal model (New Zealand rabbits), the influence of loganic acid and the polyphenolic fraction isolated from Cornelian cherry fruit was investigated. We found a strong IOP-hypotensive effect for a 0.7% solution of loganic acid, which could be compared with the widely ophthalmologically used timolol. About a 25% decrease in IOP was observed within the first 3 hours of use. PMID:26124854

  18. Reduced-impact sliding pressure control valve for pneumatic hammer drill

    DOEpatents

    Polsky, Yarom; Grubelich, Mark C.; Vaughn, Mark R.

    2012-05-15

    A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

  19. Digoxin derivatives with selectivity for the α2β3 isoform of Na,K-ATPase potently reduce intraocular pressure

    PubMed Central

    Katz, Adriana; Tal, Daniel M.; Heller, Dan; Habeck, Michael; Ben Zeev, Efrat; Rabah, Bilal; Bar Kana, Yaniv; Marcovich, Arie L.; Karlish, Steven J. D.

    2015-01-01

    The ciliary epithelium in the eye consists of pigmented epithelial cells that express the α1β1 isoform of Na,K-ATPase and nonpigmented epithelial cells that express mainly the α2β3 isoform. In principle, a Na,K-ATPase inhibitor with selectivity for α2β3 that penetrates the cornea could effectively reduce intraocular pressure, with minimal systemic or local toxicity. We have recently synthesized perhydro-1,4-oxazepine derivatives of digoxin by NaIO4 oxidation of the third digitoxose and reductive amination with various R-NH2 substituents and identified derivatives with significant selectivity for human α2β1 over α1β1 (up to 7.5-fold). When applied topically, the most α2-selective derivatives effectively prevented or reversed pharmacologically raised intraocular pressure in rabbits. A recent structure of Na,K-ATPase, with bound digoxin, shows the third digitoxose approaching one residue in the β1 subunit, Gln84, suggesting a role for β in digoxin binding. Gln84 in β1 is replaced by Val88 in β3. Assuming that alkyl substituents might interact with β3Val88, we synthesized perhydro-1,4-oxazepine derivatives of digoxin with diverse alkyl substituents. The methylcyclopropyl and cyclobutyl derivatives are strongly selective for α2β3 over α1β1 (22–33-fold respectively), as determined either with purified human isoform proteins or intact bovine nonpigmented epithelium cells. When applied topically on rabbit eyes, these derivatives potently reduce both pharmacologically raised and basal intraocular pressure. The cyclobutyl derivative is more efficient than Latanoprost, the most widely used glaucoma drug. Thus, the conclusion is that α2β3-selective digoxin derivatives effectively penetrate the cornea and inhibit the Na,K-ATPase, hence reducing aqueous humor production. The new digoxin derivatives may have potential for glaucoma drug therapy. PMID:26483500

  20. Reduced-Order Model for Dynamic Optimization of Pressure Swing Adsorption

    SciTech Connect

    Agarwal, Anshul; Biegler, L.T.; Zitney, S.E.

    2007-11-01

    The last few decades have seen a considerable increase in the applications of adsorptive gas separation technologies, such as pressure swing adsorption (PSA). From an economic and environmental point of view, hydrogen separation and carbon dioxide capture from flue gas streams are the most promising applications of PSA. With extensive industrial applications, there is a significant interest for an efficient modeling, simulation, and optimization strategy. However, the design and optimization of the PSA processes have largely remained an experimental effort because of the complex nature of the mathematical models describing practical PSA processes. The separation processes are based on solid-gas equilibrium and operate under periodic transient conditions. Models for PSA processes are therefore multiple instances of partial differential equations (PDEs) in time and space with periodic boundary conditions that link the processing steps together and high nonlinearities arising from non-isothermal effects. The computational effort required to solve such systems is usually quite expensive and prohibitively time consuming. Besides this, stringent product specifications, required by many industrial processes, often lead to convergence failures of the optimizers. The solution of this coupled stiff PDE system is governed by steep concentrations and temperature fronts moving with time. As a result, the optimization of such systems for either design or operation represents a significant computational challenge to current differential algebraic equation (DAE) optimization techniques and nonlinear programming algorithms. Sophisticated optimization strategies have been developed and applied to PSA systems with significant improvement in the performance of the process. However, most of these approaches have been quite time consuming. This gives a strong motivation to develop cost-efficient and robust optimization strategies for PSA processes. Moreover, in case of flowsheet

  1. Analysis of evaporation in nuclear waste boreholes in unsaturated tuff

    SciTech Connect

    Zhou, W.; Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.

    1993-12-31

    We present an analysis of evaporation in a nuclear waste borehole in unsaturated tuff. In unsaturated tuff, water in contact with a waste container will evaporate due to the difference in vapor pressure between water in a flat film and water held in rock pores with curved interfaces. Decay heat will also enhance evaporation. It is important to study evaporation in a potential geologic repository of nuclear waste in unsaturated rock because the corrosion of waste containers is increased with liquid water. For radionuclides other than gaseous ones, their release from waste solids requires liquid water.

  2. The simultaneous mass and energy evaporation (SM2E) model.

    PubMed

    Choudhary, Rehan; Klauda, Jeffery B

    2016-01-01

    In this article, the Simultaneous Mass and Energy Evaporation (SM2E) model is presented. The SM2E model is based on theoretical models for mass and energy transfer. The theoretical models systematically under or over predicted at various flow conditions: laminar, transition, and turbulent. These models were harmonized with experimental measurements to eliminate systematic under or over predictions; a total of 113 measured evaporation rates were used. The SM2E model can be used to estimate evaporation rates for pure liquids as well as liquid mixtures at laminar, transition, and turbulent flow conditions. However, due to limited availability of evaporation data, the model has so far only been tested against data for pure liquids and binary mixtures. The model can take evaporative cooling into account and when the temperature of the evaporating liquid or liquid mixture is known (e.g., isothermal evaporation), the SM2E model reduces to a mass transfer-only model. PMID:26595699

  3. A vertical mouse and ergonomic mouse pads alter wrist position but do not reduce carpal tunnel pressure in patients with carpal tunnel syndrome.

    PubMed

    Schmid, Annina B; Kubler, Paul A; Johnston, Venerina; Coppieters, Michel W

    2015-03-01

    Non-neutral wrist positions and external pressure leading to increased carpal tunnel pressure during computer use have been associated with a heightened risk of carpal tunnel syndrome (CTS). This study investigated whether commonly used ergonomic devices reduce carpal tunnel pressure in patients with CTS. Carpal tunnel pressure was measured in twenty-one patients with CTS before, during and after a computer mouse task using a standard mouse, a vertical mouse, a gel mouse pad and a gliding palm support. Carpal tunnel pressure increased while operating a computer mouse. Although the vertical mouse significantly reduced ulnar deviation and the gel mouse pad and gliding palm support decreased wrist extension, none of the ergonomic devices reduced carpal tunnel pressure. The findings of this study do therefore not endorse a strong recommendation for or against any of the ergonomic devices commonly recommended for patients with CTS. Selection of ergonomic devices remains dependent on personal preference. PMID:25479984

  4. Spacesuit Water Membrane Evaporator; An Enhanced Evaporative Cooling System for the Advanced Extravehicular Mobility Unit Portable Life Support System

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Makinen, Janice V.; Miller, Sean; Campbell, Colin; Lynch, Bill; Vogel, Matt; Craft, Jesse; Wilkes, Robert; Kuehnel, Eric

    2014-01-01

    Development of the Advanced Extravehicular Mobility Unit (AEMU) portable life support subsystem (PLSS) is currently under way at NASA Johnson Space Center. The AEMU PLSS features a new evaporative cooling system, the Generation 4 Spacesuit Water Membrane Evaporator (Gen4 SWME). The SWME offers several advantages when compared with prior crewmember cooling technologies, including the ability to reject heat at increased atmospheric pressures, reduced loop infrastructure, and higher tolerance to fouling. Like its predecessors, Gen4 SWME provides nominal crew member and electronics cooling by flowing water through porous hollow fibers. Water vapor escapes through the hollow fiber pores, thereby cooling the liquid water that remains inside of the fibers. This cooled water is then recirculated to remove heat from the crew member and PLSS electronics. Test results from the backup cooling system which is based on a similar design and the subject of a companion paper, suggested that further volume reductions could be achieved through fiber density optimization. Testing was performed with four fiber bundle configurations ranging from 35,850 fibers to 41,180 fibers. The optimal configuration reduced the Gen4 SWME envelope volume by 15% from that of Gen3 while dramatically increasing the performance margin of the system. A rectangular block design was chosen over the Gen3 cylindrical design, for packaging configurations within the AEMU PLSS envelope. Several important innovations were made in the redesign of the backpressure valve which is used to control evaporation. A twin-port pivot concept was selected from among three low profile valve designs for superior robustness, control and packaging. The backpressure valve motor, the thermal control valve, delta pressure sensors and temperature sensors were incorporated into the manifold endcaps, also for packaging considerations. Flight-like materials including a titanium housing were used for all components. Performance testing

  5. Taurine Supplementation Reduces Blood Pressure and Prevents Endothelial Dysfunction and Oxidative Stress in Post-Weaning Protein-Restricted Rats

    PubMed Central

    Maia, Aline R.; Batista, Thiago M.; Victorio, Jamaira A.; Clerici, Stefano P.; Delbin, Maria A.; Carneiro, Everardo M.; Davel, Ana P.

    2014-01-01

    Introduction Taurine is a sulfur-containing amino acid that exerts protective effects on vascular function and structure in several models of cardiovascular diseases through its antioxidant and anti-inflammatory properties. Early protein malnutrition reprograms the cardiovascular system and is linked to hypertension in adulthood. This study assessed the effects of taurine supplementation in vascular alterations induced by protein restriction in post-weaning rats. Methods and Results Weaned male Wistar rats were fed normal- (12%, NP) or low-protein (6%, LP) diets for 90 days. Half of the NP and LP rats concomitantly received 2.5% taurine supplementation in the drinking water (NPT and LPT, respectively). LP rats showed elevated systolic, diastolic and mean arterial blood pressure versus NP rats; taurine supplementation partially prevented this increase. There was a reduced relaxation response to acetylcholine in isolated thoracic aortic rings from the LP group that was reversed by superoxide dismutase (SOD) or apocynin incubation. Protein expression of p47phox NADPH oxidase subunit was enhanced, whereas extracellular (EC)-SOD and endothelial nitric oxide synthase phosphorylation at Ser 1177 (p-eNOS) were reduced in aortas from LP rats. Furthermore, ROS production was enhanced while acetylcholine-induced NO release was reduced in aortas from the LP group. Taurine supplementation improved the relaxation response to acetylcholine and eNOS-derived NO production, increased EC-SOD and p-eNOS protein expression, as well as reduced ROS generation and p47phox expression in the aortas from LPT rats. LP rats showed an increased aortic wall/lumen ratio and taurine prevented this remodeling through a reduction in wall media thickness. Conclusion Our data indicate a protective role of taurine supplementation on the high blood pressure, endothelial dysfunction and vascular remodeling induced by post-weaning protein restriction. The beneficial vascular effect of taurine was

  6. Emergence of Reduced Susceptibility and Resistance to Fluoroquinolones in Escherichia coli in Taiwan and Contributions of Distinct Selective Pressures

    PubMed Central

    McDonald, L. Clifford; Chen, Feng-Jui; Lo, Hsiu-Jung; Yin, Hsiao-Chuan; Lu, Po-Liang; Huang, Cheng-Hua; Chen, Pei; Lauderdale, Tsai-Ling; Ho, Monto

    2001-01-01

    A survey of 1,203 Escherichia coli isolates from 44 hospitals in Taiwan revealed that 136 (11.3%) isolates were resistant to fluoroquinolones and that another 261 (21.7%) isolates had reduced susceptibility. Resistance was more common in isolates responsible for hospital-acquired (mostly in intensive care units) infections (17.5%) than in other adult inpatient (11.4%; P = 0.08) and outpatient isolates (11.9%; P > 0.1). Similarly, reduced susceptibility was more common in isolates responsible for hospital-acquired infections (30.9%) than in other adult inpatient (21.0%; P = 0.04) and outpatient (21.4%; P = 0.06) isolates. Isolates from pediatric patients were less likely to be resistant (1.3 versus 12.0%; P < 0.01) but were nearly as likely to have reduced susceptibility (17.7 versus 21.9%; P > 0.1) as nonpediatric isolates. There was an inverse relationship in the proportion of isolates that were resistant versus the proportion that had reduced susceptibility among isolates from individual hospitals (R = 0.031; P < 0.05). In an analysis of isolates from two hospitals, all 9 resistant strains possessed double point mutations in gyrA and all 19 strains with reduced susceptibility strains had single point mutations; no mutations were found among fully susceptible strains. Risk factors for resistance included underlying cancer (odds ratio [OR], 83; 95% confidence interval [CI95], 7.3 to 2,241; P < 0.001), exposure to a quinolone (OR, undefined; P = 0.02), and exposure to a nonquinolone antibiotic (OR, 20; CI95, 2.2 to 482; P < 0.001); underlying cancer was the only independent risk factor (OR, 83; CI95, 8.6 to 807; P < 0.001). There were no significant associations between any of these factors and reduced susceptibility. Whereas acute and chronic quinolone use in cancer patients is a major selective pressure for resistance, other undetermined but distinct selective pressures appear to be more responsible for reduced susceptibility to fluoroquinolones in E. coli. PMID

  7. Chronic hypercapnic incubation increases relative organ growth and reduces blood pressure of embryonic American alligator (Alligator mississippiensis).

    PubMed

    Eme, John; Crossley, Dane A

    2015-04-01

    Reptilian nests can experience natural hypoxic and hypercapnic conditions. We incubated alligator eggs at a female-only producing temperature (30°C) in three conditions: 21% O2/0.04% CO2, 21% O2/3.5% CO2 and 21% O2/7% CO2. Alligator embryos chronically incubated in high CO2 were markedly hypotensive (blood pressure reduced by 46%) and had relatively (mass-specific) enlarged hearts (dry mass increased by 20%), lungs (dry mass increased by 17%), and kidneys (dry mass increased by 14%). This study is the first to chronically incubate reptilian eggs in hypercapnia and suggests that high CO2 alters the cardiovascular phenotype of alligator embryos (low blood pressure, relatively enlarged hearts), as well as the relative size of the organs primarily responsible for acid base balance, lungs and kidneys. The lungs and kidneys are largely non-functional during embryonic development, and the embryonic phenotype of increased relative mass may be a predictive-adaptation to metabolic or respiratory acidosis, such as during exercise or high respiratory CO2. This study demonstrates that phenotypic plasticity of alligator embryos incubated in high CO2 may result in either preferential organ growth, or maintenance of organ growth with reduced somatic growth. PMID:25499241

  8. Concord grape juice supplementation reduces blood pressure in Korean hypertensive men: double-blind, placebo controlled intervention trial.

    PubMed

    Park, Yoo Kyoung; Kim, Jung-Shin; Kang, Myung-Hee

    2004-01-01

    Many of the flavonoids found in grapes and grape products such as juice or wine have been known to exert antioxidant, anti-inflammatory, platelet inhibitory and arterial relaxing effects either in vitro, in animal studies and in human trials. This study was designed to test the effect of Concord grape juice consumption on altering blood pressure in hypertensive patients. Forty subjects were given 5.5 ml/kg body weight/day of either Concord grape juice (CGJ) or a calorie-matched placebo drink every day for 8 weeks. Blood pressure (BP) was measured on weeks 0, 4 and 8. Compared to baseline, in the CGJ group systolic BP was reduced on average by 7.2 mm Hg (p = 0.005) and diastolic BP was reduced on average by 6.2 mm Hg (p = 0.001) at the end of 8 weeks. Comparable changes in the group getting the placebo product were -3.5 mm Hg (NS) and -3.2 mm Hg (p = 0.05) Consuming Concord grape juice, which is high in polyphenolic compounds, may favorably affect BP in hypertensive individuals. PMID:15630270

  9. Arctigenin reduces blood pressure by modulation of nitric oxide synthase and NADPH oxidase expression in spontaneously hypertensive rats.

    PubMed

    Liu, Ying; Wang, Guoyuan; Yang, Mingguang; Chen, Haining; zhao, Yan; Yang, Shucai; Sun, Changhao

    2015-12-25

    Arctigenin is a bioactive constituent from dried seeds of Arctium lappa L., which was traditionally used as medicine. Arctigenin exhibits various bioactivities, but its effects on blood pressure regulation are still not widely studied. In this study, we investigated antihypertensive effects of arctigenin by long-term treatment in spontaneously hypertensive rats (SHRs). Arctigenin (50 mg/kg) or vehicle was administered to SHRs or Wistar rats as negative control by oral gavage once a day for total 8 weeks. Nifedipine (3 mg/kg) was used as a positive drug control. After treatment, hemodynamic and physical parameters, vascular reactivity in aorta, the concentration of plasma arctigenin and serum thromboxane B2, NO release and vascular p-eNOS, p-Akt, caveolin-1 protein expression, and vascular superoxide anion generation and p47phox protein expression were detected and analyzed. The results showed that arctigenin significantly reduced systolic blood pressure and ameliorated endothelial dysfunction of SHRs. Arctigenin reduced the levels of thromboxane B2 in plasma and superoxide anion in thoracic aorta of SHRs. Furthermore, arctigenin increased the NO production by enhancing the phosphorylation of Akt and eNOS (Ser 1177), and inhibiting the expression of NADPH oxidase in thoracic aorta of SHRs. Our data suggested that antihypertensive mechanisms of arctigenin were associated with enhanced eNOS phosphorylation and decreased NADPH oxidase-mediated superoxide anion generation. PMID:26585490

  10. Reduced Pressure Electron Beam Welding Evaluation Activities on a Ni-Cr-Mo Alloy for Nuclear Waste Packages

    SciTech Connect

    Wong, F; Punshon, C; Dorsch, T; Fielding, P; Richard, D; Yang, N; Hill, M; DeWald, A; Rebak, R; Day, S; Wong, L; Torres, S; McGregor, M; Hackel, L; Chen, H-L; Rankin, J

    2003-09-11

    The current waste package design for the proposed repository at Yucca Mountain Nevada, USA, employs gas tungsten arc welding (GTAW) in fabricating the waste packages. While GTAW is widely used in industry for many applications, it requires multiple weld passes. By comparison, single-pass welding methods inherently use lower heat input than multi-pass welding methods which results in lower levels of weld distortion and also narrower regions of residual stresses at the weld TWI Ltd. has developed a Reduced Pressure Electron Beam (RPEB) welding process which allows EB welding in a reduced pressure environment ({le} 1 mbar). As it is a single-pass welding technique, use of RPEB welding could (1) achieve a comparable or better materials performance and (2) lead to potential cost savings in the waste package manufacturing as compared to GTAW. Results will be presented on the initial evaluation of the RPEB welding on a Ni-Cr-Mo alloy (a candidate alloy for the Yucca Mountain waste packages) in the areas of (a) design and manufacturing simplifications, (b) material performance and (c) weld reliability.

  11. The measurement of 129I for the cement and the paraffin solidified low and intermediate level wastes (LILWs), spent resin or evaporated bottom from the pressurized water reactor (PWR) nuclear power plants.

    PubMed

    Park, S D; Kim, J S; Han, S H; Ha, Y K; Song, K S; Jee, K Y

    2009-09-01

    In this paper a relatively simple and low cost analysis procedure to apply to a routine analysis of (129)I in low and intermediate level radioactive wastes (LILWs), cement and paraffin solidified evaporated bottom and spent resin, which are produced from nuclear power plants (NPPs), pressurized water reactors (PWR), is presented. The (129)I is separated from other nuclides in LILWs using an anion exchange adsorption and solvent extraction by controlling the oxidation and reduction state and is then precipitated as silver iodide for counting the beta activity with a low background gas proportional counter (GPC). The counting efficiency of GPC was varied from 4% to 8% and it was reversely proportional to the weight of AgI by a self absorption of the beta activity. Compared to a higher pH, the chemical recovery of iodide as AgI was lowered at pH 4. It was found that the chemical recovery of iodide for the cement powder showed a lower trend by increasing the cement powder weight, but it was not affected for the paraffin sample. In this experiment, the overall chemical recovery yield of the cement and paraffin solidified LILW samples and the average weight of them were 67+/-3% and 5.43+/-0.53 g, 70+/-7% and 10.40+/-1.60 g, respectively. And the minimum detectable activity (MDA) of (129)I for the cement and paraffin solidified LILW samples was calculated as 0.070 and 0.036 Bq/g, respectively. Among the analyzed cement solidified LILW samples, (129)I activity concentration of four samples was slightly higher than the MDA and their ranges were 0.076-0.114 Bq/g. Also of the analyzed paraffin solidified LILW samples, five samples contained a little higher (129)I activity concentration than the MDA and their ranges were 0.036-0.107 Bq/g. PMID:19297180

  12. Chimney Stove Intervention to Reduce Long-term Wood Smoke Exposure Lowers Blood Pressure among Guatemalan Women

    PubMed Central

    McCracken, John P.; Smith, Kirk R.; Díaz, Anaité; Mittleman, Murray A.; Schwartz, Joel

    2007-01-01

    Background and Objective RESPIRE, a randomized trial of an improved cookstove, was conducted in Guatemala to assess health effects of long-term reductions in wood smoke exposure. Given the evidence that ambient particles increase blood pressure, we hypothesized that the intervention would lower blood pressure. Methods Two study designs were used: a) between-group comparisons based on randomized stove assignment, and b) before-and-after comparisons within subjects before and after they received improved stoves. From 2003 to 2005, we measured personal fine particle (particulate matter with aerodynamic diameter < 2.5 μm; PM2.5) exposures and systolic (SBP) and diastolic blood pressure (DBP) among women > 38 years of age from the chimney woodstove intervention group (49 subjects) and traditional open wood fire control group (71 subjects). Measures were repeated up to three occasions. Results Daily average PM2.5 exposures were 264 and 102 μg/m3 in the control and intervention groups, respectively. After adjusting for age, body mass index, an asset index, smoking, secondhand tobacco smoke, apparent temperature, season, day of week, time of day, and a random subject intercept, the improved stove intervention was associated with 3.7 mm Hg lower SBP [95% confidence interval (CI), −8.1 to 0.6] and 3.0 mm Hg lower DBP (95% CI, −5.7 to −0.4) compared with controls. In the second study design, among 55 control subjects measured both before and after receiving chimney stoves, similar associations were observed. Conclusion The between-group comparisons provide evidence, particularly for DBP, that the chimney stove reduces blood pressure, and the before-and-after comparisons are consistent with this evidence. PMID:17637912

  13. Field Investigations of Evaporation from a Bare Soil

    NASA Astrophysics Data System (ADS)

    Evett, Steven Roy

    Selected components of the water and energy balances at the surface of a bare clay loam were measured at 57 locations in a 1 ha field. Spatial and temporal variability of these components were also studied. Components included evaporation, irrigation, moisture storage, sensible heat flux and long wave radiation. Sub-studies were conducted on irrigation uniformity under low pressure sprinklers; and, on steel versus plastic microlysimeters (ML) of various lengths. An energy balance model of evaporation, requiring minimal inputs, was developed and validated giving an r ^2 value of 0.78. Model improvements included an easy method of accurately estimating soil surface temperature at many points in a field, and an empirically fitted transfer coefficient function for the sensible heat flux from the reference dry soil. The omission of soil heat flux and reflected shortwave radiation terms was shown to reduce model accuracy. Steel ML underestimated cumulative evaporation compared to plastic ML at 20 and 30 cm lengths. Cumulative evaporation increased with ML length. The 10 and 20 cm ML were too short for use over multiple days but 30 cm ML may not be long enough for extended periods. Daily net soil heat flux for steel ML averaged 44% higher than that for both plastic ML and undisturbed field soil. Christiansen's uniformity coefficient (UCC) was close to 0.83 for each of 3 irrigations when measured by both catch cans and by profile water contents. But UCC for the change in storage due to irrigation averaged only 0.43 indicating than the high uniformity of profile water contents was more due to surface and subsurface redistribution than to the uniformity of application. Profile water contents and catch can depths were time invariant across at least 3 irrigations. Midday soil surface temperatures and daily evaporation were somewhat less time invariant. Variogram plots for evaporation and surface temperature showed mostly random behavior. Relative variograms represented well

  14. Characterization of a high-pressure diesel fuel injection system as a control technology option to improve engine performance and reduce exhaust emissions

    NASA Technical Reports Server (NTRS)

    Mcfadden, J. J.; Dezelick, R. A.; Barrows, R. R.

    1983-01-01

    Test results from a high pressure electronically controlled fuel injection system are compared with a commercial mechanical injection system on a single cylinder, diesel test engine using an inlet boost pressure of 2.6:1. The electronic fuel injection system achieved high pressure by means of a fluid intensifier with peak injection pressures of 47 to 69 MPa. Reduced exhaust emissions were demonstrated with an increasing rate of injection followed by a fast cutoff of injection. The reduction in emissions is more responsive to the rate of injection and injection timing than to high peak injection pressure.

  15. Simulation on Vapor Flow in the Absorber/Evaporator of an Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    Two-dimensional numerical computation methodology for vapor flow in the absorber/ evaporator in an absorption chiller has been suggested and the effect of pitch ratio of cylinders in the absorber/evaporator has been discussed. Pseudo-diffusion effects of surfactants added to lithium bromide solution flowing along cylinders in the absorber were considered into liquid film model suggested in the previous study. From the results, the present model was found to agree well with experimental data in a rather wide range of the pressure in the present system. The present model effectively reduces the computational load for vapor flow in the absorber/evaporator including 176 cylinders. Near the top and bottom walls of the absorber/evaporator, the high velocity regions were observed and the recirculating regions were also found to be formed just inside of the high velocity regions. This high velocity region is intensified with pitch-to-diameter ratio decrease because the vapor flow penetrating from the back side of the absorber increases for the pressure drop increase of front side of the absorber.

  16. Hot air drum evaporator

    DOEpatents

    Black, Roger L.

    1981-01-01

    An evaporation system for aqueous radioactive waste uses standard 30 and 55 gallon drums. Waste solutions form cascading water sprays as they pass over a number of trays arranged in a vertical stack within a drum. Hot dry air is circulated radially of the drum through the water sprays thereby removing water vapor. The system is encased in concrete to prevent exposure to radioactivity. The use of standard 30 and 55 gallon drums permits an inexpensive compact modular design that is readily disposable, thus eliminating maintenance and radiation build-up problems encountered with conventional evaporation systems.

  17. Optimization of evaporative cooling

    NASA Astrophysics Data System (ADS)

    Sackett, C. A.; Bradley, C. C.; Hulet, R. G.

    1997-05-01

    Recent experiments have used forced evaporative cooling to produce Bose-Einstein condensation in dilute gases. The evaporative cooling process can be optimized to provide the maximum phase-space density with a specified number of atoms remaining. We show that this global optimization is approximately achieved by locally optimizing the cooling efficiency at each instant. We discuss how this method can be implemented, and present the results for our 7Li trap. The predicted behavior of the gas is found to agree well with experiment.

  18. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, Nick; Lukenbach, Max; Hokanson, Kelly; Devito, Kevin; Hopkinson, Chris; Petrone, Rich; Mendoza, Carl; Waddington, Mike

    2016-04-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This promotes high water table positions at a landscape scale which limit the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  19. Instituting a filtration/pressurization system to reduce dust concentrations in a control room at a mineral processing plant

    PubMed Central

    Noll, J.; Cecala, A.; Hummer, J.

    2016-01-01

    The National Institute for Occupational Safety and Health has observed that many control rooms and operator compartments in the U.S. mining industry do not have filtration systems capable of maintaining low dust concentrations in these areas. In this study at a mineral processing plant, to reduce respirable dust concentrations in a control room that had no cleaning system for intake air, a filtration and pressurization system originally designed for enclosed cabs was modified and installed. This system was composed of two filtering units: one to filter outside air and one to filter and recirculate the air inside the control room. Eighty-seven percent of submicrometer particles were reduced by the system under static conditions. This means that greater than 87 percent of respirable dust particles should be reduced as the particle-size distribution of respirable dust particles is greater than that of submicrometer particles, and filtration systems usually are more efficient in capturing the larger particles. A positive pressure near 0.02 inches of water gauge was produced, which is an important component of an effective system and minimizes the entry of particles, such as dust, into the room. The intake airflow was around 118 cfm, greater than the airflow suggested by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) for acceptable indoor air quality. After one year, the loading of the filter caused the airflow to decrease to 80 cfm, which still produces acceptable indoor air quality. Due to the loading of the filters, the reduction efficiency for submicrometer particles under static conditions increased to 94 percent from 87 percent. PMID:26834293

  20. Hydrodynamic Instabilities Produced by Evaporation

    NASA Astrophysics Data System (ADS)

    Romo-Cruz, Julio Cesar Ruben; Hernandez-Zapata, Sergio; Ruiz-Chavarria, Gerardo

    2012-11-01

    When a liquid layer (alcohol in the present work) is in an environment where its relative humidity is less than 100 percent evaporation appears. When RH is above a certain threshold the liquid is at rest. If RH decreases below this threshold the flow becomes unstable, and hydrodynamic cells develop. The aim of this work is to understand the formation of those cells and its main features. Firstly, we investigate how the cell size depends on the layer width. We also study how temperature depends on the vertical coordinate when the cells are present. An inverse temperature gradient is found, that is, the bottom of liquid layer is colder than the free surface. This shows that the intuitive idea that the cells are due to a direct temperature gradient, following a Marangoni-like process, does not work. We propose the hypothesis that the evaporation produce a pressure gradient that is responsible of the cell development. On the other hand, using a Schlieren technique we study the topography of the free surface when cells are present. Finally the alcohol vapor layer adjacent to the liquid surface is explored using scattering experiments, giving some insight on the plausibility of the hypothesis described previously. Authors acknowledge support by DGAPA-UNAM under project IN116312 ``Vorticidad y ondas no lineales en fluidos.''

  1. Spacesuit Water Membrane Evaporator; An Enhanced Evaporative Cooling Systems for the Advanced Extravehicular Mobility Unit Portable Life Support System

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Makinen, Janice V.; Miller, Sean.; Campbell, Colin; Lynch, Bill; Vogel, Matt; Craft, Jesse; Petty, Brian

    2014-01-01

    Spacesuit Water Membrane Evaporator - Baseline heat rejection technology for the Portable Life Support System of the Advanced EMU center dot Replaces sublimator in the current EMU center dot Contamination insensitive center dot Can work with Lithium Chloride Absorber Radiator in Spacesuit Evaporator Absorber Radiator (SEAR) to reject heat and reuse evaporated water The Spacesuit Water Membrane Evaporator (SWME) is being developed to replace the sublimator for future generation spacesuits. Water in LCVG absorbs body heat while circulating center dot Warm water pumped through SWME center dot SWME evaporates water vapor, while maintaining liquid water - Cools water center dot Cooled water is then recirculated through LCVG. center dot LCVG water lost due to evaporation (cooling) is replaced from feedwater The Independent TCV Manifold reduces design complexity and manufacturing difficulty of the SWME End Cap. center dot The offset motor for the new BPV reduces the volume profile of the SWME by laying the motor flat on the End Cap alongside the TCV.

