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Sample records for reduced pressurized evaporator

  1. Effect of nonionic surfactant on wetting behavior of an evaporating drop under a reduced pressure environment.

    PubMed

    Sefiane, Khellil

    2004-04-15

    The evaporation of sessile drops at reduced pressure is investigated. The evaporation of water droplets on aluminum and PTFE surfaces at reduced pressure was compared. It was found that water droplets on an aluminum surface exhibit a 'depinning jump' at subatmospheric pressures. This is when a pinned droplet suddenly depins, with an increase in contact angle and a simultaneous decrease in the base width. The evaporation of sessile water droplets with a nonionic surfactant (Triton X-100) added to an aluminum surface was then studied. The initial contact angle exhibited a minimum at 0.001 wt% Triton X-100. A maximum in the evaporation rate was also observed at the same concentration. Droplets with low surfactant concentrations are found to exhibit the 'depinning jump.' It is thought that the local concentration of the surfactant causes a gradient of surface tension. The balance at the contact angle is dictated by complex phenomena, including surfactant diffusion and adsorption processes at interfaces. Due to the strong evaporation near the triple line, an accumulation of the surfactant will lead to a surface tension gradient along the interface. The gradient of surface tension will influence the wetting behavior (Marangoni effect). At low surfactant concentrations the contact line depins under the strong effect of surface tension gradient that develops spontaneously over the droplet interface due to surfactant accumulation near the triple line. The maximum evaporation rate corresponds to a minimum contact angle for a pinned droplet.

  2. Evaporation for Lithium Bromide Aqueous Solution in a Falling Film Heater under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Matsuda, Akira; Ide, Tetsuo; Yukino, Keiji

    Experiments on evaporation for water and lithium bromide (LiBr) aqueous solution were made in a externally heated wetted-wall column under reduced pressures. For water, evaporation rate increased slightly as feed rate decreased. The heat transfer coefficients of falling film agreed with those for filmwise condensation. For LiBr solution, evaporation rate decreased and outlet temperature of LiBr solution increased as feed rate decreased. The equations of continuity, diffusion and energy which assume that only water moves to the surface and LiBr doesn't move through falling film of LiBr solution were solved numerically. Calculated values of evaporation rate and outlet temperature of solution agreed with experimental results. The results of this work were compared with pool boiling data reported previously, and it was shown that falling film heater is superior to pool boiling heater concerning heat transfer.

  3. Evaporation of a picoliter droplet on a wetted substrate at reduced pressure

    NASA Astrophysics Data System (ADS)

    Saverchenko, V. I.; Fisenko, S. P.; Khodyko, Yu. A.

    2011-07-01

    The results of theoretical and experimental investigation of the evaporation of picoliter water droplets on a substrate at reduced pressure (20-80 Torr) have been given. The substrate temperature varied in the range 25-40°C. The calculations have been carried out in a free-molecular approximation. It has been shown that the evaporation time sharply decreases if the average droplet height is less than 10 μm and is a few milliseconds for a 5-μm-high droplet. It has been experimentally and theoretically shown that for droplets higher than 10 μm, the evaporation time is a few seconds in the investigated pressure range.

  4. 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

    2016-03-01

    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.

  5. 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

  6. 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…

  7. 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.

  8. 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.

  9. 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.

  10. Negative pressure characteristics of an evaporating meniscus at nanoscale

    PubMed Central

    2011-01-01

    This study aims at understanding the characteristics of negative liquid pressures at the nanoscale using molecular dynamics simulation. A nano-meniscus is formed by placing liquid argon on a platinum wall between two nano-channels filled with the same liquid. Evaporation is simulated in the meniscus by increasing the temperature of the platinum wall for two different cases. Non-evaporating films are obtained at the center of the meniscus. The liquid film in the non-evaporating and adjacent regions is found to be under high absolute negative pressures. Cavitation cannot occur in these regions as the capillary height is smaller than the critical cavitation radius. Factors which determine the critical film thickness for rupture are discussed. Thus, high negative liquid pressures can be stable at the nanoscale, and utilized to create passive pumping devices as well as significantly enhance heat transfer rates. PMID:21711621

  11. Heat Transfer and Convective Structure of Evaporating Films under Pressure-Modulated Conditions

    NASA Astrophysics Data System (ADS)

    Gonzalez, Juan Carlos

    This work examines the fluid mechanical and heat transfer characteristics of evaporating films under cyclical superheat conditions. This research was motivated by the need to further understand the instability drivers in films undergoing unsteady and cyclical evaporation. The superheat was controlled modulating the system pressure. An isolated test cell allowed the films to evaporate into their own vapor without non-condensable present. A non-intrusive thickness measurement technique was used to yield dynamic heat flux measurements. A double pass schlieren system was employed to capture convective structures. System temperature and pressure measurements completed the diagnostics. The primary conclusions are briefly summarized as follows: • The evolution of thermal profile within evaporating films has a strong impact on the development of convective structure and heat transfer. In some cases convective structure appears within the film under pressure-modulated conditions even when the evaporation intervals are sufficiently short that conduction is expected to be the only heat transfer mode within the film. • Convective structure appears to persist in many cases even after evaporation is stopped. • Stopping the evaporation for short time intervals appears to have a negligible effect on the temperature profile in the film based on the subsequent evaporation behavior. • Complex, multi-wavelength convective structure behavior can be induced through cyclical superheating of the films. • A modest gain in short-term heat flux is achievable under some pressure-modulated conditions. • Surface instabilities of quasi-steady evaporating films do not lead to an increase in the evaporation rate. • Reduced gravity tests were seriously compromised by unsteady g-levels and g-jitter.

  12. 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

  13. Correlation of chemical evaporation rate with vapor pressure.

    PubMed

    Mackay, Donald; van Wesenbeeck, Ian

    2014-09-02

    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.

  14. 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.

  15. 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.

  16. 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.

  17. Prediction of pressure drops accompanying the evaporation of refrigerants inside horizontal tubes. Technical memo

    SciTech Connect

    Stoneham, H.G.; Saluja, S.N.; Dunn, A.

    1980-01-01

    Four of the more widely used correlations for the prediction of pressure drops were compared with published experimental data using statistical techniques. None of the correlations examined were found to be suitably accurate over the range of conditions normally encountered in direct expansion evaporators. A new correlation was developed and is presented here, that can be used with an acceptable degree of accuracy by the design engineer. The correlation is presented in a form that can be easily written into a program for solution on a programmable calculator leading to quick and accurate evaluation of the pressure drop that accompanies a refrigerant evaporatoring inside a horontal tube evaporator.

  18. Salinity is Reduced Below the Evaporation Front During Soil Salinization

    NASA Astrophysics Data System (ADS)

    Gran, M.; Carrera, J.; Olivella, S.; Massana, J.; Saaltink, M. W.; Ayora, C.; Lloret, A.

    2009-04-01

    Nearly 50% of irrigated lands in arid and semi-arid regimes have salinization problems. Salinization is generally caused by salts carried to the soil surface by capillary rising water and occurs under very dry conditions, when vapor fluxes become the main water flux mechanism. Despite its global importance, actual salinization mechanisms are only poorly understood. Soil salinization is generally studied by means of water and salt balances without entering on small scale processes. This may suffice for explaining large scale behavior but hardly for designing remediation practices. The objective of this work is to study the solute transport under evaporation conditions. We have performed laboratory experiments and modelled them. We have built open sand columns initially saturated with an epsomite (MgSO4•7H2O) solution. Evaporation was driven by an infrared lamp and proceeded until the overall saturation fell down to 0.32. Results imply that water vapor flows not only upwards above the evaporation front, but also downwards beneath this front, where it condensates. Condensation causes the dilution of the solution. That is, concentrations fall below the initial values. The experiments have been modelled with the program Retraso-CodeBright, which couples non isothermal multiphase flow and reactive transport. Reproducing the observations required modifying the standard retention and relative permeability functions to include oven dry conditions. The model reproduces the observed concentration, water content and temperature profiles along the column and confirms the existence of condensation and decrease of salt concentration below the evaporation front. The model also allows us to distinguish the relevance between the advective and diffusive vapor fluxes, showing that the latter is, by far, the largest. The mechanism displays positives feedbacks, as condensation will be most intense in areas of highest salinity, thus diluting saline water that may have infiltrated.

  19. 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.

  20. Pressure-induced evaporation dynamics of gold nanoparticles on oxide substrate.

    PubMed

    Meng, Gang; Yanagida, Takeshi; Kanai, Masaki; Suzuki, Masaru; Nagashima, Kazuki; Xu, Bo; Zhuge, Fuwei; Klamchuen, Annop; He, Yong; Rahong, Sakon; Kai, Shoichi; Kawai, Tomoji

    2013-01-01

    Here we report thermal evaporation dynamics of Au nanoparticles on single crystal oxide substrates, including MgO, SrTiO(3), and Al(2)O(3). The size reduction rate of Au nanoparticles via thermal treatments is strongly dependent on not only temperature but also pressure. Lowering the pressure of inert Ar gas from 10(5) to 10 Pa increases the size reduction rate over 30 times in the temperature range 800 °C-950 °C. The temperature dependence is solely due to the variation of saturated vapor pressure of Au, whereas the pressure dependence of the surrounding inert gas can be interpreted in terms of a pressure dependence on a gas-phase diffusion of evaporated Au atoms into the surroundings. We present a simplified model to explain an evaporation dynamics, which well describes the pressure dependence on a size reduction rate of Au nanoparticles. By utilizing this useful pressure-induced evaporation dynamics, we succeeded in manipulating a size reduction of Au nanoparticle arrays down to -10 nm diameter range from -300 nm initial size by programming sequentially a surrounding pressure.

  1. 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.

  2. 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.

  3. 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…

  4. 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…

  5. 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.

  6. 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.

  7. 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.

  8. Evaluation of evaporation coefficient for micro-droplets exposed to low pressure: A semi-analytical approach

    NASA Astrophysics Data System (ADS)

    Chakraborty, Prodyut R.; Hiremath, Kirankumar R.; Sharma, Manvendra

    2017-02-01

    Evaporation rate of water is strongly influenced by energy barrier due to molecular collision and heat transfer limitations. The evaporation coefficient, defined as the ratio of experimentally measured evaporation rate to that maximum possible theoretical limit, varies over a conflicting three orders of magnitude. In the present work, a semi-analytical transient heat diffusion model of droplet evaporation is developed considering the effect of change in droplet size due to evaporation from its surface, when the droplet is injected into vacuum. Negligible effect of droplet size reduction due to evaporation on cooling rate is found to be true. However, the evaporation coefficient is found to approach theoretical limit of unity, when the droplet radius is less than that of mean free path of vapor molecules on droplet surface contrary to the reported theoretical predictions. Evaporation coefficient was found to reduce rapidly when the droplet under consideration has a radius larger than the mean free path of evaporating molecules, confirming the molecular collision barrier to evaporation rate. The trend of change in evaporation coefficient with increasing droplet size predicted by the proposed model will facilitate obtaining functional relation of evaporation coefficient with droplet size, and can be used for benchmarking the interaction between multiple droplets during evaporation in vacuum.

  9. Development of Apparatus for Microgravity Experiments on Evaporation and Combustion of Palm Methyl Ester Droplet in High-Pressure Environments

    NASA Astrophysics Data System (ADS)

    Suzuki, Masato; Nomura, Hiroshi; Hashimoto, Nozomu

    New apparatus for microgravity experiments was developed in order to obtain fundamental data of single droplet evaporation and combustion of palm methyl ester (PME) for understanding PME spray combustion in internal combustion engines. n-hexadecane droplet combustion and evaporation experiments were also performed to obtain single-component fuel data. Combustion experiments were performed at atmospheric pressure and room temperature. For droplet evaporation experiments, ambient temperature and pressure were varied from 473 to 873 K and 0.10 to 4.0 MPa, respectively. Microgravity conditions were employed for evaporation experiments to prevent natural convection. Droplet diameter history of a burning PME droplet is similar to that of n-hexadecane. Droplet diameter history of an evaporating PME droplet is different from that of n-hexadecane at low ambient temperatures. In the latest stage of PME droplet evaporation, temporal evaporation constant decreases remarkably. At ambient temperatures sufficiently above the boiling temperature of PME components, droplet diameter history of PME and n-hexadecane are similar to each other. Corrected evaporation lifetime τ of PME at 873 K as a function of ambient pressure was obtained at normal and microgravity. At normal gravity, τ monotonically decreases with ambient pressure. On the other hand, at microgravity, τ increases with ambient pressure, and then decreases.

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

    SciTech Connect

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

    1985-02-01

    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. 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.

  12. An experimental investigation of pressure drop in forced-convection condensation and evaporation of oil-refrigerant mixtures

    SciTech Connect

    Tichy, J.A.; Duque-Rivera, J.; Macken, N.A.; Duval, W.M.B.

    1986-01-01

    Experimental measurements of pressure drop have been made for forced-convection evaporation and condensation of oil-refrigerant (R-12) mixtures inside a horizontal tube. Data were compared to a wide range of frictional pressure drop and void fraction relationships. The best representations for the oil-free data were then modified to better correlate both oil-free and oil-refrigerant results. For condensation, a modification of the prediction given by the Lockhart-Martinelli relation for frictional pressure drop and the homogeneous void fraction model is presented. For evaporation, the prediction given by the Dukler II frictional pressure-drop correlation and the homogeneous void fraction is modified. These relationships predict the pressure drop for 85% of the data to within +- 35%. The added oil increased the pressure drop 2% to 6% for condensation and 63% to 86% for evaporation.

  13. Monitoring Air Circulation Under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim

    Adequate air circulation is required for controlled environments to maintain uniform temperature and humidity control, and hence the ability to measure air flow accurately is important. Human and associated life support habitats (e.g.,. plant production systems) for future space missions will likely be operated at pressures less than 100 kPa to minimize gas leakage and structural mass. Under such reduced pressures, the outputs from conventional anemometers for monitoring air flow can change and require re-calibration. These effects of atmospheric pressure on different types of air flow measurements are not completely understood; hence we compared the performance of several air flow sensors across a range of hypobaric pressures. Sensors included a propeller type anemometer, a hot-wire anemometer, and a Pitot-tube based device. Theoretical schematics (including mathematical models) underlying these measurements were developed. Results demonstrated that changes in sensor outputs were predictable based on their operating principles, and that corrections could be developed for sensors calibrated under normal Earth atmosphere pressure ( 100 kPa) and then used at different pressures. The potential effects of hypobaric atmospheres and their altered air flows on plant physiology are also discussed.

  14. 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.

  15. Thermal Evaporation Synthesis and Properties of ZnO Nano/Microstructures Using Carbon Group Elements as the Reducing Agents.

    PubMed

    Lv, H; Sang, Dd; Li, Hd; Du, Xb; Li, Dm; Zou, Gt

    2010-01-21

    ZnO nano/microstructures have been formed by thermal evaporation method using ZnO powders mixed with carbon group elements (C, Si, Ge, Sn, or Pb) as the reducing agent. For cases of mixed precursors of ZnO/C, ZnO/Si, and ZnO/Ge, the pure ZnO nano/microstructures are realized, while for ZnO/Sn (ZnO/Pb) systems, the phase of Pb2O3(Zn2SnO4) generally are represented in the ZnO products. The appearance of Pb2O3(Zn2SnO4) is attributed to the lower melting point and higher vapor pressure of Sn (Pb) in the heating and evaporation processes. The morphologies and sizes of the products are controlled by adjusting the growth regions and/or introducing gaseous argon. Room temperature (RT) photoluminescence spectra indicate that the intensity (peak position) of the ultraviolet emission is increased (redshift) due to the existence of Zn2SnO4 phase in the ZnO products. The Pb2O3(Zn2SnO4) phase in ZnO nano/microstructures plays a important role in enhancing the saturation magnetizations of RT ferromagnetism with respect to the case of pure ZnO products fabricated by the precursor of mixed ZnO and graphite.

  16. Can Weight Loss Reduce the Need for Blood Pressure Medication?

    MedlinePlus

    ... weight loss reduce the need for blood pressure medication? Answers from Sheldon G. Sheps, M.D. If ... possible to reduce your dose of blood pressure medication — or stop taking your blood pressure medication completely. ...

  17. 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.

  18. 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.

  19. 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.

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

    DOEpatents

    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. 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.

  3. 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.

  4. 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.

  5. Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores.

    PubMed

    Morishige, Kunimitsu; Tateishi, Masayoshi

    2006-04-25

    To examine the theoretical and semiempirical relations between pore size and the pressure of capillary condensation or evaporation proposed so far, we constructed an accurate relation between the pore radius and the capillary condensation and evaporation pressure of nitrogen at 77 K for the cylindrical pores of the ordered mesoporous MCM-41 and SBA-15 silicas. Here, the pore size was determined from a comparison between the experimental and calculated X-ray diffraction patterns due to X-ray structural modeling recently developed. Among the many theoretical relations that differ from each other in the degree of theoretical improvements, a macroscopic thermodynamic approach based on Broekhoff-de Boer equations was found to be in fair agreement with the experimental relation obtained in the present study.

  6. Design and development of low pressure evaporator/condenser unit for water-based adsorption type climate control systems

    NASA Astrophysics Data System (ADS)

    Venkataramanan, Arjun; Rios Perez, Carlos A.; Hidrovo, Carlos H.

    2016-11-01

    Electric vehicles (EVs) are the future of clean transportation and driving range is one of the important parameters which dictates its marketability. In order to increase driving range, electrical battery energy consumption should be minimized. Vapor-compression refrigeration systems currently employed in EVs for climate control consume a significant fraction of the battery charge. Thus, by replacing this traditional heating ventilation and air-conditioning system with an adsorption based climate control system one can have the capability of increasing the drive range of EVs.The Advanced Thermo-adsorptive Battery (ATB) for climate control is a water-based adsorption type refrigeration cycle. An essential component of the ATB is a low pressure evaporator/condenser unit (ECU) which facilitates both the evaporation and condensation processes. The thermal design of the ECU relies predominantly on the accurate prediction of evaporation/boiling heat transfer coefficients since the standard correlations for predicting boiling heat transfer coefficients have large uncertainty at the low operating pressures of the ATB. This work describes the design and development of a low pressure ECU as well as the thermal performance of the actual ECU prototype.

  7. Novel reduced pressure-balance syringe for chromatographic analysis.

    PubMed

    Windom, Bret C; Bruno, Thomas J

    2010-11-19

    When withdrawing a fluid sample (for additional chromatographic analyses) from an apparatus operated at a reduced pressure, a typical syringe proves to be ineffective (even if it is equipped with a gas tight plunger). It simply does not create enough pressure differential to remove a fluid sample from a reduced pressure environment. We encountered such a situation as part of efforts to extend the operation of the advanced distillation curve protocol to reduced pressures. The problem was solved by the development of a pressure balance syringe that allows reliable and precise sampling from an apparatus operating at sub-ambient pressures. This new device uses an external vacuum source to evacuate a syringe barrel, allowing a user to withdraw fluid samples from environments with pressures as low as 0.5kPa. To demonstrate the operation of the newly developed device, distillate analyses were performed on two fluids at low pressure: a predefined validation mixture, and a commercial soy based biodiesel fuel. The pressure balance syringe was used successfully for sampling in both cases. The use of the pressure balance syringe is not limited to reduced pressure distillations; indeed it can be used for a variety of applications in which chemical/compositional analyses are desired on a fluid contained in a reduced pressure environment.

  8. 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.

  9. 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.

  10. 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.

  11. Importance of pressure reducing valves (PRVs) in water supply networks.

    NASA Astrophysics Data System (ADS)

    Signoreti, R. O. S.; Camargo, R. Z.; Canno, L. M.; Pires, M. S. G.; Ribeiro, L. C. L. J.

    2016-08-01

    Challenged with the high rate of leakage from water supply systems, these managers are committed to identify control mechanisms. In order to standardize and control the pressure Pressure Reducing Valves (VRP) are installed in the supply network, shown to be more effective and provide a faster return for the actual loss control measures. It is known that the control pressure is while controlling the occurrence of leakage. Usually the network is sectored in areas defined by pressure levels according to its topography, once inserted the VRP in the same system will limit the downstream pressure. This work aims to show the importance of VRP as loss reduction for tool.

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

    DOE PAGES

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; ...

    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

  13. 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.

  14. 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...

  15. 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.

  16. Evaporation rates and vapor pressures of individual aerosol species formed in the atmospheric oxidation of alpha- and beta-pinene.

    PubMed

    Bilde, M; Pandis, S N

    2001-08-15

    The semivolatile oxidation products (trans-norpinic acid, pinic acid, cis-pinonic acid, etc.) of the biogenic monoterpenes (alpha-pinene, beta-pinene, etc.) contribute to the atmospheric burden of particulate matter. Using the tandem differential mobility analysis (TDMA) technique evaporation rates of glutaric acid, trans-norpinic acid, and pinic acid particles were measured in a laminar flow reactor. The vapor pressure of glutaric acid was found to be log(p0 glutaric/Pa) = - 3,510 K/T + 8.647 over the temperature range 290-300 K in good agreement with the values previously reported by Tao and McMurry (1989). The measured vapor pressure of trans-norpinic acid over the temperature range 290-312 K is log(p0 norpinic/Pa) = - 2,196.9 K/T + 3.522, and the vapor pressure of pinic acid is log(p0 pinic/ Pa) = - 5,691.7 K/T + 14.73 over the temperature range 290-323 K. The uncertainty on the reported vapor pressures is estimated to be approximately +/- 50%. The vapor pressure of cis-pinonic acid is estimated to be of the order of 7 x 10(-5) Pa at 296 K.

  17. 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.

  18. 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.

  19. High-pressure saline washing of allografts reduces bacterial contamination.

    PubMed

    Hirn, M Y; Salmela, P M; Vuento, R E

    2001-02-01

    60 fresh-frozen bone allografts were contaminated on the operating room floor. No bacterial growth was detected in 5 of them after contamination. The remaining 55 grafts had positive bacterial cultures and were processed with three methods: soaking in saline, soaking in antibiotic solution or washing by high-pressure saline. After high-pressure lavage, the cultures were negative in three fourths of the contaminated allografts. The corresponding figures after soaking grafts in saline and antibiotic solution were one tenth and two tenths, respectively. High-pressure saline cleansing of allografts can be recommended because it improves safety by reducing the superficial bacterial bioburden.

  20. 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

  1. 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

  2. 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...

  3. Reduced pressure for fewer pressure ulcers: can real-time feedback of interface pressure optimise repositioning in bed?

    PubMed

    Gunningberg, Lena; Carli, Cheryl

    2016-10-01

    The aim of this study was to (i) describe registered nurses' and assistant nurses' repositioning skills with regard to their existing attitudes to and theoretical knowledge of pressure ulcer (PU) prevention, and (ii) evaluate if the continuous bedside pressure mapping (CBPM) system provides staff with a pedagogic tool to optimise repositioning. A quantitative study was performed using a descriptive, comparative design. Registered nurses (n = 19) and assistant nurses (n = 33) worked in pairs, and were instructed to place two volunteers (aged over 70 years) in the best pressure-reducing position (lateral and supine), first without viewing the CBPM monitor and then again after feedback. In total, 240 positionings were conducted. The results show that for the same person with the same available pressure-reducing equipment, the peak pressure varied considerably between nursing pairs. Reducing pressure in the lateral position appeared to be the most challenging. Peak pressures were significantly reduced, based on visual feedback from the CBPM monitor. The number of preventive interventions also increased, as well as patients' comfort. For the nurses as a group, the knowledge score was 59·7% and the attitude score was 88·8%. Real-time visual feedback of pressure points appears to provide another dimension to complement decision making with respect to PU prevention.

  4. Evaporative cooling with sprinklers to reduce heat-related fruit damage in northern highbush blueberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hot and sunny weather can cause a considerable amount of fruit damage in blueberries and results in millions of dollars of crop loss each year. The objective of this study was to evaluate the efficacy of using sprinklers to reduce the damage. The study was conducted for 2 years in a mature planting ...

  5. 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.

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

    SciTech Connect

    Anklam, T.M.; Berzins, L.V.; Braun, D.G.; Haynam, C.; McClelland, M.A.; Meier, T.

    1994-10-01

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

  7. Vegetation stress from increased vapor pressure deficit implicated in recent decline in U.S. evaporation

    NASA Astrophysics Data System (ADS)

    Salvucci, Guido, D.; Rigden, Angela

    2016-04-01

    We detect and attribute long-term changes in evapotranspiration (ET) over the contiguous United States from 1961 to 2013 using an approach we refer to as the ETRHEQ method (Evapotranspiration from Relative Humidity at Equilibrium). The ETRHEQ method primarily uses meteorological data collected at common weather stations. Daily ET is inferred by choosing the surface conductance to water vapor transport that minimizes the vertical variance of the calculated relative humidity profile averaged over the day. The key advantage of the ETRHEQ method is that it does not require knowledge of the surface state (soil moisture, stomatal conductance, leaf are index, etc.) or site-specific calibration. We estimate daily ET at 229 weather stations for 53 years. Across the U.S., we find a decrease in summertime (JJAS) ET of 0.21 cm/yr/yr from 1961-2013 with recent (1998-2013) declines in summertime ET of 1.08 cm/yr/yr. We decompose the ET trends into the dominant environmental drivers. Our results suggest that the recent decline in ET is due to increased vegetation stress induced by increases in vapor pressure deficit. We will present out results in context of other commonly used, regional ET data products.

  8. 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.

  9. 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.

  10. 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).

  11. 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.

  12. 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.

  13. Gasoline Reid Vapor Pressure

    EPA Pesticide Factsheets

    EPA regulates the vapor pressure of gasoline sold at retail stations during the summer ozone season to reduce evaporative emissions from gasoline that contribute to ground-level ozone and diminish the effects of ozone-related health problems.

  14. 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.

  15. 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.

  16. 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

  17. Droplet evaporation study applied to DNA chip manufacturing.

    PubMed

    Dugas, Vincent; Broutin, Jérôme; Souteyrand, Eliane

    2005-09-27

    DNA chips are potentially powerful technologies for genotyping and gene expression profiling that rely on comparative analyses of up to thousands of "spots of analysis" on a glass support. The spot quality throughout the support influences spot-to-spot variations within an array and the repeatability of data across experiments. For glass slide DNA microarrays, droplets of DNA solution are deposited on functionalized glass slides and left to react through complete evaporation of the droplet. On hydrophobic flat surfaces, different modes of droplet evaporation can be attained. Under atmospheric pressure, water droplets tend to evaporate under two main regimes. Initially, the droplet flattens with a constant contact area, and then the droplet shrinks at a constant contact angle. As a result, the diameter and morphology of thousands of spots on microarrays are not uniform. This leads to poor and unreliable data processing results. In this work, we report the evaporation of an aqueous solution under a constant contact area mode. Evaporation under reduced pressure and the effect of reagent additives to the solution have been investigated. Video microscopy and digital image analysis techniques were applied to monitor the evaporation of the droplets. A mixture of surfactants was developed to maintain a constant area regime during evaporation and to form homogeneous spots. The control of some physicochemical properties (wetting, evaporation rate) of the droplet allows the formation of well-controlled spots compatible with DNA grafting. The influence of surfactant molecules on the mechanisms of evaporation is also discussed.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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?

  3. 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.

  4. Assessing the ability of potential evaporation formulations to capture the dynamics in evaporative demand within a changing climate

    NASA Astrophysics Data System (ADS)

    Donohue, Randall J.; McVicar, Tim R.; Roderick, Michael L.

    2010-05-01

    SummaryRates of evaporative demand can be modelled using one of numerous formulations of potential evaporation. Physically, evaporative demand is driven by four key variables - net radiation, vapour pressure, wind speed, and air temperature - each of which have been changing across the globe over the past few decades. In this research we examine five formulations of potential evaporation, testing for how well each captures the dynamics in evaporative demand. We generated daily potential evaporation datasets for Australia, spanning 1981-2006, using the: (i) Penman; (ii) Priestley-Taylor; (iii) Morton point; (iv) Morton areal; and (v) Thornthwaite formulations. These represent a range in how many of the key driving variables are incorporated within modelling. The testing of these formulations was done by analysing the annual and seasonal trends in each against changes in precipitation (a proxy for actual evaporation), assuming that they should vary in an approximately inverse manner. The four-variable Penman formulation produced the most reasonable estimation of potential evaporation dynamics. An attribution analysis was performed using the Penman formulation to quantify the contribution of each input variable to overall trends in potential evaporation. Whilst changes in air temperature were found to produce a large increase in Penman potential evaporation rates, changes in the other key variables each reduced rates, resulting in an overall negative trend in Penman potential evaporation. This study highlights the need for spatially and temporally dynamic data describing all drivers of evaporative demand, especially projections of each driving variable when estimating the possible affects of climatic changes on evaporative demand.

  5. 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.

  6. 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.

  7. 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…

  8. 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)

  9. Intraocular pressure with rebound tonometry and effects of topical intraocular pressure reducing medications in guinea pigs

    PubMed Central

    Di, Yue; Luo, Xiu-Mei; Qiao, Tong; Lu, Na

    2017-01-01

    AIM To investigate the intraocular pressure (IOP) of adult guinea pig eyes with rebound tonometry (RBT), and assess the effects of four distinctive topical IOP reducing medications including Carteolol, Brimonidine, Brinzolamide and Latanoprost. METHODS The IOPs of twenty-four 12-week-old guinea pigs (48 eyes) were measured every two hours in one day with RBT as baselines. All the animals were then divided into four groups (Carteolol, Brimonidine, Brinzolamide and Latanaprost groups, n=6). The IOPs were measured and compared to the baseline 1, 2, 3, 5, 7, 9, 15 and 24h after treatment. RESULTS The mean baseline IOP of 24 guinea pigs (48 eyes) was 10.3±0.36 mm Hg (6-13 mm Hg) and no binocular significant differences of IOPs were observed (t=1.76, P>0.05). No significant difference of IOP in Carteolol group at each time point was observed before and after treatment (t=1.48, P>0.05). In Brimonidine group, IOP was 2.2±1.9 mm Hg lower than the baseline after one hour (t=3.856, P=0.003) and lasted for one hour. In Brinzolamide group, IOP was 1.4±1.1 mm Hg lower than the baseline after one hour (t=4.53, P=0.001) and lasted for 7h and the IOP declined most at 3h. In Latanaprost group, IOP was 2.1±1.3 mm Hg lower than the baseline after one hour (t=6.11, P=0.001) and lasted for one hour. CONCLUSION The IOP of guinea pig eyes is relatively stable compared to human eyes. In four reducing IOP medications, no significant effect of Carteolol is observed. Brinzolamide has the longest duration, while the Brimonidine has the shortest duration and the maximum level of treatment. PMID:28251075

  10. Porous plug for reducing orifice induced pressure error in airfoils

    NASA Technical Reports Server (NTRS)

    Plentovich, Elizabeth B. (Inventor); Gloss, Blair B. (Inventor); Eves, John W. (Inventor); Stack, John P. (Inventor)

    1988-01-01

    A porous plug is provided for the reduction or elimination of positive error caused by the orifice during static pressure measurements of airfoils. The porous plug is press fitted into the orifice, thereby preventing the error caused either by fluid flow turning into the exposed orifice or by the fluid flow stagnating at the downstream edge of the orifice. In addition, the porous plug is made flush with the outer surface of the airfoil, by filing and polishing, to provide a smooth surface which alleviates the error caused by imperfections in the orifice. The porous plug is preferably made of sintered metal, which allows air to pass through the pores, so that the static pressure measurements can be made by remote transducers.

  11. Pressure needed to reduce microannulus effect on CBL

    SciTech Connect

    Pilkington, P.E.

    1988-05-30

    Four different types of microannuluses can invalidate cement bond logs, but there are ways to cope with them and obtain valid logs. Only one is a rule-of-thumb procedure. The others are better ways to determine the pressure required for eliminating any microannulus effect. The microannulus effect on cement bond logs, CBL, has long been recognized. Various authors have presented rules-of-thumb to eliminate the microannulus effect so that a properly centered, calibrated, and gated tool can yield a valid cement bond log. This article reviews the various causes of the microannulus and discusses what surface pressure is required to minimize the microannulus effect on the CBL of thermal, produced, induced, and squeeze microannuluses. The unique problem of handling the microannulus in floating drilling operations is another subject.

  12. 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.