  2. Continuous enrichment culturing of thermophiles under sulfate and nitrate-reducing conditions and at deep-sea hydrostatic pressures.

    PubMed

    Houghton, J L; Seyfried, W E; Banta, A B; Reysenbach, A-L

    2007-03-01

    A continuous culture bioreactor was developed to enrich for nitrate and sulfate reducing thermophiles under in situ deep-sea pressures. The ultimate objective of this experimental design was to be able to study microbial activities at chemical and physical conditions relevant to seafloor hydrothermal vents. Sulfide, sulfate and oxide minerals from sampled seafloor vent-chimney structures [East Pacific Rise (9 degrees 46'N)] served as source mineral and microbial inoculum for enrichment culturing using nitrate and sulfate-enriched media at 70 and 90 degrees C and 250 bars. Changes in microbial diversity during the continuous reaction flow were monitored using denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16S rRNA gene fragments. Time series changes in fluid chemistry were also monitored throughout the experiment to assess the feedback between mineral-fluid reaction and metabolic processes. Data indicate a shift from the dominance of epsilon Proteobacteria in the initial inoculum to the several Aquificales-like phylotypes in nitrate-reducing enrichment media and Thermodesulfobacteriales in the sulfate-reducing enrichment media. Methanogens were detected in the original sulfide sample and grew in selected sulfate-enriched experiments. Microbial interactions with anhydrite and pyrrhotite in the chimney material resulted in measurable changes in fluid chemistry despite a fluid residence time only 75 min in the reactor. Changes in temperature rather than source material resulted in greater differences in microbial enrichments and mediated geochemical reactions. PMID:17221162

  3. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

    2011-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  4. Modelling the evaporation of a tear film over a contact lens.

    PubMed

    Talbott, Kevin; Xu, Amber; Anderson, Daniel M; Seshaiyer, Padmanabhan

    2015-06-01

    A contact lens (CL) separates the tear film into a pre-lens tear film (PrLTF), the fluid layer between the CL and the outside environment, and a post-lens tear film (PoLTF), the fluid layer between the CL and the cornea. We examine a model for evaporation of a PrLTF on a modern permeable CL allowing fluid transfer between the PrLTF and the PoLTF. Evaporation depletes the PrLTF, and continued evaporation causes depletion of the PoLTF via fluid loss through the CL. Governing equations include Navier-Stokes, heat and Darcy's equations for the fluid flow and heat transfer in the PrLTF and porous layer. The PoLTF is modelled by a fixed pressure condition on the posterior surface of the CL. The original model is simplified using lubrication theory for the PrLTF and CL applied to a sagittal plane through the eye. We obtain a partial differential equation (PDE) for the PrLTF thickness that is first-order in time and fourth-order in space. This model incorporates evaporation, conjoining pressure effects in the PrLTF, capillarity and heat transfer. For a planar film, we find that this PDE can be reduced to an ordinary differential equation (ODE) that can be solved analytically or numerically. This reduced model allows for interpretation of the various system parameters and captures most of the basic physics contained in the model. Comparisons of ODE and PDE models, including estimates for the loss of fluid through the lens due to evaporation, are given. PMID:24521538

  5. Next-Generation Evaporative Cooling Systems for the Advanced Extravehicular Mobility Unit Portable Life Support System

    NASA Technical Reports Server (NTRS)

    Makinen, Janice V.; Anchondo, Ian; Bue, Grant C.; Campbell, Colin; Colunga, Aaron

    2012-01-01

    The development of the Advanced Extravehicular Mobility Unit (AEMU) Portable Life Support System (PLSS) is currently underway at NASA Johnson Space Center. The AEMU PLSS features two new evaporative cooling systems, the Reduced Volume Prototype Spacesuit Water Membrane Evaporator (RVP SWME), and the Auxiliary Cooling Loop (ACL). The RVP SWME is the third generation of hollow fiber SWME hardware, and like its predecessors, RVP SWME provides nominal crewmember and electronics cooling by flowing water through porous hollow fibers. Water vapor escapes through the hollow fiber pores, thereby cooling the liquid water that remains inside of the fibers. This cooled water is then recirculated to remove heat from the crewmember and PLSS electronics. Major design improvements, including a 36% reduction in volume, reduced weight, and more flight like back-pressure valve, facilitate the packaging of RVP SWME in the AEMU PLSS envelope. In addition to the RVP SWME, the Auxiliary Cooling Loop (ACL), was developed for contingency crewmember cooling. The ACL is a completely redundant, independent cooling system that consists of a small evaporative cooler--the Mini Membrane Evaporator (Mini-ME), independent pump, independent feed-water assembly and independent Liquid Cooling Garment (LCG). The Mini-ME utilizes the same hollow fiber technology featured in the RVP SWME, but is only 25% of the size of RVP SWME, providing only the necessary crewmember cooling in a contingency situation. The ACL provides a number of benefits when compared with the current EMU PLSS contingency cooling technology; contingency crewmember cooling can be provided for a longer period of time, more contingency situations can be accounted for, no reliance on a Secondary Oxygen Vessel (SOV) for contingency cooling--thereby allowing a SOV reduction in size and pressure, and the ACL can be recharged-allowing the AEMU PLSS to be reused, even after a contingency event. The development of these evaporative cooling

  6. Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

    NASA Astrophysics Data System (ADS)

    Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

    2006-06-01

    Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

  7. Growth of complex SiGe/Ge superlattices by reduced pressure chemical vapour deposition at low temperature

    NASA Astrophysics Data System (ADS)

    Halpin, John E.; Rhead, Stephen D.; Sanchez, Ana M.; Myronov, Maksym; Leadley, David R.

    2015-11-01

    In this work the growth of complex n-type, high Ge content superlattice structures by reduced pressure chemical vapor deposition is presented. The structures feature 50 repeats of a 14 layer period, which includes a main quantum well that is between 13 and 21 nm wide. The total epitaxy thickness is approximately 8 μm. Diffusion and segregation in the structures was minimized by using a low growth temperature. Materials characterization shows the structures to be of good crystalline quality, with the thickness of all layers close to the design, abrupt interfaces, and uniformity throughout the structures. High angle annular dark field scanning transmission electron microscopy is shown to be an ideal technique for measuring layer thickness and interface quality in these structures.

  8. Ablation of the N-type calcium channel ameliorates diabetic nephropathy with improved glycemic control and reduced blood pressure.

    PubMed

    Ohno, Shoko; Yokoi, Hideki; Mori, Kiyoshi; Kasahara, Masato; Kuwahara, Koichiro; Fujikura, Junji; Naito, Masaki; Kuwabara, Takashige; Imamaki, Hirotaka; Ishii, Akira; Saleem, Moin A; Numata, Tomohiro; Mori, Yasuo; Nakao, Kazuwa; Yanagita, Motoko; Mukoyama, Masashi

    2016-01-01

    Pharmacological blockade of the N- and L-type calcium channel lessens renal injury in kidney disease patients. The significance of specific blockade of α1 subunit of N-type calcium channel, Cav2.2, in diabetic nephropathy, however, remains to be clarified. To examine functional roles, we mated Cav2.2(-/-) mice with db/db (diabetic) mice on the C57BLKS background. Cav2.2 was localized in glomeruli including podocytes and in distal tubular cells. Diabetic Cav2.2(-/-) mice significantly reduced urinary albumin excretion, glomerular hyperfiltration, blood glucose levels, histological deterioration and systolic blood pressure (SBP) with decreased urinary catecholamine compared to diabetic Cav2.2(+/+) mice. Interestingly, diabetic heterozygous Cav2.2(+/-) mice also decreased albuminuria, although they exhibited comparable systolic blood pressure, sympathetic nerve activity and creatinine clearance to diabetic Cav2.2(+/+) mice. Consistently, diabetic mice with cilnidipine, an N-/L-type calcium channel blocker, showed a reduction in albuminuria and improvement of glomerular changes compared to diabetic mice with nitrendipine. In cultured podocytes, depolarization-dependent calcium responses were decreased by ω-conotoxin, a Cav2.2-specific inhibitor. Furthermore, reduction of nephrin by transforming growth factor-β (TGF-β) in podocytes was abolished with ω-conotoxin, cilnidipine or mitogen-activated protein kinase kinase inhibitor. In conclusion, Cav2.2 inhibition exerts renoprotective effects against the progression of diabetic nephropathy, partly by protecting podocytes. PMID:27273361

  9. Thermodynamic performance testing of the orbiter flash evaporator system

    NASA Technical Reports Server (NTRS)

    Jaax, J. R.; Melgares, M. A.; Frahm, J. P.

    1980-01-01

    System level testing of the space shuttle orbiter's development flash evaporator system (FES) was performed in a thermal vacuum chamber capable of simulating ambient ascent, orbital, and entry temperature and pressure profiles. The test article included the evaporator assembly, high load and topping exhaust duct and nozzle assemblies, and feedwater supply assembly. Steady state and transient heat load, water pressure/temperature and ambient pressure/temperature profiles were imposed by especially designed supporting test hardware. Testing in 1978 verified evaporator and duct heater thermal design, determined FES performance boundaries, and assessed topping evaporator plume characteristics. Testing in 1979 combined the FES with the other systems in the orbiter active thermal control subsystem (ATCS). The FES met or exceeded all nominal and contingency performance requirements during operation with the integrated ATCS. During both tests stability problems were encountered during steady state operations which resulted in subsequent design changes to the water spray nozzle and valve plate assemblies.

  10. New Perspectives on Ophiolite Formation: Evidence from Ultrahigh Pressure (UHP), Highly Reduced and Crustal-type Minerals in Podiform Chromitites

    NASA Astrophysics Data System (ADS)

    Robinson, P. T.; Yang, J.

    2014-12-01

    Separated and in situ ultrahigh pressure (UHP), highly reduced and crustal-type minerals are common in podiform chromitites of the Luobusa and Dongqiao ophiolites, Tibet and the Ray-Iz ophiolite of the Polar Urals, Russia. Highly reduced and crustal-type minerals have also been recovered from the Oman ophiolite. UHP minerals include diamond, coesite-stishovite and kyanite, whereas highly reduced minerals are mainly moissanite (SiC), native elements (e.g., Si, Fe, Cr, Al, Ti, Mn, W, Ta) and a wide variety of metallic alloys. Crustal-type minerals are represented by various combinations of zircon, corundum, almandine garnet, kyanite, andalusite, quartz, K-feldspar, plagioclase, apatite, amphibole, rutile, and titanite. Most in-situ grains are hosted in small, circular to irregular patches of amorphous carbon within grains of magnesiochromite, indicating the former presence of a C-rich fluid, either during or after crystallization of the chromite. The recovered zircons are typically rounded to sub-rounded grains with complex internal structures indicating polyphase growth. Their trace element contents and low-pressure inclusion assemblages (quartz, muscovite, K-feldspar, apatite, ilmenite, rutile) indicate a continental crustal origin. The zircons have SIMS U-Pb ages that are generally much older than the host ophiolite (total range: 90 to 2500 Ma). The presence of numerous crustal minerals, particularly zircon, suggests derivation from metasedimentary rocks subducted into the mantle. The preservation of UHP, highly reduced and crustal-type minerals in chromitites implies effective isolation from the mafic melts that formed the ophiolites and chromitites. Clearly, the formation of ophiolites and podiform chromitites must be a complex, multistage process involving crystallization of magnesiochromite grains at depth in the upper mantle, upwelling of the host peridotites and chromitites, capture of mantle wedges above suprasubduction zones, further crystallization and

  11. Film evaporation MEMS thruster array for micropropulsion

    NASA Astrophysics Data System (ADS)

    Cofer, Anthony G.

    Current small sat propulsion systems require a substantial mass fraction of the vehicle involving tradeoffs between useful payload mass and maneuverability. This is also an issue with available attitude control systems which are either quickly saturated reaction wheels or movable high drag surfaces with long response times. What is needed is a low mass low power self-contained propulsion unit that can be easily installed and modeled. The proposed Film-Evaporation MEMS Tunable Array (FEMTA), exploits the small scale surface tension effect in conjunction with temperature dependent vapor pressure to realize a thermal valving system. The local vapor pressure is increased by resistive film heating until it exceeds meniscus strength in the nozzle inducing vacuum boiling which provides a stagnation pressure equal to vapor pressure at that point which is used for propulsion. The heat of vaporization is drawn from the bulk fluid and is replaced by either an integrated heater or waste heat from the vehicle. Proof of concept was initially achieved with a macroscale device made possible by using ethylene glycol, which has a low vapor pressure and high surface tension, as the working fluid. Both the thermal valving effect and cooling feature were demonstrated though at reduced performance than would be expected for water. Three generations of prototype FEMTA devices have been fabricated at Birck Nanotechnology Center on 200 and 500 micrometer thick silicon wafers. Preliminary testing on first generation models had tenuously demonstrated behavior consistent with the macroscale tests but there was not enough data for solid confirmation. Some reliability issues had arisen with the integrated heaters which were only partially alleviated in the second generation of FEMTAs. This led to a third generation and two changes in heater material until a chemically resilient material was found. The third generation of microthrusters were tested on the microNewton thrust stand at Purdue

  12. Soil water evaporation and crop residues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residues have value when left in the field and also when removed from the field and sold as a commodity. Reducing soil water evaporation (E) is one of the benefits of leaving crop residues in place. E was measured beneath a corn canopy at the soil suface with nearly full coverage by corn stover...

  13. Capillary Limit in a Loop Heat Pipe with Dual Evaporators

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Birur, Gajanana; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper describes a study on the capillary limit of a loop heat pipe (LHP) with two evaporators and two condensers. Both theoretical analysis and experimental investigation are conducted. Tests include heat load to one evaporator only, even heat loads to both evaporators and uneven heat load to both evaporators. Results show that after the capillary limit is exceeded, vapor will penetrate through the wick of the weaker evaporator and the compensation chamber (CC) of that evaporator will control the loop operating temperature regardless of which CC has been in control prior to the event Because the evaporator can tolerate vapor bubbles, the loop may continue to work and reach a new steady state at a higher operating temperature. The loop may even function with a modest increase in the heat load past the capillary limit With a heat load to only one evaporator, the capillary limit can be identified by rapid increases in the operating temperature and in the temperature difference between the evaporator and the CC. However, it is more difficult to tell when the capillary limit is exceeded if heat loads are applied to both evaporators. In all cases, the loop can recover by reducing the heat load to the loop.

  14. Convective Evaporation Of Sprayed Liquid

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth G.

    1987-01-01

    Theoretical model developed to analyze behavior of both dense and dilute clusters of evaporating liquid drops in gas flows. Particularly useful in search for methods of controlling evaporation, ignition, and combustion of fuel sprays.

  15. MOVES2014: Evaporative Emissions Report

    EPA Science Inventory

    Vehicle evaporative emissions are now modeled in EPA’s MOVES according to physical processes, permeation, tank vapor venting, liquid leaks, and refueling emissions. With this update, the following improvements are being incorporated into MOVES evaporative emissions methodology, a...

  16. A practical algorithm to reduce false critical ECG alarms using arterial blood pressure and/or photoplethysmogram waveforms.

    PubMed

    Zong, Wei; Nielsen, Larry; Gross, Brian; Brea, Juan; Frassica, Joseph

    2016-08-01

    There has been a high rate of false alarms for the critical electrocardiogram (ECG) arrhythmia events in intensive care units (ICUs), from which the 'crying-wolf' syndrome may be resulted and patient safety may be jeopardized. This article presents an algorithm to reduce false critical arrhythmia alarms using arterial blood pressure (ABP) and/or photoplethysmogram (PPG) waveform features. We established long duration reference alarm datasets which consist of 573 ICU waveform-alarm records (283 for development set and 290 for test set) with total length of 551 patent days. Each record has continuous recordings of ECGs, ABP and/or PPG signals and contains one or multiple critical ECG alarms. The average length of a record is 23 h. There are totally 2408 critical ECG alarms (1414 in the development set and 994 in the test set), each of which was manually annotated by experts. The algorithm extracts ABP/PPG pulse features on a beat-by-beat basis. For each pulse, five event feature indicators (EFIs), which correspond to the five critical ECG alarms, are generated. At the time of a critical ECG alarm, the corresponding EFI values of those ABP/PPG pulses around the alarm time are checked for adjudicating (accept/reject) this alarm. The algorithm retains all (100%) the true alarms and significantly reduces the false alarms. Our results suggest that the algorithm is effective and practical on account of its real-time dynamic processing mechanism and computational efficiency. PMID:27455375

  17. Formation and evaporation of nonsingular black holes.

    PubMed

    Hayward, Sean A

    2006-01-27

    Regular (nonsingular) space-times are given that describe the formation of a (locally defined) black hole from an initial vacuum region, its quiescence as a static region, and its subsequent evaporation to a vacuum region. The static region is Bardeen-like, supported by finite density and pressures, vanishing rapidly at large radius and behaving as a cosmological constant at small radius. The dynamic regions are Vaidya-like, with ingoing radiation of positive-energy flux during collapse and negative-energy flux during evaporation, the latter balanced by outgoing radiation of positive-energy flux and a surface pressure at a pair creation surface. The black hole consists of a compact space-time region of trapped surfaces, with inner and outer boundaries that join circularly as a single smooth trapping horizon. PMID:16486679

  18. Supine Treadmill Exercise in Lower Body Negative Pressure Combined with Resistive Exercise Counteracts Bone Loss, Reduced Aerobic Upright Exercise Capacity and Reduced Muscle Strength

    NASA Technical Reports Server (NTRS)

    Meuche, Sabine; Schneider, S. M.; Lee, S. M. C.; Macias, B. R.; Smith, S. M.; Watenpaugh, D. E.; Hargens, A. R.

    2006-01-01

    Long-term exposure to weightlessness leads to cardiovascular and musculoskeletal deconditioning. In this report, the effectiveness of combined supine treadmill exercise in a lower body negative pressure chamber (LBNPex) and flywheel resistive exercise (Rex) countermeasures was determined to prevent bone loss, reduced aerobic upright exercise capacity and reduced muscle strength. We hypothesized that exercise subjects would show less decrease in bone mineral density (BMD), peak oxygen consumption (VO2pk) and knee extensor strength (KES) than control subjects. Sixteen healthy female subjects participated in a 60-d 6(sup 0) head-down tilt bed rest (BR) study after providing written informed consent. Subjects were assigned to one of two groups: a non-exercising control group CON or an exercise group EX performing LBNPex 2-4 d/wk and Rex every 3rd-d. VO2pk was measured with a maximal, graded, upright treadmill test performed pre-BR and on 3-d after BR. BMD was assessed before and 3-d after BR. Isokinetic KES was measured before and 5-d after BR. Two-way repeated measures ANOVA were performed. Statistical significance was set at p less than 0.05. CON experienced a significant decrease in BMD in the trochanter (PRE: 0.670 plus or minus 0.045; POST: 0.646 plus or minus 0.352 g (raised dot) per square centimeter) and in the whole hip (PRE=0.894 plus or minus 0.059; POST: 0.858 plus or minus 0.057 g (raised dot) per square centimeter). BMD also decreased significantly in EX in the trochanter (PRE: 0.753 plus or minus 0.0617; POST: 0.741 plus or minus 0.061 g (raised dot) per square centimeter) and whole hip (PRE: 0.954 plus or minus 0.067; POST: 0.935 plus or minus 0.069 g (raised dot) per square centimeter). BMD losses were significantly less in EX than in CON subjects. VO2pk was significantly decreased in the CON after BR (PRE: 38.0 plus or minus 4.8; POST: 29.9 plus or minus 4.2 ml (raised dot) per kilogram per minute), but not in the EX (PRE: 39.0 plus or minus 2.0; POST

  19. Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 10(exp -7) mm Hg

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Swikert, Max; Johnson, Robert L.

    1961-01-01

    The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.

  20. Strophanthus hispidus attenuates the Ischemia-Reperfusion induced myocardial Infarction and reduces mean arterial pressure in renal artery occlusion

    PubMed Central

    Gundamaraju, Rohit; Vemuri, Ravi Chandra; Singla, Rajeev K; Manikam, Rishya; Rao, A Ranga; Sekaran, Shamala Devi

    2014-01-01

    Background: The myocardium is generally injured in the case of reperfusion injury and arterial damage is caused by hypertension. In reference to these statements, the present study was focused. Cardiac glycosides were said to have protective effects against myocardial infarction and hypertension. Strophanthus hispidus was thus incorporated in the study. Objective: The prime objective of the study was to investigate the protective effects of Strophanthus hispidus against ischemia-reperfusion myocardial Infarction and renal artery occluded hypertension in rats. Materials and Methods: The animal model adopted was surgically-induced myocardial ischemia, performed by means of left anterior descending coronary artery occlusion (LAD) for 30 min followed by reperfusion for another 4 h. Infarct size was assessed by using the staining agent TTC (2,3,5-triphenyl tetrazolium chloride). Hypertension was induced by clamping the renal artery with renal bulldog clamp for 4 h. Results: The study was fruitful by the effect of Strophanthus hispidus on infarction size, which got reduced to 27.2 ± 0.5and 20.0 ± 0.2 by 500 mg/Kg and 1000 mg/Kg ethanolic extracts which was remarkably significant when compared with that of the control group 52.8 ± 4.6. The plant extract did reduce heart rate at various time intervals. There was also a protective effect in the case of mean arterial blood pressure were the 500 mg/Kg and 1000 mg/Kg of the plant extract did reduce the hypertension after 60 minutes was 60.0 ± 4.80 and 50.50 ± 6.80. Conclusion: The results suggest that 500 mg/Kg and 100 mg/Kg ethanolic extract of Strophanthus hispidus was found to possess significant cardiac protective and anti-hypertensive activity. PMID:25298674

  1. Short-term dietary nitrate supplementation augments cutaneous vasodilatation and reduces mean arterial pressure in healthy humans.

    PubMed

    Keen, Jeremy T; Levitt, Erica L; Hodges, Gary J; Wong, Brett J

    2015-03-01

    Nitrate supplementation in the form of beetroot juice has been shown to increase nitric oxide (NO) where nitrate can be reduced to nitrite and, subsequently, to NO through both nitric oxide synthase (NOS)-dependent and -independent pathways. We tested the hypothesis that nitrate supplementation would augment the NO component of the cutaneous vasodilatation to local skin heating in young, healthy humans. Participants reported to the lab for pre- and post-supplement local heating protocols. Nitrate supplementation consisted of one shot (70 ml) of beetroot juice (0.45 g nitrate; 5mM) for three days. Six participants were equipped with two microdialysis fibers on the ventral forearm and randomly assigned to lactated Ringer's (control) or continuous infusion of 20mM l-NAME (NOS inhibitor). The control site was subsequently perfused with l-NAME once a plateau in skin blood flow was achieved to quantify NOS-dependent cutaneous vasodilatation. Skin blood flow via laser-Doppler flowmetry (LDF) and mean arterial pressure (MAP) were measured; cutaneous vascular conductance (CVC) was calculated as LDF/MAP and normalized to %CVCmax. Beetroot juice reduced MAP (Pre: 90 ± 1 mmHg vs. Post: 83 ± 1 mmHg) and DBP (Pre: 74 ± 2 mmHg vs. Post: 62 ± 3 mmHg) (P<0.05). The plateau phase of the local heating response at control sites was augmented post-beetroot juice (91 ± 5%CVCmax) compared to pre-beetroot juice (79 ± 2%CVCmax) (P<0.05). There was no difference in the %NOS-dependent vasodilatation from pre- to post-beetroot juice. These data suggest that nitrate supplementation via beetroot juice can reduce MAP and DBP as well as augment NOS-independent vasodilatation to local heating in the cutaneous vasculature of healthy humans. PMID:25554360

  2. Evaporated VOx Thin Films

    NASA Astrophysics Data System (ADS)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  3. Falling film evaporator

    DOEpatents

    Bruns, Lester E.

    1976-01-01

    A falling film evaporator including a vertically oriented pipe heated exteriorly by a steam jacket and interiorly by a finned steam tube, all heating surfaces of the pipe and steam tube being formed of a material wet by water such as stainless steel, and packing within the pipe consisting of Raschig rings formed of a material that is not wet by water such as polyvinylidene fluoride.

  4. Vertical counterflow evaporative cooler

    DOEpatents

    Bourne, Richard C.; Lee, Brian Eric; Callaway, Duncan

    2005-01-25

    An evaporative heat exchanger having parallel plates that define alternating dry and wet passages. A water reservoir is located below the plates and is connected to a water distribution system. Water from the water distribution system flows through the wet passages and wets the surfaces of the plates that form the wet passages. Air flows through the dry passages, mixes with air below the plates, and flows into the wet passages before exiting through the top of the wet passages.

  5. Ball feeder for replenishing evaporator feed

    DOEpatents

    Felde, D.K.; McKoon, R.H.

    1993-03-23

    Vapor source material such as uranium, which is to be dropped into a melt in an evaporator, is made into many balls of identical diameters and placed inside a container. An elongated sloping pipe is connected to the container and leads to the evaporator such that these balls can travel sequentially therealong by gravity. A metering valve in this pipe for passing these balls one at a time is opened in response to a signal when it is ascertained by a detector that there is a ball ready to be passed. A gate in the pipe near the evaporator momentarily stops the motion of the traveling ball and is then opened to allow the ball drop into the melt at a reduced speed.

  6. Ball feeder for replenishing evaporator feed

    DOEpatents

    Felde, David K.; McKoon, Robert H.

    1993-01-01

    Vapor source material such as uranium, which is to be dropped into a melt in an evaporator, is made into many balls of identical diameters and placed inside a container. An elongated sloping pipe is connected to the container and leads to the evaporator such that these balls can travel sequentially therealong by gravity. A metering valve in this pipe for passing these balls one at a time is opened in response to a signal when it is ascertained by a detector that there is a ball ready to be passed. A gate in the pipe near the evaporator momentarily stops the motion of the traveling ball and is then opened to allow the ball drop into the melt at a reduced speed.

  7. Ablation of the N-type calcium channel ameliorates diabetic nephropathy with improved glycemic control and reduced blood pressure

    PubMed Central

    Ohno, Shoko; Yokoi, Hideki; Mori, Kiyoshi; Kasahara, Masato; Kuwahara, Koichiro; Fujikura, Junji; Naito, Masaki; Kuwabara, Takashige; Imamaki, Hirotaka; Ishii, Akira; Saleem, Moin A.; Numata, Tomohiro; Mori, Yasuo; Nakao, Kazuwa; Yanagita, Motoko; Mukoyama, Masashi

    2016-01-01

    Pharmacological blockade of the N- and L-type calcium channel lessens renal injury in kidney disease patients. The significance of specific blockade of α1 subunit of N-type calcium channel, Cav2.2, in diabetic nephropathy, however, remains to be clarified. To examine functional roles, we mated Cav2.2−/− mice with db/db (diabetic) mice on the C57BLKS background. Cav2.2 was localized in glomeruli including podocytes and in distal tubular cells. Diabetic Cav2.2−/− mice significantly reduced urinary albumin excretion, glomerular hyperfiltration, blood glucose levels, histological deterioration and systolic blood pressure (SBP) with decreased urinary catecholamine compared to diabetic Cav2.2+/+ mice. Interestingly, diabetic heterozygous Cav2.2+/− mice also decreased albuminuria, although they exhibited comparable systolic blood pressure, sympathetic nerve activity and creatinine clearance to diabetic Cav2.2+/+ mice. Consistently, diabetic mice with cilnidipine, an N-/L-type calcium channel blocker, showed a reduction in albuminuria and improvement of glomerular changes compared to diabetic mice with nitrendipine. In cultured podocytes, depolarization-dependent calcium responses were decreased by ω-conotoxin, a Cav2.2-specific inhibitor. Furthermore, reduction of nephrin by transforming growth factor-β (TGF-β) in podocytes was abolished with ω-conotoxin, cilnidipine or mitogen-activated protein kinase kinase inhibitor. In conclusion, Cav2.2 inhibition exerts renoprotective effects against the progression of diabetic nephropathy, partly by protecting podocytes. PMID:27273361

  8. Antiatherosclerotic effects of licorice extract supplementation on hypercholesterolemic patients: decreased CIMT, reduced plasma lipid levels, and decreased blood pressure

    PubMed Central

    Fogelman, Yacov; Gaitini, Diana; Carmeli, Eli

    2016-01-01

    Background Ethanolic extract of licorice root has been shown to reduce low-density lipoprotein (LDL) oxidation in atherosclerotic mice and in both hypercholesterolemic and normal lipidemic humans. Objective This study examined the effect of licorice-root extract on carotid intima-media thickness (CIMT) in individuals with hypercholesterolemia. Design Individuals with hypercholesterolemia (total cholesterol ≥6.18 mmol/L [240 mg/dL]) and without significant stenosis were randomly allocated to two groups: an experimental group that consumed 0.2 g/day of ethanolic extract of licorice root for 12 months, and a control group that received a placebo. Results Of 110 eligible participants, 94 (41–80 years old) completed the study. A significant CIMT decrease from 0.92±0.25 mm to 0.84±0.21 mm was observed in the experimental group compared with an increase from 0.85±0.17 mm to 0.88±0.19 mm in the control group. Mean plasma total cholesterol levels and LDL cholesterol decreased, at the range baseline to 1 year, from 284±32 mg/dl to 262±25 mg/dl and from 183±8.5 mg/dl to 174±9.1 mg/dl, respectively, for the experimental group (p<0.001) and from 291±35 to 289±31 mg/dl and from 177.6±10.7 to 179.3±9.6 (p=0.08), respectively, for the control group. Mean high-density lipoprotein (HDL) did not change significantly in either group. In the experimental group, systolic blood pressure decreased from 138±12 mmHg to 125±13 mmHg after 1 year (p=0.01) and increased from 136±15 mmHg to 137±13 mmHg in the control group. Diastolic blood pressure decreased from 92±9 mmHg to 84±10 mmHg (p=0.01) in the experimental group and increased from 89±11 mmHg to 90±8 mmHg in the control group. Conclusion Following 1 year of licorice consumption, mean CIMT, total cholesterol, LDL levels, and blood pressure were decreased. This suggests that licorice may attenuate the development of atherosclerosis and of related cardiovascular diseases. PMID:27113136

  9. Adiabatic burst evaporation from bicontinuous nanoporous membranes

    PubMed Central

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk

    2015-01-01

    Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

  10. Liquid alkali metals - Equation of state and reduced-pressure, bulk-modulus, sound-velocity, and specific-heat functions

    NASA Technical Reports Server (NTRS)

    Schlosser, Herbert; Ferrante, John

    1989-01-01

    The previous work of Schlosser and Ferrante (1988) on universality in solids is extended to the study of liquid metals. As in the case of solids, to a good approximation, in the absence of phase transitions, plots of the logarithm of the reduced-pressure function H, of the reduced-isothermal-bulk-modulus function b, and of the reduced-sound-velocity function v are all linear in 1-X. Finally, it is demonstrated that ln(Cp/C/v) is also linear in 1-X, where X = (V/V/0/)exp 1/3), and V(0) is the volume at zero pressure.