  13. Role of oxygen pressure on the structural, morphological and optical properties of c-Al2O3 films deposited by thermal evaporator

    NASA Astrophysics Data System (ADS)

    Khan, Ijaz Ahmad; Amna, Noureen; Kanwal, Nosheen; Razzaq, Maleeha; Farid, Amjad; Amin, Nasir; Ikhlaq, Uzma; Saleem, Murtaza; Ahmad, Riaz

    2017-03-01

    Aluminum oxide (c-Al2O3) films are deposited for various (0.5, 1, 1.5 and 2 mbar) oxygen pressures on glass substrates by thermal evaporator. The x-ray diffraction patterns exhibit the development of single diffraction peak related to c-Al2O3 phase which grows along (2 2 0) orientation up to 1.5 mbar pressure. For 2 mbar pressure, the deposited film becomes amorphous because no diffraction peak is observed. A minimum FWHM and maximum crystallite size of c-Al2O3 (2 2 0) plane is observed for 1 mbar pressure. The enhanced crystallite size of c-Al2O3 (2 2 0) plane is responsible to decrease the dislocation density and residual stresses developed during the deposition process. The field emission scanning electron microscopic analysis reveals the formation of smooth, uniform and compact films showing uniform distribution of nano-particles of different shapes and sizes. The energy dispersive x-ray spectroscopic analysis confirms the presence of Al whose content is decreased with the increase of oxygen pressures. The ellipsometric analysis confirms that the refractive index and the thickness of c-Al2O3 film deposited for 0.5 mbar pressure are found to 1.685 and 124.43 nm respectively. In short, the crystal structure, surface morphology, film thickness and refractive index of c-Al2O3 films are associated with the increase of oxygen pressures.

  14. 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.

  15. 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.

  16. 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.

  17. Evaporation characteristics of ETBE-blended gasoline.

    PubMed

    Okamoto, Katsuhiro; Hiramatsu, Muneyuki; Hino, Tomonori; Otake, Takuma; Okamoto, Takashi; Miyamoto, Hiroki; Honma, Masakatsu; Watanabe, Norimichi

    2015-04-28

    To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were developed.

  18. 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.

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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.

  1. 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.

  2. 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.

  3. Approaches for reducing the insulator-metal transition pressure in hydrogen

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Ashcroft, N. W.

    1983-01-01

    Two possible techniques for reducing the external pressure required to induce the insulator-metal transition in solid hydrogen are described. One uses impurities to lower the energy of the metallic phase relative to that of the insulating phase. The other utilizes a negative pressure induced in the insulating phase by electron-hole pairs, created either with laser irradiation or pulsed synchrotron sources.

  4. 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.

  5. Effect of Concentration on Evaporation Rate for Lithium Bromide Aqueous Solution in a Falling Film Heater

    NASA Astrophysics Data System (ADS)

    Matsuda, Akira; Ide, Tetsuo

    Experiments on evaporation for lithium bromide aqueous solution (0-55 wt% LiBr) were made in Summary a externally heated wetted-wall column under reduced pressures. The evaporation rates of 5 and 8 wt% LiBr-water solutions were similar to those of water. The evaporation rates, however, owered with further increase of the concentration of LiBr, and at low feed rates the evaporation rates lowered with decrease of the feed rate because the temperature of the falling film rose. On the other hand, at high feed rates the evaporation rates lowered with increase of feed rates because the heat transfer coefficients of the falling film decreased. Therefore, a maximum evaporation rate existed and it was supposed that there is the optimum feed rate. The experimental data agreed with the values that were calculated numerically based on the unidirectional model that lithium bromide didn't move through falling film.

  6. 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*.

  7. Droplet evaporation with complexity of evaporation modes

    NASA Astrophysics Data System (ADS)

    Hwang, In Gyu; Kim, Jin Young; Weon, Byung Mook

    2017-01-01

    Evaporation of a sessile droplet often exhibits a mixed evaporation mode, where the contact radius and the contact angle simultaneously vary with time. For sessile water droplets containing polymers with different initial polymer concentrations, we experimentally study their evaporation dynamics by measuring mass and volume changes. We show how diffusion-limited evaporation governs droplet evaporation, regardless of the complexity of evaporation behavior, and how the evaporation rate depends on the polymer concentration. Finally, we suggest a unified expression for a diffusion-limited evaporation rate for a sessile droplet with complexity in evaporation dynamics.

  8. Microcantilever sensors for monitoring the evaporation of microdrops of pure liquids and mixtures.

    PubMed

    Liu, Chuanjun; Bonaccurso, Elmar

    2010-01-01

    We describe in detail a nonimaging technique that allows the measurement of the mass, the radius, and the contact angle of evaporating sessile microdrops of pure liquids and binary mixtures. The microdrops were deposited onto hydrophobized silicon microcantilevers whose bending and resonance frequency were monitored during drop evaporation. We verify the laws of evaporation kinetics for microdrops with diameters from 80 down to 10 microm. The evaporation of mixtures of water/ethanol drops confirmed previous results with millimeter sized drops. N,N-dimethylformamide drops undergo a transformation from an initial spherical shape to a thin film. Flattening of the drop causes a slowdown of the evaporation kinetics at the end. Two concurring factors are at its origin: the rising disjoining pressure stabilizes the thin liquid film and the increasing radius of curvature of the drop reduces the vapor pressure.

  9. Microcantilever sensors for monitoring the evaporation of microdrops of pure liquids and mixtures

    NASA Astrophysics Data System (ADS)

    Liu, Chuanjun; Bonaccurso, Elmar

    2010-01-01

    We describe in detail a nonimaging technique that allows the measurement of the mass, the radius, and the contact angle of evaporating sessile microdrops of pure liquids and binary mixtures. The microdrops were deposited onto hydrophobized silicon microcantilevers whose bending and resonance frequency were monitored during drop evaporation. We verify the laws of evaporation kinetics for microdrops with diameters from 80 down to 10 μm. The evaporation of mixtures of water/ethanol drops confirmed previous results with millimeter sized drops. N,N-dimethylformamide drops undergo a transformation from an initial spherical shape to a thin film. Flattening of the drop causes a slowdown of the evaporation kinetics at the end. Two concurring factors are at its origin: the rising disjoining pressure stabilizes the thin liquid film and the increasing radius of curvature of the drop reduces the vapor pressure.

  10. 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.

  11. 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.

  12. No graduated pressure profile in compression stockings still reduces muscle fatigue.

    PubMed

    Miyamoto, N; Kawakami, Y

    2015-03-01

    Most sporting compression stockings possess a graduated pressure profile. However, it remains unclear whether the graduated pressure profile is an essential feature for reducing the development of muscle fatigue. This study sought to examine the effect of the pressure profile of compression stockings on the degree of muscle fatigue of lower leg muscles induced by submaximal running exercise. 15 male subjects performed 30-min treadmill running in 1 control and 4 compression stocking conditions with the following profiles; 1) graduated low pressure, 2) graduated high pressure, 3) uniform pressure distribution, and 4) localized pressure just over the gastrocnemius muscle belly. Before and immediately after the exercise, T2-weighted magnetic resonance images of the right lower leg were obtained without testing garments. T2 values of the triceps surae and tibialis anterior were calculated from the images. T2 was significantly increased after the running in all conditions. The magnitude of T2 increase was significantly greater in the control than in other 3 conditions except for the one with graduated low pressure, whereas there were no significant differences among the latter 3 conditions. The findings suggest that a graduated pressure profile is not an essential feature of compression stockings for reducing the development of muscle fatigue during submaximal running exercise.

  13. Evaporation of inclined water droplets.

    PubMed

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2017-02-16

    When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets.

  14. Evaporation of inclined water droplets

    NASA Astrophysics Data System (ADS)

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2017-02-01

    When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets.

  15. Evaporation of inclined water droplets

    PubMed Central

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2017-01-01

    When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets. PMID:28205642

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Measurement of evaporation from snow

    NASA Astrophysics Data System (ADS)

    Kaser, G.

    1982-04-01

    As part of a combined study of the ice, water and energy balance of Hintereisferner (Ötztal Alps) evaporation from snow and ice is measured since 1978 at an altitudes of 3030 m. These measurements are performed with plexiglass lysimeters of 400 em2 surface area. Evaluation of meteorological records yield a good correlation of evaporation with the difference of vapor pressure of the air and of the surface, respectively, for various classes of wind speed. The daily variation displays maximum evaporation before noon, and condensation during the afternoon with a maximum two hours after sunset. There is a sharp reversal from condensation to evaporation around midnight. The mean evaporation of a 12-day period in July/August 1980 was 0.25 mm per day, with a peak of 2.0 mm per day.

  1. 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.

  2. 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.

  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. Current Perspectives on the Use of Meditation to Reduce Blood Pressure

    PubMed Central

    Goldstein, Carly M.; Josephson, Richard; Xie, Susan; Hughes, Joel W.

    2012-01-01

    Meditation techniques are increasingly popular practices that may be useful in preventing or reducing elevated blood pressure. We reviewed landmark studies and recent literature concerning the use of meditation for reducing blood pressure in pre-hypertensive and hypertensive individuals. We sought to highlight underlying assumptions, identify strengths and weaknesses of the research, and suggest avenues for further research, reporting of results, and dissemination of findings. Meditation techniques appear to produce small yet meaningful reductions in blood pressure either as monotherapy or in conjunction with traditional pharmacotherapy. Transcendental meditation and mindfulness-based stress reduction may produce clinically significant reductions in systolic and diastolic blood pressure. More randomized clinical trials are necessary before strong recommendations regarding the use of meditation for high BP can be made. PMID:22518287

  5. 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

  6. Single-layer versus two-layer stamps for reduced pressure thermal nanoimprint

    NASA Astrophysics Data System (ADS)

    Papenheim, Marc; Dhima, Khalid; Wang, Si; Steinberg, Christian; Scheer, Hella-Christin

    2015-11-01

    Low-pressure imprint is interesting to avoid stamp deformation, stamp failure as well as polymer recovery. When large-area stamps are prepared with a stepping procedure, low pressure is required to optimize the stitching. However, with low-pressure imprint, conformal contact between stamp and substrate is critical. Admittedly, the imprint pressure required for conformal contact depends on the stamp material and its thickness. To get an idea to which extent the imprint pressure can be reduced with a flexible stamp, we compared different stamp materials and stamp architectures, single-layer stamps and two-layer stamps. The two-layer stamps are replica stamps, where the structures were replicated in a thin layer of OrmoStamp, fixed by a backplane. On the background of plate theory, we deduce the pressure reduction compared to a Si stamp by calculating the respective pressure ratio, independent from geometries. In addition, temperature-induced issues are addressed which are of relevance for a thermal imprint process. These issues are related to the mismatch between the thermal expansion coefficients of the stamp and the substrate, and in case of a two-layer stamp, to the mismatch between the backplane material and the top layer. The latter results in temperature-induced stamp bending. On the basis of simple analytical calculations, the potential of single-layer stamps and two-layer stamps with respect to thermal imprint at reduced pressure is discussed and guidelines are provided to assess the imprint situation when replica stamps are used for imprint. The results demonstrate the attractiveness of two-layer stamps for reduced pressure nanoimprint, even in a temperature-based process.

  7. 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.

  8. Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia

    DTIC Science & Technology

    2006-09-01

    NM, Joyner MJ. Influence of increased central venous pressure on baroreflex control of sympathetic activity in humans. Am J Physiol Heart Circ Physiol...Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia Victor A. Convertino, PhD, William H...reduction of SV and change in MSNA during graded central hypovolemia in humans. Methods: After a 12-minute baseline data collection period, 13 men were

  9. 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.

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

    PubMed

    Coronado, Christian J R; Carvalho, João A; 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.

  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. Process investigations of extreme thermophilic fermentations for hydrogen production: effect of bubble induction and reduced pressure.

    PubMed

    Sonnleitner, Andrea; Peintner, Christian; Wukovits, Walter; Friedl, Anton; Schnitzhofer, Wolfgang

    2012-08-01

    Hydrogen production via thermophilic dark fermentation is considered a sustainable way to produce renewable hydrogen. For industrial scale an optimisation of hydrogen production is of highest importance. The aim of this work was to evaluate induced bubble formation and applying reduced pressure as methods of removing produced hydrogen instead of external gas stripping. Evaluation was carried out in a continuously stirred tank reactor using the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus. The addition of a bubble formation inductor was able to maintain the fermentation, but only at low hydrogen production rates and yields. Applying reduced pressure at a level of 305 mbar, nitrogen stripping could be omitted and hydrogen yields of around 72% of the theoretical maximum were achieved. It was proven, that application of reduced pressure is a promising alternative to inert gas stripping to obtain high hydrogen productivities and yields for thermophilic dark fermentations.

  13. Numerical acoustic characteristics and optimum design of the pressure reducing valve

    NASA Astrophysics Data System (ADS)

    Guo, P. C.; Sun, L. G.; Sun, S. H.; Feng, J. J.; Wu, K. G.; Luo, X. Q.

    2016-11-01

    The pressure reducing valves are widely used in the technological water supplied ways of gravity flow. A credible pressure reducing valve can provide stable cooling water for units with extremely low maintenance cost and labor intensity in a fairly long period of time. In this paper, a three-dimensional numerical simulation of flow field and acoustic characteristics towards a combined type pressure reducing valve was carried out based on ANSYS Fluent and the FW-H equation. The numerical results achieve the regulation of noise generation, transmission and attenuation. It shows that the sound pressure level of monitoring points seem to be higher and large gradient at low frequencies under the same flow velocity, while it presents reverse results with the increment of frequency and maintains a constant valve finally. At the same time, the monitoring points in the vicinity of throttling cone shows higher sound pressure level and upstream noise is lower than downstream's. Aiming at the problem of valve noise, a modified measure to reduce the flow-induced noise was proposed.

  14. Improving Vastus Medialis Obliquus Function Reduces Pressure Applied to Lateral Patellofemoral Cartilage

    PubMed Central

    Elias, John J.; Kilambi, Srianjana; Goerke, Derek R.; Cosgarea, Andrew J.

    2009-01-01

    The current study was performed to characterize how improving vastus medialis obliquus (VMO) function influences the pressure applied to patellofemoral cartilage. An additional focus was characterizing how lateral and medial cartilage lesions influence cartilage pressures. Ten knees were flexed to 40°, 60° and 80° in vitro, and forces were applied to represent the VMO and other muscles of the quadriceps group while a thin film sensor measured joint pressures. The knees were loaded with a normal VMO force, with the VMO force decreased by approximately 50%, and with the VMO unloaded. After tests were performed with the cartilage intact, all tests were repeated with a 12 mm diameter lesion created within the lateral cartilage, with the lateral lesion repaired with silicone, and with a medial lesion created. Based on a two-way repeated measures ANOVA and post-hoc tests, increasing the force applied by the VMO significantly (p < 0.05) decreased the maximum lateral pressure and significantly increased the maximum medial pressure at each flexion angle. A lateral cartilage lesion significantly increased the maximum lateral pressure, while a medial lesion did not significantly influence the maximum medial pressure. Improving VMO function can reduce the pressure applied to lateral cartilage when lateral lesions are present. PMID:18985700

  15. Reduced effect of percutaneous renal denervation on blood pressure in patients with isolated systolic hypertension.

    PubMed

    Ewen, Sebastian; Ukena, Christian; Linz, Dominik; Kindermann, Ingrid; Cremers, Bodo; Laufs, Ulrich; Wagenpfeil, Stefan; Schmieder, Roland E; Böhm, Michael; Mahfoud, Felix

    2015-01-01

    Renal denervation can reduce blood pressure in certain patients with resistant hypertension. The effect in patients with isolated systolic hypertension (ISH, ≥140/<90 mm Hg) is unknown. This study investigated the effects of renal denervation in 126 patients divided into 63 patients with ISH and 63 patients with combined hypertension (CH, ≥140/≥90 mm Hg) defined as baseline office systolic blood pressure (SBP) ≥140 mm Hg despite treatment with ≥3 antihypertensive agents. Renal denervation significantly reduced office SBP and diastolic blood pressure (DBP) at 3, 6, and 12 months by 17/18/17 and 5/4/4 mm Hg in ISH and by 28/27/30 and 13/16/18 mm Hg in CH, respectively. The reduction in SBP and DBP in ISH was lower compared with patients with CH at all observed time points (P<0.05 for SBP/DBP intergroup comparison). The nonresponder rate (change in office SBP <10 mm Hg) after 6 months was 37% in ISH and 21% in CH (P<0.001). Mean 24-hour ambulatory SBP and DBP after 3, 6, and 12 months were significantly reduced by 10/13/15 and 6/6/9 mm Hg in CH, respectively. In patients with ISH the reduction in systolic ambulatory blood pressure was 4/8/7 mm Hg (P=0.032/P<0.001/P=0.009) and 3/4/2 mm Hg (P=0.08/P<0.001/P=0.130) in diastolic ambulatory blood pressure after 3, 6, and 12 months, respectively. The ambulatory blood pressure reduction was significantly lower after 3 and 12 months in SBP and after 12 months in ambulatory DBP, respectively. In conclusion, renal denervation reduces office and ambulatory blood pressure in patients with ISH. However, this reduction is less pronounced compared with patients with CH.

  16. 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

  17. Chlorthalidone Plus Amiloride Reduces the Central Systolic Blood Pressure in Stage 1 Hypertension Patients

    PubMed Central

    Fernandes, Leticia Aparecida Barufi; Cestario, Elizabeth do Espirito Santo; Cosenso-Martin, Luciana Neves; Vilela-Martin, Jose Fernando; Yugar-Toledo, Juan Carlos; Fuchs, Flavio Danni

    2016-01-01

    Background Hypertension reduction strategies use blood pressure in the brachial artery as the primary endpoint. Individuals who achieve the target blood pressure reduction with antihypertensive treatment have residual cardiovascular risk attributed to the difference in pressure between the aorta and brachial artery. Antihypertensive treatment affects the intrinsic properties of the vascular wall and arterial stiffness markers and consequently the central pressure. Recent publications stress the importance of adequate control of the central compared to peripheral blood pressure. Related clinical implications suggest that individuals with normal peripheral but high central blood pressure should not receive antihypertensive drugs that act on the central pressure. Therefore, they are at greater cardiovascular risk. The aim of the study was to evaluate the effect of treatment with a thiazide diuretic versus losartan on the central blood pressure in stage 1 hypertensive patients. Methods Twenty-five patients were randomized to the chlorthalidone 25 mg/amiloride 5 mg group (q.d.) and 25 patients received losartan 50 mg (b.i.d). The central systolic blood pressure (CSBP) and augmentation index (AIx 75) were assessed using applanation tonometry. The paired t-test was used to compare the systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP), CSBP and AIx 75 between the thiazide and losartan groups at baseline and after 6 months of treatment. Results Significant reductions in CSBP (123.3 ± 14.2 vs. 113.4 ± 111.4, P = 0.0103) and AIx 75 (87.7 ± 9.6 vs. 83.8 ± 8.9, P = 0.0289) were observed after 6 months of drug treatment with chlorthalidone 25 mg/amiloride 5 mg (q.d.). The administration of losartan 50 mg (b.i.d) did not reduce the CSBP and there were insignificant changes in the AIx 75. Conclusions Six-month treatment of chlorthalidone/amiloride but not losartan reduces the CSBP and AIx 75 in adults with stage 1

  18. Reducing the effect of penstock pressure pulsations on hydro electric plant power system stabilizer signals

    SciTech Connect

    Nettleton, L.D.; Gurney, J.H.; Bollinger, K.E.

    1993-12-01

    A characteristic trait of Francis turbines operating at low-head is pressure pulsations that occur during certain load levels of the generator. These stem from pressure variations across the turbine due to pulsating flow in the draft-tube. This surging action of the water column is related to draft-tube geometry and flow-rate of water in the penstock. The pressure pulsations cause torque variations on the turbine and corresponding electric power pulsations. If electric power is used as a feedback signal to the Power System Stabilizer (PSS), then Mvar and terminal voltage pulsations will occur when the generator is operating in the ``rough zone``. This paper describes field test results for investigating feedforward control from the penstock, draft tube and spiral case pressure to reduce the effects of Mw pulsations on PSS output signals. This investigation involved a PSS with generator power as the feedback signal and the PSS tuned for local and inter-area damping.

  19. 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.

  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.

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

    PubMed Central

    Seo, Jung Hee; Mittal, Rajat

    2011-01-01

    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

  2. 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.

  3. A novel, intelligent, pressure-sensing colostomy plug for reducing fecal leakage.

    PubMed

    Chen, Fei; Li, Zhi-Chao; Li, Qiang; Liang, Fei-Xue; Guo, Xiong-Bo; Huang, Zong-Hai

    2015-06-01

    This study aims to describe and report the effectiveness of a novel, pressure-sensing colostomy plug for reducing fecal leakage. Nine miniature Tibetan pigs, aged 6-8 months, were given colostomies and divided into three groups (n = 3 each group). A novel pressure-sensing colostomy plug was placed in each pig and set to indicate when intestinal pressures of either 5, 10, or 15 mm Hg, respectively, were reached. When the pressure thresholds were reached, the animals' bowels were examined for the presence of stool and/or stomal leakage, and the data were recorded at weeks 1, 4, and 8 after surgery. The colostomy plug calibrated to 15 mm Hg pressure demonstrated the greatest accuracy in predicting the presence of stool in the bowels of study animals, averaging >90% sensitivity. In general, the sensitivity for predicting the presence of stool did not vary significantly over time, though there was a slight increase in accuracy in the 5 mm Hg group at later time-points. The sensitivity for predicting stool in the bowel did not change significantly over time in any of the three groups. Stomal leakage was found to be inversely proportional to the pressure-sensor setting, in that the 15 mm Hg group exhibited the greatest amount of leakage. This difference, however, was found to be significant only at week 1 postsurgery. The intelligent, pressure-sensing colostomy plug was able to accurately predict the presence of stool in the bowel and maintain continence, allowing negligible leakage.

  4. 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.

  5. Evaporation dehydrator

    SciTech Connect

    Bland, L.

    1985-08-06

    A method and apparatus for the treatment of oilfield heavy oil emulsions is provided. The method utilizes, in combination, the steps of evaporation, vapor/liquid separation, and solids settling to dehydrate, degassify and remove solids from the heavy oil emulsion and produce oil having less than 0.5% by volume basic solids and water. The apparatus comprises an insulated, horizontal, cylindrical vessel. Mounted in the upper end of the vessel chamber is an inclined, tubular member having a closed upper end and an open lower end. At its closed end, the member forms a receiving chamber. A mechanical foam breaker extends transversely across the interior of the tubular member, downstream of the chamber. A stack of angularly inclined, heated trays, arranged in zigzag fashion, are positioned beneath the tubular member, to provide an elongate flowpath. The lower end of the tubular member is positioned to feed onto the upper end of the first tray. The flowpath formed by the stack of trays terminates at a level above the bottom of the vessel, so that a quiescent settling sump is provided by the base of the vessel. The vessel includes a feed inlet opening into the receiving chamber, a vapor outlet leading from the top of said vessel, and liquid and solids outlets leading from the sump. A stream of pre-heated heavy oil emulsion is fed to the receiving chamber, wherein part of the contained water in the vapor form breaks out. The foaming stream is contained by the tubular member and is substantially disintegrated by the foam breaker. The stream then issues onto the upper end of the stack of trays and is heated as it passes as a shallow, broad layer over the trays, to gradually evaporate the remaining water from the emulsion and solids. The dehydrated solids are settled out in the sump, leaving oil containing less than 0.5% basic solids and water.

  6. 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.

  7. 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.

  8. Mice lacking angiotensin-converting enzyme have low blood pressure, renal pathology, and reduced male fertility.

    PubMed

    Esther, C R; Howard, T E; Marino, E M; Goddard, J M; Capecchi, M R; Bernstein, K E

    1996-05-01

    Mammals produce two isozymes of angiotensin-converting enzyme (ACE). Somatic ACE plays an important role in the control of blood pressure. The function of testis ACE, produced by male and germ cells, is not known. To examine the roles of these isozymes, we used targeted homologous recombination to introduce a modified ACE allele into a mouse line. Mice homozygous for this mutant allele lack both ACE isozymes and have markedly reduced blood pressures. Contrary to a previous report, we found heterozygous male mice to have normal blood pressures. Homozygous mutant mice also have severe renal disease. The renal papilla is markedly reduced, and the intrarenal arteries exhibit vascular hyperplasia associated with a perivascular inflammatory infiltrate. These animals cannot effectively concentrate urine. They also have an abnormally low urinary sodium to potassium ratio despite reduced levels of aldosterone. Homozygous mutant male mice sire significantly smaller litters than wild-type male mice; however, no defect in sperm number, morphology, or motility was detected. ACE-deficient animals demonstrate the role of this enzyme in systemic blood pressure, renal development and function, and male fertility.

  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. 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.

  12. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Influence of Oxygen Pressure on Structural and Sensing Properties of β-Ga2O3 Nanomaterial by Thermal Evaporation

    NASA Astrophysics Data System (ADS)

    Ma, Hai-Lin; Fan, Duo-Wang

    2009-11-01

    We prepare the gallium oxide (β-Ga2O3) nanomaterials from gallium and oxygen by thermal evaporation in the argon atmosphere and research their oxygen sensing under UV illumination with different oxygen pressures. X-ray diffraction reveals that the synthesized product is monoclinic gallium oxide, it is further confirmed by electron diffraction of transmission electron microscope, and its morphology through the observation using scanning electron microscope reveals that β-Ga2O3 nanobelts with a breadth less than 100 nm and length of several micrometers are synthesized under low oxygen pressure, while the nano/microbelts are synthesized under high oxygen pressure. Room-temperature oxygen sensing is tested under at 254 nm illumination and it is found that the current decreases quickly first and then slowly with oxygen pressure from low to high.

  13. 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.

  14. 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.

  15. 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...

  16. Vertical sleeve gastrectomy reduces blood pressure and hypothalamic endoplasmic reticulum stress in mice.

    PubMed

    McGavigan, Anne K; Henseler, Zachariah M; Garibay, Darline; Butler, Scott D; Jayasinghe, Sisitha; Ley, Ruth E; Davisson, Robin L; Cummings, Bethany P

    2017-03-01

    Bariatric surgery, such as vertical sleeve gastrectomy (VSG), causes remarkable improvements in cardiometabolic health, including hypertension remission. However, the mechanisms responsible remain undefined and poorly studied. Therefore, we developed and validated the first murine model of VSG that recapitulates the blood pressure-lowering effect of VSG using gold-standard radiotelemetry technology. We used this model to investigate several potential mechanisms, including body mass, brain endoplasmic reticulum (ER) stress signaling and brain inflammatory signaling, which are all critical contributors to the pathogenesis of obesity-associated hypertension. Mice fed on a high-fat diet underwent sham or VSG surgery and radiotelemeter implantation. Sham mice were fed ad libitum or were food restricted to match their body mass to VSG-operated mice to determine the role of body mass in the ability of VSG to lower blood pressure. Blood pressure was then measured in freely moving unstressed mice by radiotelemetry. VSG decreased energy intake, body mass and fat mass. Mean arterial blood pressure (MAP) was reduced in VSG-operated mice compared with both sham-operated groups. VSG-induced reductions in MAP were accompanied by a body mass-independent decrease in hypothalamic ER stress, hypothalamic inflammation and sympathetic nervous system tone. Assessment of gut microbial populations revealed VSG-induced increases in the relative abundance of Gammaproteobacteria and Enterococcus, and decreases in Adlercreutzia These results suggest that VSG reduces blood pressure, but this is only partly due to the reduction in body weight. VSG-induced reductions in blood pressure may be driven by a decrease in hypothalamic ER stress and inflammatory signaling, and shifts in gut microbial populations.

  17. Vertical sleeve gastrectomy reduces blood pressure and hypothalamic endoplasmic reticulum stress in mice

    PubMed Central

    McGavigan, Anne K.; Henseler, Zachariah M.; Garibay, Darline; Butler, Scott D.; Jayasinghe, Sisitha; Ley, Ruth E.; Davisson, Robin L.

    2017-01-01

    ABSTRACT Bariatric surgery, such as vertical sleeve gastrectomy (VSG), causes remarkable improvements in cardiometabolic health, including hypertension remission. However, the mechanisms responsible remain undefined and poorly studied. Therefore, we developed and validated the first murine model of VSG that recapitulates the blood pressure-lowering effect of VSG using gold-standard radiotelemetry technology. We used this model to investigate several potential mechanisms, including body mass, brain endoplasmic reticulum (ER) stress signaling and brain inflammatory signaling, which are all critical contributors to the pathogenesis of obesity-associated hypertension. Mice fed on a high-fat diet underwent sham or VSG surgery and radiotelemeter implantation. Sham mice were fed ad libitum or were food restricted to match their body mass to VSG-operated mice to determine the role of body mass in the ability of VSG to lower blood pressure. Blood pressure was then measured in freely moving unstressed mice by radiotelemetry. VSG decreased energy intake, body mass and fat mass. Mean arterial blood pressure (MAP) was reduced in VSG-operated mice compared with both sham-operated groups. VSG-induced reductions in MAP were accompanied by a body mass-independent decrease in hypothalamic ER stress, hypothalamic inflammation and sympathetic nervous system tone. Assessment of gut microbial populations revealed VSG-induced increases in the relative abundance of Gammaproteobacteria and Enterococcus, and decreases in Adlercreutzia. These results suggest that VSG reduces blood pressure, but this is only partly due to the reduction in body weight. VSG-induced reductions in blood pressure may be driven by a decrease in hypothalamic ER stress and inflammatory signaling, and shifts in gut microbial populations. PMID:28093508

  18. 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

    2016-09-06

    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.

  19. 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.

  20. Self-assembled and intercalated film of reduced graphene oxide for a novel vacuum pressure sensor

    NASA Astrophysics Data System (ADS)

    Ahn, Sung Il; Jung, Jura; Kim, Yongwoo; Lee, Yujin; Kim, Kukjoo; Lee, Seong Eui; Kim, Sungyun; Choi, Kyeong-Keun

    2016-12-01

    We report a new method for measuring vacuum pressures using Van der Waals (VDW) interactions between reduced graphene oxide (RGO) sheets. For this purpose, we utilized a reaction-based self-assembly process to fabricate various intercalated RGO (i-RGO) films, and monitored their electrical behavior with changing pressure and temperature. Pumping to remove gas from a vacuum chamber produced a decrease in the sheet resistance of i-RGO. With further pumping, distinctly different sheet resistance behaivors were observed depending on the measurement temperature. With increasing vacuum pressure, the resistance increased at 100 °C, whereas it decreased at 30 °C. Two types of VDW interactions are proposed to explain these features: a local VDW interaction between RGO sheets that resulted in V-shaped curves of sheet resistance with pressure changes and broad VDW interactions that occur between RGO sheets when the elastic force required to bend carbon clusters on an RGO sheet exceeds their vibrational energy at low temperatures. On the basis of the results, we propose that the resistance behavior of i-RGO as a function of vacuum pressure can be interpreted as the sum of the two different VDW interactions.

  1. Self-assembled and intercalated film of reduced graphene oxide for a novel vacuum pressure sensor

    PubMed Central

    Ahn, Sung Il; Jung, Jura; Kim, Yongwoo; Lee, Yujin; Kim, Kukjoo; Lee, Seong Eui; Kim, Sungyun; Choi, Kyeong-Keun

    2016-01-01

    We report a new method for measuring vacuum pressures using Van der Waals (VDW) interactions between reduced graphene oxide (RGO) sheets. For this purpose, we utilized a reaction-based self-assembly process to fabricate various intercalated RGO (i-RGO) films, and monitored their electrical behavior with changing pressure and temperature. Pumping to remove gas from a vacuum chamber produced a decrease in the sheet resistance of i-RGO. With further pumping, distinctly different sheet resistance behaivors were observed depending on the measurement temperature. With increasing vacuum pressure, the resistance increased at 100 °C, whereas it decreased at 30 °C. Two types of VDW interactions are proposed to explain these features: a local VDW interaction between RGO sheets that resulted in V-shaped curves of sheet resistance with pressure changes and broad VDW interactions that occur between RGO sheets when the elastic force required to bend carbon clusters on an RGO sheet exceeds their vibrational energy at low temperatures. On the basis of the results, we propose that the resistance behavior of i-RGO as a function of vacuum pressure can be interpreted as the sum of the two different VDW interactions. PMID:27976686

  2. Self-assembled and intercalated film of reduced graphene oxide for a novel vacuum pressure sensor.

    PubMed

    Ahn, Sung Il; Jung, Jura; Kim, Yongwoo; Lee, Yujin; Kim, Kukjoo; Lee, Seong Eui; Kim, Sungyun; Choi, Kyeong-Keun

    2016-12-15

    We report a new method for measuring vacuum pressures using Van der Waals (VDW) interactions between reduced graphene oxide (RGO) sheets. For this purpose, we utilized a reaction-based self-assembly process to fabricate various intercalated RGO (i-RGO) films, and monitored their electrical behavior with changing pressure and temperature. Pumping to remove gas from a vacuum chamber produced a decrease in the sheet resistance of i-RGO. With further pumping, distinctly different sheet resistance behaivors were observed depending on the measurement temperature. With increasing vacuum pressure, the resistance increased at 100 °C, whereas it decreased at 30 °C. Two types of VDW interactions are proposed to explain these features: a local VDW interaction between RGO sheets that resulted in V-shaped curves of sheet resistance with pressure changes and broad VDW interactions that occur between RGO sheets when the elastic force required to bend carbon clusters on an RGO sheet exceeds their vibrational energy at low temperatures. On the basis of the results, we propose that the resistance behavior of i-RGO as a function of vacuum pressure can be interpreted as the sum of the two different VDW interactions.

  3. 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.