  11. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    SciTech Connect

    Wyrzykowski, Mateusz; Trtik, Pavel; Münch, Beat; Weiss, Jason; Vontobel, Peter; Lura, Pietro

    2015-07-15

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.

  12. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

  13. Polyphenol-rich juices reduce blood pressure measures in a randomised controlled trial in high normal and hypertensive volunteers.

    PubMed

    Tjelle, Torunn Elisabeth; Holtung, Linda; Bøhn, Siv Kjølsrud; Aaby, Kjersti; Thoresen, Magne; Wiik, Siv Åshild; Paur, Ingvild; Karlsen, Anette Solli; Retterstøl, Kjetil; Iversen, Per Ole; Blomhoff, Rune

    2015-10-14

    Intake of fruits and berries may lower blood pressure (BP), most probably due to the high content of polyphenols. In the present study, we tested whether consumption of two polyphenol-rich juices could lower BP. In a randomised, double-blinded, placebo-controlled trial of 12 weeks, 134 healthy individuals, aged 50-70 years, with high normal range BP (130/85-139/89 mmHg, seventy-two subjects) or stage 1-2 hypertension (140/90-179/109 mmHg, sixty-two subjects), were included. They consumed 500 ml/d of one of either (1) a commercially available polyphenol-rich juice based on red grapes, cherries, chokeberries and bilberries; (2) a juice similar to (1) but enriched with polyphenol-rich extracts from blackcurrant press-residue or (3) a placebo juice (polyphenol contents 245·5, 305·2 and 76 mg/100 g, respectively). Resting BP was measured three times, with a 1 min interval, at baseline and after 6 and 12 weeks of intervention. Systolic BP significantly reduced over time (6 and 12 weeks, respectively) in the pooled juice group compared with the placebo group in the first of the three measurements, both for the whole study group (6·9 and 3·4 mmHg; P= 0·01) and even more pronounced in the hypertensive subjects when analysed separately (7·3 and 6·8 mmHg; P= 0·04). The variation in the BP measurements was significantly reduced in the pooled juice group compared with the placebo group (1·4 and 1·7 mmHg; P= 0·03). In conclusion, the present findings suggest that polyphenol-rich berry juice may contribute to a BP- and BP variability lowering effect, being more pronounced in hypertensive than in normotensive subjects. PMID:26227795

  14. Efficacy of a brief multifactorial adherence-based intervention in reducing blood pressure: a randomized clinical trial

    PubMed Central

    Leiva, Alfonso; Aguiló, Antonio; Fajó-Pascual, Marta; Moreno, Lucia; Martín, Mª Carmen; Garcia, Elena Marina; Duro, Rosa Elena; Serra, Francisca; Dagosto, Pilar; Iglesias-Iglesias, Ana Aurelia; Company, Rosa Maria; Yañez, Aina; Llobera, Joan

    2014-01-01

    Background Lowering blood pressure (BP) by antihypertensive (AHT) drugs reduces the risks of cardiovascular events, stroke, and total mortality. However, poor adherence to AHT medications reduces their effectiveness and increases the risk of adverse events. Objective To evaluate the effectiveness of a multifactorial adherence-based intervention in a primary care setting in lowering BP. Methods/design Multicenter parallel randomized controlled trial. Thirty two nurses in 28 primary care centers of three Spanish regions. Patients aged 18–80 years, taking AHT drugs with uncontrolled BP (n=221) were randomized to a control group (usual care) or a multifactorial adherence-based intervention including nurse-led motivational interviews, pill reminders, family support, BP self-recording, and simplification of the dosing regimen by a pharmacist. Main outcome measures The primary outcome was 12-month blinded measure of systolic BP (mean of three measurements). The secondary outcomes were 12-month diastolic BP and proportion of patients with adequately controlled BP. Results One hundred and fourteen patients were allocated to the intervention group and 109 to the control group. At 12 months, 212 (89%) participants completed the study. The systolic BP in the intervention group was 151.3 versus 153.7 in the control group (P=0.294). The diastolic BP did not differ between groups (83.4 versus 83.6). Of the patients in the control group, 9.2% achieved BP control versus a 15.8% in the intervention group. The relative risk for achieving BP control was 1.72 (95% confidence interval: 0.83–3.56). Conclusion A multifactorial intervention based on improving adherence in patients with uncontrolled hypertension failed to find evidence of effectiveness in lowering systolic BP. Trial registration ISRCTN21229328. PMID:25525344

  15. Pulmonary Artery Denervation Reduces Pulmonary Artery Pressure and Induces Histological Changes in an Acute Porcine Model of Pulmonary Hypertension

    PubMed Central

    Arnold, Nadine D.; Chang, William; Watson, Oliver; Swift, Andrew J.; Condliffe, Robin; Elliot, Charlie A.; Kiely, David G.; Suvarna, S. Kim; Gunn, Julian; Lawrie, Allan

    2015-01-01

    Background— Pulmonary arterial hypertension is a devastating disease with high morbidity and mortality and limited treatment options. Recent studies have shown that pulmonary artery denervation improves pulmonary hemodynamics in an experimental model and in an early clinical trial. We aimed to evaluate the nerve distribution around the pulmonary artery, to determine the effect of radiofrequency pulmonary artery denervation on acute pulmonary hypertension induced by vasoconstriction, and to demonstrate denervation of the pulmonary artery at a histological level. Methods and Results— Histological evaluation identified a circumferential distribution of nerves around the proximal pulmonary arteries. Nerves were smaller in diameter, greater in number, and located in closer proximity to the luminal aspect of the pulmonary arterial wall beyond the pulmonary artery bifurcation. To determine the effect of pulmonary arterial denervation acute pulmonary hypertension was induced in 8 pigs by intravenous infusion of thromboxane A2 analogue. Animals were assigned to either pulmonary artery denervation, using a prototype radiofrequency catheter and generator, or a sham procedure. Pulmonary artery denervation resulted in reduced mean pulmonary artery pressure and pulmonary vascular resistance and increased cardiac output. Ablation lesions on the luminal surface of the pulmonary artery were accompanied by histological and biochemical alteration in adventitial nerves and correlated with improved hemodynamic parameters. Conclusions— Pulmonary artery denervation offers the possibility of a new treatment option for patients with pulmonary arterial hypertension. Further work is required to determine the long-term efficacy and safety. PMID:26553697

  16. Ultrasound increases nanoparticle delivery by reducing intratumoral pressure and increasing transport in epithelial and epithelial-mesenchymal transition tumors

    PubMed Central

    Watson, Katherine D.; Lai, Chun-Yen; Qin, Shengping; Kruse, Dustin E.; Lin, Yueh-Chen; Seo, Jai Woong; Cardiff, Robert D.; Mahakian, Lisa M.; Beegle, Julie; Ingham, Elizabeth S.; Curry, Fitz-Roy; Reed, Rolf K.; Ferrara, Katherine W.

    2012-01-01

    Acquisition of the epithelial-mesenchymal transition (EMT) tumor phenotype is associated with impaired chemotherapeutic delivery and a poor prognosis. In this study, we investigated the application of therapeutic ultrasound methods available in the clinic to increase nanotherapeutic particle accumulation in epithelial and EMT tumors by labeling particles with a positron emission tomography tracer. Epithelial tumors were highly vascularized with tight cell-cell junctions, compared to EMT tumors where cells displayed an irregular, elongated shape with loosened cell-cell adhesions and a reduction in E-cadherin and cytokeratins 8/18 and 19. Without ultrasound, the accumulation of liposomal nanoparticles administered to tumors in vivo was ~1.5 times greater in epithelial tumors than EMT tumors. When ultrasound was applied, both nanoaccumulation and apparent tumor permeability were increased in both settings. Notably, ultrasound effects differed with thermal and mechanical indices, such that increasing the thermal ultrasound dose increased nanoaccumulation in EMT tumors. Taken together, our results illustrate how ultrasound can be used to enhance nanoparticle accumulation in tumors by reducing their intratumoral pressure and increasing their vascular permeability. PMID:22282664

  17. Simultaneous irrigation and negative pressure wound therapy enhances wound healing and reduces wound bioburden in a porcine model.

    PubMed

    Davis, Kathryn; Bills, Jessica; Barker, Jenny; Kim, Paul; Lavery, Lawrence

    2013-01-01

    Infected foot wounds are one of the most common reasons for hospitalization and amputation among persons with diabetes. The objective of the study was to investigate a new wound therapy system that employs negative pressure wound therapy (NPWT) with simultaneous irrigation therapy. For this study, we used a porcine model with full-thickness excisional wounds, inoculated with Pseudomonas aeruginosa. Wounds were treated for 21 days of therapy with either NPWT, NPWT with simultaneous irrigation therapy using normal saline or polyhexanide biguanide (PHMB) at low or high flow rates, or control. Data show that NPWT with either irrigation condition improved wound healing rates over control-treated wounds, yet did not differ from NPWT alone. NPWT improved bioburden over control-treated wounds. NPWT with simultaneous irrigation further reduced bioburden over control and NPWT-treated wounds; however, flow rate did not affect these outcomes. Together, these data show that NPWT with simultaneous irrigation therapy with either normal saline or PHMB has a positive effect on bioburden in a porcine model, which may translate clinically to improved wound healing outcomes. PMID:24134060

  18. Stabilization of polymer electrolyte fuel cell voltage with reduced-order Lyapunov exponent feedback and corrective pressure perturbations

    NASA Astrophysics Data System (ADS)

    Burkholder, Michael B.; Litster, Shawn

    2015-02-01

    Polymer electrolyte fuel cell (PEFC) system efficiency can be decreased by instabilities resulting from the accumulation of water in the cathode as well as by excessive air delivery parasitic loads used to prevent liquid water accumulation. In this work, we present a new instability detection diagnostic tailored for the nonlinear and chaotic dynamics of PEFC operation with multi-phase flow in the gas channels. The instability statistic, the Lyapunov exponent of the reduced-order voltage return map, λ, is a measure of the exponential rate of divergence in the dynamic voltage signal measured from the fuel cell. A key advantage of this statistic for embedded control is that it is a self-referencing measure of the system stability for feedback and is not based on an a priori performance threshold. Our experiments demonstrate that the Lyapunov exponent statistic provides a warning typically 100 s in advance of significant power loss. Using this statistic as a control diagnostic, a new control scheme that detects PEFC instability in real time and mitigates it with pressure perturbations was applied experimentally to several fuel cell systems, including one that simulates stack operation. Our control scheme resulted in increased PEFC power, decreased cathode flooding leading to a lower parasitic load for air delivery, and stable PEFC performance.

  19. Dietary saffron reduced the blood pressure and prevented remodeling of the aorta in L-NAME-induced hypertensive rats

    PubMed Central

    Nasiri, Zohreh; Sameni, Hamid Reza; Vakili, Abedin; Jarrahi, Morteza; Khorasani, Mahdi Zahedi

    2015-01-01

    Objective(s): The aim of this study was to investigate the effects of nutritional saffron (Crocus sativus L.) stigma hydroalcoholic extract on blood pressure (BP) and histology of the aorta in normotensive and hypertensive rats. Materials and Methods: Saffron (200 mg/kg/day) was given orally for 5 weeks to normotensive and hypertensive rats. Hypertension was induced by NG-nitro-L-arginine methyl ester (L-NAME; 40 mg/kg/day) administration in drinking water, and BP was measured weekly. Histological examination of the thoracic aorta included staining with hematoxylin and eosin, orcein, and periodic acid Schiff methods. Results: Saffron had no effect on normotensive rats, but on hypertensive rats, prevented BP elevation form the third week of treatment (P<0.001). Furthermore, saffron reduced the cross-section area, media thickness, and elastic lamellae number of the aorta (P<0.05). Conclusion: Nutritional saffron prevented BP increases and remodeling of the aorta in hypertensive rats. It may be useful for preventing hypertension. PMID:26949504

  20. The effect of winter drought on evaporation from a high-elevation wetland

    NASA Astrophysics Data System (ADS)

    Blanken, Peter D.

    2014-07-01

    The surface energy balance of a high-elevation groundwater-fed wetland (High Creek Fen) in central Colorado was measured from 9 June 2000 through 18 January 2005. In agreement with observations and predictions for decreased winter snow cover in the region, the low snow cover in 2001-2002 allowed for an examination of the impact of winter drought on the wetland. During years with an average snowpack, summer evaporation far exceeded precipitation. Despite near-normal summer precipitation following a winter drought, the summertime surface energy balance was affected with decreased latent heat fluxes and increased sensible heat fluxes. The leaf area index and the fraction of photosynthetic radiation absorbed were reduced following the winter drought. A shift in the primary controls on evaporation occurred as the surface's response to vapor pressure deficits and soil moisture increased following the winter drought. The earlier snowmelt coupled with earlier increase in soil temperature and moisture following winter drought did not increase evaporation, since vegetation was not yet developed, and evaporation from soil water was low during the early spring period.

  1. Effect of Variable Gravity on Evaporation of Binary Fluids in a Capillary Pore Evaporator

    NASA Technical Reports Server (NTRS)

    Girgis, Morris M.; Matta, Nabil S.; Kolli, Kiran; Brown, Leon; Bain, James, Jr.; McGown, Juantonio

    1996-01-01

    The research project focuses on experimental investigation of the capillary-pumped evaporative heat transfer phenomenon. The objective is to examine whether the heat transfer and stability of a heated meniscus in a capillary pore can be enhanced by adding trace amounts of a non-volatile solute to a solvent and to understand the changes that occur. The experimental setup consists of a single pore evaporator connected to a reservoir which supplies liquid to the evaporator. In addition to the experiments of capillary-pumped evaporation, a parallel experimental study has been conducted to systematically investigate the effects of gravity as well as the effects of bulk composition on the heat transfer characteristics of evaporating binary thin films near the contact line region along an inclined heated surface. To investigate the buoyancy effects on evaporation along an inclined heated surface, the angle of inclination from a horizontal plane was varied fro 15 C to 90 C. An optimum concentration between 0.5% and 1% decane in pentane/decane solutions has been demonstrated at different angles of inclination. Improved heat transfer was found for the geometry with the smallest angle of inclination of 15 degrees. In addition, flow visualization has revealed that at low inclination angles effective heat transfer takes place primarily due to an extension of the thin film near the contact line. At these low inclination angles, the optimum concentration is associated with enhanced wetting characteristics and reduced thermocapillary stresses along the interface.

  2. Effect of Atmospheric Pressure on Wet Bulb Depression

    NASA Astrophysics Data System (ADS)

    Wheeler, Raymond; Stasiak, Michael; Lawson, Jamie; Wehkamp, Cara Ann; Dixon, Mike

    Future space exploration missions will likely operate at pressures less than 1 atm ( 100 kPa) to reduce gas leakage and structural mass, and facilitate rapid EVAs. Understanding environmental monitoring, control, and physiological responses to reduced pressures will be required to assure mission success. Wet / dry bulb psychrometers are useful devices for monitoring humidity and provide insights into cooling phenomena for wet, evaporating surfaces. To study the effects of pressure on psychrometers we conducted a series of tests in a hypobaric chamber. Chamber RH monitoring and control were based on capacitance type devices, which previous testing and manufacturer's specifications have shown to be unaffected by pressure. Test data were gathered using an Enercorp model HT-WD-A psychrometer with matched platinum RTD temperature probes positioned side-by-side with a dew point (chilled mirror) device and two capacitance RH sensors. The chamber was kept dark and measurements were taken at three RHs (30, 50, and 70) and four pressures (10, 25, 50, and 97 kPa). Results showed an increase in wet bulb depression (i.e., a drop in wet bulb temperature) for a given RH as the pressure decreased, with the largest changes occurring as pressure dropped from 25 and 10 kPa. At a dry bulb temperature of 25 C, the normal wet bulb temperature for 30 RH and 97 kPa is 15 C, but this dropped to 8 C at 10 kPa. These observations are consistent with previous reports of increased evaporation rates at reduced pressure and match recently published psychrometric models for different pressures. The results suggest that psychrometers need direct calibration at the target pressures or that pressure corrected charts are required. Moreover, for a given vapor pressure deficit, any moist surfaces, including transpiring plant leaves, will be cooler at lower pressures due to the increased evaporation rates.

  3. Method of evaporation

    NASA Technical Reports Server (NTRS)

    Dufresne, Eugene R.

    1987-01-01

    Liquids, such as juices, milk, molten metal and the like are concentrated by forming uniformly-sized, small droplets in a precision droplet forming assembly and deploying the droplets in free fall downwardly as a central column within an evacuated column with cool walls. A portion of the solvent evaporates. The vapor flows to the wall, condenses, and usually flows down the wall as a film to condensate collector and drain. The vertical column of freely falling droplets enters the splash guard. The condensate can be collected, sent to other towers or recycled.

  4. DWPF Recycle Evaporator Shielded Cells Testing

    SciTech Connect

    Fellinger, T. L.; Herman, D. T.; Stone, M.E

    2005-07-01

    Testing was performed to determine the feasibility and processing characteristics of evaporation of actual Defense Waste Processing Facility (DWPF) recycle material. Samples of the Off Gas Condensate Tank (OGCT) and Slurry Mix Evaporator Condensate Tank (SMECT) were transferred from DWPF to the Savannah River National Lab (SRNL) Shielded Cells and blended with De-Ionized (DI) water and a small amount of Slurry Mix Evaporator (SME) product. A total of 3000 mL of this feed was concentrated to approximately 90 mL during a semi-batch evaporation test of approximately 17 hours. One interruption occurred during the run when the feed tube developed a split and was replaced. Samples of the resulting condensate and concentrate were collected and analyzed. The resulting analysis of the condensate was compared to the Waste Acceptance Criteria (WAC) limits for the F/H Effluent Treatment Plant (ETP). Results from the test were compared to previous testing using simulants and OLI modeling. Conclusions from this work included the following: (1) The evaporation of DWPF recycle to achieve a 30X concentration factor was successfully demonstrated. The feed blend of OGCT and SMECT material was concentrated from 3000 mL to approximately 90 mL during testing, a concentration of approximately 33X. (2) Foaming was observed during the run. Dow Corning 2210 antifoam was added seven times throughout the run at 100 parts per million (ppm) per addition. The addition of this antifoam was very effective in reducing the foam level, but the impact diminished over time and additional antifoam was required every 2 to 3 hours during the run. (3) No scale or solids formed on the evaporator vessel, but splatter was observed in the headspace of the evaporator vessel. No scaling formed on the stainless steel thermocouple. (4) The majority of the analytes met the F/H ETP WAC. However, the detection limits for selected species (Sr-90, Pu-238, Pu-240, Am-243, and Cm-244) exceeded the ETP WAC limits. (5) I

  5. Evaluation of simplified evaporation duct refractivity models for inversion problems

    NASA Astrophysics Data System (ADS)

    Saeger, J. T.; Grimes, N. G.; Rickard, H. E.; Hackett, E. E.

    2015-10-01

    To assess a radar system's instantaneous performance on any given day, detailed knowledge of the meteorological conditions is required due to the dependency of atmospheric refractivity on thermodynamic properties such as temperature, water vapor, and pressure. Because of the significant challenges involved in obtaining these data, recent efforts have focused on development of methods to obtain the refractivity structure inversely using radar measurements and radar wave propagation models. Such inversion techniques generally use simplified refractivity models in order to reduce the parameter space of the solution. Here the accuracy of three simple refractivity models is examined for the case of an evaporation duct. The models utilize the basic log linear shape classically associated with evaporation ducts, but each model depends on various parameters that affect different aspects of the profile, such as its shape and duct height. The model parameters are optimized using radiosonde data, and their performance is compared to these atmospheric measurements. The optimized models and data are also used to predict propagation using a parabolic equation code with the refractivity prescribed by the models and measured data, and the resulting propagation patterns are compared. The results of this study suggest that the best log linear model formulation for an inversion problem would be a two-layer model that contains at least three parameters: duct height, duct curvature, and mixed layer slope. This functional form permits a reasonably accurate fit to atmospheric measurements as well as embodies key features of the profile required for correct propagation prediction with as few parameters as possible.

  6. Sleep Apnea Related Risk of Motor Vehicle Accidents is Reduced by Continuous Positive Airway Pressure: Swedish Traffic Accident Registry Data

    PubMed Central

    Karimi, Mahssa; Hedner, Jan; Häbel, Henrike; Nerman, Olle; Grote, Ludger

    2015-01-01

    Study Objectives: Obstructive sleep apnea (OSA) is associated with an increased risk of motor vehicle accidents (MVAs). The rate of MVAs in patients suspected of having OSA was determined and the effect of continuous positive airway pressure (CPAP) was investigated. Design: MVA rate in patients referred for OSA was compared to the rate in the general population using data from the Swedish Traffic Accident Registry (STRADA), stratified for age and calendar year. The risk factors for MVAs, using demographic and polygraphy data, and MVA rate before and after CPAP were evaluated in the patient group. Setting: Clinical sleep laboratory and population based control (n = 635,786). Patients: There were 1,478 patients, male sex 70.4%, mean age 53.6 (12.8) y. Interventions: CPAP. Measurements and Results: The number of accidents (n = 74) among patients was compared with the expected number (n = 30) from a control population (STRADA). An increased MVA risk ratio of 2.45 was found among patients compared with controls (P < 0.001). Estimated excess accident risk was most prominent in the elderly patients (65–80 y, seven versus two MVAs). In patients, driving distance (km/y), EDS (Epworth Sleepiness score ≥ 16), short habitual sleep time (≤ 5 h/night), and use of hypnotics were associated with increased MVA risk (odds ratios 1.2, 2.1, 2.7 and 2.1, all P ≤ 0.03). CPAP use ≥ 4 h/night was associated with a reduction of MVA incidence (7.6 to 2.5 accidents/1,000 drivers/y). Conclusions: The motor vehicle accident risk in this large cohort of unselected patients with obstructive sleep apnea suggests a need for accurate tools to identify individuals at risk. Sleep apnea severity (e.g., apnea-hypopnea index) failed to identify patients at risk. Citation: Karimi M, Hedner J, Häbel H, Nerman O, Grote L. Sleep apnea related risk of motor vehicle accidents is reduced by continuous positive airway pressure: Swedish traffic accident registry data. SLEEP 2015;38(3):341–349. PMID

  7. 8. August, 1971. SECOND FLOOR LOOKING NW. EVAPORATOR UNITS USED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. August, 1971. SECOND FLOOR LOOKING NW. EVAPORATOR UNITS USED IN SEQUENCE TO REDUCE OR CONCENTRATE BEET JUICE. - Utah Sugar Company, Garland Beet Sugar Refinery, Factory Street, Garland, Box Elder County, UT

  8. Evaporation control research, 1955-58

    USGS Publications Warehouse

    Cruse, Robert R.; Harbeck, Guy Earl

    1960-01-01

    One hundred fifty-two compounds and compositions of matter were screened as potential evaporation retardants. The homologous straight-chain fatty alkanols are considered the best materials for retardants. Several methods of application of the alkanols to the reservoir surface were investigated. Although wick-type drippers for the application of liquids and cage rafts for the application of solids appear to be the most promising methods from an economic standpoint, both methods have serious disadvantages. Considerable study was given to reducing biochemical oxidation of the evaporation retardants. Copper in several forms was found adequate as a bacteriostatic agent but posed a potential hazard because of its toxicity. Many other bactericides that were tested were also toxic. Two sets of large-scale field tests have been completed and several others are still in progress. On the larger reservoirs, the reduction of evaporation was not more than 20 percent under the prevailing conditions and the application procedure used. Three major practical problems remain; namely, the effects and action of wind on the monofilm, the effects of biochemical oxidation, and the most effective method of application. Fundamental problems remaining include the effects of various impurities, and the composition of the best evaporation retardant; the long-range effects of monofilms on the limnology of a reservoir, including the transfer of oxygen and carbon dioxide; toxicological aspects of all components of any evaporation-retardant composition, plus toxicology of any composition chosen for large-scale use; and further studies of the calorimetry and thermodynamics involved in the mechanism of evaporation and its reduction by a monofilm.

  9. Simulations of Evaporating Multicomponent Fuel Drops

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Le Clercq, Patrick

    2005-01-01

    A paper presents additional information on the subject matter of Model of Mixing Layer With Multicomponent Evaporating Drops (NPO-30505), NASA Tech Briefs, Vol. 28, No. 3 (March 2004), page 55. To recapitulate: A mathematical model of a three-dimensional mixing layer laden with evaporating fuel drops composed of many chemical species has been derived. The model is used to perform direct numerical simulations in continuing studies directed toward understanding the behaviors of sprays of liquid petroleum fuels in furnaces, industrial combustors, and engines. The model includes governing equations formulated in an Eulerian and a Lagrangian reference frame for the gas and drops, respectively, and incorporates a concept of continuous thermodynamics, according to which the chemical composition of a fuel is described by use of a distribution function. In this investigation, the distribution function depends solely on the species molar weight. The present paper reiterates the description of the model and discusses further in-depth analysis of the previous results as well as results of additional numerical simulations assessing the effect of the mass loading. The paper reiterates the conclusions reported in the cited previous article, and states some new conclusions. Some new conclusions are: 1. The slower evaporation and the evaporation/ condensation process for multicomponent-fuel drops resulted in a reduced drop-size polydispersity compared to their single-component counterpart. 2. The inhomogeneity in the spatial distribution of the species in the layer increases with the initial mass loading. 3. As evaporation becomes faster, the assumed invariant form of the molecular- weight distribution during evaporation becomes inaccurate.

  10. Combined Evaporation and Salt Precipitation in Porous Media

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Dragila, M. I.; Nachshon, U.; Or, D.; Shaharani, E.; Grader, A.

    2012-12-01

    The vadose zone pore water contains dissolved salts and minerals; therefore, evaporation results in high rates of salt accumulation that may change the physical and chemical properties of the porous media. Here, a series of experiments, together with a mathematical model, are presented to shed new light on these processes. Experiments included: (1) long-term column evaporation experiments to quantify changes in evaporation rates due to salt precipitation; (2) CT scans of evaporated porous media samples saturated with salt solutions, to observe salt precipitation from micro to macro scales; and (3) Infrared thermography analysis to quantify evaporation rates from porous media surfaces for homogeneous and heterogeneous conditions and constant water table, in the presence of salt precipitation. As expected, the majority of salt crystallization occurs in the upper parts of the matrix, near the evaporation front. For heterogeneous porous matrices, salt precipitation will occur mainly in the fine pore regions as preferential evaporation takes place in these locations. In addition, it was found that the precipitated NaCl salt crust diffusion coefficient for water vapor is one to two orders of magnitude lower than the vapor diffusion coefficient in free air, depending on environmental conditions and salt crystallization rates. Three new stages of evaporation were defined for saline solutions: SS1, SS2 and SS3. SS1 exhibits a low and gradual decrease in the evaporation rate due to osmotic pressure. During SS2, the evaporation rate falls progressively due to salt precipitation; SS3 is characterized by a constant low evaporation rate and determined by the diffusion rate of water vapor through the precipitated salt layer. Even though phenomenologically similar to the classical evaporation stages of pure water, these stages correspond to different mechanisms and the transition between stages can occur regardless the hydraulic conditions. As well, it was shown that matrix

  11. Thermocapillary effects on steadily evaporating contact line: A perturbative local analysis

    NASA Astrophysics Data System (ADS)

    Benselama, Adel M.; Harmand, Souad; Sefiane, Khellil

    2012-07-01

    The evaporation process taking place close to the three-phase contact line is considered and studied theoretically using a linear stability analysis approach. A domain perturbation method, taking into consideration thermocapillary effects and surface forces, is used to develop the higher-order solution in terms of series expansion about lubrication condition. A closed-form solution is found for the film thickness, the pressure jump across the liquid-vapor interface and the evaporative flux in the vicinity of the contact line. The key novelty in this work is considering thermocapillary instability for very thin films (˜10 nm) accounting for surface forces. For (quasi-) flat-very-thin films, the analysis shows no instability, which is consistent with general knowledge in this field. However, for films extending from a meniscus, as encountered in wetting configurations, it is found that the competition between London-van der Waals, capillary, and thermocapillary forces leads to contact line instability and behavior revealed for the first time. According to the sign of the Marangoni number, the instability can enhance (if positive) or reduce (if negative) the evaporation rate by widening out or narrowing, respectively, the contact region and, in both cases, significantly modifies the vortical structure of the flow. If the Marangoni number is positive, the film interface close to the contact line can exhibit corrugations. The occurrence of these latter is discriminated, in addition to the Marangoni number, by the value of three operating parameters, namely the film aspect ratio, the ratio of the film diffusive thermal resistance to evaporative heat transfer resistance, and the ratio of capillary pressure to disjoining pressure. By modifying the physical and operating parameters, it is also shown that the system can be optimized in order to suppress these corrugations.

  12. A TRIAL OF TWO STRATEGIES TO REDUCE NOCTURNAL BLOOD PRESSURE IN AFRICAN AMERICANS WITH CHRONIC KIDNEY DISEASE

    PubMed Central

    Rahman, Mahboob; Greene, Tom; Phillips, Robert A; Agodoa, Lawrence Y; Bakris, George L; Charleston, Jeanne; Contreras, Gabriel; Gabbai, Francis; Hiremath, Leena; Jamerson, Kenneth; Kendrick, Cynthia; Kusek, John W; Lash, James P; Lea, Janice; Miller, Edgar R; Rostand, Stephen; Toto, Robert; Wang, Xulei; Wright, Jackson T; Appel, Lawrence J

    2012-01-01

    The objective of our study was to determine the effects of two antihypertensive drug dose schedules (‘PM dose’ and ‘Add on dose’) on nocturnal blood pressure (BP) in comparison to usual therapy (‘AM dose’) in African Americans with hypertensive chronic kidney disease (CKD) and controlled office BP. In a three period, cross-over trial, former participants of the African American Study of Kidney Disease were assigned to receive the following three regimens, each lasting 6 weeks, presented in random order: AM dose (once daily antihypertensive medications taken in the morning), PM dose (once daily antihypertensives taken at bedtime) and ‘Add on dose’ (once daily antihypertensives taken in the morning and an additional antihypertensive medication before bedtime [diltiazem 60–120 mg, hydralazine 25 mg, or additional ramipril 5 mg]). Ambulatory BP monitoring was performed at the end of each period. The primary outcome was nocturnal systolic BP. Mean age of the study population (n=147) was 65.4 years, 64% were male, mean estimated GFR was 44.9 ml/min/1.73 m2. At the end of each period, mean (SE) nocturnal systolic BP was 125.6 (1.2) mm Hg in the AM dose, 123.9 (1.2) mm Hg in the PM dose, and 123.5(1.2) mm Hg in the Add-on dose. None of the pairwise differences in nocturnal, 24-hour and daytime systolic BP were statistically significant. Among African Americans with hypertensive CKD, neither PM (bedtime) dosing of once daily antihypertensive nor the addition of drugs taken at bedtime significantly reduced nocturnal BP compared to morning dosing of anti-hypertensive medications. PMID:23172931

  13. Loss of efficiency of polymeric drag reducers induced by high Reynolds number flows in tubes with imposed pressure

    NASA Astrophysics Data System (ADS)

    Soares, Edson J.; Sandoval, Gustavo A. B.; Silveira, Lucas; Pereira, Anselmo S.; Trevelin, Renata; Thomaz, Fabricio

    2015-12-01

    This paper studies the loss of efficiency of polymeric drag reducers induced by high Reynolds number flows in tubes. The overall pressure was fixed and the apparatus was built so as to minimize the polymer degradation. We used three kinds of polymers: two flexible and one rigid. We conducted our tests to take into account the drag reduction (DR) for a wide range of concentrations of each polymer. The main results are displayed for the DR as a function of the number of passes through the apparatus. The mechanism of the loss of efficiency for the Xanthan Gum (XG) solutions (the rigid one) seems to be completely different from that observed for Poly (ethylene oxide) (PEO) and Polyacrylamide (PAM) (the flexible materials). While the PEO and PAM mechanically degrade by the action of the turbulent flow, the XG seems to remain intact, even after many passes through the pipe flow apparatus. From the practical point of view, it is worth noting that the PAM solutions are clearly more efficient than the PEO and XG. Another practical point that deserves attention is concerned with the asymptotic drag reduction found for XG. Although its maximum DR was significantly smaller than that found for PEO, the final value for both polymers were quite the same, which is obviously related to the intensified mechanical molecule scission in the PEO solutions. Our results for the relative drag reduction (the current value of DR divided by its maximum obtained at the first pass) was quite well fitted by the decay function proposed in our previous paper [A. S. Pereira and E. J. Soares, "Polymer degradation of dilute solutions in turbulent drag reducing flows in a cylindrical double gap rheometer device," J. Non-Newtonian Fluid Mech. 179, 9-22 (2012)], in which a rotating apparatus was used. This strongly suggests that the physical mechanism that governs the degradation phenomenon is independent of the geometry. We also used a degradation model for PEO proposed by Vonlanthen and Monkewitz

  14. Reservoir evaporation in Texas, USA

    NASA Astrophysics Data System (ADS)

    Wurbs, Ralph A.; Ayala, Rolando A.

    2014-03-01

    The role of reservoir surface evaporation in river/reservoir water budgets and water management is explored using a modeling system that combines historical natural hydrology with current conditions of water resources development and management. The long-term mean evaporation from the 3415 reservoirs in the Texas water rights permit system is estimated to be 7.53 billion m3/year, which is equivalent to 61% of total agricultural or 126% of total municipal water use in the state during the year 2010. Evaporation varies with the hydrologic conditions governing reservoir surface areas and evaporation rates. Annual statewide total evaporation volumes associated with exceedance probabilities of 75%, 50%, and 25% are 7.07, 7.47, and 7.95 billion m3/year, respectively. Impacts of evaporation are greatest during extended severe droughts that govern water supply capabilities.

  15. Representative shuttle evaporative heat sink

    NASA Technical Reports Server (NTRS)

    Hixon, C. W.

    1978-01-01

    The design, fabrication, and testing of a representative shuttle evaporative heat sink (RSEHS) system which vaporizes an expendable fluid to provide cooling for the shuttle heat transport fluid loop is reported. The optimized RSEHS minimum weight design meets or exceeds the shuttle flash evaporator system requirements. A cold trap which cryo-pumps flash evaporator exhaust water from the CSD vacuum chamber test facility to prevent water contamination of the chamber pumping equipment is also described.

  16. Effects of the surroundings and conformerisation of n-dodecane molecules on evaporation/condensation processes

    SciTech Connect

    Gun’ko, Vladimir M.; Nasiri, Rasoul; Sazhin, Sergei S.

    2015-01-21

    The evaporation/condensation coefficient (β) and the evaporation rate (γ) for n-dodecane vs. temperature, gas pressure, gas and liquid density, and solvation effects at a droplet surface are analysed using quantum chemical density functional theory calculations of several ensembles of conformers of n-dodecane molecules in the gas phase (hybrid functional ωB97X-D with the cc-pVTZ and cc-pVDZ basis sets) and in liquid phase (solvation method: SMD/ωB97X-D). It is shown that β depends more strongly on a number of neighbouring molecules interacting with an evaporating molecule at a droplet surface (this number is estimated through changes in the surface Gibbs free energy of solvation) than on pressure in the gas phase or conformerisation and cross-conformerisation of molecules in both phases. Thus, temperature and the surrounding effects at droplet surfaces are the dominant factors affecting the values of β for n-dodecane molecules. These values are shown to be similar (at reduced temperatures T/T{sub c} < 0.8) or slightly larger (at T/T{sub c} > 0.8) than the values of β calculated by the molecular dynamics force fields (MD FF) methods. This endorses the reliability of the previously developed classical approach to estimation of β by the MD FF methods, except at temperatures close to the critical temperature.

  17. Effects of the surroundings and conformerisation of n-dodecane molecules on evaporation/condensation processes.

    PubMed

    Gun'ko, Vladimir M; Nasiri, Rasoul; Sazhin, Sergei S

    2015-01-21

    The evaporation/condensation coefficient (β) and the evaporation rate (γ) for n-dodecane vs. temperature, gas pressure, gas and liquid density, and solvation effects at a droplet surface are analysed using quantum chemical density functional theory calculations of several ensembles of conformers of n-dodecane molecules in the gas phase (hybrid functional ωB97X-D with the cc-pVTZ and cc-pVDZ basis sets) and in liquid phase (solvation method: SMD/ωB97X-D). It is shown that β depends more strongly on a number of neighbouring molecules interacting with an evaporating molecule at a droplet surface (this number is estimated through changes in the surface Gibbs free energy of solvation) than on pressure in the gas phase or conformerisation and cross-conformerisation of molecules in both phases. Thus, temperature and the surrounding effects at droplet surfaces are the dominant factors affecting the values of β for n-dodecane molecules. These values are shown to be similar (at reduced temperatures T/Tc < 0.8) or slightly larger (at T/Tc > 0.8) than the values of β calculated by the molecular dynamics force fields (MD FF) methods. This endorses the reliability of the previously developed classical approach to estimation of β by the MD FF methods, except at temperatures close to the critical temperature. PMID:25612715

  18. Statistical rate theory examination of ethanol evaporation.

    PubMed

    Persad, A H; Ward, C A

    2010-05-13

    A series of low-temperature (246 < T(I)(L) < 267 K) steady-state ethanol evaporation experiments have been conducted to determine the saturation vapor pressure of metastable ethanol. The measured interfacial conditions have been used with statistical rate theory (SRT) to develop an expression for the saturation vapor pressure as a function of temperature, f(srt)(eth). This expression is shown to be thermodynamically consistent because it gives predictions of both the evaporative latent heat and the liquid constant-pressure specific heat that are in agreement with independent measurements of these properties. In each experiment, the interfacial vapor temperature was measured to be greater than the interfacial liquid temperature, [triple bond]DeltaT(I)(LV). When f(srt)(eth) is used in SRT to predict DeltaT(I)(LV), the results are shown to be consistent with the measurements. Other expressions for the saturation vapor pressure that are in the literature are examined and found to be thermodynamically inconsistent and do not lead to valid predictions of DeltaT(I)(LV). PMID:20405870

  19. Apparent contact angle of an evaporating drop

    NASA Astrophysics Data System (ADS)

    Morris, S. J. S.

    2012-11-01

    In experiments by Poulard et al. (2005), a sessile drop of perfectly wetting liquid evaporates from a non-heated substrate into an under-saturated mixture of vapour with an inert gas; evaporation is limited by vapour diffusion. The system exhibits an apparent contact angle θ that is a flow property. Under certain conditions, the apparent contact line was stationary relative to the substrate; we predict θ for this case. Observed values of θ are small, allowing lubrication analysis of the liquid film. The liquid and vapour flows are coupled through conditions holding at the phase interface; in particular, vapour partial pressure there is related to the local value of liquid pressure through the Kelvin condition. Because the droplet is shallow, the interfacial conditions can be transferred to the solid-liquid interface at y = 0 . We show that the dimensionless partial pressure p (x , y) and the film thickness h (x) are determined by solving ∇2 p = 0 for y > 0 subject to a matching condition at infinity, and the conditions - p = L hxx +h-3 and (h3px) x + 3py = 0 at y = 0 . The parameter L controls the ratio of Laplace to disjoining pressure. We analyse this b.v.p. for the experimentally-relevant case L --> 0 .

  20. Drug loading into porous calcium carbonate microparticles by solvent evaporation.

    PubMed

    Preisig, Daniel; Haid, David; Varum, Felipe J O; Bravo, Roberto; Alles, Rainer; Huwyler, Jörg; Puchkov, Maxim

    2014-08-01

    Drug loading into porous carriers may improve drug release of poorly water-soluble drugs. However, the widely used impregnation method based on adsorption lacks reproducibility and efficiency for certain compounds. The aim of this study was to evaluate a drug-loading method based on solvent evaporation and crystallization, and to investigate the underlying drug-loading mechanisms. Functionalized calcium carbonate (FCC) microparticles and four drugs with different solubility and permeability properties were selected as model substances to investigate drug loading. Ibuprofen, nifedipine, losartan potassium, and metronidazole benzoate were dissolved in acetone or methanol. After dispersion of FCC, the solvent was removed under reduced pressure. For each model drug, a series of drug loads were produced ranging from 25% to 50% (w/w) in steps of 5% (w/w). Loading efficiency was qualitatively analyzed by scanning electron microscopy (SEM) using the presence of agglomerates and drug crystals as indicators of poor loading efficiency. The particles were further characterized by mercury porosimetry, specific surface area measurements, differential scanning calorimetry, and USP2 dissolution. Drug concentration was determined by HPLC. FCC-drug mixtures containing equivalent drug fractions but without specific loading strategy served as reference samples. SEM analysis revealed high efficiency of pore filling up to a drug load of 40% (w/w). Above this, agglomerates and separate crystals were significantly increased, indicating that the maximum capacity of drug loading was reached. Intraparticle porosity and specific surface area were decreased after drug loading because of pore filling and crystallization on the pore surface. HPLC quantification of drugs taken up by FCC showed only minor drug loss. Dissolution rate of FCC loaded with metronidazole benzoate and nifedipine was faster than the corresponding FCC-drug mixtures, mainly due to surface enlargement, because only small

  1. Evaporation and skin penetration characteristics of mosquito repellent formulations

    SciTech Connect

    Reifenrath, W.G.; Hawkins, G.S.; Kurtz, M.S.

    1989-03-01

    Formulations of the mosquito repellent N,N-diethyl-3-methylbenzamide (deet) in combination with a variety of additives were developed to control repellent evaporation and percutaneous penetration. Deet was also formulated with the repellent dimethyl phthalate to study the interaction of the two compounds on the skin. The evaporation and penetration processes were evaluated on whole and split-thickness pig skin using radiolabeled repellents with an in vitro apparatus. Under essentially still air and air flow conditions, one of the deet formulations resulted in significantly reduced total evaporation and percutaneous penetration of deet as compared to unformulated repellent. When deet and dimethyl phthalate were combined, neither repellent affected the total amount of evaporation and penetration of the other compound. However, initial percutaneous penetration and evaporation rates were slightly less and decayed less rapidly than when both chemicals were tested separately at the same dose. These results indicated a degree of competition of the two compounds for the same avenues of loss.

  2. Evaporation from young secondary vegetation in eastern Amazonia

    NASA Astrophysics Data System (ADS)

    Hölscher, D.; de A. Sá, T. D.; Bastos, T. X.; Denich, M.; Fölster, H.

    1997-06-01

    The fallow vegetation of the slash and burn agriculture in eastern Amazonia is dominated by shrubs and trees. This study of evaporation from such secondary vegetation started when the above-ground parts of the vegetation were approximately 2.5 years old. The results are based mainly on a data set containing 231 days of micrometeorological observations in the period from April 1992 to April 1993. Evaporation values obtained with the Penman open water formula ranged from 1.1 to 7.2 mm d-1, with an overall mean of 4.6 mm d-1. Actual evaporation, calculated with the Bowen ratio approach, varied from 1.2 to 5.9 mm d-1, with an overall mean of 3.9 mm d-1. Due to the high net radiation and vapour pressure deficit, and the evenly distributed moderate rainfall, the actual evaporation was constantly high during the transition between the rainy and dry seasons. In a relatively dry period, water limitations were indicated by a decrease in the actual evaporation compared with the Penman open water evaporation. Day-to-day variability was pronounced in the rainy season. An overall average of 79% of the net radiation was converted to latent heat flux. The annual evaporation was calculated by an interpolation of missing data with the continuously observed net radiation. The total actual evaporation was estimated to be 1364 mm a-1, against rainfall of 1819 mm a-1; the remaining 455 mm were allocated to drainage. When actual evaporation exceeded rainfall during the dry season, there had to be access to water storage down to depths of more than 3 m. We conclude that the young secondary vegetation can re-evaporate an important part of the rainfall input in spite of the marked seasonal distribution of rainfall. Possible regional climatic changes due to deforestation may be less severe in areas where woody secondary vegetation plays an important role in land cover.

  3. Evaporative precooling unit

    SciTech Connect

    Rogers, A.R.

    1988-03-15

    In combination with a refrigeration unit, an evaporative heat exchange unit for precooling an air stream traveling toward and over the condensing coil of the refrigeration unit is described. The heat exchange unit includes: (a) a frame, (b) a porous heat transfer pad mounted in the frame; (c) nozzle means carried on the frame for directing a spray mist forwardly of the heat transfer pad, the spray mist emitted from the nozzle means initially traveling in a direction of travel such that the mist will not contact the porous heat transfer pad; (d) means mounted on the frame for causing the turbulent intermixing of the air stream with the spray mist prior to the air stream passing through the porous heat transfer pad; and (e) means for controlling the quantity of water emitted by the nozzle means such that substantially all of the spray mist is intermixed with the air stream prior to the air stream passing through the heat transfer pad.

  4. Evaporation reduction in stock tanks for increasing water supplies

    NASA Astrophysics Data System (ADS)

    Khan, M. A.; Issac, V. C.

    1990-11-01

    Studies were conducted to evaluate the performance of shading and floating materials in reducing evaporation from a free water surface. White polyethene sheet used for shading the water surface reduced evaporation by 91% and cost Rs.2.54 (US0.15) per 10001. Floating materials evaluated were polyethene sheet, foam rubber sheet, polystyrene sheet, bamboo, and Sacchrum munja. Evaporation reduction for a 19-month test period ranged from 37% for S. munja to 82% for polystyrene sheet. Foam rubber sheet, polyethene sheet and bamboo reduced evaporation by 74, 66 and 53%, respectively. The polystyrene sheet and polyethene sheet covers were the most economical, saving water at a cost of Rs.3.07 (US0.19) and Rs.4.44 (US$0.27) per 10001, respectively.

  5. Oxygen Isotopic Fractionation During Evaporation of SiO2 in Vacuum and in H Gas

    NASA Astrophysics Data System (ADS)

    Nagahara, H.; Young, E. D.; Hoering, T. C.; Mysen, B. O.

    1993-07-01

    isotope measurements, including ^17O and silicon isotope measurements, are now in progress, and some of the results are shown in this paper. Oxygen isotopic compositions of residues in vacuum and in hydrogen gas of total pressure of 2.6 x 10^-5 bar, which approximates the pressure of the solar nebula at the midplane at 2-3 AU, are shown in comparison with evaporation rate (Figs. 1 and 2). Oxygen isotopic fractionation is remarkable in a constant evacuation, but is negligible in hydrogen gas of 2.6 x 10^-5 bar total pressure. In vacuum, delta ^18O of solid residue increases with increasing degree of evaporation. The curve is best fit to delta ^18O = 0.00094x^2 + 0.00173x + 19.606 (r = 0.997), where x is the degree of evaporation in weight percent. The curve is fit to the Rayleigh fractionation curve with a constant fractionation factor (alpha(sub)vap-sol) of 0.9970. Figures 1 and 2 show that evaporation is significant but oxygen isotopic fractionation is insignificant in hydrogen gas in the approximate solar nebular condition. The high evaporation rate in hydrogen gas is due to the fact that evaporation is a decomposition reaction of an oxide, which should be accelerated in reducing condition. The rate, however, can be explained by an unknown diffusion process that is possible when hydrogen is reactive with silica [2]. In a fairly high hydrogen pressure, isotopic fractionation is suppressed. On the other hand, in vacuum, the evaporation rate is small but the degree of isotopic fractionation is significant. The results suggest that chondrules and CAIs without isotopic mass fractionation could have been formed in the solar nebula, but that mass loss during heating should have been significant. The CAIs with significant mass fractionation such as HAL could have been formed in vacuum. References: [1] Davis A. et al. (1990) Nature, 347, 655-658. [2] Nagahara H. (1993) LPS XXIV, 1045-1046. Fig. 1, which appears here in the hard copy, shows the evaporation rate of SiO2 heated at

  6. Efficacy of a brief multifactorial adherence-based intervention on reducing the blood pressure of patients with poor adherence: protocol for a randomized clinical trial

    PubMed Central

    2010-01-01

    Background Lowering of blood pressure by antihypertensive drugs reduces the risks of cardiovascular events, stroke, and total mortality. However, poor adherence to antihypertensive medications reduces their effectiveness and increases the risk of adverse events. In terms of relative risk reduction, an improvement in medication adherence could be as effective as the development of a new drug. Methods/Design The proposed randomized controlled trial will include patients with a low adherence to medication and uncontrolled blood pressure. The intervention group will receive a multifactorial intervention during the first, third, and ninth months, to improve adherence. This intervention will include motivational interviews, pill reminders, family support, blood pressure self-recording, and simplification of the dosing regimen. Measurement The primary outcome is systolic blood pressure. The secondary outcomes are diastolic blood pressure, proportion of patients with adequately controlled blood pressure, and total cost. Discussion The trial will evaluate the impact of a multifactorial adherence intervention in routine clinical practice. Ethical approval was given by the Ethical Committee on Human Research of Balearic islands, Spain (approval number IB 969/08 PI). Trial registration Current controlled trials ISRCTN21229328 PMID:20868531

  7. Irradiated ignition of solid materials in reduced pressure atmosphere with various oxygen concentrations for fire safety in space habitats

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Aoki, A.

    Effects of sub-atmospheric ambient pressure and oxygen content on irradiated ignition characteristics of solid combustibles were examined experimentally in order to elucidate the flammability and chance of fire in depressurized systems and give ideas for the fire safety and fire fighting strategies for such environments. Thin cellulosic paper was used as the solid combustible since cellulose is one of major organic compounds and flammables in the nature. Applied atmospheres consisted of inert gases (either CO 2 or N 2) and oxygen at various mixture ratios. Total ambient pressure ( P) was varied from 101 kPa (standard atmospheric pressure, P0) to 20 kPa. Ignition was initiated by external thermal radiation with CO 2 laser (10 W total; 21.3 W/cm 2 of the corresponding peak flux) onto the solid surface. Thermal degradation of the solid produced combustible gaseous products (e.g. CO, H 2, or other low weight of HCs) and these products mixed with ambient oxygen to form the combustible mixture over the solid. Heat transfer from the irradiated surface into the mixture accelerated the exothermic reaction in the gas phase and finally thermal runaway (ignition) was achieved. A digital video camera was used to analyze the ignition characteristics. Flammability maps in partial pressure of oxygen (ppO 2) and normalized ambient pressure ( P/ P0) plane were made to reveal the fire hazard in depressurized environments. Results showed that a wider flammable range was obtained in sub-atmospherics conditions. In middle pressure range (101-40 kPa), the required ppO 2 for ignition decreased almost linearly as the total pressure decreased, indicating that higher fire risk is expected. In lower pressure range (<40 kPa), the required partial pressure of oxygen increased dramatically, then ignition was eventually not achieved at pressures less than 20 kPa under the conditions studied here. The findings suggest that it might be difficult to satisfy safety in space agriculture since it has

  8. Evaporation Dynamics of Moss and Bare Soil in Boreal Forests

    NASA Astrophysics Data System (ADS)

    Dempster, S.; Young, J. M.; Barron, C. G.; Bolton, W. R.

    2013-12-01

    Evaporation dynamics of mosses is a critical process in boreal and arctic systems and represents a key uncertainty in hydrology and climate models. At this point, moss evaporation is not well quantified at the plot or landscape scale. Relative to bare soil or litter evaporation, moss evaporation can be challenging to predict because the water flux is not isolated to the moss surface. Evaporation can originate from nearly 10 cm below the surface. Some mosses can wick moisture from even deeper than 10 cm, which subsequently evaporates. The goal of this study was to use field measurements to quantify the moss evaporation dynamics in a coniferous forest relative to bare ground or litter evaporation dynamics in a deciduous forest in Interior Alaska. Measurements were made in two ecosystem types within the boreal forest of Interior Alaska: a deciduous forest devoid of moss and a coniferous forest with a thick moss layer. A small clear chamber was attached to a LiCor 840 infrared gas analyzer in a closed loop system with a low flow rate. Water fluxes were measured for ~ 90 seconds on each plot in dry and wet soil and moss conditions. Additional measurements included: soil temperature, soil moisture, air temperature, barometric pressure, dew point, relative humidity, and wind speed. Thermal infrared images were also captured in congruence with water flux measurements to determine skin temperature. We found that the moss evaporation rate was over 100% greater than the soil evaporation rate (0.057 g/min vs. 0.024 g/min), and evaporation rates in both systems were most strongly driven by relative humidity and surface temperature. Surface temperature was lower at the birch site than the black spruce site because trees shade the surface beneath the birch. High fluxes associated with high water content were sustained for a longer period of time over the mosses compared to the bare soil. The thermal IR data showed that skin temperature lagged the evaporation flux, such that the

  9. Out-of-tank evaporator demonstration: Tanks focus area

    SciTech Connect

    1998-11-01

    Approximately 100 million gal of liquid waste is stored in underground storage tanks (UST)s at the Hanford Site, Idaho National Engineering and Environmental Laboratory (INEEL), Savannah River Site (SRS), and Oak Ridge Reservation (ORR). This waste is radioactive with a high salt content. The US Department of Energy (DOE) wants to minimize the volume of radioactive liquid waste in USTs by removing the excess water. This procedure conserves tank space; lowers the cost of storage; and reduces the volume of wastes subsequently requiring separation, immobilization, and disposal. The Out-of-Tank Evaporator Demonstration (OTED) was initiated to test a modular, skid-mounted evaporator. A mobile evaporator system manufactured by Delta Thermal Inc. was selected. The evaporator design was routinely used in commercial applications such as concentrating metal-plating wastes for recycle and concentrating ethylene glycol solutions. In FY 1995, the skid-mounted evaporator system was procured and installed in an existing ORNL facility (Building 7877) with temporary shielding and remote controls. The evaporator system was operational in January 1996. The system operated 24 h/day and processed 22,000 gal of Melton Valley Storage Tank (MVST) supernatant. The distillate contained essentially no salts or radionuclides. Upon completion of the demonstration, the evaporator underwent decontamination testing to illustrate the feasibility of hands-on maintenance and potential transport to another DOE facility. This report describes the process and the evaporator, its performance at ORNL, future plans, applications of this technology, cost estimates, regulatory and policy considerations, and lessons learned.

  10. Vacuum flash evaporated polymer composites

    DOEpatents

    Affinito, John D.; Gross, Mark E.

    1997-01-01

    A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

  11. Vacuum flash evaporated polymer composites

    DOEpatents

    Affinito, J.D.; Gross, M.E.

    1997-10-28

    A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

  12. Experimental Investigation of Microstructured Evaporators

    NASA Astrophysics Data System (ADS)

    Wibel, W.; Westermann, S.; Maikowske, S.; Brandner, J. J.

    2012-11-01

    Microfluidic devices have become more and more popular over the last decades [1]. Cooling is a topic where microstructures offer significant advantages compared to conventional techniques due the much higher possible surface to volume ratios and short heat transfer lengths. By evaporating of a fluid in microchannels, compact, fast and powerful cooling devices become possible [2]. Experimental results for different designs of microstructured evaporators are presented here. They have been obtained either using water as evaporating coolant or the refrigerant R134a (Tetrafluoroethane). A new microstructured evaporator design consisting of bended microchannels instead of straight channels for a better performance is shown and compared to previous results [2] for the evaporation of R134a in straight microchannels.

  13. Molecular Mechanism of Water Evaporation

    NASA Astrophysics Data System (ADS)

    Nagata, Yuki; Usui, Kota; Bonn, Mischa

    2015-12-01

    Evaporation is the process by which water changes from a liquid to a gas or vapor, and is a key step in Earth's water cycle. At the molecular level, evaporation requires breaking at least one very strong intermolecular bond between two water molecules at the interface. Despite the importance of this process the molecular mechanism by which an evaporating water molecule gains sufficient energy to escape from the surface has remained elusive. Here, we show, using molecular dynamics simulations at the water-air interface with polarizable classical force field models, that the high kinetic energy of the evaporated water molecule is enabled by a well-timed making and breaking of hydrogen bonds involving at least three water molecules at the interface, the recoil of which allows one of the molecules to escape. The evaporation of water is thus enabled by concerted, ultrafast hydrogen-bond dynamics of interfacial water, and follows one specific molecular pathway.

  14. Evaporative Emission Model (EVAP 3. 0) (for microcomputers). Software

    SciTech Connect

    Not Available

    1993-02-01

    The potential role of automotive evaporative emissions in the formation of photochemical smog has underscored the need for an accurate evaluation of real-world motor vehicle evaporative emission rates. Two general categories of information are needed to predict evaporative emissions for vehicles in actual use. The first category defines the environment that a vehicle experiences in the real world. This includes conditions such as driving pattern, ambient temperature, refueling behavior, and gasoline Reid vapor pressure (RVP). The second category describes how the vehicle responds to these conditions. This includes weathering of the fuel in the fuel tank and how evaporative emissions vary as a function of RVP, ambient temperature, and fuel tank level.

  15. Does the creation of a boreal hydroelectric reservoir result in a net change in evaporation?

    NASA Astrophysics Data System (ADS)

    Strachan, Ian B.; Tremblay, Alain; Pelletier, Luc; Tardif, Simon; Turpin, Christian; Nugent, Kelly A.

    2016-09-01

    Estimates of water consumption from hydroelectricity production are hampered by a lack of common methodological approaches. Studies typically use gross evaporation estimates which do not take into account the evaporative water loss from the pre-flooded ecosystems that would occur without the presence of a reservoir. We evaluate the net change in evaporation following the creation of a hydroelectric reservoir located in the Canadian boreal region. We use a direct measurement technique (eddy covariance) over four different ecosystems to evaluate the pre- and post-flood landscape water flux over a five-year period. The net effect of reservoir creation was to increase evaporation over that of the pre-flooded ecosystem. This change was dependent both on management and differences in the timing of the evaporation with nighttime and autumn contributing strongly to the reservoir evaporation. Managed reduction of water level, and thus the evaporating area, reduced the evaporation.

  16. The Savannah River Site Replacement High Level Radioactive Waste Evaporator Project

    SciTech Connect

    Presgrove, S.B.

    1992-08-01

    The Replacement High Level Waste Evaporator Project was conceived in 1985 to reduce the volume of the high level radioactive waste Process of the high level waste has been accomplished up to this time using Bent Tube type evaporators and therefore, that type evaporator was selected for this project. The Title I Design of the project was 70% completed in late 1990. The Department of Energy at that time hired an independent consulting firm to perform a complete review of the project. The DOE placed a STOP ORDER on purchasing the evaporator in January 1991. Essentially, no construction was to be done on this project until all findings and concerns dealing with the type and design of the evaporator are resolved. This report addresses two aspects of the DOE design review; (1) Comparing the Bent Tube Evaporator with the Forced Circulation Evaporator, (2) The design portion of the DOE Project Review - concentrated on the mechanical design properties of the evaporator. 1 ref.

  17. The Savannah River Site Replacement High Level Radioactive Waste Evaporator Project

    SciTech Connect

    Presgrove, S.B. )

    1992-01-01

    The Replacement High Level Waste Evaporator Project was conceived in 1985 to reduce the volume of the high level radioactive waste Process of the high level waste has been accomplished up to this time using Bent Tube type evaporators and therefore, that type evaporator was selected for this project. The Title I Design of the project was 70% completed in late 1990. The Department of Energy at that time hired an independent consulting firm to perform a complete review of the project. The DOE placed a STOP ORDER on purchasing the evaporator in January 1991. Essentially, no construction was to be done on this project until all findings and concerns dealing with the type and design of the evaporator are resolved. This report addresses two aspects of the DOE design review; (1) Comparing the Bent Tube Evaporator with the Forced Circulation Evaporator, (2) The design portion of the DOE Project Review - concentrated on the mechanical design properties of the evaporator. 1 ref.

  18. Irradiated ignition over solid materials in reduce pressure environment: Fire safety issue in man-made enclosure system

    NASA Astrophysics Data System (ADS)

    Nakamura, N.; Aoki, A.

    Effects of ambient pressure and oxygen yield on irradiated ignition characteristics over solid combustibles have been studied experimentally Aim of the present study is to elucidate the flammability and chance of fire in depressurized enclosure system and give ideas for the fire safety and fire fighting strategies in such environment Thin cellulosic paper is considered as the solid combustible since cellulose is one of major organic compounds and flammables in the nature Applied atmosphere consists of inert gas either CO2 or N2 and oxygen and various mixture ratios are of concerned Total ambient pressure level is varied from 0 1MPa standard atmospheric pressure to 0 02MPa Ignition is initiated by external thermal flux exposed into the solid surface as a model of unexpected thermal input to initiate the localized fire Thermal degradation of the solid induces combustible gaseous products e g CO H2 or other low class of HCs and the gas mixes with ambient oxygen to form the combustible mixture over the solid Heat transfer from the hot irradiated surface into the mixture accelerates the local exothermic reaction in the gas phase and finally thermal runaway ignition is achieved Ignition event is recorded by high-speed digital video camera to analyze the ignition characteristics Flammable map in partial pressure of oxygen Pox and total ambient pressure Pt plane is made to reveal the fire hazard in depressurized environment Results show that wider flammable range is obtained depending on the imposed ambient

  19. Two stage indirect evaporative cooling system

    DOEpatents

    Bourne, Richard C.; Lee, Brian E.; Callaway, Duncan

    2005-08-23

    A two stage indirect evaporative cooler that moves air from a blower mounted above the unit, vertically downward into dry air passages in an indirect stage and turns the air flow horizontally before leaving the indirect stage. After leaving the dry passages, a major air portion travels into the direct stage and the remainder of the air is induced by a pressure drop in the direct stage to turn 180.degree. and returns horizontally through wet passages in the indirect stage and out of the unit as exhaust air.