  4. 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.

  5. 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

  6. Acute Treatment with Lauric Acid Reduces Blood Pressure and Oxidative Stress in Spontaneously Hypertensive Rats.

    PubMed

    Alves, Naiane Ferraz Bandeira; de Queiroz, Thyago Moreira; de Almeida Travassos, Rafael; Magnani, Marciane; de Andrade Braga, Valdir

    2017-04-01

    The effects of acute administration of lauric acid (LA), the most abundant medium-chain fatty acid of coconut oil, on blood pressure, heart rate and oxidative stress were investigated in spontaneously hypertensive rats (SHR). Intravenous doses of LA reduced blood pressure in a dose-dependent fashion (1, 3, 4, 8 and 10 mg/kg) in both SHR and Wistar Kyoto rats. LA (10(-8) to 3 × 10(-3) M) induced vasorelaxation in isolated superior mesenteric artery rings of SHR in the presence (n = 7) or absence (n = 8) of functional endothelium [maximum effect (ME) = 104 ± 3 versus 103 ± 4%]. After exposure to KCl (60 mM), LA also induced concentration-dependent vasorelaxation (n = 7) compared to that under Phe-induced contraction (ME = 113.5 + 5.1 versus 104.5 + 4.0%). Furthermore, LA-induced vasorelaxation in vessels contracted with S(-)-BayK8644 (200 nM), a L-type Ca(2+) channel agonist (ME = 91.4 + 4.3 versus 104.5 + 4.0%, n = 7). Lastly, LA (10(-3) M) reduced NADPH-dependent superoxide accumulation in the heart (18 ± 1 versus 25 ± 1 MLU/min/μg protein, n = 4, p < 0.05) and kidney (82 ± 3 versus 99 ± 4 MLU/min/μg protein, n = 4, p < 0.05). Our data show that LA reduces blood pressure in normotensive and hypertensive rats. In SHR, this effect might involve Ca(+2) channels in the resistance vessels and by its capability of reducing oxidative stress in heart and kidneys.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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

  13. Glycyrrhizic Acid Reduces Heart Rate and Blood Pressure by a Dual Mechanism.

    PubMed

    Singh, Kailash; Zaw, Aung Moe; Sekar, Revathi; Palak, Ahuja; Allam, Ahmed A; Ajarem, Jamaan; Chow, Billy K C

    2016-09-27

    Beta adrenergic receptors are crucial for their role in rhythmic contraction of heart along with their role in the pathological conditions such as tachycardia and high risk of heart failure. Studies report that the levels of beta-1 adrenergic receptor tend to decrease by 50%, whereas, the levels of beta-2 adrenergic receptor remains constant during the risk of heart failure. Beta blockers-the antagonistic molecules for beta-adrenergic receptors, function by slowing the heart rate, which thereby allows the left ventricle to fill completely during tachycardia incidents and hence helps in blood pumping capacity of heart and reducing the risk of heart failure. In the present study, we investigate the potential of glycyrrhizic acid (GA) as a possible principal drug molecule for cardiac arrhythmias owing to its ability to induce reduction in the heart rate and blood pressure. We use in vitro and in silico approach to study GA's effect on beta adrenergic receptor along with an in vivo study to examine its effect on heart rate and blood pressure. Additionally, we explore GA's proficiency in eliciting an increase in the plasma levels of vasoactive intestinal peptide, which by dilating the blood vessel consequently, can be a crucial aid during the occurrence of a potential heart attack. Therefore, we propose GA as a potential principal drug molecule via its potential in modulating heart rate and blood pressure.

  14. Ethylene: Response of Fruit Dehiscence to CO2 and Reduced Pressure 1

    PubMed Central

    Lipe, John A.; Morgan, Page W.

    1972-01-01

    These studies were conducted to determine whether ethylene serves as a natural regulator of fruit wall dehiscence, a major visible feature of ripening in some fruits. We employed treatments to inhibit ethylene action or remove ethylene and observed their effect on fruit dehiscence. CO2 (13%), a competitive inhibitor of ethylene action in many systems, readily delayed dehiscence of detached fruits of cotton (Gossypium hirsutum L.), pecan (Carya illinoensis [Wang.] K. Koch), and okra (Hibiscus esculentus L.). The CO2 effect was duplicated by placing fruits under reduced pressure (200 millimeters mercury), to promote the escape of ethylene from the tissue. Dehiscence of detached fruits of these species as well as attached cotton fruits was delayed. The delay of dehiscence of cotton and okra by both treatments was achieved with fruit harvested at intervals from shortly after anthesis until shortly before natural dehiscence. Pecan fruits would not dehisce until approximately 1 month before natural dehiscence, and during that time, CO2 and reduced pressure delayed dehiscence. CO2 and ethylene were competitive in their effects on cotton fruit dehiscence. All of the results are compatible with a hypothetical role of ethylene as a natural regulator of dehiscence, a dominant aspect of ripening of cotton, pecan, and some other fruits. PMID:16658260

  15. Ethylene: Response of Fruit Dehiscence to CO(2) and Reduced Pressure.

    PubMed

    Lipe, J A; Morgan, P W

    1972-12-01

    These studies were conducted to determine whether ethylene serves as a natural regulator of fruit wall dehiscence, a major visible feature of ripening in some fruits. We employed treatments to inhibit ethylene action or remove ethylene and observed their effect on fruit dehiscence. CO(2) (13%), a competitive inhibitor of ethylene action in many systems, readily delayed dehiscence of detached fruits of cotton (Gossypium hirsutum L.), pecan (Carya illinoensis [Wang.] K. Koch), and okra (Hibiscus esculentus L.). The CO(2) effect was duplicated by placing fruits under reduced pressure (200 millimeters mercury), to promote the escape of ethylene from the tissue. Dehiscence of detached fruits of these species as well as attached cotton fruits was delayed. The delay of dehiscence of cotton and okra by both treatments was achieved with fruit harvested at intervals from shortly after anthesis until shortly before natural dehiscence. Pecan fruits would not dehisce until approximately 1 month before natural dehiscence, and during that time, CO(2) and reduced pressure delayed dehiscence. CO(2) and ethylene were competitive in their effects on cotton fruit dehiscence. All of the results are compatible with a hypothetical role of ethylene as a natural regulator of dehiscence, a dominant aspect of ripening of cotton, pecan, and some other fruits.

  16. 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.

  17. 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

  18. Experimental investigation of interfacial phenomena in evaporating sessile droplets for evaporative cooling applications

    NASA Astrophysics Data System (ADS)

    MacDonald, Brendan; Mahmud, Md. Almostasim

    2016-11-01

    Evaporation of sessile droplets has applications in many fields, including evaporative cooling technology. An example from nature is human perspiration. Evaporative cooling applications typically operate at atmospheric pressure and 20 to 80°C, and systems that mimic perspiration require droplets that are continuously fed fluid. A number of studies have investigated phenomena associated with evaporating sessile droplets including (1) interfacial energy transport, (2) distribution of the evaporation flux along the interface, and (3) temperature discontinuities at the liquid-vapor interface; however, many of these studies were not undertaken in the regime relevant to evaporative cooling and used low pressures and temperatures or droplets that were not continuously fed fluid and changed shape as they were depleted. We will present the results from our experimental study, which examined these phenomena in the regime relevant to evaporative cooling to determine if they are present and if they have an impact on the evaporation behavior. In this regime we found that conduction provided a majority of the energy required for evaporation, the local evaporation flux changed depending on thermocapillary convection, and interfacial temperature discontinuities were present.

  19. 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

  20. 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

  1. 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

  2. Tear film dynamics with evaporation and osmolarity

    NASA Astrophysics Data System (ADS)

    Siddique, Javed; Braun, Richard

    2011-11-01

    We consider a model problem for the evaporation and breakup up of tear film. The model includes the effects of surface tension, Marangoni stresses, insoluble surfactant transport, evaporation, osmolarity transport, osmosis and wetting of corneal surface. Evaporation is made dependent on surface concentration in order to mimic the lipid layer of the tear film when there is a single fluid layer in the model. In many cases for a single layer, the Marangoni effect seems to eliminate a localized area of increased evaporation due to reduced surfactant concentration. In this model the osmolarity in the tear film increases because of average evaporation rate rather than by a locally increased evaporation rate. If time permits, the effect of having a second fluid layer, representing the lipid layer, will be explored as well.

  3. 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.

  4. Gastrodin Reduces Blood Pressure by Intervening with RAAS and PPARγ in SHRs

    PubMed Central

    Liu, Wei; Wang, Lingyan; Yu, Jiahui; Asare, Patrick Fordjour; Zhao, Ying-Qiang

    2015-01-01

    Gastrodin is a bioactive compound extracted from traditional Chinese medicine, Gastrodia elata  Bl. It has a definite effect on reducing blood pressure in hypertensive patients. However, the mechanisms of gastrodin in lowering blood pressure still remain unclear. In this study, 4 weeks of administration of gastrodin (100 mg/kg/d intraperitoneally injected) decreased the systolic blood pressure (SBP) in spontaneously hypertensive rats (SHRs) (190.2 ± 8.9 versus 169.8 ± 6.4, P < 0.01). Among SHRs receiving gastrodin treatment, angiotensin II (Ang II) and aldosterone (ALD) in serum were significantly decreased (2022.1 ± 53.0 versus 1528.7 ± 93.9, 213.33 ± 35.17 versus 179.65 ± 20.31, and P < 0.01, P < 0.05, resp.) and dramatically downregulated expression of angiotensin type 1 receptor (AT1R) (4.9 ± 0.9 versus 2.6 ± 0.9, P < 0.05) in myocardium in both mRNA and protein levels compared with their corresponding groups without gastrodin treatment. Additionally, gastrodin increased the mRNA expression (0.18 ± 0.07 versus 0.82 ± 0.10, P < 0.01) and protein synthesis (0.40 ± 0.10 versus 0.34 ± 0.10, P < 0.01) of peroxisome proliferator-activated receptor γ (PPARγ) in myocardium tissues. Overall, our data demonstrated that gastrodin was able to decrease the SBP in SHR. Furthermore, this study showed that gastrodin intervened with the renin-angiotensin-aldosterone system (RAAS) and PPARγ effectively, which indicates its antihypertensive mechanism. PMID:26587048

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

    PubMed

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

    2015-07-01

    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.

  6. 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.

  7. A method for reducing pressure-induced deformation in silicone microfluidics

    PubMed Central

    Inglis, David W.

    2010-01-01

    Poly(dimethylsiloxane) or PDMS is an excellent material for replica molding, widely used in microfluidics research. Its low elastic modulus, or high deformability, assists its release from challenging molds, such as those with high feature density, high aspect ratios, and even negative sidewalls. However, owing to the same properties, PDMS-based microfluidic devices stretch and change shape when fluid is pushed or pulled through them. This paper shows how severe this change can be and gives a simple method for limiting this change that sacrifices few of the desirable characteristics of PDMS. A thin layer of PDMS between two rigid glass substrates is shown to drastically reduce pressure-induced shape changes while preserving deformability during mold separation and gas permeability. PMID:20697573

  8. Latent fingermark visualisation using reduced-pressure sublimation of copper phthalocyanine.

    PubMed

    Williams, Geraint; ap Llwyd Dafydd, Hefin; Watts, Alun; McMurray, Neil

    2011-01-30

    The sublimation of copper phthalocyanine (CuPc) at a temperature of 400°C under conditions of reduced pressure is shown to be an effective method of developing latent fingermarks on certain types of surface. Preliminary experiments on a limited selection of surfaces including paper, plastic and ceramic tiles were carried out using a simple apparatus consisting of a vacuum desiccator and a resistive heater. CuPc from the gas phase condenses preferentially on fingermark deposits, revealing deep blue patterns with excellent ridge detail clarity on light coloured surfaces. The technique is shown to be most effective on porous surfaces such as paper, but relatively ineffective on non-porous ceramic and plastic surfaces.

  9. 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.

  10. The abbreviated impactor measurement (AIM) concept: part II--Influence of evaporation of a volatile component-evaluation with a "droplet-producing" pressurized metered dose inhaler (pMDI)-based formulation containing ethanol as cosolvent.

    PubMed

    Mitchell, J P; Nagel, M W; Avvakoumova, V; MacKay, H; Ali, R

    2009-01-01

    The abbreviated impactor measurement (AIM) concept is a potential solution to the labor-intensive full-resolution cascade impactor (CI) methodology for inhaler aerosol aerodynamic particle size measurement. In this validation study, the effect of increasing the internal dead volume on determined mass fractions relating to aerodynamic particle size was explored with two abbreviated impactors both based on the Andersen nonviable cascade impactor (ACI) operating principle (Copley fast screening Andersen impactor [C-FSA] and Trudell fast screening Andersen impactor [T-FSA]). A pressurized metered dose inhaler-delivered aerosol producing liquid ethanol droplets after propellant evaporation was chosen to characterize these systems. Measures of extrafine, fine, and coarse particle mass fractions from the abbreviated systems were compared with corresponding data obtained by a full-resolution ACI. The use of liquid ethanol-sensitive filter paper provided insight by rendering locations visible where partly evaporated droplets were still present when the "droplet-producing" aerosol was sampled. Extrafine particle fractions based on impactor-sized mass were near equivalent in the range 48.6% to 54%, comparing either abbreviated system with the benchmark ACI-measured data. The fine particle fraction of the impactor-sized mass determined by the T-FSA (94.4 +/- 1.7%) was greater than using the C-FSA (90.5 +/- 1.4%) and almost identical with the ACI-measured value (95.3 +/- 0.4%). The improved agreement between T-FSA and ACI is likely the result of increasing the dead space between the entry to the induction port and the uppermost impaction stage, compared with that for the C-FSA. This dead space is needed to provide comparable conditions for ethanol evaporation in the uppermost parts of these impactors.

  11. 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.

  12. Water evaporation on highly viscoelastic polymer surfaces.

    PubMed

    Pu, Gang; Severtson, Steven J

    2012-07-03

    Results are reported for a study on the evaporation of water droplets from a highly viscoelastic acrylic polymer surface. These are contrasted with those collected for the same measurements carried out on polydimethylsiloxane (PDMS). For PDMS, the evaporation process involves the expected multistep process including constant drop area, constant contact angle, and finally a combination of these steps until the liquid is gone. In contrast, water evaporation from the acrylic polymer shows a constant drop area mode throughout. Furthermore, during the evaporation process, the drop area actually expands on the acrylic polymer. The single mode evaporation process is consistent with formation of wetting structures, which cannot be propagated by the capillary forces. Expansion of the drop area is attributed to the influence of the drop capillary pressure. Furthermore, the rate of drop area expansion is shown to be dependent on the thickness of the polymer film.

  13. Modelling of multiphase flow in evaporation tests in concrete columns

    NASA Astrophysics Data System (ADS)

    Chaparro, M. Carme; Saaltink, Maarten W.; Villar, M. Victoria

    2013-04-01

    In order to characterize better the thermo-hydraulic properties and processes in concrete from a Radioactive Waste Disposal Facility at El Cabril (Spain), evaporation tests in columns have been analysed by means of numerical models. The tests consisted of letting water evaporate from the top of the column while monitoring water loss by weighing the column, and monitoring temperature and relative humidity by means of sensors placed within the column. Both non-isothermal (by heating the column with a lamp) and isothermal tests (without heating) were performed. The conceptual model considers unsaturated liquid flow and transport of vapour and heat. Some models also take into account the salinity in order to study its effect on vapour pressure and evaporation. A retention curve has been obtained from relative humidity and gravimetric water content measured after dismantling the columns. The models have been calibrated by fitting permeability and a tortuosity factor for vapour diffusion to the measured water loss, relative humidity and (in the case of the non-isothermal test) temperature. Results show that vapour diffusion is dominant above an evaporation front, and liquid advection is the dominant water transport process underneath this front. The salinity slightly reduces the evaporation with a factor of at most 5%. The tortuosity factor estimated from the isothermal test is lower than that of the non-isothermal test. This can be explained by the evaporation and condensation together with the heat transport that take place at pore scale under non-isothermal conditions, which are not taken into account by the model.

  14. Correlation for Sessile Drop Evaporation

    NASA Astrophysics Data System (ADS)

    Kelly-Zion, Peter; Pursell, Christopher; Wassom, Gregory; Mandelkorn, Brenton; Nkinthorn, Chris

    2016-11-01

    To better understand how the evaporation of sessile drops and small puddles is controlled by the vapor phase transport mechanisms of mass diffusion and buoyancy-induced convection, the evaporation rates of eight liquids evaporating under a broad range of ambient conditions were correlated with physical and geometrical properties. Examination of the correlation provides valuable insight into how the roles of diffusive and convective transport change with physical and geometrical parameters. The correlation predicts measured evaporation rates to within a root-mean-square error of 7.3%. The correlation is composed of two terms, a term which provides the rate of evaporation under diffusion-only conditions, and a term which provides the influence of convection. This second term suggests the manner in which the processes of diffusion and convection are coupled. Both processes are dependent on the distribution of the vapor, through the molar concentration gradient for diffusion and through the mass density gradient for convection. The term representing the influence of convection is approximately inversely proportional to the square root of diffusivity, indicating the tendency of diffusive transport to reduce convection by making the vapor distribution more uniform. Financial support was provided by the ACS Petroleum Research Fund.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Simulation and optimization of pressure swing adsorption systmes using reduced-order modeling

    SciTech Connect

    Agarwal, A.; Biegler, L.; Zitney, S.

    2009-01-01

    Over the past three decades, pressure swing adsorption (PSA) processes have been widely used as energyefficient gas separation techniques, especially for high purity hydrogen purification from refinery gases. Models for PSA processes are multiple instances of partial differential equations (PDEs) in time and space with periodic boundary conditions that link the processing steps together. The solution of this coupled stiff PDE system is governed by steep fronts moving with time. As a result, the optimization of such systems represents a significant computational challenge to current differential algebraic equation (DAE) optimization techniques and nonlinear programming algorithms. Model reduction is one approach to generate cost-efficient low-order models which can be used as surrogate models in the optimization problems. This study develops a reducedorder model (ROM) based on proper orthogonal decomposition (POD), which is a low-dimensional approximation to a dynamic PDE-based model. The proposed method leads to a DAE system of significantly lower order, thus replacing the one obtained from spatial discretization and making the optimization problem computationally efficient. The method has been applied to the dynamic coupled PDE-based model of a twobed four-step PSA process for separation of hydrogen from methane. Separate ROMs have been developed for each operating step with different POD modes for each of them. A significant reduction in the order of the number of states has been achieved. The reduced-order model has been successfully used to maximize hydrogen recovery by manipulating operating pressures, step times and feed and regeneration velocities, while meeting product purity and tight bounds on these parameters. Current results indicate the proposed ROM methodology as a promising surrogate modeling technique for cost-effective optimization purposes.

  20. Proposal and design of a natural gas liquefaction process recovering the energy obtained from the pressure reducing stations of high-pressure pipelines

    NASA Astrophysics Data System (ADS)

    Tan, Hongbo; Zhao, Qingxuan; Sun, Nannan; Li, Yanzhong

    2016-12-01

    Taking advantage of the refrigerating effect in the expansion at an appropriate temperature, a fraction of high-pressure natural gas transported by pipelines could be liquefied in a city gate station through a well-organized pressure reducing process without consuming any extra energy. The authors proposed such a new process, which mainly consists of a turbo-expander driven booster, throttle valves, multi-stream heat exchangers and separators, to yield liquefied natural gas (LNG) and liquid light hydrocarbons (LLHs) utilizing the high-pressure of the pipelines. Based on the assessment of the effects of several key parameters on the system performance by a steady-state simulation in Aspen HYSYS, an optimal design condition of the proposed process was determined. The results showed that the new process is more appropriate to be applied in a pressure reducing station (PRS) for the pipelines with higher pressure. For the feed gas at the pressure of 10 MPa, the maximum total liquefaction rate (ytot) of 15.4% and the maximum exergy utilizing rate (EUR) of 21.7% could be reached at the optimal condition. The present process could be used as a small-scale natural gas liquefying and peak-shaving plant at a city gate station.

  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. Doppler estimation of reduced coronary flow reserve in mice with pressure overload cardiac hypertrophy

    PubMed Central

    Hartley, Craig J.; Reddy, Anilkumar K.; Madala, Sridhar; Michael, Lloyd H.; Entman, Mark L.; Taffet, George E.

    2008-01-01

    Aortic banding produces pressure overload cardiac hypertrophy in mice leading to decompensated heart failure in 4–8 wks, but the effects on coronary blood flow velocity and reserve are unknown. To determine whether coronary flow reserve (CFR) was reduced, we used noninvasive 20 MHz Doppler ultrasound to measure left main coronary flow velocity at baseline (B) and at hyperemia (H) induced by low (1%) and high (2.5%) concentrations of isoflurane gas anesthesia. Ten mice were studied before (Pre) and at 1d, 7d, 14d, and 21d after constricting the aortic arch to 0.4 mm diameter distal to the innominate artery. We also measured cardiac inflow and outflow velocities at the mitral and aortic valves and velocity at the jet distal to the aortic constriction. The pressure drop as estimated by 4V2 at the jet was 51 ± 5.1 (mean ± SE) mmHg at 1d increasing progressively to 74 ± 5.2 mmHg at 21d. Aortic and mitral blood velocities were not significantly different after banding (p = NS), but CFR, as estimated by H/B, dropped progressively from 3.2 ± 0.3 before banding to 2.2 ± 0.4, 1.7 ± 0.3, 1.4 ± 0.2, and 1.1 ± 0.1 at 1d, 7d, 14d, and 21d respectively (all P < 0.01 vs Pre). There was also a significant and progressive increase the systolic/diastolic velocity ratio (0.17 Pre to 0.92 at 21d, all P < 0.01 vs Pre) suggesting a redistribution of perfusion from subendocardium to subepicardium. We show for the first time that CFR, as estimated by the hyperemic response to isoflurane and measured by Doppler ultrasound, can be measured serially in mice and conclude that CFR is virtually eliminated in banded mice after 21 days of remodeling and hypertrophy. These results demonstrate that CFR is reduced in mice as in humans with cardiac disease but before the onset of decompensated heart failure. PMID:18255218

  3. Evaporation From Lake Superior

    NASA Astrophysics Data System (ADS)

    Spence, C.; Blanken, P.; Hedstrom, N.; Leshkevich, G.; Fortin, V.; Charpentier, D.; Haywood, H.

    2009-05-01

    Evaporation is a critical component of the water balance of each of the Laurentian Great Lakes, and understanding the magnitude and physical controls of evaporative water losses are important for several reasons. Recently, low water levels in Lakes Superior and Michigan/Huron have had socioeconomic, ecological, and even meteorological impacts (e.g. water quality and quantity, transportation, invasive species, recreation, etc.). The recent low water levels may be due to increased evaporation, but this is not known as operational evaporation estimates are currently calculated as the residual of water or heat budgets. Perhaps surprisingly, almost nothing is known about evaporation dynamics from Lake Superior and few direct measurements of evaporation have been made from any of the Laurentian Great Lakes. This research is the first to attempt to directly measure evaporation from Lake Superior by deploying eddy covariance instrumentation. Results of evaporation rates, their patterns and controlling mechanisms will be presented. The direct measurements of evaporation are used with concurrent satellite and climate model data to extrapolate evaporation measurements across the entire lake. This knowledge could improve predictions of how climate change may impact the lake's water budget and subsequently how the water in the lake is managed.

  4. 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.

  5. 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.

  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. Experimental results on evaporation waves

    NASA Astrophysics Data System (ADS)

    Grana Otero, Jose; Parra Fabian, Ignacio

    2010-11-01

    A liquid contained in a vertical glass tube is suddenly depressurized from a high initial pressure down to one for which the stable state is vapour, so vaporization sets off at the free surface. For large enough evaporation rates, the planar vapour-liquid interface is Darrieus-Landau unstable [1], leading to the interface surface rippling close to the instability threshold. Further increasing the initial to final pressure ratio brings about evaporation waves [2,3], in which a highly corrugated front propagates downwards into the liquid. A new experimental method is presented as well as some experimental results obtained by tracking the evolution of the front with a high speed camera. In addition, a number of new phenomena related to the dynamics of bubbles growth at the walls has been uncovered. In particular, a new mode of propagation of the evaporation front is found. In this mode the front originates from below the interface, so the propagation is upwards against gravity with a curved but smooth front.[4pt] [1] F. J. Higuera, Phys. Fluids, V. 30, 679 (1987).[0pt] [2] J.E.Shepherd and B.Sturtevant, J.Fluid Mech., V.121,379 (1982).[0pt] [3] P.Reinke and G.Yadigaroglu, Int.J.Multiph. Flow, V.27,1487 (2001).

  8. 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

  9. Vitamin D therapy to reduce blood pressure and left ventricular hypertrophy in resistant hypertension: randomized, controlled trial.

    PubMed

    Witham, Miles D; Ireland, Sheila; Houston, J Graeme; Gandy, Stephen J; Waugh, Shelley; Macdonald, Thomas M; Mackenzie, Isla S; Struthers, Allan D

    2014-04-01

    Low 25-hydroxyvitamin D levels are associated with higher prevalent blood pressure. We tested whether high-dose intermittent oral vitamin D therapy could reduce blood pressure and left ventricular mass in patients with hypertension resistant to conventional treatment. We conducted a parallel-group, double-blind, randomized placebo-controlled trial. Patients with supine office blood pressure >140/90 mm Hg on ≥3 antihypertensive agents received 100 000 U oral vitamin D3 or matching placebo every 2 months. Office and 24-hour ambulatory blood pressure, glucose, and cholesterol were measured at baseline, 2, 4, and 6 months; left ventricular mass index was measured by cardiac MRI on a subgroup at baseline and 6 months. The primary outcome was mean 24-hour ambulatory blood pressure at 6 months. A total of 68 participants were randomized, 34 in each group. Mean age was 63 (SD 11) years, mean baseline office blood pressure was 154/84 (13/10) mm Hg, and mean baseline 25-hydroxyvitamin D level was 42 (16) nmol/L. Treatment with vitamin D did not reduce 24-hour ambulatory blood pressure (adjusted treatment effects: systolic, +3 mm Hg; 95% confidence interval, -4 to +11; P=0.33; diastolic, -2 mm Hg; 95% confidence interval, -6 to +2; P=0.29); similar results were seen for office blood pressure. Left ventricular mass index was measured in a subgroup (n=25); no reduction was seen with vitamin D treatment (adjusted treatment effect, +4 g/m(2); 95% confidence interval, 0 to +7; P=0.04). There was no significant change in cholesterol or glucose levels. Thus, 6 months of intermittent, high-dose oral vitamin D3 did not reduce blood pressure or left ventricular mass in patients with resistant hypertension.

  10. Silver Dressings Augment the Ability of Negative Pressure Wound Therapy to Reduce Bacteria in a Contaminated Open Fracture Model

    DTIC Science & Technology

    2011-07-01

    ORIGINAL ARTICLE Silver Dressings Augment the Ability of Negative Pressure Wound Therapy to Reduce Bacteria in a Contaminated Open Fracture Model...contaminated by S. aureus. Key Words: Contamination, Infection, Open fracture , Negative pressure, Silver dressing. (J Trauma. 2011;71: S147–S150...is commonly used in the treatment of large wounds and acute open fractures , and has even been applied to surgical incisions in an effort to minimize

  11. Blood pressure reduction does not reduce perihematoma oxygenation: a CT perfusion study.

    PubMed

    Kate, Mahesh P; Hansen, Mikkel B; Mouridsen, Kim; Østergaard, Leif; Choi, Victor; Gould, Bronwen E; McCourt, Rebecca; Hill, Michael D; Demchuk, Andrew M; Coutts, Shelagh B; Dowlatshahi, Dariush; Emery, Derek J; Buck, Brian H; Butcher, Kenneth S

    2014-01-01

    Blood pressure (BP) reduction after intracerebral hemorrhage (ICH) is controversial, because of concerns that this may cause critical reductions in perihematoma perfusion and thereby precipitate tissue damage. We tested the hypothesis that BP reduction reduces perihematoma tissue oxygenation.Acute ICH patients were randomized to a systolic BP target of <150 or <180 mm Hg. Patients underwent CT perfusion (CTP) imaging 2 hours after randomization. Maps of cerebral blood flow (CBF), maximum oxygen extraction fraction (OEF(max)), and the resulting maximum cerebral metabolic rate of oxygen (CMRO2(max)) permitted by local hemodynamics, were calculated from raw CTP data.Sixty-five patients (median (interquartile range) age 70 (20)) were imaged at a median (interquartile range) time from onset to CTP of 9.8 (13.6) hours. Mean OEF(max) was elevated in the perihematoma region (0.44±0.12) relative to contralateral tissue (0.36±0.11; P<0.001). Perihematoma CMRO2(max) (3.40±1.67 mL/100 g per minute) was slightly lower relative to contralateral tissue (3.63±1.66 mL/100 g per minute; P=0.025). Despite a significant difference in systolic BP between the aggressive (140.5±18.7 mm Hg) and conservative (163.0±10.6 mm Hg; P<0.001) treatment groups, perihematoma CBF was unaffected (37.2±11.9 versus 35.8±9.6 mL/100 g per minute; P=0.307). Similarly, aggressive BP treatment did not affect perihematoma OEF(max) (0.43±0.12 versus 0.45±0.11; P=0.232) or CMRO2(max) (3.16±1.66 versus 3.68±1.85 mL/100 g per minute; P=0.857). Blood pressure reduction does not affect perihematoma oxygen delivery. These data support the safety of early aggressive BP treatment in ICH.

  12. Surface modification of Monel K-500 as a means of reducing friction and wear in high-pressure oxygen

    NASA Technical Reports Server (NTRS)

    Gunaji, Mohan; Stoltzfus, Joel M.; Schoenman, Leonard; Kazaroff, John

    1989-01-01

    A study is conducted of the tribological characteristics of Monel K-500 during rubbing in a high pressure oxygen atmosphere, upon surface treatment by ion-implanted oxygen, chromium, lead, and silver, as well as electrolyzed chromium and an electroless nickel/SiC composite. The electrolyzed chromium dramatically increased total sample wear, while other surface treatments affected sample wear only moderately. Although the ion-implant treatments reduced the average coefficient of friction at low contact pressure, higher contact pressures eliminated this improvement.

  13. Pharmacist-physician co-management of hypertension reduces 24-hour ambulatory blood pressures

    PubMed Central

    Weber, Cynthia A.; Ernst, Michael E.; Sezate, Genesis S.; Zheng, Shimin; Carter, Barry L.

    2010-01-01

    Background Pharmacist-physician co-management of hypertension has been shown to improve office blood pressures (BP). We sought to describe the effect of such a model on 24-hour ambulatory BPs. Methods We performed a prospective, cluster-randomised controlled clinical trial in 179 patients with uncontrolled hypertension from five primary care clinics in Iowa City, Iowa. Patients were randomized by clinic to receive pharmacist-physician collaborative management of hypertension (intervention) or usual care (control) for a 9-month period. In the intervention group, pharmacists helped patients identify barriers to BP control, counselled on lifestyle and dietary modifications, and adjusted antihypertensive therapy in collaboration with the patient’s primary care provider. Patients were seen by pharmacists a minimum every 2 months. Ambulatory BP was obtained at baseline and study end. Results Baseline and end of study ambulatory BP profiles were evaluated for 175 patients. Ambulatory BPs were reduced to a greater extent in the intervention compared to control group (daytime ΔSBP [SD] 15.2[11.5] vs 5.5[13.5], p<0.001; nighttime ΔSBP [SD] 12.2[14.8] vs 3.4[13.3], p<0.001; 24-hour ΔSBP [SD] 14.1[11.3] vs 5.5[12.5], p<0.001). More patients in the intervention group had BP controlled at the end of the study (75% vs 50.7%, p<0.001) as defined by overall 24-hour ambulatory BP monitoring. Conclusions Pharmacist-physician collaborative management of hypertension achieved consistent and significantly greater reduction in 24-hour BP and a high rate of BP control. PMID:20937921

  14. Grape polyphenols reduce blood pressure and increase flow-mediated vasodilation in men with metabolic syndrome.

    PubMed

    Barona, Jacqueline; Aristizabal, Juan C; Blesso, Christopher N; Volek, Jeff S; Fernandez, Maria Luz

    2012-09-01

    We evaluated the effects of grape polyphenols in individuals classified with metabolic syndrome (MetS). Men (n = 24) aged 30-70 y were randomly assigned to consume either a freeze-dried grape polyphenol powder (GRAPE) or a placebo for 30 d in a double-blind, crossover design, separated by a 3-wk washout period. Participants were asked to maintain their usual diet and physical activity during the study and abstain from consuming polyphenol-rich foods. MetS criteria including blood pressure (BP) and markers of vascular endothelial function including brachial artery flow-mediated vasodilation (FMD), plasma total nitrite + nitrate (NOx) to estimate NO production, plasma soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured at the end of each dietary period. Systolic BP (P < 0.0025) and plasma sICAM-1 concentrations (P < 0.025) were lower, whereas the FMD response was higher (P < 0.0001), during the GRAPE compared with the placebo period. In addition, changes in sVCAM-1 concentrations between periods were positively correlated with changes in systolic BP (r = 0.45; P < 0.05). Although NOx concentrations did not differ between periods, changes in systolic BP were negatively correlated with changes in NOx concentrations (r = -0.44; P < 0.05), indicating the vasodilating properties of NO. Other MetS variables did not differ between the GRAPE and placebo periods. These results suggest that GRAPE polyphenols may potentiate vasorelaxation and reduce BP and circulating cell adhesion molecules, resulting in improvements in vascular function.