  20. Steady evaporating flow in rectangular microchannels.

    SciTech Connect

    Griffiths, Stewart K.; Martinez, Mario J.; Tchikanda, Serge W.; Nilson, Robert H.

    2005-02-01

    Analytical and numerical solutions are presented for steady evaporating flow in open microchannels having a rectangular cross section and a uniform depth. The flow, driven by the axial gradient of capillary pressure, generally consists of an entry region where the meniscus is attached to the top corners of the channel followed by a jump-like transition to a corner-flow region in which the meniscus progressively recedes into the bottom corners of the channel. Illustrative numerical solutions are used to guide the derivation of an easily applied analytical approximation for the maximum sustainable heat flux or capillary limit.

  1. Treatment of evaporator condensates by pervaporation

    DOEpatents

    Blume, Ingo; Baker, Richard W.

    1990-01-01

    A pervaporation process for separating organic contaminants from evaporator condensate streams is disclosed. The process employs a permselective membrane that is selectively permeable to an organic component of the condensate. The process involves contacting the feed side of the membrane with a liquid condensate stream, and withdrawing from the permeate side a vapor enriched in the organic component. The driving force for the process is the in vapor pressure across the membrane. This difference may be provided for instance by maintaining a vacuum on the permeate side, or by condensing the permeate. The process offers a simple, economic alternative to other separation techniques.

  2. Rapid Evaporation of microbubbles

    NASA Astrophysics Data System (ADS)

    Gautam, Jitendra; Esmaeeli, Asghar

    2008-11-01

    When a liquid is heated to a temperature far above its boiling point, it evaporates abruptly. Boiling of liquid at high temperatures can be explosive and destructive, and poses a potential hazard for a host of industrial processes. Explosive boiling may occur if a cold and volatile liquid is brought into contact with a hot and non-volatile liquid, or if a liquid is superheated or depressurized rapidly. Such possibilities are realized, for example, in the depressurization of low boiling point liquefied natural gas (LNG) in the pipelines or storage tanks as a result of a leak. While boiling of highly heated liquids can be destructive at macroscale, the (nearly) instantaneous pace of the process and the release of large amount of kinetic energy make the phenomena extremely attractive at microscale where it is possible to utilize the released energy to derive micromechanical systems. For instance, there is currently a growing interest in micro-explosion of liquid for generation of micro bubbles for actuation purposes. The aim of the current study is to gain a fundamental understanding of the subject using direct numerical simulations. In particular, we seek to investigate the boundary between stable and unstable nucleus growth in terms of the degree of liquid superheat and to compare the dynamics of unstable and stable growth.

  3. Evaporation of solids by pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Stafast, H.; Von Przychowski, M.

    The focused beam of a KrF laser (248 nm) has been applied to irradiate targets of Al 2O 3, SiC, graphite, Pb, Ni, Cr, quartz, and NaCl at variable laser energy flux is the range 0-13 J/cm 2. The amount of target material ejected into the vacuum (background pressure about 8 × 10 -4 Torr) was determined from the target weight before and after laser irradiation. The average number of particles (formula weight) evaporated per laser pulse and per unit of irradiated target area is non-linearly dependent on the laser energy flux. The evaporation of Al 2O 3, SiC, and graphite is showing a well-defined flux threshold while the vaporization of Pb, Ni and Cr is rising smoothly with increasing flux. With both groups of materials laser evaporation is monotonically increasing with the laser energy flux. NaCl and quartz, on the other hand, are showing an intermediate maximum in the laser vaporization efficiency.

  4. Removal of Sulfate Ion From AN-107 by Evaporation

    SciTech Connect

    GJ Lumetta; GS Klinger; DE Kurath; RL Sell; LP Darnell; LR Greenwood; CZ Soderquist; MJ Steele; MW Urie; JJ Wagner

    2000-08-02

    Hanford low-activity waste solutions contain sulfate, which can cause accelerated corrosion of the vitrification melter and unacceptable operating conditions. A method is needed to selectively separate sulfate from the waste. An experiment was conducted to evaluate evaporation for removing sulfate ion from Tank AN-107 low-activity waste. Two evaporation steps were performed. In the first step, the volume was reduced by 55% while in the second step, the liquid volume was reduced another 22%. Analysis of the solids precipitated during these evaporations revealed that large amounts of sodium nitrate and nitrite co-precipitated with sodium sulfate. Many other waste components precipitated as well. It can be concluded that sulfate removal by precipitation is not selective, and thus, evaporation is not a viable option for removing sulfate from the AN-107 liquid.

  5. Evaporated Lithium Surface Coatings in NSTX

    SciTech Connect

    Kugel, H. W.; Mansfield, D.; Maingi, R.; Bel, M. G.; Bell, R. E.; Allain, J. P.; Gates, D.; Gerhardt, S.; Kaita, R.; Kallman, J.; Kaye, S.; LeBlanc, B.; Majeski, R.; Menard, J.; Mueller, D.; Ono, M.

    2009-04-09

    Two lithium evaporators were used to evaporate more than 100 g of lithium on to the NSTX lower divertor region. Prior to each discharge, the evaporators were withdrawn behind shutters, where they also remained during the subsequent HeGDC applied for periods up to 9.5 min. After the HeGDC, the shutters were opened and the LITERs were reinserted to deposit lithium on the lower divertor target for 10 min, at rates of 10-70 mg/min, prior to the next discharge. The major improvements in plasma performance from these lithium depositions include: 1) plasma density reduction as a result of lithium deposition; 2) suppression of ELMs; 3) improvement of energy confinement in a low-triangularity shape; 4) improvement in plasma performance for standard, high-triangularity discharges; 5) reduction of the required HeGDC time between discharges; 6) increased pedestal electron and ion temperature; 7) reduced SOL plasma density; and 8) reduced edge neutral density.

  6. Launching a salt substitute to reduce blood pressure at the population level: a cluster randomized stepped wedge trial in Peru

    PubMed Central

    2014-01-01

    Background Controlling hypertension rates and maintaining normal blood pressure, particularly in resource-constrained settings, represent ongoing challenges of effective and affordable implementation in health care. One of the strategies being largely advocated to improve high blood pressure calls for salt reduction strategies. This study aims to estimate the impact of a population-level intervention based on sodium reduction and potassium increase – in practice, introducing a low-sodium, high-potassium salt substitute – on adult blood pressure levels. Methods/Design The proposed implementation research study includes two components: Phase 1, an exploratory component, and Phase 2, an intervention component. The exploratory component involves a triangle taste test and a formative research study designed to gain an understanding of the best implementation methods. Phase 2 involves a pragmatic stepped wedge trial design where the intervention will be progressively implemented in several clusters starting the intervention randomly at different times. In addition, we will evaluate the implementation strategy using a cost-effectiveness analysis. Discussion This is the first project in a Latin-American setting to implement a salt substitution intervention at the population level to tackle high blood pressure. Data generated and lessons learnt from this study will provide a strong platform to address potential interventions applicable to other similar low- and middle-income settings. Trial registration This study is registered in ClinicalTrials.gov NCT01960972. PMID:24667035

  7. CO2 exposure at pressure impacts metabolism and stress responses in the model sulfate-reducing bacterium Desulfovibrio vulgaris strain Hildenborough

    SciTech Connect

    Wilkins, Michael J.; Hoyt, David W.; Marshall, Matthew J.; Alderson, Paul A.; Plymale, Andrew E.; Markillie, Lye Meng; Tucker, Abigail E.; Walter, Eric D.; Linggi, Bryan E.; Dohnalkova, Alice; Taylor, Ronald C.

    2014-09-01

    Geologic carbon dioxide (CO2) sequestration drives physical and geochemical changes in deep subsurface environments that impact indigenous microbial activities. The combined effects of pressurized CO2 on a model sulfate-reducing microorganism, Desulfovibrio vulgaris, have been assessed using a suite of genomic and kinetic measurements. Novel high-pressure NMR time-series measurements using 13C-lactate were used to track D. vulgaris metabolism. We identified cessation of respiration at CO2 pressures of 10 bar, 25 bar, 50 bar, and 80 bar. Concurrent experiments using N2 as the pressurizing phase had no negative effect on microbial respiration, as inferred from reduction of sulfate to sulfide. Complementary pressurized batch incubations and fluorescence microscopy measurements supported NMR observations, and indicated that non-respiring cells were mostly viable at 50 bar CO2 for at least four hours, and at 80 bar CO2 for two hours. The fraction of dead cells increased rapidly after four hours at 80 bar CO2. Transcriptomic (RNA-Seq) measurements on mRNA transcripts from CO2-incubated biomass indicated that cells up-regulated the production of certain amino acids (leucine, isoleucine) following CO2 exposure at elevated pressures, likely as part of a general stress response. Evidence for other poorly understood stress responses were also identified within RNA-Seq data, suggesting that while pressurized CO2 severely limits the growth and respiration of D. vulgaris cells, biomass retains intact cell membranes at pressures up to 80 bar CO2. Together, these data show that geologic sequestration of CO2 may have significant impacts on rates of sulfate reduction in many deep subsurface environments where this metabolism is a key respiratory process.

  8. CO2 exposure at pressure impacts metabolism and stress responses in the model sulfate-reducing bacterium Desulfovibrio vulgaris strain Hildenborough

    PubMed Central

    Wilkins, Michael J.; Hoyt, David W.; Marshall, Matthew J.; Alderson, Paul A.; Plymale, Andrew E.; Markillie, L. Meng; Tucker, Abby E.; Walter, Eric D.; Linggi, Bryan E.; Dohnalkova, Alice C.; Taylor, Ron C.

    2014-01-01

    Geologic carbon dioxide (CO2) sequestration drives physical and geochemical changes in deep subsurface environments that impact indigenous microbial activities. The combined effects of pressurized CO2 on a model sulfate-reducing microorganism, Desulfovibrio vulgaris, have been assessed using a suite of genomic and kinetic measurements. Novel high-pressure NMR time-series measurements using 13C-lactate were used to track D. vulgaris metabolism. We identified cessation of respiration at CO2 pressures of 10 bar, 25 bar, 50 bar, and 80 bar. Concurrent experiments using N2 as the pressurizing phase had no negative effect on microbial respiration, as inferred from reduction of sulfate to sulfide. Complementary pressurized batch incubations and fluorescence microscopy measurements supported NMR observations, and indicated that non-respiring cells were mostly viable at 50 bar CO2 for at least 4 h, and at 80 bar CO2 for 2 h. The fraction of dead cells increased rapidly after 4 h at 80 bar CO2. Transcriptomic (RNA-Seq) measurements on mRNA transcripts from CO2-incubated biomass indicated that cells up-regulated the production of certain amino acids (leucine, isoleucine) following CO2 exposure at elevated pressures, likely as part of a general stress response. Evidence for other poorly understood stress responses were also identified within RNA-Seq data, suggesting that while pressurized CO2 severely limits the growth and respiration of D. vulgaris cells, biomass retains intact cell membranes at pressures up to 80 bar CO2. Together, these data show that geologic sequestration of CO2 may have significant impacts on rates of sulfate reduction in many deep subsurface environments where this metabolism is a key respiratory process. PMID:25309528

  9. Production of stable tellurium evaporated targets

    NASA Astrophysics Data System (ADS)

    Greene, John P.; Palumbo, Annalia; Tan, Wanpeng; Görres, Joachim; Wiescher, Michael C.

    2008-06-01

    Due to the low melting point of tellurium metal, self-supporting Te targets degrade quickly when exposed to particle beams. This situation is greatly improved if the tellurium material is evaporated onto C foil backings. Elastic scattering in target and backing layers broadens the Te peak, making measurements difficult, while too little material reduces the reaction rate. Therefore, it is necessary to optimize the target thickness. Evaporated metallic and oxide Te targets were prepared at Argonne National Laboratory by vacuum deposition from a resistively heated source boat. The stability of the targets was then tested by exposing them to a varying intensity alpha beam with an energy range from 17 to 27 MeV using the FN Tandem Van de Graaff accelerator at the University of Notre Dame. Optimal target thicknesses and beam currents were then obtained for p-process experiments. A description of the apparatus and production method will be presented.

  10. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  11. Experimental study of the effect of drag reducing agent on pressure drop and thermal efficiency of an air cooler

    NASA Astrophysics Data System (ADS)

    Peyghambarzadeh, S. M.; Hashemabadi, S. H.; Saffarian, H.; Shekari, F.

    2016-01-01

    Effect of polymeric drag reduction agents (DRAs) on pressure drop and heat transfer was studied. Aqueous solutions of carboxy methyl cellulose were used inside an air-finned heat exchanger. Despite the previous studies which indicated the importance of drag reduction just in turbulent flow, results of this study in laminar flow indicated that the addition of DRA increases drag reduction, and decreases the overall heat transfer coefficient.

  12. Food supplementation with an olive (Olea europaea L.) leaf extract reduces blood pressure in borderline hypertensive monozygotic twins.

    PubMed

    Perrinjaquet-Moccetti, Tania; Busjahn, Andreas; Schmidlin, Caesar; Schmidt, Annette; Bradl, Barbara; Aydogan, Cem

    2008-09-01

    Hypertension is a harmful disease factor that develops unnoticed over time. The treatment of hypertension is aimed at an early diagnosis followed by adequate lifestyle changes rather than pharmacological treatment. The olive leaf extract EFLA943, having antihypertensive actions in rats, was tested as a food supplement in an open study including 40 borderline hypertensive monozygotic twins. Twins of each pair were assigned to different groups receiving 500 or 1000 mg/day EFLA943 for 8 weeks, or advice on a favourable lifestyle. Body weight, heart rate, blood pressure, glucose and lipids were measured fortnightly. Blood pressure changed significantly within pairs, depending on the dose, with mean systolic differences of < or =6 mmHg (500 mg vs control) and < or =13 mmHg (1000 vs 500 mg), and diastolic differences of < or =5 mmHg. After 8 weeks, mean blood pressure remained unchanged from baseline in controls (systolic/diastolic: 133 +/- 5/77 +/- 6 vs 135 +/- 11/80 +/- 7 mmHg) and the low-dose group (136 +/- 7/77 +/- 7 vs 133 +/- 10/76 +/- 7), but had significantly decreased for the high dose group (137 +/- 10/80 +/- 10 vs 126 +/- 9/76 +/- 6). Cholesterol levels decreased for all treatments with significant dose-dependent within-pair differences for LDL-cholesterol. None of the other parameters showed significant changes or consistent trends. Concluding, the study confirmed the antihypertensive and cholesterol-lowering action of EFLA943 in humans. PMID:18729245

  13. Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin.

    PubMed

    Havenith, George; Bröde, Peter; den Hartog, Emiel; Kuklane, Kalev; Holmer, Ingvar; Rossi, Rene M; Richards, Mark; Farnworth, Brian; Wang, Xiaoxin

    2013-03-15

    Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has found little use in recent literature. In this experiment a thermal manikin, (MTNW, Seattle, WA) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently, allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used, and different numbers of layers were used. Tests took place in 20°C, 0.5 m/s at different humidities and were performed both dry and with a wet layer, allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin, λeff is close to the theoretical value (2,430 J/g) but starts to drop when more clothing is worn, e.g., by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base layer), increasing toward 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear, the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed. PMID:23329814

  14. Evaporation effects in elastocapillary aggregation

    NASA Astrophysics Data System (ADS)

    Vella, Dominic; Hadjittofis, Andreas; Singh, Kiran; Lister, John

    2015-11-01

    We consider the effect of evaporation on the aggregation of a number of elastic objects due to a liquid's surface tension. In particular, we consider an array of spring-block elements in which the gaps between blocks are filled by thin liquid films that evaporate during the course of an experiment. Using lubrication theory to account for the fluid flow within the gaps, we study the dynamics of aggregation. We find that a non-zero evaporation rate causes the elements to aggregate more quickly and, indeed, to contact within finite time. However, we also show that the number of elements within each cluster decreases as the evaporation rate increases. We explain these results quantitatively by comparison with the corresponding two-body problem and discuss their relevance for controlling pattern formation in carbon nanotube forests.

  15. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, Douglas R.; Rawlinson, K. Scott

    1994-01-01

    An improved evaporator section for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes.

  16. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, D.R.; Rawlinson, K.S.

    1994-01-04

    An improved evaporator section is described for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes. 1 figure.

  17. Horst Meyer and Quantum Evaporation

    NASA Astrophysics Data System (ADS)

    Balibar, S.

    2016-06-01

    With their 1963 article in Cryogenics Horst Meyer and his collaborators triggered intense research activity on the evaporation of superfluid helium. Discussing this subject with him in 1975 was enlightening. Fifty years later, the analogy between the photoelectric effect and the evaporation of superfluid helium in the low temperature limit is not yet clear, although remarkable progress has been made in its observation and its understanding. This special issue of the Journal of Low Temperature Physics is an opportunity to recall the history of quantum evaporation, and to express my gratitude to Horst Meyer. It describes quickly most of the experimental and theoretical works which have been published on quantum evaporation during the last 50 years, but it is not a comprehensive review of this fascinating subject.

  18. Evaporation Tower With Prill Nozzles

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1984-01-01

    Tower more efficient than conventional evaporation equipment. Liquids such as milk and fruit juice concentrated by passing them through tiny nozzle to form droplets, then allowing droplets to fall through evacuated tower with cooled walls.

  19. Hollow-Fiber Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  20. Comparison of efficacy of the intermittent pneumatic compression with a high- and low-pressure application in reducing the lower limbs phlebolymphedema

    PubMed Central

    Taradaj, Jakub; Rosińczuk, Joanna; Dymarek, Robert; Halski, Tomasz; Schneider, Winfried

    2015-01-01

    Introduction The primary lymphedema and chronic venous insufficiency present an important medical problem, and effective physical therapeutic methods to treat this problem are still at the search phase. The aim of this study was to compare the efficacy of intermittent pneumatic compression (IPC) of a high- or low-pressure level in the treatment of primary phlebolymphedema of the lower limbs. Methods The study included 81 patients with chronic venous insufficiency and primary lymphedema of the lower limbs. Group A consisted of 28 patients who underwent a monthly antiedematous therapy including a manual lymphatic drainage, multilayer bandaging, and IPC with the output pressure of 120 mmHg. Group B consisted of 27 patients who underwent the same basic treatment as group A and IPC with the output pressure of 60 mmHg. Group C (control) consisted of 26 patients who underwent only a basic treatment – without IPC. Results After completion of the study, it was found that the greatest reduction of edema occurred in patients who underwent treatment with a pressure of 120 mmHg. The comparison of percentage reduction of edema showed a statistically significant advantage of the group A over groups B and C, both for the changes in the right (P=0.01) and the left limb (P=0.01). Results in patients undergoing intermittent compression of the lower pressure (60 mmHg) were similar to those obtained in the control group. Conclusion The IPC with the pressure of 120 mmHg inside the chambers effectively helps to reduce a phlebolymphedema. Furthermore, it appears that the treatments with a pressure of 60 mmHg are ineffective and their application becomes useless only in the antiedematous therapy. PMID:26504396

  1. A shortcut for designing evaporators

    SciTech Connect

    Durand, M.I.A.A.

    1996-01-01

    Multiple-effect evaporation is commonly used in chemical process plants to minimize energy consumption and cooling water. In this system, several evaporators are connected by piping so that vapor passes from one effect to the next in series. Thus, the heat supplied to the first evaporator is used to vaporize water in the first effect; this vapor, in turn, passes to the next effect, until, finally, the heat in the vapor supplied to the last effect passes on to the condenser. The net result of this arrangement is the multiple reuse of heat, and a marked increase in the economic of the evaporation system. In addition to savings in steam use, there is also a saving in condenser cooling water as the number of effects increases. On the other hand, an increase in the number of effects represents an increase in capital costs since more heat transfer area is required in the evaporator system. Thus, the choice of the proper--that is, optimum--number of effects is dictated by an economic balance between the savings in steam and cooling water versus that of the additional investment costs. The paper describes the basic equations and an economic analysis of evaporator systems, and illustrates the method with an example.

  2. Evaporation Kinetics of Laboratory Generated Secondary Organic Aerosols at Elevated Relative Humidity

    SciTech Connect

    Wilson, Jacqueline M.; Imre, D.; Beranek, Josef; Shrivastava, ManishKumar B.; Zelenyuk, Alla

    2015-01-06

    Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semi-solid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on SOA particles generated, evaporated, and aged at 0%, 50% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30% to 70% of the particle mass evaporates in 2 hours, followed by a much slower evaporation rate. Evaporation kinetics at 0% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses, with aging at elevated RH leading to more significant effect. In all cases, SOA evaporation is nearly size-independent, providing direct evidence that oligomers play a crucial role in determining the evaporation kinetics.

  3. STUDIES OF POTENTIAL INHIBITORS OF SODIUM ALUMINOSILICATE SCALES IN HIGH-LEVEL WASTE EVAPORATION

    SciTech Connect

    Wilmarth, B; Lawrence Oji, L; Terri Fellinger, T; David Hobbs, D; Nilesh Badheka, N

    2008-02-27

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing aluminum and silicates has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS.

  4. Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation

    SciTech Connect

    Oji, L.N.; Fellinger, T.L.; Hobbs, D.T.; Badheka, N.P.; Wilmarth, W.R.

    2008-07-01

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing dissolved aluminate and silicate has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS. (authors)

  5. Chemical evolution of multicomponent aerosol particles during evaporation

    NASA Astrophysics Data System (ADS)

    Zardini, Alessandro; Riipinen, Ilona; Pagels, Joakim; Eriksson, Axel; Worsnop, Douglas; Switieckli, Erik; Kulmala, Markku; Bilde, Merete

    2010-05-01

    Atmospheric aerosol particles have an important but not well quantified effect on climate and human health. Despite the efforts made in the last decades, the formation and evolution of aerosol particles in the atmosphere is still not fully understood. The uncertainty is partly due to the complex chemical composition of the particles which comprise inorganic and organic compounds. Many organics (like dicarboxylic acids) can be present both in the gas and in the condensed phase due to their low vapor pressure. Clearly, an understanding of this partition is crucial to address any other issue in atmospheric physics and chemistry. Moreover, many organics are water soluble, and their influence on the properties of aqueous solution droplets is still poorly characterized. The solid and sub-cooled liquid state vapor pressures of some organic compounds have been previously determined by measuring the evaporation rate of single-compound crystals [1-3] or binary aqueous droplets [4-6]. In this work, we deploy the HTDMA technique (Hygroscopicity Tandem Differential Mobility Analyzer) coupled with a 3.5m laminar flow-tube and an Aerosol Mass Spectrometer (AMS) for determining the chemical evolution during evaporation of ternary droplets made of one dicarboxylic acid (succinic acid, commonly found in atmospheric samples) and one inorganic compound (sodium chloride or ammonium sulfate) in different mixing ratios, in equilibrium with water vapor at a fixed relative humidity. In addition, we investigate the evaporation of multicomponent droplets and crystals made of three organic species (dicarboxylic acids and sugars), of which one or two are semi-volatile. 1. Bilde M. and Pandis, S.N.: Evaporation Rates and Vapor Pressures of Individual Aerosol Species Formed in the Atmospheric Oxidation of alpha- and beta-Pinene. Environmental Science and Technology, 35, 2001. 2. Bilde M., et al.: Even-Odd Alternation of Evaporation Rates and Vapor Pressures of C3-C9 Dicarboxylic Acid Aerosols

  6. Membrane-Based Water Evaporator for a Space Suit

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; McCann, Charles J.; O'Connell, Mary K.; Andrea, Scott

    2004-01-01

    A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

  7. Numerical Study of a Hydrodynamic Instability Driven by Evaporation

    NASA Astrophysics Data System (ADS)

    Hernandez-Zapata, Sergio; Romo-Cruz, Julio Cesar Ruben; Lopez-Sanchez, Erick Javier; Ruiz-Chavarria, Gerardo

    2013-11-01

    The study of hydrodynamic instabilities in liquid layers produced by evaporation has several applications on industry and technology. In this work we study numerically the conditions under which a liquid layer becomes unstable when evaporation in the vapor-liquid interphase is present. The evaporation process follows the Hertz-Knudsen law (the evaporation rate is proportional to the difference between the saturated vapor pressure at the liquid layer temperature and the vapor partial pressure in the environment). Additionally to the usual boundary conditions on solid walls (for example, the non-slip condition for the velocity), we analyze the boundary conditions in the vapor-liquid interphase where the momentum and energy balances have to be taken into account and where the evaporation plays a crucial role. To solve this problem the linear theory of stability is used; that is, a small perturbation around the basic solution is applied (flow at rest and a temperature stationary field). The equations are solved using the Chebyshev pseudo-spectral method. The results are compared with the more usual Rayleigh-Bénard and Marangoni mechanisms as well as with some experiments carried out by our team. Authors acknowledge DGAPA-UNAM by support under project IN116312, ``Vorticidad y Ondas no lineales en fluidos.''

  8. Novel technology for hydrothermal treatment of NPP evaporator concentrates

    SciTech Connect

    Avramenko, Valentin; Dobrzhansky, Vitaly; Marinin, Dmitry; Sergienko, Valentin; Shmatko, Sergey

    2007-07-01

    A novel technology was developed for treatment of evaporator concentrates produced as a result of operation of evaporation devices comprising the main component of special water purification systems of nuclear power plants (NPP). The developed technology includes a hydrothermal (T=250-300 deg. C and P=80-120 bar) processing of evaporator concentrates in oxidation medium in order to destruct stable organic complexes of cobalt radionuclides and remove these radionuclides by oxide materials formed during such a processing. The cesium radionuclides contained in evaporator concentrates are removed by a conventional method-through application of one of the developed composite sorbents with ferrocyanides of transition metals used as active agents. Extensive laboratory studies of the processes occurring in evaporator concentrates under hydrothermal conditions were performed. It was shown that hydrothermal oxidation of evaporator concentrates has a number of advantages as compared to traditional oxidation methods (ozonization, photo-catalytic, electrochemical and plasma oxidation). A laboratory installation was built for the flow-type hydrothermal oxidation of NPP evaporator concentrates. The obtained experimental results showed good prospects for the developed method application. On the basis of the results obtained, a pilot installation of productivity up to 15 l/hour was developed and built in order to work out the technology of evaporator concentrates hydrothermal treatment. The pilot tests of the hydrothermal technology for evaporator concentrates hydrothermal treatment were performed for 6 months in 2006 at the 1. reactor unit of the Novovoronezhskaya NPP (Voronezh Region, Russia). Optimal technological regimes were determined, and estimations of the economic soundness of the technology were made. The advantages of the presented technology in terms of management of concentrated liquid radioactive wastes (LRW) at nuclear cycle facilities, as compared to other methods

  9. Characteristic lengths affecting evaporative drying of porous media.

    PubMed

    Lehmann, Peter; Assouline, Shmuel; Or, Dani

    2008-05-01

    Evaporation from porous media involves mass and energy transport including phase change, vapor diffusion, and liquid flow, resulting in complex displacement patterns affecting drying rates. Force balance considering media properties yields characteristic lengths affecting the transition in the evaporation rate from a liquid-flow-based first stage limited only by vapor exchange with air to a second stage controlled by vapor diffusion through the medium. The characteristic lengths determine the extent of the hydraulically connected region between the receding drying front and evaporating surface (film region) and the onset of flow rate limitations through this film region. Water is displaced from large pores at the receding drying front to supply evaporation from hydraulically connected finer pores at the surface. Liquid flow is driven by a capillary pressure gradient spanned by the width of the pore size distribution and is sustained as long as the capillary gradient remains larger than gravitational forces and viscous dissipation. The maximum extent of the film region sustaining liquid flow is determined by a characteristic length L_{C} combining the gravity characteristic length L_{G} and viscous dissipation characteristic length L_{V} . We used two sands with particle sizes 0.1-0.5 mm ("fine") and 0.3-0.9 mm ("coarse") to measure the evaporation from columns of different lengths under various atmospheric evaporative demands. The value of L_{G} determined from capillary pressure-saturation relationships was 90 mm for the coarse sand and 140 mm for the fine sand. A significant decrease in drying rate occurred when the drying front reached the predicted L_{G} value (viscous dissipation was negligibly small in sand and L_{C} approximately L_{G} ). The approach enables a prediction of the duration of first-stage evaporation with the highest water losses from soil to the atmosphere. PMID:18643163

  10. Corrosion study of simulated evaporator components

    SciTech Connect

    Schreiber, S.B.; Dunn, S.L.

    1989-07-01

    At the Los Alamos Plutonium Facility, ion exchange effluents and precipitation filtrates containing discardable levels of transuranic elements are concentrated using a thermosiphon evaporator before cement fixation for waste disposal. Because of changing process feed streams and scrap recovery requirements, trace amounts of free chloride ions (Cl/sup /minus//) are being introduced into the stainless steel (SS) evaporator, potentially increasing corrosion rates and thereby reducing its useful life. This study was performed to determine the effects of Cl/sup /minus// in simulated evaporator feed solutions that contain significant amounts of ferric ions (Fe/sup 3+/) in nitric acid (HNO/sub 3/). A simulated environment was produced by heating 316 SS cans that contained various tests solutions. The surface was monitored for signs of pitting or stress cracking, and vessel weight loss was measured on a daily basis to establish a rough corrosion rate. The final conclusion is that the nitric acid solution provides enough free nitrate ions (NO/sub 3//sup /minus//) to maintain minimal corrosion in a dilute ferric chloride environment. 3 refs., 5 figs., 10 tabs.

  11. An evaporation model of colloidal suspension droplets

    NASA Astrophysics Data System (ADS)

    Sartori, Silvana; Li\\ Nán, Amable; Lasheras, Juan C.

    2009-11-01

    Colloidal suspensions of polymers in water or other solvents are widely used in the pharmaceutical industry to coat tablets with different agents. These allow controlling the rate at which the drug is delivered, taste or physical appearance. The coating is performed by simultaneously spraying and drying the tablets with the colloidal suspension at moderately high temperatures. The spreading of the coating on the pills surface depends on the droplet Webber and Reynolds numbers, angle of impact, but more importantly on the rheological properties of the drop. We present a model for the evaporation of a colloidal suspension droplet in a hot air environment with temperatures substantially lower than the boiling temperature of the carrier fluid. As the liquid vaporizes from the surface, a compacting front advances into the droplet faster than the liquid surface regresses, forming a shell of a porous medium where the particles reach their maximum packing density. While the surface regresses, the evaporation rate is determined by both the rate at which heat is transported to the droplet surface and the rate at which liquid vapor is diffused away from it. This regime continues until the compacting front reaches the center of the droplet, at which point the evaporation rate is drastically reduced.