  15. Silencing of P2Y2 receptors reduces intraocular pressure in New Zealand rabbits

    PubMed Central

    Martin-Gil, Alba; de Lara, María Jesús Perez; Crooke, Almudena; Santano, Concepción; Peral, Assumpta; Pintor, Jesus

    2012-01-01

    BACKGROUND AND PURPOSE P2 receptors are involved in the regulation of ocular physiological processes like intraocular pressure (IOP). In the present study, the involvement of P2Y2 receptors in the hypertensive effect of nucleotides was investigated by use of antagonists and of a siRNA designed for the P2Y2 receptor. EXPERIMENTAL APPROACH Agonists of the P2Y2 receptor a as well as P2 antagonists were applied to eyes of New Zealand rabbits, and the changes in IOP were followed for up to 6 h. Cloning of the P2Y2 receptor cDNA was done using a combination of degenerate reverse transcription PCR (RT-PCR) and rapid amplification of cDNA ends (RACE). siRNA was synthesized and tested by immunohistochemistry. KEY RESULTS Single doses of 2-thioUTP, UTP-γ-S and UTP increased IOP. This behaviour was concentration-dependent and partially antagonized by reactive blue 2. Silencing the P2Y2 receptor was observed in the ciliary body by immunohistochemistry labelling, where a reduction in the immunofluorescence was observed. This reduction in the expression of the P2Y2 receptor was concomitant with a reduction in IOP, which was measurable 24 h after treatment with the siRNA, maximal after 2 days, followed by a slow increase towards control values for the following 5 days. Application of the P2Y2 agonists after pretreatment of the animals with this siRNA did not produce any change in IOP. CONCLUSIONS AND IMPLICATIONS P2Y2 receptors increase IOP in New Zealand rabbits. The application of a siRNA for this receptor significantly reduced IOP, suggesting that this technology might be used for the treatment of glaucoma. PMID:21740413

  16. Analysis of copper surface features obtained using TEA CO2 laser at reduced air pressure

    NASA Astrophysics Data System (ADS)

    Momcilovic, M.; Trtica, M.; Ciganovic, J.; Savovic, J.; Stasic, J.; Kuzmanovic, M.

    2013-04-01

    Interaction of a transversely excited atmospheric (TEA) CO2 laser with rough copper surface, at reduced air pressure, was studied. Optical pulse duration of the laser employed was ∼2 μs, with the initial spike FWHM of ∼100 ns. Laser energy density of ∼32 J/cm2 (intensity ∼108 W/cm2) was above the plasma ignition threshold. Morphological features of the copper can be summarized as follows: (i) superficial damages, which take crater-shaped form at a higher number of accumulated laser pulses, (ii) development of melt pools with visible bubbles inside the damage region, (iii) formation of solid droplets at near periphery, and (iv) presence of “halo” effect at the irradiated surface. The laser induced surface changes were influenced by the target plasma formation. The formation of plasma influenced the laser-target interaction in two opposite ways: trough absorption of laser energy by the plasma, i.e. trough the effect of plasma shielding, and trough energy transfer from the plasma to the sample. Optical emission spectra were compared for laser induced plasma originated by a single and by cumulative laser pulses. It was found that plasma dimensions and emission intensities have a strong correlation with the number of accumulated laser pulses. Enhancement of both atomic and ionic copper lines was registered when laser induced plasma originated from a single pulse. Chemical analysis of the surface showed a tendency of copper content increase and oxygen content reduction when going from non-irradiated region to the central irradiated region. In the central damage zone, nearly pure copper was present which can be advantageous for some applications due to considerably lower contamination.

  17. Diet and exercise training reduce blood pressure and improve autonomic modulation in women with prehypertension.

    PubMed

    Sales, Allan R K; Silva, Bruno M; Neves, Fabricia J; Rocha, Natália G; Medeiros, Renata F; Castro, Renata R T; Nóbrega, Antonio C L

    2012-09-01

    Despite mortality from heart disease has been decreasing, the decline in death in women remains lower than in men. Hypertension (HT) is a major risk factor for cardiovascular disease. Therefore, approaches to prevent or delay the onset of HT would be valuable in women. Given this background, we investigated the effect of diet and exercise training on blood pressure (BP) and autonomic modulation in women with prehypertension (PHT). Ten women with PHT (39 ± 6 years, mean ± standard deviation) and ten with normotension (NT) (35 ± 11 years) underwent diet and exercise training for 12 weeks. Autonomic modulation was assessed through heart rate (HR) and systolic BP (SBP) variability, using time and frequency domain analyses. At preintervention, women with PHT had higher SBP (PHT: 128 ± 7 vs. NT: 111 ± 6 mmHg, p < 0.05) and lower HR variability [standard deviation of normal-to-normal beats (SDNN), PHT: 41 ± 18 vs. NT: 60 ± 19 ms, p < 0.05]. At post-intervention, peak oxygen consumption and muscular strength increased (p < 0.05), while body mass index decreased in both groups (p < 0.05). However, SBP decreased (118 ± 8 mmHg, p < 0.05 vs. preintervention) and total HR variability tended to increase (total power: 1,397 ± 570 vs. 2,137 ± 1,110 ms(2), p = 0.08) only in the group with PHT; consequently, HR variability became similar between groups at post-intervention (p > 0.05). Moreover, reduction in SBP was associated with augmentation in SDNN (r = -0.46, p < 0.05) and reduction in low-frequency power [LF (n.u.); r = 0.46, p < 0.05]. In conclusion, diet and exercise training reduced SBP in women with PHT, and this was associated with augmentation in parasympathetic and probably reduction in sympathetic cardiac modulation.

  18. The reamer/irrigator/aspirator reduces femoral canal pressure in simulated TKA.

    PubMed

    Van Gorp, Cornel C; Falk, James V; Kmiec, Stanley J; Siston, Robert A

    2009-03-01

    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.

  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. Further experiments on the stability of laminar and turbulent hydrogen-air flames at reduced pressures

    NASA Technical Reports Server (NTRS)

    Fine, Burton

    1957-01-01

    Stability limits for laminar and turbulent hydrogen-air burner flames were measured as a function of pressure, burner diameter, and composition. On the basis of a simple flame model, turbulent flashback involved a smaller effective penetration distance than laminar flashback. No current theoretical treatment predicts the observed pressure and diameter dependence of laminar and turbulent blowoff.

  1. Evaporative demand, transpiration, and photosynthesis: How are they changing?

    NASA Astrophysics Data System (ADS)

    Farquhar, G. D.; Roderick, M. L.

    2009-04-01

    Carbon dioxide concentration is increasing. This affects photosynthesis via increases in substrate availability (Farquhar et al. 1980). It reduces the amount of water transpired by plants to fix a given amount of carbon into an organic form; i.e it increases transpiration efficiency (Wong et al. 1979). It also warms the earth's surface. It is commonly supposed that this warming causes an increase in evaporative demand - the rate of water loss from a wet surface. This supposition has then been extended to effects on plant water availability, with the idea that there would be offsets to the gains in productivity associated with increased transpiration efficiency. The assumption that increased temperature means increased evaporative demand has also been applied to global maps of changes in soil water content. However, observations of pan evaporation rate show that this measure of evaporative demand has been decreasing in most areas examined over the last few decades. We reconcile these observations with theory by noting that, on long time scales, warming also involves water bodies, so that the vapour pressure at the earth's surface also increases. Using the physics of pan evaporation (Rotstayn et al. 2006) we show that the reduction in evaporative demand has been associated with two main effects, (1) "dimming", a reduction in sunlight received at the earth's surface because of aerosols and clouds, being the first phenomenon identified (Roderick and Farquhar 2002), and (2) "stilling", a reduction in wind speed, being the second (Roderick et al. 2007). We show that better accounting for changes in evaporative demand is important for estimating soil water changes, particularly in regions where precipitation exceeds evaporative demand (i.e where there are rivers) (Hobbins et al. 2008). We synthesise some of these results with others on vegetation change. References: Farquhar, GD, von Caemmerer, S, and Berry, JA, 1980: A biochemical model of photosynthetic CO2 assimilation

  2. 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.

  3. 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…

  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. 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.

  6. 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.

  7. Modulation of Pre-capillary Arteriolar Pressure with Drag Reducing Polymers: A Novel Method for Enhancing Microvascular Perfusion

    PubMed Central

    Pacella, John J.; Kameneva, Marina V.; Brands, Judith; Lipowsky, Herbert H.; Vink, Hans; Lavery, Linda L.; Villanueva, Flordeliza S.

    2012-01-01

    Objective We have shown that drag reducing polymers (DRP) enhance capillary perfusion during severe coronary stenosis and increase RBC velocity in capillaries, through uncertain mechanisms. We hypothesize that DRP decreases pressure loss from the aorta to the arteriolar compartment. Methods Intravital microscopy of the rat cremaster muscle and measurement of pressure in arterioles (diameters 20–132 µm) was performed in 24 rats. DRP (polyethylene oxide, 1 ppm) was infused i.v. and measurements were made at baseline and 20 minutes after completion of DRP infusion. In a 10 rat subset, additional measurements were made 3 minutes after the start, and 1–5 and 10 minutes after completion of DRP. Results Twenty minutes after the completion of DRP mean arteriolar pressure was 22% higher than baseline (from 42±3 to 49±3 mmHg, p<0.005, n=24). DRP decreased the pressure loss from the aorta to the arterioles by 24% (from 35±6 to 27±5 mmHg, p=0.001, n=10). In addition, there was a strong trend towards an increase in pressure at 10 minutes after the completion of DRP (n=10). Conclusions DRP diminishes pressure loss between the aorta and the arterioles. This results in a higher pre-capillary pressure and likely explains the observed DRP enhancement in capillary perfusion. PMID:22578102

  8. Negative Pressure Wound Therapy Reduces Pseudomonas Wound Contamination More Than Staphylococcus Aureus

    DTIC Science & Technology

    2010-09-01

    bioluminescent bacteria were used to evaluate the effectiveness of various irrigation pressures to remove bacteria from a wound. This approach has... bioluminescent bacteria and imaging technology to compare the effect of NPWT and WTD therapy on bacterial contamination of large, complex musculoskeletal wounds...is to determine if negative pressure wound therapy (NPWT) treatment results in fewer bacteria than wet-to-dry (WTD) dressings in a contaminated open

  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. Modeling of land surface evaporation by four schemes and comparison with FIFE observations

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Mitchell, Kenneth; Schaake, John; Xue, Yongkang; Pan, Hua-Lu; Koren, Victor; Duan, Qing Yun; Ek, Michael; Betts, Alan

    1996-03-01

    We tested four land surface parameterization schemes against long-term (5 months) area-averaged observations over the 15 km × 15 km First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) area. This approach proved to be very beneficial to understanding the performance and limitations of different land surface models. These four surface models, embodying different complexities of the evaporation/hydrology treatment, included the traditional simple bucket model, the simple water balance (SWB) model, the Oregon State University (OSU) model, and the simplified Simple Biosphere (SSiB) model. The bucket model overestimated the evaporation during wet periods, and this resulted in unrealistically large negative sensible heat fluxes. The SWB model, despite its simple evaporation formulation, simulated well the evaporation during wet periods, but it tended to underestimate the evaporation during dry periods. Overall, the OSU model ably simulated the observed seasonal and diurnal variation in evaporation, soil moisture, sensible heat flux, and surface skin temperature. The more complex SSiB model performed similarly to the OSU model. A range of sensitivity experiments showed that some complexity in the canopy resistance scheme is important in reducing both the overestimation of evaporation during wet periods and underestimation during dry periods. Properly parameterizing not only the effect of soil moisture stress but also other canopy resistance factors, such as the vapor pressure deficit stress, is critical for canopy resistance evaluation. An overly simple canopy resistance that includes only soil moisture stress is unable to simulate observed surface evaporation during dry periods. Given a modestly comprehensive time-dependent canopy resistance treatment, a rather simple surface model such as the OSU model can provide good area-averaged surface heat fluxes for mesoscale atmospheric models.

  11. Water evaporation from substrate tooth surface during dentin treatments.

    PubMed

    Kusunoki, Mizuho; Itoh, Kazuo; Gokan, Yuka; Nagai, Yoshitaka; Tani, Chihiro; Hisamitsu, Hisashi

    2011-01-01

    The purpose of this study was to evaluate changes in the quantity of water evaporation from tooth surfaces. The amount of water evaporation was measured using Multi probe adapter MPA5 and Tewameter TM300 (Courage+Khazaka Electric GmbH, Köln, Germany) after acid etching and GM priming of enamel; and after EDTA conditioning and GM priming of dentin. The results indicated that the amount of water evaporation from the enamel surface was significantly less than that from the dentin. Acid etching did not affect the water evaporation from enamel, though GM priming significantly decreased the evaporation (83.48 ± 15.14% of that before priming). The evaporation from dentin was significantly increased by EDTA conditioning (131.38 ± 42.08% of that before conditioning) and significantly reduced by GM priming (80.26 ± 7.43% of that before priming). It was concluded that dentin priming reduced water evaporation from the dentin surface.

  12. Evaporator film coefficients of grooved heat pipes

    NASA Technical Reports Server (NTRS)

    Kamotani, Y.

    1978-01-01

    The heat transfer rate in the meniscus attachment region of a grooved heat pipe evaporator is studied theoretically. The analysis shows that the evaporation takes place mainly in the region where the liquid changes its shape sharply. However, comparisons with available heat transfer data indicate that the heat transfer rate in the meniscus varying region is substantially reduced probably due to groove wall surface roughness.

  13. 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.

  14. Why Your Mother Was Right: How Potassium Intake Reduces Blood Pressure.

    PubMed

    Ellison, David H; Terker, Andrew S

    2015-01-01

    Low potassium intake, common in western diets, increases blood pressure and enhances salt-sensitivity. Most humans in "Westernized" countries also consume excess salt. In studies using mice, we found that a high-salt, low-potassium diet activates the thiazide-sensitive Na-Cl cotransporter in the kidney. This effect led to sodium retention and increased blood pressure, and was dependent on plasma potassium. We postulated that this effect was mediated by changes in intracellular chloride caused by changes in membrane voltage. We developed a model in cultured cells permitting us to confirm this hypothesis. We then confirmed, using urinary exosomes, that dietary changes in normal humans, affect the thiazide-sensitive Na-Cl cotransporter in the same way. These data show that dietary potassium deficiency increases blood pressure largely by stimulating salt reabsorption along the distal nephron. They suggest that global efforts should focus on increasing potassium intake, which will attenuate the effects of high-salt diets.

  15. 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.

  16. 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

  17. Effect of reduced barometric pressure on water availability related to microbial growth.

    PubMed

    Hawrylewicz, E J; Hagen, C; Tolkacz, V; Ehrlich, R

    1967-01-01

    Data obtained from Mariner IV indicate that the barometric pressure on Mars is considerably lower than previously estimated. Current estimates from Mariner IV indicate a range from 4 to 7 mb and by near infrared spectroscopy 33-56 mb. Inasmuch as the pressure has a marked influence on availability of water, this should affect the existence of Martian life. At the maximum temperatures recorded on Mars, namely 25 degrees C, a barometric pressure of 30 mb is required for the retention of free water. The lower pressure, 4 mb, would suggest that the moisture is present as a vapor above the freezing point and consequently it is not available for utilizing by living cells. The lower estimates of barometric pressure also inversely affect the carbon dioxide concentration in the Martian atmosphere. Our previous studies have demonstrated that spores of Bacillus cereus survive, germinate and grow in a simulated Martian environment (2.4% CO2, 98 mb) supplemented with moisture. The studies described in this paper were designed to determine the effect of low barometric pressures (10 to 98 mb Hg) and high concentrations of carbon dioxide (37 to 100%) in the simulated Martian environment on survival and growth of B cereus. The organism was inoculated into a felsite-limonite soil at 8% moisture level. The temperature cycles used were 8 hr at -65 degrees C and 16 hr at 25 degrees C, or 20 hr at -65 degrees C and 4 hr at 25 degrees C. The data suggest that the organism after achieving maximum growth in the simulated Martian environment (2.4% CO2, 98 mb) immediately enters into the growth phase upon reinoculation into fresh soil. These data reflect upon the possibility of contamination through air movements. Based upon currently available Martian environmental data, the probability of contamination of Mars by terrestrial micro-organisms will be discussed.

  18. 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

  19. Reduced state relationship for limiting electrical conductances of aqueous ions over wide ranges of temperature and pressure

    NASA Astrophysics Data System (ADS)

    Marshall, William L.

    1987-09-01

    A reduced state relationship for limiting electrical conductances of aqueous ions to high temperatures and pressures is presented in which ionic conductance is a simple function of solvent density. Walden's rule is not observed. Specific parameters for 13 ions are included that can be used to calculate ionic conductances by the relationship. From these values, limiting equivalent conductances of many single and mixed aqueous electrolyte systems may be obtained over temperature-pressure ranges of 0-800 °C and up to 400 MPa (4000 bar), with reasonable estimates to 1000 °C and 1000 MPa.

  20. Quantitative analysis of acankoreoside A and acankoreagenin in the leaves of Schefflera octophylla and Schefflera actinophylla using pressurized liquid extraction and high-performance liquid chromatography coupled with evaporative light scattering detection.

    PubMed

    Cao, Kai-Yue; Qiao, Chun-Feng; Zhao, Jing; Xie, Jing; Li, Shao-Ping

    2015-07-01

    A rapid method based on pressurized liquid extraction followed by high-performance liquid chromatography coupled with evaporative light scattering detection was firstly developed for the quantitative analysis of two bioactive triterpenoids (acankoreoside A and acankoreagenin) in the leaves of Schefflera octophylla and Schefflera actinophylla. The analysis was performed on an Agilent Zorbax SB-Aq column (4.6 × 50 mm, 3.5 μm) with gradient elution of 0.1% formic acid and acetonitrile. Calibration curves of two analytes showed good linearity (R(2) > 0.9990) within the tested ranges. This novel method is simple, rapid and accurate, and the results of quantification showed that contents of each investigated compound is significant high in natural S. octophylla (6.36-14.83%), which indicated that natural S. octophylla as potential medicinal resource. Furthermore, hierarchical clustering analysis based on the typical peaks of acankoreoside A and acankoreagenin from the 17 tested samples showed that natural and cultured Schefflera species were in different clusters, which could provide a means of discriminating between Schefflera species from different origins. Thus, acankoreoside A and acankoreagnin could be selected markers for quality control of S. octophylla and S. actinophylla.

  1. Reduced-order model for dynamic optimization of pressure swing adsorption processes

    SciTech Connect

    Agarwal, A.; Biegler, L.; Zitney, S.

    2007-01-01

    Over the past decades, pressure swing adsorption (PSA) processes have been widely used as energy-efficient gas and liquid separation techniques, especially for high purity hydrogen purification from refinery gases. 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. 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. Model reduction is one approach to generate cost-efficient low-order models which can be used as surrogate models in the optimization problems. The study develops a reduced-order model (ROM) based on proper orthogonal decomposition (POD), which is a low-dimensional approximation to a dynamic PDE-based model. Initially, a representative ensemble of solutions of the dynamic PDE system is constructed by solving a higher-order discretization of the model using the method of lines, a two-stage approach that discretizes the PDEs in space and then integrates the resulting DAEs over time. Next, the ROM method applies the Karhunen-Loeve expansion to derive a small set of empirical eigenfunctions (POD modes) which are used as basis functions within a Galerkin's projection framework to derive a low-order DAE system that accurately describes the dominant dynamics of the PDE system. The proposed method leads to a DAE system of significantly lower order, thus replacing the one obtained from spatial discretization before and making optimization problem computationally-efficient. The method has been applied to the dynamic

  2. 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.

  3. Reducing the pressure drag of a D-shaped bluff body using linear feedback control

    NASA Astrophysics Data System (ADS)

    Dalla Longa, L.; Morgans, A. S.; Dahan, J. A.

    2017-01-01

    The pressure drag of blunt bluff bodies is highly relevant in many practical applications, including to the aerodynamic drag of road vehicles. This paper presents theory revealing that a mean drag reduction can be achieved by manipulating wake flow fluctuations. A linear feedback control strategy then exploits this idea, targeting attenuation of the spatially integrated base (back face) pressure fluctuations. Large-eddy simulations of the flow over a D-shaped blunt bluff body are used as a test-bed for this control strategy. The flow response to synthetic jet actuation is characterised using system identification, and controller design is via shaping of the frequency response to achieve fluctuation attenuation. The designed controller successfully attenuates integrated base pressure fluctuations, increasing the time-averaged pressure on the body base by 38%. The effect on the flow field is to push the roll-up of vortices further downstream and increase the extent of the recirculation bubble. This control approach uses only body-mounted sensing/actuation and input-output model identification, meaning that it could be applied experimentally.

  4. RCS pressure under reduced inventory conditions following a loss of residual heat removal

    SciTech Connect

    Palmrose, D.E.; Hughes, E.D.; Johnsen, G.W.

    1992-08-01

    The thermal-hydraulic response of a closed-reactor coolant system to loss of residual heat removal (RHR) cooling is investigated. The processes examined include: core coolant boiling and steam generator reflux condensation, pressure increase on the primary side, heat transfer mechanisms on the steam generator primary and secondary sides, and effects of noncondensible gas on heat transfer processes.

  5. RCS pressure under reduced inventory conditions following a loss of residual heat removal

    SciTech Connect

    Palmrose, D.E.; Hughes, E.D.; Johnsen, G.W.

    1992-01-01

    The thermal-hydraulic response of a closed-reactor coolant system to loss of residual heat removal (RHR) cooling is investigated. The processes examined include: core coolant boiling and steam generator reflux condensation, pressure increase on the primary side, heat transfer mechanisms on the steam generator primary and secondary sides, and effects of noncondensible gas on heat transfer processes.

  6. 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....

  7. 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.

  8. SY 09-4 PUBLIC POLICIES TO REDUCE SALT IN PROCESSED FOODS: HOW THEY MAY CORRELATE WITH IMPROVEMENT IN BLOOD PRESSURE CONTROL AND REDUCED CARDIOVASCULAR MORTALITY.

    PubMed

    Campbell, Norm

    2016-09-01

    Hypertension is the second leading global risk for death and disability after unhealthy diets. Amongst dietary risks, excess dietary salt (sodium) is the leading risk. As dietary sodium increases, blood pressure increases linearly. In meta-analyses of higher quality cohort studies and in a meta-analysis of randomized controlled trials, higher dietary sodium is linearly associated with increased cardiovascular disease. There are an estimated xxxx deaths and xxx DALYs in 2013 from excess dietary sodium. The World Health Organization has a recommended sodium (salt) intake of less than 2000 mg (5 g)/day with the World Health Assembly setting a voluntary target of a 30% reduction by 2025. In high income countries, the vast majority of dietary salt comes from additives during commercial food processing. In low income countries the vast majority of salt is 'discretionary' being added at home in cooking and at the table, often as condiments (e.g. soya/fish sauce or bouillon). Many highly populated countries are in nutritional transition and have the highest salt intakes with both commercial and discretionary sources. Notably diets of natural foods without added salt contain 500-800 mg sodium/day. Policies to reduce commercial sources of salt have had demonstrated efficacy at reducing salt intake, blood pressure and cardiovascular disease. Use of salt replacers (potassium partly replacing sodium) hold promise to reduce discretionary salt and in randomized controlled trials reduce blood pressure. There is renewed 'scientific' controversy about reducing dietary salt. The controversy is largely based on a small number of individuals many of whom have had associations with the food and salt industry and/or have conducted research using methods highly prone to erroneous findings. Sadly several of those dissenting have made false or misleading statements about the science supporting salt reduction, altered scientific formula to make their controversial data appear more

  9. 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.

  10. Evaporation from microreservoirs.

    PubMed

    Lynn, N Scott; Henry, Charles S; Dandy, David S

    2009-06-21

    As a result of very large surface area to volume ratios, evaporation is of significant importance when dealing with lab-on-a-chip devices that possess open air/liquid interfaces. For devices utilizing a reservoir as a fluid delivery method to a microfluidic network, excessive evaporation can quickly lead to reservoir dry out and overall device failure. Predicting the rates of evaporation from these reservoirs is difficult because the position of the air/liquid interface changes with time as the volume of liquid in the reservoir decreases. Here we present a two-step method to accurately predict the rates of evaporation of such an interface over time. First, a simple method is proposed to determine the shape of an air/liquid meniscus in a reservoir given a specific liquid volume. Second, computational fluid dynamics simulations are used to calculate the instantaneous rate of evaporation for that meniscus shape. It is shown that the rate of evaporation is strongly dependent on the overall geometry of the system, enhanced in expanding reservoirs while suppressed in contracting reservoirs, where the geometry can be easily controlled with simple experimental methods. Using no adjustable parameters, the model accurately predicts the position of the inner moving contact line as a function of time following meniscus rupture in poly(dimethylsiloxane) reservoirs, and predicts the overall time for the persistence of liquid in those reservoirs to within 0.5 minutes. The methods in this study can be used to design holding reservoirs for lab-on-a-chip devices that involve no external control of evaporation, such that evaporation rates can be adjusted as necessary by modification of the reservoir geometry.

  11. Experimental study of the use of vortex generators to reduce fluctuating pressure loads in shock wave turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Barter, John W.; Dolling, David S.

    1995-01-01

    Fluctuating wall pressure measurements have been made in a separated shock wave/turbulent boundary layer interaction produced by an unswept compression corner in a Mach 5 flow. Wheeler doublet vortex generators were placed 15.8 boundary layer thicknesses upstream of the corner to study their effect on the fluctuating pressure loads produced by the translating separation shock. The vortex generators produced significant three-dimensionality in an otherwise two-dimensional interaction. They reduced the upstream influence and the length of the region of shock motion by 60% and 64%, respectively, decreased the maximum wall pressure rms by 23%, and shifted the fluctuations to a higher frequency band. The maximum fraction of energy in the 100-500 Hz frequency band is decreased by 11%. These changes are due to a fuller boundary layer profile, a weaker separation shock, and increased boundary layer turbulence causing increased separation shock jitter.

  12. Evaporation in equilibrium, in vacuum, and in hydrogen gas

    NASA Technical Reports Server (NTRS)

    Nagahara, Hiroko

    1993-01-01

    Evaporation experiments were conducted for SiO2 in three different conditions: in equilibrium, in vacuum, and in hydrogen gas. Evaporation rate in vacuum is about two orders of magnitude smaller than that in equilibrium, which is consistent with previous works. The rate in hydrogen gas changes depending on hydrogen pressure. The rate at 10 exp -7 bar of hydrogen pressure is as small as that of free evaporation, but at 10 exp -5 bar of hydrogen pressure it is larger than that in equilibrium. In equilibrium and in vacuum, the evaporation rate is limited by decomposition of SiO2 on the crystal surface, but it is limited by a diffusion process for evaporation in hydrogen gas. Therefore, evaporation rate of minerals in the solar nebula can be shown neither by that in equilibrium nor by that in vacuum. The maximum temperature of the solar nebula at the midplane at 2-3 AU where chondrites are believed to have originated is calculated to be as low as 150 K, 1500 K, or in between them. The temperature is, in any case, not high enough for total evaporation of the interstellar materials. Therefore, evaporation of interstellar materials is one of the most important processes for the origin and fractionation of solid materials. The fundamental process of evaporation of minerals has been intensively studied for these several years. Those experiments were carried out either in equilibrium or in vacuum; however, evaporation in the solar nebula is in hydrogen (and much smaller amount of helium) gas. In order to investigate evaporation rate and compositional (including isotopic) fractionation during evaporation, vaporization experiments for various minerals in various conditions are conducted. At first, SiO2 was adopted for a starting material, because thermochemical data and its nature of congruent vaporization are well known. Experiments were carried out in a vacuum furnace system.

  13. A high-pressure cryocooling method for protein crystals and biological samples with reduced background X-ray scatter

    PubMed Central

    Kim, Chae Un; Wierman, Jennifer L.; Gillilan, Richard; Lima, Enju; Gruner, Sol M.

    2013-01-01

    High-pressure cryocooling has been developed as an alternative method for cryopreservation of macromolecular crystals and successfully applied for various technical and scientific studies. The method requires the preservation of crystal hydration as the crystal is pressurized with dry helium gas. Previously, crystal hydration was maintained either by coating crystals with a mineral oil or by enclosing crystals in a capillary which was filled with crystallization mother liquor. These methods are not well suited to weakly diffracting crystals because of the relatively high background scattering from the hydrating materials. Here, an alternative method of crystal hydration, called capillary shielding, is described. The specimen is kept hydrated via vapor diffusion in a shielding capillary while it is being pressure cryocooled. After cryocooling, the shielding capillary is removed to reduce background X-ray scattering. It is shown that, compared to previous crystal-hydration methods, the new hydration method produces superior crystal diffraction with little sign of crystal damage. Using the new method, a weakly diffracting protein crystal may be properly pressure cryo­cooled with little or no addition of external cryoprotectants, and significantly reduced background scattering can be observed from the resulting sample. Beyond the applications for macromolecular crystallography, it is shown that the method has great potential for the preparation of noncrystalline hydrated biological samples for coherent diffraction imaging with future X-ray sources. PMID:23396891

  14. Reducing effect of aerobic exercise on blood pressure of essential hypertensive patients

    PubMed Central

    Wen, Hongwei; Wang, Lijuan

    2017-01-01

    Abstract Background: The comprehensive meta-analysis aimed to explore the reductive effect of aerobic exercise on blood pressure of hypertensive patients. Methods: The related researches were selected from PubMed and Embase databases up to June 2016. Based on specific inclusive criteria, the eligible studies were selected, and the heterogeneities in their results were estimated by χ2-based Q-test and I2 statistics. Quantitative meta-analysis was assessed by R 3.12 software, and results were presented by standardized mean difference (SMD) and their 95% confidence intervals (CIs). Outcome indicators were systolic blood pressure (SBP) and diastolic blood pressure (DBP). The publication biases were estimated by Egger test. Besides, the “leave one out” method was used for sensitivity evaluations. Results: As a result, a total of 13 papers with 802 samples were included. Based on the meta-analysis results, there were no significant differences in SBP and DBP between aerobic and control groups before exercise (SMD = 0.15, 95%CI: −0.16–0.46; SMD = 0.16, 95% CI: −0.23–0.55). However, significant reductions were obviously in aerobic group after aerobics, compared with control (SMD = −0.79, 95% CI: −1.29 to −0.28; SMD = −0.63, 95% CI: −1.14 to −0.12). A significant publication bias was detected in SBP (t = −2.2314, P = 0.04549) but not in DBP (t = −1.4962, P = 0.1604). Additionally, the DBP result would be altered after the exclusion of 2 individual papers. Conclusion: Aerobic exercise may be a potential nonpharmacological treatment for blood pressure improvement in essential hypertensive patients. PMID:28296729

  15. 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.

  16. Use of pressure reducing seats and cushions in a community setting.

    PubMed

    Collins, Fiona

    2002-01-01

    It is generally accepted that sitting for long periods of time without frequent repositioning or provision of appropriate cushions or chairs can lead to pressure ulcer development in people who are elderly, frail, immobile or neurologically impaired. When sitting, in comparison to lying, only a small surface area of the body is providing support, predominantly the buttocks and thighs, and the feet. Therefore, interface pressures are much greater in sitting than lying. Sitting for long periods of time can result in the person adopting poor posture, which in turn can lead to the development of pressure ulcers, particularly on the buttocks, sacrum, greater trochanter and heels. Assessment and provision of appropriate seating equipment for people at risk is often difficult for clinicians working in the community. This article aims to describe the problems experienced by people who sit for long periods of time, to discuss where people should go in order to obtain help with seating needs, and outline some of the potential solutions to poor seating which are available to community staff.

  17. Low intravascular pressure activates endothelial cell TRPV4 channels, local Ca2+ events, and IKCa channels, reducing arteriolar tone

    PubMed Central

    Bagher, Pooneh; Beleznai, Timea; Kansui, Yasuo; Mitchell, Ray; Garland, Christopher J.; Dora, Kim A.