  12. An evaporation model of multicomponent solution drops

    NASA Astrophysics Data System (ADS)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.

    2010-11-01

    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  13. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    PubMed

    Karapetsas, George; Chandra Sahu, Kirti; Matar, Omar K

    2016-07-12

    We consider the flow dynamics of a thin evaporating droplet in the presence of an insoluble surfactant and noninteracting particles in the bulk. On the basis of lubrication theory, we derive a set of evolution equations for the film height, the interfacial surfactant, and bulk particle concentrations, taking into account the dependence of liquid viscosity on the local particle concentration. An important ingredient of our model is that it takes into account the fact that the surfactant adsorbed at the interface hinders evaporation. We perform a parametric study to investigate how the presence of surfactants affects the evaporation process as well as the flow dynamics with and without the presence of particles in the bulk. Our numerical calculations show that the droplet lifetime is affected significantly by the balance between the ability of the surfactant to enhance spreading, suppressing the effect of thermal Marangoni stresses-induced motion, and to hinder the evaporation flux through the reduction of the effective interfacial area of evaporation, which tend to accelerate and decelerate the evaporation process, respectively. For particle-laden droplets and in the case of dilute solutions, the droplet lifetime is found to be weakly dependent on the initial particle concentration. We also show that the particle deposition patterns are influenced strongly by the direct effect of the surfactant on the evaporative flux; in certain cases, the "coffee-stain" effect is enhanced significantly. A discussion of the delicate interplay between the effects of capillary pressure and solutal and thermal Marangoni stresses, which drive the liquid flow inside of the evaporating droplet giving rise to the observed results, is provided herein. PMID:27300638

  14. Reliable experimental setup to test the pressure modulation of Baerveldt Implant tubes for reducing post-operative hypotony

    NASA Astrophysics Data System (ADS)

    Ramani, Ajay

    Glaucoma encompasses a group of conditions that result in damage to the optic nerve and can cause loss of vision and blindness. The nerve is damaged due to an increase in the eye's internal (intraocular) pressure (IOP) above the nominal range of 15 -- 20 mm Hg. There are many treatments available for this group of diseases depending on the complexity and stage of nerve degradation. In extreme cases where drugs or laser surgery do not create better conditions for the patient, ophthalmologists use glaucoma drainage devices to help alleviate the IOP. Many drainage implants have been developed over the years and are in use; but two popular implants are the Baerveldt Glaucoma Implant and the Ahmed Glaucoma Valve Implant. Baerveldt Implants are non-valved and provide low initial resistance to outflow of fluid, resulting in post-operative complications such as hypotony, where the IOP drops below 5 mm of Hg. Ahmed Glaucoma Valve Implants are valved implants which initially restrict the amount of fluid flowing out of the eye. The long term success rates of Baerveldt Implants surpass those of Ahmed Valve Implants because of post-surgical issues; but Baerveldt Implants' initial effectiveness is poor without proper flow restriction. This drives the need to develop new ways to improve the initial effectiveness of Baerveldt Implants. A possible solution proposed by our research team is to place an insert in the Baerveldt Implant tube of inner diameter 305 microns. The insert must be designed to provide flow resistance for the early time frame [e.g., first 30 -- 60 post-operative days] until sufficient scar tissue has formed on the implant. After that initial stage with the insert, the scar tissue will provide the necessary flow resistance to maintain the IOP above 5 mm Hg. The main objective of this project was to develop and validate an experimental apparatus to measure pressure drop across a Baerveldt Implant tube, with and without inserts. This setup will be used in the

  15. Fixed-Combination Olmesartan/Amlodipine Was Superior to Perindopril + Amlodipine in Reducing Central Systolic Blood Pressure in Hypertensive Patients With Diabetes.

    PubMed

    Ruilope, Luis M

    2016-06-01

    This post hoc analysis from the Sevikar Compared to the Combination of Perindopril Plus Amlodipine on Central Arterial Blood Pressure in Patients With Moderate-to-Severe Hypertension (SEVITENSION) study assessed the efficacy and tolerability of olmesartan (OLM) and amlodipine (AML) in reducing central systolic blood pressure (CSBP) compared with perindopril (PER) plus AML in hypertensive patients with type 2 diabetes. Patients were randomized to OLM/AML 40/10 mg or PER/AML 8/10 mg for 24 weeks. The primary efficacy endpoint was the absolute change in CSBP from baseline to week 24, which was greater with OLM/AML (-13.72±1.14 mm Hg) compared with PER/AML (-10.21±1.11 mm Hg). The between-group difference was -3.51±1.60 mm Hg (95% confidence interval, -6.66 to -0.36 mm Hg) and was within the noninferiority margin (2 mm Hg) as well as the superiority margin (0 mm Hg). In addition, OLM/AML was associated with a higher proportion of patients achieving blood pressure normalization. In hypertensive patients with diabetes, the fixed-dose combination of OLM/AML was superior to PER/AML in reducing CSBP, as well as other secondary endpoints. PMID:26395174

  16. A model for calculation of RCS pressure during reflux boiling under reduced inventory conditions and its assessment against PKL data. [Reactor Cooling Systems (RCS)

    SciTech Connect

    Palmrose, D.E. ); Mandl, R.M. )

    1991-01-01

    There has been recent interest in the United States concerning the loss of residual heat removal system (RHRS) under reduced coolant inventory conditions for pressurized water reactors. This issue is also of interest in the Federal Republic of Germany and an experiment was performed in the integral PKL-HI experimental facility at Siemens-KWU to supply applicable data. Recently, an NRC-sponsored effort has been undertaken at the Idaho-National Engineering Laboratory to identify and analyze the important thermal-hydraulic phenomena in pressurized water reactors following the long term loss-of-RHRS during reduced inventory operation. The thermal-hydraulic response of a closed reactor coolant system during such a transient is investigated in this report. Some of the specific processes investigated include: reflux condensation in the steam generators, the corresponding pressure increase in the reactor coolant system, and void fraction distributions on the primary side of the system. Mathematical models of these and other physical processes Experiment B4.5.

  17. Simulations of diffusive lithium evaporation onto the NSTX vessel walls

    SciTech Connect

    Stotler, D.; Krstic, Predrag S; Skinner, C. H.; Blanchard, W.; Kugel, H.; Schneider, H; Zakharov, L. E.

    2011-01-01

    A model for simulating the diffusive evaporation of lithium into a helium filled NSTX vacuum vessel is described and validated against an initial set of deposition experiments. The DEGAS 2 based model consists of a three-dimensional representation of the vacuum vessel, the elastic scattering process, and a kinetic description of the evaporated atoms. Additional assumptions are required to account for deuterium out-gassing during the validation experiments. The model agrees with the data over a range of pressures to within the estimated uncertainties. Suggestions are made for more discriminating experiments that will lead to an improved model.

  18. A numerical simulation of heat transfer in evaporative cooling towers

    NASA Astrophysics Data System (ADS)

    Benton, D. J.

    1983-09-01

    A phenomenological analysis was developed for the processes which occur within an evaporative cooling tower. The analysis includes the basic principles of mass, momentum, and energy conservation and empirical elationships for component characteristics such as transfer and pressure drop coefficients. A computer model which simulates the processes occurring in evaporative cooling towers was developed. The results of this computer model are compared to field data to verify the analysis and the computer modeling. The computer model may be used to analyze the performance of existing towers or to predict the performance of alternative tower designs.

  19. Simulation of Diffusive Lithium Evaporation Onto the NSTX Vessel Walls

    SciTech Connect

    Stotler, D. P.; Skinner, C. H.; Blanchard, W. R.; Krstic, P. S.; Kugel, H. W.; Schneider, H.; Zakharov, L. E.

    2010-12-09

    A model for simulating the diffusive evaporation of lithium into a helium filled NSTX vacuum vessel is described and validated against an initial set of deposition experiments. The DEGAS 2 based model consists of a three-dimensional representation of the vacuum vessel, the elastic scattering process, and a kinetic description of the evaporated atoms. Additional assumptions are required to account for deuterium out-gassing during the validation experiments. The model agrees with the data over a range of pressures to within the estimated uncertainties. Suggestions are made for more discriminating experiments that will lead to an improved model.

  20. Milestone Report #2: Direct Evaporator Leak and Flammability Analysis Modifications and Optimization of the Organic Rankine Cycle to Improve the Recovery of Waste Heat

    SciTech Connect

    Donna Post Guillen

    2013-09-01

    The direct evaporator is a simplified heat exchange system for an Organic Rankine Cycle (ORC) that generates electricity from a gas turbine exhaust stream. Typically, the heat of the exhaust stream is transferred indirectly to the ORC by means of an intermediate thermal oil loop. In this project, the goal is to design a direct evaporator where the working fluid is evaporated in the exhaust gas heat exchanger. By eliminating one of the heat exchangers and the intermediate oil loop, the overall ORC system cost can be reduced by approximately 15%. However, placing a heat exchanger operating with a flammable hydrocarbon working fluid directly in the hot exhaust gas stream presents potential safety risks. The purpose of the analyses presented in this report is to assess the flammability of the selected working fluid in the hot exhaust gas stream stemming from a potential leak in the evaporator. Ignition delay time for cyclopentane at temperatures and pressure corresponding to direct evaporator operation was obtained for several equivalence ratios. Results of a computational fluid dynamic analysis of a pinhole leak scenario are given.

  1. Salt stains from evaporating droplets.

    PubMed

    Shahidzadeh, Noushine; Schut, Marthe F L; Desarnaud, Julie; Prat, Marc; Bonn, Daniel

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls , but also very important in many applications such as purification of pharmaceuticals, de-icing of airplanes, inkjet printing and coating applications. In many of these processes, a phase change happens within the drop because of solvent evaporation, temperature changes or chemical reactions, which consequently lead to liquid to solid transitions in the droplets. Here we show that crystallization patterns of evaporating of water drops containing dissolved salts are different from the stains reported for evaporating colloidal suspensions. This happens because during the solvent evaporation, the salts crystallize and grow during the drying. Our results show that the patterns of the resulting salt crystal stains are mainly governed by wetting properties of the emerging crystal as well as the pathway of nucleation and growth, and are independent of the evaporation rate and thermal conductivity of the substrates. PMID:26012481

  2. Reservoir evaporation in central Colorado

    USGS Publications Warehouse

    Spahr, N.E.; Ruddy, B.C.

    1983-01-01

    Evaporation losses from seven reservoirs operated by the Denver Water Department in central Colorado were determined during various periods from 1974 to 1980. The reservoirs studies were Ralston, Cheesman, Antero, Williams Fork, Elevenmile Canyon, Dillon, and Gross. Energy-budget and mass-transfer methods were used to determine evaporation. Class-A pan data also were collected at each reservoir. The energy-budget method was the most accurate of the methods used to determine evaporation. At Ralston, Cheesman, Antero, and Williams Fork Reservoirs the energy-budget method was used to calibrate the mass-transfer coefficients. Calibrated coefficients already were available for Elevenmile Canyon, Dillon, and Gross Reservoirs. Using the calibrated coefficients, long-term mass-transfer evaporation rates were determined. Annual evaporation values were not determined because the instrumentation was not operated for the entire open-water season. Class-A pan data were used to determine pan coefficients for each season at each reservoir. The coefficients varied from season to season and between reservoirs, and the seasonal values ranged from 0.29 to 1.05. (USGS)

  3. Salt stains from evaporating droplets

    PubMed Central

    Shahidzadeh, Noushine; Schut, Marthe F. L.; Desarnaud, Julie; Prat, Marc; Bonn, Daniel

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls , but also very important in many applications such as purification of pharmaceuticals, de-icing of airplanes, inkjet printing and coating applications. In many of these processes, a phase change happens within the drop because of solvent evaporation, temperature changes or chemical reactions, which consequently lead to liquid to solid transitions in the droplets. Here we show that crystallization patterns of evaporating of water drops containing dissolved salts are different from the stains reported for evaporating colloidal suspensions. This happens because during the solvent evaporation, the salts crystallize and grow during the drying. Our results show that the patterns of the resulting salt crystal stains are mainly governed by wetting properties of the emerging crystal as well as the pathway of nucleation and growth, and are independent of the evaporation rate and thermal conductivity of the substrates. PMID:26012481

  4. Calculation of Reactive-evaporation Rates of Chromia

    SciTech Connect

    Holcomb, G.R.

    2008-04-01

    A methodology is developed to calculate Cr-evaporation rates from Cr2O3 with a flat planar geometry. Variables include temperature, total pressure, gas velocity, and gas composition. The methodology was applied to solid-oxide, fuel cell conditions for metallic interconnects and to advanced-steam turbines conditions. The high velocities and pressures of the advanced steam turbine led to evaporation predictions as high as 5.18 9 10-8 kg/m2/s of CrO2(OH)2(g) at 760 °C and 34.5 MPa. This is equivalent to 0.080 mm per year of solid Cr loss. Chromium evaporation is expected to be an important oxidation mechanism with the types of nickel-base alloys proposed for use above 650 °C in advanced-steam boilers and turbines. It is shown that laboratory experiments, with much lower steam velocities and usually much lower total pressure than found in advanced steam turbines, would best reproduce chromium-evaporation behavior with atmospheres that approach either O2 + H2O or air + H2O with 57% H2O.

  5. Dewetting of evaporating thin films over nanometer-scale topographies

    NASA Astrophysics Data System (ADS)

    Akbarzadeh, A. M.; Moosavi, A.; Moghimi Kheirabadi, A.

    2014-07-01

    A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time.

  6. Tubular sublimatory evaporator heat sink

    NASA Technical Reports Server (NTRS)

    Webbon, B. W. (Inventor)

    1977-01-01

    An evaporative refrigerator or cooler comprising a bundle of spaced, porous walled tubes closed at one of their ends and vented to a vacuum at the other end is disclosed. The tube bundle is surrounded by a water jacket having a hot water inlet distribution manifold and a cooled water outlet through a plenum chamber. Hot water is pumped into the jacket to circulate around the tubes, and when this water meets the vacuum existing inside the tubes, it evaporates thereby cooling the water in the jacket. If cooling proceeds to the point where water penetrating or surrounding all or part of the tubes freezes, operation continues with local sublimation of the ice on the tubes while the circulating water attempts to melt the ice. Both sublimation and evaporation may take place simultaneously in different regions of the device.

  7. Evaporation duct communication: Test Plan

    NASA Astrophysics Data System (ADS)

    Anderson, K. D.

    1991-02-01

    The Evaporation Duct Communication (EDCOM) project is an effort to provide an alternative ship-to-ship communications channel using the natural environment. A microwave communication link can be used on an over-the-water, over-the-horizon path through the evaporation duct. This report shows how a microwave communication link, operating at a range separation of more than twice the line-of-sight range, can be constructed. This link can achieve about 80-percent availability at a transmission frequency of 14.5 GHz and can be constructed using off-the-shelf RF equipment. Operation of this link will provide the first set of measurements of channel capacity that can be critically dependent on the existence of an oceanic evaporation duct. Construction of this link presents a unique opportunity to study and evaluate an alternative communications channel that can be used to alleviate naval battlegroup communications load.

  8. Estimating daily pan evaporation using adaptive neural-based fuzzy inference system

    NASA Astrophysics Data System (ADS)

    Keskin, M. Erol; Terzi, Özlem; Taylan, Dilek

    2009-09-01

    Estimation of evaporation is important for water planning, management, and hydrological practices. There are many available methods to estimate evaporation from a water surface, comprising both direct and indirect methods. All the evaporation models are based on crisp conceptions with no uncertainty element coupled into the model structure although in daily evaporation variations there are uncontrollable effects to a certain extent. The probabilistic, statistical, and stochastic approaches require large amounts of data for the modeling purposes and therefore are not practical in local evaporation studies. It is therefore necessary to adopt a better approach for evaporation modeling, which is the fuzzy sets and adaptive neural-based fuzzy inference system (ANFIS) as used in this paper. ANFIS and fuzzy sets have been evaluated for its applicability to estimate evaporation from meteorological data which is including air and water temperatures, solar radiation, and air pressure obtained from Automated GroWheather meteorological station located near Lake Eğirdir and daily pan evaporation values measured by XVIII. District Directorate of State Hydraulic Works. Results of ANFIS and fuzzy logic approaches were analyzed and compared with measured daily pan evaporation values. ANFIS approach could be employed more successfully in modeling the evaporation process than fuzzy sets.

  9. On the theory relating changes in area-average and pan evaporation (Invited)

    NASA Astrophysics Data System (ADS)

    Shuttleworth, W.; Serrat-Capdevila, A.; Roderick, M. L.; Scott, R.

    2009-12-01

    Theory relating changes in area-average evaporation with changes in the evaporation from pans or open water is developed. Such changes can arise by Type (a) processes related to large-scale changes in atmospheric concentrations and circulation that modify surface evaporation rates in the same direction, and Type (b) processes related to coupling between the surface and atmospheric boundary layer (ABL) at the landscape scale that usually modify area-average evaporation and pan evaporation in different directions. The interrelationship between evaporation rates in response to Type (a) changes is derived. They have the same sign and broadly similar magnitude but the change in area-average evaporation is modified by surface resistance. As an alternative to assuming the complementary evaporation hypothesis, the results of previous modeling studies that investigated surface-atmosphere coupling are parameterized and used to develop a theoretical description of Type (b) coupling via vapor pressure deficit (VPD) in the ABL. The interrelationship between appropriately normalized pan and area-average evaporation rates is shown to vary with temperature and wind speed but, on average, the Type (b) changes are approximately equal and opposite. Long-term Australian pan evaporation data are analyzed to demonstrate the simultaneous presence of Type (a) and (b) processes, and observations from three field sites in southwestern USA show support for the theory describing Type (b) coupling via VPD. England's victory over Australia in 2009 Ashes cricket test match series will not be mentioned.

  10. Evaporation kinetics of laboratory-generated secondary organic aerosols at elevated relative humidity.

    PubMed

    Wilson, Jacqueline; Imre, Dan; Beránek, Josef; Shrivastava, Manish; Zelenyuk, Alla

    2015-01-01

    Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semisolid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on α-pinene SOA particles generated, evaporated, and aged at <5%, 50 and 90% RH, and on limonene SOA particles at <5% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30-70% of the particle mass evaporates in 2 h, followed by a much slower evaporation rate. Evaporation kinetics at <5% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses; with aging at elevated RH leading to a more significant effect. In all cases, the observed SOA evaporation is nearly size-independent. PMID:25494490

  11. Predicting Potential Evaporation in Topographically Complex Terrain

    NASA Astrophysics Data System (ADS)

    Koohafkan, M.; Thompson, S. E.; Hamilton, M. P.

    2012-12-01

    Predicting and understanding the water cycle in topographically complex terrain poses challenges for upscaling point-scale measurements of water and energy balance and for downscaling observations made from remote sensing or predictions made via global circulation models. This study evaluates hydrologic and climate data drawn from a spatially-distributed wireless sensor network at the Blue Oak Ranch Reserve near San Jose, California to investigate the influence of topographic variation, landscape position, and local ecology (vegetation) on one core component of the water balance: potential evaporation. High-resolution observations of solar radiation, ambient temperature, wind speed, and relative humidity are combined with canopy maps generated from LiDAR flyovers to develop spatially-distributed predictions of potential evaporation. These data are compared to estimates of EP based on inverse modeling of surface soil moisture data. Preliminary results suggest that the spatial structure of microclimate at Blue Oak Ranch Reserve is dominated by variations around the elevation gradient, with strong nocturnal inversions hypothesized to reflect the influence of the coastal marine layer. Estimates of EP based on the Penman-Monteith equation suggest that EP could vary by up to a factor of 5 across the site, with differences in vapor pressure deficit and canopy height largely responsible for this variability. The results suggest that a) large differences in the timing and magnitude of water stress could arise in topographically complex terrain due to localized differences in energy balance, and b) both localized and regional effects need to be accounted for when downscaling climate data over topographically complex sites. 2) Color map showing preliminary estimates of annual EP incorporating canopy information (spatially-distributed values of aerodynamic resistance and LAI) drawn from LiDAR imagery. The effect of the resistance on the dynamics is striking in its ability to

  12. The effect of evaporator operating parameters on the flow patterns inside horizontal pipes

    NASA Astrophysics Data System (ADS)

    Tong, Lige; Li, Haiyan; Wang, Li; Sun, Xinxing; Xie, Yunfei

    2011-08-01

    A general and simple model for simulating the steady state behaviors of air-to-refrigerant fin-and-tube evaporator is introduced with the focus on the detailed flow patterns inside the tubes. In order to simulate the heat transfer between air and the working fluid, the evaporator is divided into a number of control volumes. Empirical correlations from literature were also adopted to estimate the void fraction, the internal and external heat transfer coefficients, and the pressure drops. Simulations were performed to study the effects of varying inlet air temperature, refrigerant mass flow rate and evaporation pressure on the flow patterns inside the horizontal pipe of the evaporator. The simulation results indicate that the proposed model can be used to predict flow patterns well. The predicted results of the model agree well with experimental results, the difference is within ±3% for the cooling capacity, and is within ±0.2% for refrigerant evaporation temperature.

  13. Anaerobic granule-based biofilms formation reduces propionate accumulation under high H2 partial pressure using conductive carbon felt particles.

    PubMed

    Xu, Heng; Wang, Cuiping; Yan, Kun; Wu, Jing; Zuo, Jiane; Wang, Kaijun

    2016-09-01

    Syngas based co-digestion is not only more economically attractive than separate syngas methanation but also able to upgrade biogas and increase overall CH4 amount simultaneously. However, high H2 concentration in the syngas could inhibit syntrophic degradation of propionate, resulting in propionate accumulation and even failure of the co-digestion system. In an attempt to reduce propionate accumulation via enhancing both H2 interspecies transfer (HIT) and direct interspecies electron transfer (DIET) pathways, layered granule-based biofilms induced by conductive carbon felt particles (CCFP) was employed. The results showed that propionate accumulation was effectively reduced with influent COD load up to 7gL(-1)d(-1). Two types of granule-based biofilms, namely biofilm adhered to CCFP (B-CCFP) and granules formed by self-immobilization (B-SI) were formed in the reactor. Clostridium, Syntrophobacter, Methanospirillum were possibly involved in HIT and Clostridium, Geobacter, Anaerolineaceae, Methanosaeta in DIET, both of which might be responsible for the high-rate propionate degradation. PMID:27289059

  14. Evaporation of primordial black holes

    NASA Astrophysics Data System (ADS)

    Hawking, S. W.

    The usual explanation of the isotropy of the universe is that inflation would have smoothed out any inhomogeneities. However, if the universe was initially fractal or in a foam like state, an overall inflation would have left it in the same state. I suggest that the universe did indeed begin with a tangled web of wormholes connecting pairs of black holes but that the inflationary expansion was unstable: wormholes that are slightly smaller correspond to black holes that are hotter than the cosmological background and evaporate away. This picture is supported by calculations with Raphael Bousso of the evaporation of primordial black holes in the s-wave and large N approximations.

  15. 1998 242-A interim evaporator tank system integrity assessment plan

    SciTech Connect

    Jensen, C.E.

    1998-03-31

    Portions of the 242-A Evaporator on the Hanford Site must be assessed to meet the requirements of the Washington State Department of Ecology`s Dangerous Waste Regulation, Washington Administrative Code (WAC) 173-303. The assessment is limited to the provisions of Section 173-303-640. This Integrity Assessment Plan (IAP) identifies tasks which will be performed during the assessment phase and describes the intended assessment techniques. The 242-A Evaporator facility processes waste solutions from most of the operating laboratories and plants of the Hanford Site. The waste solutions are concentrated in the evaporator to a slurry of liquid and crystallized salts. This concentrated slurry is returned to the Tank Farms at a significantly reduce volume. The water vapor from the evaporation process is condensed, filtered, and can be pumped through an ion exchange bed before transfer to a retention basin. The non-condensable portion of the vapor is filtered and continuously monitored before venting to the atmosphere. The 242-A Evaporator will be assessed as seven subsystems. Four of the subsystems store, transport or treat Washington State Dangerous wastes, the other three subsystems are integral parts of the process, however, they do not directly store, transfer, or treat listed dangerous wastes. The facility will be inspected, tested, and analyzed through this assessment. The seven subsystems, defined in detail in Appendix B, are: Evaporator Process and Slurry Subsystem; Vapor Condenser Subsystem; Vessel Vent Subsystem; Process Condensate Subsystem; Steam Condensate Subsystem; Raw Water Disposal Subsystem; and Building and Secondary Containment Subsystem.

  16. Reducing Biogenic-Amine-Producing Bacteria, Decarboxylase Activity, and Biogenic Amines in Raw Milk Cheese by High-Pressure Treatments

    PubMed Central

    Calzada, Javier; del Olmo, Ana; Picón, Antonia; Gaya, Pilar

    2013-01-01

    Biogenic amines may reach concentrations of public health concern in some cheeses. To minimize biogenic amine buildup in raw milk cheese, high-pressure treatments of 400 or 600 MPa for 5 min were applied on days 21 and 35 of ripening. On day 60, counts of lactic acid bacteria, enterococci, and lactobacilli were 1 to 2 log units lower in cheeses treated at 400 MPa and 4 to 6 log units lower in cheeses treated at 600 MPa than in control cheese. At that time, aminopeptidase activity was 16 to 75% lower in cheeses treated at 400 MPa and 56 to 81% lower in cheeses treated at 600 MPa than in control cheese, while the total free amino acid concentration was 35 to 53% higher in cheeses treated at 400 MPa and 3 to 15% higher in cheeses treated at 600 MPa, and decarboxylase activity was 86 to 96% lower in cheeses treated at 400 MPa and 93 to 100% lower in cheeses treated at 600 MPa. Tyramine, putrescine, and cadaverine were the most abundant amines in control cheese. The total biogenic amine concentration on day 60, which reached a maximum of 1.089 mg/g dry matter in control cheese, was 27 to 33% lower in cheeses treated at 400 MPa and 40 to 65% lower in cheeses treated at 600 MPa. On day 240, total biogenic amines attained a concentration of 3.690 mg/g dry matter in control cheese and contents 11 to 45% lower in cheeses treated at 400 MPa and 73 to 76% lower in cheeses treated at 600 MPa. Over 80% of the histidine and 95% of the tyrosine had been converted into histamine and tyramine in control cheese by day 60. Substrate depletion played an important role in the rate of biogenic amine buildup, becoming a limiting factor in the case of some amino acids. PMID:23241980

  17. Gradual Rewarming with Gradual Increase in Pressure during Machine Perfusion after Cold Static Preservation Reduces Kidney Ischemia Reperfusion Injury

    PubMed Central

    Mahboub, Paria; Ottens, Petra; Seelen, Marc; t Hart, Nails; Van Goor, Harry; Ploeg, Rutger; Martins, Paulo; Leuvenink, Henri

    2015-01-01

    In this study we evaluated whether gradual rewarming after the period of cold ischemia would improve organ quality in an Isolated Perfused Kidney Model. Left rat kidneys were statically cold stored in University of Wisconsin solution for 24 hours at 4°C. After cold storage kidneys were rewarmed in one of three ways: perfusion at body temperature (38°C), or rewarmed gradually from 10°C to 38°C with stabilization at 10°C for 30 min and rewarmed gradually from 10°C to 38°C with stabilization at 25°C for 30 min. In the gradual rewarming groups the pressure was increased stepwise to 40 mmHg at 10°C and 70 mmHg at 25°C to counteract for vasodilatation leading to low perfusate flows. Renal function parameters and injury biomarkers were measured in perfusate and urine samples. Increases in injury biomarkers such as aspartate transaminase and lactate dehydrogenase in the perfusate were lower in the gradual rewarming groups versus the control group. Sodium re-absorption was improved in the gradual rewarming groups and reached significance in the 25°C group after ninety minutes of perfusion. HSP-70, ICAM-1, VCAM-1 mRNA expressions were decreased in the 10°C and 25°C groups. Based on the data kidneys that underwent gradual rewarming suffered less renal parenchymal, tubular injury and showed better endothelial preservation. Renal function improved in the gradual rewarming groups versus the control group. PMID:26630031

  18. Casein-Derived Lactotripeptides Reduce Systolic and Diastolic Blood Pressure in a Meta-Analysis of Randomised Clinical Trials

    PubMed Central

    Fekete, Ágnes A.; Givens, D. Ian; Lovegrove, Julie A.

    2015-01-01

    There is an urgent need to treat individuals with high blood pressure (BP) with effective dietary strategies. Previous studies suggest a small, but significant decrease in BP after lactotripeptides (LTP) ingestion, although the data are inconsistent. The study aim was to perform a comprehensive meta-analysis of data from all relevant randomised controlled trials (RCT). Medline, Cochrane library, EMBASE and Web of Science were searched until May 2014. Eligibility criteria were RCT that examined the effects of LTP on BP in adults, with systolic BP (SBP) and diastolic BP (DBP) as outcome measures. Thirty RCT met the inclusion criteria, which resulted in 33 sets of data. The pooled treatment effect for SBP was −2.95 mmHg (95% CI: −4.17, −1.73; p < 0.001), and for DBP was −1.51 mmHg (95% CI: −2.21, −0.80; p < 0.001). Sub-group analyses revealed that reduction of BP in Japanese studies was significantly greater, compared with European studies (p = 0.002 for SBP and p < 0.001 for DBP). The 24-h ambulatory BP (AMBP) response to LTP supplementation was statistically non-significant (p = 0.101 for SBP and p = 0.166 for DBP). Both publication bias and “small-study effect” were identified, which shifted the treatment effect towards less significant SBP and non-significant DBP reduction after LTP consumption. LTP may be effective in BP reduction, especially in Japanese individuals; however sub-group, meta-regression analyses and statistically significant publication biases suggest inconsistencies. PMID:25608938

  19. Fundamental study of evaporation model in micron pore

    NASA Astrophysics Data System (ADS)

    Oinuma, Ryoji

    As the demand for high performance small electronic devices has increased, heat removal from these devices for space use is approaching critical limits. A heat pipe is a promising device to enhance the heat removal performance due to the phase change phenomena for space thermal management system. Even though a heat pipe has a big potential to remove the thermal energy from a high heat flux source, the heat removal performance of heat pipes cannot be predicted well since the first principle of evaporation has not been established. The purpose of this study is to establish a method to apply the evaporation model based on the statistical rate theory for engineering application including vapor-liquid-structure intermolecular effect. The evaporation model is applied to the heat pipe performance analysis through a pressure balance and an energy balance in the loop heat pipe.

  20. Vacuum Evaporation Technology for Treating Antimony-Rich Anode Slime

    NASA Astrophysics Data System (ADS)

    Qiu, Keqiang; Lin, Deqiang; Yang, Xuelin

    2012-11-01

    A vacuum evaporation technology for treating antimony-rich anode slime was developed in this work. Experiments were carried out at temperatures from 873 K to 1073 K and residual gas pressures from 50 Pa to 600 Pa. During vacuum evaporation, silver from the antimony-rich anode slime was left behind in the distilland in a silver alloy containing antimony and lead, and antimony trioxide was evaporated. The experimental results showed that 92% by weight of antimony can be removed, and the silver content in the alloy was up to 12.84%. The antimony trioxide content in the distillate was more than 99.7%, and the distillate can be used directly as zero-grade antimony trioxide (China standard).