    2012-01-01

    Endothelial cell (EC) Ca2+-activated K channels (SKCa and IKCa channels) generate hyperpolarization that passes to the adjacent smooth muscle cells causing vasodilation. IKCa channels focused within EC projections toward the smooth muscle cells are activated by spontaneous Ca2+ events (Ca2+ puffs/pulsars). We now show that transient receptor potential, vanilloid 4 channels (TRPV4 channels) also cluster within this microdomain and are selectively activated at low intravascular pressure. In arterioles pressurized to 80 mmHg, ECs generated low-frequency (∼2 min−1) inositol 1,4,5-trisphosphate receptor-based Ca2+ events. Decreasing intraluminal pressure below 50 mmHg increased the frequency of EC Ca2+ events twofold to threefold, an effect blocked with the TRPV4 antagonist RN1734. These discrete events represent both TRPV4-sparklet- and nonsparklet-evoked Ca2+ increases, which on occasion led to intracellular Ca2+ waves. The concurrent vasodilation associated with increases in Ca2+ event frequency was inhibited, and basal myogenic tone was increased, by either RN1734 or TRAM-34 (IKCa channel blocker), but not by apamin (SKCa channel blocker). These data show that intraluminal pressure influences an endothelial microdomain inversely to alter Ca2+ event frequency; at low pressures the consequence is activation of EC IKCa channels and vasodilation, reducing the myogenic tone that underpins tissue blood-flow autoregulation. PMID:23071308

  18. Method for improving accuracy in full evaporation headspace analysis.

    PubMed

    Xie, Wei-Qi; Chai, Xin-Sheng

    2017-03-21

    We report a new headspace analytical method in which multiple headspace extraction is incorporated with the full evaporation technique. The pressure uncertainty caused by the solid content change in the samples has a great impact to the measurement accuracy in the conventional full evaporation headspace analysis. The results (using ethanol solution as the model sample) showed that the present technique is effective to minimize such a problem. The proposed full evaporation multiple headspace extraction analysis technique is also automated and practical, and which could greatly broaden the applications of the full-evaporation-based headspace analysis. This article is protected by copyright. All rights reserved.

  19. Hydrophobically modified nanoparticle suspensions to enhance water evaporation rate

    NASA Astrophysics Data System (ADS)

    Huang, Zhi; Li, Xiaoying; Yuan, Hao; Feng, Yanhui; Zhang, Xinxin

    2016-10-01

    The evaporation rates of water can be enhanced by adding the hydrophobically modified nanoparticles as a suspension. The magnitudes of enhancement are related to the diameter and mass concentration of nanoparticles. In particular, a 15% enhancement was achieved after adding the modified Al2O3 nanoparticle with a diameter of 13 nm and mass percentage of 0.02%. A theoretical model was established in order to estimate the evaporation rates of hydrophobic particle-based nanofluids. The obtained results indicate that the enhanced evaporation rates are attributed to the elevated saturated vapor pressures of the nanofluids. These results may have important applications for energy-efficient enhancement of water evaporation rates.

  20. 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.

  1. Aquaporin deletion in mice reduces intraocular pressure and aqueous fluid production.

    PubMed

    Zhang, Duo; Vetrivel, L; Verkman, A S

    2002-06-01

    Aquaporin (AQP) water channels are expressed in the eye at sites of aqueous fluid production and outflow: AQP1 and AQP4 in nonpigmented ciliary epithelium, and AQP1 in trabecular meshwork endothelium. Novel methods were developed to compare aqueous fluid dynamics in wild-type mice versus mice lacking AQP1 and/or AQP4. Aqueous fluid production was measured by in vivo confocal microscopy after transcorneal iontophoretic introduction of fluorescein. Intraocular pressure (IOP), outflow, and anterior chamber compliance were determined from pressure measurements in response to fluid infusions using micropipettes. Aqueous fluid volume and [Cl(-)] were assayed in samples withdrawn by micropipettes. In wild-type mice (CD1 genetic background, age 4-6 wk), IOP was 16.0 +/- 0.4 mmHg (SE), aqueous fluid volume 7.2 +/- 0.3 microl, fluid production 3.6 +/- 0.2 microl/h, fluid outflow 0.36 +/- 0.06 microl/h/mmHg, and compliance 0.036 +/- 0.006 microl/mmHg. IOP was significantly decreased by up to 1.8 mmHg (P < 0.002) and fluid production by up to 0.9 microl/h in age/litter-matched mice lacking AQP1 and/or AQP4 (outbred CD1 and inbred C57/bl6 genetic backgrounds). However, AQP deletion did not significantly affect outflow, [Cl(-)], volume, or compliance. These results provide evidence for the involvement of AQPs in intraocular pressure regulation by facilitating aqueous fluid secretion across the ciliary epithelium. AQP inhibition may thus provide a novel approach for the treatment of elevated IOP.

  2. Enhancement of liquid treatment efficiency by microwave plasma under flow-induced reduced pressure

    NASA Astrophysics Data System (ADS)

    Ito, Michiko; Takahashi, Tomohiro; Takitou, Sho; Takashima, Seigo; Nomura, Norio; Kitagawa, Tominori; Toyoda, Hirotaka

    2017-02-01

    A new microwave plasma device system for in-line solution treatment is developed. In this system, the Venturi effect for pressure reduction is utilized for stable and effective plasma production. The decomposition of phenol solution is tested to verify the efficiency of an in-line plasma treatment system, and such a treatment system is confirmed to have a higher decomposition efficiency than our previously developed batch-type treatment system. Increases in phenol decomposition speed and decomposition energy efficiency with increasing solution flow rate are observed, which suggests the suppression of OH radical recombination and the utilization of OH radicals under flowing solution conditions.

  3. Analytical solution for soil water redistribution during evaporation process.

    PubMed

    Teng, Jidong; Yasufuku, Noriyuki; Liu, Qiang; Liu, Shiyu

    2013-01-01

    Simulating the dynamics of soil water content and modeling soil water evaporation are critical for many environmental and agricultural strategies. The present study aims to develop an analytical solution to simulate soil water redistribution during the evaporation process. This analytical solution was derived utilizing an exponential function to describe the relation of hydraulic conductivity and water content on pressure head. The solution was obtained based on the initial condition of saturation and an exponential function to model the change of surface water content. Also, the evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Comparisons between the proposed analytical solution and experimental result are presented from the aspects of soil water redistribution, evaporative rate and cumulative evaporation. Their good agreement indicates that this analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile.

  4. Novel mechanism within the paraventricular nucleus reduces both blood pressure and hypothalamic pituitary-adrenal axis responses to acute stress

    PubMed Central

    Erdos, Benedek; Clifton, Rebekah R.; Liu, Meng; Li, Hongwei; McCowan, Michael L.; Sumners, Colin

    2015-01-01

    Macrophage migration inhibitory factor (MIF) counteracts pressor effects of angiotensin II (ANG II) in the paraventricular nucleus of the hypothalamus (PVN) in normotensive rats, but this mechanism is absent in spontaneously hypertensive rats (SHRs) due to a lack of MIF in PVN neurons. Since endogenous ANG II in the PVN modulates stress reactivity, we tested the hypothesis that replacement of MIF in PVN neurons would reduce baseline blood pressure and inhibit stress-induced increases in blood pressure and plasma corticosterone in adult male SHRs. Radiotelemetry transmitters were implanted to measure blood pressure, and then an adeno-associated viral vector expressing either enhanced green fluorescent protein (GFP) or MIF was injected bilaterally into the PVN. Cardiovascular responses to a 15-min water stress (1-cm deep, 25°C) and a 60-min restraint stress were evaluated 3–4 wk later. MIF treatment in the PVN attenuated average restraint-induced increases in blood pressure (37.4 ± 2.0 and 27.6 ± 3.5 mmHg in GFP and MIF groups, respectively, P < 0.05) and corticosterone (42 ± 2 and 36 ± 3 μg/dl in GFP and MIF groups, respectively, P < 0.05). MIF treatment in the PVN also reduced stress-induced elevations in the number of c-Fos-positive cells in the rostral ventrolateral medulla (71 ± 5 in GFP and 47 ± 5 in MIF SHRs, P < 0.01) and corticotropin-releasing factor mRNA expression in the PVN. However, MIF had no significant effects on the cardiovascular responses to water stress in SHRs or to either stress in Sprague-Dawley rats. Therefore, viral vector-mediated restoration of MIF in PVN neurons of SHRs attenuates blood pressure and hypothalamic pituitary adrenal axis responses to stress. PMID:26071542

  5. Novel mechanism within the paraventricular nucleus reduces both blood pressure and hypothalamic pituitary-adrenal axis responses to acute stress.

    PubMed

    Erdos, Benedek; Clifton, Rebekah R; Liu, Meng; Li, Hongwei; McCowan, Michael L; Sumners, Colin; Scheuer, Deborah A

    2015-08-15

    Macrophage migration inhibitory factor (MIF) counteracts pressor effects of angiotensin II (ANG II) in the paraventricular nucleus of the hypothalamus (PVN) in normotensive rats, but this mechanism is absent in spontaneously hypertensive rats (SHRs) due to a lack of MIF in PVN neurons. Since endogenous ANG II in the PVN modulates stress reactivity, we tested the hypothesis that replacement of MIF in PVN neurons would reduce baseline blood pressure and inhibit stress-induced increases in blood pressure and plasma corticosterone in adult male SHRs. Radiotelemetry transmitters were implanted to measure blood pressure, and then an adeno-associated viral vector expressing either enhanced green fluorescent protein (GFP) or MIF was injected bilaterally into the PVN. Cardiovascular responses to a 15-min water stress (1-cm deep, 25°C) and a 60-min restraint stress were evaluated 3-4 wk later. MIF treatment in the PVN attenuated average restraint-induced increases in blood pressure (37.4 ± 2.0 and 27.6 ± 3.5 mmHg in GFP and MIF groups, respectively, P < 0.05) and corticosterone (42 ± 2 and 36 ± 3 μg/dl in GFP and MIF groups, respectively, P < 0.05). MIF treatment in the PVN also reduced stress-induced elevations in the number of c-Fos-positive cells in the rostral ventrolateral medulla (71 ± 5 in GFP and 47 ± 5 in MIF SHRs, P < 0.01) and corticotropin-releasing factor mRNA expression in the PVN. However, MIF had no significant effects on the cardiovascular responses to water stress in SHRs or to either stress in Sprague-Dawley rats. Therefore, viral vector-mediated restoration of MIF in PVN neurons of SHRs attenuates blood pressure and hypothalamic pituitary adrenal axis responses to stress.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Cholinergic agonists reduce blood pressure in a mouse model of systemic lupus erythematosus.

    PubMed

    Fairley, Amber S; Mathis, Keisa W

    2017-04-01

    Increased inflammation arising from an abnormal immune response can damage healthy tissue and lead to disease progression. An important example of this is the accumulation of inflammatory mediators in the kidney, which can subsequently lead to hypertension and renal injury. The origin of this inflammation may involve neuro-immune interactions. For example, the novel vagus nerve-to-spleen mechanism known as the "cholinergic anti-inflammatory pathway" controls inflammation upon stimulation. However, if this pathway is dysfunctional, inflammation becomes less regulated and chronic inflammatory diseases such as hypertension may develop. Systemic lupus erythematosus (SLE) is an autoimmune disease with aberrant immune function, increased renal inflammation, and prevalent hypertension. We hypothesized that the cholinergic anti-inflammatory pathway is impaired in SLE and that stimulation of this pathway would protect from the progression of hypertension in SLE mice. Female SLE (NZBWF1) and control (NZW) mice were administered nicotine or vehicle for 7 days (2 mg/kg/day, subcutaneously) in order to stimulate the cholinergic anti-inflammatory pathway at the level of the splenic nicotinic acetylcholine receptor (α7-nAChR). Blood pressure was assessed posttreatment. Nicotine-treated SLE mice did not develop hypertension and this lower blood pressure (compared to saline-treated SLE mice) coincided with lower splenic and renal cortical expression of pro-inflammatory cytokines. These data provide evidence that the cholinergic anti-inflammatory pathway is impaired in SLE In addition, these data suggest that stimulation of the cholinergic anti-inflammatory pathway can protect the kidney by dampening inflammation and therefore prevent the progression of hypertension in the setting of SLE.

  11. 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.

  12. 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.

  13. Evaporative condensing minimizes system power requirements

    SciTech Connect

    Knebel, D.E.

    1997-04-01

    Evaporative condensing is a heat-rejection technology widely applied with industrial refrigeration. When employed with HVAC systems it can reduce electrical energy and demand consumption of an HVAC system by 20 to 40%, depending on location, compared to air-cooled condensing. Evaporative condensing allows direct-expansion (DX) systems to achieve energy and demand consumption comparable to the most efficient chilled water central plant systems. As the industry focuses its attention on solving the problems of energy conservation, demand reduction, and global warming, high-efficiency air conditioning systems utilizing evaporative condensing provide a reliable and cost-effective solution today. This article addresses the advantages of evaporative condensing over air-cooled and water-cooled condensing in DX packaged systems as well as chiller/cooling tower systems. A review of condensing methods and standard system operating characteristics will be used as examples to illustrate the thermodynamic benefits of evaporative condensing. Requirements for successful operation of evaporative condensers will be discussed.

  14. 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.

  15. 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.

  16. (−)-Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats

    PubMed Central

    Berenyiova, A.; Drobna, M.; Lukac, S.

    2016-01-01

    This study investigated the effects of subchronic (−)-epicatechin (Epi) treatment on locomotor activity and hypertension development in young spontaneously hypertensive rats (SHR). Epi was administered in drinking water (100 mg/kg/day) for 2 weeks. Epi significantly prevented the development of hypertension (138 ± 2 versus 169 ± 5 mmHg, p < 0.001) and reduced total distance traveled in the open-field test (22 ± 2 versus 35 ± 4 m, p < 0.01). In blood, Epi significantly enhanced erythrocyte deformability, increased total antioxidant capacity, and decreased nitrotyrosine concentration. In the aorta, Epi significantly increased nitric oxide (NO) synthase (NOS) activity and elevated the NO-dependent vasorelaxation. In the left heart ventricle, Epi increased NOS activity without altering gene expressions of nNOS, iNOS, and eNOS. Moreover, Epi reduced superoxide production in the left heart ventricle and the aorta. In the brain, Epi increased nNOS gene expression (in the brainstem and cerebellum) and eNOS expression (in the cerebellum) but had no effect on overall NOS activity. In conclusion, Epi prevented the development of hypertension and reduced locomotor hyperactivity in young SHR. These effects resulted from improved cardiovascular NO bioavailability concurrently with increased erythrocyte deformability, without changes in NO production in the brain. PMID:27885334

  17. 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.''

  18. 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.

  19. 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.

  20. DPP-4 Inhibitor Reduces Central Blood Pressure in a Diabetic and Hypertensive Patient

    PubMed Central

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

    2015-01-01

    Abstract 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

  1. 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.

  2. Hypertonic/Hyperoncotic Resuscitation from Shock: Reduced Volume Requirement and Lower Intracranial Pressure

    DTIC Science & Technology

    1989-10-01

    volume re- gs reference organs for measurement 3f organ blood suscitation with hypertonic saline dextran flow, using radioactive microspheres. All...oastllto Amaintained throyighout the 30 minute shoth Interval Blood was At ot; sir -o,;tnrn M,’.t was rvdured Iron 1111 tmean+SC r-ov~ed to reduce...a volume much smaller than the original shed blood volume (4-12). The addition of colloid, usually 6.0% low-molecular weight dextran , has been used

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

    DOEpatents

    Polsky, Yarom [Oak Ridge, TN; Grubelich, Mark C [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM

    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.

  4. 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

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

    PubMed

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

    2015-11-03

    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.

  6. Laser Evaporation Studies.

    DTIC Science & Technology

    1987-10-01

    concentrated aqua regia and hydrochloric energy ions. The minimum pulsed evaporation rate which acid, respectively. The metallic films capped by cw laser...Force Office of Scientific Research or the U.S. Government. 17 COSATI CODES 18 SUBJECT TERMS (Continue on reverse if necessarl and identif by block

  7. Evaporation into Couette Flow

    DTIC Science & Technology

    2008-01-01

    v Yi Statistical analysis dependent variable Greek Symbols 13 Contact angle of sessile drop a Concentration thickness A Evaporated vapor penetration...31 5 FIGURES 1. Configuration of Three Sessile Drops ............................................. 10 2. Sketch of...Droplet Geometry ............................................................. 11 3. Shape Factor as a Function of Contact Angle

  8. Statin therapy reduces the likelihood of suboptimal blood pressure control among Ugandan adult diabetic patients

    PubMed Central

    Lumu, William; Kampiire, Leaticia; Akabwai, George Patrick; Kiggundu, Daniel Ssekikubo; Kibirige, Davis

    2017-01-01

    Background Hypertension is one of the recognized risk factors of cardiovascular diseases in adult diabetic patients. High prevalence of suboptimal blood pressure (BP) control has been well documented in the majority of studies assessing BP control in diabetic patients in sub-Saharan Africa. In Uganda, there is a dearth of similar studies. This study evaluated the prevalence and correlates of suboptimal BP control in an adult diabetic population in Uganda. Patients and methods This was a cross-sectional study that enrolled 425 eligible ambulatory adult diabetic patients attending three urban diabetic outpatient clinics over 11 months. Data about their sociodemographic characteristics and clinical history were collected using pre-tested questionnaires. Suboptimal BP control was defined according to the 2015 American Diabetes Association standards of diabetes care guideline as BP levels ≥140/90 mmHg. Results The mean age of the study participants was 52.2±14.4 years, with the majority being females (283, 66.9%). Suboptimal BP control was documented in 192 (45.3%) study participants and was independently associated with the study site (private hospitals; odds ratio 2.01, 95% confidence interval 1.18–3.43, P=0.01) and use of statin therapy (odds ratio 0.5, 95% confidence interval 0.26–0.96, P=0.037). Conclusion Suboptimal BP control was highly prevalent in this study population. Strategies to improve optimal BP control, especially in the private hospitals, and the use of statin therapy should be encouraged in adult diabetic patients. PMID:28260908

  9. Reducing Mechanical Formation Damage by Minimizing Interfacial Tension and Capillary Pressure in Tight Gas

    NASA Astrophysics Data System (ADS)

    Ahmed, Arshad; Talib Shuker, Muhannad; Rehman, Khalil; Bahrami, Hassan; Memon, Muhammad Khan

    2013-12-01

    Tight gas reservoirs incur problems and significant damage caused by low permeability during drilling, completion, stimulation and production. They require advanced improvement techniques to achieve flow gas at optimum rates. Water blocking damage (phase Trapping/retention of fluids) is a form of mechanical formation damage mechanism, which is caused by filtrate invasion in drilling operations mostly in fracturing. Water blocking has a noticeable impact on formation damage in gas reservoirs which tends to decrease relative permeability near the wellbore. Proper evaluation of damage and the factors which influence its severity is essential to optimize well productivity. Reliable data regarding interfacial tension between gas and water is required in order to minimize mechanical formation damage potential and to optimize gas production. This study was based on the laboratory experiments of interfacial tension by rising drop method between gas-brine, gas-condensate and gas-brine. The results showed gas condensate has low interfacial tension value 6 - 11 dynes/cm when compared to gas-brine and gas- diesel which were 44 - 58 dynes/cm and 14 - 19 dynes/cm respectively. In this way, the capillary pressure of brine-gas system was estimated as 0.488 psi, therefore diesel-gas system was noticed about 0.164 psi and 0.098 psi for condensate-gas system. A forecast model was used by using IFT values to predict the phase trapping which shows less severe phase trapping damage in case of condensate than diesel and brine. A reservoir simulation study was also carried out in order to better understand the effect of hysteresis on well productivity and flow efficiency affected due to water blocking damage in tight gas reservoirs.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Application of the open-lung concept during positive-pressure ventilation reduces pulmonary inflammation in newborn piglets.

    PubMed

    van Kaam, Anton H; Dik, Willem A; Haitsma, Jack J; De Jaegere, Anne; Naber, Birgitta A; van Aalderen, Wim M; Kok, Joke H; Lachmann, Burkhard

    2003-01-01

    It has been shown that application of the open-lung concept (OLC) during high-frequency oscillatory ventilation (HFOV) attenuates pulmonary inflammation. We hypothesized that this attenuation could also be achieved by applying the OLC during positive-pressure ventilation (PPV). After repeated whole-lung lavage, newborn piglets were assigned to one of three ventilation groups: (1) PPV(OLC); (2) HFOV(OLC), or (3) conventional PPV (PPV(CON)). After a ventilation period of 5 h, analysis of bronchoalveolar lavage fluid showed a reduced influx of polymorphonuclear neutrophils, interleukin 8, and thrombin activity in both OLC groups as compared with the PPV(CON) group. There were no differences in tumor necrosis factor alpha levels. We conclude that application of the OLC during PPV reduces pulmonary inflammation as compared with conventional PPV and that the magnitude of this reduction is comparable to that of HFOV.

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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.

  20. 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.

  1. Antenatal Hypoxia Induces Programming of Reduced Arterial Blood Pressure Response in Female Rat Offspring: Role of Ovarian Function

    PubMed Central

    Xiao, DaLiao; Huang, Xiaohui; Xue, Qin; Zhang, Lubo

    2014-01-01

    In utero exposure to adverse environmental factors increases the risk of cardiovascular disease in adulthood. The present study tested the hypothesis that antenatal hypoxia causes a gender-dependent programming of altered arterial blood pressure response (BP) in adult offspring. Time-dated pregnant rats were divided into normoxic and hypoxic (10.5% O2 from days 15 to 21 of gestation) groups. The experiments were conducted in adult offspring. Antenatal hypoxia caused intrauterine growth restriction, and resulted in a gender-dependent increase Angiotensin II (Ang II)-induced BP response in male offspring, but significant decrease in BP response in female offspring. The baroreflex sensitivity was not significantly altered. Consistent with the reduced blood pressure response, antenatal hypoxia significantly decreased Ang II-induced arterial vasoconstriction in female offspring. Ovariectomy had no significant effect in control animals, but significantly increased Ang II-induced maximal BP response in prenatally hypoxic animals and eliminated the difference of BP response between the two groups. Estrogen replacement in ovariectomized animals significantly decreased the BP response to angiotensin II I only in control, but not in hypoxic animals. The result suggests complex programming mechanisms of antenatal hypoxia in regulation of ovary function. Hypoxia-mediated ovary dysfunction results in the phenotype of reduced vascular contractility and BP response in female adult offspring. PMID:24905716

  2. Numerical simulation on the "S" characteristics and pressure fluctuation of reduced pump-turbine at start-up condition

    NASA Astrophysics Data System (ADS)

    Liu, D. M.; Zheng, J. S.; Wen, G. Z.; Zhao, Y. Z.; Shi, Q. H.

    2012-11-01

    The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to improve the "S" characteristics of reduced pump-turbine, several MGV (misaligned guide vane) schemes are calculated. The SST (shear stress turbulence) model is added to the N-S (Navier-strokes) governing equation. In order to predict the S-shaped curve accurately and develop a reliable tool for design improvement, the "S" characteristic is investigated in a whole pump-turbine including spiral casing, stay vanes, guide vanes, runner and draft tube. To validate the scheme reasonable, the mesh independent is tested. Comparison of unit discharge and unit speed performance showed that good correspondence is obtained between experimental data and calculated results. The "S shape" of reduced pump-turbine is eliminated with MGV schemes. Based on this, internal flow analysis is carried out adopting six typical MGV schemes at the same working condition. Through the calculation, we find that, first the pressure fluctuation is different between the guide vane and runner among the five MGV schemes, second the pressure fluctuation amplitude of MGV schemes D (4*35° and 16*6° average installed) is smallest, third the main frequency is the blade passing frequency and guide vane passing frequency at vane-less space and head cover, respectively. The conclusion is the "S shape" of pump-turbine can be improved with the average installed scheme.

  3. 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.

  4. Resistance training reduces systolic blood pressure in metabolic syndrome: a systematic review and meta-analysis of randomised controlled trials

    PubMed Central

    Ferreira, Paulo Henrique; Linares, Stephanie Nogueira; Machado, Aryane Flauzino; Pastre, Carlos Marcelo; Netto, Jayme

    2016-01-01

    Aim To evaluate the effects of resistance training on metabolic syndrome risk factors through comparison with a control group. Design Meta-analysis comparing resistance training interventions with control groups. Two independent reviewers selected the studies and assessed their quality and data. The pooled mean differences between resistance training and the control group were calculated using a fixed-effects model. Data sources The MEDLINE, PEDro, EMBASE, SPORTDiscus and The Cochrane Library databases were searched from their earliest records to 10 January 2015. Eligibility criteria for selecting studies Randomised controlled trials that compared the effect of resistance training on metabolic syndrome risk factors with a control group were included. All types of resistance training, irrespective of intensity, frequency or duration, were eligible. Results Only systolic blood pressure was significantly reduced, by 4.08 mm Hg (95% CI 1.33 to 6.82; p<0.01), following resistance training. The pooled effect showed a reduction of 0.04 mmol/L (95% CI −0.12, 0.21; p>0.05) for fasting plasma glucose, 0.00 (95% CI −0.05, 0.04; p>0.05) for high-density lipoprotein (HDL) cholesterol, 0.03 (95% CI −0.14, 0.20; p>0.05) for triglycerides, 1.39 mm Hg (95% CI −0.19, 2.98; p=0.08) for diastolic blood pressure and 1.09 cm (95% CI −0.12, 2.30; p=0.08) for waist circumference. Inconsistency (I2) for all meta-analysis was 0%. Conclusions Resistance training may help reduce systolic blood pressure levels, stroke mortality and mortality from heart disease in people with metabolic syndrome. Trial registration number CRD42015016538. PMID:26964146

  5. Increased evaporation kinetics of sessile droplets by using nanoparticles.

    PubMed

    Nguyen, Tuan A H; Nguyen, Anh V

    2012-12-11

    The effect of nanoparticles on the evaporation of a sessile droplet into air is still controversial. Unlike insoluble surfactants which reduce the droplet evaporation rate, here we show that the presence of nanoparticles and the increase of their concentration lead to an increase in the overall rate of diffusive evaporation and, consequently, a decrease of the droplet lifetime. The nanoparticles accumulating at the droplet edge due to the well-known coffee-ring effect pin the three-phase contact line for an extended time and maintain a large air-water interface area, leading to the increased evaporation rate. We provide a full analytical prediction for the lifetime of a sessile droplet evaporating by the combined pinned-receding mode. A master equation and a master diagram for the droplet lifetime of the combined mode are obtained and experimentally validated, and explain the effect of nanoparticles on increasing the global evaporation rate and decreasing the droplet lifetime.

  6. Simultaneous spreading and evaporation: recent developments.

    PubMed

    Semenov, Sergey; Trybala, Anna; Rubio, Ramon G; Kovalchuk, Nina; Starov, Victor; Velarde, Manuel G

    2014-04-01

    The recent progress in theoretical and experimental studies of simultaneous spreading and evaporation of liquid droplets on solid substrates is discussed for pure liquids including nanodroplets, nanosuspensions of inorganic particles (nanofluids) and surfactant solutions. Evaporation of both complete wetting and partial wetting liquids into a nonsaturated vapour atmosphere are considered. However, the main attention is paid to the case of partial wetting when the hysteresis of static contact angle takes place. In the case of complete wetting the spreading/evaporation process proceeds in two stages. A theory was suggested for this case and a good agreement with available experimental data was achieved. In the case of partial wetting the spreading/evaporation of a sessile droplet of pure liquid goes through four subsequent stages: (i) the initial stage, spreading, is relatively short (1-2 min) and therefore evaporation can be neglected during this stage; during the initial stage the contact angle reaches the value of advancing contact angle and the radius of the droplet base reaches its maximum value, (ii) the first stage of evaporation is characterised by the constant value of the radius of the droplet base; the value of the contact angle during the first stage decreases from static advancing to static receding contact angle; (iii) during the second stage of evaporation the contact angle remains constant and equal to its receding value, while the radius of the droplet base decreases; and (iv) at the third stage of evaporation both the contact angle and the radius of the droplet base decrease until the drop completely disappears. It has been shown theoretically and confirmed experimentally that during the first and second stages of evaporation the volume of droplet to power 2/3 decreases linearly with time. The universal dependence of the contact angle during the first stage and of the radius of the droplet base during the second stage on the reduced time has been

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. 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

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

    PubMed

    Noll, J; Cecala, A; Hummer, J

    2015-12-01

    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.

  13. 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.

  14. Long-term oral calcium supplementation reduces diastolic blood pressure in end stage renal disease. A randomized, double-blind, placebo controlled study.

    PubMed

    Petersen, L J; Rudnicki, M; Højsted, J

    1994-01-01

    Previous studies suggest that oral calcium supply reduces blood pressure in patients with mild to moderate hypertension. The aim of this study was to determine whether oral calcium supply reduces blood pressure in patients undergoing haemodialysis. The study was randomized, double-blind, and placebo controlled. Eleven patients received two grams of calcium per day and 12 patients received placebo. Three patients (one from the calcium group and two from the placebo group) dropped out within the first month. The groups were comparable at inclusion regarding blood pressure, weight, and serum values. Blood pressure measurements were auscultatory with a mercury manometer and diastolic blood pressure was measured as Korotkoff phase V. At inclusion a significant positive correlation between serum phosphate and blood pressure was found. After a study period of six months a significant reduction in diastolic blood pressure was found between the two groups (p < 0.05), but no difference was found in systolic blood pressure. The reduction in diastolic blood pressure was 6.9 mmHg of the pretreatment level in the calcium group. In conclusion, the treatment of secondary hyperparathyroidism with oral calcium gives good benefits in the regulation of diastolic blood pressure. A well controlled phosphate homeostasis may also be of importance for the control of blood pressure in haemodialysis patients.

  15. 242-A Evaporator water hammer event investigation

    SciTech Connect

    Wegener, D.L.

    1992-04-01

    On February 28, 1992, at approximately 1053 hours, a water hammer occurred at the 242-A Evaporator Facility located in the 200 East Area of the Hanford Site. The facility's Raw Water/Used Raw Water (RW/URW) system was undergoing operational testing at the time of the event. While trying to establish system water pressure, a downstream pressure control valve was overcome by water pressure and abruptly shut. Approximately 2300 gal/min of raw water flow was established before the valve closed. Supply water pressure was determined to be approximately 105 psig. During preliminary damage assessments a pressure gauge was found overranged and water was observed leaking from various components. Detailed evaluations are being conducted to assess potential damage to the EC-1 Condenser and other equipment associated with the RW/URW systems.

  16. 242-A Evaporator water hammer event investigation

    SciTech Connect

    Wegener, D.L.

    1992-04-01

    On February 28, 1992, at approximately 1053 hours, a water hammer occurred at the 242-A Evaporator Facility located in the 200 East Area of the Hanford Site. The facility`s Raw Water/Used Raw Water (RW/URW) system was undergoing operational testing at the time of the event. While trying to establish system water pressure, a downstream pressure control valve was overcome by water pressure and abruptly shut. Approximately 2300 gal/min of raw water flow was established before the valve closed. Supply water pressure was determined to be approximately 105 psig. During preliminary damage assessments a pressure gauge was found overranged and water was observed leaking from various components. Detailed evaluations are being conducted to assess potential damage to the EC-1 Condenser and other equipment associated with the RW/URW systems.

  17. Interfacial stability and self-similar rupture of evaporating liquid layers under vapor recoil

    NASA Astrophysics Data System (ADS)

    Wei, Tao; Duan, Fei

    2016-12-01

    We investigate interfacial stability of an evaporating viscous liquid layer above/below a horizontal heated substrate in the framework of a long-wave model that accounts for surface tension, positive/negative gravity, and evaporation effects of mass loss and vapor recoil. With the time-dependent linear stability analysis, it is found that the interface instability is enhanced by vapor recoil with time using an effective growth rate. The destabilizing mechanism of vapor thrust competes with the stabilizing surface tension, and the effects of the latter are not asymptotically negligible near rupture, reflected by a rescaled effective interfacial pressure. A two-dimensional nonlinear evolution is investigated for the quasi-equilibrium evaporating layers with different evaporative conditions for Rayleigh-Taylor unstable and sessile layers. For weak mass loss and strong vapor recoil, the well-defined capillary ridges emerge around a deepening narrow valley with increasing wavelength under a positive gravity, while, on the basis of initial condition, main and secondary droplets are either coalesced partially or separated by a sharp dry-out point under a negative gravity. The rupture location depends strongly on the characteristics of a given initial condition, except for the random perturbation. For both the cases, an increase in the modified evaporation number tends to reduce the rupture time tr and droplet thickness remarkably. Similarity analysis along with numerical strategy is presented for the final stage of touch-down dynamics, determined by a physical balance between the vapor recoil and capillary force. The evaporation-driven rupture with a significant vapor recoil and negligible mass loss is shown to contain a countably infinite number of similarity solutions whose horizontal and vertical length scales behave as (tr - t)1/2 and (tr - t)1/3. The first similarity solution represents a stable single-point rupture.

  18. 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.

  19. 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.

  20. Adiabatic burst evaporation from bicontinuous nanoporous membranes.

    PubMed

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk; Steinhart, Martin; Xue, Longjian

    2015-05-28

    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 10(7) μm(3) 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.

  1. Rapid atmospheric pressure plasma jet processed reduced graphene oxide counter electrodes for dye-sensitized solar cells.

    PubMed

    Liu, Hsiao-Wei; Liang, Sheng-Ping; Wu, Ting-Jui; Chang, Haoming; Kao, Peng-Kai; Hsu, Cheng-Che; Chen, Jian-Zhang; Chou, Pi-Tai; Cheng, I-Chun

    2014-09-10

    In this work, we present the use of reduced graphene oxide (rGO) as the counter electrode materials in dye-sensitized solar cells (DSSCs). rGO was first deposited on a fluorine-doped tin oxide glass substrate by screen-printing, followed by post-treatment to remove excessive organic additives. We investigated the effect of atmospheric pressure plasma jet (APPJ) treatment on the DSSC performance. A power conversion efficiency of 5.19% was reached when DSSCs with an rGO counter electrode were treated by APPJs in the ambient air for a few seconds. For comparison, it requires a conventional calcination process at 400 °C for 15 min to obtain comparable efficiency. Scanning electron micrographs show that the APPJ treatment modifies the rGO structure, which may reduce its conductivity in part but simultaneously greatly enhances its catalytic activity. Combined with the rapid removal of organic additives by the highly reactive APPJ, DSSCs with APPJ-treated rGO counter electrode show comparable efficiencies to furnace-calcined rGO counter electrodes with greatly reduced process time. This ultrashort process time renders an estimated energy consumption per unit area of 1.1 kJ/cm(2), which is only one-third of that consumed in a conventional furnace calcination process. This new methodology thus saves energy, cost, and time, which is greatly beneficial to future mass production.

  2. Angiotensin Type-2 (AT-2)-Receptor activation reduces renal fibrosis in cyclosporine nephropathy: Evidence for blood-pressure independent effect.

    PubMed

    Castoldi, Giovanna; di Gioia, Cira R T; Carletti, Raffaella; Roma, Francesca; Zerbini, Gianpaolo; Stella, Andrea

    2016-09-27

    Compound 21 (C21), selective agonist of AT2 receptors, shows antinflammatory effects in hypertension and nephroprotection in diabetes. The aim of this study was to evaluate the effects of C21 in cyclosporine nephropathy, which is characterized mainly by tubulo-interstitial fibrosis. Ten days before and during the experimental periods, low-salt diet was administered to Sprague Dawley rats. Cyclosporine-A (15mg/kg/day, i.p.) and cyclosporine-A plus C21 (0.3 mg/kg /day, i.p) were administered for 1 and 4 weeks. Control groups was left without any treatment. Blood pressure (plethysmographic method) and 24 hour albuminuria were measured once a week. At the end of the experiments, the kidneys were excised for histomorphometric analysis of renal fibrosis and for immunohistochemical evaluation of inflammatory infiltrates and type I and IV collagen expression.
    After 1 and 4 weeks, the rats treated with cyclosporine showed a significant increase (p <0.01) in blood pressure, no significant changes in albuminuria, a significant increase (p <0.01) in glomerular and tubulo-interstitial fibrosis and inflammatory infiltrates as compared to the control rats. Treatment with C21 did not modify the cyclosporine dependent increase of blood pressure, which was higher than in control rats, but after 4 weeks of treatment significantly reduced (p <0.01) glomerular and tubulo-interstitial fibrosis, type 1 collagen expression and macrophage infiltration, as compared to rats treated with cyclosporine.The administration of C21 showed a protective effect on cyclosporine nephropathy, decreasing renal fibrosis and macrophage infiltration. These data suggest that C21 may counteract tubulo-interstitial fibrosis, the most potent predictor of the progression of renal diseases.

  3. Angiotensin type-2 (AT-2)-receptor activation reduces renal fibrosis in cyclosporine nephropathy: evidence for blood pressure independent effect

    PubMed Central

    Castoldi, Giovanna; di Gioia, Cira R.T.; Carletti, Raffaella; Roma, Francesca; Zerbini, Gianpaolo; Stella, Andrea

    2016-01-01

    Compound 21 (C21), selective agonist of angiotensin type-2 (AT-2) receptors, shows anti-inflammatory effects in experimental models of hypertension and nephroprotection in diabetes. The aim of the present study was to evaluate the effects of C21 in cyclosporine nephropathy, which is characterized mainly by tubulo-interstitial fibrosis. Ten days before and during the experimental periods, low-salt diet was administered to Sprague–Dawley rats. Cyclosporine-A (CsA; 15 mg/kg per day, intraperitoneal injection) and CsA plus C21 (0.3 mg/kg per day, intraperitoneal injection) were administered for 1 and 4 weeks. Control groups were left without any treatment. Blood pressure (plethysmographic method) and 24 h urinary albumin excretion were measured once a week. At the end of the experimental protocols, the kidneys were excised for histomorphometric analysis of renal fibrosis and for immunohistochemical evaluation of inflammatory infiltrates and type I and type IV collagen expression. After 1 and 4 weeks, the rats treated with CsA showed a significant increase (P<0.01) in blood pressure, no significant changes in urinary albumin excretion and a significant increase (P<0.01) in glomerular and tubulo-interstitial fibrosis and inflammatory infiltrates as compared with the control rats. Treatment with C21 did not modify the CsA dependent increase of blood pressure, which was higher than in control rats, but after 4 weeks of treatment significantly reduced (P<0.01) glomerular and tubulo-interstitial fibrosis, type 1 collagen expression and macrophage infiltration, as compared with rats treated with cyclosporine. The administration of C21 showed a protective effect on cyclosporine nephropathy, decreasing renal fibrosis and macrophage infiltration. These data suggest that C21 may counteract tubulo-interstitial fibrosis, the most potent predictor of the progression of renal diseases. PMID:27679859

  4. Improved Blood Pressure Control to Reduce Cardiovascular Disease Morbidity and Mortality: The Standardized Hypertension Treatment and Prevention Project.

    PubMed

    Patel, Pragna; Ordunez, Pedro; DiPette, Donald; Escobar, Maria Cristina; Hassell, Trevor; Wyss, Fernando; Hennis, Anselm; Asma, Samira; Angell, Sonia

    2016-12-01

    Hypertension is the leading remediable risk factor for cardiovascular disease, affecting more than 1 billion people worldwide, and is responsible for more than 10 million preventable deaths globally each year. While hypertension can be successfully diagnosed and treated, only one in seven persons with hypertension have controlled blood pressure. To meet the challenge of improving the control of hypertension, particularly in low- and middle-income countries, the authors developed the Standardized Hypertension Treatment and Prevention Project, which involves a health systems-strengthening approach that advocates for standardized hypertension management using evidence-based interventions. These interventions include the use of standardized treatment protocols, a core set of medications along with improved procurement mechanisms to increase the availability and affordability of these medications, registries for cohort monitoring and evaluation, patient empowerment, team-based care (task shifting), and community engagement. With political will and strong partnerships, this approach provides the groundwork to reduce high blood pressure and cardiovascular disease-related morbidity and mortality.

  5. Early Blood Pressure Lowering Does Not Reduce Growth of Intraventricular Hemorrhage following Acute Intracerebral Hemorrhage: Results of the INTERACT Studies

    PubMed Central

    Chan, Edward; Anderson, Craig S.; Wang, Xia; Arima, Hisatomi; Saxena, Anubhav; Moullaali, Tom J.; Delcourt, Candice; Wu, Guojun; Wang, Jinchao; Chen, Guofang; Lavados, Pablo M.; Stapf, Christian; Robinson, Thompson; Chalmers, John

    2016-01-01

    Background Intraventricular hemorrhage (IVH) extension is common following acute intracerebral hemorrhage (ICH) and is associated with poor prognosis. Aim To determine whether intensive blood pressure (BP)-lowering therapy reduces IVH growth. Methods Pooled analyses of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trials (INTERACT1 and INTERACT2) computed tomography (CT) substudies; multicenter, open, controlled, randomized trials of patients with acute spontaneous ICH and elevated systolic BP, randomly assigned to intensive (<140 mm Hg) or guideline-based (<180 mm Hg) BP management. Participants had blinded central analyses of baseline and 24-hour CT. Association of BP lowering to IVH growth was assessed in analysis of covariance. Results There was no significant difference in adjusted mean IVH growth following intensive (n = 228) compared to guideline-recommended (n = 228) BP treatment (1.6 versus 2.2 ml, respectively; p = 0.56). Adjusted mean IVH growth was nonsignificantly greater in patients with a mean achieved systolic BP ≥160 mm Hg over 24 h (3.94 ml; p trend = 0.26). Conclusions Early intensive BP-lowering treatment had no clear effect on IVH in acute ICH. PMID:27603933

  6. Effects of sound-field frequency modulation amplification on reducing teachers' sound pressure level in the classroom.

    PubMed

    Sapienza, C M; Crandell, C C; Curtis, B

    1999-09-01

    Voice problems are a frequent difficulty that teachers experience. Common complaints by teachers include vocal fatigue and hoarseness. One possible explanation for these symptoms is prolonged elevations in vocal loudness within the classroom. This investigation examined the effectiveness of sound-field frequency modulation (FM) amplification on reducing the sound pressure level (SPL) of the teacher's voice during classroom instruction. Specifically, SPL was examined during speech produced in a classroom lecture by 10 teachers with and without the use of sound-field amplification. Results indicated a significant 2.42-dB decrease in SPL with the use of sound-field FM amplification. These data support the use of sound-field amplification in the vocal hygiene regimen recommended to teachers by speech-language pathologists.

  7. 5-MCA-NAT does not act through NQO2 to reduce intraocular pressure in New-Zealand white rabbit.

    PubMed

    Alarma-Estrany, Pilar; Crooke, Almudena; Pintor, Jesús

    2009-09-01

    Solid data support the idea that the MT(3) melatonin binding site is an enzyme, quinone reductase 2 (NQO2), rather than a membrane melatonin receptor. However, the melatonin analogue, 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT), reduces intraocular pressure (IOP) via MT(3) melatonin receptors. Therefore, the aim of this work was to test whether the melatonin binding site, MT(3), is indeed the enzyme NQO2 in New Zealand rabbit eyes. To investigate this, the action of several substrates and inhibitors for NQO2 was compared to 5-MCA-NAT in their ability to modify IOP. Also, the effect of 5-MCA-NAT on IOP produced after NQO2 silencing by means of a siRNA was determinated. Altogether, the results led us to conclude that the in vivo effect of the MT(3) ligand 5-MCA-NAT on IOP is not mediated by the enzyme NQO2, suggesting the existence of another melatonin receptor.

  8. Flexible reduced graphene oxide supercapacitor fabricated using a nitrogen dc-pulse atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Yang, Cheng-Han; Kuok, Fei-Hong; Liao, Chen-Yu; Wan, Ting-Hao; Chen, Chieh-Wen; Hsu, Cheng-Che; Cheng, I.-Chun; Chen, Jian-Zhang

    2017-02-01

    We use a nitrogen dc-pulse atmospheric-pressure plasma jet to fabricate a flexible reduced graphene oxide (rGO) supercapacitor with polyvinyl alcohol (PVA)/sulfuric acid (H2SO4) gel electrolyte. An areal capacitance of 47.03 mF · cm‑2 (evaluated using cyclic voltammetry (CV) under a potential scan rate of 2 mV · s‑1) is achieved. The supercapacitor can be operated without apparent degradation under bending with a bending radius of 0.55 cm. After a 1000 cycle CV stability test, the capacitance retention rate is 100% when flat and is 98.6% under bending (bending radius  =  0.55 cm), indicating promising stability of the APPJ-processed flexible supercapacitor.

  9. Reduced defense of central blood volume during acute lower body negative pressure-induced hypovolemic circulatory stress in aging women.

    PubMed

    Lindenberger, Marcus; Länne, Toste

    2012-06-01

    Elderly humans are more vulnerable to trauma and hemorrhage than young and elderly men and respond with decreased defense of central blood volume during acute experimental hypovolemia induced by lower body negative pressure (LBNP). However, these defense mechanisms have not been evaluated in elderly women. The aim of this study was to determine the effectiveness of compensatory responses to defend central blood volume during experimental hypovolemia in elderly and young women. Cardiovascular responses in 34 women, 12 elderly (66 ± 1 years) and 22 young women (23 ± 0.4 years), were studied during experimental hypovolemia induced by LBNP of 11 to 44 mmHg. Air plethysmography was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as net capillary fluid transfer from tissue to blood in the arm. Lower body negative pressure seemed to create comparable hypovolemia measured as total calf volume increase in elderly and young women. Heart rate increased less in elderly women (LBNP of 44 mmHg: 20 ± 2 vs. 37 ± 4%; P < 0.01) but with similar (%) increase in forearm vascular resistance. Mobilization of capacitance blood from the peripheral circulation was both slower and decreased by ∼60% in elderly women (P < 0.001), and net capillary fluid absorption from surrounding tissues was reduced by ∼40% (P < 0.01, LBNP of 44 mmHg). Elderly women responded with less increase in heart rate but with equal forearm vascular resistance (%) response during LBNP. Furthermore, the compensatory capacitance response was both slower and substantially decreased, and net capillary fluid absorption considerably reduced, collectively indicating less efficiency to defend central blood volume in elderly than in young women.

  10. An experimental study of evaporation waves in a superheated liquid

    NASA Astrophysics Data System (ADS)

    Hill, Larry G.

    1990-01-01

    Evaporation waves in superheated liquids are studied using a rapid-depressurization facility consisting of a vertical glass test cell situated beneath a large, low-pressure reservoir. The objective of this study is to learn more about the physical mechanisms of explosive boiling (of which an evaporation wave is a specific example), as well as properties of the flow it produces.The test cell is initially sealed from the reservoir by a foil diaphragm, and is partially filled with a volatile liquid (Refrigerant 12 or 114). An experiment is initiated by rupturing the diaphragm via a pneumatically driven cutter. The instrumentation consists of fast-response pressure measurements, high-speed motion pictures, and spark-illuminated still photographs. The liquid temperature is typically 20°C; the liquid superheat is controlled by setting the reservoir pressure to values between vacuum and 1 atm. The pressures subsequent to depressurization are very much less than the critical pressure, and the initial temperatures are sufficiently low that, although the test liquid is highly superheated, the superheat limit is not approached. Evaporation waves in which bubble nucleation within the liquid column is suppressed entirely are considered almost exclusively.When the diaphragm is ruptured, the liquid pressure drops to virtually the reservoir value within a few milliseconds. Provided that the liquid superheat so obtained is sufficiently high, the free surface then erupts in a process known as explosive boiling, which is characterized by violent, fine-scale fragmentation of the superheated liquid and extremely rapid evaporation. The explosive boiling process proceeds as a "wavefront" into the liquid column, producing a highspeed, two-phase flow that travels upward into the low-pressure reservoir, emptying the test cell in a few hundred milliseconds. The speed of the wavefront varies between 0.2 and 0.6 m/s, depending on run conditions; the corresponding two-phase flow varies between

  11. 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.

  12. 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.

  13. Heat transfer at the nanoscale: evaporation of nanodroplets.

    PubMed

    Hołyst, Robert; Litniewski, Marek

    2008-02-08

    We demonstrate using molecular dynamics simulations of the Lennard-Jones fluid that the evaporation process of nanodroplets at the nanoscale is limited by the heat transfer. The temperature is continuous at the liquid-vapor interface if the liquid/vapor density ratio is small (of the order of 10) and discontinuous otherwise. The temperature in the vapor has a scaling form T(r,t)=T[r/R(t)], where R(t) is the radius of an evaporating droplet at time t and r is the distance from its center. Mechanical equilibrium establishes very quickly, and the pressure difference obeys the Laplace law during evaporation.

  14. Diffusion dominated evaporation in multicomponent lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Hessling, Dennis; Xie, Qingguang; Harting, Jens

    2017-02-01

    We present a diffusion dominated evaporation model using the popular pseudopotential multicomponent lattice Boltzmann method introduced by Shan and Chen. With an analytical computation of the diffusion coefficients, we demonstrate that Fick's law is obeyed. We then validate the applicability of our model by demonstrating the agreement of the time evolution of the interface position of an evaporating planar film to the analytical prediction. Furthermore, we study the evaporation of a freely floating droplet and confirm that the effect of Laplace pressure is significant for predicting the time evolution of small droplet radii.

  15. 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.

  16. Palmitoylethanolamide treatment reduces blood pressure in spontaneously hypertensive rats: involvement of cytochrome p450-derived eicosanoids and renin angiotensin system.

    PubMed

    Mattace Raso, Giuseppina; Pirozzi, Claudio; d'Emmanuele di Villa Bianca, Roberta; Simeoli, Raffaele; Santoro, Anna; Lama, Adriano; Di Guida, Francesca; Russo, Roberto; De Caro, Carmen; Sorrentino, Raffaella; Calignano, Antonio; Meli, Rosaria

    2015-01-01

    Palmitoylethanolamide (PEA), a peroxisome proliferator-activated receptor-α agonist, has been demonstrated to reduce blood pressure and kidney damage secondary to hypertension in spontaneously hypertensive rat (SHR). Currently, no information is available concerning the putative effect of PEA on modulating vascular tone. Here, we investigate the mechanisms underpinning PEA blood pressure lowering effect, exploring the contribution of epoxyeicosatrienoic acids, CYP-dependent arachidonic acid metabolites, as endothelium-derived hyperpolarizing factors (EDHF), and renin angiotensin system (RAS) modulation. To achieve this aim SHR and Wistar-Kyoto rats were treated with PEA (30 mg/kg/day) for five weeks. Functional evaluations on mesenteric bed were performed to analyze EDHF-mediated vasodilation. Moreover, mesenteric bed and carotid were harvested to measure CYP2C23 and CYP2J2, the key isoenzymes in the formation of epoxyeicosatrienoic acids, and the soluble epoxide hydrolase, which is responsible for their degradation in the corresponding diols. Effect of PEA on RAS modulation was investigated by analyzing angiotensin converting enzyme and angiotensin receptor 1 expression. Here, we showed that EDHF-mediated dilation in response to acetylcholine was increased in mesenteric beds of PEA-treated SHR. Western blot analysis revealed that the increase in CYP2C23 and CYP2J2 observed in SHR was significantly attenuated in mesenteric beds of PEA-treated SHR, but unchanged in the carotids. Interestingly, in both vascular tissues, PEA significantly decreased the soluble epoxide hydrolase protein level, accompanied by a reduced serum concentration of its metabolite 14-15 dihydroxyeicosatrienoic acid, implying a reduction in epoxyeicosatrienoic acid hydrolisis. Moreover, PEA treatment down-regulated angiotensin receptor 1 and angiotensin converting enzyme expression, indicating a reduction in angiotensin II-mediated effects. Consistently, a damping of the activation of

  17. Palmitoylethanolamide Treatment Reduces Blood Pressure in Spontaneously Hypertensive Rats: Involvement of Cytochrome P450-Derived Eicosanoids and Renin Angiotensin System

    PubMed Central

    Mattace Raso, Giuseppina; Pirozzi, Claudio; d'Emmanuele di Villa Bianca, Roberta; Simeoli, Raffaele; Santoro, Anna; Lama, Adriano; Di Guida, Francesca; Russo, Roberto; De Caro, Carmen; Sorrentino, Raffaella; Calignano, Antonio; Meli, Rosaria

    2015-01-01

    Palmitoylethanolamide (PEA), a peroxisome proliferator-activated receptor-α agonist, has been demonstrated to reduce blood pressure and kidney damage secondary to hypertension in spontaneously hypertensive rat (SHR). Currently, no information is available concerning the putative effect of PEA on modulating vascular tone. Here, we investigate the mechanisms underpinning PEA blood pressure lowering effect, exploring the contribution of epoxyeicosatrienoic acids, CYP-dependent arachidonic acid metabolites, as endothelium-derived hyperpolarizing factors (EDHF), and renin angiotensin system (RAS) modulation. To achieve this aim SHR and Wistar-Kyoto rats were treated with PEA (30 mg/kg/day) for five weeks. Functional evaluations on mesenteric bed were performed to analyze EDHF-mediated vasodilation. Moreover, mesenteric bed and carotid were harvested to measure CYP2C23 and CYP2J2, the key isoenzymes in the formation of epoxyeicosatrienoic acids, and the soluble epoxide hydrolase, which is responsible for their degradation in the corresponding diols. Effect of PEA on RAS modulation was investigated by analyzing angiotensin converting enzyme and angiotensin receptor 1 expression. Here, we showed that EDHF-mediated dilation in response to acetylcholine was increased in mesenteric beds of PEA-treated SHR. Western blot analysis revealed that the increase in CYP2C23 and CYP2J2 observed in SHR was significantly attenuated in mesenteric beds of PEA-treated SHR, but unchanged in the carotids. Interestingly, in both vascular tissues, PEA significantly decreased the soluble epoxide hydrolase protein level, accompanied by a reduced serum concentration of its metabolite 14-15 dihydroxyeicosatrienoic acid, implying a reduction in epoxyeicosatrienoic acid hydrolisis. Moreover, PEA treatment down-regulated angiotensin receptor 1 and angiotensin converting enzyme expression, indicating a reduction in angiotensin II-mediated effects. Consistently, a damping of the activation of

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Immediate Postoperative Intraocular Pressure Adjustment Reduces Risk of Cystoid Macular Edema after Uncomplicated Micro Incision Coaxial Phacoemulsification Cataract Surgery

    PubMed Central

    Jarstad, Allison R.; Chung, Gary W.; Tester, Robert A.; Day, Linda E.

    2017-01-01

    Purpose To determine the accuracy of visual estimation of immediate postoperative intraocular pressure (IOP) following microincision cataract surgery (MICS) and the effect of immediate postoperative IOP adjustment on prevention of cystoid macular edema (CME). Setting Ambulatory surgical center. Methods Prospective, randomized analysis of 170 eyes in 135 patients with MICS, performed in a Medicare approved outpatient ambulatory surgery center. Surgical parameters included a keratome incision of 1.5 mm to 2.8 mm, topical anesthetic, case completion IOP estimation by palpation and patient visualization of light, and IOP adjustment before exiting the operating theater. IOPs were classified into three groups: low (<16 mmHg), normal (16 to 21 mmHg), and elevated (>21 to 30 mmHg). IOP measurements were repeated 1 day after surgery. Optical coherence tomography (Stratus OCT, Zeiss) was measured at 2 weeks. An increase in foveal thickness greater than 15 µm was used to indicate CME. Statistical analysis was performed using one- and two-tailed Student's t-tests. Results Mean minimal foveal thickness averaged 207.15 µm in the low pressure group, 205.14 µm in the normal IOP group, and 210.48 µm in the elevated IOP group 2 weeks following surgery. CME occurred in 14 of 170 eyes (8.2%) at 2 weeks (low IOP, 35.7%; normal IOP, 14.2%; elevated IOP, 50.0%). Change in IOP from the operating theater to 1 day after surgery was within +/−5 mmHg in 54 eyes (31.7%), elevated by 6 to 15 mmHg in 22 eyes (12.9%), and elevated more than 15 mmHg in four eyes (2.3%). IOP was reduced by 6 mmHg to 15 mmHg in 39 eyes (22.9%) and reduced by more than 15 mmHg in nine eyes (5.3%). Conclusions Immediate postoperative adjustment of IOP may prevent CME in MICS. Physicians can improve their ability to estimate postoperative IOP with experience in tonometry to verify immediate postoperative IOP. There are patient safety and economic benefits to immediate IOP adjustment in the operating theater

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Evidence for the role of isometric exercise training in reducing blood pressure: potential mechanisms and future directions.

    PubMed

    Millar, Philip J; McGowan, Cheri L; Cornelissen, Véronique A; Araujo, Claudio G; Swaine, Ian L

    2014-03-01

    Hypertension, or the chronic elevation in resting arterial blood pressure (BP), is a significant risk factor for cardiovascular disease and estimated to affect ~1 billion adults worldwide. The goals of treatment are to lower BP through lifestyle modifications (smoking cessation, weight loss, exercise training, healthy eating and reduced sodium intake), and if not solely effective, the addition of antihypertensive medications. In particular, increased physical exercise and decreased sedentarism are important strategies in the prevention and management of hypertension. Current guidelines recommend both aerobic and dynamic resistance exercise training modalities to reduce BP. Mounting prospective evidence suggests that isometric exercise training in normotensive and hypertensive (medicated and non-medicated) cohorts of young and old participants may produce similar, if not greater, reductions in BP, with meta-analyses reporting mean reductions of between 10 and 13 mmHg systolic, and 6 and 8 mmHg diastolic. Isometric exercise training protocols typically consist of four sets of 2-min handgrip or leg contractions sustained at 20-50 % of maximal voluntary contraction, with each set separated by a rest period of 1-4 min. Training is usually completed three to five times per week for 4-10 weeks. Although the mechanisms responsible for these adaptations remain to be fully clarified, improvements in conduit and resistance vessel endothelium-dependent dilation, oxidative stress, and autonomic regulation of heart rate and BP have been reported. The clinical significance of isometric exercise training, as a time-efficient and effective training modality to reduce BP, warrants further study. This evidence-based review aims to summarize the current state of knowledge regarding the effects of isometric exercise training on resting BP.

  9. Evaporating metal nanocrystal arrays.

    PubMed

    Zhang, Xue; Joy, James C; Zhao, Chenwei; Kim, Jin Ho; Fernandes, Gustavo; Xu, J M; Valles, James M

    2017-03-10

    Anodic aluminum oxide (AAO) substrates with a self-ordered triangular array of nanopores provide the means to fabricate multiple forms of nano materials, such as nanowires and nanoparticles. This study focuses on nanostructures that emerge in thin films of metals thermally evaporated onto the surface of AAO. Previous work showed that films of different evaporated metals assume dramatically different structures, e.g. an ordered triangular array of nearly monodisperse nanoparticles forms for lead (Pb) while a polycrystalline nanohoneycomb structure forms for silver (Ag). Here, we present investigations of the effects of substrate temperature and deposition angle that reveal the processes controlling the nano particle array formation. Our findings indicate that arrays form provided the grain nucleation density exceeds the pore density and the atomic mobility is high enough to promote grain coalescence. They introduce a method for producing films with anisotropic grain array structure. The results provide insight into the influence of substrate nano-morphology on thin film growth energetics and kinetics that can be harnessed for creating films with other novel nano-structures.

  10. Evaporating metal nanocrystal arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Joy, James C.; Zhao, Chenwei; Kim, Jin Ho; Fernandes, Gustavo; Xu, J. M.; Valles, James M., Jr.

    2017-03-01

    Anodic aluminum oxide (AAO) substrates with a self-ordered triangular array of nanopores provide the means to fabricate multiple forms of nano materials, such as nanowires and nanoparticles. This study focuses on nanostructures that emerge in thin films of metals thermally evaporated onto the surface of AAO. Previous work showed that films of different evaporated metals assume dramatically different structures, e.g. an ordered triangular array of nearly monodisperse nanoparticles forms for lead (Pb) while a polycrystalline nanohoneycomb structure forms for silver (Ag). Here, we present investigations of the effects of substrate temperature and deposition angle that reveal the processes controlling the nano particle array formation. Our findings indicate that arrays form provided the grain nucleation density exceeds the pore density and the atomic mobility is high enough to promote grain coalescence. They introduce a method for producing films with anisotropic grain array structure. The results provide insight into the influence of substrate nano-morphology on thin film growth energetics and kinetics that can be harnessed for creating films with other novel nano-structures.

  11. 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

  12. Placental growth factor reduces blood pressure in a uteroplacental ischemia model of preeclampsia in non-human primates

    PubMed Central

    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

    2016-01-01

    An imbalance in the angiogenesis axis during pregnancy manifests as clinical preeclampsia due to endothelial dysfunction. Circulating sFLT-1 (soluble fms-like tyrosine kinase 1) increases and PlGF (placental growth factor) reduces prior to 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 non-human primate (Papio hamadryas) by uterine artery ligation at 136 days gestation (of an 182 day pregnancy). Two weeks after uteroplacental ischemia (UPI), rhPlGF (rhPlGF, n=3) or normal saline (control, n=4) was administered by subcutaneous injection (100μg/kg/day) for 5 days. Blood pressure (BP) was monitored by intra-arterial radiotelemetry, sFLT-1 and PlGF by ELISA. UPI resulted in experimental preeclampsia evidenced by increased BP, proteinuria and endotheliosis on renal biopsy and elevated sFLT-1. PlGF significantly reduced after UPI. rhPlGF reduced SBP in the treated group (-5.2mmHg+0.8mmHg;from 132.6+6.6mmHg to 124.1+7.6mmHg) compared to an increase in SBP in controls (6.5mmHg+3mmHg; from 131.3+1.5mmHg to 138.6+1.5mmHg). Proteinuria reduced in the treated group (-72.7±55.7mg/mmol) but increased in the control group. Circulating sFLT-1 was not affected by the administration of PlGF, however a reduction in placental sFLT-1 mRNA expression was demonstrated. There was no significant difference in 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

  13. 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.

  14. 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

  15. Local cooling reduces skin ischemia under surface pressure in rats: an assessment by wavelet analysis of laser Doppler blood flow oscillations.

    PubMed

    Jan, Yih-Kuen; Lee, Bernard; Liao, Fuyuan; Foreman, Robert D

    2012-10-01

    The objectives of this study were to investigate the effects of local cooling on skin blood flow response to prolonged surface pressure and to identify associated physiological controls mediating these responses using the wavelet analysis of blood flow oscillations in rats. Twelve Sprague-Dawley rats were randomly assigned to three protocols, including pressure with local cooling (Δt = -10 °C), pressure with local heating (Δt = 10 °C) and pressure without temperature changes. Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The 3 h loading period was divided into non-overlapping 30 min epochs for the analysis of the changes of skin blood flow oscillations using wavelet spectral analysis. The wavelet amplitudes and powers of three frequencies (metabolic, neurogenic and myogenic) of skin blood flow oscillations were calculated. The results showed that after an initial loading period of 30 min, skin blood flow continually decreased under the conditions of pressure with heating and of pressure without temperature changes, but maintained stable under the condition of pressure with cooling. Wavelet analysis revealed that stable skin blood flow under pressure with cooling was attributed to changes in the metabolic and myogenic frequencies. This study demonstrates that local cooling may be useful for reducing ischemia of weight-bearing soft tissues that prevents pressure ulcers.

  16. 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.

  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.

  18. 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.

  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. 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.

  1. Short-term Regular Aerobic Exercise Reduces Oxidative Stress Produced by Acute High Intraluminal Pressure in the Adipose Microvasculature.

    PubMed

    Robinson, Austin T; Fancher, Ibra S; Sudhahar, Varadarajan; Bian, Jing Tan; Cook, Marc; Mahmoud, Abeer M; Ali, Mohamed; Ushio-Fukai, Masuko; Brown, Michael D; Fukai, Tohru; Phillips, Shane A

    2017-02-24

    High blood pressure has been shown to elicit impaired dilation in the vasculature. The purpose of this investigation was to elucidate the mechanisms through which high pressure may elicit vascular dysfunction, and determine the mechanisms through which regular aerobic exercise protects arteries against high pressure.

  2. Visual study of propagation of self-sustained evaporation front within the thickness of a thermal liquid layer

    NASA Astrophysics Data System (ADS)

    Zhukov, V. E.; Moiseev, M. I.; Kuznetsov, D. V.

    2016-10-01

    In the range of low reduced pressures, the development of self-sustained evaporation front along the heat-releasing surface at non-stationary heat release is an important factor that determines possible transition to film boiling at heat fluxes, significantly lower than the critical heat fluxes at stationary heat release. This paper presents the experimental results on the scale of a leading part of the interface of self-sustained evaporation front at stepped heat release. The scale of the leading part of the interface of the evaporation front is compared with the thermal layer thickness, registered using the shadow method of visualization at high-speed video shooting with up to 25,000 frames per second. Experiments were carried out in Freon R21 under the conditions of free convection at relative pressures of 0.032 - 0.068. It is shown that self-sustained evaporation front spreads along the heated wall within the thickness of a liquid layer, superheated relative to the saturation temperature. Dependence of the front velocity on wall superheating relative to the saturation temperature does not change with significant subcooling to the temperature of liquid saturation in the volume.

  3. 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.

  4. 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

  5. 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

  6. Excessive zinc intake increases systemic blood pressure and reduces renal blood flow via kidney angiotensin II in rats.

    PubMed

    Kasai, Miyoko; Miyazaki, Takashi; Takenaka, Tsuneo; Yanagisawa, Hiroyuki; Suzuki, Hiromichi

    2012-12-01

    This study investigated the effects of excess zinc intake on the mean arterial pressure (MAP), renal blood flow (RBF), inulin clearance (IC), serum zinc level, serum angiotensin-converting enzyme (ACE) activity, and kidney angiotensin II (AT II) levels in rats. Experiments were performed on male Sprague-Dawley rats maintained for 4 weeks on a diet containing either 5 mg/100 g (control group), 50 mg/100 g (Zn50 group), or 200 mg/100 g (Zn200 group) zinc carbonate. Serum zinc levels significantly increased to 126.5 % in the Zn50 group and 198.1 % in the Zn200 group compared with controls. MAP significantly increased to 107.8 % in the Zn50 group and 114.5 % in the Zn200 group again compared with controls. Although the difference in serum ACE activity was independent of the serum zinc levels, the kidney AT II levels increased significantly to 137.2 % in the Zn50 group and 174.4 % in the Zn200 group compared with the controls. RBF was decreased significantly to 74.4 % in the Zn50 group and 69.7 % in the Zn200 group compared with the controls. IC values were significantly decreased to 69.6 % in the Zn50 group and 52.7 % in the Zn200 group as compared with control levels. Combined together, these results show that excessive Zn intake reduced IC and RBF and increased MAP and kidney AT II levels, suggesting that excessive Zn intake reduces renal function.