  1. Evaporation by mechanical vapor recompression. Technical progress report, April 1, 1980-June 30, 1980

    SciTech Connect

    Iverson, C.H.; Coury, G.E.

    1980-01-01

    The expected performance and estimated capital cost are presented of two schemes for the application of mechanical vapor recompression to a conventional, low pressure, five effect juice evaporator in a beet sugar factory. Due to the constraints of the existing system and the desire to make the most effective use of the capital investment, the recommendation is to install Scheme B. This selection recognizes the inability of the falling film evaporator to respond to rapid and frequent changes in capacity, and upon the need to raise the first effect vapor pressure to allow utilization of first effect bleed vapor to boil the white sugar crystallization pan. The recommended installation, Scheme B, is predicted to reduce the hourly steam consumption by up to 10,477 number/hr for an annual fuel savings of $126,800 on today's fuel cost at the Greeley Factory of the Great Western Sugar Company. This represents a 9.35% reduction in the amount of steam generated during the base year of 1978 to 1979. The estimated capital cost of the installation is $825,000.

  2. Influence of Oil on Refrigerant Evaporator Performance

    NASA Astrophysics Data System (ADS)

    Jong-Soo, Kim; Nagata, Katsuya; Katsuta, Masafumi; Tomosugi, Hiroyuki; Kikuchi, Kouichiro; Horichi, Toshiaki

    To explore the quantitative effect of the lubrication oil on the thermal and hydraulic evaporator performance, the detailed structure of two-phase refrigerant (R11) and lubrication oil (Suniso 5GS) flow has been investigated. Experiment has been performed using a transparent tube 20mm in inner diameter and 2600mm in total length as main test section, which was heated by surrounding hot water bath. This water bath also functioned as the visual observation section of the transition of two-phase flow pattern. Oil mass concentration was controlled initially, and circulated into the system. The void fraction at the main test section was measured by direct volume measurement using so-called "Quick Closing Valve" method. Since the effect of oil on the transition of two-phase flow pattern is emphasized at the low flow rate, operation was made at relatively low mass velocity, 50 and 100 kg/m2·s, five different oil concentrations were taken. Throughout the experiment, the evaporation pressure was kept at 105 kPa. In general, when contamination of the lubrication oil happened, the void fraction was decreasing due to the change of viscosity and surface tension and the occurence of the foaming. To correlate the void fraction as function of quality, Zivi's expression was modified to include the effect of oil concentration. The agreement between the data and this proposed correlation was favorable. Finally, to take into account the effect of lubrication oil, the new flow pattern diagram was proposed.

  3. Timing of surgical treatment for idiopathic normal pressure hydrocephalus: association between treatment delay and reduced short-term benefit.

    PubMed

    Vakili, Sharif; Moran, Dane; Hung, Alice; Elder, Benjamin D; Jeon, Lee; Fialho, Hugo; Sankey, Eric W; Jusué-Torres, Ignacio; Goodwin, C Rory; Lu, Jennifer; Robison, Jamie; Rigamonti, Daniele

    2016-09-01

    OBJECTIVE A growing body of evidence suggests that longer durations of preoperative symptoms may correlate with worse postoperative outcomes following cerebrospinal fluid (CSF) diversion for treatment of idiopathic normal pressure hydrocephalus (iNPH). The aim of this study is to determine whether the duration of preoperative symptoms alters postoperative outcomes in patients treated for iNPH. METHODS The authors conducted a retrospective review of 393 cases of iNPH involving patients treated with ventriculoperitoneal (VP) shunting. The duration of symptoms prior to the operative intervention was recorded. The following outcome variables were assessed at baseline, 6 months postoperatively, and at last follow-up: gait performance, urinary continence, and cognition. RESULTS The patients' median age at shunt placement was 74 years. Increased symptom duration was significantly associated with worse gait outcomes (relative risk (RR) 1.055 per year of symptoms, p = 0.037), and an overall absence of improvement in any of the classic triad symptomology (RR 1.053 per year of symptoms, p = 0.033) at 6 months postoperatively. Additionally, there were trends toward significance for symptom duration increasing the risk of having no 6-month postoperative improvement in urinary incontinence (RR 1.049 per year of symptoms, p = 0.069) or cognitive symptoms (RR 1.051 per year of symptoms, p = 0.069). However, no statistically significant differences were noted in these outcomes at last follow-up (median 31 months). Age stratification by decade revealed that prolonging symptom duration was significantly associated with lower Mini-Mental Status Examination scores in patients aged 60-70 years, and lack of cognitive improvement in patients aged 70-80 years. CONCLUSIONS Patients with iNPH with longer duration of preoperative symptoms may not receive the same short-term benefits of surgical intervention as patients with shorter duration of preoperative symptoms. However, with longer

  4. Assessment of the Multi-Fluid Evaporator Technology

    NASA Astrophysics Data System (ADS)

    Quinn, Gregory; O'Connor, Edward

    2008-01-01

    Hamilton Sundstrand has developed a scalable evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It was designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used as a heat sink from Earth sea level conditions to the vacuum of space. The current shuttle configuration utilizes an ammonia boiler and water based flash evaporator system to achieve cooling at all altitudes. This system combines both functions into a single compact package with improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. A full-scale system uses multiple core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A single-core MFE engineering development unit (EDU) was built in 2006, followed by a full scale, four-core prototype in 2007. The EDU underwent extensive thermal testing while the prototype was being built. Lessons learned from the EDU were incorporated into the prototype and proven out in check-out testing. The EDU and prototype testing proved out the MFE's ability to passively control back-pressure, avoid unwanted icing, tolerate icing if it should occur, provide a three-to-one turn down ratio in heat load and scale up efficiently. Some issues with these first designs of the MFE have limited its ability to reject heat without liquid evaporant carry-over. However, they are due to the implementation of the design rather than the fundamentals of the technology. This paper discusses the background, development and present state of the Multi-Fluid Evaporator technology and concludes with efforts underway to advance the state-of-the-art.

  5. Does the use of primary continuous positive airway pressure reduce the need for intubation and mechanical ventilation in infants ≤32 weeks’ gestation?

    PubMed Central

    Yee, Wendy H; Scotland, Jeanne; Pham, Yung; Finch, Robert

    2011-01-01

    BACKGROUND: Ventilator-induced lung injury is a recognized risk factor for bronchopulmonary dysplasia. OBJECTIVE: To determine whether primary continuous positive airway pressure (CPAP), defined as CPAP without previous endotracheal intubation for any indication, can reduce the need for intubation and mechanical ventilation in infants born at ≤32 weeks’ gestational age. METHODS: The literature was reviewed using the methodology for systematic reviews for the Consensus on Resuscitation Science adapted from the American Heart Association’s International Liaison Committee on Resuscitation. RESULTS: Fourteen studies were reviewed. Eleven studies provided varying degrees of supportive evidence (level of evidence 3 to 4) that the use of primary CPAP can reduce the need for intubation and mechanical ventilation. CONCLUSION: The use of CPAP as a primary intervention and mode of respiratory support is an option for infants ≤32 weeks’ gestation, but avoidance of intubation and mechanical ventilation is more likely in mature infants >27 weeks’ gestation. PMID:23204903

  6. Influence of electron evaporative cooling on ultracold plasma expansion

    SciTech Connect

    Wilson, Truman; Chen, Wei-Ting; Roberts, Jacob

    2013-07-15

    The expansion of ultracold neutral plasmas (UCP) is driven primarily by the thermal pressure of the electron component and is therefore sensitive to the electron temperature. For typical UCP spatial extents, evaporative cooling has a significant influence on the UCP expansion rate at lower densities (less than 10{sup 8}/cm{sup 3}). We studied the effect of electron evaporation in this density range. Owing to the low density, the effects of three-body recombination were negligible. We modeled the expansion by taking into account the change in electron temperature owing to evaporation as well as adiabatic expansion and found good agreement with our data. We also developed a simple model for initial evaporation over a range of ultracold plasma densities, sizes, and electron temperatures to determine over what parameter range electron evaporation is expected to have a significant effect. We also report on a signal calibration technique, which relates the signal at our detector to the total number of ions and electrons in the ultracold plasma.

  7. Instability of evaporation fronts in the interstellar medium

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2013-12-10

    The neutral component of the interstellar medium is segregated into the cold neutral medium (CNM) and warm neutral medium (WNM) as a result of thermal instability. It was found that a plane-parallel CNM-WNM evaporation interface, across which the CNM undergoes thermal expansion, is linearly unstable to corrugational disturbances, in complete analogy with the Darrieus-Landau instability (DLI) of terrestrial flames. We perform a full linear stability analysis as well as nonlinear hydrodynamic simulations of the DLI of such evaporation fronts in the presence of thermal conduction. We find that the DLI is suppressed at short length scales by conduction. The length and time scales of the fastest growing mode are inversely proportional to the evaporation flow speed of the CNM and its square, respectively. In the nonlinear stage, the DLI saturates to a steady state where the front deforms to a finger-like shape protruding toward the WNM, without generating turbulence. The evaporation rate at nonlinear saturation is larger than the initial plane-parallel value by a factor of ∼2.4 when the equilibrium thermal pressure is 1800 k {sub B} cm{sup –3} K. The degrees of front deformation and evaporation-rate enhancement at nonlinear saturation are determined primarily by the density ratio between the CNM and WNM. We demonstrate that the Field length in the thermally unstable medium should be resolved by at least four grid points to obtain reliable numerical outcomes involving thermal instability.

  8. Evaporation and radiation measurements at Salton Sea, California

    USGS Publications Warehouse

    Sturrock, Alex M.

    1977-01-01

    Evaporation from the Salton Sea, Calif., was computed for a 539-day period between July 14, 1967, and January 2, 1969, by use of energy-budget, mass-transfer, and water budget methods. The total evaporation computed by the three methods agreed within 5 percent. The values of heat transfer to and from the bed were used in the energy-budget computations. Monthly evaporation computed by the energy-budget method for 1968 showed that the Salton Sea exhibited a double wave evaporation similar to that of oceans in the same latitude. Weekly and montly comparisons were made to determine if radiation measured by the flat-plate radiometer is seasonally biased. These comparisons indicate that the measurements of radiation by the flat-plate radiometer are not seasonally biased, and that the Cummings Radiation Integrator gives reliable measurements of radiation for periods as short as 1 week. An empirical mass-transfer coefficient, N, as determined from energy-budget measurements. The value of this coefficient to give evaporation in inches per day is 0.00245 when the windspeed is expressed in miles per hour and the vapor pressure expressed in millibars. (Woodard-USGS)

  9. Evaporation from Lake Kinneret, Israel, during hot summer days

    NASA Astrophysics Data System (ADS)

    Shilo, Elad; Ziv, Baruch; Shamir, Eylon; Rimmer, Alon

    2015-09-01

    The relationships between the evaporation from a medium size (168.7 km2) Lake Kinneret (Northern Israel), and its governing synoptic factors are well demonstrated during the summer of 2010. During July-August the daily temperature of the air and water surface were ∼2-4 °C higher, the daily wind over the lake was ∼80% weaker, and the evaporation from the lake was ∼5% lower than the long-term July-August mean. In this study, we explore the impact of the regional and local synoptic-scale atmospheric conditions on the evaporation from the lake during exceptionally hot days in the mid-summer months (July-August). The factors that were found to be correlated with the lake evaporation are the temperatures at 850 hPa (negative) and 500 hPa (positive), the sea level pressure difference between Northern Egypt and Armenia (positive), and the height of the marine inversion (positive). Synoptic analysis indicates that two conditions are responsible for the reduction of the Mediterranean Sea Breeze (MSB) during exceptionally hot days, and consequently to the reduction of evaporation from the lake. First, the weakening of the permanent synoptic Etesian winds, which otherwise supports the inland penetration of the MSB; and second, the descent of the marine inversion to a height below the topographic ridge of the Galilee Mountains upwind of the study area, which blocks the Marine Sea Breeze from reaching Lake Kinneret.

  10. Harnessing Nanoparticles to Control Evaporation at Liquid-Vapor Interfaces

    NASA Astrophysics Data System (ADS)

    Yong, Xin

    2015-11-01

    It is well known that nanoparticles with appropriate size and surface chemistry adsorb to liquid-vapor interfaces and consequently modify the mechanical properties of the interfaces. However, little has been explored about the effect of nanoparticles on the heat transfer occurring at the interfaces. Using many-body dissipative particle dynamics (MDPD), we model an evaporating interface with adsorbed nanoparticles. Homogeneous and amphiphilic Janus nanoparticles, which contain hydrophobic and hydrophobic surface regions, are considered in this study. We measure the variation in the evaporation rates of the interface by gradually increasing particle loading until a hexagonal-close-packed monolayer is achieved. We explore the effect of surface chemistry and surface composition of the particles and demonstrate that evaporation can be readily adjusted by tuning the interaction parameters and amphiphilic ratio. Importantly, we observe that the evaporation suppression by adsorbed nanoparticles occurs only when the ambient vapor pressure is low. This study provides a fundamental understanding of the phase transition in multiphase interfacial systems and opens up new routes to additional control over evaporating interfaces.

  11. Evaporation of volatile organic compounds from human skin in vitro.

    PubMed

    Gajjar, Rachna M; Miller, Matthew A; Kasting, Gerald B

    2013-08-01

    The specific evaporation rates of 21 volatile organic compounds (VOCs) from either human skin or a glass substrate mounted in modified Franz diffusion cells were determined gravimetrically. The diffusion cells were positioned either on a laboratory bench top or in a controlled position in a fume hood, simulating indoor and outdoor environments, respectively. A data set of 54 observations (34 skin and 20 glass) was assembled and subjected to a correlation analysis employing 5 evaporative mass transfer relationships drawn from the literature. Models developed by Nielsen et al. (Prediction of isothermal evaporation rates of pure volatile organic compounds in occupational environments: a theoretical approach based on laminar boundary layer theory. Ann Occup Hyg 1995;39:497-511.) and the U.S. Environmental Protection Agency (Peress, Estimate evaporative losses from spills. Chem Eng Prog 2003; April: 32-34.) were found to be the most effective at correlating observed and calculated evaporation rates under the various conditions. The U.S. EPA model was selected for further use based on its simplicity. This is a turbulent flow model based only on vapor pressure and molecular weight of the VOC and the effective air flow rate u. Optimum values of u for the two laboratory environments studied were 0.23 m s(-1) (bench top) and 0.92 m s(-1) (fume hood). PMID:23609116

  12. Comparative parallel assessment of a transfer device in reducing 5-fluorouracil environmental contamination inside positive air pressure isolators.

    PubMed

    Forges, Fabien; Simoens, Xavier; Chauvin, Franck

    2011-03-01

    The environmental contamination of the antineoplastic drugs circuit, due to the centralization of preparation and the increased number of the patients treated, brought about a new occupational hazard: the chronic exposure to low doses of antineoplastic drugs. The rationalization of the hospital budgets imposes a meticulous assessment of the devices available for the preparation, in order to justify their interest, even their cost. A prospective comparative study with parallel arms was led inside the Pharmacy of the Institut de Cancerologie de la Loire in order to evaluate the Spike Swan®, a transfer device. The aim was to assess the Spike Swan® effectiveness. The antineoplastic drugs environmental contamination within the isolators is considered as a potential starting point for a larger dissemination of cytotoxic products. Therefore, the primary endpoint was the surface contamination level with 5-fluorouracil and the comparator was the standard preparation technique using needles and aeration needles. This study did not show significant effectiveness for the Spike Swan® in reducing surface contamination. Nevertheless, this device could be used to prepare large volumes and to secure occasional handlers, because it is easy to handle. PMID:20699332

  13. An economic way of reducing health, environmental, and other pressures of urban traffic: a decision analysis on trip aggregation

    PubMed Central

    Tuomisto, Jouni T; Tainio, Marko

    2005-01-01

    Background Traffic congestion is rapidly becoming the most important obstacle to urban development. In addition, traffic creates major health, environmental, and economical problems. Nonetheless, automobiles are crucial for the functions of the modern society. Most proposals for sustainable traffic solutions face major political opposition, economical consequences, or technical problems. Methods We performed a decision analysis in a poorly studied area, trip aggregation, and studied decisions from the perspective of two different stakeholders, the passenger and society. We modelled the impact and potential of composite traffic, a hypothetical large-scale demand-responsive public transport system for the Helsinki metropolitan area, where a centralised system would collect the information on all trip demands online, would merge the trips with the same origin and destination into public vehicles with eight or four seats, and then would transmit the trip instructions to the passengers' mobile phones. Results We show here that in an urban area with one million inhabitants, trip aggregation could reduce the health, environmental, and other detrimental impacts of car traffic typically by 50–70%, and if implemented could attract about half of the car passengers, and within a broad operational range would require no public subsidies. Conclusion Composite traffic provides new degrees of freedom in urban decision-making in identifying novel solutions to the problems of urban traffic. PMID:16309549

  14. Evaporation control research, 1959-60

    USGS Publications Warehouse

    U.S. Geological Survey

    1963-01-01

    Two hundred and forty-five dispersions of long-chain alkanols were formulated by using various emulsifiers and alkanols. The dispensing and spreading ability of each of these formulations was tested. The most promising emulsifier that could be used with any of the alkanols was glyceryl monostearate (self-emulsifying). However, the concentration of the alkanol in the dispersion form varied somewhat: with the length of the carbon chain. A maximum concentration of 16 percent was obtained using the longer chain alkanols in the dispersion form without losing any of the properties of a fluid. Nine field tests were undertaken on small stock tanks. The retardant materials used in these tests were dodecanol, hexadecanol, and octadecanol. These materials were applied in either liquid or dispersion form. Four types of dispensing equipment were tested. The first type used a pressure system which sprayed a liquid onto the surface of the water. An anemometer and wind-controlled vane, operated by an electrical system, determined the length End frequency of application. The second type was similar to the first except that gravity was utilized to force the liquid onto the surface. The third type. used a drip system with rates of about 10 drops per minute. The fourth type used a gravity feed and a wind-controlled valve which allowed the dispersion material to flow onto the surface of the water when the wind was in the proper direction. In the field tests, the best reduction in evaporation was obtained using octadecanol in dispersion form and dispensed with the wind-controlled valve and gravity feed system. The maximum reduction in evaporation for a 2-week period was 27 percent. However, the economics of suppressing evaporation from stock tanks is questionable because of the short travel time across the tank by the film. There are still many problems unsolved. Some of these can be resolved in the laboratory whereas others can be resolved only in the field. Some of the more serious

  15. Enhanced solar desalination unit: modified evaporating wick technique

    SciTech Connect

    El-Bassuoni, A.M.A.

    1983-12-01

    The use of solar energy for producing fresh water by desalination could avoid or reduce the expenditure of fossil fuels for that purpose. At the current time, all solar stills can be viewed as being in various stages of development, rather than as an established technology. Evaporating wick technique is developed world wide, but still has got some limitations. In the ordinary evaporating wick still made of black dyed jute, the heat collection, evaporation, and condensation takes place in the same still. To improve the efficiency and reduce the total cost of the solar still a modified unit was designed and tried. In the modified unit, the condensation operation is separated from the evaporation one. The evaporation unit which is inclined at 24/sup 0/ (the latitude of our place) consists mainly of a metallic basin having dimensions ( 1 x 1 meter) insulating with a layer of foam urethane 4 cm. thickness beneath it. The wick is suspended between two tubes, upper feeding perforated tube (2 mm. hole diameter) and lower suspending tube. The condensation unit contains the condenser which is a metallic box having dimensions of (0.9 x 0.9 meter) over which the vapor condenses. In between the evaporation and condensation unit there is a 0.1 HP. fan to suck the humid air from the evaporation unit to the condensation one. The wick still is fed continuously with water (trickle feeding) from a tank equipped with a level control valve. From this feed system water will ascard by capillarity to the edge of the gutter and then flow downward by gravity. It was found that the outside condensation enhance the efficiency of energy utilization, and the productivity of the still. The performance of the still was tested in many periods all over the year, important observations from the still performance during these period were analysed. The temperature distribution was observed and analysed. Experimental results are presented in the full paper.

  16. Forced-Flow Evaporative Cooler

    NASA Technical Reports Server (NTRS)

    Ellis, Wilbert E.; Niggemann, Richard E.

    1987-01-01

    Evaporative cooler absorbs heat efficiently under unusual gravitational conditions by using centrifugal force and vapor vortexes to maintain good thermal contact between heat-transfer surface and vaporizable coolant. System useful for cooling electronic or other equipment under low gravity encountered in spacecraft or under multiple-gravity conditions frequently experienced in high-performance airplanes.

  17. Simulation of a refrigerant evaporator

    NASA Astrophysics Data System (ADS)

    Vandermeer, Jakob Stefanus

    A computer model for the design and optimization of the compressor refrigeration cycle especially with respect to dynamic behavior was developed. A steady state version was also developed. The model describing the refrigerant is divided into the evaporation and superheating regions. A mechanism based on empirics corrects the model for the influence of transportation times in the evaporation region. The mass balance of the refrigerant in the superheat region is regarded as quasi-static, because of the small mass of the vapor. The energy balance accounts for a distributed model and is represented by the steady state solution of the partial differential equation which describes this area for the steady conditions. A correction for the dynamical effects was added to this solution, for all influencing parameters, according to the analytical dynamic solution for the case of the evaporation temperature as input parameter. The expansion device model was worked out for the usual type of device in combination with a dry evaporator, the thermostatic expansion valve. Validation tests are described.

  18. Micromachined evaporators for AMTEC cells

    SciTech Connect

    Izenson, M.G.; Crowley, C.J.

    1996-12-31

    To achieve high cell efficiency and reliability, the capillary pumping system for Alkali Metal Thermal to Electric Conversion (AMTEC) must have three key characteristics: (1) very small pores to achieve a high capillary pumping head, (2) high permeability for the flow of liquid sodium to minimize internal losses, and (3) be made from a material that is exceptionally stable at high temperatures in a sodium environment. The authors have developed micromachining techniques to manufacture high performance evaporators for AMTEC cells. The evaporators have been fabricated from stainless steel, molybdenum, and a niobium alloy (Nb-1Zr). The regular, micromachined structure leads to very high capillary pumping head with high permeability for liquid flow. Data from tests performed with common fluids at room temperature characterize the capillary pumping head and permeability of these structures. Three micromachined evaporators have been built into AMTEC cells and operated at temperatures up to 1,100 K. Results from these tests confirm the excellent pumping capabilities of the micromachined evaporators.

  19. Rate of runaway evaporative cooling

    SciTech Connect

    Groep, J. van de; Straten, P. van der; Vogels, J. M.

    2011-09-15

    Evaporative cooling is a process that is essential in creating Bose-Einstein condensates in dilute atomic gasses. This process has often been simulated based on a model using a truncated Boltzmann distribution. This model assumes that the energy distribution up to the threshold energy can still be described by a Boltzmann distribution: it assumes detailed balance up to the threshold energy. However, the evolution of the distribution function in time is not taken into account. Here we solve the kinetic Boltzmann equation for a gas undergoing evaporative cooling in a harmonic and linear trap in order to determine the evolution of the energy distribution. The magnitude of the discrepancy with the truncated Boltzmannmodel is calculated by including a polynomial expansion of the distribution function. We find that up to 35% fewer particles are found in the high-energy tail of the distribution with respect to the truncated Boltzmann distribution and up to 15% more collisions are needed to reach quantum degeneracy. Supported by a detailed investigation of the particle loss rate at different energies, we conclude that the limited occupation of high-energy states during the evaporation process causes the lowering of the evaporation speed and efficiency.

  20. Membrane evaporator/sublimator investigation

    NASA Technical Reports Server (NTRS)

    Elam, J.; Ruder, J.; Strumpf, H.

    1974-01-01

    Data are presented on a new evaporator/sublimator concept using a hollow fiber membrane unit with a high permeability to liquid water. The aim of the program was to obtain a more reliable, lightweight and simpler Extra Vehicular Life Support System (EVLSS) cooling concept than is currently being used.

  1. The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures.

    PubMed

    Gerson, Alexander R; Smith, Eric Krabbe; Smit, Ben; McKechnie, Andrew E; Wolf, Blair O

    2014-01-01

    Environmental temperatures that exceed body temperature (Tb) force endothermic animals to rely solely on evaporative cooling to dissipate heat. However, evaporative heat dissipation can be drastically reduced by environmental humidity, imposing a thermoregulatory challenge. The goal of this study was to investigate the effects of humidity on the thermoregulation of desert birds and to compare the sensitivity of cutaneous and respiratory evaporation to reduced vapor density gradients. Rates of evaporative water loss, metabolic rate, and Tb were measured in birds exposed to humidities ranging from ∼2 to 30 g H2O m(-3) (0%-100% relative humidity at 30°C) at air temperatures between 44° and 56°C. In sociable weavers, a species that dissipates heat primarily through panting, rates of evaporative water loss were inhibited by as much as 36% by high humidity at 48°C, and these birds showed a high degree of hyperthermia. At lower temperatures (40°-44°C), evaporative water loss was largely unaffected by humidity in this species. In Namaqua doves, which primarily use cutaneous evaporation, increasing humidity reduced rates of evaporative water loss, but overall rates of water loss were lower than those observed in sociable weavers. Our data suggest that cutaneous evaporation is more efficient than panting, requiring less water to maintain Tb at a given temperature, but panting appears less sensitive to humidity over the air temperature range investigated here. PMID:25461643

  2. Fuel retention in impurity seeded discharges in JET after Be evaporation

    NASA Astrophysics Data System (ADS)

    Brezinsek, S.; Loarer, T.; Krieger, K.; Jachmich, S.; Tsalas, M.; Coffey, I.; Esser, H. G.; Eich, T.; Fundamenski, W.; Giroud, C.; Grünhagen, S.; Huber, A.; Kruezi, U.; Knipe, S.; Maddison, G. P.; McCormick, K.; Meigs, A. G.; Morgan, Ph.; Philipps, V.; Sergienko, G.; Stagg, R.; Stamp, M. F.; Tabares, F. L.; EFDA Contributors, JET

    2011-07-01

    Preparatory experiments for the ITER-Like Wall in JET were carried out to simulate the massive Be first wall by a thin Be layer, induced by evaporation of about 2.0 g Be, and to study its impact on fuel retention and divertor radiation with reduced C content and N seeding. Residual gas analysis reveals a reduction of hydrocarbons by one order of magnitude and of O by a factor of 5 in the partial pressure owing to the evaporation. The evolution of wall conditions, impurity fluxes and divertor radiation have been studied in ELMy H-mode plasmas (Bt = 2.7 T, Ip = 2.5 MA, Paux = 16 MW) whereas a non-seeded reference discharge was executed prior to the evaporation. The in situ measured Be flux at the midplane increased by about a factor of 40 whereas the C flux decreased by ~50% in the limiter phase of the first discharge with respect to the reference, but erosion of the Be layer and partial coverage with C takes place quickly. To make best use of the protective Be layer, only the first four discharges were employed for a gas balance analysis providing a D retention rate of 1.94 × 1021 D s-1 which is comparable to rates with C walls. But the Be evaporation provides a non-saturated surface with respect to D and short term retention is not negligible in the balance; the measured retention is overestimated with respect to steady-state conditions like that of the ILW. Moreover, C was only moderately reduced and co-deposition of fuel with eroded Be and C occurs. The lower C content leads to a minor reduction in divertor radiation as the reference phase prior to seeding indicates. N adds to the radiation of D and the remaining C, and the N content rises due to the legacy effect which has been quantified by gas balance to be 30% of the injected N. C radiation increases with exposure time, and both contributors cause an increase in the radiated fraction in the divertor from 50% to 70%. The radiation pattern suggests that N dominates the increase in the first discharges though C

  3. Reduced phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities and lignin synthesis in wheat grown under low pressure sodium lamps

    NASA Technical Reports Server (NTRS)

    Guerra, D.; Anderson, A. J.; Salisbury, F. B.

    1985-01-01

    Wheat (Triticum aestivum L. cv Fremont) grown in hydroponic culture under 24-hour continuous irradiation at 560 to 580 micromoles per square meter per second from either metalhalide (MH), high pressure sodium (HPS), or low pressure sodium (LPS) lamps reached maturity in 70 days. Grain yields were similar under all three lamps, although LPS-grown plants lodged at maturity. Phenylalanine ammonia-lyase (PAL) and a tyrosine ammonia lyase (TAL) with lesser activity were detected in all extracts of leaf, inflorescence, and stem. Ammonia-lyase activities increased with age of the plant, and plants grown under the LPS lamp displayed PAL and TAL activities lower than wheat cultured under MH and HPS radiation. Greenhouse solar-grown wheat had the highest PAL and TAL activities. Lignin content of LPS-grown wheat was also significantly reduced from that of plants grown under MH or HPS lamps or in the greenhouse, showing a correlation with the reduced PAL and TAL activities. Ratios of far red-absorbing phytochrome to total phytochrome were similar for all three lamps, but the data do not yet warrant a conclusion about specific wavelengths missing from the LPS lamps that might have induced PAL and TAL activities in plants under the other lamps.

  4. Thermal and Evolved Gas Analysis of Calcite Under Reduced Operating Pressures: Implications for the 2011 MSL Sample Analysis at Mars (SAM) Instrument

    NASA Technical Reports Server (NTRS)

    Lauer, H. V. Jr.; Ming, D. W.; Sutter, B.; Mahaffy, P. R.

    2010-01-01

    The Mars Science Laboratory (MSL) is scheduled for launch in 2011. The science objectives for MSL are to assess the past or present biological potential, to characterize the geology, and to investigate other planetary processes that influence habitability at the landing site. The Sample Analysis at Mars (SAM) is a key instrument on the MSL payload that will explore the potential habitability at the landing site [1]. In addition to searching for organic compounds, SAM will have the capability to characterized evolved gases as a function of increasing temperature and provide information on the mineralogy of volatile-bearing phases such as carbonates, sulfates, phyllosilicates, and Fe-oxyhydroxides. The operating conditions in SAM ovens will be maintained at 30 mb pressure with a He carrier gas flowing at 1 sccm. We have previously characterized the thermal and evolved gas behaviors of volatile-bearing species under reduced pressure conditions that simulated operating conditions of the Thermal and Evolved Gas Analyzer (TEGA) that was onboard the 2007 Mars Phoenix Scout Mission [e.g., 2-8]. TEGA ovens operated at 12 mb pressure with a N2 carrier gas flowing at 0.04 sccm. Another key difference between SAM and TEGA is that TEGA was able to perform differential scanning calorimetry whereas SAM only has a pyrolysis oven. The operating conditions for TEGA and SAM have several key parameter differences including operating pressure (12 vs 30 mb), carrier gas (N2 vs. He), and carrier gas flow rate (0.04 vs 1 sccm). The objectives of this study are to characterize the thermal and evolved gas analysis of calcite under SAM operating conditions and then compare it to calcite thermal and evolved gas analysis under TEGA operating conditions.

  5. Evaporation of LOX under supercritical and subcritical conditions

    NASA Technical Reports Server (NTRS)

    Yang, A. S.; Hsieh, W. H.; Kuo, K. K.; Brown, J. J.

    1993-01-01

    The evaporation of LOX under supercritical and subcritical conditions was studied experimentally and theoretically. In experiments, the evaporation rate and surface temperature were measured for LOX strand vaporizing in helium environments at pressures ranging from 5 to 68 atmospheres. Gas sampling and chromatography analysis were also employed to profile the gas composition above the LOX surface for the purpose of model validation. A comprehensive theoretical model was formulated and solved numerically to simulate the evaporation process of LOX at high pressures. The model was based on the conservation equations of mass, momentum, energy, and species concentrations for a multicomponent system, with consideration of gravitational body force, solubility of ambient gases in liquid, and variable thermophysical properties. Good agreement between predictions and measured oxygen mole fraction profiles was obtained. The effect of pressure on the distribution of the Lewis number, as well as the effect of variable diffusion coefficient, were further examined to elucidate the high-pressure transport behavior exhibited in the LOX vaporization process.

  6. Laboratory Evaporation Testing Of Hanford Waste Treatment Plant Low Activity Waste Off-Gas Condensate Simulant

    SciTech Connect

    Adamson, Duane J.; Nash, Charles A.; McCabe, Daniel J.; Crawford, Charles L.; Wilmarth, William R.

    2014-01-27

    The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream, LAW Off-Gas Condensate, from the off-gas system. The baseline plan for disposition of this stream is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility again. Alternate disposition of this stream would eliminate recycling of problematic components, and would enable de-coupled operation of the LAW melter and the Pretreatment Facilities. Eliminating this stream from recycling within WTP would also decrease the LAW vitrification mission duration and quantity of canistered glass waste forms. This LAW Off-Gas Condensate stream contains components that are volatile at melter temperatures and are problematic for the glass waste form. Because this stream recycles within WTP, these components accumulate in the Condensate stream, exacerbating their impact on the number of LAW glass containers that must be produced. Approximately 32% of the sodium in Supplemental LAW comes from glass formers used to make the extra glass to dilute the halides to be within acceptable concentration ranges in the LAW glass. Diverting the stream reduces the halides in the recycled Condensate and is a key outcome of this work. Additionally, under possible scenarios where the LAW vitrification facility commences operation prior to the WTP Pretreatment facility, identifying a disposition path becomes vitally important. This task examines the impact of potential future disposition of this stream in the Hanford tank farms, and investigates auxiliary evaporation to enable another disposition path. Unless an auxiliary evaporator is used, returning the stream to the tank farms would require evaporation in the 242-A evaporator. This stream is expected to be unusual because it will be very high in corrosive species that are volatile in the melter

  7. Vapor-phase epitaxy of gallium nitride by gallium arc discharge evaporation

    NASA Astrophysics Data System (ADS)

    Heikman, S.; Keller, S.; Mishra, U. K.

    2006-08-01

    Vapor-phase epitaxy of GaN was performed by combining ammonia with gallium evaporated into an inert gas stream by a DC arc discharge, and letting the mixture pass through a pair of heated graphite susceptors. Growth rates as high as 30 μm/h were achieved. The growth on the top sample was specular in a large area, and was of high quality as characterized by atomic force microscopy and photoluminescence spectroscopy. The bottom sample had a high density of macroscopic defects, presumably caused by Ga droplets in the gas phase resulting from the arc evaporation process. The experimental growth rate was found to be less than {1}/{3} of values predicted in a computer flow dynamic model of the growth system, and Ga-NH 3 pre-reactions were implicated as the likely cause of the discrepancy. The growth efficiency, calculated to 2%, could arguably be improved by reducing the reactor growth pressure, and by changing the reactor geometry to avoid Ga condensation on walls. Potential advantages of the described growth technique are cheap source materials of high purity and low equipment costs. Furthermore, since no corrosive gasses were used, hardware corrosion and gas-phase impurities can be reduced.

  8. Continuous Positive Airway Pressure Reduces Risk of Motor Vehicle Crash among Drivers with Obstructive Sleep Apnea: Systematic Review and Meta-analysis

    PubMed Central

    Tregear, Stephen; Reston, James; Schoelles, Karen; Phillips, Barbara

    2010-01-01

    Context: Obstructive sleep apnea (OSA) is associated with an increased risk of motor vehicle crash. Objective: We performed a systematic review of the literature concerning the impact of continuous positive airway pressure (CPAP) treatment on motor vehicle crash risk among drivers with OSA. The primary objective was to determine whether CPAP use could reduce the risk of motor vehicle crash among drivers with OSA. A secondary objective involved determining the time on treatment required for CPAP to improve driver safety. Data Sources: We searched seven electronic databases (MEDLINE, PubMed (PreMEDLINE), EMBASE, PsycINFO, CINAHL, TRIS, and the Cochrane library) and the reference lists of all obtained articles. Study Selection: We included studies (before-after, case-control, or cohort) that addressed the stated objectives. We evaluated the quality of each study and the interplay between the quality, quantity, robustness, and consistency of the evidence. We also tested for publication bias. Data Extraction: Data were extracted by two independent analysts. When appropriate, data were combined in a fixed or random effects meta-analysis. Results: A meta-analysis of 9 observational studies examining crash risk of drivers with OSA pre- vs. post-CPAP found a significant risk reduction following treatment (risk ratio = 0.278, 95% CI: 0.22 to 0.35; P < 0.001). Although crash data are not available to assess the time course of change, daytime sleepiness improves significantly following a single night of treatment, and simulated driving performance improves significantly within 2 to 7 days of CPAP treatment. Conclusions: Observational studies indicate that CPAP reduces motor vehicle crash risk among drivers with OSA. Citation: Tregear S; Reston J; Schoelles K; Phillips B. Continuous positive airway pressure reduces risk of motor vehicle crash among drivers with obstructive sleep apnea. SLEEP 2010;33(10):1373-1380. PMID:21061860

  9. Evaporation of iodine-containing off-gas scrubber solution

    DOEpatents

    Partridge, J.A.; Bosuego, G.P.

    1980-07-14

    Mercuric nitrate-nitric acid scrub solutions containing radioiodine may be reduced in volume without excessive loss of volatile iodine. The use of concentrated nitric acid during an evaporation process oxidizes the mercury-iodide complex to a less volatile mercuric iodate precipitate.

  10. COMPARISON OF COMMON SOLVENT EVAPORATION TECHNIQUES IN ORGANIC ANALYSIS

    EPA Science Inventory

    Isolation of organic constituents from water frequently involves an extraction with a large volume of organic solvent which must be reduced to achieve the desired sensitivity. The objective of this research was to evaluate common solvent evaporation techniques to determine which ...

  11. Adjuvant Effects on Evaporation Time and Wetted Area of Droplets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Appropriate adjuvant selection for pesticide applications is central to improve spray performances on waxy leaves and to reduce off-target losses. Evaporation and deposition patterns of 500 µm sessile droplets with five classes of adjuvants on five different waxy plants were investigated. Droplets g...

  12. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  13. Analysis of energy use in tomato evaporation

    SciTech Connect

    Rumsey, T.; Conant, T.

    1980-01-01

    Field performance data for four tomato product evaporators are presented and analyzed. Steam and feed flow rates along with steam economies were measured and are compared to steady state theoretical evaporator models.

  14. Evaporation Time and Spread Area of Adjuvant-amended Droplets on Waxy and Hairy Leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the evaporation of pesticide droplets and wetting of leaf surfaces can increase foliar application efficiency and reduce pesticide use. Evaporation time and wetted area of single pesticide droplets on hairy and waxy geranium leaf surfaces were measured under the controlled conditions f...

  15. Alternative Methods for the Reduction of Evaporation: Practical Exercises for the Science Classroom

    ERIC Educational Resources Information Center

    Schouten, Peter; Putland, Sam; Lemckert, Charles J.; Parisi, Alfio V.; Downs, Nathan

    2012-01-01

    Across the world, freshwater is valued as the most critically important natural resource, as it is required to sustain the cycle of life. Evaporation is one of the primary environmental processes that can reduce the amount of quality water available for use in industrial, agricultural and household applications. The effect of evaporation becomes…

  16. Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol

    SciTech Connect

    Vaden, Timothy D.; Imre, Dan G.; Beranek, Josef; Shrivastava, ManishKumar B.; Zelenyuk, Alla

    2011-02-08

    Field measurements of secondary organic aerosol (SOA) find higher mass loads than predicted by models, sparking intense efforts to find additional SOA sources but leaving the assumption of rapid SOA evaporation unchallenged. We characterized room-temperature evaporation of pure SOA and SOA formed in the presence of spectator organic vapors with and without aging. We find that it takes ~24 hrs for pure SOA particles to evaporate 75% of their mass, which is in sharp contrast to the ~10 minutes timescales predicted by models. The presence of spectator organic vapors and aging dramatically reduces the evaporation, and in some cases nearly stops it. For all cases, SOA evaporation behavior is size independent and does not follow the liquid droplet evaporation kinetics assumed by models.

  17. Testing of a Miniature Loop Heat Pipe with Multiple Evaporators and Multiple Condensers for Space Applications

    NASA Technical Reports Server (NTRS)

    Nagano, Hosei; Ku, Jentung

    2006-01-01

    Thermal performance of a miniature loop heat pipe (MLHP) with two evaporators and two condensers is described. A comprehensive test program, including start-up, high power, low power, power cycle, and sink temperature cycle tests, has been executed at NASA Goddard Space Flight Center for potential space applications. Experimental data showed that the loop could start with heat loads as low as 2W. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of l00W to 120W, and could recover from a dry-out by reducing the heat load to evaporators. Low power test results showed the loop could work stably for heat loads as low as 1 W to each evaporator. Excellent adaptability of the MLHP to rapid changes of evaporator power and sink temperature were also demonstrated.

  18. Evaporating behaviors of water droplet on superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Hao, PengFei; Lv, CunJing; He, Feng

    2012-12-01

    We investigated the dynamic evaporating behaviors of water droplet on superhydrophobic surfaces with micropillars. Our experimental data showed that receding contact angles of the water droplet increased with the decreasing of the scale of the micropillars during evaporation, even though the solid area fractions of the microstructured substrates remained constant. We also experimentally found that the critical contact diameters of the transition between the Cassie-Baxter and Wenzel states are affected not only by the geometrical parameters of the microstructures, but also by the initial volume of the water droplet. The measured critical pressure is consistent with the theoretical model, which validated the pressure-induced impalement mechanism for the wetting state transition.

  19. Evaporation and radiation measurements at Salton Sea, California

    USGS Publications Warehouse

    Sturrock, Alex M.

    1978-01-01

    Evaporation from Salton Sea, Calif. was computed for a 539-day period between duly 14, 1967, and January 2, 1969, by use of energy-budget, mass-transfer, and water-budget methods. The total evaporation computed by the three methods agreed within 5 percent. For computing evaporation by the mass-transfer method, vapor pressure measured at raft stations on the sea was considered to be more representative of the conditions over the sea than vapor pressure measured at land stations. The values of heat transfer to and from the bed were used in energy-budget computations. The inclusion of these heat transfer values improved the correlation of evaporation computed by the energy-budget and water-budget methods. Monthly evaporation computed by the energy budget method for 1968 showed that the Salton Sea exhibited a double-wave evaporation similar to that of oceans in the same latitude. Weekly and monthly comparisons were made to determine if radiation measured by the flat-plate radiometer is seasonally biased. Weekly totals of radiation from three flat-plate radiometers were compared to values of a Cummings Radiation Integrator. Monthly totals of radiation for each of the two types of instruments were compared to an empirical method for determining radiation. These comparisons indicate that the measurements of radiation by the flat-plate radiometer are not seasonally biased, and that the Cummings Radiation Integrator gives reliable measurements of radiation for periods as short as 1 week. The net incoming radiation was measured at three stations around the Salton Sea. The areal variation was less than 1 percent on an annual basis and the largest weekly variation was less than 6 percent. An empirical mass-transfer coefficient, N, was determined from energy-budget measurements. The value of this coefficient to give evaporation in inches per day is 0.00245 when the windspeed is expressed in miles per hour and vapor pressure is expressed in millibars. The coefficient is valid

  20. Fast and Efficient non-reduced Lys-C digest using pressure cycling technology for antibody disulfide mapping by LC-MS.

    PubMed

    Cheng, Ying; Chen, Yonghong; Yu, Christopher

    2016-09-10

    Conventional sample preparation for antibody disulfide mapping often requires relatively long digestion time (from several hours to overnight) and relatively high endoproteinase concentration. These conditions are typically necessitated by the fact that antibody molecules are not sufficiently denatured under non-reduced conditions and chaotropic agents are used during digestion to achieve optimal denaturation. Disulfide scrambling can occur as artifacts of digestion as proteins are incubated for extended periods, often at neutral to slightly alkaline pH conditions. Shortening digestion time and lowering the pH during digestion frequently result in incomplete peptide cleavages or variable recoveries. Here, we report the development of a fast and efficient non-reduced Lys-C digestion method based on pressure cycling technology (PCT) and its application in determining disulfide-linkages in monoclonal antibodies (mAbs). Conditions were optimized to ensure complete digestion of the mAb with minimal sample preparation-related disulfide scrambling. The PCT-based method was able to generate up to 10-fold signal increase for some disulfide peptides in a 1h Lys-C digestion compared to the conventional bench-top digestion method. As a result of the shorter digestion time, disulfide scrambling that is seen as a major assay artifact of the conventional method was reduced to less than 0.05% in tested molecules. The results show that the PCT-based method offers fast digestion in a shorter time for all the mAbs tested. PMID:27429370

  1. Application of a drainage film reduces fibroblast ingrowth into large-pored polyurethane foam during negative-pressure wound therapy in an in vitro model.

    PubMed

    Wiegand, Cornelia; Springer, Steffen; Abel, Martin; Wesarg, Falko; Ruth, Peter; Hipler, Uta-Christina

    2013-01-01

    Negative-pressure wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open-cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open-cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large-pored PU foam, fine-pored PU foam, and the combination of large-pored foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large-pored PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine-pored PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large-pored PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced. PMID:23937617

  2. 21 CFR 131.130 - Evaporated milk.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Evaporated milk. 131.130 Section 131.130 Food and... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.130 Evaporated milk. (a) Description. Evaporated milk is the liquid food obtained by partial removal of water only from milk....

  3. Iodine retention during evaporative volume reduction

    DOEpatents

    Godbee, H.W.; Cathers, G.I.; Blanco, R.E.

    1975-11-18

    An improved method for retaining radioactive iodine in aqueous waste solutions during volume reduction is disclosed. The method applies to evaporative volume reduction processes whereby the decontaminated (evaporated) water can be returned safely to the environment. The method generally comprises isotopically diluting the waste solution with a nonradioactive iodide and maintaining the solution at a high pH during evaporation.

  4. SEWAGE DISPOSAL BY EVAPORATION-TRANSPIRATION

    EPA Science Inventory

    One of the methods for on-site disposal of wastewater from individual homes is by evaporation. Two types of evaporative disposal systems have been investigated in this study; evapo-transpiration (ET) beds and mechanical evaporation units. Twenty nine test lysimeters of 0.22 cubic...

  5. How surfactants influence evaporation-driven flows

    NASA Astrophysics Data System (ADS)

    Liepelt, Robert; Marin, Alvaro; Rossi, Massimiliano; Kähler, Christian J.

    2014-11-01

    Capillary flows appear spontaneously in sessile evaporating drops and give rise to particle accumulation around the contact lines, commonly known as coffee-stain effect (Deegan et al., Nature, 1997). On the other hand, out-of-equilibrium thermal effects may induce Marangoni flows in the droplet's surface that play an important role in the flow patterns and in the deposits left on the substrate. Some authors have argued that contamination or the presence of surfactants might reduce or eventually totally annul the Marangoni flow (Hu & Larson, J. Phys. Chem. B, 2006). On the contrary, others have shown an enhancement of the reverse surface flow (Sempels et al., Nat. Commun., 2012). In this work, we employ Astigmatic Particle Tracking Velocimetry (APTV) to obtain the 3D3C evaporation-driven flow in both bulk and droplet's surface, using surfactants of different ionic characters and solubility. Our conclusions lead to a complex scenario in which different surfactants and concentrations yield very different surface-flow patterns, which eventually might influence the colloidal deposition patterns.

  6. Evaluation of insulated pressure vessels for cryogenic hydrogen storage

    SciTech Connect

    Aceves, S M; Garcia-Villazana, O; Martinez-Frias, J

    1999-03-01

    This paper presents an analytical and experimental evaluation of the applicability of insulated pressure vessels for hydrogen-fueled light-duty vehicles. Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH?) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The purpose of this work is to verify that commercially available aluminum-lined, fiber- wrapped vessels can be used for cryogenic hydrogen storage. The paper reports on previous and ongoing tests and analyses that have the purpose of improving the system design and assure its safety.

  7. Evaporation in the Atacama Desert: An empirical study of spatio-temporal variations and their causes

    NASA Astrophysics Data System (ADS)

    Houston, John

    2006-11-01

    SummaryThe Atacama Desert is hyper-arid, and areas where adequate moisture exists for evaporation are spatially highly restricted. Nevertheless, water resources exist and their evaluation requires knowledge of this elusive but important component of the hydrological cycle. Evaporation may occur in four typical areas: rivers and associated riparian zones, localized springs, large playas and extensive areas of bare soil after infrequent precipitation events. Transpiration is locally possible where moisture is sufficiently close to the surface to allow phreatophytes or scarce grass cover to grow, but virtually no information is available for quantification. Pan evaporation data from 11 stations for the period 1977-1991 is analyzed and complemented by analysis of an evaporation study conducted in the Salar de Atacama during 1987/1988. The results show that pan evaporation, and hence maximum potential evaporation may be considered largely a function of maximum temperature and elevation as well as density of the evaporating fluid. Actual evaporation is limited by available moisture and diminishes rapidly as the level of soil moisture saturation drops below the soil surface, extinguishing at ca. 2 m depth. Evaporation is greatest during the summer, but at higher elevations convective cloudiness develops during January and February reducing evaporating rates at a time when significant precipitation may occur. Inter-annual variations in pan evaporation are considerable and weakly correlated with ENSO, but variations in actual evaporation are damped by comparison. Regression equations are developed which have widespread applicability and may be used to estimate evaporation in areas where no site-specific data exists.

  8. Does groundwater enhance evaporative cooling?

    NASA Astrophysics Data System (ADS)

    Rouholahnejad, E.

    2015-12-01

    Evaporation is a key process in land-climate interactions, not only because it directly regulates the hydrological cycle, but also because it contributes to the Earth's energy balance. Due to its feedbacks on large-scale water processes and its impact on the dynamics of the atmosphere, it has been considered as a driver of droughts and heatwaves1-3. While evaporation from ocean surfaces is likely to increase with rising temperatures, it is unclear whether evapotranspiration from land surfaces could similarly increase, due to possible limitations imposed by soil moisture and vegetation physiology4. Observations suggest that groundwater (hereafter GW) has an important role in hydrological budgets and soil moisture variability in many regions, supplying moisture for evapotranspiration during dry seasons5, 6. Although modeling studies suggest that GW is often close enough to the surface to interact with the atmosphere7, 8, the soil water storage is often underestimated by land surface models. This is most likely due to neglecting the lateral movement of water from topographically higher altitudes to valley bottoms and its convergence close to the land surface, as well as the upward movement of water in the capillary fringe.The focus of this study is to understand where and when GW may significantly enhance the availability of soil water for evapotranspiration. We also quantified the potential contribution of GW to evapotranspiration in the areas where GW is a major supply. We used the global network of eddy covariance observations9 (FLUXNET) along with global modeled GW depth10 and GLEAM ET model estimates11 to address the current gap in modelling ET due to neglecting GW supply. Having identified areas where GW is tightly coupled with the atmosphere through evaporation processes, the study provides the basis to examine the "air conditioning effect" of GW and test the idea if GW enhances evaporation to the extent that leads to a cooler temperatures and wetter climates.

  9. Evaporation by mechanical vapor recompression

    NASA Astrophysics Data System (ADS)

    Iverson, C. H.; Coury, G. E.

    1980-04-01

    Progress in the development of a study of the application of the technologies of mechanical vapor recompression and falling film evaporation as applied to the beet sugar industry is reported. Progress is reported in the following areas: technical literature search; report on visit to European factories using these technologies; energy balance studies of factories offered by the industry as candidates for the demonstration plants; and report on energy balance studies and the recommendations as to the site for the demonstration plant.

  10. Numerical study on thermodynamic characteristics of rotational supercavitating evaporator

    NASA Astrophysics Data System (ADS)

    Li, Q.; Zheng, Z. Y.; Li, F. C.; Kulagin, V. A.

    2016-05-01

    Rotational Supercavitating Evaporator (RSCE) has been proposed as a new technology for seawater desalination. However, thermodynamic characteristics of rotational supercavitation are still vacant. In this paper, numerical simulations are conducted on the supercavitating flows around a 3D rotating blade of RSCE with different rotational speeds and extraction pressures. Energy effect is taken into consideration in the simulation and thermodynamic characteristics of rotational supercavitation are obtained. Rotational supercavitation has a larger convective heat transfer coefficient than the boiling on a heated wall.

  11. Evaporative cooling on a grooved surface. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Yoder, D.

    1979-01-01

    The transition point where water begins to accumulate on the surface during spray evaporative cooling was investigated experimentally to determine the temperatures and corresponding heat flux at which this transition occurs. Several pressure ranges were considered including one below the triple point of water. Additionally, the results using a grooved surface were compared to those using a smooth surface. It was determined that a grooved surface has no effect on the heat transfer.

  12. Dynamics of evaporative colloidal patterning

    NASA Astrophysics Data System (ADS)

    Kaplan, C. Nadir; Wu, Ning; Mandre, Shreyas; Aizenberg, Joanna; Mahadevan, L.

    2015-09-01

    Drying suspensions often leave behind complex patterns of particulates, as might be seen in the coffee stains on a table. Here, we consider the dynamics of periodic band or uniform solid film formation on a vertical plate suspended partially in a drying colloidal solution. Direct observations allow us to visualize the dynamics of band and film deposition, where both are made of multiple layers of close packed particles. We further see that there is a transition between banding and filming when the colloidal concentration is varied. A minimal theory of the liquid meniscus motion along the plate reveals the dynamics of the banding and its transition to the filming as a function of the ratio of deposition and evaporation rates. We also provide a complementary multiphase model of colloids dissolved in the liquid, which couples the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate flows and the transition from a dilute suspension to a porous plug. This allows us to determine the concentration dependence of the bandwidth and the deposition rate. Together, our findings allow for the control of drying-induced patterning as a function of the colloidal concentration and evaporation rate.

  13. Nonmagnetic impellers improve evaporative cooling

    SciTech Connect

    Hausman, T. )

    1993-03-01

    This article describes how nonmagnetic impeller flow sensors help improve efficiency of open evaporative cooling water systems. Open evaporative cooling water systems provide economical heat sinks with efficient reuse of water. However, their water loss through evaporation, though minimal, results in an increased concentration of dissolved and suspended impurities in the remaining water. To deconcentrate the water and minimize impurities, the system water is bled off and replaced with fresh makeup water. Bleedoff helps, but to maintain efficient operation and protect the system from water-related catastrophes, various chemical treatments are required for the control of corrosion, deposition, and biological growth. Efficient addition of makeup water and chemical additives can be achieved by a system design employing multiple data points, using flow sensors having high reproducibility for good trend data. In such a system, nonmagnetic flow sensors provide 1% accuracy and excellent reproducibility. In addition, their low initial cost and long service life mean that they can be used cost effectively at multiple data collection points to eliminate approximations.

  14. Feasibility of subcutaneous gentamicin and pressurized irrigation as adjuvant strategies to reduce surgical site infection in colorectal surgery: results of a pilot study.

    PubMed

    Dineen, Sean P; Pham, Thai H; Murray, Bryce W; Parker, Betty J; Hartless, Kathleen; Anthony, Thomas; Huerta, Sergio

    2015-06-01

    Surgical site infections (SSIs) remain a common and costly morbidity after colorectal surgery. This rate remains high even in the setting of strict adherence to Surgical Care Improvement Project Protocols. The aim of our pilot study was to determine the feasibility and safety of subcutaneous gentamicin injection or pressurized irrigation as adjuncts to reduce SSI. A total of 132 patients who underwent colorectal surgery at the VA North Texas Health Care System were prospectively assigned to a pressurized irrigation group (n = 44), a preincision gentamicin injection group (n = 48), or control (n = 40). The primary objective was to assess safety and feasibility of these strategies. Patient demographics were matched among groups. Univariate and multivariate analyses were performed to identify possible predictions of SSI in this cohort. The rate of SSI in the control group was 25 per cent, 13.5 per cent in the pressurized irrigation group, and 12.5 per cent in the gentamicin group (P = 0.26). Combined, the intervention groups had a 13 per cent SSI versus 25 per cent control (P = 0.09). Operative time was not increased by the interventions and no intraoperative complications specifically related to the interventions were noted. Postoperative complications were not different between groups. Both albumin and body mass index were associated with SSI. Body mass index was and independent predictor of SSI (P = 0.006). In conclusion, this pilot study demonstrates the feasibility of the interventions described. There was no detrimental effect of either intervention. There was trend toward a reduction in SSI in the intervention group, which warrants further investigation. PMID:26031269

  15. Black hole evaporation in a noncommutative charged Vaidya model

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Javed, W.

    2012-06-01

    We study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine a spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordström-like solution of this model, which leads to an exact ( t - r)-dependent metric. The behavior of the temporal component of this metric and the corresponding Hawking temperature are investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of charged massive particles through the quantum horizon. We find that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that the black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from a maximum value to zero. We note that the final stage of black hole evaporation is a naked singularity.

  16. Black hole evaporation in a noncommutative charged Vaidya model

    SciTech Connect

    Sharif, M. Javed, W.

    2012-06-15

    We study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine a spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordstroem-like solution of this model, which leads to an exact (t - r)-dependent metric. The behavior of the temporal component of this metric and the corresponding Hawking temperature are investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of charged massive particles through the quantum horizon. We find that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that the black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from a maximum value to zero. We note that the final stage of black hole evaporation is a naked singularity.

  17. Estimating evaporative vapor generation from automobiles based on parking activities.

    PubMed

    Dong, Xinyi; Tschantz, Michael; Fu, Joshua S

    2015-07-01

    A new approach is proposed to quantify the evaporative vapor generation based on real parking activity data. As compared to the existing methods, two improvements are applied in this new approach to reduce the uncertainties: First, evaporative vapor generation from diurnal parking events is usually calculated based on estimated average parking duration for the whole fleet, while in this study, vapor generation rate is calculated based on parking activities distribution. Second, rather than using the daily temperature gradient, this study uses hourly temperature observations to derive the hourly incremental vapor generation rates. The parking distribution and hourly incremental vapor generation rates are then adopted with Wade-Reddy's equation to estimate the weighted average evaporative generation. We find that hourly incremental rates can better describe the temporal variations of vapor generation, and the weighted vapor generation rate is 5-8% less than calculation without considering parking activity. PMID:25818089

  18. Development of a Direct Evaporator for the Organic Rankine Cycle

    SciTech Connect

    Donna Post Guillen; Helge Klockow; Matthew Lehar; Sebastian Freund; Jennifer Jackson

    2011-02-01

    This paper describes research and development currently underway to place the evaporator of an Organic Rankine Cycle (ORC) system directly in the path of a hot exhaust stream produced by a gas turbine engine. The main goal of this research effort is to improve cycle efficiency and cost by eliminating the usual secondary heat transfer loop. The project’s technical objective is to eliminate the pumps, heat exchangers and all other added cost and complexity of the secondary loop by developing an evaporator that resides in the waste heat stream, yet virtually eliminates the risk of a working fluid leakage into the gaseous exhaust stream. The research team comprised of Idaho National Laboratory and General Electric Company engineers leverages previous research in advanced ORC technology to develop a new direct evaporator design that will reduce the ORC system cost by up to 15%, enabling the rapid adoption of ORCs for waste heat recovery.

  19. Developing CD-ROM based multimedia digital textbook of 'San-Yin-Jiao(SP-6) pressure for reducing the labor pain and shortening the labor time'.

    PubMed

    Kim, J; Jang, S; Kim, Y; Lee, S; Song, J

    2001-01-01

    The computer-based textbook is a new educational tool that promises to play a prominent role in the coming years. Classical instructional technologies, such as video, stills, audio files and computer programs with a textbook orientation, have been merged into one multimedia computer system and have created additional opportunities for learning in medical, dental and nursing education. The authors developed a hypermedia textbook of â San-Yin-Jiao pressure for reducing the labor pain and shortening the labor time' using a personal computer with hypermedia software that contains texts, images, videos, audios and literature citations. The target population of this educational CD-ROM would be nurse-midwives, clinical nurses working for the obstetric units, and faculty members who teach the Maternity and Women's Health Nursing. Valuable and practical experiences were obtained and shared. PMID:11604889

  20. Characterization of growth and photosynthesis of Synechocystis sp. PCC 6803 cultures under reduced atmospheric pressures and enhanced CO2 levels

    NASA Astrophysics Data System (ADS)

    Kanervo, Eira; Lehto, Kirsi; Ståhle, Kurt; Lehto, Harry; Mäenpää, Pirkko

    2005-01-01

    Efficient life support systems are needed to maintain adequate oxygen, water and food for humans in extraterrestrial conditions. On the near-Earth missions, these are supplied by transport from the Earth, and by physical and chemical cleaning and recycling, but on long-term missions to far-away destinations, such as Mars, on-site production of the consumables may be required. Molecular oxygen and organic biomass can be most efficiently produced biologically, i.e. by photosynthesis. The conditions on Mars are distinctly harsh, and they strictly limit the growth and survival of any photosynthetic organisms to artificially maintained containments. For obtaining most economical growth conditions, minimal parameters need to be determined which still allow efficient growth of photosynthetic organisms. In this work we are testing how reduced air pressures (hypobaria) and increased CO2 concentrations, i.e. features typical for Martian conditions, affect the durability, growth and photosynthesis of laboratory strains of cyanobacteria, a group of prokaryotic organisms capable of plant-like photosynthesis. Our preliminary results show that air pressures down to 0.1 atm or CO2 concentrations up to 20% have no harmful effect on the photosynthetic oxygen production or growth rate of the cyanobacterial model species, Synechocystis sp. PCC 6803.