  7. 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

  8. Selectively engaging β-arrestins at the angiotensin II type 1 receptor reduces blood pressure and increases cardiac performance.

    PubMed

    Violin, Jonathan D; DeWire, Scott M; Yamashita, Dennis; Rominger, David H; Nguyen, Lisa; Schiller, Kevin; Whalen, Erin J; Gowen, Maxine; Lark, Michael W

    2010-12-01

    Biased G protein-coupled receptor ligands engage subsets of the receptor signals normally stimulated by unbiased agonists. However, it is unclear whether ligand bias can elicit differentiated pharmacology in vivo. Here, we describe the discovery of a potent, selective β-arrestin biased ligand of the angiotensin II type 1 receptor. TRV120027 (Sar-Arg-Val-Tyr-Ile-His-Pro-D-Ala-OH) competitively antagonizes angiotensin II-stimulated G protein signaling, but stimulates β-arrestin recruitment and activates several kinase pathways, including p42/44 mitogen-activated protein kinase, Src, and endothelial nitric-oxide synthase phosphorylation via β-arrestin coupling. Consistent with β-arrestin efficacy, and unlike unbiased antagonists, TRV120027 increased cardiomyocyte contractility in vitro. In rats, TRV120027 reduced mean arterial pressure, as did the unbiased antagonists losartan and telmisartan. However, unlike the unbiased antagonists, which decreased cardiac performance, TRV120027 increased cardiac performance and preserved cardiac stroke volume. These striking differences in vivo between unbiased and β-arrestin biased ligands validate the use of biased ligands to selectively target specific receptor functions in drug discovery.

  9. Reduced-Pressure Chemical Vapor Deposition Growth of Isolated Ge Crystals and Suspended Layers on Micrometric Si Pillars.

    PubMed

    Skibitzki, Oliver; Capellini, Giovanni; Yamamoto, Yuji; Zaumseil, Peter; Schubert, Markus Andreas; Schroeder, Thomas; Ballabio, Andrea; Bergamaschini, Roberto; Salvalaglio, Marco; Miglio, Leo; Montalenti, Francesco

    2016-10-05

    In this work, we demonstrate the growth of Ge crystals and suspended continuous layers on Si(001) substrates deeply patterned in high aspect-ratio pillars. The material deposition was carried out in a commercial reduced-pressure chemical vapor deposition reactor, thus extending the "vertical-heteroepitaxy" technique developed by using the peculiar low-energy plasma-enhanced chemical vapor deposition reactor, to widely available epitaxial tools. The growth process was thoroughly analyzed, from the formation of small initial seeds to the final coalescence into a continuous suspended layer, by means of scanning and transmission electron microscopy, X-ray diffraction, and μ-Raman spectroscopy. The preoxidation of the Si pillar sidewalls and the addition of hydrochloric gas in the reactants proved to be key to achieve highly selective Ge growth on the pillars top only, which, in turn, is needed to promote the formation of a continuous Ge layer. Thanks to continuum growth models, we were able to single out the different roles played by thermodynamics and kinetics in the deposition dynamics. We believe that our findings will open the way to the low-cost realization of tens of micrometers thick heteroepitaxial layer (e.g., Ge, SiC, and GaAs) on Si having high crystal quality.

  10. Rates of evaporation from swimming pools in active use

    SciTech Connect

    Smith, C.C.; Loef, G.O.G.; Jones, R.W.

    1998-10-01

    The rates of water evaporation from indoor and outdoor swimming pools in active use have been measured and compared with evaporation rates from unoccupied pools and with values calculated by the equation W = (95 + 0.425 v) (pw-pa)Y, where W is evaporation rate, lb/h ft{sup 2}; v is air velocity at water surface, ft/min.; pw is saturation vapor pressure at water temperature, in. Hg; pa is saturation vapor pressure at air dewpoint, in. Hg; and Y is latent heat at pool temperature, Btu/lb. In undisturbed pools, evaporation rates were measured and found to be 74% of the rates obtained by use of the equation. Rates of evaporation from pools in active use increase with the number of swimmers, rising 40--70% above the rates from a quiet water surface. Measurements of evaporation from a pool in use by 15--20 swimmers per 1,000 ft{sup 2} were found to average 26% higher than the rate calculated by the equation.

  11. Self-measurement of blood pressure at home reduces the need for antihypertensive drugs: a randomized, controlled trial.

    PubMed

    Verberk, Willem J; Kroon, Abraham A; Lenders, Jacques W M; Kessels, Alfons G H; van Montfrans, Gert A; Smit, Andries J; van der Kuy, Paul-Hugo M; Nelemans, Patricia J; Rennenberg, Roger J M W; Grobbee, Diederick E; Beltman, Frank W; Joore, Manuela A; Brunenberg, Daniëlle E M; Dirksen, Carmen; Thien, Theo; de Leeuw, Peter W

    2007-12-01

    It is still uncertain whether one can safely base treatment decisions on self-measurement of blood pressure. In the present study, we investigated whether antihypertensive treatment based on self-measurement of blood pressure leads to the use of less medication without the loss of blood pressure control. We randomly assigned 430 hypertensive patients to receive treatment either on the basis of self-measured pressures (n=216) or office pressures (OPs; n=214). During 1-year follow-up, blood pressure was measured by office measurement (10 visits), ambulatory monitoring (start and end), and self-measurement (8 times, self-pressure group only). In addition, drug use, associated costs, and degree of target organ damage (echocardiography and microalbuminuria) were assessed. The self-pressure group used less medication than the OP group (1.47 versus 2.48 drug steps; P<0.001) with lower costs ($3222 versus $4420 per 100 patients per month; P<0.001) but without significant differences in systolic and diastolic OP values (1.6/1.0 mm Hg; P=0.25/0.20), in changes in left ventricular mass index (-6.5 g/m(2) versus -5.6 g/m(2); P=0.72), or in median urinary microalbumin concentration (-1.7 versus -1.5 mg per 24 hours; P=0.87). Nevertheless, 24-hour ambulatory blood pressure values at the end of the trial were higher in the self-pressure than in the OP group: 125.9 versus 123.8 mm Hg (P<0.05) for systolic and 77.2 versus 76.1 mm Hg (P<0.05) for diastolic blood pressure. These data show that self-measurement leads to less medication use than office blood pressure measurement without leading to significant differences in OP values or target organ damage. Ambulatory values, however, remain slightly elevated for the self-pressure group.

  12. 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.

  13. 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.

  14. [Sildenafil reduces pressure and pulmonary resistance and increases susceptibility of pulmonary arteries to nitric oxide in primary pulmonary arterial hypertension].

    PubMed

    Wodniecki, Jan; Jacheć, Wojciech; Poloński, Lech; Tomasik, Andrzej Robert; Wojciechowska, Celina; Foremny, Ala

    2005-01-01

    Primary pulmonary arterial hypertension (PPH) is a rare disease of undetermined origin and fatal prognosis. A better prognosis is associated with at least 20% reduction of either pulmonary artery pressure or pulmonary vascular resistance ("responders") in acute vasodilatory trials. Prostacycline (PGI2) or nitric oxide (NO) administration promises valuable results. NO is one of the most powerful vasodilating agents, endogenously produced by endothelial cells. It migrates from these cells to smooth muscle cells and stimulates production of cGMP, that induces smooth muscle relaxation. cGMP is hydrolyzed by 5-phopshodiesterase (PDE-5). Several papers documenting hypotensive effect in pulmonary circulation of specific PDE5 inhibitor--sildenafil (Viagra--Pfizer) have been published recently. We present a case report of a 26 year old female patient with PPH--"nonresponder" in a trial with NO--and NO responder after sildenafil administration. Initial values were: mean pulmonary artery pressure (mPAP) was 58 mmHg, pulmonary vascular resistance was 10.9 Wood's units. mPAP and PVR during NO inhalation (40 ppm) decrease from 62 to 54 mmHg and from 11.4 to 10.3 Wood's units, respectively. Measurements performed 60 minutes after 50 mg of sildenafil orally disclosed a 19% reduction of mPAP and 21% reduction of PVR. NO inhalation caused further decrease of both parameters: mPAP was decreased for additional 28% and PVR for additional 36% in comparison to initial results. Neither peripheral hypotension nor other side effects were observed. A month-long administration of sildenafil in a dose 2 x 25 mg daily reduced mPAP and PVR to values reported for the acute trial. Physical capability improved also. It was assessed as increased distance in a six-minute-walk test (280 vs. 400 m in the first week of treatment, and 330 m in a fourth week of treatment). Echocardiography showed moderate decrease of right ventricle and right atrium diameters, along with decrease of the degree of relative

  15. 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

  16. 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.

  17. Molecular Mechanism of Water Evaporation.

    PubMed

    Nagata, Yuki; Usui, Kota; Bonn, Mischa

    2015-12-04

    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.

  18. Evaporation in relation to CO 2 concentration: Analysis of mass transfer coefficient

    NASA Astrophysics Data System (ADS)

    Ojha, C. S. P.; Yasuda, Hiroshi; Rao, Surampalli; Abd Elbasit, Mohamed A. M.; Kumar, Manoj

    2011-11-01

    In this study, the potential of mass transfer approach in estimating evaporation changes under different CO 2 levels are evaluated using data from controlled chamber experiments in which radiation and wind velocity were kept constant and temperature and relative humidity profiles were varied in different patterns along with CO 2 concentration. Currently, FAO procedure lists three approaches to compute air vapour pressure based on temperature and relative humidity profiles. In this study, the impact of using different procedures of estimating air vapour pressure is examined to assess the use of mass transfer approach for estimating evaporation. To achieve this, a part of the data is used to calibrate mass transfer coefficient which is subsequently used to project evaporation for future states. Accordingly, strategies are ranked for their potential in estimating evaporation. The effect of evaporation rate is compared at 400 ppm and 600 ppm CO 2 level. It has been observed that the evaporation rate is more pronounced at higher CO 2 level.

  19. 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.

  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. Two stage indirect evaporative cooling system

    SciTech Connect

    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.

  2. Evaporation-driven instability of the precorneal tear film.

    PubMed

    Peng, Cheng-Chun; Cerretani, Colin; Braun, Richard J; Radke, C J

    2014-04-01

    Tear-film instability is widely believed to be a signature of eye health. When an interblink is prolonged, randomly distributed ruptures occur in the tear film. "Black spots" and/or "black streaks" appear in 15 to 40 s for normal individuals. For people who suffer from dry eye, tear-film breakup time (BUT) is typically less than a few seconds. To date, however, there is no satisfactory quantitative explanation for the origin of tear rupture. Recently, it was proposed that tear-film breakup is related to locally high evaporative thinning. A spatial variation in the thickness of the tear-film lipid layer (TFLL) may lead to locally elevated evaporation and subsequent tear-film breakup. We examine the local-evaporation-driven tear-film-rupture hypothesis in a one-dimensional (1-D) model for the evolution of a thin aqueous tear film overriding the cornea subject to locally elevated evaporation at its anterior surface and osmotic water influx at its posterior surface. Evaporation rate depends on mass transfer both through the coating lipid layer and through ambient air. We establish that evaporation-driven tear-film breakup can occur under normal conditions but only for higher aqueous evaporation rates. Predicted roles of environmental conditions, such as wind speed and relative humidity, on tear-film stability agree with clinical observations. More importantly, locally elevated evaporation leads to hyperosmolar spots in the tear film and, hence, vulnerability to epithelial irritation. In addition to evaporation rate, tear-film instability depends on the strength of healing flow from the neighboring region outside the breakup region, which is determined by the surface tension at the tear-film surface and by the repulsive thin-film disjoining pressure. This study provides a physically consistent and quantitative explanation for the formation of black streaks and spots in the human tear film during an interblink.

  3. A single session of low-volume high-intensity interval exercise reduces ambulatory blood pressure in normotensive males.

    PubMed

    Dantas, Teresa C B; Farias Júnior, Luiz F; Frazão, Danniel T; Silva, Paulo H M; Sousa Junior, Altieres E; Costa, Ingrid B B; Ritti-Dias, Raphael M; Forjaz, Cláudia L M; Duhamel, Todd A; Costa, Eduardo C

    2016-10-17

    The magnitude and duration of post-exercise hypotension (PEH) may provide valuable information on the efficacy of an exercise approach to blood pressure (BP) control. We investigated the acute effect of a time-efficient high-intensity interval exercise (HIIE) on ambulatory BP. Twenty-one normotensive males (23.6 ± 3.6 years) completed two experimental sessions in a randomized order: 1) control (no exercise); and 2) low-volume HIIE: 10 x 1 min at 100% of maximal treadmill velocity interspersed with 1 min of recovery. After each experimental session, an ambulatory BP monitoring was initiated. Paired sample t-test was used to compare BP averages for awake, asleep and 20h periods between the control and the low-volume HIIE sessions. A two-way repeated measures ANOVA was used to analyze hourly BP following both experimental sessions. BP averages during the awake (systolic: 118 ± 6 vs. 122 ± 6 mmHg; diastolic: 65 ± 7 vs. 67 ± 7 mmHg) and 20h (systolic: 115 ± 7 vs. 118 ± 6 mmHg; diastolic: 62 ± 7 vs. 64 ± 7 mmHg) periods were lower following the low-volume HIIE compared to the control (p<0.05). Systolic and diastolic PEH presented medium (Cohen's d = 0.50-0.67) and small (Cohen's d = 0.29) effect sizes, respectively. Systolic PEH occurred in a greater magnitude during the first five hours (3-5 mmHg). No changes were found in asleep BP (p>0.05). In conclusion, a single session of low-volume HIIE reduced ambulatory BP in normotensive males. PEH occurred mainly in systolic BP during the first five hours post-exercise.

  4. 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

  5. Lake Evaporation: a Model Study

    NASA Astrophysics Data System (ADS)

    Amayreh, Jumah Ahmad

    1995-01-01

    Reliable evaporation data are an essential requirement in any water and/or energy budget studies. This includes operation and management of both urban and agricultural water resources. Evaporation from large, open water surfaces such as lakes and reservoirs may influence many agricultural and irrigation decisions. In this study evaporation from Bear Lake in the states of Idaho and Utah was measured using advanced research instruments (Bowen Ratio and Eddy Correlation). Actual over-lake evaporation and weather data measurements were used to understand the mechanism of evaporation in the lake, determine lake-related parameters (such as roughness lengths, heat storage, net radiation, etc.), and examine and evaluate existing lake evaporation methods. This enabled the development of a modified and flexible model incorporating the tested methods for hourly and daily best estimates of lake evaporation using nearby simple land-based weather data and, if available, remotely sensed data. Average evaporation from Bear Lake was about 2 mm/day during the summer season (March-October) of this two-year (1993-1994) study. This value reflects the large amount of energy consumed in heating the water body of the lake. Moreover, evaporation from the lake was not directly related to solar radiation. This observation was clear during night time when the evaporation continued with almost the same rate as daytime evaporation. This explains the vital role of heat storage in the lake as the main driving energy for evaporation during night time and day time cloudy sky conditions. When comparing over-lake and nearby land-based weather parameters, land-based wind speed was the only weather parameter that had a significant difference of about 50% lower than over-lake measurements. Other weather parameters were quite similar. The study showed that evaporation from the lake can be accurately estimated using Penman-type equations if related parameters such as net radiation, heat storage, and

  6. Nonpsychotropic cannabinoids, abnormal cannabidiol and canabigerol-dimethyl heptyl, act at novel cannabinoid receptors to reduce intraocular pressure.

    PubMed

    Szczesniak, Anna-Maria; Maor, Yehoshua; Robertson, Harold; Hung, Orlando; Kelly, Melanie E M

    2011-10-01

    The objective of our study was to examine the pharmacology of the intraocular pressure (IOP)-lowering actions of the behaviorally inactive cannabinoids, abnormal cannabidiol (abn-CBD), and a cannabigerol analog, cannabigerol-dimethyl heptyl (CBG-DMH), in comparison to that of the nonselective cannabinoid 1 receptor (CB(1)R) and CB(2)R agonist, WIN55,212-2, in Brown Norway rats. The IOP was measured noninvasively using a hand-held tonometer in nonanesthetized animals. The IOP measurements were taken every 15 min for a period of 2 h after drug administration. All drugs were administered via intraperitoneal (i.p.) injections, and abn-CBD and CBG-DMH were also given topically. Both abn-CBD and CBG-DMH reduced IOP when administrated i.p. at doses of ≥2.5 mg/kg or topically at concentrations of 1%-2%. The IOP-lowering effects of abn-CBD and CBG-DMH were reduced by i.p. administration of O-1918 (2.5 mg/kg), a selective antagonist of the abn-CBD-sensitive cannabinoid-related receptor (CBx), but were unaffected by the CB(1)R antagonist, AM251 (2.5 mg/kg), or the CB(2)R antagonist, AM630 (2.5 mg/kg). In contrast, the IOP-lowering action of WIN55,212-2 was completely blocked by the CB(1)R-selective antagonist, AM251, and was unaffected by the CBx receptor antagonist, O-1918. However, similar to the nonpsychotropic cannabinoids, the ocular hypotensive actions of WIN55,212-2 were also insensitive to block by the CB(2)R antagonist, AM630. Consistent with this, the selective CB(2)R agonist, HU-308 (2 mg/kg) failed to reduce IOP in Brown Norway rats. Concurrent application of a dose of WIN55,212-2 that was subthreshold to reduce IOP (0.25 mg/kg), together with a topical dose of either abn-CBD (0.5%) or CBG-DMH (0.25%), respectively, potentiated the ocular hypotensive effect of either compound applied alone. This study demonstrates that the atypical cannabinoid, abn-CBD, and the cannabigerol analog, CBG-DMH, decrease IOP in the normotensive Brown Norway rat eye independent of CB

  7. 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.

  8. 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.

  9. Method for the evaporation of a liquid solution using mechanical compression

    SciTech Connect

    Eversdijk, B.P.

    1984-02-28

    A liquid solution is passed through a multi-stage evaporation plant while using recirculated vapor, fed through a mechanical compressor in order to increase the pressure and temperature of the vapor. The plant comprises a number of evaporators connected in series and split up into a plurality of groups, which comprise a decreasing number of evaporators; as seen in the flow direction-the vapor being fed in parallel, streams through said groups.

  10. 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

  11. Interfacial Instabilities in Evaporating Drops

    NASA Astrophysics Data System (ADS)

    Moffat, Ross; Sefiane, Khellil; Matar, Omar

    2007-11-01

    We study the effect of substrate thermal properties on the evaporation of sessile drops of various liquids. An infra-red imaging technique was used to record the interfacial temperature. This technique illustrates the non-uniformity in interfacial temperature distribution that characterises the evaporation process. Our results also demonstrate that the evaporation of methanol droplets is accompanied by the formation of wave-trains in the interfacial temperature field; similar patterns, however, were not observed in the case of water droplets. More complex patterns are observed for FC-72 refrigerant drops. The effect of substrate thermal conductivity on the structure of the complex pattern formation is also elucidated.

  12. 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

  13. Microfabricated Valveless Devices for Thermal Bioreactions based on Diffusion-limited Evaporation

    PubMed Central

    Wang, Fang; Yang, Ming; Burns, Mark A.

    2009-01-01

    Microfluidic devices that reduce evaporative loss during thermal bioreactions such as PCR without microvalves have been developed by relying on the principle of diffusion-limited evaporation. Both theoretical and experimental results demonstrate that the sample evaporative loss can be reduced by more than 20 times using long narrow diffusion channels on both sides of the reaction region. In order to further suppress the evaporation, the driving force for liquid evaporation is reduced by two additional techniques: decreasing the interfacial temperature using thermal isolation and reducing the vapor concentration gradient by replenishing water vapor in the diffusion channels. Both thermal isolation and vapor replenishment techniques can limit the sample evaporative loss to approximately 1% of the reaction content. PMID:18094766

  14. Using a Low-Sodium, High-Potassium Salt Substitute to Reduce Blood Pressure among Tibetans with High Blood Pressure: A Patient-Blinded Randomized Controlled Trial

    PubMed Central

    Zhao, Xingshan; Yin, Xuejun; Li, Xian; Yan, Lijing L.; Lam, Christopher T.; Li, Shenshen; He, Feng; Xie, Wuxiang; Sang, Ba; Luobu, Gesang; Ke, Liang; Wu, Yangfeng

    2014-01-01

    Objectives To evaluate the effects of a low-sodium and high-potassium salt-substitute on lowering blood pressure (BP) among Tibetans living at high altitude (4300 meters). Method The study was a patient-blinded randomized controlled trial conducted between February and May 2009 in Dangxiong County, Tibetan Autonomous Region, China. A total of 282 Tibetans aged 40 or older with known hypertension (systolic BP≥140 mmHg) were recruited and randomized to intervention (salt-substitute, 65% sodium chloride, 25% potassium chloride and 10% magnesium sulfate) or control (100% sodium chloride) in a 1: 1 allocation ratio with three months’ supply. Primary outcome was defined as the change in BP levels measured from baseline to followed-up with an automated sphygmomanometer. Per protocol (PP) and intention to treat (ITT) analyses were conducted. Results After the three months’ intervention period, the net reduction in SBP/DBP in the intervention group in comparison to the control group was −8.2/−3.4 mmHg (all p<0.05) in PP analysis, after adjusting for baseline BP and other variables. ITT analysis showed the net reduction in SBP/DBP at −7.6/−3.5 mmHg with multiple imputations (all p<0.05). Furthermore, the whole distribution of blood pressure showed an overall decline in SBP/DBP and the proportion of patients with BP under control (SBP/DBP<140 mmHg) was significantly higher in salt-substitute group in comparison to the regular salt group (19.2% vs. 8.8%, p = 0.027). Conclusion Low sodium high potassium salt-substitute is effective in lowering both systolic and diastolic blood pressure and offers a simple, low-cost approach for hypertension control among Tibetans in China. Trial Registration ClinicalTrials.gov NCT01429246 PMID:25338053

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Horst Meyer and Quantum Evaporation

    NASA Astrophysics Data System (ADS)

    Balibar, S.

    2016-11-01

    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.

  20. 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.

  1. 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.

  2. 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

  3. 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)

  4. 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.

  5. 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.

  6. 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.''

  7. Impact of ambient conditions on evaporation from porous media

    NASA Astrophysics Data System (ADS)

    Ben Neriah, Asaf; Assouline, Shmuel; Shavit, Uri; Weisbrod, Noam

    2014-08-01

    The complexity of soil evaporation, depending on the atmospheric conditions, emphasizes the importance of its quantification under potential changes in ambient air temperature, Ta, and relative humidity, RH. Mass loss, soil matric tension, and meteorological measurements, carried out in a climate-controlled laboratory, were used to study the effect of ambient conditions on the drying rates of a porous medium. A set of evaporation experiments from initially saturated sand columns were carried out under constant Ta of 6, 15, 25, and 35°C and related RH (0.66, 0.83, 1.08, and 1.41 kPa, respectively). The results show that the expected increase of the stage 1 (S1) evaporation rate with Ta but also revealed an exponential-like reduction in the duration of S1, which decreased from 29 to 2.3 days (at Ta of 6 and 35°C, respectively). The evaporation rate, e(t), was equal to the potential evaporation, ep(t), under Ta = 6°C, while it was always smaller than ep(t) under higher Ta. The cumulative evaporation during S1 was higher under Ta = 6°C than under the higher temperatures. Evaporation rates during S2 were practically unaffected by ambient conditions. The results were analyzed using a mass transfer formulation linking e(t) with the vapor pressure deficit through a resistance coefficient r. It was shown that rS1 (the resistance during S1) is constant, indicating that the application of such an approach is straightforward during S1. However, for evaporation from a free water surface and S2, the resistances, rBL and rS2, were temperature-dependent, introducing some complexity for these cases.

  8. 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.

  9. Self-regulation and social pressure reduce prejudiced responding and increase the motivation to be non-prejudiced.

    PubMed

    Buzinski, Steven G; Kitchens, Michael B

    2016-12-02

    Self-regulation constrains the expression of prejudice, but when self-regulation falters, the immediate environment can act as an external source of prejudice regulation. This hypothesis derives from work demonstrating that external controls and internal self-regulation can prompt goal pursuit in the absence of self-imposed controls. Across four studies, we found support for this complementary model of prejudice regulation. In Study 1, self-regulatory fatigue resulted in less motivation to be non-prejudiced, compared to a non-fatigued control. In Study 2, strong (vs. weak) perceived social pressure was related to greater motivation to be non-prejudiced. In Study 3, dispositional self-regulation predicted non-prejudice motivation when perceived social pressure was weak or moderate, but not when it was strong. Finally, in Study 4 self-regulatory fatigue increased prejudice when social pressure was weak but not when it was strong.

  10. Controllable evaporation of cesium from a dispenser oven.

    PubMed

    Fantz, U; Friedl, R; Fröschle, M

    2012-12-01

    This instrument allows controlled evaporation of the alkali metal cesium over a wide range of evaporation rates. The oven has three unique features. The first is an alkali metal reservoir that uses a dispenser as a cesium source. The heating current of the dispenser controls the evaporation rate allowing generation of an adjustable and stable flow of pure cesium. The second is a blocking valve, which is fully metallic as is the body of the oven. This construction both reduces contamination of the dispenser and enables the oven to be operated up to 300 °C, with only small temperature variations (<5 °C). By minimizing the temperature variation, the built up of the alkali metal at a cold spot is significantly hindered. The last feature is an integral surface ionization detector for measuring and controlling the evaporation rate. The dispenser oven can be easily transferred to the other alkali-metals.

  11. Urban evaporation rates for water-permeable pavements.

    PubMed

    Starke, P; Göbel, P; Coldewey, W G

    2010-01-01

    In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural.

  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. On the derivation of Young's equation for sessile drops: nonequilibrium effects due to evaporation.

    PubMed

    Butt, Hans-Jürgen; Golovko, Dmytro S; Bonaccurso, Elmar

    2007-05-17

    Sessile liquid drops have a higher vapor pressure than planar liquid surfaces, as quantified by Kelvin's equation. In classical derivations of Young's equation, this fact is often not taken into account. For an open system, a sessile liquid drop is never in thermodynamic equilibrium and will eventually evaporate. Practically, for macroscopic drops the time of evaporation is so long that nonequilibrium effects are negligible. For microscopic drops evaporation cannot be neglected. When a liquid is confined to a closed system, real equilibrium can be established. Experiments on the evaporation of water drops confirm the calculations.

  14. Strategies for reducing preferred orientation and strain in powder samples for high-pressure synchrotron X-ray diffraction in diamond-anvil cells

    SciTech Connect

    Tschauner, Oliver; McClure, Jason; Nicol, Malcolm

    2010-07-20

    Among the many problems associated with high-pressure X-ray diffraction from polycrystalline samples in the diamond-anvil cell are strain and preferred orientation. A method is presented for efficiently reducing preferred orientation of powder samples compressed in diamond-anvil cells to pressures in excess of 20 GPa. This method may be successfully applied to samples of yield strength higher than alkalihalides. In addition, the problem of strain is discussed using ice-VII as an example and as an illustration of the importance of laser heating as a method of minimizing strain.

  15. CO2 exposure at pressure impacts metabolism and stress responses in the model sulfate-reducing bacterium Desulfovibrio vulgaris strain Hildenborough.

    PubMed

    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 (13)C-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.

  16. 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

  17. 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.

  18. Azilsartan medoxomil plus chlorthalidone reduces blood pressure more effectively than olmesartan plus hydrochlorothiazide in stage 2 systolic hypertension.

    PubMed

    Cushman, William C; Bakris, George L; White, William B; Weber, Michael A; Sica, Domenic; Roberts, Andrew; Lloyd, Eric; Kupfer, Stuart

    2012-08-01

    Azilsartan medoxomil, an effective, long-acting angiotensin II receptor blocker, is a new treatment for hypertension that is also being developed in fixed-dose combinations with chlorthalidone, a potent, long-acting thiazide-like diuretic. We compared once-daily fixed-dose combinations of azilsartan medoxomil/chlorthalidone force titrated to a high dose of either 40/25 mg or 80/25 mg with a fixed-dose combination of the angiotensin II receptor blocker olmesartan medoxomil plus the thiazide diuretic hydrochlorothiazide force titrated to 40/25 mg. The design was a randomized, 3-arm, double-blind, 12-week study of 1071 participants with baseline clinic systolic blood pressure 160 to 190 mm Hg and diastolic blood pressure ≤119 mm Hg. Patients had a mean age of 57 years; 59% were men, 73% were white, and 22% were black. At baseline, mean clinic blood pressure was 165/96 mm Hg and 24-hour mean blood pressure was 150/88 mm Hg. Changes in clinic (primary end point) and ambulatory systolic blood pressures at week 12 were significantly greater in both azilsartan medoxomil/chlorthalidone arms than in the olmesartan/hydrochlorothiazide arm (P<0.001). Changes in clinic systolic blood pressure (mean±SE) were -42.5±0.8, -44.0±0.8, and -37.1±0.8 mm Hg, respectively. Changes in 24-hour ambulatory systolic blood pressure were -33.9±0.8, -36.3±0.8, and -27.5±0.8 mm Hg, respectively. Adverse events leading to permanent drug discontinuation occurred in 7.9%, 14.5%, and 7.1% of the groups given azilsartan medoxomil/chlorthalidone 40/25 mg, azilsartan medoxomil/chlorthalidone 80/25 mg, and olmesartan/hydrochlorothiazide 40/25 mg, respectively. This large, forced-titration study has demonstrated superior antihypertensive efficacy of azilsartan medoxomil/chlorthalidone fixed-dose combinations compared with the maximum approved dose of olmesartan/hydrochlorothiazide.

  19. Numerical simulation of water evaporation inside vertical circular tubes

    NASA Astrophysics Data System (ADS)

    Ocłoń, Paweł; Nowak, Marzena; Majewski, Karol

    2013-10-01

    In this paper the results of simplified numerical analysis of water evaporation in vertical circular tubes are presented. The heat transfer in fluid domain (water or wet steam) and solid domain (tube wall) is analyzed. For the fluid domain the temperature field is calculated solving energy equation using the Control Volume Method and for the solid domain using the Finite Element Method. The heat transfer between fluid and solid domains is conjugated using the value of heat transfer coefficient from evaporating liquid to the tube wall. It is determined using the analytical Steiner-Taborek correlation. The pressure changes in fluid are computed using Friedel model.

  20. Performance Tests of Shell and Plate Type Evaporator for OTEC

    NASA Astrophysics Data System (ADS)

    Nakaoka, Tsutomu; Uehara, Haruo

    Performance tests on a shell and plate type evaporator (total surface area = 21.95m2, length = 1450mm, width = 235mm, plate number = 100) for ocean thermal energy conversion (OTEC) plants. Freon 22 (R22) and ammonia (NH3) are used as working fluid. The empirical correlations are proporsed in order to predict the boiling heat transfer when using R22 and NH3 and water side heat transfer coefficients for a shell and plate type evaporator. The water side pressure drop is about 3 m at the warm water velocity of 0.7 m/s. The water side friction factor is obtained.

  1. 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.

  2. 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.

  3. 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.

  4. Apparent latent heat of evaporation from clothing: attenuation and "heat pipe" effects.

    PubMed

    Havenith, George; Richards, Mark G; Wang, Xiaoxin; Bröde, Peter; Candas, Victor; den Hartog, Emiel; Holmér, Ingvar; Kuklane, Kalev; Meinander, Harriet; Nocker, Wolfgang

    2008-01-01

    Investigating claims that a clothed person's mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34 degrees C in ambient temperatures of 10, 20, and 34 degrees C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (E(mass)) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (E(app)) were compared. A clear discrepancy was observed. E(mass) overestimated E(app) in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34 degrees C, apparent latent heat (lambda(app)) of pure evaporative cooling was lower than the physical value (lambda; 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, lambda(app) increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, lambda(app) even exceeds lambda by four times that value at 10 degrees C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

  5. The role of dietary polyunsaturated fatty acids and prostaglandins in reducing blood pressure and improving thrombogenic indices.

    PubMed

    Iacono, J M; Dougherty, R M

    1983-01-01

    Evidence linking dietary fats to blood pressure and thrombogenic indices is reviewed. Results of dietary studies performed at Beltsville, Maryland, have demonstrated that under controlled dietary conditions, i.e., when total fat intake is maintained at 25% fat calories with a P/S ratio of 1, at either a fixed or free-choice salt intake and where the body weight is maintained relatively constant, blood pressure can be lowered and platelet aggregation indices can be improved in men and women in the 40-60 age group. Results of a pilot epidemiologic study of farmers aged 40-45 in Finland and Italy generally confirm the experimental nutrition studies reported above. A possible explanation of these results based on the conversion of linoleic acid to prostaglandins as well as the physiological actions of prostaglandins is discussed.

  6. 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.

  7. Evaporation kinetics of laboratory-generated secondary organic aerosols at elevated relative humidity.

    PubMed

    Wilson, Jacqueline; Imre, Dan; Beránek, Josef; Shrivastava, Manish; Zelenyuk, Alla

    2015-01-06

    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 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.

  8. Negative Pressure Wound Therapy Reduces the Effectiveness of Traditional Local Antibiotic Depot in a Large Complex Musculoskeletal Wound Animal Model

    DTIC Science & Technology

    2012-09-01

    in particular, local antibiotic delivery via polymethylmethacrylate (PMMA) bone cement and negative pressure wound therapy (NPWT). In cases with gross...release of gentamicin from polymethylmethacrylate beads. An experimental and pharmacoki- netic study. J Bone Joint Surg Br. 1978;60-B:270 275. 7...diffusion from antibiotic-impregnated polymethylmethacrylate beads. Clin Orthop Relat Res. 1992;278:244 252. Stinner et al J Orthop Trauma Volume

  9. 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.

  10. 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.

  11. 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.

  12. Theoretical and computational analyses of LNG evaporator

    NASA Astrophysics Data System (ADS)

    Chidambaram, Palani Kumar; Jo, Yang Myung; Kim, Heuy Dong

    2017-04-01

    Theoretical and numerical analysis on the fluid flow and heat transfer inside a LNG evaporator is conducted in this work. Methane is used instead of LNG as the operating fluid. This is because; methane constitutes over 80% of natural gas. The analytical calculations are performed using simple mass and energy balance equations. The analytical calculations are made to assess the pressure and temperature variations in the steam tube. Multiphase numerical simulations are performed by solving the governing equations (basic flow equations of continuity, momentum and energy equations) in a portion of the evaporator domain consisting of a single steam pipe. The flow equations are solved along with equations of species transport. Multiphase modeling is incorporated using VOF method. Liquid methane is the primary phase. It vaporizes into the secondary phase gaseous methane. Steam is another secondary phase which flows through the heating coils. Turbulence is modeled by a two equation turbulence model. Both the theoretical and numerical predictions are seen to match well with each other. Further parametric studies are planned based on the current research.

  13. 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.

  14. Structural transitions in a ring stain created at the contact line of evaporating nanosuspension sessile drops.

    PubMed

    Askounis, Alexandros; Sefiane, Khellil; Koutsos, Vasileios; Shanahan, Martin E R

    2013-01-01

    Monodisperse nanosuspension droplets, placed on a flat surface, evaporated following the stick-slip motion of the three-phase contact line. Unexpectedly, a disordered region formed at the exterior edge of a closely packed nanocolloidal crystalline structure during the "stick" period. In order to assess the role of particle velocity on particle structuring, we did experiments in a reduced pressure environment which allowed the enhancement of particle velocity. These experiments revealed the promotion of hexagonal packing at the very edge of the crystallite with increasing velocity. Quantification of particle velocity and comparison with measured deposit shape for each case allowed us to provide a tentative description of the underlying mechanisms that govern particle deposition of nanoparticles at the triple line of an evaporating droplet. Behavior is governed by an interplay between the fluid, and hence particle, flow velocity (main ordering parameter) and wedge constraints, and consequently disjoining pressure (main disordering parameter). Furthermore, the formation of a second disordered particle region at the interior edge of the deposit (towards bulk fluid) was found and attributed to the rapid motion of the triple line during the "slip" regime. Additionally, the magnitude of the pinning forces acting on the triple line of the same drops was calculated. These findings provide further insight into the mechanisms of the phenomenon and could facilitate its exploitation in various nanotechnological applications.

  15. Structural transitions in a ring stain created at the contact line of evaporating nanosuspension sessile drops

    NASA Astrophysics Data System (ADS)

    Askounis, Alexandros; Sefiane, Khellil; Koutsos, Vasileios; Shanahan, Martin E. R.

    2013-01-01

    Monodisperse nanosuspension droplets, placed on a flat surface, evaporated following the stick-slip motion of the three-phase contact line. Unexpectedly, a disordered region formed at the exterior edge of a closely packed nanocolloidal crystalline structure during the “stick” period. In order to assess the role of particle velocity on particle structuring, we did experiments in a reduced pressure environment which allowed the enhancement of particle velocity. These experiments revealed the promotion of hexagonal packing at the very edge of the crystallite with increasing velocity. Quantification of particle velocity and comparison with measured deposit shape for each case allowed us to provide a tentative description of the underlying mechanisms that govern particle deposition of nanoparticles at the triple line of an evaporating droplet. Behavior is governed by an interplay between the fluid, and hence particle, flow velocity (main ordering parameter) and wedge constraints, and consequently disjoining pressure (main disordering parameter). Furthermore, the formation of a second disordered particle region at the interior edge of the deposit (towards bulk fluid) was found and attributed to the rapid motion of the triple line during the “slip” regime. Additionally, the magnitude of the pinning forces acting on the triple line of the same drops was calculated. These findings provide further insight into the mechanisms of the phenomenon and could facilitate its exploitation in various nanotechnological applications.

  16. 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.

  17. 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)

  18. 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.

  19. Effect of superhydrophobic surface morphology on evaporative deposition patterns

    NASA Astrophysics Data System (ADS)

    Dicuangco, Mercy; Dash, Susmita; Weibel, Justin A.; Garimella, Suresh V.

    2014-05-01

    Prediction and active control of the spatial distribution of particulate deposits obtained from sessile droplet evaporation are vital in printing, nanostructure assembly, biotechnology, and other applications that require localized deposits. This Letter presents surface wettability-based localization of evaporation-driven particulate deposition and the effect of superhydrophobic surface morphology on the distribution of deposits. Sessile water droplets containing suspended latex particles are evaporated on non-wetting textured surfaces with varying microstructure geometry at ambient conditions. The droplets are visualized throughout the evaporation process to track the temporal evolution of contact radius and apparent contact angle. The resulting particle deposits on the substrates are quantitatively characterized. The experimental results show that superhydrophobic surfaces suppress contact-line deposition during droplet evaporation, thereby providing an effective means of localizing the deposition of suspended particles. A correlation between deposit size and surface morphology, explained in terms of the interface pressure balance at the transition between wetting states, reveals an optimum surface morphology for minimizing the deposit coverage area.

  20. 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).

  1. 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.

  2. Transient increase in intrahepatic pressure mediates successful treatment of the Gunn rat with reduced doses of lentiviral vector.

    PubMed

    Schmitt, Françoise; Flageul, Maude; Dariel, Anne; Pichard, Virginie; Pontes, Cecilia Abarrategui; Boni, Sébastien; Podevin, Guillaume; Myara, Anne; Ferry, Nicolas; Nguyen, Tuan Huy

    2010-10-01

    Lentiviral vectors can stably transduce hepatocytes and are promising tools for gene therapy of hepatic diseases. Although hepatocytes are accessible to blood-borne viral vectors through fenestrations of the hepatic endothelium, improved liver transduction after delivery of vectors to the blood stream is needed. As the normal endothelial fenestration and lentiviral vectors are similar in size (150 nm), we hypothesized that a transient increase in hepatic blood pressure may enhance in vivo gene transfer to hepatocytes. We designed a simple surgical procedure, by which the liver is temporarily excluded from blood flow. Lentiviral vectors were injected in a large volume to increase intrahepatic pressure. We demonstrated that in the Gunn rat, a model of Crigler-Najjar disease, the administration of low vector doses (corresponding to a multiplicity of infection of 0.2) by this procedure resulted in therapeutic correction of hyperbilirubinemia, without toxicity. The correction was sustained for 10 months (end of study). The same vector amounts yielded only partial correction after intraportal delivery. We believe that this new and clinically applicable strategy may broaden the range of genetic liver diseases accessible to gene therapy.

  3. Evaporative water loss, relative water economy and evaporative partitioning of a heterothermic marsupial, the monito del monte (Dromiciops gliroides).

    PubMed

    Withers, Philip C; Cooper, Christine E; Nespolo, Roberto F

    2012-08-15

    We examine here evaporative water loss, economy and partitioning at ambient temperatures from 14 to 33°C for the monito del monte (Dromiciops gliroides), a microbiotheriid marsupial found only in temperate rainforests of Chile. The monito's standard evaporative water loss (2.58 mg g(-1) h(-1) at 30°C) was typical for a marsupial of its body mass and phylogenetic position. Evaporative water loss was independent of air temperature below thermoneutrality, but enhanced evaporative water loss and hyperthermia were the primary thermal responses above the thermoneutral zone. Non-invasive partitioning of total evaporative water loss indicated that respiratory loss accounted for 59-77% of the total, with no change in respiratory loss with ambient temperature, but a small change in cutaneous loss below thermoneutrality and an increase in cutaneous loss in and above thermoneutrality. Relative water economy (metabolic water production/evaporative water loss) increased at low ambient temperatures, with a point of relative water economy of 15.4°C. Thermolability had little effect on relative water economy, but conferred substantial energy savings at low ambient temperatures. Torpor reduced total evaporative water loss to as little as 21% of normothermic values, but relative water economy during torpor was poor even at low ambient temperatures because of the relatively greater reduction in metabolic water production than in evaporative water loss. The poor water economy of the monito during torpor suggests that negative water balance may explain why hibernators periodically arouse to normothermia, to obtain water by drinking or via an improved water economy.

  4. Evaporation control research, 1959-60

    USGS Publications Warehouse

    ,

    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

  5. 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.

  6. 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.

  7. Observations of Si field evaporation.

    PubMed

    Thompson, Keith; Sebastian, Jason; Gerstl, Stephan

    2007-01-01

    Field evaporation studies of crystalline <100> Si were performed in a three-dimensional atom-probe, which utilized a local electrode geometry. Several distinct phenomena were observed. Si field evaporation rates showed: (1) no measurable dependence on temperature below 110K, (2) an exponential dependence on evaporation rate as a function of temperature above 110K, and (3) no dependence on substrate doping (i.e., electrical conductivity) as high as 10 Omega cm in the temperature range of 40-150K. Two distinct evaporation modes were observed. The first was associated with approximately 1at% H+ in the mass spectrum. Negligible amounts of H were detected in the mass spectra of the second mode. When the pulse fraction (pf) was increased from 5% to 30%, the presence of H+ in the mass spectra, i.e. operation in the first mode, was associated with a degradation in mass resolution by as much as 80% for the 10 Omega cm Si samples. Conversely, no loss in mass resolution was detected for the approximately 0.001 Omega cm samples over the pf range studied.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. Evaporation of sessile water/ethanol drops in a controlled environment.

    PubMed

    Liu, Chuanjun; Bonaccurso, Elmar; Butt, Hans-Jürgen

    2008-12-21

    The evaporation of water/ethanol drops with different mixing ratios was investigated at controlled vapor pressure of water (relative humidity) and ethanol in the background gas. Therefore, a drop of about 1 microL was deposited on a hydrophobized silicon substrate at room temperature in a closed cell. With a microscope camera we monitored the contact angle, the volume and the contact radius of the drops as function of time. Pure water drops evaporated in constant contact angle mode. The evaporation rate of water decreased with increasing humidity. In mixed drops ethanol did not evaporate completely at first, but a fraction still remained in the drop until the end of evaporation. Depending on ethanol concentration in the drop and on relative humidity in the background gas, water vapor condensed at the beginning of the evaporation of mixed drops. Also, at a high vapor pressure of ethanol, ethanol condensed at the beginning of the evaporation. The presence of ethanol vapor accelerated the total evaporation time of water drops.

  16. Water-evaporation reduction by duplex films: application to the human tear film.

    PubMed

    Cerretani, Colin F; Ho, Nghia H; Radke, C J

    2013-09-01

    Water-evaporation reduction by duplex-oil films is especially important to understand the physiology of the human tear film. Secreted lipids, called meibum, form a duplex film that coats the aqueous tear film and purportedly reduces tear evaporation. Lipid-layer deficiency is correlated with the occurrence of dry-eye disease; however, in-vitro experiments fail to show water-evaporation reduction by tear-lipid duplex films. We review the available literature on water-evaporation reduction by duplex-oil films and outline the theoretical underpinnings of spreading and evaporation kinetics that govern behavior of these systems. A dissolution-diffusion model unifies the data reported in the literature and identifies dewetting of duplex films into lenses as a key challenge to obtaining significant evaporation reduction. We develop an improved apparatus for measuring evaporation reduction by duplex-oil films including simultaneous assessment of film coverage, stability, and temperature, all under controlled external mass transfer. New data reported in this study fit into the larger body of work conducted on water-evaporation reduction by duplex-oil films. Duplex-oil films of oxidized mineral oil/mucin (MOx/BSM), human meibum (HM), and bovine meibum (BM) reduce water evaporation by a dissolution-diffusion mechanism, as confirmed by agreement between measurement and theory. The water permeability of oxidized-mineral-oil duplex films agrees with those reported in the literature, after correction for the presence of mucin. We find that duplex-oil films of bovine and human meibum at physiologic temperature reduce water evaporation only 6-8% for a 100-nm film thickness pertinent to the human tear film. Comparison to in-vivo human tear-evaporation measurements is inconclusive because evaporation from a clean-water surface is not measured and because the mass-transfer resistance is not characterized.

  17. Pressure overload-induced mild cardiac hypertrophy reduces left ventricular transmural differences in mitochondrial respiratory chain activity and increases oxidative stress

    PubMed Central

    Kindo, Michel; Gerelli, Sébastien; Bouitbir, Jamal; Charles, Anne-Laure; Zoll, Joffrey; Hoang Minh, Tam; Monassier, Laurent; Favret, Fabrice; Piquard, François; Geny, Bernard

    2012-01-01

    Objective: Increased mechanical stress and contractility characterizes normal left ventricular (LV) subendocardium (Endo) but whether Endo mitochondrial respiratory chain complex activities is reduced as compared to subepicardium (Epi) and whether pressure overload-induced LV hypertrophy (LVH) might modulate transmural gradients through increased reactive oxygen species (ROS) production is unknown. Methods: LVH was induced by 6 weeks abdominal aortic banding and cardiac structure and function were determined with echocardiography and catheterization in sham-operated and LVH rats (n = 10 for each group). Mitochondrial respiration rates, coupling, content and ROS production were measured in LV Endo and Epi, using saponin-permeabilized fibers, Amplex Red fluorescence and citrate synthase activity. Results: In sham, a transmural respiratory gradient was observed with decreases in endo maximal oxidative capacity (−36.7%, P < 0.01) and complex IV activity (−57.4%, P < 0.05). Mitochondrial hydrogen peroxide (H2O2) production was similar in both LV layers. Aortic banding induced mild LVH (+31.7% LV mass), associated with normal LV fractional shortening and end diastolic pressure. LVH reduced maximal oxidative capacity (−23.6 and −33.3%), increased mitochondrial H2O2 production (+86.9 and +73.1%), free radical leak (+27.2% and +36.3%) and citrate synthase activity (+27.2% and +36.3%) in Endo and Epi, respectively. Transmural mitochondrial respiratory chain complex IV activity was reduced in LVH (−57.4 vs. −12.2%; P = 0.02). Conclusions: Endo mitochondrial respiratory chain complexes activities are reduced compared to LV Epi. Mild LVH impairs mitochondrial oxidative capacity, increases oxidative stress and reduces transmural complex IV activity. Further studies will be helpful to determine whether reduced LV transmural gradient in mitochondrial respiration might be a new marker of a transition from uncomplicated toward complicated LVH. PMID:22934079

  18. Fully automated open access platform for rapid, combined serial evaporation and sample reformatting.

    PubMed

    Benali, Otman; Davies, Gary; Deal, Martyn; Farrant, Elizabeth; Guthrie, Duncan; Holden, John; Wheeler, Rob

    2008-01-01

    This paper reports a novel evaporator and its integration with an automated sample handling system to create a high throughput evaporation platform. The Vaportec V-10 evaporator uses a high speed rotation motor ( approximately 6000 rpm) to spin the vial containing a sample, creating a thin film of solvent which can be readily evaporated by the application of heat to the vial, while the consequent centrifugal force prevents "bumping". An intelligent algorithm controls pressure and temperature for optimum solvent removal conditions and end of run detection, critical for automation. The system allows the option of evaporation directly from a sample source vial, or alternatively, integrated liquid handling facilities provide the capability of transferring samples portionwise from a (large) source vial or bottle to a (small) daughter container, enabling efficient sample reformatting, with minimum user intervention. The open access system makes significant advances over current vacuum centrifugal evaporators in terms of evaporation rate and ease of automation. The evaporator's main features, the integration of robotics to provide automation, and examples of evaporation rates of a wide range of solvents from a variety of containers are described.

  19. Evaporation from the understorey in the Jarrah ( Eucalyptus marginata Don ex Sm.) forest, southwestern Australia

    NASA Astrophysics Data System (ADS)

    Greenwood, E. A. N.; Klein, L.; Beresford, J. D.; Watson, G. D.; Wright, K. D.

    1985-10-01

    Annual evaporation from groundflora, litter and soil of the jarrah forest was estimated from measurements of daily evaporation by ventilated chambers on several days over two separate 12-month periods. In the first year, when sampling ranged over 0.1 ha of forest, annual evaporation during daylight hours was estimated as 410 mm (0.32 rainfall). In the second year, sampling was more frequent, on a larger scale, and included the night hours. Annual evaporation was estimated at 360 mm (0.36 rainfall). Similarly, in the second year, annual evaporation from two trees of the dominant middle storey species, Banksia grandis, was estimated at 7500 and 18,9001 respectively. The leaf area of these two trees was 9.6 and 22.4 m 2, respectively, so that annual evaporation, when expressed as mm 3 per mm 2 leaf area, was similar for both trees (mean = 820 ± 30 mm). Applying that value to all Banksia trees in a hectare of forest, and using a measured estimate of leaf area index of 0.19, the estimated annual evaporation from the Banksia component was 155 mm (0.16 rainfall). For the upland part of the forest sampled, the combined annual evaporation from the lower and middle storeys accounted for about half (0.51) of the annual rainfall. We conclude that reduced evaporation from the upper storey following clearing or thinning may be strongly counteracted by increased evaporation from the understorey due to increased availability of energy and water.

  20. The surface temperature of free evaporating drops

    NASA Astrophysics Data System (ADS)

    Borodulin, V. Y.; Letushko, V. N.; Nizovtsev, M. I.; Sterlyagov, A. N.

    2016-10-01

    Complex experimental and theoretical investigation of heat and mass transfer processes was performed at evaporation of free liquid drops. For theoretical calculation the emission-diffusion model was proposed. This allowed taking into account the characteristics of evaporation of small droplets, for which heat and mass transfer processes are not described in the conventional diffusion model. The calculation results of evaporation of droplets of different sizes were compared using two models: the conventional diffusion and emission-diffusion models. To verify the proposed physical model, the evaporation of droplets suspended on a polypropylene fiber was experimentally investigated. The form of droplets in the evaporation process was determined using microphotographing. The temperature was measured on the surfaces of evaporating drops using infrared thermography. The experimental results have showed good agreement with the numerical data for the time of evaporation and the temperature of evaporating drops.

  1. Synthesis on evaporation partitioning using stable isotopes

    NASA Astrophysics Data System (ADS)

    Coenders-Gerrits, Miriam; Bogaard, Thom; Wenninger, Jochen; Jonson Sutanto, Samuel

    2015-04-01

    Partitioning of evaporation into productive (transpiration) and non-productive evaporation (interception, soil evaporation) is of highest importance for water management practices, irrigation scheme design, and climate modeling. Despite this urge, the magnitude of the ratio of transpiration over total evaporation is still under debate and poorly understood due to measuring difficulties. However, with the current development in isotope measuring devices, new opportunities arise to untangle the partitioning of evaporation. In this paper we synthesize the opportunities and limitations using stable water isotopes in evaporation partitioning. We will analyze a set of field as well as laboratory studies to demonstrate the different evaporation components for various climate and vegetation conditions using stable isotopes 18O/16O and 2H/1H. Experimental data on evaporation partitioning of crops, grass, shrubs and trees are presented and we will discuss the specific experimental set-ups and data collection methods. The paper will be a synthesis of these studies.

  2. 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...

  3. 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.

  4. Development and Testing of a Miniaturized Multi-Evaporator Hybrid Loop Heat Pipe

    NASA Astrophysics Data System (ADS)

    Bugby, David C.; Kroliczek, Edward J.; Yun, James S.

    2005-02-01

    This paper describes the development and testing of a miniaturized multi-evaporator hybrid loop heat pipe (ME-HLHP), a centralized thermal bus architecture proposed as the next-generation thermal management system for future small spacecraft. The ME-HLHP maximizes the advantages of capillary pumped loops (CPLs) and loop heat pipes (LHPs) and mitigates their shortcomings via the use of a secondary LHP-type evaporator that supplies a small amount of excess liquid flow ("core sweepage") to each evaporator within a multi-evaporator parallel network. To validate ME-HLHP technology, single, dual, and quad-evaporator breadboard test loops were designed, fabricated, and tested. Breadboard components included miniaturized, cylindrical Teflon wick evaporators for low control power, counter-flow condensers for freeze tolerance, a back pressure regulator for heat load sharing, a co-located flow regulator for radiator switching, a cold-biased heat exchanger for temperature control, and a secondary evaporator/reservoir for core sweepage. With ammonia as the working fluid, a total of 21 tests were carried out with the quad-evaporator test loop. The results indicated quad-evaporator transport from 8-280 W, single-evaporator transport from 2-100 W, maximum heat flux of 30 W/cm2 evaporator conductance of 5-8 W/K, heat load sharing greater than 95%, condenser switching, condenser freeze tolerant design, temperature control of +/- 0.25 K with a variable set-point, rapid start-up, control power of 2-3 W, and Teflon evaporator (233-353 K) temperature cycling for durability. This paper will detail all aspects of the study.

  5. Oral supplementation with glycine reduces oxidative stress in patients with metabolic syndrome, improving their systolic blood pressure.

    PubMed

    Díaz-Flores, Margarita; Cruz, Miguel; Duran-Reyes, Genoveva; Munguia-Miranda, Catarina; Loza-Rodríguez, Hilda; Pulido-Casas, Evelyn; Torres-Ramírez, Nayeli; Gaja-Rodriguez, Olga; Kumate, Jesus; Baiza-Gutman, Luis Arturo; Hernández-Saavedra, Daniel

    2013-10-01

    Reactive oxygen species derived from abdominal fat and uncontrolled glucose metabolism are contributing factors to both oxidative stress and the development of metabolic syndrome (MetS). This study was designed to evaluate the effects of daily administration of an oral glycine supplement on antioxidant enzymes and lipid peroxidation in MetS patients. The study included 60 volunteers: 30 individuals that were supplemented with glycine (15 g/day) and 30 that were given a placebo for 3 months. We analysed thiobarbituric acid reactive substances (TBARS) and S-nitrosohemoglobin (SNO-Hb) in plasma; the enzymatic activities of glucose-6-phosphate dehydrogenase (G6PD), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) in erythrocytes; and the expression of CAT, GPX, and SOD2 in leukocytes. Individuals treated with glycine showed a 25% decrease in TBARS compared with the placebo-treated group. Furthermore, there was a 20% reduction in SOD-specific activity in the glycine-treated group, which correlated with SOD2 expression. G6PD activity and SNO-Hb levels increased in the glycine-treated male group. Systolic blood pressure (SBP) also showed a significant decrease in the glycine-treated men (p = 0.043). Glycine plays an important role in balancing the redox reactions in the human body, thus protecting against oxidative damage in MetS patients.

  6. Deletion of the G protein-coupled receptor 30 impairs glucose tolerance, reduces bone growth, increases blood pressure, and eliminates estradiol-stimulated insulin release in female mice.

    PubMed

    Mårtensson, Ulrika E A; Salehi, S Albert; Windahl, Sara; Gomez, Maria F; Swärd, Karl; Daszkiewicz-Nilsson, Joanna; Wendt, Anna; Andersson, Niklas; Hellstrand, Per; Grände, Per-Olof; Owman, Christer; Rosen, Clifford J; Adamo, Martin L; Lundquist, Ingmar; Rorsman, Patrik; Nilsson, Bengt-Olof; Ohlsson, Claes; Olde, Björn; Leeb-Lundberg, L M Fredrik

    2009-02-01

    In vitro studies suggest that the G protein-coupled receptor (GPR) 30 is a functional estrogen receptor. However, the physiological role of GPR30 in vivo is unknown, and it remains to be determined whether GPR30 is an estrogen receptor also in vivo. To this end, we studied the effects of disrupting the GPR30 gene in female and male mice. Female GPR30((-/-)) mice had hyperglycemia and impaired glucose tolerance, reduced body growth, increased blood pressure, and reduced serum IGF-I levels. The reduced growth correlated with a proportional decrease in skeletal development. The elevated blood pressure was associated with an increased vascular resistance manifested as an increased media to lumen ratio of the resistance arteries. The hyperglycemia and impaired glucose tolerance in vivo were associated with decreased insulin expression and release in vivo and in vitro in isolated pancreatic islets. GPR30 is expressed in islets, and GPR30 deletion abolished estradiol-stimulated insulin release both in vivo in ovariectomized adult mice and in vitro in isolated islets. Our findings show that GPR30 is important for several metabolic functions in female mice, including estradiol-stimulated insulin release.

  7. 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.

  8. 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.

  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. 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...

  11. 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.

  12. 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

  13. 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…

  14. Vasopressin V2 receptor antagonist tolvaptan is effective in heart failure patients with reduced left ventricular systolic function and low blood pressure.

    PubMed

    Suzuki, Satoshi; Yoshihisa, Akiomi; Yamaki, Takayoshi; Sugimoto, Koichi; Kunii, Hiroyuki; Nakazato, Kazuhiko; Abe, Yukihiko; Saito, Tomiyoshi; Ohwada, Takayuki; Suzuki, Hitoshi; Saitoh, Shu-ichi; Kubota, Isao; Takeishi, Yasuchika

    2015-01-01

    Diuresis is a major therapy for the reduction of congestive symptoms in acute decompensated heart failure (ADHF) patients. Carperitide has natriuretic and vasodilatory effects, and tolvaptan produces water excretion without electrolyte excretion. We previously reported the usefulness of tolvaptan compared to carperitide in ADHF patients with fluid volume retention. The purpose of this study was to examine whether the efficacy of tolvaptan was altered in ADHF patients with reduced left ventricular systolic function and in those with hypotension. A total of 109 hospitalized ADHF patients were randomly assigned to either a tolvaptan or a carperitide treatment group. Baseline clinical characteristics were not different between the two groups. We divided these patients based on the left ventricular ejection fraction (EF) by echocardiography, and blood pressure (BP) at the time of admission. Daily urine volume between the tolvaptan and carperitide groups in patients with preserved EF (≥ 50%) was not different, however, in those with reduced EF (< 50%), the urine volume was significantly higher in the tolvaptan group than in the carperitide group (day 2, 3, 4, P < 0.05 for all). Daily urine volume did not differ between these two groups in the high blood pressure group (BP ≥ 140 mmHg), but was significantly higher in the tolvaptan group than in the carperitide group (day 1, P = 0.021; day 3, P = 0.017) in the low blood pressure group (BP < 140 mmHg). The present study reveals that tolvaptan is more effective than carperitide, especially in ADHF patients with reduced left ventricular systolic function and without hypertension.

  15. 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.

  16. Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces.

    PubMed

    Xu, Wei; Leeladhar, Rajesh; Kang, Yong Tae; Choi, Chang-Hwan

    2013-05-21

    Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan's kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the superhydrophobic surfaces with lower solid fractions. The discrepancy between experimental results and Rowan's model is attributed to the initial large contact angle of a droplet on superhydrophobic surfaces. The droplet geometry with a large contact angle results in a narrow wedge region of air along the contact boundary, where the liquid-vapor diffusion is significantly restricted. Such an effect becomes minor as the evaporation proceeds with the decrease in a contact angle. In both the CCR and CCA modes, the evaporative mass transfer shows the linear relationship between mass(2/3) and evaporation time. However, the evaporation rate is slower on the superhydrophobic surfaces, which is more significant on the surfaces with lower solid fractions. As a result, the superhydrophobic surfaces slow down the drying process of a sessile droplet on them.

  17. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis.

    PubMed

    Siervo, Mario; Lara, Jose; Ogbonmwan, Ikponmwonsa; Mathers, John C

    2013-06-01

    Diets including food products rich in inorganic nitrate are associated with lower blood pressure (BP). The evidence for the BP-lowering effects of inorganic nitrate and beetroot in randomized clinical trials has not been systematically assessed. The objective was to conduct a systematic review and meta-analysis of randomized clinical trials that examined the effects of inorganic nitrate and beetroot supplementation on BP. Medline, EMBASE, and Scopus databases were searched from inception to February 2013. The specific inclusion criteria were: 1) randomized clinical trials; 2) trials reporting effects on systolic or diastolic BP or both; and 3) trials comparing inorganic nitrate or beetroot juice supplementation with placebo control groups. Random-effects models were used to assess the pooled BP effect sizes. Sixteen trials met the eligibility criteria for the systematic review. All studies had a crossover study design. The trials were conducted between 2006 and 2012 and included a total of 254 participants with 7-30 participants/study. The duration of each intervention ranged from 2 h to 15 d. Inorganic nitrate and beetroot juice consumption were associated with greater changes in systolic BP [-4.4 mm Hg (95% CI: -5.9, -2.8); P < 0.001] than diastolic BP [-1.1 mm Hg (95% CI: -2.2, 0.1); P = 0.06]. The meta-regression showed an association between daily dose of inorganic nitrate and changes in systolic BP (P < 0.05). Inorganic nitrate and beetroot juice supplementation was associated with a significant reduction in systolic BP. These findings need to be tested in long-term trials and in individuals at greater cardiovascular risk.

  18. Reducing biogenic-amine-producing bacteria, decarboxylase activity, and biogenic amines in raw milk cheese by high-pressure treatments.

    PubMed

    Calzada, Javier; del Olmo, Ana; Picón, Antonia; Gaya, Pilar; Nuñez, Manuel

    2013-02-01

    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.

  19. 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

  20. 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

  1. 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.

  2. 21 CFR 131.130 - Evaporated milk.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 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. Selective epitaxial silicon growth in the 650-1100 °C range in a reduced pressure chemical vapor deposition reactor using dichlorosilane

    NASA Astrophysics Data System (ADS)

    Regolini, J. L.; Bensahel, D.; Scheid, E.; Mercier, J.

    1989-02-01

    Selective epitaxial silicon layers have been grown in a reduced pressure (<2 Torr) reactor in the 650-1100 °C temperature range using only dichlorosilane (DCS) gas diluted in hydrogen. The growth rate plotted in Arrhenius coordinates (log G vs 1/T) shows an activation energy of 59 kcal/mol in the 650-800 °C range. A comparison is made between the DCS system and our previous results concerning the SiH4/HCl/H2 system.

  4. 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.

  5. 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.

  6. 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 l 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.

  7. 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.

  8. Evaporation of water droplets on soft patterned surfaces.

    PubMed

    Chuang, Yu-Chen; Chu, Che-Kang; Lin, Shih-Yao; Chen, Li-Jen

    2014-05-21

    The evaporation process of a sessile drop of water on soft patterned polydimethylsiloxane (PDMS) substrates is investigated in this study. Different softness of a regular pillar-like patterned PDMS substrate can be achieved by controlling the mixing ratio of a PDMS's prepolymer base and a curing agent at 10 : 1, 20 : 1 and 30 : 1. The receding contact angle is smaller for softer pillar-like patterned substrates. Consequently, the evaporation rate is faster on softer pillar-like substrates. A sessile drop on the regular pillar-like PDMS substrates, prepared at the mixing ratio of a base to a curing agent of 10 : 1 and 20 : 1, is observed to start evaporating in the constant contact radius (CCR) mode then switching to the constant contact angle (CCA) mode via stepwise jumping of the contact line, and finally shifting to the mixed mode sequentially. During the evaporation, a wetting transition from the Cassie to the Wenzel state occurs earlier for the softer substrate because softer pillars relatively cannot stand the increasingly high Laplace pressure. For the softest regular pillar-like PDMS substrate prepared at the mixing ratio of the base to the curing agent of 30 : 1 (abbreviated by PDMS-30 : 1 substrate), the pillars collapse irreversibly after the sessile drop exhibits the wetting transition into the Wenzel state. Furthermore, it is interesting to find out that the initial stage of evaporation of a sessile drop on the PDMS-30 : 1 substrate in the Cassie state is in the CCR mode followed by the CCA mode with stepwise retreatment of the contact line. Further evaporation would induce the wetting transition from the Cassie to the Wenzel state (due to the collapse of pillars) and resume the CCR mode followed by the CCA mode again sequentially.

  9. 